Manual arc cutting of metal of various thicknesses. Hyillotine shock cutting
Hand.backed metal cutting of metal: features, methods and technological process of work
Metal cutting is a process of separating a metal sheet or pipe into several parts by a manual, mechanical, thermal method. The Cherepovets Metal structures factory uses this process in the production of various products, so that experts can explain in detail all the features. The answer to the question of how to cut metal is, in the context of the modern development of industrial technologies, it turns out to be quite multifaceted. Since they also cut metal for household and repair purposes, the question is relevant for many people.
Oxygen cutting consists in combustion of the cut metal in an oxygen stream and the removal of this stream of resulting oxides.
The cut metal is previously heated by the heating flame of the cutter, which is formed as a result of combustion of combustible gas (acetylene, propane) in a mixture with oxygen. Upon reaching the ignition temperature of the metal in oxygen, a valve of pure oxygen (99–99.8%) is opened on the cutter under a pressure of up to 12 bar and the cutting process begins. Pure oxygen from the central channel of the mouthpiece designed to oxidize the cut metal and remove oxides, is called the cutting, unlike oxygen of the heating flame entering the mixture with combustible gas from the side channels of the mouthpiece.
A stream of cutting oxygen displaces molten oxides into an incision, they, in turn, heat the next layer of metal, which contributes to its intensive oxidation. As a result, the cut sheet is subject to oxidation throughout the thickness, and molten oxides are removed from the cutting zone under the influence of a jet of cutting oxygen.
The process of oxygen cutting begins with the fact that the surface of the cut leaf should be cleaned of scale, paints, oils, rust and dirt. Particular attention is paid to cleaning the surface of the leaf from scale, since it prevents the contact of the metal with the flame and stream of cutting oxygen. To do this, it is necessary to warm the surface of the steel with a heating flame of the cutter, as a result of which, scale will bounce off the surface. Heated should be performed by a narrow strip along the proposed cutting line, moving the flame at a speed of approximately corresponding cutting speed.
Before the oxygen, the metal is heated from the surface at the starting point of the cut to the temperature of its ignition in oxygen. After starting the jet of cutting oxygen and the beginning of the process of the oxidation of the metal along the thickness of the sheet, the cutter is moved along the cutting line.
As a rule, straight oxygen cutting of steel sheets up to 50 mm thick is performed first with the installation of the cutting nozzle of the mouthpiece in a vertical position, and then with an inclination in the direction opposite to the direction of cutting (usually at 20-30º). The tilt of the cutting nozzle of the mouthpiece to the side accelerates the process of oxidation of the metal and increases the speed of oxygen cutting, and, consequently, its performance. With a larger thickness of the steel sheet, the cutter at the beginning of the cutting is tilted to 5º to the side, the reverse movement of the cutting.
During oxygen cutting, equipment such as cutters, hoses, cylinder regulator, gas cylinders in combination with gas ramp or gasifier or gasifier are used.
This type of metal processing was designed for materials that are poorly lending to oxygen cutting. Such materials are cast iron, alloy steels, non.ferrous metals, etc. Oxygen-fluvial cutting differs from ordinary oxygen cutting only in that in addition to the heating flame and jet of cutting oxygen, flux powder is fed into the cutting zone, which provides the cutting process due to the thermal, chemical and abrasive effects.
Technology and technique during oxygen-fluisan cutting do not differ from ordinary oxygen cutting, with the exception of the nuances below.
When oxygen-fluid cutting into an oxygen cutting stream, powdered fluxes are additionally introduced, the particles of which, burning, give a significant thermal effect, contributing to the melting of refractory oxygles on the surface of oxygen contact with the processed metal without significant melting of the edges of the metal under this surface layer. The basis of such powdered flux is iron powder.
In the process of combustion of flux, high.and.bended FEO particles form, which contribute to the formation of complex more all.melting connections (FEO.SIO2; Feo.CR2O3 and others.) and facilitate oxygen access to non.oxidized parts of the metal due to the removal of refractory oxides.
Thus, in addition to the processes of the oxidation of the metal and blowing molten slag during ordinary oxygen cutting, during oxygen-fluine cutting there is an intensification of temperature in the reaction space as a result of the burning of flux powder (iron, ferrophosphorus, aluminum), accompanied removal (scale, quartz sand, clay). Oxygen-fluvial cutting is used both as dividing and as a superficial.
