What is the principle of high frequency quenching? What is the difference between high frequency quenching and intermediate frequency quenching?
Quenching can improve the hardness and wear resistance of metal workpieces. Through the combination of quenching and tempering at different temperatures, the strength and toughness of the metal can be greatly improved to meet different application requirements. Compared with other power frequency and medium frequency quenching, high-frequency quenching has better quenching quality, the workpiece is not easy to oxidize, has high hardness, small deformation, and high production efficiency. The following editor will take you to understand the high frequency quenching. High-frequency quenching is mostly used for surface quenching of industrial metal parts. It is a metal heat treatment method that generates a certain induced current on the surface of the workpiece, rapidly heats the surface of the part, and then rapidly quenches it. Induction heating equipment, that is, equipment for induction heating of workpieces for surface quenching. The principle of induction heating: the workpiece is placed in the inductor, and the inductor is generally a hollow copper tube inputting intermediate frequency or high frequency alternating current (1000-300000Hz or higher). The alternating magnetic field generates an induced current of the same frequency in the workpiece. The distribution of this induced current in the workpiece is uneven, it is strong on the surface, but very weak in the interior, and it is close to 0 in the center. This skin effect is used. , the surface of the workpiece can be heated rapidly, the surface temperature rises to 800-1000 ℃ in a few seconds, and the temperature of the core part is very small. Heating frequency Selection of induction heating frequency: The frequency is selected according to the technical requirements of heat treatment and the requirements of heating depth. The higher the frequency, the shallower the heating depth. The depth of high frequency (above 10KHZ) heating is 0.5-2.5mm, which is generally used for heating of small and medium-sized parts, such as small module gears and small and medium-sized shaft parts. The intermediate frequency (1~10KHZ) heating depth is 2-10mm, which is generally used for the heating of shafts with large diameters and gears with large and medium modules. The depth of the hardened layer by power frequency (50HZ) heating is 10-20mm, which is generally used for diathermy of larger-sized parts and surface quenching of large-diameter parts (diameter Ø: 300mm or more, such as rolls, etc.). The depth of the surface hardened layer of induction heating quenching depends on the frequency of the alternating current. Generally, the higher the frequency, the shallower the heating depth, and the shallower the depth of the hardened layer. The relationship between frequency f and heating depth δ has the following empirical formula: δu003d20/√f(20°C); δu003d500/√f(800°C). In the formula: f is the frequency, the unit is Hz; δ is the heating depth, the unit is millimeter (mm). Induction heating surface quenching has the advantages of good surface quality, small brittleness, quenched surface is not easy to oxidize and decarburize, and small deformation, so induction heating equipment has been widely used in metal surface heat treatment. Induction heating equipment is a device that generates an induction current of a specific frequency and performs induction heating and surface quenching treatment, Kehua. The difference between high-frequency quenching, high-frequency quenching and intermediate-frequency quenching The intermediate-frequency quenching has a deep hardened layer (3~5mm), which is suitable for parts that are subject to twisting and pressure loads, such as crankshafts, large gears, grinder spindles, etc. (the material used is 45# steel , 40Cr, 9Mn2V and high-frequency quenching of ductile ink can harden the surface in a short time! The crystal structure is very fine! The structural deformation is small, the surface stress of the intermediate frequency is smaller than that of the high frequency. 50HZ is called power frequency, and the heating depth is 5-10 1000-10000HZ It is called intermediate frequency. The principle of 'high frequency quenching' and 'intermediate frequency quenching' is the same, so there are certain criteria for the selection of intermediate frequency quenching equipment. Oxidation, small deformation, good quenching quality, high production efficiency, suitable for parts that work under friction conditions, such as generally small gears and shafts (the materials used are 45# steel, 40Cr). Above 10000HZ is called high frequency quenching. High Frequency quenching is mostly used for surface quenching of industrial metal parts. It is a metal heat treatment method that generates a certain induction current on the surface of the workpiece, rapidly heats the surface of the part, and then rapidly quenches the Kehua fire. Equipment for surface quenching. High-frequency quenching distinguishes the principle of induction heating: the workpiece is placed in the inductor, and the inductor is generally a hollow copper tube that inputs intermediate frequency or high frequency alternating current (1000-300000Hz or higher). The induction current of the same frequency is generated in the workpiece. The distribution of this induction current in the workpiece is uneven. It is strong on the surface and weak in the interior. It is close to 0 in the center. Using this skin effect, the surface of the workpiece can be Rapid heating, the surface temperature rises to 800-1000 ° C in a few seconds, while the core temperature rises very little. The intermediate frequency quenching is to place the metal part in an induction coil, and the induction coil is connected to alternating current to generate an alternating electromagnetic field , which induces alternating current in the metal parts. Due to the skin effect, the current is mainly concentrated on the surface of the metal parts, so the surface temperature is the highest, and water spray cooling or other cooling is followed immediately below the induction coil, because the heating and cooling are mainly concentrated On the surface, so the surface modification is obvious, but the internal modification is basically not, and it can have a very special heat treatment effect. The above is the relevant introduction about high frequency quenching, the important factors of the quenching effect, the hardness requirements and testing methods of the quenched workpiece, It is not high frequency that can solve the problem. In addition, workers should pay attention to safety during quenching.