The research on parallel machine tools began in 1965 when Stewart proposed the famous Stewart platform mechanism. From then on, the virtual machine tool research based on Stewart parallel mechanism was started. But at the beginning, people are still only staying on the theoretical analysis of this kind of institution. In 1994, the parallel 6-legged machine tool (also known as the parallel machine tool), which was exhibited for the first time at the IMTS Expo in Chicago, USA, and which caused a sensation in the world, has gradually cooled down around the world after a three-year global follow-up wave. This is because parallel machine tools have a series of problems in theory and practice, which are difficult to solve in a short period of time. At present, many companies and research institutes at home and abroad are studying virtual axis machine tools. China's parallel machine tool research started late, but the results are remarkable. Previous page Flat Pack Container House,Solar Container Home,Off Grid Container Home,Luxury Shipping Container Homes Suzhou Daxiang Container House Co, Ltd , https://www.dx-house.com
Among them, Tsinghua University is one of the earliest units in China to start research on virtual axis machine tools. It has conducted in-depth research on virtual axis machine tools and various related fields, and cooperated with Tianjin University on December 25, 1997 to jointly develop China's first. A large prototype of a boring and milling virtual axis machine tool - VAMT1Y. In the key technology of virtual axis machine tool design theory and prototype construction, it has reached the international advanced level, and some of the theoretical results are internationally pioneered.
Three different types of machine tools jointly developed by Kunming Machine Tool Co., Ltd., Jiangdong Machine Tool Plant and Dalian Machine Tool Plant have been developed and exhibited at CIMT in 2001, and are expected to be commercialized in the near future. The XNZ63 virtual axis machine tool jointly developed with Kunming Machine Tool Co., Ltd. can realize multi-coordinate linkage CNC machining, assembly and measurement of various functions, and can better meet the processing of complex special parts. Its comprehensive index has reached the international advanced level. A gantry-type virtual axis machine tool jointly developed with Jiangdong Machine Tool Plant. The structure adopts a double-column gantry table mobile type, which can complete 4 coordinate linkage. The DCB-510 five-axis linkage series-parallel machine tool jointly developed with Dalian Machine Tool Plant can realize the movement in the X, Y and Z directions through the parallel mechanism, and realize the rotation of the spindle head in the A and C directions by the traditional series connection.
In addition, the parallel machine tool designed by Tianjin University and jointly developed with Tianjin No. 1 Machine Tool Plant has also achieved success and reached a practical level. Harbin Institute of Technology and Qiqihar Second Machine Tool Enterprise Group jointly developed the BJ-1 parallel machine tool. The DSX5-70 three-pole virtual axis machine developed by Northeastern University is a five-degree-of-freedom virtual axis machine consisting of a three-degree-of-freedom parallel mechanism and a two-degree-of-freedom series mechanism.
The Galaxy-2000 virtual axis machine tool jointly developed by the National University of Defense Technology and the Hong Kong University of Science and Technology is a parallel six-degree-of-freedom machine tool developed from traditional parallel machine tools. While maintaining the advantages of the original parallel mechanism, such as high stiffness, In addition to high precision and high speed of motion, the range of motion of the machine tool is expanded by the variable mechanism.
Foreign countries, Sweden Neos Robotics company adopted the parallel plus series solution, starting from the low-level application, gradually accumulating experience and financial resources, developing to high-level applications, and adopting the correct measures such as the three-pole central tube, the parallel connection Machine tool products have already entered practical use. The 6x machine developed by the Fraunhofer Machine Tool and Forming Technology Research Institute in Germany is suitable for high-speed machining of molds. The main technical parameters are: workbench: 630×630, X, Y, Z stroke are 630mm, and the two rotational degrees of freedom are 30°, the maximum speed of the spindle is 3000r/min, the power is 16kW, the maximum feed speed of the leg is 30m/min, and the acceleration is 10m/s.
The US branch of Index of Germany used parallel machine tools for lathes to produce the "inverted car" of the V100 three-bar parallel mechanism (that is, the spindle and the workpiece move on the X and Z axes, and the tool does not move, can be converted back Knife, but does not make any vertical movement of the vertical lathe, China is known as "inverted car"). It has the following advantages: 1 compact shape. The lathe is not like the machining center, and the moving range of the workpiece relative to the tool is small, which overcomes the weakness of the effective utilization of the space of the parallel mechanism. 2 lathes generally only need two degrees of freedom (X and Z axis), and now use three-bar geometry to obtain three degrees of freedom of X, Y, and Z. One degree of redundancy can be used for free loading and unloading. In addition, in order to increase the rigidity, Index uses a double rod mechanism with two rods acting as a rod, which is similar to the structure of Tianjin First Machine Tool Plant in China.
Hexel Corporation of the United States uses a six-bar parallel structure as a separate component for turret milling machines. This upgrades low-cost conventional milling machines to 5-axis simultaneous milling machines. The Swiss Technical Institute (ETH), the Machine Tool and Manufacturing Technology Institute (IWF) and the Robotics Institute (IFR) have also jointly developed the Hexaglide virtual axis machine tool called IWF. So far, we know that the virtual axis parallel machine tool has two degrees of freedom, three degrees of freedom, three degrees of freedom of the law, four degrees of freedom of pure three degrees of freedom, five degrees of freedom of symmetry and six degrees of freedom. Virtual axis CNC parallel machine tools are mostly used for virtual axis six-degree-of-freedom CNC machine tools.
The research direction of parallel machine tools is to study the parallel machine tool degree of freedom calculation, the type of motion pair, the type of hinge and the analysis, modeling and simulation of kinematics. The research of parallel machine tool motion space includes motion space analysis and simulation, reachable workspace solution (such as numerical solution method, spherical coordinate search method, etc.), machine tool interference calculation and position analysis.
The structural design of the parallel machine tool includes many contents, such as the overall layout of the machine tool, safety mechanism design, CNC system design (including CNC platform construction, CNC system programming, CNC machining process simulation, etc.), parallel machine tool stiffness, accuracy, flexibility, dexterity Research. The characteristics of the parallel circuit of the parallel mechanism make the parallel machine tool have higher rigidity than the traditional series structure machine tool, but the coupling problem caused by this characteristic is relatively troublesome in the dynamic analysis, so it should be paid enough attention to its research. .
The research on the precision of parallel machine tools is still an international problem, including machine tool system hardware research and precision design and precision description before machine tool manufacturing, system output precision research and output data processing and precision evaluation after machine tool manufacturing. The study of the compliance of parallel machine tools includes flexibility analysis, compliance evaluation indicators and their distribution in the workspace. The dexterity mainly studies the dexterity indicators and their distribution. Parallel machine tool error research includes error analysis, modeling and error accuracy assurance, and measurement system design. Parallel machine tool module design and creation. According to the space type and plane type of workpiece machining, parallel machine tools are divided into two types: space type parallel machine tool and plane type parallel machine tool.
Parallel machine tools can be divided into the following functional modules according to their functions and structures: 1 execution module; 2 base module (static platform module); 3 moving platform module; 4 rack module; 5 positioning module; 6 drive module; Display module; 8 lubrication and cooling module. Research on a new virtual axis CNC machine tool. The virtual axis CNC machine tool is “machine tool to be made by mathematics†because the design and operation of this machine tool requires very complicated mathematical calculations and reasoning. At present, some theoretical conclusions have been made on the theoretical research of the Stewart platform. It is necessary to further study the comprehensive analysis of the Stewart platform to provide a theoretical basis for the development of virtual axis CNC machine tools. The research of parallel machine tool control includes high-speed, high-precision control algorithms, direct control of tool motion trajectory, and open CNC system. The biggest feature of the virtual axis machine tool is that the mechanical structure is simple and the control is complicated. Therefore, the research in this aspect plays an important role in the research of the parallel machine tool.