| 摘要 |
The adaptive controller for a resistance spot welder is implemented with a microcomputer and peripherals to handle the monitoring of several process variable inputs and control the welding machine in real time. Before welding power is applied, electrode load, workpiece thickness and dynamic resistance are measured and must fall within predefined limits in order to continue. The workpiece, if necessary, is conditioned to correct fit-up and surface contamination problems by applying power pulses to lower its resistance. The welding power in each half cycle is dynamically adjusted as a function of workpiece thermal expansion and its first derivative to control formation of the weld nugget, and to control the cooling rate and temper the workpiece. During welding the power limits are adjusted in real time to compensate for electrode flattening and shunt effects. The quality of each weld is diagnosed and machine diagnostics are performed.
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