Grinding apparatus

Abstract

A grinding apparatus including a chuck table whose holding surface is polygonal, a grinding unit, a moving unit, a load detection unit, and a controller, wherein the controller includes a load storage section, a holding surface grinding command section that controls a load applied to one (or both) the grinding unit and the chuck table, by controlling a parameter related to grinding processing when the holding surface is ground, and a workpiece grinding command section that controls a load that is the same type of load as that controlled by the holding surface grinding command section, by controlling the parameter related to grinding processing when a workpiece held on the holding surface is ground, and the controller controls the parameter related to grinding processing such that the load controlled by the holding surface grinding command section and the load controlled by the workpiece grinding command section have the same value.

What is claimed is: 
     
         1 . A grinding apparatus comprising:
 a chuck table that has a holding surface polygonal in plan view and is rotatable about a predetermined rotational axis by a rotary drive source including a first motor;   a grinding unit that includes a spindle mounted at a higher position than the holding surface and a spindle motor for rotating the spindle and has a grinding wheel mounted on the spindle;   a moving unit that includes a second motor and moves the chuck table and the grinding unit relative to each other along a predetermined direction;   a load detection unit that detects a load applied to one of or both the grinding unit and the chuck table; and   a controller that includes a processor and a memory and receives information regarding the load from the load detection unit, wherein   the controller includes
 a load storage section that stores one of or both a predetermined load value and the information regarding the load, 
 a holding surface grinding command section that controls the load applied to one of or both the grinding unit and the chuck table, by controlling a parameter related to grinding processing when the holding surface is ground by the grinding wheel, and 
 a workpiece grinding command section that controls the load that is applied to one of or both the grinding unit and the chuck table and that is a same type of load as that controlled by the holding surface grinding command section, by controlling the parameter related to grinding processing when a workpiece held on the holding surface is ground, and 
   the controller controls the parameter related to grinding processing such that the load controlled by the holding surface grinding command section and the load controlled by the workpiece grinding command section have a same value.   
     
     
         2 . The grinding apparatus according to  claim 1 , wherein
 the load detection unit includes at least any one of
 a first load sensor configured to detect a first load that is a load applied to the grinding unit, 
 a second load sensor configured to detect a second load that is a load applied to the chuck table, or 
 a load ammeter configured to measure a load current flowing in the spindle motor, the load current being a load of the spindle motor, 
   the load applied to the grinding unit includes the first load and the load current,   the load applied to the chuck table includes the second load, and   the parameter related to grinding processing includes
 a relative moving speed of the chuck table and the grinding unit along the predetermined direction, 
 a rotational speed of the chuck table, 
 a rotational speed of the spindle, and 
 a flow rate of grinding water to be supplied per unit hour. 
   
     
     
         3 . The grinding apparatus according to  claim 1 , wherein
 the parameter related to grinding processing is a relative moving speed of the chuck table and the grinding unit along the predetermined direction,   the holding surface grinding command section controls the moving speed such that the load applied to one of or both the grinding unit and the chuck table has the predetermined load value, when the holding surface is ground by the grinding wheel, and   the workpiece grinding command section controls the moving speed such that the load that is applied to one of or both the grinding unit and the chuck table and that is the same type of load as that controlled by the holding surface grinding command section has the predetermined load value, when the workpiece held on the holding surface is ground.   
     
     
         4 . A workpiece grinding method for grinding a workpiece held on a holding surface, polygonal in plan view, of a chuck table, after the holding surface is ground, the method comprising:
 grinding the holding surface of the chuck table by a first grinding wheel mounted on a spindle, while detecting, by a load detection unit, a load applied to one of or both a grinding unit including the spindle and the chuck table that is rotatable about a predetermined rotational axis and bringing the grinding unit and the chuck table relatively close to each other along a predetermined direction;   after the grinding the holding surface, holding the workpiece having a polygonal shape corresponding to the holding surface on the holding surface; and   after the holding, grinding the workpiece held on the holding surface by a second grinding wheel mounted on the spindle, while detecting, by the load detection unit, the load applied to one of or both the grinding unit and the chuck table and bringing the grinding unit and the chuck table relatively close to each other along the predetermined direction, wherein   a parameter related to grinding processing is controlled such that the load applied to one of or both the grinding unit and the chuck table and detected by the load detection unit in the grinding the holding surface and the load that is applied to one of or both the grinding unit and the chuck table and detected by the load detection unit in the grinding the workpiece and that is a same type of load as that controlled in the grinding the holding surface have a same value.   
     
     
         5 . The workpiece grinding method according to  claim 4 , wherein
 the load applied to the grinding unit includes a first load applied to the grinding unit and a load current that is a load of a spindle motor that rotates the spindle,   the load applied to the chuck table includes a second load applied to the chuck table, and   the parameter related to grinding processing includes
 a relative moving speed of the chuck table and the grinding unit along the predetermined direction, 
 a rotational speed of the chuck table, 
 a rotational speed of the spindle, and 
 a flow rate of grinding water to be supplied per unit hour. 
   
     
     
         6 . The workpiece grinding method according to  claim 4 , wherein,
 in the grinding the holding surface, the parameter related to grinding processing is controlled such that the load applied to one of or both the grinding unit and the chuck table has a same value as the load that is to be detected by the load detection unit when the workpiece is ground in the grinding the workpiece and that is known beforehand.   
     
     
         7 . The workpiece grinding method according to  claim 4 , wherein,
 in the grinding the workpiece, the parameter related to grinding processing is controlled such that the load applied to one of or both the grinding unit and the chuck table is of a same type and has a same value as the load detected by the load detection unit when the holding surface is ground in the grinding the holding surface.   
     
     
         8 . The workpiece grinding method according to  claim 4 , further comprising:
 before the grinding the holding surface, setting the predetermined load value as a target value in the grinding the holding surface and the grinding the workpiece, wherein   the parameter related to grinding processing is controlled such that the load controlled has the predetermined load value in both the grinding the holding surface and the grinding the workpiece.   
     
     
         9 . The workpiece grinding method according to  claim 4 , wherein
 the first grinding wheel that has last ground the holding surface in the grinding the holding surface and the second grinding wheel used throughout the grinding the workpiece are a same grinding wheel.