BP石油公司CASTROL钢板冷轧乳化液技术培训教材资料

• Tandem mill
• • • Offer a once-through continuous process Standard schedules, high volumes Extreme speeds often with accumulators in front and behind the mill so as mill only ‘slows down’ for weld Lowest cost model for production, hence highest risk for trial work
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Rolling Theory
• Leonardo De Vinci proposed principles (1452-1519) • Mangles and pasta sheet rollers adopt the same mechanics
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Rolling Theory -1
Rolls faster than strip
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To Consider…..
• Mill Type – Reversing or Tandem • Work roll - diameter - thermal crown / camber - flattening - force v pressure • Areas of restricted flow • Work hardening and anneal stress relief • (Slip)
Number of Mills 746 351 165 230
325
26 29
Carbon Steel (>1m wide) 85%
Others 8% Stainless Steel (>1m wide) 7%
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Cold Rolling Market Segments
Coolant and Mill Types
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Choice of Mill
Process and commercial
• Single stand
• • Operate in reversing sequences Mixed schedules, lower volumes with longer time to run individual coils through the mill Generally slower speeds typically 600 – 800 m/min Much more flexible applications Often first opportunity for lubricant and material trials
Emulsions 95%
Coolant Type Specific to process: • Carbon Steel Emulsions for cost and high production • Stainless Steel Neat Oil for high surface finish products • Electrical and Special Steels Emulsions or neat oil
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Cold Rolled Steel
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Global Cold Mill Market
•Total Market Value ~ USD 380 million Sales
Market Value M$ 380
Market Sector Total Market Analysed Carbon Steel (>1m wide) Stainless Steel (>1m ENTIAL
4 high Tandem Mill
Entry Side
Exit side
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6 high Configuration
Back up rolls
Intermediate rolls
Work rolls
Roll No2 carries taper
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South Korea India Taiwan AsPac - Other
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Global Cold Market
Technical Drive
• Increase in reductions - higher demand for lighter gauge ; Auto and HDG - efficiency of process demands ; pickle line and CAPL - saving the number of passes on reversing mill - the need for ultra thin or ultra hard materials • Improvements in Strip Cleanliness - exiting strip is either cleaned on route as stand alone process (ECL) or incorporated into continuous process (CAPL) - Cheaper option is “mill clean sheet route” ; where material is only annealed but requires good quality rolling lubricants to anneal clean
- Multi stage mills set up in tandem with first stand feeding the next ( typ 4-6 stands) Up to 2000 m/min
Entry Side
Exit side
- Variable entry gauges ( 3mm max) down to variable exit gauges ; auto sheet @ 0.7mm -Typical reduction per stand / pass @ 25 – 40 % -Typical strip temps on exit up to 130° C
Rolling Theory -2
• Rolling is a progressive reduction at varying speed , of sheet steel thickness , to extend length by applying vertical force load and longitudinal force (tension).
12/20 High Reversing Mill Up to 120,000 t.p.a.
4/6/Z High Reversing Mill Up to 150,000 t.p.a.
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4 high Configuration
-Reversing single stand mills, typical 800 m/min
A
B
The smaller the rolls the smaller the contact area = unit pressure greatest for smaller work rolls
Max reductions = small work rolls
Market Split by Produced Material
Neat Oil 5%
Carbon Steel 89%
Stainless 7% Electrical 2% Special 2%
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Global Cold Market
Regional and Country Split Cold Rolling Market by Major Countries
• • •
•
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Production : Mill Type Cold Rolling Volume - Mill Configurations
Carbon Steel Cold Rolling. 4 or 6 High Mills
Reversing Mill Up to 350,000 t.p.a.
Sendzimir Arrangement – 20 High
Outokompu trial work
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Work Rolls : Force v Pressure
The greater the reduction the larger the contact area = larger area requires greater force to maintain unit pressure
• Rolling is a progressive reduction at varying speed , of sheet steel thickness , to extend length by applying vertical force (load)
Load
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Load
Cold Rolling Master class
Shanghai, July 2011 Rob Hudson
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Who am I ?
• Rob Hudson, Metals Scientist – Europe • Honours degree in Applied Chemistry and Chartered Chemist • Work for I&D metalworking in Monchengladbach Germany • Live in Manchester in the UK