Around the requirements of quality, efficiency and process change, China's machinery manufacturing process equipment -- mainly numerical control equipment in the technical level has undergone profound changes. The functions of CNC machine tools are constantly enriched, and the process, process centralization and compound technology are adopted. Machine tools in the structure of the layout and the application of new materials have new development; Numerical control technology in the open, intelligent, network, high speed and high precision has made new development. Its purpose is to improve production efficiency, improve accuracy, ensure quality and achieve maximum benefit.
The constant pursuit of high quality and high efficiency is the eternal theme and goal of the research of machinery manufacturing industry and the source power to promote the development of its process and equipment. Process requirements and changes are the basis and foundation for the development and innovation of machinery manufacturing process equipment technology.
Domestic CNC machine tools through 50 years of development of the long course, in the last 10 years to come to the rapid development, especially by the government's attention, set up a major technical research special, effectively promote the development of CNC machine tools.
At present, domestic CNC machine tools are available for more than 1500 varieties, covering CNC metal cutting machine tools, CNC plate processing machine tools (CNC stamping machine tools, CNC laser machine tools, flame cutting machine tools, etc.), CNC electromachining machine tools, industrial robots, CMM, etc., the variety is basically complete. In 2010, the number of CNC metal cutting machine tools was about 1.5 million (including more than 400,000 imported machines), and the annual production of metal cutting machine tools alone was more than 160,000. From January to October 2011, the total output reached 218,000, and the annual output reached about 250,000. The number and value of domestic brand CNC machine tools account for more than 50% of the domestic market. New progress has also been made in the five axis linkage and composite machining center, numerical control system and other supporting technology products, which represent the advanced technology level. This paper mainly discusses the development and gap of numerical control technology.
Pursue high productivity
In order to pursue high productivity of mechanical manufacturing, promote numerical control equipment to processing compound (process compound and process compound), high speed, intelligence, network, process parameter optimization direction development.
Numerical control machine tool compound processing, mainly refers to the process centralization, compound and process compound.
1.1 Process centralization and compound
Since the end of 1970s, with the three linkage machining center began to be used for machinery manufacturing, began to enter the era of machining process centralization. In the 1980s, China's self-made three linkage processing center also began to be used in mechanical manufacturing, mainly for box parts and mold processing. In one loading card can realize boring, milling, drilling, tapping and other processes, improve the processing efficiency and accuracy.
2000~2011 is China's CNC machine tool development of the fastest period. During this period, we have independently developed five axis linkage machining center, turning and milling compound machining center, turning and milling compound machining center and grinding compound machining center. Some domestic manufacturers have been able to provide five-axis linkage and multi-axis linkage composite machining centers, but some are major special products, to be further commercialized and industrialized.
1.1.1 Five-axis linkage machining center
The domestic production of five axis machining center manufacturers are increasing. Such as Shenyang machine tool factory production of GMC2590 μbridge five axis linkage machining center, VM22120 μvertical five axis machining center, VMC05656E gate type five axis machining center, HS664RT five axis high-speed machining center; Dalian machine produced the VDM500 five axis vertical machining center; XKR32G five-axis linkage machining center and XKH800 five-axis linkage blade machining center produced by Beijing Mechanical and Electrical Institute; Ji 'nan two machine tool production of XV2525×60 overhead five-axis linkage machining center can achieve a complete installation of parts of the milling, boring, drilling, reaming, tapping and other processes.
The development of five axis linkage machining center has two key core components of technical difficulty, one is a double swing Angle universal machining head; One is a biaxial rotary table (see figure 2). These two components have also been developed by domestic manufacturers, but they need to be further perfected and commercialized. Double swing Angle universal machining head for large machine tools, double swing axis rotary table for small machine tools. At present, both components use direct drive torque motors and are equipped with encoders to improve dynamic performance and accuracy.
Double - swing - Angle universal machining head technology is more difficult. The main parameters of a direct-drive double-swing universal head developed by a domestic manufacturer are as follows:
Limit torque: Axis A 500~1000Nm (optional), Axis C 660~2000Nm (optional);
Positioning accuracy: ±2 ", ±2.5 ", ±3 ", ±5 "(optional);
Absolute encoder resolution: 26 bits, 29 bits (optional);
Angle range: A axis ±110°, C axis ±360°.
Our country has not formed the double swing Angle universal head serialized goods, and the international company like German CYTEC can supply serialized goods.
1.1.2 Turn-milling compound machining center
The compound machining center of turning and milling is developed on the basis of numerical control lathe and on the basis of vertical machining center. Such as Nanjing CNC Machine Tool Co., Ltd. production of CK1840S turning and milling compound machining center is developed on the basis of CNC lathe. The machine has double spindles, double tool holder, double C axis and W axis, a total of 7 axes, divided into two groups of three linkage full closed-loop control. The resolution of C-axis reached 0.001°. The machine can complete many processes such as turning, dividing and eccentric drilling, positioning milling and so on on the rotating parts in one loading, that is, one turning and milling compound machining center can complete the processing procedures of two CNC lathes, which improves the efficiency by 1 times, and improves the accuracy because it can reduce the error of secondary installation. The CX110 vertical turning and milling compound machining center produced by Anyang Xinsheng Machine Tool Co., Ltd. is developed by adding turning device on the basis of vertical machining center. The machine has the functions of turning, boring, milling, drilling, reaming, tapping and so on. It can realize the five-side machining with five-axis linkage. In addition, Dalian Machine Tool developed the VHT800 five-axis turn-milling compound machining center, CHD25 five-axis turn-milling compound machining center; WHGS7000 turning and milling compound machining center, developed by Wuhan Heavy Machine Tool Group Co., Ltd., can also realize one time loading of parts, and complete multi-process processing of complex structure and complex surface parts.
1.1.3 Turn-milling and grinding compound machining center
HTM-V120L CNC vertical turning, milling and grinding compound machining center developed by Ningbo Haitian Jigong Machinery Co., Ltd. The workpiece can be loaded once to complete turning, milling and grinding multiple processes, but also can carry out heavy cutting high-precision processing, suitable for large bearing processing.
1.1.4 Turning and milling and grinding gear machining compound center
Some turning centers are equipped with a second spindle and a grinding wheel shaft on the rotary tool rest. In the second spindle can also be installed on the gear cutting tool processing shaft gear and worm gear, and can even achieve five axis linkage, with finger milling cutter processing arc gear and bevel gear.
1.1.5 Grinding composite machining center
The H405-BE CNC compound grinder developed by Shanghai Machine Tool Works Co., Ltd., adopts Siemens CNC system to control feed of grinding wheel and worktable, rotation of head spindle and grinding wheel, and has the functions of cylindrical grinding and automatic dividing of grinding wheel and so on. Automatic cycle grinding of inner and outer circle and end face can be completed by one loading card.
1.2 Process composite
Technology compound processing is not seen much in China. VTM3501 vertical turning and milling and laser quenching compound machining center developed by SCHIESS company of shenyang machine tool group. Can realize turning, boring, drilling, tapping, milling, grinding and laser quenching and other processing. The machine tool combines the cold processing technology with the hot processing technology, greatly improving the production efficiency.
According to the relevant data, a five-axis linkage processing center or multi-procedure composite processing center than three linkage processing center can improve the production efficiency more than 1 times. Multi-axis linkage and composite machining can not only improve the production efficiency, but also reduce the error of secondary installation, and improve the precision and quality. Five axis linkage machining center and multi axis linkage composite machining center can be produced in China, but some of the major breakthrough products need to be further commercialized and industrialized.
2 high speed
In order to realize high speed CNC machining, direct drive technology is adopted in the transmission system, and high speed operation processing technology is adopted in the numerical control system.
2.1 Direct drive technology
In order to improve production efficiency, the transmission parts of CNC machine tools gradually adopt direct drive technology. The spindle is directly driven by the electric spindle, the feed is driven by the linear motor, the rotary table is directly driven by the torque motor, and the swing Angle universal head of the five-axis linkage is directly driven by the torque motor.
As early as 2000 years ago, China began the research and development of direct drive technology. At present, Shandong Bote Seiko Co., Ltd. and Luoxian Science and Technology Co., Ltd. can produce and supply motorized spindle series products, and Beijing Shouke Kage Electric Technology Co., Ltd. has also developed linear motors. The user to the above product performance and the technical index response is good, but still has the gap compared with the foreign advanced level.
At present, the foreign advanced motorized spindle unit speed up to 15000~100000r/min, the general use of 40000~50000r/min more. The feed components with direct drive of linear motor require not only high speed but also high acceleration and deceleration. Fast moving speed up to 60~200m/min, acceleration up to 2g~10g; The working feed can reach more than 60m/min, and the acceleration can reach 1g~2g. The feed speed of the traditional ball screw drive is 20~30m/min, and the acceleration is 0.1g~0.3g. Under normal circumstances, the feed speed is about 30m/min. The feed speed of direct drive is more than 1 times higher than that of ball screw drive, thus reducing auxiliary time and improving production efficiency. Linear motor drive technology has a broad application prospect, but it needs to further reduce the cost and solve the problem of heating.
