JP2003225725A - Method and device for working tube - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To secure the excellent accuracy of dimensions and shapes and surface roughness even when an inexpensive welded tube is used and efficient parallel swaging is utilized. <P>SOLUTION: After a mandrel 23 is inserted into a tube stock 20 composed of an electric welded tube, the parallel swaging is performed by moving a cylindrical die 24 and the end part of the tube stock 20 is brought into close contact with the parallel forming part 27 of the mandrel 23. After completing the parallel swaging, the die 24 is drawn out of the tube stock 20, and a pressing die 33 is made to approach the tube stock 20 from the outside in the radial direction with the mandrel 23 left in the tube stock 20 and crushes the weld bead part of the tube stock 20 in cooperation with the mandrel 23. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a working method for working a pipe into a predetermined size by plastic working and a working apparatus suitable for carrying out the method.

[0002]

2. Description of the Related Art For example, as a hydraulic shock absorber using a pipe, the hydraulic shock absorber has an inner cylinder 2 in which a piston 1 is slidably mounted as shown in FIGS. The other end of a rod (piston rod) 4, which is housed in the bottom outer cylinder 3 and has one end connected to the piston 1, has a rod guide 5 that is commonly fitted to the open ends of the inner cylinder 2 and the outer cylinder 3. The oil seal 6 fitted to the open end of the outer cylinder 3 is extended to the outside, and the oil liquid sealed in the inner cylinder 2 is supplied to the piston valve 7 of the piston 1 and the inner bottom of the outer cylinder 3. The base valve 8 provided at the position of the piston rod 4 is circulated to generate a damping force in the extension stroke and the contraction stroke, and the oil liquid entering and leaving the piston rod 4 is gas and oil liquid between the inner cylinder 2 and the outer cylinder 3. There is a structure in which compensation is performed by the reservoir 9 in which In such a hydraulic shock absorber, the rod guide 5 and the oil seal 6 are press-fitted into the opening end of the outer cylinder 3 and fixed at a predetermined position, and the opening end of the outer cylinder 3 is curled inward ( By bending), the rod guide 5 and the oil seal 6 are prevented from coming off. Further, a cap 10 for receiving a bump rubber (not shown) is normally attached to the end of the outer cylinder 3 in a state of being press-fitted and fixed to the outer peripheral side thereof,
A certain number (for example, 3) on the inner bottom side of the cap 10.
The cap 10 is positioned by the provided protrusion 10a (FIG. 7) contacting the open end of the outer cylinder 3. Reference numeral 11 is an eye that serves as a mounting portion on the axle side, 12 is a mounting member that serves as a mounting portion on the vehicle body side, and 13 is a spring receiver that receives a coil spring.

[0003]

By the way, as described above, the opening end of the outer cylinder 3 constituting the hydraulic shock absorber has the fitting portion for the rod guide 5 on the inner diameter side and the cap 10 on the outer diameter side. Since each is used as a press-fitting part,
High precision is required not only for the inner diameter and outer diameter, but also for concentricity and roundness. Further, since the inner surface of the open end of the outer cylinder 3 is also used as the fitting portion of the oil seal 6 as described above, it has an excellent surface roughness so as not to scratch the oil seal 6 when it is charged. It was necessary to secure the degree. Therefore, conventionally, electric welded pipes such as electric resistance welded pipes have been used as raw pipes,
By machining (turning) the end portion, desired dimensional accuracy and surface roughness are ensured. However, according to the conventional method of machining the end portion by machining, there is a problem that precision machining is required, and thus machining itself requires a lot of man-hours and time, and an increase in machining cost cannot be avoided. It was In addition, chips and burrs generated by machining may adhere to the inner surface, and these may enter the hydraulic shock absorber as foreign matter (contamination). Incidentally, it has been partially considered to squeeze the end portion of the raw pipe by rotary aging and omit the machining, but in this case, since it is necessary to use an expensive seamless pipe as the raw pipe, Increasing the cost burden is unavoidable, and moreover, productivity is not so high because the tact time is long. Of course, if parallel swaging is performed using an electric welded pipe as a raw pipe, the problems of cost and productivity can be solved, but in this case, the weld bead part (weld part) existing in the electric welded pipe remains the same. Since it remains, finishing work by turning is finally required, and the special advantage of parallel swaging is lost.

The present invention has been made in view of the above problems, and its object is to obtain an excellent size and shape even if an inexpensive welded pipe is used and efficient parallel swaging is used. We provide a processing method for pipes that can ensure accuracy and surface roughness, and thus contribute greatly to cost reduction and productivity improvement, and also provide a suitable processing device for implementing this processing method. To do.

