Method for forming a spline-machined part

Abstract

A novel method for manufacturing a torque transmission component is provided. The method includes providing a flat blank to a transfer press having multiple stations and performing multiple pressing operations, where the flat blank is formed into a cup shape, a rough spline is formed on the cup shape, and the rough spline is further machined to define a smooth spline. The component includes a continuous smooth inner diameter defined by a punch in the transfer press and a plurality of smooth splines defined by a die in the transfer press. The minor diameter of the spline is not machined to form the spline.

Description

Technical Field

[0001] Cross - Reference to Related Applications This PCT international patent application claims the benefit of U.S. Provisional Patent Application No. 62 / 978,096, filed on February 18, 2020, and incorporates by reference in its entirety herein.

Background Art

[0002] Field The present disclosure generally relates to a novel manufacturing method for splined parts and to splined parts manufactured according to this novel method. More specifically, the present disclosure relates to parts manufactured using a drawing process, a roller die spline forming process, and a coining operation, all of which can be sequentially provided to a transfer press apparatus.

Summary of the Invention

Problems to be Solved by the Invention

[0003] Background This section provides background information related to the present disclosure that is not necessarily prior art.

[0004] For example, types of power transmission devices used in automotive applications, such as automatic transmissions, torque converters, power take - off units, and transfer cases, typically incorporate a hydraulically - actuated multi - plate clutch assembly. Typically, a multi - plate clutch assembly includes a first clutch Component (such as a clutch hub) driven by an input component, a second clutch member (such as a clutch drum) driving an output component, a multi - plate clutch pack disposed therebetween, and a hydraulic clutch actuator for engaging the clutch pack to transmit driving torque from the clutch hub to the clutch drum. The clutch drum and the clutch hub are typically annular components having torque - transmitting spline teeth configured to engage and mesh with corresponding clutch teeth formed on the clutch plates of the clutch pack.

[0005] To reduce the mass of such clutch members while maintaining the necessary high strength and torque transmission characteristics, many modern clutch hubs and drums (hereinafter collectively referred to as "annular clutch parts") are formed from sheet metal blanks using various combinations of metal forming and metal cutting processes. Non-limiting examples of current mass production processes for annular clutch parts include Grob spline machining and flow forming.

[0006] Due to the design of these sheet metal clutch parts being formed, the currently available processes also have several known drawbacks. Specifically, the annular clutch part is first formed from a steel blank that is drawn into a cup-shaped part having a radially extending plate segment and an axially extending hub segment. The cup-shaped part is then formed on a mandrel, and a spline shape is created on the hub segment by Grob spline machining. The start of the spline shape from the flat flange segment to the outer diameter is in the form of a radius where the large radius is at the large OD and the small radius is at the small OD. Typically, after forming the spline, additional metal cutting or machining is required to form a mounting segment on the plate segment configured to allow subsequent welding or joining of another torque transmission part. Metal cutting machining is also typically required to ensure the flatness of the plate segment of the annular clutch part. However, in machining the plate segment, the cutting tool needs to cut along the entire length of the plate segment and encounter the spline-shaped edges on both surfaces of the large OD and small OD surfaces. This "cut" edge shape interrupts the cutting, and as a result, the machined edge material is pushed into the underlying spline shape as burrs. Therefore, subsequent deburring operations are required to remove the burrs in the spline-shaped area. Burrs that are not removed prior to the assembly of the clutch assembly can potentially have an adverse effect on the function and service life of the clutch assembly.

[0007] One way to form an external spline is broaching. In broaching, material is removed from the outer surface of the part to define the broached outer surface. However, this process can cause deterioration of the surface finish on the small diameter of the external spline and on the side surfaces of the external spline. The resulting deterioration of the surface finish can prevent the smooth sliding movement of the friction plate in contact with the spline surface. In addition, broaching has a long cycle time, such as 20 - 30 seconds, and the manufacturing cost can also be high.

[0008] Another way to form an external spline is one-shot forming. In one-shot forming, the spline material is formed and can provide an improved surface finish compared to broaching. However, the surface finish is still not as smooth as typically desired. The cycle time for such forming can be about 15 - 20 seconds, and the manufacturing cost is high.

[0009] In a further method of forming a spline, a cam die or a roller die is used. The cycle time for such processing can be shortened to 4 seconds, and the cost can be relatively low compared to broaching or one-shot forming. Similar to one-shot forming, this process is a material forming process rather than a material removal process like broaching. However, in this approach, the inner diameter of the part is not continuous. Rather, the side wall of the part has a generally constant thickness, and the large outer diameter, small outer diameter, as well as the large inner diameter and small inner diameter are defined by the processing.

[0010] Therefore, it is necessary to develop a metal forming process that can form an annular clutch part, which is more advanced than the conventional cold forming (Grob spline forming) process.

Means for Solving the Problems

[0011] Overview This section provides a general overview of the present disclosure and is not intended to be construed as an exhaustive list of all aspects, features, advantages, and objectives thereof.

[0012] One aspect of the present disclosure is to provide a method for manufacturing high-strength torque transmission components. Another aspect of the present disclosure is to provide a method for manufacturing high-strength torque transmission components having a high-quality surface finish.

[0013] Another aspect of the present disclosure is to provide a method for manufacturing high-strength torque transmission components having a continuous inner diameter.

[0014] Another aspect of the present disclosure is to provide a method for manufacturing high-strength torque transmission components with a short cycle time and low manufacturing cost.

[0015] According to these and other aspects of the present disclosure, a splined annular component is provided, the annular component including a radial flange segment, an axially extending hub segment integrally formed with the radial flange segment, and a plurality of splines formed on a radially outer surface of the hub segment, the splines including a large outer diameter and a small outer diameter, the annular component further including a continuous inner diameter formed on a radially inner surface of the hub segment, the small outer diameter being smooth and formed without machining, and the inner diameter being smooth and formed without machining.

[0016] In one aspect, the hub portion has a radially varying thickness around the hub portion, and a first radially measured thickness between the inner diameter and the small diameter is smaller than a second radially measured thickness between the inner diameter and the outer diameter.

[0017] In one aspect, the component includes a chamfer disposed at an intersection of the flange segment and the hub segment, the chamfer being formed without machining.

[0018] In one aspect, the chamfer portion has an outward concave shape and an inward convex shape. In one aspect, the small diameter and the large diameter include a mirror finish.

[0019] In one aspect, the component is formed from a blank coated with a sodium stearate soap coating.

[0020] In one aspect, the component is formed by a transfer press. In one aspect, the flange segment, the hub segment, and the spline are press-formed from a common blank.

[0021] In one aspect, the inner diameter includes a vertically extending witness mark that is circumferentially aligned with the small diameter.

[0022] According to yet another aspect of the present disclosure, a method of manufacturing a torque transmission component is provided, the method including providing a flat blank having a flat shape to a transfer press having a first station, a second station, a third station, and a fourth station, the first, second, third, and fourth stations each including a first, second, third, and fourth die and a first, second, third, and fourth punch, the method further including pressing the blank between the first die and the first punch at the first station of the transfer press to form an unfinished part having a radially extending flange segment and an axially extending hub segment, the unfinished part being in the form of a first cup-shaped preform, the method further including transporting the first preform to the second station and pressing the first preform between the second die and the second punch to define a second preform of the unfinished part having a chamfered portion disposed between the flange segment and the hub segment, transporting the second preform to the third station and pressing the second preform between the third die and the third punch to define a rough spline-machined preform of the unfinished part having a plurality of rough splines extending radially outwardly from the hub segment, transporting the rough spline-machined preform to the fourth station and pressing the rough spline-machined preform between the fourth die and the fourth punch to define a smooth spline-machined part having a final radially extending flange segment and a final axially extending hub segment, the smooth spline-machined part including a constant inner diameter, a smooth minor outer diameter, and a smooth major outer diameter along the final axially extending hub segment.

[0023] In one aspect, the first, second, third, and fourth punches have decreasing outer diameters. In one aspect, the pressures applied at the first, second, third, and fourth stations are different.

[0024] In one aspect, the third and fourth dies include vertically extending protrusions sized and configured to form the spline.

[0025] In one aspect, at the third station, the hub segment elongates axially in response to the pressing operation.

[0026] In one aspect, the first die and the first punch define a gap at a location that transitions from the flange segment to the hub segment.

[0027] In one aspect, the second die includes a support for forming the chamfer at the transitioning location.

[0028] In one aspect, the third station includes a counter-pressure sleeve surrounding the third punch, and the method further includes holding the counter-pressure sleeve above the hub segment.

[0029] In one aspect, the method includes pressing the material of the rough spline into a space defined by the fourth die.

[0030] In one aspect, no machining operations are performed on the minor diameter of the spline. In one aspect, the method includes trimming the upper end of the smoothly splined part.

[0031] Further applicable areas will become apparent from the description provided herein. The descriptions and specific examples in this summary are for illustrative purposes only and are not intended to limit the scope of the present disclosure.

[0032] The drawings described in this specification are merely illustrative of selected embodiments and not all possible realizations, and are not intended to limit the scope of the present disclosure.

Brief Description of the Drawings

[0033]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7A

Figure 7B

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12A

Figure 12B

Figure 12C

Figure 13A

Figure 13B

Figure 13C

Figure 14A

Figure 14B

Mode for Carrying Out the Invention

[0034] Detailed Description Throughout several of the drawings, corresponding reference numerals indicate corresponding parts and / or subassemblies.

[0035] Here, exemplary embodiments will be described in more detail with reference to the accompanying drawings. The exemplary embodiments are provided so that this disclosure is complete and can fully convey the scope to those skilled in the art. To enable a thorough understanding of the embodiments of this disclosure, numerous specific details are set forth, such as examples of specific components, devices, and methods. It will be apparent to those skilled in the art that specific details may not be necessary, and the exemplary embodiments may be embodied in many different forms and should not be construed as limiting the scope of this disclosure. In some exemplary embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail.

[0036] The terms used herein are for the purpose of describing particular exemplary embodiments only and are not intended to be limiting. The singular forms “a,” “an,” and “the” used herein may be intended to include the plural forms as well, unless the context clearly dictates otherwise. The terms “comprises,” “comprising,” “including,” and “having” are inclusive and thus specify the presence of the stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. The method steps, processes, and operations described herein should not be construed as necessarily requiring that they be performed in the particular order described or illustrated, unless specifically identified as an order of execution. It should also be understood that additional or alternative steps may be utilized.

[0037] When an element or layer is referred to as being "on," "engaged with," "connected to," or "coupled to" another element or layer, it may be directly on top of the other element or layer, directly engaged with the other element or layer, directly connected to the other element or layer, or directly coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being "directly on top of," "directly engaged with," "directly connected to," or "directly coupled to" another element or layer, intervening elements or layers may not be present. Other words used to describe the relationship between elements (e.g., "between" versus "directly between," "adjacent" versus "directly adjacent," etc.) should be interpreted in the same manner. As used herein, the term "and / or" encompasses any and all combinations of one or more of the associated listed items.

[0038] The terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers, and / or sections, but these elements, components, regions, layers, and / or sections should not be limited by these terms. These terms may be used only to distinguish one element, component, region, layer, or section from another. The terms "first," "second," etc. and other numerical terms, when used herein, do not implicitly indicate a sequence or order unless specifically stated in the context. Thus, a first element, component, region, layer, or section below may be referred to as a second element, component, region, layer, or section without departing from the teachings of the exemplary embodiments.

[0039] Spatially relative terms, such as "inner", "outer", "below", "beneath", "lower", "above", "upper", etc., may be used herein for ease of description to describe the relationship of one element or feature shown in the drawings to another element or feature. Spatially relative terms are intended to encompass different orientations of an element in use or operation in addition to the orientation shown in the drawings. For example, if an element in a figure is turned upside down, an element described as "below" or "beneath" another element or feature will then be "above" the other element or feature. Thus, the exemplary term "below" can encompass both an upward and a downward orientation. An element may be oriented differently (rotated 90 degrees or otherwise oriented), and the spatially relative descriptors used herein may be interpreted accordingly.

[0040] Generally, the teachings of the present disclosure are directed to a method of manufacturing an annular component from a steel blank, the method being capable of providing a straight formed spline that has not been machined. The present disclosure further relates to an annular clutch component fabricated using this novel part forming process. In one embodiment, the annular component is a clutch hub of a multi-plate friction clutch assembly used in vehicle driveline applications, which may include, but is not limited to, automatic transmissions, transfer cases, power take-off units, torque couplings, and disconnect couplings.

[0041] Figures 1 - 3 together define a cup-shaped member formed by cold forming operations and having a conventional (prior art) clutch component (hereinafter "annular clutch component 10") with a radial plate or flange segment 12 and an axial hub segment 14. The cup-shaped member then generally undergoes a spline forming operation, known as Grob spline machining, by which a set of circumferentially aligned spline shapes 16, i.e., "splines", are formed in the axial hub segment 14. Thereafter, trimming and slot forming operations are performed to penetrate a plurality of oil feed holes 18 and appropriately size an aperture 20 formed in the radial flange segment 12. The annular clutch component 10 after these initial operations is shown in Figure 2. A known drawback of Grob spline machining lies in the shape of the outer radius at the interface 22 between the radial flange segment 12 and the axial hub segment 14. This shape requires subsequent machining (i.e., metal cutting operations) as shown in Figure 3 to remove material, and straight splines 24 machined for subsequent laser welding of additional drive / driven components and machined steps 26 are provided. It has been found that burrs are generated by the machining operations for the straight splines 24 and the burrs must be removed by deburring operations. The foregoing description is a simplified disclosure of a well-known method for manufacturing a metal-formed clutch hub having splines 16 sized and configured to engage internal clutch teeth formed in a clutch plate of a multi-plate clutch pack. Such a "prior art" clutch hub is satisfactory for its intended purpose. However, the following detailed disclosure of an alternative manufacturing method is intended to eliminate spline machining and step machining operations and to improve the surface finish of the splines.

[0042] For this purpose, FIGS. 4 and 5 show an improved annular component 100 manufactured according to the novel method disclosed herein. In particular, FIG. 4 shows that the annular component 100 includes a cup-shaped member disposed about a central axis and having a radial flange segment 102 and an axially extending hub segment 104. The radial flange segment 102 and the hub segment merge at an interface 105. The hub segment 104 extends from the interface 105 to an open end opposite the flange segment 102.

[0043] As will be further described below, the cup-shaped preform (formed by the drawing operation) then undergoes additional pressing and forming operations such that a continuous series of circumferentially aligned spline shapes 106 are formed in the hub segment 104. As can be seen, a central aperture 110 is also provided, and an oil feed hole (not shown but similar to those shown in FIGS. 1-3) may be provided through the hub segment 104. In accordance with the present disclosure, a multi-station transfer press 120 (FIG. 6) is used to output a finished part including the non-cut straight spline shape 106 (formed by the transfer press).

[0044] Referring to FIG. 6, a transfer press 120 including four stations 120a, 120b, 120c, 120d is shown. Each station can be used to define the final formed shape of the part 100 including the spline 106 prior to any additional finishing operations. Each station will be described in further detail below.

[0045] The first station 120a can be referred to as a cup forming station. The second station 120b can be referred to as a diagonal surface forming station. The third station 120c can be referred to as a rough spline forming station. The fourth station 120d can be referred to as a finish spline forming station. Generally, the part formed after a certain station is placed into the next station for further forming, then removed and transported to the next station for further forming.

[0046] First, referring to FIG. 6, the transfer press 120 is configured to receive a flat blank 121 at the first station 120a, and a first pressing operation is performed on the blank 121 to begin defining a first cup-shaped preform 124 (having generally a radially oriented plate and an axially oriented hub portion). The first preform 124 is conveyed to the second station 120b, where the preform 124 undergoes a second pressing operation to define a second preform 126 (further defining the interface between the plate and the hub). Next, the second preform 126 is conveyed to the third station 120c, where the second preform 126 undergoes a third pressing operation to define a first splined preform 128 (a rough spline formed on the hub). Next, the first splined preform 128 is conveyed to the fourth station 120d, where the first splined preform 128 (having a rough spline shape) undergoes a fourth pressing operation to further define and shape the spline 106 and define the part 100.

[0047] For purposes of further explanation, the various intermediate shapes created between the initial flat blank 121 and the ultimately formed and splined part 100 (e.g., the various formed and splined preforms 124, 126, 128 described above) may be collectively referred to as unfinished parts 122 since they are conveyed and pressed and formed at the various stations 120a - 120d. The flat blank 121 may also generally be referred to as an unfinished part 122, and the unfinished part 122 at the final stage of the transfer press 120 may also (although it has passed through the final stage of the transfer press 120 and is in a state of being removed from the transfer press as the finished part 100) still be referred to as an unfinished part 122. When the shape of the flat blank 121 is changed to one of the intermediate shapes of the unfinished part 129 by pressing and forming, the unfinished part 122 is formed within the station and conveyed between stations, so it will be understood that the shape of the unfinished part 122 is different from the shape of the initially provided flat blank 121.

[0048] Each station of the transfer press 120 may be operated simultaneously so that the first, second, third, and fourth pressing operations are generally performed simultaneously on the different-shaped unfinished parts 122 at different forming stages. Accordingly, the cycle time per pressing operation can be shortened to, for example, 4 seconds. The unfinished parts 122 at the various forming stages may be automatically conveyed between stations between pressing instances by an automatic or robotic conveyance mechanism (not shown).

[0049] Next, referring to FIGS. 7A and 7B, the flat blank 121 is shown in its flat form. The blank 121 may have a generally flat shape with a constant thickness. In one aspect, the blank 121 may be made of high-strength steel. However, it will be understood that other materials, such as aluminum, may be used depending on the material requirements of the particular type of part 100 to be formed. The blank 121 may include a central aperture 110 such that the blank 122 has an annular shape. Depending on the final shape and size of the particular part 100, blanks 121 of various dimensions may be used. For the purposes of the description herein, specific dimensions may be described and / or illustrated for purposes of example and explanation. It will be understood that other dimensions are also possible. In one aspect, the diameter of the blank 121 may be about 230 mm and the diameter of the aperture 110 may be about 90 mm. The thickness of the blank 121 in this example may be about 3.6 mm. Thus, the blank 121 may be described, in this example, as a thin circular disk having a hole located at the center of the blank 121.

[0050] In one aspect, the blank 121 may include a coating 121a on both sides of the disk shape. The coating may be applied in a salt bath and may be used to assist in reducing the heat during the forming operations described herein. In one aspect, the active ingredient of the coating 121a may be sodium stearate soap.

[0051] The thickness of the blank 121 may be selected based on various factors, such as the desired amount of material movement, particularly the amount of material movement that occurs when forming the spline 106 on the outer diameter of the part 100. During spline forming, the material is pushed, shaped, and moved from a thick region to a spline region with a large volume. In other words, the material can be pushed or pulled into the open space defined by the tool to form the spline 106. Thus, the material of the unfinished part 122 is generally not removed from the unfinished part 122 during spline forming, but rather is reallocated to define the large and small outer diameters of the outer surface and then forms a rough spline shape that is subsequently finished.

[0052] After the flat blank 121 is processed into unfinished parts 122 of various shapes, it is introduced into the transfer press 120 as described above and conveyed between the stations 120a - d. Next, each transfer station 120a - d will be described in more detail.

