04-01-2013, 11:13 AM
DEVELOPMENTS IN DRAFTING SYSTEM
DEVELOPMENTS IN DRAFTING.pptx (Size: 3.36 MB / Downloads: 57)
Introduction
Since drafting at Ring Frame & other preparatory stages has a major influence on yarn qualities & ultimately tells on even fabric appearance
Therefore conversion of drafting is given a high priority in the efforts to upgrade a Ring Frame & other preparatory stages & the payback from such investments is attractive.
IRREGULARITY IN DRAFTING
Irregularity added in drafting is mainly caused by:
Inadequate control over the movement of short and floating fibres.
2. Slippage of strand and fibres under the drafting roller.
3. Variations in speed of drafting rollers.
4. Mechanical faults.
Developments in drafting have therefore focused mainly on reducing the contribution from these factors.
ENHANCED YARN CLEANLINESS
Novel suction system with periodically lifting cleaning lips on the top rollers.
Cleanliness at the sliver infeed.
Uniform cleaning efficiency due to automatic filter cleaning.
Neat coiling of manmade fiber slivers and their blends using the CLEANcoil coiler.
CLEANtube sliver coiling for processing cotton without accumulations of trash and short fibers.
Modern drafting system technology
Quality and economy through precise fiber guidance.
4-over-3 drafting system
The bottom rollers with high-precision fluting and a pressure bar with a special profile in the main drafting zone ensure accurate fiber guidance.
The fourth top roller gently diverts the fibers and also ensures perfect running properties.
A redesigned web guide nozzle brings the web together especially gently after it leaves the drafting system and thus prevents unwelcome fiber entanglement.
Variable loading with large top rollers.
Loading of the top rollers is variably adjustable by spring elements
or pneumatically (option). Automatic load relief on the
top rollers prevents deformation of the covers during machine
stoppages, which assures the quality of the sliver produced.
The large diameter of the top rollers compared to competing
products guarantees superior running properties with low roller
temperature and long service life.
VERY EASY OPERATION OF THE DRAFTING SYSTEM
Central setting of roller gaps permits rapid blend changes. Break draft and main draft distances can be set independently of each other for the first time. The roller gaps can be read off a scale, which makes setting gauges unnecessary. The belts can remain tensioned during setting. All mechanical settings can be performed with a single key.
The top rollers are swivel-mounted on the loading arm. This permits optimum accessibility. The sliver is threaded-in with the help of compressed air. The mounting bracket of the web guide nozzle is pivoted, which makes access to the calandering unit considerably easier. All technology components are
designed so that they can only be used in the correct position. This prevents damage due to incorrect operation.
OFFSET DRAFTING
The back bottom roller is raised by height of 13.5mm and back top roller is offset backward by 24mm so that the nip point is taken back by 15mm around the circumference of bottom roller . The incoming roving therefore wraps round the circumference of bottom roller over a considerable length before it leaves it.
Further, back zone bottom roller setting is reduced from 51 to 44mm. As a result of these actions the strand takes a V-shaped path as twist in roving is broken down. The strand width is reduced leading to improved inter fiber friction in the main drafting zone.
Detailed studies show that thick and thin places and U% of yarn are significantly reduced in cotton counts with offset drafting.