Developed over a century ago, induction stoves have become a fixture in our everyday lives. This became possible thanks to the development of electronics. Explosive growth in the power of controllers made on the basis of silicon semiconductors and the appearance on wide sale of transistors capable of providing high powers (several kilowatts) in last years took on the character of an avalanche. All this has given humanity incredibly great prospects in the development of miniature installations comparable in power to industrial devices of the recent past.

Use and structure of the device

The use of induction furnaces in household allows you to avoid the appearance of open flames in the room and is quite effective way melting and controlled heating of metals and alloys. This occurs due to the fact that the metal heats up, heats up and melts not under the influence of high-temperature burners, but by passing high-frequency currents through itself, stimulating the active movement of particles in the structure of the material.

It became possible to appear in everyday life:

In addition, electric induction stoves, which work not only with conductive material, are becoming increasingly widespread. Their design is slightly different from conventional induction furnaces, since it is based on heating by electrical induction a material that does not conduct current (they are also called dielectrics) between the capacitor plates, that is, its conclusions of different polarity. The temperatures achieved are not very high (about 80−150 degrees Celsius), so such installations are used for melting plastic or its heat treatment.

Design features and operating principle

An induction furnace operates on the basis of the formation of eddy electric currents in it. To do this, use an inductor consisting of turns of thick wire, to which the source is connected alternating current. It is alternating current that forms a constantly changing magnetic field depending on the current frequency. It provokes the transfer of these currents to the substance placed inside the coil along with big amount heat. In this case, even the most ordinary welding inverter can act as a generator.

There are two types of induction furnaces:

1. With a magnetic core, the peculiarity of which is the location of the inductor inside the volume of metal that can be melted.
2. Without a magnetic circuit - when the inductor is located outside.

The design with a magnetic core is used, for example, in channel furnaces. They use an open metal (most often steel) magnetic circuit, inside of which there is a crucible for melting and an inductor, forming the primary winding circuit. The crucible material may be graphite, heat-resistant clay, or any other non-conducting material having suitable heat resistance. The metal that needs to be melted is placed in it. These are, as a rule, all kinds of alloys of non-ferrous metals, duralumin and cast iron.

The generator of such a furnace must provide AC frequency within 400 hertz. It is also possible to use a conventional generator instead electrical network and power the furnace using a current with a frequency of 50 hertz, but in this case the heating temperature will be lower and such an installation will not be suitable for more refractory alloys.

Crucible furnaces, which do not have a magnetic circuit in their design, have become much more widespread among enthusiasts. They use currents of significantly higher frequencies to achieve higher field densities. This is due precisely to the absence of a magnetic circuit - too large a percentage of the field energy is dissipated in space. To counteract this, you need to very finely tune the oven:

• Ensure equal frequency of the induction circuit and the voltage from the generator (this is easiest to do when using an inverter).
• Select the diameter of the melting crucible so that it is close to the wavelength of the resulting magnetic field radiation.

In this way, losses can be minimized by up to 25% of the total power. To achieve the same best result It is recommended to set the AC source frequency twice or even three times higher than the resonant frequency. In this case, the diffusion of the metals that make up the alloy will be maximum, and its quality will be much better. If you increase the frequency further, you can achieve the effect of pushing the high-frequency field to the surface of the product and thus harden it.

Vacuum melting furnaces

This type of installation can hardly be called household, but it is worth considering because vacuum melting has a number of technological advantages compared to other types. In its design, it resembles a crucible, with the difference that the furnace itself is located in a vacuum chamber. This makes it possible to achieve greater purity of the metal melting process, reduce its oxidation during processing and speed up the process, achieving significant energy savings.

In addition, the limited and enclosed space helps to avoid the release of harmful fumes from melting metals into the surrounding space and maintain the cleanliness of the processing process. The ability to control the composition and processing process is also one of the advantages of this type of furnace.

