POSITIVE YARN FEEDING & How it affects to the fabric quality
Post on 31-Dec-2015
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POSITIVE YARN FEEDINGPOSITIVE YARN FEEDING
&&
How it affects to the fabric qualityHow it affects to the fabric quality
GROUP MEMBERSGROUP MEMBERS
Narampanawa R. D. BNishshanka N. A. K. P. NPahathkumbura D. K. BRanasinghe D. D
YARN FEEDING SYSTEMSYARN FEEDING SYSTEMS
POSITIVE YARN FEEDINGNEGATIVE YARN FEEDING
The needle draws yarns directly from the package (Beam, Cone etc…)
An external element decides the yarn length released to the needle
DRAW BACKS OF NEGATIVE YARN FEEDINGDRAW BACKS OF NEGATIVE YARN FEEDING
Feed rate (amount of yarn) and Yarn tension will be vary from yarn to yarn
Decrease the fabric quality.
Yarn breakages
Reduction in production efficiency.
POSITIVE YARN FEEDINGPOSITIVE YARN FEEDING
Avoid drawbacks as non uniform Feed rates
and Yarn tension variations
How?
The positive feed units usually driven by
external force (motor, gear driven) rather than
by the needles, extract yarns from the
packages and deliver them to the needles.
POSITIVE YARN FEEDING SYSTEMPOSITIVE YARN FEEDING SYSTEM
Yarn storage feeder
Positive storage yarn delivery device
Tape feed mechanism
Each yarn from the package is passed in between
its own Feed Wheel and the Drive Tape
TAPE FEED SYSTEMTAPE FEED SYSTEM
This is commonly used in circular knitting machines.
By changing the Quality Adjusting Pulley diameter, yarn delivery speed can be alter.
Continued……..Continued……..
DrawbacksDrawbacks
Due to slippage of the yarn in between drive tape and the feed tape, yarn feed rate can be affected.
Deformed loops will be formed from this knitting system.
Quality Wheel can not be adjusted while machine been operated
Yarn faults cannot be detected before the knitting zone.
Yarn Storage FeederYarn Storage Feeder
This system is used when the structure differs
from knitting system to knitting system and from
course to course within the pattern (ex : multi
color jacquard)
DrawbacksDrawbacks
Does not feed the yarn to the needle as a fully positively feeding system. (only up to the temporary storage)
Positive storage yarn delivery devicePositive storage yarn delivery device
This is a combination of tape feeder and the yarn storage.
Positive storage yarn delivery device…Positive storage yarn delivery device…
Positive storage yarn delivery device…Positive storage yarn delivery device…
Detect yarn faults before entering to the knitting zone.
Increase the efficiencyReduce needle breakages
Fabric quality through positive yarn feedingFabric quality through positive yarn feeding
Provide the foundation for the plating technique.
Controls the fabric properties ( gsm, composition, performance such as stretch ability)
Faults of yarn are detected prior to knitting zone which reduce defects of the fabric.
Uniform stitches give better fabric appearance.
FunctionFunction
Winding reelThere different winding reelsClosed wheel – prevents filament buildingThread wheel - in case of irregular thread consumption
Anti-filamentation unitIn filament yarns capillary filaments can collect onthe winding reel. This is prevented by selecting the correct take off position.
Feed rate tape selector
Vibrating yarn tensionerprevents the build up of dirtbetween the tension rings and prevent false stoppage.A magnetic tension ring applies a uniform tensioning force .
FunctionFunctionFeed Rate Tape Selector – gives the correct amount of for each course.Ex : Half Milano
In here yarn is constantly fed in the positive feed Mode.
Friction Drive Mode - On machines with variable yarn consumption (e.g. drop stitch pattern or mini Jacquard machines), this should be run in the friction mode.
But this still can not be used for complex structures where the yarn consumption differs from knitting system to knitting system.
FunctionFunction
Developments of positive yarn feedersDevelopments of positive yarn feeders
i-DSCS, Digital Stitch Control System "with Intelligence
from Shima Seiki." i-DSCS has the capability to
actively control yarn-feed in both feed and retrieval
directions as necessary. This is crucial to the precision
knitting required in WHOLEGARMENT production.
Developments of positive yarn feedersDevelopments of positive yarn feeders In seamless knitting and new warp knitting machines
have storage feeders.New storage feeders (Rojtricot) has an additional
yarn twisting and has a switch for setting the rotational direction for S or Z twist yarns.
A braking system at the end of the package body ensures that the yarn tension is uniform.
Developments of positive yarn feedersDevelopments of positive yarn feeders
►This operates continuously, without starting and
stopping. The adjustable conical magnetic tensioner
at the yarn outlet detect the tension and drive
according to it maintain constant yarn tension.
► Microprocessor is used to calculate the average
yarn usage rate and adjust the motor speed to the
yarn usage accordingly.
True Positive FeedingTrue Positive Feeding
Modern Garment shaping and Technical fabric knitting machines with patterning requires different loop lengths for different needles for each course in the fabric.
TPFTPF
This system widely uses in medical textiles such as Scan-to-knit.
Above system fulfills that requirement
How?
pre-calculate the yarn requirement and deliver the changing yarn requirement in synchrony with the feeder movement
TPF Ctd…TPF Ctd…
Course-by-course needle selection program
detailing the action of each needle across
the needle beds
Accesses this data, pre-calculates the yarn
requirement in real time as the carriage
traverses the needles and supplies the
appropriate control signals to the drive
motors
Positive Feeding on Warp KnittingPositive Feeding on Warp Knitting
Yarn beams are rotated by means of mechanical and electronic systems to give exact runner lengths uniformly.
Warp KnittingWarp Knitting
Cone and Drum mechanism is used in
mechanical systems
Electronically geared motors are used in
modern systems with the feelers.
Problem areas of positive yarn feedersProblem areas of positive yarn feeders
Yarn breakages due to friction dust, that have filaments protruding from the
yarn, that carry a relatively large amount of sizing, or that in some other way leave behind or cause traces or deposits on parts of the yarn feeder will cause an irregular feeding of the yarn and will cause a null effect on the positive yarn feeding.
With the additional force given, yarn properties be affected
Problem areas of positive yarn feedersProblem areas of positive yarn feeders
The nip roller positive feeding will require a
complex yarn path – Influences the design
of the machine
Problem areas of positive yarn feedersProblem areas of positive yarn feeders
Large fluctuations caused by individual
needle selection cannot be adopted through
positive feeding ( large area jacquards)
Due to intensive individual attention towards each and every yarn been fed
Overcoming them Overcoming them
It is the object to create a yarn feeder whose
operation properties are largely independent
of the nature of the yarn.
This object is attained by a yarn feeder having
a yarn feed wheel with a special geometry
that facilitates the feeding and payout of yarn
onto and from the yarn feed wheel.
Yarn feeder with a ceramic coated wheelYarn feeder with a ceramic coated wheel
Yarn
Ceramic coated spikes
Minimizes the effect by the heat
Friction will be at a controlled level of affection
Will make a yarn feeder, independent from the
yarn path
Change from the initial nip roller to the Change from the initial nip roller to the tape positive feeding system tape positive feeding system
CheaperAdaptableSimpler
THANK YOU
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