WO2022244449A1

WO2022244449A1 - Spinning method

Info

Publication number: WO2022244449A1
Application number: PCT/JP2022/013229
Authority: WO
Inventors: 安浩小川; 尚志早川; 徹江口; 康貴渡辺
Original assignee: 株式会社三五
Priority date: 2021-05-19
Filing date: 2022-03-22
Publication date: 2022-11-24
Also published as: JPWO2022244449A1; JP7433523B2

Abstract

This spinning method integrally forms, by spinning a stock pipe, a tubular body which is a tubular member provided with a body section comprising an un-machined section of the stock pipe, a straight pipe-shaped distal end section formed at an end of the body section and having a different cross-sectional shape and/or size than the body section, and a gradually varied section formed between the body section and the distal end section, wherein: the revolution orbit of a forming tool in the spinning is circular, both in a first step for forming the gradually varied section at the end of a stock pipe and in a second step for forming the distal end section at the end of the gradually varied section on the side opposite the body section; and at least the first step includes a period in which the molding tool contacts only a section of the peripheral surface of the stock pipe, only in a part of the revolution orbit of the forming tool, by making the revolution axis of the molding tool and the axis of the stock pipe eccentric, such that only said section of the peripheral surface of the stock pipe is reduced in diameter. Due to this configuration, a spinning method is provided that reduces problems, such as buckling and/or unforeseen deformation, and that can handle various cross-sectional shapes, with high production efficiency.

Description

Spinning method

The present invention relates to a spinning processing method. Specifically, the present invention relates to a spinning method capable of dealing with various cross-sectional shapes with high manufacturing efficiency while reducing problems such as buckling and/or unintended deformation.

For example, a cylindrical housing that houses a device such as an exhaust purification device and/or a silencer for a vehicle equipped with an internal combustion engine is generally a body portion that is a cylindrical portion having a relatively large cross-sectional area. a tip portion which is a cylindrical portion having a relatively small cross-sectional area; and a cylindrical portion which is interposed between the main body portion and the tip portion and has a cross section which decreases from the main body side to the tip side. and a tapered portion. Depending on the application of such a device, for example, the cross-sectional shape of at least one of the body portion and the tip portion may be changed due to the requirements for the space in which the housing is installed and/or the flow of fluid (e.g., exhaust gas, etc.) inside the housing. Non-circular shapes (eg, ovals and ovals and polygons such as rectangles and triangles, etc.) may be required. Specific examples of the case where at least one of the body portion and the tip portion has a non-circular cross-sectional shape include: For example, the main body has a circular cross-sectional shape and the tip has a non-circular cross-sectional shape.

For example, while pressing the forming tool against the outer periphery of the end of a blank tube having an elliptical cross-sectional shape (elliptical tube), the blank tube is relatively rotated around the axis of rotation of the blank tube, and the forming tool is directed from the center side to the edge side of the blank tube. A method of forming a tapered portion having a circular cross-sectional shape that decreases in diameter from the center side to the edge side at the end of the raw pipe by moving it so as to approach the rotation axis of the raw pipe according to the method is known. . However, when the tapered portion is formed by such a method, a protrusion projecting in the minor axis direction is formed at the intersection of the outer periphery of the oval tube in the minor axis direction and the outer periphery of the tapered portion. interferes with other members.

Therefore, in Patent Document 1 (Japanese Patent No. 4647140), the generatrix of the tapered portion is recessed so that the inclination angle of the tapered portion with respect to the axis of the blank pipe gradually decreases from the center side to the edge side of the blank pipe. A molding method for forming a concave curve has been proposed. According to this, the height of the projection can be reduced.

However, in the above method, since the forming tool is relatively rotated around the rotation axis of the blank tube (between the ovals), buckling and/or unintended deformation may occur when the difference between the major diameter and the minor diameter of the elliptical tube is large. Such problems are likely to occur, and the processing limit is low. In particular, when using a blank tube having a small wall thickness, the problem becomes more pronounced. As a measure for avoiding such a problem, for example, in the spinning process, the forming tool is moved along a trajectory that continuously changes from the elliptical cross-sectional shape of the blank pipe to the elliptical cross-sectional shape of the tapered portion. It is conceivable to control the movement of However, it is difficult to increase the processing speed in spinning processing involving such complicated control, and there is a problem that the processing time becomes long.

Furthermore, in Patent Document 2 (Japanese Patent No. 4698890), after molding a deformed tube formed by forming a diameter-reduced portion at the end of the blank tube portion, the protrusion amount of the projecting portion is reduced by further spinning. Processing methods have been proposed. According to the processing method, the center line of revolution of the forming tool for spinning processing with respect to the deformed tube is eccentric, and the forming tool is pressed into contact only with the projecting portion located on the opposite side of the eccentric direction. The protrusion amount of the protrusion can be reduced. However, performing the secondary processing after forming the deformed pipe as described above may lead to problems such as a decrease in manufacturing efficiency of the deformed pipe and an increase in manufacturing cost.

In addition, in Patent Document 3 (Japanese Patent No. 6748992), a cushioning member and a catalyst carrier are press-fitted into the main body of a cylindrical body having a non-circular curved cross section, and at least one end of the cylindrical body is subjected to spinning processing. In the manufacturing method of the catalytic converter, the buffer member and the catalyst carrier are press-fitted into the main body portion of the tubular body while the main body portion of the tubular body is held by the clamp member, and the tubular body is held while being held by the clamp member. It has been proposed to form a tapered portion by performing a spinning process on at least one end of the . According to this, it is possible to reduce the occurrence of protrusions and/or unintended deformation as described above at least for the main body. However, from the viewpoint of reducing problems such as a decrease in manufacturing efficiency and an increase in manufacturing cost, a technique that does not require a step of holding the main body using an additional member such as a clamp member is more desirable. Needless to say.

Japanese Patent No. 4647140 Japanese Patent No. 4698890 Japanese Patent No. 6748992 Japanese Patent No. 6630300

As described above, in the technical field, there is a demand for a spinning method that can handle various cross-sectional shapes with high manufacturing efficiency while reducing problems such as buckling and/or unintended deformation.

Therefore, as a result of intensive research, the inventors of the present invention found that the period during which the forming tool is brought into contact with only a part of the peripheral surface of the blank pipe only in a part of the revolution orbit of the forming tool that rotates along the circular revolution orbit in the spinning process. It has been found that the above problems can be solved by providing

Specifically, the spinning method according to the present invention (hereinafter sometimes referred to as the "method of the present invention") is a cylindrical member having a body portion, a tip portion, and a gradually changing portion. This is a spinning method for integrally forming a shaped body from a blank pipe by spinning. The body portion is a portion of the unprocessed region of the blank pipe. The tip is a straight tubular portion formed at the end of the body and having a cross section different in shape and/or size from the cross section of the body. The gradually changing portion is formed between the body portion and the tip portion, and has a cross-sectional shape that changes from the cross-sectional shape of the main body portion to the cross-sectional shape of the tip portion as it goes from the end portion on the side of the body portion to the end portion on the side of the tip portion. It is a cylindrical portion that changes and communicates the internal space of the main body and the internal space of the distal end. The method of the present invention comprises a first step of forming a gradually changing portion at the end of the blank tube and a second step of forming a tip portion at the end of the gradually changing portion opposite to the main body. include.

Furthermore, in both the first step and the second step, the orbit of the forming tool in the spinning process is circular. Additionally, at least the first step includes a partial spinning period during which the partial spinning process is performed. In the partial spinning process, the revolution axis of the forming tool and the axis of the blank pipe are eccentrically arranged so that the forming tool contacts only a part of the peripheral surface of the blank pipe in only a part of the revolution orbit of the forming tool. It is a spinning process that reduces the diameter of only a part of the circumference of the pipe.

The cross-sectional shape of the main body can be one shape selected from the group consisting of circular, elliptical, oval, rectangular and triangular. The cross-sectional shape of the tip can also be any one shape selected from the group consisting of circular, elliptical, oval and polygonal. The cross-sectional shape of the main body and the cross-sectional shape of the tip may be the same or different. Also, the relative positional relationship between the axis of the main body portion and the axis of the tip portion can be any one selected from the group consisting of coaxial, eccentric, inclined, and spatial geometric twist positions.

As described above, in the method of the present invention, it is possible to reduce the diameter of only a part of the peripheral surface of the blank tube by the above-described partial spinning process. Therefore, according to the method of the present invention, even when the difference between the major diameter and the minor diameter of the blank tube is large, various cross-sectional shapes can be obtained while reducing problems such as buckling and/or unintended deformation. Gradually changing portions and tip portions having a wide variety of cross-sectional shapes can be easily formed from the blank tube.

Furthermore, in both the first step and the second step included in the method of the present invention, the orbit of the forming tool in the spinning process is circular. That is, the cross-section of the gradually changing portion that changes from the cross-sectional shape of the blank tube to the cross-sectional shape of the tip portion as in the above-described conventional spinning method (hereinafter sometimes referred to as the "conventional method"). There is no need to complicatedly control the movement of the forming tool so as to follow the shape. Therefore, according to the method of the present invention, the processing speed can be increased and the processing time can be shortened.

