RU199207U1 - Multifunctional laboratory electric resistance furnace - Google Patents

Abstract

The utility model relates to a multifunctional laboratory electric resistance furnace for melting non-ferrous metal chips. The furnace contains a lined body with supports, a working chamber with heating elements and an extractable crucible located inside the working chamber, a limit switch for connecting to the power supply, guides located in a window made in the furnace roof, a removable cone-shaped nozzle for drying and fluxing chips, installed on crucible, and a tray for an emergency exit of metal from the furnace working chamber, installed under the furnace hearth supports, while the removed crucible is made in the form of a replaceable welded stainless steel melting and casting crucible with welded handles to ensure an axisymmetric installation of the crucible in the furnace along the mentioned guides, one from the handles of which it is made with the possibility of placing in its working position on the contact of the limit switch to prevent the removal of the replaceable melting and casting crucible from the furnace without first disconnecting the furnace from the supply network. EFFECT: simplification, reduction in cost and improvement of the quality of remelting and casting of non-ferrous metal alloys, in particular aluminum alloys, including their various chips, contaminated with various cutting fluids (coolant). 1 wp f-ly. 4 ill.

Description

The utility model relates to devices for efficient melting and casting of various aluminum alloys, melting and casting of various aluminum shavings, melting and casting of various other non-ferrous metals and alloys, allows for heat treatment of various parts made of ferrous and non-ferrous metals, is intended for various industries. It solves and removes several technological barriers: allows one and the same basic multifunctional laboratory resistance furnace, without any alteration, to carry out various technological processes: to melt aluminum ingots and lump scrap; remelting of various (twisted, chipped, drainage and other) aluminum shavings contaminated with various cutting fluids (coolant), emulsions and other aqueous technological media; allows for melting, casting and casting of various aluminum alloys into the required forms (into a chill mold, into sandy-clay molds, into plaster molds, into molds according to investment patterns and other forms); allows you to carry out various methods of heat treatment of various parts made of ferrous and non-ferrous metals (hardening, tempering, annealing and others); carry out the processes of drying paint and varnish and protective coatings, used for various other purposes.

Multifunctional laboratory electric resistance furnace allows you to optimize various production areas, eliminating additional traditional equipment and costs for the implementation of the above processes. A stationary shaft resistance melting furnace with a lined body is proposed, in the working chamber of which there is an extractable (plug-in, removable) crucible and heaters covering it. Unlike the known analogs, it provides for the possibility of removing the plug-in (removable) melting and casting crucible using the handles available on it and transferring the crucible with the melt and pouring the molten metal into the required place, into the required forms.

When installed on the melting and pouring crucible of the furnace with a metal conical nozzle, it allows efficient remelting of various aluminum shavings: dry shavings, shavings contaminated with various coolants, emulsions, detergents and other aqueous media. Due to its fluxing and drying in a conical nozzle, this can significantly increase the yield of suitable metal from remelted aluminum shavings.

The utility model relates to the field of metallurgy of non-ferrous metals and alloys, in particular to electric melting resistance furnaces and thermal electric resistance furnaces, intended, mainly as a laboratory one, for use in various industries. Can be used: in the metallurgical industry; in mechanical engineering; instrumentation; in the automotive industry; Food Industry; in the educational processes of technical schools, universities, research institutes engaged in the training of personnel in the casting and processing of various metals, the development of new alloys, the development of technologies for obtaining new products, consumer goods and in repair shops.

To assess the novelty of the claimed solution, let us consider a number of means of a similar purpose known to the applicant, characterized by a set of features similar to the claimed utility model, known from information that became available before the priority date of the utility model.

For example, resistance melting furnaces with a non-removable crucible are known, containing a lined body and a working chamber, with heaters molded in its walls, which, to ensure unloading of the melt, are usually made tiltable (tilting) using a rotary mechanism with a manual drive (Review "Electric resistance melting furnaces ", author Shishkin A.V., NSTU, AETU, 2012, p. 3) or with a pneumatic, hydraulic drive, for example, an electric crucible furnace for melting non-ferrous metals PP-2000M ZAO Nakal, Russia ( http://www.nakal.ru/catalog).

The disadvantage of such furnaces is that pouring metal into foundry molds requires pouring ladles, their preheating, mechanisms for transferring ladles with metal, many ladles (especially iron ones) require their preliminary preparation, for example, applying protective coatings to their inner surface to prevent contamination molten metal with ladle material. In such furnaces it is difficult to melt, for example, various aluminum shavings, without preliminary and rather expensive preparation.

A stationary melting dispensing electric furnace with a non-removable crucible is known, in which the melt is poured into a casting mold or an intermediate casting ladle by displacing the melt from the crucible using a special displacement mechanism (Review "Electric resistance melting furnaces" by A.V. Shishkin, NSTU, AETU, 2012, p. 5).

In these analogs, the presence of mechanisms for turning or displacing the melt determines the increased dimensions of the furnaces, it is difficult to switch to the remelting of one metal to another, without special flushing melting, additional auxiliary equipment is required, it is rather laborious to replace failed crucibles, worn-out crucibles require their irrecoverable disposal, when melting they also require special labor-intensive preparation and additional expensive equipment, so their use is more expedient, mainly, with a large crucible capacity (more than 60 kg).

Known more compact stationary resistance melting furnaces with a removable crucible, in which the crucible is not completely "recessed" in the working chamber of the body, but protrudes somewhat above it, and for pouring the melt into the casting mold (molds) is removed from the furnace manually using the furnace supplied grippers (tongs), by standard sizes corresponding to specific crucibles, for example, such furnaces as stationary electric furnace PP, JSC "Nakal" (http://www.nakal.ru/catalog/plavilnye-statsionarnye-pechi/); or a furnace of the MUV 400 type of the German company INDUTHERM Erwarmungsaniagen GmbH (Instructions for the furnaces of the MUN 400 to MUN 1200 type from 08.08; 2014; http://indutherm.de/webshop/index.php?page:=roduct&info=2337) ...

So a resistance melting furnace of the MUV 400 type, also containing a lined body with supports and a working chamber with heaters molded in its walls, as well as an extractable crucible located inside the working chamber of the furnace. In it, to ensure a reliable grip of the crucible, its upper part should protrude from the working space of the furnace onto the so-called "belt", approximately 30-70 mm high, depending on the dimensions of the crucible, which should also be attributed to disadvantages, since this size of the "belt »Is insufficient to vary the methods and means of extracting and transferring the crucible with the melt, for example, by mechanizing this process, and this reduces the range of technological possibilities for servicing the furnace, increases its cost, lowers the safety of casting technologies when moving liquid metal in cases of crucible failure.

The technological capabilities of such resistance melting furnaces are also severely limited, for example, in high-quality remelting in the same furnace of various aluminum alloys and their chips, with difficulties in reliably gripping and moving crucibles with a capacity of up to 30 kg over liquid aluminum; with the possibility of remelting and casting in a furnace of various other non-ferrous metals and alloys (babite, various zinc (for example, TsAM alloys), tin, lead, copper and other alloys) and their chips.

Known designs of some resistance furnaces with removable crucibles, aimed at solving issues of energy savings, optimizing the processes of melting various metals and their various shavings.

Thus, an electric laboratory crucible furnace is known, characterized in that the stationary heating chamber of the furnace is directed downward with its open end, which serves to introduce a crucible into the furnace, which is placed on the bottom supported by a handle and can move on the guide rods of the stand (RF Patent No. 8768). Such a melting furnace with a lifting bottom (hearth) of the furnace into the heating chamber and with a melting crucible installed on it, in the upper part of the roof (roof) of the furnace has a channel that serves to release gases. To obtain furnace temperatures of about 1000 degrees Celsius, the channel is closed, and the channel entrance to the furnace roof is covered with a fireclay cover. The crucible to be heated is placed on a thin-walled porcelain support, symmetrically installed on the bottom of the furnace, supported by a handle that can move on the support rod, and a thrust rod serves for central insertion of the crucible into the heating chamber of the furnace and removal of the crucible from the furnace.

This oven has many disadvantages. In it, the crucible is installed on a porcelain stand, and only small crucibles can be installed on it, for example, with a volume of liquid aluminum of no more than 5 (10) kg. When the crucible is eaten through or destroyed, the furnace does not have an emergency release of metal, and liquid metal undoubtedly gets on the heating elements of the furnace, causing it to fail in operation. In such a furnace, it is practically impossible to carry out high-quality melting using protective and refining fluxes. Even if the lifting under the furnace with the crucible is lowered to the bottom of the furnace, download the slags and carry out, for example, high-quality degassing of the molten metal in the crucible, before pouring the metal into the mold, it will also be difficult and ineffective. This takes a certain amount of time, and the metal in the crucible will cool down a lot and it will be quite laborious and time consuming to obtain a high-quality metal.

For moving heated crucibles and pouring metal, you will also need special pliers and grips for crucibles of various types and sizes. The placement of a channel in the upper part of the cover of the roof (roof) of the furnace, which serves to discharge the generating gases from the furnace, is not effective; it is required to connect additional gas suction systems to it.

It is also difficult, ineffective and inefficient to efficiently melt various lumpy secondary aluminum alloys and add their various shavings to them, even if it is preliminarily prepared in the form of pressed briquettes of the required dimensions.

The main problem of preparing various shavings for its rational remelting into high-quality foundry metal is that the highly branched surface of aluminum shavings of various shapes firmly retains various aqueous technological media - coolant, emulsions, washing solutions, and various other aqueous media. forming and emitting various gases during the melting of chips, especially hydrogen.

It is known that 1 kilogram of, for example, molten aluminum alloy, can dissolve up to 20 grams of hydrogen. Therefore, in order to obtain high-quality aluminum casting, using aluminum shavings, including as a secondary metal, they strive to remove their moisture as much as possible, for example, by pre-drying it in various dryers, degassing the melt in a melting crucible with various salts (for example , zinc chloride and other degassers), blowing of the melt (refining) with various neutral gases (for example, argon) and other methods. To reduce the waste of chips when preparing them for melting in various furnaces, including electric resistance furnaces, various methods and devices are also used to solve this problem, pressing dry chips into briquettes and other methods and methods of their preparation are used.

So, for example, to prepare for remelting and melting various chips of high-purity aluminum alloys, in RF patent No. 2323984, a method for processing chips includes preparing it for melting and melting, which consists in the fact that in the process of preparing for melting, the original chips are processed in a rotating perforated drum in a bath with an aqueous detergent solution with a concentration of 25-30 g / l at a temperature of 55-65 ° C for 7-10 minutes, then it is washed in running water at a temperature of 10-30 ° C for 1-2 minutes by bubbling, then it is re-rinsed in running water for 3-4 minutes in another bath, and then in running condensate at temperatures up to 90 ° C for 3-4 minutes, kept in a rotating drum above the bath for 1-2 min, dried at a temperature of 100-110 ° C for 10-15 minutes and briquetted. As the initial shavings, a mixture of various types of shavings is used, obtained after cutting with a saw, turning, turning templates, which is prepared at the following ratio: (2-4): (13-18): 1, respectively.

The technical result of such a complex preliminary preparation for remelting such initial shavings (RF patent No. 2323984), contaminated with technological media (coolant, emulsions, detergents), is aimed at reducing the cost of metal obtained using recycled chips of high-purity aluminum alloys while ensuring that the chemical composition of this metal to the established requirements.

This is dictated by the need to search for new sources of cheap raw materials, to find a solution to the problem of the most complete use of any waste, including shavings. this saves expensive charge materials, which is vital in a market economy and competition. However, this method is also quite apparatus-intensive, labor-consuming and expensive.

A known method of processing aluminum waste by mechanical processing, including degreasing, magnetic separation, briquetting, heating and pressing (Modern methods of manufacturing deformable semi-finished products from aluminum scrap in collection. Nonferrous metallurgy, series: Secondary metallurgy of non-ferrous metals. Overview, Issue 2, M. , 1990, p. 15).

This method of processing aluminum waste by mechanical processing also does not allow processing chips of various aluminum alloys due to insufficient complete removal of technological contaminants from its surface during this waste processing. The method is also expensive, apparatus-intensive, and expensive.

A known method of preparing aluminum chips for subsequent processing by briquetting it in a vacuum of 20-50 mm Hg. Art. (2.7-6.7 kPa) at temperatures up to 300 ° C and a specific briquetting pressure of 40-200 MPa (Modern methods of manufacturing deformable semi-finished products from aluminum scrap in collection. Non-ferrous metallurgy, series: Secondary metallurgy of non-ferrous metals. Survey information, Vol. .2, M., 1990, p. 10).

This method of preparing aluminum chips for subsequent processing does not exclude the excess of unacceptable impurity elements in the metal obtained using remelted chips prepared for processing according to the known method due to insufficient complete removal of technological contaminants from the surface of the chips in vacuum. In addition, this method is also quite complicated, apparatus-intensive and high-cost, which leads to an increase in the cost of metal obtained using remelted shavings prepared for processing by this method.

A known method of processing aluminum shavings, including preparing it for smelting and smelting (IV Nikolaev, VI Moskvitin, BA Fomin. Metallurgy of light alloys, M., Metallurgy, 1997, S. 268-270).

According to this method, the preparation of shavings for melting is carried out by drying it at a temperature of 400-500 ° C, magnetic separation, loading into boxes. Twisted shavings are crushed before drying. Prepared shavings are fed for melting.

This method of processing pre-crushed aluminum chips does not allow processing chips of some aluminum alloys due to insufficient complete removal of technological contaminants from its surface even at such drying temperatures and does not exclude the subsequent excess of impurity elements in the alloy metal during the melting process in amounts exceeding the established ones requirements. Dryers for various crushed shavings must be special, often expensive and sufficiently large, the drying time and additional energy consumption for drying can also be quite large.

Before drying, twisted chips are crushed, which also requires special crushing equipment, and the resulting liquids must also be somehow removed from the crushing equipment. It is known that 1 kg of twisted aluminum shavings in its branched surface can hold up to 10% of coolant (emulsions, detergents and other aqueous media that fall on it). When crushing such chips with process fluids, special or additional equipment is also required to ensure, for example, the return of the coolant and emulsions retained by the twisted chips back into the production cycle of the enterprise. In our opinion, at least partial extraction of a part of the coolant and emulsions from them is required, for example, with preliminary vibration treatment of twisted and other shavings on vibration equipment of various designs. In general, this method of processing aluminum shavings is characterized by a higher cost of metal obtained with the use of recycled shavings due to the use of high-cost operations of high-temperature drying, magnetic separation and crushing, can be used only in large and serial enterprises and industries.

There is a known method of remelting small waste and nonferrous alloy shavings (RF patent No. 2159822), which is implemented in various crucibles and in various melting units.

The method according to the RF patent No. 2159822 is carried out in the crucibles of the melting unit as follows. Here, a refractory flux is loaded into the crucible of the melting unit, filling the crucible by 0.2-0.25 of its working space. The flux is melted and superheated by 0.4-0.6 above its melting point. Waste to be remelted is placed above the crucible with the melt in special baskets for heating. Then the heated charge is loaded with the simultaneous imposition of vibration into the flux melt, in which it melts. As the melt accumulates, it is poured .

The method according to RF patent No. 2159822 is carried out as follows. Refractory flux is loaded into the crucible of the melting unit based on the filling of the crucible by 0.2 ... 0.25 of its working space. After complete melting and overheating of the flux at 70-150 ° C above its melting temperature, a receiving device is introduced into the melt - above the crucible with the flux melt, in special baskets, the waste to be remelted is placed for heating. The charge heated in this way is loaded in portions into the flux melt on the installed bowl. The portion size is determined experimentally depending on the rate of melting, and the loading is carried out to a level not exceeding the level of the flux mirror. The heated charge melts intensively, while the melt accumulates at the bottom of the bowl. The imposition of vibration promotes the passage of metabolic processes in the volume of the bowl and the flow of the melt in drops and jets through the flux layer. Passing through a layer of molten flux, jets and drops of a liquid alloy are cleaned of non-metallic inclusions and gases and sink to the bottom of the crucible, displacing the flux. As the flux level moves, the receiver is also raised. Undissolved attachments of refractory alloys and slag that have lingered in the bowl are removed.

As the melt accumulates in the crucible, it is poured. After draining the metal, clarifying and charging the flux, the process is repeated.

The remelting of the shavings of the AK9 aluminum alloy by the method (RF patent No. 2159822) was carried out in a resistance furnace SAT-0.15 (with a liquid metal capacity of 150 kg). When remelting, a flux was used with the composition: KCl 23-27%, NaF - 20-28%, Na ₂ CO ₃ - 8-12%, NaCl - the rest. The melting point of such a flux is T _pl = 620 ° C.

It is quite important in the method of the patent of the Russian Federation No. 2159822 and its implementation in a device for remelting small waste and shavings of nonferrous alloys, is that it provides for preliminary drying and fluxing of shavings and other small waste due to preliminary melting of the flux and placing the waste to be remelted for heating them over a crucible with melt in special baskets. However, this makes the process quite complicated, requiring special expensive devices and highly qualified experienced staff.

So the personnel servicing the furnace must load the flux into the melt in portions, the size of the portions is determined experimentally depending on the melting rate, and the load must be carried out to a level not exceeding the level of the flux mirror - otherwise, the material, for example, from an iron basket, may fall into the same remelted aluminum and break its required chemical composition in terms of iron content. This requires special mechanisms for lifting and moving the baskets above the flux level.

The heated charge melts intensively, while the melt accumulates at the bottom of the bowl. For the passage of metabolic processes in the volume of the bowl and the flow of the melt in drops and jets through the flux layer, vibration must be applied using special vibrators, which also increases the cost of the remelting process, requires their qualified maintenance

Passing through a layer of molten flux, jets and drops of a liquid alloy are cleaned of non-metallic inclusions and gases and sink to the bottom of the crucible, displacing the flux. As the level of the flux moves, the receiving device, together with the vibration mechanism, must also be periodically raised and fixed at a certain level above the mirror of the flux, which, in addition to everything, can also change from the blockage that falls on it, passing from the mesh baskets and due to the newly formed and rising from the metal its slags and captives (oxides, etc.). It is also difficult to fix and maintain these levels, in furnaces of various capacities and with various stationary and lifting crucibles, and cannot always be carried out and economically feasible, especially for furnaces with a small capacity, for example, with a capacity of up to 30 kg for molten aluminum, and with the possibility of manual transfer of metal to its casting.

Undissolved attachments of refractory alloys and slag, which are retained in the bowl, must be removed, and after draining the metal from the furnace, to repeat the smelting process, clarification and charging of the flux is required. It is also quite difficult and time-consuming to control the composition of the charged flux that meets all the requirements for obtaining high-quality metal. In many cases, this remelting method is characterized by a rather high consumption of expensive fluxes.

In addition, the prototype method does not provide for the refining of the metal from the gases dissolved in it, as well as the transition from one grade of remelting of small waste and aluminum alloy shavings to another grade of aluminum alloy. Thus, the remelting of the shavings of the AK9 aluminum alloy, according to the prototype method (RF patent No. 2159822), was carried out in a resistance furnace CAT-0.15 (with a liquid metal capacity of 150 kg). When remelting, a flux was used with the composition: KCl 23-27%, NaF - 20-28%, Na ₂ CO ₃ - 8-12%, NaCl - the rest. The melting point of such a flux is T _pl = 620 ° C. For various other aluminum alloys, for example, for melting the food grade aluminum alloy AK-12, a sufficiently effective flux of the following composition can be used: KCl - 10%; NaF - 30%; Na3AlF6 - 10%, NaCl - 50%. Controlling and charging such a changing flux for the AK-12 alloy, or another required flux, when switching to another aluminum alloy, for high-quality metal production, using this method will also be difficult and in many cases laborious and economically unprofitable.

Thus, this method according to RF patent No. 2159822 - remelting small waste and shavings of non-ferrous metals and alloys, including aluminum alloys, although it has its own original solutions, but also has many limitations and disadvantages. The method is applicable only for some metals, in stationary resistance furnaces, of sufficiently large volumes, from 150 kg (SAT-0.15) and above, the metal from which is poured, for example, by a siphon method into metal molds.

Known is a resistance melting furnace with a crucible lifting mechanism, containing a lined body with supports and a working chamber with heaters molded in its walls, as well as an extractable crucible placed inside the working chamber with a lifting (extraction) mechanism of a plug-in (removable) melting crucible of the furnace, made in the form of a cylindrical pusher, movable along the vertical axis of the furnace in the upper and lower guides, and the upper guide has a cruciform shape and is lined in the body under the working chamber of the furnace, and the lower one is made in the form of a sleeve and is fixed outside the furnace body on its bottom, and the upper end of the pusher contacts with the bottom of the crucible, and the lower one is connected with a system of hinged levers serving as a drive for axial displacements of the pusher, which we choose as a prototype (RF Patent for Useful Model No. 155320).

In special cases of the prototype furnaces (RF Patent for Utility Model No. 155320), the pusher and / or cruciform guide are made of silicon carbide, and used silicon carbide heating rods can be used as the material of the pusher and / or cross-shaped guide for ovens.

The implementation of a resistance melting furnace with a crucible lifting mechanism according to the prototype makes it possible to place a plug-in (removable) melting crucible completely in the working chamber of the furnace in the zone of operation of the heaters, according to the applicants, it allows to reduce heat losses, thereby reducing unproductive power consumption, which helps to increase the efficiency of the furnace , and the implementation of a cruciform upper guide and a cylindrical pusher made of silicon carbide contributes to an increase in the service life of these parts, since, as is known, silicon carbide has low corrosion (does not oxidize at high temperatures) and has a longer service life compared to heat-resistant steel. The use of silicon carbide heating rods of furnaces for their manufacture significantly reduces economic costs.

The ability to extend the crucible before removing it from the working chamber at the end of melting to a height exceeding the level above the roof of the furnace by the size of the "flange", its upper part should protrude from the working space of the furnace by more than 30-70 mm in height, depending on the dimensions of the crucible and, accordingly, this makes it possible to carry out the process of extracting and transferring the crucible with the melt using a mechanized technical means, for example , with the manipulator hand, which would eliminate manual labor in this operation and increase the safety of the process. On the other hand, this size of the "belt" may be insufficient for varying the methods and means of extracting and transferring the crucible with the melt, for example, by mechanizing this process, and this reduces the range of technological possibilities for servicing the furnace.

Before removing the melting crucible from the working chamber of the furnace at the end of melting, it is necessary to ensure that it is lifted over the gate of the heating furnace by an amount sufficient to securely grip the crucible with a specific technical means provided by the technology.

