JP2007162954A - Constant velocity universal joint - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To secure accuracy of spherical faces where an inner ring and an outer ring are kept into contact with each other and a track groove while shortening a processing time, and to reduce heat generation in an initial period of use. <P>SOLUTION: In this fixed type constant velocity universal joint for a drive shaft, a spherical inner face 5 of the outer ring 1 and the track groove 7 are formed by cut faces after quench hardening. A spherical outer face 6 of the inner ring 2 and the track groove 8 are also formed by cut faces after quench hardening. A retainer 4 has a spherical outer face 10, a spherical inner face 11, and an inner surface of a pocket 9 formed by cut faces after quench hardening. Faces of the retainer 4, the outer ring 1 and the inner ring 2 kept into contact with each other are provided with surface-treated layers to reduce frictional resistance. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a constant velocity universal joint for automobiles, and more particularly to a constant velocity universal joint used for a drive shaft.

Constant velocity universal joints for automobiles and the like are required to have rotational balance performance and suppression of internal heat generation during high-speed rotation. To improve the rotation balance performance, the gap inside the joint must be kept small. On the other hand, if the internal gap is reduced, heat generation increases, so to suppress it, the surface roughness must be reduced and the frictional resistance due to contact between components must be reduced. Therefore, particularly in a fixed ball type constant velocity universal joint, the contact portions of the inner and outer rings and the cage are ground after heat treatment to ensure dimensional accuracy and surface roughness. Further, as a means for reducing the frictional resistance inside the constant velocity universal joint, one that forms a coating layer of a solid lubricant (Patent Document 1) is known.
Japanese Utility Model Publication No. 2-121333

  The grinding process takes longer processing time than cutting. Also, in the grinding process, environmentally undesirable coolant must be used.

An object of the present invention is to provide a constant velocity universal joint that can ensure the accuracy of the spherical inner surface of the outer ring and the track groove while shortening the machining time.
Another object of the present invention is to ensure the accuracy of the spherical outer surface of the inner ring and the track groove while shortening the machining time.
Still another object of the present invention is to reduce heat generation due to contact between parts, particularly to reduce heat generation in the initial stage of use.

The constant velocity universal joint of the present invention is a constant velocity universal joint for a drive shaft, and a track groove having a curved groove bottom vertical cross-sectional shape is formed along the axial direction on the spherical inner surface of the outer ring. On the outer surface, a track groove having a curved groove bottom vertical cross-sectional shape is formed opposite to the track groove of the outer ring, a ball is incorporated between these track grooves, and a cage having a pocket in which the ball is accommodated, A spherical outer surface in surface contact with the spherical inner surface of the outer ring and a spherical inner surface in surface contact with the spherical outer surface of the inner ring are provided, and the center of curvature of the track groove in the axial section of the outer ring and the track groove in the axial section of the inner ring are provided. In a constant velocity universal joint whose center of curvature is offset equidistant from side to side with respect to the angle center of the joint, so-called fixed type constant velocity universal joint,
The spherical inner surface of the outer ring, or the track groove, or both of the spherical inner surface and the track groove are used as a cut surface after quenching.
According to this configuration, the spherical inner surface and the track groove of the outer ring are used as the cut surfaces after quenching, and the post-quenching cutting is performed instead of the grinding process after the conventional heat treatment, so that the processing time is shortened. Because of the cutting process, it is possible to perform the process without using a coolant that is undesirable in the environment. Due to the improvement of processing technology, the cutting process itself can be processed with high accuracy, and hard metal such as hardened steel can be cut. In addition, since it is a cut after quenching and heat treatment distortion does not occur thereafter, the accuracy of the spherical inner surface of the completed outer ring and the track groove is ensured by using the cut surface after quenching as described above. . For example, it is possible to obtain dimensional accuracy equivalent to that of grinding.
Cutting is usually performed before quenching. Conventionally, the outer ring of a constant velocity universal joint is quenched after cutting, but high-precision cutting is performed at the cutting stage before quenching. However, the accuracy is reduced due to subsequent heat treatment distortion. It may be possible to devise a cutting shape before quenching to a shape that allows for heat treatment distortion, but shape management is difficult. Therefore, the present invention achieves both accuracy ensuring and shortening of processing time by adopting hardened steel cutting. Thereby, cost reduction is realized while maintaining the performance.

In the present invention, the spherical outer surface of the inner ring or the track groove, or both of the spherical outer surface and the track groove may be used as a cut surface after quenching.
For the inner ring, as with the outer ring, a cutting process is used instead of the conventional grinding process after the heat treatment, so that the processing time is shortened and the spherical outer surface or the track groove, or both the spherical outer surface and the track groove. Accuracy can be ensured. Thus, the effect of improving productivity can be greatly obtained by adopting the cut surfaces after quenching for both the outer ring and the inner ring.

In the present invention, among the spherical outer surface, spherical inner surface, and pocket of the cage, at least the inner surface of the pocket may be a cut surface after quenching.
For example, the inner surface of the pocket of the cage can have a dimensional accuracy equivalent to that obtained by grinding after carburizing and quenching, and is advantageous in setting the pocket clearance within a predetermined range. Normally, the pocket is punched out by pressing and dimensioned by milling, but it is difficult to set the pocket gap within a predetermined range required for matching or the like due to subsequent heat treatment deformation or the like. Such demands on dimensional accuracy can be satisfied by using a cut surface after quenching.

In the constant velocity universal joint of the present invention, eight track grooves of the inner and outer rings may be formed.
The eight track grooves have a smaller diameter than the general six, and the number of grooves is increased in order to reduce the size by increasing the number of balls. For this reason, there is a strict requirement on the accuracy of the groove shape, but such a requirement on accuracy can be met by using a cut surface after quenching. Further, when the number of track grooves increases, it takes time for processing. However, since hardened steel cutting has better workability than grinding, the effect of shortening the processing time is great. For example, when there are eight track grooves, two grinders are required for grinding to ensure productivity, but only one is necessary for hardened steel cutting.

In the constant velocity universal joint of the present invention, a surface treatment layer for reducing frictional resistance may be formed at least on the surface of the cage. The portion for providing the surface treatment layer may be only the spherical outer surface and the spherical outer surface on the surface of the cage, but is preferably provided on the entire surface including the pocket inner surface.
In the case of a cut surface after quenching, the required surface roughness requirement can be satisfied, but lead traces may remain on the processed surface. By providing the surface treatment layer, it is possible to obtain a smoother surface having no such trace of leads. By making the surface of the cage a smooth surface on which the surface treatment layer is formed in this way, it is possible to reduce frictional resistance due to contact between components and to reduce heat generation during high-speed rotation. Further, by providing the surface treatment layer on the cage side, the effect of reducing the frictional resistance can be obtained for both the inner ring and the outer ring only by providing the surface treatment layer on the cage which is one component.

  The surface treatment layer may be a solid lubricant film layer. Thus, by providing the coating layer of a solid lubricant, the contact surface between components can be lubricated and the effect of reducing frictional resistance is great. In particular, the effect of preventing heat generation by reducing friction during high-speed rotation at the initial stage of use is great. In the initial use of the joint, the grease is not familiar and is liable to cause poor lubrication. When a coating layer of a solid lubricant is provided, excessive heat generation at the initial stage of use until such a lubricant becomes familiar is prevented.

  The surface treatment layer may be a low temperature sulfuration treatment layer. In the low-temperature sulfurization treatment, since the treatment is performed at a low temperature, the base material is not tempered during the treatment, and it is avoided that the wear resistance is lowered due to the hardness reduction due to the tempering.

In the present invention, the joint radial clearance between the track groove of the inner and outer rings and the ball may be set to 0.05 mm or less. The joint radial clearance is a joint radial distance between the ball on the pitch circle and the inner surface of each track groove.
Thus, by setting the joint radial clearance between the track groove and the ball as small as 0.05 mm or less, the rotation balance performance is improved. Even if the track groove is a cut surface after quenching, machining accuracy with the gap of 0.05 mm or less can be obtained.

  In this invention, the cross-sectional shape of the track groove of the outer ring may be an elliptical arc. In this way, when the elliptical arc shape is used, the ball makes point contact with two contact points on both sides of the track groove. For this reason, the variation of the contact angle θ is reduced. Machining to make the cross-sectional shape an elliptical arc can be easily performed by quenching steel cutting.

The constant velocity universal joint of the present invention is a fixed type constant velocity universal joint for a drive shaft, wherein the spherical inner surface of the outer ring, or the track groove, or both of the spherical inner surface and the track groove are cut surfaces after quenching. Therefore, the accuracy of the spherical inner surface of the outer ring and the track groove can be ensured while shortening the machining time.
If the spherical outer surface of the inner ring, or the track grooves, or both of these spherical outer surfaces and track grooves are used as the cut surfaces after quenching, the accuracy of the spherical outer surface of the inner ring and the track grooves can be ensured while shortening the machining time. .
In addition, when a surface treatment layer that reduces frictional resistance is formed at least on the surface of the cage, it is possible to reduce heat generation due to contact between parts, particularly heat generation in the initial stage of use while using a cut surface after quenching. it can.

  An embodiment of the present invention will be described with reference to the drawings. This embodiment is an example applied to a fixed type constant velocity universal joint for a drive shaft. This constant velocity universal joint has a plurality of track grooves 7 along the axial direction formed on the spherical inner surface 5 of the outer ring 1, and a track groove 8 facing the track groove 7 formed on the spherical outer surface 6 of the inner ring 2. A ball 3 for torque transmission incorporated between the track grooves 7 and 8 of the inner rings 1 and 2 is held by a cage 4. The cage 4 has a pocket 9 in which the ball 3 is accommodated, and has a spherical outer surface 10 and a spherical inner surface 11 that are guided in surface contact with the spherical inner surface 5 of the outer ring 1 and the spherical outer surface 6 of the inner ring 2, respectively.

The track groove 7 of the outer ring 1 has an arcuate curve in the longitudinal section along the groove bottom. The track groove 8 of the inner ring 2 also has a circular cross-sectional shape along the groove bottom. As shown in FIG. 2, the curvature center O1 in the axial section of the track groove 7 of the outer ring 1 and the curvature center O2 in the axial section of the track groove 8 of the inner ring 2 are equal to the right and left of the angular center O0 of the joint. Offset to distance. The angle center O0 of the joint coincides with the spherical centers of the spherical inner surface 5 of the outer ring 1 and the spherical outer surface 6 of the inner ring 2.
The number of track grooves 7 and 8 of the outer / inner rings 1 and 2 is six, and they are equally distributed in the circumferential direction. The number of the track grooves 7 and 8 may be eight as shown in a modification of the inner ring 2 in FIG.

  As shown in FIG. 1, the outer ring 1 is provided with a mounting flange 13 on the outer diameter surface of the mouse 12, and has an opening 14 having a smaller diameter than the mouse 12 on the back side facing the mouse 12. A cylindrical mounting portion 15 projects from the end of the outer ring. A shaft 16 is inserted into the opening 14, and the tip of the shaft is fitted to the inner diameter surface 2 a of the inner ring 2. Serrations are formed on the inner diameter surface 2a of the inner ring 2 and the outer surface of the tip end of the shaft 16, respectively. One end of a boot 17 covering the shaft 16 is fixed to the cylindrical mounting portion 15 of the outer ring 1 by a ring-shaped clasp, and the other end of the boot 17 is fixed to the outer periphery of the shaft 16 by a tightening ring. The mouse 12 of the outer ring 1 is covered with a cover 18 having a peripheral edge fitted to the inner diameter surface thereof. The constant velocity universal joint in which the shaft 16 is inserted into the outer ring 1 as in the example of the figure is called a Zepper type or a Zeppa type constant velocity universal joint. When this constant velocity universal joint is applied to a propeller shaft, the shaft 16 is a propeller shunt.

  The cross-sectional shape of the track groove 7 of the outer ring 1 is a Gothic arch shape composed of a pair of opposing arc curves 7a and 7a, as shown in an enlarged view in FIG. In the case of a Gothic arch shape, the ball 3 makes point contact with two contact points P on both sides of the track groove 7. For this reason, the variation of the contact angle θ is reduced. In addition to this, the cross-sectional shape of the track groove 7 may be an arc as shown in FIG. 5B, or may be an elliptical arc as shown in FIG. In the case of the elliptical arc shape, the ball 3 makes point contact with the two contact points P on both sides as in the case of the Gothic arch shape.

As shown in FIG. 12A, the groove depth H of the track groove 7 of the outer ring 1 is such that the mouth 12 side of the outer ring 1 gradually becomes deeper. The depth H1 from the groove bottom to the contact point P is constant over the entire length of the groove.
The track groove 7 has a depth H2 from the groove opening to the contact point P as shown in FIG. 5B, instead of keeping the depth H1 from the groove bottom to the contact point P as described above. It may be constant over the entire length. In that case, the cross-sectional shape in the depth portion from the groove bottom of the track groove 7 to the contact point P gradually changes.
When the depth H1 from the groove bottom to the contact point P is constant as in the example of FIG. 5A, the depth H2 from the contact point P to the groove opening is shallow at one groove end 7b. Although there is a risk of the ball 3 climbing, if the depth H2 from the groove opening to the contact point P is constant as in the example of FIG.

  2 and 7, the cross-sectional shape of the track groove 8 of the inner ring 2 is a Gothic arch shape, an arc shape, or an elliptical arc shape, like the track groove 7 of the outer ring 1. The depth of the track groove 8 of the inner ring 2 is also configured such that the mouse 12 side of the outer ring 1 gradually becomes deeper.

2 and 4, the spherical inner surface 5 of the outer ring 1 and the inner surface of the track groove 7 are cut surfaces after quenching. When the outer ring 1 is made of a steel material such as medium carbon steel such as S53C, the spherical inner surface 5 and the inner surface of the track groove 7 become a cut surface after quenching after induction hardening. These hardened cut surfaces preferably have a surface roughness of Ra 0.8 or less.
2 and 6, the spherical outer surface 6 of the inner ring 2 made of case-hardened steel and the inner surface of the track groove 8 are also carved and hardened like the outer ring 1 after carburizing and quenching.
2 and 9, the cage 4 made of case hardened steel or the like has a spherical outer surface 10, a spherical inner surface 11, and an inner surface of a pocket 9 which are hardened steel cutting surfaces after carburizing and quenching.
The surface roughness of each of the inner ring 2 and the cage 4 after quenching is preferably set to Ra 0.8 or less similarly to the outer ring 1. In the outer ring 1, the inner ring 2, and the cage 4, when a surface treatment layer 20 (FIGS. 14 to 16) as shown below is provided on the cut surface after quenching, the surface roughness of the surface treatment layer 20 is provided. Is set to Ra 0.8 or less.

  As shown in FIG. 11, the joint radial clearances between the track grooves 7 and 8 of the outer ring 1 and the inner ring 2 and the balls 3 are represented by d1 and d2, and the gaps d1 and d2 are the balls 3 on the pitch circle PCD. And the radial distance between the inner surfaces of the track grooves 7 and 8. Looking at the joint as a whole, the amount of play in the radial direction of the track and the ball is represented by the sum of d1 and d2 in two opposing track grooves at the angle center O0 of the joint. The total sum of d1 and d2 is preferably 0.05 mm or less. In the case of a constant velocity universal joint for a drive shaft, the sum of the gaps d1 and d2 may be, for example, in the range of 0.035 to 0.125 mm. In the case of a constant velocity universal joint for a propeller shaft, the sum total of d1 and d2 is, for example, in the range of 0.005 to 0.045 mm.

  In FIG. 9A, the axial gap d3 between the pocket 9 of the cage 4 and the ball 3 is a positive gap. The axial clearance between the pocket and the ball is negative (−0.01 to −0.06 mm).

As shown in FIG. 14, it is preferable to form a surface treatment layer 20 that reduces frictional resistance on the surface of the cage 4, particularly on the spherical outer surface 10 and the spherical inner surface 11. In this embodiment, the surface treatment layer 20 is formed on the entire surface of the cage 4 including the inner surface of the pocket 9 (FIG. 9). The surface treatment layer 20 is a coating layer of a solid lubricant. As the solid lubricant, molybdenum disulfide, graphite or the like can be used. For example, molybdenum disulfide is used and a heat-resistant resin such as polyphenylene sulfide (pps) or polyimide is coated as a binder.
As shown in FIG. 15, the surface treatment layer 20 made of a solid lubricant may be provided on the steel base material of the cage 4 via an underlayer 21. The underlayer 21 is a layer that facilitates adhesion of a solid lubricant, and is, for example, a manganese phosphate-based film.
The film thickness of the surface treatment layer 20 made of a solid lubricant is, for example, 12 μm or less. When the base layer 21 is provided, the film thickness including the base layer 21 is 12 μm or less.

In FIG. 14, the surface treatment layer 20 may be a low temperature sulfuration treatment layer. The low temperature sulfurization treatment is a treatment in which sulfur is immersed at a low temperature, and is also called a corvette treatment. When the surface treatment layer 20 is a low temperature sulfuration treatment layer, the thickness is preferably 10 μm or more, for example, about 30 μm.
In the low-temperature sulfurization treatment, since the treatment is performed at a low temperature, the base material is not tempered during the treatment, and it is avoided that the wear resistance is lowered due to the hardness reduction due to the tempering.

In addition to the cage 4, the surface treatment layer 20 is formed on the spherical inner surface 5 of the outer ring 1, the spherical outer surface 6 of the inner ring 2, and the track grooves 7 and 8 of the outer / inner rings 1 and 2, as shown in FIG. It is also preferable to provide the inner surface. Even when the surface treatment layer 20 is provided on the outer / inner rings 1 and 2, the solid lubricant or the low-temperature sulfurization treatment layer described for the cage 4 can be used, and an underlayer 21 (FIG. 15) may be provided.
The surface treatment layer 20 provided on the outer / inner rings 1 and 2 and the surface treatment layer 20 provided on the cage 4 may be of different types. For example, the surface treatment layer 20 of the outer ring 1 may be made of a fixed lubricant, and the surface treatment layer 20 of the cage 4 may be a low temperature sulfuration treatment layer. Even if the surface treatment layer 20 is provided on all of the outer / inner rings 1 and 2 and the cage 4, the surface treatment layer 20 is provided on the outer / inner rings 1 and 2, and the surface treatment layer 20 is provided on the cage 4. It is not necessary. The surface treatment layer 20 may be provided on the cage 4 without providing the surface treatment layer 20 on the outer / inner rings 1 and 2. The outer ring 1 may be provided with the surface treatment layer 20, and the inner ring 2 may not be provided with the surface treatment layer 20.

  FIG. 17 shows the manufacturing process of the outer ring 1. First, an outer ring material 1 </ b> W having a schematic shape of the outer ring 1 is forged from a steel columnar material or a pipe-shaped material. The outer surface of the forged outer ring material 1W is turned. The spherical inner surface of the outer ring material 1W may be rough processed by turning. The turned outer ring material 1W is quenched, and after quenching, the spherical inner surface 5 (FIG. 4) and the inner surface of the track groove 7 are cut after quenching, that is, quenched steel is cut. This hardened steel cutting is performed by turning the spherical inner surface 5 and milling the track groove 7. A CBN tool is used as a turning or milling tool for quenching steel cutting. When the surface treatment layer 20 (FIG. 16) is applied, the treatment is performed after the quenching and cutting.

  FIG. 18 shows the manufacturing process of the inner ring 2. As in the case of the outer ring 1, the inner ring 2 is forged from the inner ring material 2W, cut and quenched the inner ring material 2W, and after the quenching of the spherical outer surface 6 (FIG. 6) and the track groove 8 of the inner ring material 2W. The surface treatment layer 20 is processed in order.

  FIG. 19 shows the manufacturing process of the cage 4. The cage 4 is formed by pressing a cage material, forming a pocket 9 (FIG. 9), quenching, cutting after quenching of at least the inner surface of the pocket 9 among the spherical outer surface 10, the spherical inner surface 11, and the pocket 9. If necessary, the surface treatment layer 20 is processed in order.

  According to the constant velocity universal joint having this configuration, the spherical inner surface 5 of the outer ring 1 or the track groove 7 or both the spherical inner surface 5 and the track groove 7 are used as the cut surfaces after quenching, and the spherical shape of the inner ring 2 is obtained. The outer surface 6, the track groove 8, or both the spherical outer surface 6 and the track groove 8 are used as the cut surfaces after quenching, and at least the pocket 9 among the spherical outer surface 10, the spherical inner surface 11, and the pocket 9 of the cage 4. Since the inner surface is a cut surface after quenching and is a post-quenching cut instead of a conventional grinding step after heat treatment, the processing time is shortened. For example, it takes less than half of the grinding time. As a result, a cost reduction effect can be obtained. In particular, as in the example shown in FIG. 8, when the number of track grooves 7 and 8 is 8, the ratio of groove processing is large in all the processes, and therefore the effect of shortening the processing time and cutting costs by post-quenching cutting. Is big. Since this is a cutting after quenching and heat treatment distortion does not occur thereafter, the dimensional accuracy of each part is ensured by performing the cutting after quenching as described above. For example, it is possible to obtain dimensional accuracy equivalent to grinding. Moreover, since it is set as cutting after quenching, unlike grinding, it is also possible to perform processing without using an environmentally undesirable coolant. That is, in the cutting process, the tool is intermittently applied to the material intermittently, so that the tool is naturally cooled while the tool is separated. Therefore, dry processing is possible.

Because of hardened steel cutting, the machining shape is more flexible than grinding, and the cross-sectional shape of the track grooves 7 and 8 of the outer ring 1 and the inner ring 2 should be an elliptical arc as shown in FIG. You can also. As shown in FIG. 13, the elliptical arc processing changes the touch width of the tool 25 with respect to the material by gradually changing the approach angle (inclination angle) of the milling tool 25 as it advances in the longitudinal direction of the groove. Can be done. Further, by gradually changing the approach angle of the tool 25, as shown in FIG. 12B, the depth H1 from the groove bottom of the track groove 7 to the contact point P is gradually changed, and from the contact point P to the groove opening. Processing with a constant depth H2 is also possible.

  In the case of hardened steel cutting, the surface roughness becomes rougher than the grinding process, but the surface roughness can be improved by providing the surface treatment layer 20 described together with FIGS. When the surface treatment layer 20 is made of a solid lubricant film, it is effective in preventing heat generation due to a lubrication effect until the lubricant in the initial stage of use becomes familiar. When the surface treatment layer 20 is a low-temperature sulfuration treatment layer, the base material is not tempered during the treatment, and it is avoided that the wear resistance is lowered due to a decrease in hardness due to tempering.

It is sectional drawing which shows the state assembled | attached with the shaft to the constant velocity universal joint concerning one Embodiment of this invention. It is an expanded sectional view of an equivalent speed universal joint. It is a front view of an equivalent speed universal joint. It is sectional drawing of the outer ring | wheel in an equivalent speed universal joint. It is a front view of the outer ring. It is sectional drawing of the inner ring | wheel in an equivalent speed universal joint. It is a front view of the inner ring. It is a front view of the modification of the inner ring. (A) and (B) are a sectional view and a front view of a cage in an equivalent speed universal joint, respectively. (A)-(C) are expanded sectional views which show the example of various shapes of the track groove of the outer ring, respectively. It is explanatory drawing which shows the joint radial direction clearance gap of a ball | bowl and a track groove. (A), (B) is sectional drawing which shows each example of the contact point position in the track groove of the outer ring, respectively. It is explanatory drawing which shows the example of a cutting process after hardening of the track groove | channel of the same outer ring | wheel. It is sectional drawing which shows the formation state of the surface treatment layer of the same holder | retainer. It is an expanded sectional view of the modification of the same surface treatment layer. It is sectional drawing which shows the formation state of the surface treatment layer of the outer ring | wheel and an inner ring | wheel. It is process explanatory drawing which shows the manufacturing process of the same outer ring | wheel. It is process explanatory drawing which shows the manufacturing process of the same inner ring. It is process explanatory drawing which shows the manufacturing process of the same holder | retainer.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Outer ring 2 ... Inner ring 3 ... Ball 4 ... Cage 5 ... Spherical inner surface 6 of outer ring ... Spherical outer surface 7 of inner ring ... Track groove 8 of outer ring ... Track groove 9 of inner ring ... Pocket 10 ... Spherical outer surface 11 of cage Spherical inner surface 12 ... Mouse 13 ... Mounting flange 14 ... Opening 15 ... Cylindrical mounting portion 16 ... Shaft 20 ... Surface treatment layer 21 ... Underlayer d1, d2 ... Joint radial gap d3 ... Axial gap O0 ... Joint angle Center O1 ... Center of curvature of outer ring track groove O2 ... Center of curvature of inner ring track groove

Claims (9)

A track groove with a curved groove bottom longitudinal section is formed along the axial direction on the spherical inner surface of the outer ring, and a track groove with a curved groove bottom longitudinal section is formed on the outer ring of the outer ring. The cage is formed oppositely, and a ball is incorporated between these track grooves, and a spherical outer surface that is in surface contact with the spherical inner surface of the outer ring, and a surface contact with the spherical outer surface of the inner ring, in a cage having a pocket in which the ball is accommodated. For a drive shaft in which a spherical inner surface is provided and the center of curvature of the track groove in the axial cross section of the outer ring and the center of curvature of the track groove in the axial cross section of the inner ring are offset equidistantly to the left and right with respect to the angular center of the joint In constant velocity universal joints,
A constant velocity universal joint characterized in that the spherical inner surface of the outer ring, or the track groove, or both of the spherical inner surface and the track groove are used as a cut surface after quenching.   The constant velocity universal joint according to claim 1, wherein the spherical outer surface of the inner ring, the track groove, or both of the spherical outer surface and the track groove are cut surfaces after quenching.   The constant velocity universal joint according to claim 1 or 2, wherein at least an inner surface of the spherical outer surface, spherical inner surface, and pocket of the cage is a quenched surface after quenching.   The constant velocity universal joint according to any one of claims 1 to 3, wherein eight track grooves of the inner and outer rings are formed.   The constant velocity universal joint according to any one of claims 1 to 4, wherein a surface treatment layer for reducing frictional resistance is formed at least on the surface of the cage.   The constant velocity universal joint according to claim 5, wherein the surface treatment layer is a coating layer of a solid lubricant.   The constant velocity universal joint according to claim 5, wherein the surface treatment layer is a low temperature sulfuration treatment layer.   The constant velocity universal joint according to any one of claims 1 to 7, wherein a clearance in a joint radial direction between the track groove and the ball of the inner and outer rings is set to 0.05 mm or less.   The constant velocity universal joint according to any one of claims 1 to 9, wherein a cross-sectional shape of a track groove of the outer ring is an elliptical arc shape.

Images