Gear Accuracy Research Articles

Precision Distribution of Turntable Gear Transmission System of Aero-engine Blade Processing Machine

In the previous design and research on the gear transmission error of the five-axis machine turntable, the selection of the five-axis machine tool turntable gears mainly uses the high-precision gears to avoid excessive transmission errors of the turntable, to meet the design requirements of the turntable. However, the cost of the turntable manufacturing is increased and it causes excess precision and unnecessary waste. In meeting the requirements of accuracy, it is important to distribute the gear transmission error of the turntable reasonably, to avoid the high manufacturing cost of the five-axis machine, improve the technical quality of the five-axis machine turntable and reduce its cost. This paper presented the self-developed five-axis machine turntable for aero-engine blade processing as the carrier, and the optimized genetic algorithm is used as the tool to allocate the precision of the gear transmission system. While to meet the design and use requirements, the gear accuracy level is reduced. The manufacturing cost of the turntable goes down.

The use of polymer composite materials in cylindrical gears

The paper describes the use of PCM-polymer composite materials in the construction of cylindrical gears. Various types of composite materials and their characteristics for gear links of cylindrical gears, in particular with an asymmetric profile, as well as shell forming matrices for their manufacture from PCM are considered. The main issues of ensuring the accuracy of PCM gears for assessing their quality level are presented.

Geometric analysis of injection-molded polymer gears (Rapid communication)

Properties of polymer gears were tested using coordinate measurement methods. This study is a follow-up to research on geometric accuracy of gears manufactured by injection molding. Spur gears were measured on a coordinate measuring machine running the GINA software by Klingelnberg. Measurement results were output in the form of measurement sheets which included values required in the DIN 3962 standard. The article also analyses the topography of test gear teeth. The topography was presented for a single tooth of the gear and determined on the basis of the measurements of 9 profiles distributed evenly over a specific profile assessment interval (interval Lα defined in the standard) and 7 tooth traces located within a relevant tooth trace assessment interval (interval Lβ defined in the standard). All gears tested in this study were placed outside accuracy class 12.

Multiple Response Optimization of Dimensional Accuracy of Nimonic Alloy Miniature Gear Machined on Wire Edm Using Entropy Topsis Andpareto Anova

The purpose of this research is to obtain the optimum cutting parameters to achieve the dimensional accuracy of Nimonic alloy miniature gear manufactured using Wire EDM. The cutting parameters investigated in this study are current, pulse on time (PON), pulse off time (POFF), wire tension (WT) and dielectric fluids. Ethylene glycol, nanopowder of alumina and oxygen are mixed to demineralized water to prepare novel dielectric fluids. Deviation in inner diameter, deviation in outer diameter, deviation in land and deviation in tooth width are considered to check the dimensional accuracy. Taguchi L16 is employed for experimental design and multiple response optimization is performed using Entropy TOPSIS and Pareto ANOVA. Results indicate that pulse on time is the most notable parameter for good dimensional accuracy followed by dielectric fluid, current, pulse off time and wire tension. Ethylene glycol mixed demineralized water is preferred for low dimensional deviation. The optimum WEDM parameters are pulse on time at 20 μs, Ethylene glycol mixed demineralized water dielectric fluid, current at 3 A, pulse off time at 4 μs, and wire tension at 18 N.

The Influence of Pulling Up on Micropitting Location for Gears with Interference Fit Connections of Their Conical Surface

Micropitting is a surface fatigue phenomenon that occurs in Hertzian type of rolling and sliding contact that operates in elastohydrodynamic or boundary lubrication regimes and can progress both in terms of depth and extent. If micropitting continues to propagate, it may result in reducing gear tooth accuracy, increasing dynamic loads and noise. Eventually, it can develop into macropitting and other modes of gear failure such as flank initiated bending fatigue. Micropitting has become a particular problem in the gear surface fatigue. Usually micropitting initiates in the dedendum of the driver and driven at the asperities on the surface. However, the authors found for some gears with interference fit connections of their conical surface, micropitting on the pinion occurs in the addendum. This study attempted to find the reason using a 3D–TCA method based on ISO/TR 15144-1 to predict the micropitting and try to understand the key influence likely to affect micropitting location.

A measurement method for tooth surface errors of straight bevel gears based on 3D model

Due to the inconsistency between a theoretically designed tooth surface and the actual measured reference surface, the tooth surface error data obtained by the traditional measurement method is unreliable, and incorrectly reflects the machining accuracy of straight bevel gears. This has become a key problem in the current measurement process, and needs to be resolved. In this paper, a new measurement method is proposed to achieve accurate measurement and evaluation of the machining error of straight bevel gears. The 3-dimensional (3D) model surface designed by the manufacturer is directly extracted as a theoretical reference to complete the measurement, which ensures the correctness of the error results. A measurement strategy of normal rotation of the measured point is adopted to make up for the disadvantages of the one-dimensional (1D) probe and improve the measurement accuracy. The problem of the sensitive direction of the probe deviating from the normal direction is compensated for by increasing the dimension of the 1D probe and reducing the dimension of the 3D normal. According to the constructed error calculation model, the minimum tooth surface error is obtained through reconstruction and optimal matching techniques. Finally, the accuracy and effectiveness of the measurement method are verified through measurement comparison experiments. This method solves the technical problem of the inconsistency of the measured reference surface, and uses a low-cost 1D probe to achieve precise measurement of the 3D surface. It not only improves the disadvantages of current measurement methods, but also provides effective technical support for other gear measurements.

Influence of elastic deformation of gear hone teeth on machined gear accuracy

The material of resin-bond gear hones becomes deformed during operation. The gear hone tooth deformation value depends on the contact point position along the tooth height; it increases by ten folds from the lower point to the top. The deformation values are comparable with metal removal volume and the initial error values of the machined parts. Besides, the kinematic parameters of engagement vary, the values of specific sliding and contact pattern areas are distributed along the part teeth height more uniformly. This should affect the nature and the correction values of gear errors after machining. Experiments proved that accuracy of gears after machining by hones depends on the initial accuracy degree of gears and hones, the paired relationship of geared contacts, the value and nature of distribution of the gear-teeth initial error, machining time. Errors can be intentionally rectified by using gear hones with various elasticity degrees depending on the initial accuracy of parts.

Effect of laser beam cutting parameters on productivity and dimensional accuracy of miniature spur gears of stainless steel

Product quality and process productivity are one of the major indicators to evaluate the performance of any manufacturing process. The quality of any product covers its appearance, geometric and dimensional accuracy, and surface finish and integrity that majorly include microstructure, micro-hardness type of parameters. Whereas, the productivity can be determined using material removal rate. Laser beam cutting is an important advanced machining process and has been scarcely explored for miniature gears. This paper reports, the effect of laser beam cutting parameters on one of the quality parameters i.e. dimensional deviation of miniature spur gears of stainless steel and material removal rate. Box Behnken design of experiments methodology has been adopted to conduct a total of twenty nine experiments where four important laser parameters i.e. power, cutting speed, focal position, and gas pressure have been varied at three levels each. The manufactured external spur gear of stainless steel consists of ten teeth, 0.750 module, 9.04 mm outside diameter, and 4.5 mm face width or thickness. The investigation found that cutting speed significantly affected material removal rate and laser power affected dimensional deviation. Individual effects of laser parameters on both material removal rate and dimensional deviation are discussed in detail in the chapter. The investigation identifies laser beam cutting as a viable substitute of conventional manufacturing processes for fabrication of quality miniature gears with high productivity.

Research on multitask fault diagnosis and weight visualization of rotating machinery based on convolutional neural network

Recently, deep learning methods such as convolutional neural networks (CNN) have been widely used in fault diagnosis of rotating machinery. However, most methods are not designed to consider the influence of the working conditions and limited to classifying several fault types. In this paper, we propose two CNN-based multitask models, i.e., sigmoid multitask fault diagnosis model and multisoftmax multitask classification model, which can classify the fault types and the working conditions of the signal simultaneously. All samples are jointly learned at the shared network layers, and different types of learning tasks are completed at different subnetwork layers. Results show that the proposed sigmoid multitask fault diagnosis model achieves the overall classification accuracy of 96.8% when testing the CWRU bearing dataset. The proposed multisoftmax multitask classification model is used to classify different working conditions and fault types of planetary gearbox. With frequency signals as inputs, the accuracy rate is able to reach 96.2%, and the classification accuracy of gear and speed conditions reaches more than 99%. Additionally, the gradient-weighted class activation mapping (Grad-CAM) method is used to visualize the weight vectors of different convolutional layers and locate the signal segment of interest to the model.

