JP5704635B2 - Metal strip compression bending method - Google Patents

Description

  The present invention relates to a so-called arm turning type (arm rotation type) metal strip compression bending method, and in particular, when bending a straight metal strip while locally heating, thrust and compression force. TECHNICAL FIELD The present invention relates to a technique for preventing neck breakage that may occur due to a problem.

  A typical example of a metal strip to be bent is a metal tube such as a steel pipe, and a typical example of a metal strip bending is high-frequency bending using induction heating for local heating, and arm turning is applied to it. The arm swivel type high-frequency bending process (see, for example, Patent Documents 1 to 7) applies a circular local induction heating and bending moment to a metal pipe such as a steel pipe to sequentially bend the heating part in a moving manner. It is a technology to process. The bending moment is generated by the cooperative action of the front end side path regulation by the swing arm and the propulsion from the rear end side by the pusher.

  Such a metal pipe bending apparatus is provided with a heat treatment mechanism and a bending moment applying mechanism. The heat treatment mechanism includes an inductor that inductively heats a short section in the longitudinal direction of a metal tube to be bent, a cooling mechanism that cools the heated portion, a high-frequency power source that supplies power to the inductor, a cooling mechanism and an induction The water supply equipment for supplying water to the child is provided, and the bending moment adding mechanism includes a swivel arm that regulates the path on the leading side of the metal pipe to be bent in an arc shape and propels the metal pipe from the rear end side. There are pushers. Further, in the compression bending process in which the metal pipe is bent while applying a compression axial force, a compression axial force adding mechanism such as a tension mechanism using a brake or a compression chain is provided to generate a force that resists the turning motion of the turning arm. Note that the leading side of the metal tube corresponds to the tip side of the metal tube in one-time bending, but the unclamping portion corresponds to the second and subsequent times in a plurality of bending processes involving holding.

  The metal tube is clamped and fixed to the swivel end of the swivel arm, and is subject to path regulation by the swivel arm. At that time, a moment acts on the preceding clamp as a reaction of applying a bending moment to the metal tube. Further, in the compression bending process, the moment acting on the preceding side clamp increases as a reaction of applying the compression axial force to the metal pipe. Therefore, in order to perform a good bending process, it is necessary to clamp firmly so that the fixed state does not go wrong due to the moment, and the end of the metal tube is attached to the turning end of the turning arm, the upper part of the pusher, etc. A tube end clamp for gripping is provided.

  The tube end clamp is a so-called tube-in-diameter expanded diameter clamp that is inserted into the hollow of a metal tube to be bent and expands to hold the inner surface of the tube (see, for example, Patent Documents 3, 5, and 7), This is embodied by a so-called tube outer surface gripping clamp (see, for example, Patent Documents 1, 2, 4, and 6) in which the metal tube is held in pressure contact with the outer peripheral surface of the metal tube to be bent. Of the tube end clamps, the leading side clamp is usually mounted so as to be relatively movable with respect to the swivel arm via a slide bed or the like, and among the tube end clamps, the rear end side clamp is fixedly mounted on a pusher. Among them, the former in-tube diameter-increasing clamp is limited in application to holding the end of the tube.

  On the other hand, the latter outer gripping clamp can be applied not only to a tubular body but also to a solid strip material. Also, the bending process is temporarily interrupted and the bending-processed strip portion and the bending process waiting strip are suspended. Since it is also possible to bring the strip material back to the material portion, it can also be applied to a bending process in which the bending direction such as so-called S-shaped bending or three-dimensional bending is changed in the middle. In addition, the latter outer gripping clamp is a clamp in which the ring body is divided vertically so that it can be adapted to strips of various outer diameters even when attached to the turning end of the turning arm. A liner is often used in combination (see, for example, Patent Document 4). Since the clamp liner is inserted between the inner peripheral surface of the clamp and the outer peripheral surface of the strip, and fills the annular / cylindrical gap between them, if the outer diameter of the strip to be processed changes, It can be replaced with a liner with a matching inner diameter.

  In addition, as described above, the metal pipe bending method is classified into a compression bending process in which a compression axial force is applied to the metal pipe and a simple push bending process in which a compression axial force is not applied to the metal pipe. Classification is also based on the ratio of the radius ratio to the radius of the tube, and it is also classified by the difference at the beginning and end of the bending process. That is, simple bending with a constant bending radius from the beginning to the end, gradation bending that gradually decreases or gradually increases the bending radius at the beginning and end (see, for example, Patent Documents 1 and 2), and heat treatment without bending at the beginning and end. It is classified as a bending with a straight pipe part (see, for example, Patent Document 3). Even with simple bending, straight pipe parts remain at both ends of the metal pipe, but with straight pipe bending, heat treatment is applied to the straight pipe part in the same way as with curved pipe parts, but with straight bending, Is not clearly heat treated.

  By the way, if the radius ratio is reduced by compression bending, the moment acting on the leading clamp increases, and if it becomes excessive, the portion of the metal tube that is strongly pressed by the end of the leading clamp is not effective. The metal tube is bent undesirably, or the metal tube is bent undesirably there. Such neck breakage of the metal pipe not only increases the moment of the cause of neck breakage when the thrust of the pusher or the compression axial force of the compression axial force application mechanism increases, but also increases the distance between the heating part and the clamping part. Since the moment of occurrence of bending increases, neck bending is likely to occur when the bending angle is large, and neck bending is more likely to occur when bending with a straight pipe portion. Further, in gradation bending, neck bending is less likely to occur during simple bending than during simple bending while bending radius is gradually increased in the initial stage of bending.

In order to prevent the so-called neck breakage of such an undesired metal tube, the load applying device applies a load toward the bending center to the metal tube being bent. A so-called canceling load imparting type has been put into practical use in which a part of the excessive moment is canceled to keep the moment within an allowable range (see, for example, Patent Document 6).
Also, after using both the tube outer surface grip clamp and the tube insertion diameter expansion clamp, both clamp ends are shifted in the longitudinal direction of the metal tube so that the positions of the ends of the metal tube near the center do not overlap. A so-called inner / outer clamp combination type has also been developed that prevents the metal pipe from being broken by clamping in a state (see, for example, Patent Document 7).

Japanese Patent Publication No. 56-001165 (S53-076158A) Japanese Patent Publication No.62-018245 (S56-045220A) Japanese Examined Patent Publication No. 02-047290 (S61-007020A) JP 2008-264840 A JP 2009-050903 A Japanese Patent No. 3860065 (P2003-320421A) Japanese Patent Application No. 2009-287404

  Furthermore, in order to meet the demand to reduce the remaining part of the metal tube without heat treatment, the heat treatment mechanism is brought closer to the preceding clamp on the swivel arm in the initial stage of bending, but the heat treatment mechanism and the neck break at that time. Since the interference with the prevention mechanism must be avoided, even if there is no interference, the heat treatment must not be undesirably affected, and the neck breakage is unlikely to occur at the initial stage of bending. In the load application type, even if the straight part near the leading side clamp in the tip part of the metal tube belongs to the weight application range, it is outside the suitable weight application range. It is a standard to keep the load applicator away from the heat treatment, and at least the straight part is heat treated, and then the load applicator acts on the metal tube at an appropriate timing thereafter. Is a basis.

Also, in the latter combination type of inner and outer clamps, the inner side expansion / contraction part of the pipe insertion / expansion mechanism is preliminarily reduced in diameter and separated from the inner peripheral surface of the metal tube, and the corresponding part is heat-treated. By expanding the diameter of the metal tube, the neck of the metal tube is prevented.
Thus, in any type, it is possible to appropriately prevent undesired neck breakage during the metal strip compression bending process.

However, since the latter combined type of inner and outer clamps uses an in-tube insertion diameter increasing mechanism, the application target is limited to the end of the tube as described above. In addition, the former offset load application type requires a load application device capable of controlling the load as additional equipment, and additional operations such as load selection and setting are required during operation.
Therefore, it is a technical problem to realize a metal strip compression bending method that does not require such a thing and is simple and has a wide application range.

  The metal strip compression bending method of the present invention (Solution 1) was devised to solve such a problem, and the metal strip to be bent is locally plastically deformed in an annular shape. In a metal strip compression bending method in which heating is performed to a possible temperature, a bending moment and a compression axial force are applied to the heating portion while moving the heating portion relative to the longitudinal direction of the strip, and cooling is performed immediately thereafter. An attachment engaging means is provided in advance on the preceding clamp mounted on the pivoting portion of the arm, and the outer periphery of the strip member is engaged with the clamp engaging means corresponding to the attachment engaging means and the both engaging means. A neck breakage preventing attachment having a strip contact portion that abuts against a portion of the surface where the contact pressure increases or decreases in accordance with increase or decrease of neck bending deformation is separated from the preceding clamp and the strip. The bending material and the compression axial force are generated by gripping the leading side of the strip with the leading side clamp and restricting the path in an arc shape, thereby compressing and bending the strip. The strip material is processed by attaching the attachment for preventing neck breakage to the preceding side clamp by engaging the both engaging means after the separation distance between the heating part and the preceding side clamp is increased. A contact part is made to contact | abut to the outer peripheral surface of the said strip, and the neck bending of the said strip is suppressed.

  Further, the metal strip compression bending method of the present invention is (Solution means 2), which is the metal strip compression bending method of Solution 1, wherein the strip contact portion is applied to the outer peripheral surface of the strip. When the contact is made, the strip contact portion is brought into contact with a portion of the outer peripheral surface of the strip that has been heat-treated by heating and cooling.

  Further, the metal strip compression bending method of the present invention is (Solution means 3), the metal strip compression bending method of the above solution means 1 and 2, wherein the attachment for preventing neck breakage can be added to a plurality of stages. The attachment for preventing neck breakage is added step by step as the separation distance between the heating unit and the preceding-side clamp increases.

  Further, the metal strip compression bending method of the present invention is (Solution means 4), the metal strip compression bending method of the above solution means 1-3, wherein the preceding clamp is mounted on the swivel arm. A clamp body portion that performs a gripping operation, and a detachable clamp liner that is interposed between an inner peripheral surface of the grip body portion and an outer peripheral surface of the strip material, and the attachment The engaging means is provided on either one or both of the clamp body and the clamp liner.

  Moreover, the metal strip compression bending method of the present invention is (Solution means 5), the metal strip compression bending method of the above solution means 1-4, wherein the clamp engaging means of the attachment for preventing neck breakage is provided. The attachment for preventing neck breakage is attached to the preceding clamp by fitting the attachment to the attachment engaging means of the preceding clamp.

  Further, the metal strip compression bending method of the present invention (solution means 6) is the metal strip compression bending method of the above solution means 1 to 4, wherein the both engagement means are engaged by screwing. Thus, the attachment for preventing neck breakage is attached to the preceding side clamp.

