JPH07110382B2 - Die mechanism in push-through bending machine - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a die mechanism in a push-through bending apparatus, for setting an inclination angle of a die that constitutes an ideal bending condition in the special bending process. Regarding various mechanisms.

[Prior Art] The inventor of the present application uses a "push-through bending method and the same method" as a means for highly accurately bending a pipe / section or solid material (hereinafter referred to as "pipe or the like") with a simple device. Bending machine ”(Japanese Patent Application No. 1-120894).

The basic structure of this processing method is shown in Fig. 11.
It consists of a guide cylinder 102 for inserting while holding the 101 and a die 103 for holding a part of the pipe material 101 penetrating the guide cylinder 102 with a bearing portion 103a. The center axis of the guide cylinder 102 and the bearing of the die 103. The method is characterized in that the pipe material 101 is pushed through the guide cylinder 102 and the die 103 in a state where the center of the portion 103a is relatively offset. ”According to this method, the offset u between the guide cylinder 102 and the die 103 It is possible to perform continuous bending with a bending radius R corresponding to the offset u and to suppress the deformation of the cross-section of the pipe 101 or the like 101 by simply controlling. That is, the bending is performed by the force of the bearing 103a pressing the pipe 101 or the like by setting the offset u and the action of the bending moment based on the approach v, and the processing conditions for the bearing 103a sliding the pipe 101 or the like. Further, the flattening of the pipe member 101 is corrected by the bearing portion 103a to suppress the deformation of the cross section. The bending radius can also be controlled by controlling the approach v.

[Problems to be Solved by the Invention] By the way, even in the method and apparatus described above, there are limits to the bending processing conditions.

That is, as shown in FIG. 12 (a graph relating to the relationship between the bending ratio and the offset amount), the bending radius R can be decreased as the offset u is set larger, but the offset amount is not less than a certain value. If the inclination angle Ψ of the die 103 is not set correspondingly, the pipe material 1
The sliding contact force between 01 and the bearing 103a becomes abnormally large,
Normal bending will not be possible. Further, if the offset u is set larger than that, it becomes impossible to push the pipe member 101 or the like. The plots a, b, c and d in FIG. 12 show the processing limits at Ψ = 0, 10, 20, 30 (degree).

In addition, as shown in Fig. 13 (graph related to the relationship between the die tilt angle and the pushing load), the bending is not severe u / do = 3.0
Under the condition of, the pushing load P is not so much influenced by the inclination angle Ψ of the die 103, but as the bending becomes severe like the condition of u / do = 4.0, the influence appears. Pushing force P is tilt angle Ψ = 15〜
The pushing load P takes the minimum value in the range of 20 °.

Furthermore, regarding the problem relating to flattening of the pipe material 101 whose schematic cross section is shown in FIG. 14, when the influence of the inclination angle Ψ of the die 103 on the flatness is examined, the relationship shown in FIG. 15 is observed. It was That is, the flatness ratio takes the minimum value when the inclination angle Ψ is about 10 to 15 °, and the processing accuracy is improved.

Analyzing the above phenomena, in order to expand the working limit, reduce the pushing force P, and improve the working accuracy, the tilt angle Ψ of the die 103 in the bending working state is set to an appropriate value corresponding to the offset u. It is understood that you have to do.

Therefore, the present invention was created with the object of providing various die mechanisms capable of controlling the inclination angle Ψ of the die 103 to an optimum value during the push-through bending process, and thereby solving the above-mentioned problems.

[Means for Solving the Problem] A first invention is to provide a guide cylinder into which a pipe / shape or solid material (hereinafter referred to as “pipe or the like”) can be inserted while holding the pipe or the like. It consists of a die that holds a part of it in the bearing part, and bends it by pushing the pipe material etc. through the guide cylinder and the die with the center axis of the guide cylinder and the center of the bearing part of the die relatively offset. In the device (hereinafter referred to as "push-through bending device"), a spherical curved surface having an annular protrusion around the insertion port side of the pipe or the like and having a circumferential side surface centered on the delivery side of the pipe or the like from the center of the bearing part The die is formed on the base, a curved surface that holds the spherical curved surface of the die is formed, and a die holder that holds the die so as to face the guide cylinder and a guide cylinder. An annular member that is provided around the outlet side of the pipe or the like in the Linda and internally fits and faces the annular protrusion of the die, and the outer peripheral surface of the annular member is offset by the relative axial movement of the die holder and the guide cylinder. In this state, when the die rotates in the die holder and the annular protrusion of the die comes into contact with the die, the surface including the bearing part of the die is set to be substantially vertical as viewed from the center of the guide cylinder outlet. The present invention relates to a die mechanism in a push-through bending apparatus, characterized in that the die mechanism comprises a formed die control jig.

