HDTV installations with frequency control. HDTV installation for hardening

The high-frequency current is generated in the installation due to the inductor and allows heating the product placed in close proximity to the inductor. The induction unit is ideal for hardening metal products. It is in the HDTV installation that you can clearly program: the desired depth of heat penetration, hardening time, heating temperature and cooling process.

For the first time, induction equipment was used for hardening after a proposal from V.P. Volodin in 1923. After long trials and testing of high-frequency heating, it has been used for steel hardening since 1935. HDTV hardening units are by far the most productive method of heat treatment of metal products.

Why induction is better for hardening

High-frequency hardening of metal parts is carried out to increase the resistance of the upper layer of the product to mechanical damage, while the center of the workpiece has an increased viscosity. It is important to note that the core of the product during high-frequency hardening remains completely unchanged.
The induction installation has many very important advantages in comparison with alternative types of heating: if earlier HDTV installations were more cumbersome and inconvenient, now this drawback has been corrected, and the equipment has become universal for heat treatment of metal products.

Advantages of induction equipment

One of the disadvantages of the induction hardening machine is the inability to process some products that have a complex shape.

Varieties of metal hardening

There are several types of metal hardening. For some products, it is enough to heat the metal and immediately cool it, while for others it is necessary to hold it at a certain temperature.
There are the following types of hardening:

• Stationary hardening: used, as a rule, for parts that have a small flat surface. The position of the workpiece and the inductor when using this method of hardening remains unchanged.
• Continuous-sequential hardening: used for hardening cylindrical or flat products. With continuous-sequential hardening, the part can move under the inductor, or it keeps its position unchanged.
• Tangential hardening of workpieces: excellent for machining small parts that have a cylindrical shape. Tangential continuous-sequential hardening scrolls the product once during the entire heat treatment process.
• An HDTV hardening unit is equipment capable of high-quality hardening of a product and at the same time saves production resources.

Hardening is an integral part production process heat treatment of metal products. Hardening of high-frequency current is carried out in order to increase the strength of the product and increase its service life. Previously, metal was hardened in hot oil, on an open fire or in electric furnaces, but now induction equipment has appeared that allows metal processing quickly and efficiently, increasing its wear resistance and resistance to external influences.

HDTV hardening plant

Manufacturers of induction equipment have developed lines of installations suitable for a specific metal heat treatment process. The high-frequency current hardening furnace is a hardening machine or a hardening complex. If an enterprise produces a large volume of products that need heat treatment and hardening, then it is best to purchase a hardening complex, the equipment of which includes everything necessary for comfortable metal processing.
The hardening complex includes: an induction unit, a hardening machine, a cooling module, a manipulator, a control panel, and, if the customer needs it, a set of inductors for processing products of various shapes and sizes.
The hardening machine can be of two types: horizontal and vertical. The horizontal hardening machine is most suitable for processing products over 3000 mm long, and the vertical one is less than 3000 mm long.

HDTV hardening - the advantages of induction furnaces

The HDTV hardening unit copes well with its functions, for this reason it quickly began to occupy a leading position among all types of heating that exist today.
Induction furnacesdesigned for HDTV hardening have a lot of advantages. The main advantages of HDTV hardening:

1. HDTV hardening is of high quality, since heat is generated directly in the metal, evenly distributed over its entire surface.
2. High frequency current hardening equipment has a compact size, so it does not take up much space in the workshop and can be installed in enterprises with a small area.
3. HDTV hardening occurs in a short period of time, which makes it possible to increase the level of products.
4. Induction heating is rightfully recognized as environmentally friendly. It does not harm and does not create discomfort for employees of the enterprise located in the workshop.
5. Hardening complex ELSIT has an automated software allowing high precision hardening.

HDTV hardening is becoming more and more popular, so if you have not purchased induction equipment yet, then think about it.

Steel hardening using high-frequency units provides surface hardness and wear resistance of the material without changing its properties in the core. They have the ability to adjust the degree of hardness. These indicators are calculated individually for each steel part, as they depend on its characteristics. The "HDTV Converter Plant" offers to purchase HDTV induction units for surface hardening of steel.

Application and configuration of HDTV installations for hardening

HDTV hardening units are used for parts with mandatory increased surface hardness that perform torsion, friction or bending. The equipment uses transistor frequency converters PFC-66 kHz with power from 50 to 320 kW. HDTV induction hardening units are successfully installed to replace old VCHG tube generators and thyristor frequency converters TPChR. Usage this equipment for large volumes of work, it will become highly efficient due to the productivity of steel induction hardening plants.

Characteristics of surface hardening plants

HDTV surface hardening equipment differs in the following parameters:

• Rated frequency, kHz;
• Operating frequency range, kHz;
• Input voltage, U;
• Power, kW;
• Diameter of hardened parts, mm;
• Length of the hardened seams, mm.

These installations have a high efficiency of use. They allow you to perform a large amount of work due to high productivity and automation of the hardening process. The use of heat treatment with this equipment eliminates oxidation and increases the allowable deformation of steel.

To order induction installations for HDTV surface hardening at HDTV Converters Plant LLC, please contact us by phone numbers on the website. Our experts will tell you about the configuration of the equipment, its technical parameters and complete your order.

For the first time, hardening of parts using induction heating was proposed by V.P. Volodin. It was almost a century ago - in 1923. And in 1935 this species heat treatment began to be used for hardening steel. It is difficult to overestimate the popularity of hardening today - it is actively used in almost all branches of engineering, and HDTV hardening installations are also in great demand.

To increase the hardness of the hardened layer and increase the toughness in the center of the steel part, it is necessary to use HDTV surface hardening. In this case, the upper layer of the part is heated to the hardening temperature and abruptly cooled. It is important that the properties of the core of the part remain unchanged. Since the center of the part retains its toughness, the part itself becomes stronger.

With the help of high-frequency hardening, it is possible to strengthen the inner layer of the alloyed part; it is used for medium-carbon steels (0.4-0.45% C).

Advantages of HDTV hardening:

1. With induction heating, only the desired part of the part is changed, this method is more economical than conventional heating. In addition, HDTV hardening takes less time;
2. With high-frequency hardening of steel, it is possible to avoid the appearance of cracks, as well as reduce the risk of warping defects;
3. During HDTV heating there is no burnout of carbon and the formation of scale;
4. If necessary, changes in the depth of the hardened layer are possible;
5. Using HDTV hardening, it is possible to increase mechanical properties become;
6. When using induction heating, it is possible to avoid the appearance of deformations;
7. Automation and mechanization of the entire heating process is at a high level.

However, HDTV hardening also has disadvantages. So, it is very problematic to process some complex parts, and in some cases, induction heating is completely unacceptable.

HDTV steel hardening - varieties:

Stationary HDTV hardening. It is used for hardening small flat parts (surfaces). In this case, the position of the workpiece and the heater is constantly maintained.

Continuous-sequential HDTV hardening. When performing this type of hardening, the part either moves under the heater or remains in place. In the latter case, the heater itself moves in the direction of the part. Such high-frequency hardening is suitable for processing flat and cylindrical parts, surfaces.

Tangential continuous-sequential HDTV hardening. It is used when heating only small cylindrical parts that scroll once.

Do you want to purchase quality hardening equipment? Then contact the research and production company "Ambit". We guarantee that each HDTV hardening machine we produce is reliable and high-tech.

Induction heating of various cutters before soldering, hardening,
induction heating unit IHM 15-8-50

Induction soldering, hardening (repair) of saw blades,
induction heating unit IHM 15-8-50

Induction heating of various cutters before soldering, hardening

Many critical parts work for abrasion and are simultaneously subjected to impact loads. Such parts must have a high surface hardness, good wear resistance and at the same time not be brittle, i.e., not break down under impact.

High surface hardness of parts while maintaining a tough and strong core is achieved by surface hardening.

From modern methods Surface hardening is most widely used in mechanical engineering for the following: hardening when heated high frequency currents (TVCh); flame hardening and hardening in an electrolyte.

The choice of one or another method of surface hardening is determined by technological and economic feasibility.

Hardening when heated by high-frequency currents. This method is one of the most efficient methods surface hardening metals. The discovery of this method and the development of its technological foundations belongs to the talented Russian scientist V.P. Vologdin.

High frequency heating is based on the following phenomenon. When passing a variable electric current high frequency along the copper inductor around the latter, a magnetic field is formed, which penetrates the steel part located in the inductor and induces Foucault eddy currents in it. These currents cause the metal to heat up.

heating feature HDTV is that the eddy currents induced in steel are not distributed uniformly over the section of the part, but are pushed to the surface. The uneven distribution of eddy currents leads to its uneven heating: the surface layers heat up very quickly to high temperatures, and the core either does not heat up at all or heats up slightly due to the thermal conductivity of steel. The thickness of the layer through which the current passes is called the penetration depth and is denoted by the letter δ.

The thickness of the layer mainly depends on the frequency of the alternating current, the resistivity of the metal and the magnetic permeability. This dependence is determined by the formula

δ \u003d 5.03-10 4 root of (ρ / μν) mm,

where ρ is the electrical resistivity, ohm mm 2 /m;

μ, - magnetic permeability, gs/e;

v - frequency, Hz.

It can be seen from the formula that with increasing frequency, the depth of penetration of induction currents decreases. High frequency current for induction heating of parts is obtained from generators.

When choosing the current frequency, in addition to the heated layer, it is necessary to take into account the shape and dimensions of the part in order to obtain a high quality surface hardening and economically use electrical energy high frequency installations.

Copper inductors are of great importance for high-quality heating of parts.

The most common inductors have a system of small holes on the inside through which cooling water is supplied. Such an inductor is both a heating and cooling device. As soon as the part placed in the inductor heats up to the set temperature, the current will automatically turn off and water will flow from the holes of the inductor and cool the surface of the part with a sprayer (water shower).

Parts can also be heated in inductors that do not have choking devices. In such inductors, the parts after heating are dumped into the hardening tank.

