Steel Rolling: Principle, Process & Application

Description

This book covers all aspects and elements of rolling technology in one volume with even the most technical jargon being communicated in an easy to understand language. The book is exhaustive as topics ranging from rolls, rolls cooling, roll turning, roll reclamation, investigation of roll breakage, roll management and roll bearing all have been dealt in detail as these constitute the most important element of production cost. A separate chapter has been dedicated to operational management of a rolling mill, which includes safety and inventory. Packaging of the finished products and modern operating mill practices and technologies are also discussed in detail. This book will be a useful tool for shop floor personnel and for all senior management operating in the rolling mill industry; it is also a must read for all polytechnic / engineering students of metallurgical / mechanical / process engineering. This book may also be useful as reference book for students/professionals of rolling technology. Note: T&F does not sell or distribute the Hardback in India, Pakistan, Nepal, Bhutan, Bangladesh and Sri Lanka. Cover Half Title Title Page Copyright Page Dedication Page Preface Acknowledgement Brief Contents Detailed Contents 1. Roll Pass Design 1 Introduction 2 Roll Pass Design 2.1 Object of Roll Pass Design 2.2 Basic Purpose of Roll Pass Design 2.3 Characteristics of Efficient Roll Pass Design 2.4 Specified Conditions Under Which Roll Pass Design is Based Upon 2.5 Constraints to Efficient Roll Pass Design 3 Characteristics of Hot Rolling 3.1 Draft/Draught 3.2 Elongation 3.3 Spread 3.4 Types of Spread 3.5 Computation of Spread 3.6 Contact Area, Contact Angle, Angle of Bite and Roll Bite Condition 3.7 Methods to Improve Roll Biting Conditions 3.8 Forward Slip, Neutral Plane and Neutral Angle 3.9 Forward Slip in Groove Rolls 3.10 Tension 3.11 End Thrust 3.12 Mill Spring 4 Pass 4.1 Type of Passes 4.2 Classification of Passes 4.3 Elements of Passes 4.4 Neutral Line of the Pass 5 Diameter of Rolls 5.1 Average Diameter 5.2 Redressing Co-efficient 5.3 Roll Collars 5.4 Determination of Rolling Diameter 5.5 Pitch Line, Line of Rolling 5.6 Top and Bottom Pressure (Over or Under Draught) 6 Distribution of Draught In A Pass 6.1 Principle of the Distribution of Draught 6.2 Maximum Reduction 7 Roll Pass Design for Non-Uniform Deformation 7.1 Analysis of Non-Uniform Deformation 7.2 Computation of Draught In Non-Uniform Deformation 8 Characteristics of Rolling in Flanged Shapes 8.1 Direct and Indirect Draught 8.2 Effect of Taper 8.3 Effect of Friction 8.4 Speed of Rolling in Flange Profile 8.5 Asymmetry of Deformation in a Flange Pass 8.6 Stages of Rolling in a Flange Pass 8.7 Distribution of Draught Among the Elements of Flanged Profile 8.8 Features of Deformation in a Closed Web-Cutting Pass 9 Consideration for Design of Finishing Passes 9.1 Co-efficient of Expansion 9.2 Rolling with Negative Allowance 10 Specific Feature of Roll Pass Design of A Continuous Mill 11 Computation of Power Requirement 11.1 Rolling Load 11.2 Power Requirement and Rolling Torque 11.3 Factors Deciding The Size and Type of Main Drive Motor 11.4 Factors Affecting Rolling Load 2. Mechanical Working and Rolling Process 1 Introduction 2 Hot and Cold Working 3 Theory