Showing papers on "Pressure angle published in 2013"

Effect of geometric parameters on the spray cone angle in the pressure swirl injector

Abstract: Spray cone angle affects the droplet distribution after atomization and is one of the main targets of coaxial gas–liquid injector optimization. Experimental measurements and numerical modeling (vol...

Dynamic synthesis of the rotary cam and translated tappet with roll

Abstract: This paper presents an original method to determine the dynamic parameters at the camshaft (the distribution mechanisms). The authors introduce a new pressure angle, alpha, and a new method to determine the two pressure angles, alpha and delta, at the rotary cam and tappet with translational motion with roll, with a great precision. We determine initially the mass moment of inertia (mechanical) of the mechanism, reduced to the element of rotation, ie at cam (basically using kinetic energy conservation). The rotary cam with translated follower with roll is synthesized geometric, kinematics and dynamic.

Modeling and Analysis of the Meshing Losses of Involute Spur Gears in High-Speed and High-Load Conditions

Abstract: A first-principle based mathematical model is developed in this paper to analyze the meshing losses in involute spur gears operating in high-load and high-speed conditions. The model is fundamentally simple with a few clearly defined physical parameters. It is computationally robust and produces meaningful trends and relative magnitudes of the meshing losses with respect to the variations of key gear and lubricant parameters. The model is evaluated with precision experimental data. It is then used to study the effects of various gear and lubricant parameters on the meshing losses including gear module, pressure angle, tooth addendum height, thermal conductivity, and lubricant pressureviscosity and temperature-viscosity coefficients. The results and analysis suggest that gear module, pressure angle, and lubricant pressure-viscosity and temperature-viscosity coefficients can significantly affect the meshing losses. They should be the design parameters of interest to further improve the energy efficiency in high-performance, multistage transmission systems. Although the model is developed and results obtained for spur gears, the authors believe that the trends and relative magnitudes of the meshing losses with respect to the variations of the gear and lubricant parameters are still meaningful for helical gears. [DOI: 10.1115/1.4007809]

Investigation on the Effort Transmission in Planar Parallel Manipulators

Abstract: In the design of a mechanism, the quality of effort transmission is a key issue. Traditionally, the effort transmissivity of a mechanism is defined as the quantitative measure of the power flowing effectiveness from the input link(s) to the output link(s). Many researchers have focused their work on the study of the effort transmission in mechanisms and diverse indices have been defined. However, the developed indices have exclusively dealt with the studies of the ratio between the input and output powers and they do not seem to have been devoted to the studies of the admissible reactions in passive joints. However, the observations show that is possible for a mechanism to reach positions in which the transmission indices will have admissible values but the reaction(s) in passive joint(s) can reach excessively high values leading to the breakdown of the mechanism. In the present paper, a method is developed to ensure the admissible values of reactions in passive joints of planar parallel manipulators. It is shown that the increase of reactions in passive joints of a planar parallel manipulator depends not only on the transmission angle but also the position of the instantaneous centre of rotation of the platform. It allows the determination of the maximal reachable workspace of planar parallel manipulators taking into account the admissible reactions in its passive joints. The suggested method is illustrated vie a 5R planar parallel mechanism and a planar 3-RPR parallel manipulator. I Introduction Parallel manipulators have many advantages in terms of acceleration capacities and payload-to-weight ratio [1], but one of their main drawbacks concerns the presence of singularities [2]-[5]. It is known that in the neighbourhood of the singular positions the reactions in joints of a manipulator considerably grow up. In order to have a better understanding of this phenomenon, many researchers have focused their works on the analysis of the effort transmission in parallel manipulators. One of the evident criterions for evaluation of effort transmission is the transmission angle (or pressure angle which is equal to 90 degrees minus the transmission angle) [7]-[9]. The pressure angle is well known for characterizing the transmission quality in lower kinematic pairs, such as cams [10], but this idea was also used for effort transmission analysis in the parallel manipulators [7], [9]. To evaluate the effort transmission quality, several indexes have been introduced. One of the first attempts was proposed in [6]. This paper presents a criterion named the Transmission Index (TI) that is based on transmission wrench screw. The TI varies between 0 and 1. If it is equal to 0, the considered link is in a dead position, i.e. it cannot move anymore. If it is equal to 1, this link has the best static properties. In the same vein as [6], the study [11] generalizes the TI for spatial linkages and defines the Global TI (GTI). The authors also prove that the GTI is equal, for prismatic and revolute joints, to the cosine of the pressure angle. The conditioning index was also proposed [12] for characterizing the quality of transmission between the actuators and the end-effector. This index is based on the Jacobian matrix or its "norm", which relate the actuator velocities (efforts, resp.) to the platform twist (wrench, resp.) by the following relations:  t Jq  and T   w J τ , where J is the Jacobian matrix, t the platform twist, q  the input velocities,  the actuator efforts, and w the wrench applied on the platform. All these indices have been used in many works for design and analysis of parallel mechanisms [14]-[21]. However, it is also known that because of the non homogeneity of the terms of the Jacobian matrix, the conditioning index is not well appropriated for mechanisms having both translational and rotational degrees of freedom (DOF) [13]. Moreover, all the previously mentioned indices do not take into account the real characteristics of the actuators, i.e. the fact that their input efforts are bounded between [-max i  , max i  ] [13]. In order to solve this problem, in study [22] a numerical analysis method has been developed. It has been proposed to characterize the force workspace of robots taking into account a given fixed wrench applied on the platform and actuator efforts comprised in the boundary interval [-max i  , max i  ]. However, this workspace depends on the given direction and norm of the external force/moment and will change with the variation of the applied wrench. Moreover, for many robot applications, the external wrench direction is not known, contrary to its norm. Therefore, in [23], a way to compute the maximal workspace