At present, numerical control machine tools developed by some manufacturers in our country have adopted direct drive technology. For example, XHV2525×60 elevated five-axis high-speed boring and milling machining center developed by Jinan No. 2 Machine Tool adopts linear motor drive for X and Y axes. The XKR32G five-axis linkage machining center developed by Beijing Mechanical and Electrical Institute adopts torque motor direct drive for two rotating shafts of the worktable, and the spindle of XKH800 five-axis linkage blade machining center adopts electric spindle direct drive, etc. Domestic CNC machine tools using direct drive technology is still in the primary stage, is not common, there is still a certain gap in performance. More than 1500 CNC machine tools produced by German DMG company each year adopt direct drive technology. The FZ12KS five-axis machining center produced by German Jelong Co., Ltd has the spindle speed of 40000r/min, tool change time of less than 0.6s, feed acceleration of 1g~2g, fast feed speed of 90m/min, and workpiece exchange time of 2s.
2.2 High-speed computing and processing technology of CNC system
The high speed direct drive feed system requires fast operation speed, short sampling period and sufficient preprocessing ability of advance path plus (minus) speed optimization program segment. More advanced numerical control systems can preprocess thousands and tens of thousands of program segments. Acceleration and deceleration optimization can be carried out according to G code of pre-processing buffer during multi-axis linkage control. In order to ensure the machining speed, the sixth generation CNC system can change the feed speed 2,000 to 10,000 times per second.
For nc machine tools machining efficiency and machining quality, automatic programming nc system not only has the, feedforward control, fuzzy control, self-learning control, automatic generation of process parameters, 3 d cutting tool compensation, intelligent functions such as dynamic compensation movement parameters, and a fault diagnosis expert system, make the diagnosis and fault monitoring function more perfect. Intelligent servo drive system, can automatically sense the load changes, automatic optimization and adjustment of parameters.
Domestic NC system is developing towards the intelligent direction, introducing some intelligent technology. For example, the central China "Zhonhua 8" and Kendi K1000TIV type, CNC system has self-diagnosis function, real-time state display and fault real-time alarm and other intelligent functions, and are further enriched and improved intelligent technology.
Foreign such as Siemens, Fanuc, Mitsubishi production of numerical control system into the intelligent technology is more rich. Domestic numerical control system still has many gap compared with it. For example, Siemens SINUMERIK828DBASICM has intelligent coordinate conversion function for cylindrical parts processing, and has SINUMERIKM dynamics process package, which contains all the functions of "fine surface", which can realize efficient processing and obtain the best surface quality. The 30I / 31I / 32I / 35I-ModelB series CNC system is the latest artificial intelligence nano level system, which can flexibly support the boring and milling machining center, CNC lathe multi-axis linkage composite machining machine tool, etc. Intelligent technology has great contribution rate to improve the production efficiency of CNC machine tools, so we must pay attention to it.
4. Open and networked
The opening of numerical control device can more easily realize intelligent networked manufacturing and effectively promote the improvement of production efficiency.
Open CNC device means that the hardware, software and bus are open to the user. The most important advantage of open CNC device is that it has better generality, flexibility, adaptability and expansibility, which can meet the requirements of users' secondary development.
4.1.1 Concept and openness of NC and CNC
At present, numerical control device mainly has NC and CNC2 kind. The numerical control device composed of hardware logic circuit is called NC device; By the computer hardware and software together composed of numerical control device is called CNC numerical control device. Hardware is the physical basis of software operation, and software is the soul of the whole CNC operation and function realization. NC is gradually being replaced by CNC.
CNC CNC device hardware in addition to the CPU, EPROM, RAM, there are position controller, manual input (MDA) interface, display (CRT) interface and PLC interface, so CNC CNC device is a
CNC software is divided into management software and control software 2. The management software is used to manage the input and output of part program, tool position system parameters, part program display, machine tool status fault diagnosis and alarm, etc. The control software consists of decoding, interpolation, operation, tool compensation, speed control, position control and other software.
Modern open CNC device is mainly developed on the PC platform CNC device. China's "Huazhong 8" CNC device adopts open hardware and software architecture based on multi-processor and bus technology. Hardware cross-platform, software can be replaced, with software and hardware multi-level open function. K1000TIV CNC device of Beijing K1000TIV adopts open PLC and provides debugging software to support secondary development of users. Guangzhou CNC GSK25I CNC device also uses the open PLC, support PLC ladder chart online editing, diagnosis and signal tracking functions.
4.1.2 Standards and specifications
Whether to realize the opening of numerical control device is closely related to the establishment of technical standards and norms. Numerical control technology was born more than 50 years, information exchange is based on ISO6983 standard, that is, the use of G, M code to describe how to process. Obviously, the standard can not meet the requirements of the rapid development of modern numerical control technology.
In the 1990s, Europe, America, Japan and other countries began to study and formulate the architecture specification of open numerical control device (OMAC, OSAC, OSAC), and developed the open numerical control device as a development strategy. In 2000, China also began to study and develop the open CNC device standard framework, but it is not perfect.
4.2 the net