Sewing quality control in sewing machine

Abstract

The present invention relates to a sewing machine which evaluates sewing quality using a thread tightening index. During a sewing operation, an upper thread used length (U) used for each stitch is detected, and a thread tightening index (Ks) for each sewn stitch is calculated on the basis of a stitch length (M) for each stitch, defined in accordance with sewing pattern data, a fabric thickness (t) of the object being sewn, and the detected upper thread used length (U) data. A report (for example a display of the thread tightening index Ks) corresponding to the thread tightening index (Ks) calculated for each sewn stitch is issued. By comparing the thread tightening index (Ks) calculated for each sewn stitch with a reference value (Kref), the acceptability of the thread tightness for each sewn stitch can be assessed, and the assessment results can be reported.

Description

technical field [0001] The present invention relates to a sewing machine for T-stitching and embroidering an object to be sewn by winding an upper thread and a lower thread, in particular to a sewing machine capable of evaluating the tightness of the thread after sewing so as to perform quality control of the finished product A sewing machine, and also relates to a method and a program for sewing quality management. Background technique [0002] During sewing, the sewing state changes according to how to adjust the tension of the upper and lower threads. In particular, if the tension of the upper thread is too high, the lower thread will be pulled out on the fabric, and if the tension of the upper thread is too small, the tightness of the thread will become poor, resulting in poor-looking stitches. Therefore, currently, the sewing operation is performed while adjusting the needle thread tension. For example, the following patent document 1 discloses a technology that detec...

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Problems solved by technology

[0003] However, in Patent Documents 1 to 3, etc., the thread tightness of the sewn product is not actually evaluated.

In addition, even in Non-Patent Document 1, the relationship between the sewing tightness and the needle thread tension is only analyzed, and it is not actually determined whether the thread tightness of the sewn product is good or not.

In particular, when the upper thread replenishment fails due to the shuttle, the stitches may skip and cause bad stitches, or if the upper thread and lower thread breaks occur and the thread breakage is ignored, it will become a defective product.

But, in prior art, can't carry out the inspection of this kind of bad stitches or defective products

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