The prototype smelting furnace (RF Patent for Utility Model No. 155320) is positioned as cost-effective in operation and manufacture, it allows to reduce energy consumption for melting and, if necessary (with significant dimensions of the crucible), to exclude manual labor in the process of extracting and transferring the crucible with the melt, and the implementation of the prototype utility model does not require additional investment and can be carried out in the conditions of existing production, for example, by upgrading the existing resistance melting furnaces. However, the standardized range of many stationary furnaces and their crucibles in operation, for liquid metal, is determined by their capacity of 20 kg, 30 kg, 60 kg, 100 kg, 150 kg, 200 kg, 250 kg, 300 kg and more, therefore, Under the conditions of existing production, any modernization of the stationary resistance melting furnaces in operation with such capacities for liquid metal will be practically impossible and inexpedient for all economic and technological considerations and indicators.

In addition, such a prototype furnace (RF Patent for Utility Model No. 155320) has many of its own specific disadvantages.

In the prototype furnace, the crucible is installed on a working under the furnace, on which a cruciform guide is rigidly fixed, located and fixed inside the furnace, the choice of material for the manufacture of which is selected from the condition of ensuring the required service properties of this part and its economic feasibility. In special cases of execution, this guide is made of silicon carbide, which has a sufficiently high corrosion resistance, because it does not oxidize at high temperatures. The most economical option is to use silicon carbide heating rods of various heating furnaces as a material for the manufacture of a guide. The upper end of the pusher passes through this guide, which pushes the melting crucible with the metal melted in it from the working chamber of the furnace (with its lid open) to the required height above the gate of the heating chamber of the furnace, to grip it with the help of a mechanized technical means, for example, by the arm of a manipulator , by pressing the foot pedal by the operator or applying other forces located at the bottom of the furnace and equipped with lever and hinge mechanisms for transmitting forces.

Execution of prototype in furnaces (RF Patent for Useful Model No. 155320 of a pusher and / or a cruciform guide made of silicon carbide, or from used expired silicon carbide heating rods of various heating furnaces, in our opinion, is also not advisable, since this material is rather fragile , does not withstand shock loads, poorly amenable to any mechanical processing.

For the axisymmetric stroke of the pusher and vertical extraction of the crucible with molten metal from the outer, lower part of the furnace body (on the bottom of the furnace body), a guide is also provided for fastening, made in the form of a sleeve, made of the same material and the same shape as the upper guide. In this case, the lower end of the pusher is connected to a system of articulated levers that drive the axial movements of the pusher. Upon completion of the extraction of the crucible with the melt from the working chamber of the furnace, when the pressure on the pedal is released, the pusher with levers under their own weight returns to their original position.

The crucible lifting mechanism, made according to the prototype (RF Patent for Utility Model No. 155320) in the form of a cylindrical pusher movable along the vertical axis of the furnace in the upper and lower guides, the upper guide being cruciform and lined in the body under the working chamber, and the lower in the form of a sleeve and is fixed outside the body on its bottom, and at the same time the upper end of the pusher contacts the bottom of the crucible, and the lower one is connected to a system of hinged levers serving as a drive for the axial movements of the pusher, it is rather complicated, difficult to manufacture in the form of a cruciform shape of certain materials, does not contain fixing positions of various levels of extension of the crucible with molten metal from the furnace, by pressing the operator's foot pedal located at the bottom of the furnace.

For the modernization of various standard melting furnaces in operation, resistances of large capacities (from 30 kg for liquid metal and above) cannot be effective in use, even only for the reason that only in case of accidental failure of the furnace crucible (it is corroded by molten metal, burnout of the crucible, possible cracks on it, destruction of the crucible when it is securely gripped by the manipulator, etc.), all this will lead to complete failure of the furnace, since the prototype furnace does not have a system for emergency drainage of metal from the melting chamber of the furnace.

The prototype furnace is specific and is designed only to work with certain types of crucible sizes, their certain capacity (capacity) for liquid metal and dimensions. In addition, the furnace does not allow technologically and effectively using traditional methods to obtain various melted metal of the required quality, since to obtain it, it is required to melt metals using various solid coating and refining salt fluxes, to download slags and fluxes from melting crucibles, to carry out efficient processes. degassing (refining) molten metal, for example, various aluminum alloys, various salts or neutral gases. If, for example, you download slag and fluxes from the prototype melting crucibles, pushed to a certain level above the furnace roof (to the required height above the furnace heating chamber gate), by pressing the operator's foot pedal located at the bottom of the furnace, then this operator will also need an additional assistant, in their synchronized actions. With a careful download of slag, fluxes, oxides from the surface of the molten metal, the downloaded flux, slags, metal oxides and other contaminants should not fall on the outer surface of the melting crucible or get inside the furnace - into the required technological gap, between the outer wall of the furnace roof and its crucible. It takes its own time, the furnace must be turned off, the metal and the crucible itself cool down, and the furnace productivity is greatly reduced.

Standard furnace crucibles can be very different in configuration and from different materials (ceramic, chamotte-graphite, graphite, etc.). To securely grip them with the help of various mechanized technical means, various manipulators, and to safely move them to pour metal into various forms, their surfaces should not be contaminated with metals, downloadable slags and other contaminants. In addition to the conical grip (standard conical) crucibles, various manipulators and other mechanized technical means for lifting, moving and tilting crucibles when pouring metals, even for molten aluminum with a capacity of 10 - 20 kg and more, must also have reliable automatic fixation of the bottom part of the extracted melting crucible with liquid metal, especially when pouring it. This is especially important for crucibles that have already passed the first melting of metals, with partial oxidation and burnout of their surface layer. The cost of such manipulators and mechanized equipment, with adjustment of the gripping force, is quite high, which is not always economically justified and expedient.

The prototype furnace is specific and is designed only to work with certain types of crucible sizes, their specific capacity (capacity) for liquid metal, dimensions and dimensions. If the furnace crucible is not fully loaded by the mass of the melted metal, in a large crucible, there are also many difficulties, both in obtaining its high-quality metal, using various fluxes, and in conducting high-quality melting technology.

When switching to a different grade of metal smelting, expensive washing smelting is required.

When installing a crucible of other, smaller dimensions in the furnace (prototype), the gap between the heating elements of the furnace and the heated crucible with metal increases, this leads to a decrease in the overall efficiency of the furnace, increases the energy consumption for heat losses of the furnace, increases the energy consumption for heat accumulation by the furnace lining, in crucibles of small dimensions, it is more difficult to carry out the required technological operations to obtain the required quality of metal; the gripping manipulators must also be replaceable, which is generally not economically viable.

Various retractable crucibles (chamotte-graphite, graphite, some ceramic, cast iron and others) are quite expensive, and when working in an oxidizing atmosphere burn out strongly, their service life decreases, therefore they are often lined with various external (and internal) coatings, as to obtain the required quality metals, and to increase their resistance.

When the pressure on the pedal of the prototype furnace is released, the pusher with the levers under their own weight returns to their original position. Such a movement of the crucible with a possible molten metal or an empty crucible into the working chamber of the furnace for loading it is not safe, a smooth and controlled lowering of the crucible with the metal into the furnace is required, and the mechanism proposed in the prototype does not provide. Otherwise, a blow to the guide and on the furnace bottom, destruction of the crucible, failure of the furnace, emergencies, fire and other emergencies are possible.

In addition, a pusher and / or a cross-shaped guide made of silicon carbide, or from used expired silicon carbide heating rods of various heating furnaces, can also fail, since these materials are quite fragile and do not withstand any shock loads.

For the reliable operation of the prototype furnace and smooth lifting of the furnace crucible and smooth lowering of the crucible into the furnace, other rather expensive mechanisms will be required, with their automation, fixation and their qualified maintenance, which also characterizes the furnace mechanisms as ineffective and suitable only for furnaces with a small crucible volume no more than 5-10 kg for liquid metal.

The cost of various consumable retractable crucibles can be quite high, some used and broken crucibles require their disposal, require additional payment for their removal to the landfill and burial, which is also a disadvantage of such a prototype furnace.

When the crucible is completely removed from the prototype furnace, it cannot be used for other purposes, such as a resistance heating furnace for heat treatment of some, for example, asymmetrical parts. When they are placed in the furnace, lifted and removed from the furnace using the prototype mechanism, they will fall, destroy the furnace lining, its heating elements and the furnace as a whole.

In the body with the prototype furnace supports (RF Patent for Useful Model No. 155320), there is a working chamber in which the spirals - heaters are lined and the extracted furnace crucible is located. Lined furnace heating elements in the furnace lining significantly reduce the efficiency of such heaters and the furnace as a whole. Heat from the heating elements is transferred to the crucible with the molten metal by thermal conductivity, convection and a significant part by radiation. So, even if the heating elements of the furnace are located in the U-shaped groove of the lined furnace chamber, then the transfer of heat by radiation from the heating coil to the metal crucible is carried out only through the open space of the groove, and the rest of the heat goes to warming up the furnace masonry and accumulating heat by it, until the work is released the furnace to a stationary stable mode of operation and an exit to stable heat losses from its side. The same transfer of heat by thermal conductivity through the air gap from the heating elements to the furnace crucible wall will be much less than the heat going to heating the lining itself, on which the heating elements lie (in contact). Convective heat exchange, from the heating elements to the crucible from the lined U-shaped part, will be very small. Therefore, such a prototype furnace requires a minimum gap between the lined spiral (heating element) and the outer wall of the crucible, and this, as noted above, has many other technological disadvantages of such a furnace, for high-quality production of molten metal.

The prototype furnace also has poor maintainability in the event of burnout of its heating elements molded into the lining. Repairing them and putting them back into the furnace will take a lot of time and additional costs, including for lining materials.

In the prototype furnaces (RF Patent for Useful Model No. 155320), it is difficult to remelt various chips from various non-ferrous metals and alloys, for example, various (twisted, chipped, drain and other) aluminum chips contaminated with various cutting fluids (coolant) , emulsions and other aqueous technological media.

For remelting, for example, such various aluminum shavings in the prototype furnace, its preliminary expensive preparation will be required, which requires a lot of additional equipment and the process of its preparation for remelting, and the remelting process itself in a furnace with a removable lifting crucible will also be difficult, it becomes a lot of hardware and even more costly.

Unlike the prototype (RF Patent for Utility Model No. 155320), our proposed "Multifunctional laboratory electric resistance furnace", containing its plug-in (removable) melting and casting crucibles, allows simple, cheap and fairly effective and affordable means to eliminate many of the disadvantages of the prototype , significantly expand the technological capabilities of the furnace with its plug-in (removable) melting and pouring crucibles, which allow melting and casting not only aluminum ingots and lump aluminum, with a capacity of up to 30 kg for liquid aluminum, but also its effective melting of various (twisted, split, drain and other) dry aluminum shavings, as well as shavings contaminated with various cutting fluids (coolant), emulsions and other aqueous technological media, will allow for effective melting and casting of various other non-ferrous metals and alloys, to carry out various types of heat treatment of various ferrous and non-ferrous parts with working temperature up to + 1200 ° С.

In our proposed utility model "Multifunctional laboratory electric resistance furnace", some similar effective processes associated with drying and fluxing of shavings according to RF patent No. crucible, in a much simpler, technologically advanced, rather reliable and cheap design.

The task of the utility model is to create a highly efficient, versatile, inexpensive, reliable and easy-to-maintain multifunctional laboratory electric resistance furnace for melting and casting various aluminum alloys and their various shavings, including dry shavings and shavings contaminated with various coolants, emulsions, and detergents. and other aqueous media, carrying out in it various methods of heat treatment of parts made of ferrous and non-ferrous metals and alloys, drying various materials and paint coatings in it, intended for various industries, research institutes, universities, technical schools, various small enterprises, repair shops ...

The technical result of the claimed utility model is to expand the technological capabilities of stationary laboratory resistance melting furnaces, to increase their reliability, to simplify furnace maintenance, to simplify and reduce the cost of high-quality and efficient remelting processes in the same furnace of various aluminum alloys with a liquid aluminum capacity of up to 30 kg, including their various (twisted, chipped, drain and other) dry shavings and shavings contaminated with various cutting fluids (coolant), emulsions, detergents and other aqueous technological media, with the possibility of remelting and casting various other non-ferrous metals and alloys; with the possibility of carrying out in it various types of heat treatment of metals from ferrous and non-ferrous metals with an operating temperature of the furnace up to 1250 ° C; carrying out in it the processes of drying various materials (for example, the same wet chipped, chopped shavings, shavings from power saws and other thin-walled aluminum waste), drying various paints and varnishes on parts and for various other purposes.

Such a possibility of multifunctionality of a laboratory electric resistance furnace is due to the possibilities of using in it a replaceable, plug-in (removable) melting and pouring crucible made of stainless material with handles for installing it into the furnace, removing it from the furnace with molten metal, moving it and pouring metal into the required shapes, on which a plug-in (removable) conical nozzle can be installed, in which the processes of drying of twisted chips, drying of possible mixtures of twisted, chipped, drainage and chopped chips, in which processes of fluxing of various chips take place, to reduce its waste, and from which feeds the chips into the melting crucible for remelting.

The essence of the claimed utility model as a technical solution is expressed in the following set of essential features sufficient to achieve the above technical result.

Multifunctional laboratory electric resistance melting furnace containing a lined body with supports, a working chamber with heating elements and an extractable crucible located inside the working chamber, characterized in that the extractable, plug-in (removable) melting and pouring crucible is made of stainless metal, with welded handles allowing install the crucible axisymmetrically in the furnace along the guides in the window of the furnace roof, and on which a plug-in (removable) cone-shaped nozzle is installed for drying and fluxing aluminum chips fed into the crucible on the surface of the molten flux and into the molten metal under the flux layer, and installed under the furnace hearth supports pallet, for emergency exit of metal from the working chamber of the furnace, in case of emergency burnout of the walls of the melting and pouring crucible.

In a particular case, a plug-in (removable) melting and pouring crucible with a capacity of 30 kg for liquid aluminum alloy AK12 is made of a welded standard pipe billet with an outer diameter of 2019 mm, from stainless steel grade 10X18H10T, with a wall thickness of up to 10 mm.

The applicant has not identified sources containing information on technical solutions, the set of features of which coincide with the set of distinctive features of the claimed utility model, which allows us to conclude that it meets the “novelty” condition.

The essence of the utility model is illustrated in the presented drawings: Fig. 1 shows a general diagram of the base, stationary part of a multifunctional laboratory electric furnace for melting various aluminum alloys and other non-ferrous metals and alloys; in fig. 2 section A-A; in fig. 3 section B-B; in fig. 4 is a general diagram of the basic, stationary part of a multifunctional laboratory electric furnace with a cone-shaped nozzle installed on a melting and casting crucible for highly efficient remelting of various aluminum chips.

Here: 1 - metal body of the furnace with supports; 2 - multilayer furnace lining; 3- spiral heating elements laid on refractory shelves; 4 - plug-in (removable) melting and pouring crucible; 5 - welded handles for removing and installing the crucible in the furnace; 6- furnace crucible cover; 7 - limit switch (protection against electricity when removing the crucible); 8 - molten flux; 9 - molten metal; 10 - hole for draining molten metal in case of burning out of the crucible; 11 - pan for emergency metal release from the furnace when the furnace melting and pouring crucible burns out; 12 - furnace thermocouple; 13 - plug-in (removable) cone-shaped nozzle; 14 - aluminum shavings (twisted, chipped, chopped, including those containing coolant and water emulsions).

