JP2009195913A - Spinning method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a spinning method capable of suppressing local thickness reduction of a taper part and generation of wrinkles at a tube end when working a diameter-reduction portion comprising the taper part and a small diameter part continuing to the taper part by spinning. <P>SOLUTION: In a forward path toward the tube end of a tube to be worked, a working roller is pushed in the radial direction of the tube so as to be linearly varied proportionally to the distance in an axial direction with which the working roller moves from the start point of the forward path toward the end point thereof. In a return path, the working roller is pushed in the radial direction of the tube so as to be curvedly varied from the start point of the return path to the end point thereof in such a way as to be projected in the central axis direction of the tube from a straight line which connects the start point of the return path with the end point thereof. Working is carried out to form a protrusion at the tube end by allowing the working roller to turn back immediately before reaching the tube end. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for forming a tubular body having a reduced diameter portion at an end portion used for exhaust system parts such as a converter case and a muffler of an automobile.

The case of exhaust gas purification catalyst (converter), silencer (muffler) case, or exhaust gas purification catalyst using urea, which is equipped in the exhaust system of automobiles, needs to be increased in capacity and automobiles. From the viewpoint of reducing the weight of the tube, a large-diameter pipe having a thin plate thickness is used as a material. The end portions of the case members are provided with a tapered portion for connection with the front and rear members, and a small diameter portion continuous with the tapered portion as necessary.
In FIG. 1, such a case 1 has a large-diameter pipe portion (1c) as a raw material, a tapered portion (1b) provided to connect to the front and rear members, and a small-diameter straight pipe continuous to the tapered portion. The example comprised from the part (1a) is shown. And as the forming method, a spinning method is often used.

In the spinning method, the processing roller, which is a forming tool, is brought into contact with the surface of the processing tube, and the processing roller is revolved around the processing tube, while the processing roller is moved in the radial direction and the axial direction of the processing tube. This is a method of forming a tapered portion that gradually moves toward the end portion of the pipe to be processed and a small-diameter portion continuous therewith.
For example, Patent Document 1 describes that a converter case is manufactured by pressing a processing roller on the outer periphery of a pipe to be processed and performing a spinning process.

As a background of the spin processing method being frequently used as a method for forming a member having such a shape, 1) the material yield is high and 2) the production efficiency is high compared with the method in which the plate material is press-molded and then welded. 3) The member strength is high because it is integrally formed, and 4) the reliability of the member is not lowered due to the welded portion because welding is not required.
However, compared with the press forming method, the spinning method reciprocates the processing roller in the axial direction of the tube to be processed to advance the forming, so that the material is easily moved in the tube end direction of the tube to be processed by plastic deformation. In particular, the thickness of the tapered portion tends to locally decrease than the material thickness of the material to be processed.

In order to solve such a problem, Patent Document 2 proposes a method of pressing a reduced diameter side of a work tube while the work tube is being spun by a processing roller. However, this method requires a separate pressing device, and there is a problem that the cost of the device becomes high. Further, in Patent Document 3, as a method of moving the processing roller in the axial direction of the tube to be processed, in the case of forming a shape having a small-diameter straight pipe portion continuous to the tapered portion, after the tapered portion is first formed, There has been proposed a method of forming a straight pipe portion by moving a processing roller from a pipe end of a pipe to be machined to a central portion.
JP-A-11-1332038 JP 2000-179334 A JP 2004-160536 A

However, in the method of Patent Document 3, since the tube to be processed is hardened by forming the tapered portion at a predetermined angle, which is the first processing, a large processing force is required in the forming process from the end of the tapered portion to the straight tube portion. However, there is a problem that the spinning machine itself is expensive due to the maintenance of the processing force capability.
Further, both Patent Documents 2 and 3 have problems that the processing speed in the spinning process is increased, and that the wrinkle is likely to occur at the end portion when the ratio of the plate thickness to the outer diameter of the pipe to be processed is reduced. .
The present invention has been devised to solve such a problem, and when forming a tapered portion and a small diameter portion continuous therewith by spinning, it is possible to reduce a local thickness reduction at the tapered portion. Furthermore, it aims at providing the diameter reducing method which can suppress wrinkle generation | occurrence | production at the pipe end part to be processed.

In order to achieve the object of the spinning method of the present invention, a processing roller that is disposed outside the processing tube and relatively revolves around the processing tube is moved in the axial direction while moving in the radial direction of the processing tube. When forming a taper portion that gradually decreases in diameter toward the end portion of the pipe to be processed and a small diameter portion continuous with the taper portion by performing a plurality of reciprocating steps, processing is performed in forming the taper portion. The reciprocating movement of each path of the roller in the forward path toward the pipe end of the pipe to be processed is made so that the pushing of the processing roller in the radial direction of the pipe to be processed is directed from the forward path starting point of the path toward the forward path end point of the path. From the straight line connecting the return path start point and the return path end point of the path, the pushing of the processing roller in the radial direction of the pipe to be processed is given in a straight line in proportion to the moved axial distance. Inside the work tube So as to project toward the axial direction from the backward starting point of the path, characterized in that it gives to the curve vary over a return path end point of the path.
Further, in the axial reciprocation of the processing roller disposed on the outer periphery of the processing tube and relatively revolving around it, the processing tube is folded immediately before reaching the tube end of the processing tube. A protrusion may be formed at the end.

In the spinning method of the present invention, in the forward path in which the processing roller is directed toward the end of the work tube, the process roller is pushed in the radial direction of the work pipe from the forward path start point of the path toward the forward path end point of the path. From the straight line connecting the return path start point and the return path end point of the path, the pushing of the processing roller in the radial direction of the pipe to be processed is given in a straight line in proportion to the moved axial distance. The curve is changed from the return path starting point of the path to the return path end point of the path so as to be convex toward the central axis direction of the pipe to be processed. As a result, the deformation of the pipe to be processed in the forward path is mainly caused by the contraction pipe, and the change in the plate thickness is less likely to occur, so that a local reduction in the plate thickness of the tapered portion can be suppressed. In the return path, since the material is deformed in the direction opposite to the end portion of the pipe to be processed, the taper portion increases in plate thickness.
Furthermore, since the processing roller is folded immediately before reaching the end of the tube to be processed, wrinkles that are likely to occur at the tube end due to a small ratio of the plate thickness to the outer diameter of the tube to be processed can be suppressed. .

  The inventors use a processing tube and a processing roller that is disposed on the outer periphery of the processing tube and relatively revolves around the processing tube, and moves the processing roller in the radial direction of the processing tube while rotating the shaft. When forming a tapered portion that gradually decreases in diameter toward the end of the tube to be processed by reciprocating in the direction and a small-diameter portion continuous therewith, it is possible to reduce the local plate thickness of the tapered portion, Various studies have been conducted on methods for suppressing the generation of wrinkles at the edges.

  As a result, in the reciprocating motion of the processing roller in the axial direction of the tube to be processed, the reciprocating motion of each pass of the processing roller is performed in the radial direction of the processing tube of the processing roller in the outward path toward the tube end of the processing tube. Is pushed so as to change linearly in proportion to the axial distance moved from the forward path start point of the path to the forward path end point of the path, and in the return path toward the pipe to be processed in the radial direction of the workpiece. A curve extending from the return path start point of the path to the return path end point of the path so as to protrude from the straight line connecting the return path start point and the return path end point of the path toward the central axis direction of the pipe to be processed It has been found that local reduction in the thickness of the tapered portion can be suppressed by controlling the processing roller so as to change.

In order to suppress the occurrence of wrinkles at the end of the tube to be processed, the processing roller is not reciprocated in the axial direction beyond the end of the tube to be processed. However, it has been found that it is effective to reduce the amount of diameter reduction processing received by the end portion to be smaller than that of the processed portion other than the end portion and to form a so-called trumpet-shaped protrusion at the end portion.
The following points can be considered as a cause of locally reducing the thickness of the tapered portion by pushing the processing roller in the radial direction of the tube to be processed and reciprocating in the axial direction.

  That is, as shown in FIG. 2, when the end of the tube 2 to be processed is formed into the tapered portion 3 by spinning, the processing roller 4 is pushed in the radial direction of the tube 2 to be moved from the clamp 5 side to the tube end 6. The processing pipe 2 is machined by moving it in the axial direction, but when the processing roller 4 is pushed in a curve from the forward path starting point 7 where the machining is started to the forward path end point 8 where the machining of the forward path is finished, The position where the plate | board thickness of the taper part 3 reduces locally generate | occur | produces. The position where the plate thickness is locally reduced is in the vicinity where the pressing amount of the processing roller 4 is the largest, and the processing force that pulls the tube 2 to be processed toward the tube end 6 in the forward path of the processing roller 4 due to the increase of the pressing amount is also a part. As a result, the plate thickness deformation of the tube 2 to be processed is partially increased.

In FIG. 2, the processing portion is schematically illustrated so that the processing portion is formed by one-way reciprocation of the processing roller so that the relationship between the movement of the processing roller and the shape of the processing portion can be easily understood. In this method, the end of the pipe to be processed is gradually reduced in diameter by reciprocating the processing roller in a plurality of passes. The following FIG. 3 and FIG. 4 also schematically show the same one-pass processing.
Therefore, in order to suppress the local decrease in the thickness of the tapered portion, the tensile force toward the tube end in the forward path of the processing roller that causes the material to move toward the tube end of the tube to be processed by plastic working is applied. In order to realize this, it is necessary to form the tapered portion in the outward path so that the processing roller push-in pattern becomes the main component of the contraction tube while suppressing the elongation in the tube end direction. Is effective.

In order to make the indentation amount pattern in the outward path of the processing roller mainly the diameter reduction, the indentation amount pattern of the processing roller is not changed in a curve, but the processing roller 4 is in the outward path of the tube 2 as shown in FIG. If the pushing amount pattern is a linear change from the starting point 7 to the forward end point 8, the tensile force on the pipe end 6 due to a partial increase in pushing amount can be suppressed.
In the return path of the processing roller 4, even if the plate thickness deformation occurs, the plastic flow of the material to the clamp 5 side, and the boundary between the non-processed portion and the tapered portion is a corner portion. It becomes difficult to flow plastically. In other words, the plate thickness of the tapered portion 3 tends to increase, and the effect of suppressing the decrease in plate thickness is exhibited even if the pressing amount pattern of the processing roller 4 is changed in a curve.

  Note that the outer diameter of the tube end of the small diameter portion is slightly enlarged by this processing. Therefore, the pass shape may be adjusted so that the small diameter portion becomes parallel in the final processing pass. Or you may make it a desired shape by cutting and removing this pipe end part. As a method of adjusting the path shape in the final machining pass, in the final pass, the pressing of the machining roller in the return path may be given so as to change substantially linearly in accordance with the desired machining shape. Further, the final pass may be a forward-only process in which the pressing of the processing roller is given so as to change substantially linearly in accordance with a desired shape to be processed.

Moreover, the following points can be considered as the cause of the wrinkle being easily generated at the pipe end when the ratio of the plate thickness to the outer diameter of the pipe to be processed becomes small.
The circumference of the pipe changes because the taper part and the small diameter part at the end of the pipe to be processed are subjected to diameter reduction processing. It tends to occur. When the ratio of the plate thickness with respect to the outer diameter of the pipe to be processed is small, the rigidity of the pipe end is further reduced, so that wrinkles are conspicuous.

Therefore, in order to suppress the occurrence of wrinkles at the tube end, it is effective to suppress uneven deformation by increasing the material constraint in the circumferential direction of the tube at the tube end.
In order to increase the material constraint in the circumferential direction of the pipe at the pipe end, as shown in FIG. 4, the processing roller 4 is not reciprocated beyond the pipe end 6 of the pipe 2 to be processed, but to the edge of the pipe end 6. It is effective to reduce the amount of diameter reduction processed by the tube end 6 to be smaller than that of the small diameter portion 10 so that the tube end 6 becomes a so-called trumpet-shaped protrusion 11.

Thereby, the rigidity of a pipe end increases and generation | occurrence | production of the wrinkle which is a nonuniform deformation at the time of the circumference of a pipe | tube changing can be suppressed.
The trumpet-shaped projections can be formed in the desired shape by adjusting the path shape so that the small diameter part is parallel in the final machining pass of the spinning process, or by cutting and removing the tube end part after the spinning process. Can be.
Next, the processing roller push-in pattern is a curved pattern for both the forward path and the return path, and the thickness change of each part when the forward path is changed linearly and the return path is changed according to the present invention is examined. Examples are introduced as examples.

Example 1;
A raw pipe made of ferritic stainless steel plate with a thickness of 1.2 mm having mechanical properties of yield stress 251 MPa, tensile strength 428 MPa, and total elongation 36%, and having a diameter of 89.1 mm by plasma welding. To be processed pipe.
As shown in FIG. 5, the target shape of the coaxial spinning process was such that the taper angle θ was 60 °, the diameter d ₀ of the reduced diameter portion was 40 mm, and the length L ₀ of the small diameter portion was 20 mm. The number of processing passes was 13 passes, and the feed rate of the processing roller in the axial direction of the tube to be processed was constant 3000 mm / min.

As shown in FIG. 6, the processing roller push-in pattern has a radius of curvature of 300 mm over the forward path start point and the forward path end point in the forward path, and a radius of curvature of 350 mm over the return path start point and the return path end point in the forward path. In the case (condition (a)), in the forward path, a linear change with a step of 1.4 mm between the forward path start point and the forward path end point is assumed, and in the return path, the curvature radius is 100 mm from the return path start point to the return path end point (condition ( b)). However, in either case of condition (a) or condition (b), only the final machining pass has a linear path shape along the target shape of the workpiece. In FIG. 6, for easy understanding, the actual 13-pass machining is schematically replaced with a 5-pass machining.
The processed result is shown in FIG. A local thickness decrease at the taper is seen in both indentation amount patterns, but in the indentation amount pattern in which the forward path of condition (b) is a linear change and the inward path is a curve change, the thickness reduction amount is suppressed. It was possible.

Example 2;
The mechanical properties and materials were the same as those in Example 1, and two types of elementary pipes having a diameter of 89.1 mm and plate thicknesses of 0.8 mm and 1.0 mm were used as processed pipes. The ratio of the plate thickness t to the diameter D is 0.9% when the plate thickness is 0.8 mm, and 1.2% when the plate thickness is 1.0 mm. The final target shape of the coaxial spinning process was such that the taper angle θ was 30 °, the diameter d ₀ of the reduced diameter portion was 40 mm, and the length L ₀ of the small diameter portion was 20 mm. The number of machining passes was 11 and 13 and the feed speed of the machining roller in the axial direction of the work tube was 6000 and 7500 mm / min.

The pressing amount pattern of the processing roller is a linear change with a step of 1.4 mm between the forward path start point and the forward path end point in the forward path of each path shown in FIG. 6B, and on the return path to the return path start point and the return path end point. It was assumed that the radius of curvature was 100 mm. Further, horn-shaped as the axial direction of reciprocating the pipe end portion by folding immediately before reaching the pipe end of the work pipe shown in FIG. _{8 d-d 0 ≧ 2t,} L-L 0 ≧ 2t processing roller The generation of wrinkles at the end of the tube was compared between when the protrusion was formed and when it was not.
The results are shown in Table 1. When the ratio of the plate thickness to the diameter is reduced, the processing condition range in which wrinkles are generated is widened. However, it has been found that the range is narrowed by forming a trumpet-shaped protrusion at the pipe end.

Diagram showing the shape of catalyst (converter) case or silencer (muffler) Schematic diagram showing a conventional reciprocating pattern of processing rollers The schematic diagram which shows an example of the reciprocating motion pattern of the processing roller of this invention The schematic diagram which shows another example of the reciprocation pattern of the processing roller of this invention. The figure which shows the pipe end shape of the processed pipe which carried out the spinning process of Example 1. Schematic diagram of reciprocating pattern of processing roller of Example 1 The figure which shows the plate | board thickness change of Example 1. The figure which shows the pipe end shape of the processed pipe which carried out the spinning process of Example 2.

Explanation of symbols

1: Case 1a: Small diameter straight pipe portion of case 1b: Tapered portion of case 1c: Large diameter portion of case 2: Pipe to be processed 3: Tapered portion 4: Processing roller 5: Clamp 6: Pipe end 7: Outward starting point 8 : Outward end point, return path start point 9: Return path end point 10: Small diameter part 11: Projection part

Claims (2)

  By performing a plurality of passes of a step of reciprocating the processing roller, which is disposed outside the processing tube and revolves around the processing roller, in the radial direction while moving in the radial direction of the processing tube, the processing tube When forming a tapered portion that gradually decreases in diameter toward the end of the tape and a small-diameter portion that continues to the tapered portion, in forming the tapered portion, the reciprocating motion for each pass of the processing roller is performed on the pipe to be processed. In the outward path toward the pipe end, the pushing of the processing roller in the radial direction of the pipe to be processed changes linearly in proportion to the axial distance moved from the forward path start point of the path toward the forward path end point of the path. In the return path, the pressing of the processing roller in the radial direction of the processed pipe is made convex toward the central axis direction of the processed pipe from the straight line connecting the return path start point and the return path end point of the path. The path from the return point of the path Spinning method characterized by providing to the curve vary over a return path end point of.   The reciprocating motion in the axial direction of the processing roller which is arranged outside the processed pipe and revolves around the pipe is folded back just before reaching the pipe end of the processed pipe, and protrudes from the pipe end of the processed pipe The spinning processing method according to claim 1, wherein the processing in which the portion is formed is performed.

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