Gearwheel Teeth Research Articles

Generation of the teeth precessional gears by plastic deformation

The paper presents a method for obtaining the teeth of the precessional gear by plastic deformation. There are analyzed the basic problems that must be resolved to apply this process: determination of dimensions of initial workpiece; choosing the correct machining regime; determination of necessary forces for material deformation for dimensioning of mechanisms used in machine-tool. The aim is obtaining of precessional gear wheel teeth, still from workpiece to ensure a minimum cost of machining and to improve operating conditions by providing a continuous material fibrillation.

Calculating the Strength of K-H-V Planetary Gears

Рассмотрены вопросы расчета прочности планетарных зубчатых передач вида K-H-V с малой разностью чисел зубьев. При проведении расчетов внесены необходимые коррективы относительно ГОСТ 21354-87 «Передачи зубчатые цилиндрические эвольвентные внешнего зацепления. Расчет на прочность», чтобы использовать его для предупреждения пластического деформирования зубьев при оценке контактной прочности и для предупреждения поломки зубьев при расчете на изгибную выносливость, а также в расчетах на прочность при действии максимальной кратковременной нагрузки. Дополнительно приведен расчет вероятности безотказности работы передачи. На основе выполненных исследований разработана методика расчета планетарных зубчатых передач вида K-H-V на прочность, реализованная в виде интерактивной программы на ЭВМ. Приведены результаты ускоренных ресурсных испытаний передачи, которые были проведены по специально созданной методике и подтвердили основные положения методики расчета на прочность.

Advanced Design of a Gear Shaving Cutter with the Screw Cutting Edges for Finish Machining of Teeth of Gearwheels

Известны конструкции инструментов для чистовой обработки зубьев эвольвентных зубчатых колес со спирально-винтовыми режущими кромками, выполненными на одной боковой стороне витков. Обработка зубчатых колес производится при согласованном вращении инструмента и детали вокруг своих осей и перемещении их относительно друг друга в осевом направлении детали, причем обработка правой и левой стороны профиля зубьев возможна только после переустановки колеса. Недостатком этих инструментов является сложность конструкции и технологии изготовления. Известна конструкция инструмента червячного типа для чистовой обработки зубьев эвольвентных зубчатых колес (авторы Н. А. Чемборисов, Р. М. Хисамутдинов, В. А. Авдеев), выполненного с непрерывными винтовыми режущими кромками, при этом его винтовая поверхность имеет прямоугольный профиль. Недостатком этого инструмента является то, что режущий клин при его работе имеет не вполне удовлетворительную геометрию: передние и задние углы на режущих кромках практически равны нулю. Известен также инструмент (шевер) для чистовой обработки зубьев эвольвентных зубчатых колес, выполненный с непрерывными винтовыми режущими кромками, отличающийся от конструкции Чемборисова Н. А. и соавторов тем, что режущий клин имеет конструктивно выполненный задний угол (авторы Н. В. Сморкалов, В. П. Скрипин, В. П. Птицын, Ю. Ф. Белугин). Последовательная обработка правой и левой стороны профиля зубьев колеса разными винтовыми режущими кромками данным инструментом обеспечивает повышение его стойкости, а также существенно уменьшает вспомогательное время, исключая необходимость переустановки колеса и тем самым повышает производительность процесса. Разработана усовершенствованная конструкция шевера с винтовыми режущими кромками для чистовой обработки зубьев зубчатых колес, которая позволяет улучшить врезание инструмента в металл, уменьшить деформацию стружки и улучшить ее сход, уменьшить силу и мощность резания.

Investigation of Causes for Limiting the Load-Carrying Capacity of Meshing Elements of Spiroid Gears

Появившиеся относительно недавно спироидные передачи находят эффективное применение при различных условиях и режимах работы. Кроме того, существуют различия в применяемых материалах и технологиях изготовления зацепляющихся звеньев спироидных передач. Спироидные колеса можно изготавливать из полиамидов, спекаемых металлических порошков, бронзы, стали и чугуна. Червяк традиционно изготавливают из сталей с использованием термической или химико-термической обработки для повышения прочности и износостойкости. Технологические различия в свою очередь приводят к разным причинам снижениям прочности зубьев спироидных колес и витков червяка. В статье рассмотрены некоторые причины ограничения нагрузочной способности зацепляющихся звеньев спироидных передач. Проводимые многолетние испытания спироидных передач выявили различные виды разрушений для зубьев спироидных колес. Основной причиной разрушений пластмассовых спироидных колес является срез. Для порошковых колес характерны либо срез, либо излом. Однако витки спироидного червяка также могут ломаться неожиданно. Для определения отклонений в структуре и свойствах поверхностного слоя и сердцевины нитроцементованных червяков были проведены металлографические исследования. Из витков спироидных червяков были сделаны образцы, которые затем подвергались всем необходимым манипуляциям для получения микрошлифов.

