Showing papers on "Pressure angle published in 2019"

Contributions to the Synthesis of Fixed Axle Gears by Avoiding the Interference Phenomenon

Abstract: It can be seen that the minimum number of teeth required to avoid interference for the standard pressure angle, normally on the alpha0 = 20° decomposition circle, is 13, corresponding to a transmission ratio i = 1 and increases with the transmission ratio i reaching to the maximum value of 18 teeth for i>100. For normal transmission ratios, values ranging from 13 to 17 teeth for standard pressure angle. If alpha0 decreases to 4°, zmin varies between 275 and 410 teeth. When alpha0 increases to 35°, zmin varies between 5 and 6 teeth. By lowering the number of teeth of the drive wheel 1, the coverage and gearing decreases as well as increases the pressure angle, increases effort, wear and reduces the life span of the gear. If we increase in turn, the minimum number of input wheel teeth increases the coverage, increases the gear efficiency, reduces the pressure angles and effort in the coupling, increases gear reliability and operates with much lower vibrations and noise, with high yields and for a longer time. The minimum number of teeth required to avoid interference is basically a function of the transmission ratio i = |i12| = z2/z1 and the normal pressure angle of the alpha circle and the angle of inclination of the beta teeth. This is practically also maintained in internal gear gears, where there are still two additional types of interference. It is noted that zmin decreases when i decreasing and when alpha0 and/or beta increases.

A review on failure characteristics of polymeric gears

Abstract: The importance of polymer gears is increasing continuously since its advent in 1950s and developing at a very fast pace due to some of its advantage over metallic gears like light weight, self-lubricating, low noise, etc. However, due to its low mechanical property and poor heat conduction, its failure mechanism is observed entirely different comparative to metallic gears. This article presents different behavior of failures which takes place in polymer gears viz. wear, thermal and fatigue failure. Review of different polymeric materials like Nylon, Acetal, etc. are reviewed here. It is observed that acetal gear fail due to wear while nylon gear fail due to fracture below the pitch line, nearer to the root. It is also observed that mechanical property and resistance to thermal deformation of composite nylon gear improves to a significant level. Influence of rotational speed up to 1200 rpm on life cycles of gear is found negligible up to the limit of bending stress of 15MPa. Whereas influence of rotational speed is found considerable above the bending stress of 20MPa and hence the mode of failure becomes plastic deformation. Based on the literature review it is observed that an asymmetric polymer gear is being preferred in specific operating conditions where there is a requirement of high load carrying capacity and in case of unidirectional transmission loading. Bending fatigue performance of polymer gear is found improved when its pressure angle on drive side is increased from 20° to 34° as in case of an asymmetric gear.

Simulation Research on the Time-Varying Meshing Stiffness and Vibration Response of Micro-Cracks in Gears under Variable Tooth Shape Parameters

Abstract: The gear is one of the important parts of a rotary gearbox. Once catastrophic gear failure occurs, it will cause a great threat to production and life safety. The crack is an important failure factor causing changes in time-varying stiffness and vibration response. It is difficult to effectively identify the vibration response and meshing stiffness changes when there is a fine crack in the gear. Therefore, it is of great importance to improve the accuracy of meshing stiffness calculation and dynamic simulations under micro-cracks. Investigations of meshing stiffness and the vibration response of a gearbox is almost all about fixed gear shape parameters. However, the actual production process of gear system needs to change gear shape parameters. In this paper, the meshing stiffness and vibration response of the dynamic simulation signals of gear teeth with different crack depths at different tooth shape parameters (the pressure angle, the modulus, and the tooth number) were calculated, respectively. The influence of cracks on the vibration response was investigated by the fault detection indicators, the Root Mean Square (RMS), the kurtosis, and the crest factor. The result shows that when the pressure angle and modulus change, the vibration response changes erratically. However, when the tooth numbers change, the vibration response changes regularly. The results could be a guide for choosing gears in different shape parameters when system stability is the aim.

Multi-objective Dimensional Optimization of a 3-DOF Translational PKM Considering Transmission Properties

Abstract: Multi-objective dimensional optimization of parallel kinematic manipulators (PKMs) remains a challenging and worthwhile research endeavor. This paper presents a straightforward and systematic methodology for implementing the structure optimization analysis of a 3-prismatic-universal-universal (PUU) PKM when simultaneously considering motion transmission, velocity transmission and acceleration transmission. Firstly, inspired by a planar four-bar linkage mechanism, the motion transmission index of the spatial parallel manipulator is based on transmission angle which is defined as the pressure angle amongst limbs. Then, the velocity transmission index and acceleration transmission index are derived through the corresponding kinematics model. The multi-objective dimensional optimization under specific constraints is carried out by the improved non-dominated sorting genetic algorithm (NSGA II), resulting in a set of Pareto optimal solutions. The final chosen solution shows that the manipulator with the optimized structure parameters can provide excellent motion, velocity and acceleration transmission properties.

Conceptual Design and Computational Modeling Analysis of a Single-Leg System of a Quadruped Bionic Horse Robot Driven by a Cam-Linkage Mechanism.

Abstract: In this study, the configuration of a bionic horse robot for equine-assisted therapy is presented. A single-leg system with two degrees of freedom (DOFs) is driven by a cam-linkage mechanism, and it can adjust the span and height of the leg end-point trajectory. After a brief introduction on the quadruped bionic horse robot, the structure and working principle of a single-leg system are discussed in detail. Kinematic analysis of a single-leg system is conducted, and the relationships between the structural parameters and leg trajectory are obtained. On this basis, the pressure angle characteristics of the cam-linkage mechanism are studied, and the leg end-point trajectories of the robot are obtained for several inclination angles controlled by the rotation of the motor for the stride length adjusting. The closed-loop vector method is used for the kinematic analysis, and the motion analysis system is developed in MATLAB software. The motion analysis results are verified by a three-dimensional simulation model developed in Solidworks software. The presented research on the configuration, kinematic modeling, and pressure angle characteristics of the bionic horse robot lays the foundation for subsequent research on the practical application of the proposed bionic horse robot.

Research on Dynamic Load-Sharing Characteristics of Two-Stage Asymmetric Star Gear System

Abstract: It is well known that the asymmetric gears of the transmission system enhances the load carrying capacity of system, but there is no relevant conclusion about the dynamic load-sharing characteristics of the asymmetric gear transmission system. In order to analyze the dynamic performance of an asymmetric gear system, taking two-stage asymmetric helical gear star drive system as the research object, the load-sharing model of the two-stage asymmetrical helical star gear system is established by the centralized mass method and Newton's second law. The load sharing characteristic of the star gear is studied about the floating member and the tooth profile pressure angle. The influence of eccentricity error, load and input speed on the load sharing performance of the system is analyzed. Based on ADAMS virtual prototype model, through the simulation analysis of the dynamic meshing force of gears, the load sharing coefficient of each star gear is calculated, compare the results with the MATLAB solution to verify the correctness of the theory.

Modeling and Simulation of Mild Wear of Spur Gear Considering Radial Misalignment

Abstract: An appropriate clearance is required between mating gears for effective power transmission. In the present work, the effect of radial misalignment on mild wear of spur gear is modeled and simulated. The changes in the gear tooth contact geometry due to progressive wear have also been accounted in the model. The simulation results show that in the pinion dedendum region, pressure angle increases, while the contact pressure and wear depth decrease with increase in number of wear cycles. As far as the effect of radial misalignment is concerned, contact pressure decreases and wear depth increases with the increase in misalignment. In the pinion addendum region, pressure angle and wear depth increase with the increase in wear cycles, while the contact pressure and wear depth decrease with the increase in misalignment. The pressure angle and pitch point change from initial 20° (23rd pitch point) to 20.95° (26th pitch point) and 21.86° (28th pitch point) due to 0.5- and 1-mm radial misalignment, respectively. The wear depths after 50,000 wear cycles are − 1.32 × 10−2 μm, − 3.33 × 10−3 μm and − 4.39 × 10−4 μm at 23rd, 26th and 28th pitch points, respectively. The effect of radial misalignment on backlash, pressure angle, pitch point, contact ratio, double tooth contact region and speed ratio is also discussed.

Influence of grinding wheel parameters on the meshing performance of toroidal surface enveloping conical worm drive

Abstract: . A new type of toroidal surface enveloping conical worm gearing is proposed in our recent work (Chongfei and Yaping, 2019b). According to its forming principle, the geometrical shape of the generating surface has an important influence on the geometry characteristic of the enveloping worm pair. To explore the reasonable principles for selecting the geometrical parameters of the grinding wheel, some numerical study examples are performed. In this process, the methods for the tooth crest width are developed. Simple strategies for estimating the risk of the worm tooth surface being located in the invalid area and the risk of the curvature interference on the tooth surface are proposed. The numerical result shows that increasing the radius of the toroidal-generating surface and the nominal pressure angle of the grinding wheel are beneficial to improve the engagement behavior of the conical worm pair, but the tooth crest sharpening of the conical worm may happen if they are too large. For the nominal radius of the grinding wheel, it has a negligible effect on the meshing characteristics of this worm set. In addition, the selection principle of the parameters is also suggested.

Teeth profile parameter design and transmission property analysis of external generating wave movable teeth transmission

Abstract: A highly efficient integrated transmission unit – external generating wave movable teeth transmission − was proposed and two kinds of typical transmission types were researched. Fixed and moving coordinate systems were established based on movable teeth transmission theory. On the basis of the profile of a wave generator, the teeth profile equations of ring gear were deduced by using the transform matrix and profile enveloping principle. The effects of the teeth number of the ring gear, generating wave coefficient, and tooth profile coefficient on the profile of the ring gear were investigated. The formula for calculating curvature radius of the ring gear was given. The pressure angle formulas were deduced, and the change rule of the pressure angle extremum was researched to obtain a continuous transmission condition. The relationship between design parameters and performance effect was analysed based on the analysis of the curvature and pressure angle. The results show that the transmission precision reached 97.67%, and the proper design parameters could guarantee transmission performance. Those researches lay a theoretical foundation for the design and application of an external generating wave movable teeth title.

Effects of Drive Side Pressure Angle on Gear Fatigue Crack Propagation Life for Spur Gears With Symmetric and Asymmetric Teeth

Abstract: Today gears are one of the most crucial machine elements in the industry. They are used in every area of the industry. Due to the high performances of the gears, they are also used in aerospace and wind applications. In these areas due to the high torques, unstable conditions, high impact forces, etc. cracks can be seen on the gear surface. During the service life, these cracks can be propagated and gear damages can be seen due to the initial cracks. The aim of this study is to increase the fatigue crack propagation life of the spur gears by using asymmetric tooth profile. Nowadays asymmetric gears have a very important and huge usage area in the industry. In this study, the effects of drive side pressure angle on the fatigue crack propagation life are studied by using the finite element method. The initial starting points of the cracks are defined by static stress analysis. The starting angles of the cracks are defined constant at 45°. The crack propagation analyses are performed in ANSYS SMART Crack-Growth module by using Paris Law. Four different drive side pressure angles (20°-20°, 20°-25°, 20°-30° and 20°-35°) are investigated in this study. As a result of the study the fatigue crack propagation life of the gears is increased dramatically when the drive side pressure angle increase. This results show that the asymmetric tooth profile not only decrease the bending stress but also increase the fatigue crack propagation life strongly.

Analysis of the Involute and Sinusoidal Gears by the Operating Parameters and a New Method of Its Cutting

Abstract: Today, involute spur gears are the most common in mechanical engineering. However, besides of the benefits, involute teeth present several disadvantages. To overcome those disadvantages, designers resort to changes that increase the complexity of equipment, cutting tools that lead to the expensive cost. On another hand, gear and transmission, namely sinusoidal gear and transmission is known by higher properties. The results of the simulation of involute and sinusoidal gearing are described in the article. Proved that, sinusoidal gears have higher performance parameters. Simulation confirmed that sinusoidal gear have higher bending strength, lower contact stress, reduced contact friction and tension in the edging contact, improved performance indicators of transmission. The advantages are due to the following features of the sinusoidal gears geometry: gear tooth profile outlined by a smooth sine wave curve; greater teeth thickness on the pitch circle; wide range of coast flank pressure angle. A new method of gears machining is described. This technology makes it possible to reduce number of expensive and complex gears cutting tools and gears machine tools, greatly simplifies technology of tooth cutting and reduces the cost of gears manufacturing by a numerous times. The method has a wide versatility, provides the opportunity to produce a variety of gears types including, gears with asymmetric teeth.

