JP2010046675A - Pipe bending device and pipe bending method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To carry out pipe bending work stably and smoothly in a state where a pipe is deformed into an elliptical cross-sectional shape. <P>SOLUTION: In a fitting groove 4 at a bending die 1 side and fitting grooves 5, 6 at a clamping die 2 and a pressure die 3 side facing the fitting groove 4, one fitting groove 4 of the opposite fitting grooves includes a pipe restraining part 4a having a groove width (e) almost equal to an outer diameter of a pipe W before deformation at a half way in a groove depth direction, and the other fitting grooves 5, 6 are structured to invade the one fitting groove 4 together with groove wall parts 5c, 6c while having a sliding contact of the outer surface of the groove wall part with the inner surface of the pipe restraining part 4a in the pinching process of the pipe W. In the state of completion of the pinching of the pipe W, by the facing of the one fitting groove and the other fitting groove 4-6, a pipe fitting hole H with the elliptical cross-sectional shape having a hole diameter d1 in the groove depth direction larger than the outer diameter of the pipe W before deformation and a hole diameter d2 in the groove depth direction smaller than the outer diameter of the pipe W before the deformation is formed. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a pipe bending apparatus and a pipe bending method for bending a pipe material, and in detail (see FIG. 8), in particular, a clamping die with a pipe W positioned between the clamping die 2 and the bending die 1. 2 and the pressure die 3 adjacent to the clamping die 2 in the longitudinal direction of the pipe are relatively pressed and moved toward the bending die 1 to fit the pipe W into the fitting grooves 4 to 6 formed in the respective die 1 to 3. The clamping mold 2 and the bending mold 1 are sandwiched and held in a state of being joined, and the clamping mold 2 is rotated together with the bending mold 1 to the side away from the pressure mold 3 around the bending mold 1 in this sandwiched holding condition. A pipe bending apparatus that bends and winds around the bending arc 1b while being fitted in the fitting groove 4 of the bending arc 1b by being sandwiched between the arc 1b of the bending mold 1 and the pressure mold 3 at the subsequent portion. And pipe bending method About.

  Conventionally, for this type of pipe bending process, a holding process for sandwiching and holding the pipe W between the clamping mold 2 and the bending mold 1 and a form in which the pipe W is wound around the arc-shaped portion 1b of the bending mold 1 following the holding process. In each of the bending processes, in the state in which the pipes W are clamped by the molds 1 to 3, as shown in FIG. 8 (b), the groove wall ends of the opposing fitting grooves 4 to 6 are butted together. The opposing fitting grooves 4 to 6 are formed so that the pipe fitting holes H having an elliptical cross-sectional shape in which the groove depth direction is the major axis direction are formed by the facing of the fitting grooves 4 to 6 in the contact state. In this manner, the pipe W is pushed into each of the opposing fitting grooves 4 to 6 having a semi-elliptical cross-sectional shape as the pipes W are sandwiched by the molds 1 to 3. The pipe W is fitted with the push fit. Is deformed from a circular cross-section to an elliptical cross section shape that matches the cross-sectional shape of the pipe fitting holes H, scheme employing a bending a pipe W is proposed in this variant applied state.

  In other words, in this type of pipe bending process, a tensile force acts on the outer side in the bending radius direction of the bending part of the pipe W in the bending process, whereas a compressive force acts on the inner side, which causes the pipe bending part in the bending process. May cause abnormal deformation such as buckling flattening in the bending radius direction or wrinkling inside the bending radius direction at the pipe bending site. By deforming the pipe W into the elliptical cross-sectional shape in the major axis direction, the rigidity in the bending radius direction of the pipe W is increased, and by bending the pipe W in that state, pipes such as flattening and wrinkling generated in the bending process as described above It is intended to prevent abnormal deformation.

JP-A-8-141658 JP 2005-74507 A

  However, in the above-described conventional method, when the pipe to be processed is a thin pipe or a low-strength material and has a low original rigidity, as shown in FIG. When the pipe W is pushed into and fitted into each of the opposing fitting grooves 4 to 6 as the pipe W is sandwiched by the pipe 6, the pipe W loses the pushing reaction force and both sides in the groove width direction in the pipe cross-sectional shape are opposed to each other. There was a problem that wide deformation was likely to occur in a state of protruding outward from between the groove wall ends of the joint grooves 4 to 6.

