تويت
Cold and Hot Forging – Fundamentals and Applications Edited by Taylan Altan, ERC/NSM, Ohio State University Gracious Ngaile, North Carolina State University Gangshu Shen, Ladish Company, Inc.
Contents
Preface viii
Chapter 1 Metal Forming Processes in Manufacturing .1
1.1 Classification of Manufacturing Processes .1
1.2 Characteristics of Manufacturing Processes 2
1.3 Metal Forming Processes in Manufacturing 4
Chapter 2 Forging Processes: Variables and Descriptions .7
2.1 Introduction .7
2.2 Forging Operation as a System 7
2.3 Types of Forging Processes .9
Chapter 3 Plastic Deformation: Strain and Strain Rate 17
3.1 Introduction . 17
3.2 Stress Tensor 17
3.3 Properties of the Stress Tensor . 18
3.4 Plane Stress or Biaxial Stress Condition 19
3.5 Local Deformations and the Velocity Field 20
3.6 Strains . 20
3.7 Velocities and Strain Rates 21
3.8 Homogeneous Deformation . 21
3.9 Plastic (True) Strain and Engineering Strain . 23
Chapter 4 Flow Stress and Forgeability 25
4.1 Introduction . 25
4.2 Tensile Test 27
4.3 Compression Test 29
4.4 Ring Test . 35
4.5 Torsion Test . 36
4.6 Representation of Flow Stress Data 36
Appendices (CD-ROM only)
4.1 Determination of Flow Stress by Compression Test at Room
Temperature
4.2 Determination of Flow Stress at High Temperature
4.3 Forgeability and Damage Factor in Cold Forging
Chapter 5 Plastic Deformation: Complex State of Stress and
Flow Rules . 51
5.1 State of Stress . 51
5.2 Yield Criteria 52
5.3 Flow Rules 55
5.4 Power and Energy of Deformation . 56
5.5 Effective Strain and Effective Strain Rate 57
Chapter 6 Temperatures and Heat Transfer 59
6.1 Introduction . 59
6.2 Heat Generation and Heat Transfer in Metal Forming Processes 59
6.3 Temperatures in Forging Operations . 60
6.4 Measurement of Temperatures at the Die/Material Interface 60
6.5 Measurement of Interface Heat Transfer Coefficient 62
6.6 Influence of Press Speed and Contact Time on Heat Transfer 64
Appendices (CD-ROM only)
6.1 Upset Forging of Cylinders
Chapter 7 Friction and Lubrication . 67
7.1 Introduction . 67
7.2 Lubrication Mechanisms in Metal Forming 68
7.3 Friction Laws and Their Validity in Forging . 69
7.4 Parameters Influencing Friction and Lubrication . 69
7.5 Characteristics of Lubricants Used . 70
7.6 Lubrication Systems for Cold Forging 70
7.7 Lubrication Systems for Warm and Hot Forging . 73
7.8 Methods for Evaluation of Lubricants . 74
Appendices (CD-ROM only)
7.1 Ring Compression Test
7.2 Double Cup Extrusion Test
Chapter 8 Inverse Analysis for Simultaneous Determination of
Flow Stress and Friction 83
8.1 Introduction . 83
8.2 Inverse Analysis in Metal Forming . 83
8.3 Flow Stress Determination in Forging by Inverse Analysis . 85
8.4 Inverse Analysis for Simultaneous Determination of Flow Stress
and Friction 86
8.5 Example of Inverse Analysis . 86
Chapter 9 Methods of Analysis for Forging Operations 91
9.1 Introduction . 91
9.2 Slab Method of Analysis 93
9.3 Upper Bound Method and Its Application to Axisymmetric
Upsetting . 97
9.4 Finite Element Method in Metal Forming 98
Chapter 10 Principles of Forging Machines .107
10.1 Introduction .107
10.2 Interaction between Process Requirements and Forming Machines
10.3 Load and Energy Requirements in Forming .108
10.4 Classification and Characteristics of Forming Machines .110
10.5 Characteristic Data for Load and Energy .111
10.6 Time-Dependent Characteristic Data 112
10.7 Characteristic Data for Accuracy .112
Chapter 11 Presses and Hammers for Cold and Hot Forging .115
11.1 Introduction .115
11.2 Hydraulic Presses .115
11.3 Screw Presses 131
11.4 Hammers 135
Chapter 12 Special Machines for Forging 141
12.1 Introduction .141
12.2 Transverse or Cross-Rolling Machines .142
12.3 Electric Upsetters .142
12.4 Ring-Rolling Mills 143
12.5 Horizontal Forging Machines or Upsetters 144
12.6 Rotary or Orbital Forging Machines .145
12.7 Radial Forging Machines .145
Chapter 13 Billet Separation and Shearing 151
13.1 Introduction .151
13.2 Billet and Sheared Surface Quality 151
13.3 Shearing Force, Work, and Power 154
13.4 Shearing Equipment 154
Chapter 14 Process Design in Impression Die Forging .159
14.1 Introduction .159
14.2 Forging Process Variables 160
14.3 Shape Complexity in Forging .164
14.4 Design of Finisher Dies .165
14.5 Prediction of Forging Stresses and Loads 169
14.6 Design of Blocker (Preform) Dies .171
Appendix A Example of Load for Forging of a Connecting Rod .177
A.1 Introduction 177
A.2 Estimation of the Flow Stress 178
A.3 Estimation of the Friction Factor 181
A.4 Estimation of the Forging Load 181
A.5 Comparison of Predictions with Data from Actual Forging Trials .181
Appendices (CD-ROM only)
14.1 Preform Design in Closed Die Forging
14.2 Flash Design in Closed Die Forging
Chapter 15 A Simplified Method to Estimate Forging Load in
Impression-Die Forging 185
15.1 Introduction .185
15.2 Effect of Process ParamAppendices (CD-ROM only)
15.1 ForgePAL: A Computer Program for Estimating Forces in
Hot Forging with Flash
Chapter 16 Process Modeling in Impression-Die Forging Using
Finite-Element Analysis 193
16.1 Introduction .193
16.2 Information Flow in Process Modeling .194
16.3 Process Modeling Input .194
16.4 Characteristics of the Simulation Code .196
16.5 Process Modeling Output .197
16.6 Examples of Modeling Applications 200
Chapter 17 Cold and Warm Forging .211
17.1 Introduction .211
17.2 Cold Forging as a System 213
17.3 Materials for Cold Forging .213
17.4 Billet Preparation and Lubrication in Cold Forging of Steel
and Aluminum .214
17.5 Upsetting 215
17.6 Load Estimation for Flashless Closed-Die Upsetting .216
17.7 Extrusion 218
17.8 Estimation of Friction and Flow Stress .221
17.9 Prediction of Extrusion Loads from Selected Formulas 222
17.10 Prediction of Extrusion Loads from Model Test .224
17.11 Tooling for Cold Forging .225
17.12 Punch Design for Cold Forging .227
17.13 Die Design and Shrink Fit 228
17.14 Process Sequence Design .229
17.15 Parameters Affecting Tool Life 230
17.16 Warm Forging 233
Appendices (CD-ROM only)
17.1 Examples of Forging Sequences
17.2 Forward Rod Extrusion
17.3 Backward Rod Extrusion
Chapter 18 Process Modeling in Cold Forging Using Finite-Element
Analysis 237
18.1 Introduction .237
18.2 Process Modeling Input .237
18.3 Process Modeling Output .239
18.4 Process Modeling Examples .239
Chapter 19 Microstructure Modeling in Superalloy Forging 247
19.1 Introduction .247
19.2 Experiments for Microstructure Model Development 247
19.3 Microstructure Model Formulation 248
19.4 Prediction of Microstructure in Superalloy Forging .254
19.5 Nomenclature of Microstructure Model 254
Chapter 20 Isothermal and Hot Die Forging 257
20.1 Introduction .257
20.2 Isothermal Forging 257
20.3 Hot-Die Forging .258
20.4 Benefits of Isothermal and Hot-Die Forging 258
20.5 High-Temperature Materials for Isothermal and Hot-Die Forging 259
20.6 Equipment and Tooling .263
20.7 Postforging Heat Treatment 269
20.8 Production of Isothermal/Hot-Die Forging 271
20.9 Economic Benefits of Isothermal and Hot-Die Forging 272
20.10 Summary 273
Chapter 21 Die Materials and Die Manufacturing 277
21.1 Introduction .277
21.2 Die and Tool Materials For Hot Forging .277
21.3 Heat Treatment 285
21.4 Die and Tool Materials for Cold Forging 285
21.5 Die Manufacture 289
21.6 Surface Treatments .292
Chapter 22 Die Failures in Cold and Hot Forging 295
22.1 Introduction .295
22.2 Classification of Die Failures 295
22.3 Fracture Mechanisms 296
22.4 Wear Mechanisms .296
22.5 Analytical Wear Models .297
22.6 Parameters Influencing Die Failure 297
22.7 Prediction of Die Fatigue Fracture and Enhancement of Die Life
in Cold Forging Using Finite-Element Modeling (FEM) 307
22.8 Prediction of Die Wear and Enhancement of Die Life Using FEM 311
Chapter 23 Near-Net Shape Forging and New Developments .319
23.1 Introduction .319
23.2 Tolerances in Precision Forging 319
23.3 Advances in Tool Design .323
23.4 Advances in Forging Machines .326
23.5 Innovative Forging Processes 328
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