Brick / 03.03.2020

Mini induction melting furnace. Induction furnaces: principles of operation, drawings, how to do it yourself. DIY induction furnaces

The induction furnace is no longer a novelty - this invention has existed since the 19th century, but only in our time, with the development of technology and the element base, it finally begins to enter everyday life everywhere. Previously, there were many questions in the intricacies of the operation of induction furnaces, not all physical processes were fully understood, and the units themselves had a lot of shortcomings and were used only in industry, mainly for melting metals.

Now, with the advent of powerful high-frequency transistors and cheap microcontrollers that have made a breakthrough in all areas of science and technology, truly efficient induction furnaces have appeared that can be freely used for domestic needs (cooking, heating water, heating) and even assemble hands.

Physical basis and principle of operation of the furnace

Fig.1. Scheme of the induction furnace

Before choosing or making an inductor heater, you should understand what it is. Recently, there has been an outbreak of interest in this topic, but few people have a complete understanding of the physics of magnetic waves. This gave rise to many misconceptions, myths and a lot of inefficient or unsafe homemade products. You can make an induction furnace with your own hands, but before that you should get at least basic knowledge.

The induction stove is based on the principle of electromagnetic induction. The key element here is the inductor, which is a high quality inductor. Induction Furnaces are widely used for heating or melting electrically conductive materials, most often metals, due to the thermal effect of inducing an eddy electric current in them. The above diagram illustrates the design of this furnace (Fig. 1).

Generator G produces a variable frequency voltage. Under the action of its electromotive force, an alternating current I 1 flows in the inductor coil L. The inductor L together with the capacitor C is an oscillatory circuit tuned to resonance with the frequency of the source G, due to which the efficiency of the furnace is significantly increased.

In accordance with physical laws, an alternating magnetic field H arises in the space around the inductor L. This field can also exist in the air, but special ferromagnetic cores are sometimes used to improve performance, which have better magnetic conductivity compared to air.

lines of force magnetic field pass through an object W placed inside the inductor and induce a magnetic flux F in it. If the material from which the workpiece W is made is electrically conductive, an induced current I 2 appears in it, which closes inside and forms eddy induction flows. In accordance with the law of the thermal effect of electricity, eddy currents heat up the object W.

Making an inductive heater

An induction furnace consists of two main functional blocks: an inductor (a heating induction coil) and a generator (an alternating voltage source). The inductor is a bare copper tube coiled into a spiral (Fig. 2).

To make a do-it-yourself furnace with a power of not more than 3 kW, the inductor must be made with the following parameters:

tube diameter - 10 mm;
spiral diameter - 8-15 cm;
the number of turns of the coil - 8-10;
the distance between the turns is 5-7 mm;
the minimum gap in the screen is 5 cm.

Adjacent turns of the coil must not be allowed to touch, keep the specified distance. The inductor must not come into contact with the protective screen of the furnace in any way, the gap between them must not be less than the specified one.

Generator manufacturing

Fig.3. Scheme on lamps

It is worth noting that an induction furnace for its manufacture requires at least average radio engineering skills and abilities. It is especially important to have them to create the second key element - a high-frequency current generator. Neither assembling nor using a do-it-yourself oven will work without this knowledge. Moreover, it can be life-threatening.

For those who undertake this business with knowledge and understanding of the process, there are various ways and schemes by which an induction furnace can be assembled. When choosing a suitable generator circuit, it is recommended to abandon options with a hard emission spectrum. These include the widespread scheme using a thyristor key. High-frequency radiation from such a generator is capable of creating powerful interference for all surrounding radio devices.

Since the middle of the 20th century, an induction furnace assembled on 4 lamps has enjoyed great success among radio amateurs. Its quality and efficiency are far from the best, and radio tubes are difficult to access nowadays, however, many continue to assemble generators according to this scheme, since it has a great advantage: a soft, narrow-band spectrum of the generated current, due to which such a furnace emits a minimum of interference and as safe as possible (Fig. 3).

The operating mode of this generator is set using a variable capacitor C. The capacitor must be with an air dielectric, the gap between its plates must be at least 3 mm. The diagram also contains a neon lamp L, which serves as an indicator.

Scheme of a universal generator

Modern induction furnaces operate on more advanced elements - microcircuits and transistors. The universal scheme of a push-pull generator, which develops power up to 1 kW, is enjoying great success. The principle of operation is based on an independent excitation generator, while the inductor is switched on in the bridge mode (Fig. 4).

Advantages of a push-pull generator assembled according to this scheme:

The ability to work on the 2nd and 3rd mode in addition to the main one.
There is a surface heating mode.
Control range 10-10000 kHz.
Soft spectrum of radiation in the entire range.
Does not need additional protection.

Frequency tuning is carried out using a variable resistor R 2 . The operating frequency range is set by capacitors C 1 and C 2 . The interstage matching transformer must be with a ring ferrite core with a cross section of at least 2 sq.cm. The winding of the transformer is made of enameled wire with a cross section of 0.8-1.2 mm. Transistors must be seated on a common radiator with an area of \u200b\u200b400 sq. Cm.

Conclusion on the topic

The electromagnetic field (EMF) emitted by the induction furnace affects all the conductors around. It also affects the human body. The internal organs under the action of EMF are evenly warmed up, the overall body temperature rises throughout the entire volume.

Therefore, when working with the oven, it is important to observe certain precautions in order to avoid negative consequences.

First of all, the generator housing must be shielded with a casing made of galvanized iron sheets or fine mesh. This will reduce the radiation intensity by 30-50 times.

It should also be borne in mind that in the immediate vicinity of the inductor, the energy flux density will be higher, especially along the winding axis. Therefore, the induction coil must be placed vertically, and it is better to observe the heating from afar.

Induction heaters work on the principle of “getting current from magnetism”. In a special coil, a high-power alternating magnetic field is generated, which generates eddy electric currents in a closed conductor.

closed conductor in induction cookers is a metal utensil that is heated by eddy electric currents. In general, the principle of operation of such devices is not complicated, and with little knowledge in physics and electrical engineering, it will not be difficult to assemble an induction heater with your own hands.

The following devices can be made independently:

Devices for heating the coolant in the heating boiler.
Mini ovens for melting metals.
Plates for cooking food.

Do-it-yourself induction cooker must be made in compliance with all norms and rules for the operation of these devices. If electromagnetic radiation dangerous for humans is emitted outside the case in the lateral directions, then it is strictly forbidden to use such a device.

In addition, a great difficulty in the design of the slab lies in the selection of material for the base. hob, which must meet the following requirements:

Ideal for conducting electromagnetic radiation.
Not conductive.
Withstand high temperature stress.

In household induction hobs, expensive ceramics are used; in the manufacture of an induction cooker at home, it is rather difficult to find a worthy alternative to such material. Therefore, to begin with, you should design something simpler, for example, an induction furnace for hardening metals.

Blueprints

Figure 1. Electrical diagram of an induction heater. Figure 2. Device. Figure 3. Diagram of a simple induction heater.

For the manufacture of the furnace you will need the following materials and tools:

soldering iron;
solder;
textolite board.
mini drill.
radioelements.
thermal paste.
chemical reagents for board etching.

Additional materials and their features:

To make a coil, which will emit an alternating magnetic field necessary for heating, it is necessary to prepare a piece of copper tube with a diameter of 8 mm and a length of 800 mm.
Powerful power transistors are the most expensive part of a homemade induction installation. To mount the frequency generator circuit, it is necessary to prepare 2 such elements. For these purposes, transistors of brands are suitable: IRFP-150; IRFP-260; IRFP-460. In the manufacture of the circuit, 2 identical of the listed field-effect transistors are used.
For the manufacture of an oscillatory circuit you will need ceramic capacitors with a capacity of 0.1 mF and an operating voltage of 1600 V. In order for a high-power alternating current to form in the coil, 7 such capacitors are required.
During the operation of such an induction device, field-effect transistors will get very hot and if aluminum alloy radiators are not attached to them, then after a few seconds of operation at maximum power, these elements will fail. Transistors should be placed on heat sinks through a thin layer of thermal paste, otherwise the efficiency of such cooling will be minimal.
Diodes, which are used in an induction heater, must be of ultra-fast action. The most suitable for this circuit, diodes: MUR-460; UV-4007; HER-307.
Resistors used in circuit 3: 10 kOhm with a power of 0.25 W - 2 pcs. and 440 ohm power - 2 watts. Zener diodes: 2 pcs. with an operating voltage of 15 V. The power of the zener diodes must be at least 2 watts. A choke for connecting to the power outputs of the coil is used with induction.
To power the entire device, you will need a power supply unit with a capacity of up to 500. W. and voltage 12 - 40 V. You can power this device from a car battery, but you will not be able to get the highest power readings at this voltage.

The very process of manufacturing an electronic generator and coil takes a little time and is carried out in the following sequence:

From a copper pipe a spiral with a diameter of 4 cm is made. To make a spiral, a copper tube should be wound onto a rod with a flat surface with a diameter of 4 cm. The spiral should have 7 turns that should not touch. Mounting rings are soldered to the 2 ends of the tube for connection to the transistor radiators.
The printed circuit board is made according to the scheme. If it is possible to supply polypropylene capacitors, then due to the fact that such elements have minimal losses and stable operation at large amplitudes of voltage fluctuations, the device will work much more stable. The capacitors in the circuit are installed in parallel, forming an oscillatory circuit with a copper coil.
Metal heating occurs inside the coil, after the circuit is connected to a power supply or battery. When heating the metal, it is necessary to ensure that there is no short circuit of the spring windings. If you touch the heated metal 2 turns of the coil at the same time, then the transistors fail instantly.

Nuances

When conducting experiments on heating and hardening metals, inside the induction coil the temperature can be significant and amounts to 100 degrees Celsius. This heating effect can be used to heat domestic water or to heat a house.
Scheme of the heater discussed above (Figure 3), at maximum load it is able to provide the radiation of magnetic energy inside the coil equal to 500 watts.
Such power is not enough to heat a large volume of water, and the construction of a high power induction coil will require the manufacture of a circuit in which it will be necessary to use very expensive radio elements.
A budget solution for organizing induction heating of a liquid, is the use of several devices described above, arranged in series. In this case, the spirals must be on the same line and not have a common metal conductor.
as a heat exchangera stainless steel pipe with a diameter of 20 mm is used. Several induction spirals are “strung” onto the pipe, so that the heat exchanger is in the middle of the spiral and does not come into contact with its turns.
With the simultaneous inclusion of 4 such devices, the heating power will be about 2 kW, which is already enough for flow heating of the liquid with a small circulation of water, to values allowing the use of this design in the supply warm water small house.
If you connect such a heating element to a well-insulated tank, which will be located above the heater, the result will be a boiler system in which the heating of the liquid will be carried out inside the stainless pipe, the heated water will rise up, and a colder liquid will take its place.
If the area of the house is significant, the number of induction coils can be increased up to 10 pieces.
The power of such a boiler can be easily adjusted by turning off or on the spirals. The more sections that are simultaneously turned on, the greater the power of the heating device operating in this way will be.
To power such a module, you need a powerful power supply. If a DC inverter welding machine is available, then a voltage converter of the required power can be made from it.
Due to the fact that the system operates on direct electric current, which does not exceed 40 V, the operation of such a device is relatively safe, the main thing is to provide a fuse box in the generator power circuit, which, in the event of a short circuit, will de-energize the system, thereby eliminating the possibility of a fire.
It is possible to organize “free” heating of the house in this way, provided that batteries are installed to power induction devices, which will be charged using solar and wind energy.
Batteries should be combined in sections of 2, connected in series. As a result, the supply voltage with such a connection will be at least 24 V., which will ensure the operation of the boiler at high power. In addition, series connection will reduce the current in the circuit and increase the battery life.

Exploitation homemade devices induction heating, does not always make it possible to exclude the spread of electromagnetic radiation harmful to humans, therefore the induction boiler should be installed in non-residential premises and shielded with galvanized steel.
Mandatory when working with electricitysafety regulations must be followed and, especially for 220 V AC networks.
As an experimentyou can make a hob for cooking according to the scheme specified in the article, but operate this device constantly not recommended due to the imperfection of self-manufacturing of the shielding of this device, because of this, exposure to the human body of harmful electromagnetic radiation that can adversely affect health is possible.

