Claims:CLAIMS:

1. A modified track roller of skid car, comprising of:

a plurality of spherical roller bearings have two rows of rollers;

a common sphered outer ring raceway; and

two inner ring raceways inclined at an angle to the bearing axis.

2. A modified track roller of skid car as claimed in claim 1, wherein the centre point of the sphere in the outer ring raceway is at the bearing axis.

3. A modified track roller of skid car as claimed in claim 1, wherein the bearings are self-aligning and insensitive to misalignment of the shaft relative to the housing.

4. A modified track roller of skid car as claimed in claim 1, wherein the spherical roller bearings are designed to accommodate heavy radial loads, as well as heavy axial loads in both directions.

5. A modified track roller of skid car as claimed in claim 1, wherein the spherical roller bearing is SKF-22214E.

Dated: this 21st day of March, 2016.

To,
The Controller of Patents, The Patent Office, Kolkata.

(N. K. Gupta) Patent Agent, Of NICHE,
For SAIL.
, Description:FORM 2

THE PATENTS ACT, 1970

(39 of 1970)
COMPLETE SPECIFICATION (Section 10 and rule 13)

TITLE

MODIFIED TRACK ROLLER OF SKID CAR

APPLICANT

STEEL AUTHORITY OF INDIA LIMITED, A GOVT. OF INDIA ENTERPRISE, ROURKELA STEEL PLANT, ROURKELA - 769011, ORISSA, INDIA

The following specification particularly describes the nature of the invention and the manner in which it is to be performed

MODIFIED TRACK ROLLER OF SKID CAR

FIELD OF INVENTION:

The present invention relates to a modified track roller of skid car. More particularly, the present invention relates to providing a better cost-efficient means of modifying the highly expensive track type rollers used extensively in transport vans in cross transfer mechanism with the relatively inexpensive commonly available spherical roller bearings.

BACKGROUND OF THE INVENTION:

The invention has been installed and commissioned in the Roller Discharge and Slab Transfer area of Continuous Casting Machine-I (CCM-I) Shop of Steel Melting Shop-I(SMS-I) of Rourkela Steel Plant, SAIL.

There are 2nos. of 66 tons LD convertors at SMS-I, namely Convertor #P & #Q, which produce 0.4MT, steel annually.

The Continuous Casting Shop, CCM-I, houses

Ladle Heating Furnace (LHF) Argon Rinsing System (ARS) Caster Proper
Torch Cutting Machine (TCM) Slab Storage and Dispatch Yard

One LHF is used for homogenizing and final adjustment of temperature and chemical analysis of steel tapped from Converter before being sent to Casters f or casting. One ARS is used for homogenizing and final adjustment of temperature and chemical analysis of steel tapped from converters before being sent to casters for casting. ARS consists of: Alloying system, Wire feeding machine, there is a single strand slab caster and a turret for handling the ladles and providing steel on
continuous basis. They can rotate 360o and can lift a 70 T ladles and rotate. The

slab caster has a water cooled copper mould, which gives the required dimensions of the slabs produced. The strand produced is further cooled by water sprayed

through specially designed nozzles and simultaneously pulled out by drive rolls and straightened. The continuous long strand is at suitable lengths to form slabs and is cut by using transverse torch cutting machine, which moves along with the strand and cuts slabs using oxygen and acetylene.

Average heat size: 60-70 tons

No. of strand / machine: 1

Casting size: 210 mm thickness

Width: 800 - 1275 mm

Length: 6000 - 8000 mm

TCM is used to cut the slabs online to the required length. The cutting operation is done by oxyacetylene gas flame. Produced slabs are stacked for proper identification for dispatching to Hot Strip Mill (HSM) and Plate Mill (PM) for further processing.

Cross transfer with storage rack is intended for cross transferring of cut slabs of max length 6000- 8000mm coming from the continuous casting m/c. Cross transfer is installed at the end of the discharge roller table. It consists of 3 skid cars running on track beams, one car on each beam. The skid car frame is mounted on 4 runner wheels and 4 side guide rollers. Both ends of the car are clamped through wire ropes. There were various repeated instances of the skid cars failure (mainly the runner wheels would get jammed) as such either the runner or side guide wheels had to be modified.

Due to failure of the yoke bearings the cross transfer mechanism had to be shut down as such there existed both production and safety issues. The caster had be run below its optimal speed because the discharge roller table could accommodate at most 2 cut slabs and in case there was some even minor issues with the EOT cranes, the casting had to be aborted in view of the accumulated slabs. Even the hauling up of cut slabs from the roller discharge area by the cranes were fraught with safety concerns as there existed every opportunity of the crane tongs getting entangled in the ribs of the discharge rollers leading to damage to the crane as well as the whole roller discharge unit and the cross transfer unit as well.

OBJECT OF THE INVENTION:

The basic objective of the invention is to modify the highly expensive stock-out yoke type track roller runner wheel design with spherical roller design runner wheel to increase the availability of the equipment leading to higher caster productivity. It involves economics of cost saving.

Another objective of the innovation is to eliminate production loss due to equipment downtime, thus leading to higher caster productivity - the caster could be run at its optimal speed and better slab dispatch due to faster removal of cut slabs from run- out area of caster for down process.

