JP4359821B2 - Pipe processing method and processing apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a processing method for processing a pipe into a predetermined dimensional shape by plastic processing, and a processing apparatus suitable for implementing the method.
[0002]
[Prior art]
For example, there is a hydraulic shock absorber using a pipe. As shown in FIGS. 8 and 9, the hydraulic shock absorber includes an inner cylinder 2 in which a piston 1 is slidably mounted and a bottomed outer cylinder 3. A rod guide 5 and an opening of the outer cylinder 3 which are fitted in the opening ends of the inner cylinder 2 and the outer cylinder 3 with the other end of the rod (piston rod) 4 which is housed in the piston 1 and connected at one end to the piston 1. A base valve provided at the inner bottom of the piston valve 7 provided on the piston 1 and the oil cylinder sealed in the inner cylinder 2 through the oil seal 6 fitted to the end and extended to the outside. 8 is a reservoir in which gas and oil liquid are enclosed between the inner cylinder 2 and the outer cylinder 3 for generating the damping force of the extension stroke and the contraction stroke through the circulation of the piston rod 4 There is a structure that compensates in 9.
[0003]
In such a hydraulic shock absorber, a rod guide 5 and an oil seal 6 are press-fitted into an opening end portion of the outer cylinder 3 and disposed at a predetermined position. The rod guide 5 and the oil seal 6 are secured by a bent piece 10 formed by bending the open end of the outer cylinder 3 over the entire circumference or by partially bending a plurality of locations in the circumferential direction inward (for example, , See Patent Document 1). Further, a cap 11 for receiving a bump rubber (not shown) is usually attached to the end of the outer cylinder 3 in a state where it is press-fitted and fixed to the outer peripheral side, and a predetermined number (on the inner bottom side of the cap 11 ( For example, the cap 11 is positioned by the projections 11a ( FIG. 9 ) provided in contact with the bent piece 10. Reference numeral 12 denotes an eye serving as a mounting portion on the axle side, 13 denotes a mounting member serving as a mounting portion on the vehicle body side, and 14 denotes a spring receiver that receives a coil spring.
[0004]
By the way, the opening end portion of the outer cylinder 3 constituting the hydraulic shock absorber is provided as the fitting portion of the rod guide 5 on the inner diameter side and the press-fitting portion of the cap 11 on the outer diameter side as described above. High precision is required for concentricity, roundness, etc. as well as for the inner and outer diameters. Further, since the inner surface of the opening end portion of the outer cylinder 3 is also used as a fitting portion of the oil seal 6 as described above, the surface roughness is excellent so as not to damage the oil seal 6 when it is inserted. It was necessary to secure the degree. Therefore, conventionally, an electric welded pipe such as an electric welded pipe is used as a raw pipe, and the end portion is machined (turned) to ensure desired dimensional shape accuracy and surface roughness.
In some cases, a predetermined dimension and shape are secured by narrowing the end portion of the electric welding pipe (element pipe) by swaging (rotary swaging) (for example, see Patent Document 2).
[0005]
[Patent Document 1]
JP-A-3-68650 [Patent Document 2]
Japanese Patent Laid-Open No. 7-265979 [0006]
[Problems to be solved by the invention]
However, according to the conventional method in which end machining is performed 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. 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).
In addition, according to the method of swaging the end portion of the electric welded pipe, the weld bead part (welded part) existing in the electric welded pipe remains as it is, so that it is finally necessary to finish by turning. It does not lead to a solution. In the invention described in Patent Document 2, a female thread is formed on the inner surface of the pipe end portion after swaging, and when post-processing is performed in this way, there is no problem even if there is a bead residue. Further, if a seamless pipe is used as the base pipe, the above-described finishing process is not necessary. However, in this case, an expensive seamless pipe is used, so an increase in cost burden is inevitable.
[0007]
The present invention has been made in view of the above-mentioned problems, and the problem is that even if an inexpensive welded pipe is used and efficient parallel swaging is used, excellent dimensional shape accuracy and surface are achieved. To provide a processing method of a pipe that can ensure the roughness and greatly contribute to the reduction of cost and the improvement of productivity, and to provide a processing device suitable for the implementation of this processing method. is there.
[0008]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the method of the present invention inserts a mandrel into a base pipe made of a welded pipe and performs parallel swaging with a die to bring the base pipe into close contact with the mandrel . At the tip part, a thin part used as a radially inward bending piece is formed by the cooperation of the mandrel and the die, and then the die is pulled out from the raw tube, and the mandrel is left in the raw tube. It is characterized in that a pressing die is brought close to the base pipe from the outside in the radial direction and the welded portion of the base pipe is crushed in cooperation with the mandrel.
In the tube processing method performed in this way, excellent dimensional shape accuracy and surface roughness can be ensured by constricting the raw tube by parallel swaging and bringing the inner surface into close contact with the mandrel. Moreover, since the welded portion existing in the welded pipe is finally crushed by the cooperation of the pressing die and the mandrel, troublesome finishing by turning becomes unnecessary. In addition, since the thin-walled portion used as a radially inwardly bent piece is formed at the distal end portion of the raw tube by the cooperation of the mandrel and the die, the bent piece can be easily bent later.
In the method of the present invention, it is desirable to perform parallel swaging with a die after inserting the mandrel into the blank tube. By previously inserting the mandrel into the blank tube in this way, the blank tube and the mandrel are not rubbed during parallel swaging, and the inner surface of the tube is not damaged. In this case, a tapered surface may be formed on the inner edge of the tip of the raw tube by the cooperation of the mandrel and the die .
Furthermore, in the method of the present invention, an escape portion whose inner diameter is slightly enlarged may be provided on the inner periphery of the cylindrical die, and the escape portion may be used as an oil reservoir for lubricating oil.
[0009]
In order to solve the above-described problems, a pipe processing apparatus according to the present invention includes a clamp that supports a raw pipe, a mandrel that can be inserted into the raw pipe supported by the clamp, and a raw pipe that is supported by the clamp. A parallel swaging machine provided with a die that moves in parallel with the die, and a pressing die that approaches and separates the raw pipe from a radially outward direction , and the tip of the raw pipe is attached to the mandrel with a prescribed pipe wall The present invention is characterized in that a molding surface for molding thinner than that is provided.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
1 to 3 show a pipe end processing method as an embodiment of the present invention step by step. In the present embodiment, the end of the outer cylinder 3 of the hydraulic shock absorber shown in FIGS. 8 and 9 is to be finished to a predetermined size and shape by plastic working. Use welded pipes. As is well known, an ERW tube is formed by continuously forming a steel strip into a tube shape by a forming roll, and press-contacting the mating portion with resistance heating. As shown in FIG. A weld bead portion 21 is formed. However, since the bead cut is usually performed in the line in the manufacture of the electric resistance welded tube, the weld bead portion 21 is smooth on the outer diameter side of the base tube 20 as shown in FIG. In this case, the weld bead 21 left on the inner diameter side of the raw tube 20 exists as a convex bead 21a or a concave bead 21b as shown in FIG. As shown in FIG. 1, a bulging portion 22 is formed in the middle of the raw tube 20 by prior bulging. The bulging portion 22 is attached with the spring receiver 14 (FIG. 8). It is used as a latching part.
[0011]
The present embodiment is characterized in that a parallel swaging process is applied to the end portion of the raw tube 20. For this reason, a mandrel 23 that can be inserted into the raw tube 20 and a cylindrical die that can be fitted into the mandrel 23. 24 are prepared. As shown well in FIG. 4, the mandrel 23 includes a narrow taper forming part 26 that continues to the main body part 23 a of the mandrel 23 via the step surface 25, a parallel forming part 27 that follows the taper forming part 26, and The parallel molding part 27 is provided with a relief part 28 having a slightly smaller diameter than the parallel molding part 27. The parallel molding portion 27 has a size and shape that matches the inner surface 3a (FIG. 9) of the outer cylinder 3 to which the rod guide 5 and the oil seal 6 are fitted. It has a size and shape that matches the tapered surface 3c (FIG. 7) required at the inner edge of the open end of the tube 3. On the other hand, the die 24 has a cylindrical inner surface 29 that is aligned with the outer surface 3b (FIG. 9) of the outer cylinder 3 into which the cap 10 is press-fitted. Therefore, a gap S is formed between the cylindrical inner surface 29 of the die 24 and the parallel molding portion 27 of the mandrel 23, which is almost equal to the wall thickness of the raw tube 20, and the cylindrical inner surface 29 of the die 24 and the mandrel. A gap S ′ larger than the thickness of the raw tube 20 is formed between the clearance portion 28 and the relief portion 28 (FIG. 4). A taper introducing portion 30 for introducing the raw tube 20 into the die 24 is provided at the opening end portion of the die 24, and a concave relief having a diameter larger than that of the cylindrical inner surface 29 is provided at a portion farther from the opening end of the die 24. A portion 31 is formed.
[0012]
In carrying out the present invention, as shown in FIG. 1, a cushion cylinder (not shown) in which the raw tube 20 is provided in clamps 32 and 32 of a swage forming machine (parallel swage forming machine) and the mandrel 23 is provided in the swage forming machine. ), The die 24 is supported by movable parts (not shown) of the swage molding machine. The swage molding machine is provided with a push die 33 that can approach and separate from the outer radial direction with respect to the raw tube 20 supported by the clamp 32. The pressing die 33 serves to crush the weld bead portion 21 (FIG. 5) as a welded portion existing in the raw pipe 20 in cooperation with the mandrel 23 after the swaging, and is a cylinder not shown. It is supported. Note that the end face of the pressing die 33 may be a flat shape or a curved shape along the outer peripheral shape of the rough tube 20 after swaging as described later.
[0013]
Hereinafter, a method for processing an end portion of a pipe according to the present invention will be described in detail with reference to FIGS.
When the end portion of the pipe is processed, the raw pipe 20 is supported by the clamp 32 of the swage machine as shown in FIG. At this time, the raw tube 20 is supported by a rotating mechanism (not shown) attached to the swage processing machine, and prior to the support by the clamp 32, the servo motor of the rotating mechanism is controlled to weld the bead 20 of the raw tube 20. The part 21 is oriented accurately in the pressing direction by the pressing die 33. The rotation mechanism is controlled by, for example, a method in which the position of the weld bead 21 is detected by, for example, a reflective laser sensor, and after rough positioning based on this detection signal, pattern matching is further performed by image processing to perform accurate positioning. Can be adopted.
[0014]
After completion of the preparation, the mandrel 23 and the die 24 are integrally advanced as shown in the upper half of FIG. At this time, the die 24 temporarily stops its advancement at a position where the tip of the raw tube 20 abuts against the taper introduction portion 30 at the tip, while the mandrel 23 has its tip as shown in the lower half of FIG. The tube is inserted into the tube 20 until the tip of the tube 20 contacts the stepped surface 25, and the position is fixed as it is. Then, after the position of the mandrel 23 is fixed, the die 24 is slightly advanced. Then, the distal end portion of the raw tube 20 is squeezed along the taper introducing portion 30 of the die 24, and the inner edge of the distal end portion is pressed by the taper forming portion 26 of the mandrel 23, whereby the distal end portion of the raw tube 20 is pressed. Is formed with a tapered surface corresponding to the tapered surface 3c of the outer cylinder 3 (see FIG. 3).
[0015]
Thereafter, the position fixing of the mandrel 23 is released, and the cushion pressure of the cushion cylinder is applied thereto, and the die 24 is advanced as shown in the upper half of FIG. As the die 24 advances, the end portion of the raw tube 20 is gradually narrowed, so-called parallel swaging is advanced, and the mandrel 23 is slightly retracted according to the elongation of the raw tube 20 due to the progress of the parallel swaging. At this time, the distal end side of the raw tube 20 following the tapered surface 3 c is pressed against the parallel molding portion 27 of the mandrel 23 by the die 24, and the inner surface thereof is in close contact with the parallel molding portion 27. As a result, the inner diameter dimension required as the inner surface 3a of the outer cylinder 3 to which the rod guide 5 and the oil seal 6 are fitted, and the outer surface 3b of the outer cylinder 3 into which the cap 10 is press-fitted, are arranged at the distal end portion of the raw tube 20. Necessary outer diameter dimensions are secured, and necessary concentricity and roundness are secured.