  Further, in the bending process, the subsequent portion of the pipe W (in other words, the bent portion of the pipe) is sequentially sandwiched from the front side by the arc-shaped portion 1b of the rotating bending die 1 and the pressure die 3, so that the opposing fitting grooves 4, 6 In the process of being pushed and fitted into the pipe, the pipe W does not fit well into the fitting groove 6 of the pressure die 3 due to the pushing reaction force, and toward the wedge-shaped space K between the bending arc portion 1b and the pressure die 3. There is also a problem that the escape operation is easy, and the pipe bending process itself is hindered due to the pipe widening deformation and the pipe escape operation.

  In view of this situation, the main problem of the present invention is to improve the fitting groove formed in each mold, while effectively preventing pipe widening deformation and pipe escaping caused by the above-mentioned pipe push-in fitting. The bending process can be performed in a state of being appropriately deformed into an elliptical cross-sectional shape.

The first characteristic configuration of the present invention relates to a pipe bending apparatus,
With the pipe positioned between the clamping die and the bending die, the pressure die adjacent to the clamping die and the clamping die in the longitudinal direction of the pipe are relatively moved toward the bending die by moving the pipe to each die. In a state where it is fitted into the formed fitting groove, it is sandwiched and held between the clamping die and the bending die,
By rotating the clamping die together with the bending die around the bending die in this sandwiched holding state, the bending portion arcuate portion of the bending die is sandwiched by the bending die and the pressure die that rotate the subsequent portion of the pipe. In a pipe bending apparatus that bends in a state of being wound around a bending mold arcuate part while being fitted in a fitting groove,
The fitting groove on the bending die side and the fitting groove on the clamping die and pressure die side facing it are either one of the opposing fitting grooves, the outer diameter of the pipe before deformation A pipe restraint part with a groove width almost equal to
And while the other fitting groove enters into the one fitting groove together with the groove wall portion in a state involving sliding contact of the outer surface of the groove wall portion with the inner surface of the pipe restraining portion in the process of sandwiching the pipe,
In the state where the sandwiching of the pipe is completed, the hole diameter in the groove depth direction is larger than the outer diameter of the pipe before deformation and the hole diameter in the groove width direction is larger than the outer diameter of the pipe before deformation. The structure is such that a pipe fitting hole having a smaller elliptical cross-sectional shape is formed.

  In other words, in this configuration, one of the fitting grooves is inserted into the one fitting groove together with the groove wall portion as the pipe is sandwiched by the opposing type in the holding process and the bending process. The pipe that is in a state of being received by the pipe restraining portion in the groove is deformed as the fitting grooves approach each other, and finally, when the pipe is completely sandwiched, the pipe formed by facing the fitting grooves. An elliptical cross-sectional shape whose major axis direction is the groove depth direction that matches the cross-sectional shape of the fitting hole (specifically, the outer diameter in the groove depth direction is larger than the outer diameter of the pipe before deformation and the outer diameter in the groove width direction) The pipe is deformed into an elliptical cross-sectional shape smaller than the outer diameter of the pipe before deformation.

  That is, in this configuration, the fitting grooves in a state where the pipes are restrained in the groove width direction by the pipe restraining portion having a groove width substantially equal to the pipe outer diameter formed in the middle of the groove depth direction in one fitting groove. Since the pipe is deformed into the elliptical cross-sectional shape by approaching, the pipe escaping operation in the pipe widening deformation or bending process caused by the push-fitting of the pipe into the fitting groove, which has occurred in the above-described conventional method, is described above. The pipe can be satisfactorily deformed into an elliptical cross-sectional shape in which the groove depth direction is the major axis direction in a state prevented by pipe restraint by the pipe restraint portion, thereby causing flattening and wrinkle generation that occur in the bending process, etc. Pipe bending in a state in which abnormal deformation of the pipe is prevented can be performed stably and smoothly as compared with the above-described conventional method.

  In the implementation of this configuration, all the fitting grooves on the bending die side and all the fitting grooves on the clamping die and pressure die side are in the relationship between the one fitting groove and the other fitting groove. For example, for the purpose of preventing widening deformation of the pipe in the holding process, for example, only the fitting groove of the part facing the clamping mold and the fitting groove of the clamping mold in the bending mold are used. The main purpose is to make the relationship between the fitting groove and the other fitting groove, or to prevent the escape operation of the pipe in the bending process, and the fitting groove of the arc-shaped part in the bending die and the fitting groove of the pressure die Only a part of the fitting groove on the bending die side and a part of the fitting groove on the clamping die and pressure die side, such as a relationship between the one fitting groove and the other fitting groove. You may make it make it the relationship between one fitting groove and the other fitting groove.

  In the holding process, the clamping die and the pressure die are moved toward the bending die relative to the bending die, and the clamping die and the pressure die are moved toward the bending die, and vice versa. Either a form of moving to the mold side or a form of moving both molds close may be adopted.

The second feature configuration of the present invention specifies an embodiment suitable for the implementation of the first feature configuration.
The fitting groove on the bending die side is the one fitting groove, and the fitting groove on the clamping die and pressure die side is the other fitting groove.

  That is, in this type of pipe bending apparatus, the pipe is often slid with respect to the pressure type fitting groove by pulling the pipe accompanying winding of the pipe around the arcuate portion of the bending mold that rotates in the bending process. According to the above configuration, on the contrary, the fitting groove on the side of the clamping mold and the pressure mold is set to the one fitting groove (that is, the fitting groove provided with the pipe restraining portion). The sliding resistance due to the sliding between the fitting groove of the mold and the pipe as described above can be reduced by the inexistence of the pipe restraining part, and the pipe slides smoothly against the fitting groove of the pressure mold. As a result, pipe bending can be performed more stably and smoothly, and pressure die wear can be effectively suppressed to improve apparatus durability.

The third feature configuration of the present invention specifies an embodiment suitable for the implementation of the first or second feature configuration.
Of the bending mold, the fitting groove of the portion facing the clamping mold and the fitting groove of the clamping mold are the cross-section of the end of the hole on the pressure mold side as the pipe fitting hole formed by facing them. The shape is such that the pipe fitting hole is formed so as to gradually approach a circular cross-sectional shape having a hole diameter substantially equal to the outer diameter of the pipe before deformation as the side away from the pressure die is the elliptical cross-sectional shape.

  In other words, the fitting groove of the portion of the bending die that faces the clamping die (that is, the pipe holding portion in the bending die) and the fitting groove of the clamping die are used as the pipe fitting hole formed by the facing thereof. When the pipe fitting hole having the elliptical cross-sectional shape is formed over the entire length, between the pipe part sandwiched and held by the bending mold and the clamping mold in the holding process and the non-holding pipe part on the front side thereof There is a possibility that a step due to the difference in cross-sectional shape occurs.

  On the other hand, according to the above configuration, as the pipe fitting hole formed by opposing both fitting grooves, the cross-sectional shape of the hole end portion on the pressure die side is the elliptical cross-sectional shape, and the side farther from the pressure die is Since the pipe fitting hole that gradually approaches the circular cross-sectional shape of the hole diameter almost equal to the outer diameter of the pipe before deformation is formed, it is possible to effectively prevent the occurrence of the step as described above in the holding process. As a result, it is possible to manufacture a pipe bending product with higher quality.

The fourth characteristic configuration of the present invention specifies an embodiment suitable for the implementation of any of the first to third characteristic configurations,
The fitting groove of the arc-shaped part and the fitting groove of the pressure die in the bending die are the pipe fitting holes formed by facing them, and the vicinity of the end of the bending step of rotating the clamping die and the bending die. A pipe fitting hole in which the cross-sectional shape gradually changes is formed from an elliptical cross-sectional shape to a circular cross-sectional shape having a hole diameter substantially equal to the outer diameter of the pipe before deformation.

  In other words, the fitting groove of the arc-shaped portion and the fitting groove of the pressure die in the bending die sequentially form the pipe fitting hole in the contact portion between the bending die and the pressure die in the bending process. As described above, when the pipe fitting hole is formed sequentially at the contact portion between the bending die and the pressure die, the pipe fitting hole having the elliptical cross-sectional shape is formed throughout the bending process. There is a possibility that a step due to a difference in cross-sectional shape may occur between the applied pipe bending portion and the pipe portion on the rear side.

  On the other hand, according to the above configuration, the pipe fitting hole that is sequentially formed in the contact portion between the bending die and the pressure die by facing both fitting grooves is deformed from the elliptical cross-sectional shape near the end of the bending process. Since a pipe fitting hole whose cross-sectional shape gradually changes to a circular cross-sectional shape having a hole diameter substantially equal to the outer diameter of the previous pipe is formed, the bent pipe bending portion and the pipe portion on the rear side of the bent pipe portion are formed. It is possible to effectively prevent the occurrence of the above-described step difference between them, and thereby it is possible to manufacture a pipe bending product with higher quality.

A fifth characteristic configuration of the present invention relates to a pipe bending method,
With the pipe positioned between the clamping die and the bending die, the pressure die adjacent to the clamping die and the clamping die in the longitudinal direction of the pipe are relatively moved toward the bending die by moving the pipe to each die. In a state where it is fitted into the formed fitting groove, it is sandwiched and held between the clamping die and the bending die,
By rotating the clamping die together with the bending die around the bending die in this sandwiched holding state, the bending portion arcuate portion of the bending die is sandwiched by the bending die and the pressure die that rotate the subsequent portion of the pipe. In the pipe bending method of bending in a state of being wound around the bending arc portion while being fitted in the fitting groove,
In order to fit the pipe into the opposing fitting groove as the pipe is sandwiched between the opposing molds, the pipe is made into the opposing fitting groove with the pipe restraining members in contact with both sides in the groove width direction of the pipe outer peripheral surface. As well as mating
A cross-section of a pipe fitting hole formed by facing the fitting grooves in a state where the pinching of the pipe is completed with this fitting or surrounded by the opposed fitting grooves and the pipe restraining member therebetween. Deform to a cross-sectional shape that matches the shape,
Due to this deformation, the pipe has an elliptical cross-sectional shape in which the outer diameter in the groove depth direction of the fitting groove is larger than the outer diameter of the pipe before deformation and the outer diameter in the groove width direction is smaller than the outer diameter of the pipe before deformation. .

  That is, in this configuration, the pipe restraining member is provided on both sides of the pipe outer peripheral surface in the groove width direction in order to fit the pipe into the opposing fitting groove as the pipe is sandwiched between the opposing molds in the holding process and the bending process. While the pipes are in contact with each other, the pipes are fitted into the opposing fitting grooves while being deformed as the fitting grooves approach each other. Finally, when the pipe is completely clamped, the fitting grooves are opposed to each other. The pipe is deformed into a cross-sectional shape that matches the cross-sectional shape of the pipe fitting hole formed or surrounded by the opposed fitting groove and the pipe restraining member between them.

  As the pipe fitting hole, a pipe fitting hole having an elliptical cross-sectional shape in which the hole diameter in the groove depth direction is larger than the outer diameter of the pipe before deformation and the hole diameter in the groove width direction is smaller than the outer diameter of the pipe before deformation is formed. In this way, the pipe is deformed so that the outer diameter in the groove depth direction is larger than the outer diameter of the pipe before the deformation and the outer diameter in the groove width direction is smaller than the outer diameter of the pipe before the deformation. That is, an elliptical cross-sectional shape in which the groove depth direction is the major axis direction).

  That is, in this configuration, the pipe is formed into the elliptical cross-sectional shape due to the closeness of the fitting grooves in a state where the pipe is restrained in the groove width direction by the pipe restraining member abutted on both sides in the groove width direction of the outer peripheral surface of the pipe. Therefore, the pipe constriction by the pipe restraining member prevents the pipe widening deformation and the pipe escaping operation in the bending process caused by the push-fitting of the pipe into the fitting groove that occurred in the above-mentioned conventional method. In this state, the pipe can be well deformed into an elliptical cross-sectional shape in which the groove depth direction is the major axis direction, thereby preventing abnormal deformation of the pipe such as flattening and wrinkling that occur in the bending process. The pipe bending can be performed stably and smoothly as compared with the above-described conventional method.

  In the implementation of this configuration, all the fitting grooves on the bending die side and all the fitting grooves on the clamping die and pressure die side are fitted to fit the pipe under the pipe restraint by the pipe restraining member. It is not always necessary to use a groove. For example, with the main purpose of preventing widening deformation of the pipe in the holding process, only the fitting groove of the bending mold facing the clamping mold and the fitting groove of the clamping mold are described above. The main purpose is to make the fitting groove into which the pipe is fitted under the pipe restraint by the pipe restraining member, or to prevent the pipe from escaping in the bending process. A part of the fitting groove on the bending die side and a fitting groove on the clamping die and pressure die side, such as a fitting groove for fitting the pipe under the pipe restraint by the pipe restraining member only. Part of Acquire may be fitted groove for fitting the pipe under the pipe restraint by the pipe restraining member.

  In the holding process, the clamping die and the pressure die are moved toward the bending die relative to the bending die, and the clamping die and the pressure die are moved toward the bending die, and vice versa. Either a form of moving to the mold side or a form of moving both molds close may be adopted.

  In the implementation of this configuration, the pipe restraining member does not necessarily need to be configured as a separate member from each die, and the pipe restraining member is integrally formed as a pipe restraining portion on the groove wall portion of the fitting groove on the bending die side, The pipe restraining member may be integrally formed as a pipe restraining portion on the groove wall portion of the fitting groove on the clamping die and pressure die side.

  Furthermore, in the implementation of this configuration, as in the third feature configuration described above, the fitting groove of the portion of the bending die that faces the clamping die and the fitting groove of the clamping die are formed by facing the fitting grooves. As a pipe fitting hole that is surrounded by the opposing fitting groove and the pipe restraining member between them, the cross-sectional shape of the hole end on the pressure die side is the elliptical cross-sectional shape, and the side away from the pressure die A pipe fitting hole that gradually approaches a circular cross-sectional shape having a hole diameter substantially equal to the outer diameter of the pipe before deformation may be formed.

  Alternatively, similar to the above-described fourth characteristic configuration, the arc-shaped fitting groove and the pressure-type fitting groove in the bending die are formed by facing the fitting grooves or facing the fitting grooves and their As a pipe fitting hole that is surrounded by a pipe restraining member in between, a circular shape having a hole diameter substantially equal to the outer diameter of the pipe before deformation from the elliptical cross-sectional shape in the vicinity of the end of the bending process of rotating the clamping die and the bending die A pipe fitting hole in which the cross-sectional shape gradually changes to the cross-sectional shape may be formed.

  FIG. 1 shows a main part of a pipe bending apparatus (pipe bender). 1 is a bending die having a pipe holding portion 1a and an arcuate portion 1b following the pipe holding portion 1a. The clamping mold 3 to be held is a pressure mold adjacent to the clamping mold 2 in the longitudinal direction of the pipe. In this pipe bending apparatus, as shown in FIGS. By pressing and moving the clamping die 2 and the pressure die 3 toward the bending die 1 with the pipe W positioned therebetween, the pipe holding portion 1a and the clamping die 2 of the bending die 1 are near the bent portion of the pipe W. And the subsequent part of the pipe W (that is, the part to be bent) is supported by the pressure die 3.

  Then, as a bending step subsequent to the holding step, the clamping die 2 is separated from the pressure die 3 around the central axis P of the arc-shaped portion 1b in the bending die 1 as shown in FIGS. By rotating together with the bending tool 1, the subsequent portion of the pipe W is sandwiched between the arc-shaped portion 1 b of the bending tool 1 and the pressure tool 3 from the front side at the contact portion between the rotating bending tool 1 and the pressure tool 3. Then, the pipe subsequent portion is bent around the arc-shaped portion 1b of the bending die 1 and bent.

  In this bending process, the pressure die 3 may be slid at a predetermined speed in parallel with the rotation of the clamping die 2 and the bending die 1 depending on the bending conditions.

  In each of the molds 1 to 3, fitting grooves 4 to 6 for fitting the sandwiched pipe W are formed to stabilize the sandwiching of the pipe W, and the fitting grooves 4 to 6 are formed. However, as shown in FIG. 4, the fitting groove 4 of the bending die 1 has a pipe restraining portion 4 a having a groove width e substantially equal to the outer diameter of the pipe W before deformation from the groove entrance to the groove back portion. In addition, a groove bottom portion 4b that is a semi-elliptical cross-sectional shape in which the groove depth direction is the major axis direction as the groove bottom portion following the pipe restricting portion 4a is gradually reduced from the groove width e of the pipe restricting portion 4a. It has a cross-sectional structure.

  On the other hand, the fitting grooves 5 and 6 of the clamping die 2 and the pressure die 3 have a major axis in the groove depth direction similar to the groove bottom portion 4b of the fitting groove 4 of the bending die 1 from the groove entrance to the groove bottom portion. Both groove walls have a semi-elliptical cross-sectional shape as a direction, and the outer surfaces of both groove wall portions 5c and 6c are parallel surfaces in which the separation dimension e 'is slightly smaller than the groove width e of the pipe restraining portion 4a. The sections 5c and 6c have a cross-sectional structure in which the tips of the sections have a wedge-shaped pointed cross section.

  In other words, the fitting grooves 4 to 6 of each of the molds 1 to 3 are structured as described above, so that the pipe W is sandwiched between the pipe holding portion 1a and the clamping mold 2 in the bending mold 1 in the holding process, and the bending process. As shown in FIG. 4, the groove wall portions 5 c in the fitting grooves 5 and 6 on the side of the clamping die 2 and the pressure die 3, as the pipe W is sandwiched between the arc-shaped portion 1 b and the pressure die 3 in the bending die 1. While the outer surface of 6c is brought into sliding contact with the inner surface of the pipe restraining portion 4a in the fitting groove 4 on the bending die 1 side, the fitting grooves 5 and 6 on the clamping die 2 and pressure die 3 side are placed on the groove wall portions thereof. 5c and 6c are inserted into the fitting groove 4 on the side of the bending die 1 so that the pipe W in a state of being received by the pipe restraining portion 4a in the fitting groove 4 on the side of the bending die 1 is The fitting groove 4 and the fitting grooves 5 and 6 on the clamping die 2 and pressure die 3 side are deformed.

  Finally, when the pinching is completed, the fitting groove 4 on the bending die 1 side and the fitting grooves 5 and 6 on the clamping die 2 or pressure die 3 side are opposed to each other by the semi-elliptical cross-sectional shapes, so that the groove A pipe fitting hole H having an elliptical cross-sectional shape in which the hole diameter d1 in the depth direction is larger than the outer diameter of the pipe before deformation and the hole diameter d2 in the groove width direction is smaller than the outer diameter of the pipe before deformation is formed. It is deformed into an elliptical cross-sectional shape that matches the cross-sectional shape of the pipe fitting hole H (that is, an elliptical cross-sectional shape in which the groove depth direction is the major axis direction).

  That is, the circular cross section before deformation of the pipe W due to the close proximity of the fitting grooves when the pipe W is restrained in the groove width direction by the pipe restraining portion 4a formed in the fitting groove 4 on the bending die 1 side in this way. By deforming from the shape into the above-mentioned elliptical cross-sectional shape, the pipe W is widened and deformed when the pipe W is sandwiched in the holding process and the bending process, and the pipe W is bent when the pipe W is sandwiched in the bending process. It is possible to prevent the escaping operation toward the wedge-shaped space between the arcuate portion 1b and the pressure die 3.

  Then, by deforming the pipe W into an elliptical cross-sectional shape in which the groove depth direction is the major axis direction as described above, the rigidity of the pipe W in the groove depth direction (that is, the rigidity in the bending radius direction) is increased. The pipe W is bent in a bent state, and this causes abnormal pipe deformation such as flattening of the cross-sectional shape of the pipe bending part in the bending radius direction and wrinkling inside the bending radius direction of the pipe bending part in the bending process. Is prevented from occurring.

  In addition, in order to prevent abnormal deformation of the pipe in such a bending step, the necessity for additional processing such as inserting a mandrel in advance in the bending portion of the pipe W is also reduced.

[Another embodiment]
Next, other embodiments of the present invention will be listed.

