Sewing Machine Hook Release Phase Control for Thread Tension
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Solution Overview
Problem
Conventional sewing machines face difficulties in maintaining a sufficiently loosened upper thread when the needle bar swings widely, leading to potential thread breakage and abnormal noise due to increased tension.
Innovation Solution
A sewing machine with a control unit that adjusts the hook release phase to ensure the hook/upper-thread necessary amount is smaller than the thread-take-up-lever/upper-thread supply amount, using a belt adjusting mechanism to change the belt length at the tensioned side, allowing for advanced or retarded hook release phases to maintain optimal thread tension.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the needle bar swings widely to enable complex sewing patterns, then the adaptability of the sewing machine is improved, but the upper thread tension increases leading to thread breakage and abnormal noise
Solution Approach 1:
The patent applies dynamics by making the belt length adjustable during operation. The belt adjusting mechanism changes the belt length at the tensioned side based on the needle bar swing amplitude, dynamically adapting the timing between needle and hook operations. This dynamic adjustment ensures that even during wide swings for complex sewing patterns, the upper thread remains sufficiently loosened to prevent breakage while maintaining reliable stitch formation.
2Adaptability or versatility
If the swing level of the needle bar is increased to form wider zig-zag stitches, then the versatility of the sewing machine is improved, but the timing at which the needle and hook intersect changes beyond the allowable range making stitch formation difficult
Solution Approach 1:
The patent applies parameter changes by adjusting the belt length parameter in response to needle bar swing amplitude. The control unit detects the swing amplitude and相应地 changes the belt length parameter through the belt adjusting mechanism. This parameter adjustment compensates for the timing shift caused by wide needle bar swings, maintaining the intersecting phase between needle and hook within the allowable range for accurate stitch formation while enabling wide zig-zag patterns.
3Manufacturing precision
If the belt length at the tensioned side is adjusted to control the needle/hook intersecting phase, then the timing precision between needle and hook is improved, but the device complexity increases due to the belt adjusting mechanism
Solution Approach 1:
The patent uses the belt as an intermediary element between the upper shaft and lower shaft. The belt adjusting mechanism modifies the belt length to indirectly control the timing relationship between needle and hook operations. This intermediary approach allows for precise control of the intersecting phase without requiring direct mechanical coupling adjustments, achieving accurate timing control while keeping the overall device structure relatively simple.
Data Source
AI summary
A sewing machine includes a thread take-up lever that supplies an upper thread to a needle from a thread supply source, a hook which catches the upper thread inserted in the needle, and which intertwine the upper thread with a lower thread, and a control unit that controlling a hook release phase at which the hook releases the upper thread in such a way that a hook/upper-thread necessary amount that is necessary when the upper thread is intertwined with the lower thread becomes smaller than a thread-take-up-lever/upper-thread supply amount that is supplied by an operation of the thread take-up lever. The control unit controls the hook release phase at a plurality of timings.