Spot Welding Electrode Pressure Control
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Solution Overview
Problem
Existing spot welding methods face challenges with electrode positioning limitations, variable contact pressure due to positional changes and material unevenness, and reduced mobility and efficiency in welding multiple points, leading to unpredictable weld quality and increased rejects.
Innovation Solution
A method and device utilizing paired electrodes arranged on the same surface side of the workpiece with a motor-controlled contact pressure system and a stationary counterhold, allowing for precise regulation and measurement of contact pressure, enabling consistent welding quality even with curved or inhomogeneous surfaces, and allowing for simultaneous welding at multiple points.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If electrodes are positioned from both sides of the weld using welding tongs, then consistent electrode pressure force is ensured, but the mobility of the welding gun or workpieces is limited when repositioning between subsequent welding operations
Solution Approach 1:
The welding system is segmented into a stationary counterhold structure that provides stable positioning and a movable electrode assembly that can be independently positioned. This allows the counterhold to remain fixed while the electrode can move to different welding locations, resolving the contradiction between stability for pressure consistency and mobility for repositioning.
Solution Approach 2:
Instead of having both electrodes move (as in traditional welding tongs), the invention inverts the approach by making one electrode stationary (counterhold) and only the other electrode movable. This inversion maintains pressure consistency through the stationary structure while enabling mobility through the single movable electrode.
2Productivity
If multiple welding tongs are used for simultaneous welding at multiple points, then productivity is improved, but the freedom of movement of the welding device is further restricted
Solution Approach 1:
The system segments the welding function into multiple independent electrode assemblies that can operate simultaneously, while only requiring movement of individual electrodes rather than entire multi-tong assemblies. This enables parallel welding operations without the coordinated movement constraints of traditional multi-tong systems.
Solution Approach 2:
The invention introduces dynamic positioning capability where electrode positions can be independently adjusted and optimized for each welding operation. This dynamic adaptability allows the system to maintain freedom of movement while achieving simultaneous welding at multiple points through coordinated control of individual electrodes.
3Reliability
If spring preload is used to compensate for positional changes and material unevenness, then contact pressure is maintained, but electrode wear falsifies the intended contact pressure after longer periods
Solution Approach 1:
The invention incorporates feedback mechanisms including force sensors that continuously monitor actual contact pressure and control units that adjust electrode positioning in real-time. This closed-loop feedback system compensates for electrode wear and material variations, maintaining both reliability of pressure maintenance and precision of contact pressure accuracy over extended operation periods.
Solution Approach 2:
The invention replaces the purely mechanical spring preload system with an electromechanical control system that uses motors, force sensors, and control units. This substitution eliminates the cumulative error problem of mechanical spring systems while maintaining contact pressure, achieving both reliability and precision over time.
4Ease of operation
If robotic arms with spring preload are used for electrode positioning, then mobility is improved, but contact pressure is only imprecisely regulated
Solution Approach 1:
The invention adds feedback control through force sensors and control units that precisely regulate contact pressure despite electrode mobility. The system continuously measures actual pressure and adjusts positioning to achieve target pressure values, resolving the contradiction between mobility and precision in contact pressure regulation.
Solution Approach 2:
The invention replaces the simple mechanical spring preload system with an advanced electromechanical control system featuring motors, force sensors, and intelligent control units. This substitution enables both high mobility through robotic positioning and precise contact pressure regulation through active feedback control.
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
Ensures consistent high-quality welds by maintaining precise contact pressure control, enhancing production efficiency and reducing errors, even with complex or hard-to-access components, and allowing for repositioning and independent electrode positioning for improved welding efficiency.
Implementation Method 1
at least two electrodes which are arranged in pairs next to one another along the same surface side of the workpiece and are subjected to a force against the surface of the workpiece
Implementation Method 2
A welding current is conducted through the electrodes into the workpieces and at the transition between the workpieces, more precisely at the point at which they are pressed together, the base material is melted due to the high electrical resistance
Implementation Method 3
the base material is melted due to the high electrical resistance
Data Source
Figure 1
Figure 2
AI summary
Spot-welding method for workpieces (3a) using a robot with at least two electrodes (2a, 2b) comprises supporting the workpiece from below by a support block (9). The force with which at least one of the electrodes presses o the workpiece before and/or during welding is controlled to a desired value. Independent claims are included for: (A) apparatus for carrying out the method in which the force with which the electrodes press down is controlled by motors (8a, 8b); and (B) robots incorporating the apparatus.