JP2000237832A - Method and device for expanding metal tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To expand a metal tube without thinning by approaching one of rotation holding bodies to the other in a state in which the rotation around the axis is applied to the metal tube on the straight line held with a pair of rotation holding bodies facing each other, biasing to the direction crossing to the axis and then eliminating the bias to restore to the original state. SOLUTION: A drive rotation part 5 and a driven rotation part 14 are arranged so that the axis of their holding cylinder 7, 20 are coaxially positioned. Next, after a metal tube is inserted into the chuck sleeve of the drive rotation part 5 and the driven rotation part 14 and is held, the interval between the chuck sleeves 9, 21 is set to a prescribed interval by a feed device 23. Next, the metal tube is pressed in the axial direction by a pressing device 32, a motor is operated, and then the metal tube held between the chuck sleeves 9, 21 is rotated. Successively, the metal tube is bent by a bias device. The part of the metal tube between the chuck sleeve part is compressed and expanded by these pressing, rotation, bending, while continuing rotation, pressing, the bias device is restored to the original state.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for expanding a part of a metal tube. More specifically, a convex portion having a larger diameter than other portions is formed at an intermediate portion of the metal tube, that is, at an arbitrary position in the axial direction.

[0002]

2. Description of the Related Art Conventionally, telescopic joints which are used when a part of equipment requires flexibility, sealing performance, etc.
A bell-shaped metal tube such as a bellows tube is used for a flexible tube or the like. As a bellows manufacturing technique, for example, a bulge forming method using a bulge hydraulic pressure as described in Japanese Patent Publication No. 3-42969 is known. This bulge forming method is a technique of injecting a bulge liquid into a metal tube and applying pressure to process the metal tube into a shape that matches a mold. However, this method has a disadvantage that the expanded portion of the tube is reduced in thickness.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a method and an apparatus for expanding a metal tube without reducing the thickness of the metal tube.

[0004]

The present invention has been made as follows in order to solve the above-mentioned problems. In other words, a pair of rotating holders opposing each other grip a linear metal tube at an appropriate interval D, and rotate the metal tube around its axis.
By moving at least one of the rotating holders in a direction approaching the other, and gradually shifting one of the rotating holders in a direction intersecting the axis of the other rotating holder, the inside and outside of the bending After applying compressive and bending forces to the rotating metal tube under conditions where compressive stress is always applied, plastic deformation in the expanding direction of the metal tube between the two rotation holding bodies occurs, and then the inside and outside of the bending In the method described above, the bias is gradually restored while maintaining the condition in which the compressive stress acts, thereby forming an expanded portion in the middle of the metal tube.

Further, a pair of rotatable holders which are opposed to each other and are rotatable so that at least one intersects the other axis are provided, and at least one of the rotatable holders approaches and separates from the other rotatable holder. It is characterized in that a pressurizing or feeding means, a driving means for rotating at least one of the rotating holders, and a biasing means for rotating at least one of the rotating holders so as to intersect the other axis are provided.

[0006]

The method for expanding and forming a metal tube W according to the present invention will be described in detail. First, a straight metal tube W as a work is gripped and held by a pair of rotating holders facing each other. The rotation holder may be, for example, a chuck of a lathe, and may be any as long as it can hold and rotate the metal tube W firmly at an appropriate interval D. If the metal tube W to be expanded is short, a chuck sleeve that can be pressed from the end of the metal tube W may be used. Distance D to be gripped by both rotating holders
May be changed in the range of several tens of millimeters to several hundreds of millimeters according to the inner and outer diameters of the metal tube W, the expansion amount, and the length of the expansion portion.

In this state, at least one of the rotary holders is driven to rotate, and the gripping metal tube W is rotated. This rotation speed is usually several revolutions per minute to several hundred revolutions, and the metal tube W
It is sufficient to select the most suitable one according to the material, dimensions, etc. On the other hand, if the rotation speed is low, the molding time is long. If the rotation speed is too high, it is difficult to make the pressure follow the plastic deformation when the plastic deformation described later occurs, and there is a possibility that a fracture may occur due to fatigue.

Next, a compressive force is applied to the rotating metal tube W. This compression is usually performed by a hydraulic jack or a hydraulic cylinder. This compression force varies depending on the material, outer diameter, and wall thickness of the metal tube W. However, a desired shape can be obtained with an extremely small compression force as compared with the compression force at the time of bulging.

