COMPOSITE METAL FLEX SHEET

Abstract

Composite metal flex plate, comprising: an aluminum center plate (12, 112, 212) having a circular body (18, 118, 218) defining a central opening about an axis of rotation of the composite metal flex plate, the circular body (18, 118, 218) having a perimeter (24, 124, 224, 324, 424); and a steel ring gear (14, 114, 214) including an annular body (36, 136, 236, 336, 436) and external teeth formed integrally with and disposed around the annular body (36, 136, 236, 336, 436), wherein the annular body (36, 136, 236, 336, 436) of the steel ring gear (14, 114, 214) is secured to the periphery (24, 124, 224, 324, 424) of the circular body (18, 118, 218) of the aluminum center plate (12, 112, 212) by a solid-state connection (16, 116, 216), wherein the periphery (24, 124, 224, 324, 424) of the circular body (18, 118, 218) of the aluminum center plate (12, 112, 212) comprises an axial edge (26, 126, 226) extending axially from a distal end of the circular body (18, 118, 218), the axial edge (26, 126, 226) being inclined by an angle (β) of 10° to 80° to the axis of rotation, and wherein the solid-state connection (16, 116, 216) is formed between the axial edge (26, 126, 226) of the circular body (18, 118, 218) and a surface inclined by an angle (α) of between 10° to 80° to the axis of rotation (335) of the annular body (36, 136, 236, 336, 436) of the steel ring gear (14, 114, 214).

Description

INTRODUCTION

[0001] Many automobiles rely on an automatic transmission to perform torque conversions between the internal combustion engine and the downstream components of the drivetrain. To achieve torque transfer between the internal combustion engine and the automatic transmission, a torque converter is used to fluidly couple a crankshaft, which is rotationally driven by the internal combustion engine, and an input shaft of the automatic transmission, which delivers torque to a transmission output shaft through a planetary gear train. The crankshaft is attached to a front cover of a torque converter housing by a flexplate. Generally, a flexplate includes a disc-shaped center plate and a surrounding ring gear.The center plate includes a circular body defining a central opening—as well as various other holes and recesses for mounting and weight reduction / balancing—and capable of axial flexion to accommodate torque converter movement during varying vehicle speeds. The ring gear includes an annular body secured to an outer periphery of the center plate's circular body. The external teeth of the ring gear allow a pinion gear of the vehicle's starter motor to selectively rotate the flexplate when activated to initiate self-powered engine operation. The disc-shaped center plate and ring gear are each conventionally formed from steel, allowing them to be MIG-welded or laser-welded along their interface.

[0002] WO 2008 / 049 010 A2 discloses a torque converter comprising a pump assembly having a unitary pump swirl ring and vane arrangement and a formed sheet metal pump housing joined to the sheet metal pump housing by a metallurgical braze joint, a lock-up clutch disc assembly having a plurality of integrally formed vibration damping features 50, and a centrally located gear ring 24.

[0003] US 2007 / 0 277 644 A1 discloses a two-piece flywheel for use with an automotive engine, comprising a central plate with an annular periphery surrounded by a ring gear. The ring gear has an outer periphery with a plurality of radially outwardly extending teeth and an inner periphery. The inner periphery of the ring gear is seam-welded continuously 360 degrees to the annular periphery of the central plate.

[0004] DE 10 2013 202 583 B3 shows a friction welding process for fastening a connecting bushing in a housing.

[0005] DE 10 2016 224 386 A1 discloses a method for producing a blade with an airfoil and a blade root for a turbomachine. SUMMARY OF REVELATION

[0006] A composite metal flexplate according to an embodiment of the present disclosure may include an aluminum center plate and a steel ring gear. The aluminum center plate has a circular body defining a central opening about a rotational axis of the composite metal flexplate. The circular body also has a perimeter. The steel ring gear includes an annular body and external gear teeth integrally arranged circumferentially with the annular body. Furthermore, the annular body of the steel ring gear is fixed to the perimeter of the circular body of the aluminum center plate by a rigid connection.

[0007] The composite metal flexplate can be further defined. For example, the perimeter of the circular body of the aluminum center plate can include an axial edge extending axially from a distal end of the circular body, and the tight connection can be made between the axial edge of the circular body and the annular body of the steel ring gear. As another example, the perimeter of the circular body can include an axial edge extending axially from a distal end of the circular body, a radial edge extending radially outward from the axial edge and axially offset from the distal end of the circular body, and the tight connection can be made between at least one of the axial edge or the radial edge of the circular body of the aluminum center plate and the annular body of the steel ring gear.In yet another example, the annular body of the steel ring gear may include an annular main portion and a radial rim extending radially inward from the annular main portion, and the solid-state connection may be made between the circular body of the aluminum center plate and at least one of the annular main portion or the radial rim of the annular body of the steel ring gear.

[0008] A method for manufacturing a composite metal flexplate according to aspects of the present disclosure may include multiple steps. In one step, a surface of an annular body of a steel ring gear is heated. In another step, the surface of the annular body of the steel ring gear is brought into contact with a surface of a periphery of a circular body of the aluminum center plate while the surface of the annular body of the steel ring gear is still being heated. In yet another step, either the aluminum center plate or the steel ring gear is rotated while the other aluminum center plate or the other steel ring gear remains stationary to generate frictional heat between the contact surfaces of the annular body of the steel ring gear and the periphery of the circular body of the aluminum center plate.The generated frictional heat creates adjacent softened areas in the annular body of the steel ring gear and the circular body of the aluminum center plate. In yet another step, a force is applied to the contact surfaces of the annular body of the steel ring gear and the periphery of the circular body of the aluminum center plate to plastically deform the softened areas and forge the contact surfaces of the annular body of the steel ring gear and the periphery of the circular body of the aluminum center plate together, forming a solid-state bond as the softened areas cool and harden.

