WO2021024572A1

WO2021024572A1 - Method for manufacturing cylindrical member

Info

Publication number: WO2021024572A1
Application number: PCT/JP2020/019876
Authority: WO
Inventors: 紘和岩本; 早川　尚志; 恒彦木村
Original assignee: 株式会社三五
Priority date: 2019-08-06
Filing date: 2020-05-20
Publication date: 2021-02-11
Also published as: MY192796A; JP7041319B2; JPWO2021024572A1

Abstract

In a method for forming, through a spinning process, a cylindrical member having a straight tube part and a reduced tube part that is adjacent to the straight tube part and has an axis that has at least a relationship of being eccentric, inclined, or twisted with respect to the axis of the straight tube part, and that has a final target shape having a portion protruding further outside than a virtual extension surface of the straight tube part, a first step is performed to cause a portion of a workpiece having a straight tube shape to protrude toward the outside of the virtual extension surface to an extent equal to or greater than the final target shape by making the pressing force on one side of the workpiece due to a processing tool smaller than the other side, and thereafter the final target shape is formed by reducing the difference in the pressing force between one side and the other side. Accordingly, the cylindrical member provided with the reduced tube part protruding outward from the virtual extension surface of the straight tube part can be more easily formed. The first step may involve a state where in at least a portion of a plurality of paths of the processing tool, the processing tool does not make contact with one side of the workpiece. At at least a path start point in the path, it is preferable that the processing tool presses the workpiece.

Description

Manufacturing method of tubular member

In the present invention, a tubular member having a contracted tube portion protruding outward from the virtual extension surface of the outer peripheral surface of the straight tube portion is formed from a workpiece having a straight tubular shape by spinning processing. The present invention relates to a method for manufacturing a shaped member.

For example, in exhaust system parts such as catalyst converters and silencers of automobiles, for example, for the purpose of improving productivity and mountability on a vehicle, for example, eccentricity with respect to the central axis of a straight pipe portion (main body portion) ( There is a demand for an outer cylinder (case) having a complicated shape having an offset) and / or an inclined reduced tube portion (reduced diameter portion) at an end portion. A tubular member such as an outer cylinder having such a shape can be satisfactorily manufactured by forming the end portion of a work (bare tube) by, for example, eccentric spinning processing and / or inclined spinning processing.

However, in the technical field, it is said that it is impossible to form a reduced pipe portion protruding outward from the virtual extension surface of the outer peripheral surface of the raw pipe (work) of the processing source by general spinning processing. (See, for example, Patent Document 1).

Therefore, in the art, a tubular stepped work having a non-processed portion having an outer shape of the final target shape of the main body portion and a machining target portion adjacent to the non-processed portion and having a larger outer diameter than the non-processed portion is provided. It has been proposed to form a tubular member having a reduced diameter portion protruding outward from the virtual extension surface of the outer peripheral surface of the main body portion by spinning processing used as a raw pipe (for example, Patent Documents 2 and 3). See). Such a stepped work can be formed by, for example, expanding or reducing the diameter of one end of a raw tube having a straight tubular shape.

However, there is a problem to be improved even in the spinning process using the above-mentioned stepped work as a raw pipe. For example, when forming a stepped work by reducing the diameter of one end of a raw pipe, for example, the weld bead portion of a welded steel pipe such as an electric resistance pipe comes into contact with the reduced pipe mold before other portions, so that the weld bead portion Stress is concentrated at the boundary between the base metal and the base metal. As a result, the material escapes to the inside of the work, which may lead to buckling. On the other hand, when one end of the raw pipe is expanded to form a stepped work, the peripheral length of the work increases as the diameter increases, so that the plate thickness (thickness) of the enlarged diameter portion decreases. Further, in both the case where one end of the raw pipe is reduced in diameter and the case where the diameter is increased, there is a possibility that cracks may occur in the weld bead portion due to hardening (work hardening) of the portion processed in this way.

As described above, according to the spinning process according to the prior art as described above, it is possible to form a tubular member having a contracted tube portion protruding outward from the virtual extension surface of the outer peripheral surface of the straight tube portion. is there. However, in the process of forming the stepped work and the process of forming the tubular member from the stepped work as described above, there are problems such as reduction of plate thickness, buckling in the vicinity of the weld bead portion, and cracking in the weld bead portion. It may occur.

Japanese Patent No. 4683519 Japanese Patent No. 4450504 Japanese Patent No. 4303455

As described above, in the art, there is a continuation of manufacturing methods that can more easily form a tubular member having a contracted tube portion that projects outward from the virtual extension surface of the outer peripheral surface of the straight tube portion. There is a demand.

