Sewing Machine Thread Cutter with Dual Seizing Assemblies
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Solution Overview
Problem
Conventional thread cutters for sewing machines leave excessive needle and bobbin threads, leading to thread entanglement and increased manual cutting requirements, which can cause failures during initial stitches.
Innovation Solution
A thread cutter design with a first thread seizing assembly that seizes threads and a second thread seizing assembly that cuts them closer to the needle hole, using a cutting blade located near the needle hole, reducing thread remnants and preventing entanglement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the fixed blade is mounted on the proximal end side of the thread seizing assembly, then the construction is simplified, but the remaining amount of threads at the workpiece cloth side increases
Solution Approach 1:
The thread cutting function is segmented into two parts: a moving blade mounted on the thread seizing assembly and a fixed blade mounted separately. The moving blade is reciprocally moved to push threads against the fixed blade for cutting. This segmentation allows the fixed blade to be positioned optimally near the needle hole while maintaining construction simplicity.
Solution Approach 2:
The moving blade acts as an intermediary that transfers the cutting action from the fixed blade to the threads. By reciprocally moving the moving blade, threads are pushed against the fixed blade positioned near the needle hole, achieving effective cutting with minimal thread remnants without complicating the overall construction.
2Ease of manufacture
If the fixed blade is mounted farther from the needle hole, then the construction is simpler, but thread entanglement occurs during initial stitches
Solution Approach 1:
The moving blade is designed to be reciprocally movable, dynamically adjusting its position to push threads against the fixed blade. This dynamic mechanism enables the fixed blade to be positioned near the needle hole for reliable thread cutting, preventing thread entanglement during initial stitches while maintaining ease of assembly through the simple reciprocating motion mechanism.
3Ease of operation
If extra amount of threads remains, then the cutting location is easier to reach, but manual cutting is required and productivity decreases
Solution Approach 1:
The thread cutting action is performed preliminarily by the moving blade pushing threads against the fixed blade near the needle hole before the sewing operation begins. This preliminary cutting action minimizes thread remnants, eliminating the need for subsequent manual cutting and improving sewing operation efficiency while maintaining ease of operation through the automated reciprocating mechanism.
Data Source
AI summary
A thread cutter for a sewing machine includes a first thread seizing assembly reciprocally movable and including two unit thread seizing members having distal ends formed with first thread seizing portions respectively, a cutting blade located nearer to the needle hole side than a movement locus of the first assembly, and a second thread seizing assembly seizing the needle and bobbin threads both seized by the first assembly during backward movement of the first assembly, cutting the threads in cooperation with the cutting blade. When the threads seized by the first assembly are further seized by the second assembly, the first assembly is moved so that the distal ends of the unit thread seizing members are spaced from each other by a predetermined distance in a direction intersecting a movement direction of the first assembly.