Joining Sheet Metal With Thermoplastic Interlayer
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Solution Overview
Problem
The challenge lies in joining sheet metal components with a thermoplastic intermediate layer, as existing methods face difficulties in welding due to the thin outer steel cover sheets, leading to complex manufacturing processes and increased costs, especially when trying to connect high-strength steel components.
Innovation Solution
A method involving temperature-controlled electrodes to melt and displace the thermoplastic intermediate layer, allowing for a materially bonded connection between sheet-like components, which can also include electrical contact and mechanical prestressing for enhanced reliability and strength, potentially eliminating the need for adhesives and reducing corrosion susceptibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If resistance welding is attempted on composite sheets with thermoplastic intermediate layer, then welding speed and productivity improve, but the thin outer steel cover sheets cause the composite sheet to burn through around the welding electrode
Solution Approach 1:
The patent applies preliminary action by heating the thermoplastic intermediate layer to its melting point before applying the welding current. This pre-heating step (claim 1, step a) ensures the intermediate layer is already in molten state, allowing the subsequent welding current to pass through without causing burn-through of the thin cover sheets. The burning through prevention is achieved by having the intermediate layer ready to conduct current before the high-current welding phase.
Solution Approach 2:
The patent changes the thermal parameter of the intermediate layer by heating it to melting temperature before welding. This parameter change (from solid to molten state) fundamentally alters the electrical conductivity and thermal properties, enabling the welding current to pass through the intermediate layer without causing burn-through, thus resolving the contradiction between welding speed and welding quality.
2Ease of manufacture
If mechanical joining methods are used to connect composite sheets with high-strength steel, then welding is avoided, but pre-punching for blind rivets or clinching is not possible due to the high strength of form-hardened components
Solution Approach 1:
The patent replaces the mechanical joining system (blind rivets, clinching) with a thermal-electrical joining system (resistance welding). By substituting the mechanical pre-punching requirement with thermal pre-heating of the intermediate layer, the method enables joining of high-strength steel components without requiring mechanical weakening or complex pre-processing steps.
Solution Approach 2:
The thermoplastic intermediate layer serves as an intermediary that facilitates the joining process. By heating this intermediate layer to molten state, it becomes an electrically conductive medium that allows current passage for resistance welding, thereby enabling the use of simple welding equipment instead of complex mechanical joining systems.
3Reliability
If the intermediate layer is heated to melting point before welding, then electrical contact and materially bonded connection are achieved, but additional process steps and energy consumption increase
Solution Approach 1:
The patent merges two separate process steps (heating to melting point and resistance welding) into a sequential process where the heating phase is immediately followed by the welding phase using the same equipment setup. The electrodes used for heating are the same electrodes used for welding, eliminating the need for separate heating equipment and reducing overall process complexity and energy overhead.
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 enables efficient and strong connections between sheet metal components, optimizing the manufacturing process, reducing costs, and improving handling strength, while allowing for electrical contact and increased process reliability.
Implementation Method 1
At a joint 2 of the components 3a, 3b, the intermediate layer 4 is melted by means of heat input into the first and/or second component 3a, 3b
Implementation Method 2
Simultaneously or subsequently, a pressing force FE is applied to the components 3a, 3b in the area of the joint 2, so that the intermediate layer in the area of the joint 2 between the components 3a, 3b is displaced
Implementation Method 3
Alternatively or additionally, after the displacement of the intermediate layer, the production of an electrical contact between the first and second component in the region of the joint can also be provided according to the invention
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
The invention relates to a method for joining a first sheet metal-type component (3a) to a second sheet metal-type component (3b), wherein the components (3a, 3b) are connected via at least one intermediate layer (4) made of thermoplastic synthetic material, comprising the following steps: melting the intermediate layer (4) by introducing heat into the first and/or second component at a joint (2); displacing the intermediate layer (4) in the area of the joint (2) by applying pressing force to the components (3a, 3b) in the area of the joint (2); adhesively bonding the first and second component (3a, 3b) by means of melting the first and/or second component (3a, 3b), or by tack-welding the first and second component (3a, 3b) in order to produce a handling connection in the area of the joint (2); and/or producing electrical contact between the first and second component (3a, 3b) in the area of the joint (2). The invention further relates to a device for carrying out the method, and to a component assembly according to the method.