Chuck device and manufacturing method of outer joint member

Abstract

To eliminate a tailstock part which is disposed facing a centering part of a chuck body and hold an outer joint member in a cantilever state.SOLUTION: A cup-shaped outer joint member 11 is aligned and held with a chuck device when the outer joint member forming a constant-velocity universal joint and including track grooves 18 extending in an axial direction and formed at multiple positions of an inner peripheral surface 19 in a circumferential direction is processed. The chuck device includes: fixed pin 33 each of which is provided at the tip side of a chuck body 31 and engages with a back side portion of the track groove 18; movable pins 34 each of which is provided at a fixed pin front side of the chuck body 31 and engages with an opening side portion of the track groove 18; a clamp mechanism 35 which causes the movable pins 34 to protrude to the radial outer side during clamping; and an unclamp mechanism 36 which causes the movable pins 34 to retreat to the radial inner side during unclamping.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a chuck device for centering and gripping an outer joint member in a manufacturing process of an outer joint member that constitutes a constant velocity universal joint, and to a manufacturing method of an outer joint member. [Background technology]

[0002] For example, constant velocity universal joints used in the power transmission systems of automobiles and various industrial machines, and particularly incorporated into the drive shafts and propeller shafts of automobiles, are classified into two types: fixed type constant velocity universal joints and sliding type constant velocity universal joints.

[0003] These two types of constant velocity universal joints have a structure in which two shafts, a driving side and a driven side, are connected together and are capable of transmitting rotational torque at a constant speed regardless of the operating angle of the two shafts.

[0004] A drive shaft that transmits power from an automobile engine to the wheels must accommodate angular and axial displacements that occur due to changes in the relative positional relationship between the engine and the wheels.

[0005] For this reason, drive shafts are generally equipped with a sliding type constant velocity universal joint on the engine side (inboard side), which allows both axial and angular displacement, and a fixed type constant velocity universal joint on the wheel side (outboard side), which allows only angular displacement, with the two constant velocity universal joints connected by a shaft.

[0006] The main parts of the constant velocity universal joint that constitutes the drive shaft are composed of an outer joint member, an inner joint member, balls, and a cage. The outer joint member is composed of a mouth portion that houses the inner joint member, balls, and a cage, and a stem portion that extends in the axial direction from the mouth portion.

[0007] The mouth portion of the outer joint member constituting the constant velocity universal joint is cup-shaped with one end open, and has track grooves extending in the axial direction formed at a plurality of positions in the circumferential direction on its inner circumferential surface.

[0008] The outer joint member is produced by subjecting a solid rod-shaped material (bar material) to cold plastic processing such as forging and ironing, machining such as cutting and grinding, and heat treatment.

[0009] In the cutting process in manufacturing the outer joint member, for example, the outer peripheral surface and end surfaces of the outer joint member are cut while the outer joint member is held in a centered state by a chuck device disclosed in Patent Document 1. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] JP 2014-233782 A Summary of the Invention [Problem to be solved by the invention]

[0011] The chuck device disclosed in Patent Document 1 has a centering portion having a spherical tip provided at the tip of the chuck body (see FIG. 6 of Patent Document 1).

[0012] In this chuck device, the centering portion is engaged with the track groove of the outer joint member in a state where the centering portion is aligned in phase with the track groove of the outer joint member, thereby positioning and centering the outer joint member (see FIG. 8 of Patent Document 1).

[0013] On the other hand, a pointed core pushing portion is disposed opposite the tip of the chuck body. When centering the outer joint member, the core pushing portion is engaged with a center hole formed in advance in the end face of the stem portion of the outer joint member (see FIG. 8 of Patent Document 1).

[0014] In this manner, the centering portion is engaged with the track groove of the outer joint member to perform centering, and the center pushing portion is engaged with the center hole of the stem portion to perform center pushing, thereby clamping the outer joint member from both sides.

[0015] Here, in the chuck device of Patent Document 1, a process of previously machining a center hole into which the core pushing portion engages in the end face of the stem portion of the outer joint member must be performed by another facility, making it difficult to reduce the number of steps.

[0016] In addition, since the core pushing portion is disposed opposite to the tip of the chuck body, it is difficult to transfer the outer joint member in equipment with two opposing shafts, and as a result, it is difficult to accurately determine the phase of the outer joint member between processes.

[0017] Therefore, the present invention has been proposed in consideration of the above-mentioned problems, and an object of the present invention is to provide a chuck device and a manufacturing method for an outer joint member that can hold an outer joint member in a cantilevered state by eliminating the centering portion of the chuck body and the core pushing portion arranged opposite to the centering portion. [Means for solving the problem]

[0018] The present invention provides a chuck device that centers and grips an outer joint member that constitutes a constant velocity universal joint and has axially extending track grooves formed at multiple locations around the circumference of its inner circumferential surface when machining the outer joint member.

[0019] As technical means for achieving the above-mentioned object, a chuck device according to the present invention is characterized in comprising: a fixed pin provided on the tip side of a chuck body and engaging with a deep side portion of the track groove; a movable pin provided on the front side of the fixed pin of the chuck body and engaging with an opening side portion of the track groove; a clamping mechanism which causes the movable pin to protrude radially outward when clamping; and an unclamping mechanism which causes the movable pin to retract radially inward when unclamping.

[0020] In the present invention, the fixed pin located on the tip side of the chuck body is engaged with the rear portion of the track groove of the outer joint member, and the movable pin located on the front side of the fixed pin of the chuck body is engaged with the opening side portion of the track groove of the outer joint member.

[0021] The movable pin is engaged with the opening side portion of the track groove by a clamping mechanism, and is released from the opening side portion of the track groove by an unclamping mechanism.

[0022] In this way, the outer joint member can be centered and held in a cantilevered state by the fixed pin and the movable pin that engage with two locations, the deep side and the opening side, of the track groove of the outer joint member, making the conventional center pressing portion that engages with the center hole of the stem portion of the outer joint member to center the outer joint member unnecessary.

[0023] The clamping mechanism of the present invention includes a rod arranged in the chuck body so as to be movable in the axial direction, and a movable pin arranged in the chuck body so as to be movable in the radial direction. The clamping mechanism is preferably configured such that the movable pin can be protruded radially outward by the axial movement of the rod due to the contact between a tapered surface of the rod and a tapered surface of the movable pin.

[0024] With this structure, the axial movement of the rod presses the tapered surface of the movable pin that abuts against the tapered surface of the rod, causing the movable pin to protrude radially outward and engage with the track groove. With this simple structure, the outer joint member can be held in a cantilevered state.

[0025] The unclamping mechanism of the present invention includes a rod arranged on the chuck body so as to be movable in the axial direction, and a cam arranged on the chuck body so as to be rotatable while being engaged with the movable pin. The unclamping mechanism is preferably configured such that the movable pin can be retracted radially inward by the rotation of the cam accompanying the axial movement of the rod due to the contact between the tapered surface of the rod and the cam.

[0026] With this structure, the cam that comes into contact with the tapered surface of the rod is pressed and rotated by the axial movement of the rod, so that the movable pin can be retracted radially inward and removed from the track groove. With this simple structure, the outer joint member can be released from the cantilevered state.

[0027] Moreover, the present invention provides a method for manufacturing a cup-shaped outer joint member which constitutes a constant velocity universal joint and has axially extending track grooves formed at multiple locations in the circumferential direction on an inner peripheral surface thereof, the method comprising: centering and gripping the outer joint member to machine the outer joint member using a chuck device including: a fixed pin provided on a tip side of a chuck body and engaging with a deep side portion of the track groove; a movable pin provided on a front side of the fixed pin of the chuck body and engaging with an opening side portion of the track groove; a clamping mechanism which causes the movable pin to protrude radially outward when clamping; and an unclamping mechanism which causes the movable pin to retract radially inward when unclamping. Effect of the Invention

[0028] According to the present invention, the outer joint member can be centered and held in a cantilevered state by the fixed pin and the movable pin that engage with two locations, the deep side and the opening side, of the track grooves of the outer joint member, thereby eliminating the need for a conventional center pushing portion that engages with the center hole of the stem portion of the outer joint member to center push the outer joint member when machining the outer joint member.

[0029] As a result, it is not necessary to perform a process of previously machining the center hole, with which the core pushing portion engages, on the end face of the stem of the outer joint member in a separate facility. This reduces the number of processes. Also, the outer joint member can be transferred within the facility with two opposing shafts. This allows the phase of the outer joint member to be determined accurately between processes. [Brief description of the drawings]

[0030] [Figure 1] 1 is a cross-sectional view showing an overall configuration of a chuck device according to an embodiment of the present invention. [Diagram 2] 2A is a cross-sectional view taken along line PP in FIG. 1, and FIG. 2B is a cross-sectional view taken along line QQ in FIG. [Diagram 3] 2 is a sectional view showing a state in which the rod in FIG. 1 has been advanced with an outer joint member attached. FIG. [Figure 4] FIG. 4 is a cross-sectional view showing a fixing pin on the tip side of the chuck body in the state shown in FIG. 3. [Diagram 5] FIG. 4 is a cross-sectional view showing a state in which the outer joint member is clamped. [Figure 6] FIG. 6 is a cross-sectional view showing a retracted state of the rod in FIG. 5. [Figure 7] FIG. 4 is a cross-sectional view showing a state in which the outer joint member is unclamped. [Figure 8] 1 is a cross-sectional view showing an overall configuration of a constant velocity universal joint having an outer joint member applied to a chuck device. [Figure 9] FIG. 9 is a cross-sectional view taken along line RR in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a chuck device according to the present invention will be described below in detail with reference to the drawings. Before describing the chuck device, a constant velocity universal joint having an outer joint member applied to the chuck device will be described in detail.

[0032] In the following embodiments, a Rzeppa type constant velocity universal joint (BJ), which is a fixed type constant velocity universal joint that is incorporated into the wheel side (outboard side) of an automobile drive shaft, is exemplified, but the present invention is also applicable to an undercut-free type constant velocity universal joint (UJ).

[0033] The present invention can also be applied to other constant velocity universal joints, such as a double offset constant velocity universal joint (DOJ), which is a sliding type constant velocity universal joint that is incorporated into the engine side (inboard side) of an automobile drive shaft.

[0034] 8 and 9, the constant velocity universal joint of this embodiment includes a cup-shaped outer joint member 11, an inner joint member 12, a plurality of balls 13 (eight in FIG. 9), and a cage 14. A shaft 15 is coupled to the inner joint member 12 in a manner capable of transmitting torque.

[0035] The outer joint member 11 comprises a mouth portion 16 which houses the inner joint member 12, the balls 13 and the cage 14, and a stem portion 17 which extends integrally in the axial direction from the mouth portion 16. The mouth portion 16 has arc-shaped track grooves 18 which extend in the axial direction and are formed at equal intervals at multiple locations (eight locations in FIG. 9 ) in the circumferential direction of a spherical inner circumferential surface 19.

[0036] The inner joint member 12 has arcuate track grooves 20 formed at equal intervals in a plurality of locations in the circumferential direction of a spherical outer circumferential surface 21 to pair with the track grooves 18 of the outer joint member 11 .

[0037] The balls 13 are interposed between the track grooves 18 of the outer joint member 11 and the track grooves 20 of the inner joint member 12 to transmit rotational torque. The number of balls 13 may be any number other than eight.

[0038] The cage 14 is disposed between a spherical inner peripheral surface 19 of the outer joint member 11 and a spherical outer peripheral surface 21 of the inner joint member 12 to hold the balls 13 .

[0039] In the constant velocity universal joint having the above-mentioned configuration, when an operating angle is applied between the outer joint member 11 and the inner joint member 12 by the shaft 15, the balls 13 held in the cage 14 are always maintained within the bisecting plane of the operating angle, regardless of the operating angle.

[0040] This ensures a constant velocity between the outer joint member 11 and the inner joint member 12. Between the outer joint member 11 and the inner joint member 12, rotational torque is transmitted via the balls 13 while ensuring a constant velocity.

[0041] The outer joint member 11 constituting the constant velocity universal joint is manufactured by subjecting a solid rod-shaped material (bar material) to cold plastic processing such as forging and ironing, machining such as cutting and grinding, and heat treatment.

[0042] A chuck device having the following structure is used in the cutting process in manufacturing the outer joint member 11. The specific configuration of the chuck device will be described in detail.

[0043] The main parts of the chuck device of this embodiment, as shown in FIG. 1, are composed of a chuck body 31, a cylinder 32 which serves as a drive source, a fixed pin 33, a movable pin 34, a clamping mechanism 35, and an unclamping mechanism 36.

[0044] The chuck body 31 has an axial hole 38 through which a rod 37 extending axially from the cylinder 32 is inserted. The rod 37 is arranged in the chuck body 31 so as to be axially movable. In this embodiment, the cylinder 32 is exemplified as the driving source, but other driving sources such as a motor may be used.

[0045] 2(A) and 4, the fixing pin 33 is inserted into a through hole 39 formed in the radial direction at the tip portion of the chuck body 31. The fixing pin 33 is fixedly disposed in the through hole 39 of the chuck body 31 in the radial direction.

[0046] The fixing pin 33 is integrated with the pin body 40 by brazing the steel ball 41 to the tip of the pin body 40. By forming the spherical tip of the fixing pin 33 with the steel ball 41, the strength of the spherical tip is ensured and durability is improved.

[0047] A plug member 42 that closes the through hole 38 is attached to the tip of the chuck body 31. The fixing pin 33 is fixed in the radial direction to the chuck body 31 by engaging the pin body 40 with the plug member 42 and screwing it.

[0048] The fixing pins 33 are disposed at multiple locations (four locations) at equal intervals in the circumferential direction of the chuck body 31 (see FIG. 2(A)). The spherical tip portions (steel balls 41) of the fixing pins 33 are engageable with the innermost portions (see FIG. 4) of four of the eight track grooves 18 (see FIG. 9) of the outer joint member 11.

[0049] 1, 2(B) and 3, the movable pin 34 is inserted into a through hole 43 formed in the radial direction on the front side of the fixed pin of the chuck body 31. The movable pin 34 is disposed in the through hole 43 of the chuck body 31 so as to be movable in the radial direction.

[0050] The movable pin 34 is integrated with the pin body 44 by brazing the steel ball 45 to the tip of the pin body 44. By forming the spherical tip of the movable pin 34 from the steel ball 45, the strength of the spherical tip is ensured, and durability is improved.

[0051] The movable pins 34 are disposed at equal intervals at multiple locations (four locations) in the circumferential direction of the chuck body 31 (see FIG. 2(B)). The spherical tip portions (steel balls 45) of the movable pins 34 are engageable with the opening side portions (see FIG. 3) of four of the eight track grooves 18 (see FIG. 9) of the outer joint member 11 other than the track groove 18 with which the fixed pin 33 engages.

[0052] Here, when the phase of the track groove 18 with which the fixed pin 33 engages is the same as the phase of the track groove 18 with which the movable pin 34 engages, the steel ball 41 of the fixed pin 33 and the steel ball 45 of the movable pin 34 are lined up in the axial direction in one track groove 18.

[0053] In this way, when both the fixed pin 33 and the movable pin 34 are arranged in one track groove 18, if the outer diameter of the steel balls 41, 45 corresponding to the size of the outer joint member 11 becomes large, there is a risk of interference between the steel ball 41 of the fixed pin 33 and the steel ball 45 of the movable pin 34.

[0054] Therefore, in this embodiment, the phase of the track groove 18 with which the fixed pin 33 engages is shifted from the phase of the track groove 18 with which the movable pin 34 engages (see FIGS. 2(A) and (B)). Only one of the fixed pin 33 and the movable pin 34 is disposed in one track groove 18, and the fixed pins 33 and the movable pins 34 are disposed alternately in the circumferential direction in eight track grooves 18.

[0055] In this way, by shifting the phase of the track groove 18 with which the fixed pin 33 engages from the phase of the track groove 18 with which the movable pin 34 engages, even if the outer diameter of the steel balls 41, 45 becomes large in accordance with the size of the outer joint member 11, interference between the steel ball 41 of the fixed pin 33 and the steel ball 45 of the movable pin 34 can be avoided.

[0056] As shown in Figures 1 and 3, the clamping mechanism 35 has a structure in which a tapered surface 46 formed at the tip of the rod 37 abuts against a tapered surface 47 formed at the base end of the movable pin 34 (the radially inner end of the pin body 44), thereby enabling the movable pin 34 to protrude radially outward by axial movement of the rod 37.

[0057] In this embodiment, the clamp mechanism 35 is configured with the tapered surface 46 of the rod 37 and the tapered surface 47 of the movable pin 34, but the clamp mechanism may have a structure other than the tapered surfaces 46, 47.

[0058] The unclamping mechanism 36 has a structure in which a tapered surface 48 formed on the front side of the tip of the rod 37 comes into contact with a cam 49 rotatably attached to the chuck body 31, so that the movable pin 34 can be retracted radially inward by the rotation of the cam 49 accompanying the axial movement of the rod 37. A claw portion 50 of the cam 49 is engaged by being fitted into a recess 51 formed in the pin body 44 of the movable pin 34.

[0059] In this embodiment, the unclamping mechanism 36 is configured by the tapered surface 48 of the rod 37 and the cam 49, but the unclamping mechanism may have a structure other than the tapered surface 48 and the cam 49.

[0060] The chuck device having the above configuration is used, for example, in a cutting process in the manufacture of the outer joint member 11. A method for manufacturing an outer joint member using the chuck device of this embodiment will be described in detail below.

[0061] First, the outer joint member 11 is attached to the chuck body 31. At this time, the rod 37 of the cylinder 32 is retracted. As shown in Fig. 3, the tip portion of the chuck body 31 is housed inside the mouth portion 16. At this time, the fixed pin 33 and the four track grooves 18 are phase-matched. The movable pin 34 is phase-matched with the remaining four track grooves 18.

[0062] In this state, as shown in FIG. 4, the fixing pins 33 of the chuck body 31 engage with the rear portions of the four track grooves 18 of the outer joint member 11, and the steel balls 41 of the fixing pins 33 abut against the groove bottoms at the rear portions of the track grooves 18.

[0063] With the fixed pin 33 engaged with the rear portion of the track groove 18, as shown in Fig. 3, the rod 37 is advanced axially to the right by driving the cylinder 32 (see the solid arrow in Fig. 3). The axial movement of the rod 37 causes the tapered surface 46 at the tip end of the rod 37 to abut against the tapered surface 47 at the base end of the movable pin 34.

[0064] As a result, the tapered surface 46 of the rod 37 pushes the tapered surface 47 of the movable pin 34 outward in the radial direction, causing the movable pin 34 to protrude outward in the radial direction. As shown in Fig. 5, the movable pin 34 of the chuck body 31 engages with the opening side portions of the remaining four track grooves 18 of the outer joint member 11, and the steel balls 45 of the movable pin 34 abut against the groove bottoms at the opening side portions of the track grooves 18.

[0065] In this manner, the steel balls 45 of the movable pin 34 press against the groove bottoms of the track grooves 18, completing the clamping of the outer joint member 11. The outer joint member 11 can be centered and held in a cantilevered state by the fixed pin 33 engaging with the deep side portions of the four track grooves 18 and the movable pin 34 engaging with the opening side portions of the remaining four track grooves 18.

[0066] With the outer joint member 11 clamped at one end, the outer peripheral surface of the outer joint member 11, i.e., the end face and outer peripheral surface of the stem portion 17 and the outer peripheral surface of the mouth portion 16, are cut with a cutting tool 52 (see solid arrows in Figure 5).

[0067] As described above, when clamping, the outer joint member 11 is centered and gripped in a cantilevered state by the fixed pin 33 and the movable pin 34 of the chuck body 31, thereby eliminating the need for a conventional core pushing section (see FIG. 8 of Patent Document 1) that engages with the center hole of the stem portion 17 of the outer joint member 11 to center the outer joint member 11.

[0068] As a result, it is not necessary to perform a process of previously machining the center hole, with which the core pushing portion engages, on the end face of the stem 17 of the outer joint member 11 in a separate facility. This reduces the number of processes. Also, the outer joint member 11 can be transferred within the facility with two opposing shafts. This allows the phase of the outer joint member 11 to be determined accurately between processes.

[0069] After the outer joint member 11 is cut, as shown in Fig. 6, the rod 37 is moved axially backward to the left by driving the cylinder 32 (see the solid arrow in Fig. 6). This axial movement of the rod 37 causes the tapered surface 46 at the tip end of the rod 37 to move away from the tapered surface 47 at the base end of the movable pin 34.

[0070] At this time, tapered surface 48 on the front side of the tip of rod 37 abuts against cam 49, causing tapered surface 48 of rod 37 to rotate cam 49 (see dashed arrow in FIG. 6). Because claw portion 50 of cam 49 is engaged with pin body 44 of movable pin 34, cam 49 pulls movable pin 34 radially inward, causing movable pin 34 to retract radially inward.

[0071] 7, the steel ball 45 of the movable pin 34 moves away from the groove bottom at the opening side portion of the track groove 18 of the outer joint member 11, and the movable pin 34 leaves the opening side portion of the track groove 18. This completes unclamping of the outer joint member 11.

[0072] In this manner, with the movable pin 34 sufficiently retracted radially inward, it becomes possible to remove the outer joint member 11. After being removed from the chuck body 31, the outer joint member 11 is transported to the next processing step.

[0073] The present invention is not limited to the above-described embodiments, and can of course be embodied in various other forms without departing from the spirit of the present invention. The scope of the present invention is indicated by the claims, and further includes the equivalent meanings set forth in the claims, and all modifications within the scope of the claims. [Explanation of symbols]

[0074] 11 Outer joint member 18 Track groove 19 Inner surface 31 Chuck body 33 Fixing pin 34 Movable pin 35 Clamping mechanism 36 Unclamp mechanism 37 Rod 46, 47, 48 Tapered surface 49 Cam

Claims

1. A chuck device for centering and gripping an outer joint member that constitutes a constant velocity universal joint and has a cup-shaped outer joint member having an inner circumferential surface on which track grooves extending in an axial direction are formed at a plurality of locations in a circumferential direction, when machining the outer joint member, a fixed pin provided on a tip side of a chuck body and engaging with a rear portion of the track groove, a movable pin provided on a front side of the fixed pin of the chuck body and engaging with an opening side portion of the track groove, a clamping mechanism that causes the movable pin to protrude radially outward when clamping, and an unclamping mechanism that causes the movable pin to retract radially inward when unclamping.

2. 2. The chuck device according to claim 1, wherein the clamping mechanism comprises a rod arranged in the chuck body so as to be axially movable, and the movable pin arranged in the chuck body so as to be radially movable, and the axial movement of the rod causes the movable pin to protrude radially outward by abutting a tapered surface of the rod with a tapered surface of the movable pin.

3. 2. The chuck device according to claim 1, wherein the unclamping mechanism comprises a rod arranged in the chuck body so as to be axially movable, and a cam arranged in the chuck body so as to be rotatable while being engaged with the movable pin, and the chuck device further comprises a tapered surface of the rod and a cam which is engaged with the movable pin and which causes the movable pin to retract radially inward by rotation of the cam accompanying the axial movement of the rod when the tapered surface of the rod abuts against the cam.

4. A method for manufacturing a cup-shaped outer joint member that constitutes a constant velocity universal joint and has track grooves extending in an axial direction formed at a plurality of locations in a circumferential direction on an inner circumferential surface thereof, comprising the steps of: a chuck device including: a fixed pin provided on a tip side of a chuck body and engaging with a deep portion of the track groove; a movable pin provided on a front side of the fixed pin of the chuck body and engaging with an opening side portion of the track groove; a clamping mechanism for causing the movable pin to protrude radially outward when clamping; and an unclamping mechanism for causing the movable pin to retract radially inward when unclamping, the method comprising: centering and gripping the outer joint member to machine the outer joint member using a chuck device including: a fixed pin provided on a tip side of a chuck body and engaging with a deep portion of the track groove;

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