Do-it-yourself induction melting furnaces. How to choose an induction furnace

A do-it-yourself induction furnace is an excellent solution for heating various rooms.

In addition to heating induction oven can perform the following functions:

metal melting;
cleaning of precious metals;
heating metal products, after which they go through a hardening procedure or through other processes.

However, the functions described above provide industrial plants , and if you need to carry out heating at home, then a stove for the kitchen is usually installed, and you can buy it ready-made or make it yourself. Homemade induction oven it is quite simple to create, and you do not need to spend a lot of time on this process. However, it is important to know not only the rules for the formation of this design, but also its other features, so that, if necessary, you can repair or replace any of the main parts on your own.

The principle of operation of the equipment

It is important to know the features of the operation of this type of furnace in order to understand its operation and parameters well. The equipment works due to the fact that with the help of special eddy currents material is heated. Such currents are obtained due to special inductor, which is an inductor. It has how many turns of wire, which has a fairly significant thickness.

The inductor can heat up due to welding inverter or other equipment. The principle of operation of the induction furnace assumes that the inductor is powered from the mains alternating current, and a high frequency generator can also be used for this. The current flowing through the inductor generates variable field penetrating space. If there are any materials in it, then currents are induced on them, ensuring their effective heating.

If a furnace is used to create, then usually the material is water, which is heating up. If the equipment is intended for industrial purposes, then metal can be used as a material, which begins to melt under the influence of current. So the working principle induction cooker It is considered simple and understandable, so creating it on your own is quite simple.

The device of induction furnaces can be different, since two completely different types can be distinguished:

equipment equipped with a magnetic circuit;
furnaces without a magnetic circuit.

In the first case, the inductor is inside special metal, which begins to melt under the influence of currents. In the second, the inductor is located outside. The scheme of each option has its own specific differences.

Varieties and characteristics of various induction furnaces

There are several types of induction furnaces, the principle of operation of which has certain differences. Some are intended only for industrial work, while others can be used in the home, so they are often intended for the kitchen, where they provide quality heating. Most often, the latter options are formed from a welding inverter, have simple design, due to which they maintenance and repair are simple jobs.

The main types of induction furnaces include:

Vacuum induction furnace. In it, melting is carried out in a vacuum, which allows you to remove harmful and dangerous impurities from various mixtures. The result is products that completely safe for use, are of high quality. It should be noted that their repair is considered a difficult job, and the creation process itself, as a rule, cannot be carried out on its own without specialized equipment and unusual conditions.
Channel construction. It is manufactured using conventional welding transformer which operates at a frequency of 50 Hz. Here, the secondary winding of this device is replaced by an annular crucible. A video of the creation of such a furnace can be found on the Internet, and its scheme is not considered complicated. Well-designed equipment can be used to melt a large amount of non-ferrous metals, and energy consumption is considered small. Repair is considered specific and complex.
crucible furnace. The scheme of this design involves the installation of an inductor and a generator, which are the most basic parts of the equipment. To form an inductor, a standard copper tube. However, the required number of turns must be observed, which should not be more than 8, but also less than 10. The circuit of the inductor itself may be different, it may have figure eight or other configuration. It should be noted that the repair of this equipment is considered a fairly simple job.
Induction oven for space heating. As a rule, it is intended for the kitchen, created on the basis of a welding inverter. This setting is usually used in combination with hot water boiler, which allows you to provide heating for each room in the building, in addition, it will be possible to supply hot water to the structure. The principle of operation is that the inductor is powered by a welding inverter. It is believed that the efficiency of this equipment is low, but often it is the only one possible to create heating in the house.

Read also: Wood burning stove with high efficiency

Furnace Formation Process

You can make an inverter-based induction oven for the kitchen or other room in the house with your own efforts. To do this, it is recommended not only to study the theoretical part of this process, but also to watch the training video.

To form electromagnetic field, which will be available outside the inductor, it is necessary to use a special coil in which there will be a sufficiently large number of turns. Additionally, you will need to bend the pipe, and this work has certain difficulties, so a more rational solution in this case would be the location straight pipe directly inside the coil, as a result of which it will work as a core.

Typically used metal pipe, however, it is considered a weak coolant, so a polymer pipe can be used instead, inside which there will be small pieces of metal wire. For a current generator, the use of a standard inverter is considered optimal. Its maintenance and repair are considered simple and understandable works, so it will be possible to provide long service life of the equipment.

Thus, to create a structure, you will need:

polymer pipe;
steel wire;
copper wire;
wire mesh;
the presence of the inverter itself.

Steel rod cut into small pieces. One end of the polymer pipe is closed with a mesh, and metal pieces of wire are loaded into the other. The second end is also closed with a mesh. On top of the pipe is created induction winding, what is it used for copper wire. The ends of this winding are well insulated and brought to the output of the inverter. As soon as the device is turned on, an electromagnetic field is created from the coil, which ensures the appearance of eddy currents in the core. This will cause it to heat up, so water flowing through the pipe will begin to heat up. Thus, an ideal design for a kitchen or other room is obtained, and its maintenance and repair are considered simple.

