JPH10118719A - Double tube bending method and its device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrain the generation of cross section deformations and wrinkles with a simple structure and process in the case of bending a double tube. SOLUTION: In the case of bending the double tube by holding the double tube 4 having an outer tube 4a and an inner tube 4b inserted with a gap 18 between the outer tube 4a with a bending die and a clamping die and revolving the clamping die around the bending die, a core bar 42 capable of expanding the inner tube 4b into an elliptic shape is inserted into the inner tube 4b, and bending is executed in the state expanded until the inner tube comes into contact with the inner periphery of the outer tube 4a. The core bar 42 is provided in the end of a hollow supporting axis 40 inserted into the inner tube 4b and provided with expanding members 54, 56 radically moving by the movement of a driving axis 66 inserted into the supporting axis 40 so as to be movable. Also, a prescribed pressure of liquid is fed from the feeding hole 66a of the driving axis 66 into the inner tube 4b after bending to return the inner tube 4b into the circular shape.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bending method and an apparatus for bending a tube by clamping a tube between a bending die and a clamping die and revolving the clamping die around the bending die. The present invention relates to a double pipe bending method and a double pipe bending method for bending a double pipe having an inner pipe inserted with a gap between the pipe and the outer pipe.

[0002]

2. Description of the Related Art Conventionally, in bending a pipe, a core metal has been used to suppress cross-sectional deformation and wrinkles. However, a pipe is inserted between an outer pipe and the outer pipe with a gap. In the case of a double pipe having an inner pipe, even if a core metal is inserted into the inner pipe, it is not possible to prevent cross-sectional deformation and wrinkles of the outer pipe. Therefore, as disclosed in Japanese Patent Application Laid-Open No. Sho 62-9724, a wire mesh is interposed between the outer tube and the inner tube, and a liquid is filled between the outer tube and the metal tube. It is also known that the liquid is heated, returned to a liquid, and then discharged.

[0003]

However, in such a conventional pipe bending process, ice frozen during bending processing breaks and pops out of a gap between the outer pipe and the inner pipe,
Bending work cannot effectively suppress cross-sectional deformation and wrinkles.In addition, a wire mesh must be interposed between the outer pipe and the inner pipe, and the liquid is filled, cooled, solidified, and bent. There is a problem in that it is necessary to liquefy by post-heating, the process is complicated, and a liquid cooling device and a heating device must be provided, and the structure becomes complicated.

An object of the present invention is to provide a method and apparatus for bending a double pipe, which can effectively suppress cross-sectional deformation and wrinkles by a simple process and have a simple structure.

[0005]

In order to solve the above problems, the present invention employs the following method. That is, in a bending method in which a pipe is sandwiched between a bending die and a clamping die, and the clamping die is revolved around the bending die to bend the pipe, the pipe includes an outer pipe and a gap between the outer pipe and the outer pipe. After inserting a core into the inner tube, the inner tube is expanded by the core until the inner tube comes into contact with the inner periphery of the outer tube. This is a method of bending a double pipe, wherein the bending is performed by the bending die and the clamping die. After bending by the bending die and the clamping die, fluid pressure may be applied to the inner pipe to return it to a circular shape.

Further, the present invention has taken the following means in order to solve such a problem. That is, in a bending apparatus in which a pipe is sandwiched between a bending die and a clamping die, and the clamping die revolves around the bending die to bend the pipe, the pipe has a gap between the outer pipe and the outer pipe. A double pipe having an inner pipe inserted with a gap between the inner pipe and a core metal capable of being inserted into the inner pipe and expanding the inner pipe into an elliptical shape. That is it.

The core bar is provided at the tip of a hollow support shaft inserted into the inner tube, and is expanded in a radial direction by the movement of a drive shaft movably inserted into the support shaft. Alternatively, the drive shaft may have a supply hole penetrating in the axial direction, and a pressure source for supplying a liquid having a predetermined pressure from the supply hole into the inner pipe may be provided.

[0008]

Embodiments of the present invention will be described below in detail with reference to the drawings. As shown in FIG. 5, reference numeral 1 denotes an apparatus main body, and a bending mold 2 formed in accordance with a bending radius is disposed on the front side of the apparatus main body 1. A groove 6 corresponding to the outer diameter is formed. A clamping die 8 is supported on a bending arm 9 so as to be able to approach and separate from the bending die 2 so as to face the bending die 2.
And the groove 6 of the bending die 2 and the groove 10 formed in the clamping die 8 can clamp the double pipe 4.

The bending arm 9 is driven to rotate around the center C of the bending die 2 and revolves the clamping die 8 around the bending die 2 in the direction of the arrow in FIG. Thus, the double pipe 4 can be bent. Bending mold 2
The double pipe 4 is pressed and bent so as to be wound around the groove 6 of the bending die 2 without rotating. The pressure mold 12 receiving the bending reaction force at this time is arranged adjacent to the clamping mold 8.

A pair of rails 14 and 15 are laid on the apparatus main body 1 along the axial direction of the double pipe 4, and a movable table 16 is provided on the rails 14 and 15 along the rails 14 and 15. Movably engaged with each other and moved along the rails 14 and 15 by a drive mechanism (not shown).

As shown in FIGS. 1 and 3, the double pipe 4 has an outer pipe 4a and an inner pipe 4b inserted into the outer pipe 4a with a gap 18 therebetween. One end with 4b is closed by lid 4c. The lid 4c may be welded to the outer tube 4a and the inner tube 4b, or may be sealed with an O-ring or the like, inserted into the outer tube 4a and the inner tube 4b, and closed at one end by caulking or the like. Is also good.

A chuck mechanism 20 for gripping the other end of the double pipe 4 is mounted on the moving table 16, and the chuck mechanism 2
0 is supported by the chuck body 22 so as to be movable radially,
The three claws 24, 25 (only some of which are shown) that move toward the outer tube 4a by the supplied pressure fluid,
This is a configuration that grips the outer periphery of a.

As shown in FIG. 6, the chuck body 22 is
It is fixed to the front end surface of a rotating shaft 28 supported by bearings 26 and 27 on the moving table 16. A pulley 30 is fixed to the rear end of the rotating shaft 28, and the rotating shaft 28 can be rotated by a predetermined angle by a motor 32 mounted on the moving table 16 via a belt 31 wrapped around the pulley 30. It is configured to be able to.

An insertion tube 36 that can be inserted into the gap 18 coaxially with the double tube 4 is inserted and fixed to the rotating shaft 28.
The tip of the insertion tube 36 has the claw 24 of the chuck mechanism 20,
It extends to the inside of 25. The outer diameter and the inner diameter of the insertion tube 36 are substantially the same as the inner diameter of the outer tube 4a and the outer diameter of the inner tube 4b, respectively.
6 can be easily inserted, and the outer tube 4 is
The outer tube 4a is formed so that the outer tube 4a does not deform when the outer periphery of the outer tube 4a is gripped. When the double pipe 4 is inserted into the insertion pipe 36, the other end of the outer pipe 4a is formed to abut on the end face of the rotating shaft 28.

On the other hand, a support member 3
The support member 38 is fixed to the support member 38 at one end of a hollow support shaft 40 arranged coaxially with the double pipe 4. The tip of the support shaft 40 penetrates the rotary shaft 28 and is inserted into the inner tube 4b from the other end of the inner tube 4b, and the tip of the support shaft 40 extends to near the center C of the bending mold 2. Have been. The outer diameter of the support shaft 40 is formed such that it can be inserted into the inner diameter of the inner tube 4b, and the O-ring 41 is fitted to prevent leakage.

