JP2007000873A - Method for manufacturing outer wheel member for constant velocity joint - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To attain the optimum decentralization of each step by reducing the forming rate of a fourth step of forming a ball rolling groove. <P>SOLUTION: In a first step, a work 10 is subjected to the forward extrusion to form a first formed article 40, and in a second step, the upset forming is performed to form a second formed article 50. Successively, in a third step, the preliminary extrusion is performed on an upper face of the second formed article 50 to form a third formed article 60 in which a recess 62 substantially matched with the longitudinal sectional shape in the axial direction of a bottom wall 32 of a cup part of a final product is formed in the upper face. In a fourth step, the backward extrusion is performed on the third formed article 60 by using a punch having a tip shape substantially matched with the longitudinal sectional shape of the recess 62 to form a fourth formed article 70 having a cup part with a ball rolling groove formed in an inner wall thereof. Finally, in a fifth step, the cup part of the fourth formed article is ironed to manufacture an outer wheel member 12 as the final product. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an outer ring member for a constant velocity joint that constitutes a constant velocity joint for transmitting rotational driving force, and more specifically, a cup portion having a plurality of guide grooves on an inner peripheral surface and a shaft portion are integrated. The present invention relates to a method for manufacturing an outer ring member for a constant velocity joint, in which the outer ring member for a constant velocity joint is manufactured by forging.

  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 includes a cup portion and a shaft portion formed integrally with the cup portion. A plurality of ball rolling grooves extending along the axial direction are formed on the inner peripheral surface of the cup portion so as to be spaced at equal angles along the circumferential direction, and the balls roll along the ball rolling grooves. It is provided to move.

  As a method of manufacturing an outer ring member of this type of constant velocity joint, Patent Document 1 discloses that a concave part having a semicircular cross section is formed on the upper surface of a cup part by performing upsetting on a preform. It is disclosed. In this case, in Patent Document 1, by forming a concave portion having a radial cross section on the upper surface of the cup portion, the plastic fluidity at the time of backward extrusion molding in the next step becomes smooth, and the product completion accuracy can be improved. .

  Further, Patent Document 2 discloses that a concave hole is formed on the upper surface of the head by subjecting the hot-treatment material having the head and the body to a longitudinal extrusion process.

  Furthermore, Patent Document 3 discloses that a concave cave portion is formed by pressing the center portion of the end surface of the large diameter portion.

JP 2002-178090 A JP 58-50149 A Japanese Patent Laid-Open No. 55-5120

  However, in the technical idea disclosed in Patent Documents 1 to 3, in the next step, for example, a concave portion is formed in the head of the intermediate molded body only to smooth the meat flow when performing the backward extrusion molding. However, the amount of deformation (elongation of the material) in the fourth step of forming the ball rolling groove on the inner wall surface of the cup portion by the backward extrusion molding is still large, and the amount of work (molding rate) compared to the other steps ) Is a problem.

  The present invention distributes a part of the work amount in the fourth process to the third process, which is the previous process, and reduces the molding rate in the fourth process for forming the ball rolling groove, thereby optimally distributing each process. 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 be made simple.

  In order to achieve the above object, the present invention performs the following first to fifth steps.

  First, in a 1st process, the primary molded object which has a shaft part is formed by carrying out forward extrusion molding with respect to the cylindrical workpiece cut | disconnected by predetermined length.

  Subsequently, in the second step, upset molding is performed on the upper portion excluding the shaft portion, and a secondary molded body in which the upper portion of the primary molded body is compressed and expanded is formed.

  Subsequently, in the third step, by performing pre-injection molding on the upper surface of the secondary molded body, there is a concave portion that substantially matches the longitudinal sectional shape in the axial direction of the bottom wall of the cup portion of the final product. A tertiary molded body formed on the upper surface is formed. Originally, the bottom wall of the cup portion is obtained by sharing the third step with the fourth step which is the next step.

