JP2009166072A - Method for manufacturing yoke for universal joint - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method by which a yoke for universal joint capable of preventing the occurrence of defects in a base and bending parts 25a, 25a of a pair of arm parts 14, 14 can be manufactured without upsizing equipment. <P>SOLUTION: A thick-walled part 41 constituting a first intermediate material 49 is compressed in an axial direction between a crushing punch and a counter punch, and thereby a pair of lingual parts 42. 42 are made upright using a difference in flow velocity of metallic materials. The pair of the arm parts 14, 14 are formed by subjecting a pair of the sloped arm parts 60, 60 to bending. The problem can be solved by employing such manufacturing step. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  A universal joint yoke manufacturing method according to the present invention is, for example, incorporated in a steering apparatus for an automobile, and connects ends of a pair of rotating shafts that do not exist on the same straight line. The present invention relates to a method of manufacturing a yoke that constitutes a universal joint capable of transmitting a rotational force.

  For example, as shown in FIG. 13, a steering apparatus for an automobile includes a steering wheel 1, a steering shaft 2 that fixes the steering wheel 1 to the rear end (the right end in FIG. 13), and the steering shaft 2 on the inner diameter side. The steering column 3 that is rotatably supported, the steering force assisting device 4 for applying auxiliary power to the steering shaft 2, and the tie rods 5 and 5 are displaced (push and pull) based on the rotation of the steering shaft 2. A steering gear unit 6 is provided.

  The rotation of the steering shaft 2 based on the operation of the steering wheel 1 is input to the steering gear unit 6 via the universal joints 7a and 7b and the intermediate shaft 8 corresponding to the rotation shaft described in the claims. It is transmitted to the shaft 9. The steering gear unit 6 includes a rack and a pinion (not shown), and the input shaft 9 is coupled to the pinion. Further, the rack that meshes with the pinion has both tie rods 5 and 5 connected to both ends, and by pushing and pulling the tie rods 5 and 5 based on the displacement of the rack, a steered wheel (not shown). Is given a desired rudder angle.

  Further, the two universal joints 7a and 7b, as shown in detail in FIG. 14, respectively, are the first yoke 10 that is the object of the manufacturing method of the present invention, and the second yoke 11 that is out of the object of the manufacturing method of the present invention. The first and second yokes 10 and 11 are configured by a cross shaft 12 for connecting the yokes 11 and 11 to each other. Among these, the first yoke 10 is coupled and fixed to both ends of the intermediate shaft 8 by welding. The first yoke 10 is bent in a substantially perpendicular direction in the same direction (left and right direction in FIG. 14) from a substantially annular base 13 and two positions on the diametrically opposite side of the base 13 (up and down position in FIG. 14). And a pair of arm portions 14, 14. A coupling hole 15 for externally fixing and fixing the end of the intermediate shaft 8 is formed at the center of the base 13, and the cross shafts are provided at the distal ends of the arms 14 and 14. The circular holes 16 and 16 for supporting the 12 tip portions are formed concentrically with each other.

  On the other hand, the second yoke 11 includes a notch cylindrical base portion 17 for connecting to the front end portion of the steering shaft 2 and the end portion of the input shaft 9 of the steering gear unit 6, and the axial direction of the base portion 17. It has a pair of arms 18 extending in the axial direction from the diametrically opposite position (front and back position in FIG. 14) of one end edge. Further, circular holes (not shown) are formed concentrically with each other at the distal ends of the both arm portions 18.

  Then, the bearing cups 19 and 19 are disposed at the inner sides of the first and second circular holes 16 provided at the four ends of the cross shaft 12 in pairs of the first and second yokes 10 and 11, respectively. Via the support. With such a configuration, the ends of the rotating shafts such as the steering shaft 2, the intermediate shaft 8, and the input shaft 9 that do not exist on the same straight line are connected to each other, and the plurality of rotating shafts 2, 8, 9 are connected to each other. Rotational force can be transmitted between the two.

  The configuration and operation of the automobile steering device and the universal joints 7a and 7b incorporated in the automobile steering device are as described above. The first of the universal joints 7a and 7b is configured as described above. The yoke 10 has been conventionally manufactured by performing plastic working on a metal plate having sufficient rigidity, such as a steel plate, as described in Patent Document 1, for example. FIG. 15 shows a manufacturing process of the universal joint yoke (first yoke 10) described in Patent Document 1.

  As shown in FIG. 15 (A), first, circular holes 16 and 16 for supporting the ends of the cross shaft 12 (see FIG. 14) are punched on a material 20 which is a metal plate such as a steel plate. Use to drill. Next, by punching the material 20, a first intermediate material 21 as shown in FIG. The first intermediate material 21 is formed in a substantially disc-shaped element base 22 and at a position opposite to the diameter direction of the element base 22 in a state of extending outward in the diameter direction of the element base 22. It consists of a pair of tongues 23, 23. In this state, the circular holes 16 and 16 are present at the tips of the tongues 23 and 23, respectively.

  Next, the first intermediate material 21 having such a shape is bent to obtain a second intermediate material 24 as shown in FIG. Specifically, the tongue portions 23 and 23 are bent in the same direction until they are substantially perpendicular to the element base portion 22 to form a pair of arm portions 14 and 14. Finally, the coupling hole 15 is formed in the central portion of the base 22 to obtain the first yoke 10 as shown in FIG.

  In the case of the first yoke 10 manufactured through the above-described processes, the following inconvenience may occur. That is, as shown in FIG. 15 (B) → (C), when the tongue portions 23 and 23 are bent to form the arms 14 and 14, the tongue portions 23 and 23 are formed. , 23 (or arms 14, 14) and bending portions 25, 25 between the base portions 22 (base portions 13) and the base portions 22 (base portions 13) are subjected to strong tensile stress due to bending. For this reason, there is a possibility that damage such as cracks or cracks may occur in the bent portions 25 and 25. In order to prevent damage based on such tensile stress, for example, it is conceivable to use a thin metal plate as the material 20. However, when such a thin metal plate is used, it is impossible to produce a thick and high-strength yoke that has been increasingly demanded in recent years.

  On the other hand, it is also described in Patent Document 2, for example, that a yoke that constitutes a universal joint is manufactured by subjecting a metal round bar material to cold forging instead of a metal plate such as a steel plate. Yes. In the case of the manufacturing method described in Patent Document 2, a pair of arm portions constituting the yoke is formed not by bending as described above but by backward extrusion. Specifically, it is formed by directly extruding a pair of arms from a round bar material. For this reason, it is possible to prevent the occurrence of cracks and cracks as described above at the bent portions of the both arms and the base. However, when the entire pair of arms are directly formed by the backward extrusion process, the flow amount of the metal material becomes large and a large press load is required, so that it is inevitable that the equipment is enlarged.

JP 2002-66677 A Japanese Patent Laid-Open No. 10-2342

  In view of the circumstances as described above, the present invention provides a universal joint yoke capable of ensuring sufficient strength and preventing occurrence of defects such as cracks and cracks in the bent portion between the base portion and the pair of arm portions. The present invention was invented to realize a manufacturing method that can be manufactured without increasing the size of the equipment.

The present invention includes a substantially annular base for coupling and fixing to the end of a rotating shaft, and a pair of arms bent in a substantially right-angle direction in the same direction from two positions on the diametrically opposite side of the base. The universal joint yoke is manufactured from a metal round bar material.
In particular, in the case of the present invention, the above-mentioned material is subjected to predetermined plastic processing such as pressing in the radial direction and axial direction, and trim processing to remove burrs as necessary. Get an intermediate material. The first intermediate material has a substantially cylindrical or substantially disk-shaped thick portion and extends radially outward from the thick portion at a position opposite to the diametrical direction at one axial end of the thick portion. And a pair of tongue-like portions that are thinner and plate-like than the thick-walled portion. Then, a preliminary start-up process and a start-up process are performed on the first intermediate material.

