Showing papers on "Pressure angle published in 2011"

Critical Loading Points for Maximum Fillet and Contact Stresses in Normal and High Contact Ratio Spur Gears Based on Load Sharing Ratio

Abstract: Maximum contact and fillet stresses in normal and high contact ratio spur gears are evaluated based on load sharing ratio using finite element method through single- and multi-point loaded models as well as multi-pair contact model. The multi-pair contact model has been justified as an appropriate one for the present analysis as this model exclusively considers the influence of the loaded adjacent teeth and the Hertz contact deflections. A detailed parametric study on the load sharing ratio and the respective stresses has also been carried out to analyze the effect of addendum height, the pressure angle, gear ratio, teeth number, and tooth size. Finally, the importance of load sharing ratio and the critical loading points for maximum fillet and contact stresses in normal and high contact ratio spur gears is highlighted for the effective design.

Initial Experiments of High-Speed Drive System Windage Losses

Abstract: High speed gearing performance is very important to the overall drive system efficiency. Certain losses such as gear meshing and bearing drag can be minimized by design changes such as pressure angle of the gears and the geometry and type of bearings being used. One component that can have a large effect on the overall performance of high-speed drive systems is the parasitic drag known as gear windage. This loss mechanism is not well understood and minimizing this component is usually accomplished through much trial and error. The results presented in this paper will document some of the design parameter effects on the amount of windage losses. A new test facility at NASA Glenn has been assembled to systematically study the design variables. Results from recent tests will be presented. The tests are for a single gear, with and without lubricants, and some initial studies using shrouds.

Continuous method for manufacturing face gears

Abstract: A continuous method of manufacturing a face gear utilizing a tool, representing a plane which can be oriented to a face gear workpiece under an angle equal to the pressure angle of the mating pinion member of the gear set (e.g. the face gear set), and, which can be rotated around a virtual pinion axis to generate a tooth flank on the workpiece. The tool is a face cutter which performs a continuous indexing motion with equal hand of rotation of cutter and workpiece (e.g. face gear) thereby describing a hypocycloid path of motion and an indexing ratio of two cutter rotations during one workpiece gear rotation which will produce straight lines along the face width of the face gear.

Effect on Strength of Involute Spur Gear by Changing the Fillet Radius Using FEA

Abstract: Ashwini Joshi, Vijay Kumar Karma Abstract—Gearing is the special division of Mechanical Engineering concerned with the transmission of power and motion between the rotating shafts. Gears not only transmit motion and enormous power satisfactorily, but can do so with very uniform motion. It is the best and the economical means of achieving this transmission. Gear teeth fails due to the static and the dynamic loads acting over it, also the contact between the two meting gears causes the surface failures. The gear fails without any warning and the results due to this failure are catastrophic. Since the requirements are broad and are of varying difficulty, gearing is a complex and diversified field of engineering. It includes gear mathematics, geometrical design, strength and wear, material and metallurgy, fabrication and inspection. Therefore for all the reasons mentioned, this work is of more practical importance. To get the gear of more durability we can use improved material, hardening the gear surfaces with heat treatment and carburization, shot penning can be done to improve the surface finish, to change the pressure angle by using asymmetric teeth, introducing the stress relieving features of different shape, changing the addendum of the spur gear and altering the design of root fillet are the other methods.Present work deals with the effect on gear strength with variation of root fillet design using FEA. Circular root fillet design is considered for analysis. The loading is done at the highest point of single tooth contact (HPSTC).

High-Pressure Angle Gears: Comparison to Typical Gear Designs

Abstract: A preliminary study has been completed to determine the feasibility of using high-pressure angle gears in aeronautic and space applications. Tests were conducted in the NASA Glenn Research Center (GRC) Spur Gear Test Facility at speeds up to 10,000 rpm and 73 N*m (648 in.*lb) for 3.18, 2.12, and 1.59 module gears (8, 12, and 16 diametral pitch gears), all designed to operate in the same test facility. The 3.18 module (8-diametral pitch), 28 tooth, 20deg pressure angle gears are the GRC baseline test specimen. Also, 2.12 module (12-diametral pitch), 42 tooth, 25deg pressure angle gears were tested. Finally 1.59 module (16-diametral pitch), 56 tooth, 35deg pressure angle gears were tested. The high-pressure angle gears were the most efficient when operated in the high-speed aerospace mode (10,000 rpm, lubricated with a synthetic turbine engine oil), and produced the lowest wear rates when tested with a perfluoroether-based grease. The grease tests were conducted at 150 rpm and 71 N*m (630 in.*lb).

Design of asymmetric gear and accurate bending stress analysis using the es-pim with triangular mesh

Abstract: This paper proposes a novel design of an asymmetric gear that applies a larger pressure angle in the drive side and a standard pressure angle in the coast side via accurate stress analysis using the edge-based smoothed point interpolation method with triangular mesh (ES-PIM-(T3)). An asymmetric rack cutter is first developed. Then, the governing equations of the tooth profiles cut by the rack cutter are derived. Finally, five sets of asymmetric gears with the pressure angles of 20° /20°, 25°/20°, 30°/20°, 35°/20°, and 40°/20° are established to quantitatively check the stress distributions at the fillet of the drive side of these teeth. The best point for applying force in a static bending stress analysis and the best pressure angle in the drive side for a gear design are suggested.

Low torque loss gears: austempered ductile iron versus carburized steel

Abstract: Low-loss power transmission gears operate at lower temperature than conventional ones because their teeth geometry is optimized to reduce friction. The main objective of this work is to compare the operating stabilization temperature and efficiency of low-loss austempered ductile iron (ADI) and carburized steel gears. Three different low-loss tooth geometries were adopted (types 311, 411 and 611, all produced using standard 20° pressure angle tools) and corresponding steel and ADI gears were tested in a FZG machine.The results obtained showed that low-loss geometries had a significant influence on power loss, gears 611 generating lower power loss than gears 311. At low speeds (500 and 1000 rpm) and high torque ADI gears generated lower power loss than steel gears. However, at high speed and high torque (high input power and high stabilization temperature) steel gears had better efficiency.

Pressure sensor and pressure difference sensor

Abstract: A pressure sensor includes a hydraulic path filled with a pressure transfer liquid and a pressure transducer having a pressure sensitive deformation body. The hydraulic path includes a channel which extends from a pressure input opening at least to the deformation body, wherein the pressure input opening is spaced a separation distance from the deformation body, and wherein pressure on the deformation body deviates from pressure at the pressure input opening by the difference of the hydrostatic pressure of the pressure transfer liquid between the pressure input opening and the deformation body. The pressure sensor further includes an inclination sensor for determining at least one inclination value dependent on the inclination of the hydraulic path, and a processing circuit, which is suitable to determine the difference of the hydrostatic pressure of the pressure transfer liquid between the pressure input opening and the deformation body as a function of inclination value, a density value of the pressure transfer liquid and a separation distance.

Speed reduction mechanism, motor with speed reduction mechanism, and method for producing speed reduction mechanism

Abstract: A pressure angle of the worm is set to be greater than a pressure angle of the worm wheel so that a maximum number of meshing teeth becomes smaller than or equal to n (where n is a natural number) with respect to the speed reduction mechanism in which a number of meshing teeth is always n+1 or changed between n+1 and n by rotation under a condition in which the pressure angles of the worm and the worm wheel are the same with respect to each other.

