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Analysis of the global development of CNC machine tools

the world's advanced manufacturing technology increases the resistance to microcracks. The continuous rise of manufacturing technology, the application of ultra-high speed cutting, ultra precision machining and other technologies, the rapid development of flexible manufacturing systems and the continuous maturity of computer integrated systems have put forward higher requirements for CNC machining technology. In order to adapt to this situation, CNC machine tools are developing in the following aspects

compound machining machine tools based on turning

this kind of machine tools integrates the process methods of milling, drilling and tapping, boring, grinding, gear hobbing and gear shaping on the basis of horizontal and vertical turning centers, becoming horizontal or vertical turning and milling compound machining machine tools. Representatives include M65 and m60-g of wflmilltuntechnologies in Austria; 100 Ⅲ, 200 Ⅲ, 300 Ⅲ series, qtn100ms, 250msy, 350m series of Mazak company in Japan; Traubtnx65 of German in-dex company; Twin65 and other horizontal turning milling machine tools of DMG company

the M65 horizontal turning milling machine tool exhibited by Austrian wflmilltuntechnologies in the exhibition is representative. The overall layout of the machine tool adopts the traditional horizontal lathe. The machine bed adopts the 60 ° inclined structure with high rigidity. The guide rail is a specially designed large-size linear guide rail with high rigidity and excellent vibration resistance. The left end of the lathe bed is a turning spindle box with c-axis function. The right end is the tailstock device. The upper part of the inclined lathe bed is a turning, milling and boring spindle device, which can perform linear motion and swing rotation motion of axis B along the longitudinal (Z axis), transverse (x axis) and radial (Y axis). In addition, axis B can be divided by 2.5 ° and has the ability to perform cyclone turning and milling rough machining. The lower part of the inclined lathe bed is a center support which can be mechanically controlled in the longitudinal and transverse directions. It is used to support the workpiece when the tailstock device cannot be used for end face and bore hole processing. At this position, m60-g is a turning turret with double disc cutters, which can participate in the linkage machining in the longitudinal (z1) axis and transverse (x1 axis). Therefore, the machine tool has the function of X, y, Z, B and C multi axis interpolation linkage. Under the condition of no human intervention, it can carry out turning, drilling, milling, grinding, gun drilling, internal and external tooth processing, turning milling, arc milling and other processing tasks. The machine tool is equipped with a wear-free and maintenance free disc type tool magazine with up to 120 tool positions behind the spindle box to replace the traditional chain type tool magazine, which can store tools up to 900mm and weighing up to 20kg. The tool change position is located above the spindle of the spindle box at the left end of the machine tool. In order to reduce the non productive time waste caused by the back and forth movement of the turning and milling spindle during tool change, the tool change position is programmed in the full longitudinal stroke and placed in the program library. The second tool support accessory configured under the turning and milling spindle of the machine tool adopts a unique and solid dovetail groove structure, which can be installed with large tools that are much larger than the standard tool size, such as deep hole drill bar, WFL series boring bar, integral drill bit, inner cavity processing power tool and special profile boring tool. A tool change table is set above the spindle at the right end of the machine tool, which can automatically access up to two large tools with a length of 1550mm and a weight of 150kg. Deep hole boring bar and inner cavity processing power tools can be loaded with a variety of processing tools, which can be directly taken from the left tool magazine, and can be operated by an independent machine sliding door without interrupting processing. When machining the inner and outer circles of the workpiece at the same time, it can achieve very high coaxiality and ensure the position accuracy of boring and milling surfaces

composite machining machine tools based on milling

this kind of machine tools integrate the process methods of turning, drilling and tapping, boring, grinding, gear hobbing and gear shaping on the basis of horizontal machining centers and vertical machining centers to become horizontal or vertical milling and turning composite machining machines. For example, the integraxe-800v/5 and e-1550v10 horizontal milling and turning compound machine tools of Mazak company in Japan add the rotary turning function to the workbench of the five axis horizontal machining center, which can realize the complete machining of turning, milling and other processes for circular disc parts under one-time clamping. The inte-grexe-500hs vertical milling and turning compound machining machine tool is equipped with a rotary spindle with a chuck at the left and right ends of the machine tool. The chuck at the right end can be expanded and retracted in the axial direction, which can carry out top clamping processing for long shaft parts, and can also carry out turning, milling and other processes for two short shaft parts at the left and right ends at the same time

high speed and high precision

speed and precision are two important indicators of CNC machine tools, which are directly related to processing efficiency and product quality

at present, the CNC system adopts a processor with higher number of bits and higher frequency to improve the basic operation speed of the system. At the same time, the ultra large scale integrated circuit and multi microprocessor structure are adopted to improve the data processing ability of the system, that is, to improve the speed and accuracy of interpolation operation. The linear servo feed mode, which uses the linear motor to directly drive the worktable of the machine tool, has excellent high speed and dynamic response characteristics. Feedforward control technology is adopted to greatly reduce the tracking lag error, so as to improve the machining accuracy of corner cutting

in order to meet the requirements of high-speed machining based on the internal structure analysis of the experimental machine, the CNC machine tool adopts the structure of combining the spindle motor and the spindle of the machine tool, realizing the integration of the variable-frequency motor and the spindle of the machine tool. The bearings of the spindle motor adopt the forms of magnetic bearing, hydrostatic bearing or ceramic rolling bearing. At present, ceramic tools and diamond coated tools have been applied

multi functional machining centers equipped with automatic tool change mechanism (the capacity of tool magazine can reach more than 100). Various machining centers equipped with automatic tool change mechanism can realize multiple processes such as milling, boring, drilling, turning, reaming, reaming, tapping, etc. on the same machine tool at the same time. Modern CNC machine tools can adopt multi spindle and polyhedral cutting, that is, different ways of cutting different parts of a part at the same time. Because the CNC system adopts multi CPU (computer center processing device) structure and hierarchical interrupt control mode, it can simultaneously process and program on the same machine tool to realize the so-called "foreground processing, background processing". In order to meet the requirements of flexible manufacturing system and computer integrated system, the CNC system has a long-distance serial interface, which can even be connected to realize the data communication between CNC machine tools, and can also directly control multiple CNC machine tools

introduction of adaptive control technology

intelligent modern CNC machine tools will introduce adaptive control technology to automatically adjust working parameters according to the changes of cutting conditions, so as to maintain the best working state in the machining process, so as to obtain higher machining accuracy and better surface roughness, and improve the service life of tools and production efficiency of equipment. It has the functions of self diagnosis and self repair. During the whole working state, the system can self diagnose and check the CNC system itself and various equipment connected to it at any time. In case of any fault, take measures such as shutdown immediately, and give a fault alarm to prompt the location and cause of the fault. It can also automatically take the fault module offline and connect the standby module to ensure the requirements of the unmanned working environment. In order to achieve higher requirements of fault diagnosis, the development trend is to use artificial intelligence expert diagnosis system

the CNC system will adopt a more integrated electrical circuit called analyzer circuit chip, and use large-scale or super large-scale special and hybrid integrated circuits that can communicate with the company to reduce the number of components and improve reliability. Through the software of hardware functions, it can meet the requirements of various control functions. At the same time, the modularization, standardization, generalization and serialization of the machine tool body with hardware structure are adopted, which not only improves the hardware production batch, but also facilitates the organization of production and quality control. It can also realize fault diagnosis and alarm for hardware, software and various external equipment in the system by automatically running various diagnostic programs such as startup diagnosis, diagnosis and off-line diagnosis. Use the alarm prompt to eliminate the fault in time; Using fault-tolerant technology, the "redundancy" design is adopted for important components to realize fault self recovery; Various testing and monitoring technologies are used to automatically carry out corresponding protection in case of production over travel, tool damage, interference, power failure and other accidents

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