Five directions and three gaps of domestic CNC mac

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The five directions and three gaps of domestic CNC machine tool technology

revolve around the requirements of quality, effectiveness and engineering to create a very professional and wide range of technological changes in the field of materials. China's machinery manufacturing process equipment - mainly if CNC equipment has undergone deep changes in the technological level. The functions of CNC machine tools are inexhaustible and rich, and the centralized and compound technology of processes and processes are adopted; Machine tools have made new progress in layout and utilization of new materials; CNC technology has achieved new growth in openness, intelligence, collection, high-speed and high-precision. Its goal is to improve production efficiency, improve accuracy, ensure quality and maximize efficiency

constantly seeking high quality and high efficiency is the permanent theme and goal of machinery manufacturing industry research, and it is the source power to promote the growth of its process equipment. The improvement of technology is the basis and basis for the growth, innovation and change of machinery manufacturing technology and equipment

domestic CNC machine tools have gone through a long process of growth for 50 years, and have achieved rapid growth in the past 10 years. In particular, they have received the attention of the authorities and set up a serious technical research project, which has effectively promoted the growth of CNC machine tools

at present, there are more than 1500 types of domestic CNC machine tools, covering CNC metal cutting machine tools, CNC plate processing machine tools (CNC stamping machine tools, CNC laser processing machine tools, flame cutting machine tools, etc.), CNC electrical processing machine tools, industrial robots, coordinate measuring machines, etc., and the types are basically complete. In 2010, the number of CNC metal cutting machine tools was about 1.5 million (of which more than 400000 were exported). The annual output of metal cutting machine tools alone exceeded 160000, reaching 218000 from January to October 2011 and 250000 throughout the year. The number and value of domestic brand CNC machine tools account for more than 50% of the international market. New progress has also been made in the five axis linkage and composite processing center, CNC parts and other supporting technological products that represent the advanced level of technology. This paper mainly focuses on the development and gap of CNC technology

seek high production rate

in order to seek high production rate of mechanical manufacturing, promote the growth of NC equipment to the target of processing compounding (process compounding and process compounding), high speed, intelligence, collection and process parameter optimization

1 compounding

NC machine tool compounding mainly refers to process centralization and compounding. The following table lists the standard experimental conditions and process compounding for enabling new chromatographic columns

1.1 process centralization and compounding

since the late 1970s, with the three linkage processing, it began to be used in mechanical manufacturing, and began to enter the centralized period of machining processes. In the 1980s, China's cheap three linkage processing center also began to be used in machinery manufacturing, mainly for box parts and mold processing. Boring, milling, drilling, tapping and other processes can be completed in one clamping, which improves the processing efficiency and accuracy

the period from 2000 to 2011 is the fastest growing period of CNC machine tools in China. During this period, the five axis linkage machining center, turning milling compound machining center, turning milling compound machining center and grinding compound machining center were independently opened up. Some international manufacturers have been able to supply five axis linkage and multi axis linkage composite processing centers, but some are serious special research products, which need to be further commercialized and capitalized

1.1.1 five axis linkage processing center

the number of international manufacturers producing five axis linkage processing centers is increasing. For example, gmc2590 produced by Shenyang Machine Tool Factory μ Bridge five axis linkage machining center, vm22120 μ Vertical five axis machining center, vmc05656e portal five axis machining center, hs664rt five axis high speed machining center; The vdm500 five axis vertical machining center produced by Da Nian Lian machine tool; Xkr32g five axis linkage processing center and xkh800 five axis linkage blade processing center produced by Beijing Electric Machinery Institute; The xv252560 overhead five axis linkage machining center produced by Jinan No.2 machine tool can complete multiple processes such as milling, boring, drilling, reaming, tapping and so on

there are two key points in the development of five axis linkage processing. The core components are very difficult to process. One is the double swing angle universal processing head; One is the double axis reverse expansion turntable (see Figure 2). International manufacturers of these two components have also opened up, but they need to be further perfected and commercialized. The double pendulum all-round machining head is used for large machine tools, and the double pendulum shaft reverse expansion turntable is used for small machine tools. At present, these two components adopt direct drive torque motor and are equipped with encoder to improve static function and accuracy

the technology of double swing all-round machining head is more difficult. The main parameters of a direct drive double swing angle all-round head developed by an international manufacturer are as follows:

rated torque: a-axis 500~1000nm (optional), c-axis 660~2000nm (optional)

positioning accuracy: 2 ", 2.5", 3 ", 5" (optional)

relative encoder discrimination rate: 26 bits, 29 bits (optional)

swing angle range: a-axis 110, c-axis 360

China has not yet formed a series of goods with double swing angle all-round head, but internationally, companies like Germany Cytec can supply series of goods

1.1.2 turning and milling complex machining center

turning and milling complex machining center has been fundamentally developed in both CNC lathes and vertical machining centers. For example, the ck1840s turning milling compound machining center produced by Nanjing CNC Machine Tool Co., Ltd. was fundamentally developed on the basis of CNC lathes. The machine tool has double spindles, double tool holders, double C axes and W axes, a total of 7 axes, which are divided into two groups of three linkage full closed-loop control. Among them, the c-axis discrimination rate reaches 0.001. The machine tool can complete multiple processes such as turning, indexing bias drilling, positioning milling, etc. by clamping the reverse rotating body parts at one time, that is, the machining process of two CNC lathes can be completed in the middle of one lathe milling composite machining, which can double the efficiency, and improve the accuracy because it can increase the error of the secondary device. The cx110 vertical turning milling compound machining center produced by Anyang Xinsheng Machine Tool Co., Ltd. is developed by fundamentally adding turning assembly to the vertical machining center. The machine tool has the functions of turning, boring, milling, drilling, reaming, tapping and so on, and can complete the five side machining of five axis linkage. The vht800 five axis combined turning and milling complex machining center and CHD25 five axis combined turning and milling complex machining center developed by other Dalian University machine tools; The whgs7000 turning milling compound processing center opened by Wuhan Heavy Machine Tool personal company can also complete the one-time loading of parts, and complete the multi process processing of huge layout and huge surface parts

