Method for manufacturing a counter track joint

Abstract

The present invention is a method for manufacturing a counter track joint, comprising: producing a first joint portion (12) having a first ball track (22A) and a second ball track (22B) that are soft-finished and cured, i.e., not machined after curing; determining a first operating PCD value (WPCD12) from a first curved portion of the first ball track (22A) and a second curved portion of the second ball track (22B); classifying the first joint portion (12) into size classes of at least two different size classes (C12a, C12b, C12C); producing a second joint portion (13) having a first ball track (23A) and a second ball track (23B); assigning the second joint portion (13) to the first joint portion (12) in a state where the difference between WPCD12 and WPCD13 is greater than 20 micrometers and less than 80 micrometers; producing a ball cage (15) and balls (14A, 14B); and attaching the joint portions, wherein in the attached state, a first axial play (So) of the ball cage (15) with respect to the first joint portion (12) is different from a second axial play (Si) of the ball cage (15) with respect to the second joint portion (13).

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a constant velocity joint in the form of a counter track joint.

Background Art

[0002] From International Publication No. WO 2007 / 028435, a counter track joint is known that has an outer joint portion provided with a first outer ball track and a second outer ball track, and an inner joint portion provided with a first inner ball track and a second inner ball track. The first outer ball track and the first inner ball track form a first track pair that extends in a first axial direction. The second outer ball track and the second inner ball track form a second track pair that extends in a second axial direction. The balls are held in a ball cage and guided in the track pairs. An axial gap is provided on the one hand between the outer joint portion and the ball cage and on the other hand between the ball cage and the inner joint. This axial gap enables relative axial displacement between the inner joint portion and the outer joint portion. After forming with the required surplus dimensions necessary for machining, the inner spherical guide surface of the outer joint portion is soft-turned and subsequently hardened, while the ball track is hardened and ground after the forming operation.

[0003] From the specification of German Patent Application Publication No. DE 100 60 120, a counter track joint is known in which the outer joint portion and the inner joint portion are axially displaceable relative to each other. From International Publication No. WO 2006 / 048031, another counter track joint with special geometric values is known.

[0004] From Japanese Patent Laid-Open No. 11-13780, a universal joint including an outer joint member and an inner joint member is known. The inner joint member is forged from a material and heat-treated, and the shape of the ball groove remains in the forged state. The dimensions of the ball groove are measured, and the inner joint members are divided into three groups according to the dimensions. The outer joint member is forged, heat-treated, and finish-machined. The ball groove of the outer joint member is machined by grinding finish machining after heat treatment.

[0005] From Japanese Patent Laid-Open No. 2005-337290, a drive shaft for an ATV (All Terrain Vehicle: a saddle-riding type vehicle for rough terrain driving) including a double offset type joint on the inboard side and an undercut-free universal joint on the outboard side is known. The track clearance of the universal joint is in the range of 20 to 200 micrometers (μm). The PCD of the track grooves of the outer ring and the inner ring is measured and ranked according to a width of about 20 μm. From a combination of a plurality of outer rings and inner rings, the track clearance is about 20 to 60 μm for the universal joint and about 20 μm for the double offset type joint. A matching operation is performed to determine the pairing of the outer ring and the inner ring so that the distance becomes about 80 μm. The inner ring track groove and the outer ring track groove include cold forging finish.

[0006] From Japanese Patent Application Publication No. 4409706, a method and apparatus capable of detecting both the manufacturing tolerance in the radial depth of a ball track and its pitch tolerance are known. The joint part to be classified is accommodated so as to be freely movable with respect to a gauge ring in a plane perpendicular to the above axis, although it is in an axially defined position with respect to its own longitudinal axis. Measuring balls held in the openings of the gauge rings corresponding to the number of ball tracks contact the corresponding ball tracks due to the axial displacement of the measuring cone with respect to the gauge rings. Thereby, the axial position of the assumed measuring cone with respect to the gauge ring is used as a reference variable for classifying the joint part. Therefore, a specific group of inner joint parts can be assigned to a specific group of outer joint parts.

[0007] From European Patent Application Publication No. 2345823, a fixed constant velocity joint is known, which includes an outer joint member having an inner spherical surface and a plurality of track grooves, an inner joint member having an outer spherical surface and a plurality of track grooves, a plurality of balls inserted into the track grooves of the outer joint member and the inner joint member, and a cage inserted between the inner spherical surface and the outer spherical surface. At least one of the plurality of track grooves is formed by cold forging finish machining. The outer joint member, the inner joint member, the balls and the cage are assembled with each other based on a matching in which these balls and the cage respectively have ranks corresponding to the measured values of the PCD of the outer joint member.

[0008] From German Patent Application Publication No. 102010051353, a constant velocity joint is known, in which the inner peripheral surface of the outer joint part and / or the outer peripheral surface of the inner joint part is hardened, but is not machined further after hardening.

Summary of the Invention

Problems to be Solved by the Invention

[0009] The object of the present invention is to propose a method for manufacturing a constant velocity joint in the form of a counter track joint that is highly cost-effective, highly efficient during operation, and has a long service life.

Means for Solving the Problems

[0010] To achieve this object, a constant velocity joint in the form of a counter track joint according to claim 1 is proposed. Further alternative embodiments are proposed in dependent claims 2 to 15.

[0011] According to the present invention, the first ball track and the second ball track of the first joint part are soft-finished and hardened, that is, they remain unmachined after hardening. The first ball track and the second ball track of the second joint part are soft-machined, hardened, and optionally hard-machinable after hardening. Therefore, the counter track joint has an advantage in that this counter track joint can be manufactured with high cost-effectiveness due to the finish machining of the ball track of the first joint part before hardening. According to a preferred first option, the first ball track and the second ball track of the second joint part are hard-machinable. In this case, due to the hardening and subsequent hard-finishing of the ball track on which the balls run in the second joint part, a particularly good guiding function for the balls, and thus high efficiency, can be obtained. Therefore, a good balance can be obtained between cost-effective manufacturing and high efficiency during operation while having a long service life. According to a second option, the first ball track and the second ball track of the second joint part can be manufactured in the same way as the tracks of the first joint part. That is, the tracks can be soft-finished and hardened, that is, the tracks may remain unmechanically machined after hardening. In this case, due to the omission of any hard machining, the joint can be manufactured with extremely high cost-effectiveness.

