Multiple Box Motion in (automic or semi automatic) Power Looms:-

Multiple Box Motion in (automic or semi automatic) Power Looms:-

Multiple box are used to produce fabric with different colours and count. With color and counts the stripe and check fabrics can be manufactured. The main object of these multiple box is used in the weft pattern.

WEFT PATTERN:-

In many kinds of fabrics more than one color, count or quality of weft is used. Automatic change of shuttles is, therefore, essential in such looms to have a wide scope for figuring in the weft. Whilst dobbies and jacquards produce warp pattern, multiple boxes produce weft pattern in fabrics.

(a) All kinds of checks , all weft stripe, extra weft spots and fancy goods require change boxes in the looms. The variation in the order of weft change may cause various weft patterns being produced on cloth.

(b) The weft patterns are produced by multiple boxes which may be applied to one side or both.

Classification of Multiple Box Motion:-

(1) Rising or drop box motion.

(2) Circular box motion: and

(3) ‘Pick at will box’ motion.

These motions are found in a considerable variety of details, but rising and falling or drop boxes are most varied and are largely used.

Their comparative merits and uses may be summarised as following:-

(i) In drop and circular box looms, multiple boxes are applied to one end of the sley, and a single box at the opposite end. In these cases alternate picking is imperative.

(ii) In certain other looms multiple boxes are fitted at both the ends of the sley. These multiple boxes are capable of being operated for any order of wefting , including single picks of a colour or count. This type of multiple box motion, when fitted to a loom, is called a 'Pick at Will' and the loom is called 'Pick and Pick' loom. In this case, the picking mechanism will allow several picks being made in succession from either side of the sley.

(iii) The distinct feature of difference between a drop box and a circular box motion is found in the method of carrying the shuttles. In a drop box loom, shuttle boxes are arranged one above the other in shelf form, whereas in a circular box loom , shuttles are arranged in a series of cells in circular form around a common axis on which they revolve.

(iv) While the drop boxes have extensive uses in the cotton and silk or rayon industries, the circular boxes are largely used on the woollen and worsted industry.

(v) Circular boxes are generally made of six shuttle, but drop boxes are made of four shuttles.

(vi) A multiple shuttle box is no longer by from 5.1/2" to 9" or 13.97cm to 22.86 cm, than a single shuttle box.

(vii) In drop boxes alternate picking is imperative, whereas in revolving or circular boxes alternate or pick at will devices are available.

Condition of Good Multiple Box Motion:-

The following conditions are considered to good multiple box motion:-

(1) A multiple box motion should be positive in action and so connected with the other parts of the loom that will be impossible for the boxes to get out of harmony with the shedding and picking motion, whether a sley moves forward or backward.

(2) When the boxes are not mounted into their proper positions, or in case the picker or shuttle collides with the boxes, the loom or the multiple box motion should be stopped.

(3) Each set of boxes must work independently of the other set of boxes placed at both sides of the sley.

(4) The boxes should be easily adjusted for height with respect to the race , and the proper shuttle should be moved inline with the picker.

(5) Any shuttle or shuttle box at either side should be readily brought into operation irrespective of its former position . Unless a smooth movement is imparted to the shuttle, vibration of the boxes will take place.

(6) The boxes and pattern chain should be worked from the same cylinder.

(7) The multiple box motion should be provided with an efficient escape or safety motion for smooth running or stopping a loom.

(8) Shuttle should not be driven from their boxes when a loom is turned backward , for a weaver must replace them before restarting. In most cases boxes begin to remove at top crank position and complete their movements at 120°, that is , 30° passed the front center position of the crank.

DEFECTS:-

No multiple box motion can satisfy all the above conditions and the following defects are frequently met with :-

(a) If the motion imparted to the boxes is not a smooth one, vibration will take place necessitating reduced speed in a loom.

(b) Trouble is caused when the loom continues to run for two or more picks after a weft has broken . If a breakage occurs immediately before the boxes change places , two or more picks of another weft will be driven through the shed . These picks require to be removed and boxes restored to their proper places before restarting a loom.

(c) Multiple box looms are therefore, required to be provided with a center weft fork motion, and also with a fast reed motion which is necessary owing to the weight and construction of the cloth.

Types of Multiple Box Motion:-

The multiple box motion vary greatly in their construction and method of working and may be divided into two categories,

(1) Negative, and

(2) Positive box motion.

The positive multiple box motions are more numerous than the negative box motion and are more in use than the latter . The following multiple box motions are commonly used in the industry:-

Negative multiple box motin are the following:-

(i) Diggle’s chain motion.

(ii) Knowle’s chain box motion,and

(iii) Diggle’s pick-at-will motion.

Positive multiple box motions are the following:-

(i) Wrightshaw’s box motion.

(ii) Whitesmith’s box motion.

(iii) Eccle’s box motion and Cowburn and Peck motion.

(iv) Northrop four box motion .

(v) Circular non-skip box motion and

(vi) Circular skip box motion. 

Eccle’s drop motion works on the same principle as a Cowburn and Peck’s motion does, both employing a double crank and double disc.

Ref:-Weaving Mechanism Book Vol. I by Prof. N. N. Bnerjee.