JP6136645B2 - Manufacturing method of circular material - Google Patents

Description

The present invention relates to a method for manufacturing a circular material and a forging device used therefor, and more particularly to a method for manufacturing a circular material typified by railway wheels, gears and rings, and a forging device used therefor.

  Circular materials represented by railway wheels, gears and rings have a circular outer peripheral surface (cross-sectional shape perpendicular to the central axis of the circular material). Such a circular material is manufactured as follows, for example.

  First, the cylindrical material is heated. An intermediate product (forged wasteland) is manufactured by performing wasteland forming processing on the heated cylindrical material. In the wasteland forming process, upsetting forging is performed one or more times. A circular material is manufactured by performing finish rolling, finish forging, and the like on the forged wasteland. If necessary, heat treatment and machining may be performed on the circular material after finish forging.

  When the circular material is a railway wheel, forged wasteland is manufactured by performing upset forging (an early wasteland forming process and a later wasteland forming process) twice in the wasteland forming process. In the first wasteland forming step, upset forging is performed on the cylindrical material using a pair of open molds. In the later wasteland forming step, upset forging is performed using a pair of molds having a shape different from that of the earlier wasteland forming step. A forged wasteland having a rough shape of a railway wheel is manufactured by the first and second wasteland forming processes.

  In the case where the circular material is a ring, upset forging is performed by performing upset forging on the cylindrical material in the wasteland forming step. After drilling the central part of the forged wasteland, the drilled forged wasteland is subjected to finish rolling and finish forging, and further machined as necessary to produce a ring.

  When upsetting forging is performed on a cylindrical material in the first wasteland forming step, an open die is used as described above. The open mold does not restrain the outer peripheral surface of the cylindrical material during upsetting forging. Therefore, when the center axis of the columnar material is shifted from the center axis of the mold, or when the cross-sectional shape of the columnar material is non-uniform, uneven thickness occurs in the forged rough ground produced by the rough ground forming process. There is.

  A technique for suppressing the occurrence of uneven thickness is proposed in Japanese Patent Laid-Open No. 2003-19534 (Patent Document 1). In patent document 1, after arrange | positioning a cylindrical raw material in a cylindrical ring tool, upset forging is implemented with respect to a cylindrical raw material. At this time, the inner surface of the ring tool comes into contact with the outer peripheral surface of the cylindrical material deformed by upsetting forging, and restrains the cylindrical material. Subsequently, upsetting forging is stopped and the ring tool is removed from the forging device. After removing the ring tool, upset forging is performed again to produce a forged rough ground having a general shape of a circular material.

JP 2003-19534 A

  As described above, Patent Document 1 includes a step of removing the ring tool from the forging device during the wasteland forming step. In order to remove the ring tool, for example, one of a pair of molds must be separated from the cylindrical material to create a gap for extracting the ring tool. Therefore, the process of removing the ring tool decreases the production efficiency of the circular material.

  The objective of this invention is providing the manufacturing method of the circular material which can suppress generation | occurrence | production of uneven thickness, suppressing the fall of production efficiency.

  The manufacturing method according to the present embodiment manufactures a circular material by performing upset forging on a cylindrical material. The manufacturing method includes an arrangement process, a projecting process, a first upsetting forging process, a storing process, and a second upsetting forging process. In the arranging step, the columnar material is arranged between the first and second molds using a forging device including first and second molds facing each other. A 1st metal mold | die contains the cylindrical member which has an internal peripheral surface whose cross-sectional shape is a circle, and the circular member arrange | positioned in a cylindrical member coaxially with a cylindrical member. The outer diameter of the cylindrical material is smaller than the inner diameter of the cylindrical member. In the projecting step, the cylindrical member is advanced relative to the circular member and protrudes to the second mold side from the circular member. In the first upsetting forging step, after protruding the cylindrical member, upsetting forging is performed on the cylindrical material, and the cylindrical material is brought into contact with the inner peripheral surface of the cylindrical member. In the storing step, after the cylindrical material comes into contact with the inner peripheral surface of the cylindrical member, the protruding cylindrical member is moved backward relative to the circular member, and the cylindrical member is pulled out from the cylindrical material. In the second upsetting forging step, after pulling out the cylindrical member, upsetting forging is performed on the cylindrical material, and the cylindrical material is brought into contact with the end surface of the cylindrical member after retreating.

  The forging device of this embodiment is used in the above manufacturing method.

  The manufacturing method and the forging device according to the present embodiment can suppress the occurrence of uneven thickness in a circular material while suppressing a decrease in production efficiency.

FIG. 1 is a cross-sectional view of the forging device in the present embodiment. FIG. 2 is a plan view of a mold including a cylindrical member and a circular member in FIG. FIG. 3 is a cross-sectional view of the forging device after sliding the cylindrical member in FIG. FIG. 4 is a flowchart of a method for manufacturing a circular material in the present embodiment. FIG. 5 is a schematic diagram for explaining the arrangement step in FIG. 6 is a plan view of the cylindrical material in FIG. FIG. 7 is a schematic diagram for explaining the protruding step in FIG. FIG. 8 is a schematic diagram for explaining the first upset forging step in FIG. 4. FIG. 9 is a schematic diagram for explaining the storing step in FIG. FIG. 10 is a schematic diagram for explaining the second upsetting forging step in FIG. 4. FIG. 11 is a diagram showing the relationship between the amount of reduction during upsetting forging and the uneven thickness ratio of the cylindrical material. 12 is a cross-sectional view of another cylindrical member having a configuration different from that of the cylindrical member in FIG. FIG. 13 is a cross-sectional view of another forging device of the present embodiment having a configuration different from that of FIG. FIG. 14 is a cross-sectional view of another forging device of the present embodiment having a configuration different from that of FIGS. 1 and 13.

  The manufacturing method according to the present embodiment manufactures a circular material by performing upset forging on a cylindrical material. The manufacturing method includes an arrangement process, a projecting process, a first upsetting forging process, a storing process, and a second upsetting forging process. In the arranging step, first and second molds facing each other are provided, and the first mold is arranged in the cylindrical member having a cylindrical member having an inner peripheral surface whose cross-sectional shape is a circle, and coaxial with the cylindrical member. A cylindrical material having an outer diameter smaller than the inner diameter of the cylindrical member is disposed between the first and second molds of the forging device including the circular member to be formed. In the projecting step, the cylindrical member is advanced relative to the circular member and protrudes to the second mold side from the circular member. In the first upsetting forging step, after protruding the cylindrical member, upsetting forging is performed on the cylindrical material, and the cylindrical material is brought into contact with the inner peripheral surface of the cylindrical member. In the storing step, after the cylindrical material comes into contact with the inner peripheral surface of the cylindrical member, the protruding cylindrical member is moved backward relative to the circular member, and the cylindrical member is pulled out from the cylindrical material. In the second upsetting forging step, after pulling out the cylindrical member, upsetting forging is performed on the cylindrical material, and the cylindrical material is brought into contact with the end surface of the cylindrical member after retreating.

  In the present embodiment, the first upset forging is performed after the cylindrical member is protruded to the second mold side. By this upset forging, the cylindrical material is deformed and spreads in the radial direction. And when the outer peripheral surface of a columnar material contacts the inner peripheral surface of a cylinder member, a columnar material is restrained by a cylinder member. When the cylindrical material is restrained by the cylindrical member, the occurrence of uneven thickness is suppressed.

  Further, after the protruding cylindrical member is retracted and the cylindrical member is pulled out from the cylindrical material, second upset forging is performed. At this time, the columnar material further spreads in the radial direction, and contacts the end surface of the cylinder member after retreating together with the surface of the circular member. Therefore, the end surface of the cylindrical member is used as the surface (forged surface) of the first mold in the second upset forging. In the manufacturing method of the present embodiment, it is not necessary to remove the cylindrical member from the forging device as in Patent Document 1. Therefore, it is possible to suppress a decrease in production efficiency due to the removal of the cylindrical member. Further, since the upsetting forging is performed by using the end surface of the cylindrical member as the surface (forging surface) of the first mold, the inner peripheral surface of the cylindrical member effectively restrains the cylindrical material in the first upsetting forging. As can be done, the inner diameter of the cylindrical member can be made to an appropriate size.

  In this specification, the term “coaxial” refers not only to the case where the central axis of the cylindrical member exactly coincides with the central axis of the circular member, but also the cylindrical member slides in the axial direction of the first mold relative to the circular member. And the case where the central axis of the cylindrical member is slightly deviated from the central axis of the circular member.

  The inner diameter of the cylindrical member may increase toward the second mold.

  In this case, when the cylindrical member is slid after the first upset forging step, the columnar material is easily separated from the inner surface of the cylindrical member. Therefore, it is easy to pull out the tubular member from the cylindrical material.

  The end surface of the cylindrical member may be inclined to the outside of the cylindrical member.

  In this case, in the second upsetting forging step, a part of the columnar material being deformed hardly enters the gap between the circular material and the cylindrical member. Furthermore, the thickness of the outer peripheral edge portion of the intermediate product after the second upset forging step becomes thicker than other portions. Further, the scale of the cylindrical material is easily removed to the outside of the first mold.

  In the step of retracting the cylindrical member, the end surface of the cylindrical member may be arranged so that the outer edge of the surface of the circular member is closer to the second mold side than the inner edge of the end surface of the cylindrical member.

  In this case, in the second upsetting forging process, it is difficult for a part of the columnar material being deformed to enter the gap between the circular material and the cylindrical member.

  The forging device according to the present embodiment is used in the manufacturing method described above. The forging device of this embodiment performs upset forging on a cylindrical material. The forging device includes first and second molds arranged to face each other. The first mold includes a cylindrical member and a circular member. The cylindrical member includes an inner peripheral surface having a circular cross-sectional shape and an end surface disposed to face the second mold. The circular member is disposed in the cylindrical member coaxially with the cylindrical member. The forging device further includes a slide device. When the first upsetting forging is performed, the slide device advances the cylinder member relative to the circular member so that the cylindrical member protrudes toward the second mold side relative to the circular member. When the second upset forging is performed after forging, the protruding cylindrical member is moved backward relative to the circular member. In the first upsetting forging, the inner peripheral surface is in contact with the columnar material, and in the second upsetting forging, the end surface of the cylinder member after retreating is in contact with the columnar material together with the surface of the circular member.