[0012] A first option in which one joint part is soft-finished and another joint part is hard-finished can generally be realized in two embodiments resulting from assigning a bolt track that is finish-machined before or after curing. In the first embodiment, a bolt track soft-finished before curing can be assigned to the outer joint part, while a bolt track cured and subsequently hard-finished is assigned to the inner joint part. According to the reverse second embodiment, a bolt track soft-finished before curing can be associated with the inner joint part, while a bolt track cured and subsequently hard-finished is associated with the outer joint part.

[0013] In the context of the present disclosure, soft finishing particularly includes that the desired bolt track geometry is generated only by soft machining, i.e., the track geometry occurs and is completed before curing. After curing, no machining is performed to further change the geometry of the bolt track, and in particular, no cutting machining is performed. The bolt track can be soft-finished by forming, for example, by forging, hot forming, cold forming, pressing, and / or hammering. Alternatively or additionally, at least in an intermediate step, the bolt track can also be soft-machined, for example, by milling, turning, and / or grinding.

[0014] Furthermore, in the context of the present disclosure, the means of hard machining by hardening particularly means prefabricating each ball track with an appropriate oversize before hardening and performing finish machining to the desired final geometry after hardening. This prefabrication can be carried out by a machining process, such as turning or milling, and / or by a non-cutting manufacturing process, such as molding, forging or pressing. The finish machining can be particularly carried out by chip forming, such as by grinding and / or turning. In the finish machining, the oversize material of each surface provided on the intermediate product is removed after hardening, but can be, for example, a fraction of a millimeter of 1 millimeter.

[0015] For example, a ball track that is hard machined by grinding and / or cutting may have a smaller surface roughness than a ball track that is soft finished without being machined after hardening. The latter may optionally have a microstructure formed by shot peening before or after hardening.

[0016] According to the proposed method, the working pitch circle diameter (WPCD) of the first joint part is determined. The first WPCD can be determined as a function of the curved part of the first bolt track and the curved part of the second bolt track of the first joint part. For example, the first WPCD can be determined based on the smallest circle around one or more track curved parts (A) of the first bolt track and one or more track curved parts (B) of the second bolt track of the first joint part. Measuring and using the first WPCD is advantageous in that only one value needs to be determined for the purpose of grading the first joint part. The first WPCD is within the first overall PCD tolerance range (ΔWPCD), which may be, for example, 30 to 300 micrometers. The first overall PCD tolerance range (ΔWPCD) can be divided into at least two different size classes (C12a, C12b, C12c), and the first joint part can be classified into one of the above different size classes depending on the determined first WPCD.

[0017] It is proposed to hard machine the first bolt track and the second bolt track such that the working pitch circle diameter (WPCD) of the second joint part is greater than 40 micrometers and within the second overall PCD tolerance range (ΔWPCD), for example, 40 to 300 micrometers. The second WPCD is determined as a function of the curved part of the first bolt track and the curved part of the second bolt track of the second joint part. For example, the second WPCD can be determined to be the smallest intersection of one or more track curved parts (A’) of the first bolt track and one or more track curved parts (B’) of the second bolt track of the second joint part.

[0018] According to the proposed method, the second joint part is assigned to the first joint part depending on the size class (C12a, C12b, C12c) to which the first joint part is classified. In particular, the first joint part and the second joint part are selected, i.e., matched, such that the difference between the PCD of the first joint part and the PCD of the second joint part is greater than 20 micrometers and less than 80 micrometers.

[0019] The advantage of the proposed method is that the selection and mutual matching of the first joint part and the second joint part can be performed based only on the required WPCD of the first joint part and the WPCD of the second joint part. There is no need to measure, classify or match another aspect or another value, for example, the inner surface of the outer joint part, the outer surface of the inner joint part, or any offset value such as that of the outer joint part or the inner joint part. Therefore, the manufacture of the counter track joint is easy and cost-effective.

[0020] The balls can be manufactured with a manufacturing tolerance of less than 4 micrometers, i.e., ±2 micrometers, relative to the nominal ball diameter. Therefore, the balls are manufactured with a relatively small manufacturing tolerance, i.e., high manufacturing precision. In this way, any one of the balls manufactured with this manufacturing tolerance can be used to complete the counter track joint with the first joint part and the second joint part paired with each other. There is no need to match or grade the balls for any particular first joint part or second joint part, which makes the manufacture of the joint easy and cost-effective.

[0021] Each one of at least two first size classes (C12a, C12b, C12c) defined for classifying the first joint part can cover a range (R12a, R12b, R12c) of first WPCD values that is at least 10 micrometers and at most 45 micrometers.

[0022] The second joint portion can be selected such that the second WPCD deviates from the edge value of the range of the first WPCD values of each first size class of the first joint portion by 5 to 50 micrometers. When the first joint portion is an outer joint portion, the nominal PCD for the second joint portion, i.e., the inner joint portion, is smaller than the minimum value of the range of the respective first PCD values. Conversely, when the first joint portion is an inner joint portion, the nominal PCD for the second joint portion, i.e., the outer joint portion, is larger than the maximum value of the range of the respective second WPCD values.

[0023] The first WPCD of the first joint portion may be obtained from the intersection of the first curved portion of the first bolt track of the first joint portion and the second curved portion of the second bolt track. The second WPCD of the second joint portion may be obtained from the intersection of the first curved portion of the first bolt track of the second joint portion and the second curved portion of the second bolt track.

[0024] The first WPCD of the first joint portion can be determined in a system plane (ES) in which the PCD of one or more first bolt tracks of the first joint portion is equal to the PCD of one or more second bolt tracks. In particular, the first WPCD can be determined as the smallest circle or roundness around the combined first track curvature (A) and second track curvature (B). The system plane (ES) is arranged axially between the offset plane (EA) of the first bolt track of the first joint portion and the offset plane (EB) of the second bolt track, and in particular is not centered between them. The opening-side offset plane (EA) can be defined by the maximum curved portion of the first bolt track having the maximum radial distance from the first longitudinal axis (L12). The attachment-side offset plane (EB) can be defined by the maximum curved portion of the second bolt track having the maximum radial distance from the longitudinal axis (L12).

