NATIONAL INSTITUTE OF TECHNOLOGY JAMSHEDPUR

TRAINING REPORT

ROLLING MILLS

TRAINING ORGANISATION

-MECON LIMITED, RANCHI

(DURATION-MAY 25th TO JUNE 24th 2015)

NISHANT SINGH

2013UGME076

SEMESTER-V

DEPARTMENT OF MECHANICAL ENGINEERING

ABSTRACT

THIS REPORT IS BASED ON THE LEARNINGS ACHIEVED IN 2 WEEKS OF THE ONE MONTH TRAINING SESSION IN MECON LTD. UNDER THE ROLLING MILLS SECTION.

THIS REPORT PARTICULARLY FOCUSES ON THE COLD ROLING MILLS THAT ARE ESSENTIALLY THE MOST IMPORTANT AND HIGHLY PRECISE MILLS OF THE PLANT. MINOR DETAILS OF HYDRAULICS HAVE ALSO BEEN DEALT WITH TOWARDS THE END.

THE INFORMATION PROVIDED IN THIS REPORT IN BASED ON THE CUMULATIVE ACCUMULATION OF ALL THE INFORMATION GAINED FROM THE RESPECTIVE OFFICIALS AND READING THE PROVIDED DOCUMENTS.

ACKNOWLEDGEMENTS

I WOULD LIKE TO SINCERELY THANK ALL THE OFFICIALS OF THE ROLLING MILLS SECTION OF MECON LIMITED (A GOVERNMENT OF INDIA ENTERPRISE) FOR THEIR GENEROUS AND AVID CONTRIBUTION TOWARDS MY KNOWLEDGE IN THE SUBJECT WHICH WAS COMPLETELY NEW TO ME. BECAUSE OF THEIR CONTRIBUTION, AT THE END OF THE TRAINING I HAVE BEEN ABLE TO GAIN ATLEAST THE BASICS OF COLD ROLLING AND HYDRAULICS, AND ALSO SOME KNOWLEDGE OF THE NATURE AND TYPE OF WORK ACCOMPLISHED HERE IN MECON LIMITED.

OVERALL THIS LEARNING EXPERIENCE IN MECON LIMITED PROVIDED ME WITH AN IDEA OF THE CHALLENGES FACED BY THE ENGINEERS IN PROFESSIONAL LIFE AND AS A MATTER OF FACT TAUGHT ME THAT EVEN AN IOTA OF NEGLIGENCE BY THE ENGINEERS CAN CAUSE GREAT HAZARDS DURING UPCOMING PROCESSES AND SO THE JOB OF AN ENGINEER IS THAT OF GREAT RESPONSIBILITIES.

REMARKS:

CONTENTS

TOPIC PAGE NO.

1) THE TRAINING ORGANISATION 5

2) COLD ROLLING MILLS 6

3) TYPES OF COLD ROLLING MILLS7

4) COLD ROLLING 8

5) PROCESS FLOW 9

6) REVERSING VS TANDM MILLS 10

7) ANNEALING 11-12

8) SKIN PASSING 13

9) HYDRAULICS 14-15

10) CONCLUSION 16

THE TRAINING ORGANISATION

MECON LIMITED, FORMERLY KNOWN AS (METALLURGICAL & ENGINEERING CONSULTANTS (INDIA) LIMITED) IS A PUBLIC SECTOR UNDERTAKING UNDER THE MINISTRY OF STEEL OF THE GOVERNMENT OF INDIA. IT BEGAN IN 1959 AS THE CENTRAL ENGINEERING AND DESIGNING BUREAU (CEDB) OF THE HINDUSTAN STEEL LIMITED (HSL), THE FIRST PUBLIC SECTOR STEEL COMPANY. SUBSEQUENTLY, CEDB GREW AS METALLURGICAL AND ENGINEERING CONSULTANT (MECON), A SUBSIDIARY OF THE STEEL AUTHORITY OF INDIA LIMITED (SAIL) IN 1973. IT LATER BECAME AN AUTONOMOUS COMPANY REPORTING TO THE MINISTRY OF STEEL IN 1978. 1 APRIL IS OBSERVED AS FOUNDATION DAY IN MECON.

