JP4745700B2 - Cylinder member molding method, cylinder member molding die, and cylinder member - Google Patents

Description

  The present invention relates to a cylindrical member molding method, a cylindrical member molding die, and a cylindrical member used when, for example, a cylindrical spring for a piezoelectric actuator, a lock holder for a steering lock mechanism, or the like is manufactured.

Patent Documents 1 and 2 introduce a method of producing a cylindrical member by bending a plate material using a plurality of sets of press dies. When producing a cylindrical member from a plate material, springback becomes a problem. That is, at the time of press molding, even if the shape of the cylindrical member is given to the plate material by clamping, the both ends of the plate material in the rounding direction are opened by the amount of elastic strain after the mold is opened. For this reason, the cylindrical member is produced by welding the both ends of a rounding direction after mold opening.
JP 2003-154411 A JP 9-253751 A Japanese Patent Laid-Open No. 10-244318

  However, if both ends in the rounding direction are welded together, the number of steps increases accordingly. For this reason, the manufacturing cost of a cylindrical member becomes high. In addition, welding marks remain on the completed cylindrical member. For this reason, it looks bad. Further, in the case of welding, it is conceivable that a part of the welded part is peeled off, so that it is difficult to ensure a uniform joining force over the entire welded part. In other words, the joining force of the welded portion tends to vary.

  In view of this point, Patent Document 3 introduces a method of manufacturing a cylindrical member from a pre-rounded product using three divided dies and a cored bar. According to the production method described in the document, a sufficient butt load can be secured when the end portions in the rounding direction of the pre-rounded product are butted together. For this reason, both ends of a rounding direction can be joined without a welding process.

  However, in the case of the production method described in the same document, a special mold such as the three divided molds and the cored bar is required. For this reason, equipment cost and by extension, the manufacturing cost of a cylindrical member become high. In addition, the production method described in the document lacks versatility.

  The cylindrical member molding method, the cylindrical member molding die, and the cylindrical member of the present invention have been completed in view of the above problems. Therefore, an object of the present invention is to provide a cylindrical member forming method that is low in manufacturing cost of the cylindrical member and rich in versatility. Another object of the present invention is to provide a cylindrical member mold having a high versatility. Another object of the present invention is to provide a cylindrical member that has high dimensional accuracy, good appearance, and that hardly causes variation in the bonding force between the circumferential end surfaces.

(1) In order to solve the above-mentioned problem, the cylindrical member molding method of the present invention is a cylindrical member molding method for producing a cylindrical member from a plate material, and by bending the plate material, the inner diameter side end surface is set at the tip. An inner diameter side end portion, and an outer diameter side end portion having an outer diameter side end surface arranged at an outer diameter side than the inner diameter side end surface at the tip, the inner diameter side end portion and the outer diameter side end portion Between the inner diameter side end surface and the outer diameter side end surface, a workpiece manufacturing step for manufacturing a substantially cylindrical workpiece that secures an interference allowance that is expressed when trying to arrange on the same diameter, and the inner diameter side end The inner diameter side end surface is brought into sliding contact with the inner diameter side end portion by deforming at least one of the outer diameter side end portion and the outer diameter side end portion so as to consume the interference allowance . and abutting the outer diameter end,-out based on the consumption of the interference margin, by utilizing the spring-back force acting in the circumferential direction , Joining the said inner diameter side end face and the outer diameter end, and having both end surfaces joining step of producing a tubular of the tubular member.

  Here, the “plate material” includes not only a flat plate but also a deformed plate that has been bent to some extent. Further, the “cylindrical member” includes those having the same diameter over the entire length in the cylinder axis direction, and those having a diameter difference in the cylinder axis direction (for example, tapered ones).

  The cylindrical member molding method of the present invention includes a workpiece manufacturing step and a both end surface joining step. In the work production process, a substantially cylindrical work is produced. An end on the inner diameter side is formed at one end in the circumferential direction of the workpiece. On the other hand, an outer diameter side end is formed at the other circumferential end of the workpiece. The inner diameter side end surface arranged at the tip of the inner diameter side end portion and the outer diameter side end surface arranged at the tip of the outer diameter side end portion are arranged offset in the radial direction. The radial direction means a direction perpendicular to the cylinder axis when the workpiece or the cylinder member has a shape other than a circle. An interference margin is secured between the inner diameter side end and the outer diameter side end. The interference margin appears when an inner diameter side end surface and an outer diameter side end surface are arranged on substantially the same diameter. Here, even if a gap is formed between the inner diameter side end portion and the outer diameter side end portion of the workpiece, it is possible to contact both end portions by deforming at least one of the both end portions in the radial direction. If so, the interference is expressed.

  Here, the contact is, for example, any one of the outer peripheral surface of the inner diameter side end, the inner diameter side end surface, the boundary between the outer peripheral surface and the inner diameter side end surface, the inner peripheral surface of the outer diameter side end, and the outer diameter. This refers to a case where any one of the side end surfaces and the boundary between the inner peripheral surface and the outer diameter side end surface is in contact.

  In the both end surface joining step, a cylindrical member, which is an object, is produced from the workpiece. Specifically, the inner diameter side end face and the outer diameter side end face that are arranged so as to be shifted from each other in the radial direction are abutted against each other. As described above, an interference margin is secured between the inner diameter side end and the outer diameter side end. Therefore, in this step, at least one of the inner diameter side end face and the outer diameter side end face is pushed in the radial direction and the circumferential direction in accordance with the shape of the target cylindrical member by the amount of interference. Become. By this pushing operation, the inner diameter side end face and the outer diameter side end face are abutted in the circumferential direction. A springback force is generated between the inner diameter side end face and the outer diameter side end face in a direction in which the end faces are brought closer to each other by the amount of interference. This springback force ensures the end surfaces are joined together.

  According to the cylindrical member molding method of the present invention, it is not always necessary to use a special molding die (of course, a molding die suitable for realizing the cylindrical member molding method of the present invention may be used. (It will be described later.) For this reason, various molding machines conventionally used for producing cylindrical members (for example, a progressive press mold or a single shot mold of a general-purpose press molding machine) can be used as they are (or appropriately added to the molding machine). . Therefore, the cylindrical member forming method of the present invention is rich in versatility. In addition, the manufacturing cost of the cylindrical member is reduced by the amount that the conventional molding machine can be used.

  Moreover, according to the cylindrical member molding method of the present invention, it is not necessary to set a welding process for welding the both end faces again after the both end face joining process. Also in this respect, the manufacturing cost of the cylindrical member can be reduced. In addition, the number of processes can be reduced by the amount unnecessary for the welding process.

  Preferably, in the both end face joining step, it is better that the outer peripheral surface of the inner diameter side end portion and the inner peripheral surface of the outer diameter side end portion do not slide. If it carries out like this, butting of an inner diameter side end surface and an outer diameter side end surface will become easy.

  Preferably, the Vickers hardness of the plate material is better than Hv100. The reason why the Hv is 100 or more is that when the Hv is less than 100, it is difficult to obtain a springback force sufficient to join the inner diameter side end face and the outer diameter side end face. Preferably, the plate material has a Vickers hardness of Hv500 or less. The reason why the Hv is 500 or less is that when it exceeds Hv500, the workability during bending is extremely deteriorated. More preferably, the plate material has a Vickers hardness of Hv300 or less. The reason why the Hv is 300 or less is that when it exceeds Hv300, workability at the time of bending is deteriorated.

  Preferably, the plate material is a spring material. Examples of the spring material include polished special steel plates (S60C, SK5), stainless steel plates (SUS300 series, 600 series), and the like. When the cylindrical member forming method of the present invention is used for a spring material, a cylindrical spring with high dimensional accuracy can be produced from a spring material that is relatively difficult to process.

  More preferably, the spring material is a high hardness spring material. Examples of the high hardness spring material include heat-resistant alloy steel plates (maraging, Inconel, etc.). When the cylindrical member molding method of the present invention is used for a high hardness spring material, a cylindrical spring with high dimensional accuracy can be produced from a high hardness spring material that is particularly difficult to bend.

  (2) Preferably, the plate member has one end portion and the other end portion opposite to the one end portion, and the work making step performs a round bending process on a portion excluding the one end portion of the plate member. Therefore, it is better to have a configuration in which the outer diameter side end portion is formed from the one end portion and the inner diameter side end portion is formed from the other end portion.

  That is, this structure arrange | positions an end part relatively to an outer-diameter side with respect to the other end part by giving a round bending process to a board | plate material, leaving an end part. According to this configuration, it is not necessary to deform one end portion during workpiece fabrication. For this reason, the outer diameter side end and the inner diameter side end can be formed relatively easily. Further, at the time of round bending, one end and the other end are unlikely to interfere with each other.

  (3) Preferably, in the configuration of the above (2), the ratio L / t between the circumferential length L and the wall thickness t of the outer diameter side end is set to 7 or more. Good. The reason why L / t is 7 or more is that when it is less than 7, the springback force when the inner diameter side end face and the outer diameter side end face are brought into contact with each other becomes small.

  The ratio L / t between the circumferential length L of the outer diameter side end and the wall thickness t is preferably set to 13 or less. When L / t is set to 13 or less, when 13 is exceeded, the positional deviation in the radial direction between the one end and the other end increases, and the outer diameter side end face and the inner diameter side end face are abutted in the both end face joining step. This is because it becomes difficult.

  (4) Preferably, the plate member has one end portion and the other end portion opposed to the one end portion, and the workpiece manufacturing step includes the one end portion and a portion excluding the one end portion of the plate member, The outer diameter side end portion is formed from the one end portion and the inner diameter side end portion is formed from the other end portion. Better. According to this configuration, one end and the other end are unlikely to interfere during round bending. Further, in the both end face joining step, the outer diameter side end face and the inner diameter side end face can be easily butted.

  Preferably, the plate member has one end portion and the other end portion opposed to the one end portion, and the workpiece manufacturing step includes the other end portion and a portion excluding the other end portion of the plate member. , The inner diameter side end portion is formed from the other end portion having a large curvature, and the outer diameter side is formed from the one end portion having a smaller curvature than the other end portion. It is better to have a configuration that is a round bending step for forming an end portion.

