Fabric manufacturing process-2

Fabric manufacturing process-2

Weaving:-

Weaving is a process in which yarn is converted into fabric.

Transmission of motions in loom

Transmission of motions to some of the important loom components has been shown in figure.

Transmission of motions

The loom pulley get motion from motor pulley directly. The crank shaft which has a special design is connected with the loom pulley. The revolution per minute (rpm) of the crank shaft is equal with the loom speed ( no. of picks inserted per minute or picks/minute). The beat up is done by the reed which is carried by the sley and the latter is connected with the crank shaft. One revolution of crank shaft causes one beat up. Therefore, if 200 picks are being inserted per minute, 200 beat ups are required in a one minute. Thus the rpm of crank shaft is the 200.

Shedding:-

Shedding is a process in which warp yarn is separated into two layers by Heald shafts.

Shedding is mainly four types

Sufficient gap is created between them for the uninterrupted passage of the weft from one side of the loom to other.

1. Crank shedding
2. Tappet shedding or cam shedding
3. Dobby shedding
4. Jacquard shedding

All weaving machines control warp yarns to form a shed.

1. CRANK SHEDDING:-

It is simple shedding mechanism.

It is only used in plain weave fabric.

In this mechanism harness is controlled by Crank shaft of weaving machines.

2. Tappet shedding:-
Tappet shedding is also known as cam shedding. Tappet is a type of cam to which a rotary motion is given for the purpose of producing reciprocating motion in rods and levers by sliding contact.

Tappet shedding are two types

1. Negative tappet shedding
2. Positive tappet shedding

Negative tappet shedding

Cross section view of tappet shedding

Top view of tappet shedding mechanism

Construction of mechanism:-

1. Tappet achieve motion from bottom shaft.
2. The bowls are are placed on the surface of treadle lever.
3. Both treadle lever is connected with lever.
4. Lamb rods,Heald shafts, are connected to front side of treadle lever.

Working of tappet shedding:-

1. Tappets are receive motion from bottom shaft.
2. When tappets rotate the nose of tappet strike on  the bowls of treadle lever which move down with every strike.
3. The treadle lever pull the lamb rod when tappet strike on it. Due to the pulling operation the Heald shaft also move downward. 
4. There is returning spring set upto the top of the loom frame to send back the Heald frame to previous position.
5. And this spring system is continuously running.

Negative tappet shedding