In addition, in the method of the present invention, unlike the conventional method described above, there is no need to perform secondary processing after forming the cylindrical body or to use additional members to hold the main body. Therefore, according to the method of the present invention, problems such as a decrease in production efficiency and an increase in production cost can be reduced.

Other objects, features and attendant advantages of the present invention will be easily understood from the description of each embodiment of the present invention described with reference to the following drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram showing a blank pipe used in one specific example of the spinning method (first method) according to the first embodiment of the present invention and a cylindrical body formed from the blank pipe. 1. It is a schematic diagram which illustrates the outline|summary of the process which a cylindrical body is shape|molded by a 1st method from the blank pipe illustrated in FIG. 1. It is a schematic diagram which illustrates the detail of the process which a cylindrical body is shape|molded by a 1st method from the blank pipe illustrated in FIG. FIG. 4 is a schematic diagram showing a blank pipe used in another specific example of the first method and a cylindrical body formed from the blank pipe. FIG. 5 is a schematic diagram illustrating an outline of a process of forming a cylindrical body from the blank tube illustrated in FIG. 4 by a first method; FIG. 5 is a schematic diagram showing a blank pipe used in one specific example of the spinning method (second method) according to the second embodiment of the present invention and a cylindrical body formed from the blank pipe. FIG. 4 is a schematic diagram showing a blank pipe used in another specific example of the second method and a cylindrical body formed from the blank pipe. FIG. 10 is a schematic diagram showing a blank tube used in yet another specific example of the second method and a cylindrical body formed from the blank tube. FIG. 10 is a schematic diagram showing a blank pipe used in one specific example of the spinning method (third method) according to the third embodiment of the present invention and a tubular body formed from the blank pipe. In the first step included in the third method for forming a cylindrical body from a blank tube illustrated in FIG. FIG. 10 is a schematic diagram showing a process of eccentrically moving the axis of the distal end portion with respect to the axis of the main body portion. FIG. 10 is a schematic diagram showing a blank pipe used in another specific example of the third method and a cylindrical body formed from the blank pipe. FIG. 10 is a schematic diagram showing a blank pipe used in yet another specific example of the third method and a cylindrical body formed from the blank pipe. FIG. 10 is a schematic diagram showing a blank pipe used in yet another specific example of the third method and a cylindrical body formed from the blank pipe. FIG. 10 is a schematic diagram showing a blank pipe used in yet another specific example of the third method and a cylindrical body formed from the blank pipe. FIG. 5 is a schematic diagram illustrating the details of the process of forming a cylindrical body from the blank tube illustrated in FIG. 4 by the method of the present invention; FIG. 7 is a schematic diagram illustrating the details of the process of forming a cylindrical body from the blank tube illustrated in FIG. 6 by the method of the present invention. FIG. 8 is a schematic diagram illustrating the details of the process of forming a cylindrical body from the blank tube illustrated in FIG. 7 by the method of the present invention; FIG. 9 is a schematic diagram illustrating the details of the process of forming a cylindrical body from the blank pipe illustrated in FIG. 8 by the method of the present invention; FIG. 10 is a schematic diagram illustrating the details of the process of forming a cylindrical body from the blank tube illustrated in FIG. 9 by the method of the present invention; FIG. 12 is a schematic diagram illustrating the details of the process of forming a cylindrical body from the blank pipe illustrated in FIG. 11 by the method of the present invention; FIG. 13 is a schematic diagram illustrating the details of the process of forming a tubular body from the blank tube illustrated in FIG. 12 by the method of the present invention; FIG. 4 is a schematic diagram showing an example of a cylindrical body formed by a combination of the processing method disclosed in Patent Document 4 and the method of the present invention.

<<1st Embodiment>>
A spinning method according to a first embodiment of the present invention (hereinafter sometimes referred to as "first method") will be described below with reference to the drawings.

The first method is a spinning method in which a tubular body, which is a tubular member having a main body portion, a tip portion, and a gradually changing portion, is integrally formed from a blank pipe by spinning. The material forming the blank pipe is not particularly limited as long as it can be formed into a desired shape by spinning. Specific examples of such materials include metal materials such as stainless steel. The details of the spinning process are well known to those skilled in the art, and will not be described here.

The body portion is the portion other than the tip portion and the gradually changing portion of the cylindrical body, and is typically the portion consisting of the unprocessed region of the blank tube. The tip is a straight tubular portion formed at the end of the body and having a cross section different in shape and/or size from the cross section of the body. That is, in the cylindrical body formed by the first method, the cross-sectional shape of the tip portion and the cross-sectional shape of the body portion are different, the cross-sectional area of the tip portion and the cross-sectional area of the body portion are different, or The cross-sectional shape of the tip is different from the cross-sectional shape of the main body, and the cross-sectional area of the tip is different from the cross-sectional area of the main body. Specific examples of various combinations of the cross section of the tip portion and the cross section of the body portion in the cylindrical body molded by the first method will be described in detail later.

The gradually changing portion is formed between the body portion and the tip portion, and has a cross-sectional shape that changes from the cross-sectional shape of the main body portion to the cross-sectional shape of the tip portion as it goes from the end portion on the side of the body portion to the end portion on the side of the tip portion. It is a cylindrical portion that changes and communicates the internal space of the main body and the internal space of the distal end. Typically, the gradually changing portion is a tapered diameter-reduced portion whose cross-sectional area gradually decreases from the end on the main body side toward the end on the tip side. However, the cross section of the gradually changing portion does not necessarily have to be reduced in diameter over the entire circumference, and may include a portion that is not reduced in diameter and/or a portion that is increased in diameter. Further, the rate of change of the cross-sectional shape from the main body side to the tip side end toward the tip side end is not necessarily constant or uniform. For example, the rate of change may vary along the axial direction of the gradually changing portion, or may vary along the axis of the gradually changing portion.

The first method includes a first step of forming a gradually changing portion at the end of the blank tube and a second step of forming a tip portion at the end of the gradually changing portion opposite to the main body. include. As described above, the first method is a spinning method for integrally forming a tubular body, which is a tubular member having a main body portion, a tip end portion, and a gradually changing portion, from a blank tube by spinning. Therefore, in the first step, the gradually changing portion is integrally formed at the end of the blank tube by spinning, and in the second step, the gradually changing portion is formed at the end opposite to the main body portion by spinning. are integrally formed.

Furthermore, in both the first step and the second step, the orbit of the forming tool in the spinning process is circular. That is, in the first method, the cross-sectional shape of the gradually changing portion that changes from the cross-sectional shape of the main body (base tube) to the cross-sectional shape of the tip portion as in the above-described conventional spinning method (conventional method). There is no need for complicated control of the movement of the forming tool to follow. Therefore, according to the first method, the machining speed can be increased and the machining time can be shortened.

In addition, at least the first step includes a partial spinning period during which partial spinning is performed. In the partial spinning process, the axis of revolution of the forming tool such as a roller or spatula and the axis of the blank pipe are made eccentric, so that the forming tool is moved to a part of the peripheral surface of the blank pipe only in a part of the revolution orbit of the forming tool. It is a spinning process that reduces the diameter of only a part of the peripheral surface of the mother tube by contacting the chisel. That is, in the first method, it is possible to reduce the diameter of only a part of the peripheral surface of the mother pipe by partial spinning. Therefore, even when the difference between the long diameter and the short diameter of the raw pipe is large, various problems such as buckling and/or unintended deformation can be reduced, and a wide variety of raw pipes (main parts) having various cross-sectional shapes can be obtained. Gradual change portions and tip portions having various cross-sectional shapes can be easily molded.

Furthermore, unlike the conventional method described above, there is no need to perform secondary processing after molding the cylindrical body or to hold the main body using additional members. Therefore, according to the first method, problems such as a decrease in manufacturing efficiency and an increase in manufacturing cost can be reduced.

Here, some specific examples of the first method will be described in detail with reference to the drawings. FIG. 1 is a schematic diagram showing a blank pipe used in one specific example of the first method and a cylindrical body formed from the blank pipe. (a) is a front view of the tube 11 viewed from the direction of the central axis AX, in which the major axis AL and the minor axis AS in the elliptical cross section are indicated by two-dot chain lines. (b) is a left side view of the base pipe 11 when viewed from the direction of the short axis AS, and the central axis AX passing through the center of the elliptical cross section is indicated by a chain double-dashed line.

On the other hand, (c) is a front view of the cylindrical body 21 formed from the blank tube 11 by the first method when observed from the direction of the central axis AX, and (d) is a front view of the cylindrical body 21 formed from the short axis AS. It is a left side view when observed from the direction. In (c) and (d), the major axis AL and minor axis AS of the elliptical cross section and the central axis AX passing through the center of the elliptical cross section are indicated by two-dot chain lines, respectively. As illustrated in (c) and (d), the tubular body 21 is a tubular member including a body portion 21a, a tip portion 21b, and a gradually changing portion 21c.

The body portion 21a is a portion other than the tip portion 21b and the gradually changing portion 21c of the cylindrical body 21, and is a portion of the unprocessed region of the blank pipe 11. The tip portion 21b is formed at the opposite end of the body portion 21a of the gradually changing portion 21c formed at the end of the body portion 21a, and has a smaller diameter than the minor axis of the elliptical cross section of the body portion 21a. It is a straight tubular section with a circular cross-section having a The gradually changing portion 21c is formed between the main body portion 21a and the tip portion 21b, and gradually changes from the elliptical cross-sectional shape of the main body portion 21a to the tip as it goes from the end on the side of the main body portion 21a to the end on the side of the tip portion 21b. It is a cylindrical portion whose cross-sectional shape changes to the circular cross-sectional shape of the portion 21b and communicates the internal space of the main body portion 21a and the internal space of the tip portion 21b. That is, in this case, it is necessary to process the end portion of the blank tube 11 having an elliptical cross-sectional shape by the first method to form a straight pipe-like tip portion 21b having a smaller circular cross-sectional shape.

Next, the process of forming the cylindrical body 21 from the blank tube 11 by the first method will be described. In the following description, the raw tube, the cylindrical body, and the intermediate body in the process of being formed from the raw tube into the cylindrical body may be collectively referred to as "work". FIG. 2 is a schematic diagram illustrating an overview of the process of forming the cylindrical body 21 from the blank tube 11 illustrated in FIG. 1 by the first method. (a), (c), and (e) are front views of the work when observed from the axial direction, and the long and short axes of the elliptical cross section of the work are indicated by two-dot chain lines, respectively (however, , symbols AL and AS omitted). (b), (d) and (f) are left side views of the workpiece when observed from the minor axis direction, and the central axis passing through the center of the elliptical cross section is indicated by a two-dot chain line (however, , the symbol AX is omitted).

In FIG. 2, the shapes of the blank tube 11, the cylindrical body 21, and the intermediate body (workpiece) in the process of being molded from the blank tube 11 to the cylindrical body 21 are drawn by thick solid lines, and the shapes of the blank tube 11 and the cylindrical body 21 are drawn by thick solid lines. A roller 41 as a forming tool in the spinning process is drawn by a thin solid line. In the example shown in FIG. 2, the two rollers 41 are arranged at positions facing each other across the revolution axis, but the number of forming tools in the spinning process executed in the first method is limited to two. There may be one, or three or more.

Furthermore, the revolution orbit Tc of the center (rotation axis) of the roller 41 and the revolution orbit Te of the innermost end of the roller 41 are drawn by a dashed line and a dashed line, respectively. As described above, in the first method, the first step, which is the step of forming the gradually changing portion 21c at the end of the blank pipe 11, and the tip portion at the end of the gradually changing portion 21c opposite to the main body portion 21a. The orbits Tc and Te of the forming tool (workpiece 41) in the spinning process are circular in any of the second steps, which are steps for forming 21b.

As described above, in the first method, first, the first step, which is the step of forming the gradually changing portion 21c at the end of the blank pipe 11, is performed. In the example shown in FIG. 2, first, as illustrated in (a) and (b), the blank pipe 11 is rotated by rollers 41 (see solid curved arrows shown in the figure) rotating along a circular revolution orbit. The peripheral surface of the tube 11 near both ends of the major axis of the elliptical cross section (hereinafter sometimes referred to as "long axis side peripheral surface") is pressed to reduce the diameter. As a result, the cross-sectional shape of the portion of the workpiece that eventually becomes the tip portion 21b and the reduced diameter portion 21c is longer than the cross-sectional shape of the blank tube 11 (and the main body portion 21a), as illustrated in (c). It becomes a shape compressed (diameter-reduced) in the axial direction. Henceforth, the process of pressing the long-axis side peripheral surface of a workpiece|work with a forming tool and diameter-reducing it may be called a "1st step."

Note that the first step may be executed by one pass of the roller 41 or may be executed by multiple passes. Alternatively, the next step may be performed after the first step is repeatedly executed a plurality of times. Furthermore, in the first step illustrated in FIGS. 2A and 2B, the elliptical shape of the blank tube 11 is formed by so-called "coaxial spinning" in which the central axis of the blank tube 11 and the revolution axis of the roller 41 are aligned. Both peripheral surfaces (two major axis side peripheral surfaces) of the tube 11 near both ends of the major axis of the cross section of the shape were simultaneously pressed to reduce the diameter. However, as will be described later in detail, even in the first step, the central axis of the blank tube 11 and the revolution axis of the roller 41 are eccentrically arranged so that the blank tube near both ends of the major axis of the elliptical cross section of the blank tube 11 is The two peripheral surfaces (two major axis side peripheral surfaces) of 11 may be individually pressed to reduce the diameter.

Next, as exemplified in (c), the central axis of the tube 11 and the revolution axis of the roller 41 are eccentrically (offset) (see the solid line arrows shown in the drawing) to perform so-called "eccentric spinning." By executing "processing", one of the peripheral surfaces of the workpiece near both ends of the short axis of the elliptical cross section of the blank tube 11 (hereinafter sometimes referred to as "short axis side peripheral surface") is pressed. to reduce the diameter. As a result, the hatched portion in (d) of the peripheral surface of the work is formed into a shape along the orbit of the roller 41 . Furthermore, although not illustrated in FIG. 2, by eccentrically (offsetting) the central axis of the tube 11 and the revolution axis of the roller 41 to the opposite side and executing the "eccentric spinning process" in the same manner as described above, The other peripheral surface of the work near both ends of the minor axis of the elliptical cross section of the blank tube 11 (minor axis side peripheral surface) is also shaped along the revolution orbit of the roller 41 in the same manner as described above. Hereinafter, the process of reducing the diameter of the work by pressing the short axis side peripheral surface of the work with a forming tool by eccentric spinning may be referred to as a "second step".

In each of the above-mentioned "eccentric spinning processes", by eccentrically rotating the revolution axis of the roller 41 as a forming tool and the axis of the blank tube 11, the roller 41 is rotated only in a part of the revolution track Te at the innermost end of the roller 41. 41 is brought into contact with only part of the peripheral surface of the blank pipe 11 to reduce the diameter of only part of the peripheral surface of the blank pipe 11 . That is, the "eccentric spinning process" corresponds to the "partial spinning process" described above, and the period during which the "eccentric spinning process" is performed corresponds to the "partial spinning period" described above.

However, as illustrated in FIG. 1, the tip portion 21b provided in the cylindrical body 21 formed from the blank tube 11 having an elliptical cross-sectional shape in the first method illustrated in FIG. A straight tubular portion having a circular cross section with a diameter smaller than the minor axis of the elliptical cross section of the main body portion 21a, which is formed at the end of the gradually changing portion 21c opposite to the main body portion 21a. be. Therefore, at some point during the first step, which is the step of forming the gradually changing portion 21c at the end of the blank tube 11, the innermost revolving orbit Te of the roller 41 is reached in both the first step and the second step. is smaller than the minor axis of the elliptical cross section of the body portion 21a. After this time point, by performing normal spinning processing in which the roller 41 is in contact with the entire circumference of the workpiece, the cross-sectional shape of the gradually changing portion 21c matches the cross-sectional shape and size of the tip portion 21b. One step can be continued.

As described above, in the first method, the partial spinning period, which is the period during which the partial spinning process is performed, does not necessarily occupy the entire period of the first step. In other words, the period during which the first step is executed should include the partial spinning period.

It should be noted that the eccentric spinning processing on the one and the other short shaft side peripheral surfaces in the second step may also be performed by one pass of the roller 41 or may be performed by multiple passes. Further, when the normal spinning process is performed after a certain point in the middle of the first step as described above, the normal spinning process may also be performed by one pass of the roller 41, or may be performed multiple times. may be executed by the path of Furthermore, after performing the first step, the second step may be repeatedly performed multiple times. The second step may be performed before the first step depending on the cross-sectional shape to be formed. Furthermore, by repeatedly performing a set of such first step and second step, the gradually changing portion 21c may be formed at the end portion of the blank tube 11 .

FIG. 3 is a schematic diagram illustrating the details of the process of forming the gradually changing portion 21c at the end portion of the blank tube 11 by repeatedly performing a set of the first step and the second step in the first step as described above. is. Note that reference numerals are omitted in FIG. 3 for the convenience of drawing space. (a) of FIG. 3 corresponds to (a) and (b) of FIG. 2, and (b) of FIG. 3 corresponds to (c) and (d) of FIG. In the example shown in FIG. 3, after the set of the first step and the second step is executed for the first time in (a) and (b), the first step and the second step are executed in (c) and (d) for the second time. A set of 2 steps is performed. Then, in (e) and (f), the first step is executed for the third time and the fourth time, respectively.

Next, in the first method, after the above-described first step, the second step of forming the tip portion 21b at the end of the gradually changing portion 21c opposite to the main body portion 21a is performed. The tip portion 21b of the cylindrical body 21 shown in FIGS. 1(c) and 1(d) is a cylindrical portion formed coaxially with the body portion 21a. Therefore, in the first method illustrated in FIG. 2, the tip portion 21b is formed at the end of the gradually changing portion 21c on the side opposite to the main portion 21a by performing the second step by a normal coaxial spinning process. be able to. This completes the molding of the cylindrical body 21 illustrated in FIGS. 1(c) and (d) and FIGS. 2(e) and (f). The spinning process performed in the second step may also be performed by one pass of the roller 41 or may be performed by multiple passes.

Another specific example of the first method will now be described in detail with reference to further drawings. FIG. 4 is a schematic diagram showing a blank pipe used in another specific example of the first method and a cylindrical body formed from the blank pipe. (a) is a front view of the tube 11 viewed from the direction of the central axis AX, in which the major axis AL and the minor axis AS in the elliptical cross section are indicated by two-dot chain lines. (b) is a left side view of the base pipe 11 when viewed from the direction of the short axis AS, and the central axis AX passing through the center of the elliptical cross section is indicated by a chain double-dashed line. The base pipe 11 illustrated in FIG. 4 is the same as the base pipe 11 illustrated in FIG.

On the other hand, (c) is a front view of the cylindrical body 22 formed from the blank pipe 11 by the first method when observed from the direction of the central axis AX, and (d) is a front view of the cylindrical body 22 formed from the short axis AS. It is a left side view when observed from the direction. In (c) and (d), the major axis AL and minor axis AS of the elliptical cross section and the central axis AX passing through the center of the elliptical cross section are indicated by two-dot chain lines, respectively. As illustrated in (c) and (d), the tubular body 22 is a tubular member including a body portion 22a, a tip portion 22b, and a gradually changing portion 22c.

The body portion 22a is a portion other than the tip portion 22b and the gradually changing portion 22c of the cylindrical body 22, and is a portion of the unprocessed region of the blank pipe 11. The tip portion 22b is formed at the end of the gradually changing portion 22c formed at the end of the body portion 22a, opposite to the body portion 22a, and is smaller than the major axis and the minor axis of the elliptical cross section of the body portion 22a. It is a straight tubular section with an elliptical cross-section having a major and minor axis respectively. The gradually changing portion 22c is formed between the body portion 22a and the tip portion 22b, and gradually changes from the elliptical cross-sectional shape of the body portion 22a to the tip as it goes from the end on the side of the body portion 22a to the end on the side of the tip portion 22b. It is a cylindrical portion whose cross-sectional shape is reduced to the elliptical cross-sectional shape of the portion 22b (that is, its diameter is reduced) and which communicates between the internal space of the main body portion 22a and the internal space of the tip portion 22b. That is, in this case, it is necessary to process the end portion of the blank pipe 11 having an elliptical cross-sectional shape by the first method to form a straight pipe-like tip portion 22b having a smaller elliptical cross-sectional shape.

Next, the process of forming the cylindrical body 22 from the blank pipe 11 by the first method will be described. FIG. 5 is a schematic diagram illustrating an overview of the process of forming the cylindrical body 22 from the blank tube 11 illustrated in FIG. 4 by the first method. Similar to FIG. 2 described above, (a), (c), and (e) are front views of the workpiece when observed from the axial direction, and the major axis and minor axis of the elliptical cross section of the workpiece are two points each. It is indicated by a dashed line (where the symbols AL and AS are omitted). (b), (d) and (f) are left side views of the workpiece when observed from the minor axis direction, and the central axis passing through the center of the elliptical cross section is indicated by a two-dot chain line (however, , the symbol AX is omitted).

As in FIG. 2 described above, in FIG. 5 as well, the shapes of the blank pipe 11, the cylindrical body 22, and the intermediate body (workpiece) in the process of being molded from the blank pipe 11 to the cylindrical body 22 are drawn by thick solid lines. , and a roller 41 as a forming tool in the spinning process performed in the first method is drawn by a thin solid line. Furthermore, the revolution track Tc of the center (rotation axis) of the roller 41 and the revolution track Te of the innermost end of the roller 41 are drawn by a dashed line and a broken line, respectively. In the first method illustrated in FIG. 5 as well, the orbits Tc and Te of the forming tool (workpiece 41) in the spinning process are circular in both the first step and the second step.

Also in the first method illustrated in FIG. 5, first, the first step, which is the step of forming the gradually changing portion 22c at the end portion of the blank pipe 11, is performed. Specifically, as exemplified in (a) and (b), first, the long axis of the blank tube 11 is rotated by the roller 41 rotating along the circular revolution track (see the solid curved arrow shown in the drawing). The side peripheral surface is pressed to reduce the diameter. As a result, the cross-sectional shape of the portion that eventually becomes the tip portion 22b and the reduced diameter portion 22c of the work is longer than the cross-sectional shape of the base pipe 11 (and the main body portion 22a), as illustrated in (c). It becomes a shape compressed (diameter-reduced) in the axial direction. That is, the first step described above is executed.

Next, as exemplified in (c), the central axis of the tube 11 and the revolution axis of the roller 41 are eccentrically (offset) (see the solid line arrows shown in the drawing) to perform so-called "eccentric spinning." By executing "processing", one of the peripheral surfaces of the tube 11 near both ends of the minor axis of the elliptical cross section of the tube 11 (hereinafter sometimes referred to as the "short axis side peripheral surface") is pressed to reduce the diameter. As a result, the hatched portion in (d) of the peripheral surface of the work is formed into a shape along the orbit of the roller 41 . Furthermore, although not shown, the central axis of the blank tube 11 and the revolution axis of the roller 41 are eccentrically (offset) to the opposite sides, and the "eccentric spinning process" is performed in the same manner as described above. The other peripheral surface (minor axis side peripheral surface) of the tube 11 near both ends of the minor axis of the elliptical cross section is also shaped along the revolution orbit of the roller 41 in the same manner as described above. That is, the above-described second step is executed. As described above, the "eccentric spinning process" corresponds to the "partial spinning process", and the period during which the "eccentric spinning process" is performed corresponds to the "partial spinning period".

In the first step, the cross-sectional shape of the end portion of the gradually changing portion 22c on the side opposite to the body portion 22a is changed to the cross-sectional shape of the tip portion 22b by repeatedly performing the above-described first step and second step a predetermined number of times. Continue until a match is found.

Next, in the first method, after the first step, the second step of forming the tip portion 22b at the end of the gradually changing portion 22c opposite to the main body portion 22a is performed. A tip portion 22b of the cylindrical body 22 illustrated in FIGS. 4(c) and 4(d) is an elliptical cylindrical portion formed coaxially with the main body portion 21a. Therefore, in the second step included in the first method illustrated in FIG. 5, while maintaining the cross-sectional shape and size, the first step and the second step are repeated a predetermined number of times as in the first step described above. Executed repeatedly.

As described above, in the first method, not only the first step but also the second step may include a partial spinning period during which the partial spinning process is performed.

4 and 5, like the first method illustrated in FIGS. 1 and 2, the second step may be performed after repeatedly performing the first step a plurality of times. , the second step may be repeatedly performed multiple times after the first step is performed. Further, each spinning process performed in the first step and the second step may be performed by one pass of the roller 41 or may be performed by multiple passes.

In the two specific examples of the first method described above, the cross-sectional shape of the main body of the tube and the cylindrical body is elliptical, and the cross-sectional shape of the tip of the cylindrical body is circular and elliptical. explained. However, the combination of the cross-sectional shape of the main body of the tube and the cylindrical body to which the first method is applied and the cross-sectional shape of the tip of the cylindrical body is not limited to the above, and a wide variety of combinations of cross-sectional shapes are possible. (details will be described later). Further, in the above-described two specific examples of the first method, the case where the axis of the body portion and the axis of the tip portion of the cylindrical body are coaxial has been described. However, the relative positional relationship between the axis of the main body portion and the axis of the distal end portion is not limited to the above, and various positional relationships are possible (details will be described later).

Furthermore, for example, when extremely high dimensional accuracy is required for the cylindrical body, for example, after the above-described first step and second step, pressing with a mold having a molding surface corresponding to the desired dimensional accuracy The first method may further include additional steps such as subjecting the tubular body to processing. In this case, the dimensions of the cylindrical body obtained by performing the first step and the second step may be slightly larger than the finally required dimensions of the cylindrical body.

In addition, the tip portion formed at the tip of the tubular body is generally used as a connecting portion between the tubular body and other members (for example, an exhaust pipe, etc.). Therefore, depending on the use of the cylindrical body, it may be necessary to process the tip portion in accordance with the member connected to the tip portion. In such a case, for example, the first method may further include an additional step of secondary processing the tip portion by, for example, cutting after the above-described first and second steps.

As described above, in the first method, only a portion of the peripheral surface of the blank pipe can be reduced in diameter by the partial spinning process described above. Therefore, according to the first method, even when the difference between the major diameter and the minor diameter of the blank pipe is large, various cross-sectional shapes can be obtained while reducing problems such as buckling and/or unintended deformation. Gradually changing portions and tip portions having a wide variety of cross-sectional shapes can be easily formed from the blank tube.

Furthermore, in both the first step and the second step included in the first method, the orbit of the forming tool in the spinning process is circular. That is, in the first method, it is necessary to control the movement of the forming tool in a complicated manner so as to follow the cross-sectional shape of the gradually changing portion, which changes from the cross-sectional shape of the blank tube to the cross-sectional shape of the tip portion, as in the conventional method described above. There is no Therefore, according to the first method, the machining speed can be increased and the machining time can be shortened.

In addition, in the first method, unlike the conventional method described above, there is no need to perform secondary processing after forming the cylindrical body or to hold the main body using additional members. Therefore, according to the first method, problems such as a decrease in manufacturing efficiency and an increase in manufacturing cost can be reduced.

<<Second embodiment>>
A spinning method according to a second embodiment of the present invention (hereinafter sometimes referred to as "second method") will be described below with reference to the drawings.

In the two specific examples of the first method described above, the case where the cross-sectional shape of the main body of the tube and the cylindrical body is elliptical and the cross-sectional shape of the tip of the cylindrical body is circular and elliptical will be described. did. However, the combination of the cross-sectional shape of the main body of the tube and the cylindrical body to which the first method is applied and the cross-sectional shape of the tip of the cylindrical body is not limited to the above, and a wide variety of combinations of cross-sectional shapes are possible. is.

Specifically, the cross-sectional shape of the main body can be any one shape selected from the group consisting of circular, elliptical, oval and polygonal. On the other hand, the cross-sectional shape of the tip can also be any one shape selected from the group consisting of circular, elliptical, oval and polygonal. Polygons, as used herein, include a wide variety of shapes such as triangles, quadrilaterals (eg, rectangles, parallelograms, rhombuses, trapezoids, etc.), pentagons, hexagons, heptagons and octagons. Also, these polygons do not necessarily have to be linearly symmetrical or rotationally symmetrical. The cross-sectional shape of the main body and the cross-sectional shape of the tip may be the same or different.

Therefore, the second method is the above-described first method, wherein the cross-sectional shape of the main body is any one selected from the group consisting of a circle, an ellipse, an oval and a polygon, and the cross-section of the tip is The spinning method is characterized in that the shape is one selected from the group consisting of a circle, an ellipse, an oval and a polygon.

The figures represented by the terms "circular", "elliptical", "oval" and "polygonal" used herein are not necessarily limited to figures that meet strict definitions, and are not necessarily limited to figures that meet the strict definition. Shapes represented by the terms "generally circular", "generally oval", "generally oval" and "generally polygonal" can also be included. Specifically, a circle includes not only a perfect circle but also a circle with a certain degree of dimensional error as long as it is recognized as a circle by those skilled in the art. The same is true for ellipses and ovals (also called "racetracks"). In addition, as long as a person skilled in the art recognizes a polygon, each side of a polygon does not necessarily have to be a perfect straight line. It does not have to be configured. For example, in the case of a rectangle, at least one of four sides may be formed by a gentle curve, and the angle at which adjacent sides intersect may not necessarily be 90 degrees. Rectangles also include, for example, rectangles with rounded corners and rectangles with chamfers. The same is true for other polygons such as triangles.

In the above description of the first method, as illustrated in (c) and (d) of FIG. As exemplified in (c) and (d), the cross-sectional shape of the body portion is elliptical and the cross-sectional shape of the tip portion is also elliptical. However, as illustrated in FIG. 6, the main body portion 23a may have a circular cross-sectional shape and the tip portion 23b may have an elliptical cross-sectional shape. Further, as illustrated in FIG. 7, the cross-sectional shape of the main body portion 24a may be rectangular (rectangular with rounded corners) and the cross-sectional shape of the tip portion 24b may be circular. Furthermore, as illustrated in FIG. 8, the cross-sectional shape of the body portion 25a may be rectangular (rectangle with rounded corners) and the cross-sectional shape of the tip portion 25b may be elliptical.

As described above, according to the second method, while enjoying the effects achieved by the above-described first method, the gradual change portion and the tip portion having various cross-sectional shapes can be obtained from the blank tube having various cross-sectional shapes. can be easily molded.

<<Third embodiment>>
Hereinafter, a spinning method according to a third embodiment of the present invention (hereinafter sometimes referred to as "third method") will be described with reference to the drawings.

In the two specific examples of the first method and the three specific examples of the second method described above, the case where the axis of the main body part and the axis of the tip part of the cylindrical body are coaxial has been described. However, the relative positional relationship between the axis of the main body portion and the axis of the distal end portion is not limited to the above, and various positional relationships are possible. Specifically, for example, the axis of the main body and the axis of the tip may be parallel to each other but may be offset (eccentric), and the axis of the main body and the axis of the tip may be in the same plane. or in a so-called "spatial geometric twist position" where the axis of the body and the axis of the tip are not parallel and do not intersect.

Therefore, the third method is the above-described first method or second method, wherein the relative positional relationship between the axis of the main body and the axis of the distal end is coaxial, eccentric, tilted, and spatial geometric torsion. The spinning method is characterized in that the position is any one selected from the group consisting of the positions of

Several examples of cylindrical bodies in which the relative positional relationship between the axis of the main body and the axis of the tip are not coaxial will be described below with reference to the drawings.

First, FIG. 9 is a schematic diagram showing a blank tube 11 used in one specific example of the third method and a tubular body 26 molded from the blank tube 11. FIG. The base pipe 11 illustrated in FIG. 9 is the same as the base pipe 11 illustrated in FIGS. On the other hand, in the cylindrical body 26 illustrated in FIG. 9, the axis of the tip portion 26b having a circular cross-section with respect to the axis of the body portion 26a having the same elliptical cross-section as that of the base pipe 11 is on the left side of the drawing. It has the same configuration as the cylindrical body 21 illustrated in FIG. 1 except that it is eccentric. Such eccentricity is due to the fact that in the first step, which is the step of forming the gradually changing portion 26b at the end of the tube 11 (the end of the main body portion 26a), the amount of diameter reduction of the work is more to the right than to the left as viewed in the drawing. can be achieved by setting the relative positional relationship between the revolution axis of the roller 41 and the axis of the workpiece in the partial spinning process so that

Specifically, the amount of eccentricity of the axis of the main body portion 26a of the work with respect to the revolution axis of the roller 41 in the second step executed in the first step is defined as the eccentric direction of the axis of the tip portion 26b with respect to the axis of the main body portion 26a. is relatively small with respect to the short shaft side peripheral surface on the same side as the main body portion 26a, and is relatively small with respect to the short shaft side peripheral surface on the side opposite to the eccentric direction of the shaft of the tip portion 26b with respect to the axis of the main body portion 26a. set to a large value. In addition, as illustrated in FIG. 10, in the first step of pressing the long axis side peripheral surface to reduce the diameter, the axis of the main body portion 26a of the work with respect to the revolution axis of the roller 41 ( It is eccentric in the direction opposite to the eccentric direction (of the axis of the distal end portion 26b) (see the straight arrow shown in the figure). As a result, the eccentricity is achieved in a desired direction and displacement, and the cross-sectional shape and position of the end portion of the gradually changing portion 26b on the distal end side (opposite side to the main body portion 26a) changes to the cross-sectional shape and position of the distal end portion 26b. It can be achieved by matching shape and position respectively.

Next, FIG. 11 is a schematic diagram showing a blank tube 11 used in another specific example of the third method and a cylindrical body 27 formed from the blank tube 11. As shown in FIG. The base pipe 11 illustrated in FIG. 11 is the same as the base pipe 11 illustrated in FIGS. On the other hand, in the cylindrical body 27 illustrated in FIG. 11, the axis of the tip portion 26b having a circular cross-sectional shape with respect to the axis of the main body portion 26a having the same elliptical cross-sectional shape as that of the base tube 11 is at the upper left as viewed in the drawing. It has the same configuration as the cylindrical body 21 illustrated in FIG. 1 and the cylindrical body 26 illustrated in FIG. 9 except that it is eccentric to the side. Such eccentricity is a step of forming a gradually changing portion 27b at the end of the base pipe 11 (the end of the main body portion 27a), as in the case of the cylindrical body 26 illustrated in FIGS. This can be achieved by appropriately setting the relative positional relationship between the revolution axis of the roller 41 and the axis of the workpiece in the partial spinning process executed in the first step (details will be described later).

Next, FIG. 12 is a schematic diagram showing the blank tube 13 used in yet another specific example of the third method and the cylindrical body 28 formed from the blank tube 13. As shown in FIG. The base pipe 13 illustrated in FIG. 12 is the same as the base pipe 13 illustrated in FIGS. On the other hand, in the cylindrical body 28 illustrated in FIG. It has the same configuration as the cylindrical body 24 illustrated in FIG. Such eccentricity is performed in the first step, which is a step of forming a gradually changing portion 28b at the end of the blank pipe 13 (the end of the main body portion 28a), as in the case of the cylindrical body 27 illustrated in FIG. can be achieved by appropriately setting the relative positional relationship between the revolution axis of the roller 41 and the axis of the work in the partial spinning process executed in (details will be described later).

In the above description of the third method, the case where the relative positional relationship between the axis of the main body and the axis of the tip of the cylindrical body is eccentric was exemplified. However, by applying a technique well known to those skilled in the art in spinning processing, the relative positional relationship between the axis of the main body of the cylindrical body and the axis of the tip can be coaxial, inclined or spatially geometrically twisted. Certain tubular bodies can also be easily formed by the third method.

For example, FIG. 13 shows a blank tube 13 used in a further specific example of the third method and a cylindrical body formed from the blank tube 13 and having an inclined axis of the main body 29a and the tip 29b. 29 is a schematic diagram showing 29. FIG. In the first step of forming the gradually changing portion 29c, such a cylindrical body 29 rotates the workpiece by a predetermined angle around an axis parallel to the short axis of the blank pipe 13 (that is, the short axis of the main body portion 29a). It can be shaped by performing spinning while rolling. On the other hand, FIG. 14 shows the blank tube 13 used in a further specific example of the third method and the relative positional relationship between the axis of the main body part 30a and the axis of the tip part 30b formed from the blank tube 13. FIG. 4 is a schematic diagram showing a tubular body 30 at a position of geometrical twist; In addition, FIG. 14(e) is a top view (top view) when the cylindrical body 30 is observed from above in the direction of the long axis AL.

In addition, the relative positional relationship between the axis of the main body and the axis of the tip can be any one selected from the group consisting of coaxial, inclined and spatial geometric twist positions. The procedure is well known to those skilled in the art and will not be described in detail here.

Further, the tubular body can be molded by the third method regardless of whether the cross-sectional shape of the main body portion and the cross-sectional shape of the tip portion of the tubular body are the same shape or different shapes. When the relative positional relationship between the axis of the main body and the axis of the tip is coaxial and the cross-sectional shape of the main body and the cross-sectional shape of the tip are both circular, the cylindrical body is formed by a normal spinning process. can be molded, but such a cylindrical body may be molded by a third method.

As described above, according to the third method, the relative positional relationship between the axis of the main body portion and the axis of the tip portion is maintained while enjoying the effects achieved by the above-described first method and/or the second method. A cylindrical body that is any one selected from the group consisting of coaxial, eccentric, inclined and spatial geometric twist positions can be easily formed.

Various embodiments of the spinning method (method of the present invention) according to the present invention, including the first to third methods described above, will be described below with reference to the drawings. However, the various embodiments described below are merely examples. The specific configuration of the method of the present invention (for example, the number and order of the first step and the second step performed in the first step, the number of passes of the forming tool in the first step and the second step, etc.) It can be appropriately determined according to the shape of the cylindrical body to be molded by the method.

(1) Coaxial Spinning Processing from Elliptical Shape to Circular Shape Cylindrical body 21 having circular cross-sectional shape and tip end portion 21b located coaxially with main body portion 21a is formed from raw tube 11 having elliptical cross-sectional shape. Since the method of the present invention has already been described with reference to FIGS. 1 to 3, description thereof will be omitted here.

(2) Coaxial Spinning Processing from Elliptical to Elliptical The method of the present invention for molding from has already been described with reference to FIGS. However, since FIG. 5 is a schematic diagram illustrating an overview of the process of forming the cylindrical body 22 from the blank pipe 11 illustrated in FIG. 4, the details of the forming process will be described again here.

FIG. 15 is a schematic diagram illustrating the details of the process of forming the cylindrical body 22 from the blank tube 11 illustrated in FIG. 4 by the first method. Also in FIG. 15 and FIGS. 16 to 21 which will be referred to later, reference numerals are omitted for convenience of drawing space, as in FIG. In addition, in FIG. 15 and FIGS. 16 to 21 to be referred to later, the vertical direction toward the drawing is the long axis direction of the portion having the irregular cross section, and the horizontal direction toward the drawing is the short axis direction of the portion having the irregular cross section. axial direction. That is, the upper and lower circumferential surfaces of the work as viewed in the drawing are the long axis side circumferential surfaces, and the left and right circumferential surfaces of the work as viewed in the drawing are the short axis side circumferential surfaces.

(a) of FIG. 15 corresponds to (a) and (b) of FIG. 5, and (b) of FIG. 15 corresponds to (c) and (d) of FIG. In the example shown in FIG. 15, after the set of the first step and the second step is executed for the first time in (a) and (b), the first step and the second step are executed for the second time in (c) and (d). A set of 2 steps is performed. Then, in (e) and (f), the third and fourth sets of the first step and the second step are executed. As a result, the cross-sectional shape of the end portion of the gradually changing portion 22c on the distal end side (the side opposite to the main body portion 22a) can be the same cross-sectional shape as the cross-sectional shape of the distal end portion 22b having an elliptical cross-sectional shape. That is, the molding of the gradually changing portion 22c is completed, and the first step ends.

Next, the second step, which is a step of forming the tip portion 22b at the tip end of the gradually changing portion 22c, is performed. A distal end portion 22b of the cylindrical body 22 illustrated in FIGS. 4(c) and 4(d) is an elliptical cylindrical portion formed coaxially with the main body portion 22a. Therefore, in the second step, while maintaining the shape and size of the cross section, the first step and the second step are repeatedly performed a predetermined number of times in the same manner as in the first step described above, and the distal end portion 22b is formed. . This completes the molding of the cylindrical body 22 illustrated in FIGS. 4(c) and (d) and FIGS. 5(e) and (f).

(3) Coaxial Spinning Processing from Circular to Elliptical A cylindrical body 23 having an elliptical cross-sectional shape and a tip portion 23b located coaxially with the body portion 23a is formed from the blank tube 12 having a circular cross-sectional shape. The method according to the invention has already been described with reference to FIG. However, since the details of the process of forming the cylindrical body 23 from the blank pipe 12 illustrated in FIG. 6 are not described, the details of the forming process will be described here.

FIG. 16 is a schematic diagram illustrating the details of the process of forming the cylindrical body 23 from the blank tube 12 illustrated in FIG. 6 by the method of the present invention. First, in (a) and (b), the second step is executed twice consecutively. Specifically, in (a), the first partial spinning process is applied to the short axis side peripheral surface of the blank tube 12 having a circular cross-sectional shape. Next, in (b), the short axis side peripheral surface of the workpiece is subjected to a second partial spinning process. Next, in (c) and (d), a set of first and second steps is performed. Specifically, in (c), the long axis side peripheral surface of the work is partially spun, and in (d), the short axis side peripheral surface of the work is partially spun.

Next, in (e) and (f), the set of the first step and the second step is performed one more time, and in (g) and (h), the set of the first step and the second step is performed one more time. times. Finally, in (i) the last first step is performed. As a result, the cross-sectional shape of the end portion of the gradually changing portion 23c on the distal end side (the side opposite to the main body portion 23a) can be the same cross-sectional shape as the cross-sectional shape of the distal end portion 23b having an elliptical cross-sectional shape. That is, the molding of the gradually changing portion 23c is completed, and the first step ends.

Next, a second step is performed, which is a step of forming the tip portion 23b at the tip end of the gradually changing portion 23c. A tip portion 23b of the cylindrical body 23 illustrated in FIGS. 6(c) and 6(d) is an elliptical cylindrical portion formed coaxially with the main body portion 23a. Therefore, in the second step, while maintaining the shape and size of the cross section, the first step and the second step are repeatedly performed a predetermined number of times in the same manner as in the first step described above, and the tip portion 23b is formed. . This completes the molding of the tubular body 23 illustrated in FIGS. 6(c) and 6(d) and FIG. 16(j).

(4) Coaxial Spinning Processing from Rectangle (Rounded Rectangle) to Circular Shape The cylindrical body 24 having a circular cross-sectional shape and having a tip portion 24b located coaxially with the main body portion 24a is formed into a rectangular (rounded rectangular) cross section. The method of the present invention for forming from a shaped blank 13 has already been described with reference to FIG. However, since the details of the process of forming the cylindrical body 24 from the blank tube 13 illustrated in FIG. 7 are not described, the details of the forming process will be described here.

FIG. 17 is a schematic diagram illustrating the details of the process of forming the cylindrical body 24 from the blank tube 13 illustrated in FIG. 7 by the method of the present invention. First, in (a) and (b), a set of the second step and the first step is executed for the first time. Specifically, in (a), the first partial spinning process is applied to the short-axis side peripheral surface of the blank tube 13 having a rectangular cross-sectional shape. However, at this stage, the corners of the rectangular cross-section are located on the outermost side from the center axis in the cross section of the blank tube 13, so the corners are partially spun. Next, in (b), a first partial spinning process is applied to the long axis side peripheral surface of the work.

Similarly, in (c) and (d), the second set of the second step and the first step is executed. As a result, the rollers come into contact with not only the corners of the workpiece but also the areas near both ends of the minor axis of the peripheral surface on the side of the minor axis. Next, in (e) and (f), a set of the second step and the first step is executed for the third time. As a result, at this point in the middle of the first step, which is the step of forming the gradually changing portion 24c at the end portion of the blank tube 13, the diameter of the revolution orbit at the innermost end of the roller becomes smaller than the rectangular cross section of the main body portion 24a. smaller than the dimension in the axial direction (short side). After this point, as illustrated in (g) and (h), normal coaxial spinning processing is performed in which the rollers are in contact with the entire circumference of the work, thereby obtaining the cross-sectional shape and size of the gradually changing portion 24c. matches the cross-sectional shape and size of tip 24b. Thereby, the molding of the gradually changing portion 24c is completed, and the first step ends.

Next, a second step is performed, which is a step of forming the distal end portion 24b at the distal end portion of the gradually changing portion 24c. A tip portion 24b provided in the cylindrical body 24 illustrated in FIGS. 7(c) and 7(d) is a cylindrical portion formed coaxially with the main body portion 24a. Therefore, in the second step, a normal coaxial spinning process is performed while maintaining the cross-sectional shape and size to form the tip portion 24b. This completes the molding of the cylindrical body 24 illustrated in FIGS. 7(c) and (d) and FIG. 17(i).
(5) Coaxial Spinning Process from Rectangle (Rounded Rectangle) to Ellipse The cylindrical body 25 having an elliptical cross-sectional shape and having a tip portion 25b located coaxially with the body portion 25a is formed into a rectangle (rounded rectangle). The method of the present invention for forming from a blank tube 13 having a cross-sectional shape of .lambda. has already been described with reference to FIG. However, since the details of the process of forming the cylindrical body 25 from the blank pipe 13 illustrated in FIG. 8 are not described, the details of the forming process will be described here.

FIG. 18 is a schematic diagram illustrating the details of the process of forming the cylindrical body 25 from the blank tube 13 illustrated in FIG. 8 by the method of the present invention. First, in (a) and (b), a set of the second step and the first step is executed for the first time. Specifically, in (a), the first partial spinning process is applied to the short-axis side peripheral surface of the blank tube 13 having a rectangular cross-sectional shape. In this case also, as in the example shown in FIG. 17, at this stage, the outermost portion from the central axis in the cross section of the blank tube 13 is the corner of the rectangular cross section, so partial spinning is not possible. It will be applied to the corners. Next, in (b), a first partial spinning process is applied to the long axis side peripheral surface of the work.

Similarly, in (c) and (d), the second set of the second step and the first step is executed. In this example, when the pair of the second step and the first step is executed for the second time, the rollers are not only in the corners of the workpiece but also in the regions near both ends of the minor axis of the peripheral surface on the minor axis side. come into contact. Then, the set of the first step and the second step is executed for the third time in (e) and (f), and the set of the first step and the second step is executed for the fourth time in (g) and (h). be done. As a result, the cross-sectional shape of the gradually changing portion 25c matches the cross-sectional shape and size of the distal end portion 25b. That is, the molding of the gradually changing portion 25c is completed, and the first step ends.

Next, the second step, which is a step of forming the distal end portion 25b at the distal end portion of the gradually changing portion 25c, is performed. A distal end portion 245 of the cylindrical body 25 shown in FIGS. 8(c) and 8(d) is an elliptical cylindrical portion formed coaxially with the main body portion 25a. Therefore, in the second step, while maintaining the shape and size of the cross section, the first step and the second step are repeatedly performed a predetermined number of times in the same manner as in the first step described above, and the distal end portion 25b is formed. . This completes the molding of the cylindrical body 25 illustrated in FIGS. 8(c) and 8(d).

(6) Eccentric Spinning Process from Elliptical Shape to Circular Shape In the above-mentioned (1) to (5), the method of the present invention for forming a cylindrical body having a tip portion located coaxially with the main body portion has been described. . In the description from (6) onwards, the method of the present invention for molding a cylindrical body in which the relative positional relationship between the axis of the body portion and the axis of the tip portion is eccentric will be described.

A method of the present invention for forming a cylindrical body 26 having a circular cross-sectional shape and a front end portion 26b eccentric to the left side of the drawing with respect to a main body portion 26a from a blank tube 11 having an elliptical cross-sectional shape. has already been described with reference to FIGS. However, FIG. 10 shows the main body relative to the revolution axis of the forming tool not only in the second step but also in the first step in the first step included in the method of the present invention for forming a tubular body from a blank tube illustrated in FIG. Since it is a schematic diagram illustrating the outline of the process of eccentrically moving the axis of the tip portion with respect to the axis of the body portion by eccentrically moving the axis of the portion, the details of the molding process will be described here again.

FIG. 19 is a schematic diagram illustrating the details of the process of forming the cylindrical body 26 from the blank pipe 11 illustrated in FIG. 9 by the method of the present invention. In the example shown in FIG. 19, after the set of the first step and the second step is executed for the first time in (a) and (b), the first step and the second step are executed for the second time in (c) and (d). A set with the second step is performed. Then, in (e) and (f), the set of the first step and the second step is executed for the third time. At this time, the amount of eccentricity of the axis of the body portion 26a of the work with respect to the revolution axis of the roller in the second step is set in the direction opposite to the eccentricity direction (left side in the drawing) of the axis of the tip portion 26b with respect to the axis of the body portion 26a. The side (right side as viewed in the drawing) is set relatively large with respect to the short axis side peripheral surface, and the same side as the eccentric direction of the shaft of the tip portion 26b with respect to the shaft of the main body portion 26a (left side as viewed in the drawing). is set relatively small with respect to the short axis side peripheral surface of (see the straight arrow shown in the figure). As a result, the center of the cross section of the work is shifted leftward as viewed in the drawing.

Next, in (g), the first step is executed for the fourth time. The shape is circular (having a diameter greater than that of tip 26b). After this point, as illustrated in (h), the rollers can contact the entire circumference of the work, so that by performing normal eccentric spinning processing, the cross-sectional shape and The first step is continued until the size matches the cross-sectional shape and size of the tip 26b (ie, a circular cross-sectional shape having the same diameter as the cross-sectional shape of the tip 26b). Thereby, the molding of the gradually changing portion 26c is completed, and the first step ends.

In the example shown in FIG. 19, in the second step executed for the third time as described above, the axis of the body portion 26a of the work is eccentric with respect to the revolution axis of the roller. Depending on the shape of the portion 26c, the axis of the body portion 26a of the workpiece may be eccentric with respect to the revolution axis of the roller in the second step executed before the second time. Further, as illustrated in FIG. 10, in the first step of pressing the long shaft side peripheral surface to reduce the diameter, the axis of the main body portion 26a of the work with respect to the revolution axis of the roller (the tip portion 26b with respect to the axis of the main body portion 26a) It may be eccentric in the direction opposite to the direction of eccentricity of the shaft.

Next, a second step is performed, which is a step of forming the tip portion 26b at the end portion of the gradually changing portion 26c opposite to the main body portion 26a. A tip portion 26b of the cylindrical body 26 illustrated in FIGS. 10(c) and 10(d) is a cylindrical portion having an axis parallel to the axis of the body portion 26a. Therefore, in the second step, the tip portion 26b can be formed at the end of the gradually changing portion 26c opposite to the main body portion 26a by normal spinning processing without further eccentricity. This completes the molding of the cylindrical body 26 illustrated in FIGS. 9(c) and (d) and FIG. 10(c).

(7) Eccentric Spinning Processing from Elliptical to Circular A cylindrical body 27 having a circular cross-sectional shape and having a distal end portion 27b eccentric to the upper left side of the drawing with respect to the body portion 27a is formed into an elliptical shape. The method of the present invention for forming from a blank tube 11 having a cross-sectional shape has already been described with reference to FIG. However, since the details of the process of forming the cylindrical body 27 from the blank pipe 11 illustrated in FIG. 11 are not described, the details of the forming process will be described here.

As described above, the base pipe 11 illustrated in FIG. 11 is the same as the base pipe 11 illustrated in FIGS. 1, 4, 9 and 10. On the other hand, in the cylindrical body 27 illustrated in FIG. 11, the axis of the tip portion 26b having a circular cross-sectional shape with respect to the axis of the main body portion 26a having the same elliptical cross-sectional shape as that of the base tube 11 is at the upper left as viewed in the drawing. It has the same configuration as the cylindrical body 21 illustrated in FIG. 1 and the cylindrical body 26 illustrated in FIG. 9 except that it is eccentric to the side.

FIG. 20 is a schematic diagram illustrating the details of the process of forming the cylindrical body 27 from the blank tube 11 illustrated in FIG. 11 by the method of the present invention. In the example shown in FIG. 20, after the set of the first step and the second step is executed for the first time in (a) and (b), the first step and the second step are executed in (c) and (d) for the second time. A set with the second step is performed. At this time, in the first step executed in (c), the axis of the main body 27a of the work is eccentric downward in the drawing with respect to the revolution axis of the roller (straight arrow shown in the drawing). ). As a result, the center of the cross-section of the workpiece is eccentric upward in the drawing. Next, in the second step executed in (d), the axis of the main body portion 27a of the work relative to the revolution axis of the roller is eccentric downward as viewed in the drawing, and eccentric in the horizontal direction as viewed in the drawing. The amount is set so that the amount of eccentricity toward the right side of the drawing is greater than the amount of eccentricity toward the left side (see the two straight arrows shown in each drawing). As a result, the center of the cross section of the work is decentered to the upper left side as viewed in the drawing.

Then, in (e) and (f), the first step is executed for the third and fourth times, respectively. At this time, in both (e) and (f), the axis of the main body portion 27a of the work is eccentric to the lower right side of the drawing with respect to the revolution axis of the roller (in each drawing, see the two straight arrows shown). As a result, the center of the cross section of the workpiece is further eccentric to the upper left side of the drawing. At this point, the workpiece has a circular cross-sectional shape (having a diameter greater than that of tip 27b). After this point, as shown in (g), the roller can be in contact with the entire circumference of the workpiece, so that the cross-sectional shape of the gradually changing portion 27c and the The first step is continued until the size matches the cross-sectional shape and size of the tip 27b (ie, a circular cross-sectional shape with the same diameter as the cross-sectional shape of the tip 27b). Thereby, the molding of the gradually changing portion 27c is completed, and the first step ends.

Next, a second step is performed, which is a step of forming the tip portion 27b at the end portion of the gradually changing portion 27c opposite to the main body portion 27a. A tip portion 27b provided in the tubular body 27 illustrated in FIGS. 11(c) and 11(d) is a cylindrical portion having an axis parallel to the axis of the main body portion 27a. Therefore, in the second step, the leading end portion 27b can be formed at the end portion of the gradually changing portion 27c opposite to the main body portion 27a by normal spinning processing without further eccentricity. This completes the molding of the cylindrical body 27 illustrated in FIGS. 11(c) and (d) and FIG. 20(h).

(8) Eccentric Spinning from a Rectangle (Rounded Rectangle) to a Circle Cylindrical body 28 having a circular cross-sectional shape and having a tip portion 28b that is eccentric to the upper left side of the drawing with respect to the body portion 28a. has already been described with reference to FIG. However, since the details of the process of forming the cylindrical body 28 from the blank tube 13 illustrated in FIG. 15 are not described, the details of the forming process will be described here.

As described above, the base pipe 13 illustrated in FIG. 12 is the same as the base pipe 13 illustrated in FIGS. On the other hand, in the tubular body 28 illustrated in FIG. It has the same configuration as the cylindrical body 24 illustrated in FIG.

FIG. 21 is a schematic diagram illustrating the details of the process of forming the cylindrical body 28 from the blank tube 13 illustrated in FIG. 12 by the method of the present invention. First, in (a) and (b), a set of the second step and the first step is executed for the first time. Similar to the molding process of the cylindrical body 24 illustrated in FIG. 7 explained with reference to FIG. Therefore, the partial spinning process for the short shaft side peripheral surface is applied to the corners. Next, in (b), a first partial spinning process is applied to the long axis side peripheral surface of the work. At this time, the axis of the body portion 28a of the work is eccentric to the lower side and the right side of the drawing with respect to the revolution axis of the roller (see the two straight arrows shown in each drawing). As a result, the center of the cross section of the work is decentered to the upper left side as viewed in the drawing.

Next, in (c) and (d), the second set of the second step and the first step is executed. At this time, in the second step executed for the second time in (c), the axis of the main body portion 28a of the work relative to the revolution axis of the roller is eccentrically lowered as viewed in the drawing, and in the horizontal direction as viewed in the drawing. , is set so that the amount of eccentricity toward the right side of the drawing is greater than the amount of eccentricity toward the left side (see the two straight arrows shown in each figure). As a result, the center of the cross section of the workpiece is further eccentric to the upper left side of the drawing. In the second first step executed in (d), the axis of the main body portion 28a of the work with respect to the revolution axis of the roller is significantly greater than the first step executed in (b). It is eccentric to the bottom and to the right as viewed in the drawing (see the two straight arrows shown in each drawing). After that, in the set of the third second step and the first step executed in (e) and (f), the axis of the main body 28a of the work with respect to the revolution axis of the roller It is decentered further to the right (see the two straight arrows shown in each figure). As a result, the center of the cross section of the workpiece is further eccentric to the upper left side of the drawing.

After this point, as shown in (g) and (h), the rollers can contact the entire circumference of the workpiece, so that the gradually changing portion 28c can be matches the cross-sectional shape and size of tip 28b (ie, a circular cross-sectional shape having the same diameter as the cross-sectional shape of tip 28b). Thereby, the molding of the gradually changing portion 28c is completed, and the first step ends.

Next, the second step, which is a step of forming the tip portion 28b at the tip end of the gradually changing portion 28c, is performed. A tip portion 28b of the cylindrical body 28 shown in FIGS. 12(c) and 12(d) is a cylindrical portion having an axis parallel to the axis of the main body portion 28a. Therefore, in the second step, the tip portion 28b can be formed at the end of the gradually changing portion 28c opposite to the main body portion 28a by a normal spinning process without further eccentricity. This completes the molding of the tubular body 27 illustrated in FIGS. 12(c) and (d) and FIG. 21(i).

(9) Supplementary information In the above description, the case where the relative positional relationship between the axis of the main body of the cylindrical body and the axis of the distal end is eccentric has been exemplified. However, by applying a technique well known to those skilled in the art in spinning processing, the relative positional relationship between the axis of the main body of the cylindrical body and the axis of the tip can be coaxial, inclined or spatially geometrically twisted. A certain tubular body can also be easily formed by the spinning method according to the present invention (the method of the present invention).

Further, for example, in the case where extremely high dimensional accuracy is required for the cylindrical body, as described above, for example, after the above-described first step and second step, a molding surface corresponding to the desired dimensional accuracy is formed. The method of the present invention may further include an additional step of applying the cylindrical body to press working with a mold having a mold. In this case, the dimensions of the cylindrical body obtained by performing the first step and the second step may be slightly larger than the finally required dimensions of the cylindrical body. In addition, depending on the use of the cylindrical body, for example, after the above-described first step and second step, for example, the tip portion is cut to match the member connected to the tip portion (for example, an exhaust pipe, etc.) The method of the present invention may further include additional steps such as fabricating the .

Furthermore, depending on the application of the cylindrical body, there are cases where further processing is required at locations other than the tip of the cylindrical body. Specifically, for example, it may be necessary to accurately form a bearing surface in the gradually changing portion of the cylindrical body or to perforate the bearing surface. In such cases, for example, the processing method disclosed in Patent Document 4 (Japanese Patent No. 6630300) may be combined with the method of the present invention. Specifically, an open core metal is inserted into at least one of the open ends on both ends of the cylindrical body molded by the method of the present invention to support and restrain, and at least a part of the gradually changing portion is not supported or restrained. After forming the seat surface by pressing the seat pressing punch against a predetermined area of the gradually changing portion, a hole punch may be punched in a predetermined area within the outer edge of the seat surface.

FIG. 22 is a schematic diagram showing an example of a cylindrical body formed by a combination of the processing method disclosed in Patent Document 4 and the method of the present invention. A cylindrical body 31 illustrated in FIG. 22 includes a body portion 31a, a tip portion 31b, and a gradually changing portion 31c, similarly to the cylindrical body 26 illustrated in FIGS. 31d and a through hole 31e formed in the gradually changing portion 31c by the processing method disclosed in . As exemplified in FIG. 22, according to the above combination, in addition to the effects achieved by the method of the present invention, it is possible to precisely form the bearing surface and perforate the gradually changing portion of the cylindrical body. The bearing surface and the through hole can be formed with high dimensional accuracy in the gradually changing portion of the cylindrical body having various cross-sectional shapes.

In the description so far, the first step of reducing the diameter by pressing the long axis side peripheral surface of the work with the forming tool and the second step of reducing the diameter by pressing the short axis side peripheral surface of the work with the forming tool. were both performed in the first step. However, for example, the gradually changing portion and the tip end have a circumference equal to the circumference of the base pipe (that is, the circumference of the main body) and have a cross-sectional shape that is different from the cross-sectional shape of the base pipe (that is, the cross-sectional shape of the main body). When molding a cylindrical body having portions, it is not always necessary to perform both the first step and the second step in the first step.

Although several embodiments and examples having specific configurations have been described above for the purpose of illustrating the present invention, sometimes with reference to the accompanying drawings, the scope of the present invention is not limited to these exemplary embodiments. It should not be construed as being limited to the embodiments and examples, and it goes without saying that modifications can be made as appropriate within the scope of the claims and the matters described in the specification.

11, 12, 13...

Element tube

21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31...

Cylindrical body

21a, 22a, 23a, 24a, 25a, 26a, 27a, 28a, 29a . , 31c... Gradual change part 41... Roller (former)
AL...Long axis of cross section AS...Short axis of cross section AX...Center axis passing through center of cross section Tc...Revolution track of roller center (rotation axis) Te...Revolution track of innermost end of roller

Claims

A main body portion composed of an unprocessed portion of a blank tube, and a tip portion formed at the end of the main body portion and being a straight pipe portion having a cross section different in shape and/or size from the cross section of the main body portion. , which is formed between the main body portion and the tip portion and has a cross-sectional shape that changes from the cross-sectional shape of the main body portion to the cross-sectional shape of the tip portion as it goes from the end portion on the side of the main body portion to the end portion on the side of the tip portion. A cylindrical body, which is a cylindrical member having a gradually changing portion which is a cylindrical portion whose shape changes and communicates between the inner space of the main body portion and the inner space of the tip portion, is spun. A spinning method for integrally forming a tube,
A first step, which is a step of forming the gradually changing portion at the end portion of the blank tube, and a second step, which is a step of forming the tip portion at the end portion of the gradually changing portion opposite to the main body portion. In any case, the orbit of the forming tool in the spinning process is circular,
In at least the first step, by eccentrically moving the axis of revolution of the forming tool and the axis of the blank tube, the forming tool is moved to a portion of the peripheral surface of the blank tube only in part of the revolution orbit of the forming tool. Including a partial spinning period, which is a period during which a partial spinning process, which is a spinning process that reduces the diameter of only the part of the peripheral surface of the mother pipe by contacting only the part,
A spinning processing method characterized by:
A spinning processing method according to claim 1,
The cross-sectional shape of the main body is any one shape selected from the group consisting of a circle, an ellipse, an oval and a polygon,
The cross-sectional shape of the tip is any one shape selected from the group consisting of a circle, an ellipse, an oval and a polygon,
A spinning processing method characterized by:
The spinning method according to claim 1 or claim 2,
The relative positional relationship between the axis of the body portion and the axis of the tip portion is any one selected from the group consisting of coaxial, eccentric, inclined and spatial geometric twist positions,
A spinning processing method characterized by: