Resistance welding sequence cycle control
First Claim
1. The method of controlling the cycle of operation of a resistance welding device which includes a movable electrode assembly and a cycle of operation having a flight cycle portion during which the movable electrode assembly is advanced toward the work by a motive means, a squeeze cycle portion during which electrodes are maintained in pressure contact with the work, a weld cycle portion during which weld current is activated and a hold cycle portion during which pressure contact between electrodes and work is maintained subsequent to the activation of weld current comprising the steps of:
- sensing the velocity of said movable electrode assembly during said flight cycle portion,comparing the sensed velocity to a predetermined velocity value, andaltering the length of the squeeze cycle portion as a function of the comparison of said sensed velocity to said predetermined velocity value.
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Accused Products
Abstract
A method and apparatus are shown for controlling the cycle of a resistance welding device by providing compensation for variations in the effective weld area and the primary input electric power variations through a composite correction applied to the length of the squeeze time cycle portion prior to the weld cycle portion when weld current is activated. Compensation is made for secondary weld current variations by altering the length of the hold cycle, during which electrode contact is maintained with the work subsequent to the weld cycle portion, to change the amount of heat quenched from the weld zone. Further by sensing the condition wherein either the electrical input or the motive power that drives the movable electrode is beyond correctable limits, the welding cycle is aborted when suitable quality welds cannot be made.
40 Citations
15 Claims
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1. The method of controlling the cycle of operation of a resistance welding device which includes a movable electrode assembly and a cycle of operation having a flight cycle portion during which the movable electrode assembly is advanced toward the work by a motive means, a squeeze cycle portion during which electrodes are maintained in pressure contact with the work, a weld cycle portion during which weld current is activated and a hold cycle portion during which pressure contact between electrodes and work is maintained subsequent to the activation of weld current comprising the steps of:
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sensing the velocity of said movable electrode assembly during said flight cycle portion, comparing the sensed velocity to a predetermined velocity value, and altering the length of the squeeze cycle portion as a function of the comparison of said sensed velocity to said predetermined velocity value. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. The method of controlling the resistance welding cycle of a resistance welding device having a movable electrode assembly and including device welding cycle operation with a flight time
cycle portion during which the movable electrode assembly closes to a position of contact with the work, a squeeze time portion during which electrode pressure contact is maintained with the work prior to a weld cycle portion during which weld current is activated comprising: -
sensing electrode assembly velocity during said flight time cycle portion; comparing said velocity to a predetermined velocity value; sensing the welding device input power supply voltage; comparing said sensed voltage with a predetermined voltage value; altering the length of said squeeze time cycle portion by a composite correction which is the sum of the corrections resulting from said velocity comparison and said voltage comparison, whereby the effective weld contact area is corrected to effect a proper weld current density. - View Dependent Claims (10, 11)
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12. In combination with a resistance welding device including a transformer power supply and a movable electrode assembly which has a cycle of operation includng a flight time portion during which the movable electrode assembly moves from a retracted position to a position of contact with the work, a squeeze time portion during which the electrodes are retained in pressure contact with the work prior to weld current activation, a weld cycle portion during which weld current is activated and a hold cycle during which the electrodes are maintained in contact with the work subsequent to the weld cycle portion;
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controller means; first sensing means connected to said controller means for sensing movable electrode assembly velocity during said flight time portion; and first adjusting means for adjusting the time duration of said squeeze time portion as a function of the output of said first sensing means. - View Dependent Claims (13, 14, 15)
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Specification