Abstract:
This disclosure concerns a device for machining surfaces, e.g., superfinishing, polishing, grinding or lapping spherical shells or flattened domes of a workpiece, or, for example, a ball joint, using a tool having a machining stone with a workpiece receiver, a first drive for an oscillating motion about a first axis of the workpiece, a tool holder and a second drive for an oscillating motion about a second axis of the tool holder, whereby the axes are an angle to one another.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 61/077,298, filed on Jul. 1, 2008, the contents of which are incorporated herein by reference. 
     
    
     FIELD 
       [0002]    The present disclosure relates to a device for processing surfaces. 
       BACKGROUND 
       [0003]    In various cutting forms of processing, such as for example, superfinishing, honing, slotting and planing, the tool executes an oscillating motion. 
       SUMMARY 
       [0004]    The present disclosure concerns a device for processing surfaces, especially for superfinishing, polishing, grinding or lapping spherical shells for a workpiece having a flattened dome or flattened dome sections using a tool having a machining stone with a workpiece receiver and a tool holder, each with a respective drive. 
         [0005]    It is generally known that, as with other machining methods, a tool is brought into contact with a workpiece in the superfinishing method as well. By superposing the workpiece rotation and workpiece oscillation, for example, a single grain moves along a sinusoid curve typical of this method. By superposing the individual sinusoidal lines, all meshing polishing grains generate the processing traces intersecting at a defined angle. Since the tool is applied onto the workpiece at a specified pressure, care must be taken that the contact of the tool with the workpiece is not interrupted, namely that the tool does not leave the surface to be processed, as the tool has to be lifted prior to leaving the surface and would have to be subsequently put on it again, which considerably delays processing. Therefore, the aforementioned devices are suited for continuous processing of non-interrupted surfaces, for example of the surface of a camshaft or the surface of a friction bearing. Should, however, surfaces be processed having interruptions over their circumference, other methods may have to be used. 
         [0006]    Therefore, provided herein is a device by means of which surfaces may be processed, for example, with a superfinishing method, which are not continuous, but may have interruptions over their circumference. 
         [0007]    Further provided is a device for superfinishing spherical shells or parts of spherical shells or flattened domes, which are provided on workpieces, and which, for example, are part of a ball joint. The device is a tool having a machining stone, with a workpiece receiver, a first drive for an oscillating motion about a first axis of the workpiece, a tool holder, and a second drive for an oscillating motion about a second axis of the tool holder, whereby the first axis and the second axis are arranged at an angle to one another. 
         [0008]    The device has two drives, namely a drive for the workpiece or the workpiece holder and a drive for the tool, whereby both drives set the workpiece and tool into an oscillatory motion. In this way, it is assured that even in the event that interrupted surfaces are to be processed on the workpiece, the tool does not leave the processing surface since neither the workpiece nor the tool rotates. The oscillatory motions are adjusted such that the machining stone does not leave the likewise oscillating surface of the workpiece to be processed. The processing can therefore take place continuously, namely, without interruptions. 
         [0009]    Further provided is the device wherein the axes of oscillation of the first drive and the second drive intersect at the center of the center of the sphere of the spherical shells or the flattened dome. The axes may be orthogonal to one another. In this way, the desired sinusoid curves are generated, the processing traces having been at a defined angle to one another. 
         [0010]    The angle of oscillation of at least one of the drives may be adjusted. It is provided that the angle of oscillation of at least one of the drives may also be adjusted during processing. In this way, processing traces can be generated in the form of a figure eight, or a lying figure eight, or in the form of Lissajous curves. 
         [0011]    In this case, for example, oscillation angles of about ±5° to about ±20°, about ±8° to about ±15°, or about ±10° may be generated. The oscillation angles for the tool drive may also be different from the oscillation angle of the workpiece drive. The drives may be coupled so that phase-shifted motions may be generated, during which the resulting processing speed never becomes zero. 
         [0012]    In one form, the machining stone is cylindrical and has a partial spherical working surface corresponding to the shape of the flattened dome. In this case, the partial spherical working surface is advantageously situated on the frontal area of the cylinder. The cylinder may have a round, especially circular, or polygonal, e.g., rectangular or square cross section. 
         [0013]    The machining stone may be moved in the direction of or parallel to the axis of the first drive and/or to the axis of the second drive so that it is introduced into the spherical shell or flattened dome and may be advanced to the surface to be processed. 
         [0014]    In order to obtain the desired abrasion, the machining stone may be acted upon with a contact pressure in the direction of the axis of the first drive or orthogonally to the surface to be processed. This contact pressure is adjustable and/or may in turn be adjusted during processing. 
         [0015]    In order to be able to process two surfaces of a spherical shell or flattened dome that are in opposite positions to one another with a single stone, the second drive is configured for the tool holder such that the machining stone may be rotated about its oscillation axis by 180° and/or such that the machining stone has two opposed working surfaces. After finishing one of the surfaces to be processed, the stone need only be displaced in the direction of the other surface to be processed. 
         [0016]    Another version provides that the machining stone is made of several stone sections, whereby the stone sections consist of various materials. In this way, pre-machining and machining may be performed with the machining stone. Both stone sections have a working surface which, for example, have different grain sizes. 
         [0017]    Further advantages, features and details of this disclosure will be apparent from the description and claims which follow. 
     
    
     
       DRAWINGS 
         [0018]    In order that the disclosure may be well understood, there will now be described various forms thereof, given by way of example, reference being made to the accompanying drawings, in which: 
           [0019]      FIG. 1  shows a plan view of a device according to the disclosure; 
           [0020]      FIG. 2  shows a longitudinal section of the workpiece to be processed; 
           [0021]      FIG. 3  shows a plan view of the workpiece with an embodiment of the workpiece; 
           [0022]      FIG. 4  shows a plan view of the workpiece with an embodiment of the tool; and 
           [0023]      FIG. 5  shows a plan view of the workpiece with a further embodiment of the tool. 
       
    
    
       [0024]    The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. 
       DETAILED DESCRIPTION  
       [0025]    The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. 
         [0026]      FIG. 1  is a plan view of the device  10 , according to the disclosure, for processing surfaces, for example for superfinishing a workpiece  12 , whereby the workpiece  12  is inserted into a workpiece receiver  14  of a first drive  16 . The workpiece  12  is shown enlarged in  FIG. 2  and has a piston  18  and a flattened dome  20  which are components of a ball joint, for example for the drive of the piston  18 , and has surfaces  22  and  24  to be processed lying opposite one another and accommodate a ball of the ball joint between them. A machining stone  28  fastened on a tool holder  26  ( FIGS. 3 and 4 ) meshes with the flattened dome  20 , whereby the tool holder  26  is fastened to a second drive  30 . 
         [0027]    By means of the first drive  16 , the workpiece receiver  14  and, consequently, the workpiece  12 , may be driven oscillating about its longitudinal axis  32  lying perpendicular in the drawing, and indicated with the arrow  34  (see  FIGS. 3 and 4 ). 
         [0028]    With the second drive  30 , the tool holder  26  is driven oscillating about its vertical longitudinal axis  36  in the drawings, which is orthogonal to the axis  32  and intersects the axis  32  at the center of the flattened dome  20 , which is indicated with the arrow  38  (see  FIGS. 3 and 4 ). 
         [0029]    As is apparent from  FIGS. 3 and 4 , the machining stone  28  is fastened on the tool holder  26  by means of a quick-release clamping device, whereby the machining stone  28  has a cylindrical, or circular cylindrical shape, and is outfitted with a partial spherical working surface  40  on one frontal face. 
         [0030]      FIG. 4  illustrates a second embodiment in which the machining stone has two partial spherical working surfaces  40  and  42  which oppose one another and with which surfaces  22  and  24  of the flattened dome  20  may be processed. But it is also possible to manufacture the machining stone  28  in two stone halves whereby the one stone half serves for coarse machining with the superfinishing method and the other stone half serves for fine machining with the superfinishing process. 
         [0031]    After introducing the machining stone  28  into the flattened dome  20 , which takes place by displacing the tool holder  26  in the direction of arrow  44 , the tool holder  26  may in the first instance be displaced in the direction of surface  22  (arrow  46 ) until the working surface  40  lies on the surface to be processed  22  with a specifiable contact pressure. Subsequently, the workpiece  12  is driven oscillating in the direction of arrow  34  and the machining stone  28  is driven oscillating in the direction of arrow  38 , as a result of which surface  22  is machined and machining furrows are generated in the form of a  FIG. 8 . The oscillation angles of the workpiece  12  and the machining stone  28  are respectively selected such that the working surface  40  does not leave the surface  22 . Alternatively, however, after introducing the machining stone  28  into the flattened dome  20 , the workpiece  12  may also be displaced in the direction of the machining stone  28  until it is set on the working surface  40 . 
