Textile & Fashion World

Cams are the devices , which convert the rotary machine drive in to a suitable reciprocating action for the needles and other elements. In general there are two types of cams.

1. Engineering cam.
2. Knitting cam.

Engineering cam:  These are of circular type and indirectly control the motions of bares of elements. They are attached to a rotary drive shaft situated parallel to and bellow the needle bar, a number of independent cams correctly aligned movement. The drive is transmitted and adapted cam-followers, levers and rocker shafts. One complete 360-degree revolution of the drive shaft is equivalent to one knitting cycle.

In warp knitting machines four Types of cam have been employed.

1. Single acting cams
2. Cam and counter cam
3. Box cam or enclosed cam
4. Counter cam/ring cam/pot cam

Due to excessive vibration at speeds above 800 courser/minute for engineering cams eccentric drive is employed where speed is 2000courser/minute or more.

Knitting Cam:  The knitting cam is of angular type and acts directly on to the butt of needles or other elements to produce individual movement in the tricks of needle weft knitting machine as the butts pass through the stationary cam system or the cams pass across the stationary tricks. 

 

Knitting cam

Knitting cams are attached either individually or in unit form to a cam plate and depending upon the machine design, are fixed exchangeable or adjustable. At each of at least a raising cam, a stitch cam and an up throw cam whose combined effect is required. Usually four main types of knitting cams are used.

i. Raising cam:  The raising cam causes the needle to be lifted to either tuck, clearing loop transfer or needle transfer depending upon machine design.

ii. Stitch cam:  The stitch cam controls the depth to which the needle descends thus controlling the amount of yarn drawn in to the needle loop. It al so a knock-over cam.

iii. Up throw or counter cam:  The up throw or counter cam takes the needles back to the rest position and allows the formed loops to relax.

iv. Guard cam:  The guard cam is often placed on the butts and to prevent needles from falling out of track.

Function of Cam:  The functions of cam are as follows

1. To produce motion to needles .
2. To drive the needles.
3. Formation of loops.

Cam Type:
a. Engineering ----------------------- Circular type
b. Knitting ------------------------------- Angular motion

Engineering cam are 4 types :

1. Single active .
2. Cam and counter cam .
3. Box cam .
4. Counter cam / pot cam .

Knitting cam are also 4 types :

1. Stitch cam .
2. Raising cam .
3. Up throw cam .
4. Guard cam .

Knitting action :

http://textilelearner.blogspot.com/2012/12/knitting-cam-function-of-knitting-cam.html#ixzz2OHTHqWBX

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. 

http://textilelearner.blogspot.com/2011/06/cams-types-of-cams-knitting-cams_5503.html

The needles are the most important stitch forming elements. They are displaced vertically up and down and are mounted into the tricks or cuts of the knitting cylinder.
There are three types of needles namely:
1. Latch needle
2. Spring bearded needle 

3. Compound needle.

We can divide a needle into three main parts:
A. the hook, which takes and retains the thread tube looped;
B. the hook opening and closing device, that allows the hook to alternatively take a new thread and release the previous one;
C. a system allowing the needle to move and form the loop.