Patent Publication Number: US-2007101568-A1

Title: Method for improved fixture design

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
      This application claims the benefit of U.S. Provisional Application No. 60/733,723, filed Nov. 4, 2005. 
    
    
     FIELD OF THE INVENTION  
      The present invention is related to building fixtures used in the creation of prototype components to aid in product development.  
     BACKGROUND OF THE INVENTION  
      It is common practice in almost all areas of manufacturing to develop prototype components which are tested to ensure the components are ready for production and can be released into the marketplace. Larger manufacturing companies, particularly in the automotive industry, often work with suppliers in developing prototype components which will eventually be used in production. The steps in the product development process typically involve the design of the component, the creation of prototype parts, and the testing of the prototype parts to determine what changes, if any, in design are necessary. Because this process involves making the prototype parts for the first time, this process often involves the creation of tooling, or fixtures. The fixtures are then used to align components of the prototype parts for final assembly or post assembly processes, such as tolerance inspections.  
      One type of part that is commonly developed using this type of process is a door panel. The initial design of the door panel can be done using Computer Aided Design (CAD) software, ProE, or some other type of computer software having the capability to design the part. Fixtures are then created to build the prototype of the door panel, and the door panel can then be tested to determine if it will be suitable for production.  
      However, also common to the manufacturing industry is the problem that creating fixtures to build prototype parts is time consuming. Current methods of fixture construction are labor intensive and require a significant amount of man-power in the form of skilled workers. Because of this, turnaround times are high. Also, the results achieved by the current fixture design process are often of poor quality, and do not always meet the increasingly more demanding dimensional requirements. As products become more sophisticated, the tolerances allowed for the various dimensions of the components become more restrictive, and current methods of fixture design often do not meet these requirements.  
      Accordingly, there exists a need for an improved method of fixture design which reduces the time involved in creating the fixture itself, while at the same time improving the quality of the prototype part made from the fixture.  
     SUMMARY OF THE INVENTION  
      The present invention is a method for creating fixtures used in the build of prototype parts, including a base plate having various holes and notches with various details mounted onto the base plate, and wherein the various details are used to support a prototype part, and the prototype part is created by using the fixture. The method comprises the steps of first using a milling or other process for producing a base plate having the predetermined precisely located holes and notches. An electrical discharge machining process is used to create the various details. The details are then assembled onto the base plate to create a predetermined fixture. The fixture is then used to create the prototype part.  
      The notches on the base plate are T-shaped notches, and the details have protrusions which are received by the notches of the base plate for holding the details in place. The details also have recesses and projections which allow the details to interconnect with one another, simplifying the assembly of the fixture. The details in the fixture are held together by fasteners, which allow the details to be easily and quickly assembled and disassembled.  
      Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.  
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:  
       FIG. 1  is an isometric view of one embodiment of a fixture made according to the method of the present invention supporting a prototype part;  
       FIG. 2  is an isometric view of one embodiment of a fixture made according to the method of the present invention;  
       FIG. 3  is a side view of various details made according to the method of the present invention;  
       FIG. 4  is a side view of more various details made according to the method of the present invention;  
       FIG. 5  is a side view of even more various details made according to the method of the present invention; and  
       FIG. 6  is a isometric view of a base plate having various holes and notches made according to the method of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.  
      Referring to  FIGS. 1-6 , a fixture for the production of prototype parts created according to the method of the present invention is shown at  10 . The fixture  10  has a base  12  which can be equipped with various mounting orifices, such as holes  14  and notches  16 , used for receiving protrusions  18  on the various fixture components or details. The notches  16  are preferably in the form of a “T-shape,” which allows the notches to provide a higher level of precision with regard to holding the details in place. Other slot forms such as straight, I shaped, H shaped, or others which allow the respective protrusion to engage the slot in a precision positioning of the detail can be utilized. The protrusion  18  can also be used on the details to be connected with one another, as well as the base  12 . In the embodiment shown, a first slide detail  20  and a second slide detail  22  are mounted to the base  12 . A first elongated detail  24  and a second elongated detail  26  are also mounted on the base  12  in proximity to the first slide detail  20  and the second slide detail  22 . Both the first elongated detail  24  and the second elongated detail  26  are made of two flat elongated details  28  and  30 .  
      Mounted on first elongated detail  24  and second elongated detail  26  is an angled detail  32 . Mounted on each angled detail  32  are corner details  34  and raised details  36 . Mounted on the raised details  36  are third slide detail  38  and fourth slide detail  40 . Also mounted on each angled detail  32  is an edge detail  42  and a notch detail  44 . The base  12  also features two inner support details  46 .  
      Mounted into the base  12  are outer support details  48  which feature bores  50  for receiving shafts  52 . Also mounted onto shafts  52  are solid angled support detail  54  and hollow angled support detail  56 , which also have bores  50  for receiving the shafts  52 . The solid angled support detail  54  and hollow angled support detail  56  are connected together and move as a solid component on the shafts  52 . Connected to hollow angled support detail  56  is a small detail  58 .  
      The third slide detail  38  and the second slide detail  40  each have elongated slots  60  which are used to receive a fastener to connect the third slide detail  38  and fourth slide detail  40  to their respective raised details  36 .  
      The embodiment shown is used to hold the frame  62  for a seat in place so the various parts of the frame  62  can be welded together in a meticulous fashion. For example, the frame  62  is supported by the first slide detail  20 , second slide detail  22 , third slide detail  38 , fourth slide detail  40 , and inner support details  46 . The notched details  44  are used to hold rod  64  in place, while the frame  62  also rests against the edge details  42 . The rod  64  can then be welded to the frame  62 , allowing for a higher level of precision over previously used methods.  
      The method of the present invention is not limited to the construction of the fixture  10  described above. All of the details described in the embodiment above are made from aluminum “flat stock.” In the present invention it is preferred that aluminum flat stock having 0.001″ maximum thickness variation in the surface is used. This type of material can be made using the steps of the present invention into virtually unlimited shapes and sizes to create details that can accommodate the manufacture of virtually any prototype part that requires welding, cutting, fixturing part inspection or assembly.  
      The base plate  12  is preferably created by using a CNC machine, the CNC machine also can place into the base plate  12  the various holes  14  and notches  16  which are used to support the various details. Using a CNC machine to create the base plate  12  reduces the time needed to create the base plate  12 , and reduces the amount of error in the dimension of the holes  14  and notches  16 . The various details are created by an Electrical Discharge Machining (EDM) process; this process is significantly faster than creating the details from manual or CNC milling, and also allows for much improved accuracy in the various details. Because the details can be created faster, any particular prototype that needs to be built can also be created faster, and the prototype will meet the stringent dimensional tolerance requirements.  
      Another advantage of the present invention is that the details are shaped having various recesses and projections which are used to simplify the assembly of the fixture  12  as a whole. The details used in the fixture  10  can be held in place with separate fasteners. For example, the separate fasters can be a threaded nut and bolt; the advantage of the present invention is that none of the details in the fixture  10  will require drilling and tapping. The fasteners are a completely separate component from any of the details in the fixture  10 .  
      The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.