Single Lift Jacquard Mechanism

Experiment Name: -Study on the single lift jacquard mechanism.

Introduction:

In weaving if we want to make any design in our fabric we have to separate the warp yarn according to our weave plan. In tappet or dobby shedding we have some limitations in shedding for a critical design. But in jacquard shedding it can be done easily. Jacquard is a shedding device placed on the top of the loom to produce large no of patterns by using a very large no of warp threads separately by means of harness cords, hooks and needles. The figuring capacity of a jacquard is 1800+. It means it can produce design with more than 1800 warp threads by controlling them individually, which is far beyond the capacity of a dobby or tappet loom.

Objectives:

    To know the construction of Jacquard shedding mechanism.

    To identify the different parts shaped this shedding.

    To learn the mechanism of jacquard shedding.

Main parts:

1. Pattern chain.
2. Motor.
3. Pattern cylinder.
4. Needle. 
5. Knife.
6. Harness cord.
7. Neck cord.

8. Comber board.
9. Top board

10. Hook. 

11. Grid bar

12. Dead weight.

13. Spring board. 
14. Needle board. 

Fig: Single lift jacquard shedding mechanism.

Shedding mechanism:

The single-cylinder Jacquard machine is shown in Fig. l0.1. The threads are lifted by hooks 1, which are arranged in rows. In the cross-section, where the vertical plane cuts the machine at the short row of hooks, 8 hooks can be seen. There are a greater number of hooks (50 in some cases) in the long row. The hook is made of wire. The top bent part of hook can be engaged by the knife 2, which is placed in horizontal position parallel to the long row of hooks. The number of knives equals the number of the long rows of hooks. The knives are mounted in the knife frame 3, which reciprocates vertically once every pick. The bottom part of hook is bent in the form of loop, and the neck cord 4 is attached to this part. The bottom part is placed over the rod 5. The rods are arranged in the grate 6.

Each hook is connected with horizontal needle 7, which can deviate the hook to the left. Eight needles are placed in the same vertical plane, forming a short row of needles. The right-hand ends of the needles protrude at the side of the machine, passing through the holes of needle board 8, which holds the ends of the needles in the proper position against the holes of cylinder 9.

The left-hand end of the needles is positioned in the spring box 10. The spring 11 is intended to return the needle to initial position after the needle has been deviated by the card 12.

The harness cords are attached to each neck cord 4. They are drawn through the holes of the comber-board which is placed in the horizontal position above the warp parallel to the fabric fell. The length of the comber-board is a little bit greater than the width of the fabric. The comber-board is intended for uniform     arrangement of the harness cords.

To the bottom end of harness cord, a heald, or mail, is attached, to which a weight or lingoes is suspended. By means of this weight the heald, warp thread, cord and hook are returned to their initial position after they have been lifted.

At machine operation, the cylinder moves to the left, bringing the card to the needles. And if there is no hole in the card against the needle, the card presses the needle, moves the needle and deflects the hook to the left. The hook will not be engaged by the lifting knife. The warp thread remains in the lower position, forming the bottom part of the shed.

If there is a hole in the card opposite the needle, it is not deflected. The hook remains over the knife and at the next moment, the knife grasps it while going up, and lifts it. As a result, the harness cord and the warp thread are lifted. The warp thread forms the top part of the shed.

Thus, if there is a hole in the card, the warp thread is lifted and overlaps the pick. The number of holes in the card determines the number of warp threads to be lifted in the particular shed, when this card operates. And the number of cards in the chain equals the number of weft threads in the repeat. It should be taken into consideration while constructing the Jacquard design and the card-cutting tables.

The warp repeat of the fabric to be produced depends on the type of Jacquard machine. The number of differently interlacing threads in the fabric can be equal to, but should not exceed, the number of hooks in the machine. It should be taken into account while calculating the necessary, number of hooks for producing the fabric of a given warp repeat.

 Conclusion:

From this experiment we learn jacquard shedding mechanism. jacquard shedding mechanism is very  important for driving loom. It is also important for fabric design. By this experiment we also learn the different parts of this mechanism. This would be very helpful in our future career.