Tooth Face Research Articles

The Mathematical Model and the Condition of Undercutting for the Cosine Face Gear Drive Generated by a Cosine Rack

The aim of this paper is to propose a non-involute face gear drive named cosine face gear drive. The cosine face gear drive comprises a cosine pinion and a cosine face gear. The cosine pinion is generated by a cosine rack. The cosine face gear is generated by the cosine pinion. The tooth faces of cosine pinion and cosine face gear are a pair of line-conjugate tooth surfaces. The mathematical models of the tooth faces of cosine pinion and cosine face gear have been created according to the coordinate transformation theory and the theory of gearing. The condition of undercutting for the tooth face of cosine face gear is also created according to the theory of conjugate tooth surfaces. A numerical example of cosine face gear drive has been proposed to verify the mathematical models. The undercutting and pointing problems for cosine face gear can be eliminated by limiting the inner and outer radii of cosine face gear. Compared with the involute face gear drive, the cosine face gear drive has a smaller number of teeth for pinion. Therefore, under the conditions of same gear module and gear ratio, the size of cosine face gear drive is smaller than that of involute face gear drive.

Optimum design of straight bevel gears pair using evolutionary algorithms

Straight bevel gear is a type of gear which is widely used in mechanical systems to transmit power between perpendicular rotating axes. Designing straight bevel gears with the least possible volume is of great importance in industry since it results in a decrease in energy consumption and the material requirement in manufacturing. In this paper, employing two powerful optimization algorithms, simulated annealing algorithm (SA) and genetic algorithm (GA), techniques for advanced optimization, coupled with American Gear Manufacturers Association (AGMA) instructions the volume of straight bevel gears pair is minimized and the corresponding design variables are obtained. These variables include majors, including teeth number, module and face width. Using a traditional technique, recommended values of the design variables by AGMA, a design example was performed and the values were obtained. Then, the suggested techniques were utilized to get the values. The comparison between the results of all techniques shows that proposed optimization algorithms are considerably capable of minimizing the volume. It indicates that improvement in the attained volume varies between 1.56 and 17.40% for SA and 9.28 and 23.15% for GA.

DEVELOPMENT OF A MICROGEAR ENDURANCE TEST SYSTEM AND A BASIC STUDY OF LUBRICATING CONDITIONS FOR MICRO SPUR GEAR

It has become possible to manufacture highly precise, high-strength metal microgears in recent years. On the other hand, a systematic evaluation of the load-carrying characteristics of microgears is not reported. Therefore, we developed an endurance test system for the microgear. Further, we considered the lubricating conditions for the microgear. We obtained the following results: (1) Even if the operating time is very short under very low operating conditions, it is confirmed that the damage to of meshing teeth will progress rapidly. (2) Depending on the operating conditions, it is expected that maintain sufficient lubrication condition which dropped a slight amount of the lubricating oil. (3) At a rotational speed that scattered the lubricating oil, it was observed the clumps by melt in tooth tip. (4) It is possible that the endurance test system that we developed can achieve appropriate meshing because a certain wear was observed over the tooth face width.

Estimation of Novikov Gearing Loading Capacity Based om Integral Strain Gauges Application

The paper considers Novikov gearing with two contact lines. The loading capacity of such gearing depends on the irregularity of load distribution between the contact lines. The Integral Strain Gauges made of metal foil characterized by special properties are suggested to be used for this irregularity estimation. During the ISG cyclic deforming the "dark spots" reaction appears on its surface. The method of ISG calibration during a specimen cyclic contact deforming is proposed and realized. It is shown that ISG reaction border depends on number of loading cycles and the compression strain value. The picture of the compression strain distribution along the tooth face surface is obtained as a result of Novikov gearing running. The stress-strain condition of the teeth is calculated based on the Finish Element Method. The stress loading of the contact lines of gearing is determined based on matching the photos of ISG reaction and the picture of compression strain distribution.

A Clinical Study to Correlate the Facial Form and Maxillary Central Incisor Tooth Form in Males and Females of Davangere Population

AbstractAn altered facial appearance is more difficult to face, than problems related to ill-fitting denture or eating. The selection of maxillary anterior teeth for complete denture has long posed problem in clinical practice and a controversy about the best method to employ still exists. An attempt is made in the present study to clinically correlate the face form with maxillary central incisor tooth form in males and females of Davangere population. In 1914, Leon William's projected the “the form method” where he classified facial forms as square, tapering, and ovoid. Maxillary central incisors were selected according to the facial forms.Of total 100 subjects four different tooth forms and face forms were evaluated. They are: square, ovoid, square-tapered, tapered. No significant correlation existed between face form in male and females. Females exhibited greater correlation between face forms and inverted tooth form but that correlation is not sufficient to serve as a guide for selection of anterior teeth.

Correlation Between Tooth form, Face Form and Arch Form Using Computer Program

Number of methods have been studied and suggested for selection of artificial tooth for determining the artificial tooth form to find out reliable esthetic factor. In this article a method is adopted to find out the esthetic factor by superimposition of the outline form of the tooth form(central incisor ), arch fom and face outline. 50 male dental students were selected and impression of the maxillary arch is made using irreversible hydrocolloid material and cast formed. A standardized photographic procedure is used to get the face photo of each student. And then Photoshop computer program is used to get the outline form of the incisor tooth, face, and the upper arch form. and then super imposition of the all these outline is made and correlate these factor to find out esthetic factor. Result in this study shows there is insignificant correlation between face, tooth, and

Analysis of bulk temperature field and flash temperature for locomotive traction gear

Sliding velocity variation for gear meshing surface was researched based on theories of gear tribology, heat transfer and Hertz contact, and a model of contact stress considering friction force was derived. The model design process culminated in a comparison of theoretical values and simulated values. Heat flux of friction for different meshing positions and the convective heat transfer coefficient at gear tooth surface and tooth face were initially calculated accurately. The finite element method was then adopted to establish the gear bulk temperature field model and, after the steady state temperature field of the locomotive traction gear was obtained, the distribution law of the steady-state temperature for the gear teeth was analyzed. Transient thermal analysis on the gear was implemented utilizing the steady-state thermal analysis to obtain the transient temperature field of the locomotive traction gear. Applying the Blok flash temperature criterion, theoretical value of the transient temperature rise for the gear tooth surface was calculated. Comparison of the simulation values and the theoretical values for the transient temperature rise indicated that the theoretical values were higher than the simulation values as the Blok flash temperature criterion considers the heat conduction only in the direction vertical to the tooth surface and disregards heat conduction in other directions. The simulation results were then concluded to be superior in practicality and accuracy.

Correlation between inverted maxillary central incisor form and face form in a sample of Sudanese population

Introduction: The selection of artificial teeth is an important concern in complete denture construction. Many theories were developed to objectively select artificial teeth, to simplify the process of choice and to make it more suitable. Objectives: This study was conducted to evaluate the correlation between inverted maxillary central incisors form and face form in a sample of Sudanese population. Materials and Methods: One hundred and sixty-four dental students (138 females and 26 males), with a mean age (20.8 ± 1.81), were randomly selected. Three horizontal distances of the right maxillary central incisor were measured, (cervical width, contact point width, and incisal width). For facial measurements, three horizontal distances on the face were measured, (bitemporal width, bizygomatic width, and bigonial width). Results: Chi-square test was used to estimate the association between face form and central incisor form. No association between tooth form and face form was detected in the study sample (P = 0.092). Conclusion: The findings of our study indicate that this method is not applicable for selection of maxillary anterior teeth in the study sample.

Optimum weight design of functionally graded material gears

Traditional gear weight optimization methods consider gear tooth number, module, face width or other dimension parameters of gear as design variables. However, due to the complicated form and geometric features peculiar to the gear, there will be large amounts of design parameters in gear design, and the influences of gear parameters changing on gear trains, transmission system and the whole equipment have to be taken into account, which increases the complexity of optimization problem. This paper puts forward to apply functionally graded materials (FGMs) to gears and then conduct the optimization. According to the force situation of gears, the material distribution form of FGM gears is determined. Then based on the performance parameters analysis of FGMs and the practical working demands for gears, a multi-objective optimization model is formed. Finally by using the goal driven optimization (GDO) method, the optimal material distribution is achieved, which makes gear weight and the maximum deformation be minimum and the maximum bending stress do not exceed the allowable stress. As an example, the applying of FGM to automotive transmission gear is conducted to illustrate the optimization design process and the result shows that under the condition of keeping the normal working performance of gear, the method achieves in greatly reducing the gear weight. This research proposes a FGM gears design method that is able to largely reduce the weight of gears by optimizing the microscopic material parameters instead of changing the macroscopic dimension parameters of gears, which reduces the complexity of gear weight optimization problem.

On the influence of helix angle and face width on gear windage losses

This paper investigates the windage power losses generated by helical gears rotating in pure air based on experimental results and a computational fluid dynamic code. It is found that the simulated flow patterns are totally different from those calculated for spur gears and that both tooth face width and helix angle are influential. The windage losses derived from Dawson’s and Townsend’s formulae are critically assessed using computational fluid dynamic results thus highlighting the limits of a unique formulation for accurate windage loss prediction. Finally, an analytical approach is suggested which gives good results providing that the flow rates at the boundaries of the inter-tooth domains can be estimated.