In view of the above problems, as a result of diligent research, the present inventor has found that the straight pipe portion is adjacent to the straight pipe portion and has at least one of eccentricity, inclination and twist with respect to the axis of the straight pipe portion. On one side of the work, in a method of forming a tubular member having a reduced tube portion having a final target shape and having a portion of the straight tube portion protruding outward from the virtual extension surface of the straight pipe portion by spinning. One side and the other after the first step in which the pressing force by the machining tool is made smaller than the other side and a part of the work having a straight tubular shape is projected to the outside of the virtual extension surface at least equal to the final target shape. By reducing the difference in pressing force from the side of the pipe to form the final target shape, it is possible to more easily form a tubular member having a contracted pipe portion protruding outward from the virtual extension surface of the straight pipe portion. I found. At least a part of the plurality of paths of the machining tool in the first step may include a state in which the machining tool does not contact one side of the work. It is desirable that the machining tool presses the work in the path at least at the starting point of the path.

Specifically, the method for manufacturing a tubular member according to the present invention (hereinafter, may be referred to as "the method of the present invention") is a raw tube having a cylindrical shape using a spinning processing device. This is a method for manufacturing a tubular member, which forms a tubular member having a straight pipe portion and a contracted pipe portion by performing a spinning process in a range from one end to the middle of a work in the axial direction. The straight pipe portion is a portion where a part of the work is maintained in an unprocessed state. The reduced pipe portion has an axis that is adjacent to the straight pipe portion and has at least one relationship of eccentricity, inclination, and twist with respect to the axis of the straight pipe portion, and a part of the outer peripheral surface of the straight pipe portion. It is a part having a final target shape protruding outward from the virtual extension surface.

The spinning processing device is configured to be able to control the work angle, offset, and pressing radius, respectively. The work angle is an angle formed by the rotation axis of the machining tool that presses the work and the axis of the work. The offset is the distance between the central axis of the workpiece portion pressed by the machining tool and the rotation axis of the machining tool. The pressing radius is the distance from the rotation axis of the pressing portion of the processing tool.

The work used in the method of the present invention has a straight tubular shape having a constant outer diameter. Furthermore, the method of the present invention includes the first step and the second step shown below.

In the first step, the final target is the portion corresponding to the protruding portion of the work by controlling the combination of the work angle and the offset and / or the pressing radius so that the first pressing force becomes smaller than the second pressing force. This is a step of projecting to the position of the protruding portion in the shape or a position outside the virtual extension surface from the position. The first pressing force is the pressing force on the workpiece of the machining tool on the protruding side where the protruding portion is formed, which is the portion protruding outward from the virtual extension surface in the final target shape of the contracted tube portion of the tubular member. is there. The second pressing force is the pressing force on the workpiece of the machining tool on the opposite side of the protruding side with the rotation axis of the machining tool in between.

In the second step, after the first step, the pressing force difference, which is the difference between the first pressing force and the second pressing force, is smaller than the pressing force difference in the first step, and the first pressing force is equal to or less than the second pressing force. This is a step of forming a contracted tube portion having a final target shape by controlling the combination of the work angle and the offset and / or the pressing radius.

In one aspect of the method of the present invention, at least a part of a plurality of paths of the machining tool in the first step may include a state in which the machining tool does not come into contact with one side of the work. In this case, at least a part of the plurality of paths of the machining tool in the first step is a non-contact path including a state in which the machining tool does not contact the work when the machining tool is on the protruding side. In addition, the combination of the work angle and the offset and / or the pressing radius is controlled.

In another aspect of the method of the present invention, in the non-contact path described above, the machining tool may press the work at least at the starting point of the path. In this case, in at least a part of the non-contact paths, the workpiece is pressed so that the machining tool presses the work when the machining tool is on the protruding side at the starting point which is at least the end of the machining tool on the straight pipe side. The combination of angle and offset and / or pressing radius is controlled.

According to the method of the present invention, a tubular member having a contracted tube portion that protrudes outward from the virtual extension surface of the outer peripheral surface of the straight tube portion is spun into a work having a straight tubular shape having a constant outer diameter. By applying, it is possible to mold more easily without requiring a stepped work.

Other objects, other features and accompanying advantages of the present invention will be readily understood from the description of each embodiment of the invention described with reference to the drawings below.

It is a flowchart which shows the flow of each step executed in the manufacturing method (1st method) of the tubular member which concerns on 1st Embodiment of this invention. It is a schematic diagram which shows an example of the structure of the specific tubular member. It is a schematic diagram which shows how the processing tool moves in a general spinning process. It is a schematic diagram which illustrates the structure of the straight tubular work (a) used in the 1st method, and stepped work (b) used in the general spinning process which concerns on the prior art. It is a schematic diagram which shows the change of the shape of the work in the 1st step included in the 1st method. It is a schematic diagram which shows an example of the locus in each path of the processing tool in the 1st method. It is a schematic diagram which shows the shape of the work corresponding to the locus in the Nth pass of the processing tool shown in FIG. It is a schematic diagram which shows the positional relationship of the machining tool and the work in the 0th pass (N = 0) of the machining tool shown in FIG. 7, and the shape of the work. It is a schematic diagram which shows the positional relationship of the machining tool and the work in the 2nd pass (N = 2) of the machining tool shown in FIG. 7, and the shape of the work. It is a schematic diagram which shows the positional relationship of the machining tool and the work in the 5th pass (N = 5) of the machining tool shown in FIG. 7, and the shape of the work. It is a schematic diagram which shows the positional relationship of the machining tool and the work in the 8th pass (N = 8) of the machining tool shown in FIG. 7, and the shape of the work. It is a schematic diagram which shows the positional relationship of the machining tool and the work in the 11th pass (N = 11) of the machining tool shown in FIG. 7, and the shape of the work. It is a schematic diagram which shows the positional relationship of the machining tool and the work in the 14th pass (N = 14) of the machining tool shown in FIG. 7, and the shape of the work. The positional relationship between the machining tool and the work when the machining tool is on the protruding side in the non-contact path in the first step included in the method for manufacturing a tubular member (third method) according to the third embodiment of the present invention is shown. It is a schematic diagram.

<< First Embodiment >>
Hereinafter, a method for manufacturing a tubular member according to the first embodiment of the present invention (hereinafter, may be referred to as a “first method”) will be described.

<Constitution>
The first method is to use a spinning processing device to perform spinning processing from one end to the middle of the work, which is a raw pipe having a cylindrical shape, in the axial direction, thereby forming a straight pipe portion and a contracted pipe. This is a method for manufacturing a tubular member, which forms a tubular member having a portion. The straight pipe portion is a portion where a part of the work is maintained in an unprocessed state. The reduced pipe portion has an axis that is adjacent to the straight pipe portion and has at least one relationship of eccentricity, inclination, and twist with respect to the axis of the straight pipe portion, and a part of the outer peripheral surface of the straight pipe portion. It is a part having a final target shape protruding outward from the virtual extension surface. In the following description, a tubular member having a straight pipe portion and a reduced pipe portion as described above may be referred to as a "specific tubular member".

Machining tool refers to a molding tool that is pressed against the work in spinning. Specific examples of the processing tool include forming tools such as spatulas and rollers. Since the general configuration and operation of the spinning processing apparatus are well known to those skilled in the art, detailed description thereof will be omitted here.

The work used in the first method has a straight tubular shape having a constant outer diameter. That is, in the first method, a raw tube having a straight tubular shape is used as the work, not a raw tube having a special shape like the stepped work used in the above-mentioned conventional technique. Specific examples of such a work include a metal pipe such as a steel pipe.

Further, the method of the present invention includes the first step and the second step shown below. FIG. 1 is a flowchart showing the flow of each process executed in the first method.

In the first step shown as step S01 in FIG. 1, the combination of the work angle and the offset and / or the pressing radius is controlled so that the first pressing force Pf1 becomes smaller than the second pressing force Pf2. This is a step of projecting the portion corresponding to the protruding portion of the work to the position of the protruding portion in the final target shape or a position outside the virtual extension surface from the position. The first pressing force Pf1 is the pressing force against the work of the machining tool on the protruding side, which is the side where the protruding portion is formed, which is the portion protruding outward from the virtual extension surface in the final target shape of the contracted tube portion of the tubular member. Is. The second pressing force Pf2 is the pressing force on the workpiece of the machining tool on the opposite side of the protruding side with the rotation axis of the machining tool sandwiched. The magnitude of the difference between the first pressing force Pf1 and the second pressing force Pf2 in the first step is the pressing force difference ΔPf1 (Pf2-Pf1 = ΔPf1).

As described above, in the first step, the combination of the work angle and the offset and / or the pressing radius is set so that the pressing force acting on the work by the machining tool is larger on the opposite side of the protruding side than on the protruding side. Be controlled. Specifically, by controlling the combination of the work angle and the offset, the combination of the work angle and the pressing radius, or the combination of the work angle and the offset and the pressing radius, the pressing force acting on the work by the machining tool protrudes. Spinning is applied to the work while achieving a larger state on the opposite side of the protruding side than on the side.

