Progressive current limit control for a resistance welder
First Claim
1. A weld controller system for controlling the operation of a welder including a weld transformer and at least one pair of contact tips that apply current to create weld heat between at least two workpieces, said weld controller having a plurality of welding cycles, said weld controller system comprising:
- A. a microprocessor;
B. welder power means controlled by a program operating in said microprocessor and operatively connected to said weld transformer for supplying weld current to said contact tips to create said weld heat in said workpieces, said program for increasing said weld heat in increments following a predetermined stepper program having a plurality of weld cycles to provide compensation for deterioration of said contact tips wear;
C. a current sensor for sensing current supplied by said welder power means to said weld transformer, said current sensor for providing weld current data for use by said program;
D. a current limit control having an upper current threshold and a lower current threshold, said current limit for comparing said sensed weld current data with a current profile at each of said plurality of weld cycles, said current limit control for indicating an event condition if said sensed weld current data exceeds said upper current threshold or is below said lower current threshold; and
E wherein said upper current threshold and said lower current threshold track said current profile by a predetermined current offset at each of said plurality of weld cycles.
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Accused Products
Abstract
A weld controller employs a stepper program for increasing heat boost in one percent increments or steps to provide compensation for contact tip wear. The weld controller acquires weld current data in the form of current samples for each step to create a characteristic curve or nominal current profile for the stepper program. Subsequent operations of the weld control utilize high and low current limit thresholds that track the nominal current profile. The thresholds can be defined as a fixed offset from the profile or as a percentage of the profile at each step of the stepper program. This allows the use of current limits to be established in close proximity to the nominal weld current at all times, enabling the use of tighter tolerances.
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Citations
23 Claims
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1. A weld controller system for controlling the operation of a welder including a weld transformer and at least one pair of contact tips that apply current to create weld heat between at least two workpieces, said weld controller having a plurality of welding cycles, said weld controller system comprising:
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A. a microprocessor; B. welder power means controlled by a program operating in said microprocessor and operatively connected to said weld transformer for supplying weld current to said contact tips to create said weld heat in said workpieces, said program for increasing said weld heat in increments following a predetermined stepper program having a plurality of weld cycles to provide compensation for deterioration of said contact tips wear; C. a current sensor for sensing current supplied by said welder power means to said weld transformer, said current sensor for providing weld current data for use by said program; D. a current limit control having an upper current threshold and a lower current threshold, said current limit for comparing said sensed weld current data with a current profile at each of said plurality of weld cycles, said current limit control for indicating an event condition if said sensed weld current data exceeds said upper current threshold or is below said lower current threshold; and E wherein said upper current threshold and said lower current threshold track said current profile by a predetermined current offset at each of said plurality of weld cycles. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A weld controller system for controlling the operation of a welder including a weld transformer and at least one pair of contact tips that apply weld current to create weld heat between at least two workpieces, said weld controller having a plurality of welding cycles, said weld controller including a current limit control for limiting said weld current between an upper and a lower current threshold, said system comprising:
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A. a microprocessor; B. a program operating in said microprocessor, said program for increasing said weld heat in increments following a predetermined stepper program having a plurality of weld cycles; C. a current sensor for sensing current applied to said weld transformer, said current sensor for providing weld current data for use by said program; D. a comparison means for comparing said sensed weld current data with a predetermined current profile at each of said plurality of weld cycles, and for indicating an event condition if said sensed weld current data exceeds said upper current threshold or is below said lower current threshold; and E wherein said upper current threshold and said lower current threshold track said current profile by a predetermined current offset at each of said plurality of weld cycles. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19)
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20. A progressive current limit control system for use with a resistance welder, said system comprising:
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A. a microprocessor; B. a stepper program operating in said microprocessor, said program for increasing weld heat in increments following said stepper program and said stepper program having a plurality of weld cycles; C. a current sensor for sensing a weld current of said welder, said current sensor for providing weld current data; D. a current profile; E. a comparison means for comparing said sensed weld current data with an upper current threshold and a lower current threshold relative to said current profile at each of said plurality of weld cycles, and for indicating an event condition if said sensed weld current data exceeds said upper current threshold or is below said lower current threshold; and F. wherein said upper current threshold and said lower current threshold track said current profile by a predetermined current offset at each of said plurality of weld cycles. - View Dependent Claims (21, 22, 23)
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Specification