Abstract:
An apparatus for polishing an edge of an automotive glass sheet comprising a retaining device, which is capable of supporting the automotive glass sheet, and a polishing wheel assembly. A motor assembly is coupled to and drives the polishing wheel assembly to polish the edge of the automotive glass sheet to maximize the strength of the glass sheet and improve the aesthetic properties thereof. A pressure system, such as a compliant member, a robotic system, or a floating spindle assembly, is coupled to either the retaining device or the polishing wheel in order to actively maintain a predetermined generally constant contact pressure between the polishing wheel and the edge of the automotive glass sheet to insure proper polishing thereof.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application claims the benefit of U.S. Provisional Application No. 60/366,201, filed on Mar. 21, 2002. The disclosure of the above application is incorporated herein by reference. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    The present invention generally relates to automotive safety glass and, more particularly, relates to an apparatus for reliable and convenient edge polishing of automotive safety glass.  
         BACKGROUND OF THE INVENTION  
         [0003]    As is well known, automotive glass is typically constructed using generally flat sheets of glass, which are preferably sized to minimize waste thereof. During processing of this glass, the sheets are cut to size and subsequently treated in a tempering, bending, and/or otherwise shaping process. However, it should be understood that following this cutting step and preferably before further processing, the edges of the sheet should be polished to minimize burrs, reduce small peripheral fractures that could otherwise lead to shattering, and produce an aesthetically pleasing product.  
           [0004]    Frequently the polishing of the edge of the glass sheet is accomplished through a machining process, which consists of passing a fine grain polisher or a diamond wheel along the length of the sheet edge. Typically, the environment is kept humid in order to minimize the presence of air-borne glass dust during the polishing process, while a cooling fluid flows over the polishing wheel.  
           [0005]    However, conventional polishing wheel assemblies lack the ability to accommodate slight variations in the glass sheets and dimensional changes of the polishing wheel caused by wear. That is, as the polishing wheel is polishing the edge of the glass sheet, the grinding properties, such as the contact pressure on the glass sheet, invariably change due to variations in the dimensions of the glass sheet and/or polishing wheel. These dimensional variations between the glass sheet and polishing wheel result in changes in contact pressure, thereby resulting in polishing variations or even stress fractures.  
           [0006]    Accordingly, there exists a need in the relevant art to provide an apparatus for polishing the edge of automotive safety glass that is capable of maximizing the strength of the glass sheet and improving the aesthetic properties thereof. Furthermore, there exists a need in the relevant art to provide an apparatus for polishing the edge of automotive safety glass that is capable of maintaining a constant and consistent contact pressure between the glass sheet and the polishing wheel. Additionally, there exists a need in the relevant art to provide an apparatus for polishing the edge of automotive safety glass that overcomes the disadvantages of the prior art.  
         SUMMARY OF THE INVENTION  
         [0007]    According to the principles of the present invention, an apparatus is provided for polishing an edge of an automotive glass sheet. The apparatus comprises a retaining device, which is capable of supporting the automotive glass sheet, and a polishing wheel assembly. A motor assembly is coupled to and drives the polishing wheel assembly to polish the edge of the automotive glass sheet to maximize the strength of the glass sheet and improve the aesthetic properties thereof. A pressure system, such as a compliant member, a robotic system, or a floating spindle assembly, is coupled to either the retaining device or the polishing wheel in order to actively maintain a predetermined generally constant contact pressure between the polishing wheel and the edge of the automotive glass sheet to insure proper polishing thereof.  
           [0008]    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  
       [0009]    The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:  
         [0010]    [0010]FIG. 1 is a perspective view illustrating a first embodiment of the present invention employing a floating spindle apparatus having a pressure control device; and  
         [0011]    [0011]FIG. 2 is a perspective view illustrating a first embodiment of the present invention employing a servo feedback robotic arm assembly. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0012]    The following description of the preferred embodiments is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. For example, the principles of the present invention may have utility in a wide variety of glass processing applications, such as the polishing of laminated sheets, tempered glass, or other application where glass sheets having improved strength characteristics and aesthetic properties is preferred.  
         [0013]    Referring now to FIG. 1, an edge polishing apparatus, generally indicated at  10 , is provided for maintaining a constant and consistent polishing pressure upon the edge of an automotive glass sheet  12  according to a first embodiment of the present invention. Edge polishing apparatus  10  generally includes a moveable support structure  14 , a glass sheet retaining device  16 , a conveyor assembly  18 , a polishing wheel assembly  20 , and a chip removal system  22 .  
         [0014]    Preferably, glass sheet retaining device  16  is coupled to conveyor assembly  18  such that automotive glass sheet  12  is carried quickly and conveniently between processing stations (not shown) during a complete manufacturing process. Although, the principles of the present invention are intended to be employed in conjunction with traditional processing steps, such as cutting, tempering, laminating, bending, and the like, the present invention should not be regarded as requiring such steps.  
         [0015]    Still referring to FIG. 1, glass sheet retaining device  16  includes a plurality of retaining members  24 , such as suction pads or overlapping retaining arms. The plurality of retaining members  24  releasably secures automotive glass sheet  12  to glass sheet retaining device  16  such that automotive glass sheet  12  may be conveniently carried and transported by conveyor assembly  18 .  
         [0016]    Polishing wheel assembly  20  generally includes a motor  26  fixedly coupled to moveable support structure  14  to prevent relative movement therebetween. Polishing wheel assembly  20  further includes a polishing wheel  28  coupled to support structure  14  through a floating pressure assembly  30 , which enables polishing wheel  28  to move relative to support structure  14 , yet maintain a generally constant contact pressure with automotive glass sheet  12 . This relative movement between polishing wheel  28  and support structure  14  accommodates dimensional and positional variations of automotive glass sheet  12  and wear of polishing wheel  28 .  
         [0017]    Floating pressure assembly  30  includes a motor linkage or shaft  32  extending from motor  26  and a wheel linkage or shaft  34  pivotally coupled to and driving polishing wheel  28 . An intermediate linkage or member  36  is pivotally coupled at one end  38  to an end  40  of motor linkage  32  to permit the pivoting movement of intermediate linkage  36  about motor linkage  32 . Intermediate linkage  36  is further coupled at an opposing end  42  to an end  44  of wheel linkage  34 . Motor linkage  32 , intermediate linkage  36 , and wheel linkage  34  thus cooperate to provide a flexing motion between polishing wheel  28  and automotive glass sheet  12 . A spring member  47  is coupled to either intermediate linkage  36  or wheel linkage  34  to bias polishing wheel  28  in a retracted position and into contact with automotive glass sheet  12 . The biasing force of spring member  47  is adjustable via an adjustment knob  49 . Adjustment knob  49  is a screw-type device that when “tightened” will increase the biasing force of spring member  47 , thereby increasing the contact pressure of polishing wheel  28 . Conversely, when adjustment knob  49  is “loosened”, the biasing force of spring member  47  is decreased, thereby decreasing the contact pressure of polishing wheel  28 .  
         [0018]    Preferably, in order to ensure proper contact pressure between polishing wheel  28  and automotive glass sheet  12 , an optional pressure sensor  48  is coupled between support structure  14  and intermediate linkage  36 . Pressure sensor  48  is preferably a pressure transducer capable of measuring the contact force between polishing wheel  28  and automotive glass sheet  12 . Pressure sensor  48  is more preferably adjustable to be set to a specific polishing pressure setting. In operation, pressure sensor  48  could be controlled by a linear variable displacement transformer that is converted to torque or a differential amp draw on the motor created by a position. This torque or differential amp draw may be used to identify a unique position or applied force.  
         [0019]    Polishing wheel  28  is generally circular in shape and includes a polishing or grinding groove  50  extending therearound. Preferably, polishing wheel  28  is made of a fine grain or diamond material; however, it should be understood that polishing wheel  28  may be made of any material and have any cross-sectional profile that maximizes the polishing effect of the glass sheet.  
