JPH07328726A - Method for bending pipe and device therefor - Google Patents

Abstract

PURPOSE:To provide a pipe bending method by which extra small bending is smoothly performed and a pipe bending device which is easily manufactured and surely usable. CONSTITUTION:The device is provided with a supporting jig 1, forming die 2, bolster member 9 (external member 9A and internal member 9B), cushion member, bar-shaped mandrel 23 and spherical mandrel 29; the spherical mandrel 29 is positioned in the center inside a pipe M with the bar-shaped mandrel 23 inserted on each side; and in a state where a pair of bolster members 9, which is provided turnobly in the supporting jig 1 and which is provided with a pipe inserting groove 13, are abutted on each other so as to be continuous in the longitudinal direction, the pipe M is inserted into the pipe inserting groove 13. After the inserting part of the pipe M for the spherical mandrel 29 is made to correspond to between the abutting ends of both bolster members 9, while the abutting ends of both external members 9 are supported by the cushion member, bending is performed by pressing the inserting part of the spherical mandrel 29 of the pipe M with a forming die 2 from the opposite side of both bolster members 9.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pipe bending method and apparatus.

[0002]

2. Description of the Related Art Heretofore, as a pipe bending method of this kind, a method using a pipe bending apparatus shown in FIG. 6 has been known.

The pipe bending apparatus includes a support jig 31 having a pair of support shafts 30, and a pipe insertion groove 32 into which the pipe M is inserted while being pivotally supported by both support shafts 30. And a pair of oscillating dies 33 (receiving members), which are set with their tips abutting each other so that the pipe insertion grooves 32 are continuous in the longitudinal direction, and are relatively contacted and separated from the support jig 31. And a ram 36 (molding die) for pressing the pipe M by the pressing portion 35, the pressing portion 35 having an arc-shaped forming groove 34 having a diameter of the pipe M is formed at the tip. It has a cushion member 37 that supports the abutting end of the swing die 32 from the opposite side of the ram 36.

When pipe bending is performed using such a pipe bending apparatus, the pipe M is inserted into the pipe insertion groove 32 with the oscillating dies 33 butted so that the pipe insertion grooves 32 are continuous in the longitudinal direction. Then, the pipe M is pressed by the ram 36 from the opposite side of the swing dies 33 while supporting the abutting ends of the swing dies 33 by the cushion member 37. At this time, the pipe M is pushed toward the space between the abutting ends of the swing dies 32 by the ram 36, and the cushion member 37 side of the pipe M is generated by the frictional force generated between the pipe M and the swing dies 33. As a result, elongation occurs at the portion, and as a result, the pipe M is bent to a bending radius suitable for the pressing portion 35.

However, in the above conventional pipe bending method, since the portion of the pipe M on the cushion member 37 side is not supported from the inside of the pipe M, the portion of the pipe M on the cushion member 37 side is stretched. The elongation is too small to keep up with the bending deformation. As a result, the portion of the pipe M on the cushion member 37 side extends and is displaced toward the ram 36 side. Therefore, it is preferable that the bending radius is large, but if the bending radius is small, the pipe M may become flat. From this point, the bending radius cannot be made too small.

Therefore, a pipe bending method using the pipe bending apparatus shown in FIG. 7 has been considered.

The pipe bending apparatus differs from the pipe bending apparatus described above in that a pair of rod-shaped mandrel 38 which are inserted into the pipe M from both sides are provided to eliminate the cushion member. The same parts are designated by the same reference numerals.

When performing pipe bending using such a pipe bending apparatus, the rod-shaped mandrel 38 is inserted into the pipe M from both sides, and the support shaft 3 of the support jig is inserted.
After inserting the pipe M into the pipe insertion groove in a state where a pair of receiving members 33 rotatably provided at 0 are butted so that the pipe insertion grooves are continuous in the longitudinal direction, the opposite sides of both receiving members 33 Then, the pipe M is pressed by the molding die 36 to be bent. At this time, the tip portion of the rod-shaped mandrel 38 is pressed against the portion of the pipe M opposite to the molding die 36 side,
A frictional force is generated between the rod-shaped mandrel 38 and the pipe M, and this frictional force makes it difficult for the rod-shaped mandrel 38 to retract. Minimum bending radius R
= Up to 3D (D: pipe outer diameter) up to 38 bar mandrel
As a result, the portion of the pipe M on the side opposite to the forming die 36 is stretched and prevented from being displaced to the forming die 36 side. As a result, the pipe M is bent without being flat and the bent portion of the pipe M is The rod-shaped mandrel 38 gradually recedes from there.

[0009]

However, in the above conventional pipe bending method using the rod-shaped mandrel 38,
When the minimum bending radius R is smaller than 3D and is, for example, equal to or smaller than the pipe outer diameter, the elongation generated at the portion of the pipe M on the opposite side of the forming die 36 side cannot catch up with the bending deformation, and therefore is displaced to the forming die 36 side. As a result, the pipe M becomes flat or broken. Even if the pipe M is annealed or surface-treated to increase the deformability of the pipe M, the bending radius R is up to the pipe outer diameter.
After all, the pipe M becomes flat and breaks.

Therefore, conventionally, in the case of performing a minimum bending,
Use a stretchable pipe material and apply heat to the bending part to bend it, and perform secondary processes such as hydraulic pressure, ball passing, sand pressure etc. as a countermeasure against buckling, flattening and destruction caused by it. Is being considered.

In this pipe bending method, however, the pipe can be bent in a very small amount, but it is necessary to use a stretchable pipe material and still carry out local heating and a secondary process, resulting in an increase in processing cost. At the same time, it causes a problem that it is difficult to maintain the optimum shape.

The present invention has been made to solve the above problems, and a first object of the present invention is to provide a pipe bending method capable of performing extremely small bending without difficulty.

A second object of the present invention is to provide a pipe bending apparatus which can be easily manufactured by a simple modification of an existing pipe bending apparatus and which can surely carry out the above pipe bending method. It is in.

[0014]

In order to achieve the first object, according to the present invention, as described in claim 1, a spherical mandrel is positioned in the center of the pipe, and the mandrel is provided on each side of the pipe. With the rod-shaped mandrel inserted, a pair of receiving members having a pipe insertion groove rotatably provided on the support jig are butted against each other so that the pipe insertion groove is continuous in the longitudinal direction. After inserting into the insertion groove and making the insertion part of the spherical mandrel of the pipe correspond between the abutting end portions of the both receiving members, while supporting the abutting end portions of the both receiving members by the cushion member. The bending portion is performed by pressing the insertion portion of the spherical cored bar of the pipe from the opposite side of the both receiving members with a molding die.

In order to achieve the second object,
As described in claim 2, the present invention comprises a support jig having a pair of support shafts, a pipe insertion groove into which a pipe is inserted, while being pivotally supported by the support shafts. , A pair of receiving members that are set by abutting each other so that the pipe insertion grooves are continuous in the longitudinal direction,
A pair of bar-shaped cores inserted from both sides into the pipe,
A pressing portion is provided so as to be relatively close to and away from the supporting jig, and a tip is provided with an arc-shaped forming groove having a diameter of the pipe, and the pipe is pressed by the pressing portion. In the pipe bending apparatus having a molding die for forming the receiving member, the respective receiving members are slid on the groove portions of the outer member having the groove portion pivotally supported by the support shaft and the pipe insertion groove. And a spherical cored bar disposed in the pipe between the rod-shaped cores, and the abutting end of each outer member is opposite to the molding die. The pipe is supported by a cushion member from the side, and the pipe is bent by pressing the pipe at the position of the spherical mandrel by the pressing portion.

[0016]

According to the structure described in claim 1, while the butt ends of both receiving members are supported by the cushion member from the opposite side of the forming die, the insertion portion of the spherical mandrel of the pipe is pressed by the forming die. To bend and deform the pipe, thereby generating a frictional force between the pipe and the rod-shaped mandrel inserted into the pipe from both sides, and this frictional force makes it difficult to retract the rod-shaped mandrel. The rod-shaped mandrel extends the cushion member side of the insertion part of the spherical mandrel of the pipe. Along with this extension, the pipe is slid in the pipe insertion grooves of both receiving members, so that the extension is free without being restrained by the receiving members. Further, the spherical mandrel inserted into the pipe restrains the insertion part from being bent before the bending is completed until the bending is completed. As a result, it is possible to bend the bending radius smaller than the pipe outer diameter, and it is possible to make a very small bend.

According to the above-mentioned structure of claim 2,
A pipe bending device of a type in which rod-shaped mandrel is inserted into the pipe from both sides is provided with a cushion member for supporting the abutting end of each receiving member from the opposite side of the forming die, and between the both rod-shaped mandrel. A pipe bending apparatus can be easily manufactured by using a spherical mandrel to be inserted into the pipe and configuring each of the receiving members with an outer member and an inner member.

The pipe bending process is performed as follows.
That is, the pipe is inserted into the pipe insertion groove of the paired inner members. In this pipe, a spherical mandrel is located in the center, rod-shaped mandrels are inserted on both sides, and the spherical mandrel is inserted between the abutting ends of the inner members by these rod-shaped mandrels. Place them correspondingly. After inserting the pipe, the molding die is moved closer to the insertion part of the spherical mandrel of the pipe to engage the forming groove of the pressing portion, and the pressing part inserts the spherical mandrel of the pipe. Press. At this time, the pipe is bent and deformed by the pressing by the molding die, and the butt ends of the outer members respectively accommodating the both inner members are supported by the cushion member while the pipe is centered on the support shaft of the outer member. Rotate.

During pressing by the molding die, the abutting ends of both outer members are supported by a cushion member,
A frictional force is generated between the pipe and the rod-shaped mandrel inserted into the pipe from both sides, and the frictional force makes it difficult for the rod-shaped mandrel to retreat. Extend the cushion member side. Further, the inner member is slidably accommodated in the groove portion of the outer member, and when the pipe is extended, the pipe is slid in the groove portions of the both outer members while the rod-shaped cores are inserted. Freely stretch the pipe. Further, the spherical mandrel inserted in the bent portion of the pipe restrains the pipe from flattening. Therefore, it becomes possible to carry out the pipe bending method.

[0020]

First, an embodiment of a pipe bending apparatus for carrying out the pipe bending method of the present invention will be described.

FIG. 1 (1) is a sectional view taken along the line AA of (2) showing a main part of a pipe bending apparatus according to an embodiment of the present invention, and (2) shows the same main part ( 1) is a side sectional view taken along the line BB, FIG. 2 is a side view of FIG. 1 (2), FIG. 3 is an explanatory view of the action of the main part of the pipe bending apparatus shown in FIG. 1, and FIG. FIG. 5 is a front view showing a state before the operation of the processing apparatus.
FIG. 4 is a front view showing a state after the operation of the pipe bending apparatus.

The pipe bending apparatus is provided with a supporting jig 1 and a molding die 2 as shown in FIGS. The supporting jig 1 is installed on the lower mounting frame 3, and the molding die 2 is mounted on the upper mounting frame 4 via a guide 5 so as to be vertically movable, and is supported by a cylinder 6 provided on the upper mounting frame 4. . The molding die 2 has the guide 5
Is provided so as to be brought into contact with and separated from the support jig 1 on the predetermined line L in the figure by being guided by the cylinder 6.

The supporting jig 1 has a pair of supporting walls 7 standing upright on the lower mounting frame 3 and a supporting shaft 10 installed between one side and the other side of the supporting walls 7. It is configured. Reference numeral 8 denotes a plurality of through holes formed in the lower mounting frame 3 facing the support walls 7.

Further, the pipe bending apparatus is provided with a pair of receiving members 9 rotatably supported by the support shafts 10 respectively, and the center of rotation of the receiving members 9 (the support shaft 1).
0) are arranged symmetrically with respect to the predetermined line L.

Each of the receiving members 9 has a pipe insertion groove 13 into which the pipe M is inserted.
Are stopped on a line connecting the centers of rotation by a stop mechanism (not shown) so that they are continuous in the longitudinal direction, and their front ends are abutted and set on the predetermined line L.

As shown in FIG. 1, each receiving member 9 has an outer member 9A having a groove portion 11 pivotally supported by the support shaft 10 and an outer member 9A having the pipe insertion groove 13. Inner member 9B slidably accommodated in the groove portion 11 of
It consists of and. The support shaft 10 is attached to each of a pair of side wall portions 12 forming the groove portion 11.
The inner member 9B is provided between the rear end of the outer member 9A and the rear end of the inner member 9B by the predetermined line L.
The spring 14 (elastic member) that biases the side is contracted. Further, an arcuate surface 15 centered on the support shaft 10 is formed at the tip of the outer member 9B from the bottom surface to the abutting portion, and the arcuate surface 15 causes the outer member 9A to push the pressing plate described later. It can be slid and rotated on 17.

Further, the pipe bending apparatus is provided with a cushion member 21 for supporting the abutting end portion of the outer member 9A from the opposite side of the molding die 2. That is, as shown in FIG. 5, rods 16 are vertically movably inserted into the through holes 8 provided in the lower mounting frame 3, and the upper ends of the rods 16 are joined by a push plate 17.
The lower end of the rod 16 is connected by a receiving plate 18. On the other hand, a bolt 19 (mounting member) that movably inserts the receiving plate 18 is vertically provided on the lower mounting frame 3.
A nut 20 (receiving portion) is provided in the insertion portion of the bolt 19. The cushion member 21 is contracted between the nut 20 and the receiving plate 18, and the force of the cushion member 21 causes the pushing plate 17 to move to the outer member 9.
It is in contact with the bottom surface of A. The force of the cushion member 21 is adjusted by rotating the nut 20.

Further, the pipe bending apparatus is provided with a pair of bar-shaped mandrel 23 which are inserted from both sides inside the pipe M inserted in the pipe insertion groove 13 of the inner member 9B. That is, the support member 22 facing the rear end of the inner member 9B is provided at the rear end portion of the outer member 9A, and a through hole is formed in the support member 22, and the rod-shaped core is provided in the through hole. Gold 23 is slidably inserted. Engaging portions 24 are provided at the base end portions of the rod-shaped mandrel 23, respectively. A cylinder 25 for taking out the mandrel is arranged in a V shape symmetrically with respect to the predetermined line L on the upper mounting frame 4, and an inverted V-shaped locking member 26 is provided at the rod tip of the cylinder 25. Is installed. The locking tool 26 is engaged with the base end portion of the rod-shaped mandrel 23 inserted into the pipe M when the pipe M is bent and deformed, and the rod-shaped mandrel 23 is engaged when the rod 25 of the cylinder 25 is retracted. It is possible to engage with the engaging portion 24 provided at the base end of the.

The molding die 2 has a pipe M at the tip thereof.
It has a substantially V-shaped pressing portion 27 in which an arc-shaped forming groove 28 having a diameter of is formed.

Further, the pipe bending apparatus includes, in addition to the rod-shaped mandrel 23, a spherical mandrel 29 inserted into the pipe M between the rod-shaped mandrels 23.

When pipe bending is performed using the pipe bending apparatus configured as described above, a spherical mandrel 29 is located in the center of the pipe M, and rod-shaped mandrels 23 are arranged on both sides. Is inserted. Then, the pipe M is inserted into the pipe insertion groove 13 in a state where the pair of inner members 9B are abutted so that the pipe insertion grooves 13 are continuous in the longitudinal direction, and the spherical mandrel 29 of the pipe M is inserted. The part is made to correspond between the abutting ends of the both inner members 9B.

Thereafter, the pressing portion 27 of the molding die 2 is guided from the opposite side of the inner members 9B to the spherical mandrel 2 of the pipe M while guiding the guide 5 by the rod extension operation of the cylinder 6.
9, the molding groove 28 of the pressing portion 27 is engaged with the insertion portion, and the pressing portion 27 presses the insertion portion of the spherical mandrel 29 of the pipe M.