  In this case, an R portion having a curved cross section is formed along the circumferential direction at the boundary portion between the upper surface of the head of the third molded body and the opening of the recess, so that the periphery of the opening of the recess It is possible to prevent streaks from occurring.

  Subsequently, in the fourth step, a ball having a ball rolling groove is formed on the inner wall by using a punch having a tip shape substantially matching the vertical cross-sectional shape of the concave portion and subjecting the third molded body to backward extrusion. A fourth molded body having the provided cup portion is formed.

  Finally, in the fifth step, the cup part of the fourth molded body is ironed and formed into a final product, which is a bar field type constant velocity joint in which the shaft part and the cup part are integrally formed. An outer ring member is manufactured.

  According to the present invention, a part of the work of forming the bottom wall of the cup part in the fourth step is shared with the third step, which is the previous step, so as to form the ball rolling groove. The rate can be reduced.

  As a result, in the present invention, by reducing the molding rate in the fourth step, the deformation amount (elongation of the material) of the forging material is reduced, and the occurrence of material cracking is avoided to achieve good mold transferability. be able to.

  In the present invention, a part of the work amount in the fourth step is shared with the third step, which is the previous step, and the forming rate of the fourth step for forming the ball rolling groove is reduced, so that each step is optimally dispersed. Can be achieved. As a result, the yield can be improved by suppressing the occurrence of defective products such as material cracks. In particular, when it is formed by cold forging, the effect is remarkable.

  Hereinafter, preferred embodiments of a 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 constant velocity joint according to the present embodiment, as shown in the flowchart of FIG. 1, a total of five workpieces 10 (see FIG. 2A) made of carbon steel cylinders (billets) are used. Forged forming is performed once, and finally, a finished barfield type constant velocity joint outer ring member 12 (hereinafter, simply referred to as an outer ring member 12) is manufactured.

  As shown in FIGS. 3 and 4, the outer ring member 12 includes a bottomed cylindrical cup portion 16 having an opening 14 connected to one end portion of a shaft (not shown), and the cup portion 16 integrally. It is basically composed of the shaft portion 18 formed.

  The outer surface of the cup portion 16 adjacent to the coupling portion between the cup portion 16 and the shaft portion 18 is a cross section from the side circumferential portion 20 whose longitudinal section along the axial direction is substantially parallel to the axis line toward the shaft portion 18 side. A curved surface portion 22 that is reduced in diameter while being curved in an arc shape is formed, and is configured to be connected to the shaft portion 18 via an annular stepped portion 24 that continues to the curved surface portion 22 and extends in a direction perpendicular to the axis. The

  On the inner wall surface of the cup portion 16 of the outer ring member 12, a spherical inner surface 28 bulges toward the center, and a ball extending along the axial direction is formed between adjacent inner surface 28. A plurality of rolling grooves 30a to 30f are formed around the shaft center at intervals of 60 degrees (see FIGS. 3 and 4).

  The ball rolling grooves 30 a to 30 f smoothly roll a ball (not shown), and are provided to extend along the inner wall surface of the outer ring member 12 to the vicinity of the end portion on the bottom side of the cup portion 16. . Further, as shown in FIG. 5, each of the ball rolling grooves 30a to 30f is formed in a circular arc shape having a single radius of curvature when viewed from the axial direction of the outer ring member 12 (the arrow Z direction in FIG. 3). It is formed.

  Further, a bottom wall 32 (see an imaginary line F1 in FIG. 3) that is formed at the innermost part of the inner wall surface of the cup portion 16 of the outer ring member 12 and extends in a direction orthogonal to the axial direction is an outer portion of the cup portion 16. It is set at an intermediate position of the curved surface portion 22 formed on the surface, and is set so as to be separated from the virtual line F2 of the annular step portion 24 continuous with the curved surface portion 22 by ΔP (see FIG. 3).