of Microscopic Plasticity 4 Methods of Metal Working 5 Allotropy of Iron 6 Iron-Carbon Diagram 7 Transformation in steel 7.1 Transformation in Eutectoid Steel 7.2 Transformation in Hypo Eutectoid Steel 7.3 Transformation in Hyper Eutectoid Steel 7.4 Critical Temperature 8 The Effects of Various Elements on Plastic Properties of Steel 9 The Effect of Rolling on Grain Structure 10 Defination and Classification of Thermo-Mechanical Processing 11 Quenched and Self-Tempered Rebars (Qst) 12 Stages of Quenching and Self-Tempering Cycle 12.1 First Stage 12.2 Second Stage 12.3 Third Stage 13 Main Equipments of TMT Process 14 Different Metal Forming Operations 15 Rolling 15.1 History of Rolling 15.2 What is Rolling 15.3 Methods of Rolling 16 Classification of Products 16.1 General Purpose Rolled Sections 16.2 Special Purpose Rolled Section 16.3 Main Categorization of Rolled Products 17 Classification of Rolling Mills 17.1 Classification as per Number of Rolls 17.2 Classification as per Nos. of Drives in the Mill 17.3 Classification as per Products Rolled 17.4 Classification As Per Layout 17.5 Continuous/Non-continious Rolling Mill 17.6 Classification wrt Direction of Rolling 18 Special Types Mill 18.1 Double Duo Mill 18.2 Sandzimar Planetary Mill 19 Determination Of Mill Size 19.1 Where Rolls are Individually Driven 19.2 Where Rolls are Driven by Single Motor Through Pinion Stand 19.3 Flat Rolling 3. Rolls, Roll Cooling and Roll Management 1 Introduction 1.1 There are Three Parts in a Roll, Namely 2 Classification of Rolls 2.1 Classification wrt Purpose 2.2 Classification wrt Specific Duty 3 Rolls Qualities 3.1 Effect of Alloying Elements in Iron and Steel Rolls 3.2 Effect of Casting Practice 3.4 Quality Classification of Rolls 4 Cast Iron Rolls 4.1 Grain Rolls 4.2 Clear or Definite Chill Rolls (CCCI) 4.3 Indefinite Chill Cast Iron Roll (ICCI) 4.4 Spheroidal Graphite Rolls (SGCI) 4.5 Double Poured or Composite Iron Rolls 5 Steel Rolls 5.1 Forged Steel Rolls 5.2 Cast Steel 6 Cementite Carbide Roll (Rings) 7 Sleeve Roll 8 Selection of Rolls for different category of Rolling Mills 8.1 Blooming and Slabbing Mills 8.2 Structural Mill 9 Proper Care of Rolls 9.1 Care During Design 9.2 Proper use During Rolling 9.3 Care of Roll by Mill Crew 9.4 Care to Avoid Over Loading 9.5 Other Precautions 10 Proper Cooling of Rolls 10.1 Methodology of Wear-Out 10.2 Factors Affecting Wear-Out of Rolls 10.3 What is Proper Roll Cooling 10.4 Conventional Roll Cooling 10.5 Effective Roll Cooling System 10.6 Roll Cooling Parameter 10.7 Basic Requirements of Effective Roll Cooling System 11 Roll Management 11.1 Objective of Roll Management 11.2 Roll Inventory 11.3 Proper Layout of the Shop 11.4 Investigation of Roll Failures 12 Reclamation of Rolls 12.1 Automatic Submerged Arc Welding 12.2 Factors Affecting the Building up of Roll 12.3 Pre-heating of Rolls 12.4 Post heating or Stress Relieving of Rolls 12.5 Process of Arcing 12.6 Welding Machine 12.7 Welding Head 12.8 Fluxes 12.9 Preparation of the Job for Weld Deposition 12.10 Welding of Rolls 12.11 Defects of Welding 13 Roll Bearings 13.1 Open Journal Bearing 13.2 Roller Bearing 13.3 Enclosed Oil Film Bearing 4. Rolling of Blooms and Slabs 1 Introduction 2 Ingot 2.1 Classification of Ingot 2.2 Selection of Dimensions and Design of Ingot 3 Mill Proper 3.1 Layout 