JP2005152982A - Method for manufacturing outer ring member for constant velocity joint - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing an outer ring member for a constant velocity joint capable of enhancing the machining accuracy with the substantially uniform dimension of an end face thereof in the axial direction. <P>SOLUTION: In this method, a forward extrusion (S1) is performed on a work, and a preliminary upset is performed on the work to form a primary shaped article (S2). By upsetting an upper portion of the primary shaped article, an intermediate preliminary shaped article having an annular inclined surface with the flow resistance difference between a large diameter portion and a small diameter portion (S3). By performing backward extrusion on the intermediate preliminary shaped article, a quaternary shaped article having a cup part with a track groove formed therein is formed (S4), and the cup part of the quaternary shaped article is ironed for the finish to the product dimension (S5). <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing an outer ring member for a constant velocity joint that constitutes a constant velocity joint for transmitting rotational driving force.

  Conventionally, forging materials are loaded into cavities formed in an upper die and a lower die joined to each other, and pressure is applied to the forging material via a punch, for example, for driving wheels of automobiles. An outer ring member (outer cup) of a constant velocity joint is manufactured.

  The outer ring member is composed of a cylindrical cup portion and a shaft portion formed integrally with the cup portion, and three inner circumferential surfaces of the cup portion extend along the axial direction. A track groove is formed, and a roller is provided to roll along the track groove.

  With regard to a method for manufacturing an outer ring member for this type of constant velocity joint, for example, Patent Document 1 discloses that when a material for a cup-shaped outer member having a substantially uniform wall thickness is applied to a product shape dimension, In order to solve the problem that the large-diameter portion is small and the small-diameter portion is large in the amount of elongation in the direction, the amount of elongation in the axial direction is reduced by setting the dimensions of the cup-shaped outer member material according to the constant volume rule. The technical idea to make it constant is disclosed.

  In Patent Document 2, a cup-shaped crude product with a shaft having substantially the same shape as the finished shape is formed on the inner surface by forging, and then an inner mold is set on the inner surface of the crude product. In order to make the ironing rate of each part of the uniform thickness part, uniform thin part, and change part from thick to thin uniform, the entire circumference of the outer surface part is applied toward the inner surface part. The technical idea of finishing a plurality of grooves on the inner surface with high accuracy is disclosed.

JP 57-206537 A Japanese Patent Laid-Open No. 61-3618

  However, in the technical idea disclosed in Patent Document 1, since the ironing rate of the bottom portion of the track groove, the track groove, and the inner surface portion is greatly different, the bottom portion, the track groove, and the inner surface portion of the track groove are uniform. There is a problem that the accuracy of the groove surface of the track groove is inferior compared with the case where ironing is performed at the ironing rate.

  In addition, the technical idea disclosed in Patent Document 2 is based on the premise that a cup-shaped crude product with a shaft having a shape substantially the same as the finished shape on the inner surface is used as a forging material (workpiece). Yes. Therefore, for example, the manufacturing method disclosed in Patent Document 2 was applied using a cup-shaped intermediate material having a difference in wall thickness between the large-diameter portion and the small-diameter portion by subjecting the billet to backward extrusion. In this case, due to the difference in the ironing rate, the axial extension of the thin part is larger than that of the thick part, and the intermediate material whose original end face in the axial direction is uneven is ironed with a uniform ironing ratio all around the circumference. However, the end face after ironing is still uneven, and there is a problem that the amount of finishing for the end face in the axial direction increases.

  The present invention has been made to solve the above-described problems. When backward extrusion is performed, an end face in the axial direction can be obtained by causing more plastic material to flow in the large diameter portion than in the small diameter portion of the forging material. It is an object of the present invention to provide a method for manufacturing an outer ring member for a constant velocity joint that can improve the processing accuracy by making the dimensions substantially uniform.

In order to achieve the above object, the present invention is a method of manufacturing an outer ring member for a tripod type constant velocity joint in which a shaft portion and a cup portion are integrally formed by cold forging,
Forming a primary molded body having a shaft portion by subjecting a cylindrical workpiece cut to a predetermined length to forward extrusion; and
Forming a secondary molded body by performing pre-upsetting on the upper part excluding the shaft portion of the workpiece;
An intermediate in which an annular inclined surface having a flow resistance difference is formed between the large-diameter portion and the small-diameter portion by further upsetting the upper portion excluding the shaft portion of the secondary molded body. Forming a preform, and
Forming a fourth molded body having a cup portion provided with track grooves by subjecting the intermediate preform to backward extrusion;
Performing ironing on the cup portion of the fourth molded body;
It is characterized by having.

