Precision Gears Research Articles

KARAKTERISTIK KEBULATAN TERHADAP PARAMETER PROSES PEMBUBUTAN PADA MATERIAL ST 42 MENGGUNAKAN METODE TAGUCHI DAN ANOVA

This research is about the roundness characteristics of the turning process parameters on St 42 material using the Taguchi and ANOVA (Analysis of Variance) methods. A cylindrical product requires a good roundness value to ensure its quality. One of the factors that determine the quality of these products is the machining process parameters. In this study, optimization of the turning process parameters using the Taguchi and ANOVA methods was carried out on the roundness characteristics of the workpiece. The workpiece used is Steel St 42. The lathe used is the Krisbow Precision Gear Head Machine 410X1000MM. After data analysis using the Taguchi method, the parameters with the optimum roundness value of 7.385 µm were 510 rpm spindle rotation, 1mm depth of cut, and coolant opening valve. The results of the ANOVA analysis show the percent contribution of each parameter, respectively, as follows: spindle rotation 26.97%, depth of cut 24.82%, and coolant 38.63%.

The Improvement of the Precision of the Archimedean Spiral Toothline Gear Cutting Mill

Abstract The precision of gears has a major influence on the quality of the transmission. If the gear cannot be finished by grinding, the precision of the generating tool becomes essential. Archimedean spiral toothline cylindrical gears are obtained by reciprocate meshing using a milling cutter built up by individual cutters, organized in groups. The profiles of edges must be realized with a minimal profile error. In order to ensure the quality and the precision of the meshed tooth surface, and also the profile constancy after re-sharpening, relief faces must be realized by a grinding relieving operation. A secondary effect of the kinematics of relieving end the spatial extent of the grinding wheel a post undercut results and this produces an inevitable profile error. The present paper discusses a possible grinding wheel setting that produces a maximum theoretical profile error under 1μm along the whole re-sharpening reserve of the cutter. The proposed setting can be realized on a classical relieving lathe.

Optimisation of a Polarisation Nephelometer

An analysis of the influence caused by polarization nephelometer parameters on the scattering matrix measurement accuracy in a non-isotropic medium is presented. The approximation errors in the actual scattering volume and radiation beam by an elementary scattering volume and an elementary radiation beam are considered. A formula for calculating the nephelometer base is proposed. It is shown that requirements to an irradiation source of a polarizing nephelometer, i.e. mono-chromaticity and high radiation intensity and directivity in a wide spectral range can be satisfied by a set of high brightness LEDs with a radiating (self-luminous) small size body. A 5-wavelength monochromatic irradiation source, with an emission flux of (0.15–0.6) W required for a polarization nephelometer, is described. The design of small-sized polarizing phase control units is shown. An electronic circuit of a radiator control unit based on an AVR-Atmega 8-bit microcontroller with feedback and drive control realized by means of an incremental angular motion sensor and a software PID controller is presented. Precise and smooth motion of the radiator is ensured by standard servo-driven numerical control mathematics and the use of precision gears. The system allows both autonomous adjustment of the radiator’s reference positions and adjustment by means of commands from a personal computer. Both the computer and microcontroller programs were developed with the use of free software, making it possible to transfer the programs to Windows‑7(10), Linux and embedded Linux operating systems. Communication between the radiator’s position control system and the personal computer is realised by means of a standard noise immune USB-RS485 interface.

Dynamic characteristic of spur gear system with spalling fault considering tooth pitch error

AbstractThere have been many researches focusing on the dynamic characteristics of gear faults, such as spalling, crack and broken, to improve the accuracy of fault diagnosis methods. However, the tooth pitch error caused by actual gear manufacture precision is usually neglected, which may have a direct influence on the gear vibration response. In order to settle the problem of the underlying vibration mechanism with the combined effect of pitch error and spalling fault, a dynamic modeling method of the spalling gear coupling with pitch error is proposed, in which the relationship between the gear precision level and the pitch error is considered. The changes in both meshing stiffness phase and displacement excitation on the contact line caused by pitch error are analyzed, where the additional effect of spalling fault on stiffness excitation is also taken into consideration. Base on the proposed dynamic model, the dynamic responses and vibration characteristics of spur gear with coupling excitation of pitch error and spalling fault are investigated. The simulation results show that vibration characteristics caused by the early spalling fault are easy to be affected by the pitch error, especially when the gear precision is poor.