Gear tooth profile for a wind turbine

Abstract: The invention relates to an electric power-generating device that converts fluid flow to electricity The electric power- generating device comprises a rotor having blades that rotate in response to fluid flow; a main power input shaft coupled to said rotor; and at least one gear stage, coupled to the main power input shaft The gears (210, 220, 230) comprise an asymmetric gear tooth profile with high and low pressure angle flanks (212, 213, 222, 223, 232, 233; 336, 337, 346, 347, 356, 357) whereas the high pressure angle flank has a pressure angle (s2) which is greater than the pressure angle (s1) of the low pressure angle flank

Wave gear device having three-dimensionally contacting involute positive shifted tooth profile

Abstract: In a wave gear device (1), an involute tooth profile with the low pressure angle α (< 20°) is employed as a basic tooth profile of external teeth (11) of a flexible external gear (3). In the principal section (20) of the external teeth (11), the tooth depth thereof satisfies 2κ 0 mn = 2(1 + c) mn (deflection coefficient κ 0 = 1 + c, 0 < c < 0.5), which is larger than the standard one. The shifting of the teeth which takes into account coning is performed along the tooth trace direction of the external teeth (11), so that straight portions of a rack tooth profile on the respective sections perpendicular to the axis in the tooth trace direction of the external teeth (11) are conformed as viewed along the tooth trace direction. The rack tooth profile of the involute tooth profile is a straight line, and hence it is possible to attain a tooth profile enabling continuous meshing that takes into account of the coning of the tooth over the entire tooth trace of both a gear (2) and the gear (3).

Die design and experiment for forming the teeth of shafts by rolling

Abstract: Combining the theory of wedge cross rolling(WCR) with forming gears by rolling,a method was proposed to form teeth simultaneously when rolling gear shafts.The method can not only realize the near net forming of gear shafts,but also improve the mechanical properties and service life of teeth.In the process of forming teeth by rolling,the feed was not continuous but intermittent,and workpieces were compelled to roll in free graduation under the rotation of dies.The calculation method and change law of die tooth pitch,the design of die tooth forms,the calculation method of the minimum feed at the first half circle and the law of feed change in each stage of rolling were presented on the basis of mathematical models and experiments.The rolling process was simulated by numerical software Deform-3D,with which the dies can be correctly designed.A toothed shaft with the module of the gear m=2,the number of teeth z=20 and the pressure angle a′=20° has been successfully formed with the H630 rolling tool.It is proved that forming teeth on gear shafts by wedge cross rolling is feasible.

Drill/tap working device

Abstract: PROBLEM TO BE SOLVED: To provide a drill/tap working device capable of preventing breaking of a tool such as a drill or a tap and surely drilling and internally threading. SOLUTION: This drill/tap working device includes a first beam 7 turnable in a horizontal plane and a second beam 9 connected to the first beam 7 to be turnable in the horizontal plane, which are normally arranged in a horizontally turnable state forming an angle of about 90°. At a distal end of the second beam 9, a tool unit 3 is movably supported in an axis direction of the tool 25. In the drilling and internally threading, the first beam 7 and the second beam 9 perform fine turning operations according to force received by the tool 25 of the tool unit 3 during machining to self-align the tool 25. Rotary reaction force is received by a pressure angle 0° and positional deviation of the tool unit 3 by the rotary reaction force can be prevented. COPYRIGHT: (C)2011,JPO&INPIT

Rack-and-pinion type slewing equipment of coal-excavating development machine

Abstract: The invention relates to a rack-and-pinion rotator for a coal cutting development machine, mainly comprising a revolving body, a revolving gear, a left revolving rack, a right revolving rack, an upper support ring, a lower support ring, a built-in oil cylinder, a gear bearing and an articulated frame, wherein, large-scale high-power workpieces are adopted in the aspect of a structure; the plane support rings adopt ultrahigh molecular weight polyethylene materials; the revolving gear and the revolving rack adopt large-scale design; the modulus is 32; the pressure angle is 28 DEG; the gyration half angle is 26 DEG; the gyration integrated angle is 52 DEG; a high-power hydraulic built-in oil cylinder is adopted for power transmission The rack-and-pinion rotator for the coal cutting development machine has the advantages of reasonable design, compact structure, large bearing capacity, and strong pressure-proof, shock-proof, shock-absorbing and impact resistant capacities; the impact resistance can rise two to three times compared with the prior art; the workpieces are difficult to damage; moreover, the rack-and-pinion rotator has long service life, is safe, stable and reliable, and is an extremely ideal rack-and-pinion rotator for the coal cutting development machine

Wave gear device having three-dimensional contacting involute positive deflection tooth profile

Abstract: In a wave gear device, an involute tooth profile with the low pressure angle α (<20°) is employed as a basic tooth profile of external teeth of a flexible external gear. In the principal section of the external teeth, the tooth depth thereof satisfies 2κ 0 mn=2(1+c) mn (deflection coefficient κ 0 =1+c, 0

Design and analysis of offset slider-crank with translating roller-follower

Abstract: This paper presents a systematic methodology for the design and analysis of an offset slidercrank mechanism with a translating roller-follower. In the proposed approach, a generic kinematic model of the offset slider-crank and roller-follower is constructed using a homogenous coordinate transformation method and the slider cam profile are then derived using conjugate surface theory. The pressure angle and principal curvatures of the designed slider cam are analyzed based on the analytical expression of the cam profile. Finally, the NC data required to machine the slider cam are produced by equating the ability matrix of the 3- axis CNC machine tool with the desired tool location matrix.

Analytical Model of the Efficiency of Spur Gears: Study of the Influence of the Design Parameters

Abstract: An analytic model to compute the efficiency of spur gears has been developed. It is based on the application of a non-uniform model of load distribution obtained from the minimum elastic potential criterion and a simplified non-uniform model of the friction coefficient along the path of contact. Both conventional and high transverse contact ratio spur gears have been considered. Analytical expressions for the power losses due to friction, for the transmitted power and for the efficiency are presented. From this model, a complete study of the influence of some design parameters (as the number of teeth, the gear ratio, the pressure angle, the addendum modification coefficient, etc.) on the efficiency is presented.Copyright © 2011 by ASME

Experimental and Probabilistic Analysis of Asymmetric Gear Tooth

Abstract: Photoelasticity has been used previously in experimental studies on gears. With the advantages of today’s high capability of computing and software, photoelastic analysis can be combined with probabilistic analysis. The objective of this study was to perform an experimental study and probabilistic analysis of an asymmetric gear tooth. The uncertainty considered involves the material properties and geometry. In this study, different asymmetric gear tooth profiles were manufactured from PSM-5 photoelastic material. This study shows that the combination of photoelastic experiments and probabilistic analyses may be an effective tool to study the advantages of asymmetric gear over the symmetric gears.

On the Design Conditions of Planar Parallel Manipulators in Near-Singular Configurations

Abstract: Singularity is a major problem for parallel manipulators as it causes severe problems: uncontrollable or unstable motions, loss of stiffness, infinite forces/torques in actuated joints, and possibility of a breakdown. Many studies have been devoted to these problems. In particular, various criteria for measuring the closeness to singularities have been proposed. They are based on the limitation of the values of the input force/torque, pressure angle, natural frequency, etc. The present paper expands the previous work by incorporating a new criterion into mentioned problem, which allows the limitation of the reaction in passive joints. For this purpose, a new approach is developed, which shows that for given external force and moment applied on the platform, the reactions in passive joints depend not only on the pressure angle but also the position of the instantaneous centre of rotation of the platform. The developed approach is not only an effective way to reduce computation time but also to give a qualitative and geometrical interpretation of the problem. The suggested procedure for the determination of the reachable manipulator workspace taking into account the admissible reactions in passive joints is illustrated via a planar 3-RRR parallel manipulator.