3.2 Roll Stand 3.3 Stand Housing 3.4 Rolls for Primary Mill 3.5 Selection of Rolls for Primary Mill 3.6 Bearing for Primary Mill 3.7 Top Roll Adjustment System 3.8 Spindles for Primary Mill 3.9 Roll Speed 3.10 Main Drives of Motor 3.11 Roll Tables, Manupalaters of Mill 3.12 Shears for Primary Mill 3.13 Scale Disposal for Mill 4 Comparative Study of Blooming Mills 5 Roll Pass Design for Blooming Mill 5.1 Pattern of Reduction 5.2 Arrangement of Grooves in Blooming Mills Rolls 6 Types Of Passes used In Blooming Mills 7 Size and Shape of Pass 7.1 Height of Pass (H) 7.2 Width of Pass 7.3 Taper 7.4 Corner Radii 7.5 Pass Convexity 7.6 Roll Collars 8 Bottom Pressure 9 Turning of the Workpiece 10 Roll Pass Design Data Sheet of Blooming Mills 10.1 Rolling Schemes for Rolling Different Size of Blooms/Beam Blanks 11 Pass Design of Blooming Mill 11.1 Barrel or Bullhead Pass 11.2 First Pass 11.3 Second or Finishing Pass 11.4 Beam Blank 12 Defects in Bloom Rolling 12.1 Defects due to Rolling 12.2 Defects due to Steel 12.3 Defects due to Bad Heating Practice 5. Rolling of Billets 1 Introduction 2 Types of Mill and General Layout 2.1 Open Train Billet Mill 2.2 Cross Country Billet Mill 2.3 Continuous Billet Mill 3 Specific Features of Continuous Mill 3.1 Advantages of Individually Driven Stand Over Group Combined Driven Stand 4 Pass Design Details of Billet Mill 4.1 Open Box Pass 4.2 Diamond-Diamond System 4.3 Diamond-Square Sequence 4.3.1 Advantages of Diamond-square System 4.3.2 Disadvantages of Diamond-Square Sequence 4.4 Oval-Square System 4.4.1 Advantages of Oval-square System 4.4.2 Disadvantages of Oval-square System 5 Selection of a Pass Sequence 6 Comparative Study of Billet Mills 7 Layout of Continuous Billet Mill 8 Roll Pass Design of Billet 90 mm × 90 mm 8.1 Details Regarding Input Bloom and Finished Product 8.2 Details Regarding Mill 8.3 Tolerance of Billet 8.4 Computation of Reduction 8.5 Roll Pass Design of Finishing Group 8.6 Roll Pass Design of Roughing and Intermediate Group 8.7 Rolling Scheme of Billet 90 × 90 mm From Bloom 325 × 325 mm with Intermediate Size of 150 × 150 mm 9 Defects in Billet Rolling 9.1 Defects Due to Bad Rolling 6. Rolling of Rounds and TMTS Bars 1 Introduction 2 Selection of Rolling Sequence 2.1 First Method 2.2 Second Method 2.3 Third Method 2.4 Fourth Method 2.5 Fifth and Sixth Method 2.6 Seventh, Eighth, Ninth and Tenth System 3 Rolling Tolerances of Rounds as per BIS Specification 3.1 On Size of Round 3.2 Ovality or Out of Square 3.3 Weight 4 Design of Passes 4.1 Design of Finishing Pass 4.1.1 Height of Finishing Pass 4.1.2 Width of Pass 4.1.3 Roll Gap 4.1.4 Radius of Finished Pass 4.2 Design of Pre-finishing Oval Pass 4.2.1 Height of Oval 4.2.2 Width/Height Ratio of Oval Pass 4.2.3 Radius of oval 4.2.4 Outer radius r of Oval Pass 4.2.5 Area of Oval Pass 4.3 Design of Strand Pass 4.3.1 Strand Plug oval/edge Oval 4.3.2 Strand Square 4.3.3 Strand Round 4.4 Design of Following Passes in Rolling Sequence 5 Rolling Scheme of Round–32 mm 6 Roll Pass Design R-32 mm 6.1 Stand-12 (Finishing Pass) 6.2 Pass-11 (Pre-finishing Pass) 6.3 Pass-10 (Strand Pass) 6.4 Pass-8 (Rd-32-36 Pass) 6.5 Pass-6 (Rd-32-36 Pass) 6.6 Pass-4 (Rd-32-36 Pass) 6.7 Roll Design of Finishing Pass 6.8 Roll Design of Pre-finishing Pass 6.9 Roll Design of Strand Pass 7 Layout of Merchant Mill 