1.3 The needle with a line through the surface material after reaching the lowest point after the rise, due to friction material and sewing machine needle role in the formation of a loop. It forms a loop to enable a sewing machine (hook line) can enter the line ring, the bottom line to achieve surface ring by line intertwined.The line loop is formed from the following two factors .
When the needle is brought to the lower dead center with the thread , the tension at the top of the needle eye disappears due to the downward pulling force of the needle eye and the pressing of the needle edge and the seam material at the introduction groove . When the machine needle rises , the tension at the top of the needle eye disappears , and a part of the line segment is in a free state ( at this time , the line segment is changed shape as long as a small force is added to the line segment ).
From the structure of the needle on the needle, needle groove with a long groove and a short slot (or missing files) of the points, it is a long slot, and the other side is a short slot (or missing files). The slot is a long groove diameter greater than the diameter of the wire surface, lead groove is a diameter less than the face line of short slot (or missing files) structure. The needle exit slit material, into the side of the groove suture and suture material without friction random needle rise, which side of the groove of the suture and suture material extrusion friction, not random needle sewing material. With the rising in the friction force obviously short slot (missing files) larger than the long slot, which is a condition for the formation of loops.
When the three line seam sewing machine is empty, the formation of suture line ring mainly depends on the needle thread to tightly stitch the straight needle, so that the stitch is embedded into the needle slot, which acts as a similar seam material. Therefore, the stitch can still be formed under the condition of seamless material, which is different from other machines.
The formation and stability of the wire ring is related to the specifications, quality, material properties, texture, density, thickness, suture specification, material type, twist, twist direction, and needle and needle plate, presser foot pressure and pressing condition.
2. Thread hooking mechanisms
The mechanism that hooks the thread ring is called the hook line machine, it undertakes the function of hook line, branch line, cross line, disconnect line and place the bottom line. Common sewing machines include spindles, swinging shuttles, thread hooks, rotary hooks, fork hooks, etc. The rotary shuttles are mostly used in sewing machines with two-wire locking stitch, on the sleeve machine and on the keyhole machine. The curved needle is mostly used in the chain thread stitch sewing machine. Taut sewing machine and two, three, four, five, six-wire sewing machine. The main use of the fork hook is single-wire chain seam sewing machine. Rotary hook is mostly used on single wire chain sewing machine and nail buckle machine. When rotating hook and hook line, the difference is that the last thread ring enters the front line ring (self-connected ring, thread hook hook is line hook and straight needle). The difference between hooks and wire hooks entering the continuous intersecting form of interconnects.
2.1 Enter the coil
A sewing machine needle into the needle tip in the side of the coil is called into the loop. To form a good line ring is to let the crack is ready. The hook tip into reliable sewing circle is larger and more stable, while the possibility of sewing machine through the coil is greater, even a sewing machine relative to the mounting position the difference can be smoothly into the loop.
In order to make a sewing machine hook tip in the needle bar up to the appropriate time to enter the ring in the straight needle, the needle bar height are normal, most of the provisions of industrial sewing machine needle bar to reach the lowest when rising from 2.2 to 2.5mm, the hook or wire hook tip to the center line and the intersection of straight needle, needle in the above 1.5 ~ 2.5mm, with straight needle plane 0.05 ~ 0.1 mm. If the gap is double single straight needle, curved needle hook line (such as sewing machines), is to match the size and short straight line hook needle on the basis of taking into account the long needle for debugging.
Different machines have different debugging principles and matching sizes. In addition to adjusting according to the parameters specified in the specification, different types of equipment should also be considered as the form of the seams and the conditions of the sewing materials, according to the sewing materials. The special needs of stitches and stitches, as well as the wear and tear of machinery, may be made up by the appropriate advance or delay of the overlap time between the hook tip and the straight needle, that is, the change in the position of the intersection with the needle eye to make up for some deficiencies. In order to overcome the wire hook can not enter the coil accurately caused by the jump needle and wire closure and other problems. The other side of the line hook tip of the stitch is protruded or inclined to expand the seam circle after entering the ring, and the favorable bottom line is intertwined, and the other protruding surface of the line hook also forms the bottom line triangle coil.
2.2 When the coil is hooked up by the stitch, the process of the machine needle withdrawing from the seam material is called the de-stitch. A part of the sewing line exits the material through a long slot when the needle is withdrawn. This is to tighten the thread with the help of the thread take-up mechanism. The needle coil has been hooked by the sewing device when the machine needle is just exiting the sewing material. In the process of expanding or controlling movement, the stitches have friction with the upper and lower edge of the needle before the long needle groove and the machine needle occur relative motion, this kind of friction has a great influence on the strength of the stitches. In order to reduce friction. In order to reduce the wear of stitches and improve the sewing quality.