DESC:BACKGROUND OF INVENTION:-
The present invention relates to a guide roller assembly of the rolling stand of TMT (thermo mechanical treatment) bar rolling machine. More particularly, improvement of the guide roller assembly, of the rolling stand of thermo mechanical treatment to reduce bearing failure due to high temperature exposure and contamination with cooling fluid.

BACK GROUND OF INVENTION:-
TMT bar stands for thermo mechanically treated bar. In this process hot steel billets are heated in a reheating furnace and rolled through a sequence of rolling stands which progressively reduces the cross section of billets to the finished size and shape of the TMT reinforcement bar. This hot rolling process is followed by the quenching and self-tempering process to give the bar more strength and ductility.

TMT Process : There are rollers which roll the bar in between to reduce its size, description as shown in Figure 01, so the temperature of the rollers comes in direct
contact of hot steel bar is very high. The bearing which is mounted in the roller bar torotate it also exposes to high temperature. There is a cooling water contamination
which is used to cool down that roller. Design of roller assembly is as shown below in figure 3.

In the thermal mechanical treating rolling mill, the rolling stand fork holds the two no’s of roller assembly. This assembly is exposed to high temperature of 400 °C. Also there is a contamination of cooling fluid and load fluctuation of bearing. Due to these factors there is a high rate of bearing failure and very low life i.e. 6 to 10 hours.

The failure of roller assembly results in:
? Lower service life: 6-10 Hours
? Poor product quality and wastage : 1-2 meter bar length
wastage due to bearing failure?
? Change over time : 02 Hours (Approx)?
? Low productivity: Approx. 90 ton/Day?
? Higher inventory & inventory cost?
? High man fatigue level?
? Unsafe operation due to more breakdown?

OBJECT OF THE INVENTION:-
It is an object invention to provide improved roller assembly in the thermo mechanical treatment bar to reduce failure due to contaminated cooling fluid and high temperature exposure.

It another object of invention to provide improved roller assembly in the thermo mechanical treatment bar so as to improve service life, to reduce breakdown and setting time.

STATEMENT OF THE INVENTION:

Accordingly the invention provides a novel guide roller assembly of the rolling stand of thermo mechanical treatment bar rolling machine comprises a holder with one end fork formed with a pair ribs at parallel and distant with holes in line on each the said rib to support a roller with a pair of bearings; a pin, with circular head, having step diameter with larger diameter portion of the length matching with the width of the said rib adjacent to the said circular head; a pair of metallic labyrinth circular seal with center hole, of diameter matching with smaller diameter of the said pin,
mounted to the said holder with the said pin passing through the said holes of ribs; a locking socket cap of length matching with the width of said rib outer diameter matching with rib hole diameter engaged to other end of said pin with fastener.

REFERENCE TO DRAWING:-

The invention is described with reference to figures of accompanying drawings wherein,

Figure 1 shows the layout diagram of thermo mechanical treat plant;

Figure 2A and 2B front view of roller assembly in the thermo mechanical treat plant exposed to high temperature and contamination cooling fluid which makes failure of roller assembly damage to bearings;

Figure 3 shows part section view showing the details roller mounted with bearing;

Figure 4 shows perspective view of roller assembly roller of prior art held between fork of the holder;

Figure 5 shows sectional view of roller assembly according to invention indicating details of constructional features.

Figure 6 shows sectional view of roller assembly with holder arm according to invention.

DESCRIPTION OF THE INVENTION:-

Referring to figure 1, in thermo mechanical treatment bar rolling machine, there is a set of rollers which gradually decreases the diameter of the thermo mechanical treatment bar. It is a thermo mechanical process in which bar is heated to make it soften and easy to machining. ts temperature rises up to 400 C between the rollers this bar is rolled and its size is reduced and desired size is acquired.
The prior art roller assembly which is used in the mill as shown in Figures 2, 3 and
4. There is no protection for the bearing and hence the bearing gets failed after 6 to 10 hours. The failure of the bearing causes the breakdown of the process.

The roller assembly in the thermo mechanical treatment gearing is required to be protected loss of lubrication due high temperature exposure and contamination of cooling fluids.

Referring to figures 5 and 6 bearing is protected with sealing so that there is no loss of lubrication from the bearing of roller and also no contamination to bearing.
A novel guide roller assembly of the rolling stand of thermo mechanical treatment bar rolling machine comprises a holder with one end fork formed a pair ribs at parallel and distant with holes in line on each the said rib to support a roller with a pair of bearings. A pin, with circular head, having step diameter with larger diameter portion of the length matching with the width of the said rib adjacent to the said
circular head. A pair of metallic labyrinth circular seal with center hole, of diameter matching with smaller diameter of the said pin fixed to the bearing center hole mounted to the said holder with the said pin passing through the said holes of ribs and the said sleeve of seal. Alternatively, a pair of metallic labyrinth circular seal with center hole, of diameter matching with smaller diameter of the said pin, with sleeve formation fixed to the bearing center hole mounted to the said holder with the said pin passing through the said holes of ribs and the said sleeve of seal. A closure socket cap of length matching with the width of said rib outer diameter matching with rib hole diameter engaged to other end of said pin with fastener.

The roller of the assembly fitted with a pair of special ball bearings with metallic type labyrinth seal having sleeve secured the bearing mounting hole so as to totally seal both sides of cooling fluid. This will overcome the problem contamination bearing with cooling fluid. Thus cause of failure of bearing overcome. Further, from figures 3
and 6, arrangement of providing roller with metallic labyrinth circular seal with sleeve to the fork holder with stepped diameter pin will enhances sealing quality and
prevents leakage fluid to bearings through pin. The step diameter pin of large diameter portion resting against the metallic labyrinth seal will prevent leakage fluid
to bearing.

Similarly the closure socket cap resting against the metallic labyrinth seal surface prevents leakage offload to bearing.

While mounting roller to holder the bearings the said bearings provided with high temperature grease with operating range of -30°C to +600°C. At elevated temperature (over +200°C) it evaporates without carbonizing, leaves only dry lubricating film of solid which gives exceptional lubrication under the most severe condition. This possible due to sealing with metallic labyrinth seal.

The application requirement and RE designed and developed the roller assembly with bearing mounting to improve life and to reduce the breakdown. Change in design of guide roller assembly, Re-designed total roller segment incorporating bearing, seal, pin and lock in it. Roller material (AISI-D2) will be in forged condition
to for enhancement of life.
? Bearing clearance grade change: CN to C3?
? Sealing provision: for elimination of effect of contamination of fluid and adverse effect of high temperature?
? Lubrication improvement: Use of high temperature grease with operating range of -30°C to +600°C at elevated temp. (over +200°C) it evaporates without carbonizing, leaves only dry lubricating film of solid which gives exceptional lubrication under the most severe condition.?
? Total Assembly: ABC will provide total guide roller assembly instead of only bearing, which will contains modified changes, which will better address the
difficulty.?

LIST OF PARTS AND THEIR CONNECTIVITY:-

01: Special Bearing 6203 ZZ:
02: Seal Cover Top and Bottom
03: Roller
04: Pin
05: Locking cap.

FUNCTION/ PURPOSE OF EACH PART:-
? Special Bearing 6203 ZZ: To support the rolling movement of roller and absorbs shocks & vibration.
? Seal Cover Top and Bottom: To seal the bearing from the contamination of cooling water.
? Roller: Main component which comes into contact of guide roller and decreases the diameter of bar.
? Pin: Main shaft of bearing and roller.
? Locking cap: to lock the shaft in the position.

ACHIEVEMENT OF INVENTION:-
1. Improvement of service life.
2. The plant efficiency improved with reduction in breakdown.
3. The plant efficiency improved with reduction in setting time.
4. The cost of production comes down due to reduction inventory.
5. Increase in overall efficiency of machine.
6. The improvement in productivity.
7. The plant break down free performance made reduction human fatigue.
8. The plant break down free performance made reduction in man power.

ADVANTAGES OF THE PRESENT INVENTION:-
? Service life Improved: Total 8 times+ of improvement from 6 - 10 hours to more than 86 hours for whole assembly.
? Breakdown reduced: More than 8 times. Man power reduced.
? Cost reduced.
? Wastage and scrape reduced (saving of 16 meters of bar / set up).
Inventory reduced.
? Productivity Improved: Productivity increase from average 8 hrs to 85 hrs with using ABC’s component. 120 ton/day.
? Safe operation ,CLAIMS:1. A novel guide roller assembly of the rolling stand of thermo mechanical treatment bar rolling machine comprises a holder with one end fork formed with a pair ribs
at parallel and distant with holes in line on each of the said rib to support a roller with a pair of bearings; a pin, with circular head, having step diameter with larger
diameter portion of the length matching with the width of the said rib adjacent to the said circular head; a pair of metallic labyrinth circular seal with centre hole, of
diameter matching with smaller diameter of the said pin, mounted to the said holder with the said pin passing through the said holes of ribs; a locking socket cap of length matching with the width of said rib outer diameter matching with rib hole diameter engaged to other end of said pin with fastener.

2. The guide roller assembly as claimed in claim 1 wherein, the said metallic circular seal provided with a sleeve formation to the central hole, of diameter matching with smaller diameter of the said pin, to facilitate mounting to the said holder with the said pin passing through the said holes of ribs and the said sleeve of seal.

3. The guide roller assembly as claimed in claims 1 and 2 wherein, high temperature grease with operating range of -30° C to +600° C. At elevated temp. (over +200° C) provided to bearing while mounting the said metallic labyrinth seal
so that the said grease evaporates without carbonizing, leaves only dry lubricating film of solid which gives exceptional lubrication under the most severe condition.

4. The guide roller assembly as claimed in claims 1 to 3 wherein, the said Special Bearing is 6203 ZZ.

5. The guide roller assembly as claimed in claims 1 to 4 wherein, the said bearing having bearing clearance grade CN to C3.

6. The guide roller assembly as claimed in claims 1 to 5 wherein, the said roller material steel of AISI-D2 in forged condition to for enhancement of life.