| Because of the characteristics of NOMEX honeycomb, it is more and morewidely used in the aviation and aerospace field. But after the honeycomb materialbeing made, how to cut the honeycomb efficiently always troubles the aircraftmanufacturers.At present, domestic enterprises are used to machining honeycomb materialstraditionally in the same way as metal. The shortcomings of the method are: largevolume equipment, high cost, low quality of the machined workpiece surface,large amounts of dust, bad environmental protection. A number of large state-ownedenterprises has introduced the6-axis ultrasonic cutting machining, US-50from GFM.Ultrasonic cutting is the key technology of this machine, which is main equipment ofmachining honeycomb.It has been20years for ultrasonic cutting technology, whose advantages are:small cutting force, high surface quality and machining efficiency, continuous swarfand no dust. Every Research and Develop of major aircraft manufactures in Europeand the United States all have widely used ultrasonic cutting equipment to production.However, in China, this technology is still in its early stage. In order to achieve theapplication of ultrasonic cutting technology in the traditional processing equipment,ultrasonic cutting technology was brought into five axis machining center. Based onthe characteristic of small cutting force, five axis machining center would beoptimization design in lightweight.The main work and innovations are as follows:In the first chapter it is introduced that the development and characteristics ofNOMEX honeycomb material, the methods of machining honeycomb material andcomposite material are different because of its special structure. This paper listsseveral processing methods in traditional honeycomb materials and introduces andanalyses the main technology in machining honeycomb aboard-ultrasonic cuttingtechnology in detail.In the second chapter it is introduced the general layout of ultrasonic machinetool. The XH2725/5X machining center that was made by Jiangsu Xinrui HeavyTechnology Co. Ltd was chose as the optimization target. The structure of ultrasonic cutting spindle and swing mechanism was analyzed to achieve A/C axis. Theultrasonic acoustic system was designed in theory. A kind of ultrasonic cutting knifeconstant torque assembly device was designed to change ultrasonic circular knife inconstant torque.In the third chapter it is introduced the relevant technical data of gantrymachining center, whose3-D model and FEM model was built. The theoretical valuesof force in cutting honeycomb material were calculated. The gantry machining centerwas taken static analysis and calculated the static stiffness. It is also analyzed bymodal and harmonic response to establish foundation for the subsequent optimization.In the fourth chapter it is introduced that the spindle box, ram, beam and columnof the machining center was analyzed to find out the weakness of structure. The largerdisplacement of points were figured out by the static analysis, the position ofconcentration stress was determined by cloud picture of stress distribution. Theoptimization of the next chapter was provided the basis which is parts deformation gotfrom the dynamic mode.In the fifth chapter it is introduced that the spindle box, beam and column wasoptimized in structure. The spindle box design followed the internal structure ofanimal bones, the beam was designed according to arch structure, the columnperformance of supporting was improved by curvature support of round. In addition,the sensitivity analysis method is used to determine and optimize the sensitive factorof crossbeam and the column, to improve the dynamic stiffness of machine tools,machine tool to reduce weight. The optimized parts would be assembled into entirety,which would be analyzed by static and dynamic to compare the lightweight results, toachieve ultrasonic cutting lightweight design of machine tool. |
