Patent Publication Number: US-2018036791-A1

Title: Tool and method for forming surface features onto a workpiece

Description:
TECHNICAL FIELD 
     The present disclosure relates an apparatus and a method for forming surface features (e.g., a series of teeth and/or grooves) into an annular, external surface of a gear. 
     BACKGROUND 
     Automatic transmissions, torque converters, and the like have many parts with intricate surface features. For example, a planetary gearset may include gears or carriers that have a series of repeating grooves and teeth on the outer surface of the part. It is known to form the grooves of these parts by utilizing one or more rollers. 
     For example, DE102010019522 discloses a device that has an external profile including a lower die accommodating a cup-shaped blank on an arbor. The profile has an upper die that is axially adjustable opposite to the lower die, wherein the upper die has multiple rollers that are arranged over the circumference of the blank. The profile rollers are accommodated in a retaining ring that is formed from two ring parts, which are designed complementary to each other. 
     SUMMARY 
     In one embodiment, a tool for forming an annular workpiece is provided. The tool includes one or more inner form members defining a perimeter. The tool also includes a plurality of outer form members collectively disposed in an annular shape about a central axis and radially outward from the perimeter. Each outer form member has an inner surface facing the inner form member and an opposing outer surface. Each inner surface defines a surface feature for forming a corresponding outer surface feature onto the workpiece. The tool also includes a driver member configured to translate along the axis to cause the outer form members to move radially inward toward the workpiece to form the outer surface features onto the workpiece. 
     Each outer surface of the outer form members may be tapered with respect to the central axis, and the driver member may include an inner surface of the driver member is tapered with respect to the central axis. The inner surface of the driver member may slide along the outer surfaces of the outer form members to force the outer form members to move radially inward toward the workpiece to press-form the surface features onto the workpiece. 
     The perimeter or outer surface of the inner form member may define a series of surface features for forming corresponding inner surface features onto the workpiece. 
     The one or more outer form members may be a single cylindrical inner form member. Alternatively, the one or more outer form members may be a plurality of inner form members that collectively define the perimeter. 
     In another embodiment, a method of forming an annular workpiece includes locating the annular workpiece between a generally cylindrical inner form member and a plurality of outer form members, each outer form member being disposed on a support and having an outer surface. The method also includes driving a driver member toward the support and against the outer surfaces to force the outer form members to slide along the support and press against the annular workpiece. 
     In another embodiment, a system for forming a gear includes a support, and a plurality of outer form members supported by the support and arranged annularly about a central axis. The outer form members are configured to move toward and away from the central axis along the support. Each outer form member is biased away from the central axis. A driver is selectively engaged with at least one of the outer form members. Movement of the driver toward the support presses the outer form member toward the central axis to form an outer surface of the gear. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a partial perspective view of a tool in a closed position, or use position, in which the tool is forming teeth onto a gear, according to one embodiment. 
         FIG. 2  is a partial perspective view of the tool in an open position, or non-use position, in which the tool is not forming teeth onto a gear. 
         FIG. 3  is a perspective view of the tool with various components now shown in their entirety. 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments of the present disclosure are described herein. It is to be understood, however, that the disclosed embodiments are merely examples and other embodiments can take various and alternative forms. The figures are not necessarily to scale; some features could be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the embodiments. As those of ordinary skill in the art will understand, various features illustrated and described with reference to any one of the figures can be combined with features illustrated in one or more other figures to produce embodiments that are not explicitly illustrated or described. The combinations of features illustrated provide representative embodiments for typical applications. Various combinations and modifications of the features consistent with the teachings of this disclosure, however, could be desired for particular applications or implementations. 
     It should be understood that references to directions (e.g., “downward,” “upward,” “inward,” “outward,” “inner,” “outer,” etc.) are intended to describe the embodiments of a tool and gear in their orientation shown in the figures. These terms are meant to be interpreted in light of the position of the tool and gear as shown in their particular arrangement and orientation in the Figures. For example, while a driver is described below as driving “downward,” this term is intended to mean “downward when oriented as shown in the figures,” as it should be understood that the tool may take other orientations (e.g., angled, upside-down, etc.) when actually used to form the gear. Also, the terms “inner” and “outer” are meant to be taken with respect to a central axis of the tool. 
     According to one or more embodiments of this disclosure, a tool, system and method for forming a toothed gear is provided. The teeth on the gear are press-formed into the gear&#39;s surfaces in a linear direction, as opposed to roll-forming in which the roll-forming tool rolls across the surface. 
       FIG. 1  shows a tool  10  for press-forming teeth on the gear  12 . In  FIG. 1 , the tool  10  is shown in a use position in which the teeth are being formed onto the surfaces of the gear  12 . In  FIG. 2 , the tool  10  is shown in an open, unused position in which the gear is nor forming the teeth on the gear. The gear is not shown in  FIG. 2  to provide a clearer view of the tool  10 . 
     The tool  10  includes a support  20 , a driver  30 , a plurality of outer form member  40 , and an inner form member  50 . These components, as well as the gear  12 , may share a common central axis (not shown). These components work together to press outer teeth  14  and inner teeth  16  onto the surfaces of the gear  12 . The support  20 , the driver  30 , and the inner form member  50  extend in a circle entirely about the gear  12 , but in  FIGS. 1-2  these components are only shown in part for illustrative purposes; the components are shown in their entirety in  FIG. 3 . Furthermore, while only one outer form member  40  is shown in the Figures, it should be understood that this is only for illustrative purposes as well; a plurality of the outer form members  40  extend about the gear  12 . In one embodiment, the number of outer form members  40  corresponds to the number of outer teeth  14  on the gear. 
