induction phenomenon is the occurrence of induced currents. In the case of heaters trajectory of motion of the carriers have a vortex nature and significant amplitude. As a result, the metal is heated abruptly. In industrial applications currents of different frequencies are used, but not above 1 MHz, otherwise the penetration depth sharply decreases. However, the application is. Likewise possible to harden the surface of other axes and the elongated parts, which are difficult to treat other method. Local surface heating causes the formation of austenite, followed by rapid cooling to martensite. It used in metallurgy and metal processing and tempering process of steel to impart plasticity. The induction heater is simplified industrial unit of reduced size and low power.
Induction in industry and everyday life
For the induction process is characterized by a minimum inertia. It should appear alternating field, occur in response to eddy currents. The advantage: there is practically no radiation, the field decays rapidly with distance. Therefore, the radio frequency begins on hundreds of kHz. According voiced reason to use the specified wavelengths in the industry already unprofitable. Spiral induction heater in this case becomes an antenna. Another thing ultrasound frequencies lying below. Excellent induce eddy currents and do not harm the workers (operators, consumers, cooks), using the equipment.
Industrial induction heaters have tremendous power - 100 kW or more. Under these conditions the metal is heated by the two processes mentioned above, hardening and tempering, simply melted. On this principle the induction furnace with amazing abilities for power consumption. Embodies the idea: energy is transmitted directly to steel, heated eyes. This allows the use of the phenomenon of induction in blacksmithing.
Several areas where heating is required, said devices successfully solves the problem:
- metal stamping;
- welding and brazing;
- annealing;
- normalization of steel.
In household use of induction heating in appliances for cooking food and water heaters. This allows expensive freewheeling devices simultaneously with high efficiency. Troika titles at the hearing, where the technology is used:
- Multivarki.
- Cooktops.
- Water heaters.
We do not exclude the presence of other devices to facilitate a person's life.
Thus, the operating principle of the induction heater industrial type is as follows. The input voltage is rectified and supplied to the inverter input, the pulse generating the desired frequency. The cookers with decreasing wavelength fever. It is possible that a similar effect is used in induction heaters. The main element is a coil (Nikola Tesla). The shape of the heated portion is dependent. The helical coil spring in the form of raised temperature of the part, which inside (e.g., tube), plus details of the outside (inside the tube).
Readers will represent the effect of the pictures from school textbooks. Remember how the magnetic field penetrates the coil: maximum density of lines of tension falls on the center line design, invented by Laplace.
The material is a copper tube. It has good electrical conductivity and strength. Since the high-frequency current flows mainly along the surface, the interior of the conductor is not engaged. It is relatively cheap and lightweight construction. At a frequency of 50 Hz is irrelevant, most suitable for the current acoustic range and above. The additional torque - electrical resistance. Does not increase the effect, removing the core, the current is already under way on the surface. The higher the power of the induction heater, the thicker tube. Simultaneously, the electrical resistance decreases.
Simultaneously, in a ferromagnetic material, necessarily become the coil core, at which high frequency current flows, magnetic flux occurs, according to the voltage-changing direction. The effect is accompanied by heat, which is wasted on power induction heater. Because efficiency is so high.
The coil is not heated. In any case, covered with a special material: ceramic fabric or rigid structure. This is done for reasons of:
- To peremknulo coil windings are not interconnected, then operation of the device would be compromised.
- The second reason for industrial induction heater serves as protection against hot-hot parts, sometimes related coil.
Modern materials can easily withstand temperatures of over 1000 ° C without consequences.
Apparatus induction heaters
The operating principle of the induction heater resembles industrial equivalents. Only the functional and task much more modest. Induction heater is intended for feeding a working coil and a high frequency power current. As a result, the core begins to warm up. There is located a pipe with water - a typical water-heater. Sol that the throttle induces an alternating magnetic flux in a steel pipe and the water flowing past, picks up heat. Does not mean that the induction heater is not suitable for plastic risers, they may attach. But the steel pipe inside the device.
Compared with industrial induction heaters thing a lot easier. Is a copper transformer, like a welding machine, transmitting coil current. Directly involve undesirable, will something like a short circuit. We believe that should be within the ordinary thermostat to control the temperature and the potentiometer for power change. In irons.
Separate fans offer induction heater manufactured by placing their hands in polyethylene pipe segment of the drill steel, barely passing inside diameter. Laid around the structure lengthwise wooden slats. Top coil wound covering tube. By passing in the AC coils drill shock starts to warm up. It is understood that as a result of the passage of water inside the tube, the jet will get the lion share of heat.
Fans recommend the use of welding inverter loaded onto the spool reinforced stekloizolyatsiey wire wrapped around the inside of the pipe with a drill. So get rid of the need to invent. But remembering about the cost of welding inverter, do not dare call the invention a success. But probably safe to try out ideas - working or not. The difficulty in creating a suitable design of the generator. Unlikely to flow from outlet 50 Hz lay the induction currents and reverse it magnetization domains. Otherwise, why manufacturers of industrial electric heaters and try to make the power supply to the instrument.
These fans recommend choosing the frequency of the power unit 50 kHz. To assemble the inverter power 3-6 kW, have great sweat. Not every house cork pull a load. Now outlined disadvantages of induction heaters. Benefits - in great efficiency. The operating principle of the induction heater is based on two aspects:
- Eddy currents caused by electromagnetic wave inevitably arises when there are variable electric or magnetic field. In the metal induced effect, regardless of affiliation to a ferromagnetic material.
- magnetization reversal effect also causes heating. The alternating magnetic field changes the orientation of the domain, which is accompanied by a thermal effect. Above the Curie point, the phenomenon disappears. For steel, the magnetic properties loss temperature is above 700 ° C. Because utensils for induction hob steel is chosen. Aluminum will be heated solely by the eddy currents, so much slower than iron. I became an electrical resistance is greater than that is an added advantage.
Output
Advantages of induction heaters:
- Energy savings of up to 30% relative to other devices.
- Without inertia.
- Durability. Vortex Induction heaters from Izhevsk operate up to 30 years under the manufacturer's warranty of 3 years.
- Environmentally friendly controversial, if you remember about heat pumps, but it's better than burning wood, coal and gas.
Device required insulate basalt wool to not warmed air, and a pipe. Otherwise, get more convection losses. And basalt wool protects the coil from the pipe, not otherwise. The use of induction heaters own design is problematic today. The waveform generator may collect on its own or use an inverter, welding or the hob. Fault Izhevsk connected in series for heating and water supply purposes. But not at home.
