Asymmetric Spur Gear Research Articles

Objective function to Optimize Bending Stress at Critical Section of Asymmetric Spur Gear

Main objective of this paper is to optimize Bending stress at critical section, which is most important parameter in gear design. It must be low as low possible. Bending Stress optimize by all affected Parameters of asymmetric spur gear tooth at critical section of tooth. Objective function for bending stress at critical section has been developed to minimize/optimize bending stress at critical section thickness of asymmetric spur gear tooth. A programme has been developed in SciLab software with help of developed objective function to optimize the bending stress at critical section of an asymmetric spur gear. Result obtains from SciLab programme compared to ANSYS software and give comment on validation of developed objective function.

Injection molded asymmetric spur gear — development and preliminary performance evaluation

Innovative gear designs are essential to meet the increasing demands of high load carrying capacity, high endurance, low cost, long life, and high speeds in automobile, aerospace, and wind turbine industries. Conventional gears are having symmetric teeth; however most of the applications necessitate power/motion transmission in one direction. This unidirectional transmission leads to the design of asymmetric teeth in a gear. Extensive research work on design and optimization and asymmetric gear tooth profile for improved bending and contact strength has been attempted. However, very little experimental investigation has been attempted and no work has been attempted in the experimental investigation of asymmetric polymeric gears. In this work, unreinforced polypropylene material is injection molded for the asymmetric spur gears. Gears are molded to the size of 3 mm module, 18 number of teeth and having pressure angle of 34° and 20° at drive and coast side respectively. To examine surface durability and the kinematic characteristics of asymmetric gear, a gear test rig is developed in the laboratory with permanent magnet direct current motor and powder clutch dynamometer as driving and power absorption unit with necessary inline torque sensors and non contact temperature sensor. Preliminary transmission efficiency and surface temperature of test gears promises wide scope for asymmetric composite gears in motion transmission application. Due to the increase in pressure angle at drive side of gear tooth, relative sliding velocity found to decrease and hence asymmetric gear exhibit superior gear pair efficiency and less surface temperature.

A Comprehensive Study on the Asymmetric Internal Spur Gear Drives through Direct and Conventional Gear Design#

An optimum design for an internal gear pair for the desired values of input parameters has been attempted through a direct gear design approach using area of existence, which is enclosed between the isograms of a desired contact ratio, a definite pitch point contact, an interference free drive and a fouling free condition. By synthesizing several sets of asymmetric pinion cutters for specific values of input parameters, the respective gear and pinion generated by them have been analyzed for a balanced and lowest possible maximum fillet stress to decide the optimum one. A conventional gear design process has also been suggested with stub tooth concept in this regard.

Mathematical Model of a Spur Gear with Asymmetric Involute Teeth and Its Cutting Simulation#

This paper gives a mathematical model for spur gears with asymmetric involute teeth based on the gear theory and generating mechanism. The equations of designed profile of rack cutter with asymmetric teeth, the principle of coordinate transformation, the theory of differential geometry, and the theory of gearing are applied. Trochoidal envelope traced by cutter during generating process is also investigated. Computer graphs of asymmetric involute spur gears are presented based on the given model, and also generation simulation is illustrated. The results of this research should be helpful in the design and manufacture of asymmetric gears.

Optimization of asymmetric spur gear drives to improve the bending load capacity

In a given size of symmetric involute gear designed through conventional approach, as the load carrying capacity is restricted at the higher pressure angle due to tipping formation, the use of the asymmetric toothed gear to improve the fillet capacity in bending is examined in this study. Non-standard asymmetric rack cutters with required pressure angles and module are developed to generate the required pinion and gear of a drive with asymmetric involute surfaces and trochoidal fillet profiles. The respective profiles thus generated are optimized for balanced fillet stresses that are equal and possibly the lowest also. For this study of optimization, several non-standard asymmetric rack cutters are designed to accommodate different combinations in the values of pressure angle, top land thickness ratio, profile shift, speed ratio and the asymmetric factors. However for any drive with a given center distance and a speed ratio, only two non-standard asymmetric rack cutters, one for the pinion and other for the gear are used to generate a required numbers of pinion and gear with different cutter shift values for the purpose of optimization. The influence of these parameters on the maximum fillet stress has been analyzed to suggest the optimum values of these parameters that improve the fillet capacity in bending. The optimization of the asymmetric spur gear drive is carried out using an iterative procedure on the calculated maximum fillet stresses through FEM for different rack cutter shifts and finally the optimum values of rack cutter shifts are suggested for the given center distance and the speed ratio of an asymmetric gear drive. Comparisons have also been made successfully with the results of the AGMA and the ISO codes for symmetric gears to justify the results of the finite element method pertaining to this study.

Optimization of Asymmetric Spur Gear Drives for Maximum Bending Strength Using Direct Gear Design Method#

Two procedures to optimize a given asymmetric gear drive have been developed through direct gear design method. Considering several sets of the addendum pressure angles of pinion and gear for a required contact ratio, first the nonstandard rack cutters and subsequently the asymmetric tooth profiles of pinion and gear are generated for each set. FEM analysis has been carried out to determine maximum fillet stress in pinion and gear at each set. The set of profiles that develops an equal and possible lowest minimum of the maximum fillet stress at its respective fillet is considered as the optimum one for a maximum load carrying capacity. In this connection, the influence of speed ratio, asymmetric factor, number of teeth, and center distance on the maximum fillet stress is also studied.

Asymmetric modified spur gear drives: reduction of noise, localization of contact, simulation of meshing and stress analysis

An asymmetric spur gear drive is considered. The asymmetry means that larger and smaller pressure angles are applied for the driving and coast sides, respectively. The conventional design of such a drive is based on application of involute profiles. The authors propose a modified geometry of an asymmetric spur gear drive designed as a combination of an involute gear and a double crowned pinion that enables to localize and stabilize the bearing contact and obtain a favorable shape of transmission errors of reduced magnitude. Computerized design of spur gears of proposed geometry and simulation of their meshing and contact have been developed. A method of generation of a double-crowned pinion has been developed as well stress analysis of symmetric and asymmetric spur gears have been accomplished, that confirm reduction of contact and bending stresses for an asymmetric spur gear drive. The developed theory is illustrated with numerical examples.