Rails Manufacturing:

 Rails Manufacturing:

BSP generated 1080HH Rails, They are not being used because of weldability problem.

In 1080 HH rails only head is hardened, but flange is weak, whereas 1080 High Tensile Strength rails whole cross section is hardened.

NCC (Nickel Chromium copper) rails preferred to used in coastal area and R350 Grade rails preferred to used in curves.

Hot Rolling Process

Bloom temperature 1170 C to 1200 C

Step1:- Bloom will undergo 7 passes and length increase from 10 m to 20 m

Step2:-Bloom will undergo 5 passes and length will increase from 20m to 40m. In this stage preliminary shape of the rail will be achieved.

Step3:- Bloom will undergo 3 passes and length will increase from 40m to 135/137m. Final shape arrive in this stage. After this stage heat no. will be given. Finishing of the rail profile done through 3 sequences, universal rubber, universal finisher.

Step4: End cropping will be done. After that they will place rails in Pre-cambered curve with convex portion on head side. cooling fans are provided beneath the rails. Generally cooling time will be around 3hours. After completion of cooling rail will shrink and length reduced to about 132-233m

* Shrinkage 1.3%

* While(during)rolling process speed of the rail 3.4m/s

*All the machines are of "SMS MEER Make".

Stage5: Rail will undergo straightening through RRSM (Rail Roller Straightening machine). 

Initially horizontal straightening and then vertical straightening. straightening will be completed within 1 to 1.5min.

After straightening of rail end, end straightness will be checked 3m from the end of the rail using 2m straight edge. If any deviations it will be corrected through rail straightening machine.

Rail Profile is checked using different templates(Gauges for height, head width, foot width, symmetry ) and with different screw-gauge web thickness measure.

Web thickness tolerance:16.0 to 17.5mm

Tolerance checking done for every 12 blooms(12x130m)