CNC cutting is relative to manual cutting and semi-automatic cutting.
It is a cutting tool that uses a digital program to drive the movement of the machine tool to drive the equipment to cut the object. This mechatronic cutting technology is called CNC cutting technology.
At present, the domestic CNC cutting control system has basically realized graphics, networking and intelligence; the drive system has also evolved from the original stepping system and analog servo drive to today's all-digital servo system. Cutting energy has also evolved from a single flame cutting to plasma cutting, laser cutting, high pressure water jet cutting and more. Domestic large-scale gantry cutting machines have been widely used in the processing of large plates, and cantilever cutting machines are widely used in the processing of small and medium-sized plates. In addition, the portable cutting machine developed by the trolley cutting machine and the special intersecting wire cutting machine are also widely used, and the foreign advanced robot cutting machine is gradually introduced, digested and absorbed by well-known domestic enterprises. This paper comprehensively introduces the research and application status of CNC cutting in China from the perspective of cutting energy.
(1) Characteristics of Numerical Control Flame Cutting Flame cutting is a thermal cutting method in which a steel secant is heated to a molten state by using an oxyacetylene flame, and then the steel sheet is blown through high-pressure oxygen. For the three main thermal cutting methods (flame, plasma, laser), the energy density of flame cutting is the lowest, the cutting heat affected zone is the largest, the precision is the worst, and the cutting ability is the lowest, but the maximum thickness of the cuttable steel is the largest. In addition, the cost of cutting equipment is very low, so it will still occupy a place in the application field.
Especially with the advancement of technology, CNC technology is gradually applied to the field of cutting. In 1961, the world's first CNC flame cutting machine was successfully developed by British Oxygen Company. Since then, CNC flame cutting has gradually replaced manual and semi-automatic flame cutting, and has been widely used in the cutting of thick steel in machinery, shipbuilding, military, petrochemical, metallurgical mining, energy and aerospace.
On the other hand, with the experimental research on the influencing factors of the cutting process, the cutting speed has been greatly improved, and various rapid cutting nozzles and cutting methods have been developed, such as high-pressure diffusion type fast cutting nozzle, high-pressure fine oxygen jet cutting nozzle, and double Oxygen curtain cutting nozzle and multi-cutting nozzle combined high-speed cutting method. Since the 1970s, the basic research and development has become less and less. At present, the practical cutting speed of this method is still within 1m/min, and the development space is limited.
(2) Research status of domestic CNC flame cutting China's CNC flame cutting technology started in the mid-1980s with the aim of improving processing efficiency. At that time, the core technology and key components needed to be imported from abroad, and then used to sell the racks developed by ourselves, mainly used in the field of ships. As time went by, the electrical systems and control systems of the equipment imported from abroad at that time gradually deteriorated, and it was time to update. In recent years, some research institutes and universities have independently developed some CNC flame cutting machines and supporting devices that meet China's national conditions by introducing, absorbing and digesting foreign CNC cutting technology, and have made great progress.
Peng Zilong, Youbo, Ding Liang and others developed an economical CNC flame cutting machine. The hardware part of the model is the combination of the industrial controller and the motion control card to complete the control function of the control system. The drive mode is driven by the stepper motor; the software part adopts the modular idea, uses WindowsXP as the operating environment, and adopts VC++6.0 object-oriented. The development platform develops a powerful and user-friendly control interface, which eliminates the problem of low-frequency resonance of electrodes and heating during high-torque driving, and can be applied to general metal processing enterprises.
The metal sheet to be processed may be uneven in thickness, and the cutting torch must be kept at a constant height to ensure the cutting quality during the cutting process, so it is particularly important to develop a good automatic height adjustment system. Song Kaiyun, Liu Yanni, and Zhang Xinping set up an automatic height adjustment system with a height adjustment range of 12 cm. The principle is to place a high temperature resistant induction coil in a plane high with the torch. The induction coil and the flat plate constitute a Capacitor C, the height between the steel plate and the capacitor - and the capacitance C have a relationship C (constant, can be known by measuring C - can be automatically adjusted by automatic control C - the system has a good test effect, can meet the actual The processing requirements of incoming materials. Jiang Xiangjun, Zhang Youyun, Chen Zongheng and others used PWM control technology to design an automatic height control system based on fuzzy control method. The results show that the method has good stability, high precision and good application. prospect.
