Raschel Machine PDF

Knitting Technology  Raschel Machine The main parts of the raschel machine are : ►The ground beams and pattern beams having an access from front, top and back. ►The tension bar (one for each warp) which maintains tension in the warp threads. ► Guide bars and guide bar levers and...

Knitting Technology  Raschel Machine The main parts of the raschel machine are : ►The ground beams and pattern beams having an access from front, top and back. ►The tension bar (one for each warp) which maintains tension in the warp threads. ► Guide bars and guide bar levers and the sley bar.  Raschel Machine ►The knitting elements comprising guides, sinkers, needles, latch needles and trick plates. ►The fabric tension rollers, situated close to the knitting elements. ► The fabric batch roller. ► Main drive for the cam shaft. Knitting Elements  The Needles ►The needles used on the raschel machine are latch needles which are self acting. ►They are usually cast in lead of 25 or 50 mm wide which are fitted in a needle bar. ►The number of needles per 25 mm depends on the gauge of machine i.e. 14, 18 or needles on 28, 36 or 48 gg machine respectively.  The Guides ► The guides are steel pressed blades with a hole. ►They are cast in a unit of 25 mm in width and screwed onto guide bar. ►For the ground structure, front two guide bars are sufficient.  The Guides ►The guide bars producing the pattern however, only require a thread at each repeat of the design every two, three or four inches. ►Hence pattern bars are provided with finger guides. It has possible to accommodate upto guide bars.  The Sinkers ►Sinkers are thin metal blades cast in blades and the blades protrude between the needles from the rear of the machine. ► These are attached to the sinker bar. ►The motion to sinker bar is backward and forward at the appropriate time of the knitting cycle.  The Trick Plate ►This is also called as ‘ knock-over comb ’, which is a vertical plate extending the width of the machine. ► It is made of thin punched metal blades cast in the unit. ►The needle moves up and down between the blades of trick. ►The blades of the trick plate ensure an exact knocking- over of the stitches especially in long under- lapping.  The Latch Wire ►This is a thin cylindrical wire stretched across the machine just behind the needles. ►This wire hinders the closing of the latch needles when the newly formed stitch loop slides downward over the spoon.  Knitting Cycle ►Holding down. The guide bars are at the front of the machine, completing their underlap shog. ►The sinker bar moves forward to hold the fabric down whilst the needle bar starts to rise from knock-over.  Knitting Cycle ►Clearing. As the needle bar rises to its full height, the old overlaps slip down onto the stems after opening the latches, which are prevented from flicking closed by latch wires. ►The sinker bar then starts to withdraw to allow the guide bars to overlap.  Knitting Cycle ►Overlap. The guide bars swing to the back of the machine and then shog for the overlap.  Knitting Cycle ► Return swing. As the guide bars swing to the front, the warp threads wrap into the needle hooks.  Knitting Cycle ►Latch closing. The needle bar descends so that the old overlaps contact and close the latches, trapping the new overlaps inside. ►The sinker bar now starts to move forward.  Knitting Cycle ►Knocking-over and underlap. As the needle bar continues to descend, its head passes below the surface of the trick-plate, drawing the new overlap through the old overlap which is cast-off and as the sinkers advance over the trick-plate, the underlap shog of the guide bar is commenced. Knitting Cycle Knitting Cycle Jacquard-System