Skin Material with Die-Molded Stepped Guide for Stitch Line Formation
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Solution Overview
Problem
The existing methods for molding skin materials for conveyance seats face challenges in forming high-quality stitch patterns, leading to discomfort due to stitch line strain, increased workability, and water ingress through sewing holes, which affects the seating experience and manufacturing efficiency.
Innovation Solution
A skin material with a linearly-extending transferred extension in a stepped shape from a die, where a stitch line is sewn along the transferred extension, serving as a guide, and a seal material covers the sewing holes to prevent water entry, enhancing texture, workability, and reducing the number of steps and material waste.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a stitch line is formed by sewing along a stitch formation target portion transferred from a die, then the texture quality of the skin material is improved, but strain is caused in the thickness direction of the skin material at the stitch line due to mismatch between the recessed-raised interval of the transferred portion and the sewing interval
Solution Approach 1:
The patent applies preliminary action by pre-forming a stepped shape on the die before the skin material is molded. The die includes a recessed portion and a raised portion arranged in the thickness direction, creating a predetermined stitch formation target portion with a stepped shape. This preliminary structuring of the die ensures that when the skin material is molded, the stitch formation target portion already has the correct geometry to guide the sewing thread along the recessed-raised boundary, preventing strain in the thickness direction during subsequent sewing operations.
2Manufacturing precision
If the delivering speed of the sewing machine is adjusted to match the recessed-raised interval of the stitch formation target portion, then the texture quality is improved, but workability decreases and the number of steps increases
Solution Approach 1:
The patent applies self-service by designing the die and skin material structure to automatically guide the sewing process. The stepped shape on the die creates a physical guide structure on the skin material that directs the sewing thread along the recessed-raised boundary. This self-guiding structure eliminates the need for complex sewing machine speed adjustments or additional positioning steps, as the stepped shape itself serves as the guide for forming the stitch line, thereby maintaining high texture quality while improving workability.
3Ease of manufacture
If a stepped shape is formed only by sewing, then the stitch line can be created, but manufacturing efficiency decreases and material waste increases due to seam allowance requirements
Solution Approach 1:
The patent applies merging by combining the stepped shape formation and stitch line formation into a single integrated process. The die simultaneously creates both the stepped shape (for guiding the stitch) and the final contour of the skin material. The raised portion of the die corresponds to the stitch formation target portion, while the recessed portion defines the outer contour. This merging of functions eliminates the need for separate stepped shape creation and stitching operations, improving manufacturing efficiency and reducing material waste by eliminating seam allowance requirements.
Data Source
AI summary
It is intended to improve texture of a decoration using a stitch line while improving workability in sewing for forming the stitch line at a skin material, to promote manufacturing efficiency as compared to formation of a stepped shape only by sewing, and to reduce the number of steps. A skin material is used for a conveyance seat, and is molded using a die. The skin material includes a linearly-extending stepped portion having a stepped shape transferred from the die, and a stitch line sewn along the stepped portion. The stepped portion serves as a guide upon formation of the stitch line.