  If the forging apparatus of this embodiment is used, the above-mentioned manufacturing method can be implemented. Therefore, production efficiency is unlikely to decrease, and uneven thickness is less likely to occur in the circular material.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated.

[Forging equipment]
FIG. 1 is a front view of a forging device 1 according to the present embodiment. Referring to FIG. 1, forging device 1 includes a pair of molds 2 and 3. The surfaces of the pair of molds 2 and 3 (surfaces that come into contact with the end face of the cylindrical material during upsetting forging, hereinafter referred to as forged surfaces) are arranged to face each other. The mold 2 is arranged coaxially with the mold 3.

  The mold 2 has a disk shape and is disposed above the mold 3. In the mold 2, the lower surface 21 is a forged surface that comes into contact with the end surface of the cylindrical material. The forged surface 21 may be flat, or may have irregularities as shown in FIG. The mold 3 is disposed below the mold 2. The forged surface of the mold 3 is arranged to face the forged surface of the mold 2.

  The forging device 1 further includes a driving device (not shown). The drive device relatively moves at least one of the pair of molds 2 and 3 along the center axis CL of the mold 3. In FIG. 1, the mold 2 is moved up and down by the driving device. However, instead of the mold 2, the mold 3 may be moved up and down, or the mold 2 and the mold 3 may be moved up and down, respectively. By moving the mold 2 and the mold 3 relatively, upset forging is performed on the cylindrical material.

[Mold 3]
FIG. 2 is a plan view of the mold 3 in FIG. With reference to FIGS. 1 and 2, the mold 3 includes a circular member 4 and a cylindrical member 5.

  The transverse shape of the circular member 4 (the cross-sectional shape perpendicular to the central axis of the circular member 4) is a circle. In FIGS. 1 and 2, the circular member 4 has a disk shape and is disposed on a columnar base 6. However, the circular member 4 may have a columnar shape formed integrally with the base 6. The surface 41 of the circular member 4 is in contact with the end surface of the cylindrical material. Therefore, the surface 41 is a forged surface. The surface 41 may be flat or may have irregularities as shown in FIGS.

  The circular member 4 is disposed coaxially with the tubular member 5 and is disposed within the tubular member 5. In other words, the cylindrical member 5 is disposed around the outer peripheral surface of the circular member 4. Therefore, the outer diameter of the circular member 4 is smaller than the inner diameter of the cylindrical member 5.

  The cylindrical member 5 is a cylindrical member and includes an inner peripheral surface 51 and an end surface 52. The inner peripheral surface 51 has a circular cross section. The end surface 52 is connected to the upper end of the inner peripheral surface 51 and is disposed to face the surface (forged surface) 21 of the mold 2.

  In FIG.1 and FIG.2, the cross-sectional shape of the outer peripheral surface of the cylinder member 5 is a circle. However, the transverse shape of the outer peripheral surface of the cylindrical member 5 may not be a circle. The outer peripheral surface of the cylindrical member 5 may be polygonal or rectangular. In the cylindrical member 5, the cross-sectional shape of the inner peripheral surface 51 may be a circle, and the shape of the outer peripheral surface is not particularly limited.

  The forging device 1 further includes a slide device 7. The slide device 7 moves the cylindrical member 5 forward or backward relative to the circular member 4 in the direction of the central axis CL.

  In FIG. 1, the slide device 7 is connected to the cylindrical member 5. Specifically, the slide device 7 is connected to an end surface 53 opposite to the end surface 52. As shown in FIG. 3, the slide device 7 advances the cylindrical member 5 along the central axis CL so that the cylindrical member 5 protrudes toward the mold 2 from the circular member 4. The slide device 7 further retracts the protruding cylindrical member 5.

  The slide device 7 shown in FIG. 1 is, for example, a hydraulic or electric cylinder and includes a cylinder rod 71. However, the slide device 7 is not limited to hydraulic and electric cylinders. The slide device 7 may slide the cylinder member 5 up and down by a crank mechanism, or may slide the cylinder member 5 up and down by another mechanism.

  The slide device 7 may not slide the cylinder member 5 directly. For example, the cylindrical member 5 may be arranged on another member, and the cylindrical member may slide up and down by the slide device 7 sliding on this separate member. In short, the slide device 7 slides the cylindrical member 5 directly or indirectly (via another member).

  As described above, the mold 3 includes the cylindrical member 5 that can slide along the central axis CL. By causing the cylindrical member 5 to advance and protrude toward the mold 2 side, the inner peripheral surface 51 restrains the columnar material during upset forging and suppresses the occurrence of uneven thickness. Furthermore, the protruding cylindrical member 5 is retracted to extract the cylindrical member from the columnar material, and the end surface 52 of the cylindrical member 5 after the retracting is used as a forged surface, thereby suppressing a reduction in production efficiency. Hereinafter, the manufacturing method of a circular material is explained in full detail.

[Method of manufacturing circular material]
In the following description, a manufacturing method in the case where the circular material is a railway wheel will be described. However, the manufacturing method of the present embodiment can be applied even if the circular material is other than the railway wheel.

  The manufacturing method of a circular material includes a wasteland forming step, a finish rolling step, and a finish forging step. In the wasteland forming step, upsetting forging is performed a plurality of times on the cylindrical material to produce a forged wasteland having a general shape of a circular material. In the finish rolling step, the forged waste land is rolled by a known rolling method (for example, rolling using a wheel mill). In the finish forging step, a well-known forging is performed on the rolled wasteland to produce a circular material. Hereinafter, the wasteland forming step will be described in detail.

[Rough land forming process]
FIG. 4 is a flowchart of the wasteland forming process. In the wasteland forming step, the first wasteland forming step (S100) and the latter wasteland forming step (S200) are performed. In the first wasteland forming step (S100), upset forging is performed on the cylindrical material to produce an intermediate product. In the later wasteland forming step (S20), upset forging is performed on the intermediate product using a mold different from the die used in the earlier wasteland forming step to produce a forged wasteland having a rough shape of a circular material. To do.

[First half wasteland forming process]
Referring to FIG. 4, in the first wasteland forming step (S100), first, the heated cylindrical material is placed in forging device 1 (S1, placement step). Specifically, as shown in FIG. 5, a heated columnar material 10 is disposed between the pair of molds 2 and 3. The outer diameter of the columnar material 10 to be arranged is smaller than the inner diameter of the cylindrical member 5. Therefore, the lower end surface of the columnar material 10 is in contact with the surface 41. The columnar material 10 is heated by, for example, a known heating furnace.

  In the placement step (S1), the placement position of the columnar material 10 is adjusted using a manipulator (not shown) or the like so that the center axis of the columnar material 10 coincides with the center axis of the mold 3 (that is, the center axis CL). However, it is difficult to arrange the cylindrical material 10 so that the central axis thereof coincides with the central axis CL using a manipulator or the like. Therefore, the central axis of the columnar material 10 may be slightly deviated from the central axis CL.

  Furthermore, the cross-sectional shape of the columnar material 10 may not be a perfect circle. For example, when the columnar material 10 is a round billet manufactured by a continuous casting method, the outer peripheral surface of the columnar material 10 being manufactured may be pushed by a pinch roll of a continuous casting apparatus. In this case, as shown in FIG. 6, a flat portion 15 is formed on the outer peripheral surface of the columnar material 10. In this case, the columnar material 10 has a shape in which the volume is not uniform in the circumferential direction, that is, uneven thickness. The degree of this uneven thickness is hereinafter referred to as “thickness ratio”.

In the present specification, the thickness deviation rate (%) is defined as follows. Referring to FIG. 6, the cylindrical material 10 is divided into 12 parts in the circumferential direction at every 30 ° central angle. In other words, the cylindrical material 10 is divided into 12 parts with the same central angle around the central axis O when viewed from the end face. The divided areas are referred to as areas A1 to A12. The volume of each region Ai (i = 1 to 12) is obtained. Among the obtained volumes, the maximum volume is defined as Vmax, and the minimum volume is defined as Vmin. Furthermore, the average of the volumes of the regions A1 to A12 is defined as Vave. Using Vmax, Vmin, and Vave, the thickness deviation rate (%) is defined by the following equation (1).
Uneven thickness ratio = (Vmax−Vmin) / Vave (1)

  If the center axis of the columnar material 10 is arranged to be shifted from the center axis CL, or if the thickness ratio of the columnar material 10 is high, uneven thickness tends to occur in the forged rough ground after the rough ground forming step. If uneven thickness occurs in the forged wasteland, uneven thickness remains in the circular material that is the final product. Therefore, in order to suppress the occurrence of uneven thickness in the circular material, it is preferable to suppress the occurrence of uneven thickness in the forged rough land. In the manufacturing method of the present embodiment, the uneven thickness ratio of the forged wasteland can be suppressed by the steps described below.

  After the columnar material 10 is arranged between the pair of molds 2 and 3 in the arrangement step (S1), the cylindrical member 5 is protruded (S2 in FIG. 4, protruding step). Specifically, as shown in FIG. 7, the cylindrical member 5 is moved forward (raised in FIG. 7) using the slide device 7, and the cylindrical member 5 protrudes toward the mold 2 side from the circular member 4.

  As described above, the outer diameter of the columnar material 10 is smaller than the inner diameter of the cylindrical member 5. Therefore, the lower part of the columnar material 10 is accommodated in the protruding cylindrical member 5. Therefore, the inner peripheral surface 51 of the cylindrical member 5 is disposed around the outer peripheral surface of the lower part of the columnar material 10.

  Subsequently, upset forging is performed on the columnar material 10 (S3 in FIG. 4, first upset forging step). In the present embodiment, the mold 2 is lowered downward by a driving device (not shown) while the mold 3 (the circular member 4 and the cylindrical member 5) is fixed. Thereby, the columnar material 10 is compressed in the axial direction and spreads in the radial direction. As a result, as shown in FIG. 8, the outer peripheral surface of the upset forged columnar material 10 contacts the inner peripheral surface 51 of the cylindrical member 5.

  In the first upsetting forging step (S3), the outer peripheral surface of the columnar material 10 is brought into contact with the inner peripheral surface 51 of the cylindrical member 5 by upsetting forging. Therefore, the cylindrical member 5 restrains the columnar material 10 during upset forging. The columnar material 10 is deformed while being restrained by the cylindrical member 5. Therefore, the deviation of the central axis (displacement between the central axis of the cylindrical material 10 and the central axis CL) generated when the cylindrical material 10 is arranged is improved. Further, the uneven thickness generated in the columnar material 10 itself is also improved by the restraint of the cylindrical member 5. Due to the restraint of the cylindrical member 5, the thickness deviation rate of the intermediate product manufactured in the first upsetting forging process is lowered.

  The amount of rolling for upsetting forging in the first upsetting forging step (S3) may be set in advance. Moreover, the internal pressure or thrust force which acts on the cylinder member 5 by the contact of the columnar material 10 may be obtained, and the reduction amount may be adjusted according to the obtained internal pressure. In this case, for example, a strain gauge is disposed on the cylindrical member 5. The reduction amount may be adjusted by the reduction load applied to the mold 2 or the mold 3. In short, the method for adjusting the amount of reduction during upsetting forging is not particularly limited.

  Preferably, at the end of the first upsetting forging step, the entire outer periphery of the columnar material 10 contacts the inner surface 51 of the cylindrical member 5 when the columnar material is viewed from the central axis direction. The contact degree of the outer periphery of the columnar material 10 may be different depending on the position of the outer peripheral portion. For example, when the cylindrical material itself has uneven thickness, the portion where the volume is biased is in strong contact with the inner surface 51 of the cylindrical member 5, and the portion opposite to the portion where the volume is biased is slightly different from the inner surface 51 of the cylindrical member 5. It may be in contact with. In this case, uneven thickness is further improved.

  The sliding amount (movement amount) of the cylindrical member 5 in the projecting step (S2) is, for example, the amount of reduction of the upset forging in the first upsetting forging step (S3) (the relative moving distance of the mold 2 or the mold 3). Set accordingly. In the first upset forging step (S3), after the upset forging is performed, the movement of the mold 2 is stopped (that is, upset forging is temporarily stopped).

  Subsequently, the protruding cylindrical member 5 is retracted and pulled out from the columnar material 10 (S4 in FIG. 4, storage step). Specifically, as shown in FIG. 9, the protruding cylindrical member 5 is moved backward by the slide device 7. Since the cylindrical member 5 is in contact with the cylindrical material 10, the cylindrical member 5 is pulled out of the cylindrical material 10 by retracting the cylindrical member 5.

  Preferably, as shown in FIG. 9, the cylindrical member 5 is retracted until the cylindrical member 5 does not protrude from the circular member 4. More specifically, the inner edge 521 of the end surface 52 of the cylindrical member 5 is located at the same position as the outer edge 411 of the surface 41 of the circular member 4, or the outer edge 411 is closer to the mold 2 than the inner edge 521. The end surface 52 of the cylindrical member 5 is disposed. In this case, in the second upsetting forging step of the next step, the deformed columnar material 10 can spread more smoothly in the radial direction. In FIG. 9, the cylindrical member 5 is retracted until the inner edge 521 of the end surface 52 is located at the same position as the outer edge 411 of the surface 41, and the cylindrical member 5 is stopped.

  After retracting the cylindrical member 5, the second upset forging is performed to produce an intermediate product (S5 in FIG. 4, second upset forging step). Specifically, as shown in FIG. 10, upset forging is performed by moving the mold 2 closer to the mold 3 by a driving device (not shown). At this time, the compressed columnar material 10 further spreads in the radial direction. As a result, the columnar material 10 being deformed contacts not only the surface 41 but also the end surface 52 of the cylinder member 5 after retreating.

  In short, in the second upsetting forging step (S5), not only the surface 41 of the mold 3 but also the end surface 52 is used as the forging surface. By this upset forging, the columnar material 10 further expands in the radial direction, and also extends onto the end face 52 to become the intermediate product 11.

  In the intermediate product 11 manufactured in the first-stage wasteland forming step (S100) including the above steps S1 to S5, the uneven thickness ratio is reduced as compared with the intermediate product manufactured in the conventional first-stage wasteland forming step. This point will be described later using a simulation result.

  After the intermediate product 11 is manufactured, a late wasteland forming process is performed using another pair of molds different from the mold 2 and the mold 3 (S200 in FIG. 4). In the later wasteland forming process, well-known upset forging is performed. In the later wasteland forming step, a forged wasteland having a schematic shape of a wheel is manufactured.

  A well-known finishing process is implemented using the manufactured forged waste land, and the wheel for railways which is a circular material is manufactured. For example, finish rolling is performed on waste land using a wheel mill. After finish rolling, finish forging is performed to produce a circular material.