According to a second aspect of the present invention, in a push-through bending apparatus, an annular projection is provided around the insertion port side of a pipe or the like, and the peripheral side surface is formed into a spherical curved surface having a center on the delivery side of the pipe or the like from the center of the bearing portion. And a curved surface that holds the spherical curved surface of the die are formed. A die holder that holds the die facing the guide cylinder, and an elastic ring that is fixedly installed on the side surface of the die holder facing the guide cylinder. In the press-through bending apparatus, the die control ring is a member and is configured by rotation of the die in the die holder, and the outer peripheral surface of the annular projection of the die is in pressure contact with the inner peripheral surface of the elastic annular member. Related to the die mechanism.

According to a third aspect of the present invention, in a push-through bending apparatus, when the pipe material is a pipe having a circular cross section or a solid material, the shape of the bearing portion of the die is offset by the relative axial movement of the die and the guide cylinder. The die mechanism in the push-through bending apparatus is characterized in that, in the state, the shape of the bearing portion of the die as viewed from the center of the delivery port of the guide cylinder is formed into an elliptical shape having a geometrical relationship of being substantially circular.

A fourth aspect of the present invention is, in a push-through bending apparatus, a bearing portion of the die is in an offset state due to relative axial movement of the die and the guide cylinder, and is substantially viewed from the center of the outlet of the surface guide cylinder including the bearing portion. The present invention relates to a die mechanism in a push-through bending apparatus characterized by being formed so as to be vertical.

[Operation] Regarding the first invention; Since the die is held by the spherical curved surface of the die holder, it can freely rotate in relation to the bearing portion of the die and the die holder. Therefore, when the pipe material is inserted into the die and the guide cylinder to offset them, the offset causes the die to rotate and tilt, and the center of the bearing portion moves to the offset interval side.

Further, the center of the spherical holding curved surface is configured to be provided on the delivery port side such as a tube with respect to the center of the bearing part of the die, and the pipe material is pushed in while being held in the bearing part. Then, the offset interval side of the bearing portion becomes a strong sliding contact area with the pipe material or the like, so that the die is further rotated in a direction inclining. That is, a rotational moment is generated in the die itself due to the sliding joint force between the die and the pipe material and the displacement of the center of the bearing portion due to the rotation of the die, and the rotational moment further increases the inclination of the die.

As a result, once the bending process is started, the die excessively rotates in the die holder, and the normal bending process cannot be performed.

By the way, the ideal inclination angle of the die is such that the surface of the die including the bearing portion is substantially vertical when viewed from the center of the guide cylinder.

Therefore, in the present invention, an annular projection is provided around the insertion port side of the pipe material or the like in the die, while an annular member that internally fits and faces the annular projection of the die around the delivery port side of the pipe material or the like of the guide cylinder ( A die control jig) is provided, and the inclination of the die is controlled by contact between the annular protrusion of the die and the annular member that is the die control jig. For this reason, when the die and the bearing portion are in an offset state, the surface of the die control jig that is internally fitted to the ring-shaped protrusion is substantially perpendicular to the surface including the bearing portion of the die when viewed from the center of the guide cylinder. The control surface is such that
It is designed to constrain the die to an ideal tilt angle.

Regarding the second invention; As described above, the inclination angle of the die in the ideal bending state is an angle at which the surface including the bearing portion of the die becomes substantially vertical when viewed from the center of the guide cylinder in the offset state.

In this invention, the relationship between the die and the die holder is the same as in the first invention, but in order to set the above-mentioned angle condition, the die formed of an elastic annular member on the side facing the guide cylinder of the die. The control ring is fixed.

That is, due to the inclination of the die, the annular protrusion provided on the insertion opening side abuts the die control ring, and the elasticity of the control ring suppresses the excessive inclination of the die, and the inclination of the die satisfying the above ideal condition. Uses a mechanism that balances at the corners. Therefore, in the present invention, there is no engagement relationship between the die and the guide cylinder side, and the tilt angle is controlled only by the die control ring on the die side.

The elastic constant of the die control ring can be freely selected according to the diameter of the pipe material and the hardness of the material, and can be applied to a wide range of workpieces.

Third invention: The present invention is applied when a pipe or a solid material having a circular cross section is bent at a constant bending radius, and the offset is substantially constant.

