Development and application of the hottest intelli

2022-09-21
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Development and application of intelligent machining technology

concept of intelligent machining technology

1 proposal of intelligent machining problems

in production practice, the NC machining process is not always in an ideal state through this kind of method, but with the material going to Jinan gold ring stiffness special experimental machine can detect the creep limit of metal, except for a variety of complex physical phenomena, such as machining geometric errors, thermal deformation Elastic deformation and system vibration. The problem often occurs in the processing process is that the "correct" program generated by part model programming may not be able to process qualified and high-quality parts. It is precisely because of the above complex physical phenomena that the shape accuracy and surface quality of the workpiece can not meet the requirements. In the production and manufacturing of products, once the processing process design or process parameter selection is unreasonable, it will lead to poor product processing surface quality, insufficient equipment processing capacity, and the service life of machine tool components and cutters will also be affected

the reason for the above problems is that in the traditional machining process, only CNC machine tools or machining process itself are often considered, but there is a lack of comprehensive understanding of the interaction mechanism between machine tools and machining process. This interaction often produces unpredictable effects, which greatly increases the difficulty of processing process control. In order to solve the above problems, we must change the traditional concept, consider the machine tool and the machining process together, model and simulate the interaction, and then optimize the machining process, improve the design of the machining system, and reduce the defects in the machining process. At the same time, with the help of advanced sensor technology and other related technologies, CNC machine tools are equipped to timely perceive and predict the working conditions in the processing process, and evaluate and adjust the parameters and processing status in the processing process, so as to achieve the purpose of economically and effectively improving the shape accuracy and surface quality

2 concept of intelligent processing technology

intelligent processing technology realizes the modeling, simulation and prediction of the processing process and the monitoring and control of the processing system with the help of advanced detection, processing equipment and simulation means; At the same time, the existing processing knowledge is integrated, so that the processing system can automatically optimize the processing parameters and adjust its own state according to the real-time working conditions, so as to obtain the best processing performance and the best processing quality and efficiency. The technical connotation of intelligent processing includes the following aspects

(1) machining process simulation and Optimization: Aiming at various parameters that affect the machining quality of parts in the machining process such as machining process, cutting parameters, feed speed, etc., through the simulation based on the machining process model, the parameters are predicted and optimized, and the optimized machining process control instructions are generated

(2) process monitoring and error compensation: various sensors, remote monitoring and fault diagnosis technologies are used to monitor the vibration, cutting temperature, tool wear, machining deformation, as well as the running state and health status of equipment in the machining process; According to the pre established system control model, the machining parameters are adjusted in real time, and the errors produced in the machining process are compensated in real time

(3) communication and other auxiliary Intelligence: transmit real-time information to remote monitoring and fault diagnosis system and workshop management MES system. The above process is described in Figure 1

research status of intelligent processing technology

intelligent processing technology has become the main technical feature of modern high-end manufacturing equipment and an important development direction of national strategy. It has attracted much attention in developed countries such as the United States and Europe. In recent years, a lot of funds have been invested in research. Typical research plans include PMI plan, smpi plan and next plan

1pmi program

pmi program was initiated by the academic group international society of production engineering (CIRP). CIRP established a joint research group in 2003 to conduct research in this field, and the participating institutions include relevant member units of CIRP and universities in Germany, France and other countries

The research contents of PMI mainly include: the establishment and research of processing process model, the research of equipment monitoring, and the research of the interaction between process and equipment connecting the two. Among them, the research on machining process modeling includes the research on cutting, grinding and forming processes, equipment monitoring includes the research on Intelligent spindle system, tool wear prediction, etc., and the research on the interaction between process and equipment includes the description, simulation and optimization of interaction, as well as the research on the structural behavior of machine tool system

2smpi program

smpi is an intelligent processing system research program supported by the U.S. government. The plan was put forward in 2005, and the US Department of defense has allocated more than 10million US dollars to support the research. The participating units include government departments such as NASA and ardec, companies such as GE, Boeing and techsolve, and scientific research institutions such as the University of Maryland and Aachen University of technology. The research content of SPMI includes local activities based on equipment and global activities based on process, as shown in Figure 2

3next plan

next plan is a research plan for the next generation production system supported by the European Commission's Sixth Framework R & D plan, which is managed by the European machine tool industry cooperation committee (CECIMO). The participating units include machine tool manufacturing enterprises such as Siemens and darnobat group, end-user enterprises such as Bosch and Fiat, as well as research institutions such as the Institute of machine tool and production engineering (WZL) of Aachen University of technology, Germany, the Institute of production engineering of the University of Hannover (if otherwise, the control of unclear control effect is still blind control w), Budapest University of technology and Economics (Bute) and so on

The third part of the next plan involves the research on the cutting-edge of manufacturing technology, mainly including processing simulation and new technology development, new machine tool research and development, light structure and machine tool component research and parallel machine tool research and development. Machining simulation includes surface machining quality detection and cutting parameter optimization, milling/turning process modeling and simulation, ultra precision machining technology and so on. The research and development of new machine tools includes the research and development of high-speed machine tools, open CNC systems and the application of optical fiber sensors. Machine tool components include light material machine tool components, rotating shaft accuracy measurement and aerostatic bearing research

key technology of intelligent machining

1 Simulation and optimization of machining process

simulation and optimization of machining process involves the analysis of servo characteristics of CNC system, machine tool structure and its characteristics, analysis of dynamic cutting process, as well as the optimization of cutting parameters and prediction of machining quality on this basis

(1) machine tool system modeling

through the structural modeling and optimization design of the machine tool, the operation accuracy of the machine tool can be improved, the positioning and operation errors can be reduced, and the error can be predicted and compensated at the same time. The modeling and analysis of the spindle system can predict the dynamic stiffness of the tool at different speeds according to the spindle structure, and optimize the selection of processing parameters based on the results of processing stability analysis, so as to improve the processing quality and efficiency. In the aspect of cutting tools, through the analysis and optimization design of tool structure, a greater stable cutting depth can be obtained in the machining process; Through the optimization of tool load, the changing optimal feed can obtain higher machining efficiency and economic benefits

(2) cutting process simulation

cutting process simulation with the help of various advanced simulation means, the chip formation mechanism, force and heat distribution, surface morphology and tool wear in the machining process are simulated and studied. The optimized cutting parameters are selected through simulation to improve the surface machining quality

(3) process optimization

with the help of pre established simulation models and optimization methods, or existing experience and knowledge, optimize the cutting parameters and machine tool motion in complex machining conditions and machining processes. For example, in the machining of blisk, the cutting state and stability under different working conditions are predicted through the established analysis model, and the appropriate tool attitude, cutting depth and line spacing are optimized to ensure the stability of the machining process and obtain high blade surface machining quality

(4) processing quality prediction

machining quality prediction uses visual methods to predict the surface texture and machining quality formed in the cutting process, providing support for the optimization of cutting parameters, so as to further improve the machining quality of the workpiece surface, as shown in Figure 3

from the current research and development, simulation is developing towards the direction based on time-varying and physical models, and the optimal results in the theoretical sense can be obtained through simulation. However, due to the imperfection of the current model itself, the complexity of the processing process and the diversity of processing forms, the existing simulation methods are still difficult to meet the needs of practical engineering. At the same time, due to the sudden situation of materials, machine tools and system status in the processing process, the processing process must be monitored in real time, and error compensation and on-site control must be carried out

2 process monitoring and error compensation

processing process monitoring uses advanced equipment to monitor and control the processing conditions, workpiece, tool and equipment status in real time, and feeds back the monitoring data to the control system for data analysis and error compensation. The performance characterization of processing equipment is the premise of process monitoring. The performance parameters of equipment can be measured regularly through testing equipment and sensors, and the system performance parameter base or knowledge base can be updated in time. In the machining process, the force, vibration, noise, temperature, workpiece surface quality, etc. in the machining process can be monitored in real time with the help of various sensors, sound and video systems. According to the monitoring signals and multiple models established in advance, the machining state, tool wear, machine tool working state and machining quality can be determined, and then the automatic optimization and error compensation of cutting parameters can be carried out. At the same time, the health status information of the equipment can be transmitted to the workshop management (maintenance department, procurement department, etc.) through the communication system, and timely maintenance can be carried out according to the health status, so as to ensure the processing quality and reduce the downtime

3 intelligent machining machine tool

intelligent machining machine tool detects the strain, vibration, thermal deformation, etc. produced by the machine tool in the machining process with the help of micro sensors, and transmits them to the pre established model. According to the model, data analysis and error compensation are carried out, so as to improve the machining accuracy, surface quality and machining efficiency. In addition, intelligent machine tools can also carry out man-machine dialogue to realize remote diagnosis of system faults. Typical intelligent processing machine tools include products of Mikron, Mazak, Okuma and other companies

intelligent machining technology application

1 NC machining process model up to now, most NC programming systems generate NC machining trajectory based on product geometric model, and the main problem to be solved is the planning of tool path and the processing of motion interference

this NC programming technology is difficult to solve the kinematics of high-speed machining and the dynamics of complex process system of machine tools in high-speed machining of thin-walled parts. The process system has time-varying characteristics in the machining process - its dynamic response is closely related to the modal changes of the system caused by factors such as material removal in the machining process. This phenomenon has a particularly significant impact on the quality and stability in the high-speed machining of thin-walled parts

in order to solve the above problems, it is necessary to establish a machining process model and carry out theoretical research on the new generation of NC machining programming based on this model. The machining process model includes the geometric and kinematic models of the complex process system and its subsystems composed of machine tool tool workpiece fixture

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