Variable temperature characteristics of machine tool spindle
Author: Posted on: 2019-09-29 08:38:57 Text: [ big
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During the work of the machine tool spindle components, heat will be released due to energy loss such as friction and oil stirring. When the heat makes the heat received by the spindle component equal to the heat dissipated, it reaches the state of thermal equilibrium. The time required for this process is called the time of temperature. It is a function of the surface area, surface heat transfer coefficient, specific heat capacity and mass of the spindle component. The temperature rise of the main shaft components includes the temperature rise of related parts inside the main shaft box, such as the main shaft, bearings, transmission gears, and housings. On the research surface, the temperature rise of the main shaft component plays a leading role in the thermal deformation of the machine tool. The main impact of the temperature rise on the normal work and machining accuracy of the machine tool is:
1) The temperature rise causes the temperature of each part to change with time, and the machine tool loses the existing adjustment accuracy, which affects the size of the workpiece being processed. At the same time, the temperature rise also changes the bearing clearance, which affects the machining accuracy.
2) The temperature rise makes the temperature distribution non-uniform, which causes the mutual positional relationship of each part or part of the part to change, thereby causing displacement or distortion of the part. For example, 80% of the spindle tilt is caused by the temperature difference between the front and rear main bearings.
To reduce the thermal deformation of the spindle components, we can start from reducing heat sources, dissipating heat, making temperature rise stable and uniformly distributed. According to GB / T9061-1988, when the spindle reaches a stable temperature at the highest speed, the temperature of the sliding bearing must not exceed 60 ° C, the temperature of the rolling bearing must not exceed 70 ° C, and the temperature of the spindle bearing of high-precision machine tools such as coordinate boring machines must not exceed 10 ° C at room temperature. .