  In the case of this configuration, in the both end face joining step, the inner diameter side end face is abutted against the outer diameter side end face by deforming the inner diameter side end portion having a large curvature in the outer diameter direction. According to this configuration, one end and the other end are unlikely to interfere during round bending.

  (5) Preferably, before the both end surface joining step, a chamfered portion is provided on at least one of the outer peripheral surface of the tip end of the inner diameter side end portion and the inner peripheral surface of the tip end of the outer diameter side end portion. It is better to have a configuration having a chamfering step for arranging the.

  According to this configuration, the outer diameter side end face and the inner diameter side end face can be easily matched in the both end face joining step. The chamfering process may be performed immediately before the both end face joining process. Moreover, you may implement before a workpiece | work preparation process. Or you may implement during a workpiece | work preparation process.

  Preferably, the chamfered portion is planar. If it carries out like this, a chamfer part can be formed easily. Preferably, the chamfered portion is curved. If it carries out like this, the contact area at the time of a chamfering part slidingly contacting the edge part (outer diameter side edge part or inner diameter side edge part) of the other party can be made small. For this reason, the frictional force at the time of sliding contact becomes small.

(6) Preferably, in the both end face joining step, the inner diameter side end face and the outer diameter side are applied to at least one of the inner diameter side end part and the outer diameter side end part from the radial direction. The both end surface reversing step for reversing the radial positional relationship with the end surface, and the spring back acting in the radial direction generated by removing the load , the inner diameter side end portion and the end surface after the both end surface reversing step are utilized. A method comprising a both-ends face-butting step of consuming the overlapping overlap margin secured between the outer-diameter side end part and the inner-diameter side end face with the outer-diameter side end face. Is good.

  The both end face joining step of this configuration includes a both end face reversing step and a both end face butting step. In the both end face reversing step, the relative positional relationship in the radial direction between the inner diameter side end face and the outer diameter side end face is changed by applying a load. Specifically, the outer diameter side end face is moved relative to the inner diameter side of the inner diameter side end face, in other words, the inner diameter side end face is moved relative to the outer diameter side of the outer diameter side end face.

  In the both end face butting step, the load applied during the both end face reversing step is removed. By removing the load, the end (at least one of the inner diameter side end and the outer diameter side edge) to which the load is applied is radiated in the radial direction (in the case of the inner diameter side end, the inner diameter direction, the outer diameter). In the case of the side end portion, it is elastically deformed in the outer diameter direction). In other words, the inner diameter side end surface and the outer diameter side end surface approach each other by the springback. In this step, the inner diameter side end face and the outer diameter side end face are brought into contact with each other by using the spring back as described above. According to this configuration, the inner diameter side end face and the outer diameter side end face can be joined relatively easily.

  (7) Preferably, in the configuration of (6) above, after the both end surface reversing step, a center angle of the work is 1 ° or more between the outer diameter side end portion and the inner diameter side end portion in the circumferential direction. It is better to have a configuration in which overlapping overlaps are secured. The reason why the overlap margin is set to 1 ° or more is that when it is less than 1 °, it is difficult to secure a desired springback force after the both-ends butting process.

  Preferably, in the configuration of (6) above, after the both end surface reversing step, between the outer diameter side end portion and the inner diameter side end portion, the workpiece has a central angle of 4 ° or less in the circumferential direction. It is better to have a configuration in which overlapping overlap margins are secured. The reason why the overlap margin is set to 4 ° or less is that when the angle exceeds 4 °, the radial positional relationship between the inner diameter side end surface and the outer diameter side end surface is difficult to reverse in the both end surface reversing step.

(8) Moreover, in order to solve the said subject, the cylindrical member shaping | molding die of this invention is used for the said both end surface inversion process of the structure of said (6), The inner diameter side edge part which has an inner diameter side end surface at a front-end | tip, An outer diameter side end portion having an outer diameter side end surface disposed at an outer end side than the inner diameter side end surface, and the inner diameter side portion between the inner diameter side end portion and the outer diameter side end portion. A cylindrical member molding die for producing a cylindrical cylindrical member from a substantially cylindrical workpiece that secures an interference margin that appears when the side end surface and the outer diameter side end surface are arranged on substantially the same diameter. When tightening, the outer diameter side end surface is provided side by side with the outer peripheral surface convex portion that consumes the interference allowance and pushes the inner diameter side end surface further to the inner diameter side, and the outer peripheral surface convex portion. And an outer peripheral surface molding die having an outer peripheral surface concave portion that suppresses the inner diameter side end surface from being pushed into the inner diameter side together with the outer diameter side end surface. To.

  The cylindrical member molding die of the present invention includes an outer peripheral surface molding die. The outer peripheral surface mold includes an outer peripheral surface convex portion and an outer peripheral surface concave portion. The outer peripheral surface concave portion is recessed toward the workpiece outer diameter side with respect to the outer peripheral surface convex portion.

  At the time of clamping, the outer peripheral surface convex portion pushes the outer diameter side end of the work in the inner diameter direction. And the recessed part for outer peripheral surfaces suppresses that an inner diameter side edge part is pushed in with an outer diameter side edge part. When the mold is opened, the outer diameter side end is elastically deformed in the outer diameter direction by the springback. And an inner diameter side end surface and an outer diameter side end surface contact | abut.

  According to the cylindrical member forming die of the present invention, the radial positional relationship between the outer diameter side end face and the inner diameter side end face can be interchanged relatively easily. As a result, the outer diameter side end face and the inner diameter side end face can be abutted relatively easily. In addition, the cylindrical member molding die of the present invention is easily added to a conventional molding machine (for example, a progressive feed mold, a single shot mold of a general-purpose press molding machine). That is, the conventional molding machine can be used as it is by replacing the outer peripheral surface molding die of the conventional molding machine with the cylindrical member molding die of the present invention. For this reason, the cylindrical member shaping | molding die of this invention is rich in versatility. As described above, the cylindrical member molding method of the present invention can of course be carried out using a general molding die other than the cylindrical member molding die of the present invention.

  (9) Preferably, in the configuration of (8) above, the inner peripheral surface concave portion into which the outer diameter side end surface pushed in by the outer peripheral surface convex portion enters when the mold is clamped, and the inner peripheral surface For the inner peripheral surface that is arranged in parallel with the concave portion for use and suppresses the inner peripheral side end surface from being pushed into the concave portion for the inner peripheral surface together with the outer peripheral surface concave portion at the time of clamping. It is better to have a configuration including an inner peripheral surface mold having a convex portion.

  The cylinder member mold of this configuration includes an outer peripheral surface mold and an inner peripheral surface mold. The inner peripheral surface mold includes an inner peripheral surface concave portion and an inner peripheral surface convex portion. The inner peripheral surface convex portion protrudes toward the workpiece outer diameter side with respect to the inner peripheral surface concave portion.

  During mold clamping, the outer diameter side end surface pushed by the outer peripheral surface convex portion escapes into the inner peripheral surface concave portion. The inner peripheral surface convex portion cooperates with the outer peripheral surface concave portion to prevent the inner diameter side end surface from escaping into the inner peripheral surface concave portion together with the outer diameter side end surface.

  According to this configuration, the radial positional relationship between the outer diameter side end face and the inner diameter side end face can be more reliably interchanged. As a result, the outer diameter side end face and the inner diameter side end face can be brought into contact with each other more reliably. In addition, this configuration is easy to add-on to a conventional molding machine (for example, a progressive press mold or a single shot mold of a general-purpose press molding machine). That is, by replacing the outer peripheral surface mold of the conventional molding machine with the outer peripheral surface mold of this configuration and the inner peripheral surface mold of the conventional molding machine with the inner peripheral surface mold of this configuration, The molding machine can be used as it is. For this reason, this structure is rich in versatility.

(10) In order to solve the above problems, the tubular member of the present invention, the circumferential and direction end portion, the circular cylinder formed by and a bonded circumferential direction end portions in the circumferential direction in the circumferential direction end portions The end surface of the one end in the circumferential direction and the end surface of the other end in the circumferential direction are joined using a springback force acting in the circumferential direction . A chamfered portion is formed on at least one of the outer peripheral surface of the tip and the inner peripheral surface of the tip of the other end in the circumferential direction.

  The end surface of one end portion in the circumferential direction and the end surface of the other end portion in the circumferential direction of the cylindrical member of the present invention are joined using a springback force. For this reason, a welding trace does not appear in the boundary of the circumferential direction both end surfaces (the end surface of the circumferential direction one end part and the end surface of the circumferential direction other end part). Therefore, the cylindrical member of the present invention has a good appearance. Moreover, since there is no welding mark, the dimensional accuracy is high.

  Further, as described above, when both end faces are joined by welding, the joining force tends to vary. In this regard, according to the cylindrical member of the present invention, both end surfaces in the circumferential direction are joined using the springback force. For this reason, it is hard to produce dispersion | variation in the joining force of the circumferential direction both end surfaces.

  Preferably, the cylindrical member is a cylindrical spring in which a load is applied in the axial direction and a plurality of holes are arranged on the side peripheral wall. The cylindrical spring is produced, for example, by subjecting a plate material, in which holes have been previously opened, to round bending. Depending on the cutting condition of the plate material, a hole partially cut away by cutting may appear on the end face of one end in the circumferential direction or the end face of the other end in the circumferential direction. The hole has a C-shape opening at the end face.

  Here, when both end surfaces are joined by welding, when the weld between the C-shaped opening end of the hole and the end surface on the other side peels off, the C-shaped opening end is caused by the axial load applied to the cylindrical spring. Slide so as to scratch the end face. For this reason, stress tends to concentrate near the C-shaped opening end.

  In this regard, when the cylindrical member of the present invention is embodied as the cylindrical spring, even if the C-shaped opening end of the hole appears on the end surface, the C-shaped opening end is formed on the other end surface by the springback force. Always pressed. For this reason, it is difficult for stress to concentrate near the C-shaped opening end.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing cost of a cylindrical member is low, and the cylindrical member shaping | molding method rich in versatility can be provided. In addition, according to the present invention, it is possible to provide a cylindrical member molding die having a high versatility. In addition, according to the present invention, it is possible to provide a cylindrical member that has high dimensional accuracy, good appearance, and that hardly causes variation in the bonding force between the circumferential end surfaces.

  Hereinafter, embodiments of the cylindrical member molding method, the cylindrical member molding die, and the cylindrical member of the present invention will be described.

  <First embodiment>

  In the present embodiment, the cylindrical member forming method of the present invention is used for manufacturing a cylindrical spring for a piezoelectric actuator. First, the configuration of the cylindrical member forming method of the present embodiment will be described. The cylindrical member forming method of the present embodiment includes a plate material manufacturing process, a surface pressing process, a one end unprocessed process, a both end face reversing process, and a both end face butting process. The chamfering process is included in the chamfering process of the present invention. Hereinafter, each process will be described in detail.

  First, the plate material manufacturing process will be described. In this step, a plate material is produced from the strip material. First, a large number of rectangular holes are formed in a predetermined pattern in a strip made of maraging steel. The strip is then sheared to a predetermined dimension. In this way, a plate material is created.

  Next, the surface pressing process will be described. In this step, chamfered portions are formed at a pair of opposed end portions of the plate material. In FIG. 1, the perspective view of the board | plate material after this process is shown. FIG. 2 shows an enlarged view in the circle Ia of FIG. FIG. 3 shows an enlarged transmission diagram in the circle Ib of FIG.

  As shown in FIG. 1, the plate member 2 has a thin rectangular flat plate shape. A large number of rectangular holes 20 are regularly arranged in the plate member 2. As shown in FIG. 2, a flat chamfered portion 22 (hatched for convenience of explanation) is formed on the top end surface of the one end portion 21 of the plate member 2. As shown in FIG. 3, a planar chamfered portion 24 (hatched for convenience of explanation) is formed on the lower surface of the front end of the other end portion 23 (shown transparent for convenience of explanation) of the plate member 2. That is, the chamfered portion 22 and the chamfered portion 24 are disposed diagonally in the longitudinal section of the plate member 2.

  FIG. 4 shows a cross-sectional view (clamping state) of a mold used for forming a chamfered portion at one end in the surface pressing step. As shown in the figure, the mold 25a includes a steel punch 250a and a steel die 251a. The mold surface of the punch 250a has a surface shape that is symmetrical to the chamfered portion 22 and the mold. The one end 21 is pressed by a vertically moving punch 250a. By this pressing, a planar chamfered portion 22 is formed on the top end surface of the one end portion 21.

  FIG. 5 shows a cross-sectional view (clamped state) of a mold used for forming a chamfered portion at the other end in the surface pressing step. As shown in the figure, the mold 25b includes a steel punch 250b and a steel die 251b. The die surface of the die 251b has a surface shape symmetrical to the chamfered portion 24. The other end 23 is pressed by a vertically moving punch 250b. By this pressing, a planar chamfer 24 is formed on the lower surface of the tip of the other end 23.

  Next, the one end unprocessed step will be described. In this step, a total of five stages of round bending including the first stage to the fifth stage is performed on the portion other than the one end 21 of the plate member 2 to produce a substantially cylindrical workpiece.

  In the first stage, a small curvature is applied only to the other end 23. FIG. 6 shows a cross-sectional view of a mold used in the first stage of this process. As shown in the figure, the mold 3a includes a steel punch 30a and a steel die 31a. The plate material 2 is interposed between the punch 30a and the die 31a. Clamping is performed by the punch 30a being pressed against the die 31a. By clamping, the other end portion 23 of the plate member 2 is bent with a curvature larger than a desired curvature.

  In the second stage, the other end portion 23 is given a larger curvature than that in the first stage. In addition, the same curvature as that of the first stage is also given to the root of the one end 21. FIG. 7 shows a cross-sectional view of a mold used in the second stage of this process. As shown in the figure, the mold 3b includes a steel punch 30b and a steel die 31b. By clamping the mold, the other end portion 23 of the plate member 2 is bent with a larger curvature than the first stage. In addition, the root of the one end portion 21 is also bent. However, the one end 21 itself remains flat.

  In the third stage, the same curvature as that in the first stage is also applied to portions other than the other end 23 excluding the one end 21. FIG. 8 shows a cross-sectional view of a mold used in the third stage of this process. As shown in the figure, the mold 3c includes a steel punch 30c and a steel die 31c. The punch 30 c is inserted into and removed from the inner diameter side of the plate member 2 through the gap between the one end portion 21 and the other end portion 23. In the third stage, bending is also applied to the portion other than the other end 23 of the plate member 2. However, the one end 21 itself remains flat.

  In the fourth stage, bending is mainly performed mainly on the one end 21 side of the plate member 2. First, the configuration of the molding machine used at this stage will be described. FIG. 9 shows a cross-sectional view at the top dead center position of the molding machine used in the fourth stage of this process. As shown in the figure, the molding machine 4 includes an upper mold holder 40 and a lower mold holder 41. At the top dead center position, the upper mold holder 40 and the lower mold holder 41 are arranged to face each other in the vertical direction with a predetermined distance therebetween. The upper mold holder 40 is movable in the vertical direction between the top dead center position and the bottom dead center position.

  The upper mold holder 40 includes an upper mold base 400 and a pair of cam drivers 401a and 401b. The cam drivers 401a and 401b are made of steel and have a plate shape. The cam drivers 401a and 401b are arranged to face each other in the horizontal direction. A driving surface 402a is formed in a flat shape inside the lower end portion of the cam driver 401a. A U-shaped groove 403a that opens downward is formed at the lower end of the cam driver 401a. Similarly, a drive surface 402b is formed in a flat shape inside the lower end of the cam driver 401b. A U-shaped groove 403b that opens downward is formed at the lower end of the cam driver 401b.

  The upper mold base 400 is made of steel and has a rectangular parallelepiped shape. The upper mold base 400 is disposed so as to bridge between the pair of cam drivers 401a and 401b. The upper mold base 400 and the pair of cam drivers 401 a and 401 b are fixed by four bolts 404.

  The lower mold holder 41 includes a lower mold base 410, a support base 411, a pair of backup plates 412a and 412b, a pair of cam slides 413a and 413b, a pair of shafts 414a and 414b, and a pair of return springs 415a and 415b. And a cored bar 416.

  The lower mold base 410 is made of steel and has a plate shape. The support base 411 is made of steel and has a rectangular parallelepiped shape. The support base 411 is mounted at the center of the upper surface of the lower mold base 410. A support rib 417 protrudes from the center of the upper surface of the support base 411.

  The cored bar 416 is made of steel and has a cylindrical shape. On the outer peripheral surface of the cored bar 416, a step extending in the axial direction is formed. The metal core 416 is provided with the plate material 2 that has undergone the third stage. The core metal 416 and the plate material 2 are mounted on the support rib 417.

  The backup plates 412a and 412b are made of steel and have a plate shape. The backup plates 412a and 412b are mounted on the upper surface of the lower base 410, like the support base 411. In addition, the backup plates 412 a and 412 b are disposed on both sides of the support base 411 in the horizontal direction. The backup plates 412a and 412b and the support base 411 are fixed by two bolts 418. A shaft insertion hole 419a extending in the horizontal direction is formed in the backup plate 412a. Similarly, a shaft insertion hole 419b extending in the horizontal direction is formed in the backup plate 412b.

  The shafts 414a and 414b are made of steel and have a long-axis bolt shape. The shaft 414a is inserted into the shaft insertion hole 419a from the outside in the horizontal direction toward the inside. The insertion direction end of the shaft 414a protrudes from the shaft insertion hole 419a. Similarly, the shaft 414b is inserted into the shaft insertion hole 419b from the outside in the horizontal direction toward the inside. The insertion direction end of the shaft 414b protrudes from the shaft insertion hole 419b.

  The cam slide 413a is made of steel and has a rectangular parallelepiped shape. The cam slide 413a is screwed to the insertion direction end of the shaft 414a. A follower surface 420a is formed on the upper end of the horizontal outer surface of the cam slide 413a. The driven surface 420a faces the drive surface 402a in the up-down direction. On the other hand, a mold surface 421a is formed on the inner surface in the horizontal direction of the cam slide 413a. Similarly, the cam slide 413b is made of steel and has a rectangular parallelepiped shape. The cam slide 413b is screwed to the end of the shaft 414b in the insertion direction. A follower surface 420b is formed on the upper end portion of the outer surface in the horizontal direction of the cam slide 413b. The driven surface 420b faces the drive surface 402b in the up-down direction. On the other hand, a mold surface 421b is formed on the inner surface in the horizontal direction of the cam slide 413b. The mold surface 421a and the mold surface 421b are disposed opposite to each other on both sides in the horizontal direction with the plate member 2 interposed therebetween.

  The return spring 415a is made of steel and has a coil shape. The return spring 415a is mounted on the shaft 414a. The return spring 415a is disposed between the head of the shaft 414a and the backup plate 412a. The return spring 415a biases the cam slide 413a outward in the horizontal direction. Similarly, the return spring 415b is made of steel and has a coil shape. The return spring 415b is mounted on the shaft 414b. The return spring 415b is disposed between the head of the shaft 414b and the backup plate 412b. The return spring 415b biases the cam slide 413b outward in the horizontal direction.

  Next, the movement of the molding machine used at this stage will be described. FIG. 10 shows a cross-sectional view of the molding machine used in the fourth stage of this process during the transition from the top dead center position to the bottom dead center position. As shown in the figure, when the upper mold holder 40 is lowered, the driving surface 402a and the driven surface 420a are in sliding contact. In addition, the driving surface 402b and the driven surface 420b are in sliding contact. By the sliding contact, the direction of the load applied to the upper mold holder 40 is converted from the lower direction to the inner side in the horizontal direction. For this reason, the cam slide 413a moves inward in the horizontal direction against the biasing force of the return spring 415a. As the cam driver 401a is lowered, the base portion of the cam slide 413a of the shaft 414a is gradually accommodated in the U-shaped groove 403a. Similarly, the cam slide 413b moves inward in the horizontal direction against the urging force of the return spring 415b. As the cam driver 401b is lowered, the base portion of the cam slide 413b of the shaft 414b is gradually accommodated in the U-shaped groove 403b.

  FIG. 11 is a cross-sectional view at the bottom dead center position of the molding machine used in the fourth stage of this process. As shown in the drawing, at the bottom dead center position, the plate member 2 is pressed by the mold surfaces 421a and 421b from the left and right sides in the horizontal direction. In this way, mold clamping is performed.

  FIG. 12 shows an enlarged view in the circle XI of FIG. In the figure, the thin line indicates the shape of the plate material 2 before clamping. As shown in the figure, the one end 21 side (left side) of the plate member 2 is sandwiched between the mold surface 421a and the cored bar 416. In addition, the other end 23 side (right side) of the plate member 2 is sandwiched between the mold surface 421b and the cored bar 416. Here, the radius of the cored bar 416 is set such that the left side is small and the right side is large, with the step 416a as a boundary. The same curvature as the first stage is given to the one end 21 side of the plate 2. Thus, in this stage, further bending processing is performed mainly on the one end 21 side of the plate member 2 (excluding the one end 21).

  Returning to FIG. 11, after the mold clamping, the upper mold holder 40 rises and returns to the top dead center position shown in FIG. 9 through the transition state shown in FIG. 10. At this time, the cam slide 413a moves outward in the horizontal direction by the biasing force of the return spring 415a. In addition, the cam slide 413b moves outward in the horizontal direction by the biasing force of the return spring 415b. In this way, mold opening is performed.

  In the fifth stage, mainly bending is performed on the other end 23 side of the plate 2. The only difference between the molding machine used in the fifth stage and the molding machine used in the fourth stage is the shape of the cored bar and the shape of the cam slide. Therefore, only the differences will be described here.

  FIG. 13 shows a cross-sectional view at the bottom dead center position of the molding machine used in the fifth stage of this process (the top dead center position and the state during the transition from the top dead center to the bottom dead center are shown in FIG. See FIG. In addition, about the site | part corresponding to FIG. 11, it shows with the same code | symbol.

  As shown in the figure, at the bottom dead center position, the plate member 2 is pressed by the mold surface 521a of the cam slide 513a and the mold surface 521b of the cam slide 513b from the left and right sides in the horizontal direction. In this way, mold clamping is performed.

  FIG. 14 shows an enlarged view in a circle XIII in FIG. In the figure, the thin line indicates the shape of the plate material 2 before clamping. As shown in the figure, the one end 21 side (left side) of the plate member 2 is sandwiched between the mold surface 521a and the cored bar 516. In addition, the other end 23 side (right side) of the plate member 2 is sandwiched between the mold surface 521b and the cored bar 516. Here, the radius of the cored bar 516 is set such that the left side is large and the right side is small with respect to the step 516a. The same curvature as the one end 21 side is given to the other end 23 side of the plate member 2. Thus, in this stage, further bending is performed mainly on the other end 23 side of the plate member 2. After mold clamping, mold opening is performed by the same movement as in the fourth stage. Thus, the one-end unprocessed process including the first to fifth stages is completed, and the workpiece is completed.

  Next, the both end face reversal process will be described. In this step, the radial positional relationship between the outer diameter side end surface of the outer diameter side end portion of the workpiece and the inner diameter side end surface of the inner diameter side end portion is reversed. The only difference between the molding machine used in this process and the molding machine used in the fourth stage of the one-end untreated process is the shape of the core bar, the shape of the cam slide, and the shape of the upper mold base. Therefore, only the differences will be described here.

  FIG. 15 shows a cross-sectional view at the top dead center position of the molding machine used in this step. In addition, about the site | part corresponding to FIG. 9, it shows with the same code | symbol. As shown in the figure, a punch 600a protrudes downward from the center of the lower surface of the upper mold base 600. The punch 600a is included in the outer peripheral surface mold of the present invention.

  FIG. 16 shows an enlarged view in a circle XVa in FIG. As shown in the figure, an outer peripheral surface convex portion 600b and an outer peripheral surface concave portion 600c are formed on the lower surface of the punch 600a with a step 600d as a boundary. The outer peripheral surface convex portion 600b protrudes downward from the outer peripheral surface concave portion 600c.

  Returning to FIG. 15, the cam slide 613a is screwed to the shaft 414a. A mold surface 621a is formed on the inner surface in the horizontal direction of the cam slide 613a. Similarly, the cam slide 613b is screwed to the shaft 414b. A mold surface 621b is formed on the inner surface in the horizontal direction of the cam slide 613b.

  A workpiece 7 and a cored bar 616 are interposed between the mold surface 621a and the mold surface 621b. The core metal 616 is made of steel and has a cylindrical shape. The cored bar 616 is included in the inner peripheral surface molding die of the present invention. The workpiece 7 has a substantially cylindrical shape. The workpiece 7 is wrapped around the cored bar 616. The workpiece 7 is supported by the support rib 417 from below.

  FIG. 17 shows an enlarged view in the circle XVb of FIG. FIG. 18 shows an enlarged view in a circle XVII in FIG. As shown in these drawings, an inner peripheral surface convex portion 616b and an inner peripheral surface concave portion 616c are formed on the upper surface of the cored bar 616 with a step 616d extending in the axial direction as a boundary. Note that the step 616d is disposed on the right side of the perpendicular extending right above the cylinder axis O. The inner peripheral surface convex portion 616b is set to have substantially the same diameter as the inner peripheral surface of the target cylindrical spring. The inner peripheral surface convex portion 616b faces the outer peripheral surface concave portion 600c in the vertical direction. The inner peripheral surface concave portion 616c is immersed below the inner peripheral surface convex portion 616b. The inner peripheral surface concave portion 616c faces the outer peripheral surface convex portion 600b in the vertical direction.

  The work 7 includes an outer diameter side end 71 and an inner diameter side end 73. The inner diameter R of the work 7 is set to R = 4.325 mm. As shown in FIG. 14, the outer diameter side end 71 is formed from one end 21 of the plate 2. In addition, the inner diameter side end portion 73 is formed from the other end portion 23 of the plate member 2.

  The outer diameter side end 71 has a flat plate shape. A chamfered portion 72 is disposed on the inner peripheral surface of the outer diameter side end portion 71. As shown in FIG. 2, the chamfered portion 72 is formed from the chamfered portion 22. Further, an outer diameter side end surface 75 that is bent and connected to the chamfered portion 72 is disposed at the tip of the outer diameter side end portion 71. The ratio L / t between the circumferential length L (= 4.358 mm) of the outer diameter side end 71 and the wall thickness t (= 0.42 mm) is set to L / t = about 10.376. Yes.

  The inner diameter side end 73 has a curved plate shape. A chamfered portion 74 is disposed on the outer peripheral surface of the inner diameter side end portion 73. As shown in FIG. 3, the chamfered portion 74 is formed from the chamfered portion 24. Further, an inner diameter side end surface 76 that is bent and connected to the chamfered portion 74 is disposed at the tip of the inner diameter side end portion 73. The inner diameter side end face 76 is disposed at substantially the same position with respect to a perpendicular extending right above the cylinder axis O. That is, the inner diameter side end face 76 protrudes leftward from the step 616d.

  By the way, if the outer diameter side end portion 71 of the workpiece 7 is deformed in the inner diameter direction, the chamfered portion 72 and the chamfered portion 74 come into contact with each other as shown in a virtual shape 7 ′ (indicated by a dotted line in the drawing). become. That is, between the outer diameter side end 71 and the inner diameter side end 73, an interference margin IF that overlaps in the circumferential direction by a predetermined amount of the center angle of the work 7 (circumferential rotation angle about the cylinder axis O) appears. .

  Returning to FIG. 15, when shifting from the top dead center to the bottom dead center, the upper mold holder 40 is lowered. Further, the cam slide 613a moves inward in the horizontal direction due to the sliding contact between the driving surface 402a and the driven surface 420a. Similarly, the cam slide 613b moves inward in the horizontal direction by the sliding contact between the driving surface 402b and the driven surface 420b. Therefore, the punch 600a approaches the workpiece 7 from above, the cam slide 613a from the left side, and the cam slide 613b from the right side.

  FIG. 19 shows a partially enlarged cross-sectional view immediately before shifting to the bottom dead center position of the molding machine used in this process. FIG. 19 corresponds to FIG. As shown in the drawing, the outer diameter side end portion 71 of the workpiece 7 is pressed downward by the outer peripheral surface convex portion 600b of the punch 600a. For this reason, the outer diameter side end portion 71 is deformed and moved in the inner diameter direction along the shape of the outer peripheral surface convex portion 600b.

  Here, between the outer diameter side end portion 71 and the inner diameter side end portion 73, the interference margin IF shown in FIGS. 17 and 18 is set. For this reason, the chamfered portion 72 of the outer diameter side end portion 71 is in sliding contact with the chamfered portion 74 of the inner diameter side end portion 73. The chamfered portions 72 and 74 are formed so as to be approximately 45 ° with respect to the direction in which the load is applied by the punch 600a (indicated by a white arrow in the figure). For this reason, a component force in the right direction is generated at the inner diameter side end portion 73 through the sliding contact between the chamfered portion 72 and the chamfered portion 74. Therefore, the outer diameter side end 71 moves downward while consuming the interference margin IF and pushing the inner diameter side end 73 in the right direction.

  At this time, due to the frictional force acting between the chamfered portion 72 and the chamfered portion 74, the inner diameter side end portion 73 is also moved downward together with the outer diameter side end portion 71. However, an outer peripheral surface recessed portion 600 c is secured above the inner diameter side end portion 73. In addition, an inner peripheral surface convex portion 616 b is secured below the inner diameter side end portion 73. For this reason, the inner diameter side end portion 73 is separated from the outer diameter side end portion 71 and retracts in a space between the outer peripheral surface concave portion 600c and the inner peripheral surface convex portion 616b.

  FIG. 20 shows a cross-sectional view at the bottom dead center position of the molding machine used in this step. As shown in the figure, at the bottom dead center position, the workpiece 7 is pressed by the mold surfaces 621a and 621b from both the left and right sides in the horizontal direction and by the punch 600a from above. In this way, mold clamping is performed.

  FIG. 21 shows an enlarged view in a circle XX in FIG. As shown in the drawing, the outer diameter side end 71 is sandwiched between the outer peripheral surface convex portion 600b and the inner peripheral surface concave portion 616c. On the other hand, the inner diameter side end portion 73 is retracted in a space between the outer peripheral surface concave portion 600c and the inner peripheral surface convex portion 616b. That is, the outer diameter side end face 75 is pushed further into the inner diameter side of the inner diameter side end face 76. Further, an overlap margin OL that overlaps in the circumferential direction by a center angle of about 2 ° between the outer diameter side end portion 71 and the inner diameter side end portion 73 is secured. The circumferential length of the overlap margin OL is 0.133 mm.

  FIG. 22 shows an enlarged view of the workpiece and the cored bar of FIG. As shown in the figure, the outer diameter side end portion 71 is arranged over the center angle θ of the workpiece 7 of about 57 °. The central angle θ (= about 57 °) is the sum of the central angle α (= 55 °) and the overlap margin OL (= about 2 °). Further, the outer diameter side end portion 71 itself is arranged over a central angle α ′ = 67.25 ° with the arc center O ′ of the outer diameter side end portion 71 as the center. Further, the inner diameter R ′ of the outer diameter side end 71 itself is set to R ′ = 3.5 mm.

  Thus, in this step, the outer diameter side end surface 75 arranged on the outer diameter side of the inner diameter side end surface 76 before this step is moved to the inner diameter side of the inner diameter side end surface 76. That is, the radial positional relationship between the outer diameter side end face 75 and the inner diameter side end face 76 is reversed.

  Next, the both end face butting process will be described. In this step, the outer diameter side end face 75 and the inner diameter side end face 76 are butted together. This step is performed continuously with the previous step. In FIG. 20, when the upper mold holder 40 is raised (when the mold is opened), the punch 600a is also raised. For this reason, the outer diameter side end portion 71 pressed by the outer peripheral surface convex portion 600b at the time of mold clamping is released. Therefore, the outer diameter side end portion 71 moves backward by the spring back by the amount corresponding to the elastic strain. FIG. 23 shows a partially enlarged cross-sectional view at the top dead center position of the molding machine used in this step. FIG. 23 corresponds to FIG. As shown in the drawing, the outer diameter side end portion 71 moves backward to the height of the inner diameter side end portion 73. And the outer diameter side end surface 75 and the inner diameter side end surface 76 are abutted. In this way, the cylindrical spring 1 as the object is completed from the workpiece 7.

  Here, as shown in FIGS. 17 and 18, in the virtual shape 7 ′, the interference margin IF appears between the outer diameter side end face 75 and the inner diameter side end face 76. On the other hand, in the cylindrical spring 1, the interference margin IF is consumed, and the outer diameter side end face 75 and the inner diameter side end face 76 are joined. A springback force acts on the joint portion between the outer diameter side end face 75 and the inner diameter side end face 76 in a direction in which the circumferential length is shortened by the interference margin IF. By this springback force, the outer diameter side end face 75 and the inner diameter side end face 76 are urged in a direction approaching each other.

  FIG. 24 shows a perspective view of the cylindrical spring 1. As shown in the figure, the cylindrical spring 1 has a substantially true cylindrical shape. In the cylindrical spring 1, rectangular holes 10 (corresponding to the rectangular holes 20 of the plate 2) are regularly arranged. Further, a chamfered portion 12 (corresponding to the chamfered portion 72 of the workpiece 7) is formed on the inner peripheral surface of the circumferential end 1 of the cylindrical spring 1 (corresponding to the outer diameter side end portion 71 of the workpiece 7). Further, a chamfered portion 14 (corresponding to the chamfered portion 74 of the workpiece 7) is formed on the outer peripheral surface of the other end 13 in the circumferential direction of the cylindrical spring 1 (corresponding to the inner diameter side end portion 73 of the workpiece 7). The end face 15 (corresponding to the outer diameter side end face 75 of the work 7) and the end face 16 (corresponding to the inner diameter side end face 76 of the work 7) are joined in the circumferential direction by the springback force.

  The cylindrical spring 1 is assembled with the piezo element as follows. First, a plurality of short-axis columnar piezoelectric elements (not shown) are arranged on the inner diameter side of the cylindrical spring 1. The piezo elements are arranged in series along the cylinder axis of the cylindrical spring 1. Here, the axial length of the cylindrical spring 1 is set slightly shorter than the axial length of the piezoelectric element groups arranged in series. In this state, the upper and lower openings of the cylindrical spring 1 are sealed with cup members (not shown). The piezo element group is accommodated on the inner diameter side of the cylindrical spring 1 while being compressed from both axial sides by a pair of cup members (by the biasing force of the cylindrical spring 1). In this way, the piezo actuator is completed.

  The piezo actuator is used as follows. When a voltage is applied to the piezo element group, the axial length of the piezo element group extends against the urging force of the cylindrical spring 1. On the other hand, when the voltage is removed, the axial length of the piezoelectric element group is restored. At this time, the urging force of the cylindrical spring 1 assists the restoration of the piezo element group. Thus, the cylindrical spring 1 assists expansion and contraction of the piezo element group and enhances responsiveness to the drive command.

  Next, the effect of the cylindrical member molding method, the cylindrical member molding die, and the cylindrical member of the present embodiment will be described. According to the cylindrical member molding method of the present embodiment, a conventionally used cam slide type press molding machine can be used as it is. Specifically, for example, cam slides 413a, 413b, 513a, 513b, 613a, 613b, cored bars 416, 516, 616, punch 600a, etc. are appropriately added to the conventional cam slide type press molding machine. Thus, the cylindrical member forming method of this embodiment can be carried out. For this reason, it is rich in versatility. In addition, since the conventional molding machine can be used, the manufacturing cost of the cylindrical spring 1 is reduced.

  Further, according to the cylindrical member forming method of the present embodiment, it is not necessary to set a welding process for welding the end faces 15 and 16 again after the both end face butting process. Also in this respect, the manufacturing cost of the cylindrical spring 1 can be reduced. In addition, the number of processes can be reduced by the amount unnecessary for the welding process.

Further, according to the cylindrical member forming method of the present embodiment, a relatively small interference margin IF as shown in FIG. 18 is set. Therefore, as shown in FIG. 19, the sliding contact distance between the chamfered portion 74 of the inner diameter side end portion 73 and the chamfered portion 72 of the outer diameter side end portion 71 is short in the both end surface reversing step.

  Further, according to the cylindrical member forming method of the present embodiment, as shown in FIG. 21, the overlap margin OL that is overlapped in the circumferential direction by the center angle of about 2 ° is ensured. Therefore, when the inner diameter side end face 76 and the outer diameter side end face 75 are abutted in the both end face abutting step, the inner peripheral face of the inner diameter side end 73 and the outer peripheral face of the outer diameter side end 71 are not easily slidable. . Further, after the both end face butting step, the inner diameter side end face 76 and the outer diameter side end face 75 can be joined by a desired spring back force.

  Moreover, the Vickers hardness of the board | plate material 2 of this embodiment is Hv300-350. For this reason, it is easy to ensure a sufficient spring back force to join the inner diameter side end face 76 and the outer diameter side end face 75.

  Further, although the maraging steel plate 2 is difficult to bend, when the cylindrical member forming method of this embodiment is used, the cylindrical spring 1 having high dimensional accuracy and roundness can be produced. it can.

  Moreover, according to the cylindrical member shaping | molding method of this embodiment, the one end part unprocessed process is implemented as a workpiece | work preparation process. For this reason, it is not necessary to perform a round bending process on the one end portion 21 of the plate member 2. For this reason, the workpiece 7 can be produced relatively easily.

  Further, according to the cylindrical member molding method of the present embodiment, the ratio L / t between the circumferential length L of the outer diameter side end 71 and the wall thickness t is set to L / t = about 10.376. . For this reason, the positional deviation in the radial direction between the outer diameter side end 71 and the inner diameter side end 73 is relatively large. Therefore, at the fourth stage (see FIG. 12) and the fifth stage (see FIG. 14) of the one-end untreated process, the one end 21 and the other end 23 are unlikely to interfere with each other.

  Moreover, according to the cylindrical member shaping | molding method of this embodiment, a surface pressing process is implemented between a board | plate material preparation process and an one end part unprocessed process. When the chamfered portions 72 and 74 are arranged by the surface pressing process, as shown in FIG. 19, the direction of the applied load is changed from the vertical direction to the horizontal direction (circumferential direction of the workpiece 7) in the both end surface reverse process. Easy to convert. For this reason, it becomes easy to immerse the outer diameter side end 71 into the inner peripheral surface recess 616c.

  Moreover, according to the cylindrical member shaping | molding method of this embodiment, the chamfering parts 72 and 74 are exhibiting planar shape. For this reason, the chamfered portions 72 and 74 can be formed relatively easily in the surface pressing step.

  Moreover, the cylindrical member shaping | molding method of this embodiment has implemented the both end surface inversion process and the both end surface butting process as a both end surface joining process. For this reason, as shown in FIGS. 21 and 23, an upward spring back can be caused at the outer diameter side end 71 by applying and removing a load. By using the spring back, the inner diameter side end face 76 and the outer diameter side end face 75 can be joined relatively easily.

