The Temperature Model Of The Mechanical Spindle Combined With The Finite Element Method And The Bee Colony Algorithm

With the requirement of the machining accuracy continuing to improve,mechanical spindle,as an important part of CNC machine tool,its good or bad performance will directly affect the machining precision of the work piece.The processing process will produce a large amount of heat,which will lead to the occurrence of spindle expansion of different degrees in the horizontal and vertical,and profoundly affect the machining accuracy.Therefore,in recent years,the thermal deformation of mechanical spindle of CNC machine tools has attracted more and more attention,it has become one of the main factors affecting the performance of high speed machine tool.To study thermal deformation,the first thing is to determine the temperature field.Because of the complexity of the spindle structure and temperature conditions,it is difficult to rely on the traditional analytical method to determine the temperature field accurately.The convective heat transfer coefficient,as an important parameter of temperature model,its value reflects the spindle parts surface and air convection heat transfer intensity and has a great influence on the temperature field analysis of the accuracy of mechanical spindle.Traditional empirical formula,which has poor accuracy to determine the convection heat transfer coefficient,can not adapt to changes in the working conditions and other issues.In order to solve the above problems and improve the precision of the mechanical spindle temperature model,this thesis takes the 170CP06-DM mechanical spindle performance test system as an example,the research contents are as follows:Analyze the technology of mechanical spindle to determine the heat source and heat transfer,analyze thermal characteristics of the spindle in the process to define the initial conditions and boundary conditions.From the thermal characteristic analysis,we can know that the convective heat transfer coefficient is the key boundary condition in the analysis of the temperature field,which has a crucial influence on the accurate analysis of mechanical spindle temperature field.Hence,it's the key to establish a precise mechanical spindle temperature model with the precise definition of convective heat transfer coefficient.This thesis starts from the first law of thermodynamics and the fourier law,and establishes mechanism model of the mechanical spindle temperature field.As the model is a multivariable heat conduction differential equation,it's difficult to solve directly.However,the finite element method has high precision and is suitable for any complex structure.Therefore,the finite element method is used to establish the mathematical model of the transient temperature field of the mechanical spindle.An optimization method of convective heat transfer coefficient of mechanical spindle based on artificial bee colony algorithm is presented.The convective heat transfer coefficient,as a key boundary condition,is not only changing with different working conditions,but also affected by varied factors such as,flow rate and temperature of fluid,temperature difference between the shape,part,boundary of heat transfer boundary and fluid.The influence factors are multivariable,coupled and nonlinear,there isn't accurate mathematical model to describe them.First of all,the convective heat transfer is divided into regions according to different positions of convective heat transfer surface.Aiming at the situation that the traditional formula method cannot determine the convective heat transfer coefficient to adapt to changes in working conditions,this thesis will solve it by applying artificial bee colony algorithm to the convective heat transfer coefficient.The mechanical spindle convective heat transfer coefficient based on artificial bee colony algorithm Optimization method is presented,which is used to determine different convective heat transfer coefficient corresponding to different working conditions.Experimental study.With the help of 170CP06-DM mechanical spindle performance test system of high-grade stone equipment and technology of CNC state and local joint Engineering Laboratory of Shenyang Construction University in the platform,temperature rise were tested in different loads and speed,collecting a large number of experimental data of mechanical spindle,and having a research of convective heat transfer coefficient based on artificial bee colony algorithm optimization method.The experimental results show that with the proposed method,whether the no-load or load condition,whether high or low speed condition,it can find adaptive convective heat transfer coefficient,and the simulation of the temperature value is infinitely close to the actual temperature value,to improve the accuracy of machine spindle temperature model.