Wednesday, July 3, 2019

SECTIONAL WARPING PROCESS

INDIRECT WARPING OR SECTIONAL WARPING:

In this method of warping, the warp ends are first wrapped on the warping drum and then transferred on the weaver’s beam. This warping method is mostly used for warping of multi plies yarn, multicolour warp, continuous filament yarns. The single ply can also be used in this machine. Since the warp ends are wrapped over the drum in no. of sections, so that warping with less no. of warp packages is possible in this method. This method becomes more useful when required warp length is very low.

STRUCTURE AND WORKING PRINCIPLE OF INDIRECT OR SECTIONAL WARPING MACHINE:

The common parts of indirect or sectional warping machine and their working is described below:

CREEL: 

The yarn packages are mounted on the creel. It is very important part of warping machine. Creel is a frame of round or square section pipes and iron channels. The cone holders are arranged in vertical columns on the both side of creel 50 columns of cone holders in both side of creel are there in the creel of sectional warping machine. The creel of sectional warping contains 8 rows in each side. The number of columns varies according to requirement of creel capacity.  In this creel, yarn packages are mounted on the cone holders from outside of creel. After loading the yarn packages on the creel, the stands of creel are revolved at 180 degree. Yarn guide and a tensioner are provided in the creel for each warp end. These are mounted on the iron frame which can move away by rotating hand wheel or electric motor. The yarn coming from package first of all passes through the ceramic yarn guide then it passes through yarn tensioner.


The main function of tensioner is to impart sufficient amount of tension to the yarn. Normally inverted cup and dead weight washer type of tensioner is used in the warping machine. The number of washers and their weight depends upon the yarn count to be used in the warping process. As the yarn count becomes finer from coarser, the number of washers is reduced its weight is also reduced if necessary. In automatic creel, the tension of all tensioner is reduced or increased by a mechanism, which is operated by an electric motor. Now the warp end passes through many ceramic guides which are arranged at equal distance to each other. The distance depends upon the length of the creel. The main objective of these guides is to keep separate each end and to prevent end to end entanglement during warping. Second objective of these guide is to provide enough support each end. The yarn sagging problem creates due to insufficient support to the yarn during warping because a long length of yarn try to sag due to its own weight. Thus enough support needs throughout the passage of warp end. Now the next passage of warp end is drop wire. Its objective is to stop the machine immediately when end breakage occurs. The creel is equipped with fully automatic warp stop motion. The indication lamps on each row is provided in the creel whenever ends breakage occurs the indication lamp puts on immediately and machine is stopped. These indication lamps helps the operator to identify the correct situation broken end in the creel.

SEPARATING RODS:

The ends coming out from drop wire passes between the separator rods. The ends of the first top row passes under top separator rod. Ends of other rows are passed through separator rods as per row’s number respectively.



Separator rod helps to prevent the warp ends to be entangled to each other and makes smooth movement of ends during operation. It plays very important role in warping of multicolour warp of single ply yarn which necessitates sizing. The warp separation leases are inserted with the help of these separator rods.

LEASE REED:

It is located just after the separator rods. Its function is to help to insert the lease (the lease contains two strings). All the odd number ends pass over the first string and even number ends pass under it. Now odd number ends change their position and pass under the second string. The even number ends also change their position too and pass over the second string).


This reed is design in such a way that the warp ends are divided in two layers, when it is lowered or lifted. A pneumatic cylinder is used to lift or lower it. In some machines toothed rack, gears and electric motor perform this action. 

FLAT OR V- REED AND ITS MOUNTING TABLE:

  The yarn now passes through the dents of flat or v – shape reed. The main role of it is to keep the warp ends parallel to each other. It also maintain the equal space among the all warp ends. The number of ends per inch in the weaver’s beam depends upon the reed count and denting order used.


This reed is mounted on the reed table which can move left and right direction by rotating a hand wheel fitted at one side of table. Reed can also be turn at certain angle for adjusting section width whenever flat reed is being used. When v - -shape reed is used, the adjusting table has the mechanism to reduce or increase the width of reed. 

GUIDE ROLLERS:

The warp ends now pass between two guide rollers. These rollers are made of stainless steel, Teflon or vacalite fibre sheet. Lengthwise groves are made on these rollers which help to spread the warp end in the section.


These rollers are not driven positively. Yarn tension helps to rotate these rollers.

WARPING DRUM:

This is a metallic drum. Its diameter vary from 2.5 to 3.0 metres according to make of machine. The length of drum vary according to maximum beam width required to be warped. The one side of drum is designed in conical shape. The cone length varies from 1100 – 1200 mm.

 The surface of conical portion of drum is made rough to prevent slippage of yarn during warping. The drum rotates by electric motor in anti-clockwise direction during warping process.   

HYDRAULIC DISC OR DRUM BRAKES: 

The main function of brake in the warping machine in to break the momentum of drum rotating at high speed in case of machine stoppages. Two types of brakes are used in the machine. In drum brake system, the brake drum is mounted on the shaft of warping drum. It rotates with warping drum. A brake belt rests on the brake drum. One end of belt is fixed and other end is connected to hydraulically operated arm. When machine stops, the arm pulls the brake belt and exerts pressure on the brake drum. Thus machine stops immediately. This breaking system also provides tension to warp during beaming process. in disc brake system, two brake discs are mounted on the drum shaft at the each side of drum. Brake shoes are also fitted on each disc. These shoes are operated hydraulically.


When machine stops, brake shoes acts immediately and grip the disc. Thus machine stops immediately. It also provides tension during beaming process.



DRUM TRAVERSING MOTION: 

The whole machine is mounted over the traverse rail. Four wheels are provided in the machine which make the machine movable in left and right direction. A gearing system and electric motor is used to perform traverse motion to the drum. When the yarn is wound over the cone drum, the drum moves in left direction gradually to achieve conical shape of section. A square threaded shaft rotates through gearing and electric motor with drum. This shaft carries the drum in left direction during warping. An electronic encoder is fitted at the one end of this threaded shaft which counts the rotation of shaft from the starting of section till the end of the section. When section is completed, the machine moves in left direction by pressing reset push button. The machine travels the distance equal to distance travelled in right direction plus distance equal to section width. 

WAXING DEVICE: 

 It is an optional device but very useful to improve the quality of warp yarn during process. It is located between the warping drum and beaming system. In this device three rollers are used. A steel trey is used to fill the chemical to be applied on the yarn. The middle roller is mounted over the trey.


Nearly half portion of middle roller immerses in the trey. Other two rollers guide the warp yarn only. A chain sprocket is mounted at the one end of middle roller which receives the rotational motion through electric motor. The speed of middle roller is controlled by an A.C. drive. When any liquid chemical is applied to the warp, the liquid is filled in the chemical trey. The middle roller rotating in opposite direction of yarn touches with the surface of warp. The surface of roller lifts the liquid and applies it on the yarn surface. The amount of chemical to be applied is regulated by adjusting the speed of middle roller.

BEAMING SYSTEM:

when the warping is completed, there is needed to transfer the warp on the weaver’s beam. This transfer of warp from drum to weaver’s beam is called beaming process. Beaming system mainly consists of beam loading arrangement and beam traversing arrangement and beam drive mechanism. The empty beam is mounted on the beaming system by means of loading system. An iron frame in each side of the machine slides over the slide rail. These frames are moved left and right direction with the help of square threaded shaft fitted across the width of the machine. When this shaft rotates in the threaded brackets attached with the iron frames, it carries the iron frames left and right direction. The left side frame can be moved also by hand wheel which moves on the toothed rack with the help of gear. The adopters mounted on the each side of beam are entered in the hollow shafts. These shaft can be lifted or lowered according to requirement by hydraulic pressure. The hollow shaft of left rotates freely but right side shaft has the positive drive. This shaft rotates the beam during beaming. This shaft receives the rotational motion through an electric motor and a reduction gear box. This shaft is connected to gear box through a universal joint which maintain the alignment automatically during lifting and lowering the beam.

FULL WARP LENGTH STOP MOTION:

 It is fully electronically controlled system. A shaft encoder is mounted on the shaft of warping drum which counted the rotations of warping drum. A control panel converts the rotations of drum into length in metres automatically. When warp length reaches to completion, the machine stops automatically before few metres of warp length. Now machine comes in slow speed mode and completes the wrapping of remaining warp length and becomes stationary. This system is more useful during chances of brake failure.

MULTI LEASE STOP MOTION: 

 This is digitally controlled motion. This motion helps to insert more than one lease (multi leases) in one warp beam. Suppose we have to make three small warp beams say 600 metres. Length of each beam. During warping, we make a beam of 1800 metres. We inserts leases at the beginning and after each 600 metres of warp length. When we starts machine after insertion of initial lease, the machine stops automatically after wrapping 600 metres of warp. Now second lease is inserted and machine is started again. Now machine again stops after 600 metres of wrapping of warp. Operator inserts third and final lease in the warp and starts the machine again. During beaming, these three warp beams are separated. Thus every beam has an individual lease in it and time saving occurs in process.

HYDRAULIC PRESSURE SYSTEM:

A hydraulic pressure device is used to generate pressure to bring up and down the beam, pressure also imparts tension to the warp during beaming. Hydraulic pressure controls the compactness of beam. Hydraulic pressure breaks the momentum of rotating drum in case of machine stoppages. Generally a cuboid shape oil tank is used which is located at one side of machine. 68 no. hydraulic oil is filled in this tank. A geared oil pump is mounted on this oil tank. The inlet of oil pump rests in the oil. The oil enter into the oil pump through oil filter which does filter the oil. Pump’s shaft is connected to the electric motor.


This motor rotates the oil pump. Outlet of oil pump is connected to the pressure distribution arrangement. This distribution arrangement has magnetic valves, pressure regulators and oil pipes. The magnetic valves help to make oil supply on and off in various points according to requirement. The pressure is varied by using a regulator during beaming. A pressure meter is used to read actual value of pressure.  Push buttons are used to lift or lower the beam.this is an integrated A.C. inverter drive. This drives operates three electric motors (warping motor, beaming motor and machine traversing motor). The speed of warping and beaming is controlled by this drive. During warping process, the required warping speed is entered in the monitor. During beaming process, required speed is increased or decreased by using a pot in the machine.

SIGNAL LEMP:

the signal lamp is located at left side of machine. There are three types of lights used in this lamp. Green lamp means warping or beaming under process.


Red light enables that machine is stopped for warp breakage or manual stop. The white lamp enables that section length has been completed.

MONITOR: 

 This is located at the right of the machine. It has a display and key board. All the warp parameters, machine parameters are fed in this monitor. This sends the digital signals to the control panel.


If any type of error occurs during operation, which appears in this display. It provide all the operational information to the operator.

PROGRAMME LOGIC CONTROL PANEL: 

 It is also called the brain of machine. It is very important part of machine. All the automatic functions are performed by this device. It is fully electronic device. It receives all the inputs from various electronic sensors, limit switches, shaft encoders, inverter drives and hydraulic pressure control unit and send the digital signals to the various control units of machine.  The machine gets on and off according to command received from PLC device.

PRECAUTIONS DURING SECTIONAL WARPING MACHINE:

Following precautions must be taken during sectional warping process:

The tension on the each warp end should be equal and sufficient.

The creel should be cleaned by compressed air after ever creel change.

The package size should be equal. The size difference in packages creates uneven tension on the ends.

The distance between package and yarn guide should be proper and sufficient to prevent the balloon formation during unwinding of yarn from package.

The effective working of electrical stop motion should always be ensured.

The distance between stop motion and lease reed should sufficient. If it is too low, it may cause unnecessary end breakages. If this distance is too high, it may cause excessive short end in the warp and entanglement of ends which results in form of end breakages.

The distance between lease reed and flat reed or v – shape reed should be correct to minimise the end breakages at the reed.

Gears selection should be as accurate as possible. Incorrect gears selection results in the improper cone height of warp beam thus diameter of beam at one side reduces or increases. This variation in diameter results in form of bowing in fabric.

The warping speed should not be changed during process, speed change during process may change the length of section or tension of warp.

All the sections should have equal number of ends if possible.

Section width should be set correctly. If section width is less than required, there will be gap between adjacent sections and warp will become loose at these places. If it is more than required, the ends will overlapped and it will create end breakage during beaming.

There should not go any short end in the beam during warp. Short end crates lappers and end breakage during beaming.

Every short end should be repaired by reversing the machine in back direction.

Efficient working should be ensured before operating the machine.

The oil level in the hydraulic system maintained properly.

The discs and brake shoe of braking system should be cleaned by CTC or other solvent.

Wax, cold binder or antistatic oil should be used if required.

Beaming tension should be selected properly. The beam should be neither much compact nor much loose.

Excess beaming tension may create deformation in the yarn.

The flange to flange distance in the beam should be set correctly.

The beam width should be two centimetre more than reed space used in the loom.

The warp should be wound on the beam in the centre of barrel.

The flanges should be tighten properly.

The lease should be insert correctly to prevent the end crossing problem.

The number of ends per dent in the flat or v – shape reed should be as minimum as possible. Excess number of ends per dent in this reed results in the form of rolling. This rolling creates ends crossing problem during unwinding of warp on the loom.

Proper working of machine should be ensured by empty running of machine.

The electrodes of warp stop motion should be cleaned periodically.

The roughness of surface of cone shaped portion of warping drum should be maintained properly. If it becomes smooth, the slippage of sections on this side may occur. 

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