Resistance Welding Tool with Movable Earth Electrode
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Solution Overview
Problem
Existing resistance welding devices for motor vehicle bodies are complex, heavy, and leave visible marks, making them unsuitable for aesthetic surfaces, and are costly for small series production.
Innovation Solution
A lightweight, simplified resistance welding device using a robotized moving apparatus with a C-shaped welding unit and movable earth electrodes for indirect projection weldings, allowing 'invisible' welds and eliminating the need for additional clamping devices by using a resting structure with support members and reference means for precise positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional resistance welding tool is used for spot weldings, then welding function is achieved, but the tool becomes complex and heavy requiring cooling systems
Solution Approach 1:
The patent extracts the cooling system from the welding tool by using a stationary welding electrode that conducts heat to a heat sink mounted on the robot arm, rather than cooling the entire tool. This eliminates complex cooling requirements while maintaining welding reliability.
Solution Approach 2:
Instead of cooling the welding electrode actively, the patent inverts the approach by using the workpiece itself as a heat sink and conducting heat away through the robot arm structure, reversing the traditional cooling direction and methodology.
2Productivity
If spot weldings are performed on visible surfaces, then welding is completed, but visible marks are left on the welded sheet
Solution Approach 1:
The patent introduces a stationary welding electrode as an intermediary element that allows the welding process to occur without the robot-mounted tool directly contacting the visible surface, enabling welds on aesthetic surfaces without visible marks.
3Reliability
If a complex welding device is used for motor vehicle body production, then welding quality is maintained, but production costs increase for small series
Solution Approach 1:
The workpiece serves as its own heat sink and the robot arm structure is utilized for heat conduction, eliminating the need for expensive dedicated cooling systems and complex welding equipment, thereby reducing production costs while maintaining quality.
Solution Approach 2:
The robot arm structure serves multiple functions: positioning the welding tool and simultaneously acting as a heat conduction path to the heat sink, eliminating the need for separate cooling components and reducing overall system cost.
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
Enables aesthetically intact welds on visible surfaces and reduces production costs, particularly suitable for small series production by simplifying the device structure and eliminating the need for complex cooling systems and additional clamping devices.
Implementation Method 1
resistance welding device... for welding portions of a motor vehicle body... resistance welding tool which is able to carry out one or more spot weldings... projection weldings
Implementation Method 2
at least one movable earth electrode, separated from said support members, for allowing to close, through the composite panel, the circuit for feeding current to the welding electrodes
Data Source
Figure 1~2
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AI summary
A resistance welding device, particularly for welding portions of a motor vehicle body, comprises a robotized moving apparatus (12) provided with a movable arm (14) which supports a welding tool (18) intended to carry out projection weldings at a plurality of zones of a piece (20; 30). The welding tool (18) includes a body from which a welding C-shaped unit (24) extends, provided with a pair of opposite and aligned welding electrodes (26, 27), which body contains a transformer for feeding current to said welding electrodes (26, 27). The device (11) comprises a resting structure (32) provided with support members (40) for supporting a composite panel (30), reference means (42, 46) for correctly positioning the elements (30a, 30b) of the panel (30) during the welding, and at least a earth electrode (48) which is movable for closing, through the panel (30), the circuit for feeding current to the welding electrodes (26, 27).