Showing papers on "Pressure angle published in 2012"

Modeling contact angle hysteresis of a liquid droplet sitting on a cosine wave-like pattern surface.

Abstract: A liquid droplet sitting on a hydrophobic surface with a cosine wave-like square-array pattern in the Wenzel state is simulated by using the Surface Evolver to determine the contact angle. For a fixed drop volume, multiple metastable states are obtained at two different surface roughnesses. Unusual and non-circular shape of the three-phase contact line of a liquid droplet sitting on the model surface is observed due to corrugation and distortion of the contact line by structure of the roughness. The contact angle varies along the contact line for each metastable state. The maximum and minimum contact angles among the multiple metastable states at a fixed viewing angle correspond to the advancing and the receding contact angles, respectively. It is interesting to observe that the advancing/receding contact angles (and contact angle hysteresis) are a function of viewing angle. In addition, the receding (or advancing) contact angles at different viewing angles are determined at different metastable states. The contact angle of minimum energy among the multiple metastable states is defined as the most stable (equilibrium) contact angle. The Wenzel model is not able to describe the contact angle along the three-phase contact line. The contact angle hysteresis at different drop volumes is determined. The number of the metastable states increases with increasing drop volume. Drop volume effect on the contact angles is also discussed.

Oblique Drop Impact on Deep and Shallow Liquid

Abstract: Numerical simulations using CLSVOF (coupled level set and volume of fluid) method are performed to investigate the coalescence and splashing regimes when a spherical water drop hits on the water surface with an impingement angle. Impingement angle is the angle between the velocity vector of primary drop and the normal vector to water surface. The effect of impingement angle, impact velocity and the height of target liquid are carried out. The impingement angle is varied from 0 o to 90 o showing the gradual change in phenomena. The formation of ship pro like shape, liquid sheet, secondary drops and crater are seen. Crater height, crater displacement, crown height and crown angle are calculated and the change in the parameters with change in impingement angle is noted.

Rotor bearing for wind turbine, has double row spherical roller bearings with multiple barrel rollers, where pressure angle of bearing row is provided as zero degree angle

Abstract: The rotor bearing (18) has double row spherical roller bearings with multiple barrel rollers A pressure angle of a bearing row is provided as 0 degree angle A pressure angle of another bearing row is provided as 25 degree angle The barrel rollers of the former bearing row have a different shape than the barrel rollers of the latter bearing row

A study on cutting errors in the tooth profiles of the spur gears manufactured in CNC milling machine

Abstract: In this study, the cutting errors in the tooth profile of the spur gears which are manufactured by end mill according to radial cutting method in three-axis CNC milling machine are investigated. According to this method, a mathematical approach in order to investigate the cutting errors of the tooth profile is presented. Then, mathematical expressions determining the error quantity in the tooth profile curve are derived by using this approach, and a programme is developed in the MATLAB. Parameters such as module (m), tooth number (N), pressure angle (∅) and cutting angle (α m ) in the programme are changed, and the cutting errors of the involute tooth profile according to the obtained results are interpreted graphically. As a result, it is seen that the cutting errors in the involute curve increase according to increments of m, N, ∅ and α m .

Effect of triple-phase contact line on contact angle hysteresis

Abstract: Recent studies have shown that the triple-phase contact line has critical effect on the contact angle hysteresis of surfaces. In this study, patterned surfaces with various surface structures of different area fractions were prepared by electron etching on a silicon wafer. The advancing angle, receding angle and hysteresis angle of these surfaces were measured. Our experimental results showed that while the geometry of microstructure and contact line have a minor effect on the advancing angle, they have a significant effect on the receding angle and thus the hysteresis angle. We have shown that the effect of microstructure and the contact line can be described by a quantitative parameter termed the triple-phase line ratio. The theoretical predictions were in good agreement with our experimental results.

Planetary gear train and corresponding production method

Abstract: Described herein is a planetary gear train, comprising: a sun gear that can turn about an axis and comprises a plurality of first teeth; a fixed crown wheel comprising a plurality of second teeth; and two planetary gears, each comprising a plurality of third teeth, the planetary gears each meshing with the crown wheel and the sun gear and able to turn about second axes, which are in turn able to turn about the first axis; at least two third teeth simultaneously mesh with second teeth and further two third teeth simultaneously mesh with first teeth; the third teeth comprise a first and a second side, which have, respectively, a first and a second pressure angle different from one another; and the number of the third teeth is different from the absolute value of the semidifference between the number of the first teeth and of the second teeth.

Strain wave gearing with involute positive deflection tooth profile taking rim thickness into consideration

Abstract: In the strain wave gearing, an involute positive deflection tooth profile of a low pressure angle of less than 20° is used as the basic tooth profile for the rigid internal spur gear and the flexible external spur gear in order to increase the effective tooth depth. Continuous meshing of the two gears in the tooth trace direction is made possible by shifting the external teeth so that the linear parts of the rack tooth profiles coincide when viewed along the tooth trace direction. The root rim thickness of the front end of the external teeth of the flexible external spur gear is set to an optimal thickness and the root rim thicknesses at various positions other than the front end of the external teeth in the tooth trace direction are set to appropriate values.

Tooth profile design of dual-pressure angle involute helical tooth externally-meshed cylindrical gear

Abstract: The invention relates to a dual-pressure angle involute helical tooth externally-meshed cylindrical gear, and belongs to the technical field of gears. In the conventional involute helical tooth externally-meshed cylindrical gear, pressure angles at reference circles on two sides of involutes on the driving side and the driven side are equal to each other, but in the dual-pressure angle involute helical tooth externally-meshed cylindrical gear, a large pressure angle is formed at a reference circle of an involute on the driving side, and a small pressure angle is formed at a reference circle of an involute on the driven side, so the performance of the gear can be improved due to an asymmetrical design. A tooth profile on the end face of the gear comprises the involute (1) on the driving side, a tooth root transition curve (2) on the driving side, the involute (3) on the driven side, a tooth root transition curve (4) on the driven side, a tooth crest circular arc (5) and a tooth root circular arc (6); and the tooth profile on the end face moves along a spiral line to form the final dual-pressure angle involute helical tooth externally-meshed cylindrical gear.

Grinding hob for asymmetric tooth profile involute gear

Abstract: The utility model provides a grinding hob for an asymmetric tooth profile involute gear. The normal tooth profile of the grinding hob is an asymmetric rack tooth profile; a working side tooth profile comprises a working side main blade, a working side cutter tooth tip arc and a working side transition blade; the working side main blade is used for generating a gear working side involute through enveloping in the processing process; the working side cutter tooth tip arc is used for generating a gear working side tooth root arc in the processing process; the working side transition blade is arranged between the working side main blade and the working side cutter tooth tip arc; a non-working side tooth profile comprises a non-working side main blade, a non-working side cutter tooth tip arc and a non-working side transition blade; the non-working side main blade is used for generating a gear non-working side involute through enveloping in the processing process; the non-working side cutter tooth tip arc is used for generating a gear non-working side tooth root arc in the processing process; the non-working side transition blade is arranged between the non-working side main blade and the non-working side cutter tooth tip arc; a pressure angle of the working side main blade is in a range of 14-40 degrees; and the pressure angle of the working side main blade is 6-18 degrees larger than that of the non-working side main blade. The hob can be used for processing an asymmetric tooth profile involute gear.

A new approach to CNC programming for accurate multi-axis face-milling of hypoid gears

