Effect Of Temperature Rise On Machine Tools Such As Milling Machines
The temperature rise causes the temperature of each part to change with time, which causes the machine tool to lose the existing adjustment accuracy, thus affecting the size of the workpiece to be processed. At the same time, the temperature rise also changes the bearing clearance, which in turn affects the machining accuracy. The increase in temperature causes the temperature distribution to be uneven, causing a change in the mutual positional relationship between the parts or parts, thereby causing displacement or distortion of the parts.
There are four aspects to reducing the thermal deformation of the spindle:
(1) Reduce the heat source, focusing on the spindle shaft speed, clearance adjustment and reasonable pre-tightening. For thrust bearings and tapered roller bearings, due to poor working conditions, the heat is large. If necessary, the thrust angular contact ball bearings can be used instead to minimize the friction and heat of some components.
(2) Insulation, so that the heat source is away from the main shaft, such as isolating the electric motor and the transmission, and adopting a separate transmission.
(3) Heat dissipation, strengthen lubrication and cooling, adopt oil cooling, air cooling, etc., and accelerate heat dissipation.
(4) Reducing the influence of thermal deformation, no matter which way, it can only reduce the thermal deformation and it is difficult to completely eliminate the thermal deformation. Therefore, measures should be taken to reduce the influence of thermal deformation.
In the case of a plain bearing, the wear resistance of the journal has a great influence on the accuracy retention. The basic requirements of the above work performance can be seen, the spindle component has good rotation precision, which indicates that it has good working precision and good rigidity under no load conditions, and indicates that the static working precision is good. The vibration resistance and thermal deformation are good, and the dynamic characteristics of the marked spindle are good, and the wear resistance determines the retention ability of the working precision.