Narrow Woven Frames and Strengths
  • Narrow Woven Frames and Strengths



    Frames and strength wires, the weaving head, the front reed, the cloth winding mechanism, the auxiliary yarn feeding line, the weft yarn feeding line, the main eccentric camshaft (drive shaft), the shedding mechanism and the weaving loom frame. power wires, It consists of wires with small holes called beads, made of steel, in the middle, through which the warp thread is passed, attached to the frames according to the weaving drawing-in plan. As with other frame weaving machines, the forces used in narrow weaving machines are rolled center hole flat steels. For this reason, they are also called flat steel strengths. In order to select the most suitable strengths for weaving production, the thickness of the warp threads, their properties, warp density (number of warp threads per centimeter), weaving machine type and weaving speed should be taken into account.





    Frames are the system that acts according to the dobby plan of the weaving weave and enables the warp threads passed through the strength wires to form a shed. According to the shed shapes, woven fabric is obtained by passing and placing the weft through the gap called shed formed between the warp threads carried by the frames moving up and/or down by forming two groups.  







    The number of frames is determined according to the warp threads making the same movement in the drawing-in plan. Each warp group that makes different movements is collected in different frames. Forces containing the same link are distributed over two or more frames, as the number of forces in a frame reaches high density or the maximum yarn tension is exceeded, causing problems in opening the shed. Light frames (for edge and pattern threads) that carry less strength are placed behind heavy frames. Heavy frames carrying high-density threads (which ensure that more than 75% of all warp threads remain on each shuttle run) should be located at the front. Strength frames are numbered from front to back. In narrow needle weaving machines, the frames work together with the hook needle, weft needle and reed.






    Movement of the frames is provided by dobby or eccentric (cam) system. Cams or pattern chain (link) mediates the movement in the eccentric system. In weaving machines, the plate called the foot is attached to the frames, allowing the frames to move down and/or up according to the cam shape (negative or positive cam) and the opening of the shed. There are separate legs for each frame.






    The legs are numbered as 201, 202, 203.....or 1,2,3,...... If the feet are not attached to the frames they belong to, the desired pattern will not be formed.

    Seen above (b) In the machine with negative cam shedding system, the cam mechanism moves the frames downwards and opens the shed (lower shed) towards the bottom, while the springs located above the frames provide the back movement. The negative shedding system is particularly well suited for high speed weaving machines.

    In the weaving machine, shedding, weft insertion and weft compaction (pouring) are the most basic operations for the formation of quality and efficient fabric. The shed is the opening with a triangular cross section, which is formed by dividing the warp threads into two groups, one upper and the other lower, before the weft is thrown in weaving machines. Woven fabric formation is realized by pressing the weft thread through the triangular cross-section opening called the shed, formed between the warp threads. Below is the shed formation on the weaving machine.  






    The shed area from the strengths to the warp threads guide rods is called the rear shed (9), and the shed area from the strengths to the reed tip is called the front shed (10). The warp threads are drawn through the forces that provide the front shed movement. Powers pull the warp threads up or down to form the shed. The warp threads pull some of their strength upwards to form the upper shed (8), and by pulling downwards, they form the lower shed (7). The connection between the weft threads and the warp threads is repeated with the opening of a new shed at each weft insertion. Warp release and fabric wrapping are also available as auxiliary movements.

    Various systems have been developed to open the shed in accordance with the knitting desired to be created and to determine the warp threads that should be located above and below the weft thread during each weft thread. The systems used to run these systems "mouth opening systems" name is given.

    Shedding systems control the shed opening process, which is the first of the weaving processes, and determines the fabric quality and the degree of machine usability. Therefore, the weaving weave feature, the dimensions of the weave pattern (weft and warp) are primarily dependent on the level of the shedding mechanism. Shedding in narrow weaving machines is possible with eccentric and link systems as well as with dobby and jacquard shed opening systems.






    Cam (eccentric, heart) and pod (pattern chain) According to the system of shedding, shedding mechanisms are the most preferred systems in narrow weaving machines.

    An eccentric (cam, heart) is a “high kinematic pair whose pair has two degrees of freedom and has point or line contact between the kinematic elements. Briefly, the cam is the body that comes into contact with this surface of a limb with a generally curved profile and another limb with a simple shape. It directs the mouthpiece movement with its cam shapes and arrangement.. The yarn movement with the eccentric is very suitable for narrow weaving machines that move very quickly, as they are sensitive and rigid. But they can be used for small weft patterns. Cams work with 8 time (weft report) repetitions. Each time slot shows shed opening and weft insertion. With narrow weaving machines, 4-6-8 or 12 weft cams are used. Mostly 8 stroke cam is preferred. This weaving number is also very important as it enables to combine the ground weavings. The camshaft rotates and repeats 8 times slower than the weft drive shaft. A cam is placed for each frame and the frame moves around this cam circumference.






    The chamber of the eccentric machine is shown below.






    After the cams are placed according to the knitting report (see below) to be made, they are attached to the cylinder in the chamber.















    The frame moves simultaneously with the weft needle, the comb and the edge knitting needle (hook needle). The table above shows the relationship between the nozzle position, the comb movement and the weft needle.




    Posted by %PM, 10% 775% 2017 20%:%Dec in Weaving

Narrow Woven Frames and Strengths