Flow simulation of the effects of pressure angle to lobe pump rotor meshing characteristics

Abstract: Lobe pump rotor profiles' radius of base circle, addendum circle and root circle are closely connected with pressure angle. The change of pressure angle has some effect on lobe pump performance. This paper focuses on two-dimensional profile lobe pump and introduces involute rotor profiles and pressure angle parameter equation. We used geometry and two rotor mesh characteristics to establish lobe pump models of different pressure angles. Monitored the lobe pump's pressure and velocity of input and output cross section. We used the K-Epsilon turbulence model and the dynamic meshes to compute the two-dimensional turbulence flow field of the lobe pump and obtained the pressure and velocity pulsation picture of different models and speeds. The results show with increasing pressure angle, the velocity of output decreases. The fluctuation of velocity is kept almost constant. When the pressure angle is 45°, the lobe pump has good comprehensive properties. The increasing of rotor speed makes the output flow and the oil absorption pressure increase. But the pressure fluctuation is acute. The lobe pump has vortex and leakage phenomenon in work progress. It will cause energy losses and decrease efficiency.

Analytical and Experimental Investigation of Parameters Affecting Sliding Loss in a Spur Gear Pair

Abstract: The effects of gear module, pressure angle and gear ratio on the sliding losses of a spur gear pair have been investigated analytically and experimentally in this paper. The analytical investigations were done by using the gear meshing model proposed in the authors' former work. The various empirical formulas of friction coefficient are used in the calculation process. The estimated results are compared with the experimental results done by using back-to-back gear test rig. The analytical results agree well with the experimental results. The sliding losses of gears having larger module are higher than the gears having smaller module. The larger pressure angle gears have lower sliding losses, and increasing the gear ratio causes the increase in sliding loss. The estimated results calculated by using the friction coefficient formula proposed by ISO TC60 are the most accurate comparing with the experimental results.

Static and Dynamic Characteristics of the Chain Drive System of a Heavy Duty Apron Feeder

Abstract: Mechanical models of a chain drive system are proposed and applied to the theoretical analysis of chain drive system of a certain type of heavy duty apron feeder in mobile crushing station, including a five-bar model discussing the speed fluctuation problems of the chain drive system, an elastic collision model probing the effects of impulsive loads and a model of meshing area revealing the stress of chain links. Theoretical analysis indicates that the teeth number and sprocket pitch have the most influential effect on the vibration in the conveying direction; external impulsive loads are caused a significant increment of chain force, especially when loads caused by large materials; the initial pressure angle affects the roller chain stress conditions immensely. Then, multi-body dynamics models are established for the verification of theoretical results and dynamic simulation. Simulation results are in good agreement with the theoretical results and illustrate that impulsive loads affect chain tension significantly.

