The important developments can be conveniently studied under the following heads:
Improvements in the cylinder construction.
Cylinder in high production cards must be capable of withstanding the stress and strain at speeds like 600 rpm.
The present day cards are either made of thick sheet metal sufficiently reinforced and annealed at low tension or by special cast iron stabilised, rectified and reinforced.
All the cylinders are provided with ball bearings and dynamically balanced so that accurate settings can be achieved.
In the cros Rolvarga MK 4 card, dia. of cylinder is 20 % smaller than the conventional cards to add stability and strength to cylinder and permit the cylinder rotates upto three times faster than the conventionally constructed cards. This also improves dust ejection and carding effectiveness for high quality sliver.
Developments in cylinder-flat zone:
The two major developments aimed at this zone are
1) To increase the effectiveness of flats
2) To reduce the flat waste
The important innovation is running the flats in the opposite direction to the cylinder as developed by SACM, FRANCE.
The following advantages are claimed due to change of direction of flats.
Thoroughly stripped, clean flats start their action at the delivery and of the cylinder. In this way the fibres are submitted to progressively cleaner flats, the final carding being performed by flats that have just been stripped. This results is more efficient carding than with flats loaded with wastes.
On the other hand the choke of the fibres against the flats encountered is dumped by the waste already collected by those flats. The large impurities contained in the web are retained by the first flats at the moment where they complete their carding cycle and just before being stripped. These impurities are therefore immediately removed and will not cling to the flats during the whole carding cycle with a risk of being taken up again by the cylinder.
Card Master:
M/s John Hollingsworth on wheels of Greenville has developed stationary carding plates in place of revolving flats under the trade name of CARD Master.
This consists of four strong, stationary aluminium plates with special metallic clothing applied to the inside surface. These plates, contoured to the shape of the cylinder, provide greater carding surface than revolving flats. The advantages claimed are
i) The weight of the card is reduced maintenance due to lock of moving parts.
ii) There is a power saving of 4%
iii) No flat waste
iv) provides maximum carding area.
v) Improves carding quality
vi) Long life since they can be re-ground.
4. Development in cylinder front zone:
i) viking 400:
It is the post carding segment to improve the parallalisation
of fibres. This is mounted on the doffer side of cylinder. It
consists of 4 teeth segments with a total width of 128 mm and a
teeth density of 150 points/sq inch. It produces remarkable
improvement in yarn quality.
ii). Trash master:
This is a system for the removal of vegetable matter, pepper trash, short fly, sticky particles, micro dust and : fused man made fibres. A special knife is set to the cylinder wire according the fibres to be processed. This knife, together with the centrifugal force and controlled air-currents, eliminate the trash. The extracted particles are collected in the low pressure chamber and removed the continuous suction cleaning.
It requires 165m3 air or 2 millibar low pressure, can be connected to all suction cleaning systems of high production cards.
