Method and apparatus for manufacturing vitreous silica crucible

Abstract

Accurate temperature measurement during manufacturing a vitreous silica crucible is enabled. The present invention provides an apparatus for manufacturing a vitreous silica crucible including: a mold for forming a silica powder layer by supplying silica powder therein; an arc discharge unit having carbon electrodes and a power supply unit and for heating and fusing the silica powder layer by arc discharge; and a temperature measurement unit for measuring temperature of a fused portion in the mold, wherein the temperature measurement unit is an radiation thermometer for measuring temperature by detecting radiation energy of a wavelength of 4.8 to 5.2 μm.

1 . An apparatus for manufacturing a vitreous silica crucible comprising:
 a mold for forming a silica powder layer to manufacture a crucible by supplying silica powder therein;   an arc discharge unit having carbon electrodes and a power supply unit and for heating and fusing the silica powder layer by arc discharge; and   a temperature measurement unit for measuring temperature of a fused portion in the mold, wherein   the temperature measurement unit is a radiation thermometer for measuring temperature by detecting radiation energy of a wavelength of 4.8 to 5.2 μm.   
     
     
         2 . The apparatus of  claim 1 , further comprising a filter made of BaF 2  or CaF 2 . 
     
     
         3 . The apparatus of  claim 1 , wherein the temperature measurement unit has a range of a measuring temperature of 400 to 2800 deg. C. 
     
     
         4 . The apparatus of  claim 1 , wherein the temperature measurement unit detects the radiation energy at a corner portion of the vitreous silica crucible. 
     
     
         5 . The apparatus of  claim 1 , further comprising a controller for controlling the fused state of vitreous silica by changing, based on the measurement result from the temperature measurement unit, any of the amount of current supplied to the carbon electrodes, the position of the carbon electrodes, the relative position of the mold and the carbon electrodes, and the position of the mold. 
     
     
         6 . A method of manufacturing a vitreous silica crucible by use of the apparatus of  claim 1  comprising:
 a silica powder supplying process of supplying silica powder into a mold for molding a crucible, to form a silica powder layer; and 
 an arc fusing process of arc fusing the silica powder layer by arc discharge generated by carbon electrodes, wherein 
 at least the arc fusing process include a temperature measuring process of measuring temperature of a fused portion in the mold by detecting radiation energy of a wavelength of 4.8 to 5.2 μm by a temperature measurement unit which is a radiation thermometer. 
 
     
     
         7 . The method of  claim 6 , wherein, in the temperature measurement process, the temperature measurement unit measures the temperature through a filter made of BaF 2  or CaF 2 . 
     
     
         8 . The method of  claim 6 , wherein, in the temperature measurement process, the range of the measuring temperature of the temperature measurement unit is set to be 400 to 2800 deg. C. 
     
     
         9 . The method of  claim 6 , wherein, in the temperature measuring process, the temperature measurement unit detects the radiation energy at a corner portion of the vitreous silica crucible. 
     
     
         10 . The method of  claim 6 , wherein, in the temperature measuring process, the fused state of vitreous silica is controlled by changing, based on the measurement result from the temperature measurement unit, any of the amount of current supplied to the carbon electrodes, the position of the carbon electrodes, the relative position of the mold and the carbon electrodes, and the position of the mold.