Best to check before work instructional video so as not to make mistakes. After creating the equipment, you can install it in the right room. It can be intended not only for the furnace, but even for the kitchen. It is important to choose a room in which it will be easy to care for the stove and carry out its repair.

The induction melting furnace has been used to melt metals and alloys for the past few decades. The device is widely used in the metallurgical and engineering fields, as well as in jewelry. If desired, a simple version of this equipment can be made by hand. Consider the principle of operation and features of the use of an induction furnace in more detail.

Principle of induction heating

In order for the metal to pass from one state of aggregation to another, it is required to heat it to a sufficient high temperature. Moreover, each metal and alloy has its own melting point, which depends on chemical composition and other moments. The induction melting furnace conducts heating of the material from the inside by creating eddy currents that pass through the crystal lattice. The process under consideration is associated with the phenomenon of resonance, which causes an increase in the strength of eddy currents.

The principle of operation of the device has the following features:

The space that is formed inside the coil serves to accommodate the workpiece. Use this heating method in industrial environment is possible only if a large device is created in which it will be possible to place a charge of various sizes.
The installed coil can have a different shape, for example, a figure-eight, but the most common is the spiral. It should be borne in mind that the shape of the coil is selected depending on the characteristics of the workpiece subjected to heating.

In order to create an alternating magnetic field, the device is connected to a household power supply network. High-frequency generators are used to improve the quality of the obtained alloy with high fluidity.

The device and application of the induction furnace

If desired, you can create an induction furnace for melting metal from improvised materials. The classic design has three blocks:

A generator that creates a high frequency alternating type current. It is he who creates an electric current, which is converted into a magnetic field passing through the material and accelerating the movement of particles. Due to this, the transition of the metal or alloys from the solid state to the liquid occurs.
The inductor is responsible for creating a magnetic field, which heats the metal.
The crucible is designed to melt the material. It is placed in an inductor, and the winding is connected to current sources.

The process of converting electric current into a magnetic field is used today in a wide variety of industries.

The main advantages of the inductor include the following points:

A modern device is capable of directing a magnetic field, thereby increasing efficiency. In other words, the charge is heated, not the device.
Due to the uniform distribution of the magnetic field, the workpiece is heated evenly. In this case, a small amount of time is spent from the moment the device is turned on to the melting of the charge.
The uniformity of the resulting alloy, as well as its high quality.
When heating and melting the metal, no fumes are formed.
The installation itself is safe to use, does not cause the formation of toxic substances.

There is simply a huge number of different versions of home-made induction furnaces, each with its own specific features.

Types of induction furnaces

Considering the classification of devices, we note that the heating of the workpieces can take place both inside and outside the coil. That is why there are two types of induction furnaces:

Channel. This kind of device has small channels that are located around the inductor. To generate an alternating magnetic field, a core is located inside.
Crucible. This design is characterized by the presence of a special container, which is called a crucible. It is made of refractory metal with a high melting point.

It is important that channel induction furnaces have large overall dimensions and are intended for industrial metal melting. Due to the continuous melting process, a large volume of molten metal can be obtained. Channel induction furnaces are used for melting aluminum and cast iron, as well as other non-ferrous alloys.
Crucible induction furnaces are characterized by relatively small dimensions. In most cases, this kind of device is used in jewelry, as well as when melting metal at home.
By creating a furnace with your own hands, you can adjust the power, for which the number of turns changes. It should be borne in mind that with an increase in the power of the device, a more capacious battery is required, as the power consumption indicator increases. In order to reduce the temperature of the main structural elements, a fan is installed. At long-term operation ovens, its main elements can heat up significantly, which should be taken into account.
Induction furnaces with lamps are also widely used. A similar design can be made independently. The assembly process has the following features:
A copper tube is used to create an inductor, for which it is bent in a spiral. The ends must also be large, which is required to connect the device to a current source.
The inductor should be placed in the housing. It is made of heat-resistant material that can reflect heat.
Lamp cascades are connected according to the scheme with capacitors and chokes.
A neon indicator lamp is connected. It is included in the circuit to indicate that the device is ready for operation.
A tuning capacitor of variable capacitance is connected to the system.

An important point is how the system can be cooled. During operation of almost all induction furnaces, the main structural elements can heat up to high temperatures. Industrial equipment has a forced cooling system that runs on water or antifreeze. In order to create a water cooling design with your own hands, quite a lot of money is required.
At home, an air cooling system is installed. For this, fans are installed. They should be positioned so as to provide a continuous flow of cold air to the main elements of the furnace structure.

The very principle of operation of an induction furnace is that the heat for melting is obtained from electricity, which is generated by an alternating magnetic field. In such furnaces, energy is converted from electromagnetic, then to electrical and, ultimately, to heat. How is an induction furnace made by hand?

Such furnaces are divided into two types:

Crucible. In such furnaces, the inductor and core are inside the metal. This type of furnace is used in industrial foundries, for melting copper, aluminum, cast iron, steel, as well as in jewelry factories for melting precious metals.
Channel. In this type of furnace, the inductor and core are located around the metal.

Compared to boilers or other stoves, induction stoves have several advantages:

warm up instantly.
focus energy in a given range;
environmentally friendly device and relative safety;
there is no fumes;
huge possibilities for adjusting temperature and capacity;
homogeneity of the metal that is being melted.

Induction furnaces are also used for heating. This is a convenient and at the same time silent heating method.

Does not require a special room for the boiler. Scale does not accumulate on the heating element, and any liquid can be used for circulation through the heating system, be it oil, water, and others. Also, the oven is durable, as it wears out minimally. As mentioned earlier, it is very environmentally friendly, because there are no harmful emissions into the air, and it also meets all fire safety requirements.

Collection of information

For a person who understands how to read and understand an electrical circuit, it will not be difficult to figure out how to make such an induction furnace. On the Internet, you will see dozens or even hundreds of options for making various induction furnaces using household junk, for example, from an old microwave oven or a welding inverter.

Be sure to remember that electric current is a dangerous thing. And for the manufacture of an induction furnace, you need to have an idea of \u200b\u200bwhat heating using induction is. It is advisable that you have a person with you who understands at least the basics of electrical engineering well or has experience working with electrical equipment.

Principle of operation

The basis of the operation of such a stove is the extraction of heat from an electric current, which produces an alternating magnetic field using an inductor. It turns out that we get heat first from electromagnetic energy, and then from electrical energy. The closed nature of the currents that flow through the turns of the inductor (inductor) generates heat and heats the metal from the inside.

Such a stove can work, have a simplified version and operate from a 220V home network. But this requires a rectifier, that is, an adapter.

Furnace device

The design of an induction device is similar to a transformer. In it, the primary winding is powered by alternating current, and the secondary serves as a heated body.

The simplest inductor is an insulated conductor (having the form of a spiral or core), which is located on the surface metal pipe or inside it.

Here are some knots that work by induction:

inductor;
compartment for melting furnace;
heating element for heating furnace;
generator;
frame.

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.

A closed conductor in induction cookers is metal utensils, which are 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 in a 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 stove lies in the selection of material for the base of the hob, which must meet the following requirements:

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

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

Manufacturing instructions

Blueprints

Figure 1. Electrical diagram of the induction heater

Figure 2. Device.

Figure 3. Scheme of a simple induction heater

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

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.
Asa 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 the flow heating of the liquid with a small circulation of water, to values \u200b\u200ballowing the use of this design in supplying warm water to a 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 there is an inverter welding machine direct current, then it is possible to make a voltage converter of the required power 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.

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

For melting metal on a small scale, some kind of device is sometimes necessary. This is especially acute in the workshop or in small production. The most effective at the moment is a furnace for melting metal with electric heater, namely induction. Due to the peculiarity of its structure, it can be effectively used in blacksmithing and become an indispensable tool in the forge.

Induction furnace device

The oven consists of 3 elements:

1. Electronic-electrical part.
2. Inductor and crucible.
3. inductor cooling system.

In order to assemble an operating furnace for melting metal, it is enough to assemble a working electrical circuit and an inductor cooling system. The easiest option for melting metal is shown in the video below. Melting is carried out in the counter electromagnetic field of the inductor, which interacts with the induced electro-eddy currents in the metal, which keeps a piece of aluminum in the space of the inductor.

In order to effectively melt the metal, currents of large magnitude and high frequency of the order of 400-600 Hz are required. The voltage from an ordinary 220V household outlet has sufficient data to melt metals. It is only necessary to turn 50 Hz into 400-600 Hz.
Any scheme for creating a Tesla coil is suitable for this.

Tins and other scrap - for recycling! How to make a do-it-yourself aluminum melting furnace

I liked the following 2 schemes on the lamp GU 80, GU 81 (M). And powering the lamp with an ILO transformer from a microwave.

These circuits are designed for a Tesla coil, but the induction furnace from them turns out to be excellent, it is enough to place instead of the secondary coil L2 in inner space primary winding L1 piece of iron.

The primary coil L1 or inductor consists of a copper tube rolled into 5-6 turns, at the ends of which a thread is cut to connect the cooling system. For levitational melting, the last turn should be done in the opposite direction.
Capacitor C2 on the first circuit and identical to it on the second sets the frequency of the generator. At a value of 1000 pF, the frequency is about 400 kHz. This capacitor must be high-frequency ceramic and designed for high voltage of the order of 10 kV (KVI-2, KVI-3, K15U-1), other types are not suitable! Better to put K15U. You can connect capacitors in parallel. It is also worth considering the power for which the capacitors are designed (this is written on the case), take it with a margin. the other two capacitors KVI-3 and KVI-2 heat up during prolonged operation. All other capacitors are also taken from the KVI-2, KVI-3, K15U-1 series, only the capacitance changes in the characteristics of the capacitors.
Here's a schematic of what it should look like. Framed 3 blocks.

The cooling system is made of a pump with a flow of 60 l / min, a radiator from any VAZ car, and I put a regular home cooling fan in front of the radiator.

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Masters of their craft: we make a melting furnace

A smelting furnace is a large or portable facility in which some non-ferrous metal can be melted. The induction melting furnace is widely known. In industrial conditions, for melting metal in large quantities, induction melting furnaces of considerable size are installed in special rooms. They melt metal, from which many parts for motorcycles, cars, tractors are cast. To melt up to 5 kg of aluminum. you can build your own induction melting furnaces, solid fuel, gas installations. They all work great. How and from what can you make a home melter?