[0009] The method for manufacturing the composite metal flexplate may include additional steps or be further defined. In one implementation, the steel ring gear may be rotated while the aluminum center plate is held stationary. In another variation, the periphery of the circular body of the aluminum center plate may include an axial rim extending axially from a distal end of the circular body. The axial rim has an outer surface that contacts an inner surface of the annular body of the steel ring gear. In this regard, rotating the aluminum center plate or the steel ring gear results in relative contact rotational movement between the outer surface of the axial rim and the inner surface of the annular body of the steel ring gear to generate frictional heat therebetween.In yet another variation, the periphery of the circular body of the aluminum center plate may include an axial rim extending axially from a distal end of the circular body, and may further include a radial rim extending radially outward from the axial rim and axially offset from the distal end of the circular body. As such, rotating either the aluminum center plate or the steel ring gear results in relative contact rotational movement between at least one of (1) an outer surface of the axial rim and an inner surface of the annular body of the steel ring gear to generate frictional heat between the radial rim and a side surface of the annular body, or (2) a front surface of the radial rim and a side surface of the annular body of the steel ring gear to generate frictional heat therebetween.In yet another variation, the annular body of the steel ring gear may include an annular main portion and a radial rim extending radially inward from the annular main portion. To this end, rotation of either the aluminum center plate or the steel ring gear results in relative contact rotational movement between at least one of (1) a rear surface of an annular mating portion of the annular body of the aluminum center plate and a front surface of the radial rim of the annular body of the steel ring gear to generate frictional heat therebetween, or (2) an inner surface of the annular main portion of the annular body of the steel ring gear and a peripheral edge surface of the distal end of the circular body of the aluminum center plate to generate frictional heat therebetween.

[0010] The method for manufacturing the composite metal flexplate may also include heating the surface of the annular body of the steel ring gear by induction heating. Additionally, the surface of the annular body of the steel ring gear may have a temperature between 200°C and 580°C when brought into contact with the surface of a periphery of the circular body of the aluminum center plate. The aluminum center plate included in the composite metal flexplate may also define a central opening about a rotational axis of the composite metal flexplate, a first set of mounting holes proximate the central opening, and a second set of mounting holes proximate the periphery of the circular body.Furthermore, a dimensional control element may be arranged against a surface of the circular body of the aluminum center plate to resist distortion of the circular body when the force is applied that plastically deforms the softened regions and forges together the contact surfaces of the annular body of the steel ring gear and the periphery of the circular body of the aluminum center plate.

[0011] Another method for manufacturing a composite metal flexplate according to aspects of the present disclosure may include multiple steps. In one step, a steel ring gear is provided including an annular body and external gear teeth integrally and circumferentially disposed with the annular body. In another step, an aluminum center plate is provided having a circular body with a periphery, the circular body defining a central opening, a first set of mounting holes proximate the central opening, and a second set of mounting holes proximate the periphery. In another step, a surface of the annular body of the steel ring gear is heated to a temperature above 200°C.In a further step, the surface of the annular body of the steel ring gear and a surface of the circumference of the circular body of the aluminum center plate are rotated relative to each other while the surfaces are in contact with each other and the temperature of the surface of the annular body is between 200°C and 580°C, with either the steel ring gear or the aluminum center plate held stationary to generate frictional heat between the surfaces of the annular body of the steel ring gear and the circumference of the circular body of the aluminum center plate. The generated frictional heat creates adjacent softened regions in the annular body of the steel ring gear and the circular body of the aluminum center plate.And in yet another step, a force is applied to the surfaces of the annular body of the steel ring gear and the periphery of the circular body of the aluminum center plate that are in contact with each other to plastically deform the adjacent softened regions and forge the surfaces of the annular body of the steel ring gear and the periphery of the circular body of the aluminum center plate together to form a solid-state bond upon cooling and hardening of the softened regions.

[0012] The method for manufacturing the composite metal flexplate may include additional steps or be further defined. For example, the perimeter of the circular body of the aluminum center plate may include an axial rim extending axially from a distal end of the circular body. The axial rim has an outer surface that contacts an inner surface of the annular body of the steel ring gear. In this regard, rotating the aluminum center plate or the steel ring gear results in relative contact rotation between the outer surface of the axial rim and the inner surface of the annular body of the steel ring gear to generate frictional heat therebetween.In yet another variation, the periphery of the circular body of the aluminum center plate may include an axial rim extending axially from a distal end of the circular body, and may further include a radial rim extending radially outward from the axial rim and axially offset from the distal end of the circular body. As such, rotating either the aluminum center plate or the steel ring gear results in relative contact rotational movement between at least one of (1) an outer surface of the axial rim and an inner surface of the annular body of the steel ring gear to generate frictional heat between the radial rim and a side surface of the annular body, or (2) a front surface of the radial rim and a side surface of the annular body of the steel ring gear to generate frictional heat therebetween.In yet another variation, the annular body of the steel ring gear may include an annular main portion and a radial rim extending radially inward from the annular main portion. To this end, rotation of either the aluminum center plate or the steel ring gear results in relative contact rotational movement between at least one of (1) a rear surface of an annular mating portion of the annular body of the aluminum center plate and a front surface of the radial rim of the annular body of the steel ring gear to generate frictional heat therebetween, or (2) an inner surface of the annular main portion of the annular body of the steel ring gear and a peripheral edge surface of the distal end of the circular body of the aluminum center plate to generate frictional heat therebetween.Furthermore, a dimensional control element may be arranged against a surface of the circular body of the aluminum center plate to resist deformation of the circular body when the force is applied that plastically deforms the softened regions and forges together the surfaces of the annular body of the steel ring gear and the periphery of the circular body of the aluminum center plate that are in contact with each other. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a perspective view of a composite metal flexplate including an aluminum center plate and a steel ring gear circumferentially disposed about a perimeter of the aluminum center plate by a solid-state joint according to one embodiment of the present disclosure; Fig. 2 is a partial cross-sectional view of the composite metal flex plate of Fig. 1, taken along section lines 2-2 and showing the steel ring gear attached to the aluminum center plate; Fig. 3 is a micrograph showing the solid-state compound in Fig. 2, which connects the steel ring gear and the aluminum center plate; Fig. 4 is a partial cross-sectional view illustrating the step of the friction welding process in which a surface of the annular body of the steel ring gear is preheated according to an embodiment of the present disclosure; Fig. 5 is a partial cross-sectional view illustrating the step of the friction welding process in which the steel ring gear and the aluminum center plate are rotated relative to each other while surfaces of these two components are in contact with each other, according to an embodiment of the present disclosure; Fig. 6 is a partial cross-sectional view illustrating the step of the friction welding process in which the surfaces of the steel ring gear and the aluminum center plate, which have been rotated relative to each other, are pressed together under an applied force to forge these surfaces together according to one embodiment of the disclosure; Fig. 7 is a partial cross-sectional view of a composite metal flexplate including an aluminum center plate and a steel ring gear circumferentially disposed about a periphery of the aluminum center plate by a solid-state joint according to another embodiment of the present disclosure; Fig. Figure 8 is a partial cross-sectional view illustrating several steps of the friction welding process during which the steel ring gear and the aluminum center plate formed in Fig. 7 are connected to each other; Fig. 9 is a partial cross-sectional view of a composite metal flexplate including an aluminum center plate and a steel ring gear circumferentially disposed about a periphery of the aluminum center plate by a solid-state joint according to yet another alternative embodiment of the present disclosure; Fig. Figure 10 is a partial cross-sectional view illustrating several steps of the friction welding process during which the steel ring gear and the aluminum center plate formed in Fig. 9 are connected to each other; Fig. 11 is a partial cross-sectional view of a generally annular body of the steel ring gear and a periphery of the circular body of the aluminum center plate, illustrating inclined contact surfaces of these two components, according to an embodiment of the present disclosure; and Fig. 12 is a partial cross-sectional view of a generally annular body of the steel ring gear and a periphery of the circular body of the aluminum center plate, illustrating inclined contact surfaces of these two components according to another embodiment of the present disclosure. DETAILED DESCRIPTION

[0013] A composite metal flexplate is disclosed that includes an aluminum center plate and a steel ring gear. The steel ring gear is secured to the aluminum center plate by a solid-state bond, with material from the aluminum center plate and the steel ring gear being atomically interdispersed. Because the steel ring gear and the aluminum center plate are secured by a solid-state bond, brittle Fe-Al intermetallics are minimal, if present at all, within the bond formed between the two components, helping to ensure the bond is strong and able to resist fracture when the flexplate is rotated by the starter motor under normal operating conditions. To create the solid-state bond between the steel ring gear and the aluminum center plate, the two dissimilar metal components can be friction welded together.The friction welding process involves preheating the steel ring gear body, followed by rotating either the steel ring gear or the aluminum center plate. The other component is held stationary while the ring gear body and the periphery of a circular body of the center plate are in contact, generating frictional heat between them. After stopping the rotation of the rotating component, pressure is immediately applied to the contact portions of the two components to essentially forge the annular body of the steel ring gear and the periphery of the circular body of the aluminum center plate together.

[0014] The Fig. 1-3 illustrate a composite metal flexplate 10 according to one embodiment of the present disclosure. The composite metal flexplate 10 includes an aluminum center plate 12 and a steel ring gear 14 surrounding the aluminum center plate 12 and secured thereto by a solid-state bond 16. The aluminum center plate 12 may be comprised of a variety of aluminum alloy compositions, including heat-treatable aluminum alloys (e.g., AA 2000, certain 4000, 6000, and 7000 series aluminum alloys) and non-heat-treatable aluminum alloys (AA 3000, certain 4000 and 5000 series aluminum alloys). Several specific and non-limiting aluminum alloy compositions that may be employed include AA2014-T6, AA4032-T6, and AA7050-T6.The steel ring gear 14 may be constructed of a steel composition that possesses, or can be treated to possess, the strength and toughness properties required to support the function of the ring gear 14. For example, the steel ring gear 14 may be constructed of a medium carbon steel containing, for example, 0.30 wt.% to 0.55 wt.% carbon or a medium carbon alloy steel containing a similar carbon content. Several specific and non-limiting steel compositions that may be employed include SAE J405 1035-1050 steel alloys.

[0015] The aluminum center plate 12 includes a circular body 18, preferably formed by stamping. The circular body 18 defines a central opening 20 about a rotational axis 22 of both the body 18 and the composite metal flex plate 10 and has a perimeter 24 including an axial edge 26 extending axially from a distal end 28 of the body 18.Additionally, the circular body 18 defines a first set of mounting holes 30 near and around the central opening 20, a second set of mounting holes 32 spaced radially outward from the first set of mounting holes 30 and located near the distal end 28 of the circular body 18, and a plurality of circumferentially spaced cutouts 34 disposed between the first and second sets of mounting holes 30, 32 that reduce and properly distribute the weight of the center plate 12. When installed, the first set of mounting holes 32 receives bolts (not shown) that secure the aluminum center plate 12 to a crank flange on one side of the plate 12, and the second set of mounting holes 34 receives bolts that secure the aluminum center plate 12 to the front cover of a torque converter housing.The central opening 20 receives a pilot bushing which receives a pilot hub of the torque converter and serves to align a longitudinal axis of the engine crankshaft and a longitudinal axis of the transmission input shaft.

[0016] The steel ring gear 14 includes an annular body 36 and external teeth 38 integrally arranged circumferentially with the annular body 36. Each of the external teeth 38 protrudes radially outward from the annular body 36 of the ring gear 14 and extends axially along a thickness dimension of the annular body 36. The teeth 38 are typically hardened by induction hardening or another hardening process, while the annular body 36 supporting the teeth 38 is typically not hardened, allowing it to more easily participate in the formation of the solid-state joint 16. Depending on the design specification of the composite metal flexplate 10, which considers a variety of factors, including the required ring gear circumference, the number of external teeth 38 supported on the annular body 36 of the ring gear 14 can range from 100 to 200.In this particular embodiment of the composite metal flex plate 10 and as best shown in . Fig. 2, an inner wall portion 40 of the annular body 36 of the ring gear 14 is connected to an outer wall portion 42 of the axial edge 26 of the circular body 18 of the center plate 12 by the solid connection 16. The solid connection 16, as shown in the enlarged photomicrograph of Fig. 3, there is a metallurgical transition region between the annular body 38 of the ring gear 14 and the axial edge 26 of the circular body 18, wherein aluminum alloy and steel are atomically interdispersed with minimal or no Fe-Al intermetallic compounds present.

[0017] The solid-state joint 16 is preferably formed between the aluminum center plate 12 and the steel ring gear 14 by friction welding. As described in more detail below, friction welding is a solid-state joining process in which two metal components—one held stationary while the other is rotated—experience relative contact rotational movement between contacting portions of the components to generate frictional heat. The generated heat softens one or both components, so that an applied pressure or force plastically displaces material from one or both of the components to forge the two contacting portions together and enforce the atomic interdispersion that characterizes the solid-state joint 16. The friction welding process applicable herein may include at least a preheating step, a friction heating step, and a pressure application step. These steps are generally described in the Fig. 4-6 in connection with the production of the Fig. 1-3. Of course, the same method can be used to manufacture other alternative embodiments of the composite metal flex plate, some of which are described below in connection with the Fig. 7-10 are described.

[0018] The preheating step is in Fig. 4. In this step, an inner surface 44 of the annular body 36 of the ring gear 14 is heated in preparation for joining. The inner surface 44 of the unbonded steel ring gear 14 identified here will eventually be fully or partially integrated into the solid-state joint 16 and consequently lose its distinct interface demarcation as the inner wall portion 40 of the annular body 36 and the outer wall portion 42 of the axial edge 26 of the circular body 18 of the aluminum center plate 12 are forged together. The inner surface 44 of the annular body 36 can be heated by induction heating to a temperature above 200°C, or more particularly, between 200°C and 700°C.This may involve disposing an induction coil 46, such as an electromagnetic copper coil, adjacent the inner surface 44 of the annular body 36, and then passing a high-frequency alternating current, provided by a high-frequency power supply 48, through the induction coil 46. Passing the alternating current through the conduction coil 46 creates an alternating magnetic field that permeates the annular body 36 and generates eddy currents that resistively heat the inner surface 44, along with additional heating due to magnetic hysteresis.The targeted heating of the inner surface 44 of the annular body 36 to its elevated temperature - as opposed to heating the entire ring gear 14 - is useful here because it may be desirable to limit the heating of the external toothing 38 as much as possible in order to prevent the hardening back of its hardness in those situations in which the toothing 38 has already been hardened by heating and quenching to influence changes in the steel microstructure.

[0019] While the inner surface 44 of the annular body 36 is still at an elevated temperature between 200°C and 580°C (allowing some cooling if the original temperature has been heated to above 580°C), the friction heating step is carried out as in Fig. 5. In the friction heating step, the preheated (200° C-580° C) inner surface 44 of the annular body 36 of the steel ring gear 14 is adjacent and in contact with an outer surface 50 of the axial edge 26 of the circular body 18 of the aluminum center plate 12. Like the inner surface 44 of the annular body 36, the outer surface 50 of the axial edge 26 of the unbonded aluminum center plate 12 is eventually fully or partially integrated into the solid-state joint 16 when the inner wall portion 40 of the annular body 36 and the outer wall portion 42 of the axial edge 26 are forged together. Once contact has been established between the inner surface 44 of the annular body 36 and the outer surface 50 of the axial rim 26, either the aluminum center plate 12 or the steel ring gear 14 is rotated while either the other aluminum center plate 12 or the other steel ring gear 14 is held stationary.The relative contact rotational motion occurring between the inner surface 44 of the annular body 36 and the outer surface 50 of the axial rim 26 of the circular body 18 generates frictional heat between the surfaces 44, 50. This frictional heat softens adjacent regions 52, 54 of the annular body 36 and the axial rim 26, which extend from the inner surface 44 into the annular body 36 and from the outer surface 50 into the axial rim 26, respectively. Timely softening of the annular body 36 of the steel ring gear 14 is enabled by the advance heating of the inner surface 44 in the preheating step.

[0020] The aluminum center plate 12 and the steel ring gear 14 can be fixed and rotated relative to each other using conventional friction welding tools. In a preferred embodiment, for example, the aluminum center plate 12 is held stationary and the steel ring gear 14 is rotated. For this purpose, the aluminum center plate 12 can be lowered onto a support block (not shown). The support block can include guides or positioning rods that are received in one or more of the first and / or second sets of mounting holes 30, 32 defined in the circular body 18 of the center plate 12. Additional clamping devices can also be used to firmly hold the aluminum center plate 12 against the support block so that it remains stationary during the friction heating step.The steel ring gear 14 may be rigidly clamped or secured to an annular retaining member (not shown), which in turn is mounted on a rigid spindle. The preheating step may be practiced while the steel ring gear 14 is installed on the spindle to prevent significant heat loss during the time elapsed between the preheating and friction heating steps. Finally, the steel ring gear 14 is moved toward the aluminum center plate 12 until the inner surface 44 of the annular body 36 and the outer surface 50 of the axial rim 26 of the circular body 18 are in axially aligned contact. At this point, rotation of the spindle begins, causing the desired relative contact rotational movement between the inner surface 44 of the annular body 36 and the outer surface 50 of the axial rim 26.The speed and duration of spindle rotation is controlled to achieve the required softened areas 52, 54 in both the center plate 12 and the ring gear 14.

[0021] After the softened areas 50, 52 have been reached by the relative rotational friction contact, the pressure application step is carried out as in Fig. 6. In this step, the inner surface 44 of the annular body 36 and the outer surface 50 of the axial edge 26 of the circular body 18 are pressed together under an applied force 56. The inner surface 44 and the outer surface 50 are pressed together with sufficient force to cause plastic deformation of the compressed softened regions 52, 54 of the annular body 36 and the axial edge 26 and to forge the inner and outer surfaces 44, 50 together. The applied force 56 can be applied by pressing radially inward against the external teeth 38 of the steel ring gear 14, preferably hydraulically, opposite the resisting force of the axial edge 26 of the circular body 18.This radially inwardly directed pressing force against the external teeth 38 can be applied simultaneously around the entire circumference of the ring gear 14 or, in a variation, can be applied sequentially to several defined arcs of the circumference of the ring gear 14 until the entire circumference of the ring gear 14 has been pressed. Furthermore, if necessary, to prevent deformation of the axial rim 26, a dimensional control element 58 in the form of a block, plate, ring, or other suitable shape can be arranged against the inner surface 60 of the axial rim 26 to counteract the pressure applied radially inwardly against the external teeth 38 of the ring gear 14.

[0022] During the pressure application step, and possibly for a short time thereafter, the softened regions 52, 54, which are now plastically deformed, cool and harden into the solid-state joint 26. The composite metal flexplate 10 is now formed and can be removed from the friction welding tools. At this time, additional processing of the composite metal flexplate 10 can be performed. For example, any metal flash that may have been created by compressing and plastically deforming the softened regions 52, 54 of the annular body 36 and the axial rim 26 can be removed. Such flash removal can be accomplished in a variety of ways, including shearing, machining, or grinding, to name a few options.As another example, the external gear teeth 38 of the steel ring gear 14 may be hardened, if they may not have already been hardened together prior to friction welding the steel ring gear 14 and the aluminum center plate 12. Hardening the external gear teeth 38—whether before or after friction welding—typically involves induction heating the gear teeth 38, followed by quenching the gear teeth 38 in a water-based polymer solution containing rust inhibitors, and then induction tempering the gear teeth 38 to the desired surface hardness. As another example of a post-friction welding process, the composite metal flex plate 10 may be treated, at least in the exposed areas of the solid-state joint 16, by stress relieving, tempering, or coating to protect the joint 16 against premature corrosion.

[0023] The friction welding process described above is subject to several possible variations. In particular, when performing the friction heating step, the steel ring gear 14 may be held stationary while the aluminum center plate 12 is rotated. To perform the friction heating step in this manner, the steel ring gear 14 would be held firmly against the support block by clamps or other holding devices, and the aluminum center plate 12 would preferably be mounted on the rigid spindle through the central opening 20. Rotating the aluminum center plate 12 relative to a stationary steel ring gear 14 can generate frictional heat in the same manner as before to soften the adjacent regions 52, 54 of the annular body 36 and the axial rim 26, which are ultimately pressed together to form the solid-state joint 16 in the subsequent pressure application step.Additionally, as part of the preheating step, a heating technique other than induction heating may be used to heat the inner surface 44 of the annular body 36 of the steel ring gear 14. Resistance heating of the inner surface 44 is a possible alternative heating technique. Furthermore, the inner surface of the annular body 38 of the steel ring gear 14 and the outer surface 50 of the axial rim 26 of the circular body 18 may be cleaned prior to the preheating step.

[0024] In addition to the friction welding process, the resulting composite metal flex plate is also subject to a number of possible variations. Two such designs are described in the Fig. 7-8 and 9-10. The Fig. 7-8 is designated by the reference numeral 110, and the composite metal flex plate shown in the Fig. The composite metal flex plate shown in Figures 9-10 is designated by the reference numeral 210. In the following, only the material differences of these composite metal flex plates 110, 210 compared to the composite metal flex plate 10 described above will be explained in detail. Other features of these composite metal flex plates 110, 210, which are structurally and functionally similar to the features of the composite metal flex plates described above in connection with the Fig. 1-3 described composite metal flex plate 10 are designated with the corresponding reference numerals of the 100 series ( Fig. 7-8) and Series 200 ( Fig. 9-10). And, unless otherwise stated, the description of all characteristics of the Fig. 1-3 shown composite metal flex plate equally for all features in the Fig. 7-8 and 9-10, which are designated by a corresponding 100 or 200 series reference numeral, as if this discussion were repeated in its entirety herein. The above in connection with the Fig. 4-6 is capable of welding each of the materials described in the Fig. 7-8 and 9-10 to form the composite metal flex plates 110, 210.

[0025] With reference to the provisions of the Fig. 7-8, the perimeter 124 of the circular body 118 of the aluminum center plate 112 includes, as described above, an axial edge 126 and a radial edge 162 extending radially outward from the axial edge 126 and axially offset from the distal end 128 of the body 118. The solid-state connection 116 ( Fig. 7) interconnecting the steel ring gear 114 and the aluminum center plate 112 may be formed between (1) the inner wall portion 140 of the annular body 136 of the ring gear 114 and the outer wall portion 142 of the axial rim 126 of the circular body 118, (2) a sidewall portion 164 of the annular body 136 and a front wall portion 166 of the radial rim 162, or (3) both of the foregoing locations, as shown herein. To accommodate the radial rim 162, the external toothing 138 may extend axially beyond the annular body 136 along the thickness dimension of the body 136 so as to overlie a circumferential edge surface 168 of the radial rim 162, although this overhang of the external toothing 138 is not necessarily required.The inclusion of both the axial edge 126 and the radial edge 162 in the periphery 124 of the circular body 118 of the aluminum center plate 112 not only allows the formation of a wider solid-state connection 116 between the center plate 112 and the steel ring gear 114, but also allows the steel ring gear 114 and the aluminum center plate 112 to be easily positioned relative to each other during friction welding.

[0026] The aluminum center plate 112 and the steel ring gear 114 can be friction welded together using the same general friction welding tools in substantially the same manner as described above. With specific reference now to Fig. 8, the inner surface 144 and / or a side surface 170 of the annular body 136 of the ring gear 114 may be preheated during the preheating step, depending on where the metallurgical bond 116 is desired. Next, the aluminum center plate 112 and the steel ring gear 114 are secured such that the preheated inner surface 144 and the preheated side surface 170 of the annular body 136 are in contact with the outer surface 150 of the axial rim 126 and a front surface 172 of the radial rim 162, as shown. The aluminum center plate 112 and the steel ring gear 114 are then rotated relative to each other, rotating one of the components 112, 114 and holding the other of the components 112, 114 stationary.The relative contact rotational movement occurring between the surfaces 144, 150 and 170, 172 generates frictional heat between the surfaces 144, 150 and 170, 172 and softens the adjacent regions 152, 154 of the annular body 136 and the axial rim 126 and the adjacent regions 174, 176 of the annular body 136 and the radial rim 162.

[0027] An applied force then presses the inner surface 144 of the annular body 136 and the outer surface 150 of the axial rim 126 (force 156), the side surface 170 of the annular body 136 and the front surface 172 of the radial rim 162 (force 178), or both together in the pressure application step. The applied force 156, 178 causes plastic deformation of the compressed softened regions 152, 154, 174, 176 to forge their respective surfaces 144, 150 and 170, 172 together to ultimately produce the solid-state joint 116.The force 156 acting on the surfaces 144, 150 of the annular body 136 and the axial edge 126 can be applied hydraulically by pressing radially inward against the external toothing 138 of the steel ring gear 114 against the resisting force of the axial edge 126 of the circular body 118, as before, while the force 178 acting on the surfaces 170, 172 of the annular body 138 and the radial edge 162 can be applied by hydraulic pressing axially against the annular body 138 of the steel ring gear 114 against the resisting force of the radial edge 162 of the circular body 118. A dimensional control element 158 ​​may be disposed against the inner surface 160 of the axial edge 126 to counteract the pressure applied radially inwardly against the external toothing 138 of the ring gear 114 and to prevent distortion of the axial edge 126.Similarly, a dimensional control element 180 may be disposed against a back surface 182 of the radial rim 162 to counteract the pressure applied axially against the annular body 138 and to prevent distortion of the radial rim 162.

[0028] With reference to the provisions of the Fig. 9-10, the perimeter 224 of the circular body 218 of the aluminum center plate 212 is an annular connecting portion 284 that encompasses the distal end 228 of the body 218. In addition, the annular body 236 of the steel ring gear 214 includes an annular main portion 236' and a radial rim 286 extending radially inward from the annular main portion 236'. The radial rim 286 supports the perimeter 224 of the circular body 218 of the aluminum center plate 212. The solid-state connection 216 ( Fig. 9) that interconnects the steel ring gear 214 and the aluminum center plate 212 may be formed between (1) the inner wall portion 240 of the annular portion 236' of the annular main portion 236' of the steel ring gear 214 and an edge portion 288 of the distal end 228 of the annular body 218, (2) a forward portion 290 of the radial rim 286 of the annular body 236 and a rearward portion 292 of the circular body 218, or (3) both of the foregoing locations, as shown herein.In the same manner as in the previous embodiment, the inclusion of the radial rim 286 as part of the annular body 238 of the steel ring gear 214 not only allows for the formation of a wider solid-state joint 216 between the aluminum center plate 212 and the steel ring gear 214, but also allows the steel ring gear 214 and the aluminum center plate 212 to be more easily positioned relative to each other during friction welding.

[0029] The aluminum center plate 212 and the steel ring gear 214 can be friction welded together using the same general friction welding tools in substantially the same manner as described above. With specific reference now to Fig. 10, the inner surface 244 of the annular main portion 236' and / or a front surface 294 of the radial rim 286 of the annular body 236 of the ring gear 114 may be preheated during the preheating step, depending on where the metallurgical bond 216 is desired. The aluminum center plate 212 and the steel ring gear 214 are then attached such that the preheated inner surface 244 of the annular main portion 236' and the front surface 294 of the radial rim 286 contact a peripheral edge surface 296 of the distal end 228 of the circular body 218 and a rear surface 298 of the circular body 218, as shown here. The aluminum center plate 212 and the steel ring gear 214 are then rotated with respect to each other, with one of the components 212, 214 being rotated and the other of the components 212, 214 being held stationary.The relative contact rotational movement occurring between the surfaces 244, 296 and 294, 298 generates frictional heat between the surfaces 244, 296 and 294, 298 and softens the adjacent regions 300, 302 of the annular main portion 236' and the circular body 218 and the adjacent regions 304, 306 of the radial rim 286 and the circular body 218.

[0030] An applied force then presses the inner surface 244 of the annular main portion 236' and the peripheral edge surface 296 of the distal end 228 of the circular body 218 (force 256), the front surface 294 of the radial rim 286 and the rear surface 298 of the circular body 218 (force 278), or both together in the pressure application step. The applied force 256, 278 causes plastic deformation of the compressed softened regions 300, 302, 304, 306 to forge their respective surfaces 244, 296 and 294, 298 together, ultimately forming the solid-state joint 216.The force 256 acting on the surfaces 244, 296 of the annular main portion 236' of the annular body 236 and the circular body 218 can be applied hydraulically by pressing radially inward against the external toothing 238 of the steel ring gear 214 against the resisting force of the distal end 228 of the circular body 218, while the force 278 acting on the surfaces 294, 298 of the radial edge 286 of the annular body 236 and circular body 218 can be applied by hydraulic pressing axially against the annular body 238 of the aluminum center plate 212 against the resisting force of the radial edge 286 of the circular body 236.If necessary, a dimensional control element 308 may be disposed against the circular body 218 of the aluminum center plate 212 radially inward from the radial edge 286 of the annular body 236 of the steel ring gear 214 to counteract the pressure applied axially against the circular body 218 and to prevent distortion of the circular body 218.

[0031] In all the embodiments described above, the contact surfaces of the annular body 36, 136, 236 of the steel ring gear 14, 114, 214 and the periphery 24, 124, 224 of the circular body 18, 118, 218 of the aluminum center plate 12, 112, 212, which are rotated relative to each other and then pressed together to form the solid-state connection 16, 116, 216, are considered to be parallel (surfaces 44, 50 in Fig. 5, areas 144, 150 in Fig. 8 and areas 244, 296 in Fig. 10) or vertically (surfaces 170, 172 in Fig. 8 and areas 294, 298 in Fig. 10) to the rotational axis 22 of the manufactured composite metal flex plate 10, 110, 210. Although this is certainly acceptable and can be practiced, other interface configurations are also possible. For example, and with reference to Fig. 11, a generally annular body 336 of the steel ring gear and a generally periphery 324 of the circular body of the aluminum center plate are shown with respect to a rotational axis 322 extending longitudinally through the center plate's central opening. Surface 335 of the annular body 336 is intended to collectively represent the inner surfaces 44, 144, 244 of the above-described annular bodies 36, 136, 236, and surface 325 of the periphery 324 of the circular body is intended to collectively represent the outer surfaces 50, 150 of the axial rim 126, 226 and the peripheral edge surface 296 of the circular body 218, as described above. As shown, the surface 335 of the annular body 336 may be inclined relative to the rotation axis 322 by an inclination angle α, and similarly, the surface 325 of the circumference 324 of the circular body may be inclined relative to the rotation axis 322 by an inclination angle β.