  In this case, the intermediate preform has a disk-shaped head that is thinner and larger in diameter than the upper part of the secondary molded body, and the head has a radially outward direction when viewed from the plane. It is preferable that a plurality of large-diameter portions protruding toward the surface and having a predetermined separation angle along the circumferential direction and a plurality of small-diameter portions formed to be curved and recessed between the adjacent large-diameter portions are provided.

  Furthermore, an annular inclined surface whose inclination angle with respect to a horizontal plane continuously changes along the circumferential direction may be formed on the upper surface of the head. At that time, by setting the inclination angle β of the small diameter portion larger than the inclination angle α of the large diameter portion, when the rear extrusion molding is performed on the intermediate preform in the next step, the large diameter portion and the small diameter portion The amount of plastic flow with respect to the rear can be made different in correspondence with the difference in flow resistance between the two.

  According to the present invention, during the step of forming the outer ring member for a constant velocity joint by a plurality of cold forging forming, the intermediate preliminary in which the annular inclined surface having a flow resistance difference between the large diameter portion and the small diameter portion is formed. A molded body is formed.

  For example, the inclination angle α of the large diameter portion on the annular inclined surface formed in the intermediate preform is set smaller than the inclination angle β of the small diameter portion, and the flow resistance difference between the large diameter portion and the small diameter portion is set. Provided. Therefore, when the intermediate preform is subjected to backward extrusion molding in the next step, the plastic flow amount differs between the large diameter portion and the small diameter portion corresponding to the flow resistance difference, and the large diameter portion The meat flow is better than that of the small diameter portion.

  In addition, it is preferable that the angle difference of the inclination angle β of the small diameter portion with respect to the inclination angle α of the large diameter portion is set to 3 degrees or more and 12 degrees or less.

  According to the present invention, the intermediate molded body has a shape in which a large amount of meat flows more easily in the large diameter portion than in the small diameter portion, so that the cup between the large diameter portion and the small diameter portion when rearward extrusion molding is performed. The dimension in the axial direction of the end face of the portion can be made substantially uniform.

  As a result, it is possible to prevent uneven machining with respect to the fourth molded body obtained by the backward extrusion molding and to make the plastic flow of the large diameter part better than that of the small diameter part, thereby suppressing the finishing cost and finishing. As a result, the amount of cutting can be reduced.

  Hereinafter, preferred embodiments of the method for manufacturing an outer ring member for a constant velocity joint according to the present invention will be described in detail with reference to the accompanying drawings.

  In the method for manufacturing the outer ring member for a constant velocity joint according to the present embodiment, as shown in the flowchart of FIG. 1, a total of five cold forging processes are performed on the workpiece 10 made of a carbon steel cylinder. Finally, an outer ring member for a tripod type constant velocity joint is manufactured.

  2 to 7 show a method for manufacturing an outer ring member for a constant velocity joint according to the present embodiment.

  First, in the first preparation step, spheroidizing annealing is performed on the workpiece 10 (see FIG. 2) cut into a predetermined length of a cylindrical body. Thereby, the workpiece | work 10 is softened and the following 1st-5th cold forging processes become easy.

  In the second preparation step, the chemical conversion coating for lubrication is formed on the workpiece 10. That is, by forming a lubricating chemical conversion film made of, for example, zinc phosphate or the like on the surface of the workpiece 10 by bonderite treatment, lubricity is imparted to the surface. Specifically, the chemical conversion coating for lubrication may be formed by immersing the workpiece 10 in a solvent in which zinc phosphate or the like is dissolved for a predetermined time.

  Next, in the first cold forging step S1, forward extrusion molding is performed on the workpiece 10 on which the chemical conversion coating for lubrication is formed. That is, the work 10 is loaded into a work holding part of a first forging die having a shaft forming cavity (not shown). The shaft portion forming cavity is formed to have a smaller diameter than the workpiece 10, and a tapered surface is provided between the shaft portion forming cavity and the work holding portion.

  In this state, one end surface of the workpiece 10 is pressed toward the shaft portion forming cavity. By this pressing, the other end surface side of the workpiece 10 is press-fitted into the shaft portion forming cavity, and as a result, a primary diameter forming in which a reduced diameter portion 12 and a shaft portion 14 that are tapered in the other end surface side are formed. A product (primary molded body) 16 (see FIG. 3) is obtained. In addition, since the site | part loaded into the workpiece holding part in the workpiece | work 10 hardly deforms plastically, the primary molded product 16 has the upper part 18 of the dimension corresponding to the diameter of the workpiece | work 10. FIG.

  Next, preliminary upsetting is performed on the primary molded product 16 in the second cold forging step S2. That is, the primary molded product 16 is loaded into a cavity of a second forging die (not shown). At this time, the shaft portion 14 is inserted into a shaft portion holding portion provided in the second forging die.

  And while supporting the front-end | tip part of the axial part 14 inserted in the axial part holding | maintenance part with the pressing member which is not shown in figure, the upper part 18 of the primary molded product 16 is pressed and crushed with a punch. Along with this crushing, the upper portion 18 is compressed and expanded in diameter to obtain a secondary molded product (secondary molded product) 20 (see FIG. 4).

  Subsequently, in the third cold forging step S3, upset molding is performed to further compress and expand the diameter of the upper part 22 of the secondary molded product 20, and the intermediate preform 24 is formed as the tertiary molded product. (See FIG. 5 and FIG. 10).

  That is, by using the third forging die (preliminary molding die) 25 as shown in FIG. 8 and pressing the upper part 22 of the secondary molded product 20 loaded in the cavity 27 with the punch 29, An intermediate preform 24 (tertiary molded product) is obtained in which the upper part 22 of the secondary molded product 20 is compressed and deformed in the axial direction.

  As shown in FIG. 9, the center portion of the punch 29 is formed to be slightly recessed in a circular shape, and an annular shape rising from the circular recess toward the peripheral edge along the radially outward direction. An inclined surface molding portion 31 is formed, and the inclined surface molding portion 31 is configured so that the inclination angle of the inclined surface along the circumferential direction continuously changes corresponding to a first inclined surface portion and a second inclined surface portion described later. Is formed.

  As shown in FIGS. 5 and 10, the intermediate preform 24 includes a head portion 26 having a disk shape that is thinner and larger in diameter than the upper portion 22 of the secondary molded product 20, and the head portion 26. It is comprised from the axial part 14 formed by reducing in diameter integrally with the lower part side.

  The head portion 26 is adjacent to the large diameter portions 28a to 28c, which protrude from the radial direction by a predetermined length in the shape of three petals and have a separation angle of about 120 degrees along the circumferential direction when viewed from a plane. Three small-diameter portions 30a to 30c formed to be curved and recessed between the large-diameter portions 28a to 28c.

  On the upper surface of the head portion 26, an annular inclined surface 36 is formed between the circular ridge line 32 centering on the axis C and the peripheral edge ridge lines 34 of the large diameter portions 28a to 28c and the small diameter portions 30a to 30c. The annular inclined surface 36 is configured by an inclined surface that descends from the circular ridge line 32 on the center side toward the peripheral edge ridge line 34 in the radially outward direction, and includes the large diameter portions 28a to 28c and the small diameter portions 30a to 30c. It forms so that an inclination angle may each differ corresponding to a site | part.

  That is, the first inclined surface portions 38a to 38c that are formed at three locations connecting the center (axis C) and the central portions of the large diameter portions 28a to 28c are set to an inclination angle α of about 3 degrees with respect to the horizontal plane. On the other hand, the second inclined surface portions 40a to 40c including three portions connecting the center (axis C) and the central portion of the small diameter portions 30a to 30c are set to an inclination angle β of about 10 degrees with respect to the horizontal plane. Furthermore, between the 1st inclined surface part 38a-38c of the center part of the said large diameter parts 28a-28c and the 2nd inclined surface part 40a-40c of the center part of the said small diameter part 30a-30c, one 1st inclined surface part 38a. The inclination angle continuously changes (increases / decreases) in the circumferential direction from ˜38c (or second inclined surface portions 40a to 40c) toward the other second inclined surface portions 40a to 40c (or first inclined surface portions 38a to 38c). Is set to

  In other words, in the annular inclined surface 36 in which the inclination angle of the inclined surface (inclination angle with respect to the horizontal plane) continuously changes along the circumferential direction, the inclination of the central portion of the large diameter portions 28a to 28c connecting the center (axis C). The angle α is set to be the smallest, while the inclination angle β at the center of the small diameter portions 30a to 30c connecting the center (axis C) is set to be the largest.

  The inclination angle α at the center of the large diameter portions 28a to 28c and the inclination angle β at the center of the small diameter portions 30a to 30c are not limited to 3 degrees and 10 degrees, respectively. The inclination angle β is large (α <β), and the angle difference between the inclination angle α of the large diameter portions 28a to 28c and the inclination angle β of the small diameter portions 30a to 30c is set to 3 degrees or more and 12 degrees or less. Just do it. The inclination angle β of the small diameter portions 30a to 30c having a small flow resistance is set larger than the inclination angle α of the large diameter portions 28a to 28c having a large flow resistance, and the large diameter portions 28a to 28c and the small diameter portions 30a to 30c are A suitable flow resistance difference may be generated between the two.

  Next, FIG. 12 shows the experimental results when the angle difference with the inclination angle β of the small diameter portions 30a to 30c is changed when the inclination angle α of the large diameter portions 28a to 28c is set constant at 3 degrees. . In this experimental result, when the angle difference between the inclination angle α of the large-diameter portions 28a to 28c and the inclination angle β of the small-diameter portions 30a to 30c is set to 0 degree, there is a problem in entering the die in the next forging process. On the other hand, when the angle difference between the inclination angle α and the inclination angle β is 15 degrees, the large diameter portions 28a to 28c and the small diameter portion 30a Material cracking occurred at the stepped portion connecting 30c.

  Therefore, from the experimental results shown in FIG. 12, the angle difference between the inclination angle α of the large diameter portions 28a to 28c and the inclination angle β of the small diameter portions 30a to 30c is set to be 3 degrees or more and 12 degrees or less. The judgment result that it should just be obtained.

  Further, as shown in FIG. 5, the width of the annular inclined surface 36 in the radial direction is the widest at the central portion of the large diameter portions 28a to 28c and the narrowest at the central portion of the small diameter portions 30a to 30c. It is formed as follows.

  The primary molded product 16 and the secondary molded product 20 are formed symmetrically (line symmetric) with respect to the axes A and B, respectively, whereas the intermediate preform 24 that is a tertiary molded product. Then, it is formed so as to be asymmetric with respect to the axis C.

  Conventionally, in the finished product of the outer ring member for constant velocity joint, the outer periphery of the cup part was formed by a cylindrical surface, but from the need for weight reduction, the hollow part is formed in the cup part to reduce the weight. I am trying. In this case, by forming a recess in the cup portion, the shape becomes asymmetric with respect to the axis.

  After the completion of the third cold forging step S3, low temperature annealing for removing stress from the intermediate preform 24, shot blasting for removing oxide scales and the like generated during this low temperature annealing, and bondelite processing. A lubricating chemical conversion film made of zinc phosphate or the like is formed on the outer surface of the intermediate preform 24. This is because by performing these various treatments, the intermediate preform 24 (third molded product) can be easily plastically deformed.

  Thereafter, a fourth cold forging step S4 is performed using the fourth forging die 42 shown in FIG.

  The fourth forging die 42 has an upper die 44 and a lower die 46, and the upper die 44 and the lower die 46 are integrally joined by being fitted by an insert member (not shown). The lower die 46 is provided with a shaft insertion portion 48 for inserting the shaft portion 14 of the intermediate preform 24 (third molded product). A knockout pin 50 that can freely move up and down through a through hole is disposed vertically below the shaft insertion portion 48. A cup portion molding cavity 52 is provided on the inner wall of the upper die 44.

  A guide sleeve 56 made of a metal cylindrical body is fitted on the side peripheral wall portion of the punch 54 so that the punch 54 can be smoothly raised or lowered along the guide surface of the upper die 44.

  The outer peripheral surface of the punch 54 is provided with three protrusions (not shown) that are separated from each other by 120 degrees along the circumferential direction and extend by a predetermined length along the axial direction of the punch 54. As shown in FIG. 6, track grooves 60 a to 60 c are formed on the inner wall surface of the cup portion 8 of the fourth molded product 58 by these protrusions. The track grooves 60a to 60c are further improved in shape and dimensional accuracy by ironing the cup portion 62 in a fifth cold forging step S5 described later. (See FIG. 7) is formed.

  The punch 54 can be raised or lowered under the drive action of a mechanical press (not shown). In other words, a ram (not shown) of this mechanical press is connected to a lifting member (not shown) that is displaced along the vertical direction integrally with the ram. The punch 54 is fixed to the elevating member via a jig.

  The fourth cold forging process for the intermediate preform 24 (third molded product) in which the shaft portion 14 is inserted into the shaft insertion portion 48 of the fourth forging die 42 configured in this way, that is, Back extrusion is performed as follows.

