Jacquard machine and Jacquard shedding

Introduction

To weave a fabric on loom, forming a shed is necessary. The tappet shedding is the simplest one. It can be used to weave plain, twill etc. Later, the dobby was invented. It can be used to weave more complicated weaves, such as diamond, diaper and some compound weaves.

Jacquard design

But dobby shedding can not fit the requirement of large pattern which need not only a small group warp threads lifting in same way, but also the single thread lifting as well. See Fig. above. So another loom is to be created to satisfy the demand.

 Jacquard machine and Jacquard shedding

   1: hooks   

   2: knife 

Jacquard

   3:knife frame 

   4: neck cord

   5: rod   

   6: grade

   7: horizontal needle 

   8: needle broad

   9: cylinder  

   10: spring box

   11: spring  

   12: card

The principles of the Jacquard shedding are described as below:

Ø  The warp threads are lifted by hooks 1, which are arranged in rows.

Ø   The hook is made of wire. The top bent part of hook can be engaged by the knife 2.

Ø   The knives are mounted in the knife frame 3, which reciprocates vertically once every pick.

Ø  Each hook is connected with horizontal needle 7, which can deviate the hook to the left.

Ø  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.

Ø   If there is no hole in the card against the needle, the card presses the needle, moves the needle and shifting 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.

Ø  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.

Ø  The number of holes in the card determines the number of warp threads to be lifted in the particular shed, when this card operates.

Ø   And the number of cards in the chain equals the number of weft threads in the repeat.