Patent ID: 6814558
Filing Date: 2004-11-09
Classification: B29C,F16H,Y10T

Abstract:
A ball screw device which converts the rotation of a ball screw shaft, whose thrust direction is restrained by a fixed member into linear movement of at least a first and a second ball screw nut engaging threadedly with said ball screw shaft to move a working body connected to said ball screw nuts, said ball screw device comprising:a sensor carrying flange which attaches first ball screw nut to said working body; a load sensor which is mounted on said sensor carrying flange; an annular fluid pressure piston which is attached to said second ball screw nut; a fluid pressure cylinder which is attached to said working body and is open on one side, having an annular groove portion in which said piston fits in a fluid-tight manner to form a fluid pressure actuator, and a fluid pressure control unit which is provided on said fluid pressure cylinder to control the fluid pressure so as to produce a piston pushing force equal to the detected load of said load sensor, so that a load applied to said working body is distributed evenly to said at least first and second ball screw nuts.