Duct induction units

Another type of industrial furnace that has wider applications than others. They can be used not only as smelters, but also as distributors of prepared material and mixers of several types of raw materials. Typical designs of such devices include:

The slightest opening of the circuit, which is formed by the liquid metal, magnetic circuit and coil, leads to an increase in its own resistance and an instant release of the entire mass of raw material from the channel. To counteract this phenomenon, a “swamp” is left inside the channel - a small mass of metal that is maintained in liquid form.

Advantages of channel-type induction furnaces:

• Low cost of installations.
• Economical - to maintain the temperature inside the bath, which does not dissipate heat well, a small amount of electricity is needed.
• Coefficient useful action the inductor during operation is very high.

Flaws:

Basic elements of the furnace circuit

In order to assemble the installation and perform work on it, it is necessary to find a suitable diagram of the induction furnace and parts for it. To find the latter, it will be very useful to have one or more unnecessary power supplies from your computer, since most of the parts can be found in them. Typical scheme the simplest oven With homemade inverter will include elements such as:

The inverter for the installation is assembled according to the scheme proposed by S.V. Kukhtetsky for laboratory tests. It can be easily found on the Internet. The power of the inverter, which is powered by a voltage in the range of 12–35 volts, will be 6 kilowatts, and its operating frequency will be 40–80 kilohertz, this will be more than enough for home projects.

Safety precautions at work

Since working with an induction furnace involves close contact with molten metal and currents of high frequency and strength, it is worth taking care of high-quality grounding of the installation and reliable means of protection. In this case, clothing must strictly comply with all requirements:

Do not forget about good ventilation of the room in which they will work. Molten metal releases chemical compounds into the air that are not at all good for your lungs.

Vacuum units are indispensable equipment in industries where it is necessary to smelt metals and alloys, providing them with a high degree of purification. The sealed vacuum chamber prevents the penetration of contaminants and foreign gases. This allows you to obtain products without impurities or oxidations. If you need to buy a vacuum induction furnace in Moscow, you can order it from our company.

Working principle of vacuum induction furnace

An induction type vacuum furnace is equipped with a crucible in which metal is melted. Based on the operating principle, these products are divided into semi-continuous and periodic. The semi-continuous vacuum unit allows multiple heats to be performed without opening the housing. For batch-type equipment, the chamber depressurizes after each melting process.

The vacuum chamber in which the melting process takes place is sealed, which makes it possible to obtain absolutely pure products. The metal does not oxidize during processing, due to the absence of oxygen, foreign particles do not enter it. Supports required pressure, the air is pumped out by a vacuum pump with which the device is equipped.

Infrared ovens have a number of differences from other types of units:

• it is allowed to use any material: scrap, pieces, briquettes;
• liquid metal can be in a vacuum for a long time;
• during the smelting process it is possible to control and change the chemical composition and temperature of the alloy;
• can be used different ways refining and deoxidation during smelting.

This vacuum installation can be used for smelting heat-resistant, precision heat-resistant alloys, and stainless steel.

Advantages of Dana Engineering

Purchasing ready-made vacuum induction furnaces or ordering their production according to an exclusive project from Dana Engineering in Moscow provides several advantages:

• impeccable quality and durability of equipment;
• prompt order fulfillment;
• moderate cost of production.

Our company employs experienced, highly qualified specialists. They own a number of innovations that have made it possible to increase the efficiency and cost-effectiveness of installations. During our work, we have established reliable relationships with the best manufacturers components. The design bureau is located on the territory of the enterprise, which allows you to quickly develop and implement projects.

Sales and prices of vacuum induction furnaces

For those wishing to determine in advance the future costs that a vacuum induction furnace will require, the price of standard designs is indicated in the price list. The cost of equipment that is produced according to exclusive projects customer, calculated individually. It consists of several factors: the type of furnace, its dimensions, the material used to make the chamber and crucible, and additional devices.

Production and supply of vacuum induction furnaces in Russia and CIS countries

Currently, the demand for steel and specialty alloys for the aerospace, aviation, nuclear and power generation industries is growing rapidly. These industries often require more and more high values on strength, purity and other properties of the metal.