전동지게차용 Steering Axle의 구조해석 및 가속수명시험방법 적용

Purpose: This paper introduces the procedure and results of a durability test conducted for the steering axle of a two-ton electric forklift. The test is designed as an accelerated life test based on the reliability analysis standard RS B 0073, established by the Korea Institute of Machine and Materials.BRMethods: We conducted an accelerated life test that can simultaneously check the durability of the gear and housing through a tester that applies a load to the steering axle. The test was performed for a total of 360 h, with 11 h test cycle each in the forward and reverse directions under the proposed test code with a rotation speed of 2,300 rpm and an equivalent torque of 2.07 Nm. Subsequently, visual verification and gear precision measurements were performed through sample disassembly.BRResults: Altuough minor rubbing marks and gear bites were observed, no significant damage or deformation of the surface fittings was identified. A penetration test confirmed that there was no crack in the housing due to stress.BRConclusion: This paper provides guidelines for testing the life of steering axles.

Disclosing the truth: Are models better than observations?

The aphorism, ‘All models are wrong, but some models are useful’, originally referred to statistical models, but is now used for scientific models in general. When presenting results from a marine simulation model, this statement effectively stops discussions about the quality of the model, as there is always another observation to mismatch, and thereby another confirmation why the model cannot be trusted. It is common that observations are less challenged and are often viewed as a ‘gold standard’ for judging models, whereas proper interpretations and the true value of models are often overlooked. Models are not perfect, and there are many examples where models are used improperly to provide misleading answers with great confidence, but to what extent does an observation represent the truth? The precision of the observational gear may be high, but what about representativeness? The interpretation of observations is simply another model, but this time not coded in a computer language but rather formed by the individual observer. We submit that it would be more productive to initiate a process where the norm is that models and observations are joined to strengthen both. In the end, neither method is the goal, but both are useful tools for disclosing the truth. Biased views on either observational or modeling approaches would limit us from achieving this goal.

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.

Vibration and Dynamic Analysis of Right-Angle Geared Drives

<div class="section abstract"><div class="htmlview paragraph">The dynamics of hypoid or spiral bevel gears like most high-speed precision gears employed in the powertrains of automobiles, commercial trucks, and off highway vehicles are significantly influenced by the design of the shafts. The finite element modeling approach is one of the useful methodologies applied to perform gear dynamic analysis. One of the major advantages of the finite element modeling approach is that it can account for the gear-shaft-bearing assembly design more accurately than other modeling approaches, for example, the lumped parameter modeling approach. In this paper, the finite element formulation, which can generally represent more complete characteristics of the gear-shaft-bearing assembly design, is employed to investigate how the temperature change, shaft material type and shaft size influence the dynamics of spiral bevel gear system.</div></div>

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.

Transmission chain error elimination for gear hobbing machines based on classified compensation theory and frequency response identification

This paper proposes a novel classified compensation method considering frequency response to eliminate the transmission chain error (TCE) of gear hobbing machines. Based on error source analysis and Discrete Fourier Transform (DFT), the measured TCE was firstly decomposed into different error components, including the integer harmonic, the non-integer harmonic and the other. A classified compensation theory was then presented, in which the Measurement System Error Compensation (MSEC) and the software axis were used to compensate the first two types of error components, respectively. Then, the frequency response identification for the C-axis control system was performed, and the final compensation values were calculated and integrated into the classified compensation process. The experimental results on a YS3120-type gear hobbing machine showed that the peak-to-peak value of TCE was reduced by 85.5% and that both the integer and non-integer harmonic errors were effectively compensated. It lays the foundation for gear precision hobbing.

The heat treatment effect on the surface characteristics of 9310 steel gear

Gear is one of the key parts of aviation industry. With the rapid development of the aviation industry, the design and precision of gears, in particular 9310 steel ones, are permanently improved. This paper focuses on the heat treatment effect on the surface performance of 9310 steel gear. The heat treatment simulation of aviation gear is carried out the DEFORM-3D software. The effects of quenching and tempering temperature on the surface hardness and residual stress of gear are analyzed, which provides a theoretical basis for the heat treatment improvement of 9310 steel gear.