Abstract: A pair of hypoid gears refers to a pinion and a gear with skew axes. Hypoid gears are crucial to some power transmission systems, such as those of helicopters, power generation machines and automobiles. However, the design and manufacturing of hypoid gears are quite difficult. Currently, the major parameters of hypoid gears are calculated, but the geometries of the gears are not fully defined. To machine a hypoid gear, parameters of cutting systems are determined according to the gear design, whereas, settings of CNC machine tools with the machining parameters are also computed. The existing hypoid gears machining methods use the simplified blade model of the cutting systems, resulting in large errors in the machined gears. This new work proposes an accurate approach, to determine the parameters of the cutting system blades, for the face-milling of hypoid gears. In this work, a parametric model of the blades is established; and according to the hypoid gear parameters, the pressure angle and the cutting system radius are precisely calculated. Currently, hypoid gear engineers can use special CAD/CAM software to design the gears and to calculate machine settings. Unfortunately, these software are developed only for particular machine tools; it cannot be used for hypoid gear machine tools of different configurations. Moreover, few technical articles has been published to clearly address challenges in the CNC programming and post-processing for the multi-axis face-milling of hypoid gears, such as the parameters determination of a cutter system, its location and orientation calculation and CNC programs generation. To solve the current problems, another part of this research proposes a generic approach to CNC programming and post-processing for gear face-milling. The main contributions of this part includes (1) a new mathematical model to calculate the cutter system location and orientation and (2) a generic post-processing method to establish the machine kinematics chain and to compute the coordinates of the machine axes in face-milling. This approach provides a general and accurate methodology for the face-milling of hypoid gears on any machine tools and can be directly applied to the hypoid gear manufacturing for better quality.

Influencing Factors of Silicone Rubber Static Contact Angle Measurement

Abstract: To improve accuracy of static contact angle measurement of silicone rubber material,the influence of various factors on accuracy of silicone rubber static contact angle measurement should be studied.Basing on a contact angle meter,digital camera and dynamic and static contact angle calculation software DSCA(dynamic static contact angle),we studied the influences of globule volume,delay time,temperature,water conductivity and sample longitudinal inclination on the static contact angle measurement according to sessile drop method.Results indicate that globule volume has little influence on the static contact angle measurement result,while different volume's globule images need different algorithms to calculate the contact angle.Static contact angle decreases with increase in delay time,however,clean,corona,and completely migration-contaminated samples have slow decrease speed,meanwhile,immersed,incompletely migration-contaminated samples have fast decrease speed.Temperature has some influences on the static contact angle measurement,static contact angle becomes small at low temperature.Water conductivity has no obvious effect on the measured static contact angle.If inclination direction is negative,the inclination may cause large error.If inclination direction is positive,in despite of large static contact angle or small static contact angle,the inclination has little influence on the measurement result of static contact angle,however,the inclined globule image will cause difficulty in automatic calculation of static contact angle.So,if a sample is taken out from low temperature condition,it must be placed to room temperature,if the sample is taken out from high temperature condition,it can be measured directly.The globule volume should be selected as 2~4 μL.The globule image should be pictured in 5 s after dripping.Deionized water should be selected,and running water or saline water with certain conductivity can be substituted.Photos should be taken when silicone rubber plane is perpendicular to camera lens plane.

Timing gear housing gear train for common-rail engine

Abstract: The invention discloses a timing gear housing gear train for a common-rail engine. The engagement relationship of each gear in a gear train is that: a crank gear is engaged with an idler gear; the left side of the idler gear is engaged with a gear of a fuel injection pump, and the right side of the idler gear is engaged with a cam shaft gear; the right side of the cam shaft gear is engaged with a transmission gear of a compression pump; a steering pump gear is engaged with the cam shaft gear; a fuel pump gear is engaged with the idler gear; a code wheel and the cam shaft gear are coaxial and share a long bond, and positioned and fixed on a cam shaft; the normal module of each gear, the pressure angle and the helical angle of a gear on a reference cylinder in the gear train are kept to be consistent; and the valve timing and fuel supply timing of an engine are determined by a positioning pin rather than the engagement mark on the gear. The timing housing gear train has a simple structure, can fulfill valve and fuel supply timing of the engine, can drive a plurality of pumps to realize that the engine can be more compact and effectively improve the transmission efficiency, and is applicable to a common rail engine of a preposed gear train.

