On energy saving and environmental protection of h

2022-09-22
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Brief discussion on energy conservation and environmental protection of heat treatment

with the development of China's economy, the number of heat treatment in manufacturing industry is also increasing with the development of manufacturing industry. It is reported that by the early 21st century, heat treatment will account for more than 40% of the total steel. However, because heat treatment is a special process that improves the performance of parts by changing the metal structure caused by furnace heating, its high energy consumption and great pollution can be imagined. World industrial development has confirmed that the progressiveness of manufacturing technology is the guarantee of product competitiveness. The advanced level of its heat treatment technology is the key factor to ensure the quality of mechanical products. However, there is a gap between China's mechanical products and the world's advanced level for more than 20 years. Its heat treatment production technology is very backward, and its production equipment is 30 to 40 years behind the world's advanced level. Its power consumption per ton is 2 to 3 times higher than that of Japan, Europe and the United States. In addition, the cleaner production of the heat treatment industry has not been carried out, and the environment has been seriously polluted, Therefore, strengthening environmental protection and energy-saving production of heat treatment has become a top priority in the manufacturing industry. Here are some views on this

1 strengthen specialized production of heat treatment

at present, large and comprehensive, small and comprehensive, versatile, non cooperative, closed enterprises can be seen everywhere in China, that is, there are workshops, sections or teams with strong commonality in one factory, such as casting, forging, electroplating, heat treatment, mold manufacturing, heating, transportation, etc., so the product quality is poor, the task is not saturated, the production efficiency is low, the utilization rate of equipment is extremely low, energy consumption, material consumption Pollution has increased greatly. According to the information, China has about 11000 heat treatment plants and 150000 employees. Compared with the United States, the labor productivity, the number of specialized plants, profits and annual turnover of the United States are 10 times higher than that of China. The annual power consumption is less than 50% in China. For this reason, the state proposes to carry out specialized production adjustment, abolish factories with unsaturated production, poor technical conditions and high energy consumption and pollution, establish professional heat treatment plants and production cooperation points, and improve the utilization rate of equipment. A number of plants with extremely poor performance in all aspects have been abolished, and more than 40 professional heat treatment plants and more than 450 cooperation sites have been established, so that energy consumption can be eliminated significantly by removing the glass of the dial. Before the professionalization of an optical instrument factory in China, the power consumption of heat treatment reached 3000kw/h, but after the professionalization, it fell to 800kw/h, the utilization rate of equipment increased by 35%, and the productivity increased by 45%. Obvious economic and social benefits were achieved

2 vigorously promote new quenching media

at present, mineral oil, sodium chloride aqueous solution and nitrate solution in this case are still widely used in the heat treatment process in China. In the process of heat treatment, Water-soluble Polymer Quenchants prepared from organic and inorganic substances and quenching oil modified additives have been widely promoted and applied in foreign countries. Due to their adjustable cooling capacity and simple concentration determination in use, they have the characteristics of preventing quenching crack, reducing deformation, no rust, tasteless, no smoke, no fire, high service temperature, environmental protection, etc. at the same time, the cost is greatly reduced and the product qualification rate is greatly improved. After a machinery factory in China adopted a new type of PAG quenching instead of 30 oil quenching, the cost of connecting each wheel with two horizontal connecting rods decreased from 20000 yuan/year to 9000 yuan/year, and the qualified rate increased by 97% from 92%. At the same time, the cost is reduced by 20% and the pollution of volatilization in high temperature is avoided. Therefore, China should speed up the promotion of new quenching media in the process of heat treatment

3 replace traditional materials and adopt new steel grades

it is reported that a factory has conducted the following experiments: the front axle of Isuzu automobile adopts non quenched and tempered steel, and after the process of heating + heat preservation + quenching oil + high temperature tempering, the horizontal, longitudinal and street bending fatigue tests are conducted 300000 times respectively according to the specifications The 500000 CST (5) 0 impact specimen notch projector is a special light impact specimen notch projector to check the processing quality of Charpy V-shaped and U-shaped impact specimen notch. After the required times and 1million cycles plus 30000 km road test, all items meet the standard, which is 60 yuan lower than the forging cost of each piece of traditional 45# steel, and the annual purchase cost is saved by about 1.5 million yuan. Therefore, replacing traditional steel with new steel to manufacture the same parts can reduce material consumption, energy consumption and pollution

4 induction heating

as we all know, on the premise of meeting technical requirements and ensuring quality, reducing salt bath furnace heating is an effective method to save energy and eradicate pollution. For example, heating the metal mainly by barium chloride after melting with a variety of chemical salts, although it has the characteristics of fast heating speed, oxidation prevention, uniform temperature, etc., it is extremely difficult to accurately control the temperature due to the influence of salt mist, and the operation is unsafe. More importantly, heating by barium chloride at high temperature will produce serious pollution such as harmful gases, smoke and dust, salt slag, etc., and the performance of new equipment using induction heating can meet the standard, And does not produce harmful gas pollution. We have carried out experiments. Compared with induction heating with hacksaw blade and quenching in salt bath furnace, the former can obtain acicular martensite structure, and the impact toughness elimination method can improve the screw connecting oil pump and motor by 20%, and eliminate pollution

5 adopt vibration aging and deformation treatment

in order to eliminate its residual stress, stabilize its size and metal structure, and prevent deformation and cracking, the traditional process adopts furnace low-temperature heating aging. For this reason, not only the cost is high and the cycle is long, but also the environmental pollution and power consumption will inevitably increase with long-time heating. Therefore, the multi type vibration aging series computer control equipment manufactured by foreign countries using the principle of multi harmonic resonance generated by different frequencies can not only completely eradicate the heating pollution of furnaces, but also save energy. Therefore, China should improve the traditional process and adopt new process. On the other hand, we should organically combine the forging, hot rolling, casting and heat treatment processes, and use the rest of the heat for treatment, which can not only reduce repeated heating, improve equipment utilization, shorten the production cycle, but also save energy, reduce costs, improve the comprehensive performance and quality of products, and more obviously, reduce pollution, which is conducive to environmental protection. It is reported that in this experiment, a tractor part was naturally cooled after being forged, and then reheated for heat preservation + medium cooling quenching treatment. The average power consumption is 1.25kw · h/piece. Now the rest of the heat quenching treatment after forging can eliminate the reheating process. Based on the annual calculation of 200000 pieces, 25000 kW · h/year can be saved. What is more gratifying is that good benefits have been achieved due to the elimination of reheating pollution

6 study new processes and adopt new equipment

with the continuous development of science and technology, we are required to constantly study new processes and equipment for heat treatment. The application of various energy-saving, efficient and environmental friendly heat treatment equipment is the development trend of the manufacturing industry in the future. For example, the use of high-frequency and ultra-high-frequency pulse and laser heat treatment equipment, electron beam heat treatment, ion bombardment chemical heat treatment and computer applications have opened up a broad space for improving the level of heat treatment

in short, in today's manufacturing industry, heat treatment must take the road of socialization and specialization, adopt high-tech technology, new equipment and materials, and constantly improve the awareness of environmental protection and energy conservation, which is the future development direction of heat treatment

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