The effects of non-torque loads on a three-point suspension gearbox for wind turbines

The effects of non-torque loads on the load sharing and distribution of planet gears for wind turbine gearboxes were investigated through a scaled-down model experiment. The experiment model was a 35-kW class gearbox of size one-fourth that of a 2-MW class three-point suspension gearbox. The three components—axial force, radial force, and moment—were applied as non-torque loads. The strain near the tooth root of the ring gear at the low-speed planetary gearset was measured for the purpose of this study. The results obtained by applying only torque and by applying each non-torque load along with the torque were compared, and the mesh load factor and face load factor were used as indicators of the load sharing and distribution of planet gears, respectively. As a result, the load sharing became non-uniform when radial force and moments were added, resulting in increased mesh load factor about 3%. However, the effect of axial force was insignificant because the mesh load factor was unchanged. The load distribution on the tooth face width did not show a clear difference for the non-torque loads because the face load factors did not show a clear difference among loading conditions. Copyright © 2015 John Wiley & Sons, Ltd.

The Use Of Multifrequency Induction Heating For Temperature Distribution Control

AbstractThe paper presents possibilities of controlling temperature field distribution in inductively heated charge. The change of its distribution was obtained using the sequential one-, two-, and three-frequency heating. The study was conducted as a multi-variant computer simulation of hard coupled electromagnetic and temperature fields. For the analysis, a professional calculation software package utilizing the finite element method, Flux 3D, was used. The problem of obtaining an appropriate temperature distribution in the heated charge of a complex shape is very important in many practical applications. A typical example is hardening of gear wheels. For such an application, it is necessary to obtain (on the surface and at a desired depth) an uniform temperature distribution on the tooth face, top land and bottom land of the gear. The obtained temperature should have proper distribution and value. Such a distribution is very difficult to achieve.

Relationship and inter observer agreement of tooth and face forms in a Saudi subpopulation.

To determine the relationship of tooth form with the face form by different observers and further investigate the inter observer agreement on tooth forms, face forms, their relationship among male Saudis. A comparative cross-sectional study. Department of Prosthodontics, College of Dentistry, King Saud University, Riyadh, KSA, from February till August 2013. Ninety four male participants aged 18 - 35 years were randomly recruited for the study. Full-face and anterior teeth (intraoral) digital photographs in the frontal plane were recorded. The outline tracings of the face and the tooth were obtained using Autocad (version 2010) software. The outline of the tooth was enlarged proportionately, without altering the length to width ratio to fit the face outline. The outlines were then evaluated visually by 6 prosthodontists and results were tabulated. The most common type of face form (49.65%) and tooth form (56.38%) was square tapering. Using the visual method, a good relationship (31.41%), moderate relationship (35.31%), weak relationship (19.68%) and no relationship (13.65%) between the tooth form and face form was found by the observers. Overall kappa for inter observer agreement on face form, tooth form and their relationship was 0.24, 0.17 and 0.26 respectively. The kappa values showed a fair agreement between the observers. The study results indicated that there was no highly defined relationship between the tooth form and face form in the studied Saudi subpopulation. A fair agreement was found between the observers for classifying the tooth forms, face froms and their relationship.

Innovative Approach to Optimize Re-Sharpening Material Stock Removal to Improve Tool Life

Hobbing is the most widely employed cutting method for producing cylindrical gears, splines, and so on. However, because the wearing of the hob cutters always reduces their accuracy, the tooth faces on the hob gashes must be reground to ensure the accuracy of the machined gear and prolong the cutter's lifetime. In practice, the deviations of the ground tooth face of hob gashes are caused by machine error. This paper thus proposes a Optimize re-sharpening material stock removal to Improve tool life. Tool re-sharpening is an exacting craft. Keeping edges properly sharpened increases the tool's life and productivity. This paper reviews various literatures related to Hob Tool Life, Evaluation of Gear Hobbing, Gear Cutting Technology etc. Better with respect to tooth spacing and run out. Equal so far lead accuracy is required. Hobbing produces a series of radial flats based on feed rate of hob across the work.

FTS-based Face Milling of Micro Structures

This article presents a technical concept and machining possibilities for milling of micro structures with a fast tool servo (FTS). The tool is capable of tool tip displacements with a variable frequency up to 4000Hz and an amplitude up to 30μm. The control system of the actuator is linked to the angular spindle position, allowing to freely manipulate the excitation signal. Combining this tool system with a single tooth face milling head, micro structures on flat surfaces can be generated on conventional milling centers. Selected micro structures are machined and evaluated in terms of precision and surface quality. Video abstract [Display omitted]

Three-dimensional analysis of the correlation between anterior tooth form and face shape.

Traditional esthetic guidelines and denture-tooth selection protocols suggest a correlation between a patient's face and anterior tooth shapes. This study examined the correlation between face shape, maxilla shape, and maxillary anterior tooth form with fully automated algorithms. Three-dimensional digital datasets of the faces and maxillae were obtained from 117 people. Correlation was analyzed using canonical correlation analysis, ridge regression, and the Hausdorff-distance. A weak but not statistically significant correlation between face and tooth shape could be identified. However, a good prediction of tooth shape from the facial data was not possible. The described approach revealed a weak correlation between face shape and tooth shape, but the outcome was not accurate enough for clinical use.

Study on the Processing and Simulation of End-Gear Based on CNC Theory

Based on NC machining principle of hypoid gears and NC machining with high efficiency quality, This paper discusses the feasibility of the hypoid gear processing, establishes the mathematical model of face gear wheel hypoid milling machining adjustment, that will be take the basic data into vertical machining center machine tool. Through analyze the principle of the oscillating tooth face gear transmission, and compared the structure differences between face gear and bevel gear, and the realization processing method of face gear is discussed by improving the bevel gear shaper.

Fuzzy Reliability-Optimization Design for Differential Mechanism Based on Genetic Algorithm

To the widely used simple symmetric bevel gear differential, a fuzzy reliability-optimization mathematical model of a pair of bevel gear transmission is established, which used the bevel gear transmission as the research object, used the smallest volume of the gear transmission as the objective function, and used the end face module, the number of teeth and the coefficient of tooth face width as the design variables. Considering the randomness and fuzziness of the design parameters, an genetic algorithm control scheme was proposed for the optimal design, the numerical simulation results show that the volume of the gear transmission can be decreased by 3.36%, and the optimization design algorithm is more corresponded to engineering practice.

Gear Diagnostics – Fault Type Characteristics


 
 
 To date, the majority of existing Condition Indicators for gears are based on various statistical moments of a recorded time history. A supplementary analysis proposed in this study, shall suggest an approach that may, in the future, enable the identification of faulty gearwheel and possibly fault type in the system. In this work, a combined analytical and empiric approach is applied. This approach is based on the assumption that reliable dynamic models can be utilized to predict the effects of faults on vibrational patterns. Dynamic model generated signatures are used to verify experimental findings. Moreover, discrepancies between simulated and actual results, combined with understanding of the assumptions and omissions of the model, are helpful in understanding and explaining the experimental results.A spur gear transmission setup was used for experiments, along with an electric AC motor and a friction belt loading device. The experimental runs were conducted at varying speed settings. Two types of faults, a tooth face fault and a tooth root fault, were seeded in the experimental transmission and into the model. The effect on extracted signal features is examined.
 The purpose of this study is to evaluate fault detection capabilities of proposed diagnostic tools at the presence of two seeded faults of varying severity, verified by a dynamic model. Observed differences between examined fault types and their manifestation will be discussed. A basis for future work on prognostics capabilities is laid by a varying degree of tooth root fault.
 
 

Accuracy Analysis of Gear Root Strain Test under Different Rotational Speed

Involute helical gears, with advantages of large carrying capacity, smooth transmission and long life, etc., are widely used in automotive, mining, helicopters and other high-speed and heavy-load transmission system. Poor working conditions lead to fatigue crack and other faults of gear key parts such as tooth root and tooth face. To identify the root causes of gear faults, strain monitoring methods are often used to monitor the stress changes of gear key parts so as to work out individualized improvement plants. Good test results can be obtained using real-time wireless data collection technology when the gear is in low-speed and light loading condition, and we can get important data such as speed, torque and dynamic strain on tooth root, etc. However, involute helical gears tend to work in high-speed and heavy harsh conditions, especially when the gear speed reaches a large value (eg. 10000r/min above), gear strain measurement device will suffer big centrifugal force and the impact of shear force which may results partial bonded adhesive failure (cracks, erosion, etc.) and even whole peeling of strain gages, thus inaccurate and even error results will be obtained. Transient finite element analysis method is used in this paper to study the relationship between rotation velocity and test accuracy of strain gauge as well as the process of the bonded adhesive failure, which may provide effective guidance for the fault diagnoses of gear meshing.