  The longitudinal cross-sectional shape along the axial direction of the bottom wall 76 formed in the cup portion 16 has a circular flat surface 33 having a diameter D3 in plan view, and a continuous shape from the circular flat surface 33 to the opening. It is constituted by an annular inclined surface 35 having an inclination angle of θ3 with respect to the circular flat surface 33. As will be described later, the longitudinal sectional shape of the concave portion 62 of the third molded product 60 and the bottom wall 76 of the fourth molded product 70 It is almost the same.

  The outer ring member 12 is manufactured by the following process.

  First, in the first preparation step, spheroidizing annealing is performed on the workpiece 10 (see FIG. 2A) cut into a predetermined-length cylindrical body (billet). Thereby, the workpiece | work 10 is softened and the following 1st-5th 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 forging step S1, a first forging die (not shown) is used to perform forward extrusion molding on one end surface of the workpiece 10 on which the chemical conversion coating for lubrication is formed.

  That is, the workpiece 10 is loaded into a cavity of a first forging die (not shown), and one end surface of the workpiece 10 is pressed by a punch (not shown). Along with this, the other end surface side of the work 10 is press-fitted into the cavity, and as a result, as shown in FIG. The primary molded product 40 is obtained (see FIG. 2B).

  Next, upset molding is performed on the primary molded product 40 in the second forging step S2. That is, the primary molded product 40 is loaded into a cavity of a second forging die (not shown). At this time, the shaft portion 40b is inserted into a shaft portion holding portion (not shown) provided in the second forging die.

  And while supporting the front-end | tip part of the axial part 40b inserted in the axial part holding | maintenance part which is not shown in figure with the pressing member which is not shown in figure, the upper part of the primary molded product 40 is pressed and crushed with a punch. Along with the crushing, the upper part is compressed and the diameter is expanded, whereby a secondary molded product (secondary molded body) 50 (see FIG. 2C) is obtained.

  Subsequently, in the third forging step S3, preliminary pressing is performed on the upper surface of the head of the secondary molded product 50, and the third in which a recess 62 is formed in the center of the upper surface of the head. A molded product 60 is obtained (see FIG. 2D).

  That is, by using a third forging die (not shown) and pressing the upper surface of the secondary molded product 50 loaded in the cavity with a punch (not shown), the center of the upper surface of the head of the secondary molded product 50 is pressed. A recess 62 is formed in which the portion is recessed by a predetermined depth in the axial direction.

  The concave portion 62 includes a circular flat surface 64 having a diameter D1 in plan view, and an annular inclined surface 66 that is continuous from the circular flat surface 64 to the opening and has an inclination angle θ1 with respect to the circular flat surface 64. Composed.

  The predetermined depth T1 of the recess 62 (see FIG. 2D) is the depth of the circular flat surface 72 and the ball rolling groove 74 formed in the back part of the cup part of the fourth molded product 70 in the next process. It is good to set below the separation distance T2 (refer FIG. 2E) along the axial direction (vertical direction) with a part side termination | terminus part (T1 <= T2).

  In the third molded product 60, the longitudinal cross-sectional shape of the recess 62 constituted by the circular flat surface 64 and the annular inclined surface 66 is formed in the back of the cup portion in the fourth molded product 70 of the next process. The vertical cross-sectional shape of the bottom wall 76 is substantially the same as the vertical cross-sectional shape along the axial direction of the bottom wall 32 of the outer ring member 12 that is the final product.

  Further, an R portion 68 having a non-angular shape and a curved cross section having a predetermined radius of curvature is provided along the circumferential direction at a boundary portion between the upper surface of the head of the third molded product 60 and the opening of the recess 62. (See FIG. 6).

  By forming the R portion 68 at the entrance portion where the concave portion 62 opens, it is possible to prevent the generation of streaks around the opening portion of the concave portion 62 and to form the third molded product 60 in a later step. On the other hand, it is possible to avoid the occurrence of cracks and the like due to the streaks when heat treatment is performed.

