Sewing Machine Darning Width Adjustment Mechanism
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Solution Overview
Problem
Conventional over-edge sewing machines face limitations in adjusting darning width due to interference between the thread-sliding piece and the upper looper, leading to insufficient cutting width and labor-intensive thread tension adjustments, especially when sewing elastic materials.
Innovation Solution
A darning width adjusting device that allows independent adjustment of the thread-sliding piece and lower knife holder in the orthogonal direction, enabling the lower knife to move further outward without interfering with the upper looper, and allowing for fine adjustments of the thread-sliding piece's position to match cloth expansion and contraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the lower knife holder is moved outward to assure a wide cloth cutting width, then the cutting width is improved, but the thread-sliding piece and upper looper interfere with each other
Solution Approach 1:
The patent divides the support system into two independent parts: the lower knife holder and the thread-sliding piece holder. This segmentation allows each component to be positioned and adjusted independently, enabling the lower knife holder to move outward for wider cutting while the thread-sliding piece remains positioned to avoid interference with the upper looper.
Solution Approach 2:
The patent introduces independent adjustment capability in the orthogonal direction (lateral movement) for both the lower knife holder and the thread-sliding piece holder. This dimensional independence allows the system to optimize both cutting width and looper clearance simultaneously by moving components along different paths in the same spatial plane.
2Device complexity
If the thread-sliding piece is supported on the lower knife holder, then the structure is simplified, but the outward moving amount of the lower knife is limited
Solution Approach 1:
The patent separates the support functions by providing an independent thread-sliding piece holder rather than mounting the thread-sliding piece on the lower knife holder. This segmentation enables the lower knife holder to achieve greater outward movement without being constrained by the thread-sliding piece's position, while maintaining structural simplicity through clear functional separation.
3Adaptability or versatility
If the darning width is adjusted by operating a thread tensioner, then the darning width can be changed, but the adjusting operation becomes troublesome and labor is required
Solution Approach 1:
The patent implements dynamic adjustability through independent movable holders that can be repositioned along adjustment shafts. The thread-sliding piece holder and lower knife holder can be moved to different positions to accommodate various darning widths, providing a more intuitive and easier adjustment mechanism compared to operating a thread tensioner.
Solution Approach 2:
The patent introduces adjustment shafts as intermediary components that facilitate the movement and positioning of both the thread-sliding piece holder and lower knife holder. These adjustment shafts provide a simple mechanical interface for achieving darning width adjustments without requiring complex thread tensioner operations.
Data Source
AI summary
A darning width adjusting device for a sewing machine includes a lower knife holder supported by a sewing machine frame such that a moving position of the lower knife holder is adjustable in a direction orthogonal to a cloth feeding direction, a thread-sliding piece which sets a darning width by picking up a thread at a tip thereof in the vicinity of a stitch point, a thread-sliding piece holder supported by the sewing machine frame such that a moving position of the thread-sliding piece is adjustable in the orthogonal direction to the cloth feeding direction, a thread-sliding piece adjusting means for adjusting the moving position of the thread-sliding piece, and a lower knife holder adjusting means for adjusting the moving position of the lower knife holder to a position exceeding a outside marginal position of the thread-sliding piece.