[0016]
On the other hand, since the mandrel 23 has a slightly smaller diameter relief portion 28 on the tip side than the parallel molding portion 27, the inner surface of the raw tube 20 does not adhere to the mandrel 23 in this portion, and only the drawing by the die 24 proceeds. To do. Accordingly, since the concave relief portion 31 is provided in the cylindrical inner surface 29 of the die 24, the length of the molding portion (bearing portion) of the die 24 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 also suppressed. In the present embodiment, in particular, the concave relief portion 31 of the die 24 may be forcibly supplied with oil, for example, so that lubricating oil may be accumulated in advance. In this case, the processing pressure is Further reduction and galling are reliably prevented.
In some cases, the length of the weld bead portion in the circumferential direction varies depending on the manufacturing process. In order to cope with the variation in the weld bead portion of the raw tube, the rotation mechanism of the swage processing machine causes the raw tube to be rotated at a predetermined angle (for example, 10 degrees) in the forward and reverse directions with the bead portion as the center. It is desirable to press the bead portion of the raw tube with the pressing die 33. Thus, if the bead portion of the raw tube is pressed by the pressing die 33 at every predetermined angle, the inner surface of the raw tube 20 can be finished smoothly regardless of variations in the weld bead portion of the raw tube.
[0017]
In this way, the parallel swaging process is completed, and as a result, as shown in the lower half of FIG. 2, only the die 24 is retracted while the mandrel 23 remains in the raw tube 20. And simultaneously with drawing | extracting the die | dye 24 from the elementary tube 20, as shown in the upper half of FIG. Then, the weld bead portion 21 existing in the raw tube 20 is pressed against the parallel molding portion 27 of the mandrel 23 by the push die 33. As a result, the weld bead portion 21 (convex bead 21a, concave bead 21b) is crushed, and as shown in FIG.
After that, as shown in the lower half of FIG. 3, the mandrel 23 is retracted and pulled out from the raw tube 20, and the push die 33 is retracted to the original standby position. finish.
[0018]
In this way, the outer cylinder (FIGS. 8 and 9) 3 of the hydraulic shock absorber is completed. The completed outer cylinder 3 has an opening end finished in a desired size and shape, and a desired inner surface roughness. Thus, the fitting and assembling of the rod guide 5 and the oil seal 6 to the opening end can be performed smoothly, and the cap 10 can be press-fitted smoothly. Moreover, since the taper surface 3c is formed in the inner edge of the opening end, the chamfering process for smooth insertion and assembly of the oil seal 6 becomes unnecessary.
[0019]
By the way, as described above, this type of hydraulic shock absorber has the rod guide 5 and the oil by the bending piece 10 formed by bending the opening end of the outer cylinder 3 over the entire circumference or by partially bending a plurality of places in the circumferential direction. Although the sealing of the seal 6 is attempted (FIG. 9), the bending of the bent piece 10 is considerably difficult due to a short processing length. As a result of intensive studies on the bending process of the bent piece 10, the present inventors, as shown in FIG. 6, provided that a thin wall portion 3 </ b> A thinner than a prescribed tube wall is provided at the tip of the outer cylinder 3. It has been found that it is extremely useful for smoothly performing the above.
[0020]
The following embodiment has been made based on the above-described knowledge. Here, as shown in FIG. 7, the taper forming portion 26 of the mandrel 23 used in the above-described embodiment (FIGS. 1 to 3). A sub-parallel molding part 40 having a slightly larger diameter than the parallel molding part 27 is provided between the parallel molding part 27 and the sub-molding part 40 and the parallel molding part 27 are connected by a taper molding part 41. is doing.
By using the mandrel 23 described above, the end of the raw tube 20 is moved by the die 24 to the sub parallel forming portion 40, the taper forming portion 41, and the parallel forming portion 27 together with the start of the parallel swaging shown in the upper half of FIG. Pressed down. As a result, the end portion of the outer cylinder 3 after processing is formed outside the fitting portion 3B (pipe end) having a prescribed inner diameter d1 necessary for fitting the rod guide 5 and the oil seal 6 as shown in FIG. And a thin portion 3A having an inner diameter d2 (d2> d1) slightly larger than the inner diameter d1, and an end portion provided with a step portion 3C between the thin portion 3A and the fitting portion 3B. It becomes a shape.