Analytical Expressions of the Efficiency of Standard and High Contact Ratio Involute Spur Gears

Abstract: Simple, traditional methods for computation of the efficiency of spur gears are based on the hypotheses of constant friction coefficient and uniform load sharing along the path of contact. However, none of them is accurate. The friction coefficient is variable along the path of contact, though average values can be often considered for preliminary calculations. Nevertheless, the nonuniform load sharing produced by the changing rigidity of the pair of teeth has significant influence on the friction losses, due to the different relative sliding at any contact point. In previous works, the authors obtained a nonuniform model of load distribution based on the minimum elastic potential criterion, which was applied to compute the efficiency of standard gears. In this work, this model of load sharing is applied to study the efficiency of both standard and high contact ratio involute spur gears (with contact ratio between 1 and 2 and greater than 2, resp.). Approximate expressions for the friction power losses and for the efficiency are presented assuming the friction coefficient to be constant along the path of contact. A study of the influence of some transmission parameters (as the gear ratio, pressure angle, etc.) on the efficiency is also presented.

Explicit Parametric Method for Optimal Spur Gear Tooth Profile Definition

Abstract: The gear tooth profile has an immense effect on the main operating parameters of gear pairs (load capacity, working life, efficiency, vibrations, etc). In current engineering research and practice, there is a strong need to develop methods for tooth profile optimization. In this paper a new method for selecting the optimal tooth profile parameters of spur gears is described. This method has been named the Explicit Parametric Method (EPM). The addendum modification coefficient, radius of root curvature, and pressure angle of the basic rack for cylindrical gears, have been identified as the main tooth profile parameters of spur gears. Therefore, the EPM selects the optimal values for these three tooth profile parameters. Special attention has been paid to develop a method of adjustment for the particular working conditions and explicit optimization requirements. The EPM for optimal tooth profile parameters of gears uses contact nonlinear Finite Element Analysis (FEA) for calculation of deformations and stresses of gear pairs, in addition to explicit comparative diagrams for optimal tooth profile parameter selection.

Prediction of load sharing based HCR spur gear stresses and critical loading points using artificial neural networks

Abstract: The prediction of the load shared by a pair of teeth, maximum contact and fillet stresses and the respective location of the critical loading point becomes rather a difficult task in High Contact Ratio HCR gears as the contact ratio exceeds two. As this prediction greatly depends on the gear parameters like pressure angle, addendum factor and teeth number, an attempt has been made to work on this area highlighting these aspects using Finite Element FE Multi Pair Contact Model MPCM. The minimum value of contact ratio under consideration is 2.1. However, the maximum is chosen as 2.9. A new methodology based on Artificial Neural Networks ANNs is proposed for the prediction of Load-Sharing Ratio LSR, maximum fillet and contact stresses and the respective critical loading points. The data set generated from the MPCM has been used to train the networks and, furthermore, its effectiveness is proved by a different data set of HCR gear pairs determined for the randomly selected parameters.

Forming and generating gear milling machine

Abstract: The utility model discloses a forming and generating gear milling machine and a machining method. The forming and generating gear milling machine comprises a machine seat, wherein a rotating table used for supporting a workpiece is arranged on the machine seat, an X-axis sliding seat is installed on the machine seat through a sliding rail, a Y-axis sliding seat is installed on the X-axis sliding seat through a sliding seat, a Z-axis sliding seat is installed on the Y-axis sliding seat through a sliding rail, and a cutter assembly is installed on the Z-axis sliding seat. The machining method with the forming and generating gear milling machine includes the following steps that a cutter rotates to carry out cutting motion on a workpiece at first, then most of metal removal is removed through a forming machining state, and axial motion, driven by the Z-axis sliding seat, of the cutter and rotation of the workpiece finish generating machining of a single tooth groove together at last. Through application of the forming and generating gear milling machine and the machining method, the cutter with good generality than that of a generating machining cutter can be applied, and a constraint condition of an existing generating cutter module is removed from two necessary conditions including the existing generating cutter module and an existing pressure angle. Under the condition that the pressure angles are equal, the same cutter can machine gears with different cutter modules.