In the field of ships, the problem of large-diameter opening of cylinders has always been a problem. In the past, artificially placed plates, prototypes were produced, manually cut, and finally artificially ground. With the changes in the structure and steel of new ships in China and the improvement of the combat performance of ships, the traditional method of opening holes is difficult to meet the requirements. Wang Zongyi, Hu Shenghai, Zhao Shijun and others have developed a large diameter open hole CNC flame cutting machine. The variable diameter range is 1.03.Om, and the torch height varies from 1.0m. When opening the groove, the DKK-1 large-diameter open-hole numerical control flame cutting machine with thickness variation range of 30 has been applied in shipbuilding. Filled the gap in China's technology field.
The cutting of large thickness steel plates is a difficult point of flame cutting. Xiong Xiaoming, Wang Li'an, Gu Jianghan and others developed the nesting system of the CNC flame cutting machine. The system combines the automatic nesting system and the automatic adjustment system of the capacitive sensor under the program control of the industrial computer, which can effectively solve the thick The middle perforation problem of the board.
Generally speaking, the CNC flame cutting machine is mainly used for the cutting of ordinary carbon steel with a thickness of more than 5mm. It cannot be used for the cutting of non-ferrous metals and stainless steel. The reason is that the stainless steel is easy to form a dense oxide film during the cutting process to prevent the heat from going down. Passing, while non-ferrous metals are not suitable for flame cutting due to their faster heat dissipation. Plasma, laser and high pressure water jet cutting energy can be applied to the cutting of such metals, especially thin sheets.
(1) Characteristics of Numerical Control Plasma Cutting Plasma arc cutting is a thermal processing method that uses the heat of a high-temperature plasma arc to rapidly fuse the metal at the slit and utilizes the momentum of high-speed plasma to remove the molten metal to form a slit. The biggest difference compared with flame cutting is that the chemical reaction occurs along with the flame cutting process, and the plasma cutting does not cause a chemical reaction, so the plasma cutting speed is fast and is not limited by the type of material. CNC plasma cutting technology is a high-tech integrated with numerical control technology, plasma cutting technology and inverter power supply. This technology has shown great advantages in improving processing precision, saving materials and improving labor productivity, and has received extensive attention at home and abroad. .
The height control between the CNC plasma cutting torch and the workpiece is very important. The analog circuit is generally used for control in China. Zhao Jiazheng and Bujiawu Research have adopted the automatic height adjustment system with the single chip as the core to improve the control precision. Recently, the matching equipment for CNC plasma cutting has also developed rapidly. Yuan Jianguo studied the characteristics of air plasma cutting dust and developed a special water tank device for treating soot. This device can be effectively placed under the cutting port. Inhibited the diffusion and rebound of the fog cone, and received good results; Xue Wu, Nan Yuanyichen, etc. developed a plasma cutting monitoring system, and studied the relationship between plasma cutting sound characteristics, cutting sound, cutting conditions and cutting quality. Hey, the test results show that plasma cutting can be used to monitor the plasma cutting process to improve plasma cutting quality and efficiency. Due to technical reasons, the price of foreign cutting guns is several times higher than that of domestic cutting guns, and the service life is also long. In order to extend the service life of cutting torches, Harbin Welding and Cutting Complete Equipment Co., Ltd. designed a protective device for cutting torches and received good effect.
(2) Application of CNC plasma cutting technology China's CNC plasma cutting technology started in the 1980s, which is nearly 30 years away from foreign countries, and its development speed is slower. However, in recent years, some universities, research institutes and manufacturers in China have carried out research on CNC plasma cutting technology, and gradually developed and produced various types of CNC plasma cutting equipment to shorten the gap with advanced foreign technology.
The market demand for CNC plasma cutting machines in China is 300,400 units per year. At present, the domestic manufacturers of CNC plasma cutting machines mainly include Messer Cutting and Welding Co., Ltd. (Kunshan) and Shanghai ESAB Cutting Machinery Co., Ltd. They have received strong support from foreign technology, so the products are in a leading position in China. Harbin Sihai Numerical Control Equipment Co., Ltd., Harbin Welding and Cutting Equipment Co., Ltd., Harbin Electric Machinery Co., Ltd. Mechanical and Electronic Equipment Manufacturing Plant, China Shipbuilding Corporation Ship Technology Research Institute, Shenzhen Bolichang CNC Cutting Equipment Co., Ltd. and Wuxi Hualian Welding and Cutting Equipment Enterprises such as factories use their own advantages and develop rapidly in technology. The products meet the needs of different users.
The manufacturers of foreign CNC plasma cutting machines are mainly concentrated in Germany, Sakamoto, and the United States. The cutting precision of the fine plasma cutting machine of Germany ESAB has reached the lower limit of laser cutting, and the cost is only 1/3 of the laser cutting. Foreign manufacturers have installed a special cutting robot on the gantry cutting machine. Various tracks can be cut in space. In addition, underwater plasma cutting equipment and fine plasma cutting equipment are widely used abroad. In general, intelligent precision plasma cutting will become the future development direction.
The characteristics of CNC laser cutting Laser cutting is to use a high-power laser beam to illuminate the workpiece, so that the irradiated material can be rapidly melted, vaporized, ablated or reached a burning point, and the molten material is blown off by a high-speed air stream, thereby achieving a heat for cutting the workpiece. Cutting method. Compared with other thermal cutting methods, it has a wide cutting range, high cutting speed, good cutting quality, multi-station cutting, easy automatic cutting, low noise and vibration, and no pollution to the environment. However, due to limitations in laser power and equipment volume, the thickness and speed of the cutting material are also limited. In addition, in applications, materials with low laser absorption, high thermal expansion, and specially polished surfaces are not suitable for laser cutting. Since the laser for cutting is large in volume and the optical path system is precise, laser cutting is performed by a numerical control cutting device.
Research and application of CNC laser cutting China's first C02 laser cutting equipment was introduced in the 1970s. Up to now, hundreds of industrial laser cutting equipments have been applied in the fields of automobiles, ships, electronics, petroleum industry, etc. Used for cutting of sheets. Compared with developed countries such as Germany, Sakamoto, and the United States, China's laser cutting equipment automation and laser emission power are still low; in addition, developed countries have developed thousands of five-axis CNC laser cutting equipment for each The cutting of pipes and profiles is especially widely used in the automotive sector, and we are just getting started in this field.
The production of CNC laser cutting machine tools and supporting facilities in China is mainly concentrated in the Yangtze River Delta region of Shanghai and Jiangsu, the northern part of Jishen, and the central and southern regions of Hanshen.
The main production enterprises include Shanghai Unity Prima, Dazu Laser, Shenyang Prima, Wuhan Chutian Laser Group, etc.; high-power laser manufacturers mainly include Nanjing Oriental Laser Company, Changchun Institute of Optics, Shanghai Leo and Hebei Academy of Sciences. Manufacturers such as Wuhan Hengxin and Wuhan Optics Valley Keweijing. These manufacturers develop market-competitive products by introducing, digesting and absorbing foreign advanced technology.
At present, the world's leading laser cutting equipment is the world's leading laser processing of high-power three-dimensional five-axis CNC laser cutting machine, Swiss Baichao, Japan NTC, Mitsubishi, Yamazaki Mazak, Italian Prima and German Trumpf. Machine tool builders master this technology. Shanghai Unity Prima Laser Equipment Co., Ltd. is the largest manufacturer of high-power laser processing machines in China. In 2008, the company successfully developed SLCFXL3090/3D three-dimensional CNC laser cutting machine with X/Y/Z stroke of 9000/3000/ 400mm, this model has been successfully applied to high-efficiency laser cutting of complex surface parts such as automobile covers and military special parts.
CNC laser cutting technology has broad application prospects in the field of automobile manufacturing and aerospace. At present, the world famous automobile manufacturers generally use 3D laser cutting instead of the traditional blanking process, which can reduce the cost of the mold and shorten the manufacturing cycle. Only a few Chinese and foreign joint venture automobile manufacturers have introduced such equipment to trim the stamping parts. And the punching of the body. In addition, armored vehicle forming chassis, launching cabin, aerospace engine rotor hub, etc. are also processed by three-dimensional CNC laser cutting.
CNC high-pressure water jet cutting CNC high-pressure water jet cutting characteristics Water jet cutting is the use of high-pressure water with pressure of tens to hundreds of megapascals through a specially designed nozzle for high-speed jetting, using the impact of high-speed water jet kinetic energy to separate the material A processing method. Due to the high pressure used, it is also referred to as ultra high pressure water jet cutting. High-pressure waterjet cutting technology is an emerging flexible cutting technology that originated in Canada. The most important feature of this type of cutting is the high-energy jet processing of non-heat sources, which can cut almost all metallic and non-metallic materials. Compared with flame, plasma and laser cutting, it has the advantages of dust-free, odorless, non-sparking, no gas, no heat affected zone and no thermal deformation. It does not change the material and performance of the material to be cut. The quality of the cut is high and the slit width is small. It can be started and terminated at any place of the material, and can cut three-dimensional curved workpieces, which can realize safe cutting in the open fire-free operation area. Compared with laser cutting, water jet cutting is more efficient in cutting laser cutting in thin-plate cutting. However, when the material thickness exceeds 16 mm, laser cutting cannot be compared with high-pressure water jet due to the greatly increased cost. In the 21st century, which advocates green environmental protection, the development and promotion of high-pressure water jet cutting technology will have important environmental significance.