Study on Minimum Teeth without Undercutting of the Spur Involute Gears with 22.5º and 25º Pressure Angle Based on VB

Abstract: After considering the rack cutter's addendum, the minimum teeth without undercutting of spur gears with 20o, 225o and 25o pressure angle were carried out analysis and comparison in this paper On the basic of gear generating principles, origin and basic architecture of undercutting were presented, and the phenomenon of undercutting was theoretically investigated And, there also are simulated result by means of VB and experimental results in this paper The rack cutter is used to infer minimum teeth without undercutting of in volute gears with the pressure angle of 225o and 25o, and correct minimum teeth without undercutting are got when the pressure angle are respectively 225o and 25o Then, virtual simulations in the circumstance of software VB are applied to verify the validity of theoretical calculations

Effect of Pressure Angle on Bending Stress and Deformation of Asymmetric Spur Gear Using FEA

Abstract: A gear is a rotating machine part having cut teeth, which mesh with another toothed part in order to transmit torque. Gears may be spur, helical, bevel or worm in which spur gear is most common type of gear used in engineering applications. In the automobile and aerospace industries, higher strength, higher reliability and lighter weight gears are necessary as lighter automotives continue to be in demand. This has lead to development of new designs, such as gears with asymmetric teeth. The geometry of these teeth is such that the drive side profile is not symmetric to the coast side profile and it is beneficial for special applications where the loading of the gear is uni-directional. In such an instance, the loading on the gear tooth is not symmetric, thus calling for asymmetric teeth. The coefficient of asymmetry is dependent on pressure angle; therefore study of effect on pressure angle on asymmetric tooth is of great importance. This paper presents a study on effect of pressure angle on asymmetric involute spur gear.

Tooth Profile Design of an Oval Gear According to the Curvature of the Pitch Curve

Abstract: Dept. of Mechanical Engineering, Inha Technical College(Received January 2, 2012; Revised January 25, 2012; Accepted January 26, 2012)Abstract − Oval gears are typical kinds of non-circular gears and are widely used in flow meters. This paperpresents a tooth profile design of an oval gear according to the curvature of the pitch curve. The length of thepitch oval is divided by the number of teeth and the curvature of the divided points is obtained. The tooth profileis designed on the circle of the curvature as if it is the pitch circle of a gear. The teeth of the oval gear have thesame module and pressure angle, but the pitch circle of each tooth differs in size. Thus, the teeth on the dividedpoints of the pitch oval are different in shape. This type of oval gear will improve the meshing properties. Keywords − oval gears(오벌기어), non-circular gears(비원형 기어), pitch oval(피치오벌), curvature(곡률),tooth profile(치형 형상)

Double contact gear hobbing cutter

Abstract: The invention relates to a double contact gear hobbing cutter. The main points include that the addendum circle radius of the gear hobbing cutter is 0 to 0.3 time of modulus; a standard pressure angle with an angle degree of 15-30 degrees is arranged on a gear surface of 0.3 to 0.8 time of gear height below the addendum; an interference amount cutting pressure angle with an angle degree of 22-37 degrees is arranged on a gear surface of 0.05 to 0.6 time of the gear height below the standard pressure angle; and an addendum chamfering pressure angle with an angle degree of 25-50 degrees is arranged on a gear surface of 0.05 to 0.3 time of the gear height below the interference amount cutting pressure angle. The double contact gear hobbing cutter has the advantages of being simple in structure, easy to manufacture, low in cost, convenient and rapid to mount and dismount, used for processing double contact gears, simple in process, low in processing time and capable of guaranteeing the smooth connection between gradual opening line portions and transition curve portions, improving processing accuracy of the double contact gears and processing efficiency and reducing processing cost.

The Influence of Cross Angle on the Flow Ripple of Axial Piston Pumps by CFD Simulation

Abstract: This paper studies the flow pulsation of axial piston pumps of different cross angles based on CFD simulation. The swash-plate cross angle of piston pump affects the piston pump outlet flow pulsation by changing the contraction amount of the plunger in the valve plate transition zone. First, we established the flow pulsation model with swash plate cross angle based on the noise reduction principle of the swash plate cross angle, and studied the influence of cross angle of different rotation angels on the flow pulsation based on CFD simulation. The conclusion is that the maximum and minimum peak of the flow pulsation decreased when the rotation angle of the cross angle is greater than 1 °; the maximum and minimum peak of the flow pulsation increased when the rotation angle of the cross angle is less than -1 °; a good noise reduction can be got when the piston pump cross angle rotates 1°.

Method for improving grinding crack of molding gear-grinding machine

Abstract: The invention relates to a method for improving a grinding crack of a molding gear-grinding machine Parameters of the gear-grinding machine for grinding a reducer gear are as follows: a modulus M equal to 3282, a tooth number Z equal to 32, a pressure angle alpha equal to 20 degrees, a spiral angle beta equal to 0 and a tooth width B equal to 368 Tooth surface carburized quenching is taken as a heat treatment mode; quenching hardness is HRC58-62; a grinding wheel is made of corundum 4-400*70*127SA60J-35m/s; a particle size is 60; a linear velocity of the grinding wheel is 20m/s for coarse grinding and 30m/s for fine grinding; a stroke speed is 2000mm/min for coarse grinding and 1800mm/min for fine grinding; a stroke number is 2; a grinding volume is 002mm, 0015mm, 001mm and 00088mm; a cutter grinding times: the grinding wheel is polished for one time by each three teeth; and a coolant flow is increased The method provided by the invention has the advantages that after the grinding parameters are adopted, under the condition of processing a same component, no crack phenomenon exists and the quality of products is stable

Pre-grinding gear hob

Abstract: The utility model belongs to the technical field of machinery, and provides a pre-grinding gear hob which solves the problems of long gear grinding time and low processing efficiency of the conventional pre-grinding gear hob. The pressure angle of the pre-grinding gear hob is 20 DEG, the dedendum transitional fillet R is 0.2 modulus, a tooth curve at the addendum of the hob is an ellipse, the cross section of the tooth bottom of the addendum is the major axis of the ellipse, the distance between the center of the major axis to the end of the addendum is the minor semi-axis of the ellipse, the length of the minor semi-axis is 0.65 of that of the major semi-axis, the small pressure angle of the hob ranges from 9 DEG to 13 DEG, the whole depth of the hob is 2.7 modulus, and the height of addendum ranges from 1.25 modulus to 1.5 modulus. The pre-grinding gear hob has the advantages of short gear grinding time and high processing efficiency.

Silent chain transmission device

Abstract: PROBLEM TO BE SOLVED: To improve the durability of a chain transmission device while suppressing noise.SOLUTION: By using a hob cutter having an inside flank, a pitch and a pressure angle common to a silent chain 1, a sprocket 2 is cut by such gear cutting addendum modification as it is determined by the following formula: (D/2) cos(π/2z)≤H≤(D/2) cos(π/4z), where H is a distance between the advancing direction pitch line PLc of the silent chain 1 and the center of a sprocket 2, z is the number of teeth of the sprocket 2, and D is the diameter of a pitch circle in such a state that the silent chain 1 is wound around the sprocket 2.

Theoretical Study on Real Tooth Surface of Novel Toroidal Worm by the Forming Method

Abstract: The aim of this paper is to validate the rationality of the forming method for the worm surface in a novel toroidal worm-gearing with spherical meshing elements, which is made up of worm, steel balls and worm gear. Based on the directrix of worm surface, the mathematic model of worm surface is established and the directrix-based forming method for machining worm surface is proposed. Further, the principle error in the machining process is analyzed and the theoretic and real tooth surfaces of worm are fitted and compared on Open GL platform. The results show that the tooth profile error can be controlled at the range of 0~1×10 !5 mm and it is always 0 at the pressure angle.

Effect of Gear Design Variables on the Dynamic Stress of Multistage Gears

Abstract: This work presents a numerical model developed to simulate and optimize the dynamic stress of multistage spur gears. The model was developed by using the Lagrangian energy method and modified Heywood method, and applied to study the effect of three design variables on the dynamic stress on the gears. The first design variable considered was the module, and the results showed that increasing the module resulted to increased dynamic stress levels. The second design variable, pressure angle, had a strong effect on the stress levels on the pinion of a high reduction ratio gear pair. A pressure angle of 25 o resulted to lower stress levels for a pinion with 14 teeth than a pressure angle of 20 o . The third design variable, the contact ratio, had a very strong effect on bending stress levels. It was observed that increasing the contact ratio to 2.0 reduced dynamic stresses significantly. For the gear train design used in this study, a module of 2.5 and contact ratio of 2.0 for the various meshes was found to yield the lowest dynamic stress levels on the gears. The model can therefore be used as a tool for obtaining the optimum gear design parameters for optimal dynamic performance of a given multistage gear train. Keywords: dynamic load, dynamic bending stress, gear design parameters, mesh stiffness, multistage gear train

