Neural network control of spot welding
First Claim
1. A spot welder, comprising:
- at least two electrodes having tips engageable with a stack-up of material;
a power supply for energizing said electrodes to spot weld said stack-up when said electrodes are engaged with said stack-up;
a current sensor coupled to said power supply and generating a first signal representative of current supplied to said electrodes;
a voltage sensor coupled to said power supply and generating a second signal representative of voltage across said electrodes and said stack-up;
a neural network for processing, in real time, data representative of said first and second signals for a weld in progress according to a learning rule determined by data from previous welds, said neural network generating a predicted time of optimal weld strength for said weld in progress; and
,a controller responsive to said neural network for terminating said weld in progress responsive to said predicted optimal time.
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Abstract
A spot welder comprises a neural network for processing, in real time, current and voltage energizing a weld in progress. The neural network generates a predicted time of optimal weld strength and/or nugget size for the weld in progress. A controller terminates the weld in progress at the predicted time. A method for controlling a spot welder comprises the steps of: sensing in real time current and voltage energizing a spot weld in progress; predicting a time of optimal weld strength and/or nugget size with a neural network responsive to the sensed current and voltage; and, terminating the weld in progress at the predicted time. A sensor for electromotive forces (EMF) induced by the spot welder can generate a signal for canceling out a large fraction of EMF components in at least one or both of the current and voltage signals. EMF components are substantially precluded in the current signal if the current sensor uses a buried shunt. Termination of the weld in progress at the predicted time is prevented when the predicted time precedes a predetermined minimum weld duration. The weld in progress is terminated at a predetermined maximum weld duration when the predicted time is after the predetermined maximum weld duration.
135 Citations
22 Claims
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1. A spot welder, comprising:
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at least two electrodes having tips engageable with a stack-up of material; a power supply for energizing said electrodes to spot weld said stack-up when said electrodes are engaged with said stack-up; a current sensor coupled to said power supply and generating a first signal representative of current supplied to said electrodes; a voltage sensor coupled to said power supply and generating a second signal representative of voltage across said electrodes and said stack-up; a neural network for processing, in real time, data representative of said first and second signals for a weld in progress according to a learning rule determined by data from previous welds, said neural network generating a predicted time of optimal weld strength for said weld in progress; and
,a controller responsive to said neural network for terminating said weld in progress responsive to said predicted optimal time. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. An improved controller for a spot welder having current and voltage sensors for generating respective signals representative of current and voltage levels during a spot weld in progress, the improvement comprising:
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a neural network for processing, in real time, data representative of said respective signals for said spot weld in progress according to a learning rule determined by data from previous welds, said neural network generating a predicted time of optimal weld strength for said weld in progress; and
,a controller responsive to said neural network for terminating said weld in progress responsive to said predicted time of optimal strength. - View Dependent Claims (11, 12, 13, 14, 15)
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16. A method for controlling a spot welder, comprising the steps of:
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sensing in real time current and voltage levels energizing a spot weld in progress; predicting a time of optimal weld strength with a neural network responsive to said sensed current and voltage levels according to a learning rule determined by data from previous welds; and
,terminating said weld in progress responsive to said predicted time of optimal weld strength. - View Dependent Claims (17, 18, 19, 20)
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21. A spot welder, comprising:
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at least two electrodes having tips engageable with a stack-up of material; a power supply for energizing said electrodes to spot weld said stack-up when said electrodes are engaged with said stack-up; a current sensor coupled to said power supply and generating a first signal representative of current supplied to said electrodes; a voltage sensor coupled to said power supply and generating a second signal representative of voltage across said electrodes and said stack-up; a neural network for processing, in real time, data representative of said first and second signals for a weld in progress according to a learning rule determined by data from previous welds, said neural network generating a predicted time of optimal nugget size for said weld in progress; and
,a controller responsive to said neural network for terminating said weld in progress responsive to said predicted time of optimal nugget size.
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22. A method for controlling a spot welder, comprising the steps of:
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sensing in real time current and voltage levels energizing a spot weld in progress; predicting a time of optimal weld strength with a neural network responsive to said sensed current and voltage levels according to a learning rule determined by data from previous welds; and
,terminating said weld in progress responsive to said predicted time of optimal nugget size.
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Specification