  In such a metal strip compression bending method of the present invention (Solution 1), since the neck breakage prevention attachment is not yet mounted at the initial stage of machining where neck breakage does not occur, Heat treatment can be applied to the vicinity of the grip-type leading clamp. And since the separation distance between the heating part and the preceding side clamp increases before or after the start of the bending process, the neck breakage prevention attachment is attached to the preceding side clamp. If the attachment spreads more than the attachment for preventing neck breakage, the attachment work for preventing neck breakage can be attached before the moment causing the neck breakage becomes excessive.

Since the attachment for preventing neck breakage after mounting rotates together with the preceding side clamp, it keeps contacting the strip material contact portion with the strip material without moving relative to the strip material. And when a strip material is going to bend and deform | transform, a neck action of a strip material is suppressed by the passive effect | action that contact pressure is increased / decreased according to the increase / decrease. An attachment for preventing neck breakage such as an extension member after the leading side clamp is provided with a necessary shape and rigidity, so that it is not necessary to perform active load control using a hydraulic cylinder or the like. Since a movable portion such as a push roller is not required for the contact portion, a fixed shape / constant shape member is sufficient except for the mounting tool and the mounting mechanism.
Therefore, according to the present invention, it is possible to realize a metal strip compression bending method in which the leading side clamp is an outer surface holding type and has a wide application range, and the additional member is fixed and passive, and equipment and work are simple. .

  Moreover, in the metal strip compression bending method of the present invention (solution 2), the neck fracture occurrence site in the strip is moved to the heat-treated site, but the place where the heat treatment has been completed is before the heat treatment due to hardness improvement or the like. Since it is difficult to deform, the function of preventing neck breakage is further enhanced.

  Furthermore, in the metal strip compression bending method according to the present invention (Solution means 3), the attachment work of the neck fold prevention attachment can be performed separately for each easy-to-handle stage, so the attachment work is easy. Become.

  Further, in the metal strip compression bending method of the present invention (Solution means 4), the attachment work of the neck fold prevention attachment is performed on appropriate portions of the clamp main body part and the clamp liner. Even if the work is performed avoiding a heating device or the like so as not to be injured, it can be easily performed.

  Further, in the metal strip compression bending method of the present invention (solution means 5 and 6), the attachment of the neck fold prevention attachment is performed by easy external fitting or screwing even by manual work. Even if the work is not automated, it is possible to work easily and quickly.

About Example 1 of the metal strip compression bending method of this invention, (a) is a schematic plan view which shows the initial state which set the metal pipe to the metal pipe bending apparatus, (b) is the preceding side clamp at that time, etc. (C) is an outline plan view when the straight pipe part is heat-treated, (d) is an enlarged plan view of the preceding side clamp, etc. at that time, (e) is an outline plan view at the start of bending, (F) is a schematic plan view when the attachment for preventing neck breakage is mounted, (g) is an enlarged plan view of the preceding side clamp, etc. at that time, (h) is a schematic plan view when the attachment is added, (i) ) Is an enlarged plan view of the leading side clamp and the like at that time. About Example 2 of the present invention, it shows a metal strip compression bending method to be carried out using an external fitting type anti-bending attachment, (a) is a perspective view of a clamp liner, (b) is a sectional view thereof, (C) is a perspective view of an attachment for preventing neck breakage, (d) is a cross-sectional view thereof, (e) is a cross-sectional view of a leading side clamp or the like when a metal tube is set, and (f) is a state when the attachment for preventing neck breakage is mounted. Sectional drawing of a leading side clamp etc., (g) is sectional drawing of a leading side clamp etc. at the time of attachment addition. About Example 3 of this invention, the metal strip compression bending method implemented using the screwing-type attachment for neck fracture prevention is shown, (a) And (b) of the attachment which concerns on the type which attaches to a clamp main-body part. (C) is a sectional view of a leading side clamp or the like according to a deformation type with a flange, (d) is a sectional view of a leading side clamp or the like according to a type attached to a clamp liner, e) is a cross-sectional view of a leading side clamp or the like according to a type in which an auxiliary attachment is used together, and FIGS.

About the metal strip compression bending method of such this invention, the specific form for implementing this is demonstrated by the following Examples 1-3.
The embodiment 1 shown in FIG. 1 embodies the above-described solving means 1 to 3 (claims 1 to 3 at the beginning of the application), and the embodiment 2 shown in FIG. 5 to 3 (claims 1 to 5 at the beginning of the application), and the third embodiment shown in FIG. 3 is the above-described solving means 1 to 3 and 6 (claims 1 to 3 and 6 at the beginning of the application). ).

  Regarding Example 1 of the metal strip compression bending method of the present invention, prior to the description of the method, the specific configuration of the metal tube bending device 20 (metal strip compression bending device) used for the implementation is described. A description will be given with reference to the drawings. FIG. 1A is a schematic plan view of the metal pipe bending apparatus 20 in an initial state in which the metal pipe 10 has just been set, and FIG. 1B shows a leading side clamp 48 and a neck breakage prevention attachment 50 and the like. FIG. FIG. 11H is a schematic plan view of the neck breakage preventing attachment 50 and the additional attachment 53, and FIG. 10I is an enlarged plan view of the leading side clamp 48 and the additional attachment 53 and the like.

This metal tube bending apparatus 20 (see FIG. 1A) is designed to bend the metal tube 10 while preventing the occurrence of neck breakage, guide rollers 21 and 22, heat treatment mechanisms 23 to 27, and a bending moment. An additional mechanism 30 + 40 and a neck breakage prevention attachment 50 are provided.
The heat treatment mechanisms 23 to 27 include an annular inductor 23, a cooling mechanism 24, a moving mechanism 25, a high frequency power supply 26, and a water supply equipment 27, and a bending moment adding mechanism 30 +40 includes a pusher 30 and a swivel arm 40. Yes.
The swivel arm 40 may be composed of, for example, an L-shaped or I-shaped arm and a pair of slide beds as long as the path on the leading side of the metal tube 10 to be bent can be regulated in an arc shape. It is also possible to increase the rigidity by arranging the top and bottom. A leading side clamp 48 that holds the outer peripheral surface of the leading side of the metal tube 10 to be bent is attached to this.

