Temperature Field Distribution And Thermal Deformation Simulation Of Extended Right-angle Head

The extended right-angle head can expand the processing range of CNC machine tools and improve the processing efficiency.Its accuracy affects the processing accuracy.Due to the small internal space of the angle head,the internal heat generation is not easy to spread,resulting in the overall temperature rise of the angle head and the uneven distribution of the temperature field,resulting in thermal deformation.The error caused by thermal deformation accounts for more than half of all errors.Therefore,it is of great guiding significance to study the influence of thermal deformation on the performance of the angle head,and the cooling structure designed reduces the influence of thermal deformation on the accuracy of the angle head fundamentally.The main contents of the paper include:(1)The thermal characteristics of angle head are analyzed.Firstly,the internal structure of the angle head is analyzed,after that,it is determined that the main heat source of the angular head is the friction heat generation between the gear and the bearing;The heat transfer mode is heat conduction and heat convection.The convective heat transfer includes gears,bearings and lubricants,as well as rotating spindles,external surface of angle head and air.The heat flow density and convective heat transfer coefficient are calculated by empirical formula.And an iterative method was proposed to solve the problem of inaccurate natural convection heat transfer coefficient between the outer surface of the angle head and the air due to temperature difference,improving its calculation accuracy.(2)The temperature field of angle head is simulated.With the heat flux and convective heat transfer coefficient as the boundary conditions,the steady-state and transient temperature field simulation results of the angle head can be obtained through the verification of the independence of the solid mesh.The reasons for the formation and the stability time of the temperature field are analyzed.After that,the single factor analysis shows that the radial force,axial force,torque and rotational speed have influence on the temperature field of the diagonal joint.Orthogonal experiment analysis showed that the four factors had significant effects.(3)The thermal deformation simulation of angle head is carried out.The steady and transient thermal deformation results of the angle head are obtained by taking the temperature field results as the body load and setting the constraint conditions.The thermal deformation of the overall and X,Y,Z directions and the change of the thermal deformation of the front face of the output shaft with time are analyzed.Then,single factor and orthogonal experiments are carried out,and it is concluded that the other three factors have significant effects on the thermal deformation of the front end face of the output shaft of the angle head,except for the axial force.(4)The water-cooled angle head Fluid-heat-solid coupling analysis was carried out.The circumferential S-type water-cooled jacket and axial S-type water-cooled jacket were designed,and the near-wall temperature and wall-to-wall heat transfer coefficient of cooling water is extracted by Fluid-heat-solid-solid coupling.The compiled Profile file solves the problem of inaccurate cooling water wall temperature and improves simulation accuracy.The relevant information of cooling water flow field is obtained through fluid mesh independence verification and continuous iteration,and then the temperature field and thermal deformation of two types of water-cooled angle heads are obtained,which are significantly lower than those of common angle heads.