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Knitwear Technology Part One : Simple V-bed CAM selection. Jimmy Lam Institute of Textiles & Clothing. Learning Objectives. V-bed machine CAM geometry Double System Machines Needles and Jacks selection Pattern and limitation. Simple V-bed CAM geometry.
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Knitwear TechnologyPart One : Simple V-bed CAM selection Jimmy Lam Institute of Textiles & Clothing
Learning Objectives • V-bed machine CAM geometry • Double System Machines • Needles and Jacks selection • Pattern and limitation
Simple V-bed CAM geometry • All cams in V-bed machine are symmetrical on both side (Why?) • These cams include raising cam for moving the needles to tuck or knit position; and • Lowering cam and guide cam to control the stitch length
V-bed Cam geometry Can you tell the function of raising cam and stitch cam ? Ar :RHS Raising Cam B :Clearing Cam C:Guide Cam Sl :LHS Stitch Cam Sr :RHS Stitch Cam Al :LHS Raising Cam
Function of raising cam • For high and low butt needles, if raising cam is in full position • All needles will move up; • If in half position, only the long butt needles will move upward, short butt needles will miss • If the raising cam is out of action, all needles will miss
V-bed machine with transfer cam Transfer cam is used to push the needle to the highest position so that opposite needle can draw the loop from one needle bed to the other.
Transfer cam • The requirements for loop transfer are • Transfer cam; • Receiving cam; • Needle racking in ½ or ¼ pitch; and • Special transfer needle
Transfer action Loop is transferred from one needle bed to another needle bed via transfer cam and transfer needle
Double System Knitting • Double system means two knitting courses can be produced on one stroke of cam carriage. Two cam boxes are housed in the same carriage so two knitting courses can be produced
Can you name the following structure in double knit systems ? RR RR RR A I I RR A RR RR RR RR RR F I I RH RH RR F RR: All needles knit RH:high butt knit, low butt miss F: All needles tuck FR: high butt knit, low butt tuck A: All needles miss FH: high butt tuck, low butt miss
Patterning • Knitting pattern on jacquard knitting machine depends on • Yarn carrier change (colour change); • Needle sett out; • Stitch selection; • Needle bed racking; and • Cam function selection (knit/tuck/miss/transfer)
Please explain why the following pattern cannot be produced on high/low butt needles
Needle and Jack • To increase the pattern scope, we can put jacks under the needles, and have the option to select pattern via needles and jacks
Needle and Jack selection Both needles and jacks are used to make this pattern
Discussion • Why knitting cam is normally symmetrical on both side ? • What is the limitation of simple needle and jack selection ? • How can multi-jack selection increase the pattern size ?