Induction heater - This is electric heaterworking when changing the magnetic induction flow in a closed conductive circuit. This phenomenon is called electromagnetic induction. Want to know how it works induction heatingatel? Zavodrr. - This is a trading information portal, where you will find information about heaters.
The induction coil is capable of heating any metal, the heaters are collected on transistors and have a high efficiency of more than 95%, they have long replaced the lamp induction heaters, which did not go out for 60%.
The vortex induction heater for contactless heating does not have losses to set the resonant coincidence of the operating parameters of the installation with the parameters of the output oscillating circuit. Vortex-type heaters collected on transistors are able to perfectly analyze and adjust the output frequency in automatic mode.
Heaters for the induction heating of the metal have a contactless way due to the action of the vortex field. Different types of heaters penetrate the metal to a certain depth of 0.1 to 10 cm, depending on the selected frequency:
Induction metal heaters allow you to handle the details not only on open sitesBut also placing heated objects in isolated cameras in which you can create any environment, as well as vacuum.
High Frequency Electric Induction Heater Every day she gains new ways to use. The heater operates on an alternating electric current. Most often, induction electric heaters are used to bring metals to the necessary temperatures at the following operations: forging, soldering, welding, bending, hardening, etc. Electrical induction heaters, operate at a high frequency of 30-100 kHz and are used for heating different types media and coolants.
Electric heater Applied in many areas:
When a deeper heating is required, induction heaters of the mid-frequency type, operating average frequencies from 1 to 20 kHz. The compact inductor for all types of heaters is the most different shape, which is selected so as to ensure the uniform heating of the samples of the most diverse shape, and the specified local heating can be carried out. The mid-frequency type will treat materials for forging and quenching, as well as through heating under stamping.
Light in management, with efficiency up to 100%, induction mid-frequency heaters are used for a large circle of technologies in metallurgy (also for smelting of various metals), mechanical engineering, instrument making and other areas.
The widest range of high-frequency induction heaters. Heaters are characterized by a high frequency of 30-100 kHz and a wide range of 15-160 kW capacities. The high-frequency type provides a small heating depth, but this is enough to improve the chemical properties of the metal.
High-frequency induction heaters are easy to manage and economical, and at the same time their efficiency can reach 95%. All types work continuously for a long time, and a two-bit version (when a high frequency transformer is put into a separate unit) allows 24-hour work. The heater has 28 types of protection, each of which is responsible for its function. Example: water control in the cooling system.
Ultrahigh-frequency induction heaters are over frequency (100-1.5 MHz), and penetrate the warm-up depth (up to 1 mm). A superhigh frequency type is indispensable for treating thin, small, with a small diameter of parts. The use of such heaters avoids unwanted deformations associated with heating.
Ultrahigh-frequency induction heaters on JGBT modules and MOSFET transistors have a power limits - 3.5-500 kW. Used in electronics, in the production of high-precision tools, hours, jewelry, for the production of wire and for other purposes involving special accuracy and filigree.
The main purpose of the induction heaters of a blacksmith type (ICN) is heated by parts or their parts preceding the subsequent forging. Billets can be of different types, alloy and forms. Induction blacksmith heaters allow you to handle cylindrical billets by any diameter in automatic mode:
Induction heaters for hardening shafts Work together with the hardening complex. The processed item is in a vertical position and rotates inside a fixed inductor. The heater allows you to use all types of shafts for serial local heating, the depth of injection can be the shares of millimeters in depth.
As a result of the induction heating of the shaft along the entire length with an instant cooling, its strength and durability increase repeatedly.
All types of pipes can be treated with induction heaters. The pipe heater can be with an air or water type of cooling, with a capacity of 10-250 kW, with the following parameters:
Each thermoproining option is used to improve the quality of any steel pipes.
One of the most important parameters of the work of induction heaters - temperature. For more careful control over it, in addition to embedded sensors, infrared pyrometers are often used. These optical devices allow you to quickly and easily determine the temperature of it difficult to access (due to high heating, the probability of exposure to electricity, etc.) of surfaces.
If you connect a pyrometer to the induction heater, you can not only track temperature modebut also automatically maintain the heating temperature for a specified time.
In the inductor during operation, a magnetic field is formed in which the part is placed. Depending on the task assigned (the heating depth) and the parts (composition), the frequency is selected, it can be from 0.5 to 700 kHz.
The principle of operation of the heater according to the laws of physics reads: when the conductor is found in a variable electromagnetic field, it is formed by EMF (electromotive force). The amplitude schedule shows that it moves in proportion to the change in the speed of the magnetic flux. Due to this, vortex currents are formed in the circuit, the magnitude of which depends on the resistance (material) of the conductor. Under the law, Joule-Lenz, the current leads to the heating of the conductor, which has resistance.
The principle of operation of all types of induction heaters is similar to a transformer. Conductive billet, which is located in the inductor, is similar to a transformer (without magnetic pipeline). Primary winding is an inductor, the secondary inductance of the part, and the load is metal resistance. When tvch, the heating is formed "skin-effect", the vortex currents that are formed inside the workpiece, displacing the main current to the surface of the conductor, because the heating of the metal on the surface is stronger than inside.
The induction heater has undoubted advantages and is the leader among all types of instruments. This advantage is folded in the following:
Repair of induction heaters is made from spare parts from our warehouse. At the moment we can repair all types of heaters. Induction heaters are sufficiently reliable if it is strictly followed by operating instructions and not allow the extensive mode of operation - first of all monitor the temperature and proper water cooling.
The subtleties of the operation of all types of induction heaters are often not fully published in the documentation of manufacturers, their repair should be engaged in qualified specialists who are familiar with the detailed principle of work of such equipment.
You can familiarize yourself with the video operation of the mid-frequency induction heater. The average frequency is used for deep penetration To all types of metal products. The mid-frequency heater is a reliable and modern equipment that works around the round for the benefit of your enterprise.
The uniqueness of a person is that he always invents devices and mechanisms that greatly facilitate work in one or another area of \u200b\u200blabor or vital activity.
For this, usually apply newest Developments in the field of science.
Exclusion did not and induction heating. Recently, the principle of induction has been widely used in many areas, which can be safely attributed to:
To date, there is a great set of induction plants of industrial type. But this does not mean that the design of such devices is very intricate.
The simplest induction heater is quite possible to make for household needs with his own hands. In this article, let us talk in detail about the induction heater, as well as various methods Its manufacturer do it.
Induction units for heating, which are constructed with their own hands, as a rule, is usually divided into two main types:
The vortex induction heater (wines) consists of the following structural components:
The principle of wine functioning is the following steps:
Profession of a specialist: Since the induction coil is considered the most important element of the heater of this species, then it is necessary to approach its manufacture: the copper wire should be filled with tight coats plastic pipe. The number of turns should be at least 100.
As can be seen from the description, the design of the wine is not complicated enough, so the vortex heater can be safely made with his own hands.
First option.
Electronic heater circuit. (To enlarge, press) quite simple and, at the same time, a powerful induction heater can be constructed based on a printed circuit board, the diagram of which is shown in the figure.
The features of this scheme are the following important points:
Specialist Council: Since the inductor will be highlighted strong heat, then, in order to avoid damage, it is recommended to install transistors for special radiators.
Second option.
This method of the induction heater device is based on the use of an electronic transformer.
Its essence is as follows:
So we indicated all possible methods Assembling induction heater using electronic parts. We hope that our advice and recommendations will be very cognitive information for you.
See the video in which an experienced user explains one of the options for manufacturing an induction heater with your own hands:
Electric heaters are very popular, which are simultaneously safe to operate, functional and effective. Made with your own hands the induction heater can be used to heal water or become the basis of the entire heating system in a private house. It is only necessary to choose a quality scheme of manufacturing, which will make it possible to make reliable and universal equipment to use.
Similar heater - an effective heating agent
The principle of operation of induction heaters is based on the separation of heat by metals when current passing through them. When the voltage is applied to the conductive circuit, a magnetic field and an induction current is formed, which highlights a large amount of heat. Today, based on this technology, various electrical heaters are manufactured, which simultaneously combine compact dimensions and are distinguished by magnificent power. Due to the simplicity of the design of such installations, it will not be difficult to make them.
One of the advantages of this heater is almost 100% efficiency. The benefits of induction heating include the following:
In the life of induction heating technology is implemented in kitchen plates and fully automated heating boilers. Such installations are popular in the domestic market, which is explained by their simplicity of service, reliability of construction, efficiency and versatility of use.
The scheme of the induction heater device is so simple that it is not difficult to assemble it with your own hands. It will only require the minimum reading of the schemes and the ability to work with a soldering iron or similar equipment. You can make as the simplest options for heating heating in the room and make a full-fledged cauldron for a country house.
In this video you will learn how to make a simple induction heater
Induction heating technology is characterized by the effectiveness and simplicity of the scheme of its execution. To date, the distribution received two types of induction:
In the manufacture of homemade heaters, vortex varieties of induction are used, which is explained by the simplicity of their implementation and excellent efficiency. The principle of operation of such equipment is based on energy transmission to the coolant from the magnetic field. Powerful radiation is formed in a metallic conductive inductor. When electrotok passes through a metal coil, it creates powerful vortex flows, with their subsequent transformation into thermal energy.
The heat exchanger of such a boiler can be performed as a conventional column, where water comes from the bottom under pressure, and its induction heating is carried out. The heated coolant comes out of the boiler through the upper nozzle and is sent to the closed circuit of the heating system. Permanent circulation of water in the boiler warns overheating of the elements, which ensures the maximum possible safety of the use of such equipment.
The formation of scale is preventing a light vibration of the coolant when it passes through the heat exchanger, which eliminates the appearance of calcium sediments, and the homeowner eliminates any cleaning and other induction equipment service.
Induction heating is not yet so popular as gas and solid fuel boilers. Similar can be explained by the high cost of such heating systems of private houses. For household use, the boiler built on induction technology will cost 30,000 rubles and higher. Therefore, it is not surprising that many homeowners refuse to buy factory equipment and make it independently. If there is an appropriate scheme, inexpensive components and skills, you can read the technical documentation for several hours to perform an efficient and fully safe heater on induction for the heating boiler.
Perform high-quality heating induction elements can be based on a transformer with primary and secondary winding. Vortex currents necessary for the work of such equipment are formed in the primary winding and create an induction field. A powerful electromagnetic field affects the secondary winding, which is, in fact, the induction heater and emits a large amount of heat used for heating the coolant.
The design of the self-made induction heater based on the transformer will include the following items:
The core is performed in the form of two ferromagnetic tubes with different diameters. They are welded in each other, after which a toroidal winding from a durable copper wire is performed. Not less than 85 turns With mandatory withstand equal distance between them. When electricity through the core and the winding in the closed circuit, the vortex streams are created that heat the core and the secondary winding. Subsequently, the resulting heat is used to heat the coolant.
In the inductor scheme, with its own hands using a high-frequency inverter, the main elements is the alternator, heating elements and inductors. The generator will be required to convert a standard voltage with a frequency of 50 hertz into high-frequency electricals. After modulating, the current is fed to the inductor coil having cylindrical shape. The coil winding is performed from copper wire, which allows you to generate a magnetic variable field that creates the necessary vortex currents, due to the appearance of which the metal body of the water jacket is heated. The resulting heat is transmitted to the coolant.
Perform a high-quality heater on the basis of a high-frequency welding inverter will not be difficult. It is only necessary to take care of high-quality and reliable thermal insulation, which will ensure the maximum efficiency of the CPD. Otherwise, in the absence of reliable insulation, the efficiency of the heating system is significantly reduced, which leads to significant consumption of electricity to the equipment.
There are at least 3 main elements that must be in working condition in the heater Making the simplest induction metal heater with their own hands will not be much difficulty. For such work, the following tools will be required:
For the manufacture of the coil, which is used to radiate an alternating magnetic field, you will need to prepare a segment of a copper tube with a length of 800 millimeters and a diameter of 8 millimeters.
Of the components used, the most expensive are powerful power transistors that need to be installed at least two. For such a work, IRFP 150, IRFP260 or IRFP460 will be suitable.
You can make the oscillating circuit of the water heater using ceramic capacitors with a voltage of 1600 volts and a capacity of 0.1 MF. To form an AC coil with high power, not less than 7 such capacitors will be used on 12 V.
During operation, field transistors can be very hot. Without the use of high-quality aluminum radiators, they spread literally after a few seconds after the voltage is supplied to the transformer. Heat sinks and radiators put on transistors through the thermal college, otherwise the cooling efficiency will not be too high.
Diodes for induction wines of heaters use ultrafine action. It is best for such a scheme that the models of Her 307, UF 4700, MUR 460 are suitable.
It will also be necessary to purchase two resistors with a capacity of 10 com and with a capacity of approximately 0.25 W, one 2 watt resistor with a capacity of 440 ohms. You will need to use two stabilion with a voltage of 15 volts. The optimal power is not less than 2 watts. To the power wires that supply voltage to the coil, set a standard choke.
The power supply of the heater is performed due to the power supply unit with a voltage of 12-40 volts and a power of no more than 500 W. Can be used car batteries or power supply from the old computer.
A spiral with a diameter of about 4 centimeters is performed from the copper pipe along the existing template. It should have at least 7 turns that do not come into contact with each other. At the end of the second tube, ferromagnetic fastening rings are welded, which will be required to connect transistors to the radiator.
The printed circuit board is made according to the scheme that allows you to implement standard current conversion to powerful and high-frequency. With large voltage amplitudes, the manufacturer made independently the heater will work stably, consuming the minimum of electricity and providing high-quality heating. Capacitors are installed on pCB In parallel, forming an oscillating circuit with a coil.
A trial launch is running, during which the lack of short circuits in the springs windings are lacking. In the presence of closures and contact turns of the coil with each other, transistors will instantly fail, and the inductor heater made with their own hands will require expensive repairs.
Inside the induction coil, it is possible to establish an insulation of the heat exchanger case, inside of which the heated liquid will circulate. Due to its high efficiency, induction heating technology even with minimal electricity consumption ensures the allocation of a large number of thermal energy, which allows you to warm up the room.
The heat exchanger is made of a pipe with a diameter of 20 millimeters, which is made of stainless steel. One or more induction spirals are bored with such a pipe, while metal elements should not touch the coils of the snail, which is under voltage. In terms of capacity in 2 kW, the effectiveness of such an appliance will be sufficient to ensure the flow of fluid flowing with its subsequent use for technical purposes or for heating the room.
Induction heaters are a promising technology that is actively used today in the manufacture of autonomous heating boilers. The simplicity of the implementation scheme of such electrical appliances allows them to be performed independently. By making such an inductive heater with your own hands, you can save on the purchase of expensive techniques, while in its functionality homemade devices Will not give up to expensive factory heaters.
When in front of a person, it becomes necessary to heat the metallic object, fire itself comes to mind. Fire is an old-fashioned, ineffective and slow way to heat the metal. He spends the lion's share of energy on heat, and from the fire always goes smoke. It would be nice if all these problems could be avoided.
Today I will show you how to assemble the induction heater with your own hands with the ZVS driver. This device heats the majority of metals using the ZVS driver and power of electromagnetism. Such a heater is highly efficient, does not produce smoke, and the heating of such small metal products, how, let's allow, the clip is a question of several seconds. The video demonstrates the heater in action, but the instruction there is represented another.
Many of you are now wondering - what is this zvs driver? This is a highly efficient transformer capable of creating a powerful electromagnetic field, heating metal, the basis of our heater.
To make it clear how our device works, I will tell about the key points. First important moment - 24 V. power supply voltage must be 24V at maximum current 10a. I will have two lead-acid batteries connected in series. They are powered by the ZVS drive card. The transformer gives the established current to the spiral, the inside of which the object is placed, which must be heated. A constant change in the current direction creates a variable magnetic field. It creates inside the metal of vortex currents, mostly high frequency. Because of these currents and low metal resistance, heat is highlighted. According to the Ohm's law, the current is transformed into heat in the circuit with active resistance, will be p \u003d i ^ 2 * R.
