Worm drive

About: Worm drive is a research topic. Over the lifetime, 22443 publications have been published within this topic receiving 74390 citations. The topic is also known as: Worm gear.

Surgical instrument incorporating an articulation mechanism having rotation about the longitudinal axis

Abstract: A surgical instrument particularly suited to endoscopic articulates an end effector by including an end effector having a geared articulation mechanism that converts rotational motion from a handle portion. A hollow articulation drive tube transfers the rotation motion in some versions to a spear gear, bevel gear or snaggle tooth gear articulation mechanism. Alternatively, one or more threaded drive rod offset from a longitudinal axis engages a worm gear or flex-neck articulation mechanism.

Steering control for toy electric vehicles

Abstract: A device for controlling the steering and direction of movement of an electrically operated toy vehicle wherein the toy vehicle has a rear axle driven by a gear train from an electric motor and a worm gear on the rear axle engaging a helical gear. The front wheels are connected by a tie rod and are adjustable together from a normal straight line position to an angular position to cause the vehicle to run in a curved path. An adjusting arm on the helical gear presets the angular position of the helical gear in which a reversal of direction will occur and a plurality of such angular positions may be provided. The direct current source or battery for motor power for the unit includes a pair of electromagnets in circuit with the source of electrical current, which is direct current, and with contact members. Energization of one of the electromagnets will, through a link, connection to the tie rod, cause the front wheels to turn in one direction. Energization of the other electromagnet will turn the front wheels in another direction. A spring connected to the link and tie rod for normalizing the position of the tie rod causes the front wheels to be directed straight ahead. The electromagnets, the direct current power source, such as a battery, and contact members are placed in series with each other.

Handbook of Practical Gear Design

Abstract: Foreword, Preface Gear-Design Trends Manufacturing Trends Small, Low-Cost Gears for Toys, Gadgets and Mechanisms Appliance Gears Machine Tools Control Gears Vehicle Gears Transportation Gears Marine Gears Aerospace Gears Industrial Gearing Gears in the Oil and Gas Industry Mill Gears Selection of the Right Kind of Gear External Spur Gears External Helical Gears Internal Gears Straight Bevel Gears Zerol Bevel Gears Spiral Bevel Gears Hypoid Gears Face Gears Crossed-Helical Gears (Nonenveloping Worm Gears) Single-Enveloping Worm Gears Double-Enveloping Worm Gears Spiroid Gears Preliminary Design Considerations Stress Formulas Calculated Stresses Gear-Design Limits Gear-Strength Calculations Gear Surface-Durability Calculations Gear Scoring Thermal Limits Preliminary Estimate of Gear Size Gear Specifications Size of Spur and Helical Gears by Q-Factor Method Indexes of Tooth Loading Estimating Spur- and Helical-Gear Size by K-Factor Estimating Bevel-Gear Size Estimating Worm-Gear Size Estimating Spiroid-Gear Size Data Needed for Gear Drawings Gear Dimensional Data Gear-Tooth Tolerances Gear Material and Heat Treat Data Enclosed Gear Unit Requirements Design Formulas Calculations of Gear-Tooth Data Number of Pinion Teeth Hunting Teeth Spur-Gear-Tooth Proportions Root Filler Radii of Curvature Long-Addendum Pinions Tooth Thickness Chordal Dimensions Degrees Roll and Limit Diameter Form Diameter and Contact Ratio Spur-Gear Dimension Sheet Internal-Gear Dimension Sheet Helical-Gear Tooth Proportions Helical-Gear Dimension Sheet Bevel-Gear Tooth Proportions Straight-Bevel-Gear Dimension Sheet Spiral-Bevel-Gear Dimension Sheet Zerol-Bevel-Gear Dimension Sheet Hypoid-Gear Calculations Face Gear Calculations Crossed-Helical-Gear Proportions Single-Enveloping-Worm-Gear Proportions Single-Enveloping Worm Gears Double-Enveloping Worm Gears Gear-Rating Practice General Considerations in Rating Calculations General Formulas for Tooth Bending Strength and Tooth Surface Durability Geometry Factors for Strength Overall Derating Factor for Strength Geometry Factors for Durability Overall Derating Factor for Surface Durability Load Rating of Worm Gearing Design Formulas for Scoring Trade Standards for Rating Gears Vehicle Gear-Rating Practice Marine Gear-Rating Practices Aerospace Gear-Rating Practices Gear Materials Steels for Gears Mechanical Properties Heat-Treating Techniques Heat-Treating Data Hardness Tests Localized Hardening of Gear Teeth Carburizing Nitriding Induction Hardening of Steel Flame Hardening of Steel Combined Heat Treatments Metallurgical Quality of Steel Gears Cast Irons for Gears Gray Cast Iron Ductile Iron Sintered Iron Nonferrous Gear Metals Kinds of Bronze Standard Gear Bronzes Nonmetallic Gears Thermosetting Laminates Nylon Gears Gear-Manufacturing Methods Gear-Tooth Cutting Gear Hobbing Shaping-Pinion Cutter Shaping-Rack Cutter Cutting Bevel Gears Gear Milling Broaching Gears Punching Gears G-TRAC Generating Gear Grinding Form Grinding Generating Grinding-Disc Wheel Generating Grinding-Bevel Gears Generating Grinding-Threaded Wheel Thread Grinding Gear Shaving, Rolling, and Honing Rotary Shaving Rack Shaving Gear Rolling Gear Honing Gear Measurement Gear Accuracy Measurements Machines to Measure Gears Gear Casting and Forming Cast and Molded Gears Sintered Gears Cold-Drawn Gears and Rolled Worm Threads Design of Tools to Make Gear Teeth Shaper Cutters Gear Hobs Spur-Gear Milling Cutters Worm Milling Cutters and Grinding Wheels Gear-Shaving Cutters Punching Tools Sintering Tools The Kinds and Causes of Gear Failures Analysis of Gear-System Problems Determining the Problem Possible Causes of Gear-System Failures Incompatibility of Gear Systems Investigation of Gear Systems Analysis of Tooth Failures and Gear Bearing Failures Nomenclature of Gear Failure Tooth Breakage Pitting of Gear Teeth Scoring Failures Wear Failures Gearbox Bearings Rolling-Element Bearings Sliding-Element Bearings Some Causes of Gear Failure Other than Excess Transmitted Load Overload Gear Failures Gear Casing Problems Lubrication Failures Thermal Problems in Fast-Running Gears Special Design Problems Center Distance Problems Profile Modification Problems Load Rating Problem Appendix Material Introduction to Gears Dynamic Load Theory Highest and Lowest Points of Single-Tooth Contact Layout of Large Circles by Calculation Special Calculations for Spur Gears Special Calculation for Internal Gears Special Calculation for Helical Gears Summary Sheets for Bevel Gears Complete AGMA and ISO Formulas for Bending Strength and Surface Durability Profile Modification Calculation Procedure The Basics of Gear-Tooth Measurement for Accuracy and Size Shaper-Cutter Tooth Thickness General Method for Determining Tooth Thicknesses when Helical Gears Are Operated on Spread Centers Calculation of Geometry Factor for Scoring References, Index 186 tables, 291 figures HUNDREDS OF ILLUSTRATIONS Almost 300 diagrams and other schematics, photographs and micrographs clearly illustrate gear designs, gearsets and assemblies, and applications. Here is a small sampling of these illustrations. Tractor power train Partially assembled double-reduction marine gear unit Two-stage epicyclic gear, close-coupled to a high-speed gas turbine Spur-gear and rack terminology Helical-gear and rack terminology Internal gear terminology Hypoid-gear arrangement Terminology of cone-drive worm gears Dimensions used in scoring-factor calculation Eight kinds of gear arrangements for spur or helical gears Standard drawing format for spiral bevel gears Calculation of bevel-gear body dimensions Worm-gear design examples Machine induction-hardening of large internal gear Metallurgical examples, nitrided gears (micrographs) Phenolic laminated gear with a steel hub ... Comparison of form grinding and generating grinding Operating principles of single-die gear-rolling machine Outline of methods for making gear teeth ALMOST 200 TABLES A wealth of data is economically provided in the many tables in this text. Here is a small sampling of this reference material. Gear Terms, Symbols and Units Scoring Calculation Methods Ratio Factors for Single-Reduction Gears Nominal Capacity of Double-Enveloping Worm Gearing Typical AGMA Gear Tolerances for Quality Numbers 9-13 Spur-Gear Proportions Tolerances on Tooth Thickness Spur-Gear Dimensions Helical-Gear Basic Tooth Data Indexes of Tooth Loading for Preliminary Design Calculations Straight-Bevel-Gear Dimensions Load-Stress Factors for Crossed-Helical Gears Nominal Lubricant Properties Composition of Typical Gear Steels Hardness-Testing Apparatus and Applications for Gears Some Examples of Production Time for Hobbing or Milling Gear Teeth Checklist (for) Investigating Gear Failures

A Compact Rotary Series Elastic Actuator for Human Assistive Systems

Abstract: Precise and large torque generation, back drivability, low output impedance, and compactness of hardware are important requirements for human assistive robots. In this paper, a compact rotary series elastic actuator (cRSEA) is designed considering these requirements. To magnify the torque generated by an electric motor in the limited space of the compact device, a worm gear is utilized. However, the actual torque amplification ratio provided by the worm gear is different from the nominal speed reduction ratio due to friction, which makes the controller design challenging. In this paper, the friction effect is considered in the model of cRSEA, and a robust control algorithm is designed to precisely control the torque output in the presence of nonlinearities such as the friction. The mechanical design and dynamic model of the proposed device and the design of a robust control algorithm are discussed, and actuation performance is verified by experiments. Experimental results with a human subject are also presented to show the performance of the cRSEA while interacting with humans.