Analysis Of The Difference Between Reverse Stitch And Forward Stitch Of Single-needle Lockstitch Machine

The difference between reverse stitch and forward stitch of single-needle lockstitch machine:

The biggest difference between reverse stitch and forward stitch is the different stitches. The forward stitch is a standard lock stitch, just like twisting a rope, the upper and lower threads are wound together. The official name of the reverse stitch is not known yet, so it is temporarily called the button stitch, because when reverse stitching, the upper thread is tied around the lower thread to form a knot, just like the first knot of shoelaces. Obviously, the requirements for the thread are higher, and the sewing thread is required to have higher strength, more uniform strands, and smoother and softer characteristics.

The second biggest difference between reverse stitch and forward stitch is that the timing requirements for the needle bar and the lifting teeth to feed the eccentricity are different. When reverse stitching, it is possible that the machine needle will pierce the cloth in the instant when the reverse stitch wrench is pressed and lifted. If the feed teeth are still exposed on the needle plate surface at this time, the machine needle will swing with the sewing material instantly. This is one of the reasons for the broken needle and thread in reverse stitching. In order to avoid this situation, the eccentricity of the feeding teeth should be adjusted according to the requirements of reverse stitching, so that the needle does not swing instantly when the sewing material is pressed and lifted. This adjustment avoids the problem of instantaneous swing of the needle, but it causes another problem, which is that the needle is prone to break.

The third biggest difference between reverse stitching and normal stitching is that the friction resistance of the rotary shuttle is required to be smaller and smoother when the rotary shuttle is running, so that the thread take-up rod can overcome the friction resistance of the rotary shuttle with the minimum force when tightening the upper thread. Only in this way can the pressure of the thread presser be minimized without breaking the thread. Because the friction resistance here is the force of the shuttle bowl (or shuttle rack, shuttle gallbladder) against the rotary shuttle positioning hook. The greater this force, the tighter the compression spring on the thread presser plate is required, and the greater the chance of thread breakage.

The fourth biggest difference between reverse stitching and normal stitching is that the friction position between the sewing thread and the needle is different, especially the part below the needle hole. The friction in both the forward and reverse directions requires the smoothness of the needle to be all-round, and no burrs are allowed.

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