PURPOSE: To stripe a surface of a work freely in longitudinal, lateral and diagonal directions by using grinding rolls each of which is adapted to be slidingly moved along guide poles provided in a gate type frame rotatable around a lateral shaft.

CONSTITUTION: Gate type frames 21W24, each of which is rotatably supported at the central portion of a side surface thereof on a lateral shaft 6, are provided close to a work carrying conveyor 1. Each of the gate type frames 21W24 is provided with a support frame 12 which is slidingly moved by an operation of a hydraulic cylinder 17, along guide poles 3 provided in the frames 21W24. The support frame 12 is provided with a grinding roll 13 which is driven by a motor 15 and extended at right angles to the guide poles 3. In order to form a pattern of diagonal lines on a work 21, front and rear frames 21, 23 are inclined in the opposite directions to carry out a grinding operation. As a result, a diamond pattern is formed on the surface of the work 21 by the grinding rolls 13 provided on the frames 21, 23.