In the preliminary start-up process, the first intermediate material is perpendicular to the axial direction of the thick part and the arrangement direction (so-called longitudinal direction) of the pair of tongues and the thick part. While restraining from both sides, the thick part is compressed in the axial direction from one axial end side between the push side punch and the receiving side punch. Then, while reducing the thickness of the thick part in the axial direction, a part of the metal material constituting the thick part is caused to flow toward the both tongues in the arrangement direction. As a result, the two tongue-shaped portions are raised in a direction in which one side surface in the axial direction approaches the central axis of the first intermediate material, and at least the respective distal end portions are constituted by the both tongue-shaped portions, and the distance toward the distal end portion increases. A pair of inclined arm portions that are inclined in the direction of increasing the interval between the inner side surfaces facing each other are formed. Further, at the same time as forming both the inclined arm portions, a substantially disc-shaped element base portion for forming the base portion is formed between the base end portions of the both inclined arm portions, and the second intermediate material is formed. obtain.
Further, in the above-described startup process, after such a preliminary startup process, the two inclined arm portions constituting the second intermediate material are bent or paralleled until the pair of inclined arm portions are parallel or substantially parallel. And the pair of arms are formed from these inclined arms.

  Preferably, when carrying out the method for manufacturing a universal joint yoke of the present invention as described above, the thick part constituting the first intermediate material is substantially cylindrical, as in the invention described in claim 2, The shape of the outer peripheral surface of the thick wall portion is a shape in which a pair of flat surface portions and a pair of convex arc surface portions are alternately continued in the circumferential direction. The two flat surface portions are provided in a portion where the circumferential phase coincides with the pair of tongue-shaped portions, and from the base edge of the both tongue-shaped portions to the other axial end side of the thick-walled portion. It is made to incline in the direction approaching the central axis of this thick part, so that it goes.

  Alternatively, as in the invention described in claim 3, the thick portion constituting the first intermediate material is formed into a substantially disc shape, and a pair of tongue-shaped portions among the other axial end surfaces of the thick portion. In addition, a pair of bulging portions are provided at both end portions with respect to the arrangement direction of the thick-walled portion and projecting from the intermediate portion to the other end side in the axial direction.

  Moreover, when implementing this invention, Preferably, like the invention described in Claim 4, the axial direction of this thick part and 1 in the axial direction one end surface of the thick part which comprises said 1st intermediate material. A recessed portion that penetrates in a direction perpendicular to the arrangement direction of the pair of tongue-shaped portions and the thick-walled portion is provided. In the preliminary start-up step, the tip end portion of the push side punch is brought into contact with the bottom portion of the recessed portion.

  When carrying out the invention described in claim 4 as described above, preferably, as in the invention described in claim 5, a pair of outer flat surfaces are provided on the outer peripheral surface as the push side punch, A material having a convex curved surface portion between these both outer planes and the front end surface of the push side punch is used. And the radius of curvature of the cross-sectional shape of the both convex curved surface portions is the radius of curvature of the cross-sectional shape of the portion near the both ends in the width direction of the recessed portion, which is the portion where the both convex curved surface portions abut in the preliminary start-up process. Smaller than.

  Furthermore, when implementing this invention, Preferably, like the invention described in Claim 6, it acts between the axial direction other end surface of the thick part which comprises the said 1st intermediate material, and the said receiving side punch. The frictional force is made smaller than the frictional force acting between the one axial end surface of the thick part and the push side punch.

According to the method for manufacturing a yoke for a universal joint of the present invention as described above, a universal joint that can ensure sufficient strength and can prevent the bending portion between the base portion and the pair of arm portions from being cracked or cracked. York can be manufactured without increasing the size of the equipment.
That is, in the case of the present invention, by incorporating a preliminary start-up process, a pair of arms constituting the universal joint yoke can be formed stepwise (tongue-shaped portion → inclined arm portion → arm portion). Instead, in the preliminary start-up step, the inclined arm portion can be formed from the tongue-like portion by utilizing the difference in the flow rate of the metal material due to compression, not by the bending process in which the tensile stress acts. That is, a pair of inclined arm portions can be formed without applying tensile stress. Therefore, when forming a pair of arm portions by bending the both inclined arm portions in the subsequent startup process, a continuous portion of these inclined arm portions (or each arm portion) and the base portion. The tensile stress acting on the pair of bent portions existing in the case can be sufficiently reduced. As a result, it is possible to effectively prevent the occurrence of defects such as cracks and cracks due to the tensile stress in both bent portions.
Also in the case of the present invention, when forming both the inclined arm portions, as in the case of the manufacturing method (rear extrusion process) described in Patent Document 2 described above, the metal material is flowed. In the case of the invention, since both the inclined arm portions can be formed by using the both tongue-like portions, the flow amount of the metal material can be reduced as compared with the case of the invention described in Patent Document 2. For this reason, the required press load can be kept small, and an increase in the size of equipment for manufacturing the universal joint yoke can be prevented.
Further, in the case of the present invention, since a round bar material is used as the material, as in the case of the invention described in Patent Document 1 described above, a pair of arm portions and base portion meats constituting the finished product yoke are used. The thickness is not limited by the thickness of the material. For this reason, the thickness of the pair of arms and base can be increased, and a strong yoke can be manufactured.

  Further, according to the invention described in claim 2 described above, the volume of the thick part can be reduced from the one end side in the axial direction toward the other end side. The difference between the flow rate of the flowing metal material and the flow rate of the metal material flowing on the receiving punch side can be increased. Accordingly, the inclination angle of the pair of inclined arm portions (the rising angle of the tongue-like portion) can be made larger (can approach 90 degrees).

  Further, according to the invention described in claim 3 described above, the both tongue-shaped portions can be raised in two stages, that is, the bending moment and the difference in the flow rate of the metal material caused by the bulging portion being crushed. it can. For this reason, the flow amount of the metal material can be suppressed to a low level, and the press load can be further suppressed. Therefore, it is possible to more effectively prevent the equipment from becoming large.

  Further, in the case of the invention described in claim 4 described above, a recessed portion is provided on one end surface in the axial direction of the thick portion, in other words, both side portions of the one end surface near the pair of tongue-shaped portions. The volume of the metal material (metal material that obstructs the flow) existing on both sides of the push-side punch is increased with respect to the arrangement direction of the pair of tongue-shaped parts and the thick-walled parts by projecting the sword. I can do things. For this reason, the flow speed of the metal material which flows on the push side punch side in the thick part can be reduced. Therefore, as in the case of the invention described in claim 2 described above, the inclination angle of the pair of inclined arm portions can be made larger.

  Further, in the case of the invention described in claim 5 described above, the abutting portion between the convex curved surface portion provided at the tip portion of the push side punch and the concave portion provided at one end surface in the axial direction of the thick portion. The surface pressure can be increased, and the frictional force acting on the contact portion can be increased. For this reason, the flow rate of the metal material flowing on the push side punch side in the thick part can be slowed. For this reason, the inclination angle of the pair of inclined arm portions can be further increased as in the case of the inventions described in the second and fourth aspects.

  In the case of the invention described in claim 6, the flow rate of the metal material flowing on the push side punch side in the thick part and the flow rate of the metal material flowing on the receiving side punch side are The difference can be made larger. For this reason, the inclination angle of the pair of inclined arm portions can be further increased as in the case of the inventions described in the second, fourth, and fifth aspects.

[First example of embodiment]
1 to 9 show a first example of an embodiment of the present invention corresponding to claims 1, 2, and 4. FIG. In the case of this example, first, a long wire having a predetermined outer diameter drawn from an uncoiler (not shown) is cut into a predetermined length, so that a disk-like shape as shown in FIG. Material 26 is obtained. In the case of this example, as the above-mentioned wire rod, one made of carbon steel (S10 to 35C) and having an outer diameter of 50 to 60 mm is used, and this wire rod is used for the finished first yoke 10 (see FIG. 14). The material 26 is obtained by cutting at a position where the volume is larger than the volume. The material 26 corresponds to the round bar material described in the claims. In the case of this example, almost all processes are performed by cold forging except for some processes (heat treatment process, surface treatment process, trim processing process).

  The material 26 obtained as described above is subjected to heat treatment such as soft annealing and spheroidizing annealing to improve the workability of cold forging. Furthermore, in the case of this example, after performing such a heat treatment, a surface treatment such as a bonder treatment is performed in order to ensure the life of various tools and improve forging accuracy.

