Classification of gears
Gears can be classified according to tooth shape, gear shape, tooth line shape, the surface on which the gear teeth are located, and the manufacturing method.
The tooth profile of the gear includes tooth profile curve, pressure angle, tooth height, and displacement. Involute gears are easier to manufacture, so in modern gears, involute gears account for the absolute majority, while cycloid gears and arc gears are less used.
In terms of pressure angle, gears with small pressure angles have a smaller load-carrying capacity; gears with large pressure angles have a higher load-bearing capacity, but the load on the bearing increases under the same transmission torque, so it is only used in special cases. The tooth height of the gear has been standardized, and the standard tooth height is generally adopted. There are many advantages of displacement gears, which have been used in all kinds of mechanical equipment.
In addition, gears can be divided into cylindrical gears, bevel gears, non-circular gears, racks, and worm gears according to their shape; according to the shape of the tooth line, they can be divided into spur gears, helical gears, herringbone gears, and curved gears; The surface is divided into external gears and internal gears; according to the manufacturing method, it can be divided into cast gears, cut gears, rolled gears, and sintered gears.
The manufacturing material and heat treatment process of the gear has a great influence on the load-bearing capacity and size and weight of the gear. Before the 1950s, carbon steel was mostly used for gears, alloy steel was used in the 1960s, and surface hardened steel was used in the 1970s. According to hardness, tooth surface can be divided into two types: soft tooth surface and hard tooth surface.
Gears with soft tooth surfaces have low load-bearing capacity but are easier to manufacture and have good running-in performance. They are mostly used in general machinery with no strict restrictions on transmission size and weight and small-volume production. Because the small wheel has a heavier burden among the matched gears, in order to make the working life of the large and small gears roughly equal, the hardness of the tooth surface of the small wheel is generally higher than that of the large wheel.
Hardened gears have a high load-bearing capacity. They are quenched, surface quenched, or carburized and quenched after the gear is cut to increase the hardness. But in the heat treatment, the gear will inevitably produce deformation, so after the heat treatment, grinding, grinding or fine cutting must be carried out to eliminate the error caused by the deformation and improve the accuracy of the gear.
Material
The commonly used steels for making gears are quenched and tempered steel, quenched steel, carburized and quenched steel, and nitrided steel. The strength of cast steel is slightly lower than that of forged steel, and is often used for larger gears; gray cast iron has poor mechanical properties and can be used in light-load open-gear transmissions; ductile cast iron can partially replace steel to make gears; plastic gears are more commonly used In places where light load and low noise are required, the paired gears generally use steel gears with good thermal conductivity.
In the future, gears are developing in the direction of heavy load, high speed, high precision, and high efficiency, and strive to be small in size, light in weight, long life and economical, and reliable.
The development of gear theory and manufacturing technology will further study the mechanism of gear tooth damage, which is the basis for establishing a reliable strength calculation method, and the theoretical basis for improving the load-carrying capacity of gears and extending gear life; the development is represented by the arc tooth profile The new tooth profile; research new gear materials and new technology for manufacturing gears; research the elastic deformation of gears, manufacturing and installation errors, and the distribution of temperature fields, and modify the gear teeth to improve the smoothness of gear operation. When increasing the contact area of the gear teeth, so as to improve the bearing capacity of the gear.
Friction, lubrication theory, and lubrication technology are the basic work in the research of gears. Research on elastohydrodynamic lubrication theory, popularize the use of synthetic lubricating oil and appropriately add extreme pressure additives to the oil, which can not only improve the bearing capacity of the tooth surface but also It can also improve transmission efficiency.
Types
According to the transmission score:
Fixed transmission ratio-circular gear mechanism (cylindrical, cone)
Variable transmission ratio-non-circular gear mechanism (elliptical gear)
According to the relative position of the axle
Plane gear mechanism, spur gear transmission, external gear transmission, internal gear transmission, rack, and pinion transmission, helical cylindrical gear transmission, herringbone gear transmission, space gear mechanism, bevel gear transmission, cross-axis helical gear transmission, Worm gear drive
By process
Bevel gears, semi-finished gears, helical gears, internal gears, spur gears, worm gears
Luoyang Yujie Industry &Trade Co.Ltd located in Luoyang City, one of the main heavy industrial bases in China. We specialize in the production of bearings, nonstandard machinery parts, machine tools. For the bearings, we can offer cross roller bearing, slewing bearing, YRT bearing, thin section bearing, ball screw bearing, deep groove ball bearing, etc. For the nonstandard machine parts, we can produce gears, shafts, sprockets, molds, rollers, pulley, mining machine parts, etc as per customer drawing and requirements. For the machine tools, we offer CNC vertical machine center, CNC horizontal lathe, CNC gantry boring and milling machine, CNC floor type boring, and milling machine.
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