Further, in the present invention, since the die is simply offset without using a means for rotating the die itself,
No die holder is required.

The ideal tilt state of the die in the offset state is
In other words, it means a state in which the bearing portion of the die when viewed from the center of the guide cylinder at the time of offset has a cross-sectional shape of a pipe material or the like which is a workpiece.

Therefore, when the material to be processed is a pipe or a solid material with a circular cross section, an elliptical shape having a geometrical relationship such that the bearing part of the die becomes circular when viewed from the center of the guide cylinder with a certain offset state. By doing so, it is possible to configure a processing condition equivalent to that in which the ideal inclination angle of the die in the offset state is set.

Regarding the fourth invention; This invention is based on the same idea as the third invention. While the third invention focuses on the shape of the bearing portion of the die, the bearing portion in the die itself. We pay attention to the inclination angle of.

That is, the ideal inclination state of the die in the offset state is a state in which the surface including the bearing portion of the die has a substantially vertical relationship when viewed from the center of the guide cylinder,
In order to achieve this, it is sufficient from the beginning to form the bearing portion in the die so as to be inclined so as to satisfy the condition.

Therefore, in the present invention, the bearing portion of the die can be formed to have the same cross-sectional shape of the work piece as viewed from the center side of the guide cylinder regardless of the presence or absence of the offset, and the bearing portion of the die required in the offset state. It is formed so as to be inclined by an inclination angle.

Embodiments Embodiments of the present invention will be described below with reference to FIGS. 1 to 10.

Example 1 This example corresponds to the first invention, and FIG. 1 (cross-sectional view of the push-through bending apparatus) shows the configuration of the die part and the guide cylinder part.

In the figure, 1 is a die, 2 is a die holder, 3 is a guide cylinder, and 4 is a pipe material which is a workpiece.

An annular protrusion 1a is integrally formed on the side of the die 1 through which the pipe member 4 is inserted, and the peripheral side surface of the die 1 is formed into a spherical curved surface. The center C1 of the spherical curved surface of the die 1 is formed so as to be closer to the delivery port side of the pipe member 4 than the center C2 of the bearing portion 1b.

On the other hand, the die holder 2 has a curved surface for holding the spherical curved surface of the die 1 formed on the inner peripheral surface thereof.
Are held facing the guide cylinder 3. Since the spherical curved surface of the die holder 2 is in close contact with the spherical curved surface on the die 1 side, the center of the curved surface is naturally C1.

Further, the guide cylinder 3 is provided so as to face the die 1 and the die holder 2 described above, but a small-diameter annular projection is formed on the guide cylinder 3 on the delivery side of the pipe material 4, and at the same portion. A die control jig 3a is fitted and fixed to the annular projection 1a of the die 1 so as to be fitted inside.

In such a mechanism, when the die holder 2 is offset by a predetermined amount u with respect to the guide cylinder 3 while pushing the pipe material 4, the state shown in FIG. 2 is obtained.
In addition, in the process from FIG. 1 to FIG. 2, the pipe material 4 is in strong sliding contact with the lower region of the bearing portion 1b in order to maintain the initial straightness, but the offset When u is equal to or less than a certain value, the state shown in FIG. 1 is maintained, and when the pipe material 4 yields, the bending process is suddenly started and the die 1 rotates in the die holder 2.

By the way, this rotation causes the die 1 to have a predetermined inclination angle Ψ.
Occurs and the surface S including the bearing portion 1b of the die 1 is perpendicular to the center of the outlet of the guide cylinder 3 and the sliding contact processing energy of the bearing portion 1b takes a minimum value. Therefore, the inclination of the die 1 should stop in that state.

However, as is apparent from FIG. 2, when the die 1 rotates, the center C2 is displaced from the center C1 by Δy toward the strong sliding contact side of the bearing portion 1b due to the geometrical relationship. As a result, the sliding joint force and the deviation Δy
Based on the above, the rotation moment M that further increases the inclination angle acts on the die 1. That is, the ideal bending state with the predetermined tilt angle is not maintained as it is, and the die 1 is further tilted by the action of the rotation moment M.

Therefore, in this die mechanism, the fitting protrusion 1a of the die 1 and the die control jig 3a on the guide cylinder 3 side are engaged and brought into contact with each other to prevent the inclination thereof. More specifically, the engagement contact surface 3a ′ of the die control jig 3a is formed as a control curved surface obtained from the relative relationship with the inner peripheral surface of the annular projection 1a, and when the offset u is set. In the geometrical relationship, the surface S including the bearing portion 1b of the die 1 constitutes an engagement relationship in which the surface S including the bearing portion 1b is substantially vertical when viewed from the center of the delivery port of the guide cylinder 3.

