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.

Cavity Design Method for Injection-Molded Spur Gears

Abstract: Mold cavities of gears should be made larger than the product specification since plastics shrink when changing from a molten to a solid state. For injection molded spur gears, two design methods for the compensation of shrinkage are widely used. One is the module correction method and the other is the pressure angle correction method. Both methods are based on the assumption that shrinkage occurs toward the center of a molded gear. This paper deals with the shrinkage rate and proposes a method of designing gear cavity derived from the measured shrinkage rates which govern the outside diameter, the tooth depth and the tooth thickness of a molded gear. The proposed method imposes no restriction on the shrinkage direction and provides a cavity with all of the fundamental gear design parameters.

Prediction Mathematic Model and Influencing Factors of Contact Stress of Cylindrical Gear with Arc Tooth

Abstract: Given the absence of a theoretical formula to analyze the influence of parameters on the contact stress of cylindrical gear with arc tooth, an explicit mathematical model of cylindrical gear with arc tooth between the design parameters and the contact stress is established based on Kriging surrogate model. The parameters of the variation function of Kriging model are optimized by using the whale optimization algorithm (WOA), and the explicit mathematical model accuracy between the design parameters and the contact stress of the gear is in turn optimized by the improved Kriging surrogate model. The influence of design parameters on the contact stress of cylindrical gear with arc tooth is analyzed based on the established mathematical model. The proposed algorithm was realized via the programming platform MATLAB; the simulation results indicate that the precision evaluation indexes (the correlation coefficient (R2), root mean square error (RMSE), and the relative maximum absolute error (RMAE)) of the proposed Kriging model are improved, in addition to the error range which is narrowed from (−2, 4) to (0, 3). As the tooth width, modulus, pressure angle, and tooth line radius increased, the contact stress of the cylindrical gear with arc tooth gear declined, which was negatively correlated with the design parameter. The amplitude of contact stress of the cylindrical gear with arc tooth was the largest due to the change of tooth radius, followed by the change of modulus, while the influence of tooth width was less. Finally, the influence of modulus-tooth line radius interaction and pressure angle-tooth line radius interaction on contact stress of cylindrical gear with arc tooth was significant.

Gear Crack Propagation Path Studies-- Guidelines Developed for Ultrasafe Design

Abstract: Effective gear designs balance strength, durability, reliability, size, weight, and cost. However, unexpected gear failures may occur even with adequate gear tooth design. To design an extremely safe system, the designer must ask and address the question "What happens when a failure occurs?" With regard to gear-tooth bending fatigue, tooth or rim fractures may occur. For aircraft, a crack that propagated through a rim would be catastrophic, leading to the disengagement of a rotor or propeller, the loss of an aircraft, and possible fatalities. This failure mode should be avoided. However, a crack that propagated through a tooth might or might not be catastrophic, depending on the design and operating conditions. Also, early warning of this failure mode might be possible because of advances in modern diagnostic systems. An analysis was performed at the NASA Glenn Research Center to develop design guidelines to prevent catastrophic rim fracture failure modes in the event of gear-tooth bending fatigue. The finite element method was used with principles of linear elastic fracture mechanics. Crack propagation paths were predicted for a variety of gear tooth and rim configurations. The effects of rim and web thicknesses, initial crack locations, and gear-tooth geometry factors such as diametral pitch, number of teeth, pitch radius, and tooth pressure angle were considered. Design maps of tooth and rim fracture modes, including the effects of gear geometry, applied load, crack size, and material properties were developed. The occurrence of rim fractures significantly increased as the backup ratio (rim thickness divided by tooth height) decreased. The occurrence of rim fractures also increased as the initial crack location was moved down the root of the tooth. Increased rim and web compliance increased the occurrence of rim fractures. For gears with constant-pitch radii, coarser-pitch teeth increased the occurrence of tooth fractures over rim fractures. Also, 25 degree pressure angle teeth increased the occurrence of tooth fractures over rim fractures in comparison to 20 pressure angle teeth. For gears with a constant number of teeth or for gears with constant diametral pitch, varying size had little or no effect on crack propagation paths.

Helical-spur gear in Padovan helical line gear shape

Abstract: The utility model discloses a helical-spur gear in a Padovan helical line gear shape. The gear shape of the end face, from a root circle to an addendum circle, of the helical-spur gear is the Padovan helical line gear shape, namely the section with the pressure angle a of 17 degrees to 28 degrees is the Padovan helical line. The gear center of the helical-spur gear is located at the position, where an angle theta is 0 degree, of the Padovan helical line. A pitch circle of the helical-spur gear passes through the position, where the angle theta is 40 degrees, of the section, where the gear center is located, of the Padovan helical line. The section, between the root circle and the addendum circle, of the Padovan helical line serves as the gear shape. The curvature radius of the gear shape is different along with the values of n, and the value of the curvature radius is Pn. Compared with an involute, the Padovan helical line has the advantage that the thickness of the gear root is increased. Due to the fact that the radius of the Padovan helical line gear shape is larger than that of an involute gear shape, the thickness of the gear root is increased, therefore, the bent fatigue intensity of the gear root is improved, and the service life of the helical-spur gear is prolonged under the high-speed heavy-load condition. The Padovan helical line gear shape can improve the overlap ratio through the limitation to the gear width, the continuous meshing condition of the helical-spur gear is ensured, meanwhile, the meshing contact area is increased, and the bearing capacity of the helical-spur gear is improved.

Correlation of Spray Cone Angle and Fuel Line Pressure in a Pressure-Swirl Injector Spray

Abstract: The transient cone angle of a pressure swirl spray from an injector for gasoline direct injection engines was measured from 2D Mie scattering images Iso-octane was used as the fluid that was delivered at room temperature for two different static pressures, 5MPa and 85MPa The iso-octane was injected into a chamber at room temperature and ambient pressure After a rapid initial increase, the cone angle oscillates before stabilizing to a steady-state value very close to the nominal cone angle The period of the oscillation was found to correlate well with oscillations measured in the fuel line pressure