Resin Vehicle Back Door Adhesive Joint Strength
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Solution Overview
Problem
The existing vehicle resin back door structure has a joint section that divides the inside and outside of the closed cross section, making it difficult to sandwich and hold the joint portion between the inner and outer panels, thereby limiting the joint strength.
Innovation Solution
A vehicle back door joining method that involves forming a closed cross section by joining resin inner and outer panels with an adhesive, then inserting a cylindrical holding jig through a hole in the outer panel to sandwich and hold the joint portion between the panels, allowing the adhesive to harden under pressure from both sides.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the joint section is configured as a wall portion that divides the inside and outside of the closed cross section, then the structural integrity is maintained, but the joint strength cannot be improved because the joint portion cannot be sandwiched between holding jigs
Solution Approach 1:
The patent divides the joining process into two distinct stages: first forming the closed cross-section structure, then inserting holding jigs through separately formed hole portions to apply pressure during adhesive hardening. This segmentation allows the joint portion to be sandwiched between jigs without compromising the structural integrity of the closed cross-section.
Solution Approach 2:
The patent introduces holding jigs as intermediary tools that temporarily penetrate the outer panel through hole portions to apply pressure to the joint portion during adhesive hardening. These jigs act as mediators that enable strong joint formation without requiring modification to the closed cross-section's wall structure.
2Strength
If holding jigs are inserted through the outer panel to sandwich the joint portion, then the joint strength is enhanced, but the outer panel structure becomes more complex requiring additional hole portions
Solution Approach 1:
The patent performs preliminary actions by forming hole portions in the outer panel during the panel fabrication process, before the actual joining operation. This allows the holding jigs to be easily inserted later without requiring complex modifications to the outer panel structure during assembly.
Solution Approach 2:
The patent applies local quality by creating specific hole portions only in the outer panel at locations that do not compromise the overall structural integrity or aesthetic appearance. These localized openings enable jig insertion while maintaining the closed cross-section's strength in all other areas.
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 enhances the joint strength between the inner and outer panels by applying pressure during the adhesive hardening process, improving the structural integrity of the vehicle back door without compromising its design.
Implementation Method 1
joining, with an adhesive, an inner panel, preferably made of resin, and an outer panel, preferably made of resin, to each other
Implementation Method 2
the joint portion between the inner panel and the outer panel is sandwiched between and held by the first holding jig and a second holding jig placed outside the closed cross section
Data Source
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AI summary
A method of joining a vehicle back door (10), the method including forming a closed cross section (50) by joining, with an adhesive (42), an inner panel (12) made of resin and an outer panel (30) made of resin to each other; and inserting a first holding jig (60) inside the closed cross section (50) from a hole portion (40B) formed in the outer panel and allowing the adhesive (42) to harden in a state in which a joint portion between the inner panel (12) and the outer panel (30) is sandwiched between and held by the first holding jig (60) and a second holding jig (62) placed outside the closed cross section (50).