Welder Safety Sensor for Pinch-Point Protection
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Solution Overview
Problem
Operators of resistance welding machines are at risk of serious injury due to high force concentrations at pinch points between electrodes, with existing safety systems relying on operator adjustments that can be inaccurate and prone to mechanical errors, compromising safety during normal production or electrode adjustments.
Innovation Solution
A safety sensor system that monitors continuity between welding electrodes, preventing high force application if continuity with a low-impedance material is not detected, ensuring that electrodes only clamp on low-resistance materials and not on high-resistance body parts, thus providing passive pinch-point protection independent of operator adjustments and electrode position changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a limit switch with adjustable finger is used to detect electrode spacing, then the safety system can prevent high force application when fingers are between electrodes, but the accuracy and reliability of the safety system depends on operator skill and may be compromised by electrode movement or replacement
Solution Approach 1:
The safety sensor system automatically detects electrode spacing and adjusts safety parameters without requiring operator intervention. The system self-calibrates and maintains accurate spacing detection throughout production, eliminating the need for manual adjustments by setup personnel and ensuring consistent safety performance even when electrodes are moved or replaced.
Solution Approach 2:
The patent replaces the mechanical limit switch system with adjustable finger and cam-based positioning with an electronic sensor system. This substitution eliminates mechanical adjustment errors and provides more reliable, consistent spacing detection that is not dependent on operator skill or prone to mechanical wear and drift.
2Adaptability or versatility
If the electrodes are moved during normal production or electrode replacement to adjust spacing, then production flexibility is improved, but the safety of the system is compromised if the limit switch is not adjusted properly
Solution Approach 1:
The safety sensor system continuously monitors electrode spacing and provides real-time feedback to the control system. When electrodes are moved or replaced, the sensor automatically detects the new spacing and adjusts the safety parameters accordingly, ensuring that the safety system remains reliable even when production flexibility requires spacing changes.
3Object-affected harmful factors
If a mechanically or pneumatically moved sensing arm is used to detect part presence, then the system can prevent welding on high-resistance materials, but the system requires precise mechanical adjustment and can be rendered useless if the sensing arm is bent out of position
Solution Approach 1:
The patent replaces the mechanically moved sensing arm with an electronic sensor system that detects part presence and material resistance properties. This electronic system eliminates the mechanical adjustment and positioning requirements, making the system more robust and easier to operate while maintaining the ability to detect and prevent welding on high-resistance materials.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system effectively prevents serious pinch-point injuries by ensuring that high electrode force is only applied when continuity with a low-resistance material is detected, enhancing safety and reducing the risk of operator injury regardless of electrode spacing changes.
Implementation Method 1
The safety sensor monitors continuity between the welding electrodes when the welding machine has been initiated and during closure of the electrodes under low force. The safety sensor prevents application of high electrode force between the electrodes if the continuity measured does not change at least by a threshold amount indicating contact with a low-impedance material for welding.
Data Source
AI summary
A continuity sensor determines continuity between welding electrodes by detecting a change in a voltage of a sensed tracer signal across the electrodes from a time when a weld cycle is initiated to a time when the electrodes contact material to be welded. As the electrodes are brought together with low force, the continuity sensor detects changes in the sensed voltage level exceeding a threshold thereby representing continuity and enables the welder to apply the higher welding force. However, if the continuity sensor does not detect a change in the voltage signal, then the welder will not apply the full welding force, thereby preventing pinch-point injury to the operator. The digital continuity sensor reestablishes a baseline for detecting the change in voltage with every new weld cycle such that the digital continuity sensor is not subject to changing voltages or changes in the welder configuration.