  The pivot arm 40 includes a vertical support shaft 41, a horizontal arm base end portion 42 supported on the base end thereof, a moving mechanism 43 that moves the support shaft 41 in the Y direction, an arm A rotation mechanism 44 that rotates the support shaft 41 at the time of turning, an arm turning end 46 that is provided on the distal end side of the arm base end portion 42 and can be moved in the Y direction by the moving mechanism 45, and an arm turning end 46 And a moving mechanism 47 for moving the leading side clamp 48 mounted in the X direction in the initial posture, and adding a bending moment necessary for bending deformation of the metal tube 10 to the metal tube 10 and leading in the initial posture. The side clamp 48 can be positioned where the leading side of the metal tube 10 can be gripped, so that the bending radius of the metal tube 10 and the length of the straight tube portion on the leading side of the metal tube 10 can be arbitrarily set. Going on. In order to generate the compression axial force necessary for the compression bending process, the arm tip side may be pulled with a chain or the like. However, in this device, a brake is applied to the rotation mechanism 44 so that the brake resistance force Pb is applied. It has become.

The pusher 30 includes a moving mechanism 31 for moving forward and backward toward the swivel arm 40 and a rear end side clamp 32 for gripping the rear end side of the metal pipe 10 to be bent. The moving mechanism 31 may be a cylinder-driven movable table or a chain-pull-type traveling table as long as it can generate a pusher thrust P that pushes the metal tube 10 from the rear end side to the leading side.
Guide rollers 21, 22, an inductor 23, and a cooling mechanism 24 are disposed between the pusher 30 and the swing arm 40, and the metal tubes 10 are sandwiched between the guide rollers 21 and 22 from both sides. Undesired misalignment between the inductor 23 and the inductor 23 is prevented.

The inductor 23 is an induction coil that is slightly larger than the outer diameter of the metal tube 10 to be bent. When the metal tube 10 is loosely inserted in the hollow state and fed with power from the high-frequency power source 26, the longitudinal direction of the metal tube 10. The short section is inductively heated in a ring shape.
The cooling mechanism 24 is composed of an annular sprinkling tube or the like adjacent to or assembled with the inductor 23, or a tubular body also serving as the inductor 23, and from the water supply equipment 27 in a state where the metal tube 10 is loosely inserted. When the water is supplied, the annular heating portion of the metal tube 10 is followed and cooled.
The moving mechanism 25 moves the inductor 23 and the cooling mechanism 24 together in the X direction, and operates when the straight pipe portion on the leading side of the metal tube 10 is heat-treated by gradation bending or bending with a straight pipe portion. It is supposed to be.

  The neck breakage prevention attachment 50 (see FIGS. 1A and 1B) is attached to the preceding clamp 48 to prevent neck breakage, and is provided with a clamp engaging means near the leading clamp 48. 51 is provided. Although omitted in the above description, it was turned later, but the attachment engagement means 49 corresponding to the clamp engagement means 51 is provided in advance in a portion of the leading side clamp 48 where the attachment 50 for preventing neck breakage is attached. Yes. Both engaging means 49 and 51 are not particularly limited as long as they can be engaged after the machining operation is started and can withstand a reaction force necessary for preventing neck breakage at the time of engagement. It may be a latching type, a clamping type, a holding type, or a device to which a mounting tool such as a bolt or a wedge is added.

  Further, the neck breakage prevention attachment 50 is also provided with a strip material contact portion 52, and when the above-mentioned engagement means 49, 51 are engaged to attach the neck breakage prevention attachment 50 to the preceding clamp 48. The strip material contact portion 52 contacts the outer peripheral surface of the metal tube 10. In addition, at least a portion of the attachment 50 for preventing neck breakage that extends between the clamp engaging means 51 and the strip contact portion 52 is made of a rigid fixed member, and the strip contact portion 52 is broken in the neck folding direction. It will not be easily deformed even if it is pushed by. Since the strip contact portion 52 is a place where a reaction force necessary for preventing neck breakage is generated in response to the strong force of neck breakage, it has a wider surface than a narrow dot or thin line It is better if it fits the outer peripheral surface of the metal tube 10.

  Further, the metal pipe bending apparatus 20 is also provided with an additional attachment 53 which is a second stage when the neck breakage preventing attachment 50 is a first stage (see FIGS. 1 (h) and (i)). . The extension attachment 53 extends the neck breakage prevention attachment 50 and extends the contact portion between the neck breakage prevention attachment 50 and the metal tube 10 in a direction far from the preceding clamp 48. Engaging means that can be retrofitted to the prevention attachment 50, and a strip abutting portion that abuts on the outer peripheral surface of the metal tube 10 and produces a reaction force necessary to prevent neck breakage after the attachment. .

With respect to the metal strip compression bending method of the first embodiment, a procedure for performing compression bending processing on the metal tube 10 using the above-described metal tube bending device 20 will be described with reference to the drawings.
Here, bending with a straight pipe portion is performed. That is, in the first step, only the heat treatment is performed without bending the leading side of the metal tube 10, and the heat treatment is performed while bending in the subsequent steps.