Gear pump with asymmetric combined curved surface tooth form

Abstract: The invention discloses a gear pump with an asymmetric combined curved surface tooth form. The gear pump comprises a hollow pump body; a driving gear and a driven gear which are meshed mutually are arranged in the pump body; a tooth surface on one side where the driving gear and the driven gear are contacted and stressed is a working surface, and the tooth surface on the other side is a non-working surface; a pressure angle of the working surface is 20.5 to 22.8 degrees; the gear pump is characterized in that: a pressure angle of the non-working surface is 14 to 19 degrees; and the non-working surface is formed through smooth transition of an evolvent curved surface and a circular arc camber. The gear pump has large single pump output, a large overlap coefficient, small noise, low gear collapsing probability, and transmits stably, and the chamber sweeping phenomenon is avoided.

Static load sharing behavior in NGW planetary gear train with unequal modulus and pressure angles

Abstract: An analytical model for NGW planetary gear train with unequal modulus and pressure angles was presented,and in consideration of the eccentric error and tooth-frequency error of parts,a static equation of the NGW planetary system was developed based on the theory of equivalent mesh error and the principle of static equilibrium.After equation was solved,the load sharing characteristics were compared with the normal gear transmission.Also the load sharing behavior of each planet was analyzed and compared by the sun and the ring pressure angle,the difference of the gear error,the variety of mesh stiffness and support stiffness.The analysis results show that planetary gear train with unequal modulus and pressure angles has better load sharing behavior,which does not change significantly with the different pressure angles,the floating sun gear has improved the load sharing behavior substantially,and the planets fixed with the same production batch and the lower support stiffness of the sun and the planets benefit the load sharing behavior.

Analytical Method on Contact Stress of Helical Gear with Asymmetric Involutes

Abstract: Helical gear with asymmetric involutes is a new kind gear which driving side surface is large pressure angle profile. The numbers of meshing tooth are discussed during helical gear pair meshing process, thus the length of total contact lines is determined easily. It is difficult to calculate contact stress by existing formula because this kind gear is non-standard. A calculating formula is derived which can calculate contact stress of helical gear with asymmetric involutes in this paper. A computer’s software is written in order to calculate instantaneous contact stress of contact line. Contact stress is compared between symmetric helical gear and asymmetric helical gear.

Methods of Describing Plastic Gear Geometry After a Temperature Change With Application to the Prediction of Gear Load Distribution

Abstract: In Polymer gears, the rise in temperature not only influences gear rigidity but also tooth geometry. This paper presents methods to represent the influence of temperature by change in micro-geometry and macro-geometry parameters of the gear tooth. These macro and micro-geometry parameters of gear are entered into advanced gear analysis programs such as those for performing load distribution analysis and transmission error prediction. This theoretical model assumes linear thermal expansion of the material of the gear. This model is verified using a Finite Element Analysis (FEA) of the gear tooth. Two approaches were successfully used to model the thermal expansion of the material, one being to change the module of the gear and the other being to apply a pressure angle slope change to the tooth form. The profile change was verified by elevating the temperature of plastic gears of several materials and then measuring them on a Gear–Co-ordinate Measuring Machine. The two approaches were used in compatible load analysis programs that produced essentially identical transmission error predictions.© 2011 ASME

High-strength wet loader drive axle gear pair

Abstract: The utility model relates to a wet loader drive axle gear pair and discloses a high-strength wet loader drive axle gear pair. The high-strength wet loader drive axle gear pair comprises a gear shaft (1) and an umbrella-shaped gear (2). The gear shaft (1) comprises helical teeth (12), a front bearing guard (11) and a rear supporting shaft (13). In the utility model, the overlap coefficient and the bearing capability of the gear pair are improved by changing a pressure angle and a helical angle of the gear pair, so that equipment is more stable and reliable to operate, and the working noise and the fault rate are reduced.

