Pressure angle

About: Pressure angle is a research topic. Over the lifetime, 1373 publications have been published within this topic receiving 10245 citations. The topic is also known as: angle of obliquity.

Contact angle hysteresis on smooth and homogenous surfaces in gravitational fields

Abstract: In an experiment conducted on a space shuttle flight, contact angle hysteresis was observed for the water-glass system. Surface heterogeneities have usually been taken as the cause of the observed hysteresis. In order to examine if other factors such as adsorption could be the cause of the observed hysteresis, contact angles on homogenous, smooth surfaces of glass were examined in ground-based experiments. Ten glass cylinders with different inside diameters were constructed with a capillary tube in the centre of each cylinder. The cylinders were filled with prepared water and the meniscus heights inside the capillary tube and in the glass cylinder were measured. Using the values of these parameters, the pressure in the vapour and the contact angle at the three-phase line of each interface were calculated from the equilibrium conditions. In each of the cylinders, a difference in the contact angle at the three-phase line of the capillary and the three-phase line of the cylinder was observed. This contact angle hysteresis cannot be explained by surface heterogeneity or line tension effect. The observed contact angle hysteresis is predicted to be the result of the pressure profile in the system. This suggests adsorption and its extraordinary sensitivity to vapour-phase pressure as the source of the contact angle hysteresis.

Experiment of vibration and response of blade with dry friction structure

Abstract: A testing system was set up to measure dynamic response of non-rotating shrouded blades.The loading scheme can achieve continuous adjustment and accurate measurement of contact pressure.The vibration characteristics and response of the shrouded blade with different mounting tightness and pressure angles were measured.The results show that the shrouded blade has nonlinear phenomena-the resonance frequencies are forficate.The effect of mounting tightness and pressure angle were analyzed according to the test data.The results indicate that the selection of pressure angle should be considered according to the proportional relations between relative motion to normal direction and tangential direction based on vibration mode.

Four-wheel locking system for a motor vehicle

Abstract: In the drive line of a motor vehicle, a planetary transmission is arranged as four-wheel locking system, a braking device acting upon the planet carrier of this planetary transmission. The planetary transmission includes an input sun gear, an output sun gear disposed coaxially next to it, and planet wheels mating simultaneously with both sun gears. In order to keep friction losses low and avoid a self-locking in the planetary transmission, the real pitch module of all gear wheels is as small as possible and proportional to the driving torque to be transmitted, and the operational pressure angle is as large as possible.

Design of Noncircular Gears to Minimise Shaft Accelerations

Abstract: This paper presents a novel pair of noncircular gear profiles for minimising shaft accelerations of the driven gear. The proposed profiles are developed based on an “exponential” function that is valid for a portion of gear rotation, and this function is extended to the remaining parts of the rotation of both gears. The exact shapes of the centrodes of the toothed bodies, which depend on a “smoothness” parameter, b, constitute a trade-off between the maximum shaft acceleration and the smoothness of the centrodes, so as to control the maximum tooth dynamic forces and stresses. A comparison between the derived noncircular gears and a gear pair that provides a sinusoidal variation of the angular velocity is presented. Results indicate that, for two-lobule gears, the maximum and minimum values of the polar radii, the velocity at the contact point, and the gear ratio are the same for both profiles. In contrast, there are significant differences in the angular acceleration of the driven gear, the tangential acceleration at the contact point, and the pressure angle, especially in the first one. It is concluded that the derived pair not only can provide low shaft accelerations, but also low tangential accelerations and small pressure angles.Copyright © 2006 by ASME

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.