BELT GRINDING METHOD

PURPOSE:To make the quantity of grinding constant at all time by detecting sparks incurred between a grinding belt and a ground surface in a contact roll pressing section, and thereby controlling pressing force in such a way that the quantity of incurred sparks, which can be obtained with detected signals worked up through image processing, is in a set range. CONSTITUTION:The belt grinding device 1 has a grinding belt 2 installed between a drive pulley 3 and a driven pulley 4, and has the grinding belt 2 pressed against the ground surface of a thick steel plate 6 by a contact roll 5. In this case, the device is provided with a camera 7 with a shutter function detecting grinding sparks F incurred between the grinding surface of the thick steel plate 6 and the grinding belt 2. The grinding sparks F are intermittently photographed by the camera 7, photographed image information is worked up by an image processing means 21, and an operation processing means 22. the result is compared with a set value thereafter, and the pressure of a cylinder mechanism 13 is controlled via a pressing force control means 23 based on control variable signals obtained as mentioned above, so that the pressing force of the contact roll 5 is thereby controlled in such a way that the quantity of incurred sparks is in an allowable range.