  1A is a schematic plan view showing an initial state in which the metal tube 10 is set in the metal tube bending apparatus 20, FIG. 1B is an enlarged view of the leading side clamp 48 and the like at that time, and FIG. Outline plan view when the tube part 11 is heat-treated, (d) is an enlarged plan view of the preceding clamp 48, etc. at that time, (e) is an outline plan view at the start of bending, and (f) is for preventing neck breakage. An outline plan view when the attachment 50 is attached to the preceding side clamp 48, (g) is an enlarged plan view of the leading side clamp 48 and the like at that time, and (h) is added to the attachment 50 for preventing neck breakage and an attachment 53 is added. A schematic plan view at the time, (i) is an enlarged plan view of the leading side clamp 48 and the like at that time.

  Prior to the bending process, the metal tube 10 is set in the metal tube bending apparatus 20. First, the metal tube 10 is lifted by a crane or the like as usual, and the rear end side of the metal tube 10 is set to the rear end side of the pusher 30. While holding the clamp 32, the tip side (leading side) of the metal tube 10 is held and held by the leading side clamp 48 of the turning arm 40 (see FIG. 1A). The metal tube 10 is also loosely inserted into the inductor 23 and the cooling mechanism 24 in the same manner as when using a conventional clamp on the outer surface of the tube. At that time, the positioning of the metal tube 10 and the preceding clamp 48 may be performed by moving the metal tube 10 with a crane, and the moving mechanism 45, 47 is operated to move the preceding clamp 48. Or they may be used in combination.

In the initial posture of bending with a straight pipe portion (see FIG. 1A), the bending point corresponding to the support shaft 41 of the swivel arm 40 is equal to the length of the straight pipe portion 11 near the leading side clamp 48 in the metal pipe 10. Since the inductor 23 is moved in advance in the X direction from BP (the position of the two-dot chain line in FIG. 1B, etc.) (see FIG. 1A, see the broken line in FIG. 1C), it does not interfere with it. The leading clamp 48 is moved in the X direction by the moving mechanism 47 as close as possible.
At this stage (see FIG. 1 (a)), the neck breakage preventing attachment 50 is placed away from both the preceding clamp 48 and the metal tube 10 so as not to interfere with the set operation described above. Be prepared to use it as soon as you need it.

  When the preparation is completed, the metal pipe bending apparatus 20 is operated in the automatic mode to start bending with the straight pipe portion on the metal pipe 10. Then, high frequency current is supplied to the inductor 23 from the high frequency power source 26, and the metal tube 10 is heated in an annularly locally plastically deformable temperature by the high frequency induction heating, and water is supplied to the cooling mechanism 24 from the water supply equipment 27. The X direction adjacent part of the annular heating part of the metal tube 10 is cooled. In addition, while continuing such heat treatment, first, non-bending processing for forming the straight pipe portion, that is, straight pipe heating is performed (see FIGS. 1C and 1D), and then for forming the bent pipe portion. The bending process is performed while applying a compression axial force (see FIGS. 1E to 1J).

  More specifically, when the straight pipe portion is formed, the inductor 23 moves away from the preceding clamp 48 and moves toward the guide rollers 21 and 22 by moving in the X direction with the swing arm 40 and the pusher 30 stopped (see FIG. 1 (c)), the separation distance between the heat treatment mechanism 23 + 24 and the leading side clamp 48 is increased, and the straight pipe portion 11 near the leading side clamp 48 in the metal tube 10 is heat treated and hardened (FIG. 1 (d)). reference). Then (see FIG. 1 (e)), when the inductor 23 reaches the bending point BP, the heat treatment mechanism 23 + 24 stops moving and stops at the bending point BP. The tip of the metal tube 10 gripped by 48 is restricted in its path to an arc.

  The metal pipe 10 is subjected to compression bending by the bending moment and the compression axial force based on the path restriction, the pusher thrust force P, and the brake resistance force Pb, so that the curved pipe portion 12 is formed. (Refer to FIGS. 1 (f) to (i)), as the swivel arm 40 turns and the bent tube portion 12 grows, the portion of the metal tube 10 close to the preceding clamp 48 as described above. In order to prevent the occurrence of undesired neck breakage, the separation distance between the heat treatment mechanism 23 + 24 and the preceding side clamp 48 is the length of the neck breakage prevention attachment 50. If the separation distance increases to a point where attachment parts around the bending point BP do not interfere with the attachment work for the neck break prevention attachment 50, the neck break prevention attachment 50 Mounting the clamp engagement means 51 and the preceding side attachment engaging means 49 and preventing the attachment 50 folded neck by engaging the clamp 48 on the leading side clamp 48 (see FIG. 1 (f), (g)).

  Then, the strip material contact portion 52 of the neck breakage prevention attachment 50 contacts the outer peripheral surface of the metal tube 10, but the neck breakage prevention attachment 50 is longer than the unheat-treated portion at the tip portion of the metal tube 10. The abutting portion 52 abuts against a portion of the outer peripheral surface of the straight tube portion 11 of the metal tube 10 that has been heat-treated by heating and cooling. Then, as the turning of the swivel arm 40 further progresses and the bent tube portion 12 further grows, the moment to cause an undesired neck break increases further and reaches the conventional neck break occurrence level. There is a neck fold preventing attachment 50 in the neck fold direction, and the more the metal tube 10 is deformed in the neck fold direction, the stronger the contact with the strip material contact portion 52 of the neck fold preventing attachment 50 is. As a result, the reaction force to hold down the deformation increases. In addition, the contact force and reaction force are distributed over almost the entire length of the neck breakage prevention attachment 50, and more specifically, near the bending point BP that has a large canceling effect against the moment of the neck breakage factor. Since a large amount is distributed to the pipe portion 11, the neck breakage of the metal pipe 10 is effectively prevented.

  Furthermore, when the compression bending process of the metal tube 10 progresses, in the case where there is a possibility that the moment of the neck breakage factor may increase to the extent that it cannot be countered by the neck breakage prevention attachment 50 alone (see FIG. 1 ( h) and (i)), and the attachment 53 is added to the attachment 50 for preventing neck breakage. As a result, the deformation site where the neck is to be broken and the dispersion range of the reaction force that keeps the deformation widened, it becomes difficult for local plastic deformation to occur, and it is closer to the bending point BP that has a large canceling effect on the moment of the neck breaking factor. However, more specifically, the metal pipe 10 is more effectively prevented from breaking because it is distributed more in the bent pipe portion 12 after the thickening and hardening.

  A second embodiment of the metal strip compression bending method of the present invention will be described with reference to the drawings, for example, a procedure for mounting the neck fold preventing attachment 50 by external fitting. 2A is a perspective view of a clamp liner for external fitting, FIG. 2B is a cross-sectional view thereof, FIG. 2C is a perspective view of an external fitting-type attachment for preventing neck folding, and FIG. 2D is a cross-sectional view thereof. (E) is a sectional view of the leading side clamp 48 and the like when the metal tube 10 is set, (f) is a sectional view of the leading side clamp 48 and the like when the neck breakage preventing attachment 50 is mounted, and (g) FIG. 6 is a cross-sectional view of the leading side clamp 48 and the like when the addition attachment 53 is added to the neck breakage prevention attachment 50.

  In this metal strip compression bending method, the engagement mounting of the neck breakage prevention attachment 50 of the first embodiment described above to the preceding clamp 48 is embodied by an external fitting method to a clamp liner. That is, as described above (see, for example, Patent Document 4), the clamp 48 is attached to the turning arm 40 and performs a gripping operation, and the inner periphery of the gripping portion of the clamp main body 48a. And a detachable clamp liner 48b interposed between the surface and the outer peripheral surface of the metal tube 10, and the clamp engaging means 51 of the neck breakage preventing attachment 50 is used as the attachment engaging means of the clamp liner 48b. The attachment 50 for preventing neck breakage is attached to the turning arm 40 by being externally fitted to 49.

  More specifically, an attachment engaging means 49 including an annular groove and an annular flange is formed on the outer peripheral surface of one end of the clamp liner 48b (see FIGS. 2A and 2B). (Refer to FIGS. 2 (c) and 2 (d)), a vertically divided two-piece cylindrical body is connected by a hinge part 50a (hinge) and can be easily opened and closed by a handle part 50b (grip). On the inner peripheral surface of one end of the neck breakage prevention attachment 50, a clamp engagement means 51 comprising an annular jaw and an annular groove corresponding to the attachment engagement means 49 is formed. On the outer peripheral surface of the other end, the same thing as the above attachment engaging means 49 is formed in order to serve as the additional attachment 53.

Then (see FIG. 2 (e)), at the time of setting in the initial stage, the metal tube 10 is set to the preceding side clamp 48 with the clamp liner 48b interposed between the distal end side of the metal tube 10 and the clamp body 48a. At this time, the position of the clamp liner 48 is adjusted so that the attachment engaging means 49 of the clamp liner 48b protrudes from the clamp body 48a to the rear end side of the metal tube 10 and is exposed.
Then (see FIG. 2 (f)), when mounting the neck breakage prevention attachment 50, the neck breakage prevention attachment 50 is opened and closed, and the clamp engagement means 51 is put on the attachment engagement means 49, and the fitting is grasped. It fixes by bolting etc. of the parts 50b.
Further (see FIG. 2 (g)), when the attachment 50 for preventing neck breakage is extended, another attachment 50 for preventing neck breakage is used as an attachment 53, and the attachment 53 is opened and closed to open the clamp engaging means 51. It is placed on the attachment engaging means 49, and the fitting is fixed by tightening the bolts between the grip portions 50b.

  A third embodiment of the metal strip compression bending method of the present invention will be described with reference to the drawings, for example, a procedure for attaching a bolt 54 as a mounting tool and mounting the attachment 50 for preventing neck breakage by screwing. 3A is a perspective view of a neck breakage preventing attachment 50 of the type attached to the clamp main body 48a, and FIG. 3B is a cross-sectional view of the leading side clamp 48 and the like attached with bolts 54. FIG. 3C is a cross-sectional view of the leading-side clamp 48 and the like in which the flange-type deformable attachment 50 for preventing the neck breakage is attached with the bolt 54, and FIG. 3D is a bolt for attaching the attachment 50 for preventing the neck breakage to the clamp liner 48b. FIG. 5E is a cross-sectional view of the leading side clamp 48 and the like attached with a bolt 54, and FIG. 5E is a sectional view of the leading side clamp 48 and the like attached with a bolt 54 in addition to the attachment 50 for preventing neck breakage. Further, FIG. 3F is an end view of the reinforcing-type neck breakage preventing attachment 50, and FIG. 3G is a cross-sectional view of the leading side clamp 48 and the like to which the bolt 54 is attached.

  In this metal strip compression bending method, the engagement mounting of the neck breakage prevention attachment 50 of the first embodiment described above to the preceding clamp 48 is embodied by a screwing method with respect to the clamp main body 48a and the clamp liner 48b. Yes. That is, the leading side clamp 48 includes the clamp main body 48a and the clamp liner 48b as in the second embodiment, and the clamp engaging means 51 of the neck breakage preventing attachment 50 is used as the attachment of the leading side clamp 48. The neck breakage preventing attachment 50 is attached to the turning arm 40 by being screwed into the engaging means 49. In addition, although the example which provides the attachment engaging means 49 in the clamp main-body part 48a and the example provided in the clamp liner 48b is given here, the attachment engaging means 49 may be provided over both members 48a and 48b.

  An attachment 50 for preventing neck breakage shown in FIGS. 3 (a) and 3 (b) is composed of a half-cracked hook-shaped member obtained by vertically dividing a cylinder into two, and a bolt engaging hole penetrating in the axial direction is perforated. The combination means 51 is used, and the inner peripheral surface is a strip material contact portion 52. The attachment engaging means 49 corresponding to the clamp engaging means 51 is a female screw and is formed in the clamp main body portion 48a. Therefore, after the male thread portion of the bolt 54 is passed through the clamp engaging means 51, the attachment engaging means 49 is provided. The neck breakage preventing attachment 50 is attached to the preceding side clamp 48 in an implanted state.

The neck breakage prevention attachment 50 shown in FIG. 3 (c) is formed of a deformed bowl-shaped member that is split into two vertically divided flanged pipes, and a bolt insertion hole as a clamp engaging means 51 is formed in the flange portion. Has been.
The neck breakage prevention attachment 50 shown in FIG. 3D is the same as that described above, but the formation site of the attachment engaging means 49 has moved from the clamp body 48a to one end of the clamp liner 48b.

  The neck breakage prevention attachment 50 shown in FIG. 3 (e) is the same as that described above, but the auxiliary attachment 55 is also used. The auxiliary attachment 55 has the same shape as the neck breakage prevention attachment 50 and is similarly attached to the preceding side clamp 48, but the attachment position is opposite to the metal tube 10. The auxiliary attachment 55 alone is not useful for preventing neck breakage because it is opposite to the neck folding direction. However, the auxiliary attachment 55 is connected to the neck breakage preventing attachment 50 so that the neck breakage preventing attachment 50 is broken. If the pulling reaction force is generated in the connecting portion when it is pushed away from the auxiliary attachment 55, the auxiliary attachment 55 reinforces the function of the neck breakage preventing attachment 50. Helps to relieve neck breakage.

  The neck breakage prevention attachment 50 shown in FIGS. 3 (f) and 3 (g) has a rib 50 c formed on the neck fold side, so that the resistance against the neck fold is increased. The rib 50c has a large rigidity near the leading side clamp 48 and a rigidity far from the leading side clamp 48 so as to disperse the deformation of the metal tube 10 in the neck bending direction and thus the reaction force that suppresses the deformation without uneven distribution. Is getting smaller. In addition, the attachment 50 for preventing neck breakage is a flat extension of the split end surfaces on both sides in order to avoid excessive force acting on the contact portion with the preceding clamp 48 and the bolt 54 due to the principle of leverage. After extending by the member 50d to make the end view shape U-shaped, the clamp engaging means 51 is formed at the extended member 50d. Further, the clamp engagement means 51 of the neck breakage prevention attachment 50 is changed from the bolt insertion hole to the female screw so that the bolt 54 can be tightened without the metal tube 10 or the heat treatment mechanism 23 + 24, and the leading side clamp Attachment attachment means 49 of 48 is changed from the female screw, and is a bolt insertion hole that is perforated through the clamp main body 48a.

[Others]
In the above embodiment, the object to be processed was a steel pipe, but the presence of a hollow in the pipe body and the roundness of the outer periphery are not essential for the implementation of the present invention, and heat treatment by moving heating is useful for metals other than steel materials. Since the present invention can be carried out in the same manner as described above, the present invention can also be applied to a compression bending method for metal strips such as solid bars and square bars.
Moreover, in the above embodiment, since the bending with a straight pipe portion is a specific example, in the first stage of the processing work, the action of the bending moment is temporarily stopped and only the heat treatment is performed. It is preferable to perform heat treatment while temporarily relaxing and bending.

Furthermore, in the above embodiment, the brake resistance force Pb that increases the compression axial force is not explicitly applied in the first stage of the machining operation, but the brake resistance force Pb may be applied from the beginning. It is also possible to gradually increase the brake resistance force Pb.
In the above embodiment, only one bending process has been described. However, since the leading side clamp 48 follows the external gripping clamp, the bending process is temporarily interrupted as in the conventional case. Since the metal tube 10 can be re-taken between the finished strip portion and the bending-waiting strip portion, the metal tube bending apparatus 20 can also be applied to a bending process that changes the bending direction such as S-shaped bending or three-dimensional bending. can do.

  The metal strip compression bending method of the present invention is suitable for the above-described bending with a straight pipe portion, but the application is not limited thereto, and it is a compression bending in which the occurrence of neck breakage is a concern and precedes it. Any bending process that heat-treats to the immediate vicinity of the side clamp can also be applied to simple bending. Even if it is a bending with a straight pipe part, some gradation bending may be interposed between the straight pipe heating part and the main bending part, and even if it is a gradation bending, a little straight pipe heating is applied to the end side of the gradation bending part. There may be a part and a preheating part, and even a normal simple bending may have some gradation bending or a straight pipe heating part at the end side of the main bending part, and in any case, the present invention is applied. Can do.

