The power saving principle of electromagnetic induction heating technology is to make the metal heated body heat itself, and according to the specific situation, a certain heat insulation material can be wrapped outside the heating body, which greatly reduces the heat loss and improves the thermal efficiency, so the power saving effect Very significant, up to 30% to 80%.
1. Insufficiency of existing heating methods
At this stage, the heating method used by heating equipment such as plastic machinery on the market is generally electric heating coil, which transfers heat to the heated body through contact conduction, but only the heat close to the inside of the barrel surface will be better. When it is transmitted to the heated body, most of the heat outside is lost to the air, and there is a heat conduction loss, which leads to an increase in the ambient temperature. In addition, the resistance wire heating has a disadvantage of low power density, which cannot be used in some occasions that require higher temperature. Satisfied.
2. Power saving principle
The electromagnetic heating system consists of two parts: the electromagnetic heating control board and the heating coil. The temperature-controlled power supply [heating output contactor (or solid-state relay) output terminal] of the original machine rectifies, filters, and inverts the power-frequency AC power into high-frequency AC power through the electromagnetic heating control board, and connects it to the electromagnetic heating coil through the connecting wire. The high-frequency alternating current acts on the metal heated body through the insulation material to make the heated body heat itself. In addition, the power supply can also be directly input to the electromagnetic heating control board, and the original temperature controller directly controls the working state of the electromagnetic heating control board through the soft start interface of the electromagnetic heating controller.
One of the advantages of this heating method is that the equipment does not need to be preheated for a long time, it can be started or stopped at any time, and it only takes more than ten seconds to reach the set heating temperature.
Note that induction is a non-contact heating method and the coil never actually touches the workpiece at any point.
The eddy currents generate their own magnetic field, which opposes the original magnetic field generated by the coil. This opposition prevents the original magnetic field from penetrating immediately to the center of the object surrounded by the coil.
Eddy currents are most active close to the surface of the object being heated, but become much weaker towards the center.
The distance from the surface of the heated object to the depth at which the current density drops to 37% is the penetration depth. This depth increases with decreasing frequency. Therefore, the correct frequency must be selected to achieve the desired depth of penetration.
The off-line rotary pipe induction heating system production line independently developed by Hangao Tech (SEKO Machinery) has been tested and can effectively save energy by up to 50%. The whole production process includes automatic feeding-front and rear tube speed synchronization-induction heating-water cooling-automatic unloading. The equipment is customized according to the customer's specific order requirements and can handle a caliber range from 219 to 1219MM. The pipe is conveyed by rotating rollers, which avoids the collapse and deformation of the large-diameter steel pipe due to the softening of the material after heating, and solves the problem of secondary straightening. This equipment has been applied in many domestic leading pipe manufacturing enterprises, and has been fully proved by the market.