  After performing such surface treatment, the material 26 is compressed between a pair of press dies (pressed), and the first preliminary as shown in FIG. An intermediate material 27 is obtained. Thus, the operation of obtaining the first preliminary intermediate material 27 from the material 26 is performed using the first upper mold 28 and the first lower mold 29 as shown in FIG. The first upper mold 28 and the first lower mold 29 are provided with concave surfaces 30a and 30b having a partial cylindrical surface on opposite surfaces (the lower surface of the first upper mold 28 and the upper surface of the first lower mold 29). The plane portions 31a and 31b are provided.

  First, as shown in FIG. 2A, a concave curved surface portion 30a provided on the lower surface of the first upper die 28, and a concave curved surface portion 30b provided on the upper surface of the first lower die 29, The material 26 is sandwiched from both sides in the vertical direction (up and down direction in FIG. 2) with the central axis arranged in the horizontal direction. Next, by reducing the distance between the first upper mold 28 and the first lower mold 29 (lowering the first upper mold 28) until the state shown in FIG. It crushes in the up-and-down direction (diameter direction of the raw material 26) of FIG. As a result, the disk portion 32 having an outer peripheral surface shape that matches the inner surface shape of each of the concave curved surface portions 30a, 30b is formed between the two concave curved surface portions 30a, 30b facing each other, and at the same time, At the position opposite to the diameter direction of the portion 32, a pair of tongue-like portions 33, 33 are formed between the flat portions 31 a, 31 b facing each other to obtain the first preliminary intermediate material 27.

Incidentally, in the case of this example, each of concave portions 30a, the radius of curvature R ₃₀ of 30b, slightly wider than half the diameter d of the elements 26 smaller with (R ₃₀ <d / 2) is, The concave curved surface portions 30a and 30b and the flat surface portions 31a and 31b are smoothly continuous. With this configuration, in the case of this example, the fluidity of the metal material is improved and the press load is reduced.

  Next, the first preliminary intermediate material 27 obtained as described above is compressed in the axial direction between different press dies, and the second preliminary intermediate material 34 as shown in FIG. Get. Thus, the operation of obtaining the second preliminary intermediate material 34 from the first preliminary intermediate material 27 is performed using the second upper mold 35 and the second lower mold 36 as shown in FIG. Specifically, first, as shown in FIG. 3A, the first preliminary intermediate material 27 has its central axis aligned with the central axes of the second upper mold 35 and the second lower mold 36, respectively. It is placed on the upper surface of the second lower mold 36 in a state (arranged vertically). The upper surface of the second lower mold 36 is provided with a thick-wall-forming recess 37 at the center thereof, and the first preliminary intermediate material 27 is placed on the upper surface of the second lower mold 36. The thick-wall-forming recess 37 is located below the disk portion 32. The diameter of the upper end opening of the thick-walled concave portion 37 is substantially equal to the outer diameter of the disk portion 32. Therefore, only the two tongue portions 33 and 33 are placed on the upper surface of the second lower mold 36.

  Further, on the lower surface of the second upper mold 35, the tongue-shaped portion forming recesses 38, 38 are provided in portions facing the both tongue-shaped portions 33, 33, respectively. Further, a pressing convex portion 39 having a substantially trapezoidal cross section is provided in a portion between the both tongue-shaped portion forming concave portions 38, 38 at a portion facing the disk portion 32. In the case shown in the drawing, the front end surface of the pressing convex portion 39 is located on the same plane as the surface of the lower surface of the second upper die 35 other than the both tongue-shaped portion forming concave portions 38, 38. In the actual case, it does not have to be located on the same plane.

As described above, after placing the first preliminary intermediate material 27 on the upper surface of the second lower mold 36, the lower surface of the second upper mold 35 is set to the upper surface of the second lower mold 36. Lower until close to each other. Thus, the metal material constituting the first preliminary intermediate material 27 is filled in the space 40 constituted by the concave portions 37 and 38 to obtain the second preliminary intermediate material 34. The second preliminary intermediate material 34 includes a substantially cylindrical thick portion 41 and one axial end of the thick portion 41 {(C) in FIG. 1 and (B)-(a), (c) in FIG. ) On the opposite side in the diametrical direction}, and a pair of tongue-like portions 42, 42 extending outward in the diametrical direction of the thick portion 41, respectively. The thickness T ₄₂ of each of the tongue portions 42, ₄₂ is smaller than the thickness T ₄₁ {(C) of FIG. 1} of the thick portion 41 (T ₄₂ <T ₄₁ ). The thickness T ₄₁ of the portion 41 is sufficiently larger than the thickness T _{27 of} the first preliminary intermediate material 27 (T ₄₁ >> T ₂₇ ).

  The thick portion 41 has an outer surface shape that matches the inner surface shape of the thick portion forming concave portion 37, and the outer peripheral surface shape particularly has a pair of flat surface portions 43, 43 and 1 in the circumferential direction. The pair of convex arcuate surface portions 44, 44 are alternately continuous. Further, these flat surface portions 43 and 43 are provided in portions where the circumferential phase coincides with the tongue portions 42 and 42, and the base edge portions of the tongue portions 42 and 42 The axial direction other end side of the thick part 41 {the lower end side of (C) in FIG. 1 and (B)-(a) and (c) in FIG. 3} approaches the central axis of the thick part 41. Inclined in the direction. For this reason, the volume of the thick portion 41 decreases as it goes from the one end side in the axial direction to the other end side.

  Further, the axial direction of the thick portion 41 and the pair of tongue-like portions 42 are provided on one end surface in the axial direction of the thick portion 41 by a pressing convex portion 39 provided on the second upper mold 35. 42 and the arrangement direction of this thick part 41 {refer to the longitudinal direction, (C) in FIG. 1 and (B)-(a), (b) in FIG. 3 and (B)-( c), the direction perpendicular to {the front and back directions of (B)-(a) in FIG. 1, the vertical direction of (B)-(b) in FIG. The recessed portion 45 is formed so as to penetrate in the horizontal direction (B)-(c)}.

  In the case of this example, the volume of the first preliminary intermediate material 27 (and the material 26) is made larger than the volume of the space 40, and the surplus is released as a burr 46. Specifically, the burr 46 is allowed to escape radially outward from a portion between the lower surface of the second upper die 35 and the upper surface of the second lower die 36. For this reason, in the outer peripheral surface of the obtained second preliminary intermediate material 34, in the portion aligned with the contact position between the lower surface of the second upper mold 35 and the upper surface of the second lower mold 36 in the axial direction, A burr 46 is formed over the entire circumference.

  The burr 46 generated as described above is removed by performing trimming (trimming). In order to perform the trim processing, first, as shown in FIG. 4A, only the burr 46 formed on the second preliminary intermediate material 34 is sandwiched between a pair of holding dies 47a and 47b. To do. Specifically, of these two holding dies 47a and 47b, the upper holding dies 47a are pressed against the lower holding dies 47b by a pressing means such as a compression spring, so that the burrs 46 described above are pressed. Is clamped by the both holding dies 47a and 47b. Next, the second preliminary intermediate material 34 is pushed downward from above using a punching punch 48 whose tip end matches the shape of the one end surface in the axial direction of the second preliminary intermediate material 34. Thereby, only the burr 46 is removed from the second preliminary intermediate material 34 to obtain a first intermediate material 49 as shown in FIG. 1D and FIG. Since the first intermediate material 49 is obtained by removing only the burr 46 from the second preliminary intermediate material 34, the first intermediate material 49 and the second preliminary intermediate material 34 are used to form the thick portion 41. And the shape of a pair of tongue-like parts 42 and 42 becomes the same.

  Next, the first intermediate material 49 obtained as described above is subjected to a preliminary start-up process to obtain a second intermediate material 50 as shown in FIG. This preliminary start-up step is performed using a crushing punch 51, a counter punch 52, and a constraining die 53, as shown in FIG. Of these, the crushing punch 51 corresponds to the push-side punch described in the claims, and has a cross-sectional oval shape having a pair of outer flat surfaces 54, 54 on the outer peripheral surface thereof. The flat end surface 55 is made continuous by convex curved surface portions 56 and 56, respectively. With such a configuration, the shape of the tip portion of the crushing punch 51 is matched with the inner surface shape of the recessed portion 45 formed on one end surface in the axial direction of the thick portion 41.

  The counter punch 52 corresponds to the receiving side punch described in the claims, and a receiving concave surface portion 57 for supporting the other axial end surface of the thick portion 41 is formed on the upper surface which is the receiving surface. Provided. Among the width dimensions of the concave surface portion 57, the direction of arrangement of the pair of tongue portions 42, 42 and the thick portion 41 {the left-right direction of (A)-(a), (b) of FIG. The width dimension with respect to (A)-(c) front and back direction in the figure is larger than the width dimension of the other end portion in the axial direction of the thick portion 41 in the same direction (interval between the pair of flat surface portions 43, 43). It is getting bigger.

  A restraint hole 58 is provided in the central portion of the restraint mold 53 so as to penetrate in the axial direction. The constraining hole 58 has a pair of constraining surfaces 59 and 59 facing each other. These constraining surfaces 59 and 59 are in a state where the first intermediate material 49 is inserted inside the constraining hole 58. The first intermediate material 49 (the thick portion 41 and each tongue-like portion 42) is perpendicular to the axial direction and the arrangement direction of the thick portions 41 {FIG. 1 (D) and FIG. 6 (A). -It restrains from the front and back direction of (a), the up-down direction of (A)-(b) of FIG. 6, and the left-right direction of (A)-(c) of FIG. In the case of this example, the tongue portions 42 and 42 are restrained by flat surface portions provided on both side portions in the width direction among the restraining surfaces 59 and 59, and are provided in the center portion in the width direction. The thick-walled portion 41 is constrained by a partially cylindrical concave curved surface portion. However, the restriction on the thick portion 41 can be omitted.

  The operation of obtaining the second intermediate material 50 from the first intermediate material 49 using the crushing punch 51, the counter punch 52, and the constraining die 53 having the above-described configuration is performed as follows. . First, as shown in FIG. 6A, the first intermediate material 49 is placed on the upper surface of the counter punch 52 disposed inside the restraining hole 58. That is, the first intermediate material 49 is restrained by the pair of restraining surfaces 59, 59, and the other axial end of the thick portion 41 is placed on the receiving surface 57 of the counter punch 52. In the state where the first intermediate material 49 is set in this way, the central axis of the first intermediate material 49 and the central axes of the crushing punch 51, the counter punch 52, and the constraining die 53 coincide with each other. To do.

  Next, the crushing punch 51 is lowered from this state, and the tip of the crushing punch 51 is brought into contact with the bottom of the recessed portion 45 provided on one end surface in the axial direction of the thick portion 41. Then, as shown in FIGS. 6A to 6B, the crushing punch 51 is further lowered to compress the thick portion 41 between the crushing punch 51 and the counter punch 52 in the axial direction. Then, crush from one end side in the axial direction. As a result, while reducing the thickness of the thick portion 41 in the axial direction, a part of the metal material that constitutes the thick portion 41 is a portion that is separated from both the restraining surfaces 59, 59. It is made to flow to the said both tongue-like parts 42 and 42 side regarding a direction.

  As a result, both of the tongue-like portions 42 and 42 are arranged so that one side surface in the axial direction {the upper surface of (A)-(a) in FIG. 6, the surface of (A)-(b) in FIG. It is raised by a predetermined angle {θ in FIG. 1E} in a direction approaching the central axis 49. Thereby, as shown in FIG. 1E and FIG. 6B, a pair of inclined arm portions 60 that are inclined in the direction of increasing the interval between the inner side surfaces facing each other toward the tip portion, 60 is formed. Hereinafter, the reason why the both tongues 42 and 42 are raised will be described with reference to FIG.

  As described above, when the thick portion 41 is crushed in the axial direction between the crushing punch 51 and the counter punch 52, the metal material displaced is the two lingual portions 42 in the arrangement direction. , 42 side (left and right sides in FIG. 7). With regard to this flow, when considering the flow speed (moving speed) of the metal material on the one end side and the other end side in the axial direction of the thick part 41, the magnitude of the speed is expressed by the length of the arrow. The flow velocity at the end side is faster than the flow velocity at the one end side. In other words, the flow rate of the metal material is faster on the counter punch 52 side than on the crushing punch 51 side. For this reason, the metal material pushed away from the portion between both the punches 51 and 52 flows at a high speed along the receiving surface 57 of the counter punch 52, and the protrusion provided at the tip of the crushing punch 51. Using the vicinity of the curved surface portions 56, 56 as a base point, the both tongue-like portions 42, 42 are pushed upward in FIG. As a result, the two tongue-like portions 42, 42 rise in a direction in which one side surface in the axial direction approaches the central axis of the first intermediate material 49.

  As is clear from the above description, in the case of this example, a relatively large amount of metal material is pushed away from the portion between both the punches 51 and 52, and the both tongues 42 and 42 are raised. For this reason, in the case of this example, of the pair of inclined arm portions 60, 60, the respective base half portions 61, 61 are made of the metal material pushed away, and the respective leading half portions 62, 62 are formed. Is constituted by the both tongue-like portions 42, 42. In the case of this example, on the inner side surfaces of the both inclined arm portions 60, 60, the both tongue-like portions are provided between the base half portions 61, 61 and the tip half portions 62, 62. Part of the contours of 42 and 42 appears as stepped portions 63 and 63.

  In the case of this example, both the inclined arm portions 60 and 60 are formed, and at the same time, the base portion 13 constituting the first yoke 10 is formed between the base end portions of the both inclined arm portions 60 and 60. A substantially disc-shaped element base 64 for forming (see FIG. 14) is formed. In this manner, in the case of this example, the second intermediate material 50 including the both inclined arm portions 60 and 60 and the base portion 64 is obtained from the first intermediate material 49. As described above, in the case of the present example, when forming the inclined arm portions 60, 60 from the tongue portions 42, 42, the metal material pushed away from the portion between the punches 51, 52 is used. Use the resulting flow velocity difference. For this reason, as both the inclined arm portions 60 and 60 are formed, the bent end portions 25a and 25a of the base end portions of the inclined arm portions 60 and 60 and the element base portion 64 are formed on the outer portions in the bending direction. The tensile stress due to bending does not act.

  After obtaining the second intermediate material 50 as described above, subsequently, the both inclined arm portions 60, 60 are bent as a starting process. In the case of this example, as described above, the stepped portions 63 and 63 are provided on the inner side surfaces of the both inclined arm portions 60 and 60, and therefore this startup process is performed in two stages. First, in the first stage, only the base halves 61 and 61 of the both inclined arm portions 60 and 60 are bent in the same direction with respect to the element base portion 64 in a substantially right angle direction, as shown in FIG. A third intermediate material 65 is obtained. For this reason, in the case of this example, as shown in FIG. 8, by using the pressing punch 66, the split die 67, and the pedestal 68, the base half portions 61, 61 of the both inclined arm portions 60, 60 are used. Apply bending. Of these, the pushing punch 66 is the same as the crushing punch 51 (see FIGS. 6 and 7) used in the preliminary start-up process described above.

  The split die 67 is formed by combining an upper die 69a and a lower die 69b in series in the vertical direction, and the center of the upper die 69a is processed in a state of penetrating in the axial direction. A hole 70 is provided. The machining hole 70 includes a pair of constraining surfaces 59a and 59a and a pair of machining surface portions 71 and 71. Both of the restraining surfaces 59a and 59a are formed in the state in which the second intermediate material 50 is inserted inside the processing hole 70 in the same manner as in the case of the restraining die 53 (see FIG. 6). The intermediate material 50 is perpendicular to the axial direction of the element base 64 and the arrangement direction of the pair of inclined arm parts 60, 60 and the element base 64 {the front and back of (A)-(a) in FIG. Direction, vertical direction of (A)-(b), left-right direction of (A)-(c)}.