Metal is very important from which the object that you want to heat is very important. Iron-based alloys have higher magnetic permeability, they can use more magnetic field energy. Because of this, they heat up faster. Aluminum has low magnetic permeability and heats up, respectively, longer. And objects with high resistance and low magnetic permeability, such as a finger, do not warm at all. The material resistance is very important. The higher the resistance, the weaker the current will pass through the material, and that, accordingly, heat is less separated. The lower resistance, the stronger there will be a current, and according to the law of Oma, less voltage loss. It is a bit difficult, but due to the connection between resistance and power issuing, the maximum output of power is achieved when the resistance is 0.
ZVS transformer is the most complex part of the device, I will explain how it works. When the current is included, it goes through two induction chokes to both ends of the spiral. These chokes are needed to make sure that the device will not exceed too much current. Further, the current goes through 2 470 ohm resistors for MDP transistor shutters.
Due to the fact that there are no ideal components, one transistor will be turned on earlier than the other. When this happens, it assumes the entire incoming current from the second transistor. He will also shove the second to earth. Because of this, not only the current flows through the coil into the ground, but also through the fast diode will be discharged by the second transistor, thereby blocking it. Due to the fact that the condenser is connected parallel to the coil, the oscillating circuit is created. Because of the resulting resonance, the current will change its direction, the voltage will fall to 0B. At this moment, the valve of the first transistor is discharged through a diode on the shutter of the second transistor, blocking it. This cycle is repeated thousands of times per second.
The 10K resistor is designed to reduce the excess charge of the shutter of the transistor, acting as a condenser, and the zener diode must maintain the voltage on the shutters of the transistors of 12V or lower so that they do not explode. This transformer high-frequency voltage converter allows you to heat up with metal objects.
It's time to assemble the heater.
To assemble the heater of materials, you need a little, and most of them, fortunately, can be found for free. If you saw somewhere lying just so the electronmother's tube, go and take it. There is in it most of The parts fit for the heater. If you want better details, buy them in the store of electrical parts.
You will need:
For this project you will need:
In this device, the transistors are turned off at a voltage of 0 V, and it is not very hot. But if you want the heater to work for longer than one minute, you need to remove heat from transistors. I made both transistors one common heat absorber. Make sure the metal valves do not concern the absorber, otherwise the TIR transistors are short and they will explode. I used a computer heat sink, and there was already a strip of silicone sealant. To check insulation, tap the multimeter of the middle leg of each TIR-transistor (shutter) if the multimeter was packed, then the transistors are not insulated.
Capacitors are very hot due to the current constantly passing through them. Our heater needs a capacitance of a 0.47 Igf capacitor. Therefore, we need to combine all capacitors in the block, so we get the required container, and the heat dissipation area will increase. The rated voltage of the capacitors should be above 400 V to take into account the peaks of the inductive voltage in the resonant circuit. I made two copper wire rings to which 10 capacitors were 0.047 μF parallel to each other. Thus, I received a condenser battery with a cumulative capacity of 0.47 μF with excellent air-cooled. I will install it parallel to the working spiral.
This is the part of the device in which the magnetic field is created. The spiral is made of copper wire - it is very important that copper is used. At first I used the steel spiral for heating, and the device was not very good. Without workload, he consumed 14 A! For comparison, after replacing the spiral on the copper, the device began to consume only 3 A. I think that in the steel spirals there were vortex currents due to the content of iron, and it also exposed to induction heating. Not sure that the reason is exactly the case, but this explanation seems to me the most logical.
For spirals, take the copper wire of a large cross section and take 9 turns on the segment of the PVC pipe.
I did a lot of samples and made a lot of mistakes while the chain gathered correctly. Most of all the difficulties were with a power source and a spiral. I took the 55A 12V pulse power supply. I think this power supply has given too high initial current on the ZVS driver, which was exploded by TIR transistors. Perhaps it would be corrected by additional inductors, but I decided to simply replace the power supply for lead-acid batteries.
Then I suffered with a coil. As I said, the steel coil did not fit. Because of the high current consumption of the steel spiral, several more transistors exploded. In total, I exploded 6 transistors. Well, on errors learn.
I reworked the heater many times, but here I will tell you how I collected him the most successful version.
To assemble the ZVS driver, you need to follow the attached scheme. At first I took the zener diode and connected with a 10K resistor. This couple of items can be immediately soldered between the drain and the source of the TIR transistor. Make sure the zener diode looks at the stock. Then solder TIR transistors to the cabinet with contact holes. On the underside of the dummy board, you solder two fast diodes between the shutter and the flow of each of the transistors.
Make sure the white line looks at the shutter (Fig. 2). Then connect the plus from your power supply with the drains of both transistors after 2,220 ohms of the resistor. Ground both sources. Space the working helix and the condenser battery parallel to each other, then solder each one of the ends to different shutters. Finally, move the current to the shutters of transistors through 2 50 μg of choke. They may have a toroidal core with 10 wire turns. Now your scheme is ready to use.
To keep all parts of your induction heater together, they need a base. I took for this wooden bar 5 * 10 cm. Board with an electrical circuit, the condenser battery and the working helix were glued on the thermocons. It seems to me that the unit looks cool.
So that your heater is turned on, simply connect it to the power source. Then place the subject you need to heat, in the middle of the working spiral. He must start warm. My heater rolled the clip to the red glow in 10 seconds. The items are larger as nails, heated in about 30 seconds. In the process of heating, current consumption has increased by approximately 2 A. This heater can be used not only for entertainment.
After using the device, soot or smoke is not formed, it also affects insulated metal objects, for example, gas supplies in vacuum tubes. Also, the device is safe for a person - nothing will happen to the finger if you put it in the center of the working spiral. However, you can burn about the subject that was heated.
Thanks for reading!
Induction heating (induction heating) - the method of contactless heating of high frequency currents (English. RFH - Radio-Frequency Heating, heating by the waves of the radio frequency range) of electrically conductive materials.
Description of the method.
Induction heating is the heating of materials by electrical currents that are induced by a variable magnetic field. Therefore, it is the heating of products from conductive materials (conductors) by a magnetic field of inducers (sources of an alternating magnetic field). Induction heating is carried out as follows. Electrically conductive (metallic, graphite) Billet is placed in the so-called inductor, which is one or more turns of the wire (most often copper). In the inductor, with the help of a special generator, powerful currents of different frequencies are subject to (from a dozen Hz to several MHz), as a result of which an electromagnetic field occurs around the inductor. The electromagnetic field suggests vortex currents in the workpiece. The vortex currents warm up the workpiece under the action of Joulehe heat (see the Joule-Lenza law).
The "inductor-blank" system is a non-dedicated transformer in which the inductor is a primary winding. The workpiece is a secondary winding, closed spice. The magnetic flow between the windings is closed through the air.
At high frequency, the vortex currents are displaced by the magnetic field formed by the same magnetic field into thin surface layers of the blank δ (surface effect), as a result of which their density increases sharply, and the workpiece is heated. The following metal layers are heated due to thermal conductivity. It is not current current, but a large current density. In the skin-layer Δ The current density decreases in e times relative to the current density on the surface of the workpiece, while 86.4% of heat is released into the skin-layer. The depth of the skin layer depends on the frequency of the radiation: the higher the frequency, the thinner Skin layer. It also depends on the relative magnetic permeability of μ material of the workpiece.
For iron, cobalt, nickel and magnetic alloys at temperatures below the point of Curie μ has a value from several hundred to tens of thousands. For other materials (melts, non-ferrous metals, liquid low-melting eutectics, graphite, electrolytes, electrically conductive ceramics, etc.) μ is approximately equal to one.
For example, at a frequency of 2 MHz, the depth of the skin layer for copper is about 0.25 mm, for iron ≈ 0.001 mm.
