Apparatus and method for monitoring weld quality
First Claim
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1. A method for monitoring change in weld resistance of a test weld produced by a resistance welding apparatus comprising the steps of:
- 1) measuring a first voltage drop across a reference weld;
2) measuring a first current through the reference weld;
3) measuring a second voltage drop across the test weld;
4) measuring a second current through the test weld;
5) Obtaining the difference between said first current and said first voltage to provide a reference value;
6) obtaining the difference between said second current and said second voltage to provide a change value; and
7) comparing said change value to said reference value to determine the magnitude of change in weld resistance.
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Abstract
An apparatus and method for monitoring weld quality and for establishing a proper amount of weld energy and the upper and lower limits of the proper weld energy to be supplied by a precision resistance welding apparatus in order to produce acceptable welds. In the present apparatus and method the difference between the change in voltage and current supplied to a test weld is compared to a reference weld and this difference is used to obtain the upper and lower limits of the proper amount of energy to be supplied by the welder in a production context.
16 Citations
17 Claims
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1. A method for monitoring change in weld resistance of a test weld produced by a resistance welding apparatus comprising the steps of:
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1) measuring a first voltage drop across a reference weld; 2) measuring a first current through the reference weld; 3) measuring a second voltage drop across the test weld; 4) measuring a second current through the test weld; 5) Obtaining the difference between said first current and said first voltage to provide a reference value; 6) obtaining the difference between said second current and said second voltage to provide a change value; and 7) comparing said change value to said reference value to determine the magnitude of change in weld resistance. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A weld monitoring apparatus comprising:
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electrode means for contacting elements to be bonded together; a source of electric power connected to the electrode means for supplying welding energy thereto; binary programmable amplifying means for selectively amplifying the weld voltage input and the weld current input; negative precision rectifying means for further processing the weld voltage and weld current; and means for determining the difference between the amplified voltage and current, the magnitude of the difference thereby indicating the change in weld resistance relative to a reference resistance. - View Dependent Claims (15, 16, 17)
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Specification