Introduction to Warp Knitting
• In a warp knitted structure, each loop in the horizontal direction is made from a different thread and the number of threads used to produce such a fabric is at least equal to the number of loops in a horizontal row.
• In warp knitting, the thread runs thoroughly in a vertical direction
• In a weft knitted structure, a horizontal row of loops can be made by using one thread and thread runs in horizontal direction.
• Warp guides are thin metal plates drilled with a hollow in their lower end through which a warp end may be threaded if required, they are held together at their upper end in a metal lead and are spaced in it to the cam gauge as the m/c
• The leads in turn are attached to a guide bar so that the guides hang down from it with each one occupying a position at least midway between two adjacent needles in this position. The warp thread cannot be received by the needles and it will merely produce a straight vertical float.
• The needles only receive the warp thread in their hooks if the guide bar overlaps across their hook or across the side remote from their hooks when the guide bar underlaps.
- A bar running the full width of the m/s and equipped with guides through which threads are passed so that the lateral motions, imparted to the guide bars by the pattern control device, are transmitted to the threads.
- The individual guides are usually cast in 1 unit which in turns are fitted on the guide bars.
- The guides swing between and around the needles in order to wrap the yarn around them to form a new loop. They also shog side ways to connect the wales into a fabric.
- The minimum no of guide bars and warp sheets for commercially acceptable structures is usually two.
- The identity Y-shaped chain links are similar in appearance to a turning fork with the fork and leading. The tail of the preceding links fits into the fork of the succeeding link. The links are held together by pins that are pushed through holes in the sides of the fork and tail. The pins pass through all the tracks and chains, and the ends fit into grooves in the serrated flanges of the pattern drum so that as the drum turns, the chain links are advanced in unison in correct timing relationship.
- The link is slightly arched to fit the surface of the pattern drum; the forkside is the leading part of the link when connecting a chain. Links are made to fit certain m/c gauge. To eliminate any confusion, the gauge is stamped onto the links together with the height of the link are ground to produce a slope. The angle and length of the ground edge must be very accurately set so that the shogging movement is correctly timed.
The shogging movement is initiated by varying the radius of the continuously turning pattern shaft either in the form of different heights of pattern links which poses over a pattern drum attached to the shaft or in the form of carefully shaped solid metal circular cams, termed pattern wheels, attached to it. An increase in height one link to the next produces a thrust against the end of the guide by shogging it positively into the m/c a decrease will produce a negative shog towards the pattern shaft as the result of the action of a return spring. A constant height will produce no shog if the guide bar will continued to swing through the same needle space. The periphery of the pattern wheel or chain track is scanned by a roller which is link by a flexible jointed push-rod to the end of the guide bar. The under side of the rod near the roller is supported on the side with moves freely or a metal surface as shogging occurs.