Source: http://housetronic.ru/otoplenie/obogrevateli/elektroobogrevateli/indukcionnye-svoimi-rukami.html

Induction cooker diagram - basic device

The induction cooker is capable of heating metal utensils by means of induced eddy currents from a high-frequency magnetic field.

The standard scheme of an induction cooker, as a rule, is represented by an induction coil and a frequency converter, as well as an electronic control unit equipped with temperature sensors.

Introduction

Induction cookers are relatively new equipment, but already extremely popular with domestic consumers.

A feature of such stoves is the ability to heat only the bottom of the cookware.

In conventional electric stoves, the switched-on burner is initially heated.

Before choosing such equipment, it is important to familiarize yourself with the advantages of operation, as well as take into account some design flaws induction cooker.

The main advantages are presented:

a faster heating and cooking process, which takes several times less time than with a traditional electric stove;
the absence of burning food that can get on the hob during cooking, due to the low temperature of the burner;
reduction of consumed electrical energy due to the very rapid heating of the used kitchen utensils;
ease of use due to the ability to adjust the cooking mode on different stoves.

The advantages also include safety of operation, which is especially important for families with small children, pensioners or people with disabilities.

Induction cooker in the kitchen

Disadvantages of operation in such modern equipment are also present and, despite the fact that they are minimal, they should be taken into account when choosing a model:

turning on induction equipment at full power can create an increased load on the power grid;
for cooking on this type of stove, only special cookware with a ferromagnetic bottom should be used;
some models are characterized by the presence of a single high-frequency generator, which adversely affects the power level when all burners are turned on at the same time;
The hob is fragile, so during the entire period of operation, some care must be taken.

As practice shows, the operation of models belonging to the economy class price category is often accompanied by annoying noise and a peculiar buzz.

It is important to remember that induction cookers are capable of creating a sufficiently high electromagnetic type of radiation and can have a negative effect on household appliances installed at a short distance.

Scheme of the induction cooker

According to the heating scheme, electricity, which comes from the mains to the coil, undergoes a transformation into a magnetic field that generates vortex flows.

As a result of the interaction of the ferromagnetic bottom with the induction current, a contour is formed, and the resulting thermal energy warms up the used kitchen utensils and their contents.

The glass-ceramic surface of the stove covers an induction coil with an electric current flowing at a frequency of 50 kHz.

The standard equipment layout is relatively complex, and can vary greatly depending on the model.

The basis is represented by an oscillator, a driver on transistors of medium power and an output bipolar transistor with an insulated gate and controlling an inductor coil.

The scheme of operation of the induction cooker is reflected in the rules of service and the features of the operation of such equipment, and must also be taken into account when choosing cookware, which must be made of special materials with ferromagnetic properties.

Electrical diagram of the induction cooker

The most complex structural element is the electronic control unit, through which not only turns on, but also regulates the power level of the generator.

For modern models characterized by the presence of an infrared sensor device that effectively controls the cooking process.

Once the cookware is removed from the hob, the hob will automatically switch off.

Do not use copper, glass, ceramic or aluminum cookware, and the cleaning of the surface of the induction hob is carried out only by means of special means without abrasive effects.

The power circuit of a standard induction cooker can vary significantly depending on design features modifications, but most often presented:

ferrite torus, which is put on the mains wire and suppresses common-mode interference;
standard fuse;
a capacitor that filters impulse noise that occurs during operation;
a resistor that operates after the mains power is turned off;
a rectifier designed for power indicators and effectively protecting the device from overvoltage;
wire shunt;
filtering system for impulse noise;
a capacitor that allows you to return energy from the oscillatory-inductor circuit to the intermediate part with constant current indicators;
a resonant capacitor that provides continuous current after the transistor is locked;
an induction device, which is focused on the transfer of heat from the surface to the bottom of the used kitchen utensils;
a transistor that converts direct current into variable indicators;
resistor to fix the transistor after shutdown;
a resistor to suppress high-frequency current indicators;
rectifier for voltage in the electrical network;
current controller, which prevents the possible occurrence of overload;
collector voltage controller.

In budget models there are only basic structural elements, which affects the functionality of such a device.

Self-production of a simple induction cooker involves strict adherence to all standards, which will make the operation of such a device completely safe. Significant complexity in the process of designing a slab arises at the stage of selection quality material to create the base of the hob.

Do-it-yourself induction cooker - diagram

Such a material must necessarily be distinguished by the ability to correctly conduct electromagnetic radiation, not conduct current and withstand high-temperature conditions.

Factory-made household cooking equipment, which includes all modern induction cookers, is made using quite expensive ceramics.

Exactly because of this reason independent production cooking induction cooker at home is associated with certain problems of choosing a worthy alternative to a ceramic surface.

Conclusion

Modern household induction hobs have, as a rule, a standard scheme, according to which the installed magnetic coils in the process of contact with the ferromagnetic bottom of the cookware carry out stable heating of the cooked food.

The control of such household equipment can be carried out by means of mechanical switches and touch buttons, which makes the operation of the induction cooker very convenient.

Source: https://microklimat.pro/otopitelnoe-oborudovanie/otopitelnye-pribory/cxema-indukcionnoj-plity.html

Do-it-yourself induction furnace - instructions!

Induction furnaces are used for smelting metals and are distinguished by the fact that they are heated by means of electric current. The excitation of the current occurs in the inductor, or rather in a non-variable field.

DIY induction oven

In such constructions, energy is converted several times (in this sequence):

into the electromagnetic
electrical;
thermal.

Such ovens allow the use of heat from maximum efficiency, which is not surprising, because they are the most advanced of all existing models powered by electricity.

Note! Induction designs are of two types - with or without a core. In the first case, the metal is placed in a tubular chute, which is located around the inductor. The core is located in the inductor itself. The second option is called the crucible, because in it the metal with the crucible is already inside the indicator. Of course, there can be no talk of any core in this case.

In today's article, we will talk about how to make an induction furnace with your own hands.

Pros and cons of induction designs

Among the many benefits are the following:

environmental cleanliness and safety;
increased homogeneity of the melt due to the active movement of the metal;
speed - the oven can be used almost immediately after switching on;
zone and focused orientation of energy;
high melting rate;
lack of waste from alloying substances;
the ability to adjust the temperature;
numerous technical possibilities.

But there are also disadvantages.

The slag is heated by the metal, as a result of which it has a low temperature.
If the slag is cold, then it is very difficult to remove phosphorus and sulfur from the metal.
Between the coil and the melting metal, the magnetic field dissipates, so a reduction in lining thickness will be required. This will soon lead to the fact that the lining itself will fail.

Industrial Application

Both design options are used in the smelting of iron, aluminium, steel, magnesium, copper and precious metals. The useful volume of such structures can range from several kilograms to several hundred tons.

Furnaces for industrial use are divided into several types.

Medium frequency designs are commonly used in mechanical engineering and metallurgy. With their help, steel is melted, and when using graphite crucibles, non-ferrous metals are also melted.
Industrial frequency designs are used in iron smelting.
Resistance structures are intended for melting aluminum, aluminum alloys, zinc.

Note! It was induction technology that formed the basis of more popular devices - microwave ovens.

domestic use

Scheme of the induction furnace

For obvious reasons, the induction melting furnace is rarely used in the home. But the technology described in the article is found in almost all modern houses and apartments. These are the microwaves mentioned above, and induction cookers, and electric ovens.

Consider, for example, plates. They heat the dishes due to inductive eddy currents, as a result of which the heating occurs almost instantly. It is characteristic that it is impossible to turn on the burner on which there are no dishes.

The efficiency of induction cookers reaches 90%. For comparison: for electric stoves it is about 55-65%, and for gas stoves - no more than 30-50%. But in fairness, it is worth noting that the operation of the described stoves requires special dishes.

Homemade induction oven

Scheme for the design of the generator

Not so long ago, domestic radio amateurs clearly demonstrated that you can make an induction furnace yourself. Today, there are a lot of different schemes and manufacturing technologies, but we have given only the most popular of them, which means the most effective and easy to implement.

Induction furnace from high frequency generator

Below is an electrical circuit for making a homemade device from a high-frequency (27.22 megahertz) generator.

In addition to the generator, the assembly will require four high-power light bulbs and a heavy lamp for the ready-to-work indicator.

Note! The main difference between the furnace, made according to this scheme, is the condenser handle - in this case, it is located outside.

In addition, the metal in the coil (inductor) will melt in the device of the smallest power.

There are a few things to keep in mind when making important points, affecting the speed of the board of the metal. This:

power;
frequency;
eddy losses;
heat transfer rate;
hysteresis loss.

The device will be powered by a standard 220 V network, but with a pre-installed rectifier. If the furnace is intended for heating a room, then it is recommended to use a nichrome spiral, and if for melting, then graphite brushes. Let's get acquainted with each of the structures in more detail.

Graphite brush design

The essence of the design is as follows: a pair of graphite brushes is installed, and powdered granite is poured between them, after which a step-down transformer is connected. It is characteristic that when smelting, one can not be afraid of electric shock, since there is no need to use 220 V.

Making an induction furnace

Assembly technology

Step 1. The base is assembled - a box of fireclay bricks measuring 10x10x18 cm, laid on a refractory tile.

Step 2. Boxing is finished with asbestos cardboard. After wetting with water, the material softens, which allows you to give it any shape. If desired, the structure can be wrapped with steel wire.

Note! The dimensions of the box may vary depending on the power of the transformer.

Step 3 The best option for graphite furnace - transformer from welding machine with a power of 0.63 kW. If the transformer is designed for 380 V, then it can be rewound, although many experienced electricians say that you can leave everything as it is.

Step 4. The transformer is wrapped with thin aluminum - so the structure will not get very hot during operation.

Step 5. Graphite brushes are installed, a clay substrate is installed on the bottom of the box - so the molten metal will not spread.

Graphite brush design

The main advantage of such a furnace is the high temperature, which is suitable even for melting platinum or palladium. But among the minuses is the rapid heating of the transformer, a small volume (no more than 10 g can be smelted at a time). For this reason, a different design will be required for melting large volumes.

Device with nichrome spiral

So, for the smelting of large volumes of metal, a furnace with nichrome wire. The principle of operation of the design is quite simple: an electric current is applied to a nichrome spiral, which heats up and melts the metal. There are a lot of different formulas on the Web for calculating the length of the wire, but they are all, in principle, the same.

Step 1. For the spiral, nichrome ø0.3 mm is used, about 11 m long.

Step 2. The wire must be wound. To do this, you need a straight copper tube ø5 mm - a spiral is wound on it.

Step 3. A small ceramic pipe ø1.6 cm and 15 cm long is used as a crucible. One end of the pipe is plugged with asbestos thread - so the molten metal will not flow out.

Step 4. After checking the performance, the spiral is laid around the pipe. At the same time, the same asbestos thread is placed between the turns - it will prevent a short circuit and limit the access of oxygen.

Step 5. The finished coil is placed in a cartridge from a high power lamp. Such cartridges are usually ceramic and have the required size.

Finished construction

The advantages of such a design:

high productivity (up to 30 g per run);
fast heating (about five minutes) and long cooling;
ease of use - it is convenient to pour metal into molds;
prompt replacement of the spiral in case of burnout.

But there are, of course, downsides:

nichrome burns out, especially if the spiral is poorly insulated;
insecurity - the device is connected to the mains 220 V.

Note! You can not add metal to the stove if the previous portion is already melted there. Otherwise, all the material will scatter around the room, moreover, it may injure the eyes.

As a conclusion

Induction cooker

As you can see, you can still make an induction furnace on your own. But to be frank, the described design (like everything available on the Internet) is not quite a furnace, but a Kukhtetsky laboratory inverter. It is simply impossible to assemble a full-fledged induction structure at home.

Source: https://svoimi-rykami.ru/stroitelstvo-doma/pechi_i_mangaly/indukcionnaya-pech-svoimi-rukami.html

How to make an induction boiler with your own hands

induction heating boilers appeared on sale recently and immediately competed with the usual electric boilers with heating elements.

With similar size and power consumption, induction heaters are able to warm up the system much faster, in addition, they can work in systems with poor quality of the coolant and require less maintenance.

Applying knowledge in electrical engineering and ingenuity, you can make an induction heating boiler with your own hands.

Operating principle

The basis of the action of induction boilers and other heating devices of this type is the ability of conductive materials to heat up under the action of eddy currents created as a result of electromagnetic induction.