[0032] Separately and with reference now to Fig. 12, a generally annular body 436 of the steel ring gear and a generally periphery 424 of the circular body of the aluminum center plate are illustrated. Surface 437 of the annular body 436 is intended to collectively represent the side surface 170 of the annular body 136 and the front surface 294 of the radial rim 286 described above, and surface 427 of the periphery 424 of the circular body is intended to collectively represent the front surface 172 of the radial rim 162 and the rear surface 298 of the circular body 218, as described above. As shown, the surface 437 of the annular body 436 may be inclined relative to a plane 431 perpendicular to the rotation axis 422 by an inclination angle θ, and likewise the surface 427 of the circumference 424 of the circular body may be inclined relative to the plane 431 perpendicular to the rotation axis 422 by an inclination angle γ.Each of the inclination angles α, β, θ, γ can independently be greater than 0° and, if implemented, can be between 10° and 80° or more narrowly between 30° and 60°.

[0033] The inclination angles α, β, θ, γ can be used to increase the area between the surface 335, 437 of the annular body 336, 436 and the surface 325, 427 of the circumference 324, 424 of the circular body when these surfaces 325, 335 and 427, 437 are pressed and forged together during the pressure application step. In this way, a more extensive solid-state connection can be created, which can result in a stronger and more robust connection. For this purpose, when the inclination angles α, β are adjusted to improve the connection area, the surface 335 of the annular body 336 and the surface 325 of the circumference 324 of the circular body are inclined in the same direction relative to the rotation axis 322 to maintain an opposing relationship, as shown in Fig. 11, wherein their respective inclination angles α are equal to or different from each other by up to 15°. The same general conditions apply when the inclination angles θ, γ are adjusted to improve the connection area; that is, the surface 437 of the annular body 436 and the surface 427 of the circumference 424 of the circular body are inclined in the same direction as the plane 431 perpendicular to the rotation axis 422 to maintain an opposing relationship, as in Fig. 12, where their respective inclination angles θ, γ are equal or differ by up to 15°.

[0034] The above description of the preferred exemplary embodiments and specific examples are merely descriptive; they are not intended to limit the scope of the following claims. Each term used in the appended claims should be interpreted in its ordinary and generic sense unless expressly and clearly stated otherwise in the specification.