Generation Simulation and Grinding Experiment of Face-Gear Based on Single Index Generating Method

Abstract: A mathmatical model of generating face-gear by grinding disk is developed. The influence of all kinds of errors of alignment and profile on face-gear flank deviation is considered and investigated in this model, such as offset error and pressure angle error of grinding disk, location error of virtual pinion axis. A optimization method for decreasing flank deviation is proposed. The corresponding correction parameters of machine which can be used for manufacturing face gear can be computed by this optimization method. In this method, the square sum of tooth surface deviation is taken to be the objective function. A grinding experiment of face-gear is performed on a CNC grinding machine with five degrees of freedom, and the tooth flank deviation is measured on gear measuring center. The flank deviation is very large due to some alignment errors in the beginning. When the grinding machine is adjusted by optimization computation results mentioned above, the measurement results show that the deviation of grinded face-gear flank is reduced substantially. The benefit is to improve the grinding quality of face-gear by this method.Copyright © 2013 by ASME

Asymmetrical gear hob for processing intersecting axes variable thickness gear

Abstract: The utility model relates to the machining field, in particular to an asymmetrical gear hob for processing an intersecting axes variable thickness gear so as to provide the asymmetrical gear hob which enables a left pressure angle and a right pressure angle of the variable thickness gear to be unequal Asymmetrical degrees of the variable thickness gear can be improved and errors of gear forms can be reduced by using the cutter to process the variable thickness gear The asymmetrical gear hob for processing intersecting axes variable thickness gear comprises nine teeth, included angle of each tooth are 40 degrees According to the asymmetrical gear hob for processing intersecting axes variable thickness gear, the gear hob further comprises nine chip pockets which are nine straight flutes parallel to a hob axis According to the asymmetrical gear hob for processing intersecting axes variable thickness gear, actual pressure angles of the variable thickness gears can be controlled and modified by changing of a left gear form angle and a right gear form angle of the gear hob and errors of tooth forms can be reduced, and thereby stability of gear transmission can be greatly improved and the asymmetrical gear hob for processing intersecting axes variable thickness gear has certain practical values

The use of geometric uncertainty data in aero engine structural analysis and design

Abstract: A gas turbine disc has three critical regions for which lifing calculations are essential: the assembly holes or weld areas, the hub region, and the blade-disc attachment area. Typically, a firtree joint is used to attach the blades to the turbine disc instead of a dove-tail joint, which is commonly used for compressor discs. A firtree joint involves contact between two surfaces at more than one location which makes the joint more difficult to design. Large loads generated due to the centrifugal action of the disc and associated blades are distributed over multiple areas of contact within the joint. All of the contacts in a firtree joint are required to be engaged simultaneously when the blades are loaded. However, slight variations in the manufacture of these components can have an impact on this loading. It is observed that small changes in the geometric entities representing contact between the two bodies can result in variations in the stress distribution near contact edges and the notch regions. Even though manufacturing processes have advanced considerably in the last few decades, the variations in geometry due to these processes cannot be completely eliminated. Hence, it is necessary to design such components in the presence of uncertainties in order to minimise the variation observed in their performance. In this work, the variations in geometry due to the manufacturing processes used to produce firtree joints between a gas turbine blade and the disc are evaluated. These variations are represented in two different ways using measurement data of firtree joints obtained from a coordinate measuring machine (CMM): (i) the variation for the pressure angle in the firtree joint is extracted from a simple curve fit and (ii) using the same measurement data, the unevenness of the pressure surfaces is represented using a Fourier series after filtering noise components. A parametric computer aided design (CAD) model which represents the manufacturing variability is implemented using Siemens NX. Non-smooth surfaces are also numerically generated by assuming the surface profile to be a random process. Two- and three-dimensional elastic stress analysis is carried out on the firtree joint using the finite element code, Abaqus and the variations observed in the notch stresses with changing pressure angle are extracted. A surrogate assisted multiobjective optimisation is performed on the firtree joint based on the robustness principles. Kriging based models are used to build a surrogate for notch stresses and the non-dominated sorting genetic algorithm-II (NSGA-II) is implemented to perform a multiobjective optimisation in order to minimise the mean and standard deviation of the notch stresses. An iterative search algorithm that updates the Kriging models with equally spaced infill points from the predicted Pareto front is adopted. Finally, a new design of the firtree joint is obtained which has better performance with respect to the variation in the notch stresses due to manufacturing uncertainties.