[0005]

In order to solve the above-mentioned problems, the method of the present invention is to insert a mandrel into a raw pipe made of a welded pipe and perform parallel swaging with a cylindrical die to form the raw mandrel. Then, the die is pulled out from the blank pipe, the mandrel is left inside the blank pipe, and the pressing die is brought closer to the blank pipe from the outer radial direction, and the welded portion of the blank pipe cooperates with the mandrel. It is characterized by working and crushing. In the pipe processing method performed in this way,
By squeezing the blank tube by parallel swaging and bringing its inner surface into close contact with the mandrel, excellent dimensional accuracy and surface roughness can be secured. In addition, since the welding portion existing in the welded pipe is finally crushed by the cooperation of the pressing die and the mandrel, troublesome finishing work by turning is unnecessary.
In the method of the present invention, it is desirable to perform parallel swaging by a die after inserting the mandrel into the shell. By thus inserting the mandrel into the tube first, the tube and the mandrel are prevented from rubbing against each other during the parallel swaging process, and the inner surface of the tube is not scratched. In this case, a tapered surface may be formed on the inner edge of the tip of the shell by the cooperation of the mandrel and the die.
Further, in the method of the present invention, an inner peripheral portion of the die may be provided with a relief portion having a slightly enlarged inner diameter, and the relief portion may be used as an oil reservoir for lubricating oil.

In order to solve the above problems, a pipe processing apparatus according to the present invention is a clamp for supporting a blank pipe, a mandrel insertable into the blank pipe supported by the clamp, and a blank supported by the clamp. It is characterized in that a swaging machine equipped with a die that moves in parallel along the pipe is provided with a pressing die that moves toward and away from the raw pipe from the outside in the radial direction.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings. 1 to 3 show, in order, a method of processing a pipe end as an embodiment of the present invention. In the present embodiment, the end portion of the outer cylinder 3 of the hydraulic shock absorber shown in FIGS. 6 and 7 is to be finished into a predetermined size and shape by plastic working.
As an example, an electric resistance welded pipe (electric resistance welded pipe) is used.
As is well known, the electric resistance welded pipe is formed by continuously forming a band steel into a pipe shape by a forming roll and press-welding the joint portion while resistance heating, as shown in FIG. The weld bead portion 21 is formed. However, in the production of the electric resistance welded pipe, the bead cutting is usually performed in the line, so that the weld bead portion 21 is smooth on the outer diameter side of the raw pipe 20 as shown in FIG. In this case, the welding bead 21 left on the inner diameter side of the raw pipe 20 exists as a convex bead 20a or a concave bead 20b as shown in FIG. In addition, as shown in FIG. 1, the bulging portion 2 is formed in the middle of the raw pipe 20 by bulging in advance.
2 is molded, the bulging portion 22 is used as a locking portion for mounting the spring receiver 13 (FIG. 6).

The present embodiment is characterized in that the end portion of the raw pipe 20 is subjected to parallel swaging, and therefore, the mandrel 23 which can be inserted into the raw pipe 20 and the mandrel 23 can be fitted. A cylindrical die 24 is prepared.
As shown in FIG. 4, the mandrel 23 includes a taper forming portion 26 having a small width which continues to the main body portion 23a of the mandrel 23 via a step surface 25, and a parallel forming portion 27 which follows the taper forming portion 26. The parallel molding portion 27 is provided with a relief portion 28 having a diameter slightly smaller than that of the parallel molding portion 27. The parallel molding portion 27 has a size and shape that matches the inner surface 3 a (FIG. 7) of the end of the outer cylinder 3 into which the rod guide 5 and the oil seal 6 are fitted, and the taper molding portion 2
Reference numeral 6 has a size and shape matching the tapered surface 3c (FIG. 7) required for the inner edge of the open end of the outer cylinder 3. on the other hand,
The die 24 has a cylindrical inner surface 29 which is aligned with the outer surface 3b (FIG. 7) of the outer cylinder 3 into which the cap 10 is press fitted.
Therefore, a gap S, which is approximately equal to the wall thickness of the raw pipe 20, is formed between the inner surface 29 of the die 24 and the parallel molding portion 27 of the mandrel 23, and the inner surface 29 of the die 24 and the mandrel 23 are formed. Between the escape portion 28 of 23,
A gap S ′ larger than the wall thickness of the raw pipe 20 is formed (FIG. 4). A taper introducing portion 30 for introducing the raw pipe 20 into the die 24 is provided at the opening end of the die 24.
A concave escape portion 31 having a diameter larger than that of the inner surface 29 of the cylinder is formed in a portion on the inner side of the opening end.