Influence of Addendum Modification Factor on Root Stresses in Normal Contact Ratio Asymmetric Spur Gears

Abstract: Tooth root crack is considered as one of the crucial causes of failure in the gearing system and it occurs at the tooth root due to an excessive bending stress developed in the root region. The modern power transmission gear drives demand high bending load capacity, increased contact load capacity, low weight, reduced noise and longer life. These subsequent conditions are satisfied by the aid of precisely designed asymmetric tooth profile which turns out to be a suitable alternate for symmetric spur gears in applications like aerospace, automotive, gear pump and wind turbine industries. In all step up and step down gear drives (gear ratio > 1), the pinion (smaller in size) is treated as a vulnerable one than gear (larger in size) which is primarily due to the development of maximum root stress in the pinion tooth. This paper presents an idea to improve the bending load capacity of asymmetric spur gear drive system by achieving the same stresses between the asymmetric pinion and gear fillet regions which can be accomplished by providing an appropriate addendum modification. For this modified addendum the pinion and gear teeth proportion equations have been derived. In addition, the addendum modification factors required for a balanced maximum fillet stress condition has been determined through FEM for different parameters like drive side pressure angle, number of teeth and gear ratio. The bending load capacity of the simulated addendum modified asymmetric spur gear drives were observed to be prevalent (very nearly 7%) to that of uncorrected asymmetric gear drives.

Automatic hole making and riveting control system and control method

Abstract: The invention discloses an automatic hole making and riveting control system and control method. The automatic hole making and riveting control method comprises the following steps that a robot is controlled through a robot controller to move to a position, to be provided with a hole, of an aircraft wall plate; a positioning nail on the aircraft wall plate are shot, and coordinates are determined;the deviation between the positioning nail coordinates acquired by a visual camera and preset theoretical coordinates is determined based on the coordinates through the robot controller; the robot iscontrolled to move through the robot controller according to the deviation; the distance from a pressure angle unit arranged on the robot to the aircraft wall plate is detected through a laser sensor; the normal direction of the pressure angle unit and the normal deviation angle of the airplane wall plate are calculated through a PLC according to the distance; the deviation angle is sent to the robot controller; the angle of the tail end of a machine arm of the robot is adjusted through the robot controller according to the received deviation angle, so that the normal direction of the pressure unit is perpendicular to the aircraft wall plate; and the robot is controlled to complete hole making and riveting through the robot controller. According to the automatic hole making and riveting control system and control method, the automation efficiency and the assembly precision of the aircraft wall plate can be improved.

Dynamic State or Whole Field Analysis of Helical Gear

Abstract: To determine the true bending stresses at the root of the tooth is an important and crucial step in accurate design of the gears. The present work has been intended for bending stress analysis at critical section of helical gear tooth under dynamic state by different methods. The photo stress coating method along with reflection polariscope was used as experimental method. Velocity factor method and Spott’s equation method have been used to estimate dynamic load and bending stress at critical section of tooth. LS DYNA software has been used for finite element analysis under dynamic state. The results show that the experiment photo stress method gives bending stress closer to the true value in dynamic conditions amongst all method under consideration. Finally, the study proposes the correction factor for velocity factor method and Spott’s equation method to estimate true bending stress at tooth root with respect to experimental method.

End face tooth cycloidal-pin wheel pair and nutation speed reduction device

Abstract: The utility model provides an end face tooth cycloidal pin gear pair and a nutation speed reduction device. The end face tooth cycloidal pin gear pair comprises a cycloidal gear with a cycloidal toothsurface and a pin gear with a pin gear tooth surface. the pin gear is meshed with the cycloid gear in a nutation transmission mode; the included angles between the indexing surfaces of the pin gear and the cycloid gear and the corresponding axes are between 88 degrees and 91 degrees, and the sum of the two included angles is less than 180 degrees; wherein the mutually meshed parts of the pin wheel tooth surface and the cycloid tooth surface are respectively a pin wheel working tooth surface and a cycloid gear working tooth surface; and the pressure angle of the working tooth surface of the pin wheel and the working tooth surface of the cycloid gear during meshing meets the condition that alpha is greater than or equal to 45-beta-5 degrees and less than or equal to 45-beta + 5 degrees, wherein alpha is the pressure angle and beta is the friction angle between the working tooth surface of the pin wheel and the working tooth surface of the cycloid gear. The nutation speed reduction device comprises a shell, an end face tooth cycloidal-pin wheel pair arranged in the shell, an input mechanism used for driving the cycloidal-pin wheel pair to perform nutation motion, an output mechanismconnected with the cycloidal-pin wheel pair, and a torque transmission component used for transmitting torque of the cycloidal-pin wheel pair.