The source of induction is a high-frequency alternating current passing through the primary winding of the heating device, made in the form of a coil. The heating element placed inside the coil plays the role of a secondary short-circuited winding. It converts electromagnetic energy into thermal energy.

Eddy currents also occur at an industrial frequency of 50 Hz, but the efficiency of the heater will be low, and the operation of the device will be accompanied by a strong hum and vibration. When the frequency is increased to 10 kHz and above, the noise disappears, the vibration becomes imperceptible, and the heating increases.

Device

An industrial induction boiler consists of a core, the role of which is played by a heat exchanger, around which a toroidal winding is wound, connected to a high-frequency converter. When current passes through the winding, an alternating electromagnetic field is created, which results in eddy currents passing through the core.

The winding is connected to a high-frequency converter, in which a signal from the control unit creates a current of the required frequency. Modern boilers have high level automation, which allows not only to create the optimal mode of heating the coolant, but also to turn off the device in case of an emergency.

Inside the core-heat exchanger is a coolant. Under the influence of eddy currents, it heats up to high temperatures.

Due to the difference between the temperature of the coolant at the inlet and outlet, the circulation of the coolant through the system from the boiler occurs continuously, even without connecting the pump.

Therefore, induction boilers can be used in systems with forced and natural circulation.

The coolant can be either water or antifreeze, antifreeze, oil. In this case, the quality of the liquid does not matter: the constant vibration of the system, which is imperceptible by a person, makes it impossible for scale and other impurities to settle on the walls of the heating circuit.

Outer shell- a metal case equipped with a system of thermal and electrical protection insulation.

Boiler shape it can be any, as well as the method of its installation: due to the absence of a tank inside the boiler, its dimensions are usually small, and its weight does not exceed 50 kg.

The induction boiler must not even be put into operation for a short time without filling the system with coolant! Overheating of the boiler and failure of its elements may occur!

Advantages:

High efficiency. Most manufacturers give figures of 95-98%;
Large selection of models of different power for single-phase voltage ~ 220 V or three-phase ~ 380 V;
Rapid heating of the heating system at startup;
Can work with any coolant;
The circuit through which the coolant passes inside the boiler is absolutely hermetic, which eliminates leaks and related malfunctions;
Long work without formation of a scum and deposits. It is this phenomenon that over time reduces the efficiency of boilers with heating elements and serves common cause their breakdown due to overheating of the heating elements;
The service life declared by manufacturers is from 25 to 30 years.

Not without heaters and disadvantages, the most significant of which is the high price.

This factor usually prompts a prudent owner to assemble a home-made induction boiler from improvised materials and appliances.

Despite the complexity of the processes occurring in boilers of this type, it is possible to create a design that does not lag behind an industrial boiler in terms of basic parameters, and make an induction boiler with your own hands.

Boiler powered by a welding inverter

The design of such a homemade boiler is quite simple. The most difficult block for independent implementation, which requires knowledge of the basics of electronics and electrical engineering, is a high-frequency converter. Its function is perfectly performed by a modern-type welding inverter capable of delivering an output signal with a frequency of 20-50 kHz.

In addition, for installation you will need:

copper wire in enamel insulation with a diameter of 1-1.5 mm;
insulated wire with terminals for connecting the winding to the inverter;
cuttings of stainless steel wire with a diameter of 3-5 mm, 5 cm long;
fine stainless steel mesh;
section water pipe from sewn polyethylene or polypropylene for hot water and heating systems with a diameter of 50 mm and a wall thickness of 8.4 mm, length - 1 m;
adapters from a 50 mm pipe to pipes used in an existing or planned heating system, a tee for connecting an emergency valve and two ball valves;
strips of textolite for fastening the winding;
epoxy adhesive for winding insulation;
the body of a homemade boiler, it can be made from a metal or plastic distribution cabinet, in which you can install an inverter and fix the heating element.

The sequence of assembly and installation of elements:

For a segment polypropylene pipe with a diameter of 50 mm, using epoxy glue, 4 strips of textolite 8-10 mm wide are attached, stepping back from the ends of the pipe by 70-100 mm. A winding will be wound on them. To fix the extreme turns of the winding in the textolite, grooves can be made.
50-100 turns of copper wire are wound in enamel insulation. The turns should be approximately 0.3-0.6 mm apart at an equal distance. The exact number of turns depends on the diameter of the wire used and its resistivity, as well as the output parameters of the inverter.
When installing a homemade boiler in a residential area, it is recommended to perform a toroidal winding to reduce the external electromagnetic field. The toroidal winding consists of the same number of oppositely directed turns, while the electromagnetic fluxes are mutually compensated and pass only along the inner loop.
A stainless steel mesh is inserted into the pipe from one end of it and tightly packed on the other side with pieces of stainless wire - it will heat up under the influence of eddy currents. It is recommended to use stainless steel in order to prevent corrosion destruction of the wire over time, but theoretically any conductive metal, including wire rod, will do. The other end of the pipe is also closed with a mesh.
Polypropylene adapters are soldered to both ends of the pipes to the diameter used in the heating system. Ball valves are installed on them to shut off the circulation and remove the heat exchanger for revision.
An emergency valve is installed on the side of the upper outlet adapter to relieve pressure.
The winding is coated with epoxy glue to ensure high-quality electrical insulation of the winding. The manufacture of glue is recommended to be carried out with a slight deviation from the instructions, adding 10-15% less hardener. This will make the insulation less brittle.
They are attached to the terminals of the winding wires in insulation using crimp terminals. The other end of the wire must be equipped with terminals for connection to the inverter. The diameter of the wires must be able to withstand the maximum output current of the inverter.
Install the heat exchanger in the cabinet, fixing it on brackets made of heat-resistant non-conductive material. Textolite can be used.
Connect the heater to the system and fill it with water.
An inverter is placed at the bottom of the cabinet. Connect the terminals to it and turn it on to the network. The boiler is started and the mode is set.

The cabinet body made of metal must be grounded!

From induction hob

An induction boiler can also be made based on induction hob. To do this, the heating element of the tile is disassembled and a copper wire is used for winding on a core made in the above way.

The tile control unit is used to power the resulting winding, setting the required power on the touch control panel.

However, this method has significant disadvantages:

For successful work such a homemade boiler, you need to calculate the parameters of the inductance of the newly assembled coil. They may not match those for which the tile electronics are designed, as a result of which the control unit may fail. For calculations, you need to have good knowledge in the field of electrical engineering and be able to understand the connection diagram;
Most hob models are equipped with automatic shutdown 2-3 hours after the start of the burner. This will lead to a regular shutdown of the boiler;
Induction type stoves usually have a power of no more than 2.5 kW, therefore they are only suitable for conversion to a low power boiler.

Errors in the device of an induction tile boiler are shown in the video:

An easier way to use an induction hob, excluding disassembly of the device and installation of a new circuit - install a sealed stainless steel tank on it right size with an inlet and outlet fitting and connecting it as a boiler to the heating system. Almost everyone can cope with such a connection scheme.

In the presence of necessary knowledge and the ability to understand circuits, you can follow the example of the author of the video and assemble a functional induction boiler from tiles, finalizing its circuit.

Dry type heater

The principle of operation of an induction boiler involves the use of water or other liquid not only as a heat carrier, but also to cool the core.

But the heating of the secondary winding, the role of which in this device is played by a pipe with water, will also occur if it consists only of metal.
The degree of heating in this case depends on the ratio of the strength of the electromagnetic field created by the winding and the mass of the core metal.

After making the calculations, you can create a dry induction heater with your own hands from metal pipes and copper winding, as shown in the video.

The use of an induction boiler is cheaper than a conventional electric boiler with heating elements, and homemade construction will significantly reduce installation costs. Similarly, you can assemble a water heater flow type for installation in the country, choosing a device of the required power.

Features of furnaces with induction

Advantages
Flaws

Basics of oven operation

The use of stoves in everyday life

Fireplaces
Guca ovens
thorma ovens

Types of ovens with induction system

There are two main types that induction furnaces are divided into.

In one of them, the heart channel is the base, the metal in such furnaces is placed around the inductor in an annular way.

The second species does not have such a channel. This type is called a crucible, and in these furnaces the metal is located inside the inductor itself. In the latter case, the use of a closed core is technically not possible.

Features of furnaces with induction

The clear advantages of induction ovens are some of the features listed below:

Advantages

Since the metal is evenly distributed, the resulting material has a good uniform mass during the process. This type of furnace works by moving energy through zones and also has a function of focusing energy. It is possible to widely use such parameters as operating frequency, capacity and method of lining, regulation of the metal melting temperature, which is also a positive component of the workflow. The technological potential of the furnaces creates a very high melting rate, the furnaces are environmentally friendly, safe for humans and always ready to work.

Flaws

A clear flaw in these ovens is their cleaning. Since only the heat released by the metal heats the slag, and such a temperature, as a rule, is not enough to ensure its full use. Due to the high temperature difference between the slag and the metal, the waste disposal process is very difficult. Another disadvantage is the gap, due to which the thickness of the lining must always be reduced. As a result of such actions, it, as a rule, becomes faulty after a while.

Induction furnaces in industry

In industry, such types of furnaces as channel and crucible induction furnaces are mainly involved. In crucible furnaces, many metals are melted in any quantities. The capacity for metal in such furnaces can place volumes from several hundred to several tons of metal. As for channel furnaces, non-ferrous metals are smelted in them. different kind, and quantities, as well as the ability to melt cast iron.
Induction furnaces in industry come in three frequencies: medium frequency furnace, industrial frequency furnace and resistance furnace.

The first type of equipment is usually used in various workshops, such as foundries in metal smelters and in engineering plants.

In addition to smelting non-ferrous metals, their capabilities include smelting steel. This is due to the fact that such furnaces are equipped with graphite crucibles, which will also allow you to melt and overheat cast iron.

As for resistance furnaces, they are used for superheating and remelting aluminum and zinc alloys, as well as many other metals.

Basics of oven operation

There is one interesting fact. The basis of the operation and functioning of ovens with an induction system was taken to design the now much-needed microwave ovens.
microwaves carry most the possibilities of induction furnaces, only with a lower impact force and produced heating temperature. To date, there are mini ovens, such as delonghi, which function as ovens and can cook food quickly and tasty. They have in their composition heating elements specific effects that not only, for a long time, simplify life modern people and make it more comfortable.

We make a stove with our own hands - this is possible today

Very often, fans of radio technologies and radio design are interested in this topic. Today it should be clear that creating such equipment with your own hands is quite realistic, and many have already done it. But in order to create such a furnace, you need to realize the action electrical circuit, in which the actions of this very furnace would be spelled out. Such circuits require the use of RF generators that are capable of producing oscillation waves. To create the desired circuit, you need to use the capabilities of four vacuum tubes, as well as one neon lamp, which signals that the system is ready for operation.
Due to the fact that the handle of the AC capacitor is not inside the oven, you can design a mini induction oven yourself according to the above diagram. A clear advantage of such furnaces is that even a small variable capacity shows itself very well in operation. The metal placed in its coil melts surprisingly quickly, for example, a piece of aluminum melts in about thirty seconds. You can verify the power of the device with a screwdriver, which in a few seconds reaches a red-hot state.
When you are designing this type of furnace, you need to be aware that the rate of melting in such furnaces depends on several factors, which are listed below:

Generator power;
Hysteresis losses;
Losses due to eddy currents.
Pulse frequency;
The period during which heat is transferred from the furnace to the outside.

When you use lamps, you must remember that they must distribute their power so that only 4 lamps are enough. You will get a network of approximately 220 V. if a rectifier is used.

The use of stoves in everyday life

The use of such stoves in everyday life is quite rare, although such technologies, of course, are found in heating systems practically everywhere. They are found in the form of microwaves, induction cookers, and also in the form of electric ovens. This is quite a wide application in the environment of new technologies.
For example, the use of eddy currents, which are used in the operation of induction cookers, makes it possible to cook many different dishes. Since they require very little time to warm up, and you will not be able to turn on the burner if there is nothing on it. But in order to use these rather productive and useful stoves, you need to have special utensils.

Types of heating devices

Such a type of furnace as induction, of course, should not be attributed to heating furnaces. But since they are used along with many other devices, we will do it.

Fireplaces

But thanks modern technologies, we can use latest discoveries in the use of these devices. Such heating elements as planika fireplaces not only heat the house, but also play an important decorative role in decorating the room. They are biologically clean for the environment, since their fuel uses a liquid, during the processing of which water and heat are formed. Also one of their advantages is that after their work there is no dust or ash left.

Guca ovens

Nowadays, guca ovens are very popular, the main difference of which is high quality and reliability in operation, as well as a very beautiful external design. If you do not have experience in developing such ovens, it is better to trust specialized factories for the manufacture of these products. Since not only the warmth and comfort of your premises will depend on this, but, above all, safety.

thorma ovens

Very famous in our time are thorma ovens. They are manufactured in a factory with many years of experience in producing reliable and proven products. This plant is considered the leader in terms of productivity in Europe. Furnaces manufactured at the factory, as a rule, are light in weight and can be installed not only on the foundation, but also on the walls. This is very useful if your room is small and you need to save space. They are also equipped with a special mode of long-term burning of fuel. Thanks to this mode, you can: leave the stove on for a long time and not be afraid for the safety of the room. Such burning lasts about 10 hours. The furnaces have convection chambers that completely burn the fuel in the furnace. This feature saves money and time.
So, the use of furnaces of this type is becoming popular, but still they are not able to replace their competitors. Although they are the most perfect among those known in our time electric ovens and allow full use of the generated heat. Creating such stoves manually is possible if you have some experience in such activities, since the safety of the premises will depend on the performance and safety of such stoves. If you do not have this experience, it is better to use the services of factories and various workshops that are ready to help you at any moment. We hope that this article helped you if you are still going to design this miracle of technology and you will use all the above tips. Good luck in your endeavors.

Operating principle

The melting unit of the induction furnace is used to heat a wide variety of metals and alloys. The classic design consists of the following elements:

Drain pump.
Water cooled inductor.
Frame in stainless steel or aluminium.
Contact area.
Hearth made of heat-resistant concrete.
Support with hydraulic cylinder and bearing unit.

The principle of operation is based on the creation of eddy induced Foucault currents. As a rule, when working household appliances such currents cause failures, but in this case they are used to heat the charge to the required temperature. Almost all electronics start to heat up during operation. This negative factor in the use of electricity is used to its full potential.

Device advantages

The induction melting furnace has been used relatively recently. Famous open-hearth furnaces, blast furnaces and other types of equipment are installed at production sites. Such a metal melting furnace has the following advantages:

It is the latter advantage that determines the spread of the induction furnace in jewelry, since even a small concentration of foreign matter can adversely affect the result.

Depending on the design features, floor and desktop induction furnaces are distinguished. Regardless of which option was chosen, there are several basic rules for installation:

The device may become very hot during operation. That is why there should not be any flammable or explosive substances nearby. In addition, technical fire safety near must be installed fire shield.

Only two types of furnaces are widely used: crucible and channel. They have similar advantages and disadvantages, the differences are only in the method of work used:

The crucible variety of induction furnaces is more popular. This is due to their high performance and ease of operation. In addition, a similar design, if necessary, can be made independently.

Homemade versions are quite common.. To create them you need:

Generator.
Crucible.
Inductor.

An experienced electrician, if necessary, can make an inductor with his own hands. This structural element is represented by a winding of copper wire. The crucible can be purchased at the store, but a lamp circuit, a do-it-yourself battery of their transistors or a welding inverter is used as a generator.

Using a welding inverter

A do-it-yourself induction furnace for melting metal can be created using a welding inverter as a generator. This variant is the most widely used since the efforts made concern only the manufacture of the inductor:

Thin-walled copper tube is used as the main material. The recommended diameter is 8-10 cm.
The tube is bent according to the desired pattern, which depends on the features of the body used.
Between the turns there should be a distance of no more than 8 mm.
The inductor is placed in a textolite or graphite case.

After the creation of the inductor and its placement in the housing, it remains only to install the purchased crucible in its place.

Such a circuit is rather complicated in execution, it involves the use of resistors, several diodes, transistors different capacity, film capacitor, copper wire with two different diameters and rings from chokes. Assembly recommendations are as follows:

The created circuit is placed in a textolite or graphite case, which are dielectrics. Scheme, involving the use of transistors, is quite difficult to implement. Therefore, it is necessary to undertake the manufacture of such a furnace only if there are certain work skills.

Furnace with lamps

Recently, lamp stoves have been created less and less, as they require care when handling. The applied circuit is simpler in comparison with the case of using transistors. Assembly can be carried out in several stages:

The lamps used must be protected from mechanical impact.

Equipment cooling

When creating an induction furnace with your own hands, the most problems arise with cooling. This is due to the following points:

During operation, not only the molten metal is heated, but also some elements of the equipment. That is why effective cooling is required for long-term operation.
The method based on the use of air flow is characterized by low efficiency. In addition, it is not recommended to install fans near the oven. This is due to the fact that metallic elements can affect the generated eddy currents.

As a rule, cooling is carried out with water supply. Creating a water cooling circuit at home is not only difficult, but also uneconomical. Industrial versions of the furnace have an already built-in circuit, to which it is enough to connect cold water.

Safety

When using an induction furnace, certain safety precautions must be observed. Key recommendations:

When installing the equipment, consideration should be given to how the charge will be loaded and the molten metal will be extracted. It is recommended to allocate a separate prepared room for the installation of an induction furnace.

Now furnaces with an induction system are widely used in the process of melting metals. The current produced in the field of the inductor contributes to the heating of the substance, and this feature of such devices is not only the main, but also the most important. Processing leads to the fact that the substance undergoes several transformations. The first stage of transformation is the electromagnetic stage, after it the electrical stage, and then the thermal stage. The temperature emitted by the stove is applied almost without a trace, so this solution is the best among all others. Many may be interested in the stove made. Next, we will talk about the possibilities of implementing such a solution.

Types of furnaces for melting metals

This type of equipment can be divided into main categories. At the first, the heart channel acts as a base, and the metal is placed in such furnaces in an annular way around the inductor. The second category has no such element. This type is called a crucible, and the metal is placed inside the inductor itself. In this case, it is technically impossible to use a closed core.

Basic principles

The melting furnace in this case works on the basis of the phenomenon of magnetic induction. And there are several components. The inductor is the most important component of this device. It is a coil, the conductors in which are not ordinary wires, but copper tubes. This requirement is set by the design of melting furnaces. The current that passes in the inductor generates a magnetic field that affects the crucible, inside of which the metal is located. In this case, the role of the secondary transformer winding is assigned to the material, that is, a current passes through it, heating it. This is how melting is carried out, even if an induction furnace is made by hand. How to build this type of furnace and increase its efficiency? This is an important question that has an answer. The use of increased frequency currents can significantly increase the degree of equipment efficiency. For this, it is appropriate to use special power supplies.

Features of induction furnaces

This type of equipment has certain characteristic features, which are both advantages and disadvantages.

Since the distribution of the metal must be uniform, the resulting material is characterized by a good homogeneous mass. This type of furnace works by transporting energy through zones, and the function of focusing energy is also provided. Parameters such as capacity, operating frequency and lining method are available for use, as well as regulation of the temperature at which the metal melts, which greatly facilitates the workflow. The existing technological potential of the furnace creates a high melting rate, the devices are environmentally friendly, completely safe for humans and ready to work at any time.

The most noticeable drawback of such equipment is the difficulty of cleaning it. Since the heating of the slag occurs solely due to the heat released by the metal, this temperature is not enough to ensure its full use. The high temperature difference between the metal and the slag makes it impossible to make the process of waste disposal as simple as possible. As another drawback, it is customary to highlight the gap, due to which it is always necessary to reduce the thickness of the lining. Due to such actions, after a while it may turn out to be faulty.

The use of induction furnaces on an industrial scale

In industry, crucible and channel induction furnaces are most common. In the first, any metals are smelted in arbitrary quantities. Tanks for metal in such variants are able to fit up to several tons of metal. Of course, do-it-yourself induction melting furnaces in this case cannot be done. Channel furnaces are designed for smelting non-ferrous metals of various types, as well as cast iron.

Fans of radio engineering and radio technologies are often interested in this topic. Now it becomes clear that creating induction furnaces with your own hands is quite realistic, and a lot of people managed to do it. However, to create such equipment, it is required to implement the action of an electrical circuit that would contain the prescribed actions of the furnace itself. Such solutions require the involvement of those capable of producing wave oscillations. A simple do-it-yourself induction furnace according to the scheme can be built using four electronic lamps in combination with one neon, signaling that the system is ready to go.

In this case, the AC capacitor handle is not placed inside the instrument. Thanks to this, a do-it-yourself induction furnace can be created. The device diagram describes in detail the location of each individual element. You can make sure that the device is powerful enough if you use a screwdriver, which should reach a hot state in just a few seconds.

Peculiarities

If you are creating an induction furnace with your own hands, the principle of operation and assembly of which is studied and carried out according to the appropriate scheme, you should know that one or more of the factors listed below can affect the melting rate in this case:

Pulse frequency;

Hysteresis losses;

Generator power;

The period of heat release to the outside;

Losses associated with the occurrence of eddy currents.

If you are going to do an induction oven with your own hands, then when using lamps, you need to remember that their power should be distributed so that four pieces are enough. When using a rectifier, you get a network of approximately 220 V.

Domestic use of stoves

In everyday life, such devices are used quite rarely, although similar technologies can be found in heating systems. They can be seen in the form of microwave ovens and in the environment of new technologies, this development has found wide application. For example, the use of eddy currents in induction cookers allows you to cook a huge variety of dishes. Since they take very little time to warm up, the burner cannot be turned on if there is nothing on it. However, special cookware is required to use such special and useful stoves.

Assembly process

Do-it-yourself induction consists of an inductor, which is a solenoid made from a water-cooled copper tube and a crucible, which can be made of ceramic materials, and sometimes steel, graphite and others. In such a device, it is possible to smelt iron, steel, precious metals, aluminum, copper, magnesium. Do-it-yourself induction furnaces are made with a crucible capacity from a couple of kilograms to several tons. They can be vacuum, gas-filled, open and compressor. Furnaces are fed with currents of high, medium and low frequency.

So, if you are interested in a do-it-yourself induction furnace, the scheme involves the use of such basic components: a melting bath and an induction unit, which includes a hearth stone, an inductor and a magnetic core. The channel furnace differs from the crucible one in that the electromagnetic energy is converted into thermal energy in the heat release channel, in which there must always be an electrically conductive body. To make the initial start-up of a channel furnace, molten metal is poured into it or a template is inserted from a material that can be cracked down in the furnace. When the melt is completed, the metal is not completely drained, but a "swamp" is left, designed to fill the heat release channel for future start-ups. If you are going to do-it-yourself induction furnace, then to facilitate the replacement of the hearth stone for equipment, it is made detachable.

Furnace components

So, if you are interested in a do-it-yourself induction mini-oven, then it is important to know that its main element is a heating coil. When homemade version it is enough to use an inductor made of a bare copper tube, the diameter of which is 10 mm. For the inductor, an inner diameter of 80-150 mm is used, and the number of turns is 8-10. It is important that the turns do not touch, and the distance between them is 5-7 mm. Parts of the inductor must not come into contact with its screen, the minimum clearance must be 50 mm.

If you are going to do-it-yourself induction furnace, then you should know that water or antifreeze is cooling the inductors on an industrial scale. In the case of low power and short operation of the created device, it is possible to do without cooling. But during operation, the inductor becomes very hot, and scale on copper can not only drastically reduce the efficiency of the device, but also lead to a complete loss of its performance. It is impossible to make an inductor with cooling on your own, so it will need to be replaced regularly. Forced air cooling must not be used, since the fan housing located close to the coil will “attract” EMF to itself, which will lead to overheating and a decrease in the efficiency of the furnace.

Generator

When a do-it-yourself induction furnace is assembled, the scheme involves the use of such important element like an alternator. You should not try to make a stove if you do not know the basics of radio electronics at least at the level of an average radio amateur. The choice of the oscillator circuit must be such that it does not give a hard current spectrum.

Use of induction furnaces

This type of equipment has become widespread in areas such as foundries, where the metal has already been cleaned and needs to be given a specific shape. You can also get some alloys. In jewelry production, they also became widespread. The simple principle of operation and the possibility of assembling an induction furnace with your own hands make it possible to increase the profitability of its use. For this area, devices with a crucible capacity of up to 5 kilograms can be used. For small productions, this option will be optimal.

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Mini induction melting furnace. Induction furnaces: principles of operation, drawings, how to do it yourself. DIY induction furnaces