This invention relates to a ring with improved working profile for a ring traveller assembly in textile spinning machines.
Rings play a very important role in determining the twist, strength, imperfections and hairiness of the yam produced by spinning. The speed of operation of the spinning machine also depends on the surface finish and profile of the ring.
The configuration of working profile of the existing ring has an inner radius of about 1.15 mm. These rings are made of bearing steel and are hardened by heat treatment. This configuration does not provide adequate mating with the ring traveller. Further, machining and heat treatment do not result in producing very smooth inner surface. These draw backs result in inferior quality yam and affect the rate of production adversely.
This invention is aimed at improving the performance of the ring and traveller assembly for producing better quality yam. Improvement in the rate of production is also one of the objects of this invention.
The inner radius of the working profile or surface of the ring is altered from the existing 1.15 mm to a range of 0.87 mm to 0.94 mm. This enables better contact with the mating traveller without causing yam breaks.

Such rings with the improved working profile are manufactured by conventional machinery and heat treatment. Improved surface is achieved on these rings by subjecting them to cryogenic treatment or plasma nitriding. The rings undergo transformation during such treatments to provide better surface resulting in substantial reduction in friction during operation.
Cryogenic treatment is carried out in a double walled chamber. The chamber houses pipes in between walls through which any suitable coolant such as liquid nitrogen is allowed to flow. Conventional cooling agents such as liquid nitrogen may be used. Rings may be subjected to slow cooling till the required subzero temperature is reached. This temperature is maintained tor a predetermined period of time and then the temperature raised to room temperature.
In a particular example the rings are cryogenically treated inside the chamber at room temperature. The chamber is sealed and the temperature is brought down to about -320^F for about 28 to 30 hours. Then the chamber temperature is kept at about -320°F for about 48 to 60 hours. The temperature inside the chamber is then raised to room temperature of about 40°F in steps of 0.5°F. The time taken to raise the temperature from -320°F to 40°F is approximately 28 to 30 hrs. After the temperature reaches 40°F, the rings are left in the chamber for about 2 to 3 hours.

This treatment results in homogenity of the ring surface, which leads to higher wear resistance and higher sliding properties.
Rings with improved working profile may also be subjected to plasma nitriding for providing smooth surface finish. After heat treatment, these rings are subjected to plasma nitriding whereby diflusion of nitride takes place for a thickness of 13 to 120 microns leaving a specific structure consisting of very thin and compact zone for about 10 microns. This surface gives higher wear resistance and low friction properties which in turn provides high wear resistance and low fiiction. The rings thus treated have longer life and increased speed.
Plasma nitriding is effected in a double walled stainless steel chamber which is water cooled. The chamber has a viewing window and a support. A vacuum pump and power supply source are connected to this chamber.
The ring to be plasma nitrided forms the cathode and the walls of the chamber form the anode. The working chamber is evacuated after sealing and a gas mixture of nitrogen and hydrogen in the ratio of about 25% to 75% is allowed to flow therethrough. The gas flow is controlled through a flow control valve and a fieter for removing moisture and oxygen. Glow lischarge is initiated between the cathode and anode on power supply which onises the gaseous medium. Positive nitrogen ions are accelerated towards hie cathode which is the ring in this example. High kinetic energy of these

ions heats the ring to nitriding temperatures and removes possible contaminants and oxides. The pressure of the gaseous medium and the current strength are increased uniformly till the ring is saturated with nitrogen. The voltage applied to the chamber is about 300 to 500 votts and
the temperature of plasma nitriding is about 400°C to 550°C. The plasma nitrided ring can be used directly with out refinishing or cleaning.
This invention relates to a ring with improved working profile for a ring traveller assembly wherein said ring has an inner radius ranging from 0.87 mm to 0.94 mm and is surface treated to provide smooth surface finishing for reducing fiiction during operation.
This invention will now be described with reference to Figure I of the accompanying drawings which is an enlarged sectional view of the ring.
Reference numeral 1 indicates the inner radius which ranges fi^om 0.87 to 0.94 mm. Numeral 2 indicates the outer radius of the ring. Reference numerals 3 and 4 show the inner and outer web of the ring and numeral 5 shows the fitting diameter of the ring. Reference numeral 6 shows the seating surface of the ring.

WE CLAIM:
1. A ring with improved working profile for a ring traveller assembly wherein said ring has an inner radius ranging from 0.87 mm to 0.94 mm and is surface treated to provide smooth surface finishing for high wear resistance and reducing fuction during operation.
2. The ring as claimed in claim 1, wherein said surface treating is effected by subjecting the ring to cryogenic surface treatment after conventional mechanical finishing and heat treatment.
3. The ring as claimed in claim 2, wherein said cryogenic tgreatment is carried out at -320°F for about 28 to 30 hours and thereafter raising the temperature slowly to 40°F.
4. The ring as claimed in claim 1, wherein said surface treating is effected by plasma nitriding said ring after conventional mechanical finishing and heat treatment.
5. The ring as claimed in claim 1, wherein plasma nitriding is effected in the presence of a gaseous mixture of hydrogen and nitrogen at a temperature ranging from 400°C to 550°C.

6, A ring with improved working profile substantially as herein described.