A closed helical gear drive driven by an electric motor is designed. Always transfer power of p=22kw, n1=730r/min, i=3.8 ratio, gear precision grade is 8, the gear on the shaft relative to the bearing not symmetrically, but the shaft just wake up large, stable load, one-way transmission, double shift work.Would you like to ask how the material is chosen?
(soft tooth surface hardness is less than or equal to 350HBS): Forged Steel by gears after heat treatment is used for the strength, speed and accuracy requirements of the gear should be used for cutting, and the cutting tool to quickly wear blunt. Therefore, the gear blank should be cut by normalizing (normalizing) or quenching and tempering. After cutting, it is finished product. Its accuracy is generally 8, and the fine cutting can reach 7 levels. The gears are easy to manufacture, economical and efficient.Hardened (hardness > 350HBS): used for finishing gear forging steel high speed and heavy load and precision machinery (such as precision machine tool, aero engine) main gear transmission used, in addition to excellent material properties, high strength and gear tooth surface with high hardness (58 ~ 65HRC). Should also be finishing grinding etc.. Need to finish the gear is mostly cutting teeth, and then do surface hardening treatment, and finally finishing, the accuracy can reach 5 or 4. This kind of gear has high precision and expensive price, so the heat treatment methods include surface hardening, carburizing, nitriding, soft nitriding and cyaniding. Therefore, the material depends on the specific requirements and heat treatment methods.
Gear materials and their selection principlesThe form of gear failure shows that the design of gear transmission should make the tooth surface have higher wear resistance, pitting resistance, anti scuffing and plastic deformation resistance, and the tooth root should have higher resistance to break. Therefore, the basic requirements of gear material performance are: the tooth surface should be hard and the tooth core should be tough.
According to the composition and properties of alloy steel containing metal, can be made of material toughness, impact resistance, abrasion resistance and anti scuffing properties can also be improved, by heat treatment or chemical heat treatment improved the mechanical properties of the materials and improve the hardness of tooth surface. Therefore, for both high-speed, heavy load and require small size, small quality aviation gears, they are using good performance alloy steel (such as 20CrMnTi, 20Cr2Ni4A, etc.) to make.(2) cast steelCast steel has good abrasion resistance and strength, but should be treated by annealing and normalizing, and can be quenched and tempered when necessary. Cast steel is often used for larger gears.2. cast ironGray cast iron has the properties of brittleness, shock resistance and wear resistance, but its ability of anti scuffing and pitting resistance is better. Gray cast iron gears are often used in stable, low speed and low power conditions.
(1) gear material used in common use;1. steelThe steel has good toughness, impact resistance, and can also improve mechanical properties and improve the hardness of the teeth by heat treatment or chemical heat treatment, so it is most suitable for making gears.(1) forged steelIn addition to the size is too large, or the structure of complex shapes, only cast, but generally forged steel gear, commonly used in the carbon content of (0.15 ~ 0.6)% of carbon or alloy steel. The forged steel for the gears can be divided into:
