On 2018-08-08 14:48:54
The situation facing the heat treatment industry
1, less and no waste of energy to take energy-saving process measures to get twice the result with half the effort, such as shortening the heating time, reducing the heating temperature, strengthening the chemical heat treatment process, using the waste heat of the previous process, etc. The specific process includes zero heat preservation and heating and non-uniform austenitizing quenching, chemical heat treatment in ferrite state (< 600℃) instead of chemical heat treatment in austenitic state (> 850℃), carburizing from 930℃ to 1050℃, the use of rare earth and other catalytic agents, and the use of residual heat quenching after forging have been popularized and applied. Reasonable selection of equipment and energy saving potential is big, big stove than small furnace furnace energy saving, energy saving, continuous furnace than cycle make full use of waste heat resistance furnace energy saving at least 50% of fuel furnace, ceramic fiber and proportion of lightweight refractory lining brick lining of heat storage and heat dissipation is less, than the rectangle in cylindrical furnace heat to reduce energy consumption reduced by 7% 20%, the heat treatment unit, lightweight material plate, the whole basket, clamp can save 10 ~ 20% of its electricity. Rational organization of production, maintaining the continuity of production, effective management and monitoring of equipment energy is also very important for energy conservation.
2. Less and no harmful emissions advanced heat treatment technology should first of all be clean production technology without pollution to the environment. These include cleaning processes, cleaning equipment and cleaning accessories. Induction heat treatment with controlled atmosphere, vacuum and good shielding is a widely used cleaning process. Plasma heat treatment, low pressure carburizing, high pressure gas quenching, laser surface hardening, spray quenching are also low pollution technology. The corresponding vacuum furnace, atmosphere furnace, ion nitriding furnace, natural gas combustion heating furnace, Al2O3 and SiO2 floating particle furnace are pollution-free equipment. PAG polymer quenchers, non-cfc-solvent, Al2O3 and SIO2 floating particles, nitrogen and various inert gases are cleaning materials. At present, quenching oil is widely used at home and abroad. Now at home and abroad to quench soot directly into the atmosphere emissions of enterprises are still many, China thermal association in the "eleventh five-year" emission reduction plan has listed it as a key to solve the problem, has proposed several soot harmless treatment of emissions methods and facilities.
3, less massless dispersion due to the fluctuation of the chemical composition of the material, the uneven temperature in the furnace, the difference in heating and cooling conditions and the difference in operating human factors will make the quality of the heat treatment parts of the same furnace significantly different, the quality of products of different furnaces can not be repeated. The use of scientific management and advanced technology can minimize such differences. One of the goals for 2020 is to reduce the mass dispersion of heat-treated parts to "zero." In order to achieve this goal, the reliability of equipment, accurate and stable control of process parameters, high uniformity of furnace temperature and gas circulation, stability of material composition, on-line quality control and elimination of human factors are important subjects. In addition, scientific management, ISO9000 certification, raw materials into the factory inspection, before and after the process of cooperation and connection, the careful implementation of standards are also closely related to the dispersion of product quality. It can be seen that reducing the dispersion of quality is a kind of systematic engineering from technology to management. Only through long-term, meticulous and practical work can good results be achieved step by step.
4. Shape and size changes inevitably occur during heat treatment of metal parts with less distortion. Excessive and uneven distortion will increase the final finishing margin, and in severe cases, the parts will be scrapped. Parts that are no longer processed after heat treatment will also lose interchangeability due to severe distortion, worsen contact surface, and increase vehicle or machine noise. Minimizing heat treatment distortion has been a lifelong effort of many heat treatment specialists. U.S. heat treatment line chart 2020 one of the goals is to achieve "zero" distortion in heat treated parts. Developing new quenching cooling medium and cooling method, adopting isothermal graded quenching, variable circulation of cooling medium, high-pressure gas quenching, etc. can make the workpiece obtain uniform quenching cooling, reducing the temperature difference between the surface and the core are widely adopted in modern times to reduce the distortion measures. To maintain the stability of the chemical composition of the parts and the use of controlled hardenability steel (H steel) can make the quenching distortion has a stable law, it is convenient to specify the exact processing margin, choose the appropriate less distortion measures.
5. Less oxidization-free heating of metals in air and oxidizing media will lead to the loss of metals due to oxidation, which will also damage the surface state and accuracy of parts and products. Modern heat treatment heating as far as possible to avoid in the atmosphere of oxidation, and the use of neutral, inert gas protection, coated with protective coating or wrapped with stainless steel foil, heating in a deep vacuum can completely avoid oxidation. Induction methods with very short heating times, salt bath and fluidized bed heating can minimize the oxidation of metals. The combustion ratio controlled to a certain degree of reduction of the fuel furnace can also reduce the oxidation of heated metal to a certain extent.
6, less decarburized steel parts in the air and other oxidation atmosphere heating, oxidation with the surface also accompanied by the reduction of carbon content on the surface, the formation of surface decarburization. Decarburization can reduce the surface hardness, wear resistance and tensile stress of steel. The heating method of less decarbonization is basically the same as that of less oxidation, but the process conditions are more severe. To avoid decarburization, the furnace gas carbon potential needs to be adjusted to meet the carbon content of the steel surface in the controlled atmosphere with multiple mixing. The decarburized steel can also be heated in the corresponding carbon atmosphere to restore the original carbon content of the steel. Heating in a deep vacuum does not decarbonize, but in inert or neutral gases it must be heated so that the water content or dew point is fairly low (< -60℃). After heating in floating particle furnace, salt bath, deep layer and package, there is little effect of decarburization. Although there is slight oxidation in induction heat treatment, there is no significant decarburization.
7, less waste products from the design of the parts and repair, the choice of materials, material, machining process and process route optimization, database and expert decision system optimization technology and equipment, equipment ensure the reliability of the process parameters and quality control of online, nondestructive automatic detection system to complete processing and heat treatment process, implement total quality control of products, make the rejection rate and reprocessed product is zero, 100% qualified is not dream. Strict management, superb technology, reliable equipment, accurate sensing, precision control of the complete system engineering is to achieve the full guarantee of no waste, no rework product production.
8. Manual operation without manual heat treatment is a kind of heavy manual labor in a harsh environment. Some developed countries have found it difficult to recruit heat treatment operators. Manual operation will also cause different product quality fluctuations. Too much labor also increases production costs. Therefore, under the premise of mass production can be organized to achieve automated production and unmanned operations as soon as possible is no longer a vision for the future heat treatment, in some developed countries have been able to witness the miracle of this manufacturing technology. But there must be a correct understanding that unmanned operation does not mean unmanned monitoring. The implementation of unmanned operations must have sufficient technical strength, management level and talent guarantee, the normal supply of energy and electricity, high reliable equipment, sound maintenance, reliable control system, accident timely alarm, fault self-diagnosis and timely elimination of the conditions are indispensable. A mistake in any link could have serious or even disastrous consequences. Unmanned production lines can only be a natural product of a country's development to a certain extent and an enterprise's development to a fairly advanced level.