  In the manufacturing method of the present embodiment described above, the occurrence of uneven thickness in the circular material can be suppressed. FIG. 11 shows the transition of the uneven thickness ratio of intermediate products during each manufacturing process in the conventional wasteland forming process (hereinafter referred to as a comparative example) and the wasteland forming process of the present embodiment (hereinafter referred to as an example). FIG. FIG. 11 was obtained by the following method.

  In the embodiment, in the first and second upsetting forging steps (S3 and S5) in the first wasteland forming step (S100) and in the latter wasteland forming step (S200), an intermediate between upsetting forging and after upsetting forging. The thickness deviation rate of the product was obtained by the finite element method. Specifically, upset forging of steps S3, S5, and S200 was performed on a cylindrical material by a simulation based on a two-dimensional axisymmetric rigid-plastic analysis. The outer diameter of the columnar material 10 was 450 mm, and the thickness deviation rate of the columnar material 10 was 3%. The inner diameter of the cylindrical member 5 of the mold 3 was 500 mm. For the simulation, the outer diameter of the circular member 4 is the same as the inner diameter of the cylindrical member 5. The forged surfaces of the mold 2 and the mold 3 have a shape with some unevenness as shown in FIG. In the later wasteland forming step S200, a pair of molds different from the mold 2 and the mold 3 set in the earlier wasteland forming step (S3 and S5) were set.

  A simulation was performed based on the above conditions. The amount of movement from the initial position of the mold 2 at the end of the first upsetting forging step (S3) (hereinafter referred to as the amount of reduction) is D1, and the amount of reduction at the end of the second upsetting forging step (S5) is D2. And the amount of rolling reduction at the end of the later wasteland forming step (S200) was D3. The thickness deviation rate (%) of the columnar material 10 (intermediate product) after the steps S3, S5 and S200 was determined based on the formula (1).

  In the comparative example, the upper mold used in the previous wasteland forming process was the same shape as the mold 2 of the example. The lower mold has the same shape as the mold 3 of the embodiment, but the circular member and the cylindrical member are not separate members but are integrated.

  In the comparative example, the upset forging was carried out once with D2 as the amount of reduction in the wasteland forming step. Then, the latter wasteland molding was implemented on the same conditions as an Example using the same metal mold | die as the latter wasteland formation process of an Example. And the uneven thickness rate (%) after the first wasteland forming step and after the latter wasteland forming step was determined based on the formula (1).

  In both Examples and Comparative Examples, the uneven thickness ratio of the columnar material before forming the wasteland was set to 5.3%. Among these, the thickness deviation rate resulting from the shape of the cylindrical material itself was set to 3.0%. Further, the thickness deviation rate due to the deviation between the center axis of the cylindrical material and the center axis CL of the mold was set to 2.3%. The thickness deviation due to the deviation of the central axis was defined by the following method. A cylindrical material was divided into 12 parts every 30 ° of the central angle around the central axis CL of the pair of molds. The thickness deviation rate defined by equation (1) using each region Ai was defined as the thickness deviation rate due to the deviation of the central axis.

  FIG. 11 was obtained by plotting the uneven thickness ratio in each step of the example and the comparative example obtained under the above conditions. The solid line in FIG. 11 shows the thickness deviation rate (%) of an Example, and a broken line shows the thickness deviation rate (%) of a comparative example. The horizontal axis in FIG. 11 indicates the amount of reduction (mm). A vertical axis | shaft shows the thickness deviation rate (%) defined by Formula (1). Numerical values described in the vicinity of the circles (black circles and white circles) in the figure indicate the thickness deviation rate (%) at each circle mark position. The white circles in the reduction amounts D1, D2, and D3 indicate the uneven thickness rate (%) of the example, and the black circles indicate the uneven thickness rate (%) of the comparative example.

  Referring to FIG. 11, in the example, the cylindrical material 10 was compressed while being restrained by the tubular member 5 in the first upsetting forging step (S3). Therefore, the uneven thickness ratio of the example at the reduction amount D1 (at the end of the first upsetting forging process) was significantly reduced as compared with the comparative example. Therefore, the uneven thickness ratio (1.0% and 0.3%) of the examples after the first wasteland forming step (the reduction amount D2) and after the latter wasteland forming step (the reduction amount D3) are the uneven thickness ratios of the comparative example ( 2.7% and 0.9%).

  As described above, in the manufacturing method of the present embodiment, the uneven thickness ratio of the forged waste land after the waste land forming step can be significantly reduced. In the circular material manufacturing process, it is possible to correct the uneven thickness to some extent in the so-called lower processes such as the finish rolling process and the finish forging process. A big influence. In the present embodiment, the cylindrical member 10 restrains the columnar material 10 being deformed in the upper step (the wasteland forming step) during the manufacturing process, more specifically, in the first upsetting forging step (S3). Thereby, the uneven thickness rate of a forge wasteland is made low. Therefore, it is possible to manufacture a circular material with a low thickness deviation rate.

