The coil sewing method is very different from that of the conventional manual sewing.In the simplest manual stitching,the sewer fastens a thread in the small eye of the end of the needle,and then penetrates the thread completely through two pieces of fabric,from one side to the other,and then back to the original side.The needle drives the thread in and out of the fabric and stitches them together.
Although the manual sewing is very simple,but to use the machine is extremely difficult.The machine needs to release needle into the fabric of the side,and then on the other side must grabbed it immediately.Then,it needs to pull loose lines out of the fabric,rotate the needle direction,and repeat all steps in the opposite direction.This process is too complicated for a simple machin.And even for manual sewing,it can only be used with a shorter line.
Instead,the sewing material simply passes the needle through the fabric.On the needle,the eye is behind the tip,not at the end of the needle.
The needle is fixed on a needle bar by a motor through a series of gears and cams for pulling up and down motion.
When the tip of the needle through the fabric,it is in a side facing the other pulled out a small coil.A device of fabric below will seize this coil,then another coil wrapped around another thread or the same thread.In the next two sections,we will see how this system how to work.
The simplest coil suture is chain suture.To make a chain stitch,the sewing machine will loop at the back of the thread with the same length.The fabric is placed on a metal plate under the needle,fixed with a pressing foot.At the beginning of each stitch,the needle pulls out a coil through the fabric.A device that makes the coil is grasped before the needle pulls out,and the device synchronously moves with the needle.Once the needle is pulled out,the cloth feeding device will pull the fabric forward.
When the needle through the fabric again,the middle of the new coil will directly through a coil.The coil device will do again to seize the line,and make a coil around the coil.In this way,each coil will have a coil fixed in place.
The main advantages of chain stitch can be sewn very quickly.However,it is not particularly strong,if one end of the thread is loosened,the entire sewing may be loosened. Most sewing machines use a stronger thread called lock seams.
The most important element in locking device is the hook of shuttle and spool assembly.The spool is a coil under the fabric.It is located in the center of the shuttle,which rotates under the drive of the motor and is synchronized with the movement of the needle.
Same as chain stitch,lock stitch is which pulls out the needle through the fabric of a coil,while moving fabric it rises again ahead of the cloth feeding teeth,then another coil set in.However,this mechanism will not suture different coils connected together,but they are linked to another section of the line is released from the spool.
When the needle is inserted into the coil,the rotating shuttle holds the coil with the hook.With the rotation of the swing shuttle,it pulls the coil around the wire from the spool.This makes the stitching very firm.