Q26:-With suitable sketch explain picking cycle, rapier head and rapier drive for Dornier Loom.

Ans. WEFT INSERTION SYSTEM FOR DORNIER LOOM :- Weft insertion in DORNIER LOOM is based on DEWAS SYSTEM (tip transfer) In this system, the end of weft is directly transfered from one rapier to other rapier which areRigidly driven by a rod. CONSTRUCTION:-

1. The supply packages are mounted in seperate compartment of magazine, each compartment having two spindles. One for the running package & another for reserved package.

2. Then the weft thread passes through a eye &a weft tensioner device. Then the yarn passes through an eye of the vertical selector needles.

3. Downward movement of the needle places the weft at the rapier level. Simultaneously a cam operated finger swings inwards towards the temple to ensure that the selected weft is seperated from the inoperative wefts.

CYCLIC OPERATION OF THE DORNIER LOOM:- 1. The needle presents the weft to the advancing left hand rapier which grips the weft as it

enters the shed.2. The rapiers continue to move through the shed. The right hand rapier reaches the centre a

little bit earlier and it is opened by the right hand opener lever.3. The left hand rapier inserts the weft into the right hand rapier. Due to split of the left hand

rapier, the yarn forms a bridge during the operation .Then the right hand rapier opener lever closes the right hand rapier.

4. The weft continues to unwind as the right hand rapier is withdrawn outwards, in the mean time the left hand rapier returns to its position.

5. After shed change and beat up, the whole cycle is again repeated.

RAPIER DRIVE FOR DONIER LOOM:- Rigid rapier drive is used for DONIER LOOM. Conjugate paired cams produce rotary oscillation of shaft to which an arm is fastened. The oscillation of this arm ‘B’ are transmitted to a slide carrier which is in the arm ’D’ on another shaft ’E’. There is a guardant that engages with pinion and transmits movement to a spur wheel and bevel. The spur wheel engages with the nylon rack under the rapier & moves it .Any adjustment in the slide’s position does not affect the weft transfer position of rapiers.

Fig: RAPIER HEAD DRIVE FOR DORNIER LOOM

The stroke of the rapiers can be adjusted by relative position of slide & arm ‘D’.

RAPIER HEADS FOR DORNIER LOOM:- Rapier head for Dornier loom is shown below.

In both type of rapier (right &left),a lever ‘A’ pivoted at ‘B’carries at one end a steel gripping plate ‘C’ and at the other end a protrusion ‘D’ . Between ‘D’ and ‘B’ a hardened plate ‘E’ is secured to the lever. Under the lever a set of adjustable leaf spring ‘F’ applies a downward force to the gripping plate ‘H’.

The gripping plates are of various materials depending on the type of yarn to be used.T he left hand rapier has a secondary plate ‘J’, parallel with a main plate in which is formed a guide notch just behind the gripping plates. This notch holds the yarn ‘K’ so that it bridges the gap between the two plates in a position which permits the gripping plates of the right hand rapier to grip yarn at transfer.The small plate ‘L’ controls the position of the weft in the gripping jaw. Behind both rapier head, there is replacable fibre strips ‘M’ which runs lightly against the reed .

IN FIGURE:-

A -LeverB -PivotC -Gripping plateD -ProtrusionE –Harder plateF –Leaf spring G –Main plateH –gripping plateJ –secondary plateK -YarnL -Small plateM –Fibre strip

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Hamraj Meena (21)Ravi Kumar Jain (50)