The inductor is strongly heated during operation, as it absorbs itself its own radiation. In addition, it absorbs thermal radiation from a split billet. Make inductors from copper tubesWater cooled. Water is satisfied with suction - this ensures safety in the event of a burner or other depressurization of the inductor.
Application:
Ultrapy contactless smelting, soldering and welding of metal.
Obtaining prototypes of alloys.
Bending and heat treatment of machine parts.
Jewelry.
Processing small parts that may be damaged during gas-flame or arc heating.
Surface hardening.
Hardening and heat treatment of parts of complex shape.
Disinfection of medical instrument.
Benefits.
High-speed heating or melting of any electrically conductive material.
It is possible to heat in an atmosphere of protective gas, in an oxidative (or reducing) medium, in a non-conductive fluid, in vacuo.
Heating through the walls of the protective chamber made of glass, cement, plastics, wood - these materials are very poorly absorb electromagnetic radiation and remain cold when installing installation. Only the electrically conductive material is heated - metal (including melted), carbon, conductive ceramics, electrolytes, liquid metals, etc.
Due to the arising MHD, the efforts occurs intensive mixing of the liquid metal, up to hold of it in a suspended state in air or protective gas - so far be obtained alloys in small quantities (levitational smelting, smelting in an electromagnetic crucible).
Since the heating is carried out by means of electromagnetic radiation, there is no contamination of the preparation of the combustion of the torch in the case of gas-flame heating, or the electrode material in the case of arc heating. Placing samples into an atmosphere of inert gas and high speed Heating will eliminate the scale.
Ease of operation due to a small inductor size.
The inductor can be made of a special form - this will allow it evenly to warm over the entire surface of the detail of a complex configuration, without leading to their warping or local non-rest.
Easy to carry out local and selective heating.
Since the most intense warm-up is in the thin upper layers of the workpiece, and the underlying layers warmer more gently due to thermal conductivity, the method is ideal for carrying out surface hardening of parts (the core remains viscous).
Easy equipment automation - heating and cooling cycles, adjustment and deterring temperature, feed and eat blanks.
Induction heating installations:
At installations with a working frequency of up to 300 kHz, inverters are used on IGBT assemblies or MOSFET transistors. Such installations are designed for heating large parts. To warm up small parts, high frequencies are used (up to 5 MHz, the range of average and short waves), High frequency installations are built on electronic lamps.
Also, for warming up small parts, the installation of increased frequency on the MOSFET transistors on operating frequencies to 1.7 MHz is being built. Transistor management and their protection at elevated frequencies represent certain difficulties, so the installation of an increased frequency is still quite expensive.
The inductor for heating small parts has small sizes and a small inductance, which leads to a decrease in the quality of the working oscillatory circuit at low frequencies and a reduction in efficiency, and is also dangerous for the specifying generator (the voltage of the oscillating circuit is proportional to L / C, the oscillatory outline with low qualityness too good "Pumping out" with energy, forms a short circuit in the inductor and displays the specifying generator). To increase the voluntaryness of the oscillatory circuit, use two ways:
- increasing the operating frequency, which leads to the complication and appreciation of the plant;
- the use of ferromagnetic inserts in the inductor; Pluging inductor with ferromagnetic material panels.
Since the most efficient inductor works at high frequencies, industrial use of induction heating received after developing and started production of powerful generator lamps. Prior to World War I, induction heating had limited use. As generators, then used machine generators of an increased frequency (work V. P. Vologdin) or spark discharge settings.
The generator scheme can be in principle any (multivibrator, RC generator, an independent excitation generator, various relaxation generators) operating on the load in the form of an inductor coil and with sufficient power. It is also necessary that the frequency of oscillations is high enough.
For example, to "cut" in a few seconds steel wire with a diameter of 4 mm, a oscillatory capacity is needed at least 2 kW at a frequency of at least 300 kHz.
Choose a scheme for the following criteria: Reliability; stability of oscillations; stability of power secreted in the billet; simplicity; convenience of setting; minimum number of parts to reduce cost; Application of parts, in the amount of mass reduction and dimensions, etc.