8 Rolling of TMT Bars 8.1 Process of TMT 8.2 Comparison of Different TMT Grades 8.3 The Effect of Carbon Equivalent on Weldability 8.4 Rib Design 8.5 Control Data for Thermo Mechanically Treated Wire Rods/Bars 8.6 Roll Pass Design of TMT-32 9 Olling Defects and its Solution 9.1 Ovality 9.2 Diagonal Difference 9.3 Fin 9.4 Under-Filled 9.5 Fish-tail 9.6 Lap 9.7 Worn out Mark 9.8 Pipe Formation in TMT 9.9 Pass Mark 10 Mill Setting of Rounds/TMTS 10.1 Twisting 10.2 Bending of Bars (Side Ways) 10.3 Bend up and Down 10.4 Slipping in Stands 10.5 Rolling Scheme 10.6 Pass Positioning and their Dimensions 11 Major Points during Rolling 11.1 Setting of Roughing group 11.2 Setting of the Intermediate Group 11.3 Setting of The Finishing Group 12 Slit Rolling of Bars 12.1 Why Slitting is Required 12.2 Sections Produced by Slit Rolling 12.3 The Process of Slitting 12.4 Control of Loop Heights between Stands 4 and 5 and 5 and 6 12.5 Method of Slitting 12.6 Slitting and Slit Guide 12.7 Problems Faced During Slit Rolling and its Solutions 13 Mill Setting problem during Slitting 13.1 Rib Height below Tolerance on Both the Top and Bottom of The Bar 13.2 Rib Height Below Tolerance on Either the Top or Bottom of the Bar 13.3 Oval With Unequal Fill Due to Misalignment of the Entry Guide 13.4 Small Kinks Every 1 to 1.2 m 13.5 Lap 13.6 Variations in Filling Between Strands 7. Rolling of Flats and Squares 1 Introduction 2 Selection of Rolling Sequence for Rolling Flats 3 Roll Pass Design for Flat 50 × 12 – 16 mm 3.1 Selection of Mill, in which section is to be rolled 3.2 Customer’s Requirement wrt Specification, Tolerance etc. 3.3 Rolling Scheme for Flat 50 × 12 & 50 × 16 3.4 Pass Design of Flat 50 × 12 & 50 × 16 mm 3.5 Design of Pre-finishing Pass (Pass-11-Vertical Stand-Edging Pass) 3.6 Pass-7 (Vertical Stand-Intermediate Group) 4 Mill Setting and Section Control 5 Inspection and checking of dimensions of flat sections 6 Defects and its Rectifications 6.1 Round Edges (convex) 6.2. Concave Edges 6.3 Dished 6.4 Dished and Convexed 6.5 Wedge 6.6 Opposite Diagonals Rounded 6.7 Rhomboid 6.8 Sticker Mark – Due to Sticking of Metal on the Edger 6.9 Wear out Mark on Top and Bottom Edges– Due to Worn out Flat Pass or Edger. 6.10 Lap– due to Fin from edger. 6.11 Diagonal Difference 7 Rolling of Spring Steel Flats 8 Guides used in Flat Rolling 8.1 Entry Guide 8.2 Delivery Guide 9 Rolling of Squares 10 Selection of Rolling Sequence for Rolling Square 11 Roll Pass Design of Square–50 mm 12 Rolling Scheme for Square 13 Defects and its Rectifications 13.1 Overfill 13.2 Under Fill 13.3 Lap 13.4 Offsquare 8. Rolling of Angles 1 Introduction 2 Types of System used for Angle rolling 3 Selection of Rolling System 4 Salient Features of Rolling Angle 4.1 Selection of Mill Size 4.2 Design of Finishing Pass 4.3 Computation of the Size of Billet 4.4 Co-efficient of Deformation 5 Modern Method of Rolling Angles 5.1 Roll Pass Design of Equal Angle 5.2 Selection of Mill 5.3 Customer’s Requirement wrt Specification, Tolerance etc. 6 Pass Design of Angle 55 × 55 × 6 mm 6.1 Design of Finishing Pass 6.2 Computation of Thickness of other Passes of Angle Rolling 6.3 Pre-finishing Pass (Stand -10) 6.4 STRAND PASS (Stand-09) 6.5 Intermediate Group 6.6 Roughing Group 7 Rolling Computation Sheet for Angle 55 × 55 × 6 mm 8 Roll Pass Design of Unequal Angles 8.1 Design of Finishing Pass 8.2 Determination of Sizes of other Passes 8.3 Computation of Prefinishing Pass 9 Mill Setting of Angle Rolling 9.1 Setting of Roughing and Intermediate Stands 9.2 Setting of Finishing Stands and Profiles for Angle Rolling 10 Defects and its Rectification 9. Rolling of Channels 1 Introduction 2 Methods of Pass Design 2.1 Conventional Method of Rolling Channel 2.2 Modern Method of rolling Channel 3 Salient Feature of Channel Pass Design 3.1 Draughting 3.2 Work Feature 3.3 Fillets 3.4 False or Counter Flange 3.5 Profile Radii 3.6 Spread in Channel Rolling 3.7 Pitch Line Location 3.8 Condition of Entry of Strip Into Pass 3.9 Guides Used in Channel Rolling 4 Roll Pass Design for Channel 100 × 50 mm 4.1 Selection of Mill 4.2 Customer’s Requirement wrt Specification, Tolerance etc. 4.3 Selection of Billet 4.4 Determination of Co-efficient of Reduction for the Different Elements of Channel Design 5 Computation of Elements of Pass Design 5.1 Design of Finishing Pass 5.2 Pre-finishing Pass (Pass-10) 5.3 Strand Pass (Pass-9) 5.4 Pass-8 5.5 Pass-6 5.6 Pass-5 5.7 Pass-3 5.8 Pass-2 5.9 Stand-1 6 Mill Setting of Channel 7 Defects of Channels and its Rectification 10. Rolling of Beam 1 Introduction 2 Methods of Beam Design 2.1 The First Method 2.2 Second Method 2.3 Third Method 2.4 Fourth Method 3 Mill Layout 3.1 Conventional Rail & Structural Mill 3.2. Universal Rail and Structural Mill 3.3 Continuous Combined Bar and Structural Mill 4 Special Features of Beam Design 5 Important considerations for Roll Pass Design of Beam 5.1 Selection of Bloom Size and Numbers of Passes 5.2 Advantage of using Beam Shaped Bloom/Billet 5.3 Elements of Beam Section 5.4 Draughting Strategy for Beam Design 5.5 Spread 5.6 Flange Design 5.7 Buckling of Web 5.8 Fillets 5.9 Thrust 6 Roll Pass Design of Beam 125 × 70 mm 6.1 Selection of Mill 6.2 Customer’s Requirement wrt Specification, Tolerance etc. 6.3 ISMB–Details of Specification as Per BIS 6.4 Design of Finishing Pass 6.5 Selection of Billet 6.6 Determination of Co-efficient of Reduction for the Different Elements of Beam Design 7 Computation Sheet for Beam 125 × 70 MM 7.1 Computation Sheet for Flange 7.2 Computation for The Web 7.3 Computation for Pass height, Pass Area 8 Pass Design of Beam 125 × 70 8.1 Pass Design of Finishing Stand (12th) 8.2 Design of Pre-finishing Stand (10th) 8.3 Design of Strand Pass (9th) 8.4 Intermediate Group (Stand-8) 8.5 Intermediate Group (Stand-6) 8.6 Design of Pass-5 8.7 Design of Pass-3 8.8 Design of Pass-2 (“V”Pass) 8.9 Design of Pass -1 9 Rolling Scheme for Beam 125 × 70 10 Mill Setting of Beam 11 Control of Weight of Beam Section 12 Special Precaution is to be taken during Beam Rolling 13 Defects of Beam and its rectification 11. Rolling of Rail 1 Introduction 2 Development Trends 3 Rail Shaping Practice 3.1 Conventional System 3.2 Basics of Rail Design 4 Salient Features of Rail Pass Design 4.1 Draughting 4.2 Design Efficiency 4.3 Roughing Pass Design 4.4 Combination Rolls 4.5 Proper Pass Distribution 4.6 Size of Bloom 4.7 Rolling Temperature 4.8 General Consideration 4.9 Mill Setting 4.10 Diagonal Rolling 4.11 Bearing Collars 4.12 Roll Spring 4.13 Roll Diameter 5 Conventional Rail and Structural MilL 5.1 Rail Specification 5.2 Layout of Rail and Structural Mill 5.3 Details of