| 摘要 |
PURPOSE:To prevent the falling of a Y-stage and a loaded member by also lowering the internal pressure of an air pressure release brake simultaneously with the lowering of the pressure in the air cylinder supporting the own wt. of the Y-stage and controlling a rotary actuator. CONSTITUTION:An air cylinder 13 supports a Y-stage 5 and the loaded member thereon by injecting compressed air and the Y-stage 5 has the degree of freedom of direct action in a vertical direction by a direct-acting or rotary actuator 15 consisting of a ball screw 16 and a servo motor 17. An air pressure release brake 24 and a cylinder 30 are connected by a pipe 30 and always equal air pressure is supplied thereto and, when compressed air is injected in the brake 24, a brake shoe 27 is separated from a friction disc 26 against the energizing force of a compression spring 28 and the screw 16 becomes freely rotatable. When the air pressure in the cylinder 13 is lowered to a degree incapable of supporting the own wt. of the stage 5 by any trouble, the internal pressure of the brake 24 is also lowered simultaneously and the shoe 27 and the friction disc 26 are brought to a close contact state by the energizing of the spring to brake the screw 16 and the falling of the stage 5 and the loaded member thereon is prevented. |
