| High speed machining technology has become the key technology of advanced manufacturing technology,because of its advantages of high speed,high efficiency,high precision and so on.The temperature rise of the motorized spindle is one of the main factors that affect the machining precision of the high speed machining technology,which seriously restricts the development of high speed machining technology.In order to reduce the temperature rise of the electric spindle,and make it have good thermal characteristics,the permanent magnet synchronous electric spindle with small calorific capacity is selected to study object in this dissertation.The thermal characteristics of motorized spindle are studied by theoretical analysis and finite element simulation.The distribution characteristics of the temperature field are studied.The variation law of the thermal performance is mastered.The method of improving the thermal characteristics of the permanent magnet synchronous spindle is provided.Research results can provide some references for the design of the spindle.The main research contents include the following aspects:This dissertation introduces the basic structure,characteristics and working principle of the permanent magnet synchronous motorized spindle.The key technologies of the spindle system are analyzed,including the lubrication technology and the cooling technology of the spindle.The mechanism of thermal deformation of permanent magnet synchronous spindle and the main heat source are discussed and analyzed.The influence of different working conditions on the temperature rise of the spindle is also discussed.The rotational speed and the kinematic viscosity of the lubricating oil have a great influence on the temperature rise of the spindle.Two heat generation rate of bearing friction and motor loss of permanent magnet synchronous spindle are analyzed and calculated.The main heat transfer coefficient of the main shaft are calculated,which include:convective heat transfer between motor and cooling water,convective heat transfer between stator and rotor,convection heat transfer between rotor end and air,convection heat transfer between annular groove and cooling water of bearing seat,convection heat transfer between bearing and compressed air,the heat exchange between the electric spindle housing and the surrounding air.The influences of cooling water flow rate of cooling system and the compressed air flow rate on the heat transfer coefficient of the spindle are studied.The finite element analysis model of permanent magnet synchronous spindle is established.The heat analysis is carried out by using ANSYS Workbench software.The steady and transient temperature fields of permanent magnet synchronous spindle are obtained.The distribution of temperature field is analyzed by the temperature field distribution nephogram.The results show that the overall temperature distribution of the spindle is very uneven,where the maximum temperature rise at the bearing.According to the distribution law of the temperature field,the measures to improve the thermal characteristics of the permanent magnet synchronous spindle are put forward,including increasing the flow of cooling water,compressing the air through the shaft and reducing the kinematic viscosity of the lubricating oil.The improved temperature field and the primary temperature field are compared.The proposed method can effectively reduce the temperature rise of the electric spindle. |
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