Gear Manufacturing Research Articles

A novel correction method to attain even grinding allowance in CNC gear skiving process

Power skiving is currently an efficient machining process to manufacture gears. In practical applications, uneven gear profile deviations caused by the asymmetric cutting edge of a skiving cutter affect gear profile accuracy and finishing cost. Therefore, this paper proposes a novel method to attain the even grinding allowance on both gear flanks in the CNC skiving. A quadratic polynomial function is adopted to correct an asymmetric rack profile, which is used to generate the skiving cutter profile. Pressure angles, protuberances, and polynomial coefficients on two sides of the rack are determined analytically according to the requisite grinding allowance and the conjugation relationship between the gear and the cutter. Skived tooth profiles for internal/external gears are simulated based on the CNC machine motion, and its normal deviation can be estimated. As the numerical results demonstrate, the profile deviations on both gear flanks are close to the required settings, and the even grinding allowance is achieved on the active involute sections. Additionally, a radial basis function (RBF) regression model is constructed to conveniently determine the design parameters of the skiving cutter.

Developing Spiral-Conical Gears for Microsystems by Wire-Assisted Electrical Discharge Machining

The requirements of gears are increasing rapidly in the global market for applications from micro electro mechanical systems (MEMS) to aerospace. Gears of various profiles and types including spiral-conical are used for motion as well as torque transfer in microsystems. The development of such gears is a challenging task because no compromise in their quality is acceptable. It necessitates highly accurate gear manufacturing process. This article presents such a process i.e. wire-assisted electrical discharge machining (WEDM) and development of stainless-steel made spiral-conical gears of miniature size. All minute aspects of spiral-conical gear development by WEDM are reported in this paper. In order to investigate the impact of process parameters and gear quality, an experimental study has been conducted based on Taguchi’s robust design of experiment technique. The developed gears are found with good manufacturing quality characteristics.

Sustainability and performance assessment of gear hobbing under different lubrication environments for manufacturing of 20MnCr5 spur gears

Sustainability of a gear machining process is adversely affected by large amount use of synthetic machining fluids which harm the environmental and human health. This concern has necessitated development and/or exploration of innovative options without compromising quality and productivity of gears. This paper describes assessment of sustainability and performance of gear hobbing for manufacturing of spur gears made of 20MnCr5 under different lubrication environments referred as hobbing without any lubrication (HWAL), hobbing with minimum quantity lubrication (HWMQL), and hobbing with flood lubrication (HWFL). Type of lubricant and its consumption, particulate emissions, their toxicity, fumes generation, energy consumption and hob wear have respectively been used as indicators for environmental, social, and economic aspects of sustainability. Gear quality in terms of microgeometry deviation parameters and flank roughness; and material removal rate have been used for performance assessment of HWMQL, HWFL, and HWAL. This study reveals that HWMQL consumes only about 4–5% of lubricant than HWFL; increases hob cutter life by 1.5 times; improves productivity by 27.2%; and consumes 27.8% less specific energy than HWFL. HWMQL also gives good air quality at the workplace with lesser nontoxic particulate emissions and lower fumes generation. Moreover, spur gears manufactured by HWMQL had minimum microgeometry deviations and better flank finish. This study establishes HWMQL environment as the most promising alternative for sustainable manufacturing of good quality spur gears with high productivity.

Transmission system of parallel lathe machine tools

The tailstock that allows machining long and concentric components, as well as drilling, reaming and threading. More precise measurements can be obtained with more careful work and more rigorous procedures by personnel competent in skill and ability. It is the conventional machine tool widely used to produce flat and also cylindrical surfaces, in the manufacture of gears, cylindrical straight teeth, helical, hypoid, dovetail, in dies it is used to manufacture punches of different shapes and cutting dies and inlay.

Investigations on five-axis milling and subsequent five-axis grinding of gears

High-productivity processes such as gear hobbing and gear grinding are normally used in the manufacturing of gears. In some applications, however, the use of these processes is not possible due to accessibility. One example is the production of planetary gears with double helical teeth for the gear box in modern aircraft engines. The gear boxes are used to increase the efficiency of the engines but should be as light and compact as possible. Thus, the tool runout area for gear hobbing or gear grinding tools is too small. One way of manufacturing these gears is five-axis machining. While five-axis milling of gears has been the subject of several publications, five-axis grinding of gears has hardly been a topic. This paper presents the results of investigations on five-axis milling and subsequent five-axis grinding of gears in comparison to conventionally manufactured gears. For this purpose, after hardening, gears were first five-axis milled and then five-axis ground using different process parameters and then investigated on back-to-back test rigs regarding load carrying capacity. In addition, the dimensional accuracy was measured and the surfaces were examined metallographically. The dimensional accuracy became worse after five-axis grinding. However, in terms of gear life, the five-axis milled and then five-axis ground variant showed an increase of 8.2 % compared to the conventionally manufactured gear which indicates a high potential for further research in regard to the presented five-axis machining process chain of gears.