MECON LTD. IS A GOVERNMENT OF INDIA ENTERPRISE WHICH BASICALLY ACTS AS A HOUSE OF ENGINEERS WHO ASSIST VARIOUS STEEL MAKING COMPANIES IN SETTING UP THEIR RESPECTIVE PLANTS AT PARTICULAR LOCATIONS FOR A GIVEN REQUIRED PRODUCTION OF STEEL.

IT IS THE RESPONSIBILITY OF THE ENGINEERS OF MECON LTD. TO ENSURE THAT ALL THE EQUIPMENTS, LAYOUTS AND OTHER DESIGN RELATED INFORMATION SENT BY THE CONTRACTOR WHO HAS TAKEN UP THE WORK, ARE COMPLETELY UP TO THE MARK AND ARE LIABLE ENOUGH TO BE INSTALLED IN THE STEEL PLANT.

THE WORK ENVIRONMENT IS EXTREMELY SUITABLE WITH STATE-OF-THE-ART FACILITIES FOR ALL THE EMPLOYEES AND THROUGHOUT THE TRAINING PERIOD ALL THE ASSIGNED ENGINEERS WERE VERY CO-OPERATIVE AND PROVIDED ALL THE REQUIRED INFORMATION IN APPROPRIATE MANNER.

COLD ROLLING MILLS

PROCESS BY WHICH HOT ROLLED STRIP OR STOCK IS INTRODUCED BETWEEN ROLLERS AND THEN SQUEEZED OR COMPRESSED TO THE DESIRED THICKNESS.

AMOUNT OF STRAIN INTRODUCED DETERMINES THE PROPERTIES OF THE FINISHED PRODUCT

WHY IS COLD ROLLING DONE?

GOOD FORMABILITY SUPERIOR SURFACE FINISH REASONABLE STRENGTH CLOSE DIMENSIONAL TOLERANCE.

IN THIS TYPE OF ROLLING MILL THE ROLLING PROCEDURE IS CARRIED OUT AT NORMAL TEMPERATURES AND NOT AT ELEVATED TEMPERATURES. ALSO UNLIKE HOT ROLLING, THE CHANGE IN THE WIDTH IS ZERO.

COLD ROLLING MILLS ARE BASICALLY OF TWO TYPES

IN COLD ROLLING WE ATTAIN A REDUCTION OF ABOUT 30%-35% PER STAND AND AN OVERALL REDUCTION OF ABOUT 88%-90% IS ATTAINED IN THE PROCESS.WHEN THE PRODUCT PASSES THROUGH THE PHASE OF HOT ROLLING ITS TEMPERATURE IS VERY HIGH. SO AS IT GETS IN CONTACT WITH THE ATMOSPHERIC AIR, THE OXYGEN REACTS WITH Fe AND FORMS SCALES (Fe2O3). IN ORDER TO TREAT THE PRODUCT THEREAFTER AN INTERMEDIATE STEP KNOWN AS PICKLING IS NECESSARY.

PICKLING:PICKLING BASICALLY IS A SCALE REMOVAL PROCESS IN WHICH THE PRODUCT IS PASSED THROUGH THREE TANKS CONTAINING ACID (5 to 8 % acid) WHICH DISSOLVES THE SCALES AND THEN PASSED THROUGH A RINSING TANK WHICH CONTAINS HOT WATER AND RINSES ACID STAINS(IF ANY) ARE LEFT ON THE PRODUCT. THEN BRUSHING OF THE PRODUCT IS DONE IN ORDER TO FURTHER CLEAN IT AND FINALLY A COATING OF anti rust OIL IS DONE ON IT.

COLD ROLLING:AS DESCRIBED EARLIER IT CAN BE OF TWO TYPES, EITHER REVRSIBLE OR TANDEM, DEPENDING UPON THE REQUIREMENT. THE PAY OFF REEL AND THE DELIVERY TENSION REEL ARE COMMON IN BOTH THE SETUPS.IN REVERSIBLE REEL THERE IS ONLY ONE STAND AND SO THE MATERIAL IS PASSED THROUGH THE SAME STAND AGAIN AND AGAIN UNTIL THE REQUIRED DIMENSIONS HAVE BEEN ATTAINED AND FOR THIS PURPOSE ENTRY TENSION REELS ARE PROVIDED.IN THIS PROCESS THERE IS SIGNIFICANT LOSS OF MATERIALS AT THE ENDS.

WHEREAS IN TANDEM MILLS 4 OR 5 STANDS ARE PROVIDED AND THE MATERIAL PASSES THROUGH THE STANDS ONLY ONCE ANDE FINISHED PRODUCT IS RECEIVED AT THE OTHER END. LOSSES IN THIS MILL ARE NEGLIGIBLE AND ALSO BETTER FINISHED PRODUCT IS OBTAINED. TANDEM MILLS REQUIRE MORE AREA AND INSTALLATION CHARGES AS COMPARED TO THE REVERSIBLE MILLS.

HYDRAULIC FORCE IS APPLIED ON THE BACK UP ROLL WHICH PROVIDES NECESSARY PRESSURE TO ROLL THE WORK PIECE. THE FORCE GETS TRANSFERRED THROUGH THE INTERMEDIATE ROLLS TO THE WORK ROLLS.

PROCESS FLOWINSPECTION,FINISHING,DESPATCH.

THE VARIOUS ROLL TYPES ARE PICTORIALLY DEPICTED AS FOLLOWS:

SIX HI MILL FOUR HI MILL PAIR CROSS MILL

COMPARISON OF REVERSING AND TANDEM MILLS

ANNEALING

WHY ANNEALING IS DONE?

o STEEL COILS ARE HARD AND BRITTLE AFTER COLD ROLLING.

o HAS ELONGATED GRAIN STRUCTURE. o NOT SUITABLE FOR END USE.

STAGES OF ANNEALING

PROCESS OF RELIEVING INTERNAL STRESSES INDUCED DURING COLD ROLLING TAKES PLACE IN THREE STAGES:

1. RECOVERY

PHYSICAL AND MECHANICAL PROPERTIES (HARDNESS, DUCTILITY, ELECT PROP.)WHICH SUFFERED CHANGES AS A RESULT OF COLD WORKING TEND TO RECOVER TO THEIR ORIGINAL VALUES.OCCURS AT THE INITIAL PHASE OF ANNEALING AT LOWER TEMPERATURES.

2. RECRYSTALLIZATION

PROCESS OF NUCLEATION OF NEW STRAINFREE CRYSTALS (GRAINS) WHICH REPLACES ALL DEFORMED CRYSTALS OF THE COLD WORKED MATERIAL.TAKES PLACE AT A TEMPERATURE KNOWN AS RECRYSTALLIZATION TEMPERATURE.

3. Grain Growth

Increase in average size of crystals/grains on further annealing subsequent to the completion of recrystallisation.

Grain size has direct effect on the mechanical properties. Hence it is controlled to achieve optimum properties.

ANNEALING REQUIRES

Heating the cold rolled steel to the recrystallization temperature in an inert atmosphere. Soaking at this temperature for sufficient time for homogenization and necessary changes to occur. Cooling at a predetermined rate

Process Variables:

Temperature, soaking, cooling rate depending on the desired mechanical properties.

SKIN PASSING

WHY IS SKIN PASSING DONE?

TO ACHIEVE THE OPTIMUM MECHANICAL PROPERTIES o TO PREVENT OCCURRENCE OF STRETCHER STRAINS IN

ANNEALED STEELo TO IMPART DESIRED SURFACE FINISH - “MATTE” ON THE

STRIP SURFACEo TO IMPROVE STRIP SHAPE

WHAT ARE STRETCHER STRAINS?

Generated due to the yield point phenomenon exhibited by cold rolled and annealed low carbon steel sheet/strip. Appear as discrete bands on the strip surface.

HYDRAULICS

THE ROLLING MILLS SECTION IN THE STEEL PLANT IS BY FAR THE MOST TECHNOLOGICALLY ADVANCED SECTION BECAUSE AS FINISHED PRODUCT IS DIRECTLY PROVIDED BY THE ROLLING MILLS, THE TOLERANCE OF VARIOUS EQUIPMENTS INSTALLED IS VERY LESS AND NEGLIGIBLE AS COMPARED TO EQUIPMENTS IN THE OTHER SECTIONS.

