Method for measuring the thickness of flat workpieces

Abstract

A method for measuring the thickness of flat workpieces processed in a double-side processing machine comprises processing the workpieces in a working gap formed between an upper working disk and a lower working disk configured to remove material from the workpieces. Optically measuring the thickness of the workpieces during processing by at least one optical thickness measurement apparatus disposed on at least one of the upper working disk or the lower working disk. The at least one optical thickness measurement apparatus configured to measure the thickness of the workpieces disposed in the working gap through at least one through-hole in a corresponding upper working disk or the lower working disk. Supplying the measurement results of the at least one thickness measurement apparatus to a control apparatus of the double-side processing machine. Terminating the processing of the workpieces once a previously specified target thickness of the workpieces is reached.

1 . A method for measuring a thickness of workpieces processed in a double-side processing machine, the method comprising:
 processing the workpieces in a working gap formed between an upper working disk and a lower working disk, the upper and lower working disks configured to rotate relative to one another and remove material from the workpieces;   optically measuring the thickness of the workpieces during processing by at least one optical thickness measurement apparatus disposed on at least one of the upper working disk or the lower working disk, wherein the at least one optical thickness measurement apparatus is configured to measure the thickness of the workpieces disposed in the working gap through at least one through-hole in the at least one of the upper working disk or the lower working disk;   supplying the measurement results of the at least one optical thickness measurement apparatus to a control apparatus of the double-side processing machine; and   terminating the processing of the workpieces once a previously specified target thickness of the workpieces is reached.   
     
     
         2 . The method according to  claim 1 , wherein the at least one optical thickness measurement apparatus measures the thickness of the workpieces by an interferometric thickness measurement method. 
     
     
         3 . The method according to  claim 1 , wherein the at least one optical thickness measurement apparatus further comprises an optical radiation source that emits infrared radiation. 
     
     
         4 . The method according to  claim 1 , wherein the at least one optical thickness measurement apparatus further comprises at least one focusing optic disposed in the at least one through-hole. 
     
     
         5 . The method according to  claim 4 , wherein the focusing optic has a focus depth of at least 1 mm. 
     
     
         6 . The method according to  claim 4 , wherein the focusing optic has a focus depth of at least 2 mm. 
     
     
         7 . The method according to  claim 1 , wherein the at least one through-hole is flushed with compressed air at its entry to the working gap. 
     
     
         8 . The method according to  claim 1 , wherein an excess pressure with respect to the working gap is generated in the at least one through-hole. 
     
     
         9 . The method according to  claim 3 , further comprising at least one protective window that is configured to be at least partially transparent to optical radiation from the optical radiation source of the at least one optical thickness measurement apparatus and is disposed in the at least one through-hole between the at least one optical thickness measurement apparatus and the working gap. 
     
     
         10 . The method according to  claim 9 , wherein the at least one protective window is comprised of aluminum oxide or calcium fluoride. 
     
     
         11 . The method according to  claim 9 , wherein the at least one protective window is recessed not more than 10 mm with respect to a surface defining the working gap. 
     
     
         12 . The method according to  claim 11 , wherein the at least one protective window is cleaned from the surface defining the working gap by a cleaning apparatus using a cleaning fluid. 
     
     
         13 . The method according to  claim 1 , wherein multiple through-holes are disposed in at least one of the upper working disk or the lower working disk and are configured to allow the thickness of the workpiece to be optically measured during the processing of the workpiece. 
     
     
         14 . The method according to  claim 13 , wherein the workpiece thickness is measured through the multiple through-holes simultaneously during the processing of the workpiece. 
     
     
         15 . The method according to  claim 13 , wherein the workpiece thickness is measured through the multiple through-holes at different times during the processing of the workpiece. 
     
     
         16 . The method according to  claim 1 , wherein the double-sided processing machine is configured to process multiple workpieces simultaneously, and wherein the measurement results of the at least one optical thickness measurement apparatus are allocated to one workpiece. 
     
     
         17 . The method according to  claim 1 , wherein the at least one optical thickness measurement apparatus is coupled to a dampener. 
     
     
         18 . The method according to  claim 1 , wherein the control apparatus is positioned away from the upper working disk and the lower working disk. 
     
     
         19 . The method according to  claim 18 , further comprising at least one sliding contact configured to effect data transfer between the at least one optical thickness measurement apparatus, the control apparatus, and an electrical supply of the at least one optical thickness measurement apparatus.