Ways to improve the efficiency of induction heating furnace
1. Correctly select the current frequency
The correct selection of the current frequency according to the diameter or thickness of the workpiece is the fundamental guarantee for improving the efficiency of the induction heating furnace. The ratio of the diameter (or thickness) of the workpiece to the penetration depth of the current determines the electrical efficiency. For the relationship between the two, please note that the electrical efficiency should not be less than 80% when designing the induction heating furnace. When the electrical efficiency is too low, the transverse magnetic flux heating induction furnace should be adopted to improve the electrical efficiency.
2. Transverse magnetic field heating induction heating furnace
Transverse magnetic field heating is essentially that the magnetic field lines are perpendicular to the heating surface of the workpiece. At this time, the eddy current flows on the surface of the heated workpiece in a plane shape. Another induction heating furnace for heating thin plates, which uses the most commonly used strip heating induction heating furnace with additional magnetic conductors. Both the upper and lower sides are provided with inductive conductors with planar circulating currents. There is a bundle of permeable magnets across the induction conductor, and the current direction of the induction conductor on both sides of the plate is the same, which is the characteristic of this induction heating furnace.
3. Use rectangular tubes instead of round tubes
Rectangular tubes and circular tubes have different current distributions in cross-section. When the gap is the same, the efficiency of the rectangular tube is 10% higher than that of the circular tube. The current distribution on the cross section of the circular tube and the rectangular tube and the thermal pattern on the workpiece.
4. Reasonably distribute the conductive length of each part of the induction heating furnace
Each induction heating furnace is composed of two parts, namely the conductive plate and the effective coil. The voltage on the induction heating furnace must be distributed between the conductive plate and the effective coil, and their resistance is very small (and their own inductive reactance). Compared with), the distribution of voltage basically depends on the inductive reactance. The larger the inductive reactance, the more voltage is distributed. Therefore, the greater the ratio of the expanded length of the effective loop to the length of the conductive plate, the more power that the effective loop can distribute. Therefore, when the length of the conductive plate is longer, in order to increase the effective coil expansion length, a multi-turn induction heating furnace should be used. However, excessively increasing the number of turns will destroy the matching between the load and the oscillation circuit, so the number of turns must be moderate. This should also be noted.
5. Reduce the contact resistance of the connection surface of the induction heating furnace
There is contact resistance between the contact plate of the induction heating furnace and the joint of the quenching transformer, and between the opening and closing surfaces of the switching induction heating furnace. Its size is related to the contact pressure, contact form, contact area, contact material and other factors. Therefore, the contact surface of the induction heating furnace is required to have a good surface roughness and a certain contact pressure. When the contact pressure is lower than the critical value, the contact resistance will increase, leading to a vicious circle of heating and oxidation of the contact surface and further increase of the contact resistance. Therefore, the pressure arrangement of the contact surface should be designed reasonably.
6. Adopt conductive magnet
When the inner hole or flat surface of the workpiece is heated, its efficiency is lower than that of the outer circle heating. After the effective coil straddles the permeable magnet, the heating efficiency is improved. Nowadays, there are specialized factories in developed countries that install magnets for induction heating furnace which are not only used for inner hole and plane heating, but also for outer circle heating. In addition to ferrite magnetic ceramics and silicon steel sheets, the materials of the magnets have also been developed to process high and medium frequency magnets and slush magnets, which can be made into any shape required.
Reduce the offset effect of the effective magnetic field lines and avoid bad design
