KEY EQUATIONS AND CHARTS FOR DESIGNING MECHANISMS FOUR-BAR LINKAGES AND TYPICAL INDUSTRIAL APPLICATIONS All mechanisms can be broken down into equivalent four-bar linkages. They can be considered to be the basic mechanism and are useful in many mechanical
PREFACExiiiACKNOWLEDGMENTSxvCHAPTER 1 MOTION CONTROL SYSTEMS1Motion Control Systems Overview 2Glossary of Motion Control Terms 9High-Speed Gearheads Improve Small Servo Performance 10Modular Single-Axis Motion Systems 12Mechanical Components Form Specialized Motion-Control Systems 13Servomotors, Stepper Motors, and Actuators for Motion Control 14Servosystem Feedback Sensors 22Solenoids and Their Applications 29CHAPTER 2 ROBOT MECHANISMS33Industrial Robots 34FANUC Robot Specifications 38Mechanism for Planar Manipulation With Simplified Kinematics 43Tool-Changing Mechanism for Robot 44Piezoelectric Motor in Robot Finger Joint 45Six-Degree-of-Freedom Parallel Minimanipulator 46Self-Reconfigurable, Two-Arm Manipulator With Bracing 47Improved Roller and Gear Drives for Robots and Vehicles 48All-Terrain Vehicle With Self-Righting and Pose Control 49CHAPTER 3 PARTS-HANDLING MECHANISMS51Mechanisms That Sort, Feed, or Weigh 52Cutting Mechanisms 56Flipping Mechanisms 58Vibrating Mechanism 58Seven Basic Parts Selectors 59Eleven Parts-Handling Mechanisms 60Seven Automatic-Feed Mechanisms 62Seven Linkages for Transport Mechanisms 65Conveyor Systems for Production Machines 68Traversing Mechanisms for Winding Machines 73Vacuum Pickup Positions Pills 75Machine Applies Labels from Stacks or Rollers 75High-Speed Machines for Adhesive Applications 76Automatic Stopping Mechanisms for Faulty Machine Operation 82Electrical Automatic Stopping Mechanisms 88Automatic Safety Mechanisms for Operating Machines 90CHAPTER 4 RECIPROCATING AND GENERAL-PURPOSE MECHANISM93Gears and Eccentric Disk Combine in Quick Indexing 94Timung Belts, Four-Bar Linkage Team Up for Smooth Indexing 95Modified Ratchet Drive 96Odd Shapes in Planetary Give Smooth Stop and Go 97Cycloid Gear Mechanism Controls Stroke of Pump 99Converting Rotary-to-Linear Motion 100New Star Wheels Challenge Geneva Drives for Indexing 100viiCONTENTSSclater FM 5/3/01 9:50 AM Page vii Geneva Mechanisms 103Modified Geneva Drives 106Indexing and Intermittent Mechanisms 108Rotary-to-Reciprocating Motion and Dwell Mechanisms 116Friction Devices for Intermittent Rotary Motion 122No Teeth on These Ratchets 124Cam-Controlled Planetary Gear System 125CHAPTER 5 SPECIAL-PURPOSE MECHANISMS127Nine Different Ball Slides for Linear Motion 128Ball-Bearing Screws Convert Rotary to Linear Motion 130Three-Point Gear/Leadscrew Positioning 131Unique Linkage Produces Precise Straight-Line Motion 132Twelve Expanding and Contracting Devices 134Five Linkages for Straight-Line Motion 136Linkage Ratios for Straight-Line Mechanisms 138Linkages for Other Motions 139Five Cardan-Gear Mechanisms 140Ten Ways to Change Straight-Line Direction 142Nine More Ways to Change Straight-Line Direction 144Linkages for Accelerating and Decelerating Linear Strokes 146Linkages for Multiplying Short Motions 148Parallel-Link Mechanisms 150Stroke Multiplier 150Force and Stroke Multipliers 152Stroke-Amplifying Mechanisms 154Adjustable-Stroke Mechanisms 155Adjustable-Output Mechanisms 156Reversing Mechanisms 158Computing Mechanisms 159Eighteen Variations of Differential Linkage 163Space Mechanisms 165Seven Popular Types of Three-Dimensional Drives 167Inchworm Actuator 172CHAPTER 6 SPRING, BELLOW, FLEXURE, SCREW, AND BALL DEVICES173Flat Springs in Mechanisms 174Pop-Up Springs Get New Backbone 176Twelve Ways to Put Springs to Work 177Overriding Spring Mechanisms for Low-Torque Drives 179Spring Motors and Typical Associated Mechanisms 181Flexures Accurately Support Pivoting Mechanisms and Instruments 183Taut Bands and Leadscrew Provide Accurate Rotary Motion 185Air Spring Mechanisms 186Obtaining Variable Rates from