JP4573090B2 - Pipe processing method and parallel swage processing apparatus - Google Patents

Description

  The present invention relates to a processing method for finishing an end portion of a pipe into a predetermined dimensional shape by plastic processing and a parallel swage processing apparatus suitable for carrying out the processing method.

  For example, as shown in FIG. 6, in a double cylinder type hydraulic shock absorber, an inner cylinder 1 in which a piston (not shown) is slidably housed is accommodated in a bottomed outer cylinder 2, and one end is connected to the piston. The other end of the formed rod (piston rod) 3 is extended to the outside through a rod guide 4 and an oil seal 5 that are fitted to the open ends of the inner cylinder 1 and the outer cylinder 2 in common. The oil liquid that enters and exits is compensated by a reservoir 6 filled with gas and oil liquid between the inner cylinder 1 and the outer cylinder 2.

  In such a hydraulic shock absorber, the rod guide 4 and the oil seal 5 are press-fitted into the end portion of the outer cylinder 2 and are fixed in position by a bent piece 2a obtained by bending the opening end portion of the outer cylinder 2 inward. Yes. Further, a cap 7 for receiving a bump rubber (not shown) is usually attached to the end of the outer cylinder 2 in a state of being press-fitted and fixed to the outer peripheral side thereof. That is, the opening end of the outer cylinder 2 is provided as an inner peripheral surface 8A as a fitting portion of the rod guide 4 and an outer peripheral surface 8B as a press-fitting portion of the cap 7, respectively. High accuracy is required for concentricity, roundness, etc., as well as the inner and outer diameters. Further, the inner periphery 8A of the opening end portion of the outer cylinder 2 needs to ensure excellent surface roughness so as not to damage the oil seal 5 when it is press-fitted.

  By the way, conventionally, in the manufacture of the outer cylinder 2, generally, an electric welded pipe such as an electric-welded pipe is used as a base pipe, and the end portion is machined (turned) to obtain desired dimensional shape accuracy and surface roughness. I was trying to secure it. However, according to the conventional general method of performing end machining by machining, since precision machining is required, the machining itself takes a lot of man-hours and time, and an increase in machining cost is inevitable. there were. 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).

  Accordingly, various studies have been made to finish the end portion of the outer cylinder 2 by plastic working. In Patent Document 1, a mandrel is inserted into a raw pipe, and parallel swage processing is performed with a die to thereby change the end of the raw pipe. A processing method for contacting the mandrel is described. According to such a processing method, the end of the tube is narrowed and reduced in surface (reduced thickness) between the mandrel and the die by parallel swaging, so that excellent dimensional shape accuracy and surface roughness are achieved. It will be possible to secure.

JP 2003-225725 A

However, according to the processing method described in Patent Document 1, since it is necessary to ensure a predetermined area reduction rate by one parallel swaging, for example, a thick wall like a hydraulic shock absorber for a strut suspension is used. If an attempt is made to secure a desired reduction in area for the outer cylinder, the forming force required for parallel swaging will exceed the buckling load of the blank tube, resulting in a situation in which molding is impossible. It was limited.
In order to deal with this problem, it is only necessary to perform parallel swaging multiple times to gradually increase the surface reduction rate, but in this case, the parallel swage is changed by changing the process or changing the machining tool. Since processing must be performed, a decrease in productivity and an increase in manufacturing cost are inevitable.

  The present invention has been made in view of the above-mentioned problems, and the problem is that a pipe capable of greatly increasing the area reduction rate by parallel swaging without sacrificing productivity and manufacturing cost so much. And a parallel swage processing apparatus for efficiently performing this processing method.

To solve the above problems, a processing method of a tube according to the present invention, insert the mandrel into mother tube which is axially movably supported by the clamp, the ends of the raw tube by performing a parallel swaging by the die the method for processing a tube to be in close contact with the mandrel, the parallel swaging the first first stage parallel swage squeezing the blank tube by moving the die is stationary the mother tube by the clamp A second inner diameter smaller than the inner diameter of the first die, disposed coaxially with the first die and approaching the first die from the opposite side of the clamp; wherein the by the die and a second-stage parallel swaging step of squeezing the blank tube. In the tube processing method performed in this way, the parallel swaging is performed in two stages by the first die and the second die. Therefore, a forming force that does not cause buckling of the raw tube is selected, and each stage is parallel. Even if swage processing is performed, a sufficiently high surface area reduction rate can be obtained, and in addition, process transfer and step change are not required.

In this machining method, after the first stage parallel swaging process is performed by pushing the blank tube into the first fixed die, the second stage is moved closer to the first die and the second stage parallel swaging process is performed. It is desirable to implement.
Also, a welded pipe is used as the base pipe, and after the second stage parallel swaging step, the base pipe is pulled out from the first and second dies integrally with the mandrel, and the pressing die is approached from the outside in the radial direction. The welded portion of the raw pipe may be crushed in cooperation with the mandrel.

To solve the above problems, parallel swaging apparatus according to the present invention, a clamp for moving the blank tube to the supporting axial, and can be inserted mandrel to the blank pipe, which is supported by the clamp, the base pipe In a parallel swaging apparatus provided with a die that squeezes the end and closely contacts the mandrel, the die is composed of a first die and a second die having an inner diameter smaller than the inner diameter of the first die. The first die is disposed in a fixed position, and the second die is moved closer to and away from the first die from the side opposite to the clamp, thereby fixing the first die. Between the die and the clamp, a push die that approaches and separates from the radial outside direction with respect to the raw tube on the mandrel is provided .

  According to the method for processing a pipe according to the present invention, the area reduction rate by parallel swaging can be sufficiently increased without causing buckling, so the applicable range is expanded. Further, since the parallel swaging is continuously performed in two stages by the first die and the second die, there is no need for process transfer or change of stage, which is advantageous in terms of productivity and manufacturing cost.

Further, in this processing method, after the first stage parallel swaging process is performed by pushing the blank tube into the first fixed die, the second stage is moved closer to the first die and the second stage parallel swaging process is performed. When carrying out the above, two-stage parallel swaging can be performed smoothly and stably.
Also, if a welded pipe is used as the base pipe and the welded part of the base pipe is crushed by the cooperation of the pressing die and mandrel after the second stage parallel swaging process, the welded part is post-processed by separate machining There is no need to do it.

According to the parallel swage processing apparatus of the present invention, the two-stage parallel swage processing can be efficiently performed by alternately moving the clamp and the second die relative to the first fixed die.
Moreover, in this manufacturing apparatus, when a pressing die that approaches and separates from the radial outside direction with respect to the raw pipe on the mandrel is disposed, even if a welded pipe is used as the raw pipe, the welded portion is flattened. And the utility value is improved.

Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings.
1 to 3 show a parallel swage machining apparatus for carrying out a pipe machining method according to the present invention. In the present embodiment, the end portion of the outer cylinder 2 of the hydraulic shock absorber shown in FIG. 6 is to be finished into a predetermined dimensional shape by plastic working. Here, an electric resistance welded pipe ( ERW pipe is used. The outer peripheral surface of this electric resistance welded tube is smooth due to the bead cut at the time of manufacture, but a weld bead (welded portion) exists as a convex bead or a concave bead on the inner peripheral surface. The apparatus includes a clamp 11 that supports the element tube 10, a mandrel 12 that can be inserted into the element tube 10 supported by the clamp 11, and two ring-shaped dies 13 and 14 that can be fitted to the mandrel 12. , A pressing die 15 and a receiving die 16 are provided that approach and separate from the base tube 10 on the mandrel 12 in the radial direction.

  The mandrel 12 is supported by a drive means (not shown) via a cushion cylinder. At the start of processing, the tip of the mandrel 12 is inserted through two ring-shaped dies 13 and 14 as shown in FIG. It is designed to be positioned on the side. As shown in FIG. 2, the mandrel 12 has a small taper forming portion 22 that continues to the main body portion 20 via a step 21 on the tip side thereof, a parallel forming portion 23 that follows the taper forming portion 22, and The parallel molded part 23 is provided with a relief part 24 having a slightly smaller diameter than the parallel molded part 23. The parallel molded portion 23 has a size and shape that matches the inner peripheral surface 8A (FIG. 6) of the outer cylinder 2 to which the rod guide 4 and the oil seal 5 are fitted, and the tapered molded portion 22 It has a size and shape that matches the tapered surface 8C (FIG. 6) required for the inner edge of the bent piece 2a of the tube 2.

  The ring-shaped dies 13 and 14 are arranged coaxially in series in the axial direction of the mandrel 12, and are fastened and fixed to the die holders 30 and 31 using bolts 32 and 33, respectively. Of the die holders 30 and 31, the die holder 30 that holds one die 13 on the clamp 11 side is disposed in a fixed manner, and the die holder 31 that holds the other die 14 on the side far from the clamp 11 is the fixed die holder. 30 is arranged so as to be able to approach and separate. That is, one die 13 is configured as a fixed die, and the other die 14 is configured as a movable die. The movable die 14 is moved forward and backward by a driving unit (not shown), and at the start of processing, It is positioned at the retracted end with a fixed distance from the fixed die 13 (FIG. 1).

Here, as well shown in FIG. 3, each ring-shaped die 13, 14 includes a bearing portion 36 having a middle height on the inner diameter side, and gradually expands the inner diameter toward the end face on both sides of the bearing portion 36. The guide part 37 is provided. The bearing portion 36 is a portion that directly participates in parallel swaging, which will be described later, and its width W is set to be quite narrow (about 0.5 to 1.0 mm). Further, the inner diameter (caliber) D of the bearing portion 36 is set to a different value between the fixed die (first die) 13 and the movable die (second die) 14, and the inner diameter of the movable die 14 is fixed die. (as an example, about 0.4mm in diameter) slightly greater than the inner diameter of 13 is smaller. The inner diameter of the fixed die 13 is a size obtained by adding the final thickness t (2t) of the opening end of the outer cylinder 2 to the diameter of the parallel molding portion 23 (FIG. 2) of the mandrel 12. Yes. The taper angle θ of the guide portion 37 is set to about 20 degrees as an example.

  In the present embodiment, the clamp 11 moves forward and backward with respect to the fixed die 13 by a driving means (not shown). At the start of machining, the clamp 11 is positioned at a retracted end that is largely separated from the fixed die 13, and the base tube 10 is supported (set) by the clamp 11 positioned at the retracted end. On the other hand, the push die 15 and the cradle 16 are disposed so as to be relatively movable in the radial direction, and at the start of machining, the push die 15 and the cradle 16 are positioned at a retreat end that retreats from the moving range of the clamp 11 by a driving means (not shown). . A bead detection mechanism (for example, an image processing apparatus having a camera) and a rotation mechanism (not shown) for indexing the weld bead of the raw tube 10 with respect to the pressing die 15 are disposed behind the clamp 11. Alternatively, the tube 10 is accurately positioned in the rotation direction by operating the rotating mechanism prior to the support of the tube 10 by the clamp 11.

Hereinafter, the processing method performed using the parallel swage processing apparatus will be described with reference to FIG.
In carrying out this processing method, as shown in FIG. 1, after setting the raw tube 10 to the clamp 11, the clamp 11 is advanced. At this time, the raw tube 10 is positioned in the rotational direction using the rotating mechanism (not shown) or manually so that the weld bead faces the push die 33. As the clamp 11 advances, the tip of the element tube 10 passes through the fixed die holder 30 and enters the fixed die 13. First, the tip of the element tube 10 contacts the guide portion 37 of the fixed die 13.

  When the clamp 11 further advances, as shown in FIG. 4 (1), the distal end portion of the raw tube 10 is squeezed along the guide portion 32 of the fixed die 13, and the distal end abuts against the step 21 of the mandrel 12. Touch. As a result, the propulsive force of the clamp 11 is applied to the mandrel 12, and the mandrel 12 retracts integrally with the base tube 10 against the cushion pressure (back pressure) of the cushion cylinder. Then, the tip end portion of the raw tube 10 is narrowed by the bearing portion 36 of the fixed die (first die) 13 and the first stage parallel swaging process proceeds. Finally, as shown in FIG. 4 (2), the tip of the raw tube 10 reaches the guide part 37 of the movable die (second die) 14, and the advancement of the clamp 11 is stopped at this stage, The parallel swaging of the eye (process) is completed. In the first stage parallel swaging process, the tip of the blank tube 10 is first brought into close contact with the taper forming portion 22 (FIG. 3) of the mandrel 12, and the taper surface 8 </ b> C (FIG. 6) of the outer cylinder 2. A corresponding tapered surface is formed.

