Multi-Needle Chain-Stitch Sewing Machine Thread Tension Control
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Solution Overview
Problem
Multi-needle inline chain stitch sewing machines face challenges in producing closely spaced parallel seams without seam malformations, as the lack of thread tension control leads to errors due to adjacent needles and grippers catching threads.
Innovation Solution
A multi-needle chain stitch sewing machine with a thread tightening mechanism that applies additional tension to upper threads between the thread guide and needle, allowing for closer needle spacing and secure seam formation by controlling thread tension dynamically.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the distance between adjacent needles is reduced to produce closely spaced parallel seams, then productivity and seam density are improved, but thread entanglement and seam defects increase due to adjacent needles catching threads from neighboring seams
Solution Approach 1:
The patent applies dynamic tension control to the upper threads by introducing a thread tensioning device that actively adjusts thread tension during the stitching process. This dynamic adjustment prevents thread entanglement between adjacent needles while maintaining close needle spacing, thereby resolving the contradiction between productivity (closely spaced seams) and reliability (seam quality without defects).
Solution Approach 2:
The patent changes the parameter of thread tension from static to variable/dynamic. By implementing a thread tensioning device that can adjust tension levels, the system maintains optimal thread control throughout the stitching cycle, preventing the thread entanglement that would normally occur with closely spaced needles, thus enabling both high productivity and high seam quality.
2Device complexity
If thread tension is not controlled in multi-needle inline chain stitch sewing machines, then device complexity is reduced, but seam malformations occur due to large thread loops and entanglements
Solution Approach 1:
The thread tensioning device performs preliminary action by pre-tensioning the upper threads before they reach the needles. This preliminary tension control prevents the formation of large thread loops and entanglements during stitching, ensuring precise seam formation without requiring complex post-processing or additional mechanical complexity in the basic machine structure.
3Reliability
If crossline machine configuration is used to avoid thread entanglement, then seam quality is improved, but seams become offset in longitudinal direction reducing manufacturing precision
Solution Approach 1:
Instead of using the crossline machine configuration (which offsets needles to prevent entanglement but creates longitudinal seam offset), the patent inverts the approach by using an inline configuration (needles perpendicular to feed direction) and solving the entanglement problem through dynamic thread tension control. This inversion maintains both high seam formation reliability and precise longitudinal seam alignment.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables reliable formation of closely spaced chain stitch seams without thread entanglements, maintaining seam integrity and preventing malformations, with adjustable thread tension ensuring optimal loop formation and reduced risk of large thread loops.
Implementation Method 1
thread tightening mechanism that applies additional tension to upper threads between the thread guide and needle
Data Source
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AI summary
The invention is intended to enable a multi-needle chain-stitch sewing machine to produce in a single operation chain-stitch seams which run parallel to one another and are at a small distance from one another and in which the points of insertion of the needles in the seams are not offset from one another in relation to the longitudinal direction thereof. For this purpose, a multi-needle chain-stitch sewing machine is provided, comprising multiple needles (2) each guiding an upper thread (5), wherein the multiple needles are arranged respectively at a distance from one another along a straight-running line and can be moved synchronously in relation to one another, and the line is aligned at least substantially orthogonally in relation to the intended direction of advancement of a transporting mechanism for the material to be sewn, also comprising a thread guide (4) for the multiple upper threads, in order to guide each upper thread (5) from its thread supply (6) to the needle assigned to it, comprising multiple driven loopers (3), each guiding an underthread (25), wherein the loopers (3) are arranged at a distance from one another and can be moved synchronously in relation to one another, the movements of the loopers (3) and the needles (2) having the effect in each case that an upper thread (5) and an underthread (25) can be interwoven, in order in this way to produce simultaneously in the material to be sewn multiple seams running parallel to one another, with points of insertion of the needles arranged in the material to be sewn without being offset from one another in the direction of advancement, and a drive device, which has at least one motor and by which the movements of the needles and the loopers can be produced in a predetermined and coordinated way. According to the invention, such a chain-stitch sewing machine is to be provided with a thread tensioning means (10), for at least one of the upper threads (5), arranged in the region of the thread guide and provided in addition to a thread take-up (11), with which at least one of the upper threads can be provided with an additional thread tension in the region between the thread tensioning means (10) and the needle (2) assigned to the at least one upper thread (5).