A force in the bending direction is applied to the metal tube W while maintaining the rotation and the compressed state. This bending force biases any one of the rotary holders in a direction intersecting the axis of the other rotary holder using, for example, a screw-type feeder. Then, the metal tube W between both rotation holding bodies is curved,
Rotate. The bending angle is several degrees to several tens of degrees. If the angle is too small, a desired shape cannot be obtained. Conversely, if the angle is too large, an excessive force acts on the curved portion of the metal tube W, and The tube W is damaged.

As described above, when the metal tube W is bent while applying a compressive force, a strong compressive force acts on the inside of the bent portion, so that plastic deformation occurs in this portion, and the deformation in the direction in which the compressive force is released, that is, deformation. A bulge in the expanding direction occurs. Since the metal pipe W is rotating, the entire circumference of the metal pipe W is alternately located inside the bend, and plastic deformation occurs over the entire circumference. At this time, it is important to apply a compressive force to the outside of the curved portion. If a tensile force is applied to the outer portion, the metal tube W alternately expands and contracts and breaks due to fatigue. I do. In addition, when the expansion in the tube expanding direction occurs, the initial gripping distance D is reduced by that much. However, since the compressive force has to act on the entire circumference of the curved portion as described above, any amount corresponding to the reduction in the distance is used. Continuous pressure must be applied to bring one of the rotating supports closer to the other. As described above, since the compression and bending are performed while rotating the metal tube W, the metal tube W can be expanded with a small compression force as compared with bulging.

After the desired expansion is performed, the axes of both the rotation holding portions are returned to be straight so as to return the bending of the metal tube W, and the metal tube W is straightened. Also in this case, a compressive force is always applied to the inside and outside of the bend. Here, when the compression is loosened, the elongation and the contraction repeatedly act on the bent portion of the metal tube W as described above, and there is a possibility that the metal tube W is broken. If the expanded metal tube W can be straightened, the compression force may be removed, the rotation may be stopped, and the metal tube W may be removed.

According to the present tube expansion method, the metal tube W is expanded and formed by applying rotation and bending while applying a compressive force in the axial direction to the metal tube W. It is shorter in comparison. The shortened portion of the metal tube W is absorbed by the expanded portion, and the expanded portion has a thickness greater than that of the material. As described above, since the expanded portion is not reduced in thickness, the strength is increased as compared with the conventional bulge-processed product.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the processing apparatus according to the present invention will be described below with reference to the drawings. In this tube expanding apparatus 1, a pair of side plates 3 are erected on a side portion of a base 2 placed on a floor, and a rectangular frame 4 in a plan view is provided thereon.
At the front end of the frame 4 is provided a drive rotation unit 5 which is one of the rotation holders.

The driving rotary unit 5 includes a cylindrical holding cylinder 7 inside a support cylinder 6 fixed to a member 5a in the left-right direction of the frame 4.
Is rotatably supported, and a driven gear 8 is attached to an end of the holding cylinder 7. A chuck sleeve 9 is fitted inside the holding cylinder 7 as a chuck member for holding the metal tube W. The core of the chuck sleeve 9 is provided with a holding hole 9a into which the metal tube W is fitted, and the front end of the chuck sleeve 9 is provided with a slit 9b in the front-rear direction. The metal pipe W is held by attaching the fixing members 10 and 10 to the slit portions 9b and tightening the bolts 11 and 11, respectively.

A motor 12 as a drive source is provided below the support cylinder 6, and a drive gear 13 attached to an output shaft of the motor 12 meshes with the driven gear 8.

A driven rotation unit 14 as the other rotation holding member is provided so as to face the drive rotation unit 5. The driven rotating unit 14 includes a sliding body 16 that slides back and forth along a rail 15 provided on an upper edge of the frame 4,
A ring-shaped rotating frame 17 is pivotally connected to an end of the sliding body 16 by a shaft 18. This rotating frame 17
A support cylinder 19 on the driven side is fixedly mounted on the, and a holding cylinder 20 is rotatably supported inside the support cylinder 19. A chuck sleeve 21 for holding a work similar to the chuck sleeve 9 of the drive rotating unit 5 is fitted inside the holding cylinder 20. A holding hole 21a is provided in the core of the chuck sleeve 21, and a slit 21b in the front-rear direction is provided at the rear end of the holding hole 21a.
b is fastened by the fixture 22 to hold the metal tube W.

