Welding Tong Electrode Force Sensing With Interference Cancellation
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Solution Overview
Problem
Existing methods for measuring electrode force in welding guns are compromised by external interference forces, such as vibrations and movements, which reduce signal quality by overlaying on the actual force signal and making it difficult to accurately monitor the clamping force during resistance and spot welding.
Innovation Solution
The method involves using two sensors, one on each electrode arm, to measure the forces acting on the electrodes, where external interference forces cancel each other out when added, resulting in a signal that represents only the welding force between the workpiece and electrodes, effectively doubling the amplitude of the signal and improving quality by eliminating interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If force sensors are mounted on the welding gun to measure the force applied by the gun, then the clamping force can be monitored, but external disturbing forces overlay the actual force signal and reduce signal quality
Solution Approach 1:
The measurement system is segmented into two separate force sensors, each measuring forces on individual electrodes. By dividing the measurement into two independent channels, the system can later differentiate between welding forces (affecting both electrodes equally) and disturbing forces (affecting electrodes differently), thereby improving signal quality through selective signal combination.
Solution Approach 2:
The patent converts the harmful effect of disturbing forces into a beneficial differentiation mechanism. Since disturbing forces affect the two electrodes differently while welding forces affect them equally, the system uses this difference to identify and eliminate noise by adding the two force signals, thereby converting the presence of disturbing forces into a means for signal validation and improvement.
2Productivity
If multiple welding tongs or transport devices move the workpiece, then welding operations can be performed, but disturbing forces are introduced that reduce measurement accuracy
Solution Approach 1:
The system continuously monitors forces on both electrodes and provides feedback by adding the two force signals in real-time. This feedback mechanism automatically compensates for disturbing forces introduced during welding operations, allowing productive welding with multiple tongs or transport devices while maintaining accurate force measurement through continuous signal validation and correction.
Data Source
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Figure 3
AI summary
The invention relates to a method for measuring the electrode force on welding tongs (10). The welding tongs (10) have a first electrode arm (14a) with a first electrode (18a) and a second electrode arm (14b) with a second electrode (18b), said second electrode arm lying opposite the first electrode arm (14a). At least one workpiece (24) is clamped between the electrodes (18a, 18b) during the welding process. The aim of the invention is to provide a method for measuring the electrode force, said method providing an improved signal quality. The method has the following steps: a) measuring a first force acting on the first electrode (18a), b) measuring a second force acting on the second electrode (18b), and c) adding the measured first force and the measured second force, wherein an electrode force signal transmitted from the welding point to the electrodes (18a, 18b) is amplified, and an interference force signal introduced into the at least one workpiece (24) from the outside and transmitted to the electrodes (18a, 18b) is eliminated.