In order to solve the problem of improving the quality properties of smelted metals, the MetaCube company is ready to offer technologies based on innovative smelting methods for producing steel and alloys with special technological properties. These methods include vacuum induction melting.

The need to create vacuum induction furnaces arose in connection with the need to introduce industrial production highly reactive and refractory metals, such as zirconium, titanium, niobium, beryllium and molybdenum, as well as tantalum, tungsten, uranium and a number of others. A peculiarity of such metals is that they oxidize intensively when heated in air, and therefore melting must be carried out in a vacuum.

Features of vacuum induction furnaces

Vacuum induction melting technology makes it possible to obtain highly purified metals in an oxygen-free atmosphere. When using vacuum induction furnaces, it is possible to produce heat-resistant and high-alloy steels and precision alloys. Also, in vacuum induction furnaces, it is possible to carry out heat treatment and melting of precious and rare earth metals, as well as melting high-grade special glass and use them to obtain single crystals. In all cases, the material obtained in vacuum furnaces is distinguished by increased purity and minimal waste.

An important role during refining in a vacuum induction furnace is played by the process of evaporation of low-melting impurities - lead, arsenic, tin and bismuth. The high qualities of the vacuum metal are partly ensured by the purification of the alloy from these impurities, which are contained in very small quantities, which makes it impossible to determine them even with advanced analytical methods. This is necessary when the requirements for the material are quite high and the resulting special alloy must meet certain properties.

Another advantage of vacuum furnaces is the ability to obtain single-crystalline and fine-grained metal structures. In this case, the properties of the resulting material can be predicted.

The operating temperature of the furnaces is up to 2200 degrees.

• Possibility of long-term exposure of liquid metal in a deep vacuum;
• High degree of metal degassing;
• Possibility to reload the furnace during the melting process;
• The ability to actively influence the intensification of deoxidation and refining processes at any time during smelting;
• Opportunity effective control and regulation of the state of the melt according to its temperature and chemical composition throughout the entire process;
• Particular purity of the resulting castings due to the absence of any non-metallic inclusions;
• Possibility to produce fast heating(direct heating due to the heat released in the melt) due to which productivity increases;
• High homogeneity of the melt due to active mixing of the metal;
• Any form of raw materials (lumpy materials, briquettes, powder, etc.)
• High efficiency and environmental friendliness.

Design of vacuum furnaces

is a high-frequency furnace made of a refractory crucible, placed inside an inductor, which in turn is located inside a sealed housing, from which vacuum pumps gases are pumped out. The crucible of vacuum furnaces is made from powdered highly refractory materials by packing in an inductor according to a template. Vacuum induction furnaces are mechanized units. Metal pouring can occur either by rotating the furnace inside the chamber, or by rotating the chamber itself as a whole. A vacuum induction melting furnace allows you to independently perform the following operations: adjust the temperature of the melt, change the pressure inside the chamber, mix the melt, and also add other elements to the melt.

The modular principle of constructing vacuum furnaces makes it possible to achieve increased compactness of the furnace, as well as the possibility of connecting additional modules - a chamber for unloading, pouring, and also removing the resulting products.

The design of modern vacuum induction furnaces makes it possible to install molds and unload ingots from them without breaking the vacuum in the furnace. Vacuum induction furnaces are most often automated devices. Loading of the charge, introduction of additives and additives, and casting of metal are carried out using an electric or hydraulic drive.

Buy a vacuum induction furnace at a low price - MetaCube Company

The MetaCube company is ready to offer you a wide selection of vacuum induction furnaces according to low prices with delivery and commissioning throughout Russia and the CIS countries. Our company has extensive experience in supplying various metallurgical equipment to enterprises in Russia, Kazakhstan, Belarus and other CIS countries.

Vacuum melting furnaces are used to produce metals and alloys highest quality. Low pressure in the space of the working chamber allows you to sharply reduce the gas content in the ingot without the use of protective environments.

Scope of application of induction furnaces

Vacuum furnaces are used in many technological processes:

melting of metals and alloys: refractory, heat-resistant, high-alloy;

sintering of products from easily oxidizing metals;

degassing of liquid metals and other materials;

heat treatment of metals (quenching, tempering, annealing);

coating by deposition of evaporated metals, etc.

Main types of vacuum furnaces

The most common types of vacuum furnaces are:

arc: used for smelting stainless, electrical and other high-quality steels, refractory metals (titanium, zirconium, tantalum, etc.);

plasma: designed for melting highly reactive and refractory metals;

induction: they can be classified as equipment wide application. The most widespread vacuum melting induction furnaces with tilting crucible. They are used in large metallurgical plants for melting high-quality and high-alloy steels and casting them into molds.

Standard sizes of melting furnaces

Based on their dimensions, vacuum melting furnaces are divided into laboratory (capacity up to 50-100 kg) and industrial. However, such a classification is very arbitrary: there are many models of industrial importance with a working volume of only 10-20 kg.

Operating principle of induction industrial furnaces

Despite design features different types vacuum melting furnaces, they work on the same principle: in a refractory crucible placed in vacuum chamber, with the help of a heating element, the metal is melted (or liquid is heated), refined and alloyed. The process ends with casting shaped products or simple ingots.

According to the principle of operation, vacuum melting furnaces are divided into three groups:

semi-continuous;

continuous action;

periodic action.

Semi-continuous industrial melting furnaces do not require systematic depressurization. Molds are changed in them using chambers separated from the main one by gates. The same sluice devices are used to load the furnace. Semi-continuous devices are used in industry. Thanks to their design features:

the refractory lining of the crucibles is in favorable conditions, since it is not subject to temperature changes;

there is no need to pump out air before starting a new melt, which has a very positive effect on the productivity of the furnace;

in the chamber the formation of metal oxides is reduced to a minimum, and, consequently, the contamination of subsequent melting is reduced.

In smelting industrial ovens Gateways are not provided for periodic operation. To remove the mold or load the charge, you have to depressurize the housing each time and open the vacuum chamber. Laboratory ovens operate on this principle.

The main advantages of vacuum furnaces are:

economic benefit: instead of expensive inert gases, low pressure in the chamber is used;

high degree of metal purification;

the ability to strictly control the chemical composition and temperature of the melt at any stage of the technological process;

protection of heating elements from oxidation, which allows increasing the operating temperature.

The cost of vacuum melting induction furnaces and other models is quite high, but the costs quickly pay off during their operation.

Based on their operating mode, vacuum induction furnaces (VIF) are divided into batch and semi-continuous furnaces.

Batch furnaces have only one chamber – the melting and pouring chamber. After each melting and pouring of molds, the specified chamber is depressurized; remove the filled form from it; clean and fill the crucible; the charge is loaded into it again; place an empty form in the chamber; close the camera; the air is pumped out of it and a new melt is made.

Semi-continuous vacuum furnaces have, in addition to the melting and pouring chamber, additional chambers - at least one vertical and one or two horizontal. Each of the additional chambers is connected at one end to the melting and pouring chamber (MPC), and the second end is free. Additional chambers are isolated from the melting and pouring chamber (at the connection points) by vacuum seals. Similar shutters open or close the free ends of the chambers. In semi-continuous VIP, loading of the charge into the crucible and its melting, batching and all types of finishing of the liquid metal, supply of empty molds (or molds), their pouring, solidification of the liquid metal, removal of the filled molds - all these technological operations are performed without breaking the vacuum in the sealed valve.

Based on the method of draining liquid metal from a crucible into a mold or mold, VIPs are distinguished:

a) with the entire SCP tilted together with the crucible and the poured mold, suspended on hinges to the casing of this chamber;

b) with only the crucible tilted inside the PZK, and the mold to be poured is mounted motionless on some support inside the chamber.

Vacuum furnaces of semi-continuous operation include furnaces VIAM - 100, VIAM - 24, ISV - 0.6, ULVAK, KONSARK, etc.