At this time, as shown in FIG. 3, the abutting ends of both inner members 9B are supported by the cushion member 21, and the pipe M and the rod-shaped mandrel 23 inserted into the pipe M from both sides are provided. A frictional force is generated between the rod-shaped mandrel 2 and the bar-shaped mandrel 23 is made difficult to retreat by this frictional force.
The cushion member 21 side of the bent portion of the pipe M is extended by 3. Further, the inner member 9B is slidably accommodated in the groove portion 11 of the outer member 9A, and when the pipe M is extended, the pipe M is inserted into the rod-shaped mandrel 23 and the outer member 9A is inserted. The pipe M is slid in the groove 11 to freely extend the pipe M as shown by an arrow in FIG. Further, the spherical mandrel 29 inserted in the bent portion of the pipe M prevents the cushion member 21 side of the bent portion of the pipe M from being displaced toward the molding die 2 side, so that the pipe M does not become flat. The pipe M is restrained during bending.

In this way, the pipe M is bent, and along with this, the butted ends of the outer members 9A accommodating the inner members 9B are supported by the cushion member 21 while centering on the support shaft 10. Is rotated as.
When the bending process of the pipe M is completed, the rod-shaped mandrel 23 retracts as the pipe M extends, so that a gap is formed between the engaging portion 24 provided on the rod-shaped mandrel 23 and the support piece 22 provided on the outer member 9A. The locking tool 26 of the cylinder 25 is engaged with the rod-shaped mandrel 23 in the gap. Therefore, after completion of bending of the pipe M, the rod-shaped mandrel 23 can be taken out of the pipe M by the rod retraction operation of the cylinder 25.

As described above, by flexibly extending the cushion member 21 side of the bent portion of the pipe M and preventing the flatness at the bent portion of the pipe M, the bending radius can be bent smaller than the outer diameter of the pipe. Therefore, it is possible to make a very small bend with a commercially available pipe.

The effect test of the present invention is carried out by the pipe outer diameter D = 3.
.About.24 mm, wall thickness t = 0.6 to 1.5 mm, pipe material was nonferrous metal to iron steel such as alloy steel, and pipe structure was seamless, double wound steel pipe and other various pipes. As a result, without causing flatness or wrinkles on the pipe, peeling of the plating when inner surface plating is applied, and without heating the bent portion of the pipe, the maximum bending angle is 110 ° and the minimum bending radius is 110 °. R = 0.
It was found that a minimum bending of 35D (D: pipe outer diameter) or less can be performed, and a minimum bending of R = 0.2D is also possible.

In the above embodiment, the molding die 2 is arranged above and the receiving member 9 and the like are arranged below, but the arrangement relationship may be reversed, for example.

The spherical mandrel is not limited to a perfect sphere, but may be an ellipse or the like by bending, or one in which a spherical surface is formed at the tip of the rod so that it can be easily taken after molding, at least a part of which is spherical. If it is good.

[0039]

As described above, according to the present invention, the spherical mandrel is positioned in the center of the pipe, the rod-shaped mandrels are inserted on both sides, and the support jig is rotatably provided. The pair of receiving members having the pipe insertion groove are inserted into the pipe insertion groove in a state in which the pipe insertion groove is abutted so as to be continuous in the longitudinal direction, and the insertion portion of the spherical mandrel of the pipe is After making the abutting ends of both receiving members correspond to each other, while supporting the abutting ends of the both receiving members by a cushion member, the insertion portion of the spherical mandrel of the pipe from the opposite side of the both receiving members. Since the mold is pressed by the mold to perform the bending process, while supporting the butt ends of both receiving members from the opposite side of the mold with the cushion member, the insertion part of the spherical mandrel of the pipe is pressed by the pressing part of the mold. Press the pipe Bending deformation causes a frictional force to be generated between the pipe and the rod-shaped mandrel inserted into the pipe from both sides, and the frictional force makes it difficult for the rod-shaped mandrel to retreat. The cushion member side of the insertion portion of the spherical mandrel can be extended, and with this extension, the pipe is slid in the pipe insertion groove of both receiving members while the rod-shaped mandrel is inserted, The extension can be made free without restraining by both receiving members. Further, the spherical mandrel inserted into the pipe can restrain the insertion portion so that the pipe does not flatten during bending. Therefore, unlike the conventional case, the bending radius can be smaller than the pipe outer diameter in one bending step, and the minimum bending can be performed, so that the efficiency of the working operation can be improved.