  In the above-described embodiment, the pipe restraining portion 4a is formed in the fitting groove 4 on the bending die 1 side, and the fitting grooves 5 and 6 on the clamping die 2 and pressure die 3 side are connected to the groove wall portions 5c, In contrast to this, the apparatus is configured to enter the fitting groove 4 on the bending die 1 side together with the pipe 6c. On the contrary, the pipe restraining portion as described above is provided in the fitting grooves 5 and 6 on the clamping die 2 and pressure die 3 side. The fitting groove 4 on the bending die 1 side and the groove wall portion thereof may be inserted into the fitting grooves 5 and 6 on the clamping die 2 or pressure die 3 side.

  As shown in FIG. 5, the fitting groove 4 of the pipe holding part 1a facing the clamping mold 2 and the fitting groove 5 of the clamping mold 2 of the bending mold 1 are formed as pipe fitting holes H formed by facing them. The pipe having a cross-sectional shape at the end of the hole on the side of the pressure die 3 is the elliptical cross-sectional shape, and the pipe gradually approaches a circular cross-sectional shape having a hole diameter substantially equal to the outer diameter of the pipe W before deformation as it is away from the pressure die 3 Due to the structure in which the fitting hole is formed, a step due to the difference in cross-sectional shape between the pipe portion sandwiched and held by the bending die 1 and the clamping die 2 in the holding step and the non-holding pipe portion ahead of the pipe portion May be prevented from occurring.

  Further, the fitting groove 4 of the arcuate portion 1b in the bending die 1 and the fitting groove 6 of the pressure die 3 are formed as a pipe fitting hole H formed by facing them, as shown in FIG. Near the end of the bending step of rotating the bending die 1, a pipe fitting hole is formed in which the cross-sectional shape gradually changes from the elliptical cross-sectional shape to a circular cross-sectional shape having a hole diameter substantially equal to the outer diameter of the pipe before deformation. It is possible to prevent the occurrence of a step due to the difference in cross-sectional shape between the pipe bending portion bent in the bending step and the pipe portion on the rear side thereof.

  In the above-described embodiment, the pipe restraining portion 4 a is provided in one fitting groove 4 among the fitting groove 4 on the bending die 1 side and the fitting grooves 5 and 6 on the clamping die 2 and pressure die 3 sides. In this embodiment, the other fitting grooves 5 and 6 are inserted into the one fitting groove 4 together with the groove walls 5c and 6c. Instead, as shown in FIG. A pipe restraining member 7 for restraining the pipe W in the width direction of the fitting grooves 4 to 6 by contacting both sides in the width direction is provided separately from each of the molds 1 to 3, and each of the holding process and the bending process. A state in which the pipe restraining member 7 is brought into contact with both sides of the outer circumferential surface of the pipe in the groove width direction in order to fit the pipe W into the opposing fitting grooves 4 to 6 with the sandwiching of the pipe W by the molds 1 to 3 In this state, the pipe W is fitted into the opposing fitting grooves 4 to 6, and the pipe W is in a state in which the pinching is completed along with this fitting. The cross-sectional shape that matches the cross-sectional shape of the pipe fitting hole H that is formed by facing the fitting grooves 4 to 6 or surrounded by the opposing fitting grooves 4 to 6 and the pipe restraining member 7 therebetween. As a result of this deformation, the outer diameter in the groove depth direction of the fitting grooves 4 to 6 is larger than the pipe outer diameter before deformation and the outer diameter in the groove width direction is smaller than the pipe outer diameter before deformation. An elliptical cross-sectional shape may be used.

