Energy-Saving Technology for Heat Treatment of Induction Furnace
1. The heat treatment process of induction furnace: In traditional process calculation time: T = k × a × D, T is heating time, K is charging coefficient, A is heating coefficient, D is the effective thickness of the workpiece. In actual production, we usually calculate holding time based on previous work experience and the effective thickness of the workpiece, and in large quantities, we observe the fire color of workpieces according to actual experience, which is mainly reflected in carbon steel and low alloy steel This is due to the fact that there are no alloying elements and carbides in the carbon steel, so it is not necessary to keep the temperature for a long time to homogenize the austenitizing process. In other words, when the heat transfer coefficient of the workpiece reaches zero, that is to say, when the heat transfer coefficient of the workpiece reaches zero, that is to say, when the heat transfer coefficient of the workpiece reaches zero, it is mainly determined by the heat transfer time of the workpiece Hot. For mass production, we usually heat the furnace first and then put the workpiece into the furnace. When the furnace temperature reaches the processing time again, a certain homogenization time is added. This can shorten the process cycle, save energy, and reduce costs. Alloy structural steel (40Cr, 35CrMo, 42CrMo) and so on, because of the addition of some alloy elements in the material, it takes a certain time to homogenize the carbide in the heating process, so it takes a little more time than the carbon steel, and generally, it takes about 60% – 80% of the traditional process time. This can shorten the heating time of steel parts at high temperature and reduce the deformation A little less, the austenite grain is relatively small, fine martensite structure can be obtained after quenching, and its mechanical properties will be improved to a certain extent, which is also the effect that heat treatment workers want to achieve.
2. Parts charging
1) In actual production, when the number of workpieces is limited, it is not cost-effective to arrange heats separately. In this case, different workpieces and materials can be mixed into one furnace under the condition of roughly the same process parameters, such as Cr12MoV and 8407 or H13, 40Cr, and 42CrMo. The quenching temperature is approximately the same, so the charging capacity can be satisfied. Similarly, when the tempering temperature is the same, different parts and materials can be mixed in one furnace, and the tempering time can be executed according to the longest tempering time.
2) Heat treatment fixture, many products are not nearly the same, and the quantity is not many, but in order to reduce the deformation, sometimes heat treatment tooling is added, many times do not use heat-resistant stainless steel, most of them are replaced by ordinary low-carbon steel, mainly because the material price is low, and there is not a lot of quantity.
3. Cooling medium for heat treatment many mechanical parts are alloy structural steel, so when considering the quenching medium, water solution quenching can avoid large-diameter medium carbon low alloy steel. The hardness value of oil quenching for large diameter medium carbon low alloy steel may not reach, and water quenching is easy to crack. Water-soluble synthetic quenching fluid is especially suitable for induction and quenching of low and medium carbon steel, and water-soluble synthetic quenching fluid is especially suitable for low and medium carbon steel Different cooling rates can be obtained by adjusting the concentration of steel induction and large workpiece quenching. The quenched workpiece is bright and has a short-term anti-rust effect. It can be tempered directly without cleaning and without oil fume. No lampblack, no burning, no fire danger, improve the working environment. It is not easy to aging and deterioration and has a long service life compared with oil products. The cost is also relatively small.
4. Tempering process：The tempering process is to determine the furnace waste heat to be used according to the tempering temperature of the parts. The general rule is that the tempering temperature of the parts is about 300 degrees lower than the residual heat temperature of the furnace. In this way, the furnace will quickly reach the set value of the tempering process temperature after the workpiece is put into the furnace, and multiple tempering is better than one tempering. Therefore, in mass production, the microstructure and properties obtained by such secondary tempering are better than those by one tempering Fire is better, and the cost is much lower.
5. Equipment maintenance and maintenance in the production of regular maintenance equipment, check the furnace, furnace door sealing. The relevant instruments and meters of the distribution box shall be calibrated and maintained regularly to reduce the loss caused by a shutdown caused by an electrical failure. The maintenance of relevant operation equipment such as trolley and the traveling crane can reduce the loss caused by inconvenience in and out of the furnace.
6. The quality control of heat treatment is actually energy saving when the workpiece is heat treated. If a workpiece is not effectively and reasonably heat-treated, the service life of the part will not be very long. If the component fails in the early stage, it is necessary to manufacture new parts to replace it. In this way, raw materials, machining hours, and other related costs must be consumed. The effective and reasonable heat treatment can increase the service life of the workpiece. Therefore, the high quality of heat treatment can avoid the early failure of the workpiece, and avoid a series of procedures such as normalizing, re quenching and tempering, correction, stress relief, and tempering, etc. The energy-saving technology of heat treatment of medium frequency smelting furnace is incomparable.