SUMMARY OF INVENTION

The innovation is directed to modify the highly expensive stock-out yoke type track roller runner wheel design with less costly spherical roller design runner wheel having the same functionality leading to huge financial savings and thereby increase the availability of the equipment leading to higher caster productivity. With this exceptional piece of work, yoke type track rollers having extensive applicability in cam gears, bed ways and conveying equipment’s find a fully functional cheaper substitute. The present modification has been successfully attempted in the steel slab caster of Steel Melting Shop-I (SMS-I) but can be replicated in such similar and diverse applications.

Such as herein described, there is provided a modified track roller of skid car comprising of: a plurality of spherical roller bearings have two rows of rollers; a common sphered outer ring raceway; and two inner ring raceways inclined at an angle to the bearing axis.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS:

Fig. 1 illustrates the impaired skid car with the damaged worn out runner wheel as prior art;

Fig. 2 illustrate the CAD view of the original existing Yoke type track rollers NNTR70X180X85-2ZL and modified spherical roller bearing SKF-22214E in accordance with the present invention;

Fig. 3 illustrates the applied modification on the rollers for the runner wheel in accordance with the present invention;

Fig. 4 illustrates the fabricated spacer made in house for making up the width of the runner wheel in accordance with the present invention.

DETAILED DESCRIPTION:

The innovation is directed to modify the highly expensive stock-out yoke type track roller runner wheel design with spherical roller design runner wheel to increase the availability of the equipment leading to higher caster productivity. It involves economics of cost saving.

Each skid car frame is mounted on 4 runner wheels. The runner wheels are yoke type track rollers NNTR70*180*85-2ZL- full complement roller set with axial guidance, central rib, sealing shields with lamellar ring on both sides and it is guided by the central rib and the rolling elements. The impaired skid car with the damaged worn out runner wheel is shown in Fig. 1, which has the stock out expensive yoke type track rollers running it.

The runner wheels were fabricated of the required dimension after studying the existing unit and two spherical roller bearings were placed in the wheel along with spacers and locking circlips to make up for the width of the runner wheel on the track beams. End covers and lubricating points were fabricated for long running and safety of the modified unit.

As an exemplary embodiment, the expensive and stock-out yoke bearings were modified with fabricated wheels of required dimension with less costly spherical roller bearings having the same functionality leading to huge financial savings.

The Fig. 2 shows the CAD view of the original existing Yoke type track rollers

NNTR70X180X85-2ZL which is modified by spherical roller bearing SKF-22214E.

The illustrated spherical roller bearings have two rows of rollers, a common sphered outer ring raceway and two inner ring raceways inclined at an angle to the bearing axis. The centre point of the sphere in the outer ring raceway is at the bearing axis. Therefore, the bearings are self-aligning and insensitive to misalignment of the

shaft relative to the housing, which can be caused, for example, by shaft deflection. Spherical roller bearings are designed to accommodate heavy radial loads, as well as heavy axial loads in both directions.

The bearing was so chosen because the diameter of the skid car spindle on which the yoke type track rollers are assembled corresponds to the width of the shaft on which the 22214 bearing can be mounted (14x5 = 70).

The applied modification on the rollers as shown in Fig. 3, for the runner wheel wherein the spherical roller bearings have been used in place of the yoke type track rollers. As it is evident from the fig.1, the width of the yoke type track roller is more than twice that of the spherical roller bearing (B = 85 vs. 31). It was decided to incorporate two spherical roller bearings on the runner wheel with two fabricated spacers (numerically calculated thickness) to make up for the width of the runner wheel and two locating end standard circlips for ? 70mm shaft was assembled and firmly placed in the runner wheel and then fit together and mounted on the skid car spindle and the whole assembled conveying van was placed on the track beam.

There is also provided a fabricated spacer as shown in Fig. 4 for making up the width of the runner wheel along with the standard locating circlip for ? 70mm shaft for insertion in the skid car spindle. It provides us with a easier to maintain/repair/modify system.

Cost-benefit analysis:

Cost of NNTR yoke type track roller- Rs. 1.3- 1.5 lakhs

Cost of SKF spherical roller- Rs 5000

Average caster production during down-time of cross transfer-

The caster was run 0.1- 0.2 m/min below its optimal speed to accommodate hauling up of cut slabs.

Loss of production in an hr. in terms of mtrs. of casting: 0.15 * 60 = 9m

Loss of production in a day in terms of mtrs. of casting: 9 * 24 = 216m

Taking into account, 6 hrs for casting sequence break/ turnaround time & 90%

caster availability , loss in production = 9 * 18 * 0.9 = 145.8m

Considering a cut slab of 7m weigh on an average 15T, 145.8m would weigh = (145.8/7) * 15 = 312.43T

Considering a min NSR of Rs 3,500 from the sale of slabs without any further processing, lost opportunity = 312.43 * 3,500 = Rs 10,93,505 /day

Although the foregoing description of the present invention has been shown and described with reference to particular embodiments and applications thereof, it has been presented for purposes of illustration and description and is not intended to be exhaustive or to limit the invention to the particular embodiments and applications disclosed. It will be apparent to those having ordinary skill in the art that a number of changes, modifications, variations, or alterations to the invention as described herein may be made, none of which depart from the spirit or scope of the present invention. The particular embodiments and applications were chosen and described to provide the best illustration of the principles of the invention and its practical application to thereby enable one of ordinary skill in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated.