Textile & Fashion World

Cams are the devices which convert the rotary machine drive into a suitable reciprocating action for the needles and other elements.The cams are carefully profiled to produce precisely-timed movement and dwell periods and are of two types, engineering cams and knitting cams. The movements may be represented in the form of a time-displacement graph .

Types of Cams
There are two cams
1.Engineering cam
2.Knitting cam

1. Engineering cams
Circular engineering cams or high speed eccentrics control the motion of bars of elements which move en masse as single units in Cottons Patent and warp knitting machines. They are attached to a rotary drive shaft situated parallel to, and below, the needle bar.A number of identical cams are positioned along the shaft to ensure correctly aligned movement. The drive is transmitted and adapted via cam followers, levers, pivots and rocker shafts. One complete 360-degree revolution of the drive shaft is equivalent to one knitting cycle, and it produces all the required movements of the elements in their correctly-timed relationship.

2. Knitting cams
The other type of cam, the angular knitting cam (see Fig), acts directly onto the butts of needles or other elements to produce individual or serial movement in the tricks of a latch needle weft knitting machine.

Two arrangements exist:
(a) Revolving cylinder machines – the needle butts pass through the stationary cam system and the fabric hanging from the needles revolves with them.

(b) Reciprocating cam-carriage flat machines or rotating cam-box circular machines – the cams with the yarn feeds pass across the stationary needle beds. 

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