computer application in textiles-2 vignesh(pavitra)

Computer Applications in Textiles Unit-II

COMPUTER INTEGRATED MANUFACTURING (CIM)CIM is a manufacturing process in which all the functional elements and process

steps are integrated with the help of computer, so that the process operates in the most effective and efficient way.Monitoring systems

1. On-line 2. Off- line

On-line monitoring systemOn- line monitoring system is the one which is installed on-board the machine or

equipments for monitoring and controlling operation.Off-line monitoring system

Off-line monitoring system is off the machine and performs the task related to the machine independently.Advantages of on-line monitoring system

1. Constant and continuous monitoring ensures consistent process performance and product quality.

2. Quick detection of any malfunction of the machine.3. Reduction in personnel intervention 4. Increased efficiency and productivity.

On-line monitoring systems use PLC controls. PLC ( Programmable Logic Controller) have been gaining popularity on the factory floor and will probably remain predominant for some time to come. Most of this is because of the advantages they offer.

Cost effective for controlling complex systems. Flexible and can be reapplied to control other systems quickly and easily Computational abilities allow more sophisticated control. Trouble shooting aids make programming easier and reduce downtime. Reliable components make these likely to operate for years before failure.

Scope of application of computer in fibre productionMicrocomputers are used tot set, monitor and control the key parameters like

Temperature, pressure and time of polymerization Viscosity of molten polymer Extrusion rate Draw ratio Fibre fineness Finish add-on

42


PRACTICE

1. Objective Type questions 1. This is a manufacturing process in which all the functional elements and process

steps are integrated with the help of computer. (a) CAD (b) CAM (c) CIM

2. This system is the one which is installed on-board the machine or equipments for monitoring and controlling operation.

(a) On-line (b) Off-line (c) In-line

2. 2 marks questions

1. What is off-line monitoring systems?2. What are the advantages of on-line monitoring systems?3. What are the key parameters observed in man-made fibre production?4. What are the advantages of PLC?

3. Descriptive type questions

1. Write short notes on On-line and Off-line monitoring systems.

43


FLOW CONTROL IN BLOWROOMBlowroom is one area where the flow control is important one. Since different

machines are joined in a sequence to process the material. In blowroom, the material flow control can be classified into two different areas namely,

1. Material flow control within a machine2. Material flow control between machines

Flow Control within a machineMaterial flow within a machine should be controlled in order to maintain flock

size and to avoid over filling of trunks and hoppers, when a hopper is full, the feed to it should be stopped and again restarted when it reaches a predetermined lower level.

This can be carried out by any one of the following methods:1. Swing door mechanism with fast and loose pulleys2. Swing door mechanism with limit switch control3. Photo electric method

In Previous generation machines to reduce the number of motors used for driving individual components, only one motor was used. The feed lattice was driven by loose and fast pulleys with the weft fork being controlled by swing door mechanism.

When the required material level is reached the swing door through levers and fork, shifts the belt to the loose pulley, thus stopping the feed lattice. When the material is required the fast pulley is engaged and the feed is restarted. A disadvantage with this method is that efficient control becomes impossible when the production rate is increased. To overcome this, the system was changed to the individual motor drive. The switching on and off of the motor is carried out by the door through a limit switch.

In the latest generation machines to avoid surface contact of the material and mechanical setting errors and to achieve better control, photocells are used in place of swing door. In some machines an electro magnetic clutch in tandem with photo cell controls all the feeding elements with a single motor.

Flow Control between machinesFlow control between the upstream and down stream machines in blowroom is

controlled by1. Swing door with limit switch2. Photo electric method3. Differential Pressure switch

Whenever the material is full in the hopper, the swing door is activated and the motor is switched off in the upstream machine by the actuation of a limit switch connected to the swing door. This type of control is provided in the hopper feeder of old machines.

Of late these swing doors have replaced by using photo electric cells. In this if there is no material the light emitted by the emitter is received by the receiver, thereby producing some voltage. This is amplified and is used to control the feed motor of the upstream machine. This type is used in ERM and hopper feeder.

44


With the latest generation machines which are mainly used for blending operation a separate system of flow control is used to achieve better blending effect. It consists of a differential pressure switch. Using this inside chamber pressure is measured, compared with atmospheric pressure and if it exceeds a particular level, the feed is stopped.

Working of differential pressure switchThe differential pressure switch has a diaphragm sealed completely. One side of

the diaphragm is connected to the atmospheric pressure and other to chamber pressure. When there is no material, both the pressures are equal. When the material builds up inside the chamber, the chamber pressure increases, there by pushing the diaphragm to one side. The diaphragm is suitably connected to a micro switch by with a spring which actuates the relay of the feed motor of the upstream machine. When the micro switch is released the feed motor is restarted. This type of control is used in Aeromix and unimix machines.

Mixing Bale Opener Unimix AerofeedWithin the machine Between machine

Photo cell controls the feed apron drive by

operating electro magnetic clutch

Differential pressure switch senses the pressure increase inside the storage chamber with atmospheric pressure.

The flock feeder roller motor is controlled by the flock meter which operates in the photoelectric principle.

ERM Hopper FeederBetween machine Within the machine Between machine

Two reflective type photocells kept one above the other over the laminae duct. The top photocell is responsible for stopping the delivery motor at the upstream machine and bottom one is responsible for starting delivery motor.

Swing door in the intermediate chamber operates the star roller motor to give the delivery of the material when required for down stream machine and vice versa.

Photocell in the hopper operates the delivery motor of the upstream machine.

Automatic bale openersThe traditional automatic bale openers work with limited lots. Interruption in

blending and production can never be completed avoided. In BLENDOMAT BDT 020, the bales had to be fed continuously. Depending on the space available and on the mill requirements, different methods of operations are possible. The new bales may be fed manually with a fork-lift truck. However, fully automatic bale feed including the removal of the packaging and the bands and if necessary bale cleaning is possible, which can be done in one bale preparation station. It is further more conceivable to connect this station to a bale store. Another possibility of bale feed is provided by a loading terminal and Bale carriage as a link between the bale supply using a fork-lift truck and the BLENDOMAT BDT 020.

45


Continuous operation with only one new bale laydown a day.

The BLENDOMAT BDT 020 is designed for continuous bale feeding. To be able however to feed the bale reserve conveyor belt intermittently, for example once per day, the Bale Carriage L W is used. At the end of the conveyor belt, at the so called loading terminal, the Bale Carriage L W takes an opened bale from a fork-lift truck and transports it to the end of the bale laydown area. It is of no importance at which point on the reserve conveyor belt the bale. Due to this reloading principle, the bale reserve can be refilled within a fairly short period of time and the BLENDOMAT BDT 020 will then operate until the next reloading without any attention. .

After having transferred the bale from the fork-lift truck to the Bale Carriage L W at the loading terminal, the track-guided carriage moves to the end of the line of bales. The forks penetrate between the last bale and the bale which is to be positioned, and travel on tracks. Here they swing downwards. By the simultaneous forward movement of the forks and backward movement of the bale carriage itself, the bale is pushed against the existing lay down. As the bale is positioned on a slight slope, it can not fall over.

A further improvement on well-known technology

The BLENDOMAT BDT 020 works with a bale lay down that is continuously moved forward. New bales are fed automatically on a conveyor belt. The detacher head runs diagonally. While the remnants of the first bale are still being worked off, the first tufts from the last bale are already being included in the blend.

Depending on the machine length, the range of operation, the so called diagonal, can be between 10 and 25 meters. Following the operation zone, there is a conveyor belt on which already opened bales can be arranged. At the same time, this conveyor belt allows the bales to become conditioned to the room climate. In the case the preparation of the complete bale lay down doe 24 hour period has to be made during the day shift, the bale reserve conveyor belt has to be of an appropriate length. If necessary, due to space availability, the additional bale reserve can be located on the opposite side of the BLE~TIOMAT BDT 020. In this case, a bale transporter station transfers the opened bales from the reserve conveyor belt to the operating side of the machine

Microcomputer System

All BLENDOMAT BDT models are controlled and monitored by MicrocomputerControls BLENDCOMMANDER BC. This system visualizes the production processes. The current status of the machine, together with additional information, such as the remaining run times of each bale group, can be seen at glance. In case of malfunctions, the sensor reporting the malfunction is marked with a red arrow on a three-dimensional screen plan. The operator can start to remedy the cause of the malfunction immediately after looking at the monitor. To support the electrician, the monitor displays supplementary information which often saves referring to the documentation.

46


CLEANING LINESOne of the most important rules for a cleaning line is the principle of gradual

opening. The theoretical tuft weight has to be reduced from machine to machine. This ensures a gentile treatment of the cotton fibres and the same time optimum cleaning performance. On the other hand, this means that machines with the same kind of opening devices "and the same rotational speeds should not be combined. An extraction offering particles with special machinery designed for this purpose is more reliable and the targeted blending with automatic bale openers is in any case better than the traditional stack mixing. To produce a homogeneous blend, the amount of fibres stripped off the individual bales has becomes obvious when, for example, dealing with the problem of uniform tuft size.The detached head of the Automatic Bale Opener BLENDOMAT BDT 019 is fitted with two opening rolls rotating in opposite directions are shown in the figure.

1. Light Barriers 2. Swiveling Detacher 3. Opening rolls4. Grid 5. Supporting rolls 6. Flexible Tube7. Turret 8. Truck 9. Belt winding unit10. Cover Belt 11. Suction Duct

47


Depending on the direction of travel, the rolls would normally strip off tufts of different size, and the production would not be balanced between two rolls. a special mechanism solves these problems. Depending on the direction of travel, one roll is always working in the opposite direction and one is the same direction. The roll stripping off the tufts in direction, of machine travel" penetrates the bale surface more deeply by the same distance. Only this inversion mechanism guarantees that production is distributed evenly amongst both opening rolls. This development provides an even more gentle fibre removal as well as an ideal, even degree of opening, and the smallest possible tuft size. These tufts are ideal for feeding the cleaners.

1. Heavy Part SeparatorNaturally, foreign parts and heavy parts are separated also at each cleaning place.

However, in order to foreign parts, a Heavy part Separator SEP AROMAT ASTA should be positioned at the beginning of each cleaning line. The Heavy Part Separator SEPAROMATASTA utilizes the different aero dynamical pattern of cotton tufts and heavy foreign parts for separation.

Heavy Part Separator

2. Metal SeparatorsDouble Magnet Trap MROMagnet traps positioned in ducts hold back ferrous metal particles which are not

bound into the material tufts. Most common are the so-called “magnetic traps” in the duct. Magnetic metal parts stick to the strong permanent magnet. The effectiveness of this metal separation depends on the cleaning frequency of these permanent magnets. If they do not. Get cleaned periodically, the danger exists that cotton tufts pile up at the metal parts, and thus pull the metal part back into the material flow. However, the magnet traps do not extract non-magnetic metals.

With the electronic metal separator these non-magnetic parts like bottle caps are safety extracted. An electronic sensor at the duct recognizes the metal part and prompts a change box in the duct, a couple of meters down the line. The metal part and the surrounding tufts drop into a collecting box. Here problems can be caused by very heavy parts, since these do not move at sir speed, respectively tuft-speed in the ducts. In this case it is almost impossible to find the correct timing to switch the change box.

48


Electronic Metal Separator

The suction station SECUROMAT SC is also designed to extract metal parts. The SECUROMAT SC can be used directly after an automatic bale opener BLENDOMAT BDT. The built-in condenser extracts material from the BLENDOMAT. Underneath the condenser of the SECUROMAT SC, a flat sensor is installed to recognize metals. This flat sensor can locate the metal parts very precisely and head accurately for the following flaps. When using the SECUROMAT SC, less good fibres are extracted than with the electronic metal separator.

Naturally, the heavy part separator and the SECUROMAT SC can also be combined. The place to integrate separators for heavy parts and metals into the cleaning line dependent the existing space requirements and the machinery combinations. The planning is definitely handled on an individual basis by specialists.

Another safety factor of a blow room is fire prevention, consisting of three different components in Trutzschler installations

1. Fire warning via heat sensors and spark detectors.2. Safeguards of property via fire protection flaps and extraction of burning material3. Extinguishing via powder or technical gaps.

These three features can be combined, for example, a mixer can be equipped with heat sensors. Usually one sensor is necessary for each chamber. When detecting a fire, an extinguishing device is activated which floods the whole mixer with extinguishing gas.

A similar operational sequence is possible with the BLENDOMAT BDT. Here the monitoring is carried out via a spark detector located in the detacher head. The registered fire triggers an extinguishing device, resulting in flooding of the bale surface and ducts with gas upto the fire protection flap.

To avoid the spreading of fire from one machine to another, spark detectors can be installed in the ducts. The reaction to a fire can take place in two ways

1. The duct is shut via a fire protection flap and the machine is turned off. This is

49


economical solution. It has the disadvantage that the burning material remains inside the duct and requires manual removal.

2. The material flow is diverted into a fire-proof container. In this container the material can burn out or be extinguished without any danger. Such a device can be installed in every horizontal duct.

PRACTICE1. Objective type questions

1. The most important rules for a cleaning line is the principle of (a) Opening angle (b) Gradual opening (c) Wide opening

2. Double Magnet Trap MRO is one of the (a) Heavy particle separator (b) Metal detector (c) Fire extinguisher

3. To avoid the spreading of fire from one machine to another, this can be installed in the ducts.

(a) Spark detectors (b) Fire extinguishers (c) Fire protection flaps

4. This transfers the opened bales from the reserve conveyor belt to the operating side of the machine

(a) bale transporter station (b) bale carriage (c) Detacher head

5. In mixing bale opener, this controls the feed apron drive by operating electro magnetic clutch.

(a) Differential pressure switch

(b) Photocell

(c) LVDT

6. An electronic sensor at the duct recognizes the metal part and prompts a change box in the duct, a couple of meters down the line in

(a) SECUROMAT SC (b) Electronic Metal Separator (c) Fire Protection System


50


1. What is differential Pressure switch?2. What are the components of Fire Protection System?3. What is the role of metal separators?4. Write about the flow control in hopper feeder.5. Write about the between machines flow control in ERM.


1. Write about the flow control in Blowroom

2. Write about the cleaning lines in Blowroom.

NEP CONTROL IN CARDS.Online monitoring in cards is carried out by means of a nep sensor and a camera.

There are inbuilt devices to display the nep count of a card web. Integrated Grinding system (IGS) has been developed. IGS is incorporated in the carding machine which automatically grinds the cylinder to maintain sharpness of wire points over its entire life span. All the grinding is happening without intervention of carding actions and also

51


without operator intervention. Inbuilt software determines the need for grinding and actuates the grinding process. These are used in Rieter C50, C60 cards.

NEP SENSORNep sensor’s sense every single meter of card sliver whereby eliminating the

laboratory testing of neps. This works under the optical principle. A digital camera is fit under the take-off roll which is working 20 times/second. The camera moves to and fro so that entire working width of a card web can be monitored. The optical method follows the visual perception of a person and this can be superior to off-line testing of nep counting. The high performance computer which is directly attached to the profile evaluates the pictures with special analysis software. This identifies the neps, trash particles and seed coat neps. Nep sensor can be used to identify the clothing damage. It can be used in temporary or permanent manner for the group of cards or individual cards.Nep sensor is quick and easy to install and to remove. This is used in NEPCONTROL TC-NCT, a Trutzschler make.

Control of NepsA major cause of neps is the presence of thin walled immature fibres in cotton.

While blending, it would be advisable to make sure that the mixing has a maturity coefficient greater than 0.80. Immature fibres are frequently associated with seedcoat fragments either from the chalazal end of the seed or due to the break up of immature ovules and insect attached seeds. Bits of broken seeds with fibres tend ti create nucleus for nep formation. It is important to get the best cleaning efficiency in the blowrrom and cards to control the incidence of seed coat and fibre neps in yarn. Extremely fine and immature cottons with high trash content are more prone to neppiness than coarser ones. Fibres having a micronaire value > 3.5 and maturity coefficient of about 0.8 are likely to reduce nep formation. The addition of excessive soft waste in mixing will produce yarns that are more neps. Improper mixing of long and short cottons, strong and weak cottons and cottons with widely differing levels of trash produce neps.

In blowroom, neps can be minimized by Eliminating the use of rough and blunt beater edge blades and blunt pins on

beaters. Polishing the grid bars as damaged and rusty grid bars causes neps Beaters must be set with correct clearance to prevent damage to fibres and

consequent formation of neps. Minimizing the use of same type of cleaning points Avoiding the repeated treatment of fibres that stick with the beaters Use of Aero Dynamic beaters in Modern drawframe lines will help to reduce nep

generation during opening.In Carding, neps can be minimized by

Good/ right selection of cylinder and licker-in results in achieving a satisfactory level of nep removal.

The adverse effects of damaged and worn wire points can be minimized by replacing the wire and washing the cylinder with petrol or acetone periodically with the aid of stripper roller.

52


Systematic cleaning of licker-in undercasing as well as inner surface of back and front plates reduce the formation of neps.

Higher licker-in speeds (750-1100rpm) remove more motes and fly waste, thus reducing seed coat neps.

In modern high production cards, the direction of rotation of flats is made opposite to the rotation of clylinder to reduce neps in cards.

The use of CP wires helps to reduce the increase in nep level in card web between two successive grinding.

PRACTICE 1. Objective type questions

1. The nep sensor works under (a) Optical principle (b) Strain gauge principle (c) Induction principle

2. It can be used in temporary or permanent manner for the group of cards or individual cards

(a) Displacement sensor

(b) Nep sensor

(c) Strain gauge sensor

3. A digital camera is fit under the take-off roll which is working

(a) 15 times/second

(b) 25 times/second

(c) 20 times/second

2. 2 marks questions 1. What is a nep sensor?

3. Descriptive type questions 1. Write short notes on Nep Control in Cards. 2. How neps can be minimized in bow room and card.

AUTO LEVELLER IN DRAWFRAMEAn extremely good count consistency is the most important condition for an

excellent appearance of the woven or knitted end product. In order to achieve this, it is a must to control the evenness and coefficient of variation of count both at sliver as well as

53


at yarn stage. Control of these cumulative factors can be taken only by AUTOLEVELLES

Autoleveller is used to reduce count variation in the sliver. This is mainly caused by the imperfect feeding at carding. This is also produced due to

1. Drafting waves in the drawing process2. Periodic variations due to the defective rotational parts in the machines3. Incorrect drafts4. Missing slivers in drawframe feed material and 5. Comber periodicities

There are 2 ways of variying the draft1. By varying the infeed speed and retaining the constant delivery speed.2. By varying the delivery speed and retaining the constant infeed speed.

In either case, correction may be applied in preliminary (or) main draft zone. Very short term variations upto 25cm; short term variations: from 25cm to 2.5m; medium term variations: from 2.5m to 25m; long term variations: from 25m to 250m; very long term variations: more than 250 m. Doubling can only reduce the coefficient of variation value of any occurring variation by root of the total number of doublings. It can not correct long term and periodic variations. Autolevellers can help to certain extent.

Classification of AutolevellersAutolevellers can be classified into three types depending upon the variations

1 Long term autolevellersOnly the mean count value is autolevelled. The actual evening out is undertaken in full by doubling

2. Medium term autolevellersBoth the mean value and also to a large extent the complete variance-length spectrum is autolevelled. As only short-term variation remains in the materials, the complete variation spectrum is quite considerably reduced. The autoleveller takes over the normal function of doubling in the medioum term range.

3. Short term autolevellersIn this case, besides the mean value, the complete variance length spectrum is to a large extent autolevelled and can in the ideal case also completely take over the function of doubling is applied together with doublings, then its advantage lies particularly in the correction of periodicities and other short disturbances.

Autolevellers can also be classified as 1. Open loop2. Closed loop

Open loop system Measuring

54


Correction

In this system sliver deviations are detected at the feed end itself and the corrections are made near the delivery end. The loop is open so that no monitoring is possible after the deviations have been corrected.

M- Measuring ZoneDV- Desired valueA- AmplifierTD -Time DelayS- Speed Adjusting unitTG - Tacho Generator

Advantages:This system has got shorter time lag between detection and correction and hence

can easily correct even much shorter variations. Since the detection is done at feed end itself it is possible to correct the fault exactly at the right location.

Disadvantage:There is no way of ensuring that the variation detected has indeed been corrected.

In the open loop system any change in sliver thickness is converted into a voltage level by using a transducer. This voltage level is compared with a reference signal from the desired value by means of a comparator.

The comparator compare 2 signals and give error signal which is the difference between the 2 inputs

The amplifier amplifies the error signal after the suitable time delay. The error signal varies the speed at the variable speed device. The Tachogenerator verifies whether the variable speed device accurately follows

the signals from the amplifier.

Closed loop systemThe sliver coming out at the delivery end is constantly monitored for any

variation from the standard value. Any deviation detected is fed to a correction system at the feed end which corrects the draft depending upon the variation detected. This corrected sliver is again monitored at the delivery and any variation detected is fed to the feed correction system thus ensuring closed loop system.

55

M

DV A TD S TG


Measuring

Correction

M- Measuring ZoneDV- Desired valueA- AmplifierTD -Time DelayS- Speed Adjusting unitTG - Tacho Generator

The measuring device is placed at the delivery point. The resulting signal from the transducer is first integrated by the integrator. This signals compared with desired value (DV). The amplifier varies the speed on the variable speed (S). TG is verifies the variable speed device and follows the signals from the

amplifier.

AdvantageThere would be continuous monitoring of sliver after the correction has been

made.

Disadvantage At very high speed, the time lag between detection and correction is too much to

correct short term variations. Due to this, these are normally employed to correct long term and medium term variations.

Autoleveller Drawframe RSB – I

56

TG S

M

DV

I

A


The RSB-851 drawframe works with the principle of open loop control. The thickness of the incoming sliver is sensed by a pair of tongue and groove rollers called as scanning rollers. The angular movement of the scanning roller is converted into voltages by means of displacement transducer. A plate is connected to the rollers and is moved into the Electromagnetic filed of the transducer. This movement of the plates cuts the flux and a voltage is induced which depends on the thickness of the material. This signal is transferred to the electronic memory, which then transmits it to the set point stage with a certain delay.

The correction delay is determined by the pulses which can be set by FIFO(First in First out). The distance between the measuring rollers and the front draft zone is divided into 177 to 192 pulses. FIFO is a register with the first measured variation stored in the first register and so on. FIFO can be changed depending upon the drafting setting and the position of the guides.

A- Grooved roller B-Scanning roller C-Middle rollerD-Delivery roller E-Signal converter F-Electronic memoryG- Pulse generator H-Set point stage I-Control unit

J-Variable speed motor K-Planetary gearL-Tacho generator M-Main motor

This system ensures the change in draft takes place exactly when the corresponding deviating length of the sliver passes the main draft zone. The set point stage uses the measuring voltage and the machine speed which are measured by two tacho generators to calculate the speed of the servo drive. At this stage a manual override is provided for any error in correction which can be exactly set right by either adding or subtracting voltage from the measured voltage. This efficiency of the autolevellers can be

57


studied by using the evenness tester mass variation diagram and by taking count CV% readings.

The middle roller is driven by a differential gear arrangement which has a constant drive from the front roller and variable speed from the servo motor. The servo drive which can rotate in both directions either to add or subtract the speed transmits this speed to the middle roller of the drafting system thus altering the draft. Speed of the variable speed motor is continuously measured and it does not correspond with the intended speed the machine is switched off. Accurate leveling is ensured by the high dynamic servo drive, so the correction times are of the order of few milliseconds and the correction lengths a few millimeters.

Trutzschler High-Performance Draw frame HS 900The auto leveling system of the High Performance Draw frame HS 900 is based

on the principle of adaptive control. According to the adaptive control principle the new Trutzschler control uses not only one measured value at a time but several consecutive values for the draft adjustment.

The measured values are quantified according to rules established by experience and are entered into the calculation with different priorities. This new form of control which in a figurative sense, recognizes not only “black” and “white” but for example also “grey” comes very close to the human way of thinkling and enacting. This application brings significantly better results, that is to say, more even slivers.

The automatic can changing with sliver separation between the cans takes place at reduced speed. It is not necessary to bring the drawframe to a stand still. During the complete changing process the Short-term Leveller and the automatic sliver count control remain in operation, also during speed reduction and run-up. This means the first and last metres of the drawframe sliver in the can are of regulated and tested quality. Even the pieced-up sliver is also evened out by shortest correction time.

Closed loop autoleveller:

58


In case of short term variations, a control circuit with dead time and P-controller with delay and a capacitive measuring unit are capable of doing the job in a perfect manner. In case of medium and long term variations, a closed control loop with dead time and PI controller can be used.

In this system count of the sliver at the output stage is measured. The autoleveller detects deviations from the pre-set nominal value. If deviations are determined, the actuator changes the input speed of the drafting rollers changing the draft in proportion to the control signal. The Tachogenerator at the input roller and the actuator controller ensure that the actuator corrects the count in proportion to the deviation. The degree of correction is automically and continuously checked. This is a closed loop system which controls the mean sliver count and guarantees the best possible accuracy.

The length of the sliver over which correction of count takes place as the correction length. This corresponds to approximately 6 times the distance between the measuring point and the autolevelling correction point. The time taken by the sliver to travel between these two points is called the “dead time”.


1. The sensor used in open loop autoleveller is

(a) Tongue and groove

(b) Induction type

(c) Proximity sensors

59


2. Both the mean value and also to a large extent the complete variance-length spectrum is autolevelled.

(a) Short term autolevellers

(b) Medium term autolevellers

(c) Long term autolevellers

3. This system ensures the change in draft takes place exactly when the corresponding deviating length of the sliver passes the main draft zone.

(a) open loop system (b) closed loop system (c) combined system

4. The auto leveling system of the High Performance Draw frame HS 900 is based on the principle of

(a) Programmable control (b) Adaptive control (c) Logic control

5. The correction delay is determined by the pulses which can be set by (a) LILO (b) FILO (c) FIFO

6. The time taken by the sliver to travel between these two points is called the (a) Time delay (b) Dead time (c) Time factor


1. What are the advantages and disadvantages of closed loop autolevellers? 2. What are the advantages and disadvantages of Open loop autolevellers? 3. What are long term and short term autolevellers? 4. How can the draft be varied?


1. Write short notes on Open-loop Autolevellers in Drawframe 2. Write about the closed –loop Auotolevellers3. Write about the autoleveller in Trutzschler High Performance Drawframe HS

900.

60


RING DATA SYSTEMSpinning is the process of converting roving into the yarn. It is a long rectangular

double sided frame in which the upper part is designed to hold the bobbins, middle part for drafting and lower part could give the necessary amount of twist and then winds yarn on the cops.

Automation is the replacement of human activity by mechanization and electronic control. This appears as substitution of capital for wage costs. Ring data system is the online monitoring system for ring spinning. There are two types of Ringdata

1. Production data collection2. Production and single data collection

Production Data CollectionThe sensor is fitted at the delivery of each machine that is from Blowroom to

Simplex machine. The production of each machine is fed into central unit and the production, efficiency of the machines in each and every shift, previous shift, week is found.Production and Single Data Collection

In addition to data collection, further extremely important extension configuration offers the spinning mill yarn break information. The Travelling sensors check every single spindle of every machine side.

Configuration of Ring Data SystemThis includes the following

1. Sensors2. Machine station3. Machine entry station4. Concentrator5. Central unit6. Terminals7. End break indication

1. Sensors:It is a device which converts the every rotational speed of the shaft into a

electrical signal called pulse. There is a metal flap or stirrup on the rotating shaft which observes every rotation by the sensing point and the signal is sent to the central unit memory.Types of sensors

1. Production sensor2. Doffing sensor3. Travelling sensor

Production sensor:This sensor determines the rotational speed of the front roller of spinning machine

right from Blowroom to Ringframe.

Doffing sensor:This sensor determines doffing position of the ring rail is registered for the

detection of the number and duration of doffing.

61


Travelling sensor:One Travelling sensor per machine side is provided along with the ring rail. It

detects the rotational movement of the ring traveler without contacting it and provides information concerning. It observes

End break at each spindle as well as average piecing time. The machine’s rotational speed of the ring traveler and those spindles with a

rotational speed which is too low2. Machine Station:

All machine stations are connected to central unit over a common line and are called up periodically.3. Concentrator:

It is used for intermediate storage of signals from 16 spinning machines.4. Central unit:

The computer controlled central unit is the heart of the data system with the following functions

Periodic call up of the concentrators Continuous processing and storage of the machine signals Control of dialogue with the user

5. Terminals: At the end of the shift, the printer automatically prints a number of freely

selectable reports.6. End break indication:

A front lamp is installed at either side of the ring frame at the headstock and the pneumafil end of the machine. As soon as the number of stopped spindles exceeds the selected value, the appropriate lamp lights up.

As described in the relevant Uster technical leaflet, the Uster Ringdata essentially consists of the following parts

Production sensor which determines the speed of the front roller of the drafting system and provides basic information regarding production, frequency and duration of longer stoppages.

Under wind sensor which registers the under wind position of the ring rail and detects the number and duration of doffing.

Travelling sensor- which monitors one side of the ring frame, detects the rotational movement of the ring traveller without contacting it provides information concerning end break/spindle, average piecing time, mean rotational speed of the ring traveler and spindles rotating at very low speed.

Machine station – which is controlled by microprocessor collects the machine and spinning position data, controls the movement of the travelling sensor and includes optical end-break indication to save operator time spent on finding spindles with an end-break. All machine stations are connected to a central unit over a common line for periodic call up of data.

Machine entry station- which monitors the important production data such as efficiencies, out – of production times, production capacities and facilitates reduction of machine stoppages.

62


The Concentrator- in which a microprocessor takes over the tasks of combining, preprocessing and intermediate storage of the signals from 16 machines.

The Ring data reports spinning position with high end-breaks and machines with low production, low efficiency are marked for remedial action which leads to increased production and improvements in quality.


1. In this system, the sensor is fitted at the delivery of each machine that is from blowroom to simplex machine. (a) Production and single data collection (b) Production and multiple data collection (c) Production data collection

2. This sensor determines the rotational speed of the front roller of spinning machine right from Blowroom to Ring frame.

(a) Doffing sensor

(b) Production sensor

(c) Traveling sensor

3. It is used for intermediate storage of signals from 16 spinning machines

(a) Concentrator

(b) Machine station

(c) Central unit

2. 2 marks questions 1. What is the use of End break Indicator? 2. What are the types of sensors used in Ring data system? 3. What do you mean by Production and single data collection? 4. Write the functions of Central Unit. 5. What is the configuration of Ring data system?


1. Write about the Ring Data system.

63

computer application in textiles-2 vignesh(pavitra)

Documents