FIG. 1 shows a diagram of the basic, stationary part of a multifunctional laboratory electric furnace for melting various aluminum alloys and others, non-ferrous metals and alloys, their ingots and lump scrap. Inside the metal body 1 of the furnace with supports, there is a multilayer lining 2 containing heat-insulating and refractory layers. Heating elements 3 are made in the form of spirals (Fig. 1, Fig. 3), made of nichrome wire of the X20H80 type, with a diameter of 4-5 mm and they are located on refractory shelves. Unlike the overmolded heating elements of the prototype furnace, this makes the multifunctional furnace more efficient in transferring heat from the heating elements to the heated crucible by radiation, convection, and heat transfer. In addition, such a furnace has a high maintainability, if it is necessary to repair or replace the furnace heaters.

The placement of heating elements on refractory shelves also increases the maintainability of the furnace, does not require a large consumption of lining materials, does not require any disassembly of the inner refractory layer of the furnace to remove, repair or replace the heating elements of the furnace, does not require a large consumption of lining materials, reduces repair time and stove downtime.

The plug-in (removable) melting and pouring crucible 4 of the furnace is made welded (Fig. 1, Fig. 2), for example, from a standard pipe billet with an outer diameter of 219 mm, a wall thickness of up to 10 mm, from a heat-resistant, heat-resistant stainless material, for example , brand 10X18H10T. Such material is sufficiently resistant to melts of various aluminum alloys and to their required fluxes. A crucible of this size and height up to 400 mm, equipped with a sock (figure 2), for draining metal, on a liquid aluminum alloy, can have a volume of up to 30 kg.

The melting and pouring crucible 4 has welded handles 5 (Fig. 1, Fig. 2, Fig. 4), for installing and removing it with molten metal. Its removal from the furnace and safe transfer to the place of metal casting into molds (Fig. 2) can be done manually by 2 workers - a smelter and a caster, or his assistant - a molder and other personnel.

The maximum weight of a casting of such a melting and pouring crucible can be up to 30 kg for liquid aluminum alloy, this makes it possible to use the furnace in various industries, in educational processes of technical schools, universities, research institutes engaged in training personnel in casting and processing of various metals, developing new alloys, development of technologies for obtaining new products, consumer goods and in repair shops.

In addition, in such crucibles, it is also possible to melt and cast various other non-ferrous metals and alloys (babita, various zinc (for example, TsAM alloys), tin, lead, copper and other alloys), which also makes the furnace versatile and multifunctional. Restriction on the mass of other metal smelted and safe transfer of crucibles to the place of metal spill by two workers is limited to a total weight of up to 50 kg. However, it must be borne in mind that the working volume and dimensions of the melting and pouring crucible make it possible to draw metal from it and pouring ladles into the capacity, which also expands and facilitates the casting of various small-sized parts from various non-ferrous metals and alloys, and also reduces the total weight crucible with molten metal, for its safe transfer to the place of metal spill by two workers.

The plug-in (removable) melting and casting crucible 4 of the furnace has its own lid 5. The lined lid 6, has its own handle, is easily installed and removed from the crucible, allows loading into the crucible various lumpy aluminum ingots, secondary lumpy aluminum, solid small aluminum waste in in the form of chopped or chopped shavings, pour the required amount of various protective (coating) and refining fluxes onto the surface of the molten metal, reduces heat losses from the upper part of the melting and pouring crucible, reduces air access to the metal heating and melting zone, thereby reducing metal oxidation and evaporation slag from the crucible melting zone.

The gap between the outer wall of the plug-in (removable) melting and casting crucible and the upper window of the furnace roof (Fig. 1, Fig. 4) is provided for rather small, up to 5-10 mm. If necessary, this gap can be closed with heat-insulating linings, for example, made of asbestos sheet or asbestos cord. The upper part of the furnace roof with its window is made of metal and allows the crucible to be installed axisymmetrically in the furnace along the guides in the furnace roof window.

The melting and pouring crucible 4 of the furnace is installed and removed from the furnace in its off state. To protect the furnace operating personnel from any electric shock, for example, if the melting and casting crucible is accidentally removed from the furnace connected to the network, a limit switch 7 is provided on the furnace roof, the disconnecting contact of which rests on the welded handle, when raised, the furnace automatically turns off from the mains. The same limit switch can also fix the axisymmetric installation of the crucible inside the furnace.

As the process flux 8 and metal 9 melt in the furnace crucible, with its cover 6 open, the required metal addition can be easily introduced into the crucible, the resulting slag can be loaded, the required refining and modifying additives can be added, the molten metal is degassed before pouring it, using special and enough traditional tools and devices. It is not required to disconnect the furnace from the mains, the metal and the crucible do not cool down, the furnace can remain in operation in the thermostatic mode. In contrast to the prototype, this makes it possible to significantly increase the furnace productivity, reduce power consumption, improve working safety conditions, obtain high-quality metal and high-quality casting from it of various required parts and products.

For before loading into the crucible a few preheated lumpy scrap, which is also sometimes important and technological, it can be partially located on the upper part of the furnace roof (around the furnace), on its metal casing, without covering or overlapping the welded handles 5 of the insertable (removable) melting and pouring crucible 4, fig. 2 (we do not show heated lump scrap in the diagram). Heating of lumpy scrap and ingots on the roof of the furnace can ensure their drying, and also somewhat reduces the required energy consumption.

To protect the furnace from liquid metal in case of accidental or emergency consumption of the crucible material by the molten metal or even at the initial stage of partial destruction of the working crucible, a hole 10 is provided on the lined hearth of the furnace for automatic discharge (discharge) of the molten metal from the furnace into the tray 11 located under the hearth of the furnace and its supports (Fig. 1, Fig. 4). The furnace bottom lined with refractory and heat-insulating materials is tapered (Fig. 1, Fig. 4), the diameter of the hole for the emergency release of metal from the furnace does not exceed 15 mm, the heat loss from it is insignificant, to the bottom of the pallet 11, emergency release of metal from the furnace during burnout melting and pouring crucible of the furnace, quite simple and cheap and contact alarm sensors can be installed, the pallet can be lined with thermal insulation materials, sheet asbestos and other materials.

The required temperature in the furnace for melting various non-ferrous metals and alloys is regulated, measured and maintained within the specified limits by the thermocouple 12 (Fig. 2). The operating temperature of the furnace with crucibles made of such materials and heating elements can be regulated and maintained by a thermocouple and its devices over a wide range, with a maximum temperature in the furnace equal to + 1250 ° C ± 5 ° C. A platinum-platinum-rhodium thermocouple 12 is used as a temperature sensor.

To measure the temperature of the molten metal in the melting and pouring crucible 4, with its cover 6 open, the required immersion thermocouple with its potentiometer can be easily inserted. To determine the readiness and overheating of various, for example, aluminum alloys to the required temperature of their pouring into molds, a chromel-alumelium thermocouple (TCA) of various designs and measurement accuracy can be used. This allows you to quickly and quickly obtain the required parameters of the liquid metal for high-quality production of the required castings.

A significant advantage of using such melting and pouring crucibles is that after melting and casting one grade of metal, it is easily cleaned of the remnants of molten metal and, without thorough washing melts, can be used for melting and casting various other metals and alloys. The use of 2 or 3 such crucibles of the same type expands the capabilities of the melting furnace for melting various other metals and alloys in it without the required washing melting.

To obtain high-quality various aluminum alloys, various other non-ferrous metals and alloys, to prevent their contamination by the crucible material, to increase the wear resistance of melting and pouring crucibles, various protective coatings of their inner and outer surfaces can also be used.

