Abstract: Diamond wire saws have been widely used in stone cutting and construction engineering. Some new processes and new methods have been used to make diamond wire saws. The beaded automatic cold press forming technology, beaded hot isostatic pressing technology, the production efficiency is greatly improved, the production cost is greatly reduced; the brazing technology and the diamond oriented arrangement technology improve the comprehensive performance of the diamond wire saw. The use of these technologies to create high-performance small-diameter wire saws and wire ropes for engineering construction further expands the use of wire saws.
1 Introduction
As a flexible and ultra-hard material cutting tool, diamond wire saw has been developed for more than 40 years since its introduction, from the initial electroplating technology to the manufacturing technology with sintering and brazing technology as the mainstream; The quality of stone is widely used in the mining of blocks in granite mines, the cutting of reinforced concrete or metal structural parts, and the application range is becoming wider and wider while the manufacturing technology is new. At present, the comprehensive performance of domestic diamond wire saws is close to the international advanced level, and the cost is low, which can fully meet the needs of domestic stone mining and sheet metal processing industry. Even many wire saw products produced by enterprises have begun to be exported to western countries such as Europe and America. With the rapid popularization and use of diamond wire saw machinery and diamond wire saw cutting technology, China's stone block material mining has entered the era of diamond wire saw, diamond wire saw manufacturing enterprises have achieved unprecedented development. For example, in 2007, a domestic company's diamond wire saw production reached more than 30,000 meters, with an output value of 15 million yuan and a profit of more than 3 million. Compared with the previous year, the output, output value, profit and other indicators have doubled. Through the independent innovation, the domestic diamond wire saw manufacturing enterprise has promoted the rapid progress of the domestic diamond wire saw technology and laid a solid foundation for the further promotion and use of the diamond wire saw.
2. New process for making diamond wire saw
With the increase in the use of diamond wire saws and the continuous expansion of the application surface, the production technology of diamond wire saws is constantly improving. In order to comply with the rapid development of the domestic and international markets and catch up with the international advanced level, some domestic companies have been in recent years. Continuous introduction of new equipment, research and application of new technologies, while the scale of production continues to expand, product quality, production efficiency has also increased significantly, while production costs are declining.
2.1 Granulation and volumetric automatic cold pressing process
At present, domestic wire saw manufacturers generally use non-granulated powder for manual cold-pressed bead production, which has low production efficiency, product quality is easily affected by human factors, and the working environment is dusty, which is not conducive to human health.
In view of the many drawbacks of using non-granulated powder for cold pressing, a domestic company first applies the powder granulation process and supporting equipment to production practice. The powder granulation process is to add the powder into the container by the high-speed rotation of the agitator and the cutting knife and spray the atomizing solvent to form the granules. The granulation of 10kg powder can be completed in 20 minutes, and the granulated powder is dried and screened. It is made into spherical particles of 30 to 80 mesh, and the molding ratio is 85% or more. The powder prepared by this method has better fluidity. After the diamond is mixed with the granulated powder, the distribution of the diamond on the working lip surface is more uniform; the surface of the diamond after coating is wrapped by powder, which is avoided during the pressing process. Direct contact with the mold surface reduces the loss of the mold.
After powder granulation technology and diamond coating technology, some domestic companies introduced foreign-made automatic cold presses for bead production. The equipment is based on the volumetric method (the amount of fixed powder) from the loading to the substrate and the carcass. Cold press forming together, high degree of automation, saving manpower, thereby greatly improving production efficiency and reducing production costs.
2.2 Hot isostatic pressing technology
Diamond bead sintering is an important part of wire saw production, which directly affects the sawing performance of wire saws. Beading is a thin-walled cylindrical structure, which requires high density of sintering. The usual hot-pressing method is too thin due to the upper and lower indenter walls, and the pressure-reducing ability is poor, which directly limits the sintering density of the bead, and the head loss is large, and the cost is relatively high. high. The traditional method of first cold pressing and no pressure sintering, the density of beading sintering is lower, which seriously affects the performance of the wire saw. At present, the most effective sintering method is to use hot isostatic pressing (HIP) technology. In beading production, the sintered bead is placed in a glass sleeve (some enterprises do not put glass sleeves directly into hot isostatic pressing). In the sintering furnace, placed in a hot isostatic press, using inert gas Ar gas as the pressure transmitting medium, the temperature is raised to 800 ° C ~ 900 ° C for isostatic pressing, and then the glass cover is removed by roller treatment or shot peening . The bead produced by the technology has less pores and high density, can improve the hardness, strength, wear resistance and working life of the bead, and can also improve the bonding strength between the substrate and the carcass; Packing thousands of beads to facilitate mass production.
3. New technology of diamond wire saw
3.1 Brazing technology
The impregnated diamond tool is a special composite material obtained by mixing diamond particles and metal powder and sintering them. The diamond particles are generally distributed in a random state in the carcass. As the tool works, the wear of the carcass continues, and the layers of diamond particles are continuously exposed and the workpiece is cut as a micro-cutting edge. Fall off, work continuously in the form of relay, cycle back and forth and consume. The distribution of diamonds with sintered beaded in the carcass is random, the spacing between the abrasive grains is uneven, and the carcass is mainly controlled by mechanical force, the diamond edge value is low, and the cutting efficiency is low. It is difficult to solve the problem of self-sharpness, and it is impossible to play the grinding effect of each diamond, resulting in waste of raw materials. The principle of diamond bead "brazing" is to use a solder containing active elements (such as Ti, Cr, W, etc.) to chemically react the active element with the diamond surface during brazing and form a layer of carbide. The role of layer carbide, diamond, carcass (solder), matrix can achieve a strong chemical metallurgical bond. Domestic brazing beads are mainly made of nickel-based or titanium-based brazing filler metal and then sintered under vacuum or argon atmosphere. At present, domestic enterprises mainly produce single-layer diamond brazing beads, and multi-layer diamond brazing beads have yet to be studied.
