Types of Shuttle Changing looms:-
The following automatic shuttle changing looms are known to be in used in cotton, silk and woollen industries.
(1) Hattersley loom.
(2) Northrop 'NS' model loom.
(3) Butterworth and Dickinson loom.
(4) Ruti loom.
(5) Jaeggli loom.
(6) Toyode loom.
(7) Crompton and Knowle’s loom, and
(8) Benniger loom.
Hattersley’s Automatic Shuttle Changing loom:-
(i) The Hattersley’s shuttle changing loom has been designed to weave the highest quality silk and rayon fabrics and is fitted with a cam type dobby upto 25 shafts or paper roll dobby upto 28 shafts , or Jacquard with single , or two or four color boxes , a side or center weft fork, a mechnical warp stop, an automatic let-off and vernier type take-up motion. The change of shuttle is effected quietly and in a manner which incurs no risk of damage to the shuttle and the weft which it contains.
(ii) The chief characteristic element, which distinguishes Hattersley’s device , which is one of the most successful modifications of the shuttle changing type from other weft changing devices in is the stopping of the loom to effect the change of shuttles, and then the restarting is automatically. The object of that course is to allow more time to accomplish the change , and so avert the straining and breaking of the mechanical parts which are more liable to occur when the changing of weft is effected whilst the loom continues to run at full speed, as in all other automatic loom.
(iii) It is also claimed that arrangement enable a loom to be run at the same speed an ordinary loom of the same width and construction, whereas continuous acting looms require to be worked at a slower velocity. Inspite of the advantages of the Hattersley type of shuttle changing loom , continuous running shuttle changing looms are also in use.
Shuttle Changing Mechanism:-
(1) In the Hattersley loom, the reserve supply of shuttles that have been previously furnished with weft are retained in a hopper or magazine which is mounted on the breast beam and facing the shuttle box on either the right or left hand side of the loom.
(2) The changing of shuttles may be affected either by the action of the weft fork only when the weft actually fails from any cause, or by the operation of a weft feeler when the pirn is bared. In either case a change of shuttles involves a series of six distinct operation which occur in the following sequence, namely;
1) Stopping the loom.
2) Raising the shuttle box fender.
3) Ejecting the failing shuttle from its box.
4) Removing from the magazine another shuttle and placing it in the emptied shuttle box.
5) Lowering the shuttle box fender back into its normal post, and
6) Restarting the loom.
(3) The operation of which the second, third and fourth are represented by diagram in figs. 187, 188, 189 and 190 are accomplished by means of a series of four tappets governed by an indented clutch wheel, all of which are loosely mounted together on the picking shaft at the loom handle side. The clutch wheel is driven by means of a pinion carried by the loose driven pulley and revolves continuously, so that when a change of shuttle is called for, an indent or notch in the clutch wheel becomes engaged by a lug . The lug, being secured to the tappets, turns the tappets for one revolution, and thereby performs the series of operation just enumerated. Another tappet , the fifth tappet, restart the loom automatically.
(4) Thus, in the event of weft either failing or becoming nearly exhausted, either weft fork hammer or else the weft feeler motion , first disengages the starting handle to pass the driving belt from the fast or driving pulley to the loose pulley, thereby stopping the loom. At the same time the series of four tappets effect the changing of shuttles.
Fig no 187, 188, 189, 190 of tappets for changing shuttle.
(5) Firstly, one of the four tappets raises the shuttle box front C, above the shuttle B, as shown in fig. 187, to permit of the removal of the shuttle (tappet 3). The tappet operates the pusher D , which advances to eject the discarded shuttle from its box whence it falls into a receptacle ,as shown in fig. 188 . Another tappet (tappet 2) next operates the feeder E, which removes the bottom shuttle from the hopper A and places it in the same shuttles box as that previously occupied by the ejected shuttle , as represented in fig. 189 and 190. The lifting of the shuttle box lever pushes the picking stick to its outer limit and makes possible the discharge of one shuttle and entrance of another shuttle (tappet 1).
The shuttle box fender now falls sufficiently to prevent the withdrawal of the newly inserted shuttle from the box as the shuttle feeder withdraws and returns to the magazine to recive another shuttle in readiness for the next change , after which the shuttle box front falls to its normal position.
(6) If the new shuttle is not in proper position in the box or anything goes wrong , the loom prevented from the restarting (tappet 4). All the movements just described are performed during one complete revolution of the tappets, and involve in a stoppage for six picks, corresponding to six revolutions of the crank-shaft. Therefore, in a loom running at a speed of 180 picks per minute, the changing of shuttles would involve a stoppage of the loom for only two seconds for operation of tappets.
Functions of Tappets in Shuttle changing looms:-
The functions of the five tappets from stopping to restarting the Hattersley shuttle changing looms are stated as follows;
(1) TAPPET 1 :- This tappet is shaped like half moon . On its upper surface it carries the rounded end of a right angled lever. At the end of the other leg of the lever there is a locknutted setscrew. When the tappet raises the lever , the setscrew is brought in contact with another lever. The lifting of lever pushes the picking stick to its outer limit, and makes possible the discharge of one shuttle and the entrance of another shuttle.
(2) TAPPET 2:- This is the longest tappet of the series and controls the feeder for the shuttles. The shuttle carrier or feeder E is pivoted at its base , but on its shoter arm. It carries a bowl that rests on the tappet. There is only one feeder has a three-fold movement. It is moved outward to deposit the shuttle in the box and then it moves back to its stationary position (figs. 189 and 190).
(3) TAPPET 3 :- This is the smallest of tappets. It operates the horizontal lever pinned to the same shaft as the picking shaft lever. To the front of the bowl lever , a rod is attached to the lever pin , and by lever and rod being depressed, the front of the shuttle box C is raised for the ejection of a shuttle , and the insertion of the another, as soon as the carrier plate has inserted a fresh shuttle in the box and makes a clearance , the box fender descends (figs.187 and 188).
(4) TAPPET 4 :- The inmost tappet is known as 'prevention tappet ' for it arrest all movements if any thing goes wrong. The front of the tappet engaged a bowl , which is pivoted in front of the tappet. The bowl lever has charge of two catches . When the bowl lever is depressed, both catches are thrown forward and are then held lifted by the lever as its tapered top. Both catches are safety catches and by means of a rod are indirectly in contact with box swell. If there is anything wrong or the fresh shuttle is not on proper position, the swell of the box is still in its inner position , and the going part cannot move further forward than the frog allows.
(5) TAPPETS 5 :- This tappet restarts the loom. When there is a safe change of shuttle, the loom is automatically restarted by means of another tappet 5 on the tappet shaft, but at the opposite end of the loom. This is a positive tappet. The tappet gives sufficient depression to the bowl lever to raise it at the opposite end, and by this the loom starts weaving . The loom stops for 2 to 4 seconds for change of a shuttle according to pick per minute in the loom.
USES:-
In weaving finer qualities of fabrics, such as, rayon, crepe taffetas etc. ,in this type of loom, there is tendency for faults in cloth known as ‘starting place' to be caused as a result of stopping and restarting a loom. For weaving such fabrics automatic shuttle changing loom, that does not stop for a shuttle change is preferred.
Previously, shuttle changing looms were very popular and were used for weaving finer and delicate yarns , but improvements in bobbin- changing mechnism have now made it possible to weave fine and delicate yarns without any damage. Today there are limited uses of shuttle-changers excepting for special purpose , such as, woollen and towel weaving with color-boxes and for several other weaves.
Hattersley’s Weft Feeler Motion for Shuttle Changer:-
The weft feeler motion, which is used with the Hattersley’s automatic shuttle changer for weaving silk and rayon, is illustrated at fig. 191.
(i) The feeler is at C, with D the front disc and B the back disc. F is the spring , and G the top of the rod that controls the front disc. The top of the rod is at I, that rises on one pick and falls on the next pick. The rod moves the right angled lever, one arm of which is at K, fulcrumed at L . At O is the projection, that moves the parts P and and the lever D and the attached stop bar T.
(ii) The lever S and U are fixed to the top rod V , and thus move together when the rod is turned. The rod U is connected at the top to the stop pointer W and rod V. The front of the pointer E is pivoted.
(iii) When the loom continues to weave , the lever U moves from position 1 to 3 in the arc of a circle, and so does pointer W, going forward on one pick ,and brought back the next pick . When the feeder C enters into the bobbin, it prevents the bar T also arrested at half traverse , and the other pointer is brought opposite the cut in stop pin. As the sley moves forward , the stop pin is forced back and stops the loom with the crank at or near its back center.
Ref:-Weaving Mechanism Book Vol. II by Prof. N. N. Banerjee.
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