  Thereafter, as shown in FIG. 4 (3), the movable die 14 advances toward the fixed die 13 side. At this time, the clamp 11 is maintained at the stop position, so that the base tube 10 is also fixed in position, and the mandrel 12 is also fixed in position by the cushion pressure (back pressure) of the cushion cylinder. ing. Therefore, as described above, when the movable die 14 advances toward the fixed die 13, the tip of the raw tube 10 is further narrowed by the bearing portion 36 of the movable die 14, and the second stage parallel swaging process proceeds. The inner surface of the raw tube 10 is in close contact with the parallel molding portion 23 of the mandrel 12. The advancement of the movable die 14 is stopped when the bearing portion 36 exceeds the parallel forming portion 23 of the mandrel 12, and the second stage parallel swaging (process) is completed. As a result, the inner diameter required for the inner peripheral surface 8A of the outer cylinder 2 into which the rod guide 4 and the oil seal 5 are fitted and the outer cylinder 2 into which the cap 7 is press-fitted are inserted into the distal end portion of the raw tube 10. The outer diameter required for the outer peripheral surface 8B is secured, and the necessary concentricity and roundness are secured.

  When the second stage parallel swaging process is completed, the clamp 11 is moved backward, and the mandrel 12 is moved forward in conjunction with the backward movement. As shown in FIG. And come off the fixed die 13. Retraction of the clamp 11 is stopped when the portion corresponding to the inner peripheral surface 8A of the outer cylinder 2 moves to a position facing the pressing die 15, and the pressing die 15 and the receiving die 16 are moved by the retreating stop. As shown in 4 (4), the relative movement is made and the mandrel 12 is approached. Then, the weld bead existing in the base tube 10 is pressed against the parallel molding portion 23 of the mandrel 12 by the pressing die 33, whereby the weld bead (convex bead, concave bead) is crushed, The inner peripheral surface 8A of the tube 10 is finished smoothly. At this time, since the back portion of the mandrel 12 is backed up by the receiving die 16, the weld bead is reliably crushed. Thereafter, the push die 15 and the receiving die 16 are retracted to the original position, the clamp 11 and the mandrel 12 are retracted to the original position, and the mandrel 12 comes out of the outer cylinder 2 as a finished product.

  The outer cylinder 2 thus completed has its opening end finished to a desired size and shape and finished to a desired inner surface roughness, so that the rod guide 4 and the oil seal 5 are fitted to the opening end. The assembling can be performed smoothly and the cap 7 can be press-fitted smoothly. Moreover, since the tapered surface 8C is formed at the inner edge of the opening end, chamfering processing for smooth insertion and assembly of the oil seal 5 becomes unnecessary. In addition, since the parallel swaging is performed in two stages, a sufficiently high reduction in area can be obtained even if parallel swaging is performed at each stage by selecting a forming force that does not cause buckling of the raw tube 10. Thus, the present processing method can be stably applied to the processing of the outer cylinder of the hydraulic shock absorber for the strut suspension. In the present invention, as the raw tube 10, other electric welded pipes such as TIG welded pipes, MIG welded pipes, plasma welded pipes and the like can be used instead of the above-mentioned electric resistance welded pipes, and seamless pipes are used. Can do.

  Moreover, in the said embodiment, the state which fixed the position of the mandrel 12 with the cushion pressure (back pressure) of a cushion cylinder while stopping the clamp 11 which hold | maintains the raw | natural pipe | tube 10 after completion | finish of a 1st stage parallel swage process (process). However, the present invention has been shown to shift to the next second stage of parallel swage processing (process). However, the present invention is not limited to this, and the parallel swaging may be performed as follows. I do not care.

  That is, the mandrel 12 is fixed at a predetermined position by hydraulic locking or the like just before the end of the first stage parallel swaging (process), and then the clamp 11 holding the base tube 10 is slightly advanced and stopped at the predetermined position. By doing so, the first stage parallel swage processing (process) is completed. And it is made to shift to the next 2nd stage parallel swage process (process), maintaining the state. In this case, since the clamp 11 and the mandrel 12 that hold the raw tube 10 from above and below are fixed at predetermined positions, the dimension of the raw tube 10 to the axially extending side generated by performing parallel swaging is provided. The change can be suppressed to a certain range regardless of the raw tube, and the dimensional error (variation) in the axial direction of the outer cylinder 2 as a finished product can be suppressed. Note that the increased thickness due to the second stage parallel swaging (step) escapes to the small diameter relief portion 24 side of the mandrel 12.

