Abstract:
Disclosed is a process and method for forming tolerance rings. The process preferably is accomplished in a fully automated manner not requiring the manipulation of the product by human hands. The process preferably uses a fourslide tooling device and an assembly of pins to form a tolerance ring. The fourslide preferably is comprised of upper and lower tool sets for manipulating a flat strip of stock into a tolerance ring having overlapping ends and a plurality of dimple and/or bumps. Preferably the tolerance ring is formed without having to move a partially compressed tolerance ring from a first machine to a second machine.

Description:
RELATED APPLICATION  
       [0001]     This application claims priority to provisional application Ser. No. 60/507,883, filed Oct. 1, 2003, the entirety of which is hereby incorporated by reference. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The field relates to systems for forming manufacturing components. More specifically, the field is directed to the processing of tolerance rings for use in mechanical devices such as computer disk drives.  
         [0004]     2. Description of the Related Art  
         [0005]     Technology is a constantly changing field wherein processes are becoming faster and parts are becoming smaller. In all fields ranging from automobiles to computers, manufacturing companies increasingly rely on automated improvements to increase the throughput of their production processes. Current processes often involve time consuming procedures that slow the manufacturing of products and therefore result in a decline in the company&#39;s potential profit margins. Further, time consuming processes may involve unnecessary company expenditure of labor and machinery. For example, a production process may require a product to be transferred from one machine to a second machine for final preparation of the product. Such a system necessarily involves extra floor space for the second machine and an employee to move the product from the first machine to the next. Depending on the particular process, other potential drains to the company may exist: added power may be consumed by extra machines and downtime in the manufacturing process can be caused by required maintenance.  
       SUMMARY OF THE INVENTION  
       [0006]     Briefly stated, embodiments of the invention are directed towards a process and apparatus for producing formed metal objects in an improved and efficient manner. More specifically, in one embodiment, tolerance rings are produced through a process which lacks the need to manually alter the position of the tolerance ring during the manufacturing process. In other embodiments, the process uses a single machine to perform the entire manufacturing process. Preferably, the process uses a fourslide machine arranged in a stacked manner whereby partially completed products are transferred from an upper tool system to a lower tool system through the use of ejector pins and a nesting device.  
         [0007]     In one embodiment, a method of making a metallic ring is provided. This method comprises inserting a strip of metal into a first portion of a machine. In the first portion, the strip is shaped around a first pin having a first diameter. After shaping the strip around the first pin, the strip of metal is moved automatically into a second portion of the machine. In the second portion, the strip of metal is shaped around a second pin having a second diameter smaller than the first diameter. After shaping the strip around the second pin, the ring may be released from the machine.  
         [0008]     Preferably, in this method, the second portion is below the first portion. The strip of metal may be automatically moved from the first portion to the second portion by sliding the strip down the first pin having a first diameter. The strip may be shaped around the pins of each portion by sliding components that press the strip between surfaces of the sliding components and the pin. The sliding components may be found in a fourslide device. In another embodiment, a machine is provided that performs the method described above.  
         [0009]     In anther embodiment, a method for manufacturing a tolerance ring is provided. A piece of metal stock is placed having two ends adjacent a concave surface of a front cradle of an upper tool set. The front cradle is moved in the direction of a back cradle so that the metal stock at least partially compresses around a large pin, the large pin being located intermediate the front cradle and the back cradle in the upper tool set. The back cradle is moved in the direction of the front cradle such that a substantially tight fit is formed between the front cradle and back cradle, wherein the metal stock is compressed around the large pin, the piece of metal stock being formed into an at least partially compressed state. Compression is released around the large pin by moving the back cradle and front cradle in opposite directions to their original positions, while simultaneously a pressure pin makes contact with the piece of metal stock and maintains the metal stock in a fixed location on the large pin. A left nesting slide and a right nesting slide are moved in a direction approximately perpendicular to the direction traversed by the front cradle and back cradle, such that the left nesting slide and right nesting slide contact each other and close to form a nest at a vertical level below the level of the location of the upper tool set. The pressure pin is retracted from the metal stock and the large pin. The partially compressed stock is moved vertically downward, by use of ejectors, and into the nest below formed by the left nesting slide and the right nesting slide. A front tightener and a back tightener, of a lower tool set, are moved towards each other to come in contact with the partially compressed stock. The partially compressed stock is compressed, by use of the front tightener and the back tightener, around a relatively smaller pin than the large pin, the smaller pin connected to the back tightener, such that the partially compressed stock is compressed to a fully compressed state, wherein the two ends of the fully compressed stock partially overlap to form a complete circular shape. The smaller pin is moved in a horizontal direction away from the front tightener. The fully compressed stock is dropped from the small pin to a receptacle located below the lower tool set.  