At the tip of the support shaft 40, a main body 4 of a metal core 42 is provided.
4 is screwed, and the main body 44 has an inner tube 4
It is formed in a substantially elliptical shape that can be inserted into b. And
As shown in FIG. 2, they are arranged so that the major axis direction is orthogonal to the center C of the bending die 2. Further, the main body 44 has a screw hole 46 from the tip end side, and a bottomed hole 4 connected to the screw hole 46.
8. A rectangular storage hole 5 formed with a through hole 49 connected to the bottomed hole 48 and opened in the longitudinal direction.
0, 52 are formed on both sides connected to the bottomed hole 48. Enlarged diameter members 54, 5 are provided in storage holes 50, 52, respectively.
6 are slidably inserted in the radial direction.

A hollow moving shaft 58 is movably inserted into the bottomed hole 48 and the through hole 49, and is provided between the moving shaft 58 in the bottomed hole 48 and the diameter-enlarging members 54 and 56. A cylindrical holding member 60 is arranged. A steel ball 62 is inserted into the holding member 60 so as to be able to move in the radial direction in two rows in contact with the large-diameter members 54 and 56, and a hollow nut 64 screwed into the screw hole 46 of the main body 44. The movement of the holding member 60 in the axial direction is restricted.

A recess 58a is formed on the outer periphery of the moving shaft 58 in correspondence with the steel ball 62. As shown in FIG. 3, when the steel ball 62 enters the recess 58a,
The enlarged diameter members 54 and 56 are formed so as not to protrude from the main body 44. When the moving shaft 58 is moved, the steel ball 62 is extruded in the radial direction, and the enlarged diameter members 54 and 56 are moved in the radial direction. Expanding member 5
The amount of movement of the steel balls 62 is such that the inner tube 4b is extended in the longitudinal direction and the outer tube 4a is extended without contacting the inner periphery of the outer tube 4a without deformation. Has been selected.

On the other hand, the moving shaft 58 is screwed to a distal end of a driving shaft 66 inserted in the hollow supporting shaft 40 so as to be movable in the axial direction. The other end of the drive shaft 66 is configured to penetrate the support member 38 and be driven in the axial direction by a cylinder 68 attached to the support member 38.

A through hole 66a is formed in the drive shaft 66 in the axial direction, and a pressure source 70 for supplying a liquid of a predetermined pressure is connected to the through hole 66a. The passage 40a between the support shaft 40 and the drive shaft 66 is communicated with the inside of the inner tube 4b by a groove 40b and a through hole 40c formed on the outer periphery of the distal end of the support shaft 40 (see FIGS. 4 and 6). With the discharge hole 80
Is connected to the pressure source 70 via the.

Next, the operation of the above-described double pipe bending apparatus of this embodiment will be described. First, the metal core 42 is put into the inner pipe 4 b of the double pipe 4, and the double pipe 4 is inserted along the support shaft 40. In the gap 18 between the outer pipe 4a and the inner pipe 4b,
The insertion tube 36 is inserted, and the end of the outer tube 4a is abutted on the rotating shaft 28. Next, a pressurized fluid is supplied to the chuck mechanism 20 to move the claws 24 and 25 toward the outer tube 4a. The outer circumference of the outer tube 4a is pressed by the claws 24, 25, and the outer tube 4a is gripped by the claws 24, 25 and the insertion tube 36.

A carriage 16 is moved along the rails 14 and 15 to supply the double pipe 4 between the bending mold 2 and the clamping mold 8. Then, after moving the bent portion of the double pipe 4 to a position corresponding to the bending die 2, the movement of the movable base 16 is stopped,
The cylinder 68 is driven to move the drive shaft 66 in the axial direction. As a result, the moving shaft 58 is also moved, the steel ball 62 is pushed out from the recess 58a, the radially expanding members 54 and 56 are moved in the radial direction, the inner pipe 4b is expanded in an elliptical shape, and the outer pipe 4a is expanded. Contacted to the inner circumference.

