Opening/closing control device of chuck

An opening/closing control device of a chuck which carries out an opening and closing motion of a chuck (12) gripping a work (W) on the basis of a movement in an axial direction of an operation rod (15) coupled to a claw (14) of the chuck, the chuck opening/closing control device comprising:

• a stroke sensor (2) which detects a moving position of said operation rod and generates a position signal corresponding to said moving position;
• a controller (3) controlling the opening and closing motion of said chuck, wherein the controller (3) receives said position signal from said stroke sensor (2) and outputs at least one electric signal to control the movement of said operation rod (15);
• and
• an external memory device (4) connectible to said controller which stores a position of said operation rod when said chuck grips and releases said work, in connection with each of a plurality of product types of said work;
• wherein the controller includes
• a setting means (35) which sets a work gripping position (43) and a work releasing position (44) of the work of the product type when the product type of said work is designated,
• a grip detecting means (26) which outputs a grip signal in the case that the detecting position of said stroke sensor and said set work gripping position conform when said operation rod moves in the work gripping direction, and
• a release detecting means (27) which stops the movement in the axial direction of the operation rod in the case that the detecting position of said stroke sensor and said set work releasing position conform when said operation rod moves in the work releasing direction.