[0021]
The outer cylinder 3 obtained in this way is very easily bent inwardly with the thin-walled portion 3A starting from the stepped portion 3C when the bending piece 10 (FIG. 9) for retaining is bent by a press. Thus, the bent piece 10 can be formed easily and accurately.
Here, in the case where the bent piece 10 is formed by partially bending a plurality of places in the circumferential direction, only the place where the bent piece 10 is formed may be the thin portion 3A. In this case, the mandrel described above is used. The sub-parallel molding part 40 and the taper molding part 41 provided in 23 are intermittently provided in the circumferential direction.
[0022]
In each of the above embodiments, a cylindrical shape is used as the die 24. However, the die 24 may be ring-shaped. When a ring-shaped die is used, the above-described recessed relief portion 31 (FIG. 4) as an oil reservoir is not necessary.
Further, in the present invention, it is needless to say that other electric welded pipes such as TIG welded pipes, MIG welded pipes, plasma welded pipes and the like can be used as the raw pipes 20 in place of the above-mentioned electric resistance welded pipes.
[0023]
【The invention's effect】
As described above in detail, according to the pipe processing method and processing apparatus of the present invention, even if an inexpensive welded pipe is used and efficient parallel swaging is used, excellent dimensional shape accuracy and surface roughness are achieved. The cost can be ensured, and cost reduction and productivity improvement can be achieved. Further, since there is no risk of foreign matter mixing as in the case of machining, it is suitable for machining cylinders of hydraulic equipment such as hydraulic shock absorbers and cylinder devices. In addition, since the thin-walled portion used as a radially inwardly bent piece is formed at the distal end portion of the raw tube by the cooperation of the mandrel and the die, the bent piece can be easily bent later.
Further, in the method of the present invention, when parallel swaging is performed by a die after inserting the mandrel into the blank tube, the blank tube and the mandrel will not rub against each other during the parallel swaging. The inner surface is not damaged, and the surface roughness is further improved. At this time, when a tapered surface is formed on the inner edge of the tip of the raw tube by the 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 cylindrical die and the relief portion is used as a sump for lubricating oil, it greatly contributes to reduction of molding pressure and prevention of galling. To be.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a starting process 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 the final step of the processing method.
FIG. 4 is a cross-sectional view showing the structure of a mandrel and a die used in the present invention.
FIG. 5 is a schematic diagram showing a state before and after processing a weld bead portion.
FIG. 6 is a cross-sectional view showing a desirable end shape of an outer cylinder which is a processing target of the present invention.
7 is a cross-sectional view showing the structure of a mandrel and a die used for processing the outer cylinder shown in FIG. 6. FIG.
FIG. 8 is a cross-sectional view showing the overall structure of a hydraulic shock absorber equipped with an outer cylinder to be processed according to the present invention.
9 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 portion 23 Mandrel 24 Die 26 Mandrel taper forming portion 27 Mandrel parallel forming portion 31 Die relief portion 33 Push die 40 Mandrel sub parallel forming Part

Claims (5)

The mandrel is inserted into the base pipe made of a welded pipe, and parallel swage processing is performed by a die so that the base pipe is brought into close contact with the mandrel, and at this time, by the cooperation of the mandrel and the die, Form a thin wall part to be used as a radially inwardly bent piece, and then pull out the die from the blank tube, and leave the mandrel in the blank tube to bring the push die close to the blank tube from the outside of the radius. A method for processing a pipe, wherein the welded portion of the base pipe is crushed in cooperation with the mandrel.   2. The tube processing method according to claim 1, wherein after the mandrel is inserted into the base tube, parallel swaging is performed with a die.   The method of 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. The tube processing according to any one of claims 1 to 3 , wherein a relief portion having an inner diameter slightly enlarged is provided on an inner periphery of the cylindrical die, and the relief portion is used as an oil reservoir for lubricating oil. Method. A parallel swaging machine comprising: a clamp that supports a blank tube; a mandrel that can be inserted into the blank tube supported by the clamp; and a die that translates along the blank tube supported by the clamp. A pressing die that approaches and separates from a radially outward direction with respect to the pipe is provided, and a molding surface is provided on the mandrel for molding the tip of the raw pipe thinner than a prescribed pipe wall. Pipe processing equipment.

Images