Therefore, the annular projection 1a and the surface 3a 'of the die control jig 3a are
The inclination angle Ψ of the die 1 in the engagement and contact state with
The value for performing the ideal bending process is taken, and in this state, the shape of the bearing portion 1b viewed from the center of the delivery port of the guide cylinder 3 is substantially circular.

As a result, in the push-through bending apparatus, the inclination angle Ψ of the die 1 is always set to an ideal value for the offset u, the bending limit is expanded, and bending with a smaller bending radius is possible. It is possible to realize processing with a small bending and pushing force, and furthermore, it is possible to properly correct flattening of the pipe material 4 after bending, and it is possible to realize bending processing with high accuracy. In this mechanism, since the inclination angle of the die 1 is controlled by the abutting engagement relationship between the annular protrusion 1a and the annular die control jig 3a, even if the offset u is taken in any direction, It is possible to set the tilt angle of 1 to the optimum value.

Embodiment 2 This embodiment corresponds to the second invention, and the configuration of the die part and the guide cylinder part is shown in FIG. 3 (cross-sectional view of the push-through bending device).

In the figure, 21 is a die, 22 is a die holder, 23 is a guide cylinder, and 24 is a pipe material that is a workpiece.

The mechanical relationship between the die 21 and the die holder 22 in this die mechanism is the same as that in the first embodiment, and the die holder 22 holds the die 21 with a spherical curved surface and holds it facing the guide cylinder 23. Doing and dice 21
The center C1 of the spherical curved surface is formed closer to the delivery port side of the pipe member 24 than the center C2 of the bearing portion 21b.

The feature of this mechanism is that the rotation of the die 21 is elastically restrained in the relationship between the die 21 and the die holder 22.

As the rotation suppressing mechanism, first, an annular protrusion 21a is integrally formed on the insertion side of the pipe material 4 in the die 21, and a curved contact portion 21a is formed on the outer peripheral surface of the annular protrusion 21a on the tip side. 'Is formed. Meanwhile, the dice holder 2
On the side facing the guide cylinder 23 in 2, the die 2
A fitting recess having a larger diameter than the outer circumference of the first annular projection 21a is formed, and an elastic annular member 25 made of rubber is internally fitted and adhered to the fitting recess, and further, on the inner peripheral surface of the elastic annular member 25. An annular member 26 made of metal is internally fitted and adhered. Then, the inner peripheral surface of the annular member 26 has an annular protrusion 21 provided on the die 21 side.
It is configured to abut the abutting portion 21a 'of a.

The guide cylinder 23 side has a normal structure, and it is not necessary to provide the die control jig 3a as in the first embodiment.

In the above mechanism, when the die holder 22 is offset by a predetermined amount u with respect to the guide cylinder 23 while pushing the pipe material 24, the state shown in FIG. 4 is obtained. The phenomenon that occurs in the relationship between the die 21 and the die holder 22 during this time is the same as that in the first embodiment.
Is rotated by receiving the rotation moment M due to the generation of Δy and the strong sliding contact with the pipe material 24 in the lower sliding contact area of the bearing portion 21b. This rotational moment exceeds the inclination angle Ψ of the die 21 at which the bending energy with respect to the pipe material 24 becomes the minimum, that is, the angle at which the surface including the bearing portion 21b becomes vertical when viewed from the center of the delivery port of the guide cylinder 23, and the rotation moment is increased in Will give rotation.

However, in this mechanism, as shown in FIG. 4, when the die 21 rotates, the contact portion 21a 'of the annular projection 21a presses the elastic annular member 25 via the metallic annular member 26, The die 21 is prevented from rotating beyond the tilt angle Ψ. That is, when the elastic annular member 25 is pressed and compressed, the elastic annular member 25 causes a reaction force corresponding to the amount of compression on the annular protrusion 21a side, and a rotational moment in the opposite direction to the rotational moment M is applied to the die 21. Give to prevent excessive rotation of the die 21. Regarding the reaction force generated by the elastic annular member 25, the optimum rotation restraining force can be obtained by selecting the hardness of the rubber material.

In this mechanism, the inclination angle of the die 21 is controlled under the pressure contact condition of the annular contact portion 21a 'against the annular elastic member 25, so that the offset u can be set in any direction. It is possible to set the tilt angle of the die 21 to an optimum value.