Forming and generating gear milling machine and processing method

Abstract: The invention discloses a forming and generating gear milling machine and a processing method. The forming and generating gear milling machine comprises an engine base, wherein the engine base is provided with a rotary workbench used for supporting a workpiece; the engine base is also provided with an X-direction sliding seat by a sliding rail; the X-direction sliding seat is provided with a Y-direction sliding seat by a sliding rail; the Y-direction sliding seat is provided with a Z-direction sliding seat by a sliding rail; and a cutter assembly is installed on the Z-direction sliding seat. The processing method for milling a gear by the equipment comprises the following steps: a cutter rotates to form cutting movement to the workpiece; in the forming processing state, after most metal removal amount is removed, the Z-direction sliding seat drives the cutter to axially move; and the generating processing of a single-tooth groove is jointly finished by the axial movement of the cutter and the rotation of the workpiece. According to the equipment and the method, the cutter with a better generality than generating processing can be used, and a constraint condition of modulus is omitted in two items of necessary conditions of the original generating cutter, i.e. modulus and a pressure angle. Under the condition of the same pressure angle, the same cutter can be used for processing gears of different modulus.

Considerations regarding a new manufacturing technology of cylindrical worms using nc lathe

Abstract: This paper presents aspects of a new manufacturing technology cylindrical Archimedean worms on NC lathes using standard frontal – cylindrical milling tools. The frontal-cylindrical milling tools is tilted from the perpendicular to the axis of symmetry of the worm by an angle roughly equal with the pressure angle of the worm flank. At the same time the symmetry axis of frontal-cylindrical milling tools is contained in a plane parallel to the axis of symmetry of the worm. The plane is positioned for the symmetry axis at a distance that we call eccentricity. Depending on the location of the milling tool, shall be determined the shape of the profile resulted in axial plane to be able to be compared to the nominal profile of an Archimedean worm. The profile shape is determined using coordinate transformations. The program that generates the necessary points is AutoLISP and representations are made in AutoCAD.

Optimal Design of Slider-crank Mechanism Based on Creo Parametric

Abstract: In Creo Parametric,the skeleton model of offset slider-crank mechanism was created and the motion was analyzed.The length of the crank and connecting rod were optimal designed based on the function of Creo Parametric behavior modeling with length of crank and minimum pressure angle as a constrain.The method is simple,practical and has great promotion value.The purpose was to provide a new train of thought for design of slider-crank mechanism.

Asymmetric involute worm and helical gear pair

Abstract: The utility model discloses an asymmetric involute worm and helical gear pair. The asymmetric involute worm and helical gear pair comprises a worm and a helical gear, wherein a worm meshing side tooth profile and a worm non-meshing side tooth profile are arranged on the two sides of each gear tooth of the worm respectively, a helical gear meshing side tooth profile and a helical gear non-meshing side tooth profile are arranged on the two sides of each gear tooth of the helical gear respectively, the axial module of the worm is m1, the transverse module of the helical gear is m2, the pressure angle of each worm meshing side tooth profile is alpha1, the pressure angle of each worm non-meshing side tooth profile is alpha2, the pressure angle of each helical gear meshing side tooth profile is alpha3, the pressure angle of each helical gear non-meshing side tooth profile is alpha4, the addendum coefficient of each worm meshing side tooth profile is , the addendum coefficient of each worm non-meshing side tooth profile is , the tip clearance coefficient of each worm meshing side tooth profile is , and the tip clearance coefficient of each worm non-meshing side tooth profile is . When the included angle sigma between the axis of the worm and the axis of the helical gear is 90 degrees, in order to ensure correct meshing between the worm and the helical gear, the following conditions that the alpha1 is larger than the alpha2, and the alpha3 is larger than the alpha4; when the m1 is equal to the m2, the alpha1 is equal to the alpha3, and the alpha2 is equal to the alpha4; when the m1 is not equal to the m2, m1*cosalpha1=m2*cosalpha3, m1*cosalpha2=m2*cosalpha4 and the like need to be met.

On the Behaviour of Asymmetric Cylindrical Gears in Gear Transmissions

Abstract: Asymmetric gears have been proposed more than twenty years ago as the ultimate solution to increase the load capacity of gear drives while reducing their weight and dimensions. However, there are apparently contradictive statements in the literature regarding whether the higher pressure angle should be applied to the driving or coast side of the gear tooth surfaces. In this work, modern technologies of design and analysis of enhanced gear drives will be applied in order to validate the advantages of application of asymmetric gears and to determine what the right configuration of the asymmetric gear drive should be in terms of application of the higher pressure angle to the driving or coast side of the gear teeth. The evolution of contact and bending stresses as well as contact pressure for the whole cycle of meshing is investigated and compared for symmetric and asymmetric gears. Two configurations of asymmetric gears will be considered, taking into account both, the higher and the lower pressure angle for the driving side. In this way, the advantages of application of asymmetric cylindrical gears as well as the right configuration to get them are established.

Influence of Pressure Angle on Load Sharing Based Stresses in Asymmetric Normal Contact Ratio Spur Gear Drives

Abstract: The aim of this paper is to investigate the influence of pressure angle on drive and coast sides in conventional design asymmetric normal contact ratio spur gear, considering the load sharing between the gear teeth pair. The multi pair contact model in finite element analysis is used to find the load sharing ratio and respective stresses. It has been found out that the predictions through multipoint contact model are in good agreement with the available literature. A unique Ansys parametric design language code is developed for this study. It is found that, the maximum fillet stress decreases up to the threshold point for drive side (35o) and coast side (25o) pressure angles, beyond this point it increases. The load share based maximum fillet and contact stresses are lower in the high pressure angle side than that of the low pressure angle side, when it is loaded at the critical loading points.

Factor affecting the bending stress at critical section of asymmetric spur gear

Abstract: The main objective of this review paper is to show how the different parameters are affecting the bending stress at critical section of asymmetric spur gear. Bending stress at critical section is most important parameter in gear design. It must be low as low possible. Our try to minimize it by optimize all affected Parameters of asymmetric spur gear tooth to reduce Bending Stress at critical section of tooth. This reduction can translate into Increased Load Capacity, Size and Weight Reduction, Longer Life, Cost Reduction, Increased Reliability, Noise and Vibration reduction, Increased Gear Efficiency and Maintenance Cost Reduction etc. As the pressure angle on drive side increases, the bending stress reduces at critical section of asymmetric spur gear. But Decision on maximum magnitude of drive side pressure angle is constraint by the safe contact ratio and tooth peaking effect. These way parameters are affecting directly or indirectly on performance. There are so many parameters are likes Contact ratio, Top land tip thickness, Pressure angle on drive side profile, Pressure angle on coast side profile, Asymmetry factor, No. of teeth, Interference, Undercut, Centre distance, Gear ratio, Critical section thickness, Profile shift of pinion, Profile shift of gear, Module, Bending stress at critical section, Optimal fillet radius and Balance stress etc. affects the performance. So, it is necessarily to optimize these affected Parameters of asymmetric spur gear tooth to reduce Bending Stress at critical section of tooth.

Asymmetric involute worm and bevel gear pair

Abstract: The invention discloses an asymmetric involute worm and bevel gear pair The asymmetric involute worm and bevel gear pair comprises a worm and a bevel gear, the two sides of gear teeth of the worm are provided with a worm mesh side tooth profile and a worm non-mesh side tooth profile respectively, and the two sides of gear teeth of the bevel gear are provided with a bevel gear mesh side tooth profile and a bevel gear non-mesh side tooth profile respectively, wherein the axial modulus of the worm is m1, the end face modulus of the bevel gear is m2, the pressure angle of the worm mesh side tooth profile is alpha1, the pressure angle of the worm non-mesh side tooth profile is alpha2, the pressure angle of the bevel gear mesh side tooth profile is alpha3, the pressure angle of the bevel gear non-mesh side tooth profile is alpha4, and the following conditions are met: a, alpha1>alpha2, and alpha3>alpha4; b, when m1=m2, alpha1=alpha3, and alpha2=alpha4; when m1 is not equal to m2, m1cosalpha1=m2cosalpha3, and m1cosaplha2= m2cosalpha4 According to the asymmetric involute worm and bevel gear pair, tooth root fracture of the bevel gear can be effectively avoided, and the shock resistance and the bearing capacity of the asymmetric involute worm and bevel gear pair in transmission are improved

Investigation of Local Flow Parameters Caused by Flow Acceleration Corrosion Downstream of an Orifice in a Piping System

Abstract: In this study, the performance of an impeller according to blade length and pitch angle was studied experimentally by building a variable pitch impeller while changing blade length to review the effect of blade length and pitch angle on a fan`s performance. The pitch angle was changed in six steps from at intervals of while the blade lengths were changed to 90 mm, 100 mm, 110 mm and 120 mm with an identical airfoil shape while carrying out the experiment. The results are summarized as follows : The air flow per static pressure of axial fans increased linearly with increase of pitch angle, but the high static pressure showed a decrease at a pitch angle of . The shaft power increased proportionally to the pitch angle at all blade lengths; the larger the pitch angle, the larger the measured increase of shaft power. This is because the drag at the fan`s front increases with the pitch angle. In the axial fans considered in this research, the flow and incre.

