The method of temperature difference is to use heating hole or cooling shaft to form clearance fit through thermal expansion and cold contraction. After the temperature returns to normal temperature, the clearance fit is converted into interference fit to meet the specified interference amount and meet the technical requirements. However, for the assembly of large parts with large interference, it is difficult to handle; the investment of heating equipment is large; the high heating temperature is very easy to cause the change of material organization and performance; the construction personnel can not get close to the key process of internal control assembly of the workpiece. As long as the high tonnage parts are positioned and clamped according to the requirements of the assembly process, the cold assembly method is very convenient for the parts with small cooling volume, handling and process monitoring, and it is easy for the construction with high efficiency. The cold assembly method has a wide range of application and will not change the material properties. It can be used for most low-carbon steel parts, alloy steel and non-ferrous metals. It is especially suitable for the fit of shaft parts with relatively small size with large interference of large hole parts, with high positioning accuracy.
Industrial refrigerator cooling method belongs to the cryogenic treatment of materials, also known as ultra-low temperature treatment, which refers to a method of material treatment below – 150 ℃, which is an extension of conventional cold treatment. Cryogenic treatment can greatly reduce the residual austenite in the metal material, make the matrix structure of the metal precipitate uniform, fine and dispersed carbide, significantly improve the mechanical properties and service life of the metal material, stabilize the shape and size, improve the general uniformity, reduce the stress and deformation; Simple operation, no damage to the workpiece, no pollution, low cost, with considerable economic benefits and market prospects.
Process implementation
For the spindle freezing, it is necessary to prepare low-temperature gloves, protective masks, goggles, boots, helmets and other labor protection appliances before freezing.
The result of this assembly is a key step that directly affects whether the subsequent machining process can meet the design accuracy. Finally, in the process of precision machining based on the spindle, the assembly effect is also verified to be very ideal, which fully meets the requirements of precision machining based on the spindle, and well ensures the interference required by customers. In the future, for the assembly of large parts with large interference and high matching accuracy, cold assembly of industrial refrigerator will become an important means to ensure the interference and quality requirements. Cold shrink assembly will also be more widely used with the design requirements of the mechanical industry and higher use standards.