Below the Surface at EMO

Andrew Allcock provides a fast recap on high precision gear grinding developments at the recent EMO show. They highlight the drive for ever higher precision gears to support the needs of electric vehicle gearboxes, robots and the aerospace industry

Estimation of residual stresses in gear form grinding using finite element analysis and experimental study based on grinding force and heat flux distribution models

Form grinding is one of the most important finishing methods to produce precision gears with high surface quality; however, the generation of high temperatures in the ground zone due to very high energy density induces a complex residual stress field during this process. In the present research, temperature distributions in the workpiece were examined using the finite element method (FEM). The heat generation process was assumed as a three-dimensional distribution of moving heat flux, and different grinding factors, including nonlinear distribution of tangential grinding force, grinding parameters, heat partition ratio along the tooth profile, and triangularly distributed heat source along the contact arc, were considered for thermal analysis. The workpiece temperature field was used as thermal loading in stress calculations, and thermal stresses were determined by thermal elastic–plastic FEM with temperature-dependent material properties and a bilinear kinematic hardening model. Further, grinding forces along the tooth profile were measured using a force dynamometer; surface temperatures were estimated by thermocouples pre-embedded along tooth profile; and surface residual stresses in both grinding direction and tooth profile direction were measured by X-ray diffraction (XRD) analysis. Experimental results of temperatures and residual stresses were utilized to validate the FEM results, and the comparison between numerical and experimental results suggests that the proposed model can be adopted to estimate residual stresses in gear form grinding.

Thermal characteristics testing and thermal error modeling on a worm gear grinding machine considering cutting fluid thermal effect

The coolant absorbing cutting heat has strong influence on thermal behaviors for high precision machine tool using flood cooling technique. However, the majority of applied thermal error compensation models are without considering cutting fluid thermal effect, which results in poor simulation accuracy of thermal deformation. This paper experimentally investigated the effect of coolant temperature on the thermal characteristics of a worm gear precision grinding machine. Experiments were carried out under three conditions: no-load with coolant, no-load with heated coolant, and load test. Moreover, a real-time thermal error compensation model was theoretically developed and validated based on the experimental data involving the cutting fluid thermal effect. The results show that the temperature distribution of the machine tool was more uniform and the temperature gradient was decreased when the grinding heat was partially considered using heated coolant, which indicates that coolant can positively affect the thermal behavior if it is controlled to flow correctly. The thermal error compensation model was built based on the optimal four temperature variables and with a high accurate prediction and robustness. For the no-load operating conditions, the maximum absolute errors and mean absolute errors are 2.7 μm and 1.5 μm respectively. For the load operating conditions, the prediction accuracy of the model built by no-load measuring data is also greatly improved because the grinding heat is partially considered by heated coolant in the no-load test. And the maximum prediction error is 13.0% when the influence of the feed drive system adjustment is considered.

Optical Inspection System for Gear Tooth Surfaces Using a Projection Moiré Method.

The demand for rapid online optical inspection of gear tooth surfaces is increasing, especially for precision gears. In this study, a non-contact optical measurement method was established for the inspection of gear tooth surfaces. For the system architecture, a halogen lamp was selected as the light source, and a collimated beam was produced by an autocollimator. Subsequently, moiré fringes were formed as the collimated beam went through the two linear gratings. The moiré fringes projected on the gear tooth surface were recorded with a charge-coupled device (CCD) camera, and the contour of the gear tooth surface was estimated and reconstructed from the phase information of the fringes by our developed computer codes. To verify the accuracy of the system, a spur gear tooth surface measured by a commercial coordinate measuring machine (CMM) was defined as the reference tooth profile. The tooth topography, involute profile deviation, and axial-direction deviation were successfully calculated by measuring the deviation of the optically measured surface based on the reference gear tooth profiles measured using the CMM.

Analysis of Dimensional Variations of Precision Gear Forging Die Geometry Due to Shrink Fit

The usual way to shrink fit design for precision forging dies are made by thick wall cylinder approach; i.e., taking the pitch diameter of the gear as bore diameter of the die insert without considering gear tooth shape. However, the compressive pre-stress due to the shrink fitting causes dimensional variations on the gear profile of the die insert. The dimensional accuracy of the final product is dependent on the accuracy of the gear die. Therefore, the dimensional variations due to shrink fit must be pre-determined and the gear tooth profile on the die insert modified accordingly. In this study, the dimensional variations of the precision spur gear forging die because of shrink fitting are analyzed by finite element method and the results are compared with the experimental ones. The results show that the FE model is successful to simulate the cylindrical die and agree well with thick wall cylinder approach and the experimental measurements. However, both the experimental measurements and the finite element results of gear die predict much higher radial displacements than the results of cylindrical die. Therefore, the determination of shape change of the gear die profile is beyond the capability of the thick wall cylindrical approach.