Retracted] Application Value Analysis of Nanooptical Materials in Martial Art Single‐Kick Protective Equipment

If there is no protective equipment in martial art single practice, it is very easy to be injured, so protective equipment in martial arts has been paid more and more attention. The protective effect of Wushu Sanda protective gear is related to the safety of every Wushu Sanda practitioner. The purpose of this paper is to study crystalline nanooptical materials and Wushu Sanda protective gear and propose the idea of using more crystalline nanooptical materials in the manufacture and use of Wushu Sanda protective gear. This paper mainly introduces the related content of crystalline nanooptical materials, martial art single‐leg kick, and martial art single‐leg protective gear and conducts experiments on crystalline nanooptical materials and martial art single‐leg protective gear based on crystalline nanooptical materials. The experimental results show that the protective effect of protective equipment based on crystalline nanooptical materials can play a greater role than traditional protective equipment. In the experiments in this paper, the martial art single‐leg kicking protective gear based on crystalline nanooptical materials has at least a 10% improvement in protective effect.

Improving the load capacity of cylindrical gears and transmissions by parametric optimal design with CAD/CAM systems

Gears are an essential component of modern drives and systems. Cylindrical gears with involute profile have established themselves as one of the most widely used. Recent years have seen intensive research of both their profiling, as well as methodologies for improving their load carrying capacity. One way to increase productivity in the manufacture of cylindrical gears is the use of automated design systems. This paper presents an approach for optimal gear selection by applying the methods of parametric optimal design, modeling and study of gears with involute profile and study of their load carrying capacity.

Dynamic Simulation and Analysis of Engagement Process for Logarithmic Spiral Bevel Gear Based on Accurate 3D Model

Based on the accurate 3D model of logarithmic spiral bevel gear, the operation of spiral cone gear engagement is analyzed and simulated by ANSYS. Through the nonlinear static contact analysis of different positions, the stress change rule and the maximum contact stress is obtained. Compared with the theoretical contact stress strength rule, this paper also analyzes the dynamic operation situation of the gear pairs, obtains the dynamic contact situation rule at different engagement times and different rotating speeds, the influence of the rotating speed on the gear contact characteristics is compared too. The static, dynamic performance and change rules of the gear engagement is obtained, which lay a solid foundation for the further research, design and manufacture of spiral bevel gears.

Study on the Doping Effect Cr-doped Fe Metal Powder and Sintering Temperature on Microstructure and Mechanical Properties of Spur Gear Fabricated by Powder Metallurgy

We fabricated mechanical parts of the automotive machines by using Cr-doped the Fe metal powder. We used water as a binder and used a mechanical press for compaction of about 20 ton/in2 followed by non-reactive sintering at 1100 oC. Cr doped Fe metal powder was prepared in the form of GC with percentage values of 0, 0.5, 1.0, 1.5, and 2.0%. The Cr element has been successfully distributed into the main ferrite or Fe phase. However, there is a difference when the Cr percentage is 2%, it is possible that saturation will occur which results in the accumulation of Cr powder so that a new phase is formed which gives rise to new granules. We can confirm that there is a certain limit in the addition of the element Cr in the manufacture of gears made from Fe powder. Based on the calculation, the average number of the Vickers microhardness as a function of Cr content of 0, 0.5, 1, 1.5, and 2% respectively were estimated at about 131, 184, 291, 302, and 270 HV/0.01, respectively. Furthermore, four samples with different sintering temperatures were prepared for comparative purposes. The shrinkage ratio of the GC after sintering at 900, 1000, 1100, and 1200 oC was estimated to be 4.3, 5.7, 7.6, and 9.4%, respectively. The shrinkage ratio of the GC increased linearly when the sintering temperature increased. Sintering temperature variations produce differences in the microstructure of each sample. With the increase of the sintering temperatures, the grains will reach a permanent bond because the constituent particles are fully agglomerate. As a result, grain boundaries between particles will decrease causing the dimensions of the product to shrink so that its density increases. Theoretically, the density value is inversely proportional to porosity. The higher the density value of a product, the lower the porosity value. Increasing the sintering temperature could lead to the appearance of a liquid and the healing of pores. The hardness value and the shrinkage ratio increased with the sintering temperature increased from 900 to 1200 oC. The hardness value increased from 297 to 305 HV/0.01, as the sintering temperature increased from 900 to 1200 oC.

Investigation on effects of variation of applied load on helical bevel gear made of different materials using simulation technique

Gears are the devices used to transmit power even with high torque. Gears are damaging due to different loads applied to the teeth and heat generated in transmission. Usually, gears are made of different materials. In this study, force vibrational analysis is done on the helical bevel gear for different materials such as Aluminum, cast iron, copper, iron, steel, and titanium. In this investigation, different material is selected for the manufacturing of gears that can sustain even under the different loads and impact loads. Simulation is performed to analyse the effect of the application of loads on various materials. The stresses developed by the application of loads are von Mises stress and the total deflection in the gear. It is reported that with the variation of the loads being applied, von Mises and displacement both changes linearly with the load applied.

History of Gleason Works Spiral Bevel Gear Technology

The paper deals with the history of Gleason Works history in regard for their bevel gear manufacturing technology. In spiral bevel gear technology Gleason is a leading company, with many patterns and research studies in this field. The focus of this paper is to show the development of the technology provided by Gleason over the past more than 100 years.

Shot Peening Simulation Oriented to Residual Stress Interaction in Gear Manufacturing Chain

Shot Peening Simulation Oriented to Residual Stress Interaction in Gear Manufacturing Chain

Effect of gear honing by tools with various elasticity on vehicle gear quality

Gear honing withthe abrasive gear hones is used for batch and mass production of vehicles to ensure high quality of gear teeth lateral faces. The service life of vehicle systems as well as the vehicle noise level depend on accuracy of the parameters and gear machining quality. In terms of the elasticity modulus, gear hones can be hard and elastic, depending on the bonding agent type. The gear hone material undergoes deformation during operation. The gear hone tooth deformation value depends on the contact point height; it increases by ten folds from the lowest point to the top. Deformation values are comparable to metal removal values and initial-error values of machined details. Besides, the kinematic parameters of engagement vary, the values of specific sliding and contact-pattern areas are distributed along the tooth height more uniformly. It affects the nature and values of post-machining rectification of gear inaccuracy. The studies made it clear that increase of the gear hone material elasticity degree is associated with more significant rectification of gear defects and substantial decrease of the roughness value, even in case of a large grit size, as a consequence of aligning of abrasive grain peaks along the bearing surface, increased contact time of grains and the machined surface, contact pattern area, and machining fullness. Though such coarse irregularities as dints and burrs are removed better by hard gear hones. Increased quality of gear manufacture results in a decreased noise level of vehicle gears.

Application of computer technologies for calculation of gears at studying of a course " Details of machines"

The computer program GearKURT has been created to calculate mechanical gears. The program allows you to calculate gears:
 - closed cylindrical spur gear
 - closed cylindrical helical gear
 - open cylindrical spur gear
 - Novikov's gear
 - closed bevel spur gear
 - closed bevel gear with indirect teeth
 - open bevel gear
 - worm-gear.
 The computer program has a dialog interface written in the object-oriented programming language Delphi and compiled into an exe-file. The program allows you to choose the necessary material and method of heat treatment for the manufacture of gears, to calculate the optimal geometric dimensions and transmission parameters, to determine the design of gears. The program provides all the necessary reference materials in the form of tables and graphs, which must be used to select the coefficients and other values necessary for calculations. The program provides access to the theoretical material of the course "Machine Parts" and the ability to save the results of calculations in a separate file. Recommendations for using this program are given.

Detecting Teeth Defects on Automotive Gears Using Deep Learning.

Gears are a vital component in many complex mechanical systems. In automotive systems, and in particular vehicle transmissions, we rely on them to function properly on different types of challenging environments and conditions. However, when a gear is manufactured with a defect, the gear’s integrity can become compromised and lead to catastrophic failure. The current inspection process used by an automotive gear manufacturer in Guelph, Ontario, requires human operators to visually inspect all gear produced. Yet, due to the quantity of gears manufactured, the diverse array of defects that can arise, the time requirements for inspection, and the reliance on the operator’s inspection ability, the system suffers from poor scalability, and defects can be missed during inspection. In this work, we propose a machine vision system for automating the inspection process for gears with damaged teeth defects. The implemented inspection system uses a faster R-CNN network to identify the defects, and combines domain knowledge to reduce the manual inspection of non-defective gears by 66%.

Characterizations of Polymer Gears Fabricated by Differential Pressure Vacuum Casting and Fused Deposition Modeling.

In recent years, polymer gears have gradually become more widely employed in medium or heavy-duty conditions based on weight reduction in transmission systems because of low costs and low noise compared to metal gears. In the current industry, proposing a cost-effective approach to the manufacture of polymer gears is an important research issue. This paper investigates the wear performance of polymer gears fabricated with eight different kinds of materials using differential pressure vacuum casting and additive manufacturing techniques. It was found that both additive manufacturing and differential pressure vacuum casting seem to be an effective and cost-effective method for low-volume production of polymer gears for industrial applications. The gate number of one is the optimal design to manufacture a silicone rubber mold for differential pressure vacuum casting since the weld line of the polymer is only one. Polyurethane resin, 10 wt.% glass fiber-reinforced polylatic acid (PLA), or 10 wt.% carbon fiber-reinforced PLA are suggested for manufacturing gears for small quantity demand based on the deformation and abrasion weight percentage under process conditions of 3000 rpm for 120 min; epoxy resin is not suitable for making gears because part of the teeth will be broken during abrasion testing.

5-axis double-flank CNC machining of spiral bevel gears via custom-shaped tools\u2014Part II: physical validations and experiments

Recently, a new methodology for 5-axis flank computer numerically controlled (CNC) machining, called double-flank machining, has been introduced (see “5-axis double-flank CNC machining of spiral bevel gears via custom-shaped milling tools—Part I: Modeling and simulation”). Certain geometries, such as curved teeth of spiral bevel gear, admit this approach where the machining tool has tangential contact with the material block on two sides, yielding a more efficient variant of flank machining. To achieve high machining accuracy, the path-planning algorithm, however, does not look only for the path of the tool, but also for the shape of the tool itself. The proposed approach is validated by series of physical experiments using an abrasive custom-shaped tool specifically designed for a particular type of a spiral bevel gear. The potential of this new methodology is shown in the semifinishing stage of gear manufacturing, where it outperforms traditional ball end milling by an order of magnitude in terms of machining time, while keeping, or even improving, the machining error.

Comparative LCA of automotive gear hobbing processes with flood lubrication and MQL

The life cycle inventory (LCI) data of a gear hobbing was obtained by means of the methodology unit process life cycle inventory (UPLCI), to conduct a comparative life cycle assessment (LCA) between hobbing assisted by flood lubrication (FL) and minimum quantity lubrication (MQL). The results pointed out 4 among 11 normalized environmental impact categories totalized more than 80% of the accumulated impacts: Fossil Depletion (43%), Climate Changes (19%), Terrestrial Acidification (11%), and Freshwater Consumption (8%). The identified hotspot in the case study was the input flow of raw material for the system “Hobbing Machine,” which was linked to more than 75% of the total amount of normalized potential environmental impacts. Once, changes on raw material depends on the gear design, the research focused on the environmental aspects of energy and cutting fluid consumption, which depends directly on the hobbing process parameters. The introduction of MQL provided reduction of 70.77% on the total amount of normalized potential impacts, while the strategies to reduce electric energy consumption by the machine tool accounted only for 3.74%. Nevertheless, when raw material flow is considered in the LCA, it turns into the process hotspot, due to high energy demanded in the steel-making process, forging, and turning operations to shape the semi-finished gear. The relevance of the key environmental aspects, electric energy, cutting fluids, and raw material, can vary significantly according to the gear size itself. The performed case study was considered a pilot project for the hosting company and can be scaled up to a whole gear manufacturing plant to identify manufacturing cells, which are eligible to optimization in the use of cutting fluids and electric energy by the machine tools.

Static analysis of epoxy resin and carbon fibre composite spur gear

Gears are called to be the most essential and significant element in automobile and power transmission systems. These are the machine component which are used for power transmission and motion among the shafts by process of repetitive engagement in the form of teeth. The progression in the transmission has made the gears as one of the most advanced and operative means of transmitting power due to its effectiveness and compatibility. A good spur gear is one which is easy to produce and should be of high strength to weight ratio. In this project we have compared Von Mises Stress, Equivalent strain and Total deformation for ‘Epoxy resin and Carbon fibre’ composite gear with a gear made up of steel as a replacement in the gear manufacturing industry and the software which was used to get the best result was CATIA and ANSYS.

Vibration signal analysis of planetary gear with amplitude, frequency and phase modulation

In this paper, the vibration signal of planetary gear with amplitude, frequency and phase modulation is studied. The proposed mathematical model is employed to in- vestigate the modulation behavior of planetary gear. Based on this model, the ampli- tude modulation (AM) sidebands are analyzed to verify the correctness of theoretical calculation by Inalpolat and Kahraman. Then, the frequency modulation (FM) side- bands and phase modulation (PM) sidebands are also illustrated through an exam- ple analysis. The effects of parameters of planetary gear such as number of planets, teeth of sun and planet phasing relationships on the AM, FM and PM sidebands are analyzed. Finally, the specific expression of transmission error, time-varying mesh stiffness and dynamic mesh force including gear manufacturing error is developed. Time history signal and acceleration spectra of gear mesh interface excitations including AM, FM and PM are investigated for the meshes of sun-planet and ring- planet. The results show that gear parameters have important influence on the mod- ulation behavior. Additionally, manufacturing errors can be introduced to predict the sidebands of planetary gear. The amplitude, frequency and phase modulation study are extremely significant for the noise and vibration reduction, especially the fault diagnosis of planetary gear