Cycloidal gear tooth profile linear modification method and cycloidal pin gear transmission device

Abstract: The invention provides a cycloidal gear tooth profile linear modification method and a cycloidal pin gear transmission device, the method comprising the following steps: S1, setting cycloidal gear tooth profile curve parameters; S2, deducing the equation of the tooth profile curve and the formula of the curvature radius of a cycloidal gear; S3, deriving the equation of pressure angle alpha with respect to psi; S4, deducing the equation of the meshing angle alpha' of the cycloidal gear tooth profile; S5, deducing the relation equation between the pressure angle alpha of the cycloid gear tooth profile and the meshing angle alpha'; S6, modifying the pin tooth radius rz=rz (psi), wherein rz (psi) is a linear function of the rotation angle psi, and solving the linear function rz (psi). At the same time of ensuring the required backlash of installation, lubrication and the like, the invention can obtain small cultivation amount and higher transmission accuracy.

Method for machining reverse bevel gear by variable pressure angle hobbing cutter

Abstract: The invention relates to a method for machining a reverse bevel gear by a variable pressure angle hobbing cutter. By means of the method, the problem that an out-of-gear risk of a transmission is increased due to the occurrence of bigger errors when matching a joint surface and a reverse bevel gear machined by an existing machining method is solved. The method comprises the following steps: 1, calculating a standard root cone angle theta by using a formula through a back taper tooth pressure angle alpha n and a rounding included angle gamma; 2) determining a pressure angle alpha t of the variable pressure angle hobbing cutter; 3) calculating a variable pressure angle back root cone angle theta'; and 4, debugging the movement path of a machine tool shaft on a gear hobbing machine accordingto the variable pressure angle back root cone angle theta', and finishing the machining of the reverse bevel gear by the variable pressure angle hobbing cutter.

Balancing of a Wire Rope Hoist Using a Cam Mechanism

Abstract: To design machines that perform their mechanical functions with minimal power consumption is an important and challenging issue. It may be obtained by applying a gravity balanced mechanical systems. The objective of the paper is to design a cam-roller follower mechanism to gravity balance a wire rope hoist for lifting loads. It is analysed how various geometric features affect the applicability of the cam mechanism (jerks, pressure angle, roller radius). The paper provides the method to synthesize cams with different geometries realizing the same performance, among which a designer can choose the one that is optimal with respect to strength properties.

Solar Tracking Linkage RSSR for all Latitudes

Abstract: In the paper, a planar 2 DOF RSSR solar tracking linkage applicable for all latitudes is analyzed. The mechanism is contained in the vertical North-South plane of the observer. The coupler angle relative to horizontal plane defines the tilt angle χ of the active conversion surface and depends on the latitude and Earth’s declination. It can be modified by a linear actuator. The coupler passive motion defines the diurnal angle φ3 of the active conversion surface and it is driven by a second linear actuator. The angles χ and φ3 are limited to - 65° … + 65° by constructive requirements of the linkage and pressure angle. Optimal mechanism design and functionality simulation at different latitudes are detailed in the paper. A case study for latitude φ = 50° corresponding to Krakow region is presented in the paper. As result, tracking efficiency is very high, the solar energy lost is below 1% for winter time and under 4% for summer time from the total available solar energy in a clear sky day.

