Flash welding apparatus and method

• US 4,376,242 A
• Filed: 01/30/1980
• Issued: 03/08/1983
• Est. Priority Date: 01/30/1976
• Status: Expired due to Term

• Current Assignee: LTV Steel Company, Inc. (LTV Corp.)
• Original Assignee: Republic Steel Corp. (LTV Corp.)
• Inventors: Buff, Grier E., Phillips, Talmadge V.
• Primary Examiner(s): Shaw, C. C.
• Application Number:
  US06/117,031
• Time in Patent Office: 1,133 Days
• Field of Search: 219/97, 219/100, 219/109, 219/110
• US Class Current: 219/97
• CPC Class Codes: B23K 11/043 characterised by the electric circuits used therewith
• CPC Class Codes: B23K 11/246 for flash welding

Abstract

Improved apparatus and method for performing flash welding is disclosed. The apparatus moves adjacent surfaces of workpieces toward each other and applies electrical energy between them for flash heating the surfaces in a flashing step, after which it forces the surfaces together in an upsetting step, while continuing the application of the electrical energy for a predetermined time. Apparatus is provided for calculating and monitoring the amount of electrical energy applied to the workpieces during welding, along with control circuitry, for limiting the amount of electrical energy applied during the upset step to a predetermined function of that applied during the flashing step. An energy recorder produces an indication of the amount of electrical energy applied to the workpieces during welding.

Claims

1. A welder comprising:

(a) apparatus for applying heating energy to effect welds between workpieces in a plurality of steps;

(b) sensing apparatus for producing a signal representing the amount of heating energy applied in one of said steps; and

(c) control apparatus responsive to the sensing apparatus for controlling the amount of heating energy applied in another of said steps as a function of the energy applied in said one step, said function having a positive first derivative over a range of energy sensed in said one step.

2. The welder of claim 1, wherein:

(a) said welder is a flash welder for effecting welds in accordance with a flashing step and an upsetting step; and

(b) said control apparatus comprises circuit means for limiting the energy applied in the upsetting step as a predetermined function of the energy applied in the flashing step.

3. The welder of claim 2, wherein:

said predetermined function is a direct proportion.

4. The welder of claim 2 wherein said control apparatus further comprises:

adjustment circuitry for varying said predetermined function.

5. The welder of claim 3 wherein said control apparatus further comprises:

adjustment circuitry for varying said predetermined function.

6. 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.

7. The method of claim 6, wherein:

(a) said first welding step is a flashing step;

(b) said second welding step is an upsetting step; and

(c) said controlling step comprises limiting the electrical energy applied in the upsetting step to a predetermined function of the electrical energy applied in the flashing step.

8. The method of claim 7, wherein:

said predetermined function is a direct proportion.

9. The method of claim 8, further comprising the step of:

adjustably varying said predetermined function.

10. In a flash welder of the type having means for applying electrical heating energy and mechanical energy for effecting flashing and upsetting steps for welding workpieces together, the improvement comprising the combination of:

(a) an energy monitor for sensing and storing a representation of the amount of electrical energy applied in the flashing step; and

,

(b) a control circuit connected to the energy monitor for controlling the amount of electrical energy applied in the upsetting step as a 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 flashing step energy.

11. 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.

12. 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.

13. The system of claim 12, further comprising:

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.

14. 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.

15. 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.

16. 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.

17. The welder of claim 16, wherein:

(a) said welder is a flash welder for effecting welds in accordance with a flashing step and an upsetting step, and

(b) said control apparatus comprises circuit means for limiting the energy applied in the upsetting set as a predetermined function of the energy applied in the flashing step.

18. The welder of claim 17, wherein:

said predetermined function is a direct proportion.

19. The welder of claim 17, wherein said control apparatus further comprises:

adjustment circuitry for varying said predetermined function.

20. The welder of claim 18, wherein said control apparatus further comprises:

adjustment circuitry for varying said predetermined function.

21. A welding method comprising the steps of:

(a) applying electrical energy to effect welds between workpieces in a plurality of steps;

(b) producing a signal representing the amount of electrical energy applied in one of said steps, and

(c) 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.

22. A flash welder comprising:

(a) apparatus for effecting flash welds by applying heating energy between workpieces in accordance with a flashing step and an upsetting step;

(b) sensing apparatus for producing a signal representing the amount of heating energy applied in said flashing step, and

(c) control apparatus responsive to the sensing apparatus for limiting the energy applied in the upsetting step as a predetermined function of the amount of energy applied in the flashing step, said function having a positive first derivative over a range of sensed flashing step energy.

23. The welder of claim 22, wherein:

said predetermined function is linear.

24. The welder of claim 22, wherein said control apparatus further comprises:

adjustment circuitry for varying said predetermined function.

25. The welder of claim 23, wherein said control apparatus further comprises:

adjustment circuitry for varying said predetermined function.

26. 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.

27. The method of claim 26, wherein:

said predetermined fraction is a direct proportion.

28. The method of claim 27, further comprising the step of:

adjustably varying said predetermined function.

29. 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.