Universal speed reducer with slidable-tooth engagement pair

Abstract: A universal speed reducer with a slidable-tooth engagement pair is provided. The reducer comprises: a housing (5), a power input shaft (1) provided with an eccentric sleeve (3), and a power output shaft (2) provided with a slidable-tooth disk (6). The slidable-tooth disk is provided with slidable teeth (9) in such a manner that the slidable teeth can slide in the radial direction of the slidable-tooth disk with single degree of freedom. Tooth grooves (8), which are concentric with the power input shaft, are fixed on the housing and meshed with the slidable teeth in a small tooth difference manner. The groove width of the tooth grooves is greater than the tooth thickness of the slidable teeth in the circumferential direction. The eccentric sleeve is just opposite to the slidable teeth in axial direction and is eccentrically arranged within the slidable-tooth disk. The pressure angle of a gear according to the invention can be adjusted by changing the eccentricity of the eccentric sleeve, therefore, the pressure angle of a conjugate gear can be decreased from about 60° to 25°. The power loss caused by excessive pressure angle is avoided, the transmission efficiency is greatly increased, and the motion is smoothly and unhinderedly output. Reduction ratio can be fit by the number of the tooth grooves; the range of transmission ratio is enlarged and can reach 5-50. The invention has simple design, small structure and size, few parts and low processing cost.

Different teeth pump

Abstract: The utility model relates to a mechanical displacement pump, in particular to a different teeth pump. The different teeth pump is characterized in that two different teeth gears form a different teeth gear pair, one to four high teeth are used as working teeth, short teeth are used as driving teeth, the working teeth and the driving teeth are teeth with the same modulus, pressure angle, tooth addendum coefficient, modification coefficient, tooth thickness coefficient and tooth profile curve or different moduluses, pressure angles, addendum coefficients, modification coefficients, thickness coefficients and tooth profile curves, at least more than one parameter is ensured to be different, and the working teeth are higher than the driving teeth. The different teeth pump overcomes the defects of low efficiency, high shock, serious abrasion, small compression ratio and great processing difficulty existing in the existing mechanical displacement pump; as the volume of a working chamber enclosed by the working teeth is increased, the working performance and the processing performance of a gear pump are improved, so that the different teeth pump is suitable for liquid medium as well as gaseous medium and can be applied to a motor and an internal combustion engine.

Novel ring die type pellet mill

Abstract: The utility model provides a novel die type pellet mill which comprises the following components: a speed reducer, a coupling, a belt, a pulley transmission mechanism gearbox, a base, a motor equipped on the base, a rotary vibration sieve, a vibration motor which is equipped on the rotary vibration sieve, and a material inlet hopper which is provided on a frame. The speed reducer is connected with the motor. An output shaft of the speed reducer is connected with one end of the coupling. The other end of the coupling is connected with an input shaft of the transmission mechanism gearbox. The body of the transmission mechanism gearbox is provided with a driving shaft and a driven shaft, which are respectively connected with a driving gear and a driven gear on the body of the transmission mechanism gearbox. The driving shaft and the driven shaft are respectively provided with a ring die. A pressure angle is formed between the two ring dies. The structure of the novel ring die type pellet mill has the following advantages: capability for preventing temperature raise in operation effectively, no requirement for adding large-scale cooling device when pellet preparation is performed at a low-temperature environment (less than 50 DEG C), greatly saved production cost; capability for ensuring that the raw material is squeezed to granular; and restrained pressure increase in the frame.

Optimization Design Method of Noise Control on Fine-Pitch Gear

Abstract: Proceed from reducing the noise of automotive gears, a new method of the fine-pitch tooth profile optimization is proposed. Under the premise of the constant gear parameter values of the transmission ratio, modulus, and pressure angle, the method considers the minimum noise objective value as the design object, and the constraint conditions are established such as the noninterference in meshing, the non-undercutting, and the non-pointed in the tip and so on. Then the coefficients of addendum and modification are optimized with the purpose of increasing the contact ratio value and full-depth tooth. And it is necessary for this paper to conduct a strength analysis on the design result. The analysis result shows that the new method can not only reduce the noise, also ensure the high quality of the automotive gear strength.