Нестабильность глубины резания при шлифовании зубьев зубчатых колес методом копирования

Нестабильность глубины резания при шлифовании зубьев зубчатых колес методом копирования

Load Distribution along Tooth Length for Wheels with Two Satellites and Assembled Carrier

The paper presents a method for determining the load factor of uneven distribution along the length of teeth of the James planetary gear wheels containing a prefabricated U - shaped carrier. The solution was carried out with the use of equations for joint motion of gear elements. At the same time it took into account the effect of torsion and bending deformations of the carrier on the load distribution in wheels mesh.

Methodology for Structural Calculation of Gear Teeth with Unconventional Profile

After having made reference to the structural analysis used in the study of gear wheel teeth, we then move on to the state of the art on the topic. We proceed to identify the boundary conditions used in the structural analysis of unconventional teeth with sides having a profile of an involute of a circle but with different pressure angles in each of the two sides. A procedure for the discretization of traditional teeth and of innovative teeth is presented and compared with the discretization obtained using current software.

An automation of design and modelling tasks in NX Siemens environment with original software - cost module

The design-constructional process is a creation activity which strives to fulfil, as well as it possible at the certain moment of time, all demands and needs formulated by a user taking into account social, technical and technological advances. Engineer knowledge and skills and their inborn abilities have the greatest influence on the final product quality and cost. They have also deciding influence on product technical and economic value. Taking into account above it seems to be advisable to make software tools that support an engineer in the process of manufacturing cost estimation. The Cost module is built with analytical procedures which are used for relative manufacturing cost estimation. As in the case of the Generator module the Cost module was written in object programming language C# in Visual Studio environment. During the research the following eight factors, that have the greatest influence on overall manufacturing cost, were distinguished and defined: (i) a gear wheel teeth type it is straight or helicoidal, (ii) a gear wheel design shape A, B with or without wheel hub, (iii) a gear tooth module, (iv) teeth number, (v) gear rim width, (vi) gear wheel material, (vii) heat treatment or thermochemical treatment, (viii) accuracy class. Knowledge of parameters (i) to (v) is indispensable for proper modelling of 3D gear wheels models in CAD system environment. These parameters are also processed in the Cost module. The last three parameters it is (vi) to (viii) are exclusively used in the Cost module. The estimation of manufacturing relative cost is based on indexes calculated for each particular parameter. Estimated in this way the manufacturing relative cost gives an overview of design parameters influence on the final gear wheel manufacturing cost. This relative manufacturing cost takes values from 0.00 to 1,00 range. The bigger index value the higher relative manufacturing cost is. Verification whether the proposed algorithm of relative manufacturing costs estimation has been designed properly was made by comparison of the achieved from the algorithm results with those obtained from industry. This verification has indicated that in most cases both group of results are similar. Taking into account above it is possible to draw a conclusion that the Cost module might play significant role in design constructional process by adding an engineer at the selection stage of alternative gear wheels design. It should be remembered that real manufacturing cost can differ significantly according to available in a factory manufacturing techniques and stock of machine tools.

Comparative studies of the character of destruction in 38Cr2Ni2MoA and 12Cr2Ni4A steel gearwheel teeth operated under extreme conditions

A comparative analysis of the character of destruction occurring in gearwheels that had been preliminary strengthened by high-frequency current quenching and cementation, in the process of their operation under heavy loading was performed. The microstructure of strengthened layers has been shown to be almost identical, despite the difference between the chemical compositions of the gearwheel steels and the methods used for their surface strengthening. The common mechanisms of surface destruction under operation, such as fatigue wear with the formation of pittings at its initial stage, and the formation of wear particles with further abrasive wear, have been established.

Phase-Chromatic Control of Wear of the Working Profiles of the Gear Wheels of a Reduction Gear in the Course of Operation

The use of a phase-chronometric method in estimation of the wear of the working profiles of the teeth of gear wheels in the course of operation of a reduction gear without stopping and disassembly of the reduction gear is described. A very simple mathematical model describing the dynamics of a reduction gear is presented. A diagram of a test bed is presented.

The Modeling Gear Optimization Design Research Based on Pro-E

With the development of computer technology, gear modeling in industry more and more widely used, the PRO-E tool has good modeling function, on the design of three-dimensional CAD tools has a significant role, the tracing point method, parameter method, plug-in method analysis, optimum gear profile modeling. On the tooth height model modification method, draw gear high maximum model modification, model modification can be assigned in the active or passive gear wheel tooth, but also at the same time in the driving wheel and a driven wheel model modification. Corresponding to a single tooth meshing zone involute not model modification, only to repair the dual meshing zone, reach the gear model optimization objective.

Investigation of the surface residual stresses in spray cooled induction hardened gearwheels

Abstract The objective of the current investigation consists of testing the interchangeability of polymer solutions used during induction hardening with water – air spraying regarding compressive residual stresses. Gearwheels made of 42CrMo4 steel were induction hardened and subsequently quenched using water–air spray cooling. The effect of different cooling parameters on the surface's residual stresses in the gearwheel's tooth flanks was analysed by means of X-ray diffraction. The microstructure was characterised by means of hardness measurements and light-microscopy. Residual stresses could be specified after using water – air spray cooling and are comparable to those using polymer quenching. Quench parameters leading to maximum compressive residual stresses in tooth flanks were determined.

Computed determination of the coefficient of bending stresses on the teeth of gear wheels under skewness

An analytical method is given to determine the coefficient of bending stresses in the teeth of gear wheels under skewness caused by elastic deformations and inaccuracies of the manufacturing and mounting of the elements of the gearing. The problem of bending a beam with a finite length on an elastic base under the effect of an arbitrary load was solved. Experimental data of the attenuation of deflections along the length of a cantilever plate were shown to be in satisfactory agreement with the computed results for deflections of a beam with a finite length on an elastic base. Formulas to deter-mine the coefficient of the concentration of bending stresses in the teeth of gear wheels were obtained. The dependences obtained allow us to develop a distribution diagram for variations of the coefficient of the concentration of bending stresses along the length of the teeth under skewness.

An investigation of manual transmission drive rattle

Manual transmission gear rattle is an NVH (noise, vibration, and harshness) concern in the automotive industry. It is induced by repetitive impacts on loose (unselected) gear wheel teeth by their corresponding driving pinions. This phenomenon occurs under various loading conditions and is classified accordingly, including ‘idle rattle’ when the transmission is in neutral and ‘creep and drive rattle’ when the transmission is in a gear with a widely open or a partially open throttle. The phenomenon is also present from drive to coast conditions, referred to as overrun rattle. Engine order fluctuations on the input shaft are considered to be the underlying cause for rattle of loose gears. However, the mechanism of transmission of vibration through lubricated contacts is not fundamentally understood. It is surmised that changes in lubricated contact conditions at different bulk oil temperatures may play a key role and, therefore, offer an opportunity to deal with rattle by a root-cause fundamental solution. This means that a detailed multi-physics approach (including dynamics, vibration, and tribology) is needed. This article provides detailed analytical models of lubricated conjunctions in a multi-body dynamics model of a transaxle seven-speed transmission system under creep rattle conditions. The results show the important role of the regime of lubrication in lightly loaded conjunctions, increasing the propensity to rattle at higher temperatures. It is also revealed that the effect of engine order vibration as an initiating source for rattle becomes significant with reduced hydrodynamic contact stiffness at rising temperatures.

Investigation of Contact Fatigue of High Strength Steel Gears Subjected to Surface Treatment

In this paper the contact fatigue resistance of gearwheel teeth, subjected to shot-peening treatment, was investigated experimentally and analytically. The main objective was the evaluation and prediction of fatigue crack initiation, propagation, direction, and rate. A specially designed experimental rig was used to test a number of spur gears with the following characteristics: (a) unhardened, thermally untreated unpeened surfaces, (b) thermally treated unpeened surfaces, (c) unhardened peened surfaces, and (d) thermally treated peened surfaces. The theoretical model assumed initiation and propagation of surface cracks of gears operating in the elastohydrodynamic lubrication regime while loading was due to simultaneous rolling and sliding. Finite element modeling was used for the calculation of the stress field at the gear teeth. Comparison of the experimental and analytical results showed considerable improvement in the contact fatigue strength of thermally treated gear teeth and especially those that underwent shot peening, which increased surface durability. The residual stresses induced by shot peening are mainly effective in stopping microcrack propagation. When shot peening is applied on thermally untreated gear teeth surface, it increases the contact fatigue life of the material by 17% at 7 × 105 loading cycles. If shot peening is applied on carburized gear teeth surfaces, it increases the surface fatigue life by approximately 8% at 106 cycles. Contact fatigue and eventual pitting are treated as a normal consequence of the operation of machine elements. To study this failure process different types of testing machines have been designed. The purpose of this paper is the presentation and evaluation of a new design experimental rig for studying contact fatigue damage of gear teeth subjected to different load patterns.

Simulation of the distortion manipulation of gear wheel teeth by thermal pre‐stressing

AbstractAn additional process step in the production process chain of steel components, the thermal induced pre‐stressing, has been developed. This new process step enables the manipulation of the distortion potential of the components before it is released in the hardening process at the end of the process chain. In order to predict the final distortion of the component in dependence on the process parameters of the thermal pre‐stressing a simulation model has been developed, which also includes the final heat treatment (hardening process). The model accounts for the stress and deformation due to the generation of thermal strain as well as those due to phase transformations. A first implementation was done using the geometry of an idealized gear wheel tooth (finger sample). After optimization, with special focus on the calculation time, the application for realistic gear wheel teeth has been implemented.

Developement of Mathematical Model for Detection of Cracks in Tooth Root Using an Adaptive Algorithm

This paper presents a control and diagnostics model of single stage gear wheels using acoustic responses. The model is based on various methods and procedures that provide information about the generator’s condition and, specifically, its service life. Four procedures are combined in this model: the mathematical module of the gear wheel that translates the complete mechanical module into mathematical form, the adaptive FIR (Finite Impulse Response) filter that calculates impulse responses from the non-linear system, the module for calculating any impulse response, and the FFT (Fast Fourier Transform) frequency analysis used for simulating frequency spectrums. The result of the simulation is the sound frequency spectrum that allows the analysis of gear wheel tooth damage and, based on this spectrum, calculation of the remaining service life and/or the maintenance process.

Prediction of the wear pattern in worm gears

The paper is concerned with the prediction of the detailed pattern of wear, which takes place on the teeth of worm gear wheels under lubricated conditions. The wear model adopted is based on a published empirical standard, which includes the effect of fluid film thickness in the form of a lambda ratio parameter (film thickness/RMS roughness). The analysis is based upon a full elastohydrodynamic lubrication (EHL) solution in which the detailed distribution of wear on the tooth surfaces during meshing is summed to determine the calculated wear per meshing cycle. The calculated wear is then used to modify the unloaded geometry of the tooth surfaces, and the EHL and wear calculations are repeated in a series of “wear steps”. Results are presented that show the way in which the pattern of wear develops to produce the wear scars seen on the teeth of gears in practice.

Vectorial theory of gear wheel tooth profiles

The mechanical problem of the admissible gear tooth profiles is treated by a method using the geometry of the complex plane. This method is better known in the electrical branch of technical science, but may — as is shown in this paper — easily be generalised to a complete version of plane geometry and applied to mechanical problems.

Electrical Industry and Research

SEVERAL notable developments have taken place in the research laboratories of the Metropolitan Vickers Electrical Co., Ltd., during the past year. The investigations on the ‘creep’ or deformation of metals under stress at high temperatures have led to definite results which are of importance in mechanical engineering. It has been proved that even at the lower stresses and temperatures of turbine practice steels cannot be regarded as permanently elastic materials. They are subject to gradual stretch or other permanent distortion. A quick method of testing steels has been developed in the laboratories, and thoy can now be placed in order of merit after a duration test of only a few days.‘Creep’ tests as ordinarily applied may last for months. A particular sample was subjected to test for twelve months and was found to creep at the rate of one part in a hundred million per hour. For the next two months, however, after the year was completed, it only increased at a tenth of this rate. The limit of sensitivity of the apparatus has now been reached, but it is not yet possible to say definitely that creep has ceased. If we consider a turbine cylinder 100 inches in diameter and subject to a rate of increase of one part in a hundred million per hour over a period of ten years, its diameter would have increased by nearly one-tenth of an inch, and this increase would seriously limit the life of the turbine. Other useful mechanical researches are being made in the laboratory as to the effect of surface hardening on the fatigue resistance of gear-wheel teeth. The results obtained are of great use in designing the best driving gears for electric trams and locomotives.