BEAT-UP MECHANISM: CLASSIFICATIONS, CONSTRUCTIONS AND WORKING PRINCIPLE

 

Beat-up

It is the third primary motion of (loom/weaving) that pushes the newly inserted weft yarn to the fell of the cloth (with a reed attached to the sley) to make the fabric compact.

There are following types of beat-up according to different factors.

• According to number,

1. i) Single beat-up
2. ii) Double beat-up

• According to the mechanism,

1. i) Conventional 
2. ii) Cam 

• According to the movement of reed,

1. i) Real 
2. ii) False 

1) Single Beat-up: It is the mechanism where one beat-up happens by one cycle of the crank shaft after insertion of the weft.

Main Parts:

A. Crank Shaft
B. A Crank
C. Crank arm
D. Reed
E. Sley sword
F. Race board
G. Reed cap
H. Rocking shaft
I. End-frame

Parts of Beat-up Mechanism

Construction:

1. In the figure crank (B) contains crank shaft (A). A crank pin connects crank arm (C) with crank.
2. All the parts depend on End frame (I) that connects Sley sword (E) with the rocking shaft (H).
3. The top of the sley sword fulcrums the crank arm which holds crank as well as crank shaft.
4. The other topside of the sley sword contains Raceboard (F), Reed (D) with Reed cap (G).

Single Beat-up Motion

Working Principle:

1. The motor gives motion to the crank shaft enforcing crank to rotate anticlockwise and creates three simple positions. And thus three positions for the sley sword and single beat-up and backward position for the reed in one revolution.
2. When the crank revolves around the crank shaft and is at 0° with the machine, it is in beat-up position.
3. Next, when the crank is at 90° and 270°, it is in neutral down and neutral up position respectively.
4. Finally, when the crank is at 180°, it is in the backward position.

2) Double Beat-up: It is the mechanism where two beat-up happen by one cycle of the crank shaft after insertion of the weft.

Construction with Working Principle:

Double Beat-up Motion

The basic difference with double beat-up mechanism’s construction is that it has a knuckle joint dividing the crank arm. Therefore, It is the crank arm connected to the sley sword, allowing itself to beat-up action twice in one revolution.

1. When the crank arms are straight by the knuckle joint like in position 1 and 3, they’re at beat-up position.
2. But when the crank arms bend by knuckle joint like in position 2 and 4, they’re at backward position.
3. By virtue of the knuckle joint the crank arms are able to create 2 different positions twice in one revolution. And therefore, the mechanism makes double beat-up happen.

Read more: MECHANISM OF A  BASIC LOOM IN WOVEN MANUFACTURING

Sley Eccentricity: 

It is the ratio between crank radius (r) and crank arm length (l).

Sley eccentricity, e = r/l.

Pros and cons of High Sley Eccentricity:

Pros:

1. The more sley eccentricity, the more time for the pick insertion process.
2. Secondly, The more sley eccentricity, the more effective the operation.
3. Finally, the more sley eccentricity, the more velocity of the sley and thus more  velocity.

Cons:

1. Beat-up mechanism with high sley eccentricity is costlier.
2. Excessive vibration occurs as a result of high sley eccentricity.
3. It forces the sley to accelerate and deaccelerate rapidly.
4. As a result, it gradually wears down the loom frame.

Nota Bene: Universally the ratio of r:l is kept down to 3:10.