JP2000230568A - Ball type constant velocity joint - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a constant velocity joint, in which a compact size can be realized, a grinding allowance of an inner race is not increased after full enclosed die forging, a durability of the constant velocity joint is not reduced even at an area at which a torque load becomes larger and service life is not decreased. SOLUTION: A cross section along the axial direction at a groove bottom of a ball groove 12 of an inner race 2 of a constant velocity joint J is formed by a circular arc making a point O1, axially offset against a center O of an outer spherical surface 10 of the inner race 2 as a curvature center and is constituted by a circular portion 14 which is to become an actually used range AO of a ball 4 and concave round portions 15a, 15b extending from the circular arc portion 14. A cross section along an axial direction at the groove bottom of a ball groove 9 of an outer race 1 is formed by a circular arc portion 16 and convex round portions 17a, 17b corresponding to the circular arc portion 14, the concave round portions 15a, 15b of the inner race 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a constant velocity joint used for an automobile, and more particularly to a ball type constant velocity joint.

[0002]

2. Description of the Related Art Ball type constant velocity joint (CVJ)
Includes an outer race 1, an inner race 2, a cage 3, and a torque transmission ball (hereinafter, referred to as a ball) 4, as shown in FIG. 11 to 13 show BJ
(Birfield Joint) shows a constant velocity joint.
The outer race 1 is integrally connected to the driven shaft 6, and the inner spherical surface 8 is formed at least partially in a spherical shape, and six ball grooves 9 are formed at equal intervals along the axial direction. An inner race 2 spline-connected to the drive shaft 7 is inserted into the cavity of the outer race 1.

The inner race 2 has an outer spherical surface 10 having a partially spherical shape, and six ball grooves 12 which are paired with the ball grooves 9 of the outer race 1 are formed along the axial direction. The balls 4 held by the ball holding windows 5 of the cage 3 are arranged at equal intervals in the circumferential direction between the inner race 2 and the outer race 1 and fitted in the ball grooves 9 and 12.

[0004] The outer peripheral surface of the cage 3 is
The cage 3 is formed into a partially spherical shape so as to be guided by the inner spherical surface 8, that is, the outer peripheral surface of the cage 3 has a curved surface in an axial section and a curved surface in an axial perpendicular section. The inner peripheral surface is formed in a partially spherical shape so as to be guided by the outer spherical surface 10 of the inner race 2. That is, the inner peripheral surface of the cage 3 has a curved surface in the axial section and a curved surface in the axial perpendicular section.

In the above constant velocity joint, the inner race 2 is formed by a closed forging method. FIGS. 15A to 15C show an example of the closed forging method.
From the state of FIG. 15A, as shown in FIG.
After the material 20 is sealed with the upper die 21 and the lower die 22, the upper punch 23 is lowered and the lower punch 24 is raised at the same time as shown in FIG. By the operation of the punches 23 and 24, the material 20 is compressed and extruded into the cavities in the molds 21 and 22 to obtain the product 2A. 15 (a) to 15 (c), for convenience of explanation, the axial length (length in the vertical direction in FIG. 15) is shown contracted. In FIG. 14, the material 20 is closed as described above. It is sectional drawing of the inner race 2A (product) obtained by the forging method. Note that in this figure, the upper and lower punches 23 and 24
A has a through hole 20a. The product 2A formed as described above is further ground as shown by a chain line in FIG. 14 and formed as shown in FIG.

[0006] BJ (Birfield Joint) and UF
In the case of J (Undercut Free Joint), since a part or the whole of the cross section of the ball groove 12 has an arc shape, when the central axis of the inner race 2 is viewed horizontally, a part or the whole of the cross section of the bottom of the ball groove 12 is formed. Has an arc shape. Therefore, when the center axis of the inner race 2 is viewed horizontally, the cross section of the bottom of the ball groove 12 (cross section in the direction of the bottom groove of the ball groove) has a shape in which the thickness is reduced on one side or both sides from the top of the mountain. I have. In order to prevent the inner race 2 from being underfilled at the corner of the ball groove 12 and the outer spherical surface by closed forging, a sufficient ball groove bottom wall thickness and a punching amount are required.

For example, in the case of a conventional BJ, as shown in FIG. 14, the inside diameter of only the thin-walled side portion B is reduced so as to satisfy it.

[0008]

In recent years, as the trend toward smaller size and lighter weight has been increasing due to the trend of energy saving and lower fuel consumption, if the size of the constant velocity joint is reduced by reviewing the internal design, the thickness of the bottom of the ball groove is reduced. It has been proposed to try to make it thinner.

As a method of reducing the size of a ball type constant velocity joint such as BJ or UFJ, the ball pitch circle diameter PCD (see FIG. 12) is reduced, and the contact between the ball 4 and the ball groove 12 is kept as it is. Since the surface pressure of the portion increases, the ball diameter is increased to prevent the surface pressure from deteriorating. Then, the thickness of the bottom of the ball groove 12 of the inner race 2 is reduced by the reduction in the ball pitch diameter PCD and the increase in the diameter of the ball 4.

As described above, when the ball groove 12 having a reduced thickness at the bottom of the ball groove 12 is closed and forged, if the inner diameter of the inner race 2 is made smaller as compared with the prior art, the amount of punch extrusion is reduced. In addition, there is a problem that the corners of the ball groove 12 and the outer spherical surface are thinned.

Therefore, it is generally known that the entire thickness of the groove at one end or both ends where the bottom thickness of the ball groove 12 is reduced without changing the inner diameter of the inner race 4 is increased in forming the material. Normally, the ball groove cross section (the cross section perpendicular to the ball groove line)
As shown in FIG. 13, a ball groove is formed with a constant radius of rotation with a position offset by an arbitrary amount d in the axial direction from the outer ball center α of the inner race 4 as a center of curvature β. In this case, the radius of curvature gradually increases near one end or both ends where the thickness of the bottom section of the ball groove becomes thinner (when viewed from the bottom section of the ball groove, one end or the end of the normal convex R section). A concave R surface is formed near both ends.FIG. 13 shows an example in which γ portions near both ends of the convex R are concave R surfaces.)
The required thickness is ensured, and after the closed forging, the ball groove is ground so that the cross section of the bottom of the groove becomes an arc shape.

However, if the thickness of the entire ball groove 12 is increased, the machining allowance in the grinding process after the closed forging increases, resulting in a problem that productivity is deteriorated. or,
A constant velocity joint disclosed in Japanese Patent Application Laid-Open No. 9-329151 has been proposed as a configuration in which the thickness is increased near one end or both ends where the thickness of the bottom cross section of the inner race ball groove is reduced. In this constant velocity joint, when the constant velocity joint is at a large bending angle, the inner race ball shall be shallow so that the groove at one or both ends of the inner race ball does not become deep so that the inner end angle of the ball holding window does not chip. ,
The configuration is such that the amount of movement of the ball in the radial direction with respect to the ball holding window is reduced.

However, in this configuration, in a region where the torque load is large, that is, when the constant velocity joint has a large bending angle (operating angle), the curvature of the ball groove on the outer race side particularly changes from concave to convex. As a result, the surface pressure of the contact portion with the torque transmitting ball is increased, and the durability of the constant velocity joint is reduced, so that the life is shortened.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art, and it is possible to reduce the size and increase the allowance for grinding the inner race after closed forging. There is no need to provide a constant velocity joint.

Another object of the present invention is to provide a constant velocity joint in which the durability of the constant velocity joint does not decrease and the life of the constant velocity joint does not decrease even in a region where the torque load is large.

[0016]

According to the first aspect of the present invention, an inner race is provided on one of two axes which intersect with each other, and an outer race is provided on the other, and formed on each of an outer spherical surface of the inner race and an inner spherical surface of the outer race. Ball grooves, a plurality of torque transmission balls disposed between these ball grooves, and forming a ball holding window for holding the torque transmission balls fitted between the inner race and the outer race, The outer peripheral surface is a ball-type constant velocity joint having a curved surface in an axial cross section and a cage having a curved surface in a vertical cross section. The torque transmission is formed by an arc having a center of curvature at a point O1 offset in the inner race axis direction with respect to the center O of the outer spherical surface. A first curved portion that is in an actual use range in which the roller substantially rolls or presses, and at one end or both ends of the inner race, the first curved portion extends from the first curved portion in the actual use range; When the portion is a convex R, the cross-sectional shape along the axial direction of the outer race at the bottom of the ball groove of the outer race includes a straight portion or a second curved portion having a concave R, and this is the actual use range of the inner race. First
The gist of the present invention is a ball type constant velocity joint formed corresponding to a curved portion, a straight portion outside the actual use range, or a second curved portion.

The maximum operating angle of the constant velocity joint is such that, when the inner race is fitted into the outer race and the inner race and the inner race shaft are assembled together, the inner race shaft is positioned at the periphery of the opening of the outer race. At the time of contact with the outer race axis and the inner race axis. The actual use in the present invention does not mean the use up to the maximum operating angle, but means that the constant velocity joint is actually used in a state of being mounted on a vehicle or the like.

Therefore, the "actual use range" is defined as the range of movement of the contact point with respect to the ball groove of the ball and the range of the elliptical contact in the range of the operating angle between the inner race axis and the outer race axis in actual use. It refers to the total range obtained by adding the surface ranges. When the ball contacts the ball groove, it is theoretically point contact. However, in actuality, torque is applied between the ball contact surface and the bottom of the ball groove during torque transmission, so that the ball and the ball contact each other. The ball groove elastically deforms and makes an elliptical contact. The area in contact with the ellipse is called an elliptical contact surface.

According to a second aspect of the present invention, in the first aspect, the straight portion extending from the first curved portion is a ball-type constant velocity joint extending in a tangential direction of the first curved portion. It is.

According to a third aspect of the present invention, there is provided a ball type constant velocity joint according to the first aspect, wherein a straight portion is formed along the inner race axis direction in the second curved portion serving as the concave R. It is.

(Function) According to the first aspect of the present invention, even when the size of the constant velocity joint is reduced, molding without underfill can be performed similarly to the related art. Further, a constant velocity joint can be obtained in which the allowance for grinding the inner race after the closed forging does not increase.

Further, in the inner race, since the straight portion or the second straight portion is provided from the first curved portion which is the actual use range, the durability of the constant velocity joint is reduced even in a region where the torque load is large. And there is no reduction in service life.

According to the second aspect of the present invention, the function of the first aspect is realized by the configuration in which the linear portion extending from the first curved portion extends in the tangential direction of the first curved portion. According to the third aspect of the present invention, the function of the first aspect is realized even if a straight line portion is formed along the inner race axis direction in the second curved portion serving as the concave R.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention in which a ball type constant velocity joint used in an automobile is embodied in a BJ will be described below with reference to FIGS.

FIG. 1 is a sectional view showing the structure of the constant velocity joint J. Regarding the same configuration as the conventional example of FIG.
The same reference numerals are given and the detailed description is omitted. This embodiment differs from the conventional example in that the shape of the bottom of the ball groove 9 provided on the inner spherical surface 8 of the outer race 1 and the shape of the cross section of the bottom of the ball groove 12 of the inner race 2 are different. , Will be described in detail.

As shown in FIG. 4, the outer spherical surface 10 of the inner race 2 forms a uniform arc having a radius of curvature R1 when viewed in a cross section along the axis L1. The point O is located on the axis L1 of the shaft 7. This point O is the joint center of the constant velocity joint J. The axis L1 coincides with the axis of the inner race 2.

The six ball grooves 12 of the inner race 2
The ball grooves 12 are arranged at an equal angle to each other, and are included in a plane including the axis L <b> 1 of the inner race 2. The ball grooves 12 are opened at both axial ends of the inner race 2. The ball groove 12 has a substantially circular cross section,
It has a groove bottom 12a and an arc-shaped inner surface 12b extending from both sides of the groove bottom 12a to the outer spherical surface 10 side.

FIG. 6 shows a point O1 offset from the point O by d3 on the axis L1 as shown in FIG.
2 shows a cross section of the ball groove 12 drawn on a diametral plane passing through (referred to as a first groove bottom center) and orthogonal to the axis L1. The center of the radius of curvature R2 of the groove bottom 12a is the center O of the first groove bottom.
1 and a point O on the reference axis L3 that bisects the groove bottom 12a.
a. Further, the center of the radius of curvature R2 of the inner side surface 12b is offset from the first groove bottom center Oa by d1 in the left-right direction with respect to the reference axis L3 in FIG. D on the bottom 12a side
The points Ob1 and Ob2 are offset by 2 minutes. The groove bottom 12a and the inner side surface 12b are connected at an F portion as shown in FIG.

The ball 4 has a diameter φ.
The two inner surfaces 12b are in contact at two K points. As shown in FIGS. 2 and 4, the groove bottom 12a of the ball groove 12 has an arcuate portion 1 as a first curved portion in the axial direction.
4 and a pair of concave R portions 15a and 15b as second curved portions continuously provided at both ends of the circular arc portion 14.

The arc portion 14 is formed on the outer spherical surface 1 of the inner race 2.
It is formed as a circular arc with the point O1 offset from the center O of 0 by d3 in the axial direction as the center of curvature. The actual use range A where the ball 4 substantially rolls or presses.
In the present embodiment, 0 is the total range obtained by adding the range of movement of the K contact with respect to the ball groove 12 of the ball 4 and the range of the elliptical contact surface. When the ball 4 comes into contact with the ball groove 12, it is theoretically point contact. However, in actuality, the torque is applied between the ball contact surface and the ball groove 12 at the time of torque transmission. Also, the inner surface of the ball groove 12 is elastically deformed and comes into contact with the elliptical shape. The area in contact with the ellipse is the elliptical contact surface. In FIG. 3, C1 is the ball 4 and the inner surface 12b of the ball groove 12.
Indicate elliptical contact surfaces in contact with each other.

In FIG. 4, A1 indicates the range of movement of the K contact between the ball 4 and the ball groove 12. A2 indicates a range in which the actual use range is replaced with a movement around the center of the ball 4. A3 indicates a ball center moving range of the maximum operating angle of the constant velocity joint including a manufacturing error, and the range is narrower than A2.

The concave R portions 15a and 15b extend from the arc portion 14 at both ends of the inner race 2, and are formed in the concave R while the arc portion 14 is convex R. I have. The biconcave R portions 15a and 15b are formed by arcs having the point O1 and arbitrary points OC1 and OC2 on a straight line passing through the boundary between the arc portion 14 and the concave R portions 15a and 15b as centers of curvature. Have been.

As shown in FIG. 5, the inner spherical surface 8 of the outer race 1 has a radius of curvature R as viewed in a cross section along the axis L2.
3, the center of curvature of which is a point O located on the axis L2 of the driven shaft 6. This point O is the joint center of this constant velocity joint.
The axis L2 coincides with the axis of the outer race 1.

The six ball grooves 9 of the outer race 1 are arranged at an equal angle to each other, and the ball grooves 9 are included in a plane including the axis L2 of the outer race 1. Further, the ball groove 9 is opened in the chamfer 19 of the opening of the outer race 1 on the side opposite to the driven shaft 6 in the axial direction of the outer race 1,
On the driven shaft 6 side, it communicates with a polishing relief 18 that is recessed in the cavity inside the outer race 1.

The polishing relief 18 is a part required when grinding the ball groove 9 and when inserting the inner race 2 together with the ball 4 and the cage 5, and in this embodiment, it is made larger than the conventional one. ing. That is, the drive shaft 7
When assembling the inner race 2, the ball 4, and the cage 5 which are not yet connected to the outer race 1, the inner race 2
In the outer race 1 at an angle larger than the maximum operating angle. At this time, since the ball 4 is pushed more deeply into the outer race 1 at the concave R portion 15a than in the conventional case, the polishing relief 18 is provided with a large concave portion so that the ball 4 can be stored.

The ball groove 9 has a substantially circular cross section and has a groove bottom 9.
a, and a pair of arc-shaped inner side surfaces 9b extending from both sides of the groove bottom 9a toward the inner spherical surface 8 side. The ball groove 9 is formed so as to contact the ball 4 at one point (K contact point) with each of the inner side surfaces 9b, similarly to the ball groove 12 of the inner race 2.

The groove bottom 9a of the ball groove 9 has, in the axial direction of the axis L2, an arc portion 16 as a third curved portion, and a pair of convex portions as fourth curved portions connected to both ends of the arc portion 16. R sections 17a and 17b are provided. The arc portion 16 is d4 in the axial direction with respect to the center O of the inner spherical surface 8 of the outer race 1.
It is formed by an arc centered on the curvature of the point O2 offset by the distance. The arc portion 16 is provided corresponding to the arc portion 14 which is the actual use range A0 of the ball groove 12 of the inner race 2.

Here, the range of the arc portion 16 of the ball groove 9 of the outer race 2 corresponding to the actual use range A0 is such that when the constant velocity joint J is actually used, the ball 4 on the inner race 2 When moving in the use range A0,
A movement range B0 (hereinafter, referred to as a movement range) on the ball groove 9 of the outer race 1
(Referred to as a corresponding range) (see FIG. 5).

In FIG. 5, B1 is the outer race 1
3 shows the range of movement of the K contact point between the ball 4 and the ball groove 9 in FIG. B2 indicates a range in which the actual use range in the inner race 2 is replaced with the movement around the center of the ball 4 and the range A2 is replaced with the outer race 1. B3 indicates a ball center moving range of the maximum operating angle of the constant velocity joint including a manufacturing error in the outer race 1.

In FIG. 3, C2 indicates an elliptical contact surface where the ball 4 and the inner surface 9b of the ball groove 9 are in contact with each other. Further, the convex R portions 17a and 17b are
6, the arc portion 16 is formed to be convex R while the arc portion 16 is formed to be concave R.

The biconvex R portions 17a and 17b are connected to the point O2,
In addition, it is formed by an arc centered on any point OC3, OC4 on a straight line passing through the boundary between the arc portion 16 and the convex R portions 17a, 17b. The convex R portions 17a, 1
7b are provided corresponding to the concave R portions 15a and 15b which are outside the actual use range A0 of the ball groove 12 of the inner race 2.

In this embodiment, the driven shaft 6 corresponds to an outer race shaft, and the drive shaft 7 corresponds to an inner race shaft.
Therefore, the constant velocity joint J having the above configuration has the following advantages.

(1) In this embodiment, the inner race 2
The cross-sectional shape along the axial direction of the groove bottom 12a of the ball groove 12 is formed by an arc having a point O1 axially offset with respect to the center O of the outer spherical surface 10 of the inner race 2 as a center of curvature. 4 is the arc portion 14 which is the actual use range
(A first curved portion) and a concave R portion 15 extending from an arc portion 14 which is an actual use range at both ends of the inner race 2.
a, 15b (second curved portion). The cross-sectional shape along the axial direction of the groove bottom 9a of the ball groove 9 of the outer race 1 is defined by the circular arc portion 14 that is the actual use range A0 of the inner race 2 and the concave R portions 15a and 15b that are outside the actual use range A0. Arc part 16 and convex R part 17 corresponding to
a and 17b were formed.

For this reason, the concave R portions 15a and 15b outside the practical use range A0 of the inner race 2 can be made thicker than before, so that when the size of the constant velocity joint is reduced, the inner race 2 is closed. When forming by the forging method, the corners of the ball groove 12 and the outer spherical surface 10 can be formed without being thinned.

In consideration of the actual use range A0, the concave R portion 1
Since the groove bottom 12a of the ball groove 12 is allowed to be changed so that the wall thickness of the ball grooves 5a and 15b can be made larger than before, when the through-hole (corresponding to the through-hole 20a in FIG. 14) after the closed forging is ground, the grinding is performed. Since there is no increase in the allowance, the grinding process does not take much time and the productivity does not deteriorate.

Further, the thickness of the concave R portions 15a and 15b, which is outside the actual use range A0, can be made thicker than before. Therefore, unlike the constant velocity joint described in Japanese Patent Application Laid-Open No. 9-329151, even in a region where the torque load is large, that is, even when the constant velocity joint J has a large bending angle (operating angle) (FIG. 3). Reference), the surface pressure does not increase because the shape of the groove bottom 9a in the ball groove 9 on the outer race 1 side changes from concave to convex outside the corresponding range B0.
For this reason, the durability of the constant velocity joint does not decrease, and the life can be extended.

The present invention is not limited to the above embodiment, but may be implemented as follows. (1) In the above embodiment, the groove bottom 12 of the inner race 2
a, the concave R portions 15a, 15b outside the actual use range A0.
Provided, but instead of the arc portion 1 outside the actual use range A0.
Linear portions 15c and 15d extending in a tangential direction from the end portion 4 may be provided as shown in FIG. In this case, instead of providing the concave R portions 15a and 15b at the groove bottom 9a of the outer race 1, straight portions 17c and 17d extending from the end of the arc portion 14 are provided outside the corresponding range B0 as shown in FIG.

In this case, the same operation and effect as the above embodiment can be obtained. (2) In the above embodiment, the groove bottom 12 of the inner race 2
a, the concave R portions 15a, 15b outside the actual use range A0.
However, the arc length of the concave R portions 15a, 15b is shortened, and instead, as shown in FIG.
The straight portions 15c and 15d may be extended from 5b.

In this case, at the groove bottom 9a of the outer race 1, the arc length of the convex R portions 17a, 17b is reduced,
Linear portion 1 extending from the end of arc portion 14 outside corresponding range B0
7c and 17d are provided as shown in FIG.

In this case, the same operation and effect as those of the above embodiment can be obtained. (3) In each of the above embodiments, the concave R portions 15a and 15b, the straight portions 15c and 15d, etc. are provided outside the both ends of the actual use range A0, but the concave R portions are provided only at one end outside the actual use range A0. Any of a single part, a single linear part, and a combination of a concave R part and a linear part may be selected and adopted. In this case, the corresponding range B0 is also provided on the ball groove 9 side of the outer race 1 side.
Corresponding to the configuration outside the actual use range of the inner race 2 only at one outer end, any one of the convex R portion alone, the linear portion alone, and the configuration combining the convex R portion and the linear portion is selected. Good.

(4) In the above embodiment, the constant velocity joint is embodied as a BJ, but may be embodied as a UFJ. Since UFJ has no undercut, it can be formed by forging without grinding. Therefore, even if the configuration of the present invention is adopted, unlike the BJ, when the inner race is formed by closed forging, since the die can be removed without using a split die, it can be handled without grinding. it can.

Here, in addition to the technical ideas described in the claims, the technical ideas grasped by the above-described embodiments are listed below together with their effects. (1) In claim 1, the cross-sectional shape along the outer race axial direction at the ball groove bottom of the outer race corresponds to the first curved portion, which is the actual use range of the inner race, with a concave R, A ball portion formed by corresponding to a straight portion outside the actual use range by a straight portion, or by forming a second curved portion outside the actual use range by a convex R. Constant velocity joint. By doing so, the function and effect of claim 1 can be realized.

[0053]

As described above in detail, according to the first to third aspects of the present invention, even when the size of the constant velocity joint is reduced, molding without underfill can be performed as in the related art.
Further, it is possible to obtain a constant velocity joint in which the grinding allowance of the inner race after the closed forging does not increase. or,
The thin portion of the cross section at the bottom of the ball groove, which is the starting point of the damage of the inner race, can be made thicker than before, so that the strength of the inner race itself can be improved and the miniaturization design can be facilitated.

Further, in the inner race, since the straight portion or the second straight portion is provided from the first curved portion which is the actual use range, the durability of the constant velocity joint is reduced even in the region where the torque load is large. And there is no reduction in service life.

[Brief description of the drawings]

FIG. 1 is a sectional view showing the structure of a ball type constant velocity joint according to an embodiment of the present invention.

FIG. 2 is a half sectional view of a main part showing a connecting portion between an outer race and an inner race.

FIG. 3 is a cross-sectional view of a constant velocity joint when an intersection angle is increased.

FIG. 4 is a sectional view of the inner race in the axial direction of the inner race.

FIG. 5 is a sectional view of the outer race in the axial direction of the outer race.

FIG. 6 is an explanatory view showing a contact point between a ball and a ball groove.

FIG. 7 is an inner race axial half-sectional view of an inner race according to another embodiment.

FIG. 8 is a half sectional view of the outer race in the axial direction of the outer race.

FIG. 9 is a half sectional view in the inner race axial direction of an inner race according to another embodiment.

FIG. 10 is a half sectional view of the outer race in the axial direction of the outer race.

FIG. 11 is a sectional view showing the structure of a conventional ball type constant velocity joint.

FIG. 12 is a front view of the inner race.

FIG. 13 is a half sectional view of a main part of the inner race.

FIG. 14 is a sectional view of the inner race after closed forging.

15 (a) to (c) are explanatory views showing a closed forging method.

[Explanation of symbols]

1 ... outer race, 2 ... inner race, 3 ... cage, 4
... Torque transmitting ball, 5 ... Ball holding window, 6 ... Driven shaft (constituting outer race shaft), 7 ... Drive shaft (constituting inner race shaft), 8 ... Inner spherical surface of outer race, 9
... ball groove of outer race, 10 ... outer spherical surface of inner race, 12 ... ball groove of inner race, L1 ... axis, L2
... Axes, A0 ... Actual use range, B0 ... Corresponding range.

Claims (3)

[Claims] An inner race is provided on one of two intersecting axes, and an outer race is provided on the other. A ball groove formed on each of an outer spherical surface of the inner race and an inner spherical surface of the outer race is provided between the ball grooves. A plurality of torque transmitting balls, and a ball holding window for holding the torque transmitting ball fitted between the inner race and the outer race, and the outer peripheral surface has a curved surface in the axial cross section and a vertical In a ball-type constant velocity joint having a cage having a curved surface, a cross-sectional shape of the inner race along the axial direction of the inner race at the bottom of the ball groove is in the axial direction of the inner race relative to the center O of the outer spherical surface of the inner race. Actual use in which the torque transmitting ball is formed of an arc having the offset point O1 as the center of curvature, and the torque transmitting ball is substantially rolled or pressed. A first curved portion to be surrounded, at one end or both ends of the inner race, extending from the first curved portion which is the actual use range, and when the first curved portion is a convex R, a straight portion or a concave R A first curved portion that is an actual use range of the inner race, and a straight portion that is out of the actual use range, wherein the cross-sectional shape along the outer race axial direction at the ball groove bottom of the outer race is included. Or a ball type constant velocity joint formed corresponding to the second curved portion. 2. The ball type constant velocity joint according to claim 1, wherein the straight portion extending from the first curved portion extends in a tangential direction of the first curved portion. 3. The ball type constant velocity joint according to claim 1, wherein a straight portion is formed along the inner race axis direction in the second curved portion which becomes the concave R.