Example 3 This example corresponds to the third invention.

The basic structure of this mechanism during bending is the same as that shown in FIG. 11, and the die 31 is used in the manner as shown in FIG.
A guide cylinder 32 is provided, and a pipe material 33 is inserted therethrough.

In this mechanism, no additional element is provided on the die 31 side or the guide cylinder 32 side, and only the shape of the bearing portion 31a of the die 31 is devised. That is, as shown in FIG.
Although the front view of is shown, it is characterized in that the bearing portion 31a is formed in an elliptical shape. A circle 33a shown by a dotted line in FIG. 6 indicates the outer peripheral surface of the pipe material 33.

To perform bending of the pipe material 33 using this die 31, while pushing the pipe material 33 with the pipe material 33 inserted as shown in FIG. 5, an offset u is applied to the die 31 as shown in FIG.
give.

In this case, the die 31 is only moved in parallel to the guide cylinder 32, and the die 31 does not rotate unlike the first and second embodiments. However, with the offset u given, the bearing portion 31a of the die 31 as viewed from the center of the delivery port of the guide cylinder 32 becomes circular. In other words,
The bearing portion 31a of the die 31 is formed in an elliptical shape satisfying such a geometrical relationship.

Therefore, in the case of this mechanism, S including the bearing portion 31a is not vertical when viewed from the center of the delivery port of the guide cylinder 32 in the state where the offset u is given, but the bearing portion 31a does not cover the entire circumference of the pipe material 33. The relationship of holding and sliding contact is configured, and the bending of the pipe material 33 can be performed under substantially ideal conditions while performing strong sliding contact processing in the upper sliding contact area of the bearing portion 31a. When machining with a circular bearing part like a conventional die, the tubing after processing is elliptical (ellipse having a major axis in the direction perpendicular to the offset direction)
However, in this mechanism, such a problem does not occur because the bearing portion 31a sends out the pipe member 33 while holding the pipe member 33 in a circular shape under the above-mentioned geometrical conditions.

Example 4 This example corresponds to the fourth invention.

The mechanism according to this embodiment is also devised only in the bearing portion of the die as in the third embodiment, and the structure of the die is shown in FIG. 8 (side view) and FIG. 9 (front view). .

That is, the bearing portion 41a of the die 41 is formed by being inclined in advance by the angle ψ with respect to the axis on the guide cylinder side.

The die 41 is arranged on the guide cylinder as shown in FIG. 10, and the offset u is given to the guide cylinder 42. In this state,
The die 41 holds the pipe material 43 at the bearing portion 41a, and the surface S including the bearing portion 41a has a guide cylinder 4
It has a vertical relationship when viewed from the center of the second delivery port, and the bearing portion 41a also has a circular shape.

In other words, when the bending is performed with the offset u set to be constant, the inclination angle Ψ of the bearing portion 42a for performing the ideal bending is also constant, and in this mechanism, the offset u is applied to the die 41. Is given, the state in which the bearing portion 42a is inclined by the ideal inclination angle ψ is uniquely configured, and in that state, ideal bending can be performed as it is.

[Advantages of the Invention] The present invention having the above-described configuration has the following advantages.

According to the inventions of claims (1) and (2), in a push-through bending apparatus for a pipe material or the like, only by giving an offset to the die,
The tilt angle of the die is automatically set to the optimum angle to form an ideal bending state. That is, the dies are rotationally controlled in accordance with the offset amount so that the surface including the bearing portion is in a substantially vertical relationship with respect to the center of the delivery port of the guide cylinder.

As a result, the bending limit of the push-through bending apparatus is expanded so that the bending radius can be made smaller, and the pushing force of the pipe material etc. is reduced and the flatness that occurs in the pipe material after processing is prevented and the processing accuracy is improved. Realize improvement.

Furthermore, the mechanisms of these inventions have a configuration that exerts their function even if the die is offset in any direction, and has an advantage that it can also be used for three-dimensional continuous bending of pipes and the like. There is.

According to claims (3) and (4), in a push-through bending apparatus for a pipe material or the like, an ideal bending process is performed only by providing a bearing portion of a die with a shape and an angle that configure an optimum processing condition in an offset state. To realize. These inventions can be applied only to one-way bending unless the die setting direction is changed, but do not require additional elements, the bending limit is expanded, the pushing force is reduced and the processing accuracy is extremely simple. Realize the improvement of.

