Electrical feed drives for machines tools / edited by Hans Gross.

CONTENIDO
1. Feed Drive and Position Control Loop 13
Basics of Control Theory 13
Open and Closed Loop Control 13
Stationary Systems Behavior 14
Characteristic Curves 14
Linearization 15
Normalized Values 16
Referenced Values 18
Dynamic Systems Behavior 18
Differential Equations 18
Transient Response 22
Frequency Response Curve 26
Bode Diagram 29
Linkage of Transfer Elements 32
Frequency Response Curve Symbol for Control Loops 34
Experimental Determination of the Frequency Response Curve 35
Basics of the Position Control Loop 36
Construction and Functioning of the Position Control Loop 36
Localization 38
Measuring Value Detection 38
Measuring Procedures 39
Location of Measurement 39
Characteristic Values and Properties ofPosition Control Loops 40
Dynamic Systems Behavior of Single Control Loop Elements 41
Explanation Terms 44
Behavior Linear Position Control Loops 44
Non-linearities in the Position Control Loop 50
Position Loop Gain 52
Position Control Loop Model 52
Settling Time and Overshoot Width at Positioning 53
Ramp Distance for Thread Cutting 56
Contour Deviations on Corners 61
Contour Deviations on Circles 63
Disturbance Transient Response 66
Reqllirements for the Position Loop Gain 67
Bibliography 69
2. DC Motors for Feed Drives 70
Requirements for the Feed Drive 70
Requirements for Stationary Operation 70
DC Shunt Motor 71
Construction Forms 71
Permanent Magnet-excited DC Servo Motors of the Series 71
Electrically Excited DC Servo Motors of the Series 74
Drive Behavior 76
Differential Equation and Block Diagram 76
Stationary Behavior of the Uncontrolled Drive 80
Dynamic Behavior of the Uncontrolled Drive 82
Dynamic Behavior of the Speed-controlled Drive 84
Calculating the Drive Nominal Angular Frequency 86
External Tnertia Effect 92
Dead Time Effect 94
Selection of DC Servo Motors 96
Methods of Calculation 96
Stationary Load 97
Friction and Losses 98
Machining Force 100
Dynamic Load 102
Heating Behavior 111
Periodic Load Changes 111
Overload Behavior 112
Thermal Time Constants 116
Additional Optimization Criteria 118
Energy Content of Moved Masses 118
Attainable Acceleration 119
Drive Comparisons 121
Calculation Scheme 123
Summary of Calculation Formulas 132
Bibliography 133
3. Current Converters for DC Servo Motors 134
Notions and General Overview 134
Requirements 134
Dead Time 136
Form Factor 137
Efficiency 139
Costs 140
Transistor DC Choppers 141
Applications 141
Principie of Operation 141
Driving, Clockwise, 1. Quadrant 142
Driving, Counterclockwise, ITI. Quadrant 144
Braking, Clockwise, IV. Quadrant 144
Brakillg, Counterc1ockwise, n. Quadrant 145
DC Bus 145
Line Synchrollized Thyristor Controllers 146
Generalities 146
Rectitíer and Inverter Operation 147
Circulating Curent-free Connection 149
Circulating Current-conducting Connection 150
6-Pulse Circulating Current - conducting Cross Connection 151
3-Pulse Circulating Current-conducting Anti-parallel Connection 153
6-Pulse Circulating Current-free Anti-parallel Connection 157
2-Pulse Circulating Current- conducting Anti-parallel Connection 159
Controllers 163
Structure of the Control Loop 163
Overcurrent Limitation 164
Subordinated Current Control 165
Speed Control with Current Limit 166
Status Monitor 168
Adaptive Speed Control Influence 169
Selection Criteria 172
Characteristic Values of Converter Circuits 172
Applications for Con verter Circuits 172
Bibliography 175
4. Design Versions of Mechanical Transmission Elements 177
Generalities 177
Requirements for the Mechanical Transmission System 178
Nominal Angular Frequency 180
Stiffness 184
Damping Gradient 185
Non-linearities 189
Reversing Errors 189
Friction 190
Effects of Rhersing Errors and Frictional Reversing Errors 194
Indirect Position Control Measurement 195
Direct Position Control Measurement 198
Moment of Inertia 202
Cylindrical Bodies 202
Linearly Moved Masses 204
Gear Ratio 205
Calculating the Slide Elements of the Drive 205
Feed Screw Drives 205
Construction and Requirements 205
Feed Screw 208
Stiffness of the Feed Screw 209
Moment of Inertia of the Feed Screw 213
Efficiency 215
Feed Screw Lead 216
Lead Accuracy 216
Critical Speed 217
Buckling Strength 218
Ball Screw Nut 220
Feed Screw Bearings 223
Stiffness and Preload 224
Effect of the Bearing Mounting Elements 226
Friction and Temperature Behavior 227
Rack and Pinion Drives 229
Range of Applications, Influencing Variables 229
Stiffness 230
Torsional Stiffness of Shafts 230
Bending Strength of Shafts 231
Radial Stiffness of Shaft Bearings 231
Bending Strength of the Gear Wheel, Pinion, and Rack Teeth 233
Example 233
Preload at the Pinion 236
Machine Slide and Guides 238
Machine Slide 238
Table Guides 239
Requirements 239
Friction Guides 210
Roller Guides 241
Hydrostatic Guides 243
Aerostatic Guides 244
Damping 245
Gears 247
Overview of Applications 247
Requirements 251
Moment of Inertia 251
Torsion and Bending 253
Reversing Errors 254
Toothed Belt Gear 255
Advantage Limits of a Gear Ratio 259
Motors of Equal Frame Size 259
Motors of Different Frame Size 261
Disturbance Transient Response 264
Comparison of two Motors 264
Couplings 266
Bibliography 268
5. Command Value Modification 271
Purpose of the Command Value Modification 271
Smoothing the Command Values 271
Effects ofCommand Vallle Smoothing 275
Stress and Contour Deviation Characteristics 275
Contour Movements 276
Diagrams for Contour Deviation and Stress Characteristics 279
Determining the Command Value for Acceleration 284
Conclusions 287
Bibliography 287
6. Measurements on Feed Drives 288
Substantiation, Aim 288
Measuring Procedures 289
Measurements on the Mechanical Transmission Elements 289
Reversing Error (Back Lash) 290
Total Stiffness, Nominal Angular Frequency 295
Friction Characteristics 296
Measurements on the Speed Control Loop 298
Step Response, Transient Response 299
Current Limit 301
Motor Heat 301
Nominal Angular Frequency of the Feed Drive 302
Measurements on the Position Control Loop 304
Contour Deviations 304
Measuring the Position Loop Gain 306
Measurements for the Smallest Position Increments 308
Positioning Response 309
Measuring Values of Machines in Use 310
Evaluation of Measured Frequency Response Curves 310
Measurements on a Timing Belt Gear 311
Effect of the Moment of Inertia 314
Motors in Short Version 314
Effects of Optimization of the Speed Control 316
Frequency Response Curve of a Shell Magnet Motor 316
Influence of the Con verter Circuit 318
Frequcncy Rcsponse Curve of an Electrically Excited DC Servo Motor 320
Conclusions 321
7. Technical Data 322
DC Servo Motors 322
General Data 322
Design Series 1 HU 325
Design Series 1 GS 3 331
Current Converter Units 334
Transistor DC Choppers 334
Line-synchronized Thyristor Controllers 336
8. Technical Appendix 339
Symbols and Units Used 339
SI Units 350
Conversion Tables 353
Equations 356
Index 358