     The tool  10  operates to form teeth on the gear  12  as follows. The gear  12  is placed on the support  20  or some other underlying surface (not shown). To initiate the forming process, the driver  30  is driven or pressed downward by hydraulics, for example. As the driver  30  is driven downward, the driver  30  engages the outer form members  40  to force the outer form members  40  along in the support  20  in an inward direction toward the gear  12 . When driven further, the driver  30  forces the outer form members  40  further inward to press against the gear  12 . The gear  12  is pressed between the outer form members  40  and the inner form member  50 , with each member  40 ,  50  being provided with surface features to form corresponding outer teeth  14  and inner teeth  16  onto the gear  12 . 
     The support  20  has a generally planar upper surface  22 . The upper surface  22  may be provided with tracks or grooves that extend radially outward from the central axis. These tracks or grooves guide the outer form members  40  inward and outward when they are forced inward and outward by the driver  30 . The lower surfaces of the outer form members  40  may each have a corresponding protrusion that fits within one of the tracks or grooves. In another embodiment, the upper surface  22  may be provided with radially-extending protrusions that each fit within a corresponding groove or track on the bottom surface of a respective one of the outer form members  40 . The interaction of the grooves or tracks with the protrusions is but one example of allowing a slideable coupling between the outer form members  40  and the support  20 . 
     The driver  30  can move downward toward the support  20  and upward away from the support  20  to selectively press and release the outer form members  40  from the gear  12 . The driver  30  includes an inner surface  32  that faces toward the central axis. In one embodiment, the inner surface  32  is tapered with respect to the central axis such that the top of the inner surface  32  is closer to the central axis than the bottom of the inner surface  32 . As shown in  FIG. 3 , the inner surface  32  may take a frustroconical shape. 
     The outer form members  40  have corresponding outer surfaces  42  that engage the driver  30  as the driver is driven. The outer surface  42  of each outer form member  40  is tapered with respect to the central axis such that the top of the outer surface  42  is closer to the central axis than the bottom of the inner surface  32 . The shape of the outer surface  42  of each outer form member  40  corresponds with the shape of the inner surface  32  of the driver  30 . In one embodiment, the surfaces  32 ,  42  engage in a face-to-face relationship when the driver is driven to assure a smooth linear movement of the outer form members  40  toward the central axis. 
     When the driver is in a non-use or open position (e.g.,  FIG. 2 ), the driver is spaced from the outer form members  40  and does not directly engage the outer form members  40 . When the driver  30  is driven, the inner surface  32  of the driver engages the outer surfaces  42  of the outer form members  40 . The tapered surfaces transfer downward movement of the driver  30  into radial movement (i.e., toward the gear  12 ) of each of the outer form members  40 , as described above. 
     Each outer form member also includes an inner surface  44  that is provided with surface features  46 . In one embodiment, the surface features  46  are in the desired shape of the outer teeth  14  on the gear. As the outer form members  40  are pressed toward and onto the gear  12 , the surface features  46  presses against the outer surface of the gear  12 , forming the outer teeth  14 . 
     In an embodiment in which inner teeth  16  are formed onto the gear  12 , the inner form member  50  includes an outer surface  52  with a plurality of surface features  54 . These surface features  54  are in the desired shape of the inner teeth  16 . The outer surface  52  and the surface features  54  provide a resisting force against the radially-inward pressing force from the outer form members  40 . Therefore, when the driver  30  presses the outer form members  40  against the gear  12 , both the outer teeth  14  and the inner teeth  16  can be formed simultaneously. 
     A method of forming an annular workpiece, such as a gear  12 , can be accomplished using the tool described above. In one embodiment, the gear  12  is placed between the generally cylindrical inner form member  50  and the plurality of outer form members  40 . Each outer form member  40  is slideably disposed on the support  20 . The driver  30  is driven toward the support and against the outer surfaces  42  of the outer form members  40 . This forces the outer form members  40  to slide along the support and press against the gear  12 . The outer form members  40  can be spaced from one another, but can collectively define a perimeter or circumference that is adjustable in size by way of driving the driver  30  up and down. 
     It should be understood that the gear  12  described above can be one of many types of gears, such as a ring gear, a carrier, a sun gear, etc. Many different types of gears are known to exist in a transmission or torque converter of a vehicle, and the tool and forming system disclosed above can be implemented on any type of gear. If a particular gear being formed is intended to have no inner teeth, then the inner form member  50  can be designed to have no outer surface features. Likewise, if the particular gear being formed is intended to have no outer teeth, then the outer form members  40  can be designed to have no inner surface features. 
     Utilizing the tool of this disclosure, as opposed to conventional roll-forming of the gears, reduces the amount of moving parts. This reduces the opportunity for damage done to the parts. The amount of rotating parts during roll-forming is more costly to maintain as compared to the forming of this disclosure. 
     It should be understood that relative terms such as “generally,” as in a “generally cylindrical inner form member” can include surface features, bumps or grooves on the outer surfaces, but one of skill in the art would still recognize the member as being overall “generally” cylindrical. 
     While exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms encompassed by the claims. The words used in the specification are words of description rather than limitation, and it is understood that various changes can be made without departing from the spirit and scope of the disclosure. As previously described, the features of various embodiments can be combined to form further embodiments of the invention that may not be explicitly described or illustrated. While various embodiments could have been described as providing advantages or being preferred over other embodiments or prior art implementations with respect to one or more desired characteristics, those of ordinary skill in the art recognize that one or more features or characteristics can be compromised to achieve desired overall system attributes, which depend on the specific application and implementation. These attributes can include, but are not limited to cost, strength, durability, life cycle cost, marketability, appearance, packaging, size, serviceability, weight, manufacturability, ease of assembly, etc. As such, to the extent any embodiments are described as less desirable than other embodiments or prior art implementations with respect to one or more characteristics, these embodiments are not outside the scope of the disclosure and can be desirable for particular applications.