Research on High-Precision Form Grinding Technology of Gear Based on Ambient Temperature Adaptability

The thermal error of high-precision computer numerical control (CNC) form grinding machine has become the critical factor affecting its locating precision. Because the thermal error is more complicated to be measured directly, most of the measurement tests are usually aimed at no-load conditions. In this article, a method to evaluate the machine tool thermal error based on the principle of tooth profile error through the gear grinding precision is presented. Based on high-precision CNC form grinding machine need to maintain isoperibol, this paper proposed the ambient temperature as a variable, for different ambient temperature to measure the thermal error of the machine tool. According to the measurement results of the thermal error, the method of partial least squares neural network is used to structure the thermal error prediction model of the machine tool. The experimental data show that the grade of the gear precision can reach four levels at different temperatures. This approach shows a promising prospect in the application of high-precision CNC gear form grinding machine in the future.

A study on the design of slicing cutter for cycloid gear based on conjugate theory

In order to improve the machining precision and efficiency of cycloid gear, a design method of cycloidal slicing cutter is proposed based on the conjugate surface principle. An error-free cutting edge is picked out from the conjugate surface of the cycloid tooth surface. In order to construct a rake face with uniform rake angle, some ideal lines that pass through the points on the cutting edge are constructed according to the definition of working rake angle. The rake face is fitted by these lines using cubic B-spline surface. The flank face is constructed by the ideal cutting edges which would be obtained after cutter resharpening in theory. For this construction, some new conjugate surfaces of the tooth surface are calculated considering that the center distance between workpiece and cutter would decrease after every resharpening. The cutting edges are designed on these conjugate surfaces. The flank face is fitted by these cutting edges using cubic B-spline surface. At last, the feasibility of this design method is verified by a design example, machining simulation, and machining test.

Modeling and adaptive compensation of tooth surface contour error for internal gearing power honing

The machining of high precision gears requires a strict and accurate co-movement relationship controlled by the electronic gearbox between the moving axes of the gear machine tools. This article proposes a tooth surface contour error modeling method and an adaptive electronic gearbox cross-coupling controller for internal gearing power honing. First, the electronic gearbox model is structured according to the generative machining principle of internal gearing power honing and the tooth surface contour error is established by means of homogeneous coordinate transformation and meshing principle. Then, the adaptive electronic gearbox cross-coupling controller is designed, which comprises the electronic gearbox cross-coupling controller and the fuzzy proportional–integral–derivative controllers whose universes of membership functions in fuzzy rules are optimized by particle swarm optimization to improve the adaptability and robustness to disturbance fluctuation and model uncertainty of the system. Finally, experiments are carried out on a self-developed gear numerical control system. The results have demonstrated that the estimated tooth surface contour error using the proposed method is very close to the actual one, and the proposed adaptive electronic gearbox cross-coupling controller can effectively reduce the tracking error and the tooth surface contour error when compared to the electronic gearbox cross-coupling controller and non–electronic gearbox cross-coupling controller (electronic gearbox controller without cross-coupling and adaptive compensation).

A manufacturing error measurement methodology for a rotary vector reducer cycloidal gear based on a gear measuring center

A manufacturing error of a cycloidal gear is the key factor affecting the transmission accuracy of a robot rotary vector (RV) reducer. A methodology is proposed to realize the digitized measurement and data processing of the cycloidal gear manufacturing error based on the gear measuring center, which can quickly and accurately measure and evaluate the manufacturing error of the cycloidal gear by using both the whole tooth profile measurement and a single tooth profile measurement. By analyzing the particularity of the cycloidal profile and its effect on the actual meshing characteristics of the RV transmission, the cycloid profile measurement strategy is planned, and the theoretical profile model and error measurement model of cycloid-pin gear transmission are established. Through the digital processing technology, the theoretical trajectory of the probe and the normal vector of the measured point are calculated. By means of precision measurement principle and error compensation theory, a mathematical model for the accurate calculation and data processing of manufacturing error is constructed, and the actual manufacturing error of the cycloidal gear is obtained by the optimization iterative solution. Finally, the measurement experiment of the cycloidal gear tooth profile is carried out on the gear measuring center and the HEXAGON coordinate measuring machine, respectively. The measurement results verify the correctness and validity of the measurement theory and method. This methodology will provide the basis for the accurate evaluation and the effective control of manufacturing precision of the cycloidal gear in a robot RV reducer.