  The raw tube 10 was made of STKM12B having an outer diameter of 50.8 mm and a wall thickness of 2.9 mm, and two-stage parallel swaging was performed by the parallel swaging apparatus shown in FIG. The molding apparatus uses SK3 heat-treated products (HRC 50 to 55) as the mandrel 12 and the dies 13 and 14, and the mandrel 12 has an outer diameter of the parallel molding portion 23 set to 44.2 mm, and a fixed die. For the (first die) 13 and the movable die (second die) 14, the inner diameter of each bearing portion 36 was variously changed so that various area reduction rates were obtained. Then, the cushion pressure (back pressure) applied to the mandrel 12 is set in a range of 20 to 40 kN, the above-described first-stage parallel swage process and the second-stage parallel swage process are performed, and the parallel swage process of each stage is performed. The molding force required for implementation was determined.

  FIG. 5 shows the molding force obtained as described above, organized by area reduction ratio. In the figure, the broken line represents the buckling load (about 150 kN) obtained in advance for the above-mentioned raw tube. From this, the first-stage parallel swaging process reduces the area reduction rate to about 13% and the second-stage parallel stage process. Then, the area reduction rate is less than the buckling load of the raw pipes to about 10%. In this case, in consideration of safety, it is desirable to suppress the molding pressure to about 80% or less (120 kN or less) of the buckling load. The area reduction ratio converted from the molding pressure satisfying this is about 10% in the first stage parallel swaging process and about 8% in the second stage parallel swaging process. In this case, the total area reduction ratio including the first and second parallel swaging steps is about 17%, which is sufficiently satisfactory even when applied to the processing of the outer cylinder of the hydraulic shock absorber for the strut type suspension. It can be said that the area reduction rate can be secured. When comparing the first-stage parallel swage process and the second-stage parallel swage process, the molding force of the second-stage parallel stage process is larger than the molding force of the first-stage parallel swage process for each area reduction. However, this is due to the effect of work hardening.

It is sectional drawing which shows the principal part structure of the parallel swage processing apparatus which concerns on this invention. It is sectional drawing which shows the structure of the mandrel used with this parallel swage processing apparatus. It is sectional drawing which shows the structure of the die | dye used with this parallel swage processing apparatus. It is sectional drawing which shows the processing method of the pipe | tube which concerns on this invention implemented using this parallel swage processing apparatus in order of a process. It is a graph which shows the relationship between the area reduction rate and molding force which were obtained in the Example of this invention. It is sectional drawing which shows the principal part structure of the hydraulic shock absorber equipped with the outer cylinder which is a process target of this invention.

Explanation of symbols

2 Outer cylinder of hydraulic shock absorber 10 Base tube 11 Clamp 12 Mandrel 13 Fixed die (first die)
14 Movable die (second die)
15 Pressing die 16 Receiving die 30, 31 Die holder

Claims (3)

A method of processing a tube, wherein a mandrel is inserted into an element tube supported so as to be movable in the axial direction by a clamp, and a parallel swaging process is performed by a die so that an end of the element tube is in close contact with the mandrel. The processing is arranged on the same axis as the first die, the first stage parallel swaging step of squeezing the raw tube by moving the raw tube to the first die fixed in position by the clamp, and the first die A second-stage parallel swaging step of narrowing the raw tube with a second die having an inner diameter smaller than the inner diameter of the first die, which is made to approach one die from the side opposite to the clamp. A method of processing a pipe, characterized by the above. A welded pipe is used as the base pipe, and after the second stage parallel swaging process, the base pipe is pulled out from the first and second dies integrally with the mandrel, and the pressing die is approached from the outside in the radial direction, the pressing die and the mandrel The method of processing a pipe according to claim 1, wherein the welded portion of the raw pipe is crushed by the cooperation. A clamp for moving the blank tube to the supporting axial, parallel with and inserted mandrel to the blank pipe, which is supported by the clamp, and a die for adhering the end portion the mandrel squeezing of the base pipe swage In the processing apparatus, the die is composed of a first die and a second die having an inner diameter smaller than the inner diameter of the first die, the first die is disposed in a fixed manner, and A second die is moved closer to and away from the first die than the side opposite to the clamp, and the raw tube on the mandrel is positioned between the first die and the clamp that are fixed in position. On the other hand, there is provided a processing apparatus for a tube, wherein a pressing die that is approached and separated from the radial outside direction is disposed .

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