SPOT WELDING GUN, AND METHOD FOR CONTROLLING PRESSURIZING FORCE OF SPOT WELDING GUN

摘要

PPROBLEM TO BE SOLVED: To suppress a fluctuation in pressurizing force caused by the influence of heat in a spot welding gun driven by a servomotor, and to obtain the more uniform pressurizing force. PSOLUTION: During position control, the position control is performed based on a migration command r and a position feedback content y, and a torque command (current command) is obtained, and a servomotor is driven to move welding tips (S1, S6). The difference between the temperature T detected by a temperature sensor and the initial temperature TO is multiplied by a coefficient A, and the correction quantity of the pressurizing force is previously obtained (S3, S4). On transition to the control of the pressurizing force, the correction quantity of the pressurizing force is reduced from the command pressurizing force p, and command pressurizing force p' subjected to temperature correction is obtained (S8, S9). The value obtained by reducing estimated pressurizing force d estimated by an observer from the command pressurizing force p' is multiplied by a constant K2 to obtain a torque command (current command) , and the servomotor is driven to pressurize the object to be welded by the welding tips (S2, S10, S7). Since the command pressurizing force has been subjected to temperature correction, stable, uniform pressurizing force can be obtained without being affected by a change in temperature. PCOPYRIGHT: (C)2004,JPO