Gear Manufacturing Research Articles

The Concept of Technological Support of Operational Properties Based on Stabilization of Mechanical Properties of Gear Materials in a Gas Turbine Engine Drive System

Modern production of gears for gas turbine engines for aviation, marine and land use is inherently related to the calculation of the stress state of the working surfaces of the mating teeth. To create conditions for the operability of the gear train and the drive system as a whole, an engineering analysis of the contact endurance of the mating surfaces is a necessary criterion. The contact strength determines the life of the gear mechanism. The value of the contact strength, taking into account its distribution in the contact zone of the working mating surfaces of the gears, is determined by the processing technology and operation, but the mechanical properties and texture of the material have the greatest influence. This determines the requirements for the stability of the mechanical properties of the materials used for the manufacture of gears, making a topical question on their study. The technology of manufacturing the gears in the gas turbine engine drives forms the layer structure of the toothed crown because of the use of chemical-thermal treatment. The surface hardened layer of the gear tooth after chemical-thermal treatment is saturated with carbon and nitrogen, and as a result of thermal action acquires mechanical properties and structure different from the material in the supply. The paper presents the results of practical research of evolution of mechanical properties of structural steels 20H3MVF-Sh, 18H2N4MA, 16H3NVFM-Sh and 12H2N4A-Sh based on various types of chemical-thermal treatment, as well as microstructure of toughened layer and core of the part. The steel mechanical properties stabilization evaluation in the process of gear technology was performed. The presented results of experimental studies of mechanical properties of the material prove stabilization of mechanical and structural indicators, which are responsible for the contact strength of the mating surfaces of toothed gears.

Dynamic Testing and Fatigue Analysis of the I-31P Nose Landing Gear

Abstract The landing gear is a critical safety component of any aircraft, playing a key role in managing the significant loads experienced during landing and ground maneuvers. In the case of the I-31P aircraft, a redesign of the I-23 landing gear system, required comprehensive testing to validate its performance, after change of landing gear parts manufacturer and minor updates to materials and technologies. This study focuses on the dynamic testing of the I-31P nose landing gear (NLG), particularly to assess its energy dissipation and fatigue resistance under operational conditions. Dynamic tests, performed in accordance with CS-23 standards, utilized strain gauges to monitor potential stress concentrations, especially on the half-fork design. Results demonstrated that the I-31P nose landing gear meets the required safety standards, with key performance metrics such as deflection and load factors within acceptable limits. The findings also highlighted the importance of continued monitoring for potential fatigue issues, offering valuable insights for future design enhancements.

Deep learning of 3D point clouds for detecting geometric defects in gears

Geometric integrity directly impacts the functionality, reliability, and safety of final manufactured products, making the qualification of parts based on measurements of their geometry a fundamental quality control activity in modern manufacturing. Recent advancements in three-dimensional (3D) metrology technologies have enabled fine-scale inspection of geometric integrity characterized by dimensional accuracy, surface quality, and shape conformity. However, the widespread adoption of high-resolution 3D metrology in manufacturing faces some significant challenges posed by the inherent data structures of 3D point clouds such as high dimensionality, unstructured nature, and sparsity in defective regions. To address these challenges, this paper first creates a “MFGNet-gear” dataset, which is a scalable and comprehensive benchmark dataset comprising 12 part designs with four quality classes for each design. Subsequently, we develop a deep learning model adapted from the PointNet++ architecture to enable automated, end-to-end analysis of 3D point clouds. The model can be configured for different decision-making tasks including part design classification and multi-class geometric defect detection. Implementations of the proposed model on the “MFGNet-gear” dataset achieve accuracies up to 100% in classifying gear designs and up to 85% in four-class quality inspection. Additionally, we systematically investigate the impacts of measurement resolution and precision on the classification performance through a series of case studies. The obtained results highlight the potential of using deep learning methods for automated analysis of 3D point clouds for a variety of quality control tasks beyond gear manufacturing. This study also proposes future research directions, including the development of new deep learning architectures specifically designed for manufacturing 3D point clouds and strategies for adaptive measurement planning.

Calculation of the inverse involute function and application to measurement over pins

Abstract Measurement over pins plays a crucial role in ensuring the quality of gear manufacturing, which requires the evolution of the inverse involute function. In this paper, an efficient algorithm for calculating the inverse involute function is proposed. Firstly, the initial approximate solution of the pressure angle near 0 rad is established by using Padé approximation and one step of Schröder iteration. Then, the involute equation is transformed into another form by introducing a variable transformation, and the initial approximate solution of the pressure angle near π / 2 rad is constructed by using the same method. A piecewise initial approximate solution over the entire interval of expanded angles is obtained by combining these solutions. Again, the accuracy of the initial approximate solution can be significantly improved by using one step of Schröder iteration. A numerical example of a two-pin measurement is presented to demonstrate the superiority of our method over traditional iterative approaches. The algorithm is highly efficient and accurate, and is a useful tool for designers to accurately calculate gear systems.

Multi-physics field coupling interface lubrication contact analysis for gear transmission under various finishing processes

Surface integrity is crucial for the load-bearing capacity, transmission performance, and service life of gears. Finishing processes can effectively improve surface quality and are widely used in gear manufacturing processes to enhance surface integrity and improve the service performance of gears. Five precision machining tests of form grinding, vibratory finishing, barrel finishing, honing, and abrasive flow machining were conducted on spur gears. High-precision surface integrity characterization methods were used to analyze the surface integrity parameters of the finished gear surfaces, including surface roughness, surface microtopography, residual stress, texture aspect ratio, roughness peak curvature radius. The finishing processes uniformity and effectiveness of the tooth profile surface were also evaluated. By using the finished rough surfaces as inputs and considering the impact of thermal elasto hydrodynamic lubrication on the gear surface, a multi-field coupling contact analysis model encompassing solid, liquid, and thermal fields at the gear meshing interface was established. Lubrication performance parameters such as oil film pressure, oil film thickness, oil film temperature rise, and friction coefficient under various finishing surfaces were compared and analyzed. Experimental results indicate that barrel finishing can simultaneously improve various parameters, such as surface roughness, texture aspect ratio, and compressive residual stress. Finishing processes can effectively reduce surface roughness, improve lubrication performance and reduce the risk of scuffing failure. This approach provided an effective method for the comprehensive evaluation of the effects of various finishing processes. The developed program offers theoretical guidance and data support for the selection and optimization design of gear surface finishing processes.

Modelling width of the spectral component of a gas-turbine engine gearbox output shaft speed

Gearbox is the most stressed component in an aircraft gas-turbine engine. This implies the need for finding ways to monitor its technical condition. Practice shows that the most efficient method is vibration-based diagnostics. However, this method requires the use of sophisticated measurement systems and highly skilled personnel. This paper shows that errors of gear coupling manufacture and assembly, characteristics of machine operating mode, design factors, frequency modulation of the carrier of the engine rotor speed in the stationary mode of its operation, and wear of teeth flanks determine the width of the spectral component of the gearbox output shaft speed. Using the results obtained from the developed model of the width of gear tooth spectral component, ratios for width of the spectral component of the signal of the “standard” tachometric speed sensor of the gearbox output shaft speed and the corresponding spectral component of its vibration were obtained. Models for repaired and newly manufactured gearboxes and gearboxes with tooth flank wear were proposed. This allowed the development of a number of new diagnostic indicators of a defect. Several examples of the use of these new diagnostic indicators are given for the gearbox of one of turbo-prop engines. The results obtained provide an opportunity to assess the gearbox technical condition in operation.

Gear Hobs-Cutting Tools and Manufacturing Technologies for Spur Gears: The State of the Art.

The present work aims to provide the readers with a bird's-eye view of the general domain of cylindrical gear manufacturing technologies, including the cutting tools used, and related topics. The main scientific sources are explored to collect data about the subject. A systematization of the scientific works is completed, to emphasize the main issues the researchers have focused on in the past years in the domain. Several specific aspects are investigated: chip-forming process, cutting tool lifetime, the materials used to produce gear hobs, temperature and lubrication, the cutting tool geometry, cutting parameters, design methods, and optimization. Some gaps in the research have been identified, which are mainly related to the gear hob's design. These gaps, the organization of knowledge, the current requirements of the industry, and the actual socio-economic priorities form the basis for identifying new scientific research directions for the future in the area of spur gears manufacturing technologies and cutting tools. The main output of this work is a frame to guide the development of scientific research in the domain of spur gear production.

Addendum To: Manufacturing of spur gears having normal teeth on different pressure angles by module disc milling cutter

Addendum To: Manufacturing of spur gears having normal teeth on different pressure angles by module disc milling cutter

Relationship between firefighter protective clothing design ease and heat stress

PurposeClothing fit, including garment ease and drape, impacts the volume of air between clothing layers and the body, directly affecting the amount of heat that can be transferred through a multi-layer clothing system. As most acute firefighting fatalities are caused by overexertion and heat strain, the purpose of this research was to determine the impact of ease allowances on air gaps in structural firefighting turnout suits and their subsequent effect on total heat loss (THL) when worn on a three-dimensional form.Design/methodology/approachFour turnout suits with chest ease allowances of 6″, 8″, 10″ and 12″ were evaluated using an ANDI dynamic sweating thermal manikin. The average predicted manikin THL of each ensemble was calculated from the thermal and evaporative resistance measurements. A three-dimensional (3D) body scanner was utilized to calculate the distance and volume of clothing air gaps between the base layer and each turnout suit.FindingsResults demonstrate that reductions in upper body ease measurements trend towards statistically significant increases in THL, to a point, with fit limitations being reached before benefits can be significantly realized. An increase in standard chest ease measurements significantly decreased heat loss, even when forced convection from movement was considered.Originality/valueThis is the first article of its kind to explore the relationship between garment ease and predicted manikin THL, especially for fire service protective clothing. Findings indicate a valid recommendation for turnout gear designers and manufacturers to optimize clothing fit to improve breathability and potentially reduce incidents of heat strain in the fire service.

A virtual measurement method for evaluating the gear radial composite deviation based on point cloud data

Radial composite deviation is an important index to evaluate the precision of gear transmission, and its detection method is also an important trend of gear detection in industrial development. The ability to predict radial composite deviation while obtaining geometric deviation of gears is a key challenge in advancing intelligent online inspection within gear manufacturing workshops. This study presents a virtual measurement method for determining gear radial composite deviation using point cloud data. The method involves using an optical three-dimensional scanner to capture tooth surface cloud data, determining tooth profile deviation, and applying reverse engineering technology to reconstruct the gear model, the variation curve of gear center distance is determined by simulating, allowing for the calculation of the total radial composite deviation and tooth-to-tooth radial composite deviation. In comparison to actual measurement, the virtual measurement method is generally reliable. It can effectively illustrate the overall trend of center distance variation and has good interpretability for predicting radial composite deviation results. This method reduces the dependence on the specialized gear measuring instrument and addresses the critical issue of simultaneously obtaining tooth profile deviation and radial composite deviation.

New deterministic model for calculating mesh stiffness and damping of rough-surface gears considering elastic–plastic contact and energy-dissipation mechanism

For a long time, meshing parameter calculations and dynamic modeling of gear systems have assumed smooth tooth surfaces, disregarding the impact of actual three-dimensional (3D) microscopic topography. Based on elastic–plastic contact and energy-dissipation mechanisms, this work developed a comprehensive deterministic model that integrates 3D rough surface modeling, reconstruction, and contact analysis, for calculating the time-varying mesh stiffness (TVMS) and mesh damping (TVMD) of deterministic rough-surface gears. Distinct from fractal and statistical models, the deterministic model analyzes deterministic, real 3D rough surfaces rather than simple surfaces defined by a few parameters. Utilizing stochastic process theory, different-topography surfaces are obtained using height and spatial features and reconstructed employing watershed algorithm and ellipsoidal asperity fitting. Subsequently, a deterministic elastic–plastic contact model based on equivalent rough curved-surface contact is constructed, emphasizing local contact states and energy dissipation for calculating contact stiffness (CS) and damping (CD) of gears. Accordingly, a meshing characteristics analysis model is established for calculating TVMS, TVMD, and load sharing ratio (LSR). Experimental validation and comparisons with several statistical and gear contact models demonstrate the effectiveness, reliability, and superiority of the proposed deterministic model. Multi-parameter impact analysis reveals small Sq (meaning low roughness Sa) and Ssk and high load correlate with increased CS and TVMS, while CD and TVMD depend on their interaction and hardness. Overall, by bridging the micro-surface topography and macro-meshing parameters, our model provides essential insights for the design and manufacturing of high-performance gear to reduce vibration and noise.

MODELLING AND 3D-PRINTING OF BEVEL GEAR

Bevel gear have teeth cut on conical blanks. The gear pair is used to connect non-parallel intersecting shafts for motor transmissions, differential drives and mechanical instruments. Bevel gears are used for transmission of power between axles in rear wheel of vehicle will be modelled by using solid works. Shaping, Casting and Grinding are the traditional methods of manufacturing of bevel gear which are time consuming, and increased in production cost. To overcome this, new method such as rapid prototyping method of manufacturing is used which offers the potential for faster and more cost-effective manufacturing with ability to customize the design and improve performance. In this project, the Bevel Gear is designed using solid works by ensuring that the gear's dimensions and tolerances are appropriate for the 3D printing process being used and then the Bevel Gear is printed using the 3D- Printer. Keywords: Bevel Gear, 3D Printing,Rapid Prototyping, Design

Rear Axle Whine Reduction by Gear Contact Patch Optimization

In-cab whine is a highly annoying phenomena in all the category of vehicles. The in-cab noise of passenger vehicle with Rear Wheel Drive ( RWD) considered for this study consist of axle whine noise. The whine noise is heard at multiple speeds during Wide Open Throttle (WOT) as well as coasting. To resolve the issue of whine noise, series of measurement are carried out to identify the source and transfer path of the whine. The noise measurement revealed that rear axle pinion mesh order is responsible for in-cab whine. It is confirmed through measurement that the whine is structure borne. The order based operational deflections shapes of rear axle show excessive vibration on differential nose in affected speed zones. It is thus learnt that whine is due to poor contact pattern of pinion and crown wheel of the rear axle. The three resonances in operation range amplify this mesh order resulting in whine. It is decided to work on noise source i.e. gear rather than transfer path. The hypoid gear design is optimized through Tooth Contact Analysis (TCA). The lapping and heat treatment processes of gear manufacturing are modified. The contact pattern of optimized gear is identified on gear tester machine. Significant improvement is observed in contact pattern. The in-cab noise measurement is carried out with optimized hypoid gear and it is found that the whine is completely eliminated.
 Keywords: Rear axle, Whine reduction, Gear contact, Patch optimization, Rear Wheel Drive, Whine Source, Vibration on Transfer Paths, Noise Generation, Hypoid Gear, Heat Treatment

Machine learning for monitoring hobbing tool health in CNC hobbing machine

Utilizing Machine Learning (ML) to oversee the status of hobbing cutters aims to enhance the gear manufacturing process’s effectiveness, output, and quality. Manufacturers can proactively enact measures to optimize tool performance and minimize downtime by conducting precise real-time assessments of hobbing cutter conditions. This proactive approach contributes to heightened product quality and decreased production costs. This study introduces an innovative condition monitoring system utilizing a Machine Learning approach. A Failure Mode and Effect Analysis (FMEA) were executed to gauge the severity of failures in hobbing cutters of Computer Numerical Control (CNC) Hobbing Machine, and the Risk Probability Number (RPN) was computed. This numerical value aids in prioritizing preventive measures by concentrating on failures with the most substantial potential impact. Failures with high RPN numbers were considered to implement the Machine Learning approach and artificial faults were induced in the hobbing cutter. Vibration signals (displacement, velocity, and acceleration) were then measured using a commercial high-capacity and high-frequency range Data Acquisition System (DAQ). The analysis covered operating parameters such as speed (ranging from 35 to 45 rpm), feed (ranging from 0.6 to 1 mm/rev), and depth of cut (6.8 mm). MATLAB code and script were employed to extract statistical features. These features were subsequently utilized to train seven algorithms (Decision Tree, Naive Bayes, Support Vector Machine (SVM), Efficient Linear, Kernel, Ensemble and Neural Network) as well as the application of Bayesian optimization for hyperparameter tuning and model evaluation were done. Amongst these algorithms, J48 Decision tree (DT) algorithm demonstrated impeccable accuracy, correctly classifying 100% of instances in the provided dataset. These algorithms stand out for their accuracy and efficiency in building, making them well-suited for this purpose. Based on ML model performance, it is recommended to employ J48 Decision Tree Model for the condition monitoring of a CNC hobbing cutter. The emerging confusion matrix was crucial in creating a condition monitoring system. This system can analyze statistical features extracted from vibration signals to assess the health of the cutter and classify it accordingly. The system alerts the operator when a hobbing cutter approaches a worn or damaged condition, enabling timely replacement before any issues arise.

АНАЛИЗ И УСТАНОВЛЕНИЕ ПРИЧИН РАЗРУШЕНИЯ ТЯЖЕЛОНАГРУЖЕННЫХ ЗУБЧАТЫХ ПЕРЕДАЧ

The destruction of gears occurs due to various reasons, first, connected with violation of manufacturing technology at different stages, poor quality assembly of the gear or the whole mechanism, as well as exceeding the specified operating loads. The aim of the study was to establish the causes of failure of the top drive gears in the drilling rig based on the mechanical and structural characteristics obtained by generally accepted methods, collectively used to assess the nature of the resulting damage. In order to analyze the compliance of the gear manufacturing quality with the operational requirements and to identify the cause of their failure, we carried out complex studies, including microstructural analysis of the gear metal, determination of its chemical composition and mechanical properties, as well as the study of the fracture surface morphology using scanning electron microscopy. As a result, we found that the gears failed due to a violation of the manufacturing technology in terms of wrong heat treatment.

УПРАВЛІННЯ ГЕОМЕТРІЄЮ ПЕРЕХІДНОЇ КРИВОЇ ПРОФІЛЮ ТА ВЕЛИЧИНОЮ ГРАНИЧНОГО ДІАМЕТРА ЦИЛІНДРИЧНОГО ЗУБЧАСТОГО КОЛЕСА

Information is given on the use of cylindrical gears. The influence of the geometry of the transition curve on other parameters is considered. With the development of numerically controlled machines and 3D printing, it becomes possible to manufacture gears with any geometry, in particular, it is possible to manufacture a transition surface with any parameters of the transition curve. The formula for determining the limit diameter is presented. The above formula is valid for gears that do not have undercutting. As can be seen from the obtained formula, the maximum diameter depends on the module, the number of teeth, the angle of the profile, the offset and other parameters of the initial contour. An example of a formed depression of a gear wheel is presented. The results of calculation and modeling of the value of the limit diameter depending on different values of the radius of curvature of the output contour were obtained.

Prediction and optimization of hobbing parameters for minimizing energy consumption and gear geometric deviations

Improving gear precision and achieving green sustainability in gear machining are two important aspects of the gear manufacturing process. However, to achieve these two goals simultaneously, it may be necessary to make trade-offs when selecting the gear processing parameters. In this work, both energy consumption and gear geometric deviations were considered simultaneously to optimize the hobbing parameters. The relationships between the hobbing parameters, energy consumption, and gear geometric deviations were modeled using the response surface method (RSM). The statistical significance of the model was tested using analysis of variance (ANOVA). An improved multi-objective particle swarm optimization (IMOPSO) was then performed to solve optimization problems that involved multiple and conflicting objectives in the hobbing process. The results obtained indicate that both the energy consumption ( E) and the gear geometric deviations are parameter-dependent. The feed rate ( f) and the spindle speed ( n) have opposing effects on both energy consumption E and the gear geometric deviations. The optimum hobbing parameter sets obtained from the calculated Pareto frontier can provide a feasible solution for manufacturers to solve the trade-off problems that occur in the hobbing process, and the experimental results confirmed the effectiveness of the IMOPSO approach.