Design of Planetary Gear Reducer with Double Circular-Arc Helical Gear

Abstract: The two gears of the double circular-arc helical gear is a mesh of a concave/convex combination. Because the curvature is close to each other, the strength also increased and thus, it is often used in heavily-loaded workplaces. The national standard for double circular-arc helical gear (ex., GB12759-91) is based on the size of the gear module to design its tooth profile. This shows that tooth geometric-related designs are quite complicated. If the effect of the different pressure angle parameter is considered, we would be unable to conduct relevant studies for the original standard formula with a double circular-arc helical gear set at a pressure angle of 24°. Firstly, this paper would redefine a new double circular-arc helical gear according to the discontinuousness tooth profile molded line of the double circular-arc helical gear and unchangeable pressure angle and explain the improvements in the design and stress analysis of the tooth especially since the double circular-arc helical gear has no limitation in the minimum number of teeth. Thus, the decrease in the driving gears’ number of module and can further increase the reduction gear ratio. For heavily-loaded planetary gear reducer, it’s quite obvious in the miniaturizing and high torque superiority. This paper also used certain winch’s speed reducer as example to explain that the change of the pressure angle can reduce contact stress by 3%~40% and also enhances the torque ability by 3%~40%.

Power output mechanical device for tractor

Abstract: The utility model particularly relates to a power output mechanical device for a tractor. The power output mechanical device mainly comprises a power output transmission shaft, a low-gear driving gear, a high-gear driving gear, a high-gear driven gear, a low-gear driven gear, a power output intermediate shaft, a power output shaft and the like, wherein the power output transmission shaft is connected with the low-gear driving gear and the high-gear driving gear through an involute spline; the involute spline has a modulus of 2.5mm, 15 teeth, a major diameter of phi40 -0.337mm and a minor diameter of phi33.75 -0.337mm; each of the low-gear driving gear, the high-gear driving gear, the high-gear driven gear and the low-gear driven gear has a pressure angle of 25 degrees; and the power output shaft is an eight-tooth rectangular spline, and the eight-tooth rectangular spline has a tooth width of 7.98 -0.11mm, a major diameter of phi48 -0.087mm and a minor diameter of phi40 -0.1mm. The strength of each of the gears and the shafts is strengthened, and a center distance and a transmission ratio are not required to be redesigned and changed; and the power output mechanical device is particularly suitable for solving the problem of tooth breakage caused by the weak roots of the gears, and has the characteristics of easiness for implementation and high universality.

Experimental and numerical stress analysis of involute splined shaft

Abstract: In this study, the induced splined shaft teeth contact and bending stresses have been investigated numerically using finite element method(Ansys package version 11.0) with changing the most effecting design parameter, (pressure angle, teeth number, fillet radius and normal module), for internal and external splined shaft. Experimental work has been achieved using two dimensional photoelastic techniques to get the contact and bending stresses; the used material is Bakelite sheet type "PSM-4". The results of numerical stress analysis indicate that, the increasing of the pressure angle and fillet radius decrease the bending stress and increase the contact stress for both internal and external spline shaft teeth while the increasing of the normal module and teeth number decrease the contact and bending stresses.

Analysis of Contact Stresses in Altered Tooth-Sum Spur Gearing

Abstract: Contact stress between the gear teeth in mesh determines the ability of the gear to transmit the power safely. In improving the contact strength of gear teeth, profile shift is found to be the best option beyond the use of high strength materials and surface treatment techniques. This paper discusses an alternate yet simple method of improving contact strength by the way of altering the tooth-sum. Altering the tooth-sum working between a specified center distances for a given module changes the operating pressure angle and hence necessitates profile shift. Using this profile shift gears can be designed to advantage. Few cases are considered for the purpose of discussion for clear understanding of the presentation. Large volume of monographs are developed which the practicing engineers can use.