  After the completion of the third forging step S3, a low temperature annealing for removing stress from the third molded product 60, a shot blasting process for removing oxide scales and the like generated during this low temperature annealing, and a first process by a bonderite process. A lubricating chemical conversion film made of zinc phosphate or the like is formed on the outer surface of the tertiary molded product 60. This is because the third molded product 60 can be easily plastically deformed by performing these various processes.

  Thereafter, a fourth forging step S4 is performed using a fourth forging die (not shown). For the third molded product 60 in which the shaft portion is inserted into the shaft portion insertion portion of the fourth forging die (not shown), the tip shape is substantially the same as the longitudinal sectional shape of the recess 62 of the third molded product 60. A fourth forging process is performed using a punch (not shown) to obtain a fourth molded product 70 (see FIG. 2E).

  In this case, the vertical cross-sectional shape of the bottom wall 76 formed in the back part of the cup part of the fourth molded product 70 includes a circular flat surface 72 having a diameter D2 in plan view and the circular flat surface 72. An annular inclined surface 78 that continues to the opening and has an inclination angle of θ2 with respect to the circular flat surface 72 is substantially the same as the longitudinal sectional shape of the recess 62 of the third molded product 60 as described above.

  In the fourth forging step S4, the third molded product 60 is performed by using a punch (not shown) whose tip shape substantially matches the vertical cross-sectional shape of the concave portion 62 of the third molded product 60. The circular flat surface 64 constituting the recess 62 becomes a non-plastic flow site, and only the annular inclined surface 66 becomes a plastic flow site and is pushed out rearward of the cup portion.

  After the fourth forging step S4 is performed, the fifth cold forging step S5 is performed on the fourth molded product 70. Before performing the fifth forging step S5, a liquid lubricant may be applied to at least one of the surface of the fourth molded product 70 and the fifth forging die (not shown). Thereby, it is possible to avoid the seizure of the fourth molded product 70 or the fifth forging die during the fifth forging step S5. As the liquid lubricant, a known liquid lubricant that has been conventionally used may be used.

  In the fifth forging step S5, a fifth forging die (not shown) is used, and a tip (not shown) whose tip shape is substantially the same as the longitudinal sectional shape of the recess 62 of the third molded product 60 is used. The inner and outer surfaces of the fourth molded product 70 are subjected to ironing (final sizing molding) for finishing the cup portion 16 into a final product shape.

  That is, the cup portion 16 is processed so that the thickness of the cup portion 16 and the width and depth of the ball rolling grooves 30a to 30f have predetermined dimensional accuracy, thereby including the shape of the ball rolling grooves 30a to 30f and the like. An outer ring member 12 for a Barfield type constant velocity joint as a finished product having a dimensional accuracy of 16 is obtained (see FIG. 2F).

  When the fifth forging step S5 is performed on the fourth molded product 70, the circular flat surface 72 constituting the bottom wall 76 of the cup portion becomes a non-plastic flow site, and only the annular inclined surface 78 is plastic. Sizing is performed as a flow site.

  The vertical cross-sectional shape of the bottom wall 32 formed in the inner portion of the cup portion of the outer ring member 12 is continuous from the circular flat surface 33 having a diameter D3 in plan view and the circular flat surface 33 to the opening. It is constituted by an annular inclined surface 35 having an inclination angle of θ3 with respect to the circular flat surface 33, and is substantially the same as the longitudinal sectional shape of the concave portion 62 of the third molded product 60 and the bottom wall of the fourth molded product 70.

  In other words, the diameters of the circular flat surfaces 64, 72, 33 from the third molded product to the fifth molded product (the outer ring member 12 which is the final product) are D1≈D2≈D3, and the circular shape. The inclination angles of the annular inclined surfaces 66, 78, and 35 with respect to the flat surfaces 64, 72, and 33 are θ1 = θ2 = θ3. It is preferable that the inclination angle of each annular inclined surface 66, 78, 35 is set to about 45 degrees.