Waste or worn-out melting and pouring crucibles made of stainless metal are easily cleaned of metal residues (for example, from various aluminum alloys) and they can be handed over to non-ferrous metal collection points as clean, non-clogged secondary metals, receiving a high payment for the delivered scrap, thereby reducing the cost of the required crucibles and the reduction of the cost of smelting and casting various parts and products.

FIG. 4 shows a significant expansion of the technological capabilities of the base, stationary part of the multifunctional laboratory electric resistance furnace (Fig. 1) with its plug-in (removable) melting and pouring crucibles, which allow melting and casting not only aluminum ingots and lump aluminum, but also performing efficient melting and various (twisted, chipped, drainage and other) aluminum dry shavings, as well as shavings contaminated with various cutting fluids (coolant), emulsions and other aqueous technological media, in the form of the required amount of metal in the crucible before loading the furnace to the required capacity , as well as as an independent melting furnace for the production of high quality secondary aluminum alloys (ingots) for their further use as charge materials.

For these purposes, in the base, stationary part of a multifunctional laboratory electric furnace (Fig. 1), its cover 6 is removed from the melting and pouring crucible of the furnace 4, and instead of it, a plug-in (removable) cone-shaped nozzle 13 is installed on the melting and pouring crucible 4, in which is loaded, for example, twisted aluminum shavings, or a mixture of twisted, drain and other forms of shavings 14, requiring its rational and resource-saving remelting.

The loading of various shavings into the cone-shaped nozzle must be such that it is gas-permeable for the heat coming from the molten metal 9 and the flux 8, which is in the melting crucible 4 (Fig. 4) from its open upper part.

Such drying of possibly wet (wet) chips and their fluxing (with evaporating fluxes and exhaust gases from the melting space of the crucible of the furnace, allows you to save heat passing through the cover 6 during the usual melting of solid lump materials into the surrounding space, as heat irrecoverable losses of the base furnace (Fig. 1), and the deposition on the surfaces of the chips of the evaporating flux 8, with subsequent mechanical (manual) pushing it into the crucible, onto the surface of the molten flux and into the layer of molten metal under the molten flux, will significantly reduce its oxidation and waste.

As fluxes 8, their various working coating and refining fluxes can be used, including, for example, for the AK9 aluminum alloy, of a known composition: KCl 23-27%, NaF - 20-28%, Na ₂ CO ₃ - 8 -12%, NaCl - the rest, having a melting point T _pl = 620 ° C, but with an increased content of the low-melting component KCl, up to 27%.

Strongly wet aluminum shavings, for example, twisted and other shavings with a high content of coolant and emulsions, can be preliminarily subjected to vibration processing, for example, on an inexpensive vibrating table, to extract coolant and emulsions from it, in order to regenerate them and return them back to production, and the shavings with residual moisture to direct it for drying and fluxing into the cone-shaped nozzle 13 of the furnace (Fig. 4), for its further remelting.

The use of a cone-shaped nozzle for drying various wet chips and their fluxing, followed by mechanical (manual) pushing it into the melting space of the crucible on the surface of the molten flux and into the layer of molten metal under the molten flux, allows a simple and cheap method to reduce oxidation and waste of various chips by 15 -25% of her net weight. This makes it possible to rational and resource-saving use of a multifunctional laboratory electric resistance furnace for use in various small enterprises, in various repair shops, and for other enterprises with a small volume of high-quality castings produced - up to 3.0 tons per month.

Thus, in the proposed multifunctional laboratory electric resistance furnace, it is possible to melt not only the lumpy composition of aluminum alloys, but also their various shavings, rather simply and effectively.

Above the cone-shaped nozzle 13, as well as over the entire base, stationary part of the multifunctional laboratory electric furnace (Fig. 1), according to the conditions of their safe operation, as well as for various other melting furnaces, exhaust ventilation must be installed. Most often, for these purposes, a simple umbrella is used with an exhaust ventilation connected to it, which does not interfere with the removal of the melting and pouring crucibles from the furnace, the installation and removal of the cone-shaped nozzle.

When removing the melting and pouring crucible 4 from the base stationary part of the multifunctional laboratory electric furnace (Fig. 1), the working space of the furnace can be used to carry out various other technological processes in it. So, in it, it is also simple and reliable to carry out various types of heat treatment of parts of various configurations, to carry out: heating of various parts for hardening; carry out low-temperature and high-temperature tempering of various parts in the furnace; anneal parts and workpieces made of various ferrous and non-ferrous metals; carry out various other required heat treatment processes with furnace operating temperatures up to 1250 ° C; to carry out in it the processes of drying various paints and varnishes on parts and for various other purposes.

When heated for heat treatment of various small parts, they can be fixed on special devices of the “herringbone” type and also easily and easily loaded (and unloaded) into the working space of the furnace through its upper window of the furnace roof. In this case, the cover 6 (Fig. 1) of the melting and pouring crucible can also be used as the cover of the most multifunctional laboratory electric resistance furnace - using it to carry out various required heat treatment processes of various parts and products in the furnace. It also expands the technological capabilities of the furnace, making it more versatile and multifunctional.

To reduce heat losses from the outer surfaces of the furnace, its metal casing and cone-shaped nozzle are painted with heat-resistant light or white paint, for example, silver paint, which reduces heat loss of heat into the surrounding space and makes the furnace more economical.

The oven works as follows. The required external inspection of the furnace, its readiness for connection to the mains and the availability of the required auxiliary tools on the site is carried out. The melting and casting crucible 4 prepared for melting is symmetrically installed by two workers in the melting chamber of the furnace, while its handle must close the contact of the limit switch 7. The melting and casting crucible is manually loaded, for example, with lumpy scrap and ingots of the required aluminum alloy. The required amount of protective and refining flux is poured onto the loading surface. The melting and pouring crucible 4 is closed with a cover 6. The furnace exhaust ventilation is switched on, the furnace is energized. Temperature control in the oven chamber is controlled by the readings of the device connected to the thermocouple 12.

As the metal 9 melts in the crucible, slags are formed on the surface of the flux 8, which can be removed manually using a special hand tool. It is not necessary to disconnect the oven from the mains.

If necessary, preheated lump metal or scrap of the same metal grade, taken, for example, from the furnace roof, can be added to the crucible. Cold lumpy scrap, before being immersed in the melting crucible, can be heated over the molten slag bath or molten flux using special tongs.

As soon as the metal is ready, slag and spent flux 8 are downloaded from it (Fig. 4), it is degassed (refined), for example, with zinc chloride using a "bell", or by blowing with inert gases. Using a hand tool, we collect floating contaminants and captivity (oxide films of aluminum alloy) from the metal surface. In this case, the oven can remain switched on and operate in thermostatic mode.

Using an immersion thermocouple, we determine the correspondence of the temperature of the molten metal to its required overheating temperature for pouring it into the mold.

In general, the technological process of metal melting here is not much different from the same standard technological processes of metal melting in various standard electric furnaces with their fixed or rotary crucibles.

When the metal is ready, the furnace is disconnected from the network and two workers carefully remove the melting and pouring crucible from the furnace, transfer it to the place where the metal is poured into the mold, set it on the casting pedestal and carefully tilt the crucible to drain the metal from the crucible, through its nose into the mold, maximum which weight for metal is up to 30 kg.

Metal from the melting and pouring crucible, for casting small castings by weight, from the melting and pouring crucible can be scooped out and carried by hand for pouring it and using various ladles with their own welded handles.

After draining the metal, the heated crucible is returned and installed back into the furnace for loading and subsequent melting. Leaving the "swamp" - up to 10% of liquid metal in the crucible, significantly reduces the time of subsequent melting of the metal, in the same, but already heated furnace, up to 25% in time.