         [0020]    Polishing wheel  28  is driven through a drive system  51  that is coupled to or disposed within floating pressure assembly  30 . By way of non-limiting example, the drive system may include a gearing system disposed within the linkage members (i.e. a first drive shaft  51   a,  a second drive shaft  51   b,  and an intermediate drive member  51   c ), which are interconnected through known gearing components. That is, the drive system may include a series of drive shafts interconnected through a belt assembly and/or worm gear systems. Ideally, first drive shaft  51   a  is directly coupled to motor  26  so as to permit first drive shaft  51   a  to be driven in response thereto. Intermediate drive member  51   c  is preferably a belt extending between first drive shaft  51   a /motor linkage  32  and second drive shaft  51   b /wheel linkage  34 , which maintains a driving connection even as polishing wheel  28  floats.  
         [0021]    Still referring to FIG. 1, edge polishing apparatus  10  includes chip removal system  22  and a cooling system  52 . Chip removal system  22  is preferably a vacuum system that is capable of removing, containing, and/or treating glass dust and other debris produced during polishing. Cooling system  52  preferably includes pump assembly  54  for pumping a cooling fluid from a sump  56  to an outlet  58 . Outlet  58  is preferably oriented such that the cooling fluid is directed generally toward polishing wheel  28  to provide cooling of polishing wheel  28 . The cooling fluid further serves to lubricate the contact point between polishing wheel  28  and automotive glass sheet  12 . Preferably, pump assembly  54  includes a filtering device (not shown) for removing debris from the cooling fluid.  
         [0022]    During operation, automotive glass sheet  12  is retained by retaining device  16  via the plurality of retaining members  24 . According to the present embodiment, automotive glass sheet  12  remains stationary as polishing wheel  28  passes therearound. During this time, motor  26  rotatably drives polishing wheel  28  via drive system  51 . Simultaneously, moveable support structure  14  carries polishing wheel assembly  20 , chip removal system  22 , and cooling system  52  about automotive glass sheet  12  along a predetermined path. As can be appreciated, due to the ability of edge polishing apparatus  10  to accommodate dimensional variations of automotive glass sheet  12  and/or dimensional variations of polishing wheel  28 , it is not necessary that moveable support structure  14  trace an exact path relative to automotive glass sheet  12 . Alternatively, it should be understood that polishing wheel assembly  20 , chip removal system  22 , and cooling system  52  may remain stationary while automotive glass sheet  12  is rotated during polishing.  
         [0023]    During the polishing process, polishing wheel  28  remains in contact with automotive glass sheet  12 . However, dimensional variations in automotive glass sheet  12  and/or polishing wheel  28  produce a resultant force between polishing wheel assembly  20  and automotive glass sheet  12 . This resultant force, in the case where the portion of automotive glass sheet  12  extends outwardly, forces polishing wheel  28  and wheel linkage  34  in a direction, generally indicated by Arrow A. Consequently, intermediate linkage  36  pivots about motor linkage  32 , thereby moving intermediate linkage  36  against the biasing force of spring member  47 . However, spring member  47  is set to a predetermined setting to maintain the appropriate biasing force within intermediate linkage  36  and, thus, the appropriate contact pressure between polishing wheel  28  and automotive glass sheet  12 . A similar, but opposite, operation occurs when a portion of automotive glass sheet  12  extends inwardly.  
         [0024]    It should be understood, however, that although pressure sensor  48  may be used to ensure the proper contact pressure between polishing wheel  28  and automotive glass sheet  12 , it is not required. That is, once polishing wheel assembly  20 , namely spring member  47 , is set to maintain the desired contact pressure, further adjustment is not generally required. Therefore, pressure sensor  48  may be subsequently removed. Moreover, it should be understood that motor  26 , polishing wheel  28 , and a direct drive shaft (not shown) may be used in fixed relationship with each other. In this case, the entire unit consisting of motor  26 , polishing wheel  28 , and a direct drive shaft would be biased in an engaged position against automotive glass sheet  12 . During operation, this unit would be capable of articulating relative to the edge of automotive glass sheet  12 .  
         [0025]    During the polishing operation, chip removal system  22  removes, contains, or treats glass dust and other debris produced during polishing. Additionally, chip removal system  22  is preferably capable of removing, cleaning, and recirculating the cooling fluid output by cooling system  52 . Such filtering may be accomplished within a filtering device of cooling system  52 .  
         [0026]    Referring now to FIG. 2, an edge polishing apparatus, generally indicated at  100 , is provided for maintaining a constant and consistent polishing pressure upon the edge of an automotive glass sheet  12  according to a second embodiment of the present invention. Although it should be readily understood that such components may be used in conjunction with the present embodiment.  
         [0027]    Edge polishing apparatus  100  generally includes a moveable support structure  115 , a glass sheet retaining device  116 , a polishing wheel assembly  120 , chip removal system  22 , and a cooling system  52 .  
         [0028]    Moveable support structure  115  is provided for handling automotive glass sheet  12  during the polishing procedure. Moveable support structure  115  is preferably a joint servo robot  122  having a base structure  124 , a first arm linkage  126 , and a second arm linkage  128 . An end  130  of first arm linkage  126  is pivotally coupled to base structure  124  at joint  132 . First arm linkage  126  is articulatable about base structure  124  to provide the necessary degrees of freedom.  
         [0029]    Similarly, an opposing end  134  of first arm linkage  126  is pivotally coupled to second arm linkage  128  at an end  136  at joint  138 . Unlike joint  132 , joint  138  may be limited to freedom along a single plane. However, if additional degrees of freedom are required, joint  138  may be a ball joint or the like. Glass retaining device  116  is further coupled to an opposing end  140  of second arm linkage  128 . Glass retaining device  116  may be of similar construction to glass retaining device  16  or may include a single main suction member, as shown.  
         [0030]    Joint servo robot  122  includes a plurality of servo motors (not shown) that actuate first arm linkage  126  and second arm linkage  128  to position the edge of automotive glass sheet  12  in contact with polishing wheel assembly  120  according to the principles of the present invention. To this end, joint servo robot  122  rotates automotive glass sheet  12  such that the entire edge of automotive glass sheet  12  is polished.  
         [0031]    Polishing wheel assembly  120  generally includes a motor  126  fixedly coupled to a support structure  114  to prevent relative movement therebetween. Polishing wheel assembly  120  further includes a polishing wheel  28  coupled to motor  126  through a direct drive assembly  130 .  
         [0032]    Direct drive assembly  130  may be a motor linkage  132  extending from motor  126  pivotally coupled to polishing wheel  28 . In order to ensure proper contact pressure between polishing wheel  28  and the edge of automotive glass sheet  12 , motor linkage  132  is preferably a compliant member that is capable of flexing to accommodate the dimensional variation of automotive glass sheet  12  and/or dimensional variation of polishing wheel  28  caused by wear. However, it should be understood that direct drive assembly  130  may include spring member  47  and adjustment knob  49 , as described above and illustrated in phantom in FIG. 2.  
         [0033]    Polishing wheel  28  is driven through direct drive system  130 , which may include a gearing system disposed within the motor linkage  132 . Alternatively, direct drive system  130  may include a drive shaft that is capable of driving polishing wheel  28 .  
         [0034]    During operation, automotive glass sheet  12  is retaining by retaining device  116 . According to the present embodiment, polishing wheel assembly  120  remains generally stationary as joint servo robot  122  rotates automotive glass sheet  12  such that the entire edge of automotive glass sheet  12  is polished by polishing wheel  28 . During this time, motor  126  rotatably drives polishing wheel  28  via direct drive system  130 . As can be appreciated, due to the ability of edge polishing apparatus  100  to accommodate dimensional variations of automotive glass sheet  12  or dimensional variations of polishing wheel  28 , it is not necessary that joint servo robot  122  rotate automotive glass sheet  12  exactly, since variations in contact pressure are accommodate by compliant motor linkage  132 .  
         [0035]    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.