Method and apparatus for finishing glass sheets

Abstract

Methods and apparatus for finishing an edge of a glass sheet are described. The edge of the glass sheet is finished using a grinding wheel mounted on one end of a spindle, the grinding wheel having a peripheral edge that contacts the edge of the glass sheet during the grinding. The edge of the glass sheet is further finished by polishing the edge of the glass sheet with a polishing wheel mounted on one end of a spindle, the polishing wheel having an end face which contacts the glass edge during polishing.

What is claimed is: 
     
         1 . An apparatus for finishing an edge of a glass sheet comprising:
 a worktable which supports the glass sheet while the edges are subjected to grinding and polishing, wherein an X-axis is a direction of lateral movement on a plane of a glass sheet on the worktable, a Y-axis is a direction of longitudinal movement on the plane which is perpendicular to the X-axis, and a Z-axis is a direction of vertical movement with respect to the plane;   a rotary table movable along the X-axis and the Y-axis, the rotary table having a rotary table axis of rotation;   a first spindle and a second spindle mounted to the rotary table having a common spindle axis of rotation about which the first spindle and the second spindle rotate, the common spindle axis of rotation orthogonal to the rotary table axis of rotation; and   a grinding wheel mounted on the first spindle and a polishing wheel mounted on the second spindle, the grinding wheel configured to grind an edge of the glass sheet with the common spindle axis of rotation parallel to the Z-axis and the polishing wheel configured to polish an edge of the glass sheet with the common spindle axis of rotation parallel to the X-axis.   
     
     
         2 . The apparatus of  claim 1 , further comprising a plurality of first peripheral liquid cooling nozzles arranged in a ring, the first peripheral liquid cooling nozzles adjacent the first spindle and positioned to direct cooling liquid toward a peripheral edge of the grinding wheel. 
     
     
         3 . The apparatus of  claim 2 , further comprising a plurality of second peripheral liquid cooling nozzles arranged in a ring, the second peripheral liquid cooling nozzles adjacent the second spindle. 
     
     
         4 . The apparatus of  claim 2 , further comprising a plurality of remote liquid cooling nozzles positioned remotely from the grinding wheel and the polishing wheel and positioned to direct cooling liquid toward an edge of the glass sheet. 
     
     
         5 . The apparatus of  claim 4 , wherein the plurality of first peripheral liquid cooling nozzles and remote liquid cooling nozzles are configured to be activated during grinding of the glass sheet. 
     
     
         6 . The apparatus of  claim 2 , wherein the plurality of first peripheral liquid cooling nozzles includes four cooling nozzles. 
     
     
         7 . The apparatus of  claim 2 , wherein the plurality of first peripheral liquid cooling nozzles includes six cooling nozzles. 
     
     
         8 . The apparatus of  claim 1 , wherein the grinding wheel comprises a cylindrical wheel including a peripheral grinding edge and the polishing wheel comprises a cup wheel including a peripheral polishing edge and a polishing end face. 
     
     
         9 . The apparatus of  claim 8 , wherein the first spindle and the grinding wheel are configured to contact an edge of the glass sheet by the peripheral grinding edge during grinding and the second spindle and the polishing wheel are configured to contact an edge of the glass sheet by the polishing end face. 
     
     
         10 . The apparatus of  claim 9 , wherein the polishing end face of the cup wheel comprises a slotted surface. 
     
     
         11 . The apparatus of  claim 1 , wherein the rotary table is mounted on a gantry movable along the y-axis and the rotary table is movable along the x-axis. 
     
     
         12 . The apparatus of  claim 11 , wherein the gantry is movable along a y-axis carriage, and the rotary table is movable along an x-axis carriage. 
     
     
         13 . A method of grinding and polishing an edge of a glass sheet comprising:
 supporting a glass sheet on a surface, wherein an X-axis is a direction of lateral movement on a plane of a glass sheet on the surface, a Y-axis is a direction of longitudinal movement on the plane which is perpendicular to the X-axis, and a Z-axis is a direction of movement orthogonal to the plane;   grinding the edge of the glass sheet with a grinding wheel mounted on one end of a first spindle, the first spindle oriented along the Z-axis during grinding and the grinding wheel comprising a peripheral edge that contacts the edge of the glass sheet during the grinding; and   polishing the edge of the glass sheet with an end face of a polishing wheel mounted on one end of a second spindle, the second spindle positioned parallel to the plane during polishing.   
     
     
         14 . The method of  claim 13 , further comprising directing cooling fluid at the peripheral edge of the grinding wheel with a plurality of first peripheral liquid cooling nozzles arranged in a ring, the first peripheral liquid cooling nozzles adjacent the peripheral edge of the grinding wheel. 
     
     
         15 . The method of  claim 14 , further comprising directing cooling fluid at the edge during polishing with a plurality of remote liquid cooling nozzles positioned remotely from the edge of the glass sheet. 
     
     
         16 . The method of  claim 15 , further comprising directing cooling fluid at the edge during grinding with the plurality of remote liquid cooling nozzles positioned remotely from the edge of the glass sheet. 
     
     
         17 . The method of  claim 15 , further comprising moving the first spindle and the second spindle relative to the glass sheet in a direction along the Y-axis during grinding and polishing of the edge of the glass sheet. 
     
     
         18 . The method of  claim 17 , wherein the first spindle and second spindle rotate about a common spindle axis of rotation. 
     
     
         19 . The method of  claim 15 , wherein the polishing wheel is a cup wheel. 
     
     
         20 . The method of  claim 19 , wherein the cup wheel comprises slots on the end face thereof. 
     
     
         21 . The method of  claim 13 , further comprising forming a hole in the glass sheet with a hole drilling tool coupled to the first spindle or the second spindle. 
     
     
         22 . The method of  claim 13 , the edge being a finished edge after grinding and polishing, the finished edge having an average roughness of less than about 0.2 micrometers. 
     
     
         23 . The method  claim 22 , wherein the glass sheet comprises SiO 2  in a range of 50 mol % to 80 mol %, Al 2 O 3  in a range of 0 mol % to 20 mol %, and B 2 O 3  in a range of 0 mol % to 25 mol %, and less than 50 ppm by weight Fe.