10 ... Metal pipe (strip),
20 ... Metal pipe bending device (metal strip compression bending device),
21, 22 ... guide rollers, 23 ... inductors, 24 ... cooling mechanism,
25 ... Movement mechanism, 26 ... High frequency power supply, 27 ... Water supply equipment,
30 ... pusher, 31 ... moving mechanism, 32 ... rear end side clamp,
40 ... swivel arm, 41 ... spindle, 42 ... arm base end, 43 ... moving mechanism,
44 ... Rotating mechanism, 45 ... Moving mechanism, 46 ... Arm turning end, 47 ... Moving mechanism,
48 ... Leading side clamp, 48a ... Clamp body 48a,
48b ... clamp liners 48b, 49 ... attachment engaging means,
50 ... Attachment for preventing neck breakage, 50a ... Hinge part, 50b ... Handle part,
51 ... Clamp engaging means, 52 ... Strip material contact portion,
53 ... Additional attachment, 54 ... Bolt, 55 ... Auxiliary attachment

Claims (5)

A metal strip to be bent is locally heated to a plastically deformable temperature in an annular shape, and a bending moment and a compressive axial force are applied to the heating portion while moving the heating portion relative to the longitudinal direction of the strip. In the metal strip compression bending method for cooling immediately after that, an attachment engaging means is provided in advance on the preceding side clamp provided in the turning portion of the turning arm, and the clamp engaging means corresponding to the attachment engaging means is provided. Neck break prevention comprising a joint member and a strip contact portion that contacts a portion of the outer peripheral surface of the strip that increases or decreases in contact with the deformation of the neck according to increase or decrease of the neck bending deformation. The front attachment is prepared in a state separated from the preceding side clamp and the strip material, and the front side of the strip material is gripped by the preceding side clamp and the path thereof is regulated in an arc shape. A bending moment and the compression axial force are generated to compress and bend the strip material, and after the separation distance between the heating portion and the preceding clamp is increased, the engagement means are engaged to engage the neck. said elongated member those the contact portion is brought into contact with the outer peripheral surface of said elongated member to suppress the bending neck of the strip material Rukin Shokujo material compression bending method by the bending preventing attachment mounted on the leading side clamp Because
A detachable type in which the preceding clamp is attached to the swivel arm and performs a gripping operation, and is inserted between the gripper inner peripheral surface of the clamp main body and the outer peripheral surface of the strip. of are those equipped with a clamp liner, the attachment engaging means bending either or compression characteristics and be Rukin Shokujo material that is provided in both of said clamping liner and the clamp main body processing Method. A metal strip to be bent is locally heated to a plastically deformable temperature in an annular shape, and a bending moment and a compressive axial force are applied to the heating portion while moving the heating portion relative to the longitudinal direction of the strip. In the metal strip compression bending method for cooling immediately after that, an attachment engaging means is provided in advance on the preceding side clamp provided in the turning portion of the turning arm, and the clamp engaging means corresponding to the attachment engaging means is provided. Neck break prevention comprising a joint member and a strip contact portion that contacts a portion of the outer peripheral surface of the strip that increases or decreases in contact with the deformation of the neck according to increase or decrease of the neck bending deformation. The front attachment is prepared in a state separated from the preceding side clamp and the strip material, and the front side of the strip material is gripped by the preceding side clamp and the path thereof is regulated in an arc shape. A bending moment and the compression axial force are generated to compress and bend the strip material, and after the separation distance between the heating portion and the preceding clamp is increased, the engagement means are engaged to engage the neck. said elongated member those the contact portion is brought into contact with the outer peripheral surface of said elongated member to suppress the bending neck of the strip material Rukin Shokujo material compression bending method by the bending preventing attachment mounted on the leading side clamp Because
Features and to Rukin that mounting the neck bending preventing attachment by externally fitted the clamp engagement means of the neck bending preventing attachment to said attachment engaging means of said leading side clamped to the leading side clamp Strip material compression bending method. A metal strip to be bent is locally heated to a plastically deformable temperature in an annular shape, and a bending moment and a compressive axial force are applied to the heating portion while moving the heating portion relative to the longitudinal direction of the strip. In the metal strip compression bending method for cooling immediately after that, an attachment engaging means is provided in advance on the preceding side clamp provided in the turning portion of the turning arm, and the clamp engaging means corresponding to the attachment engaging means is provided. Neck break prevention comprising a joint member and a strip contact portion that contacts a portion of the outer peripheral surface of the strip that increases or decreases in contact with the deformation of the neck according to increase or decrease of the neck bending deformation. The front attachment is prepared in a state separated from the preceding side clamp and the strip material, and the front side of the strip material is gripped by the preceding side clamp and the path thereof is regulated in an arc shape. A bending moment and the compression axial force are generated to compress and bend the strip material, and after the separation distance between the heating portion and the preceding clamp is increased, the engagement means are engaged to engage the neck. said elongated member those the contact portion is brought into contact with the outer peripheral surface of said elongated member to suppress the bending neck of the strip material Rukin Shokujo material compression bending method by the bending preventing attachment mounted on the leading side clamp Because
By engaging the both engaging means by screwing, the attachment for preventing neck breakage is attached to the preceding clamp in an implanted state, and the preceding clamp is extended rearward to the attachment for preventing neck breakage. features and to Rukin Shokujo material compression bending method of Rukoto. The neck breakage prevention attachment is divided into a plurality of stages that can be added in a state of direct contact between adjacent stages, and the neck breakage prevention attachment is increased step by step as the separation distance between the heating unit and the leading side clamp increases. The metal strip compression bending method according to any one of claims 1 to 3, wherein the metal strip material is bent and added. When the strip contact portion is brought into contact with the outer peripheral surface of the strip, the strip contact portion is applied to a portion of the outer peripheral surface of the straight portion of the strip that has been heat-treated by heating and cooling. The metal strip compression bending method according to any one of claims 1 to 4, wherein the metal strip is compressed.

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