Prediction of injection molding parameters for symmetric spur gear.

Polymer gears pose major advantages, like noiseless operation, resistive against corrosion, low weight, ability to damp vibrations, ease of manufacturability, and ability to operate without lubrication like in printers, household appliances, etc. In order to enhance mechanical properties of gear materials, various reinforcing materials are added such as glass and carbon fibers. The orientation of these fibers and distribution are critical parameters at the microstructural level for polymer reinforced with short fibers, which defines the strength and life of gears. The geometric accuracy and precision of molded gears are improved by the injection molding technique. The fiber orientation prediction is a new and novel aspect for high performance and life, as these injection-molded gears have complex patterns of fiber orientation. This also affects material properties such as elastic modulus, strength, and gear geometrical dimensional properties shrinkage and warpage. In this present work, an attempt is made to develop 3D symmetric spur gear tooth geometry using Autodesk Fusion 360. The injection molding parameters such as fiber orientation tensor, volumetric shrinkage at ejection, weld lines, deflection, and confidence in filling are studied for modeled gear having symmetric teeth profile for unreinforced and 20%, 30%, 40%, 50%, and 60% glass fiber-reinforced nylon 6/6 (PA66) by using Autodesk Moldflow Adviser 2017. The result obtained from mold simulation tool indicates that fiber orientation tensor for varying glass fiber contents was close to unity. The volumetric shrinkage considerably reduced from unreinforced PA66 to glass-reinforced PA66.Graphical abstract.

Analysis of End-Effect Force and Weakening Method for Permanent Magnet Toroidal Motor

In the research of torque ripple of permanent magnet toroidal motor (PMTM), the planet gears are affected by the end-effect force during its rotation due to the special structure of the central worm stator. The existence of the end-effect force will cause vibration and noise, which will lead to poor operation accuracy of the planet gears. In view of the above problems, the formation mechanism of the torque ripple is analyzed. We point out that the sudden change in the magnetic induction intensity at the end of the central worm stator is the main source of the end-effect force. The Schwarz-Christoffel transformation method is used to analyze the magnetic field distribution at the end of the stator. The mathematical model of the end-effect force of PMTM is derived by applying Maxwell stress tensor method. The influence of the structural parameters on the end-effect force of PMTM is analyzed by finite-element simulation. The results show that the output fluctuation of PMTM can be effectively reduced by choosing the optimal wrap angle of the central worm stator by calculating. In addition, choosing the appropriate polar arc coefficient of the planet gears can further reduce the influence of the end-effect force. These research results can provide important reference for the structural optimization of PMTM.

The research of oil film thickness on the gear tooth surface: A review

Increasingly demanding performance standards and operating requirements are driving the growing interest on the influence of gear oil film on reliability under the condition of high speed and heavy load. The fatigue life of gears can be increased by optimizing the oil film thickness on the gear tooth surface. The oil film thickness can reflect the ability of the gear to resist pitting and gluing failure. Many theories and experiments are devoted to the study of the oil film thickness. The improvement of gear manufacturing accuracy also makes the influence of tooth surface roughness on oil film thickness not negligible. In order to compile and categorize key investigations in an expansive field with substantial recent research, this work reviews oil film thickness with focus on numerical calculation methods, influence of gear surface roughness on oil film thickness and fatigue life analysis based on oil film thickness.

Rationality and possibility of automation of precision calibration of gears

The main factors that determine the accuracy and quality of the ring gear during precision calibration are described. The corresponding ACS (automated control system) schemes are proposed.

Influence on center distance by measurement force in double-flank gear rolling test

Double-flank gear rolling test is widely used in high speed gear measurement in workshop, but the measurement results may be influenced by measurement force. An algorithm is proposed for gear tooth radial deformation by measurement force in the test. The numerical results calculated in MATLAB considers different measurement forces and materials. Finite Element Method (FEM) used analyzes the radial tooth deformation under the influence of the measurement force. The maximum difference of radial deformation between the two methods is 0.1 μm. Experiments are carried out on a tester under different measurement force varying from 0.5 N to 4 N. The variation of tooth-to-tooth radial composite deviation is 3.0 μm, while the variation in MATLAB is 6.12 μm. Compared to ISO 1328–2:1997, the product gear accuracy grade deviates from grade 11 to 10. The algorithm proposed can be used to calculate gear radial deformation influenced by measurement force in double-flank gear rolling test.

Accuracy of Geometry of Plastic Gear Produced with 3D Printing Technology

The article concerns the accuracy of the geometry of a single-stage gear made of plastic with 3D printing technology. The aim of the paper has been to assess the accuracy of gears made by 3D printing methods. The accuracy assessment has been made in relation to the accuracy of the same steel gears made by machining. Gear virtual solid models, necessary for using 3D printing technology, have been created based on steel gear using Reverse Engineering Technique. Plastic gears have been printed with two 3D Printing methods: Selective Laser Sintering (SLS) and Multi Jet Modeling (MJM) from plastics used in these methods. Gear geometry has been measured using a measuring machine. In order to determine the manufacturing accuracy, the accuracy classes of the geometrical parameters of gear have been used. It has been found out that the manufacturing accuracy for both 3D Printing technology methods is similar but worse than for machining. The obtained results of gears accuracy made by SLS and MJM methods correspond to the International Tolerance (IT) grade 12 or higher. Milling process produce the IT grades indicated. The originality of the work is the study of the accuracy of gears geometry made using two different 3D printing methods. The test results obtained are the basis for conducting research on the impact of individual parameters of 3D printing technology on gears accuracy.

Investigation of GFRP Gear Accuracy and Surface Roughness Using Taguchi and Grey Relational Analysis

Glass fiber reinforced polymer (GFRP) composite gear is used in a number of applications where fine motion transmission and silent rotation is required. In order to increase its usage there is a need to increase the quality of gear. Shrinkage problem is associated with injection molded gear. In present case blank is prepared by injection molding and teeth are cut on gear shaper by which metrology can be controlled by optimizing the machining parameters. An analysis of variance was applied on 27 experiments to validate the process and found out that rotary feed is at rank 1 which is 0.15[Formula: see text]mm/stroke, cutting fluid ratio is at rank 2 which is 12%, cutting speed is at rank 3 which is 240 stroke/min, fluid flow rate is at rank 4 which is 30 ml/min. By using these parameters optimum performance obtained is 0.213[Formula: see text]mm root diameter deviation (RD), 0.165[Formula: see text]mm tooth thickness variation (TT) and 1[Formula: see text][Formula: see text]m roughness average (Ra) with grey relational grade of 0.8318. The optimum response provided the best value of RD, TT and Ra for the range included in experimental results which is 0.138 to 0.416[Formula: see text]mm, 0.012 to 0.187[Formula: see text]mm and 1.2 to 2.43[Formula: see text][Formula: see text]m respectively. Surface roughness improvement in this work is 49.8% higher as compared to result available in literature.

Meshing contact analysis of cycloidal-pin gear in RV reducer considering the influence of manufacturing error

The manufacturing error of cycloid gear is the key factor affecting the transmission precision and meshing characteristics of cycloidal-pin gear in RV reducer. Taking the RV cycloidal-pin gear pair transmission as the object, a meshing contact analysis method is proposed for RV cycloidal-pin gear transmission considering the influence of manufacturing error. The modified tooth profile of cycloid gear is effectively superimposed and transformed by taking the influence of tooth profile and pitch errors of cycloidal gear into consideration, and the theoretical contact analysis model of cycloidal-pin gear transmission is established. By analyzing and solving the meshing contact model, the characteristic parameters such as the meshing point position, meshing backlash and transmission error of cycloidal-pin gear between the meshing contact surfaces are obtained under the influence of manufacturing error, and the effective pre-control of the tooth profile and the meshing contact performance is realized. The verification analysis results show that the manufacturing error has a great influence on the transmission accuracy of RV cycloidal-pin gear, among which the tooth pitch error has the greatest influence on the transmission error, which is in a positive proportion. And the influence of tooth profile error on transmission error is second. The meshing contact analysis method considers the interactive influence of the manufacturing error and modification shape of tooth profile on the meshing contact status of RV transmission; the cycloidal tooth profile can be obtained which is more suitable for engineering practice. This analysis method can provide the theoretical support and technical means for profile modification design, motion accuracy improvement and load-bearing contact analysis of RV transmission.

A New Tooth Profile Modification Method of Cycloidal Gears in Precision Reducers for Robots

The tooth profile modification of cycloidal gears is important in the design and manufacture of precision reducers or rotary vector (RV) reducers for robots. The traditional modification design of cycloidal gears is mainly realized by setting various machining parameters, such as the size and center position of the grinding wheel. The traditional modification design has some disadvantages such as complex modification calculation, uncontrollable tooth profile curve shape and unstable meshing performance. Therefore, a new tooth profile modification method is proposed based on the consideration of the comprehensive influences of pressure angle distribution, meshing backlash, tooth tip and root clearance. Taking the pressure angle and modifications of tooth profile as the parameters of the modification function and the meshing backlash of gear teeth as constraints, the mathematical model for tooth profile modifications is built. The modifications are superimposed on the normal direction of the theoretical profile—the force transmission direction. The mathematical relationship between the modifications and the pressure angle distribution, which determines the force transmission performance, is established. Taking the straight line method, cycloid method and catenary method as examples, by means of the tooth contact analysis technology, the transmission error and minimum meshing backlash, which reflects the lost motion, of the newly modified profile are analyzed and verified. This proposed method can flexibly control the shape change of the modification profile and accurately pre-control the transmission accuracy of the cycloid-pin gear. It avoids the disadvantages of traditional modification methods, such as uncontrollable tooth profile shape and unstable meshing accuracy. The method allows good meshing characteristics, high force transmission performance and more precise tooth profile curve. The study provides a new design method of the modified profile of cycloidal gears.

Determination of transformation plasticity coefficient of steel by horizontal quenching of shaft

Shape accuracy of steel gears and shafts depends on the heat treatment distortion in the oil quenching condition of those parts. The distortion is mainly caused by the inhomogeneous cooling in oil quenching. The deformation by heat treatment can be estimated by the numerical simulation considering transformation plasticity. The key material property for the simulation is the transformation plasticity coefficient. The coefficient is conventionally measured by tensile or bending test under controlled temperature and stress, however the determination of the coefficient is not easy. In this study, the authors propose a simple method to determine the coefficient using horizontal quenching of a steel shaft. Horizontal quenching tests of chrome steel shafts were conducted to demonstrate inhomogeneous deformation by experiments and numerical simulations. The specimen was uniformly heated at 850 °C, and then quenched into oil with 100 °C. The direction of deflection has changed depending on the diameter of the specimen. Through the comparison between the predicted deformation by simulation and the experimental results, the transformation plasticity coefficients were determined as 3.0 x 10-5 MPa-1 (austenite -> martensite) and 4.0 x 10-5 MPa-1 (austenite -> bainite).

Effects of Heat Treatment Techniques on the Fatigue Behaviour of Steel Gears: A Review

Heat treatment of gears are fundamental to efficient and reliable gear production because of its contribution to the overall cost of manufacturing. Different heat treatment techniques are targeted to improving hardness, ductility and strength to minimize material degradation or wear. However, several heat treatment methods had led to gear tooth distortion such as shrinkage of tooth thickness which eventually affects the contact angle. The study therefore focused on some selected heat treatment on gears and their effects on gear applications. from the reviewed heat treatment techniques, distortion is a common occurrence that result to gear fatigue. Also, it was noted that most times, the medium for quenching and most importantly, variation in the concentration affects the gear accuracy. Thus, local fracture and material loss ensue. Nevertheless, the study further suggested the use of empirical model and simulation approach for stress prediction.