A feeder 23 is provided at the rear of the slide 16. The feed device 23 serves as feed means for moving the driven rotary unit 14 back and forth in a direction approaching and moving away from the drive rotary unit 5, and a bracket 24 is provided at the rear end of the sliding body 16. Is provided with a bearing 25. The horizontal frame 26 at the rear end of the frame 4 is provided with a through hole 26a, and a tubular body 27 constituting a feeding means is fixed to the front side. The cylindrical body 27 is provided with a slit 27a in the front-rear direction, and a moving block 28 having a screw hole in the front-rear direction is provided inside the cylinder 27, with a protrusion 28a provided at the upper end thereof projecting from the slit 27a. It is fitted movably.

The bearing 25 of the bracket 24 and the horizontal frame 26
Thus, the feed rod 29 is rotatably supported around the axis. A male screw is provided on the outer peripheral portion of the feed rod 29, and the moving block 28 is screwed into the male screw. At the front end of the feed rod 29 is a ring 3 for retaining
0 is attached, and a handle 31 is attached to the rear end.

A pressurizing device 32 is provided below the driven rotary unit 14. The pressurizing device 32 constitutes a pressurizing means for pressing the driven rotary unit 14 toward the drive rotary unit 5, and a hydraulic jack 33 as a fluid jack is installed on the base 2. A cam 35, which is rotatably supported up and down by a shaft 34, is provided at an upper front portion of the hydraulic jack 33. An engaging portion 35 which engages with the rear portion of the sliding body 16 of the driven rotating portion 14 is provided at a front portion of the cam 35.
a is formed. On the rear side of the cam 35, there is provided a receiving portion 36 which comes into contact with the piston rod of the hydraulic jack 33 and receives a pushing force of the jack.

The driven rotating unit 14 includes the driven rotating unit 1
A biasing device 37 is provided as biasing means for rotating the vertical direction 4. The biasing device 37 is provided with the driven rotation unit 1.
4 includes a nut member 38 fixed to the support cylinder 19 and a screw rod 39 screwed to the nut member 38. The lower end of the screw rod 39 is in contact with the sliding body 16, and a handle 40 is attached to the upper end. When the handle 40 is turned, the screw rod 39 rotates. However, since the lower end of the screw rod 39 is in contact with the upper surface of the sliding body 16, the screw rod 39 itself does not move up and down. The nut member 38 moves up and down together with the support cylinder 19. As a result, the driven rotation unit rotates up and down about the axis.

When using the tube expanding device, first, the drive rotating unit 5 and the driven rotating unit 14 are arranged such that the axes of the holding cylinders 7 and 20 are located on the same line. That is, the angle addition by the biasing device 37 is released.
Next, the metal tube W is inserted and held in the chuck sleeve 9 of the driving rotation unit 5 and the chuck sleeve 21 of the driven rotation unit.
At this time, the portion to be the expanded portion is aligned with the rear end of the chuck sleeve 9, the fixing member 10 is arranged at the position of the slit 9b, the chuck sleeve 9 is tightened with the screw 11, and the metal tube W is held.

Thereafter, the distance between the chuck sleeve 9 of the driving rotary unit 5 and the chuck sleeve 21 of the driven rotary unit 14 is set to a predetermined distance D by the feeder 23. This interval D
Is a distance at which a desired expansion can be obtained, and is determined by conducting a test in advance. To adjust the gap, the handle 31 is operated to move the moving block 28 so that the protrusion 28 a
After moving backward until it comes into contact with the rear end of a, the handle 31 is further turned to advance the feed rod 29 gradually. Since the distal end of the feed rod 29 is connected to the sliding body 16, the driven rotating unit 14 moves forward along the rail 15. After the predetermined interval D, the fixing member 22 is inserted into the slit 21b of the chuck sleeve of the drive rotating unit.
To hold the metal tube W.

Next, the metal tube W is pressurized in the axial direction by the pressurizing device 32, and the motor 12 as the driving means is operated. This pressurization is performed by operating the hydraulic jack 33 and rotating the cam 35 in the arrow X direction. When the motor 12 is operated, the metal tube W held by the chuck sleeves 9 and 21 rotates. That is, the metal tube W is rotating while being compressed in the axial direction. The rotation speed at this time may be about several times to several hundred times per minute. After this, the biasing device 3
7, the metal tube W is bent. The bending angle at this time is 3
It may be about 7 degrees.

As an example, when an expanded portion having an outer diameter of 27 mm and a width of 7 mm is formed in the middle of a carbon steel pipe for machine structure having an outer diameter of 22.2 mm and a wall thickness of 1.6 mm, the rotation speed is increased. The tube can be expanded under the conditions of 4 rotations per minute, a bending angle of 6 degrees and a compression force of 1 to 2 tons.

The space between the chuck sleeves 9 and 21 is compressed by the above-described pressurization, rotation and bending, and the tube is expanded. With the progress of the expansion, the initial interval D is reduced, but the pressurization is continued during this interval. At this time, when the pressurized state is released, the metal tube W
Is repeated within the interval D, and the metal tube W is broken. When the desired expansion is performed, the biasing device 37 is returned to the original state while continuing rotation and pressurization, and the metal pipe W is linearized. At this time, pressurization is still continued. As a result, a straight metal tube W whose intermediate portion is expanded is obtained. Therefore, the rotation and pressurization are stopped, and the metal tube W is removed from the chuck sleeves 9 and 21.

The metal tube W is connected to the chuck sleeves 9 on both sides,
21 was initially loosely fitted, but the rotation, bending,
By compression, the vicinity of the expanded portion is tightly fitted into the chuck sleeves 9 and 21. Therefore, removal of the metal tube W is performed as follows. First, hydraulic jack 3
3 is slid backward to lower the cam 35 in the anti-X direction. Then, the fixing member 22 is loosened, the drive rotating unit 5 and the driven rotating unit 14 are separated from each other by the feed device 23, and the metal tube W is extracted from the chuck sleeve 21. The pin 41 is pulled out, the fixing of the frame 4 and the horizontal frame 26 is released, and the driven rotary unit 14 is slid backward to pull out the metal tube W. Thereafter, the fixing member 10 may be loosened, and the metal pipe W may be extracted from the drive rotating unit 5 side.

[0027]

As described above, according to the method and apparatus for expanding a metal pipe of the present invention, it is possible to obtain an expanded section without reducing the thickness of the metal pipe.

[Brief description of the drawings]

FIG. 1 is a side sectional view showing an example of a pipe expanding apparatus of the present invention.

FIG. 2 is a plan view thereof.

FIG. 3 is a side sectional view of a main part showing the operation.

FIG. 4 is a sectional side view of a main part showing a first step (expanded state of a metal pipe) of a pipe expanding process.

FIG. 5 is a sectional side view of a main part showing a second step (expanding, rotating, compressing and bending the metal pipe) of the pipe expanding process;

FIG. 6 is a third step of the pipe expanding process (a state where the second step is continued).
Main part side sectional view showing

FIG. 7 is a sectional side view of a main part showing a fourth step of pipe expansion processing (a state in which bending is returned while rotating and compressing the metal pipe).

FIG. 8 is a cross-sectional view of an expanded portion showing an expanded state.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Expanding apparatus 5 Drive rotation part 14 Follower rotation part 23 Feeding device 32 Pressurizing device 37 Deflection device W Metal tube

Claims (2)

[Claims] At least one of the rotary holders is gripped by holding a linear metal tube at an appropriate distance D with a pair of rotary holders facing each other and rotating the metal tube around an axis. Is moved in a direction approaching the other, and one of the two rotation holders is gradually displaced in a direction intersecting the axis of the other rotation holder, so that a compressive stress always acts inside and outside the bending. After applying compressive and bending forces to the rotating metal tube under the conditions and causing plastic deformation in the expanding direction of the metal tube between the two rotating supports, compressive stress acts on the inside and outside of the bending. The method of expanding a metal pipe according to claim 1, wherein the bias is gradually restored while maintaining the condition, thereby forming an expanded part at an intermediate portion of the metal pipe. 2. A pair of rotatable holders which are opposed to each other and are rotatable so that at least one of them intersects the other axis, and at least one of the rotatable holders approaches and separates from the other rotatable holder. A metal provided with a pressurizing or feeding means, a driving means for rotationally driving at least one of the rotation holding bodies, and a biasing means for rotating at least one of the rotation holding bodies so as to intersect the other axis; Pipe expansion equipment.