[Brief description of drawings]

FIG. 1 is a sectional view of a push-through bending apparatus according to Example 1, FIG. 2 is a sectional view of the same bending process, FIG. 3 is a sectional view of a push-through bending apparatus according to Example 2, and FIG. Sectional view at the time of processing, FIG. 5 is a sectional view of a push-through bending apparatus according to Example 3, FIG. 6 is a front view of a die, FIG. 7 is a sectional view at the time of bending using the same die, and FIG. Is a cross-sectional view of the die, No. 9
Figure is the same front view, Figure 10 is a cross-sectional view during bending using the same die, Figure 11 is a cross-sectional view of a conventional push-through bending device, and Figure 12 is a graph showing the relationship between the bending ratio and the offset amount. FIG. 13 is a graph showing the relationship between the die tilt angle and the pushing load, FIG. 14 is a schematic sectional view of the pipe material, and FIG. 15 is a graph showing the influence of the die tilt angle on the flatness. 1 ... Die, 1a ... Annular protrusion 1b ... Bearing part, 2 ... Die holder 3 ... Guide cylinder, 3a ... Die control jig 3a '... Control curved surface, 4 ... Pipe material u ... Offset C1 …… Center of spherical surface of die C2 …… Center of bearing S …… Surface including bearing Ψ …… Inclination angle of die 21 …… Die, 21a …… Annular protrusion 21a ′ …… Abutment, 21b …… Bearing section 22 …… Die holder, 23 …… Guide cylinder 24 …… Tube material 25 …… Elastic ring member (die control ring) 31 …… Die, 31a …… Bearing section 32 …… Guide cylinder, 33 …… Pipe material 41 …… Die, 41a …… Bearing part 42 …… Guide cylinder, 43 …… Pipe material

Claims (4)

[Claims] [Claim 1] Tubing / shape or solid material (hereinafter referred to as "tubing, etc."
It is composed of a guide cylinder for inserting the guide cylinder and a die for holding a part of the pipe material penetrating the guide cylinder with a bearing portion, and the center axis of the guide cylinder and the center of the bearing portion of the die are relatively arranged. In a device that bends pipes, etc. by pushing them through the guide cylinder and the die while offsetting them (hereinafter referred to as "push-through bending device"), an annular projection is provided around the insertion side of the pipes and A die whose side surface is formed into a spherical curved surface having a center on the delivery port side of the pipe material or the like from the center of the bearing portion, and a curved surface that holds the spherical curved surface of the die are formed.
A die holder that holds the die opposite to the guide cylinder, and an annular member that is provided around the outlet side of the pipe and the like in the guide cylinder and that internally fits and faces the annular protrusion of the die, and the outer peripheral surface of the annular member. However, when the die rotates in the die holder and the annular projection of the die comes into contact with the die holder in an offset state due to the relative axial movement of the die holder and the guide cylinder, the surface including the bearing part of the die comes out of the guide cylinder. A die mechanism in a press-through bending apparatus, comprising a die control jig formed of a control curved surface that is set to be substantially vertical when viewed from the center of the die. 2. The push-through bending apparatus according to claim 1, wherein an annular projection is provided around the insertion port side of the pipe or the like, and the peripheral side surface is centered on the delivery side of the pipe or the like from the center of the bearing part. The die formed on the spherical curved surface having, and the curved surface that holds the spherical curved surface of the die are formed,
A die holder that holds the die opposite to the guide cylinder, and an elastic annular member that is fixedly installed on the side surface of the die holder that faces the guide cylinder. The inner circumference of the elastic annular member is generated by the rotation of the die inside the die holder. A die mechanism in a press-bending apparatus, comprising a die control ring in which the outer peripheral surface of the annular projection of the die is pressed against the surface. 3. The push-through bending apparatus according to claim 1, wherein when the pipe material or the like is a pipe having a circular cross section or a solid material, the shape of the bearing portion of the die is the relative shape of the die and the guide cylinder. The push-through bending apparatus characterized in that the bearing portion of the die as viewed from the center of the outlet of the guide cylinder is formed into an elliptical shape having a geometrical relationship in which it is substantially circular in an offset state due to the axial movement of the guide cylinder. Dice mechanism in. 4. The push-through bending apparatus according to claim 1, wherein the bearing portion of the die is in an offset state due to the relative axial movement of the die and the guide cylinder, and the bearing portion is the center of the delivery port of the guide cylinder. A die mechanism in a push-through bending apparatus, wherein the die mechanism is formed so as to be substantially vertical as viewed.