As a result of the above, the amount of protrusion of the tip side (constricted tube side) of the work toward the protruding side gradually increases. Eventually, the portion corresponding to the protruding portion of the work (that is, the portion that becomes the protruding portion in the final target shape) protrudes to the position of the protruding portion in the final target shape or a position outside the virtual extension surface from the position. At this point, the first step is completed and the process proceeds to the next second step.

The virtual extension surface of the outer peripheral surface of the straight pipe portion is a surface obtained when the outer peripheral surface of the straight pipe portion is extended in the axial direction of the straight pipe portion. As described above, the straight pipe portion is a portion where a part of the work is maintained in an unprocessed state. Therefore, the virtual extension surface is also a surface obtained when the outer peripheral surface of the work is extended in the axial direction of the work.

Next, in the second step shown as step S02 in FIG. 1, after the first step, the pressing force difference, which is the difference between the first pressing force and the second pressing force, is larger than the pressing force difference in the first step. This is a step of forming a contracted tube portion having a final target shape by controlling the combination of the work angle and the offset and / or the pressing radius so that the first pressing force is smaller than the second pressing force. ..

As described above, in the second step, the portion corresponding to the contracted tube portion of the work (that is, the portion that becomes the contracted tube portion of the finally obtained tubular member) is formed into the final target shape and the contracted tube. The combination of the workpiece angle and the offset and / or pressing radius is controlled so that the portion is formed. In this respect, the spinning process performed in the second step is basically the same as the general spinning process.

However, in the first step, the portion corresponding to the protruding portion of the work is already formed so as to protrude to the position of the protruding portion in the final target shape or a position outside the virtual extension surface from the position. That is, it is not necessary to bend the work to the protruding side any more in the second step. Therefore, in the second step, the work angle and the offset and / or the pressing radius are set so that the pressing force difference, which is the difference between the first pressing force and the second pressing force, is smaller than the pressing force difference in the first step. The combination of is controlled.

In addition to the above, in the first step, the protrusion amount of the portion corresponding to the position of the protrusion in the final target shape or the protrusion of the work formed so as to protrude to a position outside the virtual extension surface from the position is It is necessary to prevent the portion from being reduced in the second step and returning to the inside of the virtual extension surface. Therefore, in the second step, it is necessary that the first pressing force is equal to or less than the second pressing force. In other words, in the second step, it is necessary that the first pressing force is not larger than the second pressing force. Therefore, in the second step, the combination of the work angle and the offset and / or the pressing radius is controlled so that the first pressing force is equal to or less than the second pressing force.

<Molding process>
Here, the molding process of the work in the first method will be described in detail below with reference to the drawings. FIG. 2 is a schematic view showing an example of the structure of the specific tubular member. (A) is a partial cross-sectional view when the specific tubular member is observed from the side surface, (b) is a plan view when the specific tubular member is observed from the opposite side of the protruding side, and (c) is (c). It is sectional drawing of the straight pipe part of the specific tubular member by the plane including the broken line AA shown in b).

The specific tubular member 200 illustrated in FIG. 2 includes a straight pipe portion 210, which is a portion of the work that is maintained in an unprocessed state, and a straight pipe portion 210 that is adjacent to the straight pipe portion 210 and has a straight pipe portion 210. It has an axis that is inclined with respect to the axis, and has a final target shape in which a part (the part surrounded by the broken line) protrudes outward from the virtual extension surface (two-dot chain line) of the outer peripheral surface of the straight pipe portion 210. It is a tubular member having a reduced tube portion 220 which is a portion.

As described at the beginning of the present specification, in the technical field, a contracted pipe portion protruding outward from the virtual extension surface of the outer peripheral surface of the raw pipe (work) of the processing source is formed by general spinning processing. It is said that it is impossible to do so. That is, it is not possible to form the specific tubular member as illustrated in FIG. 2 from a work having a straight tubular shape by general spinning processing. This is because, for example, as shown in FIG. 3, in general spinning processing, the processing tool 310 moves inward from the outer peripheral surface (dashed line) of the work while pressing the work (white outline). See the arrow).

Therefore, for example, in order to form the specific tubular member as illustrated in FIG. 2 by a general spinning process, it is not the straight tubular work 100 as shown in FIG. A tubular stepped work 130 having a non-processed portion 110 corresponding to the straight pipe portion 210 as shown in b) and a processed target portion 120 adjacent to the non-processed portion 110 and having an outer diameter larger than that of the non-processed portion 110. It is necessary to use it as a bare tube.

On the other hand, in the first method, as described above, a raw tube having a straight tubular shape is used as a work. Then, in the first step, the portion of the work corresponding to the protruding portion of the reduced tube portion constituting the specific tubular member is placed outside the position of the protruding portion in the final target shape of the reduced tube portion or the virtual extension surface from the position. Protrude to the position of. Such a forming process is performed in the spinning processing apparatus by controlling the combination of the work angle and the offset and / or the pressing radius so that the first pressing force becomes smaller than the second pressing force.

FIG. 5 is a schematic view showing a change in the shape of the work in the first step included in the first method. As shown by the dotted line in FIG. 5A, in the final target shape of the reduced tube portion 220, a part (protruding portion) of the reduced tube portion 220 is larger than the virtual extension surface of the straight tube portion 210 by the amount of protrusion D. It protrudes outward. Such a shape cannot be formed by general spinning. However, in the first step, the pressing force (first pressing force Pf1) at which the machining tool 310 presses the work 100 on the projecting side (lower side toward the drawing) on which the protruding portion is formed is the machining tool 310. The combination of the work angle and the offset and / or the pressing radius is set so that the machining tool 310 is smaller than the pressing force (second pressing force Pf2) pressing the work 100 on the opposite side of the rotating shaft of Be controlled.

Specifically, for example, rotation of a machining tool that presses the work by rotating a clamp 320 that holds the work 100 around an axis that forms a predetermined angle (for example, 90 °) with respect to the axis of the work 100. The work angle, which is the angle formed by the axis and the axis of the work, can be controlled. Further, by adjusting the position of the clamp 320 with respect to the axis of the work 100, it is possible to control the offset which is the distance between the central axis of the part of the work pressed by the machining tool and the rotation axis of the machining tool. Further, by adjusting the position of the machining tool 310 from the rotation axis, it is possible to control the pressing radius, which is the distance from the rotation axis of the pressing portion of the machining tool.

As a result of the above, as shown by a thick solid line in FIG. 5B, the portion of the work 100 corresponding to the protruding portion in the final target shape of the contracted tube portion 220 is the position of the protruding portion or a virtual extension surface from the position. It can be projected to a more outer position. Therefore, in the next second step, the portion corresponding to the contracted tube portion 220 of the work 100 (that is, the contracted tube portion 220 of the finally obtained tubular member 200) is obtained in the same manner as the general spinning process. The contracted tube portion 220 can be formed by molding the portion) into the final target shape.

Note that FIG. 5 shows a very schematic change in the shape of the work 100 in the first step for the purpose of facilitating the understanding of the present invention, and accurately represents the actual shape of the work 100. is not it. Therefore, the transition of the processed shape of the work 100 in the process of forming the specific tubular member 200 from the work 100 having a straight tubular shape by the first method will be described in detail below.

FIG. 6 is a schematic diagram showing an example of a locus in each path of the machining tool in the first method. More specifically, in FIG. 6, a specific tubular member having a straight pipe portion 210 in which a part of the work is maintained in an unprocessed state and a contracted pipe portion 220 having a substantially tapered final target shape. On the left side of the drawing of 200, a figure showing the trajectory of the machining tool in the first method in the Nth pass is drawn by a thick solid line (N = 2, 5, 8, 11, 14). In each path of the machining tool in the first method, the combination of the work angle and the offset and / or the pressing radius is appropriately controlled as described above.

FIG. 7 is a schematic view showing the shape of the work 100 corresponding to the locus in the Nth pass of the machining tool shown in FIG. 6 (N = 0,2,5,8,11,14). In the example shown in FIG. 7, the portion of the work 100 corresponding to the protruding portion of the reduced tube portion 220 constituting the specific tubular member is indicated by the (dotted line) of the reduced tube portion 220 by the fifth pass of the processing tool. It protrudes to the position of the protruding part in the final target shape. That is, in the example shown in FIG. 7, up to the fifth pass of the machining tool corresponds to the above-mentioned first step, and the sixth and subsequent passes of the machining tool correspond to the above-mentioned second step.

As described above, in the first method, the above-mentioned first step and the second step are executed by appropriately controlling the combination of the work angle and the offset and / or the pressing radius. Therefore, the Nth pass (N = 2,5,8,11,14) of the machining tool shown in FIG. 6 and the Nth pass (N = 0,2,5,8,11) of the machining tool shown in FIG. , 14) The positional relationship between the machining tool and the work (work angle, offset and pressing radius) in the path and the shape of the work are schematically shown in FIGS. 8 to 13, respectively. In these figures, the final target shape of the portion of the specific tubular member to be the contracted tube portion 220 finally obtained is shown by the dotted line.

FIG. 8 is a schematic view showing a state in which the work 100 is held by a clamp 320 included in a spinning machine (not shown) at the start of the first method, and the work 100 has not yet been pressed by a machining tool (not shown). Indicates a state (ie, N = 0). Therefore, in FIG. 8, the work 100 has a straight tubular shape.

Next, FIG. 9 shows the positional relationship (work angle, offset and pressing radius) of the machining tool 310 and the work 100 in the second pass (N = 2) of the machining tool 310 shown in FIGS. 6 and 7, and the work 100. It is a schematic diagram which shows the shape of. In the second pass illustrated in FIG. 9, the work 100 is rotated clockwise by a predetermined angle and offset by a predetermined amount to the protruding side (lower side toward the drawing) as shown by the white arrow. Spinning is performed with a predetermined pressing radius. At this time, as described above, the pressing force (first pressing force Pf1) of the machining tool 310 on the work 100 on the protruding side of the work 100 is the machining tool 310 on the opposite side of the protruding side across the rotation axis of the machining tool 310. It is controlled to be smaller than the pressing force on the work 100 (second pressing force Pf2). As a result, the amount of protrusion of the tip side (the side that becomes the contracted tube portion 220) of the work 100 toward the protruding side is slightly increased.

Further, FIG. 10 is a schematic view showing the positional relationship between the machining tool 310 and the work 100 and the shape of the work 100 in the fifth pass (N = 5) shown in FIGS. 6 and 7. In the fifth pass illustrated in FIG. 10, the spinning process is performed with a larger work angle, a larger offset, and a smaller pressing radius as compared with the second pass illustrated in FIG. Also in this pass, the first pressing force Pf1 is controlled to be smaller than the second pressing force Pf2. As a result, the amount of protrusion of the tip side portion of the work 100 toward the protruding side is further increased, and the tip end side portion of the work 100 is the protruding portion of the contracted tube portion 220 (indicated by the dotted line) in the final target shape. It protrudes to the position. That is, in the examples shown by these figures, as described above, up to the fifth pass (N = 5) of the machining tool 310 corresponds to the first step described above, and the sixth and subsequent passes of the machining tool 310 ( N ≧ 6) corresponds to the second step described above.

Next, FIG. 11 is a schematic diagram showing the positional relationship between the machining tool 310 and the work 100 and the shape of the work 100 in the eighth pass (N = 8) shown in FIGS. 6 and 7. In the eighth pass illustrated in FIG. 11, the spinning process is performed with a larger work angle, a larger offset, and a smaller pressing radius as compared with the fifth pass illustrated in FIG. However, since the first step is completed by the spinning process up to the fifth pass (N = 5) illustrated in FIG. 10 as described above, the eighth pass (N = 8) illustrated in FIG. 11 is Corresponds to the second step. Therefore, the pressing force difference ΔPf2, which is the difference between the first pressing force Pf1 and the second pressing force Pf2 at this time, is smaller than the pressing force difference ΔPf1 in the first step, and the first pressing force is equal to or less than the second pressing force. As described above, the combination of the work angle and the offset and / or the pressing radius is controlled.

Further, as described above, the work 100 formed so as to project to the position of the protruding portion in the final target shape by the spinning process (first step) up to the fifth pass (N = 5) illustrated in FIG. The amount of protrusion of the portion corresponding to the protrusion is reduced in the spinning process (second step) after the sixth pass (N = 6) so that the portion does not return to the inside of the virtual extension surface. There is a need. Therefore, as described above, in the second step, the combination of the work angle and the offset and / or the pressing radius is controlled so that the first pressing force Pf1 is equal to or less than the second pressing force Pf2. As a result, the portion on the tip end side (the side that becomes the reduced tube portion 220) of the work 100 is formed so as to approach the final target shape of the reduced tube portion 220.

Then, as shown in FIGS. 12 and 13, in the 11th and 14th passes (N = 11 and N-14) shown in FIGS. 6 and 7, a larger work angle, a larger offset, and a smaller pressing force are then made. Spinning is performed at the radius. Also in these passes, the pressing force difference ΔPf2, which is the difference between the first pressing force Pf1 and the second pressing force Pf2, is smaller than the pressing force difference ΔPf1 in the first step, and the first pressing force is equal to or less than the second pressing force. The combination of the work angle and the offset and / or the pressing radius is controlled so as to be. As a result, the portion on the tip end side (the side that becomes the reduced tube portion 220) of the work 100 is formed so as to be closer to the final target shape of the reduced tube portion 220.

If the cutting edge of the final shape obtained as described above (the leftmost portion when facing the drawing) is longer than the cutting edge of the final target shape of the reduced tube portion 220, for example, cutting or the like. Depending on the method, secondary processing may be performed to a shape that matches the final target shape.

<effect>
As described above, according to the method of the present invention, a tubular member having a contracted tube portion protruding outward from the virtual extension surface of the outer peripheral surface of the straight tube portion has a straight tubular shape having a constant outer diameter. By applying spinning processing to the work, it can be formed more easily without the need for a stepped work.

<< Second Embodiment >>
Hereinafter, a method for manufacturing a tubular member according to a second embodiment of the present invention (hereinafter, may be referred to as a “second method”) will be described. As described above, in the first step included in the first method, the combination of the work angle and the offset and / or the pressing radius is controlled so that the first pressing force Pf1 becomes smaller than the second pressing force Pf2. To. As a result, the portion corresponding to the protruding portion of the work can be projected to the position of the protruding portion in the final target shape or a position outside the virtual extension surface from the position.

In the above, from the viewpoint of more efficiently projecting the portion corresponding to the projecting portion of the work, in at least a part of the plurality of paths of the machining tool in the first step, the machining tool does not come into contact with the protruding side of the work. It is desirable to cause it.

<Constitution>
Therefore, the second method is the first method described above, and the machining tool comes into contact with the work when at least a part of the plurality of passes of the machining tool in the first step is on the protruding side. It is a method of manufacturing a tubular member that controls a combination of a work angle and an offset and / or a pressing radius so as to be a non-contact path that includes a non-contact state.

In the above non-contact path, when the machining tool is on the protruding side, the machining tool does not come into contact with the work. In this way, when the machining tool is on the protruding side and the machining tool does not come into contact with the work, the machining tool is on the opposite side of the protruding side than when the machining tool is on the protruding side. Will be in contact with the work for a longer period of time. In addition, since the machining tool does not come into contact with the work when the machining tool is on the protruding side, the first push pressure Pf1 can be made smaller than the second push pressure Pf2 more reliably, and the first push in the first step can be performed. The pressing pressure difference ΔPf1 (= Pf2-Pf1), which is the difference between the pressure Pf1 and the second pressing pressure Pf2, can be sufficiently increased.

<effect>
As described above, in the second method, at least a part of the plurality of paths of the machining tool in the first step includes a state in which the machining tool does not contact the work when the machining tool is on the protruding side. The combination of the work angle and the offset and / or the pressing radius is controlled so as to be a non-contact path. Therefore, according to the second method, the portion corresponding to the protruding portion of the work can be more reliably projected to the position of the protruding portion in the final target shape or a position outside the virtual extension surface from the position.

<< Third Embodiment >>
Hereinafter, a method for manufacturing a tubular member according to a third embodiment of the present invention (hereinafter, may be referred to as a “third method”) will be described. As described above, in the second method, at least a part of the plurality of paths of the machining tool in the first step includes a state in which the machining tool does not contact the work when the machining tool is on the protruding side. The combination of the work angle and the offset and / or the pressing radius is controlled so as to be a non-contact path. Therefore, according to the second method, the portion corresponding to the protruding portion of the work can be more reliably projected to the position of the protruding portion in the final target shape or a position outside the virtual extension surface from the position.

However, according to the findings obtained by the present inventor, even in the above-mentioned non-contact path, the final target is the portion corresponding to the protruding portion of the work by making the machining tool press the work at least at the starting point of the path. It is possible to project more efficiently to the position of the protruding portion in the shape or to a position outside the virtual extension surface from the position.

<Constitution>
Therefore, the third method is the above-mentioned third method, in which the machining tool is on the protruding side at least in at least a part of the non-contact paths at the starting point which is the end of the path of the machining tool on the straight pipe portion side. It is a method of manufacturing a tubular member that controls a combination of a work angle and an offset and / or a pressing radius so that a machining tool sometimes presses a work.

FIG. 14 is a schematic view showing the positional relationship between the machining tool and the work when the machining tool is on the protruding side in the non-contact path in the first step included in the third method. In the example shown in FIG. 14, the machining tool 310 presses the portion of the work 100 corresponding to the contracted tube portion (220) of the specific tubular member at the starting point (the portion surrounded by the broken line), and then the machining tool 310 presses the work 100. The work angle, offset and pressing radius are controlled so as to move away from.

As described above, when the machining tool is on the protruding side at the starting point (the part surrounded by the broken line) which is the end on the straight pipe side of the path of the machining tool, the machining tool presses the work to form a specific tubular shape. It is considered that stress concentration occurs on the pressing portion in the portion of the work corresponding to the contracted tube portion of the member, and the work bends more easily starting from the pressing portion. Regarding the magnitude of the pressing force of the machining tool with respect to the work at the above starting point, the first pressing force is smaller than the second pressing force, and the amount of protrusion of the work portion corresponding to the contracted tube portion of the specific tubular member is reduced. There is no particular limitation as long as the relevant part does not return to the inside of the virtual extension surface.

<effect>
As described above, in the third method, in at least a part of the non-contact paths, the machining tool is operated when the machining tool is on the protruding side at least at the starting point which is the end of the machining tool path on the straight pipe portion side. The combination of the work angle and the offset and / or the pressing radius is controlled so as to press the work. Therefore, according to the third method, the portion corresponding to the protruding portion of the work can be more efficiently projected to the position of the protruding portion in the final target shape or a position outside the virtual extension surface from the position. ..

As described above, for the purpose of explaining the present invention, some embodiments having a specific configuration have been described with reference to the accompanying drawings, but the scope of the present invention is limited to these exemplary embodiments. It should not be construed as being limited, and it goes without saying that amendments can be made as appropriate within the scope of claims and the matters described in the specification.

100 ... Work (straight tubular), 110 ... Non-machined part, 120 ... Machined part, 130 ... Stepped work, 200 ... Specific tubular member, 210 ... Straight pipe part, 220 ... Shrinked pipe part, 310 ... Processing tool, And 320 ... Clamp.

Claims

The work angle, which is the angle formed by the rotation axis of the machining tool that presses the workpiece, which is a raw tube having a cylindrical shape, and the axis of the workpiece, the central axis of the portion of the workpiece pressed by the machining tool, and the machining. The work is made by using a spinning machine configured to be able to control the offset, which is the distance of the tool from the rotation axis, and the pressing radius, which is the distance of the pressing portion of the processing tool from the rotation axis. A straight pipe portion, which is a portion in which a part of the work is maintained in an unprocessed state by performing spinning processing in a range from one end to the middle in the axial direction of the work, and the straight pipe portion. It has an axis that is adjacent to and has at least one relationship of eccentricity, inclination, and twist with respect to the axis of the straight pipe portion, and a part of the shaft is outside the virtual extension surface of the outer peripheral surface of the straight pipe portion. A method for manufacturing a tubular member, which forms a tubular member having a contracted tube portion which is a portion having a protruding final target shape.
The work has a straight tubular shape having a constant outer diameter and has a straight tubular shape.
The first pressing force, which is the pressing force on the work of the machining tool on the protruding side, which is the side where the protruding portion is formed, which is the portion protruding outward from the virtual extension surface in the final target shape, is the rotation of the machining tool. The combination of the work angle and the offset and / or the pressing radius is controlled so as to be smaller than the second pressing force, which is the pressing force of the machining tool on the work on the opposite side of the protruding side with the shaft in between. By doing so, the first step is a step of projecting the portion of the work corresponding to the protruding portion to the position of the protruding portion in the final target shape or a position outside the virtual extension surface from the position.
After the first step, the pressing force difference, which is the difference between the first pressing force and the second pressing force, is smaller than the pressing force difference in the first step, and the first pressing force is the second pressing force. The second step, which is a step of forming the contracted tube portion having the final target shape, by controlling the combination of the work angle and the offset and / or the pressing radius so as to be equal to or less than the pressure.
including,
A method for manufacturing a tubular member.
The method for manufacturing a tubular member according to claim 1.
At least a part of the plurality of paths of the processing tool in the first step is a non-contact path including a state in which the processing tool does not contact the work when the processing tool is on the protruding side. The combination of the work angle and the offset and / or the pressing radius is controlled so as to be.
A method for manufacturing a tubular member.
The method for manufacturing a tubular member according to claim 2.
In at least a part of the non-contact path, the machining tool presses the work when the machining tool is on the protruding side at the starting point which is at least the end of the path of the machining tool on the straight pipe portion side. As described above, the combination of the work angle and the offset and / or the pressing radius is controlled.
A method for manufacturing a tubular member.