FIELD OF THE INVENTION

The present invention relates to spinning and twisting rings used in textile ring spinning and twisting machines. More particularly, this invention relates to an improved hard chrome plating technique used on the rings of textile ring spinning and twisting machines.

BACKGROUND OF THE INVENTION

In conventional ring spinning and twisting machines, spinning or twisting rings are used to support a traveler that moves rapidly around the circumference of the spinning ring. The ring comprises a flange portion making a track for running of a ring traveler in a sliding contact condition and a mount portion mounted on a ring rail through fitting connection means. The traveler engages and guides the yarn delivering from the drafting zone as it is being twisted and wound onto the tube mounted downstream on the spindle and the yarn cop built-up takes place. The traveler engages and guides a loose yarn as it is being twisted and wound onto the tube mounted on the revolving spindle.

An increase in spinning speed increases the rate at which the traveler rotates around the surface of the spinning ring thereby also increases the centrifugal force applied between the traveler and the ring. In turn, the greater centrifugal force increases frictional heating of the ring and the traveler and also increases the abrasive force applied to the ring and the traveler. Due to frequent running at higher speeds, fine vibrations are possibly generated on the ring flange portion at the time of running of a ring traveler and causes the ring traveler and the ring flange portions to undergo abnormal wear and reduces the service life of the ring and traveler. It may reduce the lifetime of the traveler to a large extent, and also typically reduces the lifetime of the spinning ring because the surface of the ring can peel off, chip or otherwise become roughened. As the spinning speed is increased, the resulting increase in frictional or abrasive forces between the ring and the traveler can cause breaks in the yarn being spun or twisted. Yarn breaks are particularly undesirable because they lead to downtime in the spinning operation and thus leads to a lower manufacturing efficiency. For this reason, the construction of the rings and the traveler have a substantial impact on the efficiency of the ring spinning and twisting process.

In existing ring spinning and twisting machines, rings are being coated with hard chrome plating having higher coefficient of friction and lesser hardness. Further the. hard chrome plated rings does not provide higher machine efficiencies at higher speeds of the spindle rotation. The main drawback in the hard chrome plating is substantial rejection of rings due to the inherent problems associated with the manufacturing process (i.e. peel off, rough surface finish). Further, after assembling the rings in the machine, the spindle speed has to be maintained at lesser rotation levels for few days in order to provide proper running-in for the rings. During running-in period, the production efficiency is very low.

It will be advantageous if the hard chrome plating process over the rings results in lesser coefficient of friction and increased hardness. Further it will be more advantageous if the running-in period is eliminated. It will be advantageous if the spindle speed can be increased straight away (i.e. zero running-in period) after the completion of machine erection thereby the productivity of the machine can be enhanced. Thus there is a need in the art for a ring that overcomes the disadvantages of the prior art.

The hard chrome plating technique revealed in this invention overcomes the above said drawbacks since the hard chrome plated ring has a low friction coefficient and heat generation at the contact point of ring and traveler is much lesser compared to that of the existing hard chrome plated rings.

OBJECTS OF THE INVENTION

It is an object of the present invention to provide an improved hard chrome plating technique for application on the rings of textile ring spinning and twisting machines.

It is another object of the invention to provide a ring for textile ring spinning and twisting machines resulting in enhanced efficiency.

It is yet another object of the invention to increase the life of the ring as well as the traveler in textile ring spinning and twisting machines.

It is another object of the invention to eliminate the aforementioned disadvantages in the prior art.

SUMMARY OF THE INVENTION

Normally, textile spinning and twisting rings are provided with hard chrome plating before usage in ring spinning and twisting machines. The present invention suggests suspension of nanodiamond particles in the electrolyte bath before hard chrome plating. The process is explained in the following description. The trials conducted on the rings with the disclosed method exhibited eminent improvement in the characteristics of the ring.

BRIEF DESCRIPTION OF THE INVENTION

The rings are manufactured using Carbon and alloy steel in any one of the known techniques and are hardened and smooth finished to a surface finish value of less than 0.2 Ra. The rings so manufactured may contain contaminants such as dust, dirt, oil, pigments, grease, fingerprints and so on. Hence the rings are thoroughly cleaned by ultrasonic cleaning equipment. The ultrasonic cleaning method uses ultrasound (usually from 20 to 400 kHz) and an appropriate cleaning solution to clean the rings. The ultrasound is not effective without the cleaning solution. The rings are first placed in a chamber containing cleaning solution. Then ultrasonic waves are passed into the chamber through any ultrasound generating means. As a result, the rings are cleaned thoroughly. The surface dirt and contaminants are completely removed. Then the cleaned rings are to be hard chrome plated.

The plating process is explained for a sample of 100 litres of galvanic electrolyte bath. The proportions can be varied based on the suitable ratio for the total volume of electrolytic bath. For example, before hard chrome plating, 100 litres of galvanic electrolyte should be prepared for chrome plating. The electrolyte used is Chromic acid solution. Then the amount of known chemicals used in hard chrome plating corresponding to 100 litres of chrome plating bath should be dispersed in 70 litres as a concentrated suspension.

Then the Nanodiamond (ND) suspension with concentration 50 to 100 grams/litre and total volume of 8 to 10 litres should be dispersed in 20 litres of De-Ionised water (Dl water) by mechanical stirring until an uniform suspension is obtained. After that, the well stirred Nanodiamond (ND) suspension is slowly added into 70 litres of the hard chrome plating concentrate and mixed thoroughly in any known method (i.e. mechanically or with air agitation etc). The above procedure is done before plating.

The hard chrome plating is done in usual method after the above said process using Nanodiamond suspension. For plating, Nanodiamond with purity level 90 to 99 % is used. The size of single ND particle is in the range of 4 to 10 nm.

The above said process has improved the characteristics of the rings to an increased extent. The following are the advantages obtained in the rings using said plating process:

- Reduced grain size
- Increased micro hardness
- Increased wear resistance (2 to 8 times more than existing hard chrome plating)
- Reduced corrosion
- Decreased porosity
- Enhanced adhesion (30 to 40 %).

Further the rings exhibit a higher hardness in the range of 1100 to 1400 HV. The thickness of the rings at the inside functional area is found to be 10 to 25 microns. The friction coefficient is below 0.1 which is remarkable and leads to zero running-in. The increased hardness and low friction coefficient will provide a longer life to both the rings and travelers compared to that produced by existing hard chrome plating. The process disclosed overcomes all the disadvantages cited in the background of the invention.

The following advantages are obtained in the resultant yarn using said rings:

- Reduced Hairiness Index (Total length of protruding fibres)
- Reduced Imperfections (Yarn faults such as thick places, thin places and neps).
- Reduced Unevenness (Number of fibres in a cross section steadily decreases and increases without uniformity). - Reduced End Breakage Rate.

TRIAL RESULTS

We claim:

1. A method for producing a textile spinning or twisting ring, comprising the steps of

a) hardening and smoothening said ring;

b) cleaning said ring by ultrasonic cleaning using ultrasound waves; and

c) chrome plating said ring in an electrolyte bath by hard chrome plating concentrate characterized in that the hard chrome plating concentrate has nanodiamond suspension.

2. The method as claimed in claim 1, wherein the electrolyte is chromic acid
solution.

3. The method as claimed in claim 1, wherein the purity level of nanodiamond suspension is 90 to 99%.

4. The method as claimed in claim 1, wherein the size of single nanodiamond particle is 4 to 10 nm.

5. The method as claimed in claim 1, wherein nanodiamond suspension has concentration of 50 to 100 grams per litre.

6. The method as claimed in claim 1, wherein the nanodiamond suspension is dispersed in de-ionized water until a uniform suspension is obtained.

7. The method as claimed in claim 1, wherein the friction coefficient of the hard chrome plated ring is less than 0.1.

8. The method as claimed in claim 1, wherein the hardness of the ring is in the range of 1100 to 1400 HV.

9. The method as claimed in claim 1, wherein the thickness of ring at the inner functional area of the ring is 10 to 25 microns.

10. A textile spinning and twisting ring comprising; a hard chrome plating on said ring; wherein said hard chrome plating is formed in an electrolyte bath with hard chrome plating concentrate and wherein the hard chrome plating concentrate has nanodiamond suspension.