Thermally Expandable Joint Filling for Gap-Free Workpiece Joining
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for joining hollow profiles and node elements in motor vehicle body construction, such as metal inert gas welding, face challenges with distortion, inconsistent weld quality, and gaps leading to reduced mechanical force transfer and corrosion resistance, while alternative methods like adhesives and injection bonding are cumbersome and lack consistency.
Innovation Solution
A method using a thermally expandable material arranged between workpieces, which melts and expands to fill the overlapping area, forming a strong, gap-free connection through thermal energy introduction, allowing for improved mechanical force transfer and corrosion resistance, and can be automated for reproducibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If metal inert gas welding is used to join hollow profiles and node elements, then a strong connection is achieved, but distortion of the component occurs due to high heat input
Solution Approach 1:
The invention changes the thermal parameters of the joining process by using a thermally expandable material that melts at a lower temperature than the workpieces. This allows the joining process to proceed at lower temperatures, reducing heat-affected zone and minimizing distortion while maintaining connection strength through the phase change and expansion of the joining material.
Solution Approach 2:
The invention utilizes phase transitions of the thermally expandable material (solid to liquid to expanded solid) as the core mechanism for joining. The material melts and then expands to fill the gap and create a strong mechanical interlock, achieving strong connections with controlled thermal input that minimizes distortion.
2Strength
If metal inert gas welding is used for joining, then connection strength is improved, but the process becomes very time-consuming and consistent weld quality is difficult to ensure
Solution Approach 1:
The thermally expandable material performs multiple functions automatically: it fills the gap, creates mechanical interlock, and forms a protective seal against corrosion. This self-service capability eliminates the need for separate operations and ensures consistent quality through the material's inherent properties rather than operator skill.
Solution Approach 2:
The controlled phase transition of the thermally expandable material provides a reproducible joining mechanism that is less sensitive to process variations. The material automatically expands to fill gaps and create consistent mechanical interlocks, ensuring uniform weld quality across different joints and operators.
3Adaptability or versatility
If a gap is present in the overlapping area between hollow profile and spigot, then tolerance compensation is achieved, but mechanical force transfer and corrosion resistance are reduced
Solution Approach 1:
The invention uses thermal expansion of the joining material to fill the gap created by tolerance compensation requirements. The thermally expandable material expands during the joining process to completely fill the overlapping area, creating both tolerance compensation and continuous mechanical force transfer paths while preventing corrosion ingress.
Solution Approach 2:
The invention creates a composite structure where the thermally expandable material bonds the hollow profile and spigot together. This composite approach allows the gap-filling material to provide both tolerance accommodation and continuous load transfer, combining the benefits of gap presence and gap-free connection.
4Ease of manufacture
If adhesive is applied to the locating spigot before pushing the hollow profile onto it, then connection is achieved, but the adhesive can be displaced during assembly so continuous closed connection cannot be guaranteed
Solution Approach 1:
The thermally expandable material undergoes phase transition during the assembly process, melting and then expanding to fill the gap and create a continuous closed connection. This phase change ensures the material remains in place and guarantees continuous connection, eliminating the displacement problem associated with pre-applied adhesives.
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 enhances mechanical force transfer and corrosion resistance by eliminating gaps and ensuring a consistent connection, reducing distortion and operational complexity, and is suitable for metallic materials like steel in motor vehicle body construction.
Implementation Method 1
a thermally expandable material being arranged in a space between a first workpiece and a second workpiece, thermal energy being used in a joining process
Implementation Method 2
The thermally expandable material and/or the material that is thermally expanded after the method has been carried out can completely or partially fill the overlapping area
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).