For the rational melting of various dry and wet aluminum shavings, a cone-shaped nozzle 13 is used. For example, twisted aluminum shavings, or a mixture of twisted, drainage and other forms of shavings 14, requiring its rational and resource-saving remelting, are placed in it.

The loading of various shavings into the cone-shaped nozzle must be such that it is gas-permeable for the heat coming from the molten metal 9 and the flux 8, which is in the melting crucible 4 (Fig. 4) from its open upper part.

Therefore, at the bottom of the cone-shaped nozzle, it is recommended to lay twisted shavings, and then a mixture of twisted shavings, drain and chipped shavings, it is possible to alternate them in layers so that it is gas-permeable, for the heat coming from the molten metal 9 and flux 8. As fluxes 8, can be used in different required working coating and refining fluxes.

The cone-shaped nozzle 13, together with the gas-permeable shavings placed in it, can be installed on a pre-loaded cold melting and pouring crucible with cold lumpy remeltable aluminum and flux placed in it, and in this state the furnace can be switched on from a cold state. Above the furnace, with a loaded cone nozzle, the exhaust ventilation is switched on. As the metal 9 and flux 8 melt (Fig. 4), the chips are dried and fluxed.

The progress of the drying process of wet chips and their fluxing are observed visually on the upper part of the box as the removal of moisture (steam) and burning, and at the level of the exhaust ventilation hood. In the presence of various cutting fluids and emulsions on the surface of the chips (containing various oils, petroleum products and various additives (anti-corrosion, antifoam, antibacterial, stabilizing and others)), they also burn out and evaporate.

Drying, burnout of oils and petroleum products of some cutting fluids and emulsions (the flash point of some oils and petroleum products is in the range of 140-160 ° C), occurs with some smoke emission, however, the combustion of oils and petroleum products and their transition to soot (carbon) does not strongly affect on the deterioration of the quality of the smelted metal. Burnout oils and other petroleum products remaining in the form of soot on the surface of the shavings additionally further protect it from strong oxidation and burnout of the metal of the shavings at high temperatures and when it is pushed onto the surface of the slag melt or into a layer of molten metal, under a layer of flux.

Burnt carbon-containing materials, when melted on the surface of the slag, easily pass into slag, and the metal, passing through the slag layer, is purified to its high purity.

When manually pushing the dried and fluxed shavings onto the surface of the metal bath, under the slag layer, it melts just as effectively with a decrease in its waste and oxidation. Processing with a refining flux occurs at the interface between a liquid metal bath of molten metal and a molten refining flux.

Thus, after the end of the observed processes of moisture evaporation and smoke formation, on the upper part of the cone-shaped nozzle, after a short exposure of the chips in the cone-shaped nozzle, it is manually pushed into the melting crucible. This makes it possible to effectively introduce an additive into the molten metal to replenish its total melt volume up to 10-15% or more, without disturbing the composition and quality of the resulting metal.

It is also possible to re-insert into the melting and pouring crucible, already with molten metal and flux, a new cone-shaped nozzle, with a new portion of moist chips placed in it, and the process is repeated. The drying time and fluxing of the chips, as well as their melting, are significantly reduced.

When melting, or leaving the molten metal in the crucible in the form of a "swamp" equal to 10% of the total volume of the crucible, and adding to it a slightly larger volume of the required refining flux, thus it is possible to remelt the chips to its full volume in the crucible - up to 30 kg for liquid aluminum, to obtain high quality secondary aluminum alloys (ingots) for their further use as charge materials.

The choice of one or another mode of operation of the furnace is determined by the task facing it: melting and casting a lump llama; smelting and casting of lumpy scrap with additional loading of casting with various remelted aluminum shavings; melting and casting of various shavings to obtain an aluminum alloy for charge purposes; and other purposes of obtaining new materials.

At the end of the melting of the shavings, the cone-shaped nozzle 13 is removed from the melting and pouring crucible, slag and spent flux 8 are downloaded from it (Fig. 4), it is degassed (refined), for example, with zinc chloride using a “bell”, or by inert blowing gases. We use hand tools to collect floating contaminants from the metal surface, including captivity (oxide films of aluminum alloy) and possible carbon contaminants. In this case, the oven can also remain switched on and operate in thermostatic mode.

Using an immersion thermocouple, we determine the correspondence of the temperature of the molten metal to its required overheating temperature for pouring it into the mold.

When the metal is ready, the furnace is disconnected from the network and two workers carefully remove the melting and pouring crucible from the furnace, transfer it to the place where the metal is poured into the mold, set it on the casting pedestal, and carefully tilt the crucible to drain the metal from the crucible, through its nose into the required forms, the maximum weight of which for metal is up to 30 kg.

When dry shavings are loaded into a cone-shaped nozzle, the processes of their fluxing and remelting into high-quality metal are shortened in duration, and the yield increases.

The total drying time and fluxing of various shavings is determined empirically, depends on the composition and amount of their contaminants (various coolants, emulsions, various washing solutions and other aqueous media. Practice and operating experience of such a device, in terms of flux consumption, sludge yield, presence of oxidized part slip metal (captivity), allows a more complete, rational and efficient remelting in a furnace of various aluminum shavings and shavings from various other non-ferrous metals and alloys.

The results of experimental melting on a multifunctional laboratory electric resistance furnace of AK 12 aluminum alloy, and its various chips contaminated with various coolants and emulsions, confirm that it allows obtaining high-quality metal that meets all the requirements for obtaining high-quality castings with the lowest cost, a simple and affordable device. ...

The possibility of industrial application of the claimed technical solution is beyond doubt, since the proposed furnace (installation) can be manufactured industrially from many well-known materials using known technologies and technical means (sheet iron, angle iron, bar, stainless steel pipes, refractory and heat-insulating furnace materials, refractory shelves, refractory binders, nichrome wire, cutting, welding, thermocouple, etc.), which determines, in the applicant's opinion, its compliance with the "industrial applicability" condition.

The use of the claimed solution in comparison with all known means of a similar purpose provides the possibility of obtaining a universal, multifunctional, inexpensive, reliable, convenient and economical to operate multifunctional laboratory electric resistance furnace, which provides: melting and casting of various aluminum alloys, with a capacity of liquid aluminum up to 30 kg ; melting and casting of various aluminum shavings, including dry shavings and shavings contaminated with various cutting fluids (coolant), emulsions, detergents and other aqueous technological media, with a reduction in oxidation and waste of various shavings up to 15-25% of its pure weight; providing remelting and casting in it of various other non-ferrous metals and alloys; providing various types of heat treatment of various parts made of ferrous and non-ferrous metals with an operating temperature inside the furnace up to + 1250 ° C; and for various other purposes.

Claims (2)

1. Multifunctional laboratory electric resistance furnace for melting non-ferrous metal shavings, containing a lined body with supports, a working chamber with heating elements and an extractable crucible located inside the working chamber, a limit switch for connecting to the mains, characterized in that it is equipped with guides placed in a window made in the furnace roof, a removable cone-shaped nozzle for drying and fluxing chips installed on the crucible, and a pan for an emergency exit of metal from the working chamber of the furnace, installed under the furnace hearth supports, while the removed crucible is made in the form of a replaceable welded stainless steel melting - a casting crucible with welded handles to ensure an axisymmetric installation of the crucible in the furnace along the said guides. 2. Resistance furnace according to claim 1, characterized in that one of the handles of the replaceable melting and pouring crucible is made with the possibility of placing in its working position on the contact of the limit switch to prevent the removal of the replaceable melting and pouring crucible from the furnace without first disconnecting the furnace from the supply network ...

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