We build our own furnace for melting

The installation for melting metal (Fig. 1) is assembled from bricks. It must be fireproof. Chamotte clay is used as a binder. To burn the device with coal, forced air is needed. For it, in the lower half of the unit, it is necessary to leave a special channel for air access. A grate is placed under this channel. This is a special cast iron grate on which coal or coke is laid out. The grate can be used from an old stove or purchased on the market, in a hardware store. For strength, some scald the finished structure with a metal belt. Brick can be placed on edge.

A melting furnace cannot do without a crucible. Instead, you can use a cast-iron cauldron. It can be found on the farm. Well, if it turns out to be enameled. The crucible is placed closer to the burning coke. It remains to put a fan as a forced blower, light the coke and start melting. Do-it-yourself oven is ready. It can be used for melting cast iron, copper, bronze, aluminum.

Construction of a tabletop oven

From simple materials it is possible to build gas or electrical devices that fit perfectly on a table or workbench. For work you will need:

Asbestos has been banned in recent years home use, so it can be replaced with tiles made of tiles or cement. Dimensions depend on the desire of the owner. Power plays a big role here. electrical network and the output voltage of the transformer. It is enough to apply a voltage of 25 V to the electrodes. For an industrial transformer used in welding, this voltage is usually 50-60 V. In this case, the distance between the electrodes must be increased. Much is done by experience. As a result, melting 60-80 g of metal is a good result.

Electrodes are best made from brushes from a fairly powerful electric motor. They have a very handy power cord. You can carve them yourself. There should be no big problems with finding material. V homemade product you need to drill holes with a diameter of 5-6 mm on the side, insert a copper stranded wire with a thickness of about 5 mm into them, carefully hammer in a nail to secure the wire. It remains to make a notch with a file, it will help to improve contact with graphite in powder form. Inside the furnace is laid out with mica. This is an excellent thermal insulator. Outside, the walls of the furnace are reinforced with tiles.

To power the furnace, you can take a transformer that lowers the mains voltage to 52 V. The mains winding is wound with 620 turns of wire Ø1 mm. The lowering winding is wound with a 4.2x2.8 mm wire with fiberglass insulation. Number of turns #8212; 70. The furnace is connected to the transformer with wires with a cross section of 7-8 mm² in good insulation. The finished installation must be turned on for a while so that all organic inclusions burn out. The stove is assembled by hand.

using a scoop or spatula, pour graphite and make a hole in it;
a material blank is laid in the hole;
precious metals must be placed in a glass ampoule;
tin and aluminum are placed in a separate iron cup;
for alloys, refractory metal is melted first, then low-melting metal.

It is impossible to melt magnesium, zinc, cadmium, silver contacts in such furnaces.

When melted, cadmium burns out with the formation of poisonous yellow smoke.

When working with the installation, you must observe safety precautions:

Do not allow short circuits in the wires.
The mains switch must be located near the operator.
Do not leave the device unattended during operation.
Nearby there is always a container in which water is poured, in which the workpieces are cooled.
For melting cast iron and other metals, goggles and gloves must be used.

If desired, gas installations can be made. They are well suited for melting small batches of non-ferrous metal. Induction furnaces for melting are capable of melting any metals. They can be used as conventional installations for working with non-ferrous and precious metals, as melting holding furnaces in production. They are suitable for various needs: for heating metals, for the manufacture of alloys of several metals, for the smelting of cast iron.

You can melt a small piece of iron in a self-assembled induction furnace. This is the most efficient device that runs on a 220V home outlet. The oven is useful in the garage or workshop, where it can be placed simply on the desktop. It makes no sense to buy it, since a do-it-yourself induction furnace is assembled in a couple of hours if a person can read electrical circuits. It is undesirable to do without a diagram, because it gives a complete picture of the device and allows you to avoid connection errors.

Scheme of the induction furnace

Parameters of the induction furnace

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How to properly assemble an induction furnace?

Helping a repairman

We offer your review for self repair electrical wiring diagrams!

Plates of Russian and imported production are presented, which do not change for years.
Click on the picture to enlarge the view.

The main elements and units of the stove: heating element E1 (in the first burner), E2 (in the second burner), E3-E5 (in the oven), a switching unit consisting of switches S1-S4, thermal relay F type T-300, indicators HL1 and HL (gas-discharge to indicate the operation of the heating element), HL3 (incandescent type to illuminate the oven). The power of each heating element is about 1 kW

A 4-position switch S1 is used to adjust the power and degree of heating of the heating element of the oven. When its handle is set to the first position, contacts P1-2 and P2-3 will close. At the same time, the following will be connected to the network using a plug: TEN E3 in series with parallel connected TEN E2 and E3. The current will pass along the path: the lower contact of the XP, F, P1-2, E4 and E5, E3, P2-3, upper HR plug contact. Since the E3 heater is connected to the E4 and E5 heaters in series, the 38 circuit resistance will be maximum, and the power and degree of heating will be minimal. In addition, the neon indicator HL1 will glow due to the passage of current through the circuit: the lower contact of the XP plug, F, P1-2, E4 and E5, R1, HL1, the upper contact XP.

Connecting nodes Dream 8:

In the second position, contacts P1-1, P2-3 are switched on. In this case, the current will flow through the circuit: the lower contact of the plug XP, F, P1-1, E3, P2-3, the upper contact XP. In this situation, only one heating element E3 will work and the power will be greater due to a decrease in the total resistance at a constant mains voltage of 220V.

In the third position of the switch S1, the contacts P1-1, P2-2 will close, which will lead to the connection to the network of only parallel connected heating elements E4 and E5. Switch S4 is used to turn on the oven light HL3.

5.Elektra 1002

H1, H2 - tubular burners, H3 - cast iron burner 200mm, H4 - cast iron burner 145mm, P1, P2-stepless power controls, P3, P4-seven-position power switches, PSH - three-stage oven switch, P5-blocking switch, L1 .... L4 - signal lamps for turning on the burners, L5 - signal lamp for turning on the heaters of the oven or grill, L6 - signal lamp for reaching the set temperature in the oven, H5, H6 - heaters for the oven, H7 - grill, T - thermostat, B - key switch, L7 - oven lighting lamp, M - motor reducer.

6. BURNER SWITCHES Combustion, Hansa, Elektra, Lysva:

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Table of contents:

Principle of operation
Parameters of the induction furnace
Features of the operation of the inductor

You can melt a small piece of iron in a self-assembled induction furnace.

How to make a crucible or melting furnace with your own hands

This is the most efficient device that runs on a 220V home outlet. The oven is useful in the garage or workshop, where it can be placed simply on the desktop. It makes no sense to buy it, since a do-it-yourself induction furnace is assembled in a couple of hours if a person can read electrical circuits. It is undesirable to do without a diagram, because it gives a complete picture of the device and allows you to avoid connection errors.

The principle of operation of the induction furnace

A home-made induction furnace for melting a small amount of metal does not require large dimensions and such a complex device as industrial units. Its work is based on the generation of current by an alternating magnetic field. The metal is melted in a special blank called a crucible and placed in an inductor. It is a spiral with a small number of turns of a conductor, such as a copper tube. If the device is used for a short time, the conductor will not overheat. In such cases, it is sufficient to use copper wire.

A special generator launches powerful currents into this spiral (inductor), and an electromagnetic field is created around it. This field in the crucible and in the metal placed in it creates eddy currents. It is they who heat the crucible and melt the metal due to the fact that it absorbs them. It should be noted that the processes occur very quickly if a non-metal crucible is used, for example, fireclay, graphite, quartzite. A home-made melting furnace provides for a removable crucible design, that is, metal is placed in it, and after heating or melting, it is pulled out of the inductor.

Scheme of the induction furnace

The high frequency generator is assembled from 4 electron tubes (tetrodes), which are connected in parallel. The heating rate of the inductor is controlled by a variable capacitor. Its handle is brought out and allows you to adjust the capacitance of the capacitor. The maximum value will provide heating of a piece of metal in the coil in just a few seconds to a red state.

Parameters of the induction furnace

The effective operation of this device depends on the following parameters:

generator power and frequency,
the amount of eddy current losses,
the rate of heat loss and the amount of these losses to the surrounding air.

How to choose the components of the circuit in order to obtain sufficient conditions for melting in the workshop? The generator frequency is pre-set: it should be 27.12 MHz if the device is assembled by hand for use in a home workshop. The coil is made of a thin copper tube or wire, PEV 0.8. It is enough to make no more than 10 turns.

Electronic lamps should be used with high power, for example, brand 6p3s. The scheme also provides for the installation of an additional neon lamp. It will serve as an indicator of device readiness. The circuit also provides for the use of ceramic capacitors (from 1500V) and chokes. Connection to a home outlet is carried out through a rectifier.

Externally, a home-made induction furnace looks like this: a generator with all the details of the circuit is attached to a small stand with legs. An inductor (spiral) is connected to it. It should be noted that this assembly option for a home-made melting device is applicable for working with a small amount of metal. The inductor in the form of a spiral is the easiest to make, therefore, for a home-made device, it is used in this form.

Features of the operation of the inductor

However, there are many different modifications of the inductor. For example, it can be made in the shape of a figure eight, trefoil, or any other shape. It should be convenient for placing material for heat treatment. For example, a flat surface is easiest to heat with serpentine coils.

In addition, it tends to burn through, and in order to extend the life of the inductor, it can be insulated with heat-resistant material. Use, for example, filling with a refractory mixture. It should be noted that this device is not limited to copper wire material. You can also use steel wire or michrome. When working with an induction furnace, its thermal hazard must be taken into account. If accidentally touched, the skin gets a severe burn.

Homemade melting crucible electric furnace.

So, a furnace for melting metal. Here I did not invent anything much, but simply tried to make a device, if possible from ready-made components and, if possible, without giving any slack in the manufacturing process.
At the furnace, the upper part is called the melter, the lower part is the control unit.
Don't let the white box on the right scare you - this is, in general, an ordinary transformer.
The main parameters of the furnace:
– furnace power - 1000 W
– crucible volume - 62 cm3
– maximum temperature - 1200 grC

smelter

Since my task was not to waste time on experiments with corundum-phosphate binders, but to save time by using ready-made components, I used a ready-made heater from YASAM, as well as a ceramic muffle working with it.

Heater: Fechral, wire diameter 1.5 mm, rods 3 mm in diameter are welded to the terminals. Resistance 5 ohm. The presence of a muffle is mandatory, since the wires inside the heater are bare. Heater size Ф60/50х124 mm. Muffle dimensions Ф54.5/34х130 mm. In the bottom of the muffle we make a hole for the elevator rod.
The body of the melter is made of standard stainless steel. 220/200 pipe machined to an acceptable wall thickness. The height is also taken for a reason. Since we will have a fireclay brick as a lining, the height is taken taking into account three brick thicknesses. It's time to post the assembly drawing. In order not to clutter up the page, I will not publish here, but I will give links: Part1, Part2.
The first drawing does not show the lightweight fireclay washer on which the crucible rests, the height of the washer depends on the crucible used. There is a hole for the rod in the center of the washer. The rod is pointed and in the lower position does not reach the crucible.
As I already wrote, the lining of the furnace is made of fireclay lightweight bricks ШЛ 0.4 or ШЛ 0.6 of size No. 5. Its dimensions are 230x115x65 mm. Brick is easily processed with saws and sandpaper. Saws, however, will not last long 🙂 Processing fireclay bricks. On the right is the original brick 🙂
Rectilinear cuts - a hacksaw for wood, for curved cuts - homemade saw from hacksaw blade with large teeth, with a reduced (grinded) width of the blade.

In the manufacture of lining, simple rules should be observed:
- do not use any mortar to hold the parts together. Everything is dry. It still breaks
— parts of the lining should not abut anywhere. There must be slack, gaps
- large parts of the lining, if you make it from another material, it is better to divide it into small parts. It will still split. Therefore, you better do it.

For the thermocouple in the third layer we make a hole, and in the second and first layers we make a gap between the heater and the lining. The gap is such that the thermocouple is pushed in tightly, as close as possible to the heater. You can use a purchased thermocouple in the same place in YASAM, but I use homemade ones. It's not that I feel sorry for the money (although they are quite expensive there), I just basically leave a bare junction for better thermal contact. Although there is a risk of burning the input circuits of the regulator.

Control block

In the control unit, the lower and upper covers are equipped with grilles for cooling the heater leads. All the same, the diameter of the pins is 3 mm. In addition, heat radiation through the bottom of the melter is also present. The regulator does not need to be cooled - 10 watts in total. At the same time, cool the cold ends of the thermocouple. Control unit with temperature controller Termodat-10K2. Top right is the on/off switch. At the top left is the crucible lift lever with the lift rod (stainless steel electrode Ф3mm).

Why I chose Termodat as a regulator. I dealt with Aries, but after one winter in an unheated room, his firmware crashed. The thermodat has withstood several winters and has retained not only the firmware, but also the settings.

Crucible furnace: design options, do-it-yourself manufacturing

In addition, the case is metal, indestructible. (We should at least take a bubble from Permians, for advertising 🙂
In addition, they can also take a power element - the Triac Control Unit BUS1-V01. This block is designed to work with Thermodata.
The instruction for Termodat-10K2 is here.

Diagram of an electric oven. The thick line shows high-current circuits. They use a wire of at least 6 mm2.

I'll talk about the transformer later. Now about the control unit. It is turned on by the T1 toggle switch, protected by a 0.25 A fuse. In addition, a line filter is provided to power the regulator, which is located in the transformer housing. A triac TS142-80 (1420 volts, 80 amperes, ordered in CHIP and DIP) is used as a power element. I put the triac on a radiator, but as practice has shown, it almost does not heat up. Do not forget to isolate the triac from the case. Or mica, or ceramics. Either the triac itself, or assembled with a radiator.

In the photo, behind the Thermodat, there is a fan power supply. I then added it to the fan, which I placed on the lower grille. The power supply unit is the simplest - trans, bridge and capacitor, produces 12 volts. Computer fan.
Heater outlet. Through the grate output in a ceramic tube. To connect to the terminal, I used a bolt drilled across.
Entering a thermocouple into the control unit. If you do not have such a ceramic tube, send the required amount to YaSAM.

Please note - the installation is made with an ordinary mounting wire, high-current circuits - stranded at least 6 mm2, thermocouple ends - directly into the terminal block. BUS in the factory form does not fit, I had to remove the cover - (and who is easy now? ;). The rest can be seen in the photo.

Transformer.

Despite such a formidable appearance, this device is a conventional 1 kW transformer. It's just that before that he changed several professions (graphite smelter, welder, etc.) and got a case, an automatic switch, an indicator of the current consumed from the network, and other wonderful things.

Of course, you do not have to fence all this, a simple kilowatt trance under the table is enough. The basis of everything is a sh-shaped iron transformer. I, depending on the need, rewind it without disassembling and without changing the primary.
What is a transformer for? The fact is that in order for the heater to work for some acceptable amount of time, the diameter of the wire must be as thick as possible. After analyzing this table, we can draw a disappointing conclusion - the wire should be as thick as possible. And this is no longer 220 volts.

Therefore, you will not find heaters designed for 220 volts in serious devices. Directly, if you connect this heater to the network, then the power consumption will be around 9 kW. You will plant a network throughout the house, and such a blow will be fatal for the heater. Therefore, voltage limiting circuits are used. For me, the most convenient is to use a transformer.
So, the primary: - 1.1 Volts per turn
- No-load current 450 mA
Secondary: - for a load of 5 ohms and a power of 1000 W, the voltage will be 70 Volts
- secondary current 14 A, wire 6 mm2, wire length 28 m.
Of course, this heater is not eternal. But I can replace it by finding a suitable wire and quickly rewinding the secondary.
If you read the instructions for Thermodat, then there is the possibility of limiting the maximum power. But this will not work for us, because we are talking about the average power per heater. In the mode of distributed pulses, as we have, the pulses will be for all 9 kW and we risk getting a pandemonium with light music. And on the neighbors too, because the machines in the entrance are also designed for average power.

For those who do not like to read instructions for a long time, I post a cheat sheet with coefficients and settings for a specific oven. After setting the Thermodata, turn on the trance and go.
The indicator of the current consumed from the network, due to the inertia of the arrow, also shows the average power. While the heater is cold, the current will be closer to 5 amps, as it warms up a little lower (due to the increase in heater resistance). As it approaches the setpoint, it will drop to almost zero (PID operation).

We load a full crucible with bronze scrap, close the lid. The lid is lined from the inside with fireclay lightweight on a mortar for fireplaces and stoves. For those who are especially curious (I myself am), there is a window covered with mica in the lid.

The temperature is over 1000, and the surface of the melter has not yet warmed up. This speaks volumes about the quality of the lining. After 30-40 minutes, the contents of the crucible melted.
After the end of melting, we press the elevator lever, after which we can already pick up the crucible with a grip. The photo shows a recess in the upper part of the crucible just for a secure grip.

P.S. About crucibles. YaSAM completes its furnaces with graphite crucibles that work with these heaters. If you work with gold and silver, it makes sense to buy them. But I am against these bourgeois excesses. The fact is that the F32/28 stainless pipe miraculously coincides with the diameter of the graphite crucible. Draw your own conclusion

We isolate the heater leads from the body with ceramic tubes. Ceramic tubes - from fuses, it is possible from resistors.

The top row of bricks is flush with the edge of the hull. Don't forget the hole for the elevator rod.

Third layer of lining. In this layer we make holes for the heater leads and for the thermocouple (pictured).

The second layer of lining. Cut for the upper output of the heater.

In induction furnaces, the metal is heated by currents excited in the non-variable field of the inductor. In essence, induction furnaces are also resistance furnaces, but differ from them in the way that energy is transferred to the heated metal. Unlike resistance ovens Electric Energy in induction furnaces, it turns first into electromagnetic, then again into electric, and finally into heat.

At induction heating heat is released directly in the heated metal, so the use of heat is the most complete. From this point of view, these furnaces are the most advanced type of electric furnaces.

There are two types of induction furnaces: with a core and without a core, crucible. In core furnaces, the metal is in an annular trough around the inductor, inside of which the core passes. In crucible furnaces, a crucible with metal is located inside the inductor. It is impossible to use a closed core in this case.

Due to a number of electrodynamic effects that occur in the metal ring around the inductor, the specific power of channel furnaces is limited to certain limits. Therefore, these furnaces are mainly used for melting low-melting non-ferrous metals and only in some cases are used for melting and overheating cast iron in foundries.

The specific power of induction crucible furnaces can be quite high, and the forces resulting from the interaction of metal and inductor magnetic furnaces have a positive effect on the process in these furnaces, contributing to metal mixing.

How to assemble an induction furnace - diagrams and instructions

Coreless induction furnaces are used for smelting special, especially low-carbon steels and alloys based on nickel, chromium, iron, cobalt.

An important advantage of crucible furnaces is the simplicity of design and small dimensions. Thanks to this, they can be completely placed in a vacuum chamber and it is possible to process the metal with vacuum during the melting process. As vacuum steel-smelting units, induction crucible furnaces are becoming more and more widespread in the metallurgy of high-quality steels.

Figure 3. Schematic representation of an induction channel furnace (a) and a transformer (b)

Induction furnaces. Melting technology in induction furnaces

INDUCTION CRUCIBLE FURNACES.

Alloys of ferrous and non-ferrous metals and pure Me (cast iron, steel, bronze, brass, copper, and aluminum) are smelted in these furnaces. By current frequency: 1) Furnaces of industrial frequency 50 Hz. 2) Medium frequency up to 600 Hz. (up to 2400 Hz also included). 3) High frequency up to 18000Hz.

Often ind. ovens work in pairs (duplex process). In the first furnace, the mixture is melted, in the second, Me is brought to the desired chemical. composition or withstand Me at the desired t-re until the moment of pouring. The transfer of Mel from furnace to furnace can be carried out continuously along the chute using crane ladles or ladles on an electric car. In induction furnaces, the composition of the charge changes; instead of pig iron, lightweight low-quality materials are used (chips, lightweight scrap metal, waste own production, i.e. trim).

