GB1262713A - Means for adjusting the speed of a grinding wheel - Google Patents

Abstract

1,262,713. Grinding. ALLMANNA SVENSKA ELEKTRISKA A.B. 26 June, 1969 [28 June, 1968], No. 32245/69. Heading B3D. Means for adjusting the speed of a grinding wheel as it wears down by monitoring the wheel diameter, includes at least one nozzle through which gas is blown substantially parallel to the wheel axis, and at least one sensing member to sense the pressure in or near the gas nozzle, which pressure is dependent on the position of the nozzle in relation to the wheel periphery, and provides an output signal for transmission to control means to adjust the wheel speed. In a first embodiment, Fig. 4, a set of spatially fixed nozzles 11-16 are provided in a pressure space 20, each having a central sensing tube 21-26 connected to a respective pressureoperated switch 33-38 for by-passing resistances R 1 -R 6 respectively in a resistor bridge circuit. As the grinding wheel 17 wears down, the gas streams sequentially cease to impinge on its axial face, and the pressure in the sensing tubes changes from slightly super-atmospheric to slightly sub-atmospheric. Diaphragms 41 in the switches 33-38 successively short out each resistance R 1 -R 6 to change the electric output signal across resistance Ru, variation in this parameter controlling the speed of a grinding wheel motor. Alternatively, Figs. 7, 8, a single monitoring means 81 is mounted on a pivotable arm 82 to follow the contour of the grinding wheel 80, a spring 86 biasing the arm upwardly and outwardly, while the pressure in the sensing tube 90 connected to a bellows 87 balances the spring force when the monitoring means is adjacent the wheel periphery. A potentiometer output signal dependent on the angle of the arm 82 governs the motor speed. In a similar embodiment, Figs. 5-6 (not shown), the sensing tube of a single monitoring means may control, through a pressure-operated switch (63) a motor (54) for raising or lowering the pivotable arm (52).