         [0032]    After ending the machining process, in the embodiment of  FIG. 3 , the tool holder  26  is slightly displaced in the opposite direction of arrow  46 , until the machining stone  28  lifts off from surface  22  and [is] then rotated 180° in the direction of arrow  38  so that the opposite surface  24  may be processed. After finishing surface  24 , the machining stone  28  is once again displaced in the direction of arrow  46  up to the center of the flattened dome  20  and lifted off the flattened dome  20  opposite the direction of arrow  44 . 
         [0033]    There also exists the possibility of additionally moving the machining stone  28  oscillating about the axis  32  toward the workpiece  12 , which is represented with arrow  48 . 
         [0034]    In the embodiment of  FIG. 4 , the tool holder  26  is displaced after finishing surface  22  opposite the direction of arrow  46  until the working surface  42  lies on surface  24  so that it may be processed. Alternatively, and in particular in case of two different stone halves, the tool holder  26  is rotated 180° in the direction of arrow  38  after finishing surface  22  and after lifting the machining stone  28  from surface  22  such that the surface  22  can be machined with the working surface  42  of the second stone half. Subsequently, the tool holder  26  is displaced in the opposite direction of arrow  46  until the working surface  40  lies on surface  24  so that it may be machined. Subsequently, the tool holder  26  is in turn rotated 180° in the direction of arrow  38  so that surface  24  may be machined with the working surface  42 . The machining sequence may be selected in any desired manner. 
         [0035]    A further version of the invention is represented in  FIG. 5 . The machining stone  28  is likewise divided in two in this embodiment, whereby a device  50  for spreading the machining stone sections is provided between the two machining stone sections. The machining stone sections may also be pressed with a definable contact pressure against the surfaces of workpiece ( 12 ) to be machined. 
         [0036]    It is moreover apparent from  FIG. 5  that a finishing band  52  may be interposed between working surface  40  and/or  42  of the machining stone  28  and the surface of the workpiece  20  to be processed. This is also possible in the other versions described above. The machining stone sections of device  50  are moved together to remove the tool  28  from the workpiece  20 . By means of device  50 , the machining stone sections may also be pressed against working surfaces  40  and  42  with a defined contact pressure. The finishing band  52  oscillates together with the machining stone  28  which also may merely be an element for transferring the desired shape and is made of Vulcolan®, for example. 
         [0037]    In any case, a curved surface  22 ,  24  which does not extend over 360° may be machined with the device  10  according to the invention without the machining stone  28  having to be lifted from the surfaces  22 ,  24  to be machined during the machining process. The surface  22  or  24  to be machined as well as the working surfaces  40  and  42  of the machining stone  28  execute oscillating motions at an angle to one another. In this case, the oscillatory motions have different frequencies which, advantageously, are not whole number multiples of one another. 
         [0038]    It should be noted that the disclosure is not limited to the embodiment described and illustrated as examples. A large variety of modifications have been described and more are part of the knowledge of the person skilled in the art. These and further modifications as well as any replacement by technical equivalents may be added to the description and figures, without leaving the scope of the present disclosure.