Springs 188Belleville Springs 189Spring-Type Linkage for Vibration Control 190Twenty Screw Devices 191Ten Ways to Employ Screw Mechanisms 194Seven Special Screw Arrangements 195Fourteen Adjusting Devices 196Linear Roller Bearings Are Suited for High-Load, Heavy-Duty Tasks 197CHAPTER 7 CAM, TOGGLE, CHAIN, AND BELT MECHANISMS199Cam Basics 200Cam-Curve Generating Mechanisms 201viiiSclater FM 5/3/01 9:50 AM Page viii Fifteen Ideas for Cam Mechanisms 207Special-Function Cams 209Cam Drives for Machine Tools 210Toggle Linkage Applications in Different Mechanisms 211Sixteen Latch, Toggle, and Trigger Devices 213Six Snap-Action Mechanisms 215Eight Snap-Action Devices 217Applications of the Differential Winch to Control Systems 219Six Applications for mechanical Power Amplifiers 221Variable-Speed Belt and Chain Drives 224Getting in Step With Hybrid Belts 227Change Center Distance Without Affecting Speed Ratio 231Motor Mount Pivots for Controlled Tension 231Bushed Roller Chains and Their Adaptations 232Six Ingenious Jobs for Roller Chain 234Six More Jobs for Roller Chain 236Mechanisms for Reducing Pulsations in Chain Drives 238Smoother Drive Without Gears 240CHAPTER 8 GEARED SYSTEMS AND VARIABLE-SPEED MECHANISMS241Gears and Gearing 242Nutating-Plate Drive 243Cone Drive Needs No Gears or Pulleys 244Variable-Speed Mechanical Drives 245Unidirectional Drive 253More Variable-Speed Drives 254Variable-Speed Friction Drives 256Variable-Speed Drives and Transmissions 258Precision Ball Bearings Replace Gears in Tiny Speed Reducers 260Multifunction Flywheel Smoothes Friction in Tape Cassette Drive 261Controlled Differential Drives 262Twin-Motor Planetary Gears Provide Safety Plus Dual-Speed 263Harmonic-Drive Speed Reducers 263Flexible Face-Gears Make Efficient High-Reduction Drives 266Compact Rotary Sequencer 267Planetary Gear Systems 268Noncircular Gears 275Sheet-Metal Gears, Sprockets, Worms, and Ratchets 279How to Prevent Reverse Rotation 281Gear-Shift Arrangements 282Shifting Mechanisms for Gears and Clutches 284Fine-Focus Adjustments 286Ratchet-Tooth Speed-Change Drive 287Twinworm Gear Drive 287Compliant Gearing for Redundant Torque Drive 289Lighter, More-Efficient Helicopter Transmissions 290Worm Gear With Hydrostatic Engagement 290Straddle Design of Spiral Bevel and Hypoid Gears 292CHAPTER 9 COUPLING, CLUTCHING, AND BRAKING DEVICES293Coupling of Parallel Shafts 294Novel Linkage Couples Offset Shafts 295Disk-and-Link Coupling Simplifies Transmissions 296Interlocking Space-Frames Flex as They Transmit Shaft Torque 297Off-Center Pins Cancel Misalignment of Shafts 299Hinged Links and Torsion Bushings Give Drives a Soft Start 300ixSclater FM 5/3/01 9:50 AM Page ix Universal Joint Relays Power 45° at Constant Speeds 301Basic Mechanical Clutches 302Spring-Wrapped Slip Clutches 304Controlled-Slip Concept Adds New Uses for Spring Clutches 306Spring Bands Grip Tightly to Drive Overrunning Clutch 307Slip and Bidirectional Clutches Combine to Control Torque 308Walking Pressure Plate Delivers Constant Torque 309Conical-Rotor Motor Provides Instant Clutching or Braking 310Fast-Reversal Reel Drive 310Seven Overrunning Clutches 311Spring-Loaded Pins aid Sprags in One-Way Clutch 312Roller-Type Clutch 312One-Way Output From Speed Reducers 313Springs, Shuttle Pinion, and Sliding Ball Perform in One-Way Drives 314Details of Overriding Clutches 316Ten Ways to Apply Overrunning Clutches 318Applications for Sprag-Type Clutches 320Small Mechanical Clutches for Precise Service 322Mechanisms for Station Clutches 324Twelve Applications for Electromagnetic Clutches and Brakes 326Trip Roller Clutch 328Geared Electromechanical Rotary Joint 329Ten Universal Shaft Couplings 330Methods for Coupling Rotating Shafts 332Linkages for Band Clutches and Brakes 336Special Coupling Mechanisms 337Link Coupling Mechanisms 338CHAPTER 10 TORQUE-LIMITING, TENSIONING, AND GOVERNING DEVICES339Caliper Brakes Help Maintain Proper Tension in Press Feed 340Sensors Aid Clutch/Brakes 340Warning Device Prevents Overloading of Boom 341Constant Watch on Cable Tension 341Torque-Limiters Protect Light-Duty Drives 342Limiters Prevent Overloading 343Seven Ways to Limit Shaft Rotation 346Mechanical Systems for Controlling Tension and Speed 348Drives for Controlling Tension 352Switch Prevents Overloading of a Hoist 355Mechanical, Geared, and Cammed Limit Switches 356Limit Switches in Machinery 358Automatic Speed Governors 362Centrifugal, Pneumatic, Hydraulic, and Electric Governors 364Speed Control Devices for Mechanisms 366Floating-Pinion Torque Splitter 367CHAPTER 11 PNEUMATIC AND HYDRAULIC MACHINE AND MECHANISM CONTROL369Designs and Operating Principles of Typical Pumps 370Rotary-Pump Mechanisms 374Mechanisms Actuated by Pneumatic or Hydraulic Cylinders 376Foot-Controlled Braking System 378Linkages Actuate Steering in a Tractor 378Fifteen Jobs for Pneumatic Power 379Ten Ways to Use Metal Diaphragms and Capsules 380Differential Transformer Sensing Devices 382High-Speed Counters 384Designing With Permanent Magnets 385xSclater FM 5/3/01 9:50 AM Page x Permanent Magnet Mechanisms 387Electrically Driven Hammer Mechanisms 390Thermostatic Mechanisms 392Temperature-Regulating Mechanisms 396Photoelectric Controls 398Liquid Level Indicators and Controllers 400Instant Muscle With Pyrotechnic Power 402CHAPTER 12 FASTENING, LATCHING, CLAMPING, AND CHUCKING DEVICES405Remotely Controlled Latch 406Toggle Fastener Inserts, Locks, and Releases Easily 407Grapple Frees Loads Automatically 407Quick-Release Lock Pin Has a Ball Detent 408Automatic Brake Locks Hoist When Driving Torque Ceases 408Lift-Tong Mechanism Firmly Grips Objects 409Perpendicular-Force Latch 409Quick-Release Mechanisms 410Ring Springs Clamp Platform Elevator Into Position 411Quick-Acting Clamps for Machines and Fixtures 412Friction Clamping Devices 414Detents for Stopping Mechanical Movements 416Ten Different Splined Connections 418Fourteen Ways to Fasten Hubs to Shafts 420Clamping Devices for Accurately Aligning Adjustable Parts 422Spring-Loaded Chucks and Holding Fixtures 424Short In-Line Turnbuckle 424Actuator Exerts Tensile or Compressive Axial Load 425Gripping System for Mechanical Testing of Composites 426Passive Capture Joint With Three Degrees of Freedom 427Probe-and-Socket Fasteners for Robotic Assembly 428CHAPTER 13 KEY EQUATIONS AND CHARTS FOR DESIGNING MECHANISMS429Four-Bar Linkages and Typical Industrial Applications 430Designing Geared Five-Bar Mechanisms 432Kinematics of Intermittent Mechanisms—The External Geneva Wheel 436Kinematics of Intermittent Mechanisms—The Internal Geneva Wheel 439Equations for Designing Cycloid Mechanisms 442Designing Crank-and-Rocker Links With Optimum Force Transmission 445Design Curves and Equations for Gear-Slider Mechanisms 448Designing Snap-Action Toggles 452Feeder Mechanisms for Angular Motions 455Feeder Mechanisms for Curvilinear Motions 456Roberts’ Law Helps to Find Alternate Four-Bar Linkages 459Ratchet Layout Analyzed 460Slider-Crank Mechanism 461CHAPTER 14 NEW DIRECTIONS IN MACHINE DESIGN463Software Improvements Expand CAD Capabilities 464New Processes Expand Choices for Rapid Prototyping 468Micromachines Open a New Frontier for Machine Design 475Multilevel Fabrication Permits More Complex and Functional MEMS 478Miniature Multispeed Transmissions for Small Motors 481MEMS Chips Become Integrated Microcontrol Systems 482LIGA: An Alternative Method for Making Microminiature Parts 484INDEX487xiSclater FM 5/3/01 9:50 AM Page xi . Roller and Gear Drives for Robots and Vehicles 48All-Terrain Vehicle With Self-Righting and Pose Control 4 9CHAPTER 3 PARTS-HANDLING MECHANISMS5 1Mechanisms. 148Parallel-Link Mechanisms 150Stroke Multiplier 150Force and Stroke Multipliers 152Stroke-Amplifying Mechanisms 154Adjustable-Stroke Mechanisms 155Adjustable-Output