Design Of Worm Gear Research Articles

ASPECTS REGARDING OPTIMAL DESIGN FOR THE WORM-GEAR DRIVE

It is known that, from the point of view of the accuracy of a machine-tool, at its design, the dynamic behaviour of each element of the kinematic chains prevails. Worm-gear drives are widely used in the different machine-tools and robots. Therefore, it is important that during meshing, as far as possible, there are no vibrations, shocks, power losses, noise and low durability. These requirements can be met if, for example, the gear ratio is constant during meshing, without transmission errors, which means that the worm-gear drive should have a high accuracy. The accuracy improvement of the worm-gear drive has long been a focus of attention for machine-tools designers. Thus, this paper presents various approaches to solving such problems, based on modelling and simulation, such as: estimating the load share of worm-gear drives and to calculate the instantaneous tooth meshing stiffness and loaded transmission errors; the desired worm-gear drive design configuration by altering the optimum set of worm-gear drive design parameters which are suitable for the required performance by associating it with SVM (Support Vector Machine); optimization approach for design of worm-gear drive based on Genetic Algorithm; design optimization of worm-gear drive with reduced power loss; etc. The optimization of the worm-gear design is an important problem for the research because the design variables are correlated to each other. An optimal design algorithm developed by the authors of this paper, for worm-gear drive, is also presented.

Investigation on the Backlash of Roller Enveloping Hourglass Worm Gear: Theoretical Analysis and Experiment

This paper proposes a single-roller enveloping hourglass worm gear design and verifies its advantages compared to the existing double-roller worm gear system and the conventional worm gear set. Our hypothesis is that the single-roller worm gear with appropriate configurations and parametric values can eliminate the backlash in mating gear transmission while maintaining advantages of the double-roller worm gears. Also, the self-rotation of the rollers when they are in the worm tooth space (TS) will help the gear system to avoid jamming and gear tooth scuffing/seizing problems caused by zero backlash and thermal expansion. In order to test that hypothesis, a mathematical model for the single-roller enveloping hourglass worm gear is developed, which includes a gear engagement equation and a tooth profile equation. Using that model, a parametric study is conducted to inspect the influences of center distance, roller radius, transmission ratio, and the radius of base circle on the worm gear meshing characteristics. It is found that the most effective way in eliminating the backlash is to adjust the roller radius and the radius of base circle. Finally, a single-roller enveloping hourglass worm gear set is manufactured and scanned to generate a 3D computer model. That model is compared with a theoretical model calculated from the developed mathematical model. Comparison results show that both models match very well, which verifies the accuracy of the developed mathematical model and our initial hypothesis that it is possible to achieve transmissions with zero backlash by adjusting the design parameters.

Innovative design of non-backlash worm gear drives

In this paper the authors present the newest designs of worm gear drives which allow to adjust or decrease the amount of backlash. This effect is achieved with innovative designs of worms and worm wheels. The designed drives are aimed to find their application in systems for precise positioning of measurement assemblies, precise drives of technological instrumentation, as well as in micro-mechanisms. Many of the presented designs allow backlash adjustment without removing of the worm gear drive. The described solutions present a good alternative to conventional high-gear precision drives as well as harmonic drives used at speeds typical to positioning mechanisms.This paper presents the results of numerical research performed with the MES finite element method and also the results of experimental research on the innovative worm gear drive with an axially adaptive worm. The results analysis has led to the conclusion, that the described solutions allow reduction of backlash to 5–15%, and even greater reduction of its standard deviation – that is 5–10% – of their initial values.

Accounting for Film-Forming and Damping Properties of Lubricants in Worm Gear Design

Accounting for Film-Forming and Damping Properties of Lubricants in Worm Gear Design

Методика проектирования червячных передач с учетом неравномерности вращения ведомого вала

Методика проектирования червячных передач с учетом неравномерности вращения ведомого вала

The Automatic Up-Down Material Manipulator Wrist 3d Design

The automatic up-down material manipulator wrist requirements compact structure, rational layout. The typical wrist structure has a variety of, this design wrist structure for step motor drives a turbine worm movement of the structure, main function is to drive the PAWS, make its can accurately to grab parts and placed parts. Operation mode for step motor drive worm and worm wheel rotation, and then drive the turn of the wrist. Through the design of the wheel of worm gear and worm gear design, step motor selection, etc, and then, a 3 d design, and gives a picture.

Load sharing and stress analysis of single enveloping worm gearing considering transmission errors

A procedure, known as the slicing method, which has been developed earlier by the authors to estimate the load share of single enveloping (cylindrical) worm gear drives and to calculate the instantaneous tooth meshing stiffness and stresses, is extended in this study to investigate the effect of transmission error on loading and stresses. Tooth composite deflection caused by bending, shearing, contact deformation and initial separation due to profile mismatch are determined in the analysis as well as tooth stiffness variation during the course of contact of both the worm and the wheel. The elasticity theory was used to calculate fillet stresses and deformation of both the worm and wheel. Numerical examples are presented to illustrate the response of worm gear set in the presence of transmission error and under given loading conditions. The procedure was proven to be safe and reliable in rating the load capacity and useful in the design of worm gear drives with compact size and high power transmission.

Pitch Cone Design and Avoidance of Contact Envelope and Tooth Undercutting for Conical Worm Gear Drives

This paper presents a systematic approach for the design, generation and analysis of conical worm gear drives. The approach is based on the mathematical formulations on the mesh, tooth generation process and conditions for the appearance of contact envelope and tooth undercutting of this type of worm drives. The formulation is implemented by a computer model developed in MatLab environment. By model simulation on worm gear mesh or generation, the conditions for the formation of contact envelope and tooth undercutting are accurately determined for the proper design of worm gear blank and tooth geometry. The computer model can also be used to calculate worm gear tooth geometry and create solid models for the worm gear drives. Numerical examples on conical worm gear drive design, analysis on the problems of contact envelope, limit line and limit point are included in the paper.

Computer program in Visual Basic language for simulation of meshing and contact of gear drives and its application for design of worm gear drive

The authors propose: (i) enhanced computer program for simulation of meshing and contact of gear drives; (ii) application of computer program for analysis of worm gear drive; and (iii) advanced design of worm gear drive with reduced transmission errors and favorable bearing contact. The output of Tooth Contact Analysis (TCA) program are: function of transmission errors, path of contact and bearing contact. The program is written in Visual Basic language and enables to combine numerical computation and graphical illustration. The improved design of worm gear drive is based on application of an oversized hob and modified worm generated by varied plunging of the generating tool. It is discovered that worm generation without tool plunging may cause positive transmission errors, unacceptable for favorable conditions of force transmission. Positive transmission errors are the herald of possible surface interference. A predesigned parabolic function of transmission errors is provided in order to absorb transmission errors caused by errors of alignment and reduce the level of vibrations, especially in the case of application of multi-thread worms. The investigation is accomplished for a worm-gear drive with the Klingelnberg type of the worm that is ground by a circular cone, but the proposed approach may be applied for other types of worm gear drives with cylindrical worms.

Computerized Design, Generation and Simulation of Meshing of a Spiroid Worm-Gear Drive with a Ground Double-Crowned Worm

The authors propose methods of computerized design and analysis of a spiroid worm-gear drive with ground worm based on the following considerations: (1) The theoretical thread surface of the hob is generated by a cone surface. (2) The worm surface is crowned in profile and longitudinal directions in comparison with the hob thread surface. (3) The double crowning of the worm enables to localize the bearing contact and obtain a predesigned parabolic function of transmission errors of an assigned level. Computerized design of the worm-gear drive enables to discover and avoid singularities of the generated worm face-gear surface and pointing of teeth. The meshing and contact of the double-crowned worm and the worm face-gear is simulated to determine the influence of misalignment on the shift of bearing contact and transmission errors. Computer program for numerical solution is developed and applied. A numerical example that illustrates the developed theory is provided.

The Thermal Rating of Worm Gearboxes

The paper deals with the factors affecting the temperature rise of totally enclosed self-lubricated gearboxes, with particular reference to worm gearboxes, and is based on observations obtained from a power circulating apparatus through worm gears which has provision for the accurate measurement of efficiency and temperature rise under variable load and speed. The theory underlying the heating and cooling of gearboxes is discussed, for gears running under continuous load and also under a repeated cycle of intermittent load. Temperature rise depends on the heat-dissipating capacity of the gearbox and the power losses within the box; heat-dissipating capacity is dealt with in relation to surface area of the box, speed of the gears, and artificial cooling by air fan; power losses are discussed under the headings of efficiency and oil drag losses. It is shown that gear speed and turbulence in the lubricant contribute considerably to heat-dissipating capacity, and that oil drag losses play an important part, particularly on large gears running at moderate or high speed. Cooling by air or other means is shown to result in an increase in power capacity (for a given allowable temperature rise) much more than in proportion to the increase in heat-dissipating capacity of the box, owing to a higher overall efficiency when transmitting heavier loads. Results of worm gear efficiency tests carried out in the past on the Daimler-Lanchester testing machine at the National Physical Laboratory on the author's design of worm gear, which gave the highest efficiency of any published tests carried out on this machine, are reconsidered in the light of recent work and it is contended that the National Physical Laboratory machine gives efficiency figures which are in general higher than the true efficiency.