SURFACE POLISHING DEVICE WITH MACHINING PRESSURE CORRECTING MECHANISM

PURPOSE:To improve machining precision of a work, by a method wherein the weight of an upper surface plate is measured by a sensor, the pressure of fluid, which is fed to a cylinder head, is regulated by a wear amount. CONSTITUTION:When machining is completed, fluid in a head chamber 17a is discharged, an upper surface plate 11 is raised by means of a force exerted on a second piston 19, and in this case, a weight W of the upper surface plate 11 is measured by means of a sensor 21. A measurement signal from the sensor 21 is inputted to a control circuit 26 to compare it with a previously inputted reference value, and the wear amount of the upper surface plate 11 is determined as a difference therebetween. A control signal responding to the difference is outputted from the control circuit 26 to a pressure control valve 25, and a fluid pressure, fed to a head chamber 17a of a cylinder 17 during subsequent machining, is increased. Thus, the fluid pressure is increased by an amount equivalent to the decreased weight W of the upper surface plate 11 to keep a machining pressure at a specified value. This constitution enables improvement of machining precision of a work.