Equipments: Mill and Furnace 5.4 Details of Major Equipments in Finishing Area 5.5. Welding 6 Rail Testing 7 Roll Pass Design for RAIL 7.1 Rolling Scheme of Roughing line 7.2 Rolling Scheme of Finishing Line 7.3 Pass Design of Individual Pass in Finishing Line 7.4 Computation Sheet for Rail Design 7.5 Graph for computation of Co-efficient of Reduction 8 Universal Roll Pass Design 8.1 Advantages of Shaping in Universal Pass 8.2 Mill Configuration with Universal Rolling Practice 8.3 Layout of Finishing Line 9 Defects and Its Rectifications 9.1 Steel Defects 9.2 Mill Defects 9.3 Finishing Defects 12. Operation, Safety and Quality Management 1 Operation Management 1.1 Principal Elements of the Operation Management 1.2 Technological Instruction on Preparation of Rolls and Rolling in Light Structural Mill 1.3 Precautions to be Taken During Roll Changing 1.4 Points/areas to be Checked after Roll Changing 1.5 Starting the Mill After Major Roll Changing 1.6 Examination of the Finished Products 1.7 Technical and Economical characteristics of Rolled Metal Production 2 Safety Management of Rolling Mill 2.1 Accident Prevention Regulations in the Rolled Metal Production 3 Quality Management in Rolling Mills 3.1 Quality concept of Products 3.2 Reliability, Availability and Maintainability of Products 3.3 Rolled Product Quality Control 3.4 Quality Control in the Production of Rolling Products 3.5 Requirement of TMT Rolling 13. Packaging of Steel Products 1 Introduction 2 Objective 3 Concepts of Packaging 3.1 Role of Packaging 3.2 Theoretical Aspects of Packaging 3.3 Approach to Packaging Design 3.4 Importance of Steel Product Packaging 3.5 Advantages of Packaging of Steel Products 4 Packaging of Long Products 4.1 Piling 4.2 Bundling 4.3 Binding 14. Energy Efficient Practices and Technologies 1 Introduction 2 Role of Reheating Furnace 2.1 Type of Furnace 2.2 Purpose of Heating Metal for Rolling 2.3 Problem Associated with Heating 3 Operational Energy Efficient Improvement Practices in Furnace and Mill 3.1 Optimal Operation of Combustion System 3.2 Optimization of Thermal Regimes 3.3 Furnace Pressure Regimes 3.4 Hot Charging of Material 3.5 Furnace Productivity 3.6 Hearth Coverage 3.7 Use of Coil Box 3.8 Unfired Preheat Zone 3.9 Recovery of Waste Energy 3.10 Stack Efficiency 3.11 Thermal Cover of Roll Table in the Mill 3.12 Computer/combustion Control Model 3.13 Discharge Temperature 3.14 Using Higher Mill Speed 3.15 Using Bigger Diameter Roll 3.16 Running Mill Concept 3.17 Establishing Communication System Between Furnace and Mill Proper 3.18 Idle Running of the Mill 3.19 Automatic Stoppage of Mill Drives/Roll Tables 3.20 Use of VVVF Drives with Air Blowers and Auxiliaries 4 Use of Energy Efficient Operating Technologies 5 Improvement in The Rolling of Rebar Technology 5.1 Reheating 5.2 Low Temperature Rolling 5.3 Increased Capacity 5.4 Dimensional Tolerances 5.5 Endless Welding and Rolling (EWR) 5.6 Improved Mill Utilization 5.7 Size-free Rolling 5.8 Thermo-Mechanical Treatment (TMT) Process 6 Recent Developments in Production of Structurals 6.1 Size-Free Rolling of H-shapes 6.2 Quenching and Self Tempering (QST) Process for Structural Steel 6.3 Endless Welding and Rolling (EWR) for Structural Steel 6.4 High Precision Rolling (HPR) 6.5 In-line Head Hardening of Rails 6.6 Vanadium Steels Index