Vehicle Door Frame Partial Hemming Process
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Solution Overview
Problem
The conventional three-step process for forming a folded edge in vehicle door frames is complex and costly, requiring down-flanging, prehemming, and rope-hemming, with the need for the folded edge to contact the remaining metal sheet for effective rust prevention and appearance enhancement.
Innovation Solution
A two-step process involving down-flanging and partial hemming, where the folded edge is angled relative to the remaining part of the metal sheet, eliminating the need for rope-hemming and allowing the end of the folded edge to remain noncontact with the metal sheet, with an opening angle less than 25 degrees for improved workability and cost reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional three-step hemming process (down-flanging, prehemming, rope-hemming) is used, then the folded edge contacts the remaining metal sheet for effective rust prevention, but the manufacturing process becomes complex and costly
Solution Approach 1:
The patent extracts and eliminates the rope-hemming step from the conventional three-step hemming process. By using down-flanging followed by prehemming only, the folded edge is left in a non-contact state with the remaining metal sheet, removing the need for the third hemming operation while maintaining rust prevention through sealant application in the created space.
Solution Approach 2:
The patent applies partial hemming (prehemming) to achieve the necessary fold angle without completing the full rope-hemming process. The folded edge is bent to a specific angle (e.g., 45-135 degrees) but deliberately left in a non-contact state, using partial action to create the functional hemming structure without excessive processing.
2Reliability
If rope-hemming is performed to fold the edge back onto the metal sheet, then rust prevention is improved, but production time and cost increase
Solution Approach 1:
The patent removes the rope-hemming step from the manufacturing process, reducing the number of operations from three to two. This extraction of the unnecessary step directly improves productivity while maintaining edge protection through the combination of prehemming and sealant application.
Solution Approach 2:
The patent performs prehemming as a preliminary action that creates the folded edge structure and the space between the folded edge and remaining metal sheet. This preliminary folding action prepares the structure for subsequent sealant application, which provides the rust prevention function that would otherwise require the full rope-hemming process.
3Device complexity
If the folded edge is left in noncontact position with inclined shape, then the manufacturing process is simplified, but it must ensure effective application of waterproof agent
Solution Approach 1:
The patent introduces sealant (waterproof agent) as an intermediary substance that fills the space created between the folded edge and the remaining metal sheet. This sealant mediates the waterproofing function, allowing the folded edge to remain in a non-contact inclined position while still achieving effective rust prevention through the sealant barrier.
Data Source
AI summary
In a vehicle door frame structure including a sheet-metal member of a vehicle door frame, the sheet-metal member formed by a metal sheet includes a folded edge at an edge of the metal sheet, wherein an end of the folded edge is in noncontact with a remaining part of the metal sheet. The folded edge has an inclined shape which is inclined to increase a distance between the folded edge and the remaining part of the metal sheet in a direction from a bend of the folded edge to a free end of the folded edge.