  In the present embodiment, the end face 52 of the cylinder member 5 after retreating is used as a forging surface together with the surface 41 of the circular member 4 in the second upsetting forging step (S5). If the end surface 52 is not used as a forged surface, only the circular member 4 is used as the mold 3. In this case, if an intermediate product 11 having a shape as shown in FIG. 10 is to be manufactured, the outer diameter of the circular member 4 must be increased. As the outer diameter of the circular member 4 increases, the inner diameter of the cylindrical member 5 also increases. If the inner diameter of the cylindrical member 5 is increased, the inner peripheral surface of the cylindrical member 5 is less likely to contact the columnar material 10 in the first upset forging step (S3). Therefore, the cylindrical member 5 cannot restrain the column material 10 being deformed, and uneven thickness occurs.

  Further, after correcting the uneven thickness of the columnar material 10 using the cylindrical member 5 having an appropriate inner diameter (S3), the cylindrical member 5 is further lowered from the position shown in FIG. 10 and the second upsetting forging process is performed. When doing so (S4), only the circular member 4 is used as the mold 3. In this case, the outer edge portion of the upset forged columnar material 10 is deformed so as to warp outward from the outer edge of the columnar member 4. Therefore, the intermediate product 11 does not have an appropriate shape.

  In the present embodiment, because the end surface 52 of the cylindrical member 5 is used as the forged surface during the second upsetting forging step (S5), the inner diameter of the cylindrical member 5 is the columnar material during the first upsetting forging (S3). 10 can be of an appropriate size that can be restrained. And the 2nd upsetting forge process can be rapidly implemented by retracting the cylinder member 5. FIG. Therefore, a decrease in production efficiency is suppressed.

  In the present embodiment, the cylindrical member 5 is slid in the axial direction of the mold 3 and the cylindrical member 5 is easily pulled out from the columnar material 10. Therefore, it is not necessary to divide the cylindrical member 5 in the circumferential direction in order to pull it out, and the cylindrical member 5 can be formed integrally. If the cylindrical member 5 is formed integrally, the rigidity of the cylindrical member 5 can be increased, and the columnar material 10 can be more effectively restrained.

  Preferably, the inner diameter of the cylindrical member 5 increases toward the opposing mold 2 side. For example, in FIG. 12, the inner peripheral surface 51 has a tapered shape (taper half angle A1 °). In this case, the inner diameter D52 at the end face 52 is larger than the inner diameter D53 at the end face 53. In this case, it becomes easier to pull out the cylindrical member 5 from the columnar material 10 in the storing step (S4). In FIG. 12, the longitudinal shape (cross-sectional shape in the direction of the central axis CL) of the inner peripheral surface 51 is a straight line. However, if the inner diameter of the cylindrical member 5 is larger toward the mold 2, the longitudinal shape of the inner peripheral surface 51 is not particularly limited. For example, the longitudinal shape of the inner peripheral surface 51 may be a curve. In addition, as shown in FIG. 1 etc., even if the internal diameter of the cylinder member 5 is constant, the cylinder member 5 can be extracted from the columnar material 10.

  The end surface 52 may be flat or may have irregularities. The end face 52 may not be inclined with respect to the surface 41 and may be disposed substantially parallel to the surface 41.

  Preferably, the end surface 52 is inclined to the outside of the cylindrical member 5 as shown in FIG. More specifically, the end surface 52 is disposed away from the mold 2 from the inner peripheral surface 51 side toward the outer peripheral surface side of the tubular member 5. In this case, when the columnar material 10 spreads in the radial direction in the second upsetting forging step (S5), it is difficult for a part of the columnar material 10 being deformed to enter the gap between the circular member 4 and the cylindrical member 5. Furthermore, since the end face 52 is inclined outward, the scale of the columnar material 10 is easily removed to the outside of the mold 3 during the second upsetting forging step (S5).

  Preferably, when the cylindrical member 5 is retracted in the storing step (S4), the outer edge 411 (see FIG. 9) of the surface 41 of the circular member 4 is closer to the mold 2 side than the inner edge 521 of the end surface 52 of the cylindrical member 5. The cylindrical member 5 is arranged so as to be. In this case, the circular member 4 slightly protrudes toward the mold 2 side than the cylindrical member 5. Therefore, in the second upsetting forging, when the columnar material 10 spreads in the radial direction, a part of the columnar material 10 being deformed hardly enters the gap between the circular member 4 and the cylindrical member 5.

  In the above-described embodiment, the mold 2 is lowered by a drive device (not shown), the mold 3 after the cylindrical member 5 is slid is fixed, and upset forging is performed. However, as long as one of the pair of molds 2 and 3 is moved relative to the other to perform upset forging, the relative movement method of the mold 2 or 3 is not particularly limited. For example, upsetting forging may be performed by fixing the mold 2 and sliding the mold 3 in the direction of the central axis CL. Further, upset forging may be performed by sliding the mold 2 and the mold 3 in the direction of the central axis CL.

