Gear Module Research Articles

Research on Stress Intensity Factor of Gear Crack and its Variation with Changes of Gear Parameters

Used the theory of linear fracture mechanics and FEM, the two-dimensional model of single-tooth gear is established under the environment of ANSYS. The stress intensity factor(SIF) is analyzed when gear crack occurs and the variation of SIFs is discussed with changes of crack length, gear module, number of teeth, load when gear crack emerges at the pitch circle and tooth root respectively, and the influence of different cracked directions on tooth root is studied; The pragmatic expression of SIFs KI, KII have been brought forth with the results obtained by FEM. These establishes a good foundation on the fracture analysis and diagnosis of gear

The Influence of Gear Parameters on Oil Film Thickness of Tooth Surface

Applying elastic-hydrodynamic lubrication theory, oil film thickness of tooth surface was studies in accordance with the quasi-steady state. This paper focused on the influence of gear parameters such as gear ratio, module and center distance on the thickness of oil film of tooth flank. The results show, as speed ratio increases, oil film thickness increases significantly. When the number of teeth is fixed, oil film thickness increases significantly with the increase of module. When center distance is fixed, oil film thickness declines greatly with the increase of module in both into meshing and out of meshing points. Therefore when center distance is fixed, less module and more teeth are selected，on the condition that gear intensity is met. By results analyzing, the minimal oil film thickness may occur in the single tooth meshing area and into meshing or out of meshing points.

Improvements to the Design of a Compact Robot for Minimally Invasive Surgery

Surgical manipulation has been successfully demonstrated using a robotic spherical serial mechanism (called CoBRASurge) having a remote center of rotation driven through a compact bevel-geared system. This cost-effective prototype confirmed surgical robots do not have to be large and expensive machines to operate effectively. After testing and assessing the device, several key design changes were proposed for a second CoBRASurge robot, which would significantly increase the overall effectiveness of the device. These design changes were found after considering the following desirable characteristics: reliability, compactness, precision, protection from contamination, and flexibility in initial setup. These redesign characteristics led to improvements including an increase in gear transmission accuracy by decreasing gear module, implementation of a motor housing to protect against outside contamination, a new rack and pinion driving assembly for a more robust tool translation, decreased volume and weight for ease of use and overall effectiveness, and a new mounting system for a quicker and easier initial setup process. It is believed that these features will further allow the operating surgeon to more effectively complete tasks in less time, and with increased ease as compared with current laparoscopic surgery techniques, while also making multirobot cooperating interventions more feasible.

Gear Precision and Cutting Force in Dry Hobbing Gear Cutting for Gears Made of Brass Material

Gear precision measurement was carried out for gear with tooth number z=17, gear module mn=0.5, tooth width b=10mm, spur gear design and made using JIS C 3604 brass material. Cutting force measurement was carried out for gear with z=30, mn=1.75, spur gear, and JIS C 3604 brass material. Main results are as follows: (1) Gear precision and cutting force was almost the same in both dry and wet cutting. (2) Process capability index Cp of tooth profile errors were almost the same in both dry and wet hobbing gear cutting, and 5.9 to 8.1. Cp of tooth lead errors was 5.8 to 10.7. It was concluded that dry hobbing gear cutting of brass material has a sufficient production capacity. (3) Almost the same gear precision in both dry and wet hobbing gear cutting was considered because cutting forces were also same.

1309 歯切り用総形フライスカッタに関する研究(歯車の加工法,一般講演)

An insert-type formed gear cutter with positive both side and rake angles for cutting large module gears was designed and manufactured. The shape of insert and design parameters of the cutter were interactively decided in consideration of interference and a relief angle at a flank face using the software developed in this paper. Cutting tests with trial-made gear cutter were carried out. As the results, sufficient accuracy as a cutter for roughing large module gears was obtained.

