bluuebunny/crossref_metadata_2025 huggingface dataset:
Simulations of Gear-Rolling Element Bearing Interactions in Geared Transmissions
Authors: Lahmar F. , Velex P.
Published: June 2008

The modular model of geared systems presented in this paper makes it possible to simultaneously account for the contact conditions in gears and rolling element bearings. Gears are modeled as two rigid cylinders connected by distributed mesh stiffnesses while ball and roller bearings contribute to the equations of motion as time-varying, non-linear external forces. Solutions are obtained by combining a Newmark time-step integration scheme, a Newton-Raphson method for ball bearing non-linearity and a normal contact algorithm that deals with the contact problem between the teeth. It is found that the static gear-bearing couplings are generally more important than the dynamic couplings with a significant influence of the gear on the bearing response. Finally, it is shown that, in certain conditions, bearings can generate non-linear parametric excitations of the same orders of magnitude as those associated with the meshing of helical gears.
Dynamic Analysis of Multi-Mesh Helical Gear Sets by Finite Elements
Authors: Kubur M. , Kahraman A. , Zini D. M. , Kienzle K.
Published: June 2008

A dynamic model of a multi-shaft helical gear reduction unit is proposed in this study. The model consists of a finite element model of shaft structures combined with a three-dimensional discrete model of helical gear pairs. Both counter-shaft reduction and idler configurations are included in the model. Bearing and housing flexibilities are included in the model as well. Free and forced vibrations were studied to quantify the influence of a number of system parameters including, shaft position angles, shaft dimensions, bearing types and locations, and gear mesh phasing relationships. A limited parametric study is performed to demonstrate the sensitivity of the model to certain system parameters.
The Development of the Traction Drive Mechanism Made of the Plastic Magnet
Authors: Shoji Akira , Kawashima Giichi
Published: June 2008

This paper is the one that it was described to have developed the traction drive by using the plastic hard magnet. The plastics material was used to research by the following reasons. The plastics material can mold it. As a result, it processes complex and it is possible to make it to the magnet. In addition, it is possible to mass-produce, it is light, and it is also possible that the miniaturization reduces possible and the cost. Next, the mechanism of the traction drive is described. It rotates by being circumscribed by non-contact, and inscribing two plastic hard rings as if the gear. N pole and S pole are divided equally in the direction of the circumference of the ring. It becomes by these as if the match of the god with teeth and teeth. These devices are commonly called “Gear without teeth”. Some doughnut disks with a different outside diameter were produced. Each disk is made magnetism. Each disk was set, and assembled to one disk. The disk is molded with the plastic hard. The plastics material used the one that the ferrite powder was mixed with the polyacetal resin. Making to magnetism is possible by the magnetization technology. The mechanism, molding, making to magnetism, and the magnetic induction, etc. were examined in the experiment. The development of non-contact made of plastic hard traction drive device was proven to be possible by this research.
Coupled Belt-Pulley Vibration in Serpentine Drives With Belt Bending Stiffness
Authors: Kong Lingyuan , Parker Robert G.
Published: June 2008

A method is developed to evaluate the natural frequencies and vibration modes of serpentine belt drives where the belt is modeled as a moving beam with bending stiffness. Inclusion of bending stiffness leads to belt-pulley coupling not captured in moving string models. New dynamic characteristics of the system induced by the belt bending stiffness are investigated. The belt-pulley coupling is studied through the evolution of the vibration modes. When the belt-pulley coupling is strong, the dynamic behavior of the system is quite different from that of the string model where there is no such coupling. The effects of major design variables on the system are discussed. The spatial discretization can be used to solve other hybrid continuous/discrete eigenvalue problems.
A Model of the Dynamic Behavior of Spur Gears With Consideration of Off-Line-of-Action Contacts
Authors: Duverger O. , Velex P. , Vedmar L. , Sainsot P.
Published: June 2008

Because of deflections under load, contacts on tooth flanks can occur outside the theoretical plane of action between nonconjugated profiles especially when tooth modifications are not appropriate. The main objective of the present paper is to introduce an original model of the dynamic behavior of spur gears when submitted to these particular meshing conditions. The pinion and the gear of a pair are modeled as two rigid cylinders linked by stiffnesses and dampers whose amplitudes and orientations vary in order to simulate the evolutions of the meshing conditions. For the sake of simplicity, only three torsional degrees-of-freedom on the pinion, the gear and the motor are considered. The results show that the contacts between non-conjugated flanks lead to a particular dynamic behavior characterized by i) an actual contact ratio larger than the theoretical one, ii) the possibility of impacts at engagement whose amplitudes depend on transmitted loads and speeds.
Analysis of the Mesh Characteristics of Hypoid Gear Pair Dynamics
Authors: Wang Hongbin , Lim Teik C.
Published: June 2008

Most of the current models employed in analyzing the dynamics of hypoid or bevel gear pair systems are based on approximate representations of the tooth meshing kinematics. The approximate gear mesh representations that account for tooth contact position and load line of action vector are normally derived from experimental observations or semi-empirical considerations. Moreover, the resultant dynamic model is often linear with time-invariant coefficients. The fundamental behavior of the time-varying mesh points and load line of action vectors, which can be important characteristics of the hypoid gear pair system, have not been fully explored. To address this issue more in-depth, the current study examines the inherent spatial and time-varying tooth meshing positions and normal load vectors of typical hypoid gear pairs applied in automotive systems. Numerical results of the quasi-static gear tooth contact analysis using 3-dimensional finite element models are compared to the theoretical data produced by a set of analytical tooth contact analysis equations based strictly on gear geometry formulation. The potential effects of gear meshing characteristics on dynamic transmission error as well as torsional vibration response are also discussed.
Rotational Vibration of a Spur Gear Pair Having Tooth Helix Deviation: Effect of Lead Modifications
Authors: Ogawa Yuichi , Matsumura Shigeki , Houjoh Haruo , Sato Taichi
Published: June 2008

Lead form modification has been used to avoid detrimental effects of tooth helix deviation caused by manufacturing error or misalignment of a gear pair from the viewpoint of tooth strength on gear design. Hence parabolic crowning, elliptic crowning and end relief are adopted conventionally as a typical modified lead form. However the effect of both the shape and the amount of the lead modification on dynamic characteristics of the gear pair has not been made clear enough yet. Using the simulator which was developed by authors and is capable of analyzing vibration response of a pair of spur gear considering tooth surface deviation, the present paper shows that the effect of a proper lead crowning is to maintain the designed dynamic behavior even when tooth helix slope deviation exists, or that is equivalent to misalignment. An optimum form of end relief approximated to that of crowning is determined by the least square method. In addition, since the amplitude of gear vibration is sensitive to the tooth profile error, importance of considering tip relief is presented.
Cutter Interchangeability for Spiral-Bevel and Hypoid Gear Manufacturing
Authors: Gosselin Claude , Masseth Jack , Liang Wei
Published: June 2008

In the manufacturing of spiral-bevel and hypoid gears, circular cutter dimensions are usually based on the desired performance of a gear set. In large manufacturing operations, where several hundred gear geometries may have been cut over the years, the necessary cutter inventory may become quite large since the cutter diameters will differ from one geometry to another, which results in used storage space and associated costs in purchasing and maintaining the cutter parts. Interchangeability of cutters is therefore of significant interest to reduce cost while maintaining approved tooth geometries. An algorithm is presented which allows the use of a different cutter, either in diameter and/or pressure angle, to obtain the same tooth flank surface topography. A test case is presented to illustrate the usefulness of the method: the OB cutter diameter of an hypoid pinion is changed from 8.9500" to 9.1000". CMM results and the comparison of the bearing patterns before and after change show excellent correlation, and indicate that the new pinion can be used in place of the original pinion without performance or quality problems. Significant cost reductions may be obtained with the application of the method.
A Study on Reducing the Gear Tooth Profile Error by Finish Roll Forming
Authors: Uematsu Seizo , Lyu Sung-Ki , Houser Donald R. , Lim Ju-Suck , Lu Long
Published: June 2008

This paper deals with the tooth profile error of spur gears that have been finished by roll forming. First, we present experimental data that confirms that the tooth profile error is a synthesis of a concave error and a pressure angle error. Since various types of tooth profile errors appear in the experiments, evaluation parameters are introduced for rolling gears so that profile quality may be objectively evaluated. Using these evaluation parameters, the relationship among the tooth profile error, the addendum modification factor (A. M. factor), and the tool loading force are verified. The character of concave error, pressure angle error and tool loading force of finish roll forming by using a forced displacement method are verified. This study makes clear that the tool loading force of finish roll forming is a very important factor that affects involute tooth profile error. The results of the experiment and analysis show that the proposed method reduces both concave and pressure angle errors.
Tip-Fillet Interference in Cylindrical Gears
Authors: Polder Jan Willem , Broekhuisen Hans
Published: June 2008

The occurrence of severe tip-fillet interference which could not be explained by existing formulas, and the tendency of modern design rules to go up to the geometrical limits, were reasons to develop three new views. The old geometrical condition proved to be incorrect. It required the usable flank to exceed the active flank, which guarantied only a correct mating on the line of action. However, while the involute flanks are mating regularly in an arbitrary position, then outside the line of action the tip of the pinion may penetrate the fillet of the mating gear. The possible tip-fillet interference is not restricted to one single position, but takes up a certain part of the path of action. The deduction of a completely new geometrical condition was based on a positive free distance between tip and fillet in each position. Secondly, a condition based exclusively on nominal dimensions did not suffice. The neglect of inaccuracies and deformations was as irresponsible as neglecting functional backlash in any conventional gear pair. Emphatically, the geometrical condition has to answer the same influences. Therefore, a new algorithm includes a relation with maximal backlash. Thirdly, by introducing a quality dependent backlash function in a geometrical condition, there will be more necessity to standardize a clear backlash-related tolerance system than in the past was required for the minimal functional backlash.
Influence of Undercut on the Load Capacity for Involute Teeth With Small Pressure Angle
Authors: Pedrero Jose´ I. , Arte´s Mariano , Garci´a-Masia´ Carlos
Published: June 2008

The minimum number of teeth to avoid undercut on involute spur and helical gears depends on the pressure angle, among some other geometrical parameters. Higher number of teeth is required if the pressure angle becomes smaller. However, the contact ratio may be increased by reducing the pressure angle, which means the load is distributed along a longer line of contact. In many cases, even if undercut arises and teeth are weakened, both effects may result in higher load capacity for the gears. This paper presents a study on the influence of the pressure angle on the contact ratio, and through it on the length of contact and the load capacity, including a discussion on the condition to improve the load capacity by reducing the pressure angle beyond the undercut limit.
Determination of Addendum Modification Coefficients for Spur Gears Operating at Non-Standard Center Distances
Authors: Arikan M. A. Sahir
Published: June 2008

Although it is possible to find some recommended conventional values both for the sum of the addendum modification coefficients and for the allocation of the sum of the addendum modification coefficients (e.g. ISO/TR 4467), a detailed analysis is necessary to determine the addendum modification coefficient values for the desired optimization criteria and the performance since the main objective of the above mentioned sources is to facilitate practical design of non-standard gear drives which will not have problems while operating. They give practical average values within a safe range. In this study, by considering the required gear ratio, center distance and the desired backlash, alternative gear pairs are determined and corresponding gear performance variables are calculated in order to allocate the addendum modification coefficients for the pinion and the gear by using criteria such as: not having undercut or pointed (or excessively-thinned-tip) tooth, having desired proportions for the lengths of the dedendum and addendum portions of the line of action, having maximum contact ratio, having sufficient bottom clearance, having minimum contact stresses, having balanced pinion and gear tooth root stresses, having equal pinion and gear lives, etc.
Simulation of Hobbing for Analysis of Cutting Edge Failure Due to Chip Crush
Authors: Komori Masaharu , Sumi Masaoki , Kubo Aizoh
Published: June 2008

There are great advantages in dry hobbing not only for friendliness on the environment, but also for increasing productivity and for decreasing manufacturing cost. Dry hobbing, however, often causes failures of cutting edge of hob or problems about the surface quality of tooth flank of manufactured gear, which have not been of problem in case of hobbing with cutting oil. Pinching and crushing of generated chips between cutting edge of hob and tooth flank of work gear is considered to be a major cause for those problems. In this report, a calculating method of trace of each cutting edge of hob relative to work gear is compiled to simulate the clearance between cutting edge of hob and tooth flank of work gear. The thickness and form of generated chip and its movement on rake surface of hob tooth during hobbing process can be clarified by consulting the result of this simulation. Probability of pinching of chips between cutting edges of hob and tooth flank can be evaluated by dealing with the relation among the position and width of clearance, chip thickness and direction of chip movement, which contributes to successful dry hobbing.
Remedies for Cutting Edge Failure of Carbide Hob Due to Chip Crush: Some Results of Evaluation by This Method in Automotive Industry
Authors: Komori Masaharu , Sumi Masaoki , Kubo Aizoh
Published: June 2008

Dry hobbing, for friendliness on the environment, for increasing productivity and for decreasing manufacturing cost, often suffers failure of cutting edge of hob or problems about the surface quality of tooth flank of manufactured gear. In the previous report, a simulation method to calculate the clearance between cutting edge of hob and tooth flank of work gear during hobbing process is developed. In this report, this simulation is applied to some practical industrial problems of dry hobbing, i.e. chipping failure of cutting edge of carbide hob and bad coarse scratched surface finish of hobbed tooth flank of manufactured gears, perhaps due to chip crush. The simulation explains the mechanism of such actual failures in detail. On this fact, the “Distance of Single Edge Cutting” of a hob tooth is proposed to be an index of pinching and crushing of chips that could intrude into the clearance between hob cutting edge and tooth flank of work gear. Influencing factors on it are investigated and the bases for finding countermeasures are shown. This method has been applied to some practical cases of problem in mass-production of automotive gears, and good result was confirmed.
Direct Dry Hobbing of High Hardened Material: RGC (Round Bar Gear Cutting) Method
Authors: Fukunaga Keigo , Inoue Syunji , Yonekura Masataka , Sakuragi Isao
Published: June 2008

Almost all customers require gear motor manufacturers to develop low noise, low vibration and low cost gear motors. Low noise and low vibration gear motors can be accomplished only by using high precision gears. The traditional method of manufacturing high precision gears for general industries is to grind the teeth after gear cutting. However, recently, there is now a strong demand to increase productivity and reduce manufacturing cost by using only a hobbing machine. To content these requirements, it is believed that direct dry hobbing after gear material heat treatment is the best manufacturing method. First, 0.45% carbon steel of round gear material was hardened to HRC53-56 by high frequency induction heat treatment till the specified depth. Next, the high hardened material was directly hobbed by special carbide hob installed on a highly rigid CNC (Computer Numerical Control) hobbing machine without using cutting oils. In the other words, the authors have developed Direct Dry Hobbing of High hardened Material, called the RGC (Round bar Gear Cutting) Method. The gears applying the RGC Method were module 0.8 to 1.25 and of helix angle 25°. The gear profile accuracy was JIS Grade 1–2, which is comparable to AGMA Grade 11–12. Gear motors incorporating gears manufactured by the RGC Method have been launched into the market and are now receiving remarkable customers satisfaction as low noise and low vibration gear motors.
Potential of Carbide Tools for High Performance Hobbing
Authors: Klocke Fritz , Winkel Oliver
Published: June 2008

To match the future goals of higher productivity and lower production costs, the cutting speeds and feeds in modern gear hobbing applications have to increase further. In several cases, coated carbide tools have substituted the commonly used HSS tools. Because this leads to production processes working on the upper level of their performance opportunities, the tolerances for deviations from the optimum process settings are getting smaller. To match with this situation, especially in carbide hobbing, all factors that have an influence on the hobbing process like the workpiece geometry, the process parameters and especially the tool design have to be taken into account if a high level of process performance is desired. This essay will present a case study based on two industrial gearings. The investigations include the influence of the tool design concerning coating, substrate, layout and edge preparation on the tool performance. In detail, fundamental base line trials using the analogy process “fly-cutter hobbing” will be presented. Besides several coating and substrate combinations also different tool layouts have been tested. To verify the results, real hobbing trials under industrial production conditions have been carried out as well. Finally, the potential of modern simulation and calculation programs to optimize hobbing processes will be shown. The report aims to give new impulses to the tool design of carbide hobs and an optimized process setting.
New Approach to Computerized Design of Spur and Helical Gears
Authors: Goldfarb V. I. , Tkachev A. A.
Published: June 2008

The approach to the design of spur and helical cylindrical gears is being considered on the basis of application of special type geometrical objects named dynamic blocking contours (DBC) by means of which the rational choice of addendum modification coefficients (profile shift coefficients) of pinion and gearwheel is carried out. The stage of shift coefficients selection by means of DBC is singled into an independent procedure during which some gear qualities may be forecast before basic geometrical and strength calculations, that is, at the initial stage of design. Based on the concept of DBC, the computer-aided design of spur and helical gears has been developed with the practical realization of the stated design principles. In order to provide better obviousness of the design, CAD includes visualization units of meshing process of gear pair and meshing element generation by rack type cutting tool. Educational release of the developed system allows the user to master the methodology and possibilities of gear design on the basis of DBC concept and to evaluate the importance of shift coefficients selection to obtain specified properties of gears.
High-Reduction, High-Torque Gear Reducer Design Emphasizes Compactness
Authors: Surjaatmadja Jim B. , Tucker James C.
Published: June 2008

The design of high-torque, high-reduction gear reducers often requires the use of multi-stage gearing, planetary gear systems, or both. Because these systems contain many independent parts, they often become bulky. When these systems will be used in downhole oilfield equipment, compactness can become a crucial factor. Moreover, downhole oilfield equipment generally requires that areas of the system be reserved to provide some fluid flow-path around the equipment. A unique gear reducer was designed to accommodate this need for compactness. The new reducer system consists of only four gears, two of which are built as a single part. All four gears are positioned roughly concentrically within a donut-like space, and the open center accommodates fluid flow. Unlike other gear reducer systems, this system employs not only a ratio (divisional) method, but also a unique subtraction method. Consequently, a reduction of more than 2000:1 is possible. With this radical design, conventional gear teeth cannot be used if good meshing is desired. Subsequently, a special gear tooth shape was designed to provide surface contact between the teeth. With this special shape, full contact of more than 30% of the teeth can be achieved, compared to one or two teeth in standard designs. Thus, the new system also improves load-transmitting capacity. In this paper, the design of the new gear reducer is discussed in detail. A specific application in which high-pressure, sand-laden slurry is pumped through the center of this gear reducer is also discussed.
Conveying High Torque via an Efficient, High Reduction Ratio, Coaxial, Lightweight A-XYZ Transmission™
Authors: Kuehnle Manfred R.
Published: June 2008

In the past, weight and bulk of high torque gear transmissions were determined by the emphasis on lifetime durability, manufacturability, and manufacturing cost obtainable within the stress limits of classical materials when applying the rules of classical kinematics. In contrast, the Advanced XYZ Transmission (A-XYZ™) uses neither conventional materials nor classical kinematics. Instead, for the purpose of achieving load distribution over many rolling contact “teeth”, the A-XYZ transmission conveys the required torque and speed (power) via a three-dimensional path of motion which combines simultaneous vertical rotation and precessional horizontal motion of the machine elements to achieve a dynamically balanced, reversible, coaxial input/output operation. With this intellectually challenging geometric construct plus the use of new materials, the present and future goals of obtaining lightweight gearboxes, mechanical compactness, compatibility with high-speed prime movers, such as micro-turbines and small, high rpm electric motors, have been achieved. Of course, low weight and high efficiency means more mileage per liter of fuel or KWh of energy available. The low acoustic noise (no clicking teeth) represents a high quality trademark, which all competent mechanical engineers will appreciate.
Gear Defect Diagnosis Using Acoustic Emission
Authors: Mba David
Published: June 2008

It is widely recognised that Acoustic Emission (AE) is gaining ground as a Non-Destructive Technique (NDT) for health diagnosis on rotating machinery. This paper reports on part of an ongoing experimental investigation on the application of acoustic emission for gear defect diagnosis. In addition, a review of experimental investigations on the applicability of acoustic emissions to gear defect diagnosis is presented. It is concluded that AE offers a complimentary tool for health monitoring of gears.
Digital Approach for the Solution of Gearing Problems
Authors: Egorov I. M. , Morrish L.
Published: June 2008

Gear mesh analysis usually involves calculations of gear geometry and mesh parameters at chosen mesh positions. Normally, this is done by solving simultaneous equations describing the processes of gear machining and meshing. Numerical methods usually are used only at the stage of analysis (1), (2). As there are practically no restrictions on modern computers memory, a wider use of a numerical approach is feasible when solving gearing problems. A method is proposed to perform gearing analysis in the following way: the initial information about meshing gears is given not analytically, but via co-ordinates of large number of points on gear teeth surfaces. These can be received either via analytical simulation of a manufacturing process (teeth cutting) or via direct CMM measurements of gears. The coordinates could also be retrieved from a different gear mesh simulation software, thus initial teeth shape data would take into account changes occurring due to meshing under load (e.g., different types of deformations, including wear, temperature deformation etc.). A contact between teeth at several meshing positions is modeled via a direct simulation of ‘bringing two contacting surfaces together’. The described approach allows universal programs for gear mesh analysis to be created. Models of this type work and remain stable for a wide range of input parameters. They are not sensitive to such phenomena like undercutting and edge contact. These models can be used for gear quality control via CMM measurements, for mathematical modeling of the processes of gear cutting, gear meshing and gear wear. They can be adapted for various types of gears (spur, helical, worm, globoidal, spiroidal etc.). Models created via described approach are discussed. They have been verified experimentally on test rigs and in industry.
New Investigation on the Geometry of the Contact in Gear Generation
Authors: Gabiccini Marco , Guiggiani Massimo , Di Puccio Francesca
Published: June 2008

Based on a recently developed geometric approach to the theory of gearing that does not make use of any reference systems [1], this paper presents some useful relations between the geometric properties of the enveloping surface and those of its envelope. Treating vectors as such, that is without expressing their components in any reference systems, it is possible to obtain compact expressions for the coefficients of the first and second fundamental forms of the envelope surface. These coefficients show to be central in the determination of the contact matrix between mating surfaces. Moreover, since this approach is coordinate free, it is valid regardless of the reference frame actually employed to perform calculations and allows a, hopefully, clearer understanding of the roles played by the intrinsic geometric properties of the enveloping surface, the relative position of the gear axes and the gear ratio.
Development of Conical Involute Gears (Beveloids) for Vehicle Transmissions
Authors: Bo¨rner J. , Humm K. , Joachim F.
Published: June 2008

Conical involute gears (beveloids) are used in transmissions with intersecting or skew axes and for backlash-free transmissions with parallel axes. Conical gears are spur or helical gears with variable addendum modification (tooth thickness) across the face width. They can mesh with all gears made with the same tool. The geometry of such gears is generally known, but applications in power transmissions are more or less exceptional. ZF applications so far include marine transmissions with inclined output shafts and low backlash robot transmissions. The latest development has been realized for the AWD version of a six-speed automatic transmission. Here, the torque must be transmitted from a center differential to a front-axle bevel gear. By means of conical spur gears, it has been possible to realize an inclined drive shaft which offers considerable advantages in terms of installation space. This lecture deals with the development of conical gears for vehicle transmissions: basic geometry, design, production and testing.
Dynamic Modeling of a Dual-Clutch Automated Lay-Shaft Transmission
Authors: Zhang Y. , Chen X. , Zhang X. , Tobler W. , Jiang H.
Published: June 2008

This paper presents a systematic model for the simulation and analysis of a power-shift transmission that features a dual-clutch design. The paper models the kinematics, dynamics and control of the transmission for the analysis of powertrain overall performance and shift transient characteristics. The model is implemented in an object-oriented software tool. Analytical formulations and look-up tables are both used for modeling of powertrain components. The vehicle system model is established by integrating the various components and subsystem models according to the transmission structure and control logic. As a numerical example, the model is used for a vehicle equipped with the power-shift transmission to simulate the speed follow-up over a standard EPA drive range and the wide open throttle position performance.
The Autark Hybrid in a Test Vehicle: First Results
Authors: Ho¨hn Bernd-Robert , Pflaum Hermann , Schmidbauer Thomas
Published: June 2008

Nowadays the task to diminish energy consumption and air pollution caused in large shares by road traffic occupies a key issue. One possible approach is the Autark Hybrid, a well balanced configuration of an usual internal ic-engine, an electric motor with dedicated battery system in combination with a CVT of wide ratio range. Main target of the drive train is to reduce fuel consumption. After designing this powertrain at Technische Universita¨t Mu¨nchen a prototype vehicle has been assembled in order to verify the concept under real circumstances. Starting from its standard configuration a compact class vehicle has been modified. The test vehicle already started operation on a roller test bench as well as on separate testing roads and in public road traffic. Function and handling characteristics are demonstrated.
Coroning: High Performance Gear Honing Without Dressing
Authors: Schenk Thomas , Uebel Ulrich , Wo¨lfel Friedrich
Published: June 2008

Gear honing with internally toothed tools was first used as a gear finishing process for improving unfavorable surface conditions of external cylindrical gears after grinding. Stock removal was minimal (less than 0.01 mm) and only dressable tools were used. From the beginning, the multi-directional surface structure created by gear honing was considered beneficial for gear noise performance. But limitations of the early machine and tool technology did not allow for more stock removal. For a long time gear honing represented an additional finishing process, performed after pre-finishing by shaving or grinding. In the early 1990’s, significant research and development efforts aimed at higher stock removal capacity as well as improved ability to eliminate pre-machining errors. The requirement of combining advantageous functional work piece characteristics after gear honing and the economic benefits of a single hard finishing process has led to the development of Coroning. Using similar process kinematics as in conventional gear honing, Coroning distinguishes itself by the application of highly aggressive electroplated diamond tools. Because of the increased stock removal capability of Coroning, it is a true single-finishing process for mass production. Coroning is applied after gear hobbing or shaping and heat treatment. It does not require prior shaving or grinding. This paper will explain the unique tool concept used for Coroning and discuss related process kinematics in comparison with conventional gear honing. Tool design aspects will be considered and suitable process strategies will also be presented. Application examples will be used to describe typical stock conditions, process parameters and the geometric quality that can be achieved with Coroning.
A Surface Wear Prediction Model for Parallel-Axis Gear Pairs
Authors: Bajpai P. , Kahraman A. , Anderson N. E.
Published: June 2008

In this study, a surface wear prediction model for spur and helical gears is proposed. The model employs a finite elements-based gear contact mechanics model in conjunction with the Archard’s wear formulation to predict wear of contacting tooth surfaces. An iterative numerical procedure is developed to account for the changes in the gear contact as the gears wear. A methodology is developed to import gear coordinate measurement machine data into the gear contact model in order to analyze gears with actual manufactured surfaces with profile and lead modifications. Results of an experimental study are presented for validation of the model. A set of simulations is also included to highlight the differences between gear pairs having modified and unmodified tooth surfaces, with and without manufacturing errors in terms of their wear characteristics.
Open Gears for the Mining Industry: Material and Manufacturing Process Selection
Authors: Botto Ivo , Hurtado Eduardo O. , Lovell Stephen S.
Published: June 2008

One of the characteristics of the mining industry is the need to deal with large and heavy-section components. The concept of heavy-section is relative and, in the case of this paper, the authors will cover both the material selection criteria and two new manufacturing solutions available for large open gearing. Open gears for the mining industry drive grinding mills up to 10,000 HP with a single pinion and daily throughputs of approximately 30,000 metric tons (∼ 66,600 pounds). They are further characterized by some unique numbers such as weights in excess of 100 metric-tons (∼ 222,000 pounds), diameters up to 13.6 meters (45 ft.), face widths up to 1,143 mm (45 inches), tooth sizes up to 40 module (5/8 diametric pitch), rim thickness up to 250 mm (10 inches), and hardness up to 350 Brinell, with machining tolerances to AGMA Q10 in accordance with AGMA 2001-B88 [1]. The most demanding challenges in the advancement of this technology and the manufacturing of these components are achieving AGMA GRADE 2 material requirements in heavy-section gear rims and overcoming the many obstacles associated with welding high-strength low-alloy (HSLA) materials of extraordinary size and mass. This paper demonstrates how these challenges have been overcome by providing a thorough description of the manufacturing process. Beginning with steel making, the topics are melting, special refinements, forging, rolling, specialized heat treatment, metallurgical enhancements for improved weldability and material testing. Topics relating to the fabricating and general manufacturing process are: cold forming of heavy-section high-strength, low-alloy rim plates, the application of both nontraditional and traditional welding processes, nondestructive testing, machining and tooth cutting.
A New Calibration Facility for the UK’s National Gear Metrology Laboratory
Authors: Frazer R. C. , Mancasola P. , Mikoleizig G.
Published: June 2008

The paper discusses the calibration and measurement uncertainty requirements of the UK gear industry. It makes particular reference to the new ISO documents: Draft ISO 18653 and draft TR 10064-5 that are being developed by ISO TC60/WG2 that describe the calibration of gear measuring instruments and measurement uncertainty assessment. Further, the paper the describes initial tests on the performance of a new Klingelnberg P65 Gear Measuring Centre selected by the UK’s National Gear Metrology Laboratory as the platform for improving gear calibration in the UK.
Predictions of Wear and Transmission Errors of Cylindrical Worm Gears
Authors: Wang X. , Morrish L.
Published: June 2008

Transmission error (TE) is an important transmission parameter for precision worm gears. Modern cutting methods in conjunction with modern software allow manufacturers to deliver worm gear products of high accuracy to the highly competitive market. However, the initial shape of a bronze wheel tooth changes dramatically due to bedding-in and wear when gears mesh under load, and hence transmission characteristics change. A computer program is being developed to predict wear during bedding-in and constant wear rate stages for involute worm gears. A progressive wear over given number of tooth engagements is estimated using both the available experimental wear data and theoretical considerations. Being subtracted from an “as-cut” geometry, a new shape of worm wheel tooth surface can be predicted. The calculations can be executed iteratively for as many wear steps as necessary. The model takes load sharing and contact stress distribution into account to estimate the lubrication oil film thickness and wear intensity. Contact patterns, TE, load cycles and meshing stiffness are also modeled. A comparison between theoretical wear predictions and experimental wear data is made. Predictions of wear and transmission errors are useful for optimization of existing worm gear design and for development of worm gears of new designs.
Computer Aided Tooth Contact Analysis in Cylindrical Worm Gears
Authors: Simon Vilmos V.
Published: June 2008

A method for computer aided loaded tooth contact analysis in different types of cylindrical worm gears is proposed. The method covers both cases — that of the theoretical line and point contact. The geometry and kinematics of a worm gear pair based on the generation of worm gear teeth by a hob is presented. The full loaded tooth contact analysis of such a gear pair is performed. A computer program based on the theoretical background presented, has been developed. By using this program the path of contact, the potential contact lines, the separations of mating surfaces along these contact lines, the load distribution and transmission errors for different types of modified and non-modified worm gear pairs are calculated and graphically presented. The influence of gear tooth modifications on tooth contact is investigated and discussed.
Analysis of Microelastohydrodynamic and Mixed Lubrication Effects in Gear Tooth Contacts
Authors: Holmes M. J. A. , Evans H. P. , Snidle R. W.
Published: June 2008

The paper presents results obtained using a transient analysis technique for point contact elastohydrodynamic lubrication (EHL) problems based on a formulation that couples the elastic and hydrodynamic equations. Results are presented for transverse ground surfaces in elliptical point contact that show severe film thinning at the transverse limits of the contact area. This thinning is caused by transverse leakage of the lubricant from the contact in the remaining deep valley features. A comparison is also made between the point contact results on the entrainment centre line and the equivalent line contact analysis.
Engineered Surfaces for Improved Gear Scuffing Resistance
Authors: Ribaudo Carl R. , Aylott Chris , Hofmann Dieter , Darragh Craig V. , Evans Ryan D. , Cooke Elizabeth P. , Doll Gary L.
Published: June 2008

Scuffing is a severe form of adhesive wear that can occur on gear flanks operating at combinations of high sliding speed and contact stress in marginal lubrication. Engineered Surfaces (ES) refers to the selection, application, and use of certain topographical modification (TM) techniques and thin film coatings applied using advanced physical vapor deposition (PVD) to improve the tribological performance of mechanical components. In this study, the effects of ES technology upon the scuffing resistance of helical gears were empirically determined. Six different treatments of ES technology were tested along with a baseline treatment of uncoated ground surfaces. In the testing, the gear speed was kept constant while the input torque on the gears was incrementally increased until scuffing was observed. Three ES treatments produced statistically significant increases in the scuffing torque relative to the baseline. Increases in mean scuffing torque using ES technology were as high as 89%.
Windage Losses in High Speed Gears: Preliminary Experimental and Theoretical Results
Authors: Diab Y. , Ville F. , Changenet C. , Velex P.
Published: June 2008

Power losses in high-speed gears come from the friction between the teeth (sliding and rolling), the lubrication process (dip or jet lubrication), the pumping of a gas-lubricant mixture during the meshing and the losses associated with windage effects. The objective of this paper is to present a number of preliminary experimental and theoretical findings on the prediction of windage losses. Experiments were conducted on a test bench whose principle consists in driving a gear to a given speed and then measuring its deceleration once it has been disconnected from the motor. The transmission between the motor and the rotor is ensured by a friction wheel which also plays the role of speed multiplier. A pneumatic jack either imposes a sufficient contact pressure between the driving wheel and the rotor (transmission of rotation), or is used for separating the parts when the maximum speed is reached. A disk and 4 different gears were tested in the absence of a lubricant at speeds ranging from 0 to 12 000 rpm. Two different theoretical approaches have been developed: i) a dimensional analysis based upon the dimensionless groups of terms which account for the flow characteristics (Reynolds number), the gear geometry (tooth number, pitch diameter, face width) and the speed, ii) a quasi-analytical model considering in detail the fluid flow on the gear faces and inside the teeth. It is found that both approaches give good results in comparison with the experimental evidence and two analytical formulae aimed at predicting windage losses in high-speed gears are proposed.
Pressure Measurement of Ambient Air in the Root Space of Helical Gears for the Purpose of Understanding Fluid Flow to Improve Lubrication Efficiency
Authors: Houjoh Haruo , Ohshima Shun-ichi , Matsumura Shigeki , Yumia Yasuhiro , Itoh Keiji
Published: June 2008

Lubricant supply in gearing gives excess power loss due to churning as well as lubrication system. Since the behavior of lubricant at the mesh region is still unclear, much greater amount of oil than required is used for cooling because most part is thrown away by centrifugal force. For lower loss due to lubrication, it is necessary to discover the location of supplying nozzle. Authors have measured the pressure variation during the mesh process, which will give us an idea how we can deliver the lubricant properly with minimal but efficient cooling. Pressure measurement was done for several pairs of helical gears, that had a pressure gage installed at the bottom of root space. A sucking action is found to distribute along the tooth width especially at the recess side of meshing. Although there is global axial flow due to helix angle, which is directed from the leading side towards the trailing side, there is the opposite flow at a part at the trailing side.
Improving the Characteristics of Gear Pumps: Part A — Discharge
Authors: El-Bahloul Ahmed M. M. , Ali Yasser Z. R.
Published: June 2008

The main objective of this paper is to study the effect of gear geometry on the discharge of gear pumps. We have used gears of circular-arc tooth profile as gear pumps and have compared between these types of gearing and spur, helical gear pumps according to discharge. The chosen module change from 2 to 16 mm, number of teeth change from 8 to 20 teeth, pressure angle change from 10 to 30 deg, face width change from 20 to 120 mm, correction factor change from −1 to 1, helix angle change from 5 to 30 deg, and radii of curvature equal 1.4, 1.5, 2, 2.5, 2.75, and 3m are considered. The authors deduced that the tooth rack profile with radius of curvature equal 2.5, 2.75, 3m for all addendum circular arc tooth and convex-concave tooth profile, and derived equations representing the tooth profile, and calculated the points of intersections between curves of tooth profile. We drive the formulas for the volume of oil between adjacent teeth. Computer program has been prepared to calculate the discharge from the derived formulae with all variables for different types of gear pumps. Curves showing the change of discharge with module, number of teeth, pressure angle, face width, correction factor, helix angle, and radius of curvature are presented. The results show that: 1) The discharge increases with increasing module, number of teeth, positive correction factor, face width and radius of curvature of the tooth. 2) The discharge increases with increasing pressure angle to a certain value and then decreases with increasing pressure angle. 3) The discharge decreases with increasing helix angle. 4) The convex-concave circular-arc gears gives discharge higher than that of alla ddendum circular arc, spur, and helical gear pumps respectively. 5) A curve fitting of the results are done and the following formulae derived for the discharge of involute and circular arc gear pumps respectively: Q=A1bm2z0.895e0.065xe0.0033αe−0.0079βQ=A2bm2z0.91ρ10.669e−0.0047β
Improving the Characteristics of Gear Pumps: Part B — Pressure
Authors: El-Bahloul Ahmed M. M. , Ali Yasser Z. R.
Published: June 2008

The main objective of this paper is to study the effect of gear geometry on the oil pressure of gear pumps. We have used gears of circular-arc tooth profile as gear pumps and have compared between these types of gearing and spur, helical gear pumps according to pressure. The chosen module change from 2 to 16 mm, number of teeth change from 8 to 20 teeth, pressure angle change from 10 to 30 deg, face width change from 20 to 120 mm, correction factor change from −1 to 1, helix angle change from 5 to 30 deg and radii of curvatures equal 1.4, 1.5, 2, 2.5, 2.75, and 3m are considered. The authors deduced that the tooth rack profile with radius or curvature equal 2.5, 2.75, 3m for all- addendum circular arc tooth and convex-concave tooth profile, and derived equations of pressure difference for spur, helical, and circular- are gear pumps. Computer program has been prepared to calculate the pressure from the derived formulae with all variables for different types of gear pumps. Curves showing the change of pressure with module, number of teeth, pressure angle, face width, correction factor, helix angle, and radius of curvature are presented. The results show that: 1) Pressure increases with increasing helix angle. 2) Pressure decreases with increasing face width, number of teeth, positive correction factor, module, pressure angle and radius of curvature of the tooth. 3) The all- addendum circular-arc gears generates pressure higher than helical, convex-concave and spur gear pumps. 4) A curve fitting is done for all variables with pressure and the following formulae derived for the pressure: P=A3b−0.943z−1.175m−2.1β0.175e−0.61xe−0.0048αP=A4b−1z−1.34m−2β0.119ρ1−0.393 These formulae represent simple tool for the designer to calculate the pressure of involute and circular arc gear pumps.