[0053] Referring to FIG. 8, before performing the first pressing operation, also referred to as the first drawing process, the flat blank 121 is positioned and shown within the first station 120a. The first station 120a includes a first die 130 and a first punch 132. In fact, unless otherwise specified, each station includes a die and a punch, and these may be operated in a conventional transfer press operation. The punch is disposed above the die. Thus, relative orientations such as above and below are used herein to describe the various positions of the various parts. However, it will be understood that different orientations are also possible. For example, the punch may be disposed below the die. In another aspect, the punch and die may be configured to move horizontally or at an oblique angle with respect to horizontal / vertical.

[0054] Figures 8 through xx show cross-sectional views of the dies and punches of various stations 120a - d. The first die 130 may support a blank 122 that can be disposed above the die 130. In one aspect, the first die 130 may define an outer portion 130a that has an inner diameter defining a die cavity 130c defined radially within the outer portion 130a. In one aspect, the first die 130 may further include a lower portion (not shown) disposed below the cavity 130c, and this lower portion may be combined with the outer portion 130a to define a cup-shaped configuration. However, in one aspect, the bottommost surface of the flat blank 121 may not contact such a lower portion during the first press / molding operation, so the lower portion may be omitted. Subsequent forming operations at subsequent stations may be used to define a radially extending plate portion of the part.

[0055] The first die 130 (and other dies described herein) is shown cross-sectionally as generally half of a rotationally symmetric shape. It will be understood that a similar configuration is disposed on the opposite side of the central axis. As shown in FIG. 8, the central hole / aperture of the flat blank 121 is shown on the left side of the figure below the punch 132.

[0056] In one aspect, when the flat blank 121 is supported on the die 130, a retaining ring 134 having an annular shape may be disposed above the blank 121. More specifically, the retaining ring 134 may sandwich the blank 121 against the outer portion 130a of the die 130, and the blank 121 may extend over the die cavity 130c.

[0057] When the blank 122 is supported on the die 130 and the holding ring 134 is disposed on the blank 121, the blank 121 may undergo a first drawing process as shown in FIG. 9, and the flat blank 121 may transition to the unfinished part 122. The unfinished part 122 undergoes a plurality of subsequent operations until it reaches its finished form and its shape is further improved, particularly by forming the spline 106. The unfinished part 122 is the same as the flat blank 121 described above, but it will be understood that it has a different shape.

[0058] FIG. 9 shows how the unfinished part 122 is formed into a cup-shaped first preform 124 during the first drawing process. The first punch 132 moves to the position shown in FIG. 9 towards the first die 130. When the first punch 132 moves downward relative to the first die 130, the flat blank 121 is pushed downward into the die cavity 130c to create the first preform 124 of the unfinished part 122. The outer portion 130a of the die 130 may include a rounded inner edge 130d. When the flat blank 121 is pushed downward into the cavity 130c, the flat blank 121 slides inward along the top of the outer portion 130a and slides along the rounded edge 130d and falls into the cavity 130c to form the first preform of the unfinished part 122. The unfinished part 122 in this position has an outer edge 122a that is disposed below the top of the outer portion 130a of the die 130. In one aspect, the holding ring 134 may be lifted during the first drawing process so that the material can slide inward more easily. In another aspect, the holding ring 134 may be removed or eliminated.

[0059] The first punch 132 is sized to be received within the die cavity 130c and may include a bottom surface 132a and an outer diameter 132b. A chamfer 132c may be defined at the intersection of the bottom surface 132a and the outer diameter 132b. The chamfer 132c may be rounded at the intersection with the outer diameter 132b and may also be rounded at the intersection with the bottom surface 132a.

[0060] When the punch 132 is pressed into the die 130, the blank 122 is drawn in and bent around the overall shape of the punch 132. The chamfer portion 132c can form the component 122 to include a rounded edge 122b. The rounded edge 122b of the component 122 does not exactly match the shape of the chamfer portion 132c, and an open space or gap may be arranged between the punch 132 and the blank 122 in the region of the chamfer portion 132c.

[0061] In one aspect, the chamfer portion 132c may have a concave cross-sectional shape instead of a constant slope. In either case, since the material of the unfinished component 122 bends around the chamfer portion 132c, a space may be defined between the curved shape of the rounded edge 122b and the surface of the chamfer portion 132c.

[0062] In addition, the die 130 may define a gap or space between the blank 122 and the die 130 in the region of the chamfer portion 132c. The rounded edge 122b of the unfinished component 122 can be further formed and processed in subsequent pressing operations, such as at station 120b. Since both the chamfer portion 132c and the die 130 define a gap with respect to the unfinished component 122, the actual shape and curvature of the unfinished component 122 can vary from part to part at this step, and a more predictable curvature and shape can be defined in subsequent steps performed on the unfinished component 122.