  In this case, as forging, the first forging step S1 to the third forging step S3 are performed by warm forging or hot forging, and the fourth forging step S4 and the fifth forging step. S5 may be performed by cold forging. Alternatively, all the steps from the first forging step S1 to the fifth forging step S5 may be performed by cold forging.

  According to the present embodiment, part of the work of forming the bottom wall of the cup portion in the fourth forging step S4 is originally assigned to the third forging step S3, which is the previous step. By forming the recess 62 on the upper surface of the tertiary molded product 60, the molding rate of the fourth forging step S4 for forming the ball rolling grooves 30a to 30f can be reduced.

  As a result, in the present embodiment, by reducing the forming rate in the fourth forging step S4, the deformation amount of the forging material (elongation of material) is reduced, and the occurrence of material cracking is avoided and good gold Mold transferability can be achieved.

  Further, in the present embodiment, the circular flat surface of the recess formed in the third molded product 60 becomes a non-plastic flow site and is removed from the plastic flow site, so that the fourth forging step and the fifth The plastic flow (meat flow) when forming the ball rolling groove in the next forging process becomes even smoother, and the ball rolling groove can be formed with high accuracy.

  Furthermore, in the present embodiment, the ball rolling grooves 30a to 30f are formed by sharing a part of the work amount in the fourth forging process with the third forging process, which is the preceding process. It is possible to reduce the forming rate in the quaternary forging process and achieve optimum dispersion of each process. As a result, the yield can be improved by suppressing the occurrence of defective products such as material cracks.

It is a flowchart which shows the manufacturing process of the outer ring member for constant velocity joints which concerns on this Embodiment. 2A to 2F are a side view and a partial vertical cross-sectional view showing the shape of the outer ring member for a constant velocity joint that reaches a finished product by forging a workpiece along the manufacturing process shown in FIG. It is a longitudinal cross-sectional view along the axial direction of the outer ring member for constant velocity joints which is a completed product. FIG. 4 is an arrow view seen from the direction of arrow Z in FIG. 3. FIG. 5 is a partially enlarged side view of the ball rolling groove shown in FIG. 4. It is the elements on larger scale of the R section formed in the boundary part of the crevice and the upper surface of the tertiary molded product shown in Drawing 2D.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Work 12 ... Outer ring member 14 for constant velocity joints ... Opening part 16 ... Cup part 18 ... Shaft part 20 ... Side peripheral part 22 ... Curved surface part 24 ... Annular level | step-difference part 28 ... Inner diameter surface 30a-30f ... Ball rolling groove 32 , 76 ... bottom wall 33, 64, 72 ... circular flat surfaces 35, 66, 78 ... annular inclined surfaces 40, 50, 60, 70 ... molded product 62 ... recessed portion 68 ... R portion

Claims (2)

A method for producing an outer ring member for a barfield type constant velocity joint in which a shaft portion and a cup portion are integrally formed by forging,
A first step of forming a primary molded body having a shaft portion by forward-extruding a cylindrical workpiece cut into a predetermined length;
A second step of forming a secondary molded body in which the upper part of the primary molded body is compressed and expanded by upsetting the upper part excluding the shaft part;
By performing pre-indentation on the upper surface of the secondary molded body, a recess that substantially matches the longitudinal sectional shape in the axial direction of the bottom wall of the cup portion of the final product is formed on the upper surface. A third step of forming a next molded body;
A punch having a tip shape substantially matching the vertical cross-sectional shape of the concave portion is used, and the third molded body is subjected to a backward extrusion molding to have a cup portion having a ball rolling groove on the inner wall. A fourth step of forming a quaternary molded body;
A fifth step of 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,
An outer ring member for a constant velocity joint, wherein an R portion having a curved cross section is formed along a circumferential direction at a boundary portion between the upper surface of the head of the third molded body and the opening of the recess. Manufacturing method.

Images