Oil Churning Power Losses of a Gear Pair: Experiments and Model Validation

This paper presents the results of an experimental study on load-independent (spin) power losses of spur gear pairs operating under dip-lubricated conditions. The experiments were performed over a wide range of operating speed, temperature, oil levels, and key gear design parameters to quantify their influence on spin power losses. The measurements indicate that the static oil level, rotational speed, and face width of gears have a significant impact on spin power losses compared with other parameters such as oil temperature, gear module, and the direction of gear rotation. A physics-based gear pair spin power loss formulation that was proposed in a companion paper (Seetharaman and Kahraman, 2009, “Load-Independent Spin Power Losses of a Spur Gear Pair: Model Formulation,” ASME J. Tribol., 131, p. 022201) was used to simulate these experiments. Direct comparisons between the model predictions and measurements are provided at the end to demonstrate that the model is capable of predicting the measured spin power loss values as well as the measured parameter sensitivities reasonably well.

Optimizing modular gears in the mechanical drive of beam pumps

In the present work, we consider the optimization of a two-flow, three-stage modular gear by means of a redesigned mechanical drive for beam pumps. Oscillations of modular-gear shafts with added gears and two-crown gear modules arise under the action of external periodic forces at the point of beam suspension and are related to elastic deformation of the mechanical system. Small oscillations relative to the equilibrium position become dangerous for the shafts and the structure as a whole when the frequency of the perturbing force approaches the eigenfrequency of the system, i.e., at resonance. The stress in the shafts then increases significantly and is mainly due not to an external force but to inertial forces in the oscillating masses. To maintain the strength of the gear system, resonance must be avoided. Hence, we see the importance of vibrational design of the structure, in which the eigenfrequencies of its components are determined and permissible speed ranges are established. The drive shafts and driven shafts of two-flow threeand five-stage modular gear systems connected to gears and two-crown gear modules have infinitely many degrees of freedom. Mathematical description of this system may be based on partial differential equations. To simplify the solution, the system with a continuous parameter distribution is replaced by a system with a discrete distribution, characterized by a finite number of degrees of freedom. The two-crown gear modules on the driving and driven shafts are assumed to be floating, weightless, and undeformable. This permits transition to a system with a point mass, which has one degree of freedom, and to description of the system’s motion using an ordinary differential equation. Obviously, both torsional and flexural oscillations are most significant for the high-speed shaft (the drive shaft) of the gear system. Vibration of this shaft is mainly associated with flexural deformation. In approximate calculations, the drive shaft with a twocrown gear module may be regarded as a rod with a point mass (disk), hinged to rigid bearings. The mass of the shaft is reduced to the mass of the gear module by summation, taking account of the reduction coefficient, which depends on the positions of the bearings and the gear module.

GM-10 NEW DEVELOPMENTS IN GRINDING OF LARGE MODULE GEARS(MANUFACTURING OF GEARS)

In the last years the demand for grinding machines of large module gears increased very strong. New productive solutions were developed. The profile grinding technology was improved. By using the fast feed rate grinding it is possible to do rough grinding with much higher specific metal removing rates. Also the non-productive auxiliary times are reduced. Before grinding the gears they are measured completely with high-speed measuring. Based on these results the grinding process will be optimized to prevent grinding times without contact of grinding wheel and gear. Another possibility to increase quality and productivity is the combination of processes in one machine. The grinding of the gear teeth, the bore and the face of a planetary gear will be executed in one machine. The results are presented. The continuous generating grinding was further developed. Now it is possible to grind large module gears up to a gear diameter of 1000 mm and a module of 10. The productivity could be increased significant. The specifics and the problems in comparison with profile grinding are discussed. An outlook to future developments is given.

Study on the Composite Measuring Method for Small Module Gears

The detection technique of small module gears has a very important research and application value. In this paper, a composite measuring method is presented based on combining traditional mechanical contact measurement with optical image non-contact measurement. First of all, this paper analyzes the basic principle of composite probe composed of optical fiber stylus and CCD imaging system. The tail-end of the stylus is shaped into a micro-sphere, where a small refection mirror is designed. When the laser is transmitted through the fiber, a round facula can be seen from the CCD camera. The micro-sphere is kept contact with the surface of the measured gear at the time of measuring and the error of the measured gear will be reflected by the offset of the facula center. Meanwhile, the sub-pixel extraction algorithm for the center of facula image is presented. Then the calibration principle and method of probe system is analyzed in detail. Finally, the data processing principle of the presented method is discussed for gear measurement.

A Novel Design of a Brushless DC Motor Integrated with an Embedded Planetary Gear Train

This paper presents a novel design by integrating a planetary gear train (PGT) within a brushless dc (BLDC) motor to be a compact structure assembly. It provides functional and structural integrations to overcome the inherent disadvantages of the traditional designs. The effects of the gear teeth on the magnetostatic field of the BLDC motor associated with the kinematics of the PGT are investigated. By designing the number of gear teeth integrated on the stator and magnet poles on the rotor, the cogging torque of the proposed motor configuration is effectively reduced. The magnetic field distribution and the output torque of the novel design with different standard gear modules are numerically calculated by two-dimensional finite-element analysis. Through the kinematic analysis that utilizes the fundamental circuits, feasible solutions for the number of gear teeth of the PGT are determined to meet the desired speed ratio

Teeth-Number Synthesis of a Multispeed Planetary Transmission Using an Estimation of Distribution Algorithm

The gear-teeth number synthesis of an automatic planetary transmission used in automobiles is formulated as a constrained optimization problem that is solved with the aid of an Estimation of Distribution Algorithm. The design parameters are the teeth number of each gear, the number of multiple planets and gear module, while the objective function is defined as the departure between the imposed and the actual transmission ratios, constrained by teeth-undercut avoidance, limiting the maximum overall diameter of the transmission and ensuring proper spacing of multiple planets. For the actual case of a 3+1 speed Ravigneaux planetary transmission, the design space of the problem is explored using a newly introduced hyperfunction visualization technique, and the effect of various constraints highlighted. Global optimum results are also presented.

Computerized tooth profile generation and analysis of characteristics of elliptical gears with circular-arc teeth

This study describes rack cutters with circular-arc profile teeth to generate elliptical gears which rotate about one of their foci. A mathematical model for elliptical gears with circular-arc teeth is developed according to gear theory. The influence of the design parameters, such as the number of teeth, gear module, pressure angle at the pitch point and the major-axis, are investigated. The effects of the circular-arc radius of the rack cutter on both the undercutting of teeth and on pointed teeth of the generated circular-arc elliptical gear are also studied. Three numerical examples are presented to elucidate the generation of gear tooth profiles using the proposed mathematical model, and to investigate the phenomena of tooth undercutting and pointed teeth.

Gear Forging: Mathematical Modeling and Experimental Validation

A useful facility to the adaptation of precision gear forging by industry, is a quick method of load and flow predictions. In this work, the process of precision forging spur and helical gears is modeled by means of an upper bound analysis. A new velocity field, which includes bulging of the tooth form, is proposed and a computerized incremental procedure for the prediction of the bulged surface profile of the teeth, the forging load, and its increase due to corner filling is presented. The effect of workpiece/die interface friction, gear module, numbers of teeth, helix angle, gear height and bore size on forging pressure are determined. Experimental results obtained for room and elevated temperature forgings compared well with theoretical predictions.

Design of Input Coupled Split Power Transmissions, Arrangements, and Their Characteristics

This paper presents input coupled split power transmissions, arrangements and comparisons between the single and dual stage designs. Selection of the shift point between stages is discussed. Mathematical models for the transmission are constructed. An algorithm is developed for an efficiency optimization routine. The effects of the gear material strength, gear module, gear tooth width, and shaft offset on the efficiency are determined. Power loss contributions are presented in conjunction with their effect on the overall transmission efficiency.

Decision Method of Optimum Specification of Involute Helical Gears for High Load Carrying Capacity (2nd Report, Design Algorithm and Endurance Test)

Motor power of vehicles is increasing to accomplish more speedy and comfortable drive. On the other hand, smaller and lighter drive train is required to expand the internal space of vehicles. Gears used for those drive trains must therefore have high load carrying capacity. In this report, gearbox whose center distance, gear ratio and face width are fixed, is treated and the influence of module, number of teeth and profile modification of tooth flank on load carrying capacity is investigated, where pressure angle, helix angle, addendum modification factor and tooth depth are optimized by the method proposed in the previous report. There is an optimum value of module in load carrying capacity and the characteristic of the optimum module depends on tooth number. Tooth profile modification for larger module gear contributes to improve load carrying capacity, but that has small effects for small module gears. Asymmetrical tooth profile form correction has little advantage if gear dimensions are optimized. Total decision method of gear specification for high load carrying capacity is proposed, which includes the decision of module, number of teeth, pressure angle, helix angle, addendum modification factor and tooth depth and profile modification of tooth flank as well. Endurance test of the gears designed by the proposed method is carried out and the improvement in gear life is confirmed.

液晶マスクを用いた非積層マイクロ光造形法に関する研究（第２報）―液晶動画像を用いた薄層型積層造形―

This paper presents a new micro stereolithography technique to fabricate a micro 3D structure rapidly and precisely by using LCD live-motion mask. Exposure through the live-motion mask fabricates each thin layer precisely without scanning. The extremely thin layers are continuously solidified by providing liquid resin synchronized with the mask changes. As a result, a 3D object is fabricated by continuous laminations of these thin layers.In order to verify the feasibility, we developed LCD micro stereolithography system based on 3D-CAD and performed some experiments. The lateral and depth resolutions reached 3μm and 1μm, respectively. It took only about 7 minutes to fabricate a pyramidal shape consisting of 100 layers. A micro two-step gear with shaft was fabricated precisely and rapidly without assembling. The module of this two-step gear is only 20μm. The number of the tooth is 100 for the large gear and 25 for small one. These results show that our proposed method has possibility of precise micro fabrication in practical use.

GM-20 CARBURIZING OF BIG MODULE AND LARGE DIAMETER GEARS(GEAR MANUFACTURING)

The carburizing gears have higher strength and better life-time compared with induction-hardening or quench-tempered gears, but in big-module gears, the carburizing heat-treatment becomes time-consuming, cost-expensive and sometimes cannot achieved good hardness due to the big mass-effect, and it is not easy to reduce the distortion of gears during heat treatment. In order to achieve good surface hardness of carburizing layer, it is necessary to precisely control the carbon content distribution. Since the carburizing time is much longer for big module gears due to deeper case-depth requirement, after carburizing it is necessary to have intermediate cooling under 650℃ to get finer grain size and better mechanical properties. By using a carburizing furnace equipped with fast cooling function, the work-pieces can proceeding intermediate cooling and heat up again to quench temperature inside the same furnace. This can reduce the total heat-treatment time as well as costs remarkably. The distortion comes from heat treatment is not avoidable, by improving the arrangement of load we can reduce the distortion and then reduce the manufacturing costs.

1003 光切断法による微小モジュール歯車の歯形精度測定 : 2方向からの光切断像を用いた測定(O.S.10-1 精密機器の高度化)(オーガナイズドセッション10 : 情報機器/精密機器の高度化)

1003 光切断法による微小モジュール歯車の歯形精度測定 : 2方向からの光切断像を用いた測定(O.S.10-1 精密機器の高度化)(オーガナイズドセッション10 : 情報機器/精密機器の高度化)

Studies of Influences of Geometrical Errors to Final Performances in Small Backlash Planetary Gears. Relations Among Position Deviations of Planet Gears, Target of Backlash and Non-Working Flank Load.

Reductions of meshing and bearing clearances are requisite in design and production of small backlash planetary gears. In this case, however, there is a risk of losing proper load distribution to each planet gears, which has risk of occurrence of non-working flank load. The state of non-working flank load increases unnecessarily working flank load and gives some undesirable influences on reliability of planetary gears. To solve this problem, this paper aims to analyze quantitatively about relations between the load distribution and position deviations of planet gears. These deviations are considered to be most influential to the problem in reality. About one type of the device with 4 planet gears, 20 kinds of combination pattern of the position deviations are selected out, and the influences of backlash, reduction ratio and gear module to the above relations are clarified. Consequently, allowable position deviations to avoid the state of non-working flank load are found out for various conditions and useful materials for design are obtained.

微小モジュール歯車の歯形精度測定への光切断法の応用 ４ 細線化についての考察

In this study, with the aim of measuring the tooth profile error of minute module gears rapidly and precisely, a new measuring method that applies the optical cutting method is developed. This report considers about image processing method to get the tooth profiles exactly. Applying the Laplacian filter to the optical cutting images grayed into 256 levels has effect of emphasizing edges of image, and values of the threshold level become less effective to get binary images. Consequently, the medial lines of the images also can be extracted from the binary images in independence of the threshold levels. This could improve stability and reliability of measurements.