In the design of nc machine tool bearing selection skills

Bearing is an important component of the spindle component, its type, structure, configuration, accuracy, installation, adjustment, lubrication and cooling are directly affect the performance of the spindle component. The spindle rotation accuracy to a great extent, determined by the bearing. The spindle rolling bearing ( 1) The type of rolling bearings rolling bearing small friction resistance, can be preloaded, lubrication maintenance is simple, can be in the range of speed and load changes within the scope of a steady job. Rolling bearing by the chemical plant production, easy maintenance of choose and buy. But compared with sliding bearing, the rolling bearing noise is very big, the limited number of rolling elements, stiffness is variable, vibration resistance of slightly and to speed limit. Rolling bearing based on the structure of the roller is divided into the ball bearings, cylindrical roller bearings. Ceramic bearing is bearing roller is made of ceramic material, while the inner and outer ring are made of bearing steel. Chose a rolling body, mainly because it has the following: is light weight, the second is the small thermal expansion coefficient, three is the modulus of elasticity. So it has a small centrifugal force, friction small, stable pre-tightening force, elastic deformation is small, high rigidity. ( 2) Reasonable arrangement of main shaft bearing 1) The choice of main shaft bearing and configuration form of machine tool spindle before and after two and before, during and after the three supporting two kinds, with the former is relatively rare. Two bearing spindle bearing configuration forms, including the main shaft bearing selection, combination and arrangement, according to the main spindle components involved in the rotational speed, bearing capacity, stiffness and accuracy requirements. When determining the two bearing spindle bearing configuration forms should follow the principle of the following as: (1) to meet the requirements of rigidity and bearing capacity: the choice of the form of main shaft bearing configuration should be first meet the required stiffness and bearing capacity. (2) to adapt to the speed requirements: different models, specifications and precision bearing allowed by the rotating speed is different. Under the same conditions, higher than the line contact point contact; Cylindrical roller is higher than tapered roller. (3) to meet the requirements of accuracy, the thrust bearing of the spindle component under axial force configuration form directly influence the axial location precision of the spindle. 2) Three supporting some spindle component of machine tool, due to the structural design of spindle box length is longer, the spindle bearing span between two supporting than span, at this point, add intermediate support should be considered to improve the spindle rigidity and vibration resistance of the component. 3) Spindle rolling bearing design of the application of (1) the main shaft of the rolling bearing stiffness and load capacity of rolling bearing stiffness depends mainly on relation with contact stiffness between the rolling element and raceway. Movement of bearing stiffness and bearing type, load and pre-tightening condition, and with the increase of load is nonlinear. (2) the main shaft bearing lubrication lubrication performance and the life of the bearing of the spindle component work has a great influence. Lubrication may cause unreasonable increase of quantity of heat, reduces the working precision of the spindle, and accelerate the bearing wear. Used for rolling bearing lubricants can be divided into two categories, namely the grease lubricant and liquid lubricant. (3) the main shaft seal of rolling bearings rolling bearing sealing device and prevent the action of coolant, chip, dust and debris into the bearing, and keep the lubricant without leakage within the bearing, so as to give full play to the performance of the bearing, ensure that the service life of bearing. Is: to the requirement of spindle component sealing device is suitable for the spindle speed, adapt to the working environment, structure tightly. Seal of main shaft bearing points of contact type and non-contact. And the former can be divided into radial sealing ring felt ring seal, seal box, suitable for low speed spindle. Non-contact seal can be divided into gap seal, seal gasket seal box curved road, in order to ensure the sealing function, the radial clearance of rotational part and fixed part should be less than 0. 2 - 0. 3 mm, the seal should be back to oil control, in case of oil spill. Tags: