SLIT ROLLING MILL

Achieving high production of high premium smaller sizes of TMT bars, utilizing fully the Reheating capacity

MULTI STRAND SLIT ROLLING

The dogbone, slit, finishing stands rolled through ‘Size Stabiliser Housing less Stands’, through multi strand ‘Controlled Cooling Bar Tempering system’, cut by ‘Wide Blade Flying Shear’ conveyed & braking through ‘ Lifting Apron Type entry roller table & ‘ Walking Beam Cooling Bed’ with inbuilt ‘Layer transfer system’

ADVANTAGE
  • 15% Power saving for slit sizes, since the cross section area rolled is in multiple of strands.
  • Fuel saving, as the furnace discharge temperature can be reduced by 40degC, as speed of rolling in roughing & intermediate stands is higher, the material gets heated during rolling.
  • Four nos. less nos. of total stands for four slit, Less roll consumption per ton.
EXAMPLE TO KNOW HOW THE ROLLING MILL CAPACITY IS DECIDED

Suppose these are the technical specifications for a mill (250,000 TPA) We have explained How to Calculate the production for such a mill.

SPECIFICATION
Basic Raw Material M.S Billets
130 x 130 mm x 6000 mm (760 Kgs.)
130 x 130 mm x3000mm (380) Kgs.)
Finished Products Rounds ;
Re-bars
Size 8 mm dia to 40 mm dia.
AS LONG PRODUCTS ON COOLING BED
Mill Automation Complete mill operation is Fully Automatic except discharge after the Cooling bed where manual material handling shall be done.
Production Capacity 250000 TONNES Per Annum.
40/50 Tons/Hr for 6000 running hours
Connected Load 7150 K.W
30 Min. Integrated Max. Demand 5500 KVA

PRODUCTION CAPACITY ASSESSMENT

The Production capacity of these kinds of Mills depend on the finishing speeds of various sections which is given hereunder.

PRODUCT SIZE (DIA – MMS) SECTIONAL WT. KG./MET. FINISHING SPEED METS./SEC.
8 0.395 * 4 Strand 12.00
10 0.617 * 4 Strand 9.00
12 0.888 12.00
16 1.578 9.0
20 5.5
25 3.85 3.5

Production capacity for 8 mm dia bars is taken for basic calculations since this is the smallest size of bars produced on Cooling bed as long products.

Basic Raw material Wt. 760 Kg (average)
Sectional Wt. of 8 mm dia 0.395 *4
Length of 8 mm dia 760/0.395*4 = 481 Mts.
Speed of 8 mm dia rolling 12.00 Mts./sec.
Time taken to roll one piece 481/12.00 = 40 Secs.
Idle time between piece 05 Secs.
Total time taken to roll one piece 40 + 5 = 45 Secs.
Say = 45 Secs.
No. of pieces that can be rolled in One hour 3600/45 = 80 Pieces
Production per hour = 80 x 760 x 0.80 x 0.96 / 1000
- Mill efficiency
- Yield (Minimum)
= 46 .69 TONS Per hour
Say = 45 TONNES PER HOUR

We have calculated the production for the smallest size of 8 mm dia at 12.00mets./sec. speed.
Production capacity for 10 mm dia bars is taken for basic calculations since this is the smallest size of bars produced on Cooling bed as long products.

Basic Raw material Wt. 760 Kg (average)
Sectional Wt. of 10 mm dia 0.617*4
Length of 10 mm dia 760/0.617*4 = 308 Mts.
Speed of 10 mm dia rolling 9.00 Mts./sec.
Time taken to roll one piece 308/9.00 = 34 Secs.
Idle time between piece 05 Secs.
Total time taken to roll one piece 34 + 5 = 39 Secs.
Say = 39 Secs.
No. of pieces that can be rolled in One hour 3600/39 = 92 Pieces.
Production per hour = 92 x 760 x 0.80 x 0.96 /1000
- Mill efficiency
- Yield (Minimum)
= 53.58 TONS Per hour
Say = 50 TONNES PER HOUR
12mmx2 at 12m/s shall yield 50Mt/hr
16mm at 12m/s shall yield 45 Mt/hr
All sizes above 16mm shall yield 50 Mt/hr

ANNUAL PRODUCTION CAPACITY
Total No. of Hours in a day = 24 Hours.
No. of working days in an year = 300 days.
No. of Hours of mill operation = 300 x 24 = 7200 * 0.75 = 5400 HRS.
8 mm dia production about 15 % of total operation. = 810 HRs.
10mm dia production about 30 % = 1620 hrs
Other sizes from 12 to 32 mm = 2970 HRs.
Production of 8 mm dia 15% = 810 x 45 = 36,410 Tonnes.
Production of 10 mm dia 30% = 1620 x 50 = 81,000 Tonnes.
Other sizes from 12 to 32 mm = 2970 x 50 = 148,500 Tonnes.
Total production per year = 265910 Tonnes.
Safely we take the production of 250,000 Tonnes.


ADDRESS

Nav Bharat Engineering Works

C- 233, B.S. Road, Industrial Area, Site-1 Ghaziabad - 201001, Uttar Pradesh, India
+(91) - 8130550265


sales@navbharatengineering.com hr@navbharatengineering.com sparesnbew@gmail.com

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