Gear Manufacturing Research Articles

Simulation of spiral bevel gear manufacturing by face hobbing and prediction of the cutting forces using a novel CAD-based model

Simulation of spiral bevel gear manufacturing by face hobbing and prediction of the cutting forces using a novel CAD-based model

Special Issue on Recent Progress in Manufacturing Technology

The continued effects of the global spread of COVID-19 have reaffirmed that restrictions on the movement of people and products have geopolitical consequences. In addition, the impacts involved in the decarbonization of the global environment have further strengthened the growing demand for the building of a sustainable society. These factors have had no small impact on the global economy and on global manufacturing as well. In this context, the demand for the realization of new manufacturing technologies that can respond to changes in social and economic environments has been growing. This special issue focuses on recent advances in manufacturing technologies that maximize product quality and reduce costs, with an emphasis on the machinery industry. This special issue of the IJAT contains 12 papers. These include works on cutting technology, machining metrology, advanced machine tools, gear manufacturing technology, additive manufacturing, and more. The first five papers are proposals for new cutting technologies and elucidations of cutting phenomena. The next three papers are new proposals for machining measurements. The next two papers are on precision positioning technologies and a rack gear compensation technology. The last two papers are theoretical investigations into the basic phenomenon of additive manufacturing and its applications. These papers were originally presented at the 10th International Conference on Leading Edge Manufacturing in the 21st Century (LEM21), held in Kitakyushu, Japan in 2021. The papers have been revised and expanded at the request of the editors. The editors would like to thank all authors for their comprehensive efforts in making this special issue possible, and would like to thank the anonymous reviewers for their hard work. We wish them all the best in their future research in this field of manufacturing technology.

Experimental and numerical study of contact fatigue for 18CrNiMo7-6 and 20MnCr5 carburized gear tooth

Gear manufacturers must make decisions about the manufacturing materials and superficial treatments. The best performance as to a type of failure should be evaluated. However, it is a time-demanding and costly process. The present work proposes a methodology for a comprehensive assessment (experimental and computational) of contact fatigue of gears in FZG test rig. The materials investigated were 18CrNiMo7-6 and 20MnCr5 alloy steels, widely used in industrial and automotive transmission systems, but with very different raw material costs, which can exceed twice the first compared to the second. The study evaluated the contact analysis between gears from the macroscopic point of view and the microscopic (inclusion of roughness). At the same time, the evolution of roughness and pit-damaged area after each test stage was monitored. The approach determined the stress field after each loading cycle and thus correlating the regions of higher stresses with surface and subsurface fatigue (micropitting and pitting). In addition, Weibull’s statistical analysis and SEM-EDS observations were executed. In many cases, the methodology correlated the increased roughness and pitting affected area with the regions submitted to the higher contact stress. Observations by SEM-EDS revealed that the occurrence of plastic deformation as a mechanism of wear should be considered in the equations of microscopic stress analysis. The similar fatigue life of such different materials may be correlated to the competitive mechanisms of higher mechanical strength of 18CrNiMo7-6 and better crack propagation characteristics of 20MnCr5. The methodology proved to be consistent for fatigue failure analysis of gears in FZG test rig.

Experimental Evaluation of the Feasibility and Reproducibility of a Novel Multi-step Forming Process for Cu-OFE Micro Gear Manufacturing Compared to Macro-scale Forming

The increasing miniaturization of technical systems leads to a rising demand for micro components. Miniaturized drive systems with geared micro parts or micro gears are applied in various industries. Due to the demand for high production volumes, productive and resource-efficient fabrication is of major importance. Compared to industrially applied manufacturing methods like cutting and metal powder injection, cold forming provides technological, economic and ecological potential for the mass production of micro gears. It enables high productivity and advantageous mechanical properties of the gears. In the macroscopic size range, forming processes are well established in series production of gears. However, in micro-scale, according to the current state of the art, cold forming of modules m<0.2mm is not possible due to size effects, high tool loads and handling problems. Within this contribution, a multi-stage forming process for the fabrication of micro gears with a module of m=0.1mm is introduced and compared with a conventional forming process on macro-scale with a module of m=1.0mm. The use of coil material provides potential for easy handling of the micro parts in a progressive die for the potential application in a high-speed press. In addition, the multi-stage forming achieves a grain alignment, which enhances the formation of the micro gear profile. Based on the comparison between micro- and macro-scale, the performance of the micro process is analyzed with regard to deviations of process force as well as gear quality and possible size effects are identified. The results prove the feasibility of the process chain and the achievement of equivalent part quality and reproducibility compared to macro-scale forming.

An Emergy-Based Sustainability Method for Mechanical Production Process—A Case Study

To promote the sustainability of mechanical production process, this study proposes an emergy-based sustainability evaluation method to evaluate the resource utilization and environmental pollution of the mechanical production process. Firstly, this study constructs the sustainability evaluation index system of the mechanical production process from the perspectives of economy and environment. Secondly, an emergy analysis method-based sustainable evaluation of the mechanical production process is constructed. Finally, taking the gear manufacturing process as an example, the method is tested. The results show that this method can effectively quantify and identify the sustainability of the gear manufacturing process and provide effective feedback to improve the process. The resulting improvements can aid in reconsidering the economic and environmental factors, improving the production efficiency and the sustainability of the production process, and reducing the difficulty of operating the lathe in the production process. This study provides method support for the sustainability evaluation of mechanical production process and decision support for its improvement.

An Effective Shrinkage Control Method for Tooth Profile Accuracy Improvement of Micro-Injection-Molded Small-Module Plastic Gears.

An effective method to control the non-linear shrinkage of micro-injection molded small-module plastic gears by combining multi-objective optimization with Moldflow simulation is proposed. The accuracy of the simulation model was verified in a micro-injection molding experiment using reference process parameters. The maximum shrinkage (), volume shrinkage (), addendum diameter shrinkage (), and root circle diameter shrinkage () were utilized as optimization objectives to characterize the non-linear shrinkage of the studied gear. An analysis of the relationship between key process parameters and the optimization objectives was undertaken using a second-order response surface model (RSM-Quadratic). Finally, multi-objective optimization was carried out using the non-dominated sorting genetic algorithm-II (NSGA-II). The error rates for the key shrinkage dimensions were all below 2%. The simulation results showed that the gear shrinkage variables, , , , and , were reduced by 5.60%, 8.23%, 11.71%, and 11.39%, respectively. Moreover, the tooth profile inclination deviation (), the profile deviation (), and the total tooth profile deviation () were reduced by 47.57%, 23.43%, and 49.96%, respectively. Consequently, the proposed method has considerable potential for application in the high-precision and high-efficiency manufacture of small-module plastic gears.

Experimental monitoring of eccentric gears with different mechanical conditions

The use of Condition Monitoring (CM) for engineering design, and industrial gears, has dramatically changed the gear design and manufacturing process in a short space of time. As CM deployment grows rapidly, the feasibility of CM for the diagnosis and prognosis of most common gear failure modes has well been investigated and documented. However, this is not the case for the CM of industrial gear eccentricity. Previous published work, in particular, focused only on the use of simulation models as a basis to investigate the gear eccentricity. Simulations cannot always ease the detection of complex problems and complications that are experienced in real operations. For instance, excessive eccentricity can be considered as one of manufacturing errors that may severely lead to direct effect on the overall dynamic performance of gears. Yet, it produces very high modulated mesh frequency rates; thus, making the detection of faulty machine components very difficult or even impossible. With this in mind, this paper presents the first known attempt at the diagnosis and prognosis of experimental vibration datasets from five different eccentric gear conditions. Datasets were first analysed using Signal Intensity Estimator (SIE) method in time and frequency domains. Then, the data was subjected to additional processing for the classification of gearbox status. Observations from the results showed that the proposed techniques could successfully discriminate the “good” and “bad” gears.

Spur gear manufacturing using conventional machine tools

The objective of this writing is to develop a methodology for the manufacture of a spur gear prototype using conventional machine tools. The purpose of this article is to help scientists and engineering students who need a guide to manufacture this type of elements that are part of a mechanical system for the transmission of movement and force. This study intends a comprehensive analysis of each step used for the manufacture of a spur gear, which allows in an objective way to determine the cutting tools and equipment necessary to carry out its manufacture, starting from the design of the element in question and applying the technical formulas necessary to adjust the parameters in the machining of the part. The methodological approach for this study has been determined based on the practical skills and experience that are paramount in the use of conventional machines. As a contribution we can say that with this methodology it will be possible to eliminate many previous problems in terms of planning and the lack of experience in handling conventional tools.

Flank Surface Treatment of Spur Gears Machined by MQL Assisted Hobbing Using Micro-Plasma Transferred Arc

In the present study, feasibility of micro-plasma transferred arc (M-PTA) for flank surface treatment of gears has been explored. 20MnCr5 spur gears manufactured by sustainable technique minimum quantity lubrication assisted hobbing (MQLAH) were subjected to M-PTA-based heat treatment for further improving the surface properties of flank surface and comparisons were made with respect to M-PTA treated gears machined by conventional flood lubrication assisted hobbing (FLAH). The results revealed that M-PTA enhanced flank surface hardness of all the gears without deteriorating the gear accuracy. However, flank hardness increment was observed to be almost 18% in case of MQLAH gears as compared to 15% for FLAH gears. This study proves that M-PTA based heat treatment after MQLAHcan result in superior surface hardness along with better gear accuracy and can improve the sustainability of overall process chain involved in machining-based gear manufacturing.

Sustainable Manufacturing of Asymmetric Miniature-Sized Ratchet Wheels by Wire Electrical Discharge Machining

In this paper, the outcomes of an investigation conducted on the sustainable manufacturing of asymmetric rotary miniature-sized ratchet wheels of stainless steel (SS) 304 by a vertically traveling wire electrical discharge machining (WEDM) process are reported. The consumptions of energy and wire material are the process sustainability indicators considered in this work. Box-Behnken-based seventeen experiments were conducted by varying spark-on-time ‘Ton’, spark-off-time ‘Toff’, and wire rigidity ‘WT’. Desirability function analysis (DFA) based on multi-response optimization was performed to obtain an optimum setting of WEDM parameters to manufacture miniature-sized ratchet wheels with minimum energy and wire consumption. Sustainable manufacturing of ratchet wheels is performed at the optimum parameter combination of Ton-1.5 µs; Toff-40.5 µs; WT-1260 g, for the least values of energy consumption of 0.64 kWh and wire consumption of 20.11 g with no wire breakage and a significant reduction in total idle time. This ratchet wheel, manufactured at optimum parameters of WEDM, was also found to have a good finish (average surface roughness ‘Ra’-1.08 µm and maximum surface roughness ‘Rt’-6.81 µm) and defect-free tooth flank surfaces. Overall, it is concluded that WEDM has the potential to achieve sustainability in the manufacturing of miniature-sized ratchet wheels and other gears. The outcomes of this work will extensively facilitate engineers and researchers in selecting a suitable range of machining parameters for sustainable manufacturing of miniature-sized wheels and gears.

Research on the profile modification of power skiving tool for internal gears

Power skiving provides an effective solution and considerable machining efficiency for the machining of internal gears. The tool profile design and the reusability after resharpening is crucial in gear manufacturing. In this paper, a novel method of tool profile correction based on the inverse error-complement of involute profile is proposed. Firstly, the mathematical model of involute cutter with rake angle and relief angle is established. The profile error relative to the target gear is calculated by the mathematical model. Then, the distribution of the gear profile errors is fitted by a fifth-order multinomial. The fitted multinomial function is attached to the cutter profile. The maximum theoretical error of the target gear profile is in 10e-7 mm order of magnitude through the calculation of fewer iterations. Finally, the distribution of the multinomial coefficients along the resharpening direction is obtained by linear programming. The result shows that the cutter designed by the proposed method possess almost negligible error to the gear profile and good repeatability of resharpening.

Optimization of Gear Manufacturing for Quality and Productivity

Multi-objective optimization in manufacturing can effectively be solved using Multicriteria decision-making (MCDM) techniques. This paper presents the implementation methodology of the Fuzzy-MOORA hybrid technique for multi-objective optimization in laser machining of stainless-steel gears. Further, simultaneous optimization of gear quality and process productivity have been reported. Four important laser parameters, i.e., laser power, cutting speed, focal position, and gas pressure, have varied during twenty-nine experiments to machine gears by a laser process. The quality of miniature gear was measured in terms of average surface roughness, mean roughness depth, and dimensional deviation. The productivity of the laser machining process was estimated via material removal rate. An optimum set of laser machining parameters obtained after Fuzzy-MOORA optimization is laser power 2000 W, cutting speed 3 m/min, focal position -2.5 mm, and gas pressure 16 bar. This work encourages researchers and scholars to make further attempts using such MCDM techniques to develop intelligent processes in industrial and manufacturing engineering.

Vibration-based gear continuous generating grinding fault classification and interpretation with deep convolutional neural network

Continuous generating grinding plays an essential role in modern gear manufacturing, while the increasing need for high-quality gear products pushes the quality control of the grinding process. This paper proposed a vibration-based process monitoring method to classify faults generated during grinding processes. Gear grinding measurements have been conducted during experiments with different parameters of the feed rate, infeed, and gear eccentricity. The grinding vibration signals have been gathered to form a dataset with seven gear quality categories. A novel deep learning model is presented in this paper exploiting the power of Wavelet Packet Decomposition (WPD) and Deep Convolutional Neural Network (DCNN). The WPD is adopted to transform the vibration signal into 2D time-frequency representations, used as inputs to the DCNN model for classification. Experimental results show that, the proposed DCNN can achieve a high classification accuracy of 95.83%, demonstrating the methodology's efficiency. In addition, this paper exploits the Gradient-weighted Class Activation Map (Grad-CAM) technique to interpret the deep neural network's decisions in order to facilitate the model deployment in industrial production. The Grad-CAM visualizations are utilized to show the activation regions on the spectrograms, which further indicate that the attentions of the DCNN have a strong correlation with the manufacturing parameters of different grinding passes.

Design Modification of Cluster Gear Shaft of Synchromesh Gearbox in Tractor

Abstract: A cluster shaft is a rotating member/machine element, which is used to transmit power from one place to another. A cluster shaft is a shaft that runs parallel to the main shaft in a gearbox, and carries the pinion wheels. The failure of the second gear mounted on the cluster shaft occurred due to wear and tear. The objectives of the paper is to study the existing cluster gear shaft, and providing the proper solution so as to avoid the failure of cluster gear shaft. There are various reasons due to the gear may fail, few of them could be application error, design error, manufacturing error or application error. According to American gear manufacturing association, the failures of gear can be classified into four major categories namely surface fatigue, wear, plastic, and breakage. It has been observed that in most of the cases the failure starts from the bearing. After FEM analysis it is found that the maximum equivalent stress occurred on the second gear which is equal to 12.45 MPa. Keywords: gear failure, wear, lubrication, misalignment.

Loaded contact fatigue-oriented carburizing surface optimization model of spiral bevel gears

In order to improve geometric accuracy and loaded contact fatigue life on tooth surface carburizing, an innovative optimization model is established for spiral bevel gears. First, finite element method (FEM)-based tooth surface carburizing simulation is performed. Where, the output carbon content and hardness gradient are used to determine the S-N curve of the given material 20MnCr5 steel. The output residual stress is integrated into the bending stress solution. The output carburizing surface deformation is introduced into the composite surface geometric accuracy. Second, loaded contact fatigue assessment is performed by FEM-based loaded contact stress and S-N curve. Where, loaded contact stress considering residual stress is determined by simulated loaded tooth contact analysis (SLTCA). Third, loaded contact fatigue life-oriented carburizing surface optimization model is established. In this modeling, the composite surface geometric error including carburizing deformation, loaded contact deformation and the prescribed ease-off is used to reflect manufacturing geometric accuracy. Moreover, the limit fatigue life at dangerous point is used a standard to determine the target surface. A sensitivity analysis strategy-based optimization strategy is developed. The proposed method can effectively improve the process parameter modification strategy by considering the collaborative optimization on geometric accuracy and loaded contact fatigue life. Moreover, it also can provide new technical for the current co-design and manufacture of spiral bevel gears.

INVESTIGATION OF THE INFLUENCE OF GEAR ERRORS ON THE PERFORMANCE OF THE ROCKING MACHINE GEARBOX

This article presents the results of a study of the influence of gear manufacturing errors on the smooth operation of the reducer of the mechanical drive of the oil pumping unit based on a specially developed 3D modeling technique for the formation of kinematic error. This technique consists in constructing a three-dimensional solid-state model of a gear transmission with specified primary errors of the wheels and subsequent modeling of the gear engagement operation. Models of gears are obtained as a result of modeling the tooth-cutting process. This makes it possible to include manufacturing errors in the gear models caused by various technological reasons, such as, for example, fluctuations in the chain links of the machine, the beating of the cutting tool and the workpiece, errors in the cutting edges of the tool, errors in the installation of cutting tools, etc. The simulated graphs of the kinematic error of gears consisting of wheels are given, which contain the main manufacturing errors affecting the smooth operation of the reducer of pumping unit (errors in the lateral profile of the teeth, the error of the gearing step). Keywords: pumping unit, reducer, errors, working capacity.

Analysis and optimisation of the cutting parameters based on machinability factors in turning AISI 4140 steel

ABSTRACT AISI 4140 alloy steel has high abrasion resistance, toughness, torsional, and fatigue strength. Different types of this alloy with different hardness are used to manufacture gears, crankshafts, collars, jigs, and milling spindles. In this study, turning tests were carried out on AISI 4140 steel using coated carbide inserts considering Taguchi L9 orthogonal array at three different cutting speeds, feed rates, and cutting depths. The output parameters were selected as cutting forces, surface roughness, current and sound intensity. According to the ANOVA results, feed rate was the most effective parameter on the cutting force and surface roughness. As the feed rate increases, the cutting force and surface roughness value enhance. The feed rate was also the most important factor affecting the current with 81.61% contribution, followed by cutting depth with 12.67% contribution. The cutting depth with 66.95% contribution has the highest impact on the sound intensity. It was followed by a feed rate with 26.07% contribution. According to the optimisation results, the experimental and the estimated values ⁣⁣were significantly close to each other.

Failure analysis of nylon gears made by additive manufacturing

Additive manufacturing enables fast manufacturing of polymer gears directly from a 3D model. Failed polymer gears can be replaced easily and quickly using many different materials. Mechanical and thermal characteristic of gears manufactured using additive manufacturing are mostly dependent on selected manufacturing parameters and material. In this research, the influence of the most important manufacturing parameter (infill percentage) on failure types and service life of additive manufactured nylon gears is experimentally investigated. The experimental tests were carried out using a custom-made gear testing device. Samples with 20, 40, 60, 80 and 100% of infill volume were tested. Infill type, shell thickness, and manufacturing speed were the same for all samples. Service life of gears was tested and failure types were characterized.

Quality of manufacturing of gears from sparingly alloyed steel at all stages of technological conversion

The advantages of sparingly alloyed steels for the manufacture of large-module gears are substantiated. A test output quality control of the manufacture of gears from rolled new structural sparingly alloyed steel 21ХГНМБА (21KhGNMBA) was carried out at all stages of technological conversion in the conditions of serial production. The efficiency of the developed technological processes of preliminary heat treatment of workpieces and chemical-thermal treatment of gears is shown. A significant reduction in the labor intensity of these processes is achieved in comparison with the processes of chemical-thermal treatment of steels with a high nickel content. Recommendations are given on the choice of an abrasive tool for grinding surface-hardened gears made of economically alloyed steel.

Prognostics of Gear Manufacturing Errors for Planetary Gear Systems Based on Power Flow Theory

Abstract Gear manufacturing errors are key parameters in planetary gear trains and have effects on load sharing, tooth stress, and so on. Accurate estimation of manufacturing errors can help monitor the conditions of planetary gear systems. This study investigates the dynamic response sensitivity to model parameters for a nonlinear single-stage planetary gear set with coupled lateral and torsional motions. Power flow theory is introduced to assess the gear vibration and the parameter sensitivity. The response sensitivity equations are deduced with the direct method (DM). The influence of the rotating speed is considered in the sensitivity analysis. Then, the identifiability of the parameter estimation is investigated based on the sensitivity results. The Gauss-Newton method is applied to estimate the manufacturing errors. Gear meshing is a primary factor in gear vibration, so the sensitivities of its vibration power to the parameters are analyzed in this paper. The estimated results are accurate when the collected data contain a lower noise signal. The sensitivity and parameter estimation make it possible to provide support for the design and diagnosis of a planetary gear set.