3.2 Diamond directional arrangement technology
The diamond is arranged in an orderly manner on the working lip surface of the tool. The arrangement distance between the diamond and the diamond and the arrangement law are controllable. To meet the cutting requirements of different cutting objects, we call this technology Oriented arrangement technology for diamonds. The methods for achieving the orderly arrangement of diamonds include a template method, a dispensing method, and a laser method. The latest practical method is to form the required regular arrangement of holes in the cold press forming process of the carcass. The diameter of the hole is designed according to the coarsest particle size of the diamond coating. It is automatically cold pressed by an automatic cold press and then special. The special equipment fills the diamond into the hole and then cold presses to perform hot press sintering. After the diamonds are arranged in an orderly manner on the beading working lip surface, the cutting efficiency and cutting life are greatly improved compared with the conventional beading, and the utilization rate of the diamond is also greatly improved.
3.3 Comprehensive technical application
In summary, the beading made by high-temperature brazing and diamond ordering integrated manufacturing technology has incomparable advantages compared with impregnated sintering and electroplated beading, especially on small-diameter beaded ropes. The main advantages are: 1 high diamond exposure, the height of the ordinary beaded diamond is limited to 1/3 of the height of the abrasive, and the height of the brazed bead can reach 2/3, up to 70% to 80%. The exposed height of the diamond greatly expands the chip space and is not prone to chip clogging and tool failure. 2The cutting efficiency is high, the cutting efficiency of the brazed bead is 4 times that of the ordinary sintered bead, and its strong chemical metallurgical combination is suitable for efficient grinding. 3 diamond utilization is high, the amount of diamond is reduced by half, reducing the cost, and the sawing life is equivalent to conventional beading. The application of brazing technology on small-diameter beading can produce good results. If the diameter of the carcass of the sintered bead is reduced, the characteristics of the multi-layer diamond are lost, and the brazing technology can produce superior performance. Diamond beads with smaller specifications.
4 Diamond wire saw new series and new application expansion
4.1 New series of diamond wire saws
Compared with the traditional diamond series wire saw (the diameter is generally 58-512mm), represented by the application of small diameter diamond wire saw (the bead diameter is generally 55.5-57.5mm), it forms a new series of diamond wire saws, which are mainly used in Strict requirements for the size of the slit.
At the same time, the reduction of bead diameter is of great significance for the cutting of precious stones. The application of small-diameter diamond wire saws in stone processing, on the one hand, saves stone resources, on the other hand, reduces processing energy consumption, making the processing methods more environmentally friendly. In order to meet the market demand, some domestic companies have now produced a variety of beaded ropes, the smallest diameter has been able to achieve 56.0. To reduce the size of the wire saw, it is necessary to reduce the diameter of the steel wire core and the diamond bead. The diameter of the wire rope is generally only 53.5 to 53.8 mm. Due to the reduction of the cutting resistance, the small diameter diamond wire saw can be sawed by a large area (4 m2) and thickness ( 5mm) Very thin granite sheet, sawing efficiency is increased by 3 times. The cutting force and energy consumption of the small diameter wire saw is reduced by about 20% to 30% compared to the 59mm wire saw, and the cutting time per square meter is reduced by about 25%. The material size deviation processed by the small diameter wire saw is also smaller than that of the large diameter diamond wire saw, so it has some special properties. At present, small diameter beading is preferably produced by hot isostatic pressing (first after cold pressing, isostatic pressing) or by brazing diamond. Reducing the diameter of the diamond bead helps to increase productivity, reduce production costs, and has less noise, less pollution, and lower energy consumption during use.
4.2 Progress in the new application of reinforced concrete cutting wire saw
At present, the domestic reinforced concrete wire saw technology has developed to a relatively mature stage, and the scope of actual use is constantly expanding. In addition to the traditional reinforced concrete structure cutting, it also has a large-scale application in the fields of submarine cable cutting, oil pipeline cutting, large-scale steel and other metal structural parts cutting, boiler and smelting furnace transformation. For example, the submarine oil pipeline and cable pipe cutting wire saw and supporting equipment jointly developed by Harbin Engineering University and a domestic company have been applied on a small scale; the renovation projects of domestic large and medium-sized iron and steel enterprises such as Shanghai Baosteel and Guangxi Liugang have also been completed. A large number of diamond wire saws are used, which have the advantages of small slits, simple operation, environmental protection, and strong cutting ability of components, which can save a lot of transformation cost for the enterprise.
5 Conclusion
Compared with other diamond tools, the diamond wire saw is a flexible tool, which can be used not only for cutting straight plates, but also for cutting shaped plates; it is not limited by the surface shape of the object, the work site is simple, and it can be cut in a large area; the use of a diamond wire saw can be used. Improve resource utilization and reduce environmental pollution. Due to these advantages, the market size is getting larger and larger, and the application range is wider and wider. With the advancement of technology, the use of powder granulation technology and automatic cold pressing technology can greatly improve the production efficiency of diamond wire saws; new processes such as hot isostatic pressing technology, diamond oriented arranging technology, brazing technology, etc. The diamond wire saw made by the method can greatly improve the comprehensive performance of the wire saw. The large-scale use of the high-performance diamond wire saw is of great significance for improving the utilization of stone resources, reducing the cutting cost per unit area and protecting the ecological environment.
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