Metal-Polymer Sandwich Panel Tack Welding for Resistance Weldability
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Solution Overview
Problem
Existing sandwich structures with non-metallic layers prevent the formation of a continuous electric circuit during resistance welding, making them non-weldable with other components or sheets, which hinders their use in subsequent processing industries that rely on cost-efficient resistance welding processes.
Innovation Solution
A method involving a non-cured and non-hardened non-metallic layer positioned between metal layers, allowing for tack welding to achieve a continuous metallic material closure, enabling subsequent resistance welding processes without damaging the non-metallic material and allowing for further forming operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a non-metallic layer is positioned between metal layers in sandwich structures, then the structural integrity and insulation properties are improved, but the weldability through resistance welding is lost due to prevention of continuous electric circuit formation
Solution Approach 1:
The non-metallic layer is applied in a non-cured and non-hardened state before welding, allowing the metallic layers to be tack welded together first. This preliminary positioning enables subsequent resistance welding operations to proceed on the metallic surfaces without the obstruction of a hardened non-metallic barrier, while still providing structural support during the welding process.
Solution Approach 2:
The key parameter change is the state of the non-metallic layer - transitioning from a non-cured/non-hardened state during welding to a cured/hardened state for final structural integrity. By controlling the curing state, the material properties are optimized for different process stages: weldability during manufacturing, and strength in the final product.
2Ease of manufacture
If resistance welding is performed on sandwich structures with non-metallic layers, then welding current transmission is improved, but the non-metallic material may be damaged due to high thermal energy
Solution Approach 1:
Tack welding is performed first to establish metallic contact and ensure proper positioning of layers before applying full welding current. This preliminary action allows the welding current to be transmitted through continuous metallic paths while minimizing direct thermal exposure to the non-metallic material, preventing damage.
Solution Approach 2:
The welding process is divided into two stages: partial welding (tack welding) to establish contact, and then complete welding to achieve full strength. This partial action approach allows current transmission optimization without excessive thermal damage to the non-metallic layer, as the tack welds create sufficient metallic continuity for current flow.
3Ease of manufacture
If metal layers are tack welded to achieve continuous metallic contact, then subsequent resistance welding becomes possible, but the handling and positioning precision during assembly becomes more critical
Solution Approach 1:
The non-metallic layer is positioned and held in place in its non-cured state before tack welding, allowing for adjustment and precise positioning. The tack welding then secures this positioning while maintaining the ability to achieve continuous metallic contact. This preliminary positioning action reduces the need for high precision during subsequent operations.
Solution Approach 2:
The non-metallic layer acts as an intermediary that facilitates proper positioning and spacing of metal layers during assembly. Its soft, non-cured state allows it to accommodate minor positioning variations while still enabling tack welding to establish continuous metallic contact, thereby reducing the stringency of positioning precision requirements.
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
This method ensures weldability in the initial state, allowing for high form stability and efficient manufacturing with resistance roller seam welding, enabling the use of sandwich structures in car body engineering and other applications with improved handling and reduced production costs.
Implementation Method 1
the physical law of Joule for resistance heating is used. That means the transformation of electrical energy into ohmic resistance and then further into thermal energy
Implementation Method 2
At the transition points from the copper to the metallic sheets, between the sheets and from the second sheet to the copper, the current energy is changed to ohmic resistances. These resistances are called transition resistances or contact resistances
Implementation Method 3
the thermal energy at this point reaches the melting temperature of the sheets and a weld point or called weld nugget results
Data Source
AI summary
A method for manufacturing a sandwich panel as a semi-finished product where at least one layer of a non-metallic material is positioned between at least two metallic layers. At least one of the metal layers is shaped into a three dimensional layer and the metal layers are material closured to each other by a tack weld on the metallic contacts between the metallic layers to enable resistance weldability of the semi-finished product in order to connect the semi-finished product to a desired combination of solutions.