For many decades, an inductive trimmer was used as a high-frequency oscillation generator (Hartley Generator, an autotransformed feedback generator, a circuit on an inductive contour voltage divider). This is a self-exciting scheme of parallel power of an anode and a frequency-selective chain, made on the oscillatory circuit. It was successfully used and continues to be used in laboratories, jewelry workshops, industrial enterprises, as well as in amateur practice. For example, during the Second World War on such installations, a surface hardening of the rollers of T-34 tank was performed.
Disadvantages of three points:
Low efficiency (less than 40% when using a lamp).
The strong deviation of the frequency at the time of heating the billets from magnetic materials above the Curie point (≈700C) (changes μ), which changes the depth of the skin-layer and unpredictably changes the heat treatment mode. When thermal processing of responsible parts, it may be unacceptable. Also, powerful TDHs should operate in a narrow range of frequencies permitted Rossvyazokhrankulture, since with poor shielding are actually radio transmitters and can interfere with television and radio broadcasting, coastal and rescue services.
When changing billets (for example, smaller to larger) changes the inductance of the inductor-blank system, which also leads to a change in the frequency and depth of the skin layer.
When changing single inductors on multi-ski, on larger or more small-sized frequencies also changes.
Under the leadership of Babat, Lozinsky and other scientists, two- and three-constructive schemes of generators with a higher efficiency (up to 70%) were developed, as well as better retaining operating frequency. The principle of their action is as follows. Due to the use of related contours and loosening the connection between them, the change in the inductance of the working circuit does not entail a strong change in frequency frequency circuit. By the same principle, radio transmitters are designed.
Modern TVH-generators are inverters on IGBT assemblies or powerful MOSFET transistors, usually made according to the bridge or semi-sequence. Work at frequencies up to 500 kHz. Transistor shutters are open using a microcontroller control system. The control system, depending on the task, allows you to automatically hold
A) constant frequency
b) constant power allocated in the workpiece
c) the highest efficiency.
For example, when the magnetic material is heated above the Curie point, the skin-layer thickness increases sharply, the current density drops, and the billet begins to warm worse. The magnetic properties of the material also disappear and the magnetization process is stopped - the billet begins to heat worse, the load resistance is jumpingly decreased - this can lead to a "separation" of the generator and the failure of it. The control system monitors the transition through the Curie point and automatically increases the frequency with a hopping load reduction (or reduces power).
Comments.
Inductor if possible, it is necessary to have as close as possible to the workpiece. This not only increases the density of the electromagnetic field near the workpiece (in proportion to the square of the distance), but also increases the power coefficient COS (φ).
Increasing the frequency sharply reduces the power coefficient (proportional to the frequency cube).
When the magnetic materials are heated, additional heat is also highlighted due to reclamation, their heating to the point Curie is much more efficient.
When calculating the inductor, it is necessary to take into account the inductance of the entrance to the inductor of the tire, which can be much more inductance of the inductor itself (if the inductor is made in the form of a single turn of a small diameter or even parts of the turn - arcs).
There are two cases of resonance in oscillatory circuits: stress resonance and current resonance.
Parallel oscillatory circuit - reasons.
In this case, on the coil and on the condenser, the voltage is the same as the generator. With resonance, the contour resistance between branching points becomes the maximum, and the current (I total) through the load resistance RN will be minimal (current inside the loop I-1L and I-2C larger than the generator current).
In the ideal case, the total contour resistance is equal to infinity - the diagram does not consume the current from the source. When the generator frequency changes, to any side of the resonance frequency, the total contour resistance decreases and the linear current (I Society) increases.
Sequential oscillating circuit - stress resonance.
The main feature of the serial resonance contour is that its full resistance is minimally with resonance. (ZL + ZC - minimum). When adjusting the frequency by a value exceeding or the resonant frequency below, the imperative increases.
Output:
In a parallel circuit, with a resonance, the current through the conclusions of the contour is 0, and the voltage is maximum.
In a sequential circuit, on the contrary, the voltage tends to zero, and the current is maximum.
The article is taken from the site http://dic.academic.ru/ and recycled to a more understandable text for the reader, the company LLC "Prominductor".
