JP2006239735A - Method for producing outer ring member for constant velocity joint, and punch - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the durability of a punch by avoiding stress concentration developed to a specific portion of the punch caused by fluid action of the material when a track groove is formed by performing a backward extrusion-formation. <P>SOLUTION: When the backward extrusion-formation is applied with the punch 30 having three projecting parts 46 and recessing parts 48, separated at the same angle along the circular direction and extended along the axial line direction, one pair of tapered surfaces 38a, 38b connected with a first to third rectangular inclining surfaces 36a-36c formed at the tip end part of the projecting part 46 of the punch 30 abutted on a head parts of a secondary forming product and inclined at a prescribed angle along the circular direction to the first to third rectangular inclining surfaces 36a-36c, are arranged. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a manufacturing method of a tripod type constant velocity joint outer ring member that constitutes a constant velocity joint for transmitting a rotational driving force, and a punch used in the manufacturing method.

  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, the present applicant is able to omit the fourth step, which is ironing processing (final sizing molding) to finish the final product shape. And a forging method have been proposed (see Patent Document 1).

  That is, in the cold forging method according to the prior art, as shown below, the outer ring member is forged by sequentially performing the first step to the fourth step. The fourth step of the cold forging method can be omitted.

  First, a cylindrical work piece (forging material) connected to a predetermined length is subjected to a spheroidizing annealing treatment, and subsequently a lubricating chemical coating such as a phosphate coating is formed on the surface by a bonderite treatment. A shaft portion extending along the axial direction is formed by performing forward extrusion with the first forging die (first step).

  Next, a second step of performing upsetting on the unprocessed portion of the workpiece via another second forging die different from the first forging die is performed. And, for the molded product that has been subjected to upsetting, a low temperature annealing treatment for removing stress, a shot blasting treatment for removing oxide scale, etc. generated during the low temperature annealing treatment, and an outer surface of the workpiece Bonderite treatment for forming a chemical conversion coating for lubrication is performed.

  Subsequently, a third step is performed on the workpiece, in which a cup portion is formed and backward extrusion is performed to form a ball groove or a roller groove on the inner peripheral surface thereof. This backward extrusion molding is performed by another third forging die different from the first and second forging dies. The molded product subjected to the backward extrusion molding is subjected to a low-temperature annealing process to soften the workpiece, and then the oxide scale and the like are removed by shot blasting, and further, bonderite processing is performed to obtain lubricity at the time of molding. .

  Finally, the ironing process (final sizing molding) for finishing to the final product shape is performed as the fourth step by using another fourth forging die different from the first to third forging die. A finished product is obtained.

  As described above, in the forging method according to the prior art, various forging processes are performed on the workpiece using the first to fourth forging dies having different structures, and various processing operations are performed during the forging process. Made.

JP 2002-178086 A

  By the way, in the forging method according to the above-described prior art, in the third step of performing the backward extrusion, when the tip of the punch abuts against the work and pressurizes the work, the radial direction extends from the center of the work. Thus, the flow of the meat in the circumferential direction is generated by the meat flow extruding along the circumferential direction in order to form the track groove by the convex portion of the punch. In this case, the radial meat flow and the circumferential meat flow merge to cause stress to concentrate on the base of the bulge formed on the punch, thereby deteriorating the life of the punch. There is a problem.

  The present invention has been made in view of the above problems, and when forming the track groove by performing the rear extrusion, the plastic flow of the meat radially spreading along the radially outward direction and the meat in the circumferential direction are formed. An object of the present invention is to provide a method for manufacturing an outer ring member for a constant velocity joint and a punch capable of improving the durability of the punch by avoiding stress concentration generated in a specific portion of the punch by a synergistic action with plastic flow. And