  When the shaft portion 14 of the intermediate preform 24 is loaded along the shaft insertion portion 48 of the lower die 46, the cup portion forming cavity 52 formed on the inner wall of the upper die 44 and the large diameter portions 28a to 28a. Between the outer wall surface of the intermediate preformed body 24 including the 28c and the small diameter portions 30a to 30c, a uniform clearance is set along the circumferential direction with a predetermined interval (for example, 0.2 to 0.3 mm). .

  First, the elevating member connected to the ram of the mechanical press is lowered under the driving action of the mechanical press. Following this, the punch 54 descends and finally comes into contact with the upper surface of the head portion 26 of the intermediate preform (third molded product) 24.

  By further lowering the punch 54 and pressing the head portion 26 of the intermediate preform 24, the head portion 26 is plastically deformed. At that time, the large diameter portions 28 a to 28 c and the small diameter portions 30 a to 30 c of the intermediate preform 24 are controlled along the outer peripheral surface of the punch 54 while the plastic flow is restricted by the inner wall portion of the cup portion forming cavity 52. The cup portion 62 is formed by plastic flow toward the rear (upward) opposite to the descending direction.

  In this case, the large-diameter portions 28a to 28c are extended by plastic flow, so that the track grooves 60a to 60c directed in the axial direction of the intermediate preform 24 (third molded product) by the protrusions of the punch 54. Is formed on the inner wall surface of the cup portion 62.

  Thereafter, when the punch 54 is lifted together with the ram and the lifting member under the driving action of the mechanical press, and the knockout pin 50 is further lifted, the fourth molded product 58 shown in FIG. 6 is exposed.

  Normally, when backward forging is performed on a forging material, the rearward elongation amount (plastic flow amount) is smaller in the large diameter portion than in the small diameter portion. For example, the difference in deformation resistance (deformability) in the forging material Due to the above, there is a possibility that problems such as cracks and uneven thickness occur.

  Therefore, in the present embodiment, the inclination angle α of the large diameter portions 28a to 28c in the annular inclined surface 36 formed in the intermediate preform 24 is set smaller than the inclination angle β of the small diameter portions 30a to 30c, A flow resistance difference is provided between the large diameter portions 28a to 28c and the small diameter portions 30a to 30c. Corresponding to the difference in flow resistance, the amount of plastic flow between the large-diameter portions 28a to 28c and the small-diameter portions 30a to 30c at the time of rearward extrusion molding is made different so It was made to be better than 30c.

  Therefore, in the present embodiment, in the intermediate preform 24, a large amount of meat flows more easily in the large diameter portions 28a to 28c than in the small diameter portions 30a to 30c, so that the large size is obtained when the rear extrusion is performed. The dimension in the axial direction of the end surface of the cup portion 62 is substantially uniform between the diameter portions 28a to 28c and the small diameter portions 30a to 30c.

  As a result, in the present embodiment, finishing in the subsequent process is achieved by preventing uneven thickness with respect to the fourth molded product 58 obtained by the backward extrusion molding and improving the plastic flow of the large diameter portions 28a to 28c. The processing amount (cutting processing amount) can be suppressed.

  As described above, in the present embodiment, the intermediate preformed body 24 (third molded product) is formed in the subsequent process before the fourth cold forging process S4 in which the rear extrusion is performed. The accuracy of the finished product can be improved, and the amount of finishing work in the subsequent process can be reduced.

  After the fourth cold forging step S4 is performed, the fifth cold forging step S5 is performed on the fourth molded product 58. In addition, before performing 5th cold forging process S5, it is good to apply | coat a liquid lubricant to at least any one of the surface of the 4th molded product 58, or the 5th forging die (not shown). Thereby, it is possible to avoid the seizure of the fourth molded product 58 or the fifth forging die during the fifth cold forging step S5. As the liquid lubricant, a known liquid lubricant that has been conventionally used may be used.

  In the fifth cold forging process S5, a fifth forging die (not shown) is used to finish the cup portion 62 into a final product shape with respect to the inner surface and the outer surface of the fourth molded product 58. Ironing (final sizing) is performed. That is, the cup portion 62 is processed so that the thickness of the cup portion 62 and the width and depth of the track grooves 60a to 60c have a predetermined dimensional accuracy, thereby the dimensional accuracy of the cup portion 62 including the shape of the track grooves 60a to 60c and the like. Thus, an outer ring member for a tripod type constant velocity joint is obtained as a finished product 64 from which is issued (see FIG. 7).