         [0010]     In another embodiment, a method of forming a stock material is provided. A front cradle and a back cradle of a first tool set are moved to compress a piece of stock material around a large pin, the large pin located intermediate the front cradle and the back cradle, wherein the stock material forms an at least partially circular shape and is in a partially compressed state. The partially compressed stock automatically moves to a location between a front tightener and a back tightener of a second tool set. The partially compressed stock is compressed around a small pin with the front and back tighteners, the stock material forming a complete circular shape and being in a fully compressed state. The fully compressed stock is released from the small pin.  
         [0011]     In another embodiment, an apparatus for forming a piece of material is provided. An upper tool set, movable in a horizontal forward and backward direction, comprises a front cradle and a back cradle adapted to compress the piece of material around a large pin. A nest, movable in a horizontal left and right direction, comprises a left nesting slide and a right nesting slide, wherein the nest is located at a vertical level below the upper tool set. A lower tool set, movable in a horizontal forward and backward direction, comprises a front tightener and a back tightener, wherein the lower tool set is at a vertical level below the nest and the nesting slides are approximately perpendicular to the lower tool set, wherein the front and back tighteners are adapted to compress around a small pin, the small pin being smaller than the large pin. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]      FIG. 1  is a schematic view from overhead of an embodiment of the upper or top cradle tools.  
         [0013]      FIG. 2  is a schematic view of an embodiment of a stock unit after it is shaped by the front cradle around a large pin.  
         [0014]      FIG. 3  is a schematic side view of the embodiment of  FIG. 1 .  
         [0015]      FIG. 4  is a schematic view from overhead of the upper or top cradle tools with the nesting slides in position to hold a partially formed tolerance ring.  
         [0016]      FIG. 5  is a schematic view from overhead view of an embodiment of the lower or bottom cradle tools.  
         [0017]      FIG. 6  is a schematic side view of the embodiment of  FIG. 5 .  
         [0018]      FIG. 7  is a schematic view from overhead of an embodiment of the upper or top cradle tools, nesting slides, and lower cradle tools.  
         [0019]      FIG. 8  is a schematic side view of the embodiment of  FIG. 7 .  
         [0020]      FIG. 9  is a schematic view from overhead of the nesting slides.  
         [0021]      FIG. 10  is a schematic side view of the nesting slides and the large pin.  
         [0022]      FIG. 11  is a schematic view from overhead of an embodiment of the large pin and ejectors.  
         [0023]      FIG. 12  is a schematic side view of the embodiment of  FIG. 11 . 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0024]     Embodiments of the invention are directed towards forming manufacturing parts in a quick and efficient manner. The systems and procedures employed here may apply to a variety of shapes and materials. One of the embodiments is directed to forming tolerance rings; however, the invention can be used to form a variety of parts. Generally, the embodiments described below will be used for objects composed of metal; however, it is understood that the invention may be used with any suitable materials that may be readily transformed from one configuration to another.  
         [0025]     Tolerance rings are generally circular ring-like structures formed from a metal stock unit. In order to form a tolerance ring, the metal stock is rolled to a precise radial measurement so that it may perform in its corresponding mechanical and/or electrical component. For example, tolerance rings may be used in disk drives or automotive parts. Tolerance rings may be substantially circular strips of metal with a plurality of dimple and/or bumps located thereon. It will be appreciated that other types of parts may be formed in addition to tolerance rings. Preferably the apparatus and the process may be best understood with reference to the accompanying figures.  
         [0026]      FIG. 1  is an overhead view of the upper tool set  12  of an embodiment of a fourslide device  10 . The upper tool set  12  is comprised of a front cradle  14  and a back cradle  16 . Between the two cradles  14 ,  16  lies a large pin  18  for shaping the stock  20 . Preferably a plurality of bumps and/or dimples (not shown) is formed on the stock  20  before the stock  20  enters the fourslide device  10 . The stock  20  may be composed of various shapes but for exemplifying purposes, the stock  20  discussed herein is a rectangular strip. The large pin  18  of the embodiment is shown to be generally circular. The large pin  18  may have various alternative cross-sectional shapes including but not limited to geometric configurations. Further, the large pin  18  of the embodiment shown has a substantially smooth surface. In other embodiments, it may be preferable for the large pin  18  to have a pattern located thereon to add shape to the stock  20  upon compression around the large pin  18 . For example, in some embodiments, the large pin  18  may have a plurality of dimples or bumps located thereon.  
         [0027]     With continued reference to  FIG. 1 , the front cradle  14  moves the stock  20  around the large pin  18  to give it a substantially U-shaped  22  structure (as shown in  FIG. 2 ). The front cradle  14  has a generally concave surface  24  substantially corresponding to the curvature of the large pin  18 . The concave surface  24  of the front cradle  14  further contains two adjacent edges  26  that are substantially straight. The concave surface  24  of the front cradle  14  is generally smooth in the disclosed embodiment, however, like the large pin  18 , may have a pattern located thereon to further add shape to the stock  20  upon compression around the large pin  18 . In some embodiments, the concave surface  24  is smooth while only the large pin  18  has a pattern. Likewise, in other embodiments, the large pin  18  may have a smooth surface while the concave surface  24  has a pattern located thereon. Further, both the large pin  18  and the concave surface  24  may have patterns located thereon.  
         [0028]     After the front cradle  14  has compressed the stock  20  around the large pin  18 , the back cradle  16  closes to form a tight fit with the large pin  18  and the front cradle  14 . The back cradle  16  and the front cradle  14  compress the stock  20  around the large pin  18  to give the stock  20  a shape generally matching that of the accompanying large pin  18 . In some embodiments, the back cradle  16  may begin to move towards the large pin  18  simultaneously with the front cradle  14 . In other embodiments, the back cradle  16  may move towards the large pin  18  before the front cradle  14  begins to move. Still, in other embodiments, one or more of the cradles  14 ,  16  may remain stationary while the large pin  18  moves the stock  20  to and from the cradles  14 ,  16 . The back cradle  16  of the disclosed embodiment has a concave upper surface  24  generally matching the shape of the large pin  18 . The back cradle  16  has straight edges  26  lying adjacent to the upper concave surface  24 , which are configured to receive the straight edges  26  of the front cradle  14 . Upon compression of the stock  20  around the large pin  18  by both cradles  14 ,  16 , the stock  20  thereafter obtains a shape similar to that of the large pin  18 . The cradles  14 ,  16  later retract from the large pin  18  to their original positions. Subsequently, due to the natural elasticity of the stock  20 , the stock  20  may expand to form a shape having a larger diameter than that of the large pin  18 .  
         [0029]     The diameter of stock  20  is meant to refer to the measurement of one location  28  on the stock  20  to a location  30  directly opposite the first location  28 . The term diameter is generally meant to have the same definition as would be normally applied to a circle. The same basis for measuring points should likewise apply here even though the partially compressed stock  20  may not form a complete circle. Here, the stock  20  assumes a shape such that no overlap between ends  32  of the stock  20  exists. In other embodiments the partially compressed state may have the ends  32  of the stock  20  touching. In other embodiments, the ends  32  may overlap each other in the partially compressed state.  
         [0030]     In one embodiment, it is preferred that the cradles  14 ,  16  compress the large pin  18  at a force of about 19-90 lbs. per square inch. In a preferred embodiment, the amount of pressure exerted is measured at about 50 lbs. per square inch. In the embodiments in which one or more of the cradles  14 ,  16  remain stationary, the large pin  18  retracts to its original position and away from the cradles  14 ,  16  to allow the stock  20  to relax to its partially compressed state.  
         [0031]      FIG. 3  shows a side view of  FIG. 1 . After the two cradles  14 ,  16  compress the stock  20  around the large pin  18 , the cradles  14 ,  16  return to their original retracted positions. Upon release by the cradles  14 ,  16 , the stock  20  may partially spring back to its original position due to the internal tension of the stock  20 . A pressure pin  36  may be located on the front cradle  14  to hold the stock  20  against the large pin  18  in a substantially fixed manner. The pressure pin  36  ensures that the stock  20  retains its new shape while waiting to move to the next step in one embodiment of the process. The pressure pin  36  may be retracted to release the stock  20 .  
         [0032]      FIG. 4  shows a nesting level  38 . The nesting level  38  is composed of a left slide  40  and right slide  42 . The nesting level  38  is generally located beneath the upper or top tool set  12 . When the cradles  14 ,  16  and pressure pin  36  retract, a pair of slides  40 ,  42  move into place to receive the partially compressed stock  20 . The left slide  40  and right slide  42  close to form a nest  44  for the partially compressed stock  20 . Upon release of the partially compressed stock  20  by the cradles  14 ,  16  and pressure pin  36 , one or more ejectors  46  may push the partially compressed stock  20  off of the large pin  18  and into the nest  44 . The ejectors, with three shown in the illustrated embodiment, may be metal strips provided as part of the upper tool set that slide along the surface of the large pin. Upon retraction of the cradles  14 ,  16 , the partially compressed stock  20  thereafter descends down the length of the large pin  18  and into the nest  44  waiting below. The nest  44  temporarily holds the partially compressed stock  20  before the lower or bottom tool set  48  moves into place. (Shown in  FIGS. 5-6 ).  
         [0033]      FIG. 5  is a top view of the lower tool set  48 . The lower tool set  48  is composed of a back tightener  50  and a front tightener  52 . The tighteners  50 ,  52  resemble the configuration of the cradles  14 ,  16  of the upper tool set  12 . The tighteners  50 ,  52  of the embodiment generally differ from the upper tool set  12  in that they each have a smaller concave surface  54  area than the cradles  14 ,  16 . The tighteners  50 ,  52  of the lower tool set  48  may have the same patterned surface and operation of the upper tool set  12 . In a preferred embodiment the back tightener  50  and front tightener  52  move simultaneously to close around the partially compressed stock  20 . A small pin  56  is preferably attached on the upper surface of the back tightener  50 . The small pin  56  may alternatively be attached to the front tightener  52 . In one embodiment, the small pin  56  has a smaller diameter than that of the large pin  18 . In some embodiments, the diameter of the small pin  56  may be equal to that of the large pin  18 . The tighteners  50 ,  52  further compress the partially compressed stock  20  to a fully compressed state thus creating a final product. In the disclosed embodiment, the ends  32  of the fully compressed stock  20  partially overlap to form a complete circle. In other embodiments, the ends  32  of the fully compressed stock  20  may not overlap at all. In other embodiments, more than two tool sets  12 ,  48  may be used to create a final product.  
         [0034]      FIG. 6  is a side view of the embodiment of  FIG. 5 . Below the small pin  56  lies a support surface  60 , that may be bolted to a table. After the partially compressed stock  20  is completely compressed around the small pin  56 , it becomes a fully compressed stock  20  which substantially encloses the small pin  56 . The small pin  56  may be connected to the back tightener  50  such that the back tightener  50  is able to pull the small pin  56  laterally away from the large pin  18  and the support surface  60 . The back tightener  50  preferably pulls the small pin  56  away from the support surface  60  by holding an upper portion  62  of the small pin  56 . The upper portion  62  of the small pin  56  preferably lies above the upper edge  64  of the fully compressed stock  20 . As the small pin  56  is moved away from the large pin  18  and the support surface  60 , the fully compressed stock  20  is able to drop from the small pin  56  and into a supply bucket or other suitable receptacle below (not shown) for holding completed products. Alternatively, ejectors may be used as described above to cause the stock  20  to descend from the small pin  56 .  
         [0035]      FIG. 7  shows an overhead view of a fourslide device  10 . The fourslide device  10  is comprised of an upper tool set  12 , a left slide  40 , a right slide  42 , and a lower tool set  48  operating in combination with each other. In this embodiment, the upper tools  12  are located directly above the lower tools  48  while the slides  40 ,  42  are stationed approximately perpendicular to and on the same level as the lower tools  48 . In other embodiments, the upper and lower tools  12 ,  48  may not be in direct alignment with each other. Further, in some embodiments, the slides  40 ,  42  may not lie perpendicular to or on the same level as the lower tools  48 . Some embodiments may use more than two levels. For example, one embodiment may have a third level consisting of another nesting level or another set of tools.  
         [0036]      FIG. 8  is a side view of the embodiment of  FIG. 7  (support surface  60  not shown). The upper tool set  12  is located above the lower tool set  48 .  
         [0037]      FIG. 9  shows an overhead view of the left slide  40  and the right slide  42 . In one embodiment the partially compressed stock  34  is formed around the large pin  18 . When the pressure pin  36  (not shown) retracts from the partially compressed stock  34 , one or more ejectors  46  descend down the large pin  18  to force the partially compressed stock  34  into the nest  44  below. In one embodiment three ejectors are used to position the partially compressed stock  34  securely in the nest  44 .  
         [0038]      FIG. 10  shows a side view of the embodiment shown in  FIG. 9 .  
         [0039]      FIG. 11  shows an overhead view of an embodiment of a large pin  18  having a plurality of ejectors  46  for forcing the partially compressed stock  20  off of the large pin  18  and into the nest  44  below (not shown).  
         [0040]      FIG. 12  is a side view of the embodiment show in  FIG. 11 . An ejector  46  is shown contacting an edge of the partially formed stock  20  to force it off of the large pin  18 .  
         [0041]     Although this invention has been disclosed in the context of certain preferred embodiments and examples, it will be understood by those skilled in the art that the present invention extends beyond the specifically disclosed embodiments to other alternative embodiments and/or uses of the invention and obvious modifications and equivalents thereof. In addition, while a number of variations of the invention have been shown and described in detail, other modifications, which are within the scope of this invention, will be readily apparent to those of skill in the art based upon this disclosure. It is also contemplated that various combination or subcombinations of the specific features and aspects of the embodiments may be made and still fall within the scope of the invention. Accordingly, it should be understood that various features and aspects of the disclosed embodiments can be combined with or substituted for one another in order to form varying modes of the disclosed invention. Thus, it is intended that the scope of the present invention herein disclosed should not be limited by the particular disclosed embodiments described above.