Operating principle The charge is loaded into the crucible, variable el. the current passing through the inductor (coil) creates a magnetic field that induces an electromotive force in the metal cage, which is caused by induced currents, which cause heating and melting of Mel. Inside the coil there is a crucible made of refractory material, which protects the inductor from exposure to liquid Mel. The primary winding is an inductor. Secondary winding and at the same time load - Me-l in the crucible.

The efficiency of the furnace depends on the electrical resistance of Me-la and on the frequency of the current. For high efficiency, it is necessary that the diameter of the charge (d of the crucible) be at least 3.5-7 current penetration depths in Me-l. Approximate ratios between the crucible capacity and the current frequency for steel and cast iron. The productivity of the furnaces is usually 30-40 t/h for cast iron and steel. With an electric power consumption of 500-1000 kWh / ton. For bronze, copper 15-22 t/h, for aluminum 8-9 t/h. Most often, a cylindrical crucible is used. The magnetic flux created by the inductor passes through closed lines both inside the inductor and outside.

Depending on the way the magnetic flux passes with outside distinguish: 1) open; 2) shielded; 3) closed oven design

With an open design, the magnetic flux passes through the air, so the structural elements (for example, the frame) are non-metallic or placed at a great distance from the inductor. When shielding, the magnetic flux from steel structures is separated by a copper screen. When closed - the magnetic flux passes through the radially arranged packages of transformer steel - magnetic circuits.

Scheme of the device of an electric induction furnace: 1 - cover, 2 turning unit, 3 - inductor, 4 - magnetic circuits, 5 - metal structure, 6 - water cooling inlets, 7 - crucible, 8 - platform

The furnace includes sl. nodes:Inductor, Lining, Frame, Magnetic circuits, Cover, Padina, Tilt mechanisms.

Aluminum Smelting Furnace

In addition to the main purpose, the inductor also performs the function of the element that perceives the fur. and thermal load from the side of the crucible. In addition, the cooling of the inductor ensures the removal of heat that occurs due to electrical losses, therefore, the inductors are made either in the form of a cylindrical single-layer coil, where all the turns are arranged in the form of a spiral with a constant angle of inclination, or in the form of a coil, all the turns of which are laid in a horizontal plane , and the transitions between them are in the form of short inclined sections.

Depending on the brand Me-la and level t-r 3 types of lining are used:

1. Sour(contains > 90% SiO2) withstands 80-100 melts

2. Main(up to 85% MgO) withstands 40-50 melts for small furnaces and up to 20 melts for furnaces with a capacity of >1 ton

3. Neutral(based on Al2O3 or CrO2 oxides)

Schemes of induction melting furnaces: a - crucible, b - channel; 1 - inductor; 2 - molten metal; 3 - crucible; 4 - magnetic core; 5 - a hearth stone with a heat release channel.

The padina is made of fireclay bricks for large ovens or aspot cement for small ones. Issue cover from structural steel and lined from the inside. Advantages of crucible furnaces:1) Intensive circulation of the melt in the crucible; 2) The ability to create an atmosphere of any type (oxidizing, reducing, neutral) at any pressure; 3) High performance; 4) Possibility of complete draining of Me-la from the furnace; 5) Ease of maintenance, the possibility of mechanization and automation. Flaws: 1) Relatively low t-ra slags directed at the Me-la mirror; 2) Relatively low lining life at high t-max melt and in the presence of heat exchangers.

INDUCTION DUCT FURNACES.

The principle of operation is that a variable magnetic flux permeates a closed circuit formed by liquid Chalk and excites a current in this circuit.

The contour of liquid Me-la is surrounded by a refractory material, which is baked into a steel case. The space filled with liquid Chalk has the shape of a curved channel. The working space of the furnace (bath) is connected to the channel by 2 holes, due to which a closed circuit is formed. During operation of the furnace, liquid Me-l moves in the channel and at the junctions with the bath. The movement is caused by Mel-la overheating (in the channel it is higher by 50-100 ºС than in the bath), as well as by the influence of a magnetic field.

When all Mel is drained from the furnace, an electrical circuit breaks, which is created by liquid Mel in the channel. Therefore, in channel furnaces produce a partial discharge of liquid Me-la. The mass of the “swamp” is determined based on the fact that the mass of the column of liquid Mel above the channel exceeds the electrodynamic force pushing Mel out of the channel.

Channel furnaces are used as a mixer for holding and melting furnaces. The mixer is designed to accumulate a certain mass of Me-la and hold Me-la at a certain t-re. The capacity of the mixer is assumed to be at least twice the hourly output of the melting furnace. Dispensing ovens are used to pour liquid Me-la directly into molds.

Compared to crucible furnaces, channel furnaces have lower capital investments (50-70% of crucible furnaces), low specific power consumption (higher efficiency). Flaw: Lack of flexibility in chemical composition regulation.

The main nodes include: Furnace frame; lining; Inductor; Fur-zm tilt; Electrical equipment; Water cooling system.