Answer: Ultra-high pressure water cutting, also known as water knife and water jet, is a high-energy (380MPa) water flow generated by multi-stage pressurization of ordinary water, and then it is sprayed and cut at a speed of nearly 1,000 meters per second through a very fine ruby nozzle (φ 0. 1-0.35 mm). This cutting method is called ultra-high pressure water cutting.

Q: When and where did ultra-high pressure water cutting originate?

A: The discovery of high-pressure water cutting originated in Scotland. After 100 years of experimental research, an industrial high-pressure water cutting system appeared.

During the period of 1936, mining engineers in the United States and the Soviet Union successfully used high-pressure water jet for coal mining and mining. By 1956, the former Soviet Union cut rocks with water at a pressure of 2000 bar. In fact, high-pressure water cutting is not a patent, until 1968, a professor of Columbia University in the United States added an abrasive to high-pressure water, which accelerated the cutting process through the grinding effect of high-pressure water jet and abrasive.

Q: What is the current situation of water cutting?

A: At present, the United States, Germany, the former Soviet Union and Italy have broken through the ultra-high pressure water cutting technology. The global representative enterprises are Fulu, Ingersoll Rand and Bystronic. The highest cutting pressure can reach 550MPa, which is widely used in stone, metal, glass, ceramics, cement products, paper, food, plastics, cloth, polyurethane, wood and leather. The research on this work has been carried out in China for nearly 40 years, and the Ministry of Machinery, the Ministry of Aerospace and the State Shipbuilding Industry Corporation have successively initiated research projects, but ultra-high pressure water cutting has been in the laboratory stage and has not been used for stable commercial operation. For this reason, XXXX cooperates with Ukraine to produce ultra-high pressure water cutting equipment, with a stable working pressure of 380MPa, and the main components are imported. The cooperative products have been used to cut the stainless steel plate of Swedish XXX company, the ink wheel of American XX printer and the waste ammunition of the General Armament Department.

Other domestic enterprises also have manufacturers of water cutting equipment, and the actual operating pressure is only about 220MPa, which belongs to the middle and low pressure level. The higher the pressure, the better the cutting technology and the faster the cutting speed. Especially when cutting thick plates, the water cutting machine with medium and low pressure (200MPa) can't ensure the consistency of the upper and lower cutting curves of the cut material, and even can't cut through, so the cutting speed is very slow. The maximum cutting thickness of steel plate is 70mm and the cutting speed is about 15 mm/min. The maximum stone cutting thickness is 80mm, and the cutting speed is 20-50mm/min. Cutting speed is related to cutting thickness, material to be cut, roughness and abrasive selection. The roughness of cutting is also related to the choice of cutting material, cutting speed and abrasive.

Obviously, ultra-high pressure water cutting has many advantages, but it also puts forward higher requirements from the technical point of view, such as the wear resistance of materials, the sealing problem of ultra-high pressure, the safety problem of ultra-high pressure and the reliability problem of ultra-high pressure, which are the focus of attention in the industry. XX Company has successfully solved the problem of ultra-high pressure cutting of 380MPa, and is now focusing on the technical research of higher pressure of 600MPa, so as to promote the development of ultra-high pressure water cutting technology and better serve customers.

Q: Is ultra-high pressure water cutting a universal cutting method?

Answer: Although ultra-high pressure water cutting can cut any material, it is mainly applied.

Water cutting has three main uses. One is to cut non-combustible materials, such as marble, ceramic tiles, glass, cement products and other materials, which cannot be processed by hot cutting; The second is to cut flammable materials, such as steel plate, plastic, cloth, polyurethane, wood, leather, rubber and so on. In the past, hot cutting can also be used, but it is easy to produce burning area and burr, while water cutting will not produce burning area and burr, and the physical and mechanical properties of cutting materials will not change, which is also a big advantage of water cutting; Third, cutting inflammable and explosive materials, such as ammunition and cutting in inflammable and explosive environment, is irreplaceable by other processing methods.

Generally speaking, when the processing methods such as laser, plasma, flame, wire cutting, sawing and milling can basically meet the processing requirements, water cutting is not suitable. After all, the running cost of water cutting is high, and nozzles, guide sleeves and high-pressure seals are all imported consumables, which are expensive. However, when you think that the thickness of laser and plasma cutting is too thin, the burr is too large, and the heat affected zone is unfavorable, you can consider using water cutting; When you think that the burr of flame cutting is too large, the roughness is too poor and the heat affected zone is too large, you can consider cutting with water; When you think that the speed of wire cutting is too slow to cut non-conductive materials, you can consider using water cutting; When you think that milling produces a lot of waste chips, which causes great waste, you can also consider using water cutting, because water cutting will not produce waste chips, but cut the whole piece, and most of the materials cut by water cutting are available; When you think it is too slow to make nonlinear cutting with circular saw and band saw, you can still consider cutting with water; When cutting flammable and explosive materials or cutting in flammable and explosive environment, water cutting must be considered; When you don't want to produce toxic gas, secondary processing, thermal effect or deformation or microcracks, but also want to produce good trimming quality and cut small holes at the same time, you should consider using water cutting. In a word, water cutting is a general cutting method, but it is not the best in some cases, so it should be analyzed in detail when choosing.

Q: What are the forms of ultra-high pressure water cutting?

A: As far as water quality is concerned, there are two forms of ultra-high pressure water cutting. One is pure water cutting, and its cutting seam is about 0.1-1.1mm; The second is abrasive cutting, and the cutting seam is about 0.8-1.8 mm.

From the structural form, there are many forms, such as: gantry structure, two or three-axis CNC cantilever structure, which are mostly used for plate cutting; Robot structure with five to six numerical control axes is mainly used for cutting automobile interior parts and automobile linings.

Q: How is the consistency of the cutting curve between the top and bottom of the cutting material required?

Answer: This poor consistency, also called water cutting bevel, has a lot to do with cutting speed. High-energy jet will definitely produce energy attenuation after cutting work, so it is normal to produce bevel edge. In general, it is appropriate to control the unilateral hypotenuse at 0.08 mm-0.15 mm.

Q: Can ultra-high pressure water cutting cut complex curves?

Answer: The simplest ultra-high pressure water cutting machine tool has two CNC axes, and the X-Y is controlled by CNC to do CNC movement, which can realize the direct conversion between CAD and CAM, and truly avoid keyboard input and realize drawing-free processing. Any complex curve drawn in CAD/CAM can be directly cut and formed.

Q: What is the cutting accuracy that can be achieved by water cutting?

Answer: The cutting accuracy of water cutting is between 0. 1mm and 0.25mm. Its cutting accuracy depends on the accuracy of the machine, the size range of the cut workpiece and the thickness and material of the cut workpiece. Generally, the system positioning accuracy of the machine is between 0.0 1mm and 0.03 mm.

Q: What abrasive is used for water cutting? What is the particle size?

A: The abrasives used for water cutting are quartz sand, garnet, river sand and emery.

The abrasive particle size is usually 40-70 mesh. The higher the abrasive hardness, the larger the particle size and the stronger the cutting ability. The water jet abrasive of XX Company uses 60-mesh garnet.

Q: What is the high-pressure water flow of water jet in Q:XX Company?

A: 3.8 liters/minute.

This is used in industry now.