[0063] It will be understood that the punch 132 may further have a different shape (in addition to or instead of the chamfer portion 132c) so as to define various shape features along the bottom surface 132a and the outer diameter 132b.

[0064] During the first drawing process shown in FIG. 9, the punch 132 may be actuated with a force of about 30 tons. In the first drawing process, since the flat blank 121 is not formed into its final shape, a relatively low amount of pressure is required. Rather, the blank 121 is formed into the cup-shaped first preform 124 of the unfinished part 122. In one aspect, the die 130 may include a gas assist that applies an upward force toward the punch 132 to provide a reaction force to the punch 132. Gas assist may also be used at other stations of the transfer press 120.

[0065] When the part 122 is formed into the preform 124 as shown in FIG. 9, the punch 132 and the die 130 may separate, and the part 122 may be removed and conveyed to the second station 120b.

[0066] Next, referring to FIGS. 10 and 11, it is shown that the part 122 is being formed at the second station 120b during the second press operation, i.e., the second drawing process. The second station includes a second die 140 and a second punch 142. The shapes of the second die 140 and the second punch 142 may generally be similar to those of the first die 130 and the first punch 132. However, the following differences provide further shaping of the blank 122.

[0067] The second die 140 may include a support portion 140e disposed at an inner corner between the outer portion 140a and the lower portion 140b. The support portion 140e is in contrast to the voids described above. The support portion 140e is shaped to define the rounded edge 122b of the part 122 into a different shape corresponding to the shape of the support portion 140e. The punch 142 includes a corner shape corresponding to the shape of the support portion 140e.

[0068] As shown in FIG. 10, the support portion 140e may generally have a convex shape, and the punch 142 may generally include a concave shape. As shown in FIG. 10, the punch 142 is not yet fully pressed to engage with the die 140, and the component 122 still has a generally curved edge of the first preform 124.

[0069] FIG. 11 shows how the corners of the component 122 are formed into a shape corresponding to the shapes of the support portion 140e and the punch 142. In FIG. 11, the punch 142 is pushed down to engage with the die 140. The shape of this corner of the blank 122 may be application-specific depending on the design needs of the final component and is generally independent of the design needs of spline forming. As shown in FIG. 11, the gaps on both sides of the corner of the unfinished component 122 are eliminated, and the corner is shaped like the punch 142 and the die 140 at the position of the support portion 140e.

[0070] The second die 140 may include an inner diameter defined by the outer portion 140a that is slightly smaller than the inner diameter defined by the outer portion 130a of the first die 130. The second punch 142 may have a diameter slightly smaller than that of the first punch 132. The reduction in diameter from the punch / die for the first station 120a functions such that a rough shape can be defined at the first station 120a and then the shape can be further refined and defined at the second station 120b. Also, since the diameter of the punch 142 is small, the punch can be more easily received within the first preform 124.

[0071] Before the punch 142 and the die 140 are both translated to the positions shown in FIG. 11, the part 122 may be disposed above the upper surface of the second die 140 in the state of its cup-shaped first preform 124. The second punch 142 fits inside the cup-shaped inner diameter of the unfinished part 122. By the pressing operation of the second drawing process (shown in FIG. 11), the final shape of the part 100 without splines is effectively defined. However, the inner diameter may ultimately be slightly smaller during the spline forming process. In addition, the shape of the chamfered area of the part 122 may be further changed by including different die shapes as desired. During the second drawing process, a force of 510 tons may be applied by the second punch 142. The force applied at the second station 120b during this drawing process is considerably higher than the force applied at the first station 120a because the geometric shape of the unfinished part 122 is more precisely defined.

[0072] After the second drawing process at the second station 120b, the unfinished part 122 having its second preform shape 126 may be removed from the second station 120b and conveyed to the third station 120c.

[0073] Referring to FIGS. 12A - 12C, the third station 120c is shown, and the part 122 is formed to include rough-form splines 106 on the outer surface of the unfinished part 122. The third station 120c includes a third punch 152 and a third die 150.

[0074] The outer portion 150a of the die 150 may define a negative shape with respect to the desired shape of the splines 106 for the ultimately formed part 100. In other words, the die 150 may include a plurality of vertically extending protrusions 150f corresponding to the shape of the indentation of the desired splines 106. Each protrusion 150f may extend radially inward from the outer portion 150a of the die. The protrusion 150f may include a lead-in feature 150g at the uppermost end of the protrusion 150f.

[0075] Before operating the punch 152 and / or the die 150, an injector (not shown) may hold the blank 122 above the position of the die 150 prior to the pressing operation.

[0076] During the pressing operation, the punch 152 may apply a pressure of about 140 tons. During the pressing operation, the die 150 pushes / pulls the material of the blank 122 upward along the outer portion 150a of the die 150, extending the axial length of the part 122 in the region of the spline 106. By pulling the material of the part 122, further, the material is pressed against the outer diameter of the punch 152, and the outer diameter of the punch 152 operates to define the inner diameter of the part 122. In one example, the top of the unfinished part 122 is about 63.9 mm above the lowermost surface of the unfinished part. In the previous pressing step, the top of the part 122 was about 46.9 mm from the lowermost surface of the part 122. Since the inner diameter of the punch 152 is slightly smaller than the inner diameter of the second punch 142, the third punch 152 can fit into the unfinished part 122 and can form the material during the pressing operation and press it against the slightly smaller diameter of the third punch 152.

[0077] Figures 12A and 12B show the punch 152 and the die 150 in two positions. Figure 12A shows the punch 152 and the die 150 before the pressing operation, and Figure 12B shows the formation of the rough form of the spline 106 by moving the die 150 upward relative to the punch 152. The inner diameter 122 of the part is generally constant and is defined by the diameter of the punch 152.

[0078] In one aspect shown in Figures 12A and 12B, a counter-pressure sleeve 153 is disposed above the part 122 and surrounds the punch 152. The counter-pressure sleeve 153 may be fixed in a predetermined position relative to the punch 152, and when the punch 152 moves downward relative to the die 150, the counter-pressure sleeve operates to fix the unfinished part 122 when the spline is formed by the relative upward movement of the die 150.

[0079] In another aspect, the counter pressure sleeve 153 may be eliminated and the punch 152 may provide a counter pressure.

[0080] After the pressing operation of the third station 120c in FIG. 12, the part 122 includes a rough form of the external spline 106 thereon, and the annular wall of the part 122 has an extended axial length caused by the pulling and forming of the material caused by the vertical protrusion hitting the part 122. Then, the part 122 formed as the first spline-machined preform 128 having the rough form of the spline 106 thereon can be taken out and transferred from the third station 120c to the fourth station 120d. FIG. 12C is a top view of the first spline-machined preform 128, showing a constant inner diameter and the rough form of the spline 106.

[0081] FIGS. 13A-13C show a further spline forming pressing operation in which the rough form of the spline 106 is formed into a final smooth form. The reference to the final form refers to the last station 120d of the processing of the disclosed transfer press 120, but it will be understood that additional processing may be further performed.

[0082] Similar to the previous station, the part 122 is positioned above or in the upper opening of the fourth die 160, and the fourth punch 162 is configured to be inserted into the blank 122 to push the blank 122 into the fourth die 160. The outer shape of the fourth punch 162 mimics the final inner shape of the part 100. Similarly, the shape of the fourth die 160 mimics the final outer shape of the part 100. The cooperating shapes of the fourth die 160 and the fourth punch 162 are configured to form the material of the unfinished part 122 into the form of the final part 100, and the corresponding shapes of the fourth die 160 and the fourth punch 162 define the smooth continuous inner diameter 101, the chamfered edge 103, and the outer spline shape 106 of the part 100. The fourth station 120d may also be referred to as a finishing spline forming station.

[0083] Prior to the pressing operation, as shown in FIG. 13A, the rough form of the spline 106 is aligned with the vertically extending protrusion 160f formed on the outer portion 160a of the fourth die 160, such that the protrusion 160f is aligned with the vertical recesses present in the rough form of the spline 106 of the preform 128. Similarly, the rough spline shape protruding radially outward of the part 122 is aligned with the recesses between the vertically extending protrusions 160f.

[0084] A pressure of approximately 95 tons may be applied to the fourth punch 162. Since the rough form of the spline 106 already exists, this pressure amount is lower than the pressure amount in the third station 120c. The diameter of the punch 162 is slightly smaller than the diameter of the third punch 152 and defines the smooth continuous inner diameter 101 of the part 100.

[0085] At the end of the pressing operation of the fourth station 120d shown in FIG. 13B, the unfinished part 122 is in the form of the finished part 100 and may be removed. In this form, the forming operation is complete, and since the inner diameter 101, the chamfered region 103, and the external spline geometry 106 are in their final formed states, the unfinished part 122 may be referred to as part 100 or the finished part 100. FIG. 13C shows a top view of the finished part 100 including the inner diameter 101 and the spline 106.

[0086] However, additional processing may be further performed on the part 100. For example, the part 100 may be trimmed by a trimming operation at the upper end where the material of the part 100 was pushed / pulled during the spline forming step. However, further machining of the spline 106 is not required. In addition, the smooth and continuous inner diameter 101 of the part 100 provides a part that does not require additional machining of the inner shape of the part 100. In other words, generally, there is no need to remove or machine the material in the radial direction of the part to define the spline shape or the inner or outer diameter of the part.

[0087] Thus, the resulting part 100 includes a smooth and continuous inner diameter 101. The external spline 106 further exhibits a smooth and shiny / mirror-like appearance. This appearance is different from the result of broaching or one-shot machining. In particular, the surface finish at the root of the spline 106 and on the outer surface of the spline 106 is mirror-like and very smooth as shown in FIG. 5, but in other machining, witness marks occur in the forming direction (along the length of the spline) and the finish is rougher. In the part 100, witness marks may exist at the inner corners of the cup shape of the part 100 as a result of the material contacting the punch of the transfer press 120. Thus, both the large outer diameter and the small outer diameter of the part 100 and its spline 106 are smooth and mirror-like. As shown in FIGS. 4 and 5, the inner diameter 101 includes vertically extending witness marks that are circumferentially aligned with the small diameter of the spline 106.

[0088] The improved surface finish of the spline 106 can improve the performance with mating components, and in particular, the sliding contact between the surface of the mating component and the spline 106 of the component 100 can be improved.

[0089] The machining described above and the resulting component 100 provide various advantages. For example, the cycle time of machining is shortened. As a result of the shortened cycle time and the reduced machining operations on the spline, the manufacturing cost is reduced. In addition, the surface finish is improved as described above, for example, compared to broaching.

[0090] Referring to FIG. 14A, a basic schematic view of a multi-plate friction clutch assembly 200 disposed between a rotary input component 202 and a rotary output component 204 is shown. The clutch assembly 200 includes a clutch hub 206 driven by the input component 202, a clutch drum 208 driving the output component 204, a clutch pack 210, and a hydraulic clutch actuator 212. In one aspect, the component 100 may be formed as the clutch hub 206. The clutch pack 210 includes an inner clutch plate 214 coupled to the clutch hub 206 via a spline and an outer clutch plate 216 coupled to the clutch drum 208 via a spline. The clutch actuator 212 applies an engagement force to the clutch pack 210 to transmit driving torque from the input component 202 to the output component 204. At least the clutch hub 206 (and optionally the clutch drum 208) is intended to be manufactured using the method of the present disclosure.

[0091] FIG. 14B is a basic schematic view of the friction clutch assembly 200 being used as a hydraulic braking device and optionally as part of an automatic transmission. As shown, the clutch drum 208 is a stationary member here, but the clutch hub 206 is coupled to a component of the planetary gear set 220. As is well known, the release and braking operations of the friction clutch 200 function to provide a pair of speed ratio outputs to the output component 204 via the planetary gear set 220.

[0092] The purpose of exemplifying these potential uses of the component 100 of the present disclosure is to enable those skilled in the art to understand that these components 100 can be adapted to a wide variety of automotive and non-automotive torque transmission applications.

[0093] The description of the embodiments described above is provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the present disclosure. The individual elements or features of a particular embodiment are generally not limited to that particular embodiment and, where appropriate, can be interchanged and used in the selected embodiment without specific recitation or description. Also, the individual elements or features of a particular embodiment may be variously modified. Such modifications should not be regarded as a departure from the present disclosure, and all such modifications are intended to be included within the scope of the present disclosure.

Claims

**Claim 1** A method of manufacturing a torque transmission component, the method comprising: providing a flat blank having a flat shape to a transfer press having a first station, a second station, a third station, and a fourth station, wherein the first, second, third, and fourth stations each include a first, second, third, and fourth die and a first, second, third, and fourth punch, and the method further comprises: at the first station of the transfer press, pressing the blank between the first die and the first punch to form a semifinished part having a radially extending flange segment and an axially extending hub segment, the semifinished part being in the form of a first cup-shaped preform, and the method further comprises: transferring the first preform to the second station and pressing the first preform between the second die and the second punch to define a second preform of the semifinished part having a chamfered portion disposed between the flange segment and the hub segment; transferring the second preform to the third station and pressing the second preform between the third die and the third punch to define a rough spline-machined preform of the semifinished part having a plurality of rough splines extending radially outward from the hub segment; transferring the rough spline-machined preform to the fourth station and pressing the rough spline-machined preform between the fourth die and the fourth punch to define a smooth spline-machined part having a final radially extending flange segment and a final axially extending hub segment; and the smooth spline-machined part includes a constant inner diameter, a smooth minor outer diameter, and a smooth major outer diameter along the final axially extending hub segment. **Claim 2** The method of claim 1, wherein the first, second, third, and fourth punches have decreasing outer diameters. **Claim 3** The method of claim 1, wherein the pressures applied at the first, second, third, and fourth stations are different. **Claim 4** The method according to claim 1, wherein the third and fourth dies include vertically extending protrusions sized and configured to form the spline.

5. The method according to claim 1, wherein in the third station, the hub segment extends axially in response to the pressing.

6. The method according to claim 1, wherein the first die and the first punch define a gap at a position transitioning from the flange segment to the hub segment.

7. The method according to claim 6, wherein the second die includes a support portion for forming the chamfer at the transitioning position.

8. The method according to claim 1, wherein the third station includes a counter-pressure sleeve surrounding the third punch, and the method further comprises holding the counter-pressure sleeve above the hub segment.

9. The method according to claim 1, further comprising pressing the material of the rough spline into a space defined by the fourth die.

10. The method according to claim 1, wherein no machining operation is performed on the small outer diameter of the spline.

11. The method according to claim 10, further comprising trimming the upper end of the smoothly splined part.

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