The principle of stitching Just like a car, the basic principle of most sewing machines is the same. The heart of the car is the internal combustion engine, the sewing machine is the core of the sewing system.
Coil sewing methods and ordinary hand-sewing vary widely. In the simplest hand-stitching, the sewer attaches a thread to the small eye at the end of the needle and then passes the needle together through two pieces of fabric, going from one side to the other and then back to the original side. In this way, the needle drives the thread in and out of the fabric and sews them together.
Although this is very hand-made, it is extremely difficult to stretch it with a machine. The machine needs to release the needle on one side of the fabric and then grab it again on the other side. Then it needs to pull the loose thread all the way out of the fabric, turning the needle in the opposite direction and repeating all the steps in the opposite direction. This process is too complicated for a simple machine, impractical, and easy to use even with short lines, even to the hand.
Instead, the sewing machine simply passes the needle portion through the fabric. On the needle, the needle's eye is behind the tip, not at the end of the needle.
The needle is fixed to the needle bar and the needle bar is pulled up and down by the motor through a series of gears and cams (described in detail later).
When the needle's tip passes through the fabric, it pulls out a small loop on the other side. A device underneath the fabric grips the loop and wraps it around another loop or another loop on the same line. In the following two sections, we will see how this system works.
The simplest stitch is chain stitching. To sew a chain stitch, the sewing machine looped back the same length of thread behind the thread. The fabric is located on a piece of metal under the needle and secured with a presser foot. At the beginning of each stitch, the needle pulls a loop through the fabric. A coil-making device grasps the coil before the needle is pulled out and the device moves synchronously with the needle. Once the needle is pulled out of the fabric, the feed dog device (described later) pulls the fabric forward.
When the needle passes through the fabric again, the new coil will pass directly through the middle of the previous coil. The coil device will grab the wire again and make the coil around the next coil. In this way, each coil holds the next coil in place.