Patent ID: 7125452
Filing Date: 2006-10-24
Classification: C30B,F27D,Y10T

Abstract:
1. Process for calibrating the temperature control unit of an oven producing a fused material, in particular of a vertical gradient freeze crystal growth oven in which a crucible is surrounded by resistance heaters operating stacked one on top of the other or separately and in which at least one control temperature indicator is provided for each individual resistance heater that controls the heat output of each resistance heater, characterized by the fact that the temperature at the level of the individual control temperature indicators of the oven is measured after turning on the resistance heaters via a reference temperature indicator that can be fully inserted in the oven during the calibration process, and first the output of the respective resistance heater is set to a desired temperature as measured by the reference temperature indicator, and by the fact that thereby the difference with the temperature of the respective control temperature indicator is determined, and that after removal of the reference temperature indicator the calibration process is terminated by comparing the temperature differences between the reference temperature indicators and the control temperature indicators and the desired temperature differences specified for the oven and the respective calculation of the corrective offsets for the control temperature indicators, and by the fact that the oven subsequently is operated according to the control temperature indicators taking into consideration the corrective offsets determined during calibration, wherein a test body instead of a fused body is used for the calibration that does not melt at the oven temperature and that has a comparable heat conductivity as the fused material, a central bore and a geometry that approximates that of the crystal to be grown and has an axial bore for inserting the reference temperature indicator.