Sewing Machine Thread Cutting Device with Selective Upper and Lower Thread Control
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Solution Overview
Problem
Existing automatic thread cutting devices for sewing machines with horizontal loop takers face difficulties in efficiently cutting upper and lower threads separately, especially during embroidery stitching where only the upper thread needs to be exchanged while the lower thread remains unchanged.
Innovation Solution
An automatic thread cutting device with a first instruction means for cutting both upper and lower threads, and a second instruction means for cutting only the upper thread, utilizing a thread catching means and a thread regulating means to selectively catch and cut the threads, allowing for simultaneous or sequential cutting based on operator input.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a movable blade is operated to cut both upper and lower threads simultaneously, then thread cutting operation is simplified, but operational efficiency decreases when only upper thread needs to be exchanged
Solution Approach 1:
The thread cutting function is segmented into two independent modes: cutting both upper and lower threads simultaneously, and cutting only the upper thread. This is achieved through separate instruction means (first instruction means for cutting both threads, second instruction means for cutting only upper thread) that control the thread catching means to selectively catch and cut the required threads, allowing operational efficiency to be maintained when only upper thread exchange is needed.
2Extent of automation
If thread catching means is designed to catch both upper and lower threads, then simultaneous cutting is achieved, but flexibility to cut only upper thread is lost
Solution Approach 1:
The thread catching means is designed with dynamic adaptability to change its catching behavior based on operational requirements. Through the control system receiving instructions from the first or second instruction means, the thread catching means can dynamically adjust to catch either both upper and lower threads or only the upper thread, providing versatility while maintaining automatic operation.
3Device complexity
If a single thread cutting mechanism is used, then device complexity is reduced, but ability to selectively cut only upper thread is limited
Solution Approach 1:
The single thread catching means and thread cutting means are designed with multi-functionality to perform different cutting tasks. By incorporating first and second instruction means that control the same thread catching means to selectively catch and guide threads to the cutting means, the system achieves versatile cutting capabilities (both threads or upper thread only) without increasing the complexity of the core cutting mechanism.
Data Source
AI summary
Disclosed is an automatic thread cutting device for a sewing machine which is provided with a horizontal loop taker, wherein a thread catching member (4) is operated in response to a thread cutting instruction to reciprocatingly move with a movable blade (5) along a predetermined course, the thread catching member (4) normally catching the upper thread when moving in the return-way of reciprocation to guide the upper thread to a fixed blade (14) which is provided to cut the upper thread in cooperation with the movable blade (5), and wherein a thread regulating means is provided to cut the lower thread (29d) together with the upper thread, the thread regulating means being operated to press down the lower thread (29d) to a position where the lower thread (29d) is caught by the thread catching member (4) in addition to the upper thread when the thread catching member (4) is moving in the return-way of reciprocation.