Subsequently, the clamping die 8 is moved toward the bending die 2 so that the double pipe 4 is sandwiched between the bending die 2 and the clamping die 8 and the pressure die 12 is brought into contact with the outer periphery of the double pipe 4. Let it. By rotating the bending arm 9, the clamping die 8 revolves around the bending die 2. Thus, the double pipe 4 is pressed and bent in accordance with the shape of the bending mold 2.

At this time, since the inner tube 4b expanded by the diameter-enlarging members 54 and 56 of the metal core 42 is in contact with the inner periphery of the outer tube 4a, cross-sectional deformation and wrinkling of the outer tube 4a are prevented. Is done. Since the inner tube 4b is held coaxially with the outer tube 4a, the inner tube 4b is also bent according to the shape of the bending mold 2. In this manner, the double pipe 4 can be bent while suppressing cross-sectional deformation and wrinkles in a simple process of expanding and bending the metal core 42. Also, the core metal 42 having a simple structure is used.
Thereby, the double pipe 4 can be bent.

After the clamping die 8 is revolved around the bending die 2 by a predetermined angle and bent, the clamping die 8 is separated from the bending die 2 and revolved in the opposite direction to return to the original position. Then, the movable table 16 is moved to move the next bent portion to a position corresponding to the bending die 2. At this time, when the bending directions are different, the motor 32 is driven to drive the belt 31, the pulley 30,
The double pipe 4 is rotated via the rotation shaft 28 and the chuck mechanism 20. Then, as described above, the double pipe 4 is clamped and bent by the clamping die 8 and the bending die 2.

On the other hand, during this time, the pressure source 70
A liquid at a predetermined pressure is supplied into the inner tube 4b through the inner tube 4b.
The air in the inner pipe 4b is exhausted from the passage 40a between the support shaft 40 and the drive shaft 66 via the discharge hole 80. Accordingly, a fluid pressure of a liquid having a predetermined pressure is applied to the inner periphery of the inner tube 4b, and the inner tube 4b deformed into an elliptical shape by the cored bar 42.
Acts to return the cross section of the to a circular shape.

As a result, the inner tube 4b is returned to a circular shape. After the bending, the liquid filled in the inner tube 4b is discharged from the discharge hole 80 and the like, and the claws 24 and 25 are moved in the radial direction. To release the grip of the double pipe 4. Then, the double tube 4 is pulled out from the insertion tube 36 and the cored bar 42, and a new double tube 4 is inserted. If the cross-sectional shape of the inner tube 4b remains elliptical and there is no problem in use, the bending may be completed without applying fluid pressure.

Next, a second embodiment of the metal core 100 different from the above-described metal core 42 will be described with reference to FIG. still,
The same members as those in the above-described embodiment are denoted by the same reference numerals, and detailed description is omitted. This core metal 100 is
The drive shaft 106 is formed in the through hole 105 formed in
Is movably inserted in the corrugated uneven portion 108 formed at the tip of the. The main body 102 having an elliptical cross section
Rectangular storage hole 11 opened toward the long axis direction
0, 112 are formed on both sides connected to the through-hole 105. Diameter-enlarging members 104 and 106 are inserted into the storage holes 110 and 112 so as to be slidable in the radial direction, respectively.

The back side of each of the diameter-enlarging members 104 and 106 is formed in a corrugated shape corresponding to the uneven portion 108.
When the corrugations of the corrugations 08 and the corrugations of the expanding members 104 and 106 coincide with each other, the expanding members 104 and 106
0, 112 so as not to protrude from the main body 102.

Then, the corrugation of the uneven portion 108 and the diameter-enlarged member 1
When the wave-shaped protrusions 04 and 106 coincide with each other, the diameter-enlarging members 104 and 106 are moved in the radial direction. The amount of movement of the diameter-enlarging members 104 and 106 is corrugated so as to expand the inner tube 4b in the long axis direction and expand the inner tube 4b to such an extent that the inner tube 4b contacts the inner periphery of the outer tube 4a without deforming the outer tube 4a. Irregularities are formed. Note that three elastic rings 114 are fitted to the enlarged diameter members 104 and 106, and the enlarged diameter members 104 and
106 is urged toward the center.

Also in this cored bar 100, when the drive shaft 106 is moved in the axial direction, the enlarged diameter members 104, 106 are moved in the radial direction against the biasing force of the elastic ring 114. Then, the inner tube 4b is brought into contact with the inner periphery of the outer tube 4a, and bending is performed in this state, whereby the cross-sectional deformation and wrinkling of the outer tube 4a can be prevented as described above. Further, the structure of the cored bar 100 is simpler than that of the cored bar 42 described above.

As described above, the present invention is not limited to such an embodiment, and can be implemented in various modes without departing from the gist of the present invention.

[0033]

As described above in detail, according to the method of bending a double pipe of the present invention, the outer pipe can be deformed in cross-section and wrinkled by a simple process of bending while the inner pipe is expanded by the core metal. This has the effect that bending can be performed while preventing occurrence of cracks. In addition, the section can be returned to a circular shape by applying a fluid pressure to the inner tube.

Further, according to the double pipe bending apparatus, there is an effect that the core pipe having a simple structure can be bent while preventing cross-sectional deformation and wrinkling of the outer pipe. In addition, the section can be returned to a circular shape by applying fluid pressure to the inner tube from the supply hole.

[Brief description of the drawings]

FIG. 1 is an enlarged sectional view of a double pipe bending apparatus as one embodiment of the present invention, in which a diameter expanding member of a metal core is moved in a radial direction.

FIG. 2 is a sectional view taken along the line AA of FIG.

FIG. 3 is an enlarged cross-sectional view of a state before moving a diameter-enlarging member of a core metal according to the present embodiment.

FIG. 4 is a sectional view taken along the line BB of FIG. 3;

FIG. 5 is a schematic perspective view of a double pipe bending apparatus of the present embodiment.

FIG. 6 is a schematic configuration diagram of a double pipe bending apparatus of the present embodiment.

FIG. 7 is an enlarged cross-sectional view of a state in which the core expanding member of the second embodiment is moved in the radial direction.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Device main body 2 ... Bending mold 4 ... Double pipe 4a ... Outer pipe 4b ... Inner pipe 8 ... Clamping mold 40 ... Support shaft 42, 100 ... Core metal 54, 56, 104, 106 ... Diameter expansion member 58 ... Moving shaft 62: steel ball 66, 106: drive shaft

Continued on the front page (51) Int.Cl. ⁶ Identification code FI B21D 39/04 B21D 39/04 E

Claims (5)

[Claims] 1. A bending method in which a pipe is sandwiched between a bending die and a clamping die, and the clamping die revolves around the bending die to bend the pipe. A double pipe having an inner pipe inserted with a gap in the pipe, after inserting a core into the inner pipe, the inner pipe is expanded by the core until the inner pipe comes into contact with the inner circumference of the outer pipe. In the bent state by the bending die and the clamping die. 2. The method of bending a double pipe according to claim 1, wherein the inner pipe is returned to a circular shape by applying a fluid pressure to the inner pipe after bending by the bending mold and the clamping mold. 3. A bending apparatus for clamping a pipe between a bending die and a clamping die, and revolving the clamping die around the bending die to bend the pipe, wherein the pipe is an outer pipe and the outer pipe. A double pipe having an inner pipe inserted with a gap in the pipe, comprising: a core metal inserted into the inner pipe and capable of expanding the inner pipe into an elliptical shape. Processing equipment. 4. The expansion bar, which is provided at the tip of a hollow support shaft inserted into the inner tube, and which moves in a radial direction by the movement of a drive shaft movably inserted into the support shaft. The bending apparatus according to claim 3, further comprising a diameter member. 5. The drive shaft according to claim 4, wherein the drive shaft has a supply hole penetrating in the axial direction, and a pressure source for supplying a liquid at a predetermined pressure from the supply hole into the inner tube is provided. Double pipe bending equipment.