Эластичные хоны для полирования профилей зубьев термообработанных цилиндрических колес специального назначения

Introduction. The most important component of the technological process of manufacturing of gear wheels of critical products is the operation of teeth honing. Special requirements are imposed on the surface quality of special-purpose gears, where imported abrasive tools were used, the supply of which in modern economic conditions is impossible. Purpose of work: development of formulation, technological equipment and technology of manufacturing of elastic diamond gear hones instead of imported ones for teeth honing of gear wheels of special purpose. Research methods. Subject of research are samples of imported elastic gear hones and created domestic analogs. The mechanical properties, morphology and chemical composition of the abrasive (diamond) layer of the working surface of the teeth and the annular gear were determined. The content of chemical elements was controlled in separate points of the surface and by scanning over the area on a scanning electron microscope. The formulation and technology of production of annular gears were determined. Results and Discussion. Designs of molds for forming the abrasive layer and the hub of the gear hone are developed. The peculiarities of morphology of the material of the working layer and the annular gear of the elastic diamond gear hone are revealed. On the basis of the conducted research, domestic analogs of materials of constituent elements of the gear hone are determined. Two manufacturing technologies were considered: pressing and injection molding. Two molds were made to test the technology: a simplified model consisting of two teeth and a round mold. Several methods of manufacturing hone teeth were analyzed: manufacturing of an abrasive layer with different degree of pre-vulcanization, subsequent introduction of gear material and final vulcanization of the whole product. The mechanical properties of the materials of the working abrasive layer and the annular gear were determined. The chemical composition of the components of the hone and the boundary zone are studied. As a result of the conducted research, recommendations on the formulation of the abrasive layer and the annular gear, technology of manufacturing of the gear hone intended for final treatment of teeth of heat-treated spur wheels of special purpose are given.

Studying the Performance of Reinforced Polymer Gear Wheels: Development of an Advanced Test Bench for Wear Analysis

In recent years, polymeric materials have gained prominence as a competitive option for gear manufacturing. Nevertheless, the absence of comprehensive literature addressing the wear due to the coupling of these materials presents a real challenge in response to this innovative trend. Wear of plastic gearwheels represents, in fact, a key issue, traditionally assessed using standard formulations under optimal dry operating conditions. These calculations often rely on coefficients derived from specialized gear tests, but their applicability is constrained to specific polymer–metal combinations. This research was dedicated to the development of a test bench tailored to evaluate the wear of glass fiber-reinforced self-lubricating polymer gearwheels under different operating conditions. This study commenced with a comprehensive exploration of wear phenomena in thermoplastic gearwheels and the inherent challenges associated with utilizing existing standards and the scientific literature for wear analysis. This was followed by a careful evaluation of the operational needs of the test bench, which, starting from a basic solution already implemented, improved its use in various aspects. Finally, this study introduced an optical-based methodology for average linear wear control. This research strived to establish a testing approach that minimizes uncertainties when assessing the wear of thermoplastic gears.

Data-Driven Multi-Objective Optimization Approach to Loaded Meshing Transmission Performances for Aerospace Spiral Bevel Gears.

Loaded meshing transmission performance optimization has been an increasingly significant target for the design and manufacturing of aerospace spiral bevel gears with low noise and high strength. An innovative data-driven multi-objective optimization (MOO) method is proposed for the loaded meshing transmission performances of aerospace spiral bevel gears. Data-driven tooth surface modeling is first used to obtain a curvature analysis of loaded contact points. An innovative numerical loaded tooth contact analysis (NLTCA) is applied to develop the data-driven relationships of machine tool settings with respect to loaded meshing transmission performance evaluations. Moreover, the MOO function is solved by using an achievement function approach to accurate machine tool settings output, satisfying the prescribed requirements. Finally, numerical examples are given to verify the proposed methodology. The presented approach can serve as a powerful tool to optimize the loaded meshing transmission performances with higher computational accuracy and efficiency than the conventional methods.