  In the above-described embodiment, the slide device 7 moves the cylindrical member 5 forward or backward to project the cylindrical member 5 with respect to the circular member 4 or return it to the original state. However, the slide device may move the circular member 4 forward or backward so that the cylindrical member 5 protrudes from the circular member 4. In short, if the cylindrical member 5 is moved forward or backward relative to the circular member 4, the cylindrical member 5 can protrude from the circular member 4, and is arranged so as not to protrude from the circular member 4. You can also.

  In the above-described embodiment, in the first wasteland forming step (S100), the cylindrical material 10 is first disposed between the molds 2 and 3 (S1), and then the cylindrical member 5 is slid and protruded (S2). However, the cylindrical material 10 may be disposed between the mold 2 and the circular member 4 after protruding the cylindrical member 5 first.

  In the above-described embodiment, after the upsetting forging in the first upsetting forging process is temporarily stopped, the cylindrical member 5 is retracted and pulled out from the columnar material 10. However, while continuing upsetting forging, the cylindrical member 5 may be pulled out from the columnar material 10, and the second forging process may be continued. In short, it is not necessary to stop upsetting forging before the tubular member 5 is retracted and pulled out from the columnar material 10.

  In the above-described embodiment, the mold 3 corresponding to the lower mold among the pair of molds 2 and 3 includes the circular member 4 and the cylindrical member 5. However, at least one of the pair of molds 2 and 3 may be provided with a circular member and a cylindrical member. For example, as shown in FIG. 13, the mold 2 corresponding to the upper mold may include a circular member 23 and a cylindrical member 22. The configurations of the circular member 23 and the cylindrical member 22 are the same as those of the circular member 4 and the cylindrical member 5. Even if the forging apparatus having the configuration of FIG. 13 is used, the same waste land forming process as that of FIG. 4 can be performed.

  As shown in FIG. 14, both the mold 2 and the mold 3 may include circular members 23 and 4 and cylindrical members 22 and 5. In this case, the first upset forging step (S3) may be carried out after protruding the cylindrical member 22 of the mold 2 and the cylindrical member 5 of the mold 3 together. Even in such a manufacturing process, the occurrence of uneven thickness of the forged wasteland is suppressed as in the above-described embodiment.

  In the case of using a forging device provided with a pair of molds 2 and 3 shown in FIG. 14, a forged waste land having a flange can also be manufactured. For example, in the first upsetting forging step (S3), the arrangement of the cylindrical member 22 and the cylindrical member 5 is set so that the upsetting forging ends with a gap provided between the cylindrical member 22 and the cylindrical member 5. . In this case, in the first upsetting forging step (S3), a part of the columnar material 10 protrudes from the gap between the cylindrical members 22 and 5, and an intermediate product with a flange is manufactured.

  In the above-mentioned embodiment, the manufacturing method in case a circular material is a wheel for railways was illustrated. However, even when the circular material is a member other than the wheel (gear, ring, etc.), the above-described waste land forming step (FIG. 4) is performed to suppress the decrease in productivity and the uneven thickness rate. Low circular material can be produced.

  The embodiment of the present invention has been described above. However, the above-described embodiment is merely an example for carrying out the present invention. Therefore, the present invention is not limited to the above-described embodiment, and can be implemented by appropriately changing the above-described embodiment without departing from the spirit thereof.

DESCRIPTION OF SYMBOLS 1 Forging device 2, 3 Die 4 Circular member 5 Cylindrical member 7 Slide device 10 Cylindrical material 51 Inner peripheral surface 52 End surface

Claims (4)

A manufacturing method for manufacturing a circular material by performing upset forging on a cylindrical material,
1st and 2nd metal mold | die arrange | positioned facing each other, The said 1st metal mold | die has an inner peripheral surface whose cross-sectional shape is a circle | round | yen, and the end surface arrange | positioned facing the said 2nd metal mold | die. Between the first and second molds of the forging device, which is smaller than the inner diameter of the cylindrical member, and a circular member disposed in the cylindrical member coaxially with the cylindrical member. Arranging a cylindrical material having an outer diameter;
A step of advancing the cylindrical member relative to the circular member and projecting it toward the second mold side than the circular member;
After projecting the cylindrical member, performing upset forging on the columnar material, contacting the columnar material with the inner peripheral surface of the cylindrical member;
After the cylindrical material comes into contact with the inner peripheral surface, the protruding cylindrical member is retracted relative to the circular member, and the cylindrical member is pulled out of the cylindrical material;
And a step of performing upset forging on the columnar material after pulling out the cylindrical member, and bringing the columnar material into contact with the end surface of the cylindrical member after retreating. The manufacturing method according to claim 1,
The inner diameter of the said cylinder member is a manufacturing method which becomes large toward the said 2nd metal mold | die. It is a manufacturing method of Claim 1 or Claim 2, Comprising:
The manufacturing method in which the end surface of the cylindrical member is inclined outward of the cylindrical member. It is a manufacturing method given in any 1 paragraph of Claims 1-3,
In the step of retracting the cylindrical member, the end surface of the cylindrical member is disposed so that an outer edge of the surface of the circular member is closer to the second mold side than an inner edge of the end surface of the cylindrical member. Production method.

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