Fabric Club Of BD: 06/01/2011

THE CENTRE SHED JACQUARD MECHANISM

Labels: Weaving Manufacturing Technology | at 6/29/2011 10:24:00 PM

The centre shed jacquard

As the title suggests, the centre shed jacquard machine is built to produce a warp shed on the closed & centre shedding principle. It consequently merits all the advantage which characterizes this principle of shedding, but it also inherits all its defects.

A centre shed jacquard is very suitable for use in weaving figured gauzes where one or two dopes are placed in front of the harness mounting.

The chief details of mechanism in the centre shed jacquard are supplied in fig: 1; which is a line diagram, showing one row of upright and needles, together with a vertical section through the griffe blades and upper and lower reciprocating boards. A indicates the top and usual griffe bars’ the resting or suspension hook board free to rise or fall. The griffe A is connected to the spindle C at the position D and the board B is similarly connected to the second spindle E at the position F. The uprights are shown at G and the cross wires or needles at H. The usual card cylinder, needle board and spring box are also indicated.

Fig: 1

The diagram is painted and the cards cut in the usual way. There are two jacquard cross heads K and L and two head levers and reciprocating rods and a double throw eccentric as in double lift machines, but the eccentric is set screwed fast to the crank shaft, so that as the cross head K rises and falls, the cross head L falls and rises once for each pick of weft or revolution of the crank shaft.

Action of the mechanism

The crank shaft of the loom revolves as usual once, for every shot of weft. The cross head K raises with the spindle C and griffe A with all the hooks G that have been left over the griffe knives, according to pattern, to from the top warp shed. Simultaneously the cross head L with spindle E descends together with the bottom board B supporting all the hooks G that have been left clear of the top knives in griffe A ,according to pattern , to from the bottom shed. Then the weft is inserted and the griffe A descends whilst B ascends until the uprights G meet in the centre, irrespective of the position which they are to occupy on the next and succeeding picks of weft. The operation is similarly repeated for each shot of weft.

NOTE: In the given diagram the shed is fully opened.

DEVOGE'S CROSS BORDER JACQUARD

Labels: Weaving Manufacturing Technology | at 6/23/2011 12:36:00 AM

Devoge’s cross border jacquard

This machine is a double acting, double cylinder jacquard but for cross borders is worked as a single cylinder machine with either cylinder at will. Fig: I is a diagonal representation of the mechanical details employed for locking and detaching either cards cylinder by hand to suit the requisite length or number of repeats of pattern for either sets of cards.’

A is the reciprocating rod operated from an eccentric on the crank shaft of the loom; B is a stud connecting the rod A with a lever C s crewed to the shaft D which extends across the length of the machine and near its base. B is a lever set sewed at right angles behind C to the same shaft D. An adjustable stud F combines the lever E with the link G which in turn is adjusted through the stud H to the lever I pivoted at J.K and Kꞌ are two studs set equidistant from the common fulcrum J.L is a connecting arm pivoted at K. Near the free end the arm L a special socket M is

Fig: I

Formed, which is free to lock as required with a suitable formed stud N, securely fixed near the base of the swing batten lever O, pivoted to a fixed bracket projecting from the top of the jacquard framework at P. The position of the card cylinder is shown at Q. The extremity of the arm L is linked by the connection R to a small lever S, set screwed to the shaft T which extends and is fastened to the swing batten O and its duplicates for the same cards cylinder. Immediately behind the lever S and set screwed diametrically opposite to it, is second lever U to which a cord V is attached. This hangs down to within the control of the weaver. Corresponding details, from K to V inclusive, are indicated from Kꞌ to Vꞌ for controlling the card cylinder on the opposite side of the jacquard machine. Portions of the needles and needle board for the right hand cylinder are given at W, and for the left hand at Wꞌ.

Action of the mechanism

In the illustration ,the socket Mꞌ of arm Lꞌ is in working contact with the stud Nꞌ in the swing batten lever Oꞌ , so that card cylinder Qꞌ will strike against the needles Wꞌ on every short whilst this arrangement last. But immediately weaver stops the loom, pulls down and makes fast the cord Vꞌ he elevates through the medium of parts Uꞌ, Sꞌ and Rꞌ the free arm of Lꞌ and detaches the socket Mꞌ from its connections Nꞌ and swing lever Oꞌ. Simultaneously the cord V is released and the arm L falls, by gravity ,on to the stud N ,so that by turning the loom slowly ‘over; the notch M falls over the stud N and locks itself , by which means the cylinder Q is in working operation for as long as required.

CROSS BORDER JACQUARD MACHANISM

Labels: Weaving Manufacturing Technology | at 6/22/2011 02:19:00 PM

Cross border jacquard mechanism

Cross border patterns are specially adapted to the manufacture of handkerchief, napkins, damask; table covers shawls tapestries and carpets. The arrangement of the mechanism for producing the side borders and the body or center for any of these types of woven figured fabrics present few difficulties , one portion of the upright hooks being set apart for weaving the borders and another for producing the center. When two or more jacquard machine is used one is frequently reserved for the border and the rest for the center. The harness cords are tied up to their respective sets hooks or machine and passed through the comber boards to suits the side borders and center.

The difficulties being when having woven one or more repeat of patterns it is necessary to producing a change or cross border which shall balance the side borders and make one complete square or oblong pattern. The manufacture of bordered fabrics involves the adoption of one or more other of the fallowing mechanical methods.

1) Whenever the center and the side border constitute only one repeat of pattern, it is usual to stamp two repeats of the cross border and one repeat of the center but to lace the second set of border cards the reverse way making one continuous chain so that the loom can run without interruption for change of pattern. When only a small quantity is required to be woven the cross border cards are only stamped for one repeat; this are woven forwards, before weaving the center and backwards after the center has been woven. Where a large number of webs have to be produced the former plan is sometimes adopted even when there are two or more repeats of pattern for the center to be woven withes very long length of table covers etc this plan become most expensive involving the use of many thousands of cards a greater number than the loom is capable of accommodating.

2) Two sets of cards are cut one for the center and sides and the other for the cross border the latter consisting of two repeats laced in opposite direction. As many repeats of the center as may be required are woven then by hand the cross border cards are substitute over the cards cylinder and adjusted so as to start with no 1 card and the whole sets are woven over once when the cards are again changed by hand to the first set; the operation are similarly repeated until the request quantity of material has been woven. The slowness and inconvenience of this method have led to the introducing of several semi or wholly automatic device.

3) A common method consists in employing two sets of cards with two cards cylinder as on the double lift principle. One sets of pattern cards and card cylinder controls the centre and the other set and cylinder the cross border. The cylinders are designed to strike on every pick but are only in action one at a time according to whether the centre or cross border is being woven. Whenever either cylinder has to be put into action the other must be simultaneously thrown out.Numerous inventions have been designed whereby this operation may be performed by hand or automatically. The mechanism which will perform these changes automatically is a desideratum and ideal but such motion of necessity involve very many mechanical details and complications for which reasons they do not readily find favor.