In order to achieve the above object, the present invention is a method for manufacturing an outer ring member for a tripod type constant velocity joint in which a shaft portion and a cup portion are integrally formed,
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 having a head having a diameter larger than that of the upper portion by performing upsetting on the upper portion excluding the shaft portion of the workpiece;
Forming a third molded body having a cup portion provided with a track groove by performing backward extrusion molding on the head of the second molded body;
Performing ironing on the cup portion of the third molded body;
Have
The secondary molded body with a punch having a plurality of ridges spaced at equal angles along the circumferential direction and extending along the axial direction and recesses formed between the adjacent ridges. The first to third rectangular inclined surfaces formed at the tips of the protrusions of the punch that come into contact with the head of the second molded body when the head is pressed and subjected to rear extrusion. A pair of taper surfaces that are continuous and are inclined at a predetermined angle along the circumferential direction with respect to the first to third rectangular inclined surfaces promotes plastic flow of meat in the circumferential direction, thereby the pair of tapers. It is characterized in that the concentration of stress is relaxed with respect to the jaw portion facing the concave portion in the vicinity of the surface.

Furthermore, the present invention is used when manufacturing an outer ring member for a tripod type constant velocity joint in which a shaft portion and a cup portion are integrally formed, and a rear extrusion molding is performed on the head of the intermediate molded body. A punch for forming a track groove on the inner wall surface of the cup part,
A recess formed so as to extend along the axial direction between a plurality of protruding ridges that are equiangularly spaced along the circumferential direction and extend along the axial direction; ,
First to third rectangular inclined surfaces formed along the radially outward direction at the tips of the ridges contacting the head of the intermediate molded body;
Each of the first to third rectangular inclined surfaces is continuous, and a pair of tapered surfaces that are inclined at a predetermined angle along a circumferential direction with respect to the first to third rectangular inclined surfaces;
Is provided.

  According to the present invention, when the track groove is formed by performing the rear extrusion, the plastic flow of the meat that spreads radially along the radially outward direction by the first to third rectangular inclined surfaces of the punch; Jaw that is continuous with the pair of tapered surfaces and faces the concave portion is prevented from intersecting and joining the plastic flow of the meat in the circumferential direction by the pair of tapered surfaces continuing to the third rectangular inclined surface. It is possible to improve the durability of the punch by avoiding stress concentration on the part.

  In this case, the pair of tapered surfaces that are continuous with the first to third rectangular inclined surfaces and inclined at a predetermined angle function as escapes that actively promote plastic flow of the meat in the circumferential direction, and are close to the tapered surfaces. Thus, the stress on the jaw facing the concave portion is reduced and stress concentration is avoided.

  According to the present invention, when the track groove is formed by performing the backward extrusion, the punch is formed by the cooperative action of the plastic flow of the meat radially extending along the radially outward direction and the plastic flow of the meat in the circumferential direction. It is possible to improve the durability of the punch by avoiding stress concentration occurring at a specific portion.

  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 constant velocity joint outer ring member according to the present embodiment, as shown in the flowchart of FIG. 1, the forging process is performed a total of four times on the workpiece 10 made of a carbon steel cylinder. Finally, a tripod type constant velocity joint outer ring member is manufactured.

  In the present embodiment, warm forging is performed from the first to the third, and cold forging is performed for the fourth. However, the present invention is not limited to this, and warm forging and cooling are performed. It may be combined with hot forging or only one of warm or cold forging may be used.

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

  First, as a preparatory step, after performing a coating process and a lubrication spray process on a workpiece 10 (see FIG. 2A) made of a billet in which a round bar material is cut to a predetermined length, it is about 850 degrees through a heating means (not shown). Heat to 870 degrees.

  Next, in the first warm forging step S1, forward extrusion molding is performed on the workpiece 10 heated to the predetermined temperature. 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 with 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. 2B) 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, in the second warm forging process S <b> 2, upsetting is performed on the upper portion 18 of the primary molded product 16. 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 (not shown) provided in a second forging die (not shown).

  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 the punch which is not shown in figure. Along with this crushing, the upper portion 18 is compressed and expanded in diameter, whereby a secondary molded product (secondary molded body) 20 (see FIG. 2C) is obtained.

  Subsequently, in the third warm forging step S <b> 3, the head portion 22 of the secondary molded product 20 is formed on the substantially bottomed cylindrical cup portion 24, and three on the inner peripheral surface of the cup portion 24. The track grooves 26a to 26c are formed by rear extrusion forming the axial direction to form the third molded product 28 (see FIG. 2D).