1.1.3 turning milling composite processing center

htm-v120l CNC vertical turning milling composite processing center developed by Ningbo Haitian Precision Machinery Co., Ltd. can complete turning, milling and grinding multiple processes at one time, and can also stop heavy cutting and high-precision processing, which is suitable for large-scale bearing processing

1.1.4 turning, milling and gear processing compound middle

some turning middle is equipped with a second spindle and a grinding wheel shaft on the reverse rotating tool rest. Gear cutters can also be installed on the second spindle to process shaft gears and worm gears, and even five axis linkage can be completed, and spiral gears and bevel gears can be processed with finger milling cutters

1.1.5 grinding compound machining center

the h405-be CNC compound grinding machine developed by Shanghai Machine Tool Works Co., Ltd. adopts Siemens CNC system to separately control the feed of grinding wheel frame and task table, the torsion of head frame spindle and grinding wheel frame, and has the functions of cylindrical grinding and active division of grinding wheel frame. One time clamping can complete the active circular grinding of the inner and outer circles and end faces

1.2 process compounding

process compounding is rare in the world. The vtm3501 vertical turning milling and laser quenching compound processing center developed by Shenyang Machine Tool personal Schiess company. It can complete turning, boring, drilling, tapping, milling, grinding and laser quenching. The machine tool combines the cold working process with the hot working process, greatly improving the productivity

according to relevant data, a five axis linkage processing center or multi process composite processing center can improve the production efficiency by more than twice as much as a three-axis linkage processing center. Multi axis linkage and composite processing can not only improve production efficiency, but also add secondary device error, and improve accuracy and quality. Five axis linkage processing center and multi axis linkage composite processing center can be produced internationally, but some products are serious key problems and need to be further commercialized and commercialized

2 high speed

in order to complete the high-speed NC processing, the transmission system adopts the direct drive technology, and the NC system adopts the high-speed operation processing technology

2.1 direct drive technology

in order to improve production efficiency, the transmission parts of CNC machine tools slowly adopt direct drive technology. The spindle adopts direct drive of electric spindle, the feed adopts direct drive of linear motor, the reverse rotation task table adopts direct drive of torque motor to improve the infiltration drive of matrix to filler, and the five axis linkage swing angle universal head adopts direct drive of torque motor, etc

as early as 2000, China began the research and development of direct drive technology. At present, Shandong Bote Precision Industry Co., Ltd. and luoxiangyan Technology Co., Ltd. can produce and supply motorized spindle series products, and Beijing Shouke Kaiqi Electrical Technology Co., Ltd. has also opened up linear motors. Users respond well to the above product functions and technical goals, but there is still a gap compared with foreign advanced predecessors

at present, the unit speed of foreign advanced motorized spindle can reach 15000~100000r/min, and 40000~50000r/min is commonly used. The feeding part with linear motor direct drive requires not only high speed, but also high acceleration function. The fast moving speed can reach 60~200m/min, and the acceleration can reach 2g~10g; The task feed can reach more than 60m/min, and the acceleration can reach 1g~2g. The feeding speed of the feeding part driven by the traditional ball screw is 20~30m/min, and the acceleration is 0.1g~0.3g; Under normal environment, the feed speed is around 30m/min. The feed speed of direct drive is more than twice that of ball screw drive, which increases the auxiliary time and improves the productivity. Linear motor drive technology has a broad and bold prospect, but it still needs to further reduce costs and deal with heating problems

at present, CNC machine tools developed by some manufacturers in China have adopted direct drive technology. For example, in the middle of xhv252560 overhead five axis linkage high-speed boring and milling developed by Jinan No.2 machine tool, the X and Y axes are driven by linear motors. The two reverse rotating shafts of the xkr32g five axis linkage processing intermediate task table developed by Beijing Electric Machinery Institute adopt torque motor direct drive, and the spindle in the middle of xkh800 five axis linkage blade processing adopts electric spindle direct drive, etc. The direct drive technology of international CNC machine tools is still in its infancy, not widespread, and there is still a certain gap in function. More than 1500 CNC machine tools produced by German DMG company each year adopt direct drive technology. Fz12ks five axis machining center produced by German JuLang company has a spindle speed of 40000 R/min, a tool change time of less than 0.6s, a feed acceleration of 1g~2g, a rapid feed speed of 90m/min, and a workpiece exchange time of 2S

2.2 processing technology of NC piecemeal high-speed operation

high speed direct drive feeding requires fast NC piecemeal operation speed, short sampling period, and sufficient pre-processing ability of acceleration (deceleration) optimization method section in advance. More advanced CNC systems can pre process thousands and tens of thousands of segments. In multi axis linkage control, you can stop and accelerate the optimization processing according to the G code of the preprocessing buffer. To guarantee the processing speed, the sixth

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