  Moreover, the punch 600a of the cylindrical member forming die of the present embodiment includes an outer peripheral surface convex portion 600b and an outer peripheral surface concave portion 600c. In addition, the cored bar 616 includes an inner peripheral surface convex portion 616b and an inner peripheral surface concave portion 616c. For this reason, the positional relationship in the radial direction between the outer diameter side end face 75 and the inner diameter side end face 76 can be interchanged relatively easily. As a result, the outer diameter side end face 75 and the inner diameter side end face 76 can be abutted relatively easily.

  Moreover, the cylindrical member molding die of this embodiment is easy to add-on to a conventional molding machine. That is, the conventional molding machine can be used as it is by replacing the punch of the conventional molding machine with the punch 600a of the present embodiment and the core metal of the conventional molding machine with the core metal 616 of the present embodiment. it can. For this reason, the cylindrical member shaping | molding die of this embodiment is rich in versatility.

  Further, as shown in FIGS. 23 and 24, the end surface 15 of the circumferential one end 11 and the end surface 16 of the other circumferential end 13 of the cylindrical spring 1 of the present embodiment use springback force. Are joined. For this reason, welding marks are not expressed at the boundary between the end faces 15 and 16. Therefore, the cylindrical spring 1 of this embodiment has a good appearance. Moreover, since there is no welding mark, the dimensional accuracy is high.

  Moreover, when the end surfaces 15 and 16 are joined by welding, the joining force tends to vary. In this regard, according to the cylindrical spring 1 of the present embodiment, the end faces 15 and 16 are joined using a springback force. For this reason, it is hard to produce dispersion | variation in the joining force of the end surfaces 15 and 16. FIG.

  Further, as shown in FIG. 24, C-shaped holes 10a and 10b formed by half-cutting the rectangular hole 10 are expressed at the boundary between the end faces 15 and 16 of the cylindrical spring 1. If the end faces 15 and 16 are joined by welding, when the welding is peeled off, the axial end applied to the cylindrical spring 1 causes the opening end of the C-shaped hole 10a to open the end face 16 and the opening of the C-shaped hole 10b. The end slides to scratch the end face 15. For this reason, stress tends to concentrate in the vicinity of the C-shaped holes 10a and 10b.

  In this regard, according to the cylindrical spring 1 of the present embodiment, the open end of the C-shaped hole 10a is always in pressure contact with the end face 16 and the open end of the C-shaped hole 10b is always in pressure contact with the end face 15 by the springback force. For this reason, stress hardly concentrates in the vicinity of the C-shaped holes 10a and 10b.

  <Second embodiment>

  The difference between the present embodiment and the first embodiment is only one end unprocessed process. Therefore, only the differences will be described here. In the one end unprocessed step of this embodiment, a bending process including a first stage and a second stage is performed on a portion other than the one end of the plate material to produce a substantially cylindrical workpiece.

  In the first stage, by using a plurality of molds in order, a flat plate material is formed in a substantially W shape step by step. FIG. 25 shows a cross-sectional view of a mold used in the first stage of the one end unprocessed process of the present embodiment. In addition, what is shown to a figure is the metal mold | die used last among the some metal mold | dies used at a 1st step. As shown in the figure, the mold 8a includes a steel punch 80a and a steel die 81a. The mold surface of the punch 80a and the mold surface of the die 81a are both substantially W-shaped. The plate member 2 is interposed between the punch 80a and the die 81a. Clamping is performed by the punch 80a being pressed against the die 81a. Incidentally, a planar section F is defined at one end of the W shape of the punch 80a and the die 81a. In the plane section F, one end 21 of the plate member 2 is disposed. On the other hand, the other end 23 of the plate member 2 is subjected to a predetermined bending process.

  In the second stage, a substantially cylindrical workpiece is produced from the substantially W-shaped plate material 2. FIG. 26 shows a cross-sectional view (a state before mold clamping) of a mold used in the second stage of the one end unprocessed process of the present embodiment. As shown in the drawing, the mold 8b includes a steel cored bar 80b and a steel die 81b. The core metal 80b has a cylindrical shape. The die 81b has a semicircular surface. The plate material 2 is interposed between the cored bar 80b and the die 81b. When the peak portion at the center of the W-shape of the plate material 2 is pressed by the core metal 80b, the plate material 2 is deformed so that the one end portion 21 and the other end portion 23 approach each other (just so that the opening is closed).

  FIG. 27 shows a cross-sectional view (clamped state) of a mold used in the second stage of the one end unprocessed process of the present embodiment. In addition, about the site | part corresponding to FIG. 17, it shows with the same code | symbol. As shown in the drawing, when the cored bar 80b is lowered to a predetermined position, the substantially cylindrical workpiece 7 is completed. An outer diameter side end portion 71 is formed from the one end portion 21. In addition, an inner diameter side end portion 73 is formed from the other end portion 23.

  The cylindrical member molding method of this embodiment has the same effects as the cylindrical member molding method of the first embodiment. Moreover, according to the cylindrical member molding method of the present embodiment, the one-end unprocessed step can be performed only by providing the plane section F shown in FIG. 25 in the mold of the conventional molding machine. For this reason, the cylindrical member shaping | molding method of this embodiment is rich in versatility.

  <Third embodiment>

  The difference between the present embodiment and the first embodiment is only one end unprocessed process. Therefore, only the differences will be described here. In the one end untreated process of the present embodiment, roll bending is performed on a portion other than the one end of the plate material to produce a substantially cylindrical workpiece.

  FIG. 28 shows a cross-sectional view of a roll forming machine used in the one-end untreated process of the present embodiment. The roll forming machine 8c includes a rigid roll 80c and an elastic roll 81c that can rotate together.

  The rigid roll 80c is made of steel and has a cylindrical shape. The elastic body roll 81 c includes a steel core 810 and a urethane rubber roll body 811. The core 810 has a cylindrical shape. The roll body 811 is wrapped around the core 810. The plate member 2 is inserted between the rigid roll 80c and the elastic roll 81c with the other end 23 at the head.

  FIG. 29 is a cross-sectional view of the roll forming machine used in the one end unprocessed step of the present embodiment during plate processing. As shown in the drawing, the plate material 2 is bent along the rigid roll 80c, whereby the plate material 2 is subjected to a round bending process. The plate member 2 is inserted between the rigid roll 80c and the elastic roll 81c, leaving only one end 21.

  In FIG. 30, sectional drawing after the board | plate material processing of the roll forming machine used by the one end part unprocessed process of this embodiment is shown. In addition, about the site | part corresponding to FIG. 17, it shows with the same code | symbol. As shown in the figure, the entire portion (including the inner diameter side end portion 73) excluding the outer diameter side end portion 71 is subjected to a round bending process. In this way, a substantially cylindrical workpiece 7 is completed.

  The cylindrical member molding method of this embodiment has the same effects as the cylindrical member molding method of the first embodiment. In addition, according to the cylindrical member forming method of the present embodiment, the workpiece 7 can be produced relatively easily. Moreover, according to the cylindrical member shaping | molding method of this embodiment, a one end part unprocessed process can be implemented using the conventional roll forming machine as it is. For this reason, the cylindrical member shaping | molding method of this embodiment is rich in versatility.

  <Fourth embodiment>

  The difference between the present embodiment and the first embodiment is only one end unprocessed process. Therefore, only the differences will be described here. In the one end unprocessed step of the present embodiment, a curl bend is applied to a portion other than one end of the plate material to produce a substantially cylindrical workpiece.

  FIG. 31 shows a cross-sectional view (a state before mold clamping) of a mold used in the one end unprocessed step of the present embodiment. The mold 8d includes a steel punch 80d and a steel die 81d. The mold surface of the punch 80d has a semicircular surface shape. The plate material 2 is interposed between the punch 80d and the die 81d. The other end 23 is disposed close to the punch 80d. On the other hand, the one end portion 21 is disposed away from the punch 80d. When the punch 80d is inserted into the die 81d, the plate material 2 is gradually rounded with the other end 23 at the head by the die surface of the punch 80d. When the punch 80d reaches the bottom dead center, the entire portion excluding the one end 21 of the plate member 2 is subjected to a round bending process.

  FIG. 32 shows a cross-sectional view (clamping state) of a mold used in the one end unprocessed step of the present embodiment. In addition, about the site | part corresponding to FIG. 17, it shows with the same code | symbol. As shown in the figure, the entire portion (including the inner diameter side end portion 73) excluding the outer diameter side end portion 71 is subjected to a round bending process. In this way, a substantially cylindrical workpiece 7 is completed.

  The cylindrical member molding method of this embodiment has the same effects as the cylindrical member molding method of the first embodiment. In addition, according to the cylindrical member forming method of the present embodiment, the workpiece 7 can be produced relatively easily. Moreover, according to the cylindrical member shaping | molding method of this embodiment, the one end part unprocessed process can be implemented using the conventional curl forming machine as it is. For this reason, the cylindrical member shaping | molding method of this embodiment is rich in versatility.

  <Fifth embodiment>

  The difference between the present embodiment and the first embodiment is only the shape of the chamfered portion. Therefore, only the differences will be described here. FIG. 33 is a partially enlarged cross-sectional view at the top dead center position of the molding machine used in the both end surface reversing step of the present embodiment. In addition, about the site | part corresponding to FIG. 18, it shows with the same code | symbol.

  As shown in the figure, a chamfered portion 72 a is formed on the inner peripheral surface of the distal end of the outer diameter side end portion 71. The chamfered portion 72a has a curved surface shape. On the other hand, a chamfered portion 74 a is formed on the outer peripheral surface of the distal end of the inner diameter side end portion 73. The chamfered portion 74a has a curved surface shape. These chamfered portions 72a and 74a are formed by a surface pressing process (see FIGS. 4 and 5).

  FIG. 34 is a partial enlarged cross-sectional view immediately before shifting to the bottom dead center position of the molding machine used in the both end face reversal process of the present embodiment. In addition, about the site | part corresponding to FIG. 19, it shows with the same code | symbol. As shown in the drawing, the outer diameter side end portion 71 of the workpiece 7 is pressed downward by the outer peripheral surface convex portion 600b of the punch 600a. For this reason, the chamfered portion 72 a of the outer diameter side end portion 71 is in sliding contact with the chamfered portion 74 a of the inner diameter side end portion 73. Here, the chamfered portions 72a and 74a are both curved. Therefore, the chamfered portions 72a and 74a are in line contact with each other. Moreover, a component force in the right direction is generated at the inner diameter side end portion 73 through the line contact between the chamfered portions 72a and 74a. Therefore, the outer diameter side end 71 moves downward while consuming the interference and pushing the inner diameter side end 73 in the right direction.