  That is, by using a third forging die (not shown) and pressing the head 22 of the secondary molded product 20 loaded in the cavity with the punch 30, the head 22 of the secondary molded product 20 is axial. A third molded product (third molded product) 28 extruded in a cup shape along the direction is obtained.

  Here, the punch 30 used for back extrusion molding of 3rd warm forging process S3 is shown in FIGS.

  The punch 30 extends along the axial direction between the three ridges 46 that are equiangularly spaced along the circumferential direction and extend along the axial direction, and the adjacent ridges 46. A concave portion 48 formed so as to exist, first to third rectangular inclined surfaces 36a to 36c formed at the distal end of the protrusion 46 along the radially outward direction, and the first to third rectangular shapes. Each of the inclined surfaces 36a to 36c is provided with a pair of tapered surfaces 38a and 38b that are inclined at a predetermined angle along the circumferential direction with respect to the first to third rectangular inclined surfaces 36a to 36c.

  That is, as shown in FIGS. 3 and 5, at the tip of the punch 30, a circular plane portion 32 formed at the center, and a band-shaped annular inclined surface 34 surrounding the circular plane portion 32. The first to third rectangular slopes that are continuous with the annular inclined surface 34 and spaced apart at equal angles along the circumferential direction, and are inclined at the same angle along the radially outward direction from the circular plane portion 32. Surfaces 36a to 36c are formed.

  The inclination angle A of the first to third rectangular inclined surfaces 36a to 36c with respect to the circular plane portion 32 is set, for example, within a range of 5 degrees to 15 degrees, and preferably set to 10 degrees. It is good (see FIG. 8). When the inclination angle A is less than 5 degrees, the action of plastically flowing the meat along the radially outward direction is weak, while when the inclination angle A exceeds 15 degrees, wear of the punch becomes significant.

  As shown in FIG. 7, a predetermined angle with respect to each of the first to third rectangular inclined surfaces 36a to 36c is provided on both sides along the circumferential direction of each of the first to third rectangular inclined surfaces 36a to 36c. A pair of inclined tapered surfaces 38a and 38b are formed, and the boundary portions between the tapered surfaces 38a and 38b and the first to third rectangular inclined surfaces 36a to 36c are formed in a chamfered R portion.

  In addition, the inclination angle B of each taper surface 38a, 38b is set in the range of 30 degrees-60 degrees, for example, It is good to set to 45 degrees suitably (refer FIG. 7). When the inclination angle B is less than 30 degrees, the effect of promoting the plastic flow of the meat in the circumferential direction is poor, whereas when the inclination angle B exceeds 60 degrees, the groove accuracy (dimensional accuracy) of the track groove is deteriorated. There is a risk.

  A straight chamfered portion 40 is formed to connect the pair of tapered surfaces 38a, 38b with each of the first to third rectangular inclined surfaces 36a to 36c interposed therebetween. It is formed to be inclined by a predetermined angle with respect to the shape inclined surfaces 36a to 36c.

  An arc-shaped chamfered portion 42 that follows the annular inclined surface 34 is formed between one tapered surface 38a and the other tapered surface 38b that face each other with the concave portion 48 therebetween, and the arc-shaped chamfered portion 42 is formed. A chamfered jaw portion 44 is formed at a connection portion between the tapered surface 38a (38b) and the tapered surface 38a (38b).

  In this case, the respective widths D and E of the linear chamfered portion 40 and the arcuate chamfered portion 42 that are continuous with the tapered surfaces 38a and 38b are obtained from the width F of the tapered surfaces 38a and 38b, as shown in FIG. Is also set small (D, E <F).

  The outer peripheral surface of the punch 30 is provided with three protrusions 46 that are separated from each other at an angle of 120 degrees along the circumferential direction and extend a predetermined length along the axial direction of the punch 30; A recess 48 is formed between the adjacent protrusions 46 along the axial direction. As shown in FIG. 2D, track grooves 26 a to 26 c are formed on the inner wall surface of the cup portion 24 of the third molded product 28 by these three protrusions 46.

  The protrusion 46 and the recess 48 are continuous with the first to third rectangular inclined surfaces 36a to 36c and the annular inclined surface 34 at the tip of the punch 30 through the chamfered curved surface portion, respectively. A molding land portion 50 having a predetermined width H is formed over the entire circumference of the punch 30 on the side surface of the punch 30 close to the tip. In FIG. 6, the angle θ indicates the inclination angle of the bulging molded land portion 50 compared to the other surface, and T indicates the thickness difference from the other surface.

  These track grooves 26a to 26c are formed by ironing the cup portion 24 in a fourth forging process S4 described later, thereby forming the track grooves 26a to 26c with further improved shape and dimensional accuracy. Is done.

  The punch 30 is provided so as to 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 30 is fixed to the elevating member via a jig.

  The third warm forging process for the secondary molded product 20, that is, the backward extrusion molding is performed as follows.

  First, the elevating member connected to the ram of the mechanical press is lowered under the driving action of a mechanical press (not shown). Following this, the punch 30 descends and finally comes into contact with the upper surface of the head portion 22 of the secondary molded product 20.

  By further lowering the punch 30 and pressing the head 22, the head 22 is plastically deformed. At that time, the head 22 of the secondary molded product 20 is plastically deformed by the molding land portion 50 of the punch 30 while the plastic flow is restricted by the inner wall portion of the not-shown cup portion forming cavity, whereby the punch 30 The meat plastically flows along the outer peripheral surface toward the rear (upward) opposite to the downward direction of the punch 30, and the cup portion 24 is formed.

  In this case, the large diameter portion of the cup portion 24 is extended by plastic flow, so that the track grooves 26 a to 26 c along the axial direction of the third molded product 28 are formed by the protrusion portion 46 of the punch 30. It is formed on the inner wall surface.

  Thereafter, when the punch 30 is lifted together with the ram and the lifting member under the driving action of the mechanical press, and further, the knockout pin (not shown) is raised, a fourth molded product (not shown) is exposed.

  In the present embodiment, when forming the track grooves 26a to 26c by performing the rear extrusion, the plasticity of the meat radially spreading along the radially outward direction by the first to third rectangular inclined surfaces 36a to 36c of the punch 30. Flow (see arrow M in FIG. 9) and plastic flow of meat in the circumferential direction by a pair of tapered surfaces 38a, 38b continuous with the first to third rectangular inclined surfaces 36a-36c (arrow P in FIG. 9) Therefore, it is possible to prevent the stress from concentrating on the jaw portion 44 that is continuous with the pair of tapered surfaces 38a and 38b and faces the concave portion 48 side. Can be improved.

  In other words, by forming a pair of tapered surfaces 38a and 38b that are continuous with the first to third rectangular inclined surfaces 36a to 36c and are inclined at a predetermined angle, plastic flow of meat in the circumferential direction (arrow P in FIG. 9). Therefore, the stress applied to the jaw portion 44 facing the concave portion 48 in the vicinity of the tapered surfaces 38a and 38b is reduced and stress concentration is avoided (see FIG. 9).

  By providing the pair of tapered surfaces 38a, 38b at the tip of the punch 30 in this way, it is avoided that the plastically flowed meat directly presses the jaw portion 44 with high pressure, and the jaw portion 44 of the punch 30 is worn. Can be prevented. The portions of the track grooves 26a to 26c that are in contact with the peripheral surfaces of the rollers (not shown) are formed by the jaws 44 of the punch 30. Therefore, the important portions of the track grooves 26a to 26c that are in contact with the peripheral surfaces of the rollers are formed. Dimensional accuracy can be ensured.

  Further, the width F of the pair of tapered surfaces 38a and 38b is set to be larger than the widths D and E of the linear chamfered portion 40 and the arcuate chamfered portion 42 that are continuous with the pair of tapered surfaces 38a and 38b. Thus, the fluidity of meat in the circumferential direction can be more actively performed.

  As a result, the lifetime of the punch 30 can be extended to improve durability, and the track grooves 26a to 26c can be formed with high accuracy.

  Finally, a fourth cold forging step S4 is performed on the third molded product 28. In addition, before performing 4th cold forging process S4, it is good to apply | coat a liquid lubricant to at least any one of the surface of the 3rd molded article 28, or the 4th forging die (not shown). Thereby, it is possible to avoid the seizure of the third molded product 28 or the fourth forging die during the fourth cold forging step S4. As the liquid lubricant, a known liquid lubricant that has been conventionally used may be used.

  In the fourth cold forging step S4, a fourth forging die (not shown) is used to finish the cup portion 24 into a final product shape with respect to the inner surface and the outer surface of the third molded product 28. Ironing (final sizing) is performed. That is, the thickness of the cup portion 24 and the width and depth of the track grooves 26a to 26c are processed so as to have a predetermined dimensional accuracy, whereby the dimensional accuracy of the cup portion 24 including the shape of the track grooves 26a to 26c and the like. An outer ring member for a tripod type constant velocity joint is obtained as a finished product.

It is a flowchart which shows the manufacturing method of the outer ring member for constant velocity joints which concerns on embodiment of this invention. FIG. 2A is a side view of a workpiece made of a cylindrical body cut out to a predetermined length, FIG. 2B is a side view of a primary molded product obtained by forward extrusion molding with respect to the workpiece, and FIG. FIG. 2D is a side view and a plan view of a third molded product that has been subjected to backward extrusion molding with respect to the second molded product. It is. It is a partially-omission perspective view of the punch used for back extrusion molding of Drawing 2D. It is a partial cross section side view along the axial direction of the punch. FIG. 5 is an arrow view of the punch as seen from the direction of arrow Z in FIG. 4. It is a longitudinal cross-sectional view along the VI-VI line of FIG. It is a longitudinal cross-sectional view along the VII-VII line of FIG. It is a partially omitted side view of the tip of the punch. It is explanatory drawing which shows the plastic flow state of meat when back extrusion is performed with the punch shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Work 12 ... Reduced diameter part 14 ... Shaft part 16, 20, 28 ... Molded product 24 ... Cup part 26a-26c ... Track groove 30 ... Punch 32 ... Circular plane part 34 ... Annular inclined surface 36a-36c ... Rectangular shape Inclined surfaces 38a, 38b ... tapered surface 40 ... linear chamfered portion 42 ... arc-shaped chamfered portion 44 ... jaw portion 46 ... protruded portion 48 ... concave portion 50 ... molded land portion

Claims (2)

A method for manufacturing an outer ring member for a tripod type constant velocity joint in which a shaft portion and a cup portion are integrally formed,
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 having a head having a diameter larger than that of the upper portion by performing upsetting on the upper portion excluding the shaft portion of the workpiece;
Forming a third molded body having a cup portion provided with a track groove by performing backward extrusion molding on the head of the second molded body;
Performing ironing on the cup portion of the third molded body;
Have
The secondary molded body with a punch having a plurality of ridges that are equiangularly spaced along the circumferential direction and that extend along the axial direction, and a recess formed between the adjacent ridges. The first to third rectangular inclined surfaces formed at the tips of the protrusions of the punch that come into contact with the head of the secondary molded body when the head is pressed and the rear extrusion is performed. The pair of taper surfaces are urged by a pair of tapered surfaces that are continuous and are inclined at a predetermined angle along the circumferential direction with respect to the first to third rectangular inclined surfaces. A method for manufacturing an outer ring member for a constant velocity joint, characterized in that stress concentration is reduced with respect to a jaw portion facing a concave portion close to a surface. Used when manufacturing a triport type constant velocity joint outer ring member in which the shaft portion and the cup portion are integrally formed, and the inner portion of the cup portion is formed by subjecting the head of the intermediate molded body to backward extrusion. A punch for forming a track groove on a wall surface,
A recess formed so as to extend along the axial direction between a plurality of protruding ridges that are equiangularly spaced along the circumferential direction and extend along the axial direction; ,
First to third rectangular inclined surfaces formed along the radially outward direction at the tips of the ridges contacting the head of the intermediate molded body;
Each of the first to third rectangular inclined surfaces is continuous, and a pair of tapered surfaces that are inclined at a predetermined angle along a circumferential direction with respect to the first to third rectangular inclined surfaces;
Punch characterized by being provided.

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