During oxygen-fluid cutting, equipment such as capacities for flux (floweringer), cutters, hoses, cylinder regulator, gas cylinders in combination with gas ramp or gasifier or gasifier is used.
Cutting with electrodes: pros and cons of
Each of the methods of processing materials using electrodes is characterized by its own advantages and disadvantages.
Advantages of cutting:
- the convenience and simplicity of the process even for a novice artist who does not have special qualifications;
- No specialized equipment is required;
- process security for the contractor.
- The speed of cutting depends on the thickness of the processed metal;
- With an increase in thickness, the speed decreases significantly;
- poor quality of the resulting cut, it is distinguished by irregularities and leakage;
- Low performance.
Description of technology
At the beginning of work (both before welding and in front of a strip), preparation is always carried out. It includes stripping the welding area of the surface of the part. The strip is carried out with sandpaper, a grinding machine or file.
All foci of corrosion, inclusion of foreign materials, pollution, unevenness are removed. After that, the surface is treated with degreasing liquid. The quality of the welding connection will depend on the quality of the stripping.
The current level of current is set depending on the diameter of the electrode. With a size of 4 mm, the current strength should reach 150-200 amperes. If the size of the rod is larger. the current strength increases, if less, decreases.
For stability of the work of arcs, it is worth setting up a constant type of current. The polarity is established negative. It will also lower the consumption of the material.
To improve the density of the seam and stabilize the arc with strip and welding, flux is used. They exist several types: powder, pasta, liquid. Anyone can be used, however, the shape of the pasta or liquid is more suitable for use at home.
For the best effect, the flux should include ionizing substances. The flux itself is applied to the welding surface and distributed by a thin uniform layer.
Next, the filler element is inserted into the holder, the arc is fired and the welding bath is formed. The arcs are ignited by tapping (stir) the tip of the working element on the metal surface.
During operation, the visible part of the filler element should not exceed 7 cm. Promotion along the joint should be uniform, taking into account the melting of the edges and the formation of the compound.
Welding of parts, as well as a string to be used by a coal electrode at home, however, for this you need to use factory production equipment. Homemade units for such welding are not suitable due to the lack of the possibility of setting up current strength.
Oxygen-duging stimulating low-carbon steel steel electrodes as follows:
Oxygen-duging cutting is used in construction and installation work, repair, and in other cases when you have to perform short cuts (up to 500 mm), combined with arc welding. To move from welding to cutting, the welder does not need to change the electrod holder, electrode and mode. Can be used both alternating and direct current.
With mechanized oxygen-dug cutting, it is more rational to use carbon electrodes, direct current and cutting of the corresponding structure.
Air-anteum cutting is based on the melting of the metal at the cutting site of the heat of an electric arc burning between the coal or graphite electrode and metal, with the continuous removal of liquid metal with a stream of compressed air. This method is used for dividing and surface cutting.
Air-air cutting by a carbon electrode can be effectively used when cutting off casting profits, cutting the edges for welding, removing defective places of welds, captivity and non-metallic inclusions, especially when processing highly alloyed heat-resistant and stainless steels. The disadvantage of this method is to scrap the surface layer of metal at the cut edges, a high specific electricity consumption, high idle voltage, which creates danger when changing the electrode, as well as the high cost of direct current power supply.
Cars for an airborne cutting according to GOST 10796-64 should meet the following characteristic:
In Fig. 116, and the universal cutting of the RVD-4A-66 is shown for manual surface and dividing cutting of low-carbon and stainless steel thickness up to 20 mm of VNIIAVTOGENMASH structure.
The cutter has a handle with a lever valve for supplying compressed air. A coal or graphite electrode is engaged between the lips. In the contact-main part of the cutting of the slope of the cheek, the openings through which the compressed air enters, which is supplied to the cutter under a pressure of 5-6 kgf/cm 2 along the hose.
The jets of air blow molten metal from the cut.
The position of the cutter during dividing and surface cutting is shown in the rice. 116, b, in IG. The distance from the sponges to the lower end (departure) of the electrode should not exceed 100 mