Research On Temperature Control Strategy Of High Precision Turntable In Vacuum Environment

Vacuum turntable equipment is an important attitude control device in space detection technology,which requires high motion accuracy.However,because vacuum turntable is usually used in high and low temperature environment,in addition to the influence of ambient temperature,the thermal conduction generated by the motor in the turntable equipment makes its temperature field uneven.In vacuum environment,the heat can only enter through solid contact and thermal radiation Therefore,it is necessary to provide a high-precision turntable temperature control strategy suitable for vacuum environment to improve its temperature control accuracy.In this paper,the working environment of the vacuum turntable is-173 ℃-60 ℃.It is necessary to ensure that the temperature of each key part of the turntable is maintained at about20 ± 1 ℃ in order to maintain the high accuracy of the turntable.Through the thermal analysis of the turntable without thermal control system,it is found that the ambient temperature has a great influence on the temperature field of the turntable.Some parts need to be heated and some parts need to be cooled,which increases the difficulty of the temperature control of the turntable.Therefore,it is necessary to isolate the environment from the turntable system.By wrapping the insulation material on the outer surface of the vacuum turntable equipment,the radiation heat transfer between the equipment and the environment is reduced,Turn it into simple cooling.In aerospace equipment,polyimide is usually used as insulation material,which has very low thermal conductivity and surface emissivity.The temperature control strategy of polyimide is simplified,and the temperature control of polyimide outer surface is greatly reduced.Through the analysis of the temperature field of the turntable with heat insulation system,it is found that the temperature rise rate of the turntable transient temperature field is slow under the protection of heat insulation materials.The heat insulation system effectively reduces the impact of environmental radiation on the turntable,and the thermal control demand of the turntable is transformed into the heat generated by the main control motor and load.For this reason,a heat exchange system is further proposed: a heat exchange plate is arranged on the surface to be heat exchanged,a flow channel is set in the heat exchange plate,and a certain temperature heat exchange agent is introduced.When the heat exchange surface is heated or cooled,the temperature of the temperature control plate is adjusted according to the set control strategy after sensing the temperature change of the vacuum turntable equipment The temperature and the flow rate of heat medium are adjusted to keep the temperature near the heat source stable.Through the analysis of the temperature field of the turntable with the heat exchange system,the results show that the temperature of the main parts of the turntable is stable at about 20 ± 1 ℃ in the vacuum environment of-173 ℃-60 ℃,which ensures the accuracy of the turntable.