| Machine tool industry is the foundation of modern manufacturing.The processing of large equipment needs not only large machine tools,but also the participation of various functional components.NC facing and boring heads which are massively produced domestic and foreign are similar in basic structure.However,the processing quality and performance of NC facing and boring heads which are produced domestic is not high and unstable respectively,so it is difficult to apply to medium and high grade machine tools.In this paper,the temperature distribution,the thermal deformation and the static equilibrium performance of NC facing and boring head are studied by theoretical analysis and experiment,which improves the processing performance of NC facing and boring head.(1)It analyzes the transmission system of NC facing and boring head and obtains the heat source and the thermal boundary condition,which is applied on the finite element of NC facing and boring head.The thermal equilibrium temperature at the maximum speed of the finite element model is 40.75 ?.The temperature rising can be estimated by the temperature measurement experiment at different speed and on which the thermal boundary conditions under maximum speed is corrected.The thermal equilibrium temperature of the modified model is 31.54 ?,and its maximum error of the calculated value and the experimental value is 1.52%,which can accurately reflect the temperature field distribution.(2)It uses the finite element software to calculate the thermal deformation under the maximum speed.The maximum deformation of fixed body and rotating body is 25.04 ?m and 24.63 ?n respectively,and the radial runout and the end runout of the rotating body is 4.84?n and 2.13 ?m respectively.The axis asymmetry of temperature field distribution of NC facing and boring head is the main factor of the large radial runout and end runout,which requires further structural optimization.(3)To improve the heat dissipation condition by adding openings on the fixed body,which reduces the thermal deformation of NC facing and boring head.Using the finite element software to parameterize the opening model,taking the decrease of radial runout and the end runout as goal,the opening shape,size,and position as design variables,keeping the second-order fixed frequency of the fixed body basically invariable.The optimal opening model is rectangular,and its width and height are 130 mm and 30 mm respectively.The optimal position is located at the left end of the motor output shaft by 70.68 mm and the installed motor base by 29.76 mm.The radial runout reduced from the original 4.84 ?m to 4.57 ?m,decreased by 5.58%;and the end runout reduced from the original 2.13?n to 1.86?m,decreased by 12.68%.The optimization effect is obvious.(4)According to the structural characteristics of NC facing and boring head,the static equilibrium condition and the balance error are analyzed theoretically,and the counterweight checklist and the balance error table of NC facing and boring head are established.A new type of transmission method is proposed,making the NC facing and boring head itself have a good balance performance and the feasibility of the new transmission mode is verified by experiment,which improves the processing performance of NC facing and boring head.The thermal characteristics and structural optimization reduce the temperature rising and thermal deformation of NC facing and boring head;the new transmission mode itself has a good static equilibrium,and the complicated table look-up process and discontinuity of static equilibrium are avoided.All of these behaviors improve the balance and processing performance of NC facing and boring head. |
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