  In addition, each of the processed surface portions 71 and 71 has guide surface portions 72 and 72, throttle portions 73 and 73, and relief portions 74 and 74 in order from the opening side {upper side of (A)-(a) in FIG. 8}. Is provided. Of these, the guide surface portions 72, 72 are curved so as to increase the distance (opening width) between the two guide surface portions 72, 72 toward the opening side, and the second intermediate material 50 is used for the processing. In the state inserted in the hole 70, the outer surfaces of the both inclined arm portions 60, 60 are supported. The throttle portions 73 and 73 are vertical planes that continue smoothly below the guide surface portions 72 and 72. The distance (opening width) between the throttle portions 73 and 73 is the first yoke of the finished product. 10 is equal to the space | interval (width dimension) of the outer side surfaces of a pair of arm parts 14 and 14 (refer FIG. 14) which comprises 10. FIG. The relief portions 74, 74 are provided in a state of smoothly continuing below the throttle portions 73, 73, and the opening width between the relief portions 74, 74 is the same between the throttle portions 73, 73. It is slightly larger than the opening width.

  Further, a machining hole 70a is also provided in the central portion of the lower die 69b so as to penetrate in the axial direction, and this machining hole 70a also has a pair of constraining surfaces 59b and 59b and a machining surface portion. 71a, 71a. Both the restraining surfaces 59b and 59b are provided in a state of being continuous with the both restraining surfaces 59a and 59a. The processed surface portions 71a and 71a are also provided so as to be continuous with the processed surface portions 71 and 71, and the relief portions 74a and 74a provided in a state of being continuous with the relief portions 74 and 74 of the upper die 69a. And a pair of flat portions 75, 75 provided in a state of being continuous below both of the escape portions 74a, 74a.

  Further, the pedestal 68 has a support recess 76 on its upper surface for supporting the other axial end portion (lower end portion) of the element base portion 64 constituting the second intermediate material 50, and the dividing die 67. The upper die 69a has a processing hole 70 and a lower die 69b have a processing hole 70a that can move up and down and is provided with an upward elasticity.

  Using the pushing punch 66, the split die 67, and the pedestal 68 having the above-described configuration, the work of bending the inclined arm portions 60 and 60 is performed as follows. First, as shown in FIG. 8A, the second intermediate material 50 is inserted into the processing hole 70 of the upper die 69 a constituting the divided die 67. In this state, the outer side surfaces (lower surfaces) of the inclined arm portions 60 and 60 constituting the second intermediate material 50 are supported by the upper surfaces of the guide surface portions 72 and 72 constituting the processed surface portions 71 and 71. . Further, the other axial end portion of the element base 64 constituting the second intermediate material 50 is supported by a support recess 76 provided in the pedestal 68.

  Next, the pushing punch 66 disposed above is lowered, and the tip end portion of the pushing punch 66 is brought into contact with one end surface of the element base portion 64 in the axial direction. From this state, by further lowering the pushing punch 66, the base end portions of the two inclined arm portions 60, 60 are pushed into the two throttle portions 73, 73. In the case of this example, as shown in FIG. 8B, stepped portions 63, 63 formed on the inner side surfaces of the both inclined arm portions 60, 60 are provided on the outer peripheral surface of the pushing punch 66. The pushing punch 66 is lowered until it comes into contact with the outer flat surfaces 54a, 54a. As a result, the outer side surfaces of the base half portions 61, 61 of the both inclined arm portions 60, 60 are handled from the lower side toward the upper side by the two throttle portions 73, 73, and the inner side surfaces of the two outer side planes are handled. Press against 54a, 54a. That is, the base half portions 61 and 61 of the both inclined arm portions 60 and 60 are raised upward while applying a compressive force between the pressing punch 66 and the both throttle portions 73 and 73. Thereby, the base half portions 61 and 61 of the both inclined arm portions 60 and 60 are bent in a substantially right angle direction with respect to the element base portion 64 in a state where the tensile stress acting on the bent portions 25a and 25a is kept low. I can do things. As a result, the third intermediate material 65 as shown in FIG.

  After bending the base half portions 61 and 61 of the both inclined arm portions 60 and 60 as described above, the first half of the both inclined arm portions 60 and 60 is used as the second stage of the start-up process. The parts 62 and 62 are bent to obtain a fourth intermediate material 77 as shown in FIG. For this reason, in the case of this example, after the pushing punch 66 is extracted from the portion between the inner side surfaces of the two base halves 61, 61, as shown in FIG. The tip of another pressing punch 66a is inserted into The push punch 66a, like the push punch 66, has a pair of outer flat surfaces 54a, 54a. The push punch 66a extends axially at the center in the width direction of both the outer flat surfaces 54a, 54a, and the both end halves 62 , 62 are provided with concave grooves 78, 78 having a width dimension slightly larger than the width dimension of the base halves 61, 61 (but smaller than the width dimension of the two base halves 61, 61). For this reason, as shown in FIG. 9A, in the state in which the tip end portion of the pressing punch 66a is inserted between the inner side surfaces of the base half portions 61, 61, both the base half portions 61 are arranged. , 61 and the bottom of both concave groove portions 78, 78 are separated from each other (by the groove depth of the concave groove portion 78). 9A shows the pressing punch 66a until the stepped portions 63, 63 formed on the inner side surfaces of the inclined arm portions 60, 60 come into contact with the bottoms of the concave groove portions 78, 78. It shows a state where is lowered.

  Then, by further lowering the pressing punch 66a from a state in which the tip end portion of the pressing punch 66a is in contact with one end surface in the axial direction of the element base portion 64, the first half portions of the both inclined arm portions 60, 60 are provided. 62 and 62 are pushed into the diaphragm portions 73 and 73. At this time, the outer side surfaces of the front half portions 62 and 62 of the both inclined arm portions 60 and 60 are guided by the throttle portions 73 and 73 while being supported by the both guide surface portions 72 and 72. Accordingly, the inner side surfaces are pressed against the bottom portions of the both concave groove portions 78 and 78 while the outer side surfaces of the both end half portions 62 and 62 are handled by the both throttle portions 73 and 73. Thereby, the front half portions 62 and 62 of the both inclined arm portions 60 and 60 are bent to a state where they are located on an extension line of the both base half portions 61 and 61. As a result, the inclined arm portions 60, 60 are substantially parallel over the entire range from the base end portion to the tip end portion, and a pair of arm portions 14, 14 are formed.

  In the case of this example, after forming the fourth intermediate material 77 as described above, the ends of the arms 14 and 14 are punched to support the ends of the cross shaft 12. The circular holes 16 and 16 (see FIG. 14) are formed concentrically with each other. Further, a punching process is applied to the center of the base portion 64 formed between the base end portions of the both arm portions 14 and 14 so as to externally fix and fix the end portion of the rotating shaft. (See FIG. 14). Thereby, the substantially annular base 13 (see FIG. 14) can be formed from the element base 64, and the first yoke 10 (see FIG. 14) as a finished product can be obtained.

  As described above, in the case of the method for manufacturing a universal joint yoke according to the present example, the pair of arm portions 14 and 14 can be moved stepwise (tongue portion 42 → tilted arm 42) by incorporating a preliminary start-up process. Part 60 → arm part 14), and in this preliminary start-up step, the inclined arm part 60 is not bent from the tongue-like part 42 but subjected to tensile stress, as shown in FIG. It can be formed by utilizing the difference in flow rate of the metal material due to compression. That is, in the case of this example, the thick portion 41 constituting the first intermediate material 49 is compressed between the crushing punch 51 and the counter punch 52 so as to be pushed away from the portion between these punches 51, 52. The two inclined arm portions 60 and 60 (the base half portions 61 and 61 thereof) can be formed by the difference in flow velocity generated in the obtained metal material. For this reason, when forming these both inclined arm parts 60 and 60, tensile stress does not act on the bending parts 25a and 25a of the base end part of these both inclined arm parts 60 and 60 and the said base 64. . In the case of this example, the base half portions 61 and 61 of the both inclined arm portions 60 and 60 are pressed against the pressing punch 66 in the rising step (first stage). While handling the outer surface, it starts up with a compressive force applied. Thus, in the case of this example, by adopting the preliminary start-up process and the start-up process, the both tongue-shaped portions 42 and 42 are raised step by step, and in the start-up process, the both slopes are raised. In order to raise the base half parts 61 and 61 of the arm parts 60 and 60 in the state which applied the compression force, the bending part 25a of these inclination arm parts 60 and 60 (thru | or the arm parts 14 and 14) and the element base part 64 is carried out. 25a, the tensile stress acting on 25a can be kept sufficiently small. As a result, it is possible to effectively prevent cracks and cracks due to tensile stress from occurring in the bent portions 25a and 25a.

