1. Processing accuracy
1) Dimensional accuracy. The dimensional accuracy of shaft parts mainly refers to the dimensional accuracy of the shaft diameter and the dimensional accuracy of the shaft length. According to the requirements of use, the dimensional accuracy of the main journal diameter is usually IT6-IT9 level, and the precision journal can also reach IT5 level. The length of the shaft is usually specified as the nominal size, and the length of each step of the stepped shaft can be given a corresponding tolerance according to the requirements of use.
2) Geometric accuracy. Shaft parts are generally supported on the bearing with two journals. These two journals are called supporting journals and are also the basis for the assembly of the shaft. In addition to the dimensional accuracy, the geometric accuracy (roundness, cylindricity) of the supporting journal is generally required. For the journal of general accuracy, the geometric shape error should be limited to the diameter tolerance range. When the requirement is high, the allowable tolerance value should be separately specified on the part drawing.
3) Mutual position accuracy. The coaxiality of the matching journals (the journals of the assembled transmission parts) relative to the supporting journals in the shaft parts is a common requirement for their mutual position accuracy. Generally, the shaft of ordinary precision, the accuracy of the radial circle runout of the supporting journal is generally 0.01-0.03mm, and the shaft of high precision is 0.001-0.005mm. In addition, the mutual position accuracy also includes the coaxiality of the inner and outer cylindrical surfaces, and the perpendicularity requirements of the axial positioning end surface and the axis line.
2. The surface roughness depends on the precision of the machine, the speed of the operation, and the surface roughness requirements of the shaft parts are also different. In general, the surface roughness Ra of the supporting journal is 0.63-0.16μm; the surface roughness Ra of the matching journal is 2.5-0.63μm.
Stainless steel (StainlessSteel) is the abbreviation of stainless acid-resistant steel. It is resistant to weak corrosive media such as air, steam, water or stainless steel, and is called stainless steel; ) Corrosive steel is called acid-resistant steel.
Due to the difference in chemical composition of the two, their corrosion resistance is different. Ordinary stainless steel is generally not resistant to chemical medium corrosion, while acid-resistant steel is generally stainless. The term "stainless steel" not only refers to a single type of stainless steel, but also refers to more than one hundred kinds of industrial stainless steel. Each type of stainless steel developed has good performance in its specific application field. The key to success is to first clarify the purpose, and then determine the correct steel grade. There are usually only six types of steel related to the application of building construction. They all contain 17-22% chromium, and the better steel grades also contain nickel. The addition of molybdenum can further improve atmospheric corrosion, especially resistance to chloride-containing atmospheres.