Claims

[1] Composite metal flex plate, comprising: an aluminum center plate (12, 112, 212) having a circular body (18, 118, 218) defining a central opening about an axis of rotation of the composite metal flex plate, the circular body (18, 118, 218) having a perimeter (24, 124, 224, 324, 424); and a steel ring gear (14, 114, 214) including an annular body (36, 136, 236, 336, 436) and external teeth formed integrally with and disposed around the annular body (36, 136, 236, 336, 436), wherein the annular body (36, 136, 236, 336, 436) of the steel ring gear (14, 114, 214) is secured to the periphery (24, 124, 224, 324, 424) of the circular body (18, 118, 218) of the aluminum center plate (12, 112, 212) by a solid-state connection (16, 116, 216), wherein the periphery (24, 124, 224, 324, 424) of the circular body (18, 118, 218) of the aluminum center plate (12, 112, 212) comprises an axial edge (26, 126, 226) extending axially from a distal end of the circular body (18, 118, 218), the axial edge (26, 126, 226) being inclined by an angle (β) of 10° to 80° to the axis of rotation, and wherein the solid-state connection (16, 116, 216) is formed between the axial edge (26, 126, 226) of the circular body (18, 118, 218) and a surface inclined by an angle (α) of between 10° to 80° to the axis of rotation (335) of the annular body (36, 136, 236, 336, 436) of the steel ring gear (14, 114, 214). [2] The composite metal flexplate of claim 1, wherein the periphery (24, 124, 224, 324, 424) of the circular body (18, 118, 218) includes an axial edge (26, 126, 226) extending axially from a distal end of the circular body (18, 118, 218) and further comprising a radial edge (162, 286) extending radially outwardly from the axial edge (26, 126, 226) and axially offset from the distal end of the circular body (18, 118, 218), and wherein the solid-state connection (16, 116, 216) is formed between at least one of the axial edge (26, 126, 226) or the radial edge (162, 286) of the circular body (18, 118, 218) of the aluminum center plate (12, 112, 212) and the annular body (36, 136, 236, 336, 436) of the steel ring gear (14, 114, 214). [3] The composite metal flexplate of claim 1, wherein the annular body (36, 136, 236, 336, 436) of the steel ring gear (14, 114, 214) comprises an annular main portion and a radial rim (162, 286) extending radially inward from the annular main portion, and wherein the solid-state connection (16, 116, 216) is made between the circular body (18, 118, 218) of the aluminum center plate (12, 112, 212) and at least one of the annular main portion or the radial rim (162, 286) of the annular body (36, 136, 236, 336, 436) of the steel ring gear (14, 114, 214). [4] A method of manufacturing a composite metal flex plate, the method comprising: Heating a surface (335) of an annular body (36, 136, 236, 336, 436) of a steel ring gear (14, 114, 214); Bringing the surface (335) of the annular body (36, 136, 236, 336, 436) of the steel ring gear (14, 114, 214) into contact with a surface of a circumference (24, 124, 224, 324, 424) of a circular body (18, 118, 218) of the aluminum center plate (12, 112, 212) while the surface (335) of the annular body (36, 136, 236, 336, 436) of the steel ring gear (14, 114, 214) is still heated; Rotating one of the aluminum center plate (12, 112, 212) or the steel ring gear (14, 114, 214) while the other aluminum center plate (12, 112, 212) or the other steel ring gear (14, 114, 214) remains stationary to generate frictional heat between the contact surfaces of the annular body (36, 136, 236, 336, 436) of the steel tube gear and the periphery (24, 124, 224, 324, 424) of the circular body (18, 118, 218) of the aluminum center plate (12, 112, 212), wherein the generated frictional heat heats adjacent softened regions in the annular body (36, 136, 236, 336, 436) of the steel ring gear (14, 114, 214) and the circular body (18, 118, 218) of the aluminum center plate (12, 112, 212); and Applying a force to the contact surfaces of the annular body (36, 136, 236, 336, 436) of the steel ring gear (14, 114, 214) and the circumference (24, 124, 224, 324, 424) of the circular body (18, 118, 218) of the aluminum center plate (12, 112, 212) in order to plastically deform the softened areas and the contact surfaces of the annular body (36, 136, 236, 336, 436) of the steel ring gear (14, 114, 214) and the circumference (24, 124, 224, 324, 424) of the circular body (18, 118, 218) of the aluminum center plate (12, 112, 212) together to form a solid connection (16, 116, 216) upon cooling and hardening of the softened areas wherein the periphery (24, 124, 224, 324, 424) of the circular body (18, 118, 218) of the aluminum center plate (12, 112, 212) includes an axial edge (26, 126, 226) extending axially from a distal end of the circular body (18, 118, 218), the axial edge (26, 126, 226) being inclined at an angle (β) of 10° to 80° to the axis of rotation, the axial edge (26, 126, 226) having an outer surface which is inclined at an angle (α) between 10° to 80° to the axis of rotation, an inner surface (335) of the annular body (36, 136, 236, 336, 436) of the steel ring gear (14, 114, 214), and wherein rotation of either the aluminum center plate (12, 112, 212) or the steel ring gear (14, 114, 214) results in relative contact rotational movement between the outer surface of the axial rim (26, 126, 226) and the inner surface of the annular body (36, 136, 236, 336, 436) of the steel ring gear (14, 114, 214) to generate frictional heat therebetween. [5] The method of claim 4, wherein the periphery (24, 124, 224, 324, 424) of the circular body of the aluminum center plate (12, 112, 212) has a radial edge (162, 286) extending radially outwardly from the axial edge (26, 126, 226) and axially offset from the distal end of the circular body (18, 118, 218), and wherein rotating the aluminum center plate (12, 112, 212) or the steel ring gear (14, 114, 214) results in relative contact rotation between at least one of (1) an outer surface of the axial edge (26, 126, 226) and an inner surface of the annular body (36, 136, 236, 336, 436) of the steel ring gear (14, 114, 214) to generate frictional heat therebetween, or (2) a front surface of the radial edge (162, 286) and a side surface of the annular body (36, 136, 236, 336, 436) of the steel ring gear (14, 114, 214) to generate frictional heat therebetween. [6] The method of claim 4, wherein the annular body (36, 136, 236, 336, 436) and the steel ring gear (14, 114, 214) have an annular main portion and a radial rim (162, 286) extending radially inward from the annular main portion, and wherein rotating one of the aluminum center plates (12, 112, 212) or the steel ring gear (14, 114, 214) results in relative contact rotational movement between at least one of (1) a rear surface of an annular terminal portion of the annular body (36, 136, 236, 336, 436) of the aluminum center plate (12, 112, 212) and a front surface of the radial rim (162, 286) of the annular body (36, 136, 236, 336, 436) of the steel ring gear (14, 114, 214) to generate frictional heat therebetween or (2) an inner surface of the annular main portion of the annular body (36, 136, 236, 336, 436) of the steel ring gear (14, 114,214) and a peripheral edge surface of the distal end of the circular body (18, 118, 218) of the aluminum center plate (12, 112, 212) to generate frictional heat therebetween. [7] The method of claim 4, wherein a dimensional control element is disposed against a surface of the circular body (18, 118, 218) of the aluminum center plate (12, 112, 212) to resist distortion of the circular body (18, 118, 218) when the force is applied that plastically deforms the softened regions and forges together the contact surfaces of the annular body of the steel ring gear (14, 114, 214) and the periphery (24, 124, 224, 324, 424) of the circular body (18, 118, 218) of the aluminum center plate (12, 112, 212). [8] A method of manufacturing a composite metal flex plate, the method comprising: Providing a steel ring gear (14, 114, 214) including an annular body (36, 136, 236, 336, 436) and external teeth arranged integrally and circumferentially with the annular body (36, 136, 236, 336, 436); Providing an aluminum center plate (12, 112, 212) having a circular body (18, 118, 218) with a perimeter (24, 124, 224, 324, 424), the circular body (18, 118, 218) defining a central opening, a first set of mounting holes proximate the central opening, and a second set of mounting holes proximate the perimeter (24, 124, 224, 324, 424); Heating a surface (335) of the annular body (36, 136, 236, 336, 436) of the steel ring gear (14, 114, 214) to a temperature above 200°C; Rotating the surface (335) of the annular body (36, 136, 236, 336, 436) of the steel ring gear (14, 114, 214) and a surface of the circumference (24, 124, 224, 324, 424) of the circular body (18, 118, 218) of the aluminum center plate (12, 112, 212) relative to each other while the surfaces are in contact with each other and the temperature of the surface (335) of the annular body is between 200° C and 580° C, wherein either the steel ring gear (14, 114, 214) or the aluminum center plate (12, 112, 212) is held stationary in order to generate frictional heat between the surfaces (335) of the annular body of the steel ring gear (14, 114, 214) and the circumference (24, 124, 224, 324, 424) of the circular body (18, 118, 218) of the aluminum center plate (12, 112, 212), wherein the generated frictional heat is distributed adjacent to the softened areas in the annular body (36, 136, 236, 336, 436) of the steel ring gear (14, 114, 214) and the circular body (18, 118, 218) of the aluminum center plate (12, 112,212), wherein the circumference (24, 124, 224, 324, 424) of the circular body (18, 118, 218) of the aluminum center plate (12, 112, 212) includes an axial edge (26, 126, 226) extending axially from a distal end of the circular body (18, 118, 218), the axial edge (26, 126, 226) being inclined by an angle (β) of 10° to 80° to the axis of rotation, the axial edge (26, 126, 226) having an outer surface which is inclined by an angle (α) between 10° to 80° to the axis of rotation, 436) of the steel ring gear (14, 114, 214);, Applying a force to the surfaces (335) of the annular body (36, 136, 236, 336, 436) of the steel ring gear (14, 114, 214) and the circumference (24, 124, 224, 324, 424) of the circular body (18, 118, 218) of the aluminum center plate (12, 112, 212) that are in contact with each other to plastically deform the adjacent softened areas and to soften the surfaces (335) of the annular body (36, 136, 236, 336, 436) of the steel ring gear (14, 114, 214) and the circumference (24, 124, 224, 324, 424) of the circular body (18, 118, 218) of the aluminum center plate (12, 112, 212) together to form a solid-state joint (16, 116, 216) upon cooling and hardening of the softened areas.

Images