Brute force gear cutting cutter design method

Abstract: The invention discloses a brute force gear cutting cutter design method. When a gear is cut with brute force, a crossed axis angle is formed between the axis of a brute force gear cutting cutter and the axis of a machined gear, namely, a pair of staggering shafts is formed between the brute force gear cutting cutter and the machined gear, according to the engagement principle of no-gap engagementof a cylinder and the gear, namely, the screw pitch of a pitch circle is equal to the relation between the pitch circle gear thickness of the machined gear and the pitch circle gear thickness of the brute force gear cutting cutter, the end face pitch circle pressure angle of the brute force gear cutting cutter and the end face pitch circle pressure angle of the machine gear are calculated and obtained, and thus, in combination with other known parameters, design of the brute force gear cutting cutter is achieved. When the brute force gear cutting cutter designed by adopting the method machinesthe gear, in comparison with a common gear inserting cutter, the machining efficiency can be improved by 4-8 times, the gear surface roughness Rz is improved by 2-3 levels, and the gear machining precision reaches the ISO7 level.

Asymmetric gear design method based on tooth profile inclination deviation

Abstract: The invention provides an asymmetric gear design method based on tooth profile inclination deviation. According to the method, a left-right tooth surface and tooth root complete symmetry small pressure angle tooth profile gear can be designed according to a standard cylinder gear design method, the pressure angle of a large pressure angle tooth profile gear is calculated according to the standardcylinder gear design method and the strength requirement needed for the drive work condition, accordingly, the tooth profile inclination deviation is calculated, then, shape correction is conducted from the involute start circle position on the drive tooth surface of the small pressure angle tooth profile gear according to the tooth profile inclination deviation, and the large pressure angle toothprofile is obtained; and finally, tooth thickness compensation is conducted at the pitch circle position for the large pressure angle tooth profile, and an asymmetric gear in which the drive tooth surface and the reverse dragging tooth surface are different in pressure angle but side clearance is normal is finally obtained. According to the asymmetric gear design method, tooth profile inclinationdeviation shape correction is conducted on the drive tooth surface, the large pressure angle tooth profile is obtained, accordingly, the drive tooth surface can meet the large-torque drive requirement, and the reverse dragging tooth surface meets the low-torque NVH requirement.

Design method of incomplete gear transmission mechanism with variable motion-stand ratio

Abstract: The invention discloses a design method of an incomplete gear transmission mechanism with a variable motion-stand ratio. The method includes steps of S1, calculating the number of hypothetical full circumference teeth of a driven wheel according to the number of hypothetical full circumference of a driving wheel and the modulus of the driven wheel; S2, calculating the contact ratio of the drivingwheel and the driven wheel according to a pressure angle of a first tooth of the driving wheel and a tooth top pressure angle of the driven wheel, if the contact ratio is greater than 1, starting to carry out the step S3, and if not, starting operation from the step S1 to re-adjust the number of the hypothetical full circumference teeth of the driving wheel; S3, based on the circle center angle corresponding to each toothed segment on the driving wheel and the corresponding motion-stand ratio of the toothed segment, determining the circle center angle value corresponding to the locking arc, adjacent to the toothed segment, of an incomplete driving gear; and S4, making sure that the number of the toothed segments of a moving wheel is equal to the number of the toothed segments of the driving wheel, and the difference between the number of teeth of each toothed segment on the driving wheel and the number of teeth of the corresponding tooth segment on the driven wheel is one. According tothe method, the designed incomplete gear has compact structure and is easy and convenient to design.

A method for modifying cycloidal wheel

Abstract: The invention discloses a method for modifying a cycloidal gear, which comprises the following steps: establishing a standard tooth profile curve equation of the cycloidal gear; according to the principle of sectional modification and the change rule of pressure angle in cycloidal gear meshing process, the tooth profile section of cycloidal gear being determined; according to the backlash requirement of cycloidal pinwheel transmission, the curve equation of the angle modification and the tooth profile modification of the cycloidal pinwheel working section being determined; according to the working section tooth profile modification equation of cycloidal gear and the working section tooth profile interval, the end point parameters of the working section tooth profile being determined; according to the characteristics of grease lubricated meshing transmission and the requirement of oil content, the cubic fitting curve equation of the tooth root of non-working section of cycloidal gear being determined; according to the clearance requirement of cycloidal gear tooth top, the cubic fitting curve equation of non-working section tooth top of cycloidal gear being determined Thus, the curve equation of complete tooth profile of cycloidal gear overlapping small tooth modification can be determined, and the requirements of tooth tip clearance and tooth side clearance that cycloidal gearneedle wheel needs to meet can be realized