  The cylindrical member molding method of this embodiment has the same effects as the cylindrical member molding method of the first embodiment. Further, according to the cylindrical member forming method of the present embodiment, the chamfered portions 72a and 74a are both curved. For this reason, the chamfered portions 72a and 74a are in line contact with each other in the both end surface reversing step. Therefore, the frictional force at the time of sliding becomes small. As described above, according to the cylindrical member molding method of the present embodiment, it is easy to reverse the radial positional relationship between the outer diameter side end face 75 and the inner diameter side end face 76. Further, in the cylindrical spring of this embodiment, the chamfered portion is not noticeable. For this reason, it looks good.

  <Sixth embodiment>

  The difference between the present embodiment and the first embodiment is that one end reverse bending step is performed instead of the one end untreated step. In addition, a chamfered portion is not formed on the plate material and the cylindrical spring. Therefore, only the differences will be described here.

  In the one end portion reverse bending step, a round bending process is performed on one end portion of the plate material that has been flat in the one end portion non-processing step, in the direction opposite to the portion other than the one end portion. The round bending process is performed by press forming, roll bending, curl bending, or the like described in the first to fifth embodiments.

  FIG. 35 is a partial enlarged cross-sectional view at the top dead center position of the molding machine used in the both end face reversal process of the present embodiment. In addition, about the site | part corresponding to FIG. 17, it shows with the same code | symbol. As shown in the figure, the outer diameter side end portion 71a is subjected to a round bending process in the direction opposite to the portion other than the outer diameter side end portion 71a of the workpiece 7.

  FIG. 36 is a partial enlarged cross-sectional view immediately before shifting to the bottom dead center position of the molding machine used in the both end face reversal process of the present embodiment. In addition, about the site | part corresponding to FIG. 19, it shows with the same code | symbol. As shown in the figure, the outer diameter side end portion 71a of the work 7 is pressed downward by the outer peripheral surface convex portion 600b of the punch 600a. At this time, the outer diameter side end 71a is gradually deformed so as to follow the shape of the inner peripheral surface recess 616c. For this reason, the vicinity of the outer diameter side end face 75a of the outer diameter side end 71a gradually warps. In other words, the intersection angle between the outer diameter side end face 75a and the inner diameter side end face 76a gradually opens. Therefore, the tip A of the inner peripheral surface of the outer diameter side end portion 71a comes into line contact with the inner diameter side end surface 76a of the inner diameter side end portion 73a. The tip A slides downward on the inner diameter side end face 76a. Thus, also when the tip A of the inner peripheral surface of the outer diameter side end portion 71a contacts the inner diameter side end surface 76a of the inner diameter side end portion 73a, the “interference allowance” of the present invention is expressed.

  The cylindrical member molding method of this embodiment has the same effects as the cylindrical member molding method of the first embodiment. Further, according to the cylindrical member forming method of the present embodiment, the tip A of the inner peripheral surface of the outer diameter side end portion 71a is in line contact with the inner diameter side end surface 76a of the inner diameter side end portion 73a. For this reason, the frictional force at the time of sliding becomes small. Therefore, according to the cylindrical member molding method of the present embodiment, it is easy to reverse the radial positional relationship between the outer diameter side end face 75a and the inner diameter side end face 76a. Moreover, the cylindrical spring of this embodiment does not have a chamfered portion. For this reason, it looks good.

  <Others>

  The embodiment of the cylindrical member forming method, the cylindrical member forming die, and the cylindrical member of the present invention has been described above. However, the embodiment is not particularly limited to the above embodiment. Various modifications and improvements that can be made by those skilled in the art are also possible.

  For example, in the above-described embodiment, the plate material 2 sheared from the strip material in advance is used, but as shown in FIG. 37, the plurality of plate materials 2 connected by the connecting portion 90 are passed through the molding machine to bend. Processing may be performed. And you may cut out the connection part 90 after cylindrical spring preparation. In addition, as shown in FIG. 38, unevenness 91 may be provided on the surface of the plate member 2.

  Moreover, in the said embodiment, although the cylindrical member shaping | molding method of this invention was used for the cylindrical spring 1 for piezoelectric actuators, you may use for the cylindrical spring for piezoelectric sensors, the cylindrical spring for mold plungers, etc. Moreover, you may use not only for a cylindrical spring but for all cylinder members, such as a lock holder for steering lock mechanisms, various pipes, and various collars.

  Further, the shape of the cylindrical member may be a perfect circle or an ellipse. In the case of an ellipse, the entire circumference may be a curved surface, and a part of a plane may be interposed, for example, as in an athletics track. Further, the shape of the cylindrical member is not limited to a circle, and may be a polygon such as a rectangle or a pentagon.

  Further, the outer diameter side end 71 and the inner diameter side end 73 of the work 7 after the work preparation step may be in contact with each other in the radial direction. Moreover, the molding machine in the said embodiment does not need to interlock | cooperate mechanically. For example, a hydraulic cylinder type may be used. Moreover, the metal mold | die in the said embodiment is not restricted to steel, For example, the product made from rubber | gum and ceramics may be sufficient. Further, the springback amount of the outer diameter side end 71 in the both end face butting step can be appropriately adjusted by changing the load value of the punch 600a, for example. Further, the interference allowance IF (see FIGS. 17 and 18) and the overlap OL (see FIGS. 21 and 22) can be appropriately changed depending on the hardness of the plate member 2 and the like.

  Further, when the plate member 2 is formed of a material having a relatively small amount of spring back (for example, a material with low hardness), the load value of the punch 600a is large, and the stress distribution in the outer diameter side end portion 71 is not uniform. If it can be corrected, the reversing process on both ends is not necessary. In this case, the number of processes can be reduced by the amount that the both end face reversal process is unnecessary. Further, the outer peripheral surface convex portion 600b, the outer peripheral surface concave portion 600c, and the step 600d of the punch 600a shown in FIG. In addition, the inner peripheral surface convex portion 616b, the inner peripheral surface concave portion 616c, and the step 616d of the cored bar 616 become unnecessary. That is, a conventional mold can be used as it is.

  Moreover, in the said embodiment, although the center angle (alpha) (refer above-mentioned FIG. 22) was set to 55 degrees, the center angle (alpha) is not specifically limited. Preferably, the central angle α is 40 ° or more. The reason why the central angle α is set to 40 ° or more is that when the angle is less than 40 °, it is difficult to secure a desired springback force after the both end face-butting step.

  In addition, the center angle α is preferably 70 ° or less. The reason why the central angle α is set to 70 ° or less is that when it exceeds 70 °, it is difficult to reverse the radial positional relationship between the inner diameter side end surface 76 and the outer diameter side end surface 75 in the both end surface reversing step.

It is a perspective view of the board | plate material after the surface pressing process of 1st embodiment. It is an enlarged view in the circle Ia of FIG. It is an expansion permeation | transmission figure in the circle Ib of FIG. It is sectional drawing (mold clamping state) of the metal mold | die used in order to form a chamfering part in an end part by a surface pressing process. It is sectional drawing (clamping state) of the metal mold | die used in order to form a chamfering part in an other end part at the same process. It is sectional drawing of the metal mold | die used at the 1st step of the one end part unprocessed process of 1st embodiment. It is sectional drawing of the metal mold | die used at the 2nd step of the process. It is sectional drawing of the metal mold | die used at the 3rd step of the process. It is sectional drawing of the metal mold | die used at the 4th step of the process. It is sectional drawing in the middle of the top dead center position-bottom dead center position transfer of the molding machine used in the 4th step of the process. It is sectional drawing in the bottom dead center position of the molding machine used in the 4th step of the process. It is an enlarged view in the circle XI of FIG. It is sectional drawing in the bottom dead center position of the molding machine used in the 5th step of the process. FIG. 14 is an enlarged view in a circle XIII in FIG. 13. It is sectional drawing in the top dead center position of the molding machine used at the both end surface inversion process of 1st embodiment. FIG. 16 is an enlarged view in a circle XVa in FIG. 15. It is an enlarged view in the circle | round | yen XVb of FIG. It is an enlarged view in the circle | round | yen XVII of FIG. It is a partial expanded sectional view in front of the bottom dead center position transfer of the molding machine used at the same process. It is sectional drawing in the bottom dead center position of the molding machine used at the same process. It is an enlarged view in the circle XX of FIG. It is an enlarged view of the workpiece | work and cored bar of FIG. It is a partial expanded sectional view in the top dead center position of the molding machine used at the both-ends side butting process of a first embodiment. It is a perspective view of the cylindrical spring of this embodiment. It is sectional drawing of the metal mold | die used at the 1st step of the one end part unprocessed process of 2nd embodiment. It is sectional drawing (state before mold clamping) of the metal mold | die used at the 2nd step of the process. It is sectional drawing (clamping state) of the metal mold | die used at the 2nd step of the process. It is sectional drawing of the roll forming machine used at the one end part non-processing process of 3rd embodiment. It is sectional drawing in the board | plate material processing of the roll forming machine used at the same process. It is sectional drawing after the board | plate material process of the roll forming machine used at the same process. It is sectional drawing (state before mold clamping) of the metal mold | die used at the one end part non-process of 4th embodiment. It is sectional drawing (clamping state) of the metal mold | die used at the same process. It is a partial expanded sectional view in the top dead center position of the molding machine used in the both end surface reversing process of the fifth embodiment. It is a partial expanded sectional view in front of the bottom dead center position transfer of the molding machine used at the same process. It is a partial expanded sectional view in the top dead center position of the molding machine used at the both end surface reversing process of the sixth embodiment. It is a partial expanded sectional view in front of the bottom dead center position transfer of the molding machine used at the same process. It is one Embodiment of the board | plate material used for the cylindrical member shaping | molding method of this invention. It is one Embodiment of the board | plate material used for the cylindrical member shaping | molding method of this invention.

