Wednesday, July 3, 2019

SECTIONAL WARPING PROCESS l STRUCTURE AND WORKING PRINCIPLE OF SECTIONAL WARPING MACHINE

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 the warping of multiplies 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 the 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 a very important part of the warping machine. Creel is a frame of round or square section pipes and iron channels. The cone holders are arranged in vertical columns on both sides of the creel 50 columns of cone holders on both sides of the creel are there in the creel of the sectional warping machine. The creel of sectional warping contains 8 rows on each side. The number of columns varies according to the requirement of creel capacity.  In this creel, yarn packages are mounted on the cone holders from outside of the creel. After loading the yarn packages on the creel, the stands of creel are revolved at 180 degrees. A 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 handwheel or electric motor. The yarn coming from the package first of all passes through the ceramic yarn guide then it passes through the yarn tensioner.


The main function of the tensioner is to impart a sufficient amount of tension to the yarn. Normally inverted cup and deadweight washers 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 tensioners 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 an end to end entanglement during warping. The second objective of these guides is to provide enough support to each end. The yarn sagging problem creates due to insufficient support to the yarn during warping because a long length of yarn tries to sag due to its own weight. Thus enough support needs throughout the passage of the 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 are provided in the creel whenever ends breakage occurs the indication lamp puts on immediately and the machine is stopped. These indication lamps help the operator to identify the correct situation broken end in the creel.

SEPARATING RODS:

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



A separator rod helps to prevent the warp ends to be entangled to each other and makes the smooth movement of ends during operation. It plays a very important role in the 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 into two layers when it is lowered or lifted. A pneumatic cylinder is used to lift or lower it. In some machines toothed racks, 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 maintains equal space among 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 the table. Reed can also be turned at a certain angle for adjusting section width whenever flat reed is being used. When the v-shape reed is used, the adjusting table has the mechanism to reduce or increase the width of the 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 grooves 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 varies from 2.5 to 3.0 metres according to the make of the machine. The length of the drum varies according to the maximum beam width required to be warped. The one side of the drum is designed in a conical shape. The cone length varies from 1100 – 1200 mm.

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

HYDRAULIC DISC OR DRUM BRAKES: 

The main function of the brake in the warping machine is to break the momentum of the drum rotating at high speed in case of machine stoppages. Two types of brakes are used in the machine. In the drum brake system, the brake drum is mounted on the shaft of the warping drum. It rotates with a warping drum. A brake belt rests on the brake drum. One end of the belt is fixed and another end is connected to the hydraulically operated arm. When the 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 the beaming process. in the disc brake system, two brake discs are mounted on the drum shaft at each side of the drum. Brake shoes are also fitted on each disc. These shoes are operated hydraulically.


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



DRUM TRAVERSING MOTION: 

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

WAXING DEVICE: 

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


Nearly half portion of the middle roller immerses in the trey. The other two rollers guide the warp yarn only. A chain sprocket is mounted at the one end of a middle roller which receives the rotational motion through the electric motor. The speed of the 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 tray. The middle roller rotating in the opposite direction of yarn touches the surface of the warp. The surface of the roller lifts the liquid and applies it to the yarn surface. The amount of chemical to be applied is regulated by adjusting the speed of the 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 the beaming process. The 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 a loading system. An iron frame on each side of the machine slides over the slide rail. These frames are moved left and right direction with the help of a 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 a hand wheel which moves on the toothed rack with the help of gear. The adapters mounted on each side of the beam are entered in the hollow shafts. These shafts can be lifted or lowered according to requirement by hydraulic pressure. The hollow shaft of the left rotates freely but the right side shaft has a positive drive. This shaft rotates the beam during beaming. This shaft receives the rotational motion through an electric motor and a reduction gearbox. This shaft is connected to the gearbox through a universal joint which maintains the alignment automatically during lifting and lowering the beam.

FULL WARP LENGTH STOP MOTION:

 It is a fully electronically controlled system. A shaft encoder is mounted on the shaft of the warping drum which counted the rotations of the warping drum. A control panel converts the rotations of the drum into length in metres automatically. When warp length reaches completion, the machine stops automatically before few metres of warp length. Now machine comes in slow-speed mode and completes the wrapping of the 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 insert leases at the beginning and after every 600 metres of warp length. When we start the machine after insertion of the initial lease, the machine stops automatically after wrapping 600 metres of warp. Now the second lease is inserted and the machine is started again. Now machine again stops after 600 metres of wrapping of warp. The operator inserts the 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 the 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 the beam. Hydraulic pressure breaks the momentum of the rotating drum in case of machine stoppages. Generally, a cuboid shape oil tank is used which is located at one side of the machine. 68 no. hydraulic oil is filled in this tank. A geared oil pump is mounted on this oil tank. The inlet of the oil pump rests in the oil. The oil enters the oil pump through an oil filter which does filter the oil. The pump’s shaft is connected to the electric motor.


This motor rotates the oil pump. The outlet of the 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 the 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 the warping process, the required warping speed is entered into the monitor. During the beaming process, the required speed is increased or decreased by using a pot in the machine.

SIGNAL LEMP:

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


Red light enables that machine to be 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 keyboard. 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 provides all the operational information to the operator.

PROGRAMME LOGIC CONTROL PANEL: 

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

PRECAUTIONS DURING SECTIONAL WARPING MACHINE:

Following precautions must be taken during the sectional warping process:

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

The creel should be cleaned by compressed air after every 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 balloon formation during unwinding of yarn from a 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 the warp beam thus the diameter of the 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 the process, speed change during the process may change the length of section or tension of the warp.

All the sections should have an 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 be 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 the back direction.

Efficient working should be ensured before operating the machine.

The oil level in the hydraulic system is maintained properly.

The discs and brake shoe of the braking system should be cleaned by CTC or another 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 centimetres more than the reed space used in the loom.

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

The flanges should be tightened properly.

The lease should be inserted 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. The excess number of ends per dent in this reed results in the form of rolling. This rolling creates an end crossing problem during the unwinding of the warp on the loom.

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

The electrodes of warp stop motion should be cleaned periodically.

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

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