File Name: construction and details of spur gear .zip
An innovative approach to the design of the gear-tooth root-profile, and its effects on the service life is reported in this paper. Following the AGMA and ISO standards for fatigue loading, the von Mises stress at the critical section and stress distribution along the gear tooth root are studied. Spur gears are made of high-strength steel alloy 42CrMo4, the effects of its properties and surface treatment on service life improvement not being included in this study. This is a preview of subscription content, access via your institution. Rent this article via DeepDyve.
One of the fundamental s of gear design is the profile of the gear tooth. Gears generally have an involute curve tooth profile. This involute curve helps the gears transmit power smoothly during the rolling action. The curve is produced by wrapping a string around a cylinder, the base circle, and as it is unwrapped from this cylinder traces the involute curve. The base circle of the involute curve is also important because it helps to determine the pressure angle of the gear, another fundamental of gear design.
Spur gears are a type of cylindrical gear, with shafts that are parallel and coplanar, and teeth that are straight and oriented parallel to the shafts. The teeth of a spur gear have an involute profile and mesh one tooth at a time. The involute form means that spur gears only produce radial forces no axial forces , but the method of tooth meshing causes high stress on the gear teeth and high noise production. Because of this, spur gears are typically used for lower speed applications, although they can be used at almost any speed. An involute gear tooth has a profile that is the involute of a circle , which means that as two gears mesh, they contact at a single point where the involutes meet. This point moves along the tooth surfaces as the gears rotate, and the line of force known as the line of action is tangent to the two base circles.
Bevel gears are gears where the axes of the two shafts intersect and the tooth -bearing faces of the gears themselves are conically shaped. Bevel gears are most often mounted on shafts that are 90 degrees apart, but can be designed to work at other angles as well. Two important concepts in gearing are pitch surface and pitch angle. The pitch surface of a gear is the imaginary toothless surface that you would have by averaging out the peaks and valleys of the individual teeth. The pitch surface of an ordinary gear is the shape of a cylinder. The pitch angle of a gear is the angle between the face of the pitch surface and the axis. The most familiar kinds of bevel gears have pitch angles of less than 90 degrees and therefore are cone-shaped.
Description. In order to design, build and discuss gear drive systems it is necessary to understand the terminology and concepts associated with gear systems.
The gear ratio is the ratio of the number of teeth in the gear to the number of teeth in the pinion, the pinion being the smaller of the two gears in mesh. The pitch-circle diameters of a pair of gears are the diameters of cylinders co-axial with the gears which will roll together without slip. The pitch circles are imaginary friction discs, and they touch at the pitch point.
Gears have teeth that mesh with other gears in order to transmit torque. For gears to be compatible with each other, the meshing teeth must have the same shape size and pitch. Gears offer more flexibility in transforming motion than sprockets and chain because there are a larger variety of gear sizes available. There are many different types of gears; one of the simplest and most commonly used is a spur gear , and that is the gear type used in the REV 15mm Build System. Spur gears consist of a disk with straight teeth projecting radially outward from the center and these gears will only mesh correctly with other gears if they are on parallel shafts.
The gear teeth act like small levers. The axes may be parallel, intersecting, neither parallel nor intersecting. Here is a brief list of the common forms. We will discuss each in more detail later. Gears for connecting intersecting shafts Straight bevel gears Spiral bevel gears Neither parallel nor intersecting shafts Crossed-helical gears Hypoid gears Worm and wormgear 7.
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