The VIAM-100 furnace PZK has a cylindrical shape and is located horizontally. Approximately in the center of the chamber there is a crucible (with an inductor), which, when draining the liquid metal, tilts along the axis of the seal. Below the crucible there is a roller table (with disc rollers), on which the molds are placed during pouring. A vertical cylindrical chamber is installed on the upper part of the SCP casing, through which the charge is loaded into the crucible without depressurizing the melting working space of the furnace. The axis of the vertical charge chamber coincides with the axis of symmetry of the crucible.

Before starting the next oven cycle

VIAM – 100 it is necessary: ​​the crucible should be inspected, cleaned and repaired (if necessary); Close the SCP on all sides with vacuum seals (i.e., isolate it from all other chambers) and pump out air from it to a residual pressure of mm Hg. Art.; depressurize the upper and side chambers, i.e. open their external vacuum seals. Strictly speaking, the listed operations are performed before the start of the first melt. If the furnace operates in a continuous mode (for example, during two shifts), then the PZK, naturally, is not depressurized and the charge is loaded into the crucible immediately after the previous dose of liquid metal is drained.

Next, to resume a new melting cycle, it is necessary to: take a dose of the charge components into a special loading basket, place it in the charge chamber and close the chamber with an external vacuum seal; pump out air from the charge chamber to a residual pressure equal to the pressure in the shut-off valve; open the internal vacuum seal between these chambers, unload the charge from the basket into the crucible; lift the empty basket into the batch chamber and close the internal vacuum seal; supply air (at atmospheric pressure) into the charge chamber; open the external vacuum seal; collect a dose of charge components into the loading basket, etc.; start melting the charge in the crucible.

The VIAM-100 furnace also has two horizontal additional cylindrical chambers. These chambers are located on the sides (left and right) of the central protective shield and are connected to it with their working ends. As mentioned above, each side chamber at both ends (working and free) is closed or opened by vacuum shutters. At the bottom of the chambers there are roller conveyors with disc rollers located at the same level as the rollers in the shut-off valve. Through one of the side chambers (for example, the right one), empty molds are fed into the melting chamber for pouring. Let's call the right chamber the loading chamber. Through the other (left) they are removed after they are filled. Let's call the left chamber the unloading chamber. The sequence of feeding empty molds after the end of melting: place the molds to be poured on the auxiliary roller table (in front of the right chamber) so that the pouring bowls of different shapes are located in the same horizontal plane, the most convenient for pouring from the crucible; push the forms onto the roller table inside the right chamber and close it with an external vacuum seal; pump out air from the loading (right) chamber to a residual pressure equal to the pressure in the shut-off valve; open the vacuum seal between these chambers, submit (in turn) the first, second and other molds for pouring, positioning each of them so that the pouring bowl is under the toe of the crucible, and fill the molds (the number of molds depends on their metal content and overall dimensions); close the vacuum seal between the melting and pouring and loading chambers; supply air into the loading chamber (at atmospheric pressure), open the external vacuum seal and prepare for the next arrival of forms.

The left side chamber is used as follows: close the free end with an external vacuum seal (the working end was closed with a vacuum seal earlier before the start of melting): pump out air from the discharge (left) chamber to a residual pressure equal to the pressure in the shut-off valve; open the vacuum shutter between these chambers, move the poured molds from the melting room to the left chamber and close the vacuum shutter, while maintaining the “vacuum” in the shut-off valve; supply air (at atmospheric pressure) to the unloading chamber, open the external vacuum shutter and roll out the filled forms onto the auxiliary roller conveyor located after the left chamber. The order and operating time of all chambers must be coordinated so that the furnace downtime is minimal. If shell ceramic molds obtained by investment casting are used, then the time between removing these molds from the calcination furnace and pouring should be no more than 15 minutes.

The VIAM-100 oven can work with one side chamber, for example the right one, using it both for loading empty forms and for unloading filled ones. The sequence of closing and opening vacuum valves, pumping or supplying air to the side chamber, etc. depends on the purpose for which it is used at a given stage of the furnace operation.

