Method for controlling length stability of thread residue in sewing machine needle

Abstract

The invention provides a method for controlling the length stability of a thread residue in a sewing machine needle. The method includes the following steps that a thread pressing device, a driving source and a presser foot lifting mechanism connected between the driving source and a presser foot in a sewing machine are arranged in the sewing machine; in the process that a needle moves downwards when the sewing machine starts sewing, the thread pressing device acts on a section of sewing thread arranged between a take-up lever and the needle in the sewing machine in a penetrating mode, to increase the thread tension of the section of sewing thread; and meanwhile, the driving source acts, and the presser foot is lifted upwards by a preset height through the presser foot lifting mechanism. In the process that the needle moves downwards when sewing is started, the thread tension of the section of sewing thread between the take-up lever and the needle is increased through the thread pressing device, the length of the thread residue of the sewing thread left at the needle can be shortened, a bird nest phenomenon is avoided, and it is guaranteed that the stitch is attractive; meanwhile, in the process, the driving source enables the presser foot to be lifted up slightly through the presser foot lifting mechanism, the phenomenon that the sewing thread residue left at the needle is pressed by the presser foot is avoided, and therefore the phenomenon that the sewing thread is broken due to the combined action of the thread pressing device and the presser foot is avoided.

Description

technical field [0001] The invention relates to the field of sewing machines, in particular to a method for controlling the stability of the thread end length in a sewing machine needle. Background technique [0002] At present, all sewing machines are equipped with an automatic thread trimming mechanism, such as an automatic thread trimming mechanism for a sewing machine disclosed in a Chinese invention patent application with the application number 201710215982.X, which is used for automatic thread trimming at the end of sewing. A piece of thread remains on the sewing material and a piece of thread remains on one side of the needle. After the sewing machine is actually used, there are the following problems: the length of the remaining suture end on the needle side is very unstable, and it is very easy to have problems such as the end of the suture being pulled off, shortened in length, and completely protruded from the needle hole of the needle. , thus affecting the form...

AI Technical Summary

Problems solved by technology

After the sewing machine is actually used, there are the following problems: the length of the remaining suture end on the needle side is very unstable, and it is very easy to have problems such as the end of the suture being pulled off, shortened in length, and completely protruded from the needle hole of the needle. , thus affecting the formation of stitches at the beginning of sewing

Therefore, after the upper thread is cut off by the engagement of the movable knife and the fixed knife, and then the movable knife and the fixed knife are separated and reset, the thread take-up lever continues to move upwards to take up the thread. A section of upper thread passes through multiple thread passers and thread grippers, and is in a state of tension or low tension, but the section of upper thread between the thread take-up lever and the needle is in a state of no tension, and the thread take-up action is performed with the thread take-up lever , the part of the upper thread between the thread take-up lever and the needle will be taken away, which will cause the length of the thread remaining on the needle side after thread trimming to be unstable, and it is very easy to cause thread trimming flying thread and remaining thread on the needle The thread end in the middle becomes shorter, the thread end comes out completely from the needle hole of the machine needle, etc., which will affect the formation of stitches at the next sewing start

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