Production of CNC high-pressure water jet cutting China's water jet cutting technology started in the 1990s, and universities and research institutes that track advanced foreign technology mainly include Nanjing University of Science and Technology, Zhongshan University and Hefei General Machinery Research Institute; The enterprises that promote and apply mainly include Nanjing Dadi Water Jet Cutting Co., Ltd., Shenzhen Bolichang Company, Zhejiang Huangyan Zhechen Water Jet Equipment Factory and other enterprises. In 1998, the application of the Nanjing Dadi Water Shooting System in the gantry plasma cutting machine was introduced in detail by Shenzhen Zhongxingxing Numerical Control Technology Co., Ltd. (Guangdong 518052) Luo Zhengbing Control Center.
At present, the CNC cutting machine used in China's metal processing industry is mainly based on flame and ordinary plasma cutting machine. The simple flame cutting can not meet the needs of modern production. The CNC cutting machine currently required by the market is mostly CNC plasma cutting machine. This type of cutting machine can meet the needs of different materials, different thickness of sheet metal cutting and metal parts processing, so the demand will be larger and larger. However, the expensive numerical control system, high equipment cost, complexity and maintenance and operation restrict the further popularization of CNC plasma cutting in China.
Flow Cutting Co., Ltd. unveiled its own model at the 5th China International Machine Tool Show, marking China as the fifth country to produce water jet cutting machines.
At present, the pressure of domestic ultra-high pressure water cutting machine reaches 400MP, the cutting thickness can reach 30 (100mm or more, the water jet speed is up to 800 (1000m/S), the numerical control platform adopts the precision transmission technology of ball screw and rolling linear guide, the control precision All are within +0.02mm.
At present, CNC ultra-high pressure water jet cutting technology is widely used in industrial fields such as aerospace manufacturing, automobile manufacturing, glass deep processing, concrete, stone and ceramic processing. This technology can be used to cut aircraft fuselage, tails, wing sections, turbine blades, switchboards, sheet metal parts up to 203 mm (8 in) thick, and rubber and plastic parts requiring smooth, flat surfaces without delamination. The shape of automotive interior decorations is more complicated, and these products are mainly made of PVC, PET, etc., so they cannot be processed by hot cutting. Nanjing Dadi Water Jet Cutting Co., Ltd. has introduced the DCM space water cutting system widely used. Processing of such products.
Pan, its remarkable feature is the entire curve cutting of ceramic stone. Commonly with the development of domestic numerical control technology, some domestic CNC cutting machine manufacturers have introduced domestic control system technology, and designed a cost-effective CNC cutting machine suitable for China's national conditions. These special CNC cutting devices have reached or exceeded the similar products in foreign countries.
From the mechanical structure point of view, the development of CNC cutting machine has experienced three stages: cross type (light type), door type (small size) and gantry type (large size), and the corresponding models have various types. Although the cross type, door type and gantry type are produced in China, the breadth is not enough. The manufacturer's product models are more single cases: large ceramic murals, lobby floor mosaics, pottery screens, cabinet shaped shaped countertops and stone art furniture.
As far as the current technical level is concerned, there is still a big gap between the domestic CNC cutting technology and the foreign CNC cutting cutting technology. Due to the high technical content, foreign advanced CNC machine tools have the characteristics of complicated operation interface, complicated structure and difficult maintenance. Once there is a problem in the introduction of equipment, foreign experts must be required to carry out on-site maintenance. The cost is quite expensive, so the enterprise should according to its own product characteristics and Economic strength, combined with the characteristics of CNC flame, plasma, laser and water jet process cutting equipment selection, instead of blindly pursuing high-priced CNC cutting machine tools. The introduction of cutting equipment should be carried out in a targeted manner. At the same time, we must closely follow the advanced technology of foreign countries, actively carry out the technology digestion and absorption of cutting equipment, vigorously carry out basic theoretical research on various cutting methods, strengthen cooperation research in related fields, and make theoretical reserves and provide technical support for research and development of new products. The whole society must fully develop independent technology research and development, equipment development, and create CNC cutting equipment with independent intellectual property rights to adapt to the development of China's machinery manufacturing industry, and strive to achieve low carbon
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