TYING OR KNOTTING PROCESS (A weaving process).
WARP TYING/KNOTTING PROCESS (A Weaving process):-
knotting machine dressing stand.
imge of tying or knotting machine.
When a running beam is exhusted on the loom. If the new beam design is same or the number of ends in the new beam is same then it is not to be drawn only a process alled wrap tying or knotting is done.The process of warp tying can be performed in two ways;
1) Mannual warp piecing.
2) Automatic warp tying or knotting.
(1)Manual piecing:-
In this method of warp piecing , all the actions of the process are manually performed. A well trained person does this job . Very high skill is required to perform this job . When the existing warp is exhausted, this warp beam is required to change with a new warp beam. First of all, the lease is inserted in warp sheet of the loom before unloading the empty warp beam. The empty warp beam is unloaded on the loom.
Now piecer makes the temporary piecing stand with the help of aluminium pipe and wooden blocks. The warp sheet of the new warp sheet and warp sheet of the loom and tied on both side of the temporary piecing stand. The piecer stands between the whip roller and the aluminium pipe. He takes a bunch of each warp ends from both warp sheet from one side of the machine. Now the piecer ties these bunches on his waist. He select a one end of new warp beam and one end of the warp sheet of the loom by hand. He cut both ends as per the requirement with help of a sharp knife . Now both ends are twisted together to make a joint. This action is repeated again and again till the completion of of piecing. The lease helps to separate the ends in the correct sequence and prevents the crossing of ends to each other.
DISADVANTAGES OF MANUAL PIECING:-
Manual piecing has many disadvantages, which are given below;
1) Manual piecing is highly time consuming process .
2) The ends joints are not too strong , the twisted joints may be opened during pulling of pieced warp .
3) The warp tension is not equal on both side of the warp sheet after piecing.
4) High end breakage occurs due to uneven warp tension when the loom is restored.
5) Loom effeciency reduced.
6) Extra process mayb be needed to draw broken ends.
7). There may be pattern mistake in the warp .
8) High end breakage during pieced warp pulling can be cause the end crossing.
Automatic warp tying or knotting:-
The warp tying or knotting machine is very important machine in the weaving shed. When a style of the fabrics design is repeated for a long time on loom . When the designed is repeated , fresh drawing-in warp is not required
The ends of new warp are joined with ends of warp sheet of the loom with the help of automatic warp tying or knotting machine.
The warp knotting is completed in two different following stage;
DRESSING OF WARP SHEET:-
Knotting machine dressing table.
The empty beam is unloaded from the loom and is replaced a new warp beam. Now knotter sets the knotting stand behind the loom . First of all the warp shed of the new beam is taken over the knotting stand the the ends are spread out on the stand . A brush roller holds the warp sheet temporarily. Now the lease rods are inserted into the warp sheet and the ends are tightenef by a rotating brush roller. When all the ends of warp sheet get tension properly , the warp is clamp by clamping stripes. Now knotter separate all the end with the help of a dressing brush. The brush roller is rotating after each ends separated. The process of end separation is repeated till the completion of proper end separation. Now the ends of the warp sheet are brought to there proper place with the help of a half reed (comb,)
When all the ends gets their proper places. The warp sheet fixing clamp. Now lease rods are replaced by harness string nd these are tied on both the ends of the stand
Now knotter takes two warp sheet loom over the stand and the same process is repeated as mentioned above. Now the dressing process of the warp sheet is completed and the knotter start the next step which is called "knotting."
KOTTNG:-
Knotter mounts the knotting machine by loading the gear with the toothed rack. Now the loose strings are passed, the lease pipe are tied to the right side of the stand . The power supply of knotting machine is connected to the supply point. Knotter starts the machine by pushing the start button. The machine automatic joins the ends of both warp sheet.
Structure and working of knotting machine:-
The common components and working of knotting machine are as given below;
ELECTRIC MOTOR:-
An electric motor is mounted inside the machine . The toothed pulley is mounted on the motor roller shaft. The motoin is transmitted to the mechanism by a toothed belt. It is a D C motor 180 volt A C supply is used to run this motor. A voltage stabilizer is used to supply constant voltage to the motor.This A C supply is converted in to D C automatically by voltage converter in the machine.
CONTROL UNIT:-
All the functions of knotting machine are connected electronically. The speed of the machine is inserted by rotating a knob mounted on the top of the machine. If a machine fails to select the end of the top or bottom layer , feelers sends a signal to the control unit and stops the machine immediately. All the machine operations are initialised by the push buttons .
KNOT COUNTER:-
A knot counter is mounted on the top of the machine, which counts the knot of knots completed during the process.
MACHINE TRAVELLING GEAR:-
These gears are mounted in the bottom of the machine. When knotting machine is kept over the stand , these gears are engaged with a toothed rack of stand by processing the gear locks. When the lock is passed, the travelling gears come down wards and engaged with the teeth of the rack . These toothed racks fixed . When the machine gets started , the geats also rotates . The machine travels on the rack with the help of rotating gears on a toothed rack.
SELECTION NEEDLE:-
Itis a very very important part of the knotting machine . Two needles of same size are used during the process . The function of the selection needle is to select a single end from each layer of the warp sheet. The top needle make a selection of ends of top warp layer and bottom needle makes the selection of end of the bottom warp layer. These selection needles are neede to change when warp count changes . Different size of selection needles are put in the reserve according to various type of warp count to be used.
YARN FEELER:-
The function of the feeler is to send the confirmation of the selection of ends to be knotted. If proper selection is not perform, the control unit stops the machine immediately. In the knotting machine, two feelers are used, one for the bottom larger and the other for the top layer. These feelers move by the pressure of the yarn.
YARN CARRIER:-
The main function of the yarn carrier is to carry the selected ends in the yarn gripper. When the selection process happens , the top selection needle pushes the end downward and the bottom selection needle pushes the ends upward. At the same time, the yarn carrier starts to move towards the yarn grippers. The top and bottom hooks of the yarn carriers catch the selected ends and carry them into the yarn gripper.
GRIPPERS:-
The main function of yarn grippers is to hold the selected ends during knotting. Two grippers are used in the knotting machine. The top gripper holds the ends of the bottom layer . The push springs are used to create enough gripping pressure between the gripping plates of the yarn gripper. The gripping pressure can be adjusted with the help of a screw. There is a need to change gripping pressure when warp count is changed.
MAIN CUTTER:-
The function of the main cutter is to cut the tails of the end after the gripping of the ends by the gripper. There are two cutters used in the knotting machine. These cutters work positively. The cutter cuts the tails of the top end and the bottom cutter cuts the bottom ends.
KNOTTER HOOK:-
When the extra length of both ends are cut, the knotter hook starts to rotate . It wraps both the ends together with it and makes a loop.
KNOTTING NEEDLE:-
The knotting needles is fitted in the hollow pipe of the knotter hook. Ii makes in and out movement during operation. When the loop is formed ,the needle comes out and catches the ends . Now knotting is completed.
WASTE CUTTER:-
When the knotting is completed, knotted ends have extra tail length. It is very difficult to pass these knotted ends through the eye by heald wire and dents of reed. It needs to cut the extra length of tail. The waste cutter performs this job.
LEASE PIPE:-
The lease pipes are used to select the ends according to the sequence. The lease pipe makes up and down movement and separates the ends according to the sequence.
PRECAUTIONS TO BE TAKEN IN KNOTTING PROCESS:-
Knotting or tying is very delicate process. Any negligence the process may be dangerous on weaving . Following precautions should be taken during the process;
1) The dressing of both warp sheet should be done perfectly.
2) All the ends should have enough and equal tension .
3) There should be no crossing ends when the warp sheet is being clamped.
4) Each warp layer should be clamped properly. There should not be any slippage between clamp and yarn.
5) The tension on the warp sheet should be according to requirement.
6) The length of the tail of knotted end should be adjusted properly by adjusting the main cutter.
7) The knot should be fully tightened to prevent its slippage.
8) If the knot is loose , the length of knotting needle should be adjusted by making a slight band in it.
9) The gripping pressure should be adjusted properly.
10) The edge of the main cutter should be enough sharp to cut the ends.
11) The selection needle should choose precisely. In correct selection may cause double selection of ends or selection failure.
12) The waste cutter should work properly, improper working of it may cause break to the ends.
13) The quality of knot should be checked
manually after regular intervals of times.
14) Cutting action of the main cutter should be clean. If there is any fibrous parts at the tail of the end , it may be caught by grippers.
15) Yarn feelers should work properly.
16) Machine should be cleaned with karosene oil . The machine should be run in a tub of filled with karosene oil for half an hour .
17) The oiling of the machine should be properly. For the oiling of the machine, it should be run in the tub filled with sewing machine oil (22 number oil) for half an hour.
18) Moving parts of the dressing stand should be oiled properly.
. Ref:-https://www.textileadvisor.com
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