Further, the present invention comprises a support jig having a pair of support shafts, a pipe insertion groove rotatably supported by the support shafts, and a pipe insertion groove into which the pipes are inserted. A pair of receiving members that are set so that their distal ends abut against each other so that the insertion grooves are continuous in the longitudinal direction, a pair of rod-shaped cores that are inserted into the pipe from both sides, and a support jig Bending with a pressing die having a circular arc-shaped forming groove having substantially the same diameter as the pipe, and a forming die for pressing the pipe by the pressing portion. In the processing device, each receiving member has an outer member having a groove portion pivotally supported by the support shaft and an inner member having the pipe insertion groove and slidably accommodated in the groove portion of the outer member. And consists of both A spherical mandrel is arranged in the pipe between the cored mandrels, and the abutting ends of the outer members are supported by a cushion member from the opposite side of the molding die, and the pipe is the spherical mandrel. Since the bending is performed by pressing with the pressing portion at the position, each receiving member of the pipe bending apparatus is composed of an outer member and an inner member, and the abutting end portion of each outer member is formed. A simple modification to attach a cushion member that supports from the opposite side of the mold,
With the use of a spherical mandrel inserted into the pipe between the rod-shaped mandrels, the mandrel can be manufactured in a conventional manner, and the pipe bending method can be reliably performed.

[Brief description of drawings]

FIG. 1 is a front sectional view taken along line AA of (2) showing a main part of a pipe bending apparatus according to an embodiment of the present invention. (2) It is a side sectional view taken along the line BB of (1) showing the main part.

FIG. 2 is a side view of FIG. 1 (2).

FIG. 3 is an operation explanatory view of a main part of the pipe bending apparatus shown in FIG.

FIG. 4 is a front view showing a state before the operation of the pipe bending apparatus.

FIG. 5 is a front view showing a state after the operation of the pipe bending apparatus.

FIG. 6 is a front view showing a conventional pipe bending apparatus.

FIG. 7 (1) is a front view showing another conventional pipe bending apparatus. (2) It is a front view showing a state after the operation of the pipe bending apparatus.

[Explanation of symbols]

 M Pipe 1 Support jig 2 Mold 9 Receiving member 9A Outer member 9B Inner member 10 Support shaft 11 Groove portion 13 Pipe insertion groove 21 Cushion member 23 Rod-shaped mandrel 27 Pressing portion 28 Forming groove 29 Spherical mandrel

Front page continued (72) Inventor Koichi Komatsu 1 at 52 Kamigada, Susono City, Shizuoka Prefecture

Claims (2)

[Claims] 1. A pair of pipes each having a spherical mandrel positioned in the center of the pipe, rod-shaped mandrels inserted on both sides, and a pipe insertion groove rotatably provided on a supporting jig. The pipe is inserted into the pipe insertion groove in a state where the receiving member is abutted so that the pipe insertion groove is continuous in the longitudinal direction, and the insertion portion of the spherical mandrel of the pipe is abutting end portions of the both receiving members. After making them correspond to each other, while supporting the abutting ends of the both receiving members by the cushion member,
A method for bending a pipe, characterized in that a portion for inserting the spherical mandrel of the pipe is pressed from a side opposite to the receiving members with a molding die to perform bending. 2. A support jig having a pair of support shafts, and a pipe insertion groove into which a pipe is inserted and which is rotatably supported by the support shafts, respectively. A pair of receiving members set so that their front ends abut against each other so as to be continuous in a direction, a pair of rod-shaped mandrel inserted into the pipe from both sides, and relatively contact with and separated from the supporting jig. A pipe bending apparatus having a pressing portion provided with a pressing portion in which an arc-shaped forming groove having a diameter of the pipe is formed at the tip, and the forming die pressing the pipe by the pressing portion, Each of the receiving members is composed of an outer member having a groove portion pivotally supported by the support shaft and an inner member having the pipe insertion groove and slidably accommodated in the groove portion of the outer member. Together with the pad between the rod-shaped mandrel. A spherical mandrel is disposed in the pipe, the abutting ends of the outer members are supported by a cushion member from the opposite side of the mold, and the pipe is pressed at the position of the spherical mandrel. A pipe bending apparatus characterized in that bending is performed by pressing by a section.