[0025] According to one embodiment, when the first WPCD value is within a predetermined first WPCD range (R12a), it belongs to the first size class (C12a); or when the first WPCD value is within a predetermined second WPCD range (R12b), it belongs to the second size class (C12b); or when the first WPCD value is within a predetermined third WPCD range (R12c), the first joint part can be respectively assigned to the third size class (C12c).

[0026] The first joint part, the second joint part, and the ball cage can be manufactured such that, in the assembled and aligned state of the counter track joint, the first axial play (So) between the ball cage and the first joint part is more than 25 micrometers different from the second axial play (Si) between the ball cage and the second joint part. On the one hand, the outer cage surface and the inner surface of the outer joint part, and on the other hand, the inner cage surface and the outer surface of the inner joint part, in the assembled and aligned state of the counter track joint, the outer radial clearance between the ball cage and the outer joint part and the inner radial clearance between the ball cage and the inner joint part can be made to have different sizes, and / or the outer axial clearance (So) between the ball cage and the outer joint part and the inner axial clearance (Si) between the ball cage and the inner joint part can be made to have different sizes. For example, one of the first axial play (So) and the second axial play (Si) can be more than 50 micrometers, and the other of the first axial play (So) and the second axial play (Si) can be more than 75 micrometers. When the outer joint part, or the outer ball track, is soft-finished before hardening, the outer radial clearance is preferably larger than the inner radial clearance. Conversely, when the inner joint part, or the inner ball track, is soft-finished before hardening, the outer radial clearance is preferably smaller than the inner radial clearance.

[0027] According to one embodiment, the first joint part can be fabricated in the form of an outer joint part, and the second joint part can be fabricated in the form of an inner joint part. In this case, the first bolt track, the second bolt track, and the circumferential surface of the outer joint part can be soft-finished, particularly by a molding process and / or forging. Next, the first outer bolt track and the second outer bolt track of the outer joint part can be hardened. The first bolt track, the second bolt track, and the circumferential surface of the inner joint part can be pre-soft machined, then hardened, and then hard-finish machined, particularly by a chip forming process such as turning, milling, and / or grinding.

[0028] According to one embodiment, the first outer bolt track can be formed to have a first outer undercut on the opening side, the second outer bolt track can be formed to have a second outer undercut on the opening side, and the first outer undercut is smaller than the second outer undercut.

[0029] At least one of the outer cage surface and the inner cage surface can be soft-finished, particularly by a molding process, and then hardened.

[0030] The outer joint part and the inner joint part are fabricated such that during the operation of the counter track joint, the inner joint part makes an angular movement with respect to the outer joint part at a joint angle (β) that is particularly greater than 20° and up to 30°. This joint angle (β) can also be referred to as the operating joint angle or the working joint angle. This angle can be defined as the joint angle at which all the balls are still held in the track pair when moving towards the opening side in each track pair. The ratio of the operating PCD (WPCD) of the outer joint part to the maximum diameter (d) of the insertion opening of the inner joint part can be, for example, less than 2.05 (WPCD / d < 2.05).

[0031] To attach the ball, the inner joint part can be rotated relative to the outer joint part, whereby the first inner ball track faces the first outer ball track and forms a first track pair that expands toward the opening side of the outer joint part, and the second inner ball track faces the second outer ball track and forms a second track pair that expands toward the connecting part side of the outer joint part. Next, with the inner joint part and the outer joint part deflected relative to each other, the first track pair and the second track pair each accommodate one of the torque transmission balls, and the ball can be inserted into the cage window. The ball is held by the ball cage in the joint center plane (EM) with the longitudinal axes of the inner joint part and the outer joint part coaxially aligned. A part of the plurality of webs of the inner joint part can be made with flattened portions on both sides, whereby the ball cage can be passed through the cage window for assembly. Additionally, or as an alternative embodiment, on the connecting part side having pockets that are recessed radially with respect to the functional track part and in which the balls associated with the case when the constant velocity joint is articulated can move radially, at least a part of the plurality of second outer ball tracks of the outer joint part can be made.

[0032] The first outer ball track and the second outer ball track are preferably designed to form two-point contact with the associated ball in any case when viewed in cross-section. Alternatively or additionally, the first inner ball track and the second inner ball track may be designed to form two-point contact with the associated torque transmission ball in any case when viewed in cross-section. The two-point contact can be caused, for example, by a track shape that is Gothic or elliptical when the track is viewed in a cross-sectional view. The two-point contact or two-point path is advantageous for measuring the ball track in a self-centering manner. However, a track with a circular cross-section can also be used.

[0033] Hereinafter, preferred embodiments will be described with reference to the drawings.

Brief Description of the Drawings

[0034]

Figure 1A

Figure 1B

Figure 1C

Figure 1D

Figure 1E

Figure 2A

Figure 2B

Figure 2C

Figure 2D

Figure 3A

Figure 3B

Figure 3C

Figure 4

Figure 5A

Figure 5B

Figure 5C

Figure 5D

Figure 6A

Figure 6B

Figure 6C

Figure 6D

Figure 7A

Figure 7B

Figure 7C

Figure 8A

Figure 8B

Best Mode for Carrying Out the Invention

[0035] Referring to FIGS. 1A to 8B, a method according to the present invention for manufacturing a counter track joint 11 will be described. The method for manufacturing a counter track joint includes fabricating a first joint part 12, fabricating a second joint part 13, fabricating a ball cage 15, fabricating balls 14A, 14B, inserting the inner joint part into the ball cage 15, inserting the ball cage 15 into the outer joint part, accommodating one of the balls 14A, 14B respectively by a first track pair and a second track pair, and inserting the balls 14A, 14B into the cage window 18.

[0036] Figs. 1A to 1E, also collectively referred to as Fig. 1, show a first joint portion 12 for a constant velocity joint fabricated in accordance with the present invention. The first joint portion 12 is fabricated with first ball tracks 22A and second ball tracks 22B that are circumferentially distributed on the circumferential surface 24 of the first joint portion 12. The first joint portion 12 has a first longitudinal axis L12. Each of the first ball tracks 22A has a first curved portion in a longitudinal cross section that includes a central curved portion extending toward the opening side 20' of the first joint portion 12, and a first maximum curved portion having a maximum radial distance from the first longitudinal axis L12. Each of the second ball tracks 22B has a second curved portion in a longitudinal cross section that includes a central curved portion extending toward the attachment side 19' of the first joint portion 12, and a second maximum curved portion having a maximum radial distance from the longitudinal axis L12. The first ball tracks 22A and the second ball tracks 22B of the first joint portion 12 are soft finished and hardened, i.e., they remain unmachined after hardening.

[0037] After hardening, the first operating PCD is required based on the first curved portion A of the first bolt track 22A and the second curved portion B of the second bolt track 22B of the first joint portion 12. The value obtained for the first operating PCD, referred to as WPCD12, is within the first overall operating PCD tolerance range referred to as ΔWPCD12. The operating PCD of the first joint portion 12 can be determined so as to represent the first bolt track 22A and the second bolt track 22B. For example, the first WPCD can be determined to be the minimum intersection point between the first PCD of the first bolt track 22A of the first joint portion 12, or the first curved portion A, and the second PCD of the second bolt track 22B, or the second curved portion B. In particular, the first WPCD12 of the first joint portion 12 can be determined within the system plane ES in which the sizes of the WPCD (WPCDA) of the first bolt track 22A and the WPCD (WPCDB) of the second bolt track 23B are equal. The system plane ES can be arranged at any position in the axial direction between the offset plane EA of the first bolt track 22A and the offset plane EB of the second bolt track 22B. The opening side offset plane EA can be defined as a plane including the maximum curved portion of the first bolt track 22A having the maximum radial distance from the axis L12. The attachment side offset plane EB can be defined as a plane including the maximum curved portion of the second bolt track 22B having the maximum radial distance from the axis L12.

[0038] The second joint portion 13 is fabricated with a first bolt track 23A and a second bolt track 23B that are circumferentially distributed on the circumferential surface 26 of the second joint portion 13. The second joint portion 13 defines a second longitudinal axis L13. Each of the first bolt tracks 23A of the second joint portion 13 has a first curved portion A' in the longitudinal cross-section, including a central curved portion that expands toward the opening side 20' of the second joint portion and a first maximum curved portion having a maximum radial distance from the second longitudinal axis L13. Each of the second bolt tracks 23B of the second joint portion 13 has a second curved portion B' in the longitudinal cross-section, including a central curved portion that expands toward the opposite side 19' of the second joint portion 13 and a second maximum curved portion having a maximum radial distance from the second longitudinal axis L13. The first bolt track 23A and the second bolt track 23B of the second joint portion 13 are soft-machined, hardened, and preferably hard-machined after hardening.

[0039] The hard machining of the first bolt track 22A and the second bolt track 22B of the second joint portion 13 can be performed such that the second operating PCD value WPCD13 is within the second overall operating PCD tolerance range ΔWPCD13. The operating PCD of the second joint portion 13 can be determined to represent the first bolt track 23A and the second bolt track 23B, particularly based on the first track line A' of the first bolt track 23A and the second track line B' of the second bolt track 23B. For example, the second WPCD can be determined as the minimum circumscribing circle or rounding around one or more WPCDs of the first bolt track 23A of the second joint portion 13, or track line A', and one or more WPCDs of the second bolt track 23B of the second joint portion 13, or track line B'.

[0040] Figures 5A and 5B show the outer joint portion 12 and the inner joint portion 13 with the required operating PCD drawn thereon. The inner joint portion 13 having the WPCD13 obtained based on the operating PCD of the first track line A' and the second track line B' may be graded and also matched by the respective outer joint portions 12 having the WPCD12 obtained based on the operating PCD of the first track line A and the second track line B.

[0041] On the left side of FIG. 5C, exemplary values and dimensions for a batch of the outer joint portions 12 fabricated as described above are shown. The first tolerance range ΔWPCD12 of the outer joint portion can be read. The first tolerance range ΔWPCD12 is the difference between the maximum operating PCD and the minimum operating PCD of the outer joint portion 12, that is, (1) ΔWPCD12 = WPCD12max - WPCD12min is defined as.

[0042] The first WPCD value obtained from the first bolt track 22A of the outer joint portion 12 is within the first allowable tolerance range ΔWPCD12. The first allowable tolerance range ΔWPCD12 may be, for example, 30 to 300 micrometers, particularly 60 to 150 micrometers. In this embodiment, the first allowable tolerance range ΔWPCD12 has two different size classes C12a, C12b, and it goes without saying that more size classes, for example 3, 4, 5 or more, can also be selected. Depending on the obtained first WPCD, the first joint portion 12 is classified into one of the different size classes C12a, C12b described above. For example, when the first WPCD value is within a predetermined first PCD range R12a, it belongs to the first size class C12a, or when the first WPCD value is within a predetermined second PCD range R12b, the first joint portion 12 can be assigned to the second size class C12b respectively. The second size class C12b is adjacent to the first size class C12a and has a WPCD value larger than that of the first size class C12a. The extension of the ranges R12a, R12b depends on the number of size classes C12a, C12b. In this embodiment having two size classes C12a, C12b, the first PCD range R12a and the second PCD range R12b may be, for example, 15 to 150 micrometers, particularly 30 to 75 micrometers.

[0043] On the right side of FIG. 5C, exemplary values and dimensions for a batch of the inner joint portion 13 fabricated as described above are shown. The allowable tolerance range ΔWPCD13 of the inner joint portion 13 can be observed. The allowable tolerance range ΔWPCD13 is the difference between the maximum operating PCD and the minimum operating PCD of the inner joint portion 13, that is, (2) ΔWPCD13 = WPCD13max - WPCD13min is defined as.

[0044] Furthermore, the minimum overall allowable tolerance range ΔWPCDmin is the difference between the minimum operating PCD of the outer joint portion 12 and the maximum operating PCD of the inner joint portion 13, that is, (3) ΔWPCDmin = WPCD12min - WPCD13max is defined as follows.

[0045] As can be seen in FIG. 5C, the operating PCD (WPCD12) of another joint portion 12 and the operating PCD (WPCD13) of the inner joint portion 13 overlap each other by ΔWPCDmin. The scales for WPCD12 and WPCD13 shown in FIGS. 5A and 5B may be, for example, steps of 5 micrometers. The joint PCD value of the counter track joint attached to the side shaft of an automotive vehicle may be, for example, 55 to 65 mm, but is not limited thereto.

[0046] The maximum overall tolerance range ΔWPCDmax is the difference between the maximum operating PCD of the outer joint portion 12 and the minimum operating PCD of the inner joint portion 13, that is, (4) ΔWPCDmax = WPCD12max - WPCD13min is defined as follows.

[0047] The WPCD value obtained from the outer joint portion 13 (WPCD13) is within the first tolerance range ΔWPCD13. The first tolerance range ΔWPCD13 may be, for example, 40 to 300 micrometers, particularly 60 to 150 micrometers. In this embodiment, the first tolerance range ΔWPCD13 also has two different size classes C13a and C13b. However, it goes without saying that a larger number of size classes, for example, 3, 4, 5, 6, 7 or more can be selected, and the number of size classes C13 for the outer joint portion 13 may be larger than the number of size classes C12 for the inner joint portion 12. However, in a specific embodiment where the second joint portion 13 is hard machined after hardening, due to high manufacturing accuracy, classification into size classes may not be necessary. In this case, the second joint portion can be manufactured such that the second WPCD value is within the tolerance required to immediately match the first WPCD value of the first joint portion.

[0048] To match the required WPCD of the first joint part 12, the second joint part 13 can be manufactured accordingly and / or classified into one of the above-described different size classes C13a, C13b. For example, when the first WPCD value is within a predetermined first PCD range R13a, it can be assigned to the first size class C13a, or when the first WPCD value is within a predetermined second PCD range R13b, it can be assigned to the second size class C13b. The sizes of the ranges R13a, R13b depend on the number of the size classes C13a, C13b. In this embodiment having two size classes C13a, C13b, the first PCD range R13a and the second PCD range R13b may be, for example, 20 to 150 micrometers, particularly 30 to 75 micrometers.

[0049] The second joint part 13 is assigned to the first joint part 12 such that the difference between the WPCD12 of the first joint part 12 and the second operating PCD value WPCD13 of the second joint part 13 is greater than 20 micrometers and less than 80 micrometers, depending on the size classes C12a, C12b of the first joint part 12. Each one of the first size classes C12a, C12b provided for classifying the first joint part 12 preferably covers a range R12a, R12b of first PCD values that is at least 10 micrometers and at most 45 micrometers. The second joint part 13 can be selected such that the measured PCD13 deviates by 5 to 50 micrometers from the edge values of the range R12a, R12b of the first PCD values of the corresponding first size classes C12a, C12b of the first joint part 12.

[0050] The ranges R12a and R12b of the PCD values of the first joint portion 12 and the ranges R13a and R13b of the respective PCD values of the second joint portion 13 are selected such that there is always a gap between the maximum values of the ranges R13a and R13b of the values of the inner joint portion 13 and the minimum values of the respective ranges R12a and R12b of the values of the outer joint portion 12. Accordingly, the WPCD of the inner joint portion is smaller than the WPCD of the outer joint portion, whereby a pitch path separation PPS is obtained. In the mounted state of the constant velocity joint 2, the pitch path separation PPS represents half of the difference between the WPCD12 of the first joint portion 12 and the WPCD13 of the second joint portion, that is, PPS = (WPCD12 - WPCD13) / 2.

[0051] FIG. 5D shows a pitch path separation range PPSa that is obtained as a result of pairing the inner joint portion 13 with the WPCD within the range R13a and the outer joint portion 12 with the WPCD within the range R12a. Correspondingly, the pitch path separation range PPSb is obtained as a result of pairing the inner joint portion 13 of the range R13b and the outer joint portion 12 of the range R12b. The overall pitch path separation range PPS may be given as the difference between the maximum PPS value PPSmax and the minimum PPS value PPSmin. The PPS may be, for example, 5 to 45 micrometers, but is not limited thereto.

[0052] The ball cage 15 shown in detail in FIGS. 3A to 3C is provided with a cage axis L15, an inner cage surface 17, an outer cage surface 16, and cage windows 18 distributed circumferentially around the cage axis L15. The outer cage surface 16 and the inner cage surface 17 are made to have play in the axial direction and the radial direction with respect to the respective circumferential surfaces 24, 26 of the first joint portion 12 and the second joint portion 13. In the embodiment shown here, the first joint portion 12 is an outer joint portion, and the second joint portion 13 is an inner joint portion. In the present embodiment, the surface centers M16 and M17 are in the common joint center plane EM, and in a modified embodiment, the surface centers M16 and M17 may also have axial offsets in opposite directions with respect to the joint center plane EM, respectively.

[0053] Exemplary balls 14A, 14B are shown in FIG. 4. The balls are preferably manufactured with a manufacturing tolerance of less than 4 micrometers with respect to the nominal ball diameter. With such high manufacturing precision, any balls 14A, 14B can be used for any pair of the first ball tracks 22A, 23A and the second ball tracks 22B, 23B.

[0054] The counter track joint 2 manufactured by the method according to the present invention is shown in FIGS. 6A to 6D in the installed state.

[0055] In the mounted state, a circumferential gap 25 is formed between the outer surface 16 of the ball cage 15 and the inner surface 24 of the outer joint portion 12. Also, a circumferential gap 27 is formed between the inner surface 17 of the ball cage 15 and the outer surface 26 of the inner joint portion 13. The first joint portion 12, the second joint portion 13, and the cage 15 are manufactured such that the size of the first axial play So between the ball cage 15 and the first joint portion 12 and the size of the second axial play Si between the ball cage 15 and the second joint portion 13 are different in the mounted and aligned state of the counter track joint. The first axial play So is the sum of the axial play Soa on the opening side and the axial play Sob on the base side between the outer surface 16 of the cage and the inner surface 24 of the outer joint portion. The second axial play Si is the sum of the axial play Sia on the opening side and the axial play Sib on the base side between the inner surface 17 of the cage and the outer surface 27 of the inner joint portion 13.

[0056] The balls 14A, 14B are held in the cage windows 18 distributed in the circumferential direction of the ball cage 15 in the joint center plane EM. A longitudinal axis L12 is marked on the outer portion 12 of the joint, and a longitudinal axis L13 is marked on the inner portion 13 of the joint. The intersection points of the longitudinal axes L12, L13 and the joint center plane EM form the joint center point M.

[0057] In the present embodiment, the inner surface 24 of the outer joint portion 12, the outer cage surface 16, the inner cage surface 17, and the outer surface 27 of the inner joint portion 13 are spherical. Alternatively or additionally, one or more of the above surfaces may have a cylindrical, toroidal and / or conical section. For the inner surface 24 of the outer portion 12, the opening side section 24a, the central section 24c, and the base side section 24b are shown in FIG. 1C. The base side section 24b forms a support surface, and the ball cage 15 may be axially supported by its outer surface 16 against this support surface.

[0058] The outer joint portion 12 may have, for example, a base 19 that may have a connecting journal and an opening 20. The inner joint portion 13 has an opening 34, and a journal of the drive shaft 30 can be inserted into this opening 34 in a rotationally fixed manner to transmit torque. The counter track joint 11 to which the shaft 30 is attached is shown in FIGS. 7A to 7C. In the present disclosure, the position of the base 19 indicates the axial direction "towards the attachment side", and the position of the opening 20 indicates the axial direction "towards the opening side". These terms are also used as 19' and 20' with respect to the inner part of the joint if the actual connection of the shaft to the inner part of the joint 13 is ignored.

[0059] The first track pair 22A, 23A having the first ball 14A for transmitting torque and the second track pair 22B, 23B having the second ball 14B for transmitting torque are alternately arranged in the circumferential direction. The shape of the first track pair 22A, 23A is shown in FIG. 7B, and the shape of the second track pair 22B, 23B is shown in FIG. 7C. The first ball 14A is in contact with the first outer ball track 22A in the outer joint portion and the first inner ball track 23A in the inner joint portion, respectively. Here, when moving along the outer first ball track 22A and the inner first ball track 23A, the center of the first ball 14A defines the first center lines A, A', respectively, whereas when moving along the outer second ball track 22B and the inner second ball track 23B, the center of the second ball 14B defines the second center lines B, B', respectively.

[0060] When the outer joint portion 12 and the inner joint portion 13 are coaxially aligned, the tangents T22A and T23A to the ball 14A at the contact points with the first tracks 22A and 23A form an opening angle δΑ that opens toward the opening side. The second ball 14B is guided by the outer ball track 22B in the outer joint portion 12 and the inner ball track 23B in the inner joint portion 13. The balls 14A and 14B are shown in contact with the track bases of the optional ball tracks. The balls may be in two-point contact in the cross-sectional view, and in this case, may have a radial gap with respect to each track base. In the illustrated aligned state, the tangents T22B and T23B to the second ball 14B at the contact points with the second tracks 22B and 23B form a second opening angle δΒ that opens toward the connecting portion side. In one of the modified track configurations of the counter track joint, the opening angles directed in the opposite axial direction may result in a slightly angled position of the joint, especially up to 2°.

[0061] The first track pair and the second track pair are each located in a radial plane whose center line passes through the joint, but are not limited thereto. Each of the balls 14A and 14B is received in a cage window 18 in the ball cage 15. The radial planes each have the same angular distance from each other. The number of torque transmitting balls 14A and 14B, and correspondingly the number of outer ball tracks and inner ball tracks, is eight in this case, but is not limited thereto. In any case, the two first track pairs 22A and 23A of the outer joint portion 12 and the inner joint portion 13 are diametrically opposed to each other, and the two second track pairs 22B and 23B are diametrically opposed to each other.

[0062] In the present disclosure, the following provisions apply to the counter track joint.

[0063] The joint articulation angle β defines the angle sandwiched between the longitudinal axis L12 of the outer joint portion 12 and the longitudinal axis L13 of the inner joint portion 13. The joint articulation angle β is zero when the joints are aligned.

[0064] The opening angle δ defines the angle enclosed by the tangent T to the balls at the points of contact with the first ball track and the second ball track, respectively, when the joint is in the aligned state.

[0065] The central plane EM is defined by the centers of the torque transmission balls 14A, 14B when the joint is aligned.

[0066] The first pitch circle diameter PCDA defines the diameter formed by the center of the first ball 14A when the joint is aligned.

[0067] The second pitch circle diameter PCDB defines the diameter formed by the center of the second ball 14B when the joint is aligned.

[0068] Figures 8A and 8B show another embodiment for classifying and matching the WPCD values of the first joint portion 12 and the second joint portion 13. This embodiment broadly corresponds to the embodiment shown in Figures 5A and 5B, and here, this embodiment is referred to with the same details and / or corresponding details having the same reference numerals as Figures 5A and 5B for corresponding features. The first joint portion 12 and the second joint portion 13 can be manufactured such that one of the first joint portion (12) and the second joint portion (13) is soft-finished and the other of the first joint portion (12) and the second joint portion (13) is hard-finished, as described above.

[0069] In this embodiment, the first allowable tolerance range ΔWPCD12 has three different size classes C12a, C12b, and C12c. Depending on the obtained first WPCD, the first joint portion 12 is classified into one of the above-described different size classes C12a, C12b, and C12c. For example, when the first WPCD value is within a predetermined first PCD range R12a, it belongs to the first size class C12a; when the first WPCD value is within a predetermined second PCD range R12b, it belongs to the second size class C12b; and when the first WPCD value is within a predetermined third PCD range R12c, it belongs to the third size class C12c. Thus, the first joint portion 12 can be respectively assigned. The sizes of the ranges R12a, R12b, and R12c depend on the number of the size classes C12a, C12b, and C12c. In this example having three size classes C12a, C12b, and C12c, the first PCD range R12a, the second PCD range R12b, and the third PCD range R12c may be, for example, 10 to 100 micrometers, particularly 20 to 50 micrometers.

[0070] On the right side of FIG. 8A, exemplary values and dimensions for a batch of the inner joint portion 13 fabricated as described above are shown. The first WPCD value obtained from the inner joint portion 13 is within the allowable tolerance range ΔWPCD13. The first allowable tolerance range ΔWPCD13 may be, for example, 40 to 300 micrometers, particularly 60 to 150 micrometers. In this example, the allowable tolerance range ΔWPCD13 also has three different size classes C13a, C13b, and C13c, but is not limited thereto.

[0071] To match the required WPCD of the first joint part 12, the second joint part 13 can be manufactured accordingly and / or classified into one of the size classes C13a, C13b, C13c. For example, if the first WPCD value is within a predefined first PCD range R13a, it belongs to the first size class C13a; or if the first WPCD value is within a predefined second PCD range R13b, it belongs to the second size class C13b; or if the first WPCD value is within a predefined third PCD range R13c, it belongs to the third size class C13c. The second joint part 13 can be assigned to each of them respectively. The sizes of the ranges R13a, R13b, R13c depend on the number of the size classes C13a, C13b, C13c. In this embodiment having three size classes C13a, C13b, C13c, the first PCD range R13a, the second PCD range R13b, and the third PCD range R13c may be, for example, 10 to 100 micrometers, particularly 20 to 50 micrometers, but are not limited thereto.

[0072] In the state where the constant velocity joint is attached, the pitch path separation PPS represents the radial play of the balls in each track pair. FIG. 8B shows the pitch path separation range PPSa resulting from pairing the inner joint part 13 of the value range R13a with the outer joint part 12 of the value range R12a. Correspondingly, the pitch path separation range PPSb is obtained by pairing the inner joint part 13 of the value range R13b with the outer joint part 12 of the value range R12b, and the pitch path separation range PPSc is obtained by pairing the inner joint part 13 of the value range R13c with the outer joint part 12 of the value range R12c. The PPS may be, for example, 5 to 45 micrometers, but is not limited thereto.

Explanation of Signs

[0073] 11 Counter track joint 12 First / outer joint part 13 Second / inner joint part Balls 14A, 14B Cage 15 Outer surface (15) 16 Inner surface (15) 17 Window 18 Attachment side / base 19 Opening side / aperture 20 First and second outer ball tracks 22A, 22B First and second inner ball tracks 23A, 23B Inner surface (12) 24 Outer gap 25 Outer surface (13) 26 Inner gap 27 Radial expansion part 28 Pocket 29 Shaft 30 Web 31 Flattened part 32 Web 33 Aperture 34 Track lines A, A’ Track lines B, B’ Size class C Longitudinal axis L Joint center part M Tangent T First offset plane EA Second offset plane EB Joint center plane EM System plane ES Overall inner axial play Si Overall outer axial play So Pitch circle diameter PCD Pitch path separation PPS Size range R Operating pitch circle diameter WPCD Joint angle β Opening angle δ Allowable tolerance range ΔWPCD

Claims

1. A method of manufacturing a counter track joint, comprising: manufacturing the first joint part (12) having a first longitudinal axis (L12), the first joint part (12) being provided with a first ball track (22A) and a second ball track (22B) distributed circumferentially on the circumferential surface (24) of the first joint part (12), each of the first ball tracks (22A) having a first curved portion in a longitudinal cross-section with a central curved portion extending toward the opening side (20) of the first joint part (12), and each of the second ball tracks (22B) having a second curved portion in a longitudinal cross-section with a central curved portion extending toward the attachment side (19) of the first joint part (12), the first ball track (22A) and the second ball track (22B) of the first joint part (12) being soft-finished and hardened, i.e., remaining unmachined after hardening; determining a first operating PCD value (WPCD12) of the first joint part (12); classifying the first joint part (12) into size classes of at least two different size classes (C12a, C12b, C12c) depending on the first operating PCD value (WPCD12); manufacturing a second joint part (13) having a second longitudinal axis (L13), the second joint part (13) being provided with a first ball track (23A) and a second ball track (23B) distributed circumferentially on the circumferential surface (26) of the second joint part (13), each of the first ball tracks (23A) of the second joint part (13) having a first curved portion in a longitudinal cross-section with a central curved portion extending toward the opening side (20') of the second joint part, and each of the second ball tracks (23B) of the second joint part (13) having a second curved portion in a longitudinal cross-section with a central curved portion extending toward the opposite side (19') of the second joint part (13), the first ball track (23A) and the second ball track (23B) of the second joint part (13) being soft-machined and hardened; determining a second operating PCD value (WPCD13) of the second joint part (13); Assign the second joint part (13) that conforms to one of the size classes (C12a, C12b, C12c) of the first joint part (12) depending on the second operating PCD value (WCPD13) such that the difference between the first operating PCD value (WPCD12) of the first joint part (12) and the second operating PCD value (WPCD13) of the second joint part (13) is greater than 20 micrometers and less than 80 micrometers. Produce a ball cage (15) having a cage axis (L15), an inner cage surface (17), an outer cage surface (16), and cage windows (18) distributed circumferentially around the cage axis (L15), wherein the inner cage surface (17) and the outer cage surface (16) are produced such that one of the first joint part (12) and the second joint part (13) is an outer joint part and the other of the first joint part (12) and the second joint part (13) is an inner joint part, and have axial and radial play with respect to the respective circumferential surfaces (24, 26) of the first joint part (12) and the second joint part (13). Produce balls (14A, 14B). Insert the inner joint part (13) into the ball cage (15). Insert the ball cage (15) into the outer joint part. Accommodate one of the balls (14A, 14B) by the first track pair and the second track pair respectively, insert the balls (14A, 14B) into the cage windows (18), and in the assembled and aligned state of the counter track joint, the magnitude of the first axial play (So = Soa + Sob) between the ball cage (15) and the first joint part (12) is different from the magnitude of the second axial play (Si = Sia + Sib) between the ball cage (15) and the second joint part (13). Method. Claim 2 After hardening, perform hard machining on the first bolt track (23A) and the second bolt track (23B) of the second joint portion (13). After the hard machining, considering the first curved portion of the first bolt track (22A) and the second curved portion of the second bolt track (22B) of the first joint portion (12), obtain the first operating PCD value (WPCD12), and the method according to claim 1, characterized in that the first operating PCD value (WPCD12) is within the first overall operating PCD tolerance range (ΔWPCD12).

