Thermally Expandable Joint Filling for Hollow Profile Welding
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Solution Overview
Problem
Existing methods for joining hollow profiles and node elements in vehicle construction, such as MIG welding, are time-consuming, difficult to automate, and result in inconsistent weld quality, gaps that compromise mechanical force transmission and corrosion resistance.
Innovation Solution
A method involving a thermally expandable material placed between workpieces, which expands and fills gaps upon thermal energy input, creating a material-bonded and form-fit connection, enhancing mechanical force transmission and corrosion resistance, and is automatable.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If MIG welding is used to join hollow profiles and node elements, then a connection is achieved, but the process is time-consuming and difficult to automate
Solution Approach 1:
The patent replaces the manual MIG welding process with a resistance spot welding process that uses electrical current to generate heat directly at the joint interface. This substitution enables automated joining through programmable electrode positioning and controlled current application, eliminating the need for manual operation while significantly increasing joining speed and consistency.
Solution Approach 2:
The patent introduces a thermally expandable material as an intermediate layer between the workpieces. By controlling the thermal parameters (heating to expansion temperature), the material expands to fill gaps and ensure consistent contact between surfaces. This parameter control enables reliable automated welding by standardizing the joint geometry before welding occurs.
2Strength
If MIG welding is used to join hollow profiles, then a connection is achieved, but distortion of the component occurs due to high heat input
Solution Approach 1:
The patent replaces conventional MIG welding with resistance spot welding, which concentrates heat generation at the precise joint location through electrical current flow. This localized heating method, combined with the use of a thermally expandable intermediate material, significantly reduces overall heat input to the component, thereby minimizing thermal distortion while maintaining joint strength.
Solution Approach 2:
The thermally expandable material serves as an intermediary layer between the hollow profile and node element. During the joining process, this material expands to fill gaps and distribute heat more evenly, preventing concentrated thermal zones that cause distortion. The intermediary material acts as a thermal buffer that protects the base components from excessive heat while still enabling strong joint formation.
3Reliability
If MIG welding is used to join hollow profiles and node elements, then a connection is achieved, but consistent weld quality is difficult to guarantee
Solution Approach 1:
The patent incorporates a thermally expandable material that is pre-positioned between the workpieces before joining. This preliminary action ensures that when heating occurs, the material expands to fill any gaps or irregularities in the joint interface, creating consistent contact conditions. This pre-preparation eliminates variability in weld quality by standardizing the joint geometry before the actual joining process begins.
Solution Approach 2:
The patent utilizes controlled thermal parameter changes to achieve consistent joining results. By heating the thermally expandable material to a specific temperature range, the material expands predictably to fill gaps and ensure uniform contact between surfaces. This controlled parameter change creates repeatable joining conditions that guarantee consistent weld quality across multiple joints, while the rapid heating and cooling cycle maintains high productivity.
4Ease of operation
If a gap forms in the overlap area between hollow profile and receiving pin, then assembly is easier, but mechanical force transmission and corrosion resistance are compromised
Solution Approach 1:
The thermally expandable material serves as an intermediary substance that is introduced into the gap between the hollow profile and receiving pin during assembly. When heated during the joining process, this material expands to completely fill the gap, creating a solid bridge that transmits mechanical forces effectively. The intermediary material thus eliminates the harmful effects of gaps while maintaining assembly ease, as the gap-filling action occurs automatically during the controlled heating phase.
Solution Approach 2:
The patent exploits the phase transition of the thermally expandable material from a compact state to an expanded state through controlled heating. In the initial assembly phase, the material remains in its compact form, allowing easy insertion and gap filling. During the joining phase, thermal energy triggers expansion, transforming the material into a dense, force-transmitting structure that eliminates the gap's negative effects on mechanical strength and corrosion resistance.
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 method provides a reproducible, automated process that eliminates gaps, improves mechanical force transmission, and enhances corrosion resistance by using thermally expandable materials in resistance spot welding, minimizing distortion and eliminating the need for additional sealing or curing steps.
Implementation Method 1
a thermally expandable material is arranged in an intermediate space between a first workpiece and a second workpiece, wherein thermal energy is introduced into the joining area in a joining process
Implementation Method 2
thermal energy is introduced into the joining area in a joining process in order to produce a connection between the first workpiece and the second workpiece
Data Source
Figure 1~2
Figure 3~4
AI summary
A method (200) for joining workpieces (10, 11) is provided, in which the transmissibility of mechanical forces and the corrosion resistance are improved and which is automatable, highly reproducible and easy to perform, wherein a thermally expandable material (17) is arranged in a space (16) between a first workpiece (10) and a second workpiece (11), wherein thermal energy is introduced into a joining area (24) in a joining process to create a connection between the first workpiece (10) and the second workpiece (11), wherein the thermally expandable material (17) melts in the joining area (24) so that a connection between the first workpiece (10) and the second workpiece (11) is created in the joining area (24).and wherein the thermally expandable material (17) expands in an expansion area (26) adjacent to the connection area (24), such that the thermally expanded material (17) substantially completely fills the space (16) between the first workpiece (10) and the second workpiece (11) in the expansion area (26).