The movements necessary for the stitch formation and for transferring the needle from one cylinder to the other can be briefly outlined as follows (picture 116):
STEP 1: The double latch needle is locked by the slider on the lower cylinder and starts rising driven by the butt of the slider.
STEP 2: The needle reaches a position that allows the slider of the upper cylinder to lock its head.
STEP 3: The needle taken by the upper cylinder is released from the slider of the lower cylinder.
STEP 4: The needle is transferred to the upper cylinder; the thread fed by the thread guide is received under the hook; the knocking-over of the previous stitch and the formation of the new one are carried out on the upper cylinder (purl knitting).
All the commands on this type of machine can be mechanically or electronically controlled. The mechanical control unit frequently relies on punched cards which store all the information necessary for controlling all the machine motions, for example the cam locks, the stripe pattern motions etc. The needle selection is performed by means of the butt sliders; many machines offer the possibility of controlling the needle selection by means of turrets that can drive the jacks arranged on the lower cylinder below the sliders. The arrangement of the jacks can be the symmetrical or the diagonal type; the width of the pattern area is strictly related to number of jacks.
On electronically controlled machines, needle-by-needle selection is carried out by means of individual magnets that drive the slider butts. These machines are now offered in a restricted number of versions for the manufacturing of cloths and fabrics with welt and separation thread. The diameter is usually 33 inches, the gauge ranges from E 4 to 14 and the number of feed systems is generally limited to 12.
Was this article helpful?