In carrying out the present invention, as shown in FIG. 1, a cushion cylinder in which the element pipe 20 is provided in clamps 32, 32 of a swage forming machine (parallel swage forming machine) and the mandrel 23 is provided in the swage forming machine. (Not shown)
The die 24 is attached to a movable part (not shown) of the swaging machine.
Have each support. Thus, the swaging machine is provided with a pressing die 33 that can approach and separate from the raw pipe 20 supported by the clamp 32 from the outside in the radial direction. The pressing die 33 has the mandrel 2 after the swaging.
And the welding bead portion 21 (FIG. 5) as the welding portion existing in the raw pipe 20 in cooperation with the metal pipe 3,
It is supported by a cylinder (not shown). The end surface of the pressing die 33 may have a flat shape or a curved shape that follows the outer peripheral shape of the rough tube 20 after swaging which will be described later.

The method for processing the end portion of the pipe according to the present invention will be described below in detail with reference to FIGS. When processing the end of the pipe, clamp 3 of the swaging machine as shown in FIG.
2 supports the raw pipe 20. At this time, the rotating mechanism (not shown) attached to the swaging machine supports the raw pipe 20, and prior to the support by the clamp 32, the servo motor of the rotating mechanism is controlled to weld the weld bead of the raw pipe 20. Part 21
Is accurately directed in the pressing direction by the pressing die 33. The rotation mechanism is controlled by, for example, detecting the position of the welding bead 21 with a reflective laser sensor, performing rough positioning once based on this detection signal, and then performing pattern matching by image processing to perform accurate positioning. Can be adopted.

After the preparation is completed, the mandrel 23 and the die 24 are integrally advanced as shown in the upper half of FIG. At this time, the die 24 has the taper introduction portion 30 at the tip thereof.
The forward movement of the mandrel 23 is temporarily stopped at the position where the tip of the raw tube 20 comes into contact with the mandrel 23. Insert it into the tube 20 and fix it in place. And
After fixing the position of the mandrel 23, the die 24 is slightly advanced. Then, the tip portion of the raw pipe 20 is squeezed along the taper introduction portion 30 of the die 24, and the inner edge of the tip portion is pressed by the taper forming portion 26 of the mandrel 23, whereby the tip end portion of the raw pipe 20 is pressed. Is formed with a taper surface corresponding to the taper surface 3c of the outer cylinder 3 (see FIG. 3).

After that, the position fixing of the mandrel 23 is released, and the cushion pressure of the cushion cylinder is applied to this, and the die 24 is advanced as shown in the upper half of FIG. By the advance of the die 24, the end portion of the raw pipe 20 is gradually narrowed, so-called parallel swaging is progressed,
The mandrel 23 retracts little by little according to the elongation of the shell 20 due to the progress of the parallel swaging. At this time, the tip end side of the tube 20 following the tapered surface 3c is pressed by the die 24 against the parallel forming portion 27 of the mandrel 23, and the inner surface thereof comes into close contact with the parallel forming portion 27. As a result, the inner diameter of the outer tube 3 at which the rod guide 5 and the oil seal 6 are fitted to the tip end of the raw tube 20 and the outer surface 3b of the outer tube 3 at which the cap 10 is press-fitted are formed. The required outer diameter dimension is secured, and the required concentricity and roundness are secured.

On the other hand, the mandrel 23 has an escape portion 28 having a slightly smaller diameter on the front end side than the parallel molding portion 27, so that the inner surface of the raw pipe 20 does not adhere to the mandrel 23 at this portion, and is drawn by the die 24. Only progresses. Then, since the concave relief portion 31 is provided on the cylindrical inner surface 29 of the die 24, the length of the molding portion (bearing portion) of the die 24, which is involved in the drawing of the raw tube 20, is substantially shortened. As a result, the processing pressure required for drawing is reduced, and the occurrence of galling is suppressed. In the present embodiment, in particular, for example, the concave relief portion 31 of the die 24 may be forcibly pressurized to supply oil, and lubricating oil may be stored in advance.
In this case, the working pressure is further reduced, and the galling is surely prevented.

In this way, the parallel swaging is completed, and as a result of this completion, as shown in the lower half of FIG. 2, only the die 24 is retracted while leaving the mandrel 23 in the tube 20. Then, at the same time when the die 24 is pulled out from the raw pipe 20, the pressing die 33 is brought closer to the raw pipe 20 from the outside in the radial direction as shown in the upper half of FIG. Then, the welding bead portion 21 existing in the raw pipe 20 is replaced by the pressing die 3
It is pressed against the parallel forming part 27 of the mandrel 23 by 3. Thereby, the weld bead portion 21 (convex bead 21
a, the concave bead 21b) is crushed, and as shown in FIG. 5, the inner surface of the blank 20 is finished smoothly. After that,
As shown in the lower half of FIG. 3, the mandrel 23 is retracted to withdraw it from the raw pipe 20, and the pushing die 33 is retracted to the original standby position, whereby the series of pipe end processing is completed. In this way, the outer cylinder of the hydraulic shock absorber (FIGS. 6 and 7)
3 is completed, but since the opening end of the completed outer cylinder 3 is finished to have a desired size and shape and the inner surface has a desired roughness, the rod guide 5 and the oil for the opening end are formed. The seal 6 can be smoothly fitted and assembled, and the cap 10 can be smoothly press-fitted. Further, since the tapered surface 3c is formed on the inner edge of the opening end, chamfering for smoothing the charging and assembling of the oil seal 6 is not necessary.

In the present invention, as the base pipe 20, other electric welded pipes such as TIG welded pipe, MIG welded pipe, plasma welded pipe and the like can be used instead of the electric resistance welded pipe.

[0016]

As described above in detail, according to the pipe processing method and the pipe processing apparatus of the present invention, excellent dimensions can be obtained even if an inexpensive welded pipe is used and efficient parallel swaging is used. Shape accuracy and surface roughness can be ensured, and cost reduction and productivity improvement can be achieved. Further, since there is no danger of foreign matter mixing as in the case of machining, it is suitable for machining a cylinder of hydraulic equipment such as a hydraulic shock absorber and a cylinder device. Further, in the method of the present invention, after inserting the mandrel into the tube, when performing parallel swaging by a die, during the parallel swaging, the tube and the mandrel do not rub against each other. The inner surface is not scratched and the surface roughness is further improved. In this case, when a tapered surface is formed on the inner edge of the tip of the raw tube by cooperation of the mandrel and the die, the subsequent chamfering process can be omitted. Furthermore, in the method of the present invention, when a relief portion whose inner diameter is slightly enlarged is provided on the inner periphery of the die and the relief portion is used as an oil reservoir of lubricating oil, it greatly contributes to reduction of molding pressure and prevention of galling. Becomes

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a starting step of a pipe processing method according to the present invention.

FIG. 2 is a cross-sectional view showing an intermediate step of the present processing method.

FIG. 3 is a cross-sectional view showing a final step of this processing method.

FIG. 4 is a sectional view showing a structure of a mandrel and a die used in the present invention.

FIG. 5 is a schematic view showing a state before and after processing of a weld bead portion.

FIG. 6 is a cross-sectional view showing the overall structure of a hydraulic shock absorber equipped with an outer cylinder which is a processing target of the present invention.

7 is a cross-sectional view showing a main structure of the hydraulic shock absorber shown in FIG.

[Explanation of symbols]

3 Outer cylinder of hydraulic shock absorber 5 Rod guide 6 oil seal 20 Elementary tube 21 Weld bead 23 Mandrel 24 dies 26 Mandrel taper forming part 27 Parallel forming part of mandrel 31 Die escape 33 Press die

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Claims (5)

[Claims] 1. A mandrel is inserted into a base pipe made of a welded pipe, and parallel swaging is performed by a cylindrical die to bring the base pipe into close contact with the mandrel, and then the die is pulled out from the base pipe to obtain the mandrel. Left in the tube,
A method for processing a pipe, characterized in that a pressing die is brought closer to the base pipe from an outer radial direction, and a welded portion of the base pipe is crushed in cooperation with the mandrel. 2. The parallel swaging process is performed by a die after inserting the mandrel into the blank tube.
The method of processing a pipe described in. 3. The method for processing a pipe according to claim 2, wherein a tapered surface is formed on the inner edge of the tip of the raw pipe by cooperation of a mandrel and a die. 4. The die according to claim 1, wherein the inner periphery of the die is provided with a relief portion whose inner diameter is slightly enlarged, and the relief portion is used as an oil reservoir for lubricating oil. How to process pipes. 5. A parallel swaging process comprising: a clamp supporting a blank pipe; a mandrel insertable into the blank pipe supported by the clamp; and a die that translates along the blank pipe supported by the clamp. A machine for processing a pipe, wherein the machine is provided with a pressing die that moves toward and away from the outer pipe in the radial direction.