Material selection and gear structure analysis for gear machining

The commonly used gear materials include tempered steel, quenched steel, carburized quenched steel and nitriding steel. The strength of cast steel is slightly lower than that of forged steel, which is often used for larger gears; Gray cast iron has poor mechanical properties and can be used in open gear transmission with light load. Ductile iron can partially replace steel in gear manufacturing; Plastic gears are mostly used for light load and low noise requirements, and their paired gears are generally steel gears with good thermal conductivity. After years of development in the gear industry, the future gear is approaching the direction of heavy load, high speed, high precision and high efficiency, and the size, weight, service life and cost performance of gear products put forward higher requirements.

Pinion and rack generally include tooth, tooth groove, end face, normal face, tooth top circle, tooth root circle, base circle, degree circle. A gear tooth, abbreviated as a tooth, is each convex part of a gear used for meshing. These convex parts are usually arranged in a radial shape. The teeth of the paired gear contact each other to keep the gear engaged. A groove is the space between two adjacent teeth on a gear; The end face is a cylindrical gear or cylindrical worm, perpendicular to the gear or worm axis plane. The end face is the plane of both ends of the gear, and the normal face refers to the plane perpendicular to the tooth line of the gear. The apex circle refers to the circle where the top of the tooth is located, and the root circle refers to the circle where the bottom of the groove is located. The base circle forms the involute line as the pure rolling circle, and the indexing circle is the reference circle in the end face to calculate the geometric dimension of the gear.

Nowadays, the manufacturing process of many gear factories has been developed to further study the mechanism of tooth damage, which is the basis for establishing a reliable strength calculation method, and is the theoretical basis for improving the bearing capacity of gear and prolonging the life of gear. The development of gear is represented by the new tooth shape of circular arc tooth profile. Research new gear materials and new gear manufacturing technology; The elastic deformation, manufacturing and installation errors and the distribution of temperature field of the gear were studied, and the gear teeth were modified to improve the stability of the gear operation, and the contact area of the gear teeth was increased when the gear was fully loaded, so as to improve the bearing capacity of the gear. Friction, lubrication theory and lubrication technology are the basic work in the research of gear. Studying the theory of elastohydrodynamic lubrication, popularizing synthetic lubricating oil and appropriately adding extreme pressure additives to the oil can not only improve the bearing capacity of tooth surface, but also improve the transmission efficiency.