Flash welding apparatus and method

A method for applying electrical energy to workpieces to effect welds between workpieces in accordance with a plurality of steps, said method comprising the steps of:

• (a) executing a first welding step;
• (b) producing and storing a signal representing the amount of electrical energy applied during said first welding step;
• (c) executing a second welding step;
• and
• (d) controlling the amount of electrical energy applied in the second welding step as a function of the amount of electrical energy sensed as applied in the first welding step, said function having a positive first derivative over a range of energy applied in said first step.

A method for performing successive welding cycles for flash welding together one of a succession of groups of at least two workpiece surfaces, said method for performing each cycle comprising the steps of:

• (a) executing an initial flashing step by:
• (i) moving the workpiece surfaces toward each other;
• and
• (ii) applying an electrical potential between the workpiece surfaces during such motion to cause flash heating of the surfaces;
• (b) monitoring separately the amount of electrical energy so applied in said flashing step;
• and
• (c) subsequently executing an upsetting step by:
• (i) forcing the workpiece surfaces together;
• and
• (ii) continuing the application of electrical potential between the workpieces in an amount which is a function of the amount of electrical energy separately sensed as applied in said flashing step, said function having a positive first derivative over a range of applied flashing energy.

A system for executing a welding cycle for flash welding together a plurality of workpiece surfaces comprising:

• (a) apparatus for executing an initial flashing step comprising:
• (i) apparatus for moving the workpiece surfaces toward each other;
• and
• (ii) means for applying electrical energy between the workpiece surfaces during such motion to cause flash heating of the surfaces;
• (b) apparatus for continuously monitoring the amount of electrical energy applied during the welding cycle, including during the flashing step, by producing total energy output signal continuously representing the instantaneous time integrated electrical power applied during the cycle;
• and
• (c) apparatus for subsequently executing an upsetting step, comprising:
• (i) apparatus for forcing the workpiece surfaces together subsequent to the flashing step;
• and
• (ii) control circuitry for continuing the application of electrical energy to the workpieces for only a predetermined time during the upsetting step, said predetermined time being a function of the amount of electrical energy applied during the flashing step, said function having a positive first derivative.

A system for executing a welding cycle for flash welding together workpiece surfaces, the system comprising:

• (a) apparatus for executing an initial flashing step comprising:
• (i) apparatus for moving the workpiece surfaces toward each other, and
• (ii) means for applying electrical energy between the workpiece surfaces during such motion to cause flash heating of the surfaces;
• (b) apparatus for continuously monitoring the amount of electrical energy applied during the welding cycle, including during the flashing step, by producing a total energy output signal continuously representing the instantaneous time integrated electrical power applied during the cycle;
• (c) apparatus for subsequently executing an upsetting step, comprising:
• (i) apparatus for forcing the workpiece surfaces together subsequent to the flashing step, and
• (ii) control circuitry for continuing the application of electrical energy to the workpieces for a time during the upsetting step, said time being a function of the amount of electrical energy applied during the flashing step, said function having a positive first derivative over a range of applied flashing step energy, and
• (d) apparatus for adjustably varying said function.

A system for executing a welding cycle for flash welding together workpiece surfaces, the system comprising:

• (a) apparatus for executing an initial flashing step comprising:
• (i) apparatus for moving the workpiece surfaces toward each other, and
• (ii) means for applying electrical energy between the workpiece surfaces during such motion to cause flash heating of the surfaces;
• (b) apparatus for continuously monitoring the amount of electrical energy applied during the welding cycle, including during the flashing step, by producing a total energy output signal continuously representing the instantaneous time integrated electrical power applied during the cycle;
• (c) apparatus for subsequently executing an upsetting step, comprising;
• (i) apparatus for forcing the workpiece surfaces together subsequent to the flashing step, and
• (ii) control circuitry for continuing the application of electrical energy to the workpieces for a time during the upsetting step, said time being a function of the amount of electrical energy applied during the flashing step, and
• (d) said control circuitry comprising means for establishing said function as a direct proportion having a positive first derivative.

A welder comprising:

• (a) apparatus for applying electrical energy to effect welds between workpieces in a plurality of steps.
• (b) sensing apparatus for producing a signal representing the amount of electrical energy applied in one of said steps;
• and
• (c) control apparatus responsive to the sensing apparatus for controlling the amount of electrical energy applied in another of said welding steps as a function of the energy applied in said one step wherein greater energy application in said one step results in greater energy application in said another step, and lesser energy application in said one step results in lesser energy application in said another step.

A method for applying electrical energy to workpieces to effect flash welds between such workpieces in accordance with at least a flashing step and an upsetting step, said method comprising the steps of:

• (a) executing a flashing step;
• (b) producing and storing a signal representing the amount of electrical energy applied during said flashing step;
• (c) executing an upsetting step, and
• (d) controlling the amount of electrical energy applied in the upsetting step by limiting such energy as a predetermined function of the amount of electrical energy sensed as applied in the flashing step, said function having a positive first derivative over a range of energy applied in said flashing step.

A system for executing a welding cycle for flash welding together a plurality of workpiece surfaces comprising:

• (a) apparatus for executing an initial flashing step comprising:
• (i) apparatus for moving the workpiece surfaces toward each other;
• and
• (ii) means for applying electrical energy between the workpiece surfaces during such motion to cause flash heating of the surfaces;
• (b) apparatus for continuously monitoring the amount of electrical energy applied during the welding cycle, including during the flashing step, by producing a total energy output signal continuously representing the instantaneous time integrated electrical power applied during the cycle;
• (c) apparatus for subsequently executing an upsetting step, comprising:
• (i) apparatus for forcing the workpiece surfaces together subsequent to the flashing step;
• and
• (ii) control circuitry for continuing the application of electrical energy to the workpieces for only a predetermined time during the upsetting step, said predetermined time being a function of the amount of electrical energy applied during the flashing step, said function having a positive first derivative, and
• (d) an energy recorder connected to the monitoring apparatus for producing an indication of the amount of electrical energy applied to the workpieces during the flashing and upsetting steps.