Explanation of symbols

  1: cylindrical spring (cylindrical member), 10: rectangular hole, 10a: C-shaped hole, 10b: C-shaped hole, 11: one end in the circumferential direction, 12: chamfered part, 13: other end in the circumferential direction, 14: chamfered part 15: end face, 16: end face, 2: plate material, 20: rectangular hole, 21: one end, 22: chamfer, 23: other end, 24: chamfer, 25a: mold, 25b: mold, 250a : Punch, 250b: Punch, 251a: Die, 251b: Die, 3a: Mold, 3b: Mold, 3c: Mold, 30a: Punch, 30b: Punch, 30c: Punch, 31a: Die, 31b: Die, 31c: die, 4: molding machine, 40: upper mold holder, 400: upper mold base, 401a: cam driver, 401b: cam driver, 402a: driving surface, 402b: driving surface, 403a: U-shaped groove, 403b: U Gutter, 404: Bolt, 41: Lower mold Holder: 410: Lower mold base, 411: Support base, 412a: Backup plate, 412b: Backup plate, 413a: Cam slide, 413b: Cam slide, 414a: Shaft, 414b: Shaft, 415a: Return spring, 415b: Return spring 416: cored bar, 416a: step, 417: support rib, 418: bolt, 419a: shaft insertion hole, 419b: shaft insertion hole, 420a: driven surface, 420b: driven surface, 421a: mold surface, 421b: mold surface 513a: cam slide, 513b: cam slide, 516: core metal, 516a: step, 521a: mold surface, 521b: mold surface, 600: upper mold base, 600a: punch (outer peripheral surface mold), 600b: outer peripheral surface Convex part, 600c: concave part for outer peripheral surface, 600d: step, 613a: Slide, 613b: cam slide, 616: core metal (inner peripheral surface mold), 616b: convex portion for inner peripheral surface, 616c: concave portion for inner peripheral surface, 616d: step, 621a: mold surface, 621b: mold surface, 7: Work, 7 ': Virtual shape, 71: Outer diameter side end, 71a: Outer diameter side end, 72: Chamfered part, 72a: Chamfered part, 73: Inner diameter side end, 73a: Inner diameter side end, 74: chamfered portion, 74a: chamfered portion, 75: outer diameter side end surface, 75a: outer diameter side end surface, 76: inner diameter side end surface, 76a: inner diameter side end surface, 8a: mold, 8b: mold, 8c: roll molding Machine, 8d: mold, 80a: punch, 80b: core metal, 80c: rigid roll, 80d: punch, 81a: die, 81b: die, 81c: elastic roll, 81d: die, 810: core, 811: roll Main body, 90: connecting portion, 91: unevenness 91, A: End, F: Plane section, IF: Interference allowance, L: Circumferential length of outer diameter side end, O: Cylindrical axis, O ′: Arc center, OL: Overlap allowance, R: Inner diameter, R ′: Inner diameter , T: thickness of the outer diameter side end, α: center angle, α ′: center angle, θ: center angle.

Claims (10)

A cylinder member molding method for producing a cylinder member from a plate material,
By bending the plate material, an inner diameter side end portion having an inner diameter side end surface at the tip, and an outer diameter side end portion having an outer diameter side end surface arranged at the outer diameter side from the inner diameter side end surface at the tip, The inner diameter side end face and the outer diameter side end face between the inner diameter side end part and the outer diameter side end part, the interference margin that is expressed when trying to arrange the substantially same diameter on the outer diameter side end face A workpiece fabrication process for fabricating a cylindrical workpiece;
By deforming at least one of the inner diameter side end and the outer diameter side end so as to consume the interference margin, the inner diameter side end and the outer diameter side end are brought into sliding contact with each other, The inner diameter side end face and the outer diameter side end face are abutted, and based on the consumption of the interference, utilizing the springback force acting in the circumferential direction and the direction in which the inner diameter side end face and the outer diameter side end face are brought closer to each other, Both end face joining step of joining the inner diameter side end face and the outer diameter side end face to produce the cylindrical tubular member;
I have a,
In the both end surface joining step, a radial position between the inner diameter side end surface and the outer diameter side end surface is applied to at least one of the inner diameter side end portion and the outer diameter side end portion from the radial direction. Both ends reversing process to reverse the relationship;
Utilizing a springback acting in the radial direction generated by removing the load, overlapped in the circumferential direction secured between the inner diameter side end and the outer diameter side end after the both end face reverse process And the both end face butting process of butting the inner diameter side end face and the outer diameter side end face,
The plate member has one end and the other end facing the one end,
In the work preparation step, the outer diameter side end portion is formed from the one end portion and the inner diameter side end portion is formed from the other end portion by subjecting the plate material to a portion other than the one end portion. A cylindrical member forming method, which is an untreated one end portion process.   2. The cylindrical member forming method according to claim 1, wherein a ratio L / t between a circumferential length L and a thickness t of the outer diameter side end is set to 7 or more and 13 or less.   A cylinder member molding method for producing a cylinder member from a plate material,
  By bending the plate material, an inner diameter side end portion having an inner diameter side end surface at the tip, and an outer diameter side end portion having an outer diameter side end surface arranged at the outer diameter side from the inner diameter side end surface at the tip, The inner diameter side end face and the outer diameter side end face between the inner diameter side end part and the outer diameter side end part, the interference margin that is expressed when trying to arrange the substantially same diameter on the outer diameter side end face A workpiece fabrication process for fabricating a cylindrical workpiece;
  By deforming at least one of the inner diameter side end and the outer diameter side end so as to consume the interference margin, the inner diameter side end and the outer diameter side end are brought into sliding contact with each other, The inner diameter side end face and the outer diameter side end face are abutted, and based on the consumption of the interference, utilizing the springback force acting in the circumferential direction and the direction in which the inner diameter side end face and the outer diameter side end face are brought closer to each other, Both end face joining step of joining the inner diameter side end face and the outer diameter side end face to produce the cylindrical tubular member;
Have
  In the both end surface joining step, a radial position between the inner diameter side end surface and the outer diameter side end surface is applied to at least one of the inner diameter side end portion and the outer diameter side end portion from the radial direction. Both ends reversing process to reverse the relationship;
  Utilizing a springback acting in the radial direction generated by removing the load, overlapped in the circumferential direction secured between the inner diameter side end and the outer diameter side end after the both end face reverse process And the both end face butting process of butting the inner diameter side end face and the outer diameter side end face,
  The plate member has one end and the other end facing the one end,
  The workpiece manufacturing step includes forming the outer diameter side end portion from the one end portion by subjecting the one end portion and a portion excluding the one end portion of the plate material to round bending in opposite directions. A cylindrical member forming method, which is a one end reverse bending step of forming the inner diameter side end from the other end.   Further, before the both end surface joining step, at least one of the outer peripheral surface of the tip end of the inner diameter side end portion and the inner peripheral surface of the tip end of the outer diameter side end portion is provided with the cylinder after the both end surface joining step. The cylindrical member forming method according to any one of claims 1 to 3, further comprising a chamfering step of arranging a chamfer exposed in a radial direction of the member.   The cylindrical member forming method according to any one of claims 1 to 4, wherein the overlap margin is secured at a central angle of 1 ° or more and 4 ° or less of the workpiece.   The cylindrical member is a cylindrical spring to which a load is applied in the axial direction and a plurality of holes are arranged on the side peripheral wall,
  The cylindrical member forming method according to any one of claims 1 to 5, wherein an opening end of the hole is arranged on the inner diameter side end face and the outer diameter side end face of the cylindrical spring.   It is used for the both end surface reversing step in the cylindrical member forming method according to claim 1,
  An inner diameter side end portion having an inner diameter side end surface at the tip, and an outer diameter side end portion having an outer diameter side end surface disposed on the outer diameter side from the inner diameter side end surface, the inner diameter side end portion, From the substantially cylindrical workpiece that secures an interference margin that occurs when the inner diameter side end surface and the outer diameter side end surface are arranged on substantially the same diameter between the outer diameter side end portion and the cylindrical tube, A cylindrical member mold for producing a member,
  At the time of mold clamping, the outer diameter side end surface, the outer peripheral surface convex portion that consumes the interference allowance and pushes further to the inner diameter side of the inner diameter side end surface,
  An outer peripheral surface molding die that is provided in parallel with the outer peripheral surface convex portion and has an outer peripheral surface concave portion that suppresses the inner diameter side end surface from being pushed into the inner diameter side together with the outer diameter side end surface during mold clamping. A cylindrical member molding die characterized by the above.   Further, when clamping, the inner peripheral surface concave portion into which the outer diameter side end surface pushed by the outer peripheral surface convex portion enters,
  In parallel with the concave portion for the inner peripheral surface, the inner peripheral side end surface is prevented from being pushed into the concave portion for the inner peripheral surface together with the outer peripheral surface concave portion when the mold is clamped. The cylindrical member molding die according to claim 7, further comprising an inner circumferential surface molding die having an inner circumferential surface convex portion.   Manufactured by the cylindrical member forming method according to any one of claims 1 to 6,
  A cylindrical tube member comprising a circumferential one end and a circumferential other end joined to the circumferential one end in the circumferential direction,
  The end surface of the one end portion in the circumferential direction and the end surface of the other end portion in the circumferential direction are joined using a springback force acting in the circumferential direction and the direction in which the both end surfaces are brought close to each other.
  A cylindrical member characterized in that a chamfered portion that is exposed in the radial direction is formed on at least one of the outer peripheral surface at the tip of the circumferential end and the inner peripheral surface of the tip of the other end in the circumferential direction. .   A load is applied in the axial direction, a plurality of holes are arranged in the side peripheral wall,
  The cylindrical member according to claim 9, wherein an opening end of the hole is disposed on the end surface of the one circumferential end and the end surface of the other circumferential end.

Images