Hardening of HDTV is mainly carried out by simultaneous and continuous-sequential methods. With the simultaneous method, the hardened part rotates inside a fixed inductor, the width of which is equal to the hardened section. When the set heating time expires, the time relay cuts off the current from the generator, and another relay, interlocked with the first one, turns on the water supply, which bursts out of the inductor holes in small but strong jets and cools the part.

With the continuous-series method, the part is stationary, and the inductor moves along it. In this case, sequential heating of the hardened section of the part, after which the section falls under the water jet of a showering device located at some distance from the inductor.

Flat parts are hardened in loop and zigzag inductors, and gear wheels with a small module are simultaneously hardened in ring inductors. Macrostructure of the hardened layer of a fine-modulus car gear made of steel grade PPZ-55 (low hardenability steel). The microstructure of the hardened layer is finely acicular martensite.

The hardness of the surface layer of parts hardened by heating with high-frequency current is obtained by 3-4 units HRC higher than the hardness of conventional bulk hardening.

To increase the strength of the core, the parts are improved or normalized before hardening.

The use of HDTV heating for surface hardening of machine parts and tools makes it possible to drastically reduce the duration technological process heat treatment. In addition, this method makes it possible to manufacture mechanized and automated units for hardening parts, which are installed in the general flow of machining shops. As a result, there is no need to transport parts to special thermal shops and rhythmic work is ensured. production lines and assembly lines.

Flame surface hardening. This method consists in heating the surface of steel parts with an oxy-acetylene flame to a temperature that is 50-60 ° C higher than the upper critical point A C 3 , followed by rapid cooling with a water shower.

The essence of the flame hardening process is that the heat supplied by the gas flame from the burner to the hardened part is concentrated on its surface and significantly exceeds the amount of heat distributed into the depth of the metal. As a result of such a temperature field, the surface of the part first quickly heats up to the hardening temperature, then cools down, and the core of the part practically remains unhardened and does not change its structure and hardness after cooling.

Flame hardening is used to harden and increase the wear resistance of large and heavy steel parts such as crankshafts of mechanical presses, large-modulus gears, excavator bucket teeth, etc. In addition to steel parts, parts made of gray and pearlitic cast iron are subjected to flame hardening, for example guides of the beds of metal-cutting machines.

Flame hardening is divided into four types:

a) sequential, when the hardening torch with the coolant moves along the surface of the fixed part being processed;

b) hardening with rotation, in which the burner with the coolant remains stationary, and the part to be hardened rotates;

c) sequential with the rotation of the part, when the part continuously rotates and a hardening burner with a coolant moves along it;

d) local, in which the fixed part is heated to a given quenching temperature by a fixed burner, after which it is cooled by a jet of water.

A method of flame hardening a roller that rotates at a certain speed while the burner remains stationary. The heating temperature is controlled by a milliscope.

Depending on the purpose of the part, the depth of the hardened layer is usually taken equal to 2.5-4.5 mm.

The main factors affecting the depth of hardening and the structure of the hardened steel are: the speed of movement of the hardening torch relative to the hardened part or part relative to the burner; gas flow rate and flame temperature.

The choice of hardening machines depends on the shape of the parts, the hardening method and the required number of parts. If you need to harden parts of various shapes and sizes and in small quantities, then it is more expedient to use universal hardening machines. In factories, special installations and lathes are usually used.

For hardening, two types of burners are used: modular with a module from M10 to M30 and multi-flame with replaceable tips having a flame width of 25 to 85 mm. Structurally, the burners are arranged in such a way that the holes for the gas flame and cooling water are arranged in one row, in parallel. Water is supplied to the burners from the water supply network and serves simultaneously for hardening parts and cooling the mouthpiece.

Acetylene and oxygen are used as combustible gases.

After flame hardening, the microstructure in different zones of the part is different. The hardened layer gets a high hardness and remains clean, without traces of oxidation and decarburization.

The transition of the structure from the surface of the part to the core occurs smoothly, which has great importance to increase the operational stability of parts and completely eliminates harmful phenomena - cracking and delamination of hardened metal layers.

The hardness changes according to the structure of the hardened layer. On the surface of the part, it is equal to 56-57 HRC, and then lowered to the hardness that the part had before surface hardening. To ensure high quality hardening, obtaining uniform hardness and increased core strength, cast and forged parts are annealed or normalized in accordance with ordinary conditions before flame hardening.

Surface forcalc in the electrolyte. The essence of this phenomenon is that if a constant electric current is passed through the electrolyte, then a thin layer is formed on the cathode, consisting of the smallest hydrogen bubbles. Due to the poor electrical conductivity of hydrogen, the resistance to the passage of electric current increases greatly and the cathode (part) is heated to a high temperature, after which it is hardened. As an electrolyte, an aqueous 5-10% solution of soda ash is usually used.

The hardening process is simple and consists in the following. The part to be hardened is lowered into the electrolyte and connected to the negative pole of a DC generator with a voltage of 200-220 V and density 3-4 a / cm 2, as a result of which it becomes the cathode. Depending on which part of the part is subjected to surface hardening, the part is immersed to a certain depth. The part heats up in a few seconds, and the current is turned off. The cooling medium is the same electrolyte. So, the electrolyte bath serves as both a heating furnace and a quenching tank.