Virtual Machine Tool Processing System Research

July 23, 2024

1 Overview

The research work of the virtual machine tool processing system was first proposed by the United States. The virtual machine tool research institute established by the University of Illinois and the US NIST have invested a lot of manpower and material resources to carry out the research and development of virtual machine tools. The former work is mainly carried out in two parts: machine tool behavior modeling and process modeling. The behavioral modeling of virtual machine tools includes the following six parts: (1) machine tool topology model; (2) machine tool kinematics model; (3) machine tool control model; (4) geometric error model; (5) spindle dynamics model; 6) Thermal error model. Process modeling is primarily about establishing the relationship between system response, artifact properties, and machining processes. Including: (1) cutting process model; (2) workpiece attribute model; (3) tooling fixture model and other three parts. The latter, in view of providing support tools for virtual manufacturing, and setting the foundation for the development of next-generation information-based manufacturing technology standards.
On the basis of tracking the progress of foreign research, we have completed a software system for virtual machine tool processing system based on turning machining. In this paper, some of the research contents of the virtual machine tool processing system will be discussed in depth (the research content of this paper is funded by the National "863 Program").

2 Basic content and key technologies of virtual machine tool processing system research

  1. Basic requirements for virtual machine tool processing systems
    2. The virtual machine tool processing system is a set of software tools on the computer that can describe the real machining process and quality inspection process, allowing the user to test and optimize the machining process and predict the machining quality. It can be initialized according to the actual machining machine or machining center, and then the CNC machine can drive the virtual machine for cutting. In addition to describing the real motion trajectory of the tool, it can also calculate the shape error, shape and position error, geometric size error and surface roughness of the workpiece according to the tool characteristics, so as to achieve the purpose of predicting the processing quality. The products produced by the virtual machine tool processing system are visual virtual products, which have all the characteristics necessary for real products, and are a digital product.
    The modeling of virtual machine tool processing systems has the following two basic requirements:
    1. In terms of function, it must have certain equivalence with the actual machine tool processing system;
    2. The composition of the structure must be comparable to the machine tool processing system in the actual manufacturing system. It must be serialized, reusable and reconfigurable.
    In addition, the virtual machine tool processing system is an indispensable tool for estimating and verifying the manufacturability of new products. It focuses on the description of metal cutting, which is based on realism and is dependent on real systems. The processing through the virtual implementation will eventually be implemented in a real environment. Therefore, the virtual machine tool processing system should include such things as: (1) the model of the machine tool; (2) the main structural dimensions of the machine tool, the size of the table, the working stroke, etc.; (3) the accuracy of the machine tool, including the motion accuracy of each working part during machining. , guide rail accuracy, positioning accuracy, etc.; (4) the use of machine tools, such as failure rate, failure causes, maintenance records, use environment, etc.; (5) all information on the operation of the machine personnel.
    A virtual machine tool processing system is a virtual system that contains all of the above information and can freely communicate with other virtual resources and real systems.
  2. The basic content of virtual machine system research
    The figure shows the basic framework of a virtual machine tool processing system that meets the above objectives and requirements and the connection of the system to other virtual manufacturing resources and real resources. It clearly shows the basic content of the virtual machine tool processing system.

    2
    The basic framework and research content of virtual machine tool processing system

    The various connections shown in the figure are two-way. The work of the entire virtual production system is centered on the virtual machine tool processing system. The CAD/CAM system provides standardized design data for virtual machine tool processing systems. According to this design data, the virtual machine tool processing system selects the actual machine tool system at the off-site machining position to initialize the product and then processes the product, and delivers the product data obtained after processing to the virtual inspection system and the virtual assembly system inspection product. Quality and performance, while suggesting modifications to the process and design. This process is repeated until a qualified virtual product is obtained. The formed processing data is then fed back to the final selected processing location for processing. Through the above process, a new product is quickly processed. Before the formal delivery of processing data, virtual processing not only does not require any resources, but also can meet the special requirements of customers at any time to achieve agile production.
  3. Key Technologies for Virtual Machine Tool Processing System Research
    1. Establish a virtual machine tool processing system topology model that has certain comparability with the actual machine tool processing system, represents the common characteristics of a class of machine tool processing systems, and has higher flexibility, reconfigurability and reusability;
    2. The kinematics model of the virtual machine tool processing system is established for the above model, thereby completing the description of the motion state of the virtual machine tool processing system spindle and the description of the motion path of the tool;
    3. The error model of the virtual machine tool processing system is established, and the error of a class of machine tool processing system is integrated into the kinematic model, so that the working space of the tool has higher authenticity;
    4. The establishment of a cutting model that truly reflects the cutting process;
    5. A standardized product data representation that truly reflects all of the workpiece's information;
    6. Interface definition and information exchange between unified systems;
    7. Forecast and monitoring of processed products and processing quality of digital parts.

3 Some basic methods to solve key technologies

  1. Establish a machine tool processing system topology model
    Using topological equivalence relations, a machine tool in a topological sense can be formed to establish the most general rendition relationship. This kind of re-enactment relationship refers to various relationships affecting the processing quality contained in the virtual machine tool processing system and the actual machine tool processing system and the virtual machine tool processing system. In the establishment of the topology model, we divide the existing machine into appropriate components to form the corresponding structure. For multi-axis machines, the order of the components and the different modes of motion will make a significant difference in the composition of the tool path and error. In particular, the adjustment error has a great relationship with the relative position of the various components of the machine tool. The characteristic kinematic chain of a forming motion can be used to represent the topology of the machine tool and facilitate the fusion of errors. For example, the forming function of a multi-axis machine tool can be expressed as
    r W =A i1 A i2 ...A ij ...A in r T (1)
    r W - the position vector of the workpiece in the workpiece coordinate system
    r T - the position vector of the tool in the tool coordinate system
    A ij - the homogeneous coordinate transformation matrix of the workpiece-to-tool kinematic chain component frame <
    Here, a multi-axis machine tool can be represented by a certain code. For example, if a five-axis machine tool can be expressed as W/baxyz/T(Z), the forming function is
    r W =A (φ) 5 A (φ) 4 A (x) 1 A (y) 2 A (z) 3 r T (2)
    In the formula, x, y, and z are the movement amounts of the X, Y, and Z axes, and φ and Φ are the rotation amounts of the A and B axes.
    This shaping function constitutes the prototype of the topology. All subsequent work is based on it.
  2. Initialization of the virtual machine tool processing system The main function of the initialization of the virtual machine tool processing system is to enable the virtual machine tool processing system to be more realistically machined according to the existing machine tool, so that the processed results can be quickly applied to the real processing site. This is actually a machine selection problem in process planning. Although the range of choices at this time has become quite large. In addition to this, the task of virtualizing the selected machine is also done here. It requires a lot of parameters and a lot of graphics operations. To accomplish these tasks, support for network communications is essential.
  3. Research on workpiece attribute model
    4. The ultimate goal of a virtual machine tooling system is to get the ability to predict the properties of the workpiece. Therefore, the establishment of the workpiece attribute model is very important for the success of the virtual machine tool processing system. The fields involved include the representation of the surface data of the workpiece, the modeling of the tool, the performance of the single-point tool and the multi-point tool, and the modeling method of the surface forming. At the same time, attention is also paid to the influence of machine tool system errors.
    Data organization forms of realistic processed surfaces and calculation methods for direct picking of errors such as roughness are further studied. A description format for unified data is necessary. Because it will affect all aspects of the virtual machine tool processing system. At present, methods for describing workpiece data mainly include CSG, STEP method, and the like. In addition, a description of the processing of the graphic data and the description of the microstructure of the processed surface can also be performed using a fractal method. In short, considering the existing methods and various possible factors, summing up an appropriate program is the main work at present.
  4. Motion, geometric error model and consideration of dynamics problems
    For the establishment of the kinematics model of multi-axis machine tools, most of the current D-H method or the D-H method is modified. When applying the error analysis, there are methods using a four-parameter model and a five-parameter model. Although the D-H method can relate motion, transformation and mapping to matrix operations, it is not very convenient to solve problems such as error calibration and speed and force. The spin method can significantly simplify the compilation of the calculation program and can simultaneously process the free vector and the line vector. The use of this method not only makes the research in this area less difficult, but also makes it clearer.
    In addition, since the machine tool processing system is a very complicated processing technology system, although its research has been a long history since its inception, there are still many difficult problems that are not well quantified. The leading role is still the empirical and experimental data; at the same time, its various components have a very strong connection, and various connection factors are complicated. This brings considerable difficulty to the virtual work. In particular, the effect of dynamic errors on the quality of the processing is very large. Variations in vibration and processing temperatures will play a critical role in roughness over a certain range. It has become a generally accepted research strategy to use a simplified method to decompose it into relatively independent components.

4 Conclusion

In China, research on virtual manufacturing technology has been carried out relatively early and has achieved certain results. However, research on virtual machine tool processing systems has not been reported. Based on the in-depth study of some key technologies of the virtual machine tool processing system, we completed a software system for the virtual machine tool processing system based on turning machining. The software system has the functions of complete NC code conversion, virtual processing and processing quality monitoring, which has certain practical significance. Research on virtual machine tool processing systems for multi-axis machine tools is currently underway. Focusing on the characteristics of multi-axis machine tools and the characteristics of machined workpieces, we focus on the description of workpiece properties, the modeling of cutting forces, the description and detection of surface contours after workpiece machining, and the research of Agent technology.
The research of Agent-based technology is very valuable for the establishment of a software tool such as virtual machine tool processing system. Practice has shown that Agent-based architecture will play a huge role in virtual manufacturing and distributed networked manufacturing.

Check Valve

The check valve is used in the piping system, its main function is to prevent the backflow of the medium, prevent the pump and its driving motor from reversing, as well as the release of the medium in the container.


Check valves can also be used to feed pipes where the pressure may rise to exceed the pressure of the main system. Check valve according to the different material, can be applied to a variety of media pipeline.


The check valve is installed on the pipeline, which becomes one of the fluid components of the complete pipeline. The opening and closing process of the valve disc is affected by the transient flow state of the system in which it is located. In turn, the closing characteristics of the disc have an effect on the fluid flow state.

Check Valve,Hydraulic Check Valve,Check Valve Types,Ball Check Valve

WUXI KVC-VALVE , https://www.kvgatevalve.com