Outside joint member for constant velocity universal joint and fixed constant velocity universal joint comprising the same

Abstract

To realize a low-cost outside joint member for a constant velocity universal joint capable of ensuring required maximum operation angle and durability.SOLUTION: In an outside joint member 2 for a constant velocity universal joint, a plurality of outside track grooves 24 where balls 4 roll is formed on a spherical inner peripheral surface 23 of a mouth part 21 having a bottomed bowl shape, and a surface-hardened layer 6 formed by heat treatment is provided in an inner diameter surface part of the mouth part 21 including the spherical inner peripheral surface 23 and the outside track grooves 24, where a tapered surface 26 is provided between a groove bottom surface of the outside track groove (24) and an opening end surface (25) of the mouth part (21) to connect the two. The tapered surface (26) is formed so that an angle θ1 between itself and the groove bottom surface of the outside track groove (24) and an angle θ2 between itself and the opening end surface (25) are both 100° or larger, and an angle θ3 with respect to a rotational axis is 15° or larger and 40° or less.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an outer joint member for a constant velocity universal joint and a fixed type constant velocity universal joint including the outer joint member. [Background technology]

[0002] As is well known, automobiles equipped with a drive source such as an engine or electric motor on their chassis are equipped with a power transmission device such as a drive shaft or propeller shaft to transmit the output (torque) of the drive source to the wheels. This power transmission device connects two shafts, a drive shaft and a driven shaft, and is equipped with a constant velocity universal joint that can transmit torque at a constant velocity regardless of the operating angle of the two connected shafts (regardless of relative angular displacement). Constant velocity universal joints are broadly divided into fixed-type constant velocity universal joints that allow only angular displacement of the two connected shafts, and sliding-type constant velocity universal joints that allow angular and axial displacement of the two connected shafts.

[0003] For example, as described in Patent Document 1 below, a fixed constant velocity universal joint constituting a drive shaft includes an outer joint member having a cup-shaped mouth portion with a bottom and a plurality of outer track grooves formed on the spherical inner peripheral surface of the mouth portion, an inner joint member having a plurality of inner track grooves formed on the spherical outer peripheral surface, a plurality of balls interposed between the paired outer and inner track grooves to transmit torque between the two joint members, and a cage that holds the balls at intervals in the circumferential direction. The inner joint member is connected to (the inner joint member of) a sliding constant velocity universal joint via a shaft member also called an intermediate shaft so as to be able to transmit torque. To ensure the durable life required of the fixed constant velocity universal joint, at least the balls and the outer and inner track grooves in which the balls roll are subjected to heat treatment such as quenching and tempering.

[0004] Incidentally, the maximum value of the amount of angular displacement (maximum operating angle) required for a fixed type constant velocity universal joint when an automobile is being driven (operated) differs depending on the application, as exemplified below. Automobile front drive shaft: 45° or more Automotive rear drive shaft: 20°~30° Automobile propeller shaft: 10° or less As such, the maximum operating angle required for a fixed constant velocity universal joint for a rear driveshaft (hereinafter also referred to as a "rear CVJ" for short) is significantly smaller than that required for a fixed constant velocity universal joint for a front driveshaft (hereinafter also referred to as a "front CVJ" for short). Therefore, the length of the outer track groove (effective track length) can be shorter in a rear CVJ than in a front CVJ. Therefore, a smaller outer joint member with a more compact mouth portion in the axial direction is used in a rear CVJ compared to a front CVJ. This allows for the fixed constant velocity universal joint, and ultimately the suspension components of an automobile, to be made lighter and more compact.

[0005] A specific example will be described based on the partial vertical cross-sectional view of a front CVJ shown in Fig. 7(a) and the partial vertical cross-sectional view of a rear CVJ shown in Fig. 7(b). The front CVJ 100 shown in Fig. 7(a) includes an outer joint member 101 having a bowl-shaped mouth portion 102 with a bottom and a plurality of outer track grooves 102a formed on the spherical inner peripheral surface of the mouth portion 102, an inner joint member 103 having a plurality of inner track grooves 103a formed on the spherical outer peripheral surface, a plurality of balls 104 arranged between pairs of track grooves 102a, 103a, and a cage 105 that holds the plurality of balls 104 at intervals in the circumferential direction. The rear CVJ 110 shown in Fig. 7(b) includes an outer joint member 111, an inner joint member 113, balls 114, and a cage 115 that correspond to the above-mentioned components of the front CVJ 100, respectively.

[0006] The major difference between the rear CVJ 110 and the front CVJ 100 is that, as described above, the mouth portion of the outer joint member has been made more compact in the axial direction. As is clear from comparing Figures 7(a) and 7(b), the mouth portion 112 of the outer joint member 111 of the rear CVJ 110 is shorter in the axial direction on the opening side of the axis-orthogonal plane P passing through the joint center O, compared to the mouth portion 102 of the outer joint member 101 of the front CVJ 100. Note that for the inner joint member 113 of the rear CVJ 110, a dedicated part that is designed to be compact in accordance with the more compact mouth portion 112 may be used, or the inner joint member 103 of the front CVJ 100 may be used.

[0007] As described above, the rear CVJ 110 requires a small maximum operating angle, and therefore does not need to provide a large tapered portion (also referred to as an "inlet chamfer") 106 [see FIG. 7(a)] on the inner peripheral edge of the opening end of the mouth portion 112 of the outer joint member 111 to avoid interference with the shaft member, as is provided on the inner peripheral surface of the opening end of the mouth portion 102 of the outer joint member 101 of the front CVJ 100. Therefore, as shown in FIG. 7(c), which is a partially enlarged view of FIG. 7(b), in the rear CVJ 110, an edge formed at an intersection C between (the groove bottom surface of) an outer track groove 112a formed on the spherical inner peripheral surface of the mouth portion 112 of the outer joint member 111 and the opening end face 112b of the mouth portion 112 is a so-called sharp edge, in which the angle α formed by the two surfaces 112a, 112b forming the edge is an acute angle. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Patent No. 6863785 Summary of the Invention [Problem to be solved by the invention]

[0009] As described above, if the edge formed at the intersection C between (the groove bottom surface of) the outer track groove 112a and the opening end surface 112b becomes a sharp edge, the intersection C becomes a location where heat is concentrated during heat treatment, making it harder than other locations. This increases the crack sensitivity at the intersection C (making it easier for cracks to occur near the intersection C), and there are cases where the required fatigue strength cannot be ensured. In order to prevent such problems as much as possible, measures such as devising innovative ways of implementing the heat treatment are sometimes taken, but this inevitably increases costs due to the more complicated heat treatment.

[0010] In view of the above circumstances, an object of the present invention is to ensure a desired maximum operating angle and fatigue strength for an outer joint member that constitutes a fixed constant velocity universal joint (rear CVJ), particularly for a rear drive shaft, thereby realizing a high-quality rear CVJ with excellent durability at low cost. [Means for solving the problem]

[0011] The present invention, which has been devised to achieve the above object, provides an outer joint member for a constant velocity universal joint, which has a bowl-shaped mouth portion with one open end and a bottom, a plurality of outer track grooves in which balls roll are formed on the spherical inner peripheral surface of the mouth portion, and a surface-hardened layer formed by quenching is provided on the inner diameter surface layer portion of the mouth portion including the spherical inner peripheral surface and the outer track grooves, a tapered surface is provided between the groove bottom surface of the outer track groove and the opening end surface of the mouth portion, connecting the two; The tapered surface is characterized in that the angle θ1 formed with the groove bottom surface and the angle θ2 formed with the opening end surface are both 100° or more, and the angle θ3 formed with the rotation axis is 15° or more and 40° or less. This rotation axis refers to the rotation axis when a constant velocity universal joint, which includes this outer joint member for a constant velocity universal joint as a component, is mounted on, for example, a vehicle and rotates.

[0012] As described above, by providing a tapered surface connecting the groove bottom surface of the outer track groove and the opening end surface of the mouth portion, and by making the angle θ1 between this tapered surface and the groove bottom surface of the outer track groove and the angle θ2 between this tapered surface and the opening end surface both obtuse angles of 100° or greater, it is possible to prevent excessive heat input to the intersection between the tapered surface and the groove bottom surface and the intersection between the tapered surface and the opening end surface due to heating during heat treatment. This makes it possible to avoid increased crack sensitivity due to the two intersections being harder than other locations. Furthermore, this effect can be achieved by additionally providing a tapered surface of a predetermined angle in the preform of the outer joint member to be subjected to heat treatment, without any special modifications to the form or conditions of the heat treatment. Therefore, an outer joint member with desired fatigue strength can be produced at low cost.

[0013] When the maximum operating angle set for a constant velocity universal joint is changed, the total length (effective track length) of the outer track grooves must also be changed accordingly. However, because the present invention requires the above conditions (θ1 ≥ 100° and θ2 ≥ 100°) to be satisfied, the angle θ3 formed by the tapered surface with respect to the rotation axis must be appropriately set in order to ensure the required effective track length. Here, "effective track length" refers to the length of the track grooves within which balls can contact (roll). If this effective track length is insufficient, the balls will fall out of the outer track grooves, preventing torque transmission between the outer joint member and the inner joint member—in other words, preventing the desired operating angle. As will be described in detail later, the inventors' investigations have shown that an outer joint member with the required effective track length, particularly for a rear CVJ, can be achieved by setting θ3 between 15° and 40° (15° ≤ θ3 ≤ 40°).

[0014] It is preferable that the entire opening side end of the groove bottom surface of the track groove is connected to the opening end surface via the tapered surface. In this case, the axial width of the tapered surface can be constant over the entire area in the groove width direction of the track groove, or can be gradually reduced from the ends on one and the other sides in the groove width direction of the track groove toward the center in the groove width direction.

[0015] The tapered surface can be, for example, a machined surface obtained by pressing an end mill (the blade of an end mill), which is a type of cutting tool, against the tapered surface, or a formed surface formed by plastic processing. In short, the processing method for obtaining the tapered surface can be selected arbitrarily.

[0016] In the above configuration, the number of track grooves can be six or eight.

[0017] The outer joint member according to the present invention having the above-mentioned configuration can form a fixed constant velocity universal joint in cooperation with the inner joint member that is disposed on the inner periphery of the mouth portion and has a plurality of track grooves on its spherical outer circumferential surface in which balls roll, the balls that are interposed between the track grooves of the outer joint member and the track grooves of the inner joint member to transmit torque between the two joint members, and a cage that holds the balls. Since the outer joint member according to the present invention has the above-mentioned features, this fixed constant velocity universal joint is a joint with excellent durability and a long life. [Effects of the Invention]

[0018] As described above, according to the present invention, it is possible to realize at low cost an outer joint member of a fixed type constant velocity universal joint (particularly a fixed type constant velocity universal joint for a rear drive shaft) that ensures a desired maximum operating angle and fatigue strength, thereby realizing at low cost a high-quality fixed type constant velocity universal joint with excellent durability. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a longitudinal sectional view of a fixed type constant velocity universal joint including an outer joint member according to an embodiment of the present invention, in a state where an operating angle is 0°. [Figure 2] 1. FIG. 1(a) is a partially enlarged view of FIG. 1, and FIG. 1(b) is an enlarged view of part A1 in FIG. 1(a). [Figure 3] FIG. 1(a) is a partially enlarged view of a fixed type constant velocity universal joint according to a modified example, and FIG. 1(b) is an enlarged view of a portion A2 in FIG. 1(a). [Figure 4] FIG. 2( a ) is a partial schematic perspective view of an outer joint member according to an embodiment of the present invention, and FIG. 2( b ) is a partial schematic perspective view of an outer joint member according to a modified example. [Figure 5] FIG. 10 is a longitudinal sectional view of a fixed type constant velocity universal joint including an outer joint member according to another embodiment of the present invention, in a state where the operating angle is 0°. [Figure 6] 5, and FIG. 6(b) is an enlarged view of part A3 in FIG. 6(a). [Figure 7] Figure (a) is a partial longitudinal cross-sectional view of a conventional fixed type constant velocity universal joint for a front drive shaft, Figure (b) is a partial longitudinal cross-sectional view of a conventional fixed type constant velocity universal joint for a rear drive shaft, and Figure (c) is an enlarged partial view of Figure (b). DETAILED DESCRIPTION OF THE INVENTION

[0020] Hereinafter, an embodiment of the present invention will be described with reference to the drawings (FIGS. 1 to 6).

[0021] FIG. 1 shows a longitudinal cross-sectional view of a fixed constant velocity universal joint 1 according to one embodiment of the present invention, with an operating angle of 0°. This fixed constant velocity universal joint 1 is arranged along the vehicle width direction of an automobile and is used as a component of a drive shaft (rear drive shaft) that transmits the output (torque) of a drive source such as an engine or electric motor mounted on the chassis of the automobile to the rear wheels of the automobile, and is connected to a wheel bearing device (not shown) that rotatably supports the rear wheels. The rear drive shaft connects the fixed constant velocity universal joint 1 and a sliding-type constant velocity universal joint (not shown), which are arranged at a distance in the vehicle width direction of the automobile, via a shaft member (not shown) also called an intermediate shaft, so that torque can be transmitted. Note that hereinafter, the fixed constant velocity universal joint 1 will also be simply referred to as the "constant velocity universal joint 1."

[0022] 1 includes an outer joint member 2, an inner joint member 3, a plurality of balls 4 that transmit torque between the two joint members 2, 3, and a cage 5 that holds the balls 4, and a maximum relative angular displacement of 30° is permitted between the two joint members 2, 3. In other words, the maximum operating angle of this constant velocity universal joint 1 is 30°.

[0023] The outer joint member 2 integrally comprises a bottomed, bowl-shaped mouth portion 21 and a shaft portion 22 extending axially outward from the bottom of the mouth portion 21, and a plurality of outer track grooves 24 corresponding to the number of balls 4 are formed at equal intervals in the circumferential direction on the spherical inner peripheral surface 23 of the mouth portion 21.

[0024] The inner joint member 3 is formed in an annular shape and is disposed on the inner circumference of the mouth portion 21 of the outer joint member 2. A plurality of inner track grooves 32 corresponding to the number of balls 4 are formed at equal intervals in the circumferential direction on a spherical outer peripheral surface 31 of the inner joint member 3. A spline 33 is formed on the inner peripheral surface (inner wall surface of the shaft hole) of the inner joint member 3, and a spline formed on the outer peripheral surface of one end of the shaft member is fitted into this spline 33. An inner joint member of a sliding type constant velocity universal joint is spline-fitted to the other end of the shaft member, whereby (the inner joint member 3 of) the constant velocity universal joint 1 and (the inner joint member of) the sliding type constant velocity universal joint are connected via the shaft member so as to be able to transmit torque.

[0025] The plurality of balls 4 are respectively interposed in ball tracks formed between pairs of track grooves 24, 32, and transmit torque between the outer joint member 2 and the inner joint member 3. The number of balls 4 is six or eight.

[0026] The cage 5 is formed in an annular shape from a metal or resin material, and is disposed between the spherical inner peripheral surface 23 of the mouth portion 21 of the outer joint member 2 and the spherical outer peripheral surface 31 of the inner joint member 3. The cage 5 has a plurality of pockets 51 that open onto its spherical outer peripheral surface and spherical inner peripheral surface, and are formed at equal intervals in the circumferential direction, and the balls 4 are individually held by the pockets 51.

[0027] The outer joint member 2, the inner joint member 3, and the ball 4 are all made of steel such as carbon steel or alloy steel, and surface-hardened layers are formed by heat treatment such as quenching and tempering in areas requiring high mechanical strength and hardness, such as the inner diameter surface layer of the mouth portion 21 of the outer joint member 2, the outer diameter surface layer of the inner joint member 3, and the surface layer of the ball 4. In Fig. 1, only the surface-hardened layer 6 provided on the mouth portion 21 of the outer joint member 2 is shown by cross-hatching.

[0028] Although not shown in the figure, a cylindrical boot is fitted between the outer joint member 2 and the shaft member, and this boot prevents the lubricant such as grease sealed in the internal space of the mouth portion 21 of the outer joint member 2 from leaking out and prevents foreign matter from entering the internal space of the joint.

[0029] The fixed type constant velocity universal joint 1 of this embodiment having the above configuration is for a rear drive shaft with a maximum working angle of 30°, and therefore, as with the conventional outer joint member 111 illustrated in Fig. 7(b), the mouth portion 21 is made compact in the axial direction, and the mouth portion 21 does not have a large tapered portion 106 (inlet chamfer) on the opening side inner peripheral edge portion for avoiding interference with the shaft member as illustrated in Fig. 7(a). However, the mouth portion 21 of the outer joint member 2 is provided with a characteristic configuration described below that is not adopted in the conventional outer joint member 111, making it possible to realize a high-quality fixed type constant velocity universal joint 1 that ensures the required maximum working angle and durable life at low cost.

[0030] 2(a)(b) and 3(a)(b), a tapered surface (track entrance chamfer) 26 is provided between the groove bottom surface of the outer track groove 24 and the opening end surface 25 of the mouth portion 21, connecting the two, and the angle (first taper angle) θ1 that this tapered surface 26 makes with the groove bottom surface of the outer track groove 24 and the angle (second taper angle) θ2 that this tapered surface 26 makes with the opening end surface 25 are both obtuse angles of 100° or more. In the example shown in Fig. 2, θ1 = 152° and θ2 = 105°, and in the example shown in Fig. 3, θ1 = 131° and θ2 = 125°. The tapered surfaces 26 may be formed, for example, as a formed surface that is formed simultaneously with the forging of the outer track grooves 24 on a preform of an outer joint member to be subjected to heat treatment such as quenching and tempering, or may be a machined surface that is obtained by subjecting the preform from which the outer track grooves 24 have been forged to machining such as cutting.

[0031] The provision of the tapered surface 26 as described above makes it possible to prevent excessive heat input to the intersection (first intersection) C1 between the tapered surface 26 and the groove bottom surface of the outer track groove 24 and the intersection (second intersection) C2 between the tapered surface 26 and the opening end surface 25 when the outer joint member 2 (preform) is subjected to heat treatment. This makes it possible to avoid increased crack sensitivity due to the two intersections C1 and C2 being harder than other locations. This effect can be achieved simply by additionally providing the tapered surface 26 of a predetermined angle on the preform of the outer joint member 2 to be subjected to heat treatment, without any special efforts being made to the mode or conditions of heat treatment. Therefore, according to the present invention, an outer joint member 2 having a desired fatigue strength can be realized at low cost.

[0032] If the maximum operating angle set for the constant velocity universal joint 1 is changed, it becomes necessary to change the length of the outer track groove 24 (effective track length EL: see Figures 2(b) and 3(b)) accordingly. However, due to the configuration of the present invention, which requires that the above-mentioned first taper angle θ1 and second taper angle θ2 both be 100° or greater (θ1≧100° and θ2≧100°), there is a problem that unless the angle (third taper angle) θ3 formed by the tapered surface 26 with respect to the rotation axis is appropriately set, the required effective track length EL, in other words, the maximum operating angle, cannot be secured.

[0033] 2 and 3, under the above-mentioned conditions of θ1 ≧ 100° and θ2 ≧ 100°, as the third taper angle θ3 decreases, the first taper angle θ1 increases while the second taper angle θ2 decreases (conversely, as the third taper angle θ3 increases, the first taper angle θ1 decreases while the second taper angle θ2 increases). Here, if the distance between the first intersection point C1 and the second intersection point C2 (the length of the tapered surface 26) is too small, the effect of preventing excessive heat input to the intersection points C1 and C2 during the heating stage of heat treatment cannot be adequately obtained, and there is a concern that it may become difficult to ensure the fatigue strength required for the outer joint member 2. To avoid this situation, the third taper angle θ3 can be reduced to increase the distance between the first intersection point C1 and the second intersection point C2. However, as the third taper angle θ3 is reduced, the first intersection point C1 shifts toward the rear (opposite the opening) of the mouth portion 21, shortening the effective track length EL and potentially making it impossible to ensure the desired maximum operating angle (30° in this case). Taking the above into consideration, in the present invention, the third taper angle θ3 is set to 15° or greater and 40° or less (15°≦θ3≦40°). In this embodiment, in which the maximum operating angle is 30°, the third taper angle θ3 is set to 15° or greater and 35° or less (15°≦θ3≦35°). This makes it possible to obtain an outer joint member 2 that ensures the effective track length EL and fatigue strength required for the constant velocity universal joint 1.

[0034] As shown in FIGS. 3(a) and 3(b), the tapered surface 26 is formed so that the entire opening-side end of the groove bottom of the track groove 24 is connected to the opening end surface 25 via the tapered surface 26. In this case, the axial width of the tapered surface 26 can be constant over the entire area in the groove width direction (circumferential direction) of the track groove 24 as shown in FIG. 4(a), or can be gradually reduced from the ends on one and the other sides in the groove width direction of the track groove 24 toward the center in the groove width direction as shown in FIG. 4(b). The tapered surface 26 shown in FIG. 4(b) can be obtained, for example, by pressing an end mill, which is a type of cutting tool, against the inner peripheral edge portion of the opening side of the mouth portion 21. In this case, the tapered surface 26 is a machined surface obtained by cutting.

[0035] Figure 5 is a longitudinal sectional view of a fixed type constant velocity universal joint 1 including an outer joint member 2 according to another embodiment of the present invention. In the constant velocity universal joint 1 shown in the figure, the outer joint member 2 and the inner joint member 3 are capable of relative angular displacement of up to 25°, that is, the maximum operating angle is set to 25°. Since the maximum operating angle of the constant velocity universal joint 1 shown in Figure 5 is smaller than that of the constant velocity universal joint 1 shown in Figure 1, the outer joint member 2 used has a mouth portion 21 that is even more compact in the axial direction than the outer joint member 2 shown in Figure 1.

[0036] The outer joint member 2 of the constant velocity universal joint 1 shown in Fig. 5 also employs a characteristic configuration similar to that of the outer joint member 2 shown in Fig. 1. That is, as illustrated in Figs. 6(a) and 6(b), a tapered surface (track inlet chamfer) 26 connecting the groove bottom surface of the outer track groove 24 and the opening end surface 25 of the mouth portion 21 is provided between them, and the angle (first taper angle) θ1 that this tapered surface 26 forms with the groove bottom surface of the outer track groove 24 and the angle (second taper angle) θ2 that this tapered surface forms with the opening end surface 25 are both obtuse angles of 100° or more. In the figures, θ1 = 133° and θ2 = 130°.

[0037] Furthermore, in order to ensure the required effective track length EL, in other words, the maximum operating angle, the angle (third taper angle) θ3 formed by the tapered surface 26 with respect to the rotation shaft is set to 40°. With the above configuration, it is possible to realize the outer joint member 2 at low cost, which ensures the required effective track length EL and fatigue strength.

[0038] Although the fixed type constant velocity universal joint 1 including the outer joint member 2 according to the embodiment of the present invention has been described above, the embodiment of the present invention is not limited to this. For example, the number of balls 4 incorporated into the constant velocity universal joint 1 may be eight or more, specifically ten or twelve.

[0039] The present invention is not limited to the above-described embodiments, and may be embodied in various forms without departing from the spirit of the present invention. The scope of the present invention is defined by the claims, and includes the equivalent meanings of the claims and all modifications within the scope of the claims. [Explanation of symbols]

[0040] 1 Fixed constant velocity universal joint 2 Outer joint member 3 Inner joint member 4 balls 5 Cage 6 Surface hardening layer 21 Mouse section 23 Spherical inner surface 24 outer track groove 25 Open end face 25 Tapered surface EL Effective track length θ1 angle (first taper angle) θ2 angle (second taper angle) θ3 angle (third taper angle)

Claims

1. a mouth portion that is shaped like a bowl with a bottom and an open end in the axial direction, and a plurality of outer track grooves in which balls roll are formed on the spherical inner peripheral surface of the mouth portion; In the outer joint member for a constant velocity universal joint, a surface hardened layer is provided by heat treatment on an inner diameter surface layer portion of the mouth portion including the spherical inner peripheral surface and the outer track groove, a tapered surface is provided between the groove bottom surface of the outer track groove and the opening end surface of the mouth portion, connecting the two surfaces; the tapered surface is formed so that an angle θ1 formed between the tapered surface and the groove bottom surface and an angle θ2 formed between the tapered surface and the opening end surface are both 100° or more, and an angle θ3 formed with respect to a rotation axis is 15° or more and 40° or less.

2. 2. The outer joint member for a constant velocity universal joint according to claim 1, wherein the entire opening side end of the groove bottom surface is connected to the opening end surface via the tapered surface.

3. 3. The outer joint member for a constant velocity universal joint according to claim 2, wherein the axial width of the tapered surface gradually decreases from the ends on one and the other sides in the groove width direction of the outer track groove toward the center in the groove width direction.

4. 2. The outer joint member for a constant velocity universal joint according to claim 1, wherein the tapered surface is a formed surface formed by plastic working.

5. 2. The outer joint member for a constant velocity universal joint according to claim 1, wherein the number of said outer track grooves is six or eight.

6. 6. A fixed type constant velocity universal joint comprising: the outer joint member for a constant velocity universal joint according to any one of claims 1 to 5; an inner joint member that is disposed on an inner periphery of the mouth portion and has a plurality of inner track grooves on a spherical outer circumferential surface on which balls roll; balls that are interposed between the outer track grooves and the inner track grooves to transmit torque between both joint members; and a cage that holds the balls.

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