THEREFORE MECHANICALLY CONTROLLED SYSTEM WOULD NOT BE AN IDEAL OPTION FOR OPERATING THE EQUIPMENTS AS MECHANICALLY CONTROLLED EQUIPMENTS WOULD PROVIDE LESS EFFICIENCY, WOULD REQUIRE FREQUENT AND EXPENSIVE MAINTENANCE. THOUGH THE HYDRAULICALLY CONTROLLED SYSTEM REQUIRES MAINTENANCE BUT THERE IS NO EFFECT ON THE PRODUCTION DUE TO THAT DURING THE MAINTENANCE PERIOD.

HENCE NOWADAYS THE HYDRAULICALLY CONTROLLED SYSTEM IS BECOMING MORE AND MORE POPULAR IN ALL THE SECTORS.

HERE, I LEARNED ONLY THE BASICS OF A HYDRAULIC CIRCUIT THAT IS USED TO EQUIP A CYLINDER PISTON SYSTEM.

THE FEW COMPONENTS THAT I CAME ACROSS WERE AS FOLLOWS:

DIRECTION CONTROL VALVE:

THIS VALVE CAN BE DESIGNED IN VARIOUS TYPES DEPENDING UPON THE REQUIREMENT. ITS BASIC NEED IS TO CHANGE THE FLOW DIRECTION OF THE WORKING FLUID IN ORDER TO MAINTAIN CONTINUITY IN THE WORKING OF THE SYSTEM AND TO ENSURE THAT THE FLOW DIRECTION OF THE FLUID IS IN THE PATH AS REQUIRED BY THE CIRCUIT.

CHECK VALVE:

ITS BASIC NEED IS TO PREVEN THE WORKING FLUID FROM FLOWING BACKWARDS IN THE CIRCUIT TOWARDS THE PUMP.

PUMPS:

PUMPS ARE PRACTICALLY OF MANY TYPES BUT AS EXPLAINED TO ME; HERE THEY ARE BROADLY CLASSIFIED AS POSITIVE DISPLACEMENT PUMP AND NON POSITIVE DISPLACEMENT PUMP.

IN A POSITIVE DISPLACEMENT PUMP THE SEALING BETWEEN THE INNER VEIN, PLUNGER OR PISTON AND THE OUTER SHELL IS VERY FIRM SO THAT THE INPUT FLUID IS EQUAL TO THE OUTPUT FLUID OF THE PUMP AND IT SUFFERS NO LOSSES.

WHEREAS IN A NON POSITIVE DISPLACEMENT PUMP SUCH AS IN A CENTRIFUGAL PUMP, THE PUMP SUFFERS FLUID LOSES BECAUSE OF POOR SEALING. THIS TYPE OF PUMP IS CHEAPER AS COMPARED TO A POSITIVE DISPLACEMENT PUMP.

BUT IN A HYDRAULIC CIRCUIT ONLY POSITIVE DISPLACEMENT PUMPS ARE PREFERRED.

SUCTION COMPENSATOR:

A SUCTION COMPENSATOR BASICALLY ABSORBS THE VIBRATIONS GENERATED BY THE PUMP OR WHICH EVER PORTION IT DEALS WITH SO AS TO PREVENT ANY DAMAGE TO THE CIRCUIT.

ACCUMULATOR:

ITS USE IS TO ENSURE THAT THE CIRCUIT IS ALWAYS WORKING EVEN IF THERE IS NO POWER SUPPLY FOR SOME TIME IN THE MOTORS.

CONCLUSION

THE PROJECT REPORT CONSTITUTES ALL THE BASIC KNOWLEDGE AS RECEIVED DURING THE 2 WEEKS IN ROLLING MILLS SECTION OF

MECON LIMITED, RANCHI. ALL POSSIBLE EFFORS HAVE BEEN MADE TO PROVIDE LEGITIMATE INFORMATION IN THE REPORT BUT A

KIND CONSIDERATION IS EXPECTED FROM THE READERS IN CASE ANY INEVITABLE ERROR MIGHT HAVE CREPT IN.

THE SUPPORT AND GUIDANCE OF ALL THE OFFICIALS DESPITE THEIR OWN WORKLOAD THROUGHOUT THE COMPLETION OF THE

REPORT IS HIGHLY COMMENDABLE AND APPRECIATED FROM THE STUDENT'S END.

THANK YOU.