WO2015008647A1

WO2015008647A1 - Yoke for universal joint and production method therefor

Info

Publication number: WO2015008647A1
Application number: PCT/JP2014/068079
Authority: WO
Inventors: 拓真仲村; 祥史黒川
Original assignee: 日本精工株式会社
Priority date: 2013-07-16
Filing date: 2014-07-07
Publication date: 2015-01-22
Also published as: CN104620005B; CN104620005A; JP5910758B2; JPWO2015008647A1

Abstract

A yoke for a universal joint, having provided in a coupling hole (14a): a press-fit hole section (21) for press-fitting an end section of a shaft, provided between a center section and another end section in the axial direction; and a non-press-fit hole section (22) having a larger diameter than the press-fit hole section (21) and not having the shaft end section press-fitted therein, provided at one end section in the axial direction.

Description

Universal joint yoke and manufacturing method thereof

The present invention relates to a yoke that forms a cross shaft type universal joint (cardan joint) for connecting the rotating shafts constituting the steering device so that torque can be transmitted, and an improvement of the manufacturing method thereof.

The automobile steering device is configured as shown in FIG. The movement of the steering wheel 1 operated by the driver is transmitted to the input shaft 6 of the steering gear unit 5 via the steering shaft 2, the universal joint 3a, the intermediate shaft 4, and another universal joint 3b. The rack and pinion mechanism built in the steering gear unit 5 pushes and pulls the pair of left and

right tie rods

7 and 7 so that the right and left pair of steered wheels have an appropriate steering angle corresponding to the operation amount of the steering wheel 1. It is configured to grant.

As the

universal joints

3a and 3b to be incorporated in such a steering apparatus, generally, a cross shaft type universal joint called a cardan joint as illustrated in FIG. 12 is widely used. Each of the

universal joints

3a and 3b includes a pair of

yokes

8a and 8b (8c and 8d), and a cross shaft 9 that pivotably connects the tip ends of the pair of

yokes

8a and 8b (8c and 8d). Prepare. The base of one yoke 8a (8c) is coupled and fixed to the rear end of the male shaft 10 (the front end of the female shaft 11 which is a hollow shaft) that is a solid shaft constituting the intermediate shaft 4 so as to transmit torque. The The base portion of the other yoke 8b (8d) is coupled and fixed to the front end portion (rear end portion of the input shaft 6) of the steering shaft 2 so that torque can be transmitted. The intermediate shaft 4 is formed by combining a male shaft 10 and a female shaft 11 so that torque can be transmitted and relative displacement in the axial direction can be achieved.

FIG. 13 shows a first example of a conventional structure of a yoke called a vertical insertion type that can be used as one

yoke

8a, 8c constituting the

universal joints

3a, 3b. The yoke 8e shown in FIG. 13 is described in Patent Document 1 or the like, and is widely known from the past, by applying a stamping and bending process to a metal plate material such as a steel sheet, or It is made in one piece by forging or punching a metal material such as a steel round bar. Such a yoke 8e includes a base portion 12 and a pair of

arm portions

13 and 13. The base 12 is formed in a substantially annular shape, and has a coupling hole 14 formed in the axial direction (vertical direction in FIG. 13) at the center in the radial direction. The coupling hole 14 is a circular hole whose inner peripheral surface is a simple cylindrical surface, or a serration hole formed by forming female serrations on the inner peripheral surface of such a circular hole. The

arm parts

13 and 13 are provided in a state extending from two positions on the opposite side in the radial direction of the base part 12 to one axial side (upper side in FIG. 13). Concentric

circular holes

15 and 15 are formed at the distal ends of the

arm portions

13 and 13, respectively. With the cross shaft universal joint assembled, the bottomed cylindrical bearing cups 16 and 16 (see FIG. 12) are fitted and fixed in the

circular holes

15 and 15, respectively. At the same time, the end portions of the cross shaft 9 (see FIG. 12) are rotatably supported in the

bearing cups

16 and 16 via a plurality of

needles

17 and 17, respectively. The inner side surfaces of the

arm portions

13 and 13 facing each other and the one side surface in the axial direction of the base portion 12 are smoothly continuous by concave curved surfaces, respectively.

When the end portion of the shaft 18 formed in a columnar shape or a circular tube shape such as an intermediate shaft is coupled to the base portion 12 of the yoke 8e as described above, first, the end portion of the shaft 18 is coupled to the base portion 12. It press-fits into the hole 14 (it fits with an interference fit). When the coupling hole 14 is a serration hole, male serration is formed on the outer peripheral surface of the end portion of the shaft 18. Then, with the press-fitting, the male serration is engaged with the serration hole with a tightening margin. Next, welding is performed on the corner between the other side surface in the axial direction of the base portion 12 (the lower side surface in FIG. 13) and the outer peripheral surface of the shaft 18, thereby welding metal 19 between both surfaces. As a result, the end portion of the shaft 18 is coupled and fixed to the base portion 12 of the yoke 8e so that torque can be transmitted.

FIG. 14 shows a second example of a conventional structure of a vertically inserted yoke. In the case of the yoke 8f of the second example of the conventional structure, in the base portion 12a, in the peripheral portion of the other end portion in the axial direction of the coupling hole 14, compared to the peripheral portion near the other end portion in the axial direction of the coupling hole 14. An overhanging ring portion 20 having a reduced radial thickness is provided. The overhang ring portion 20 and the shaft 18 are welded in a state where the weld metal 19 is passed between the outer peripheral surface and the front end surface of the overhang ring portion 20 and the outer peripheral surface of the shaft 18.

In the case of the second example having such a conventional structure, the overhanging ring portion 20 can be intensively heated when performing the above-described welding (the heat applied to the overhanging ring portion 20 is applied to the shaft of the base portion 12a). Can be difficult to disperse in the middle part of the direction). For this reason, the amount of penetration of the outer peripheral surface and the front end surface of the overhang ring portion 20 can be increased, and the strength of the welded portion can be easily secured correspondingly.

In the case of each conventional structure described above, the entire coupling hole 14 is a press-fitting hole for press-fitting the end of the shaft 18. A large hoop stress (a tensile stress in the circumferential direction) is generated in the surface layer portion of the coupling hole 14 as the end portion of the shaft 18 is press-fitted. On the other hand, a cross-shaft type is provided on the peripheral edge of the one end opening of the coupling hole 14 (P portion in FIGS. 13 and 14), which is a continuous portion between one axial side surface of the base 12 (12a) and the inner peripheral surface of the coupling hole 14. When torque is transmitted with the universal joint assembled, stress concentration due to torsion occurs. That is, in each of the conventional structures described above, a large hoop stress due to press-fitting and a stress concentration based on torsion are generated on the peripheral edge (P portion) of the one end opening of the coupling hole 14 in an overlapping manner. The maximum value increases. Therefore, the design for securing the strength of the base 12 (12a) becomes difficult.

Japanese Unexamined Patent Publication No. 2013-24369

In view of the circumstances as described above, the present invention generates a large hoop stress in the surface layer portion of the press-fitting hole portion of the coupling hole and presses the end portion of the shaft into the coupling hole, and at the time of torque transmission, Invented to realize a structure capable of easily designing for securing strength and a manufacturing method thereof for a universal joint yoke in which stress concentration due to torsion occurs at the peripheral edge of one end opening of the coupling hole. .

The above object of the present invention is achieved by the following configurations.
(1) an annular base portion having a coupling hole formed in the axial direction at a radial center portion;
A pair of arms provided in a state of extending in one axial direction from two positions opposite to the radial direction of the base;
A universal joint yoke comprising:
The coupling hole has at least an axially intermediate portion of the axially intermediate portion or the other end portion as a press-fit hole portion for press-fitting an end portion of the shaft, and is adjacent to the press-fit hole portion in the axial direction. A universal joint yoke in which one end in the axial direction is a non-press-fit hole portion having a diameter larger than that of the press-fit hole portion and into which the end portion of the shaft is not press-fitted.
(2) The universal joint yoke according to (1), wherein the base and the shaft are welded.
(3) The universal joint yoke according to (1) or (2), wherein a chamfered portion is provided in a continuous portion between the inner peripheral surface of the non-press-fit hole portion and one axial side surface of the base portion.
(4) Of the base portion, an overhanging ring having a smaller thickness in the radial direction around the other end portion in the axial direction of the coupling hole than in the surrounding portion near the other end portion in the axial direction of the coupling hole The universal joint yoke according to any one of (1) to (3), wherein a portion is provided.
(5) The universal joint yoke according to (4), wherein the radial thickness of the projecting ring portion decreases toward the distal end in the axial direction.
(6) The non-pressing hole portions are respectively recessed in the radial direction at two positions on the opposite side in the radial direction orthogonal to the facing direction of the inner surfaces of the pair of arm portions, and The universal joint yoke according to any one of (1) to (5), comprising a recess for reducing rigidity that opens on one side surface in the axial direction.
(7) A method for manufacturing a universal joint yoke according to (4),
Prepare a press die having a non-press-fit hole working surface that is a work surface that matches the non-press-fit hole portion on the outer peripheral surface of the tip portion, and form a substantially disk shape or a substantially circular shape for forming the base portion After obtaining the intermediate material having the columnar base meat portion, the front end portion of the pressing mold is pushed into the base meat portion from the central portion of one axial side surface of the base meat portion. Thus, of the pushed-in portion, the portion that matches the processing surface for the non-press-fit hole portion is used as the non-press-fit hole portion, and the central portion of the other side surface in the axial direction of the base portion meat portion is bulged in the axial direction. And let this bulged portion be the overhang ring portion meat portion for forming the overhang ring portion,
Manufacturing method of universal joint yoke.
(8) forming the press-fitting hole at the center of the base meat portion;
With the formation of the press-fitting hole portion, by removing the central portion of the meat portion for the overhang ring portion, the overhang ring portion is formed,
Press-fit the end of the shaft into the press-fitting hole,
Welding the overhanging ring portion and the shaft so as to cover the overhanging ring portion;
The manufacturing method of the universal joint yoke described in (7).
(9) The object to be manufactured is provided with a chamfered portion at a continuous portion between the inner peripheral surface of the non-press-fit hole portion and one axial side surface of the base portion, and the chamfered portion is formed by pressing. 4) The universal joint yoke described in 4),
In addition to the non-press-fit hole processing surface, a chamfered portion processing surface that is a processing surface that matches the chamfered portion is provided on the outer peripheral surface of the tip portion of the press die,
From the central part of one side in the axial direction of the base meat part that constitutes the intermediate material, by pushing the tip of the pressing mold into the inside of the base meat part, The portion that matches the processed surface for non-press-fit holes is the non-press-fit hole portion, and the portion that matches the processed surface for chamfered portions is the chamfered portion,
The manufacturing method of the universal joint yoke described in (7).

In the case of the universal joint yoke described in (1), the surface layer portion of the press-fitting hole portion of the joint hole, which is a portion where a large hoop stress is generated when the end of the shaft is press-fitted into the joint hole, and the cross When torque is transmitted in the assembled state of the shaft type universal joint, a continuous portion of the inner peripheral surface of the non-press-fit hole portion of the coupling hole and one axial side surface of the base portion, where stress concentration occurs due to torsion The peripheral edge of the coupling hole at one end) is located at a position away from each other. Therefore, in the case of the present invention, as in each of the conventional structures described above, a portion where a large hoop stress caused by press-fitting and a portion where stress concentration due to torsion occurs overlap each other at the base portion. The maximum value of the generated stress can be kept low. As a result, the design for securing the strength of the base can be easily performed.

According to the universal joint yoke described in (2), since the base and the shaft are welded, the base of the yoke and the end of the shaft are more firmly coupled and fixed.

According to the universal joint yoke described in (3), since the chamfered portion is provided in the continuous portion between the inner peripheral surface of the non-press-fit hole portion of the coupling hole and the one side surface in the axial direction of the base portion, The stress concentration based on torsion can be alleviated. Therefore, the maximum value of the stress generated in the base can be kept lower. As a result, the design for ensuring the strength and rigidity of the base can be performed more easily.

In the case of the universal joint yoke described in (4), when the base portion is coupled to the end portion of the shaft, the end portion of the shaft is press-fitted into the coupling hole, and the outer peripheral surface of the shaft and the projecting ring portion If the shaft and the overhanging ring portion are welded in a state where the weld metal is stretched between the outer peripheral surface and the front end surface of the steel plate, the overhanging ring portion can be heated intensively during the welding. (It is possible to make it difficult to disperse the heat applied to the overhanging ring portion toward the intermediate portion in the axial direction of the base portion). For this reason, it is possible to increase the amount of penetration of the outer peripheral surface and the front end surface of the projecting ring portion, and it is easy to secure the strength of the welded portion accordingly.

According to the universal joint yoke described in (5), since the radial thickness of the overhanging ring portion decreases toward the distal end in the axial direction, the end of the shaft is press-fitted into the press-fitting hole. In this state, it is possible to prevent the surface pressure acting on the fitting portion between the press-fitting hole portion and the end portion of the shaft from being intensively increased at a portion corresponding to the axial tip portion of the overhanging ring portion.

According to the universal joint yoke described in (6), based on the presence of the pair of recesses for reducing rigidity, among the continuous portions of the inner peripheral surface of the non-press-fit hole portion and the one axial side surface of the base portion, It is possible to reduce the rigidity in the circumferential direction of the parts other than the both rigidity reducing recesses. Accordingly, the amount of elastic deformation in the circumferential direction of the portion can be increased when torque is transmitted with the cross shaft universal joint assembled. As a result, each part is a part of the part, and parts in the same phase as both ends in the width direction of the base end part of the pair of arm parts with respect to the circumferential direction (four parts where stress concentration due to torsion becomes particularly large) Can reduce the stress concentration.

According to the method for manufacturing a universal joint yoke described in (7), the front end of the press die is placed inside the base meat portion from the central portion of one axial side surface of the base meat portion of the intermediate material. By pushing in, a non-press-fit hole part and a meat part for the overhanging ring part for forming the overhanging ring part can be formed at the same time. For this reason, the manufacturing cost of the universal joint yoke can be suppressed.

According to the method for manufacturing a universal joint yoke described in (8), since the overhanging ring portion can be heated intensively during welding, the amount of penetration of the outer peripheral surface and the front end surface of the overhanging ring portion can be reduced. It can be increased, and it is easy to secure the strength of the welded part.

According to the method for manufacturing a universal joint yoke described in (9), the tip of the pressing die is placed inside the base meat portion from the central portion of one axial side surface of the base meat portion of the intermediate material. By pushing in, the non-press-fit hole portion and the chamfered portion and the overhang ring portion meat portion for forming the overhang ring portion can be formed simultaneously. For this reason, the manufacturing cost of the universal joint yoke can be suppressed.

The perspective view of the yoke which shows the 1st example of embodiment of this invention. (A) is an end view of the yoke as viewed from above (B). (B) is sectional drawing of a yoke. (C) is an end view of the yoke as viewed from below (B). The a section enlarged view of Drawing 2 (B). FIGS. 8A to 8C are cross-sectional views showing an example of a yoke manufacturing method in the order of steps. FIGS. Sectional drawing for demonstrating the process of obtaining the intermediate material shown to FIG. 4 (B) from the intermediate material shown to FIG. 4 (A). The fragmentary sectional view shown in the state which fixedly fixed the end of the shaft to the base of the yoke. FIG. 7A is an enlarged view of a portion b in FIG. (B) is the same figure as (A) regarding a comparative example. (A) is the end elevation seen from the front end side of the yoke which shows the 2nd example of an embodiment of the invention. FIG. 5B is a sectional view taken along the line cc of FIG. (A) The end elevation seen from the front end side of the yoke which shows the 3rd example of an embodiment of the invention. (B) is a dd sectional view of (A). The figure similar to FIG. 3 which shows another example of the shape of the chamfering part employable when implementing this invention. The partially cut side view which shows an example of the steering apparatus known conventionally. The partial cutting side view of the intermediate shaft which couple | bonded the conventional cross-shaft type universal joint provided with the vertical insertion type yoke to the both ends. The fragmentary sectional view shown in the state where the end of the shaft was coupled and fixed to the base of the yoke of the first example of the conventional structure. The figure similar to FIG. 13 regarding the yoke of the 2nd example of a conventional structure. The principal part expanded sectional view which shows the 4th example of embodiment of this invention. The principal part expanded sectional view which shows the 5th example of embodiment of this invention.

[First example of embodiment]
1 to 7 show a first example of an embodiment of the present invention. The feature of this example is mainly the structure of the coupling hole 14a provided in the central portion in the radial direction of the base portion 12b, and the manufacturing method of the yoke 8g provided with such a coupling hole 14a. Including the point that an overhanging ring portion 20 is provided at the central portion of the other side surface in the axial direction of the base portion 12b, and the structure and operation of the other portions are the same as those of the prior art shown in FIG. Since this is the same as in the case of the second example of the structure, the overlapping description will be omitted or simplified, and the following description will focus on the features of this example. In the following description, with respect to the axial direction of the yoke 8g (and its intermediate material), one side means the upper side in each of FIGS. 1, 2B, and 4 to 6, and the other side means The lower side in each figure is said.

In the case of the yoke 8g of this example, the coupling hole 14a has a press-fitting hole part 21 for press-fitting the end part of the shaft 18 at the axially intermediate part or the other end part. At the same time, one end in the axial direction adjacent to the press-fit hole 21 in the axial direction is a non-press-fit hole 22 having a larger diameter than the press-fit hole 21 and into which the end of the shaft 18 is not press-fit. The press-fit hole portion 21 and the non-press-fit hole portion 22 are provided concentrically with each other, and between the axial end edges of the press-fit hole portion 21 and the non-press-fit hole portion 22 are circular (in the illustrated example, circular). An annular step surface 23 is provided. The press-fitting hole 21 is a circular hole or a serration hole similar to the coupling hole 14 constituting the yoke 8f of the second example of the conventional structure shown in FIG. On the other hand, the non-press-fit hole portion 22 is a circular hole whose inner peripheral surface is a simple cylindrical surface. Continuation of the inner peripheral surface of the non-press-fit hole portion 22 and one axial side surface of the base portion 12b (including a concave curved surface that smoothly connects the one axial side surface and the inner side surfaces of the pair of arm portions 13 and 13). As shown in FIG. 3, an R chamfer 24 having a partial arc shape in cross section is provided over the entire circumference of the section. In the case of this example, the R chamfered portion 24 is formed by press working.

Next, a method for manufacturing the yoke 8g of this example having the above-described configuration will be described. When manufacturing the yoke 8g, first, by subjecting a metal plate material such as a steel plate to press working including punching and bending, or by forging a metal material such as a steel round bar, A first intermediate material 25 as shown in FIG. The first intermediate material 25 has a substantially disk-like or substantially columnar base meat part 26 for forming the base part 12b, and two axial positions opposite to the base part meat part 26 in the radial direction from one position in the axial direction. A pair of arm

portion meat portions

27 and 27 each having a substantially rectangular plate shape are provided to form a pair of

arm portions

13 and 13 provided in an extended state.

If such a first intermediate material 25 is obtained, then, with the first intermediate material 25 placed in a cavity of a die (not shown), from the central portion on one side surface in the axial direction of the base meat portion 26, the base material The tip of a press die (press punch) 28 as shown in FIG. 5 is pushed into the meat portion 26. The front end surface of the press die 28 is a circular plane perpendicular to the axial direction. The outer diameter side portion of the front end surface of the pressing die 28 is a step surface processing surface 29 that is a processing surface that matches the step surface 23. The outer peripheral surface of the tip end portion of the press die 28 is a processed surface that matches the inner peripheral surface of the non-press-fit hole portion 22 and the processed surface 30 for the non-press-fit hole portion, and the processed surface that matches the R chamfered portion 24. It is the processing surface 31 for the R chamfered portion. Note that the stepped surface 29 and the non-press-fit hole portion processed surface 30 are smoothly continuous with a convex surface having a partially arcuate cross section. Then, as described above, by pushing the tip end portion of the pressing die 28 from the central portion on one axial side surface of the base meat portion 26 into the base meat portion 26, The center of one side of the axial direction is recessed. Of the recessed portion (the portion into which the tip of the pressing die 28 is pushed), the portion that matches the step surface 29 is the step surface 23 and is aligned with the non-press-fit portion processing surface 30. A portion to be aligned is referred to as a non-press-fit hole portion 22, and a portion aligned with the R chamfered portion machining surface 31 is referred to as an R chamfer portion 24. At the same time, the central portion of the other side surface in the axial direction of the base portion meat portion 26 bulges in the axial direction, and this bulged portion is used as a bulge ring portion meat portion 32 for forming the bulge ring portion 20. A second intermediate material 33 as shown in FIG.

The outer surface shape of the overhanging ring portion meat portion 32 is identical to the outer surface shape of the overhanging ring portion 20 except for the opening of the press-fitting hole portion 21. In the case of this example, in order to obtain the outer surface shape of the overhanging ring portion meat portion 32, the center of the other side surface in the axial direction of the base portion meat portion 26 in the portion facing the cavity on the inner surface of the die. A receiving concave portion having an inner surface that coincides with the outer surface of the overhanging meat portion 32 is provided in a portion facing the portion. Then, based on the fact that the meat bulged in the axial direction from the central portion of the other axial side surface of the base meat portion 26 as described above is filled into the receiving recess, the above-described protruding ring meat The outer surface shape of the part 32 is obtained.

If the second intermediate material 33 as described above is obtained, then punching or cutting (the press-fitting hole portion 21 is used as a serration hole) in the central portion of the base meat portion 26 constituting the second intermediate material 33. In this case, the press-fitting hole portion 21 is formed by performing broaching for forming female serration. Along with the formation of the press-fitting hole portion 21, the overhanging ring portion 20 is formed by removing the central portion of the overhanging ring portion meat portion 32. Moreover, the

circular holes

15 and 15 are formed by stamping and cutting the front-end | tip part of the arm

part meat parts

27 and 27. As shown in FIG. Further, by performing other post-processing as necessary, a yoke 8g as shown in FIG. 4C is completed.

When the end portion of the shaft 18 is coupled to the base portion 12b of the yoke 8g as described above, first, the end portion of the shaft 18 is press-fitted into the press-fit hole portion 21 of the coupling hole 14a as shown in FIG. . When the press-fitting hole portion 21 is a serration hole, a male serration is formed on the outer peripheral surface of the end portion of the shaft 18, and the male serration is engaged with the serration hole with a tightening margin with the press-fitting. When the press-fitting hole portion 21 is a circular hole whose inner peripheral surface is a simple cylindrical surface, the outer peripheral surface of the end portion of the shaft 18 is a cylindrical surface, and this cylindrical surface is formed into the press-fitting hole portion 21 formed of a circular hole. Engage with tightening allowance. Alternatively, the press-fitting hole portion 21 may be a circular hole, the outer peripheral surface of the end portion of the shaft 18 may be a male serration, and the male serration may be press-fitted into the press-fitting hole portion 21. Alternatively, the press-fitting hole portion 21 may be a serration hole, the outer peripheral surface of the end portion of the shaft 18 may be a cylindrical surface, and this cylindrical surface may be press-fitted into the press-fitting hole portion 21. Next, in a state where the weld metal 19 is spanned between the outer peripheral surface and the front end surface of the overhang ring portion 20 and the outer peripheral surface of the shaft 18, that is, in a state where the entire overhang ring portion 20 is covered, The shaft 18 is welded. In particular, when the shaft 18 is a hollow shaft, the overhanging ring portion 20 and the shaft 18 have substantially the same thickness, so that both the shaft 18 and the yoke 8g are melted equally during welding, and the welding strength can be increased.

In the case of this example, the axial direction intermediate part thru | or other end part including the part corresponding to the overhang | projection ring part 20 among the coupling holes 14a are made into the press-fit hole part 21. FIG. At the same time, the outer peripheral surface of the projecting ring portion 20 is a partial conical surface that is inclined in a direction in which the diameter decreases toward the tip end side in the axial direction of the projecting ring portion 20. For this reason, the radial thickness (rigidity) of the overhanging ring portion 20 becomes smaller toward the distal end side in the axial direction. Therefore, the surface pressure σ _P acting on the fitting portion between the press-fitting hole 21 and the end of the shaft 18 in a state where the end of the shaft 18 is press-fitted into the press-fitting hole 21 is the tip of the overhanging ring part 20 in the axial direction. It is possible to prevent intensive increase in the part corresponding to the part.

That is, as shown in FIG. 7B, when the outer circumferential surface of the overhanging ring portion 20a is cylindrical, the radial thickness (rigidity) of the overhanging ring portion 20a is constant in the axial direction. The surface pressure σ _P acting on the fitting portion is intensively increased at the portion corresponding to the axial end portion of the overhanging ring portion 20a (the lower end portion in the figure, which is the end portion on the inlet side of the press-fitting described above). Tend. On the other hand, in the case of this example, as shown in FIG. 7A, the radial thickness (rigidity) of the projecting ring portion 20a becomes smaller toward the distal end side in the axial direction. It is possible to prevent the surface pressure σ _P acting on the portion from being intensively increased at the portion corresponding to the tip end portion in the axial direction of the overhanging ring portion 20 (the lower end portion in the figure). Therefore, in the case of this example, the shear stress applied to the boundary portion between the region where the surface pressure σ _P is acting and the region where the surface pressure σ _P is not acting can be effectively suppressed near the end of the shaft 18. As a result, the design for ensuring the durability of the boundary portion can be easily performed. Such an effect is particularly advantageous when the shaft 18 is a hollow shaft. In order to sufficiently obtain the effect of suppressing the surface pressure as described above, preferably, the inclination angle of the outer peripheral surface (partial conical surface) of the overhang ring portion 20 with respect to the central axis of the overhang ring portion 20 is: Set in the range of 20-70 degrees.

In the case of the universal joint yoke of the present example configured as described above, the press-fitting hole portion 21 of the coupling hole 14a is a portion where a large hoop stress is generated when the end of the shaft 18 is press-fitted into the coupling hole 14a. The inner peripheral surface of the non-press-fit hole portion 22 of the coupling hole 14a and the shaft of the base portion 12b are portions where stress concentration due to torsion occurs when torque is transmitted with the surface layer portion and the cross shaft universal joint assembled. A continuous portion (a portion provided with the R chamfered portion 24) with one side surface in the direction exists at a position away from each other. Therefore, in the case of this example, as in the conventional structures described above, the base 12b is compared with a structure in which a portion where a large hoop stress due to press-fitting occurs and a portion where stress concentration due to torsion overlaps each other. The maximum value of the stress generated in can be kept low. As a result, the design for securing the strength of the base portion 12b can be easily performed.

In the case of this example, since the R chamfered portion 24 is provided at the continuous portion between the inner peripheral surface of the non-press-fit hole portion 22 and one axial side surface of the base portion 12b, it is based on the twist generated in the continuous portion. Stress concentration can be relaxed. Furthermore, in this example, the R chamfered portion 24 is formed by press working. For this reason, compressive residual stress can be given to the surface layer part of a continuous part. Since the compressive residual stress has an action of suppressing the occurrence of damage such as cracks based on the stress applied during use, the allowable stress of the continuous portion can be improved. As a result, the design for securing the strength of the base portion 12b can be performed more easily.

In the case of this example, the tip of the pressing die 28 is pushed into the base meat portion 26 from the central portion of one axial side surface of the base meat portion 26 of the first intermediate material 25. Accordingly, the stepped surface 23, the non-press-fit hole portion 22, the R chamfered portion 24, and the protruding ring portion meat portion 32 can be formed simultaneously. For this reason, the manufacturing cost of the universal joint yoke can be suppressed.

[Second Example of Embodiment]
FIG. 8 shows a second example of the embodiment of the present invention. In the case of the yoke 8h of the present example, in the non-press-fit hole portion 22a constituting the coupling hole 14b, the opposing directions of the inner side surfaces of the pair of arm portions 13 and 13 {vertical direction in FIG. 8A}. Recessed in the radial direction at two positions opposite to the radial direction {left and right direction in FIGS. 8A and 8B) orthogonal to each other (the phase with respect to the rotation direction is shifted by 90 degrees) and the base 12c Are provided as a part of the non-press-fit hole 22a. Also in this example, the yoke 8h is manufactured by the same method as in the first example of the embodiment described above. Therefore, the non-press-fit hole processing surface 30 and the R chamfer processing surface 31 (see FIG. 5) constituting the press die 28 are provided with rigidity-reducing

recesses

35 and 35 and their opening edges. A matching shape is added. When the present invention is implemented, the R chamfered portion 24 can be formed only in a portion that is out of the

recesses

35 and 35 for reducing rigidity in the circumferential direction. In this case, the processed surface 31 for the R chamfered portion may be provided only in a portion corresponding to the removed portion.

According to the universal joint yoke of the present example having the above-described configuration, the inner peripheral surface of the non-press-fit hole portion 22a and the one axial side surface of the base portion 12c are formed based on the presence of the

recesses

35 and 35 for reducing rigidity. Of the continuous part (the part provided with the R chamfered part 24), the rigidity in the circumferential direction of the parts other than the rigidity-reducing

recesses

35, 35 can be reduced. Accordingly, the amount of elastic deformation in the circumferential direction of the portion can be increased when torque is transmitted with the cross shaft universal joint assembled. As a result, each of the portions is a part of the portion, and the portions in phase with the width direction both ends of the base end portions of the

arm portions

13 and 13 with respect to the circumferential direction, that is, the stress concentration due to torsion becomes particularly large. It is possible to relieve the stress concentration at the four portions (α portion) shown in FIG. The configuration and operation of the other parts are the same as in the case of the first example of the embodiment described above.

[Third example of embodiment]
FIG. 9 shows a third example of the embodiment of the present invention. In the case of the yoke 8i of this example, guide recesses 36 and 36 are provided at the intermediate portions in the width direction of the tip portions of the inner side surfaces of the pair of

arm portions

13a and 13a, respectively. At the same time, a part of the

circular holes

15 and 15 provided at the distal end portions of the

arm portions

13a and 13a (end portions on the distal end side of the

arm portions

13a and 13a) are opened in the guide

concave portions

36 and 36. This facilitates the insertion of the shafts of the cross shaft 9 (see FIG. 12) into the

circular holes

15 and 15 through the guide recesses 36 and 36.

Also in this example, the yoke 8i is manufactured by the same method as in the first example of the embodiment described above. Then, the guide recesses 36 are formed at the same time as the non-press-fit hole portion 22, the protruding ring portion meat portion 32, and the R chamfered portion 24 {see FIG. 4 (B)}. For this reason, on the outer peripheral surface near the base end of the press die 28 (see FIG. 5), the guide recesses (for forming the guide recesses 36, 36) that coincide with the guide recesses 36, 36 are used. A processing surface is provided. The configuration and operation of the other parts are the same as in the case of the first example of the embodiment described above.

When the present invention is implemented, the guide recesses 36 and 36 can be provided on the yoke of the second example of the embodiment described above. Also in this case, the guide recesses 36 can be formed by the same method as in the third example of the embodiment described above.

[Fourth Example of Embodiment]
FIG. 15 shows a fourth example of the embodiment of the present invention. In this example, the non-press-fit hole portion 22 is not provided in the yoke 8e, but the shaft small-diameter cylindrical portion 40 that is a non-press-fit portion is provided at the end of the shaft 18 on the yoke 8e side. The shaft small-diameter cylindrical portion 40 can also suppress the maximum value of the stress generated in the base portion 12 of the yoke 8e as in the non-press-fit hole portion 22. In this example, the example in which the present invention is applied to the universal joint yoke using the yoke 8e without the overhanging ring portion 20 is shown. However, the

yokes

8g, 8h, and 8i with the overhanging ring portion 20 provided. It can also be applied to a universal joint yoke using Further, the coupling hole 14 may be a serration hole instead of a circular hole. In this case, male serrations are formed on the outer peripheral surface of the end portion of the shaft 18.

[Fifth Example of Embodiment]
FIG. 16 shows a fifth example of the embodiment of the present invention. In this example, the yoke 8e is not provided with the non-press-fit hole 22, but the yoke 8e is provided with a large chamfer 41. The chamfered portion 41 can also suppress the maximum value of the stress generated in the base portion 12 of the yoke 8e as in the non-press-fit hole portion 22. In this example, the example in which the present invention is applied to the universal joint yoke using the yoke 8e without the overhanging ring portion 20 is shown. However, the

yokes

In carrying out the present invention, it is not always necessary to provide a chamfered portion at a continuous portion between the inner peripheral surface of the non-press-fit hole portion of the coupling hole and one side surface in the axial direction of the base portion. Further, when the chamfered portion is provided, the chamfered portion may be a C chamfered portion 34 having a linear cross-sectional shape as shown in FIG.

When carrying out the method for manufacturing a universal joint yoke of the present invention, for example, a press die having a shape in which the R chamfered portion processing surface 31 (see FIG. 5) of the press die 28 is omitted is used. Then, after the non-press-fit hole portion 22 and the overhanging ring portion meat portion 32 are formed at the same time in the same manner as in the above-described embodiment, a chamfered portion 24 (see FIG. 4) is formed on the continuous portion for another press. It can also be formed in a separate process by pressing using a die or by cutting.

In the case of manufacturing the yoke of the present invention, when the yoke is provided with the chamfered portion 24 and the pair of

recesses

35 and 35 for reducing rigidity (see FIG. 8), first, the first press gold By press working using a die, in the same manner as in the above-described embodiment, the non-press-fit hole portion 22 and the protruding ring portion meat portion 32 (see FIG. 4) not provided with the

recesses

35, 35 for reducing rigidity are provided. The chamfered portion 24 and the rigidity-reducing

recesses

35 and 35 can be simultaneously formed by pressing using a second press die.

When the yoke of the present invention is manufactured and the yoke includes the chamfered portion 24 and the pair of guide recesses 36 and 36 (see FIG. 9), first, the first press die In the same manner as in the above-described embodiment, non-press-fit hole 22 (see FIG. 4) {or 22a (see FIG. 8)} and overhanging meat portion 32 (see FIG. 4) Can be simultaneously formed, and then the chamfered portion 24 and the guide

concave portions

36 and 36 can be formed simultaneously by press working using a second pressing die.

Further, in the case of manufacturing the yoke of the present invention, the yoke includes the chamfered portion 24, a pair of rigidity-reducing

recesses

35, 35, and a pair of guide recesses 36, 36 (see FIGS. 8 and 9). In the case where the first press die is used, first, by press working using the first press die, the non-press-fit hole portion 22 and the overhanging hole portion 22 not provided with the rigidity-reducing

concave portions

35 and 35 are projected in the same manner as the above-described embodiment. The annular portion 32 (see FIG. 4) is formed at the same time, and then the chamfered portion 24, the rigidity-reducing

recesses

35 and 35, and the guide recesses 36 and 36 are formed by pressing using a second pressing die. Can be formed simultaneously.

Moreover, when carrying out the present invention, it is not always necessary to use the overhanging ring portion as a portion for passing the weld metal between the shaft and simply as a portion for securing the axial length of the coupling hole. You can just use it.

Moreover, when implementing this invention, the axial direction other end part of a joint hole can also be made into a non-press-fit rear part instead of a press-fit hole part.

The present application is Japanese Patent Application 2013-147233 filed on July 16, 2013, Japanese Patent Application 2013-228672 filed on November 1, 2013, Japanese Patent Application 2014-108684, 2014 filed on May 27, 2014. This is based on Japanese Patent Application No. 2014-116393 filed on June 5, 1, the contents of which are incorporated herein by reference.

DESCRIPTION OF SYMBOLS 1 Steering wheel 2

Steering shaft

3a, 3b Universal joint 4 Intermediate shaft 5 Steering gear unit 6 Input shaft 7 Tie rod 8a-8i Yoke 9 Cross shaft 10 Male shaft 11

Female shaft

12, 12a-

12c Base portion

13,

13a Arm portion

14, 14a , 14b Coupling hole 15 Circular hole 16 Bearing cup 17 Needle 18 Shaft 19 Weld metal 20, 20a Overhang ring portion 21 Press-

fit hole portion

22, 22a Non-press-fit hole portion 23 Step surface 24 R Chamfer portion 25 First intermediate material 26 Meat for base portion Part 27 Arm part meat part 28 Press die 29 Stepped surface processed surface 30 Non-press-fit hole processed surface 31 R Chamfered part processed surface 32 Overhang ring part meat part 33 Second intermediate material 34 C chamfered part 35 Rigidity-reducing concave part 36 Guide concave part 40 Shaft small-diameter cylindrical part (non-press-fit part)
41 Chamfered part (non-press-fit part)

Claims

An annular base portion having a coupling hole formed in the axial direction at the center in the radial direction;
A pair of arms provided in a state of extending in one axial direction from two positions opposite to the radial direction of the base;
A universal joint yoke comprising:
The coupling hole has at least an axially intermediate portion of the axially intermediate portion or the other end portion as a press-fit hole portion for press-fitting an end portion of the shaft, and is adjacent to the press-fit hole portion in the axial direction. A universal joint yoke in which one end in the axial direction is a non-press-fit hole portion having a diameter larger than that of the press-fit hole portion and into which the end portion of the shaft is not press-fitted.
The universal joint yoke according to claim 1, wherein the base and the shaft are welded.
The universal joint yoke according to claim 1 or 2, wherein a chamfered portion is provided at a continuous portion between an inner peripheral surface of the non-press-fit hole portion and one axial side surface of the base portion.
Of the base portion, a protruding ring portion having a smaller radial thickness than the peripheral portion near the other axial end of the coupling hole is provided around the axial other end of the coupling hole. The universal joint yoke according to any one of claims 1 to 3, wherein:
The universal joint yoke according to claim 4, wherein a radial thickness of the projecting ring portion decreases toward the tip end side in the axial direction.
The non-press-fit holes are recessed in the radial direction at two positions on the opposite side in the radial direction orthogonal to the opposing direction of the inner surfaces of the pair of arm portions, and the axial piece of the base portion The universal joint yoke according to any one of claims 1 to 5, further comprising a rigidity-decreasing recess opening on a side surface.
A method for manufacturing a universal joint yoke according to claim 4,
Prepare a press die having a non-press-fit hole working surface that is a work surface that matches the non-press-fit hole portion on the outer peripheral surface of the tip portion, and form a substantially disk shape or a substantially circular shape for forming the base portion After obtaining the intermediate material having the columnar base meat portion, the front end portion of the pressing mold is pushed into the base meat portion from the central portion of one axial side surface of the base meat portion. Thus, of the pushed-in portion, the portion that matches the processing surface for the non-press-fit hole portion is used as the non-press-fit hole portion, and the central portion of the other side surface in the axial direction of the base portion meat portion is bulged in the axial direction. And let this bulged portion be the overhang ring portion meat portion for forming the overhang ring portion,
Manufacturing method of universal joint yoke.
Forming the press-fitting hole at the center of the base meat part,
With the formation of the press-fitting hole portion, by removing the central portion of the meat portion for the overhang ring portion, the overhang ring portion is formed,
Press-fit the end of the shaft into the press-fitting hole,
Welding the overhanging ring portion and the shaft so as to cover the overhanging ring portion;
A method for manufacturing a universal joint yoke according to claim 7.
The manufacturing object is provided with a chamfered portion at a continuous portion between an inner peripheral surface of the non-press-fit hole portion and one axial side surface of the base portion, and the chamfered portion is formed by press working. The universal joint yoke described,
In addition to the non-press-fit hole processing surface, a chamfered portion processing surface that is a processing surface that matches the chamfered portion is provided on the outer peripheral surface of the tip portion of the press die,
From the central part of one side in the axial direction of the base meat part that constitutes the intermediate material, by pushing the tip of the pressing mold into the inside of the base meat part, The portion that matches the processed surface for non-press-fit holes is the non-press-fit hole portion, and the portion that matches the processed surface for chamfered portions is the chamfered portion,
A method for manufacturing a universal joint yoke according to claim 7.