Toothed-Lobed Gear Pump

Abstract: Toothed gears and lobed gears intermesh to create large volume pockets in gear sets of a given size. The pockets are larger than the pockets that exist in current tooth or lobe pumps and provide the benefit of a pump that better handles shear sensitive liquids. Preferably, the profiles of the teeth and of the lobes are involute-shaped to provide rolling contact and a fixed pressure angle between the teeth and lobes during engagement. The toothed gears and lobe gears improve upon standard spur and helical gear designs by omitting alternate teeth on the standard toothed gears and filling in corresponding gaps on the mating standard lobed gears. Additional tooth and lobed gear rotors may be added in tandem as additional pairs of gears to the shafts and circumferentially offset to provide driving tooth engagement between at least one pair of the toothed and lobed rotors at every point around the rotational circumference of the rotors. This spur gear or helical gear configuration eliminates the need for separate driving/synchronizing gears.

Study on Minimum Teeth without Undercutting of Involute Gears with 14.5 Degree Pressure Angle

Abstract: Study on minimum teeth without undercutting for considering the rack cutter’s addendum c*m of a kind of gear with 14.5 degree pressure angle, and the gear standard No is B436-1940 and used in UK. Based on the generating method, reasons for undercut phenomena is analyzed, and the numbers of minimum teeth without undercutting of the involute spur gear, involute helical cylindrical gear and involute spur bevel gear are theoretically analyzed and figured out. The correct number of minimum teeth without undercutting of gear with 14.5 degree pressure angle is given, and also illustrated the validity of theoretical derivation.

Gear pump bearing dam

Abstract: A gear pump includes gears (114, 116) having a gear root diameter (135, 137) and teeth (134, 136) having an addendum and pressure angle. A housing (102) includes a fluid inlet and discharge, bearings (104, 106) configured to position the gear teeth in intermeshing contact across a fluid dam (158). The fluid dam includes a first face (161) arranged at an angle to a split line (152), spaced apart from a center line (150) at the split line a first distance towards the inlet, and extending from the first gear root diameter away from the center line to the first gear root diameter, and a second face (181) arranged approximately perpendicular to the split line (152), spaced apart from the center line at the split line a second distance towards the outlet, and extending between the first gear root diameter and the second gear root diameter.

Technological solution to profile and generate the teeth of central gear for precessional gear drives

Abstract: The transmission based on precessional gear pairs, mostly used for rotation speed reduction, has some important advantages relative to the common gear drives, such as the capability to produce very low transmission ratios, or the high loading capacity/dimensions ratio (due to the fact that all the teeth of a precessional gear pair are simultaneously in contact during its functioning). One among the likeliest constructive solutions for the precessional gear pair uses a satellite built with conical rollers. However, its practical use is restricted by the difficulty to realize the central gear teeth machining without using special and relative complicated devices. This paper introduces a technological substitutive profile for the central gear tooth, which enables the use of a simpler and more productive method for working it, without bringing major negative consequences regarding the teeth contact correctness or the drive loading capacity. The profile was found by analyzing the contact surface and the pressure angle evolution during the contact between conjugate teeth. The paper also presents technological solutions to generate the new tooth profile by milling it with a disk-tool or an end-mill cutter, together with methods to profile the required tools.

Double-contact hobbing cutter

Abstract: The utility model relates to a double-contact hobbing cutter which is characterized in that tip circle radius of a tooth of the hobbing cutter is 0-0.3 times of modulus, a standard pressure angle with an angle of 15 degrees-30 degrees is arranged on a tooth face 0.3-0.8 times of tooth height down from a tooth tip, a cutting-off-interference-quantity pressure angle with an angle of 22 degrees-37 degrees is arranged on a tooth face 0.05-0.6 times of tooth height down from the standard pressure angle, and a tooth tip chamfering pressure angle alpha 3 with an angle of 25 degrees-50 degrees is arranged on a tooth face 0.05-0.3 times of tooth height down from the cutting-off-interference-quantity pressure angle. The double-contact hobbing cutter is simple in structure, easy to manufacture, low in cost, convenient and fast in cutter assembly and disassembly, simple in procedure and short in machining time, is used for machining a double-contact gear, can accurately provide cutting off interference quantity and uproot quantity for fine machining of the gear, ensures smooth connection of an involute part and a transition curve part, improves machining accuracy of the double-contact gear, reduces machining cost, and improves machining efficiency.