Plane and front view of pipe bending machine Plan view sectional view and front view sectional view for explaining the holding step Plan view sectional view and front view for explaining the bending process Front sectional view explaining the process of pinching the pipe Cross-sectional shape explanatory drawing of a pipe fitting hole showing another embodiment Cross-sectional shape explanatory drawing of a pipe fitting hole showing another embodiment Plan view sectional view and front sectional view showing another embodiment Plan view and front sectional view showing the conventional method Front sectional view for explaining the process of sandwiching the pipe in the conventional method

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Bending type | mold 1b Arc-shaped part 2 Clamping type 3 Pressure type W pipe 4 Bending type fitting groove 4a Pipe restraint part 5 Clamping type fitting groove 6 Pressure type fitting groove 5c, 6c Groove wall part H Pipe fitting hole d1 Hole diameter in the groove depth direction d2 Hole diameter in the groove width direction 7 Pipe restraining member

Claims (5)

With the pipe positioned between the clamping die and the bending die, the pressure die adjacent to the clamping die and the clamping die in the longitudinal direction of the pipe are relatively moved toward the bending die by moving the pipe to each die. In a state where it is fitted into the formed fitting groove, it is sandwiched and held between the clamping die and the bending die,
By rotating the clamping die together with the bending die around the bending die in this sandwiched holding state, the bending portion arcuate portion of the bending die is sandwiched by the bending die and the pressure die that rotate the subsequent portion of the pipe. A pipe bending apparatus that bends in a state of being wound around a bending arc portion while being fitted in a fitting groove,
The fitting groove on the bending die side and the fitting groove on the clamping die and pressure die side facing it are either one of the opposing fitting grooves, the outer diameter of the pipe before deformation A pipe restraint part with a groove width almost equal to
And while the other fitting groove enters into the one fitting groove together with the groove wall portion in a state involving sliding contact of the outer surface of the groove wall portion with the inner surface of the pipe restraining portion in the process of sandwiching the pipe,
In the state where the sandwiching of the pipe is completed, the hole diameter in the groove depth direction is larger than the outer diameter of the pipe before deformation and the hole diameter in the groove width direction is larger than the outer diameter of the pipe before deformation. A pipe bending apparatus having a structure in which a pipe fitting hole having a smaller elliptical cross-sectional shape is formed.   The pipe bending apparatus according to claim 1, wherein the fitting groove on the bending die side is the one fitting groove, and the fitting groove on the clamping die and pressure die side is the other fitting groove.   Of the bending mold, the fitting groove of the portion facing the clamping mold and the fitting groove of the clamping mold are the cross-section of the end of the hole on the pressure mold side as the pipe fitting hole formed by facing them. 2. The structure is such that a pipe fitting hole is formed in which the shape is the elliptical cross-sectional shape and gradually approaches a circular cross-sectional shape having a hole diameter substantially equal to the outer diameter of the pipe before deformation as the side away from the pressure die. 2. The pipe bending apparatus according to 2.   The fitting groove of the arc-shaped part and the fitting groove of the pressure die in the bending die are the pipe fitting holes formed by facing them, and the vicinity of the end of the bending step of rotating the clamping die and the bending die. 4. A structure for forming a pipe fitting hole in which the cross-sectional shape gradually changes from an elliptical cross-sectional shape to a circular cross-sectional shape having a hole diameter substantially equal to the outer diameter of the pipe before deformation. The pipe bending apparatus as described in 1. With the pipe positioned between the clamping die and the bending die, the pressure die adjacent to the clamping die and the clamping die in the longitudinal direction of the pipe are relatively moved toward the bending die by moving the pipe to each die. In a state where it is fitted into the formed fitting groove, it is sandwiched and held between the clamping die and the bending die,
By rotating the clamping die together with the bending die around the bending die in this sandwiched holding state, the bending portion arcuate portion of the bending die is sandwiched by the bending die and the pressure die that rotate the subsequent portion of the pipe. A pipe bending method of bending in a state of being wound around a bending arc portion while being fitted in a fitting groove,
In order to fit the pipe into the opposing fitting groove as the pipe is sandwiched between the opposing molds, the pipe is made into the opposing fitting groove with the pipe restraining members in contact with both sides in the groove width direction of the pipe outer peripheral surface. As well as mating
A cross-section of a pipe fitting hole formed by facing the fitting grooves in a state where the pinching of the pipe is completed with this fitting or surrounded by the opposed fitting grooves and the pipe restraining member therebetween. Deform to a cross-sectional shape that matches the shape,
This deformation causes the pipe to be bent into an elliptical cross-sectional shape in which the outer diameter in the groove depth direction of the fitting groove is larger than the outer diameter of the pipe before deformation and the outer diameter in the groove width direction is smaller than the outer diameter of the pipe before deformation. Method.

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