Research on the hottest virtual machine tool proce

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Research on virtual machine tool machining system (Part 2)

the key technology of virtual machine tool machining system research

establish a topological model of virtual machine tool machining system that has certain comparability with real machine tool machining system in structure, represents the common characteristics of a kind of machine tool machining system, and has higher flexibility, reconfigurability, and reusability; According to the above model, the kinematics model of the virtual machine tool machining system is established, so as to complete the motion state description of the spindle of the virtual machine tool machining system and the motion trajectory description of the tool; The error modulus of virtual machine tool machining system reaches 12% The error of a kind of machine tool processing system is integrated into the kinematic model, so that the workspace of the tool has higher authenticity; The establishment of a cutting model that truly reflects the cutting process; A standardized product data representation that can truly reflect all the information of the parts after being put into the preform; Unified interface definition and information exchange mode between systems; Forecast and monitor the processing quality of processed products and digital parts

3 some basic methods to solve the key technologies

establish the topological model of machine tool processing system

use the topological equivalence relationship to form a machine tool in the topological sense and establish the most general mapping relationship. This kind of mapping relationship refers to the various relationships that affect the processing quality contained in the virtual machine tool processing system, the real machine tool processing system and the virtual machine tool processing system. In the establishment of topological model, we divide the existing machine tools into appropriate components in order to form the corresponding structure. For multi axis machine tools, the difference of the sequence and movement mode of each component will make the composition of tool path and error significantly different. In particular, the adjustment error is closely related to the relative position of each component of the machine tool. Using a characteristic kinematic chain of forming motion, the topological structure of the machine tool can be expressed, and the error fusion is convenient. For example, the forming function of a multi axis machine tool can be expressed as

rw=ai1ai2 AIJ ainrt (1)

in the formula RW position vector of the workpiece in the workpiece coordinate system RT position vector of the tool in the tool coordinate system AIJ homogeneous coordinate transformation matrix from the workpiece to the moving chain component frame of the tool. Here, a certain code can be used to represent the multi axis machine tool. For example, a five axis machine tool can be expressed as w/baxyz/t (z), then the forming function is

rw=a () 5A () 4a (x) 1a (y) 2A (z) 3RT (2)

where x, y, Z are the movement of X, y, z axes, and,, are the rotation of a, B axes. This shaping function forms the rudiment of topology. All subsequent work is based on it

initialization of virtual machine tool processing system the main function of initialization of virtual machine tool processing system is to enable the virtual machine tool processing system to carry out virtual processing according to the existing machine tools more truly, so that the obtained processing results can be quickly applied in the real processing site. This is actually the choice of machine tools in process planning. Although the range of choices becomes quite large at this time. In addition, the virtualization task of the selected machine tool should also be completed here. It requires a lot of parameters and many graphic operations. To complete these tasks, the support of network communication is essential

The ultimate goal of virtual machine tool machining system is to get the ability to predict workpiece attributes. Therefore, the establishment of workpiece attribute model is very important to the success of virtual machine tool machining system. The fields involved include the representation of workpiece surface data, modeling of tools, performance of single point tools and multi-point tools, modeling methods of surface forming, etc. At the same time, we also pay attention to the influence of machine tool system error

the data organization form of realistic machined surface and the calculation method of directly picking up errors such as roughness are still under further study. It is necessary to unify the description format of data. Because it will affect all links of the virtual machine tool processing system. At present, the main methods to describe workpiece data are CSG, step, etc. In addition, fractal method can also be used to describe the processing process of graphic data and the micro morphological characteristics of machined surface. In short, the main work at present is to comprehensively consider the existing methods and various possible factors and summarize an appropriate scheme

consideration of motion, geometric error model and dynamics problem

for the establishment of kinematics model of multi axis machine tool, at present, most of them adopt DH method or make some correction to DH method. There are also four parameter model and five parameter model in error analysis. Although D H method can connect motion, transformation and mapping with matrix operation, it is not very convenient for error calibration and solving problems such as speed and force. The spinor method can obviously simplify the compilation of calculation program, and can deal with free vector and line vector at the same time. The use of this method can not only reduce the difficulty of this research, but also make it clearer

in addition, because the machine tool processing system is a very complex processing technology system, although its research has a long history since its inception, there are still many difficult problems that have not been well explained quantitatively, and the empirical and experimental data still play a leading role; At the same time, its various components have strong connections, and various connecting factors are complex. This brings considerable difficulty to virtual work. Especially, the dynamic error has a great influence on the machining quality. Vibration and the change of processing temperature will play a key role in roughness in a certain range. Using a simplified method to decompose it into relatively independent components to study has become a widely recognized research strategy

4 Conclusion

in China, the research on virtual manufacturing technology has been carried out relatively early and has made some achievements. However, the research on virtual machine tool machining system has not been reported. Based on the in-depth study of some key technologies of virtual machine tool machining system, we have completed a software system of virtual machine tool machining system based on turning. The software system has the functions of NC code conversion, virtual machining and machining quality monitoring, which has a certain practical significance. At present, the virtual machine tool machining system of multi axis machine tool is being studied. According to the characteristics of multi axis machine tools and workpiece processing, we focus on the description of workpiece attributes, the modeling of cutting force, the description and detection of workpiece surface contour after machining, and the research of agent technology

the research of agent-based technology is very valuable for the construction of such a software tool as virtual machine tool machining system to achieve comprehensive, harmonious and sustainable development. The practice shows that agent-based structure will play a great role in virtual manufacturing and distributed networked manufacturing

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