Tuesday, March 3, 2020

RING FRAME PROCESS PARAMETERS


PARAMETERS IN RING FRAME PROCESS:

The parameters used in the ring frame process are given below:

The hardness of the traveller should be less than the hardness of the ring surface. This practice helps to optimise the life of the ring surface. The traveller is cheaper than a ring, so that maintenance cost is also gets reduced. The replacement method of traveller is easier in comparison ring so that reduced downtime also helps to optimise the efficiency of the machine. 

The hardness range 800 - 850 Vickers of the ring surface gives the best results in terms of the life of the ring. 

The weight of the traveller gets selected according to the spindle speed, yarn count, yarn strength and material to be processed. Low traveller weight results in the form of low bobbin density and low cop content. The higher traveller weight causes high yarn tension. The ends breakages get increased.

If the higher break draft is applied in the ring frame process, the draft setting gets more critical.

The break draft in the ring frame process is employed to the total draft in each case since the main draft does not exceed 25 to 30.

• The setting of the front top roller is kept slightly forward by a distance of 2 to 4mm relative to the front bottom roller, while the middle top roller is kept a short distance of 2mm behind the middle bottom roller.

The overhang of the front top roller results in the form of smooth working of the top rollers and reduces the spinning triangle. This helps to reduce the end breakage rate in the ring frame process.

The back top rollers are coated with hard rubber generally because compact and twisted roving enters the back roller which does not need extra guidance and fibres control.  The hardness of rubber cots is kept 80 – 85 degrees shore in the back front roller.

The hardness of rubber cots of front top roller ranges between 63 – 65 degrees shore because the drafted fibre strand contains very less number of fibres which needs extra guidance and fibres control.

The proper setting in the ring frame process has great importance. The specific shape of the cop is achieved by placing the layers of yarn in a conical arrangement.

• In the winding of a layer,  when the ring rail gets moved upward direction, the rail traverse speed is low at the bottom and increased at the top position.
When the rail comes downward direction, the rail's traverse speed gets maximum at the top position and minimum at the bottom portion.
This gives a ratio between the length of yarn in the main (up) and cross (down) windings about 2:1.

A maximum traveller speed of 40 m/sec can be achieved in a modern ring and traveller combination with good fibre lubrication.

The high contact pressure (up to 35 Newtons /square metre) gets generated between the ring and the traveller during winding, mainly due to centrifugal force. This pressure leads to the generation of heat.

Traveller mass determines the magnitude of frictional forces between the traveller and the ring, and these in turn determine the winding and balloon tension.

If a choice is available between two traveller weights, then the heavier is normally selected since it will give greater cop weight, smoother running of the traveller and better transfer of heat out of traveller.

The total length of a complete layer (main and cross windings together) should not be greater than 5m (preferably 4 m) to facilitate unwinding.

The traverse stroke of the ring rail is ideal when it is about 15 to 18% greater than the ring diameter.

End break suction system has a variety of functions. It removes fibres delivered by the drafting arrangement after an end break and thus prevents multiple end breaks on neighbouring spindles. It enables better environmental control since a large part of the return airflow of the air condition system is led past the drafting system, especially the region of the spinning triangle.

In modern installations, approx. 40 to 50 % of the return air-flow passes back into the duct system of the Air conditioning plant via the suction tubes of the pneumatic suction system.

A significant pressure difference arises between the fan and the last spindle. This pressure difference will be greater, the longer the machine and the greater the volume of air to be transported.

A relatively high vacuum must be generated to ensure suction of waste fibres    for cotton - around 800 Pascal for synthetic - around 1200 Pascal

The airflow rate is normally between 5 and 10 cubic meters per hour.  Remember that the power needed to generate an airflow of 10 cubic meters/ hour, is about 4.5 times the power needed for an airflow of 6 cubic meters/ hour, because of the significantly higher vacuum level developed at the fan.



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