High-frequency heating: The current frequency is 100-500 kHz, resulting in a hardening depth of 0.5-2 mm;
Medium-frequency heating: The current frequency is 500-10000 Hz, resulting in a hardening depth of 2-10 mm.
The heating principle of a high-frequency melting furnace is that a high-frequency, high-current flows through a heating coil wound into a ring or other shape (usually made of copper tubing). This generates a strong, rapidly changing magnetic flux within the coil. When a metal or other object to be heated is placed inside the coil, the magnetic flux penetrates the entire object. A corresponding large eddy current is generated within the heated object in the opposite direction to the heating current. Due to the resistance within the heated object, a large amount of Joule heat is generated, causing the object's temperature to rise rapidly, achieving the purpose of heating all metal materials.
The heating principle of a medium-frequency melting furnace uses a three-phase bridge controlled rectifier circuit to rectify AC power into DC power. After smoothing by a reactor, it becomes a constant DC current source. When the magnetic flux surrounded by the conductor loop changes, an induced electromotive force is generated in the loop. Similarly, a conductor in an alternating magnetic field also generates an induced electromotive force due to electromagnetic induction. This forms an induced current in the conductor. The induced current overcomes the conductor's own resistance and generates Joule heat. This heat is used to heat the conductor itself, causing it to heat up and melt, achieving various thermal processing purposes.
High-frequency melting furnaces are fast, inexpensive, small in size, and occupy little space. The temperature can reach up to 1600℃. High-frequency melting furnaces are economical and practical, with high melting efficiency and rapid melting of various metals;
Medium-frequency melting furnaces are lightweight, have fast heating speed, high efficiency, and save electricity. They also have multiple protection functions such as overcurrent, overvoltage, and overheating. They are easy to operate and install, and the temperature can reach up to 2600℃. It not only eliminates the strong noise, production hazards, excessive metal splashing, and high material loss associated with traditional oxygen-fueled metal melting, but also offers the advantages of being harmless to the human body, safer and faster operation, and improved productivity.
High-frequency melting furnaces are suitable for melting 1-5 kg of precious metals, mainly used for small and medium-sized parts requiring a thin hardened layer, such as large-module gears and small and medium-sized shafts.
Medium-frequency melting furnaces are suitable for melting 5 kg to 60 tons of various metals, mainly used for parts requiring a deeper hardened layer, such as medium-module gears, large-module gears, and shafts with larger diameters.