  According to the manufacturing method according to the present embodiment, the flow resistance difference between the large-diameter portions 28a to 28b and the small-diameter portions 30a to 30b before performing the backward extrusion molding in the fourth cold forging step S4. By molding the intermediate preformed body 24 on which the annular inclined surface 36 that generates the above is formed, the product accuracy and quality stability of the finished product 64 can be improved.

It is a flowchart which shows the manufacturing process of the outer ring member for constant velocity joints which concerns on this Embodiment. It is the side view and top view of a workpiece | work which consist of a cylindrical body cut out by predetermined length. It is the side view and top view of the 1st molded product by which forward extrusion molding was made | formed with respect to the said workpiece | work. It is the side view and top view of the 2nd molded product in which preliminary upsetting was made | formed with respect to the said 1st molded product. It is the side view and top view of the intermediate | middle preformed body which were upset-molded with respect to the said secondary molded product. It is the side view and top view of the 4th molded product by which back extrusion molding was made | formed with respect to the said intermediate | middle preform. It is the side view and top view of the finished product of the outer ring member for tripod type | mold constant velocity joint by which ironing was made | formed with respect to the said 4th molded product. FIG. 5 is a partially omitted vertical sectional view of a third forging die for forming an intermediate preform. FIG. 9 is a partially cutaway side view and bottom view of a punch constituting the third forging die shown in FIG. 8. It is a perspective view of the intermediate preform. FIG. 10 is a partially omitted vertical cross-sectional view of a fourth forging die that performs backward extrusion molding on the intermediate preform. It is explanatory drawing which shows the experimental result at the time of making inclination-angle (alpha) of a large diameter part constant, and changing the inclination-angle (beta) of a small diameter part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Work 16 ... Primary molded product 20 ... Secondary molded product 24 ... Intermediate preform (3rd molded product)
25 ... 3rd forging die 28a-28c ... Large diameter part 29, 54 ... Punch 30a-30c ... Small diameter part 31 ... Inclined surface molding part 32 ... Circular ridge line 34 ... Peripheral part ridge line 36 ... Annular inclined surface 38a-38c ... 1st inclined surface part 40a, 40b ... 2nd inclined surface part 42 ... 4th metal mold | die for forging 58 ... 4th molded product 64 ... Finished product

Claims (4)

A method of manufacturing an outer ring member for a tripod type constant velocity joint in which a shaft portion and a cup portion are integrally formed by cold forging,
Forming a primary molded body having a shaft portion by subjecting a cylindrical workpiece cut to a predetermined length to forward extrusion; and
Forming a secondary molded body by performing pre-upsetting on the upper part excluding the shaft portion of the workpiece;
An intermediate in which an annular inclined surface having a flow resistance difference is formed between the large-diameter portion and the small-diameter portion by further upsetting the upper portion excluding the shaft portion of the secondary molded body. Forming a preform, and
Forming a fourth molded body having a cup portion provided with track grooves by subjecting the intermediate preform to backward extrusion;
Performing ironing on the cup portion of the fourth molded body;
The manufacturing method of the outer ring member for constant velocity joints characterized by having. In the manufacturing method of Claim 1,
The intermediate preform has a disk-shaped head that is thinner and larger in diameter than the upper part of the secondary molded body, and the head is directed radially outward when viewed from a plane. A plurality of large-diameter portions having a predetermined separation angle along the protruding circumferential direction and a plurality of small-diameter portions formed to be curved and recessed between the adjacent large-diameter portions are provided, etc. Manufacturing method of outer ring member for speed joint. In the manufacturing method of Claim 2,
The upper surface of the head is formed with an annular inclined surface in which the inclination angle with respect to the horizontal plane continuously changes along the circumferential direction, and the inclination angle β of the small diameter portion is set larger than the inclination angle α of the large diameter portion. Thus, when the backward extrusion molding is performed on the intermediate preform in the next step, the amount of plastic flow with respect to the rear differs depending on the difference in flow resistance between the large diameter portion and the small diameter portion. Manufacturing method of outer ring member for constant velocity joint. In the manufacturing method of Claim 3,
The method of manufacturing an outer ring member for a constant velocity joint, wherein an angle difference between an inclination angle β of the small diameter portion and an inclination angle α of the large diameter portion is set to 3 degrees or more and 12 degrees or less.

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