3. Finish forging the first bolt track (22A) and the second bolt track (22B) of the first joint portion (12) before hardening, After hardening, mechanically finish machine the first bolt track (23A) and the second bolt track (23B) of the second joint portion (13), the method according to claim 2, characterized in that.

4. Manufacturing the balls (14A, 14B) with a manufacturing tolerance of less than 4 micrometers with respect to the nominal ball diameter, the method according to any one of claims 1 to 3.

5. Each one of at least two of the first size classes (C12a, C12b, C12c) defined for classifying the first joint portion (12) covers a range (R12a, R12b, R12c) of PCD values that is at least 10 micrometers and at most 45 micrometers, the method according to any one of claims 1 to 4.

6. The method according to claim 5, characterized in that the second joint portion (13) is selected such that the second operating PCD value (WPCD13) deviates by 5 to 50 micrometers from an edge value that conforms to one of the ranges (R12a, R12b, R12c) of the first PCD value of the first joint portion (12).

7. The first operating PCD (WPCD12) of the first joint portion (12) is obtained as a function of the first curved portion of the first bolt track (22A) and the second curved portion of the second bolt track (22B) of the first joint portion (12), The method according to any one of claims 1 to 6, characterized in that the second operating PCD (WPCD13) of the second joint part (13) is determined as a function of the first curved part of the first bolt track (23A) of the second joint part (13) and the second curved part of the second bolt track (22B).

8. The method according to any one of claims 1 to 7, characterized in that the first operating PCD (WPCD12) of the first joint part (12) is determined in the system plane (ES), and the operating PCD of the track line (A) of the first bolt track (23A) and the operating PCD of the track line (B) of the second bolt track (23B) are of the same size.

9. The method according to any one of claims 1 to 8, characterized in that the first joint part (12) is assigned to the first size class (C12a) when the first operating PCD value (WPCD12) is within a predetermined first PCD range (R12a), or to the second size class (C12b) when the first operating PCD value is within a predetermined second PCD range (R12b), or to the third size class (C12c) when the first operating PCD value is within a predetermined third PCD range (R12c).

10. The method according to any one of claims 1 to 9, characterized in that the first joint part (12), the second joint part (13) and the ball cage (15) are manufactured such that, in the assembled and aligned state of the counter track joint, the first axial play (So) between the ball cage (15) and the first joint part (12) differs by more than 25 micrometers from the second axial play (Si) between the ball cage (15) and the second joint part (13), and one of the first axial play (So) and the second axial play (Si) is greater than 50 micrometers and the other of the first axial play (Si) and the second axial play (So) is greater than 75 micrometers.

11. Manufacture the first joint part (12) in the form of an outer joint part and the second joint part (13) in the form of an inner joint part. The first bolt track (22A), the second bolt track (22B), and the circumferential surface (24) of the outer joint portion are soft-finished by a special molding process, and then the first outer bolt track (22A) and the second outer bolt track (22B) of the outer joint portion are hardened. The method according to any one of claims 1 to 10, characterized in that the first bolt track (23A), the second bolt track (23B), and the circumferential surface (26) of the inner joint portion are soft-pre-machined, then hardened, and then hard-finished by machining.

12. The first outer bolt track (22A) is formed to have a first outer undercut (H22A) on the opening side, the second outer bolt track (22B) is formed to have a second outer undercut (H22B) on the opening side, and the first outer undercut (H22A) is smaller than the second outer undercut (H22B). The method according to any one of claims 1 to 11.

13. The method according to any one of claims 1 to 12, characterized in that at least one of the outer cage surface (16) and the inner cage surface (17) is soft-finished by a special molding process and then hardened.

14. In the operating state of the counter track joint, the outer joint portion (12) and the inner joint portion (13) are manufactured such that the inner joint portion (13) is movable at a joint angle (β) greater than 20° and at most 30° with respect to the outer joint portion (12). The method according to any one of claims 1 to 13, characterized in that the ratio of the operating PCD (WPCD12) of the outer joint portion (12) to the maximum diameter (d13) of the insertion opening (34) of the inner joint portion (13) is less than 2.05 (WPCD12 / d13 < 2.05).

15. To attach the balls (14A, 14B), the inner joint portion (13) is rotated with respect to the outer joint portion (12), whereby the first inner ball track (23A) faces the first outer ball track (22A) to form a first track pair that expands toward the opening side of the outer joint portion (12), and the second inner ball track (23B) faces the second outer ball track (22B) to form a second track pair that expands toward the connecting portion side of the outer joint portion (12). With the inner joint portion (13) and the outer joint portion (12) deflected relative to each other, the first track pair and the second track pair each accommodate one of the balls (14A, 14B), the balls (14A, 14B) are inserted into the cage window (15), and the balls (14A, 14B) are held by the ball cage (15) in the joint center plane (EM) with the longitudinal axis (L13) of the inner joint portion (13) and the longitudinal axis (L12) of the outer joint portion (12) coaxially aligned. A part of a plurality of webs (31m) of the inner joint portion (13) is formed with flattened portions (32A, 32B) on both sides, whereby the ball cage (15) can be passed through the cage window (18) for assembly and / or a pocket (29B) that is recessed radially with respect to the functional track portion, and on the connecting portion side provided with the pocket (29B) in which the ball (14B) associated with the case when the constant velocity joint (11) is articulated can move radially, at least a part of the plurality of second outer ball tracks (22B) of the outer joint portion is formed. The method according to any one of claims 1 to 14, characterized in that.

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