  In particular, in the case of this example, as shown in FIG. 5 and the like, the volume of the thick portion 41 constituting the first intermediate material 49 is reduced from the one end side in the axial direction toward the other end side. Therefore, the metal material that obstructs the flow is large on one end side in the axial direction of the thick portion 41 and decreases on the other end side. For this reason, the difference in the flow rate of the metal material generated between the crushing punch 51 side and the counter punch 52 side can be further increased. For this reason, the inclination angle of both the inclined arm portions 60, 60 (the rising angle of the tongue portions 42, 42) can be further increased.

  In the case of this example, a recessed portion 45 is provided on one end surface in the axial direction of the thick portion 41. In other words, both side portions of one end surface in the axial direction are projected in a bank shape with respect to the central portion. For this reason, the metal material (metal material that obstructs the flow) existing in the moving direction of the metal material is not provided on one end side in the axial direction of the thick portion 41, and the concave portions 45 as described above are not provided. It can be increased compared to the case of not projecting. For this reason, the flow rate of the metal material on the crushing punch 51 side can be further reduced, and the inclination angles of the two inclined arm portions 60 and 60 can be further increased. Accordingly, when the pair of arm portions 14 and 14 are formed from the both inclined arm portions 60 and 60, the amount of bending deformation of both the inclined arm portions 60 and 60 can be reduced, and the both inclined arm portions 60 and 60 can be reduced. The tensile stress acting on the outer side in the bending direction of the bent portions 25a, 25a between the portion 60 (or the arm portion 14) and the element base portion 64 can be effectively suppressed.

Further, in the case of this example, as shown in FIG. 1, the thickness T ₄₁ in the axial direction of the thick portion 41 is sufficiently larger than the thickness T ₄₂ of the both tongue portions 42, _42. large (T ₄₁ »T _42), and the other axial end portion of the thick portion 41 (lower end in FIG. 1), largely from the other axial side of the Ryozetsu shaped portions 42 and 42 (the lower surface in FIG. 1) It is protruding. For this reason, it is possible to secure a large margin for crushing by the crushing punch 51 and to maintain a state in which a speed difference has occurred with respect to the flow of the metal material. Further, the base 64 formed in the portion between the crushing punch 51 and the counter punch 52 can be sufficiently worked and hardened.

  Further, in the case of this example, the first half portions 62 and 62 of the both inclined arm portions 60 and 60 are constituted by the tongue-like portions 42 and 42, respectively, thereby forming both the inclined arm portions 60 and 60. The amount of flow of the metal material, which is necessary for this, is reduced. That is, as in the case of the manufacturing method described in Patent Document 3 described above, the amount of flow of the metal material can be reduced compared to the case where the entire arm portion is formed by the flow of the metal material by backward extrusion. For this reason, in the case of this example, the press load required when performing a preliminary | backup start-up process can be suppressed smaller. For this reason, the enlargement of equipment can be prevented.

Further, in the case of this example, as in the case of the invention described in Patent Document 1 described above, the thickness of the pair of arm portions 14 and 14 and the base portion 13 constituting the first yoke 10 of the finished product is the same. Since the thickness of the material 20 made of metal is not restricted, the thickness of the pair of arm portions 14 and 14 and the base portion 13 can be ensured to ensure the strength. The first yoke 10 that can be sufficiently obtained can be manufactured.
As described above, according to the manufacturing method of this example, sufficient strength can be secured, and further, it is possible to prevent the occurrence of defects such as cracks and cracks in the bent portion between the base and the pair of arms. The yoke can be manufactured without increasing the size of the equipment.
In the case of this example, since the step portions 63 and 63 exist on the inner side surfaces of the both inclined arm portions 60 and 60, the start-up process was performed in two stages. When 63 and 63 do not exist, the pair of arm portions 14 and 14 can be formed from the both inclined arm portions 60 and 60 by the first stage of the start-up process described above.

[Second Example of Embodiment]
A second example of the embodiment of the present invention corresponding to claims 1, 2, 4, and 6 will be described with reference to FIG. In the case of this example, the thickness of the first intermediate material 49 is designed by devising the surface properties of the tip of the crushing punch 51 and the receiving surface of the counter punch 52a used in the preliminary start-up process. The frictional force acting between the other axial end surface of the portion 41 and the receiving surface of the counter punch 52a acts between the axial one end surface of the thick portion 41 and the tip end portion of the crushing punch 51. It is made smaller than the friction force.

FIG. 10 is a graph showing a result obtained by computer simulation of the inclination angle of the inclined arm portion 60 when the friction coefficient of the receiving surface portion 57a of the counter punch 52a is changed in order to confirm the effect of the invention according to this example. Show. FIG. 10A corresponds to the product of this example, and shows the result when the coefficient of friction of the concave surface portion 57a of the counter punch 52a is reduced (the lap surface). On the other hand, (B) of the figure is a comparative product, and shows the result when the coefficient of friction of the receiving concave surface portion 57a is increased (rough surface). As apparent from the comparison between the inclination angles θ ₁ and θ _{2 of} the inclined arm portion 60 shown in FIGS. 10A and 10B, the coefficient of friction of the concave surface portion 57a of the counter punch 52a is as follows. When the angle is small, the inclination angle becomes large. In this way, increasing the tilt angle means that instead of leaving the coefficient of friction of the concave surface part 57a as it is (or reducing the coefficient of friction of the concave surface part 57a), the tip of the crushing punch 51 This can also be done by increasing the friction coefficient.

That is, when considering the flow speed of the metal material pushed away from the portion between the crushing punch 51 and the counter punch 52a, in the case of FIG. 10A, the flow speed on the crushing punch 51 side, because the difference between the counter punch 52a side of the flow rate becomes larger, the inclination angle theta ₁ of the respective inclined arms 60 increases. On the other hand, in the case of FIG. 10B, the difference between the flow speed on the crushing punch 51 side and the flow speed on the counter punch 52a side is reduced, so that the inclined arm portions 60 are inclined. The angle θ ₂ is reduced.

  As is clear from the results of the computer simulation as described above, in the case of this example, compared with the case of the first example of the above-described embodiment, the inclination angles of the pair of inclined arm portions 60 (each tongue shape) The rising angle of the portion 42 can be increased. For this reason, when these two inclined arm portions 60 are bent to form a pair of arm portions 14 and 14 (see FIGS. 1 and 14), both the inclined arm portions 60 (or the arm portions 14 and 14). ) And the base portion 64, the tensile stress acting on the outer portion in the bending direction of the bent portion 25a can be further reduced. For this reason, it can prevent more effectively that a crack and a crack arise in each these bending part 25a.

  In addition, as a concrete means for reducing the friction coefficient of the receiving surface (receiving concave portion 57a) of the counter punch 52a, for example, the counter punch 52a is made of die steel (SKD11, SKD61) or high speed steel (SKH51). , High-speed steel), cemented carbide, etc., and surface treatment such as TiCN or lapping may be applied to the surface.

On the other hand, as a specific means for increasing the friction coefficient of the tip portion (tip surface 55, convex curved surface portion 56) of the crushing punch 51, the tip portion remains as a cutting surface, or the tip It is conceivable to perform a grinding process using a grindstone having a large particle size in the part. However, if the surface roughness of the crushing punch 51 is excessively increased, wear tends to occur on one end surface in the axial direction of the thick portion 41 where the tip of the crushing punch 51 comes into contact. For this reason, as long as both the inclined arm portions 60 can be tilted to a necessary extent only by reducing the friction coefficient of the counter punch 52a, the tip portion of the crushing punch 51 is subjected to a surface treatment such as a lapping treatment. Things are preferable.
Other processes and operations / effects are the same as those in the first example of the embodiment described above.

[Third example of embodiment]
A third example of the embodiment of the present invention corresponding to claims 1, 2, 4, and 5 will be described with reference to FIG. In the case of this example, the curvature radius of the cross-sectional shape of the convex curved surface portion 69a constituting the tip portion of the crushing punch 51a is the portion with which each convex curved surface portion 69a abuts during the preliminary start-up process. The radius of curvature of the cross-sectional shape of the portion closer to both ends in the width direction of the recessed portion 45 provided on one end surface in the axial direction of the thick portion 41 constituting the one intermediate material 49 is made smaller.

  FIG. 11 shows a change in the radius of curvature of the cross-sectional shape of the convex curved surface portion 69a in relation to the radius of curvature of the cross-sectional shape of the portion near both ends of the recessed portion 45 in order to confirm the effect of the invention according to this example. The result which calculated | required the inclination-angle of the inclination arm part 60 in the case of having been obtained by computer simulation is shown. In this computer simulation, the curvature radius of the cross-sectional shape of the recessed portion 45 near the both ends in the width direction was set to 9 mm (R9). Moreover, the arrow shown in the figure has shown the frictional force which acts on the metal material which flows through the crushing punch 51a side, The length has shown the magnitude | size of the frictional force. Similarly, the oval and crescent shaped portions indicate the distribution of the magnitude of the surface pressure acting on the recessed portion 45.

(A) in FIG. 11 corresponds to the embodiment product, and the radius of curvature of the cross-sectional shape of each convex curved surface portion 69a is smaller than the radius of curvature of the cross-sectional shape of the portion near both ends of the concave portion 45 {4 mm. (R4)} shows the result. On the other hand, (B) of the figure is a comparative product, and shows the result when the radius of curvature of the convex curved surface portion 69a is the same as the radius of curvature of the sectional shape of the recessed portion 45 (R9). As is clear from the comparison between the inclination angles θ ₁ and θ _{2 of} the inclined arm portion 60 shown in FIGS. 11A and 11B, the radius of curvature of the cross-sectional shape of each convex curved surface portion 69a is as follows. When the radius of curvature of the cross-sectional shape of the recessed portion 45 is smaller, the inclined angle θ ₁ of each inclined arm portion 60 becomes larger.

  As shown in FIG. 11A, the reason why the inclination angle increases is as follows. That is, when the curvature radius of the cross-sectional shape of the both convex curved surface portions 69a is small, the tip portion of the crushing punch 51a and the bottom portion of the recessed portion 45 provided on one end surface in the axial direction of the thick portion 41 are formed. When abutting, the surface pressure between the both convex curved surface portions 69a and the portions near the both ends in the width direction of the recessed portion 45 is increased. For this reason, the frictional force which acts on the said contact part becomes large. Therefore, among the metal material pushed away from the portion between the crushing punch 51a and the counter punch 52, the metal material flowing on the crushing punch 51a side is easily retained at the contact portion. As a result, the difference between the flow speed of the metal material flowing on the crushing punch 51a side and the flow speed of the metal material flowing on the counter punch 52 side can be increased, and the inclined arm portions 60 can be inclined. The angle can be increased.

  On the other hand, when the curvature radius of the cross-sectional shape of the biconvex curved surface portion 69a is the same (or larger) than the curvature radius of the cross-sectional shape of the concave portion 45, the biconvex curved surface portion 69a and the concave portion 45 are provided. The surface pressure of the abutting portion with the portion near both ends in the width direction is reduced. For this reason, the frictional force which acts on the said contact part becomes small. Accordingly, among the metal material pushed away from the portion between the crushing punch 51a and the counter punch 52, the metal material flowing on the crushing punch 51a side is less likely to stay at the contact portion. As a result, the difference between the flow rate of the metal material flowing on the crushing punch 51a side and the flow rate of the metal material flowing on the counter punch 52 side is reduced, and the inclination angle of the both inclined arm portions 60 is reduced. .

As is clear from the results of the computer simulation as described above, in the case of this example, compared to the case of the first example of the above-described embodiment, the inclination angle of each pair of inclined arm portions 60 (each tongue shape) The rising angle of the portion 42 can be increased. For this reason, when these two inclined arm portions 60 are bent to form a pair of arm portions 14 and 14 (see FIGS. 1 and 14), both the inclined arm portions 60 (or the arm portions 14 and 14). ) And the base portion 64, the tensile stress acting on the outer portion in the bending direction of the bent portion 25a can be further reduced. For this reason, it can prevent effectively that a crack and a crack arise in each these bending part 25a.
Other processes and operations / effects are the same as those in the first example of the embodiment described above.

[Fourth Example of Embodiment]
A fourth example of the embodiment of the present invention corresponding to claims 1 and 3 will be described with reference to FIG. In the case of this example, as the first intermediate material 49a, the thick portion 41a has a substantially disk shape, and the thick portion 41a is positioned at one end side in the axial direction (upper end side in FIG. Each of the thick-walled portions 41a is provided with a pair of tongue-like portions 42 and 42 in a state of extending outward in the diameter direction. Particularly in the case of this example, of the other axial end face of the thick part 41a, both ends of the pair of tongue-like parts 42 and 42 and the arrangement direction of the thick part 41a (the left-right direction in FIG. 12). Similarly, a pair of bulging portions 79 and 79 projecting toward the other end in the axial direction (lower end in FIG. 12) as compared with the intermediate portion are provided. In the case of this example, these both bulging portions 79, 79 are semi-cylindrical. The first intermediate material 49a having such a shape is formed using a press die different from the press die (second upper die 35 and second lower die 36) as shown in FIG. .

  When the first intermediate material 49a having such a configuration is subjected to a preliminary start-up process, as shown in FIG. 12A, the other axial end surface of the thick portion 41a constituting the first intermediate material 49a The both bulging portions 79 and 79 provided on the counter punch 52 are placed on the receiving surface 57 of the counter punch 52. And the crushing punch 51 arrange | positioned upwards is dropped, and the front-end | tip part is contact | abutted to the axial direction one end surface of the said thick part 41a. From this state, the crushing punch 51 is further lowered, the thick portion 41 is compressed in the axial direction between the crushing punch 51 and the counter punch 52, and is crushed from one end side in the axial direction.

In the case of this example, when the thick portion 41a is compressed between the punches 51 and 52, first, as shown in FIG. As a base point, the two tongue-like portions 42 and 42 rise by a predetermined angle θ _{3 in a} direction in which one axial side surface (the upper surface in FIG. 12) approaches the central axis of the first intermediate material 49a. That is, the tongue portions 42 and 42 can be raised (bent) by a bending moment generated by the downward force of the crushing punch 51 and the upward reaction force of the bulging portions 79 and 79.

In this manner, when the both tongues 42 and 42 are raised by a predetermined angle θ ₃ , the crushing punch 51 is further lowered to completely crush both the bulging portions 79 and 79. As a result, the metal materials constituting the bulging portions 79 and 79 are caused to flow toward the both tongue-like portions 42 and 42 with respect to the arrangement direction, and as shown in FIG. 42 and 42 are further raised (inclination angle θ ₄ ). In this way, in the case of this example, a pair of inclined arm portions 60a, 60a can be formed from these tongue portions 42, 42, and the second intermediate material 50a can be obtained.
The reason why the tongues 42 and 42 are raised by flowing the metal material constituting the bulges 79 and 79 as described above is the same as in the first example of the embodiment described above. It is.

As described above, in the case of this example, by providing the pair of bulging portions 79, 79 on the other axial end surface of the thick portion 41a, in addition to the difference in the flow rate of the metal material, the bending moment Thus, the two tongue portions 42 can be raised. For this reason, the rising angle based on the difference in the flow velocity of the metal material can be reduced (θ ₄ −θ ₃ can be achieved). Therefore, in the case of this example, the flow amount of the metal material can be suppressed as compared with the case of the first example of the embodiment described above. As a result, the press load can be further reduced, and the increase in size of the equipment can be effectively prevented. In the case of this example, as described above, in order to raise the tongue portions 42, 42 by a bending moment, the base end portions of the tongue portions 42, 42 and the thick portion 41a A slight tensile stress due to bending acts on the bent portions 25b and 25b. Therefore, in the case of this example, the size of both the bulging portions 79, 79 (from the other axial end surface of the thick portion 41a) is within a range in which the occurrence of cracks and cracks due to such tensile stress can be suppressed. The amount of protrusion).
Other processes and operations / effects are substantially the same as those in the first example of the embodiment described above.

Sectional drawing which shows the 1st example of embodiment of this invention in process order. Similarly, the steps of making the preliminary first intermediate material from the material are shown in the order of (A) and (B). Of (A) and (B), (a) is a front view, and (b) is a diagram of (a). XX sectional drawing. Similarly, the steps of making the preliminary second intermediate material from the preliminary first intermediate material are shown in the order of (A) and (B), and among (A) and (B), (a) is a cross section in the longitudinal direction of each material. The figure, (b) is XX sectional drawing of (a), (c) is YY sectional drawing of (a). Similarly, the steps of making the first intermediate material from the preliminary second intermediate material are shown in the order of (A) and (B), and among (A) and (B), (a) is a sectional view in the longitudinal direction of each material. (B) is XX sectional drawing of (a), (c) is YY sectional drawing of (a). The 1st intermediate material is shown similarly, (A) is a front view, (B) is a top view, (C) is a bottom view, (D) is a right view. Similarly, the steps of making the second intermediate material from the first intermediate material are shown in the order of (A) and (B), and among (A) and (B), (a) is a sectional view in the longitudinal direction of each material, (B) is the X arrow directional view of (a), (c) is YY sectional drawing of (a). Sectional drawing for demonstrating the reason a tongue-like part rises similarly. Similarly, the steps of making the third intermediate material from the second intermediate material are shown in the order of (A) and (B), and among (A) and (B), (a) is a sectional view in the longitudinal direction of each material, (B) is the X arrow directional view of (a), (c) is YY sectional drawing of (a). Similarly, the steps of making the fourth intermediate material from the third intermediate material are shown in the order of (A) and (B), and among (A) and (B), (a) is a cross-sectional view regarding the longitudinal direction of each material, (B) is the X arrow directional view of (a), (c) is YY sectional drawing of (a). The figure for demonstrating the preliminary start-up process of the 2nd example. The figure for demonstrating the preliminary start-up process of the 3rd example. The figure which shows the preliminary start-up process of the 4th example in order. The fragmentary sectional view which shows the state which incorporated the universal joint yoke used as the object of the manufacturing method of this invention in the steering device for motor vehicles. FIG. 14 is an enlarged cross-sectional view of a portion of FIG. The figure which shows the manufacturing process of the yoke for universal joints described in patent document 1. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Steering wheel 2 Steering shaft 3 Steering column 4 Steering force auxiliary device 5 Tie rod 6 Steering gear unit 7a, 7b Universal joint 8 Intermediate shaft 9 Input shaft 10 First yoke 11 Second yoke 12 Cross shaft 13 Base portion 14 Arm portion 15 Joint hole 16 circular hole 17 base portion 18 arm portion 19 bearing cup 20 material 21 first intermediate material 22 element base portion 23 tongue-shaped portion 24 second intermediate material 25, 25a, 25b bent portion 26 material 27 first preliminary intermediate material 28 first upper mold 29 1st lower mold | type 30a, 30b Concave-curved surface part 31a, 31b Plane part 32 Disc part 33 Raw tongue-shaped part 34 2nd preliminary | backup intermediate material 35 2nd upper mold | type 36 2nd lower mold | type 37 Thick part forming recessed part 38 Tongue | Convex part forming part 39 Indentation convex part 40 Space 41, 41a Thick part 42 Tongue part 43 Flat Surface portion 44 Convex arc surface portion 45 Recessed portion 46 Burr 47a, 47b Holding die 48 Punch punch 49, 49a First intermediate material 50, 50a Second intermediate material 51, 51a Crushing punch 52, 52a Counter punch 53 Restrained die 54, 54a Outer plane 55 End surface 56 Convex curved surface part 57, 57a Receiving surface part 58 Restraint hole 59, 59a, 59b Restraint surface 60, 60a Inclined arm part 61 Base half part 62 Front half part 63 Step part 64 Element base part 65 Third intermediate material 66, 66a Indentation punch 67 Split die 68 Base 69a Upper die 69b Lower die 70, 70a Processing hole 71, 71a Processing surface portion 72 Guide surface portion 73 Restriction portion 74, 74a Escape portion 75 Flat portion 76 Support recess 77 Fourth intermediate material 78 Concavity Groove part 79 bulge part

Claims (6)

  For a universal joint having a substantially annular base for coupling and fixing to the end of the rotating shaft, and a pair of arms bent in a direction substantially perpendicular to the same direction from two positions opposite to the diameter in the base. The yoke is made of a metal round bar material, and is a method for manufacturing a universal joint yoke, which is obtained by subjecting this material to plastic working, and a substantially cylindrical or substantially disc-shaped thick portion, A pair of tongues that are thinner than the thick part and are plate-like tongues provided in a state extending radially outward of the thick part at one axial end side of the thick part. The first intermediate material provided with the shape portion is constrained from both sides in the direction perpendicular to the axial direction of the thick portion and the arrangement direction of the pair of tongue-like portions and the thick portion. The axial part of this thick part is compressed in the axial direction from one axial end side between the push side punch and the receiving side punch. By reducing the thickness of the metal material, a part of the metal material constituting the thick part is caused to flow toward the both tongues with respect to the arrangement direction. A pair that rises in a direction approaching the central axis of one intermediate material, and at least each tip portion is constituted by each of the above tongue-like portions, and is inclined in a direction that widens the interval between the inner side surfaces facing each other toward the tip portion. And forming a second intermediate material by forming a substantially disc-shaped element base for forming the base between the base ends of the two inclined arm portions at the same time. Bending process and bending the two inclined arm portions until the pair of inclined arm portions are parallel or substantially parallel to form the pair of arm portions from the two inclined arm portions. Manufacturing a universal joint yoke Law.   The thick-walled portion constituting the first intermediate material is substantially cylindrical, and the outer peripheral surface shape of the thick-walled portion is a shape in which a pair of flat surface portions and a pair of convex arc surface portions are alternately continued in the circumferential direction. These two flat surface portions are provided in a portion where the circumferential phase coincides with the pair of tongue-shaped portions, and the axially other end side of the thick-walled portion from the base end edge portion of each tongue-shaped portion. The method for manufacturing a universal joint yoke according to claim 1, wherein the yoke is inclined in a direction approaching the central axis of the thick-walled portion as it goes toward.   The thick part constituting the first intermediate material is substantially disc-shaped, and the same is applied to both ends of the other end face in the axial direction of the thick part with respect to the arrangement direction of the pair of tongues and the thick part. The method for manufacturing a universal joint yoke according to claim 1, wherein a pair of bulging portions projecting toward the other axial end side from the intermediate portion are provided.   On one end surface in the axial direction of the thick part constituting the first intermediate material, there is a recessed part that penetrates in the direction perpendicular to the axial direction of the thick part and the arrangement direction of the pair of tongues and the thick part. The universal joint yoke according to any one of claims 1 to 3, wherein the universal punch yoke is provided, and a front end portion of the push side punch is brought into contact with a bottom portion of the recessed portion during the preliminary start-up step. Production method.   A pair of outer planes are provided on the outer peripheral surface of the push side punch, and a convex curved surface portion is provided between the both outer planes and the front end surface of the push side punch. The curvature radius of the shape is smaller than the curvature radius of the cross-sectional shape of the portion near the both ends in the width direction of the recessed portion, which is a portion where each convex curved surface portion abuts during the preliminary start-up step. Manufacturing method of universal joint yoke.   Friction force acting between the axial end of the thick part constituting the first intermediate material and the receiving punch is a friction force acting between the axial end of the thick part and the push punch. The manufacturing method of the yoke for universal joints as described in any one of Claims 1-5 smaller than this.

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