| One: IntroductionWith the process of the integration of the global economy accelerating and the development of the information technology speedup, the condition of the modern manufacturing industry has changed a lot. Its main features are shown as follow, product life cycle become shorter; production time is a major competitive factor; individual users demand; the proportion of varieties and small batch production increase. Machine enterprises should be able to make quick response with the rapid changes of the market demand, and make reasonable adjustments to their production in time. By the development and application of virtual manufacturing technology, the research and development of high-tech CNC machine tools have make a progress. It is the key issue that how to apply the virtual simulation technology to solve the key techniques of machine tools at the design stage.In this paper, the writer has modeled the virtual prototype of the FIDIA D165 high-speed milling center. First the writer modeled the solid parts and assembled them, then checked the interference, finally generated a complete prototype model. By using the finite element software ANSYS, the writer analyses the static and the dynamic characters of the machine bed. Based on the analysis results, the writer did some appropriate improvement to the bed structure, and it provided a reference for the future improvements of the machine tool. Two: The 3D Solid Modeling for the FIDIA D165 high-speed milling centerBase on the study of the structure of the machine tools, the writer modeled the virtual prototype of the FIDIA D165 high-speed milling machine by using the 3D solid modeling software Pro/engineer wildfire 2.0. According to the machine tool features, the machine tool will be divided into machine bed, saddle, cross-slide, ram, and table case five main components. Because of the differences between features of the casting and welding pieces, they are different in modeling too. Modeling directly for castings, however, welding parts required to assemble after modeling the pieces. A complete model of the machine tool will be established after modeling the various components for assembling. The complete model of machine tool in Figure 1 below: Fig 1: the complete model of FIDIA D165 high-speed milling centerThree: The static, dynamic analysis for machine bedStiffness will affect the performance of the whole machine directly. To get the static, dynamic parameters of machine bed, the writer did the static, dynamic characteristic analysis by using the finite element analysis software.The solid model of the machine bed should be simplified before the analysis. Get rid of the unnecessary characteristics which don't affect the analysis results, such as the convex, tiny hole and so on. If we don't do that, the finite element model which will be generated later, will has too much element even can't be generated. The simplified model will be transmitted to finite element analysis software ANSYS by the interface between the Pro/E and ANSYS. Setting the parameters for the model which transmitted to ANSYS, and grid it in the pre-processor, then we get the finite element model of the machine bed. We need to know the pressure on the machine bed when the slide saddle arrives at Y-axis limit position before we start the static analysis. Then we put them on the finite element model as the boundary conditions. The static analysis result is shown in figure 2. This paper also do the modal analysis of the machine bed, and get the first 10 step natural frequencies and mode shapes. Fig2: the result of the dynamic analysis of the machine bedFour: the optimization and design for the structure of the machine bedThe machine bed has many vertical and horizontal tendon plates inside. The tendon plates have an important impact on the performance of the machine bed. The most effective method to enhance the stiffness of the bed is to design the tendon reasonable. The reasonable designed tendon plates not only can improve the stiffness of the bed, but also can reduce its weight. Therefore, this paper gives four options which based on the shape of the sand hole, the number of the tendon plate, the thickness of the tendon plate and etc to improve the static and dynamic characters of the bed.Scheme1: change the shape of the sand holes which are on the rib from square to circle.Scheme2: change the spacing between the two ribs, adding a horizontal rib.Scheme3: change the thickness and the number of the rib, reduce a cross rib and increase the other ribs'thickness.Scheme4: change the shape of the sand holes, the thickness and the number of the rib at the same time.We can see the static and dynamic characters by analyzing the finite element model of the four optimized machine beds, and compare them with the results of the original one. We can find out the affection of the sand hole, the number and the thickness of the rib on static and dynamic characters of the machine bed. Considering with the weight and the characters of the machine bed we can choose a better one. That will be good for the optimization of the machine in the future.Five: Conclusion(1) In this paper, we have studied on the structure of the production of the Shenyang FIDIA Machine Tool Company Ltd. FIDIA D165 high-speed CNC milling machine. Its main components were classified in accordance with the processing. We modeled all the parts and assembled them together. We also checked the interference and got rid of them. Finally, we got the entire model of the machine tool.(2) Analyzing the static character of the machine bed. By calculating the weight of the components which on the machine bed, the writer got the loads of the machine bed, and applied them on it. After setting all of the boundary conditions we can know the deformation of machine bed when the sliding saddle was on its limited position.(3) Analyzing the model character of the machine bed. We got the first ten natural frequencies and mode shapes by analyzing the machine bed simplified finite element modal.(4) Improving the structure of the machine bed. According the analysis of machine bed static, dynamic characters, the writer give four improvement programs. We find out the influence of the shape of sand hole and the numbers of the internal tendons plate on the performance of the machine bed. Finally we obtained a better improvement program and the paper provided a reference for the future improvements of the machine tool.(5) The designer can analyze and compare the design programs by the parametric 3D CAD and the FEA, so the design can modify the modal or redesign as early as they can. This method needn't to machine the sample, so it not only cost the less money but also shorten the design cycle.
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