Multi-point spot welding machine controller

Claim 1

A multi-point spot welding controller comprising a central processing unit, a memory means, a monitoring interface means, a system bus, an input means, a first display means, a second display means, an output interface means, a switch output interface means, and a plurality of spot welding circuits; said central processing unit together with said memory means constituting a central control means for controlling an operation of said spot welding controller; said monitoring interface means being electrically connected to said central processing unit and allowed to be electrically connected to an external personal computer by which a user operates to monitor and control said spot welding controller; said system bus being electrically connected between said central processing unit and said memory means for data communication therebetween; said input means being electrically connected to said system bus for inputting a set of predetermined spot welding parameters; said switch output interface means being electrically connected to said system bus for controlling said welding electrodes to move up or down, to respectively start or stop a welding operation; said output interface means being electrically connected to said system bus for sending a plurality of welding signals; said spot welding circuit being electrically connected to said output interface means for receiving said welding signals therefrom and responsive to drive or stop driving a pair of welding electrodes connected thereto; said first display means and said second display means being electrically connected to said system bus for displaying conditions; said multi-point spot welding controller further comprising: a welding circuit comprising a plurality of substantially identical subcircuits; means for positioning said workpieces in a welding platform; means for activating a welding machine having a plurality of pairs of welding electrodes, each pair of said welding electrodes being connected to one of said subcircuits comprising a transformer and a pair of silicon-controlled rectifiers (SCPs); means for checking whether said workpieces and said welding electrodes of said welding machine are positioned in respective predetermined relative positions; means associated with said output interface means for sending welding signals to at least one sub circuit corresponding to a predetermined welding location; means for preheating said workpieces for a predetermined period of time, said preheating being provided by setting the phase angles of said pair of silicon-controlled rectifiers associated with a selected pair of welding electrodes not equal to zero so as to allow an AC power to be transmitted to said welding electrodes via said transformer connected thereto; means for first resting said electrodes by turning off said preheating for a predetermined period of time; means for applying welding on said workpieces for a predetermined period of time, said welding being provided by setting the phase angles of said pair of silicon-controlled rectifiers not equal to zero so as to allow an AC power to be transmitted to said welding electrodes via said transformer; means for second resting said electrodes by turning off said welding for a predetermined period of time; means for applying heat compensation on said workpieces for a predetermined period of time, said heat compensation being provided by setting the phase angles of said pair of silicon-controlled rectifiers not equal to zero so as to allow an AC power to be transmitted to said welding electrodes via said transformer; means for holding said workpieces, to which said heat compensation has been applied, for a predetermined period of time: and means associated with a pair of switches on said silicon controller rectifiers for sending said welding signals to other intended welding locations.