Tuesday, 13 October 2009

Warp Knitting | Stitch Forming Process on Raschel Machines

285° – knock over position
The compound needles and slides are at their lowest position (knocking-over position).
The knock-over comb bar moves back and rests just in front of the stitch comb bar. In so doing, the next to last loop slips from the needles. The last loop lies in the head of the needle and is pulled through the preceding loop when it is cast off.


345° – holding down
The knock-over comb bar moves further in the direction of the rear reversal point. The compound needles rise, the slides remain in their lowest position. The stitch comb bar holds the fabric down together with the fabric take-down. The last-laid loop slip onto the shands of the needles.


0° – rear reversal point
The slides rise but do not come out of the groove in the compound needles. The
knock-over comb bar is at the rearmost point.

40° – swing-in
Before the compound needles swing into the pattern bar of the last shogging course the under-lapping shog of the guide bars in completed. The knock-over comb bar, compound and slide bars move forward (in the photograph the compound needle is just swinging into the last shogging course of the pattern bars; on this type of machine the guide bars and stitch comb are fixed).


 105° – overlapping shog of the ground guide bars
The knock-over comb, compound needle and slide bars swing out of the stitch
comb bar into the forward reversal position (ejection position). As they move forward the compound needles pass the pattern bars and ground guide bars. The yarns now lie in the gaps between the needles. Once the needles have passed the foremost guide bar L 1(GB 1), the overlapping shog begins. The knock-over comb, compound needle and slide bars begin their movement backwards and as they pass through guide bar L 1(GB 1) the yarns laid in the underlapping slip into the hooks of the needles.

190° – closing of the compound needles
The knock-over comb, compound needle and slide bars move further back.
After the swinging through of the second shogging course the compound needles
begin to sink. The slides remain in their upper position until the needles are closed.

220° – start of the underlapping
After the compound needles are closed they move down together with the direction
of the knock-over edge. Now the underlapping of the guide bars can begin.
As the compound needles move further back the old loops slip from the shanks onto the slides. As the needles pass the knock-over edge the newly laid-in yarns in the needles heads are pulled through the old loops. When the backwards movement of the compound needles with the slide bar has been completed the latter are in the
knocking-over position (285°). The loops whick slip over the heads of the needles as a result of this are pulled by the take down over the top edge of the knock-over
sinker. Depending on the take down and yarn tension the cast-off loops are pulled
together in their final form and size.