The VIAM-24 vacuum furnace consists of three main chambers: melting and pouring, charge and for feeding and dispensing casting molds.

The shut-off valve has a cylindrical shape, is located horizontally and is closed at the ends by spherical bottoms, of which the front one opens like a door, and the rear one moves along the axis of the chamber. In the center of the chamber there is a crucible (with an inductor) attached to the rear bottom, so if you move the bottom, the crucible is removed from the SCP and using, for example, a workshop overhead crane, you can repair or replace the crucible or inductor. When draining the liquid metal crucible, it tilts in a plane perpendicular to the axis of its chamber. Under the crucible there is a roller conveyor with disc rollers for setting molds during pouring.

The charge chamber is made in the form of a cylinder, located vertically on the PZK casing coaxially with the crucible and isolated from the melting space by a vacuum seal. Loading of the charge through this chamber is carried out similarly to the VIAM-100 furnace.

The only side chamber has a cylindrical shape, is located horizontally and its working end is connected to the slam-shut valve through a vacuum seal. Such a shutter closes and opens the free end of the side chamber. Inside the chamber there is a roller conveyor with disc rollers. The sequence of supplying empty forms from this chamber for filling and receiving filled forms is the same as in similar chambers of the VIAM-100 furnace. An auxiliary roller conveyor for empty and filled forms is also installed in front of the chamber.

In Fig. Figure 1.5 shows a device for a semi-continuous vacuum ITP type ISV - 0.6 for casting ingots from heat-resistant alloys and special steels.

The ISV - 0.6 furnace is serviced as follows: Slam-shut valve 1 of the furnace is closed on top with a lid 7 located on a self-propelled bridge-type trolley 8 with an electric drive. The trolley with the lid moves on the rails to the right (according to Fig. 1.5), the shut-off valve opens, resulting in free access for cleaning, repairing and replacing the crucible 3.

Rice. 1.5. Vacuum ITP type ISV – 0.6

semi-continuous:

1 – melting and pouring chamber; 2 – melting crucible; 3 – chamber for loading the charge into the crucible; 4 – rotary column; 5 – device for taking fluid samples and measuring its temperature; 6 – dispenser; 7 – lid of the melting and pouring chamber; 8 – four-wheeled self-propelled cart; 9 – vacuum seal; 10 – chamber for loading and unloading molds (i.e. casting molds);

11 – trolley for feeding molds (molds) into the loading and melting-pouring chambers and removing filled molds from them; 12 – charge chamber casing; 13 – basket for charge;

14 – winch for lowering and raising the basket for the charge

The charge is loaded into the crucible using the charge chamber 3, which is a cylindrical casing 12, inside of which a basket 13 for the charge is suspended on a cable. The basket with the charge loaded into it is lowered into the crucible using a winch 14, after which the bottom of the basket opens and the charge is poured into the crucible. Charge chamber 3 is mounted on a rotating column 4, which allows chamber 3 to be moved to the side for the convenience of loading basket 13 with a new portion of charge into it. Chamber 3 is separated from the shut-off valve by a vacuum technological shutter and connected to the vacuum system. This allows the charge to be loaded into the crucible without breaking the vacuum in the sealed valve.

Dispenser 6 is designed for introducing various solid additives into the crucible during melting. The dispenser chamber has several sections into which the required filler materials are loaded. They are transferred from the dispenser to the crucible by a special rotary ladle with a hinged bottom. Just like the charge chamber 3, the dispenser 6 is separated from the SCP by a vacuum seal.

A chamber of 10 molds is connected to the SCP. It is separated from the workshop and the control room by technological vacuum valves 9 and connected to the vacuum system. The supply of molds into the mold chamber, and then into the shut-off valve, is carried out on a trolley 11. Consequently, the mold chamber with vacuum shutters acts as a sluice chamber, ensuring that vacuum is maintained in the shut-off valve when replacing molds in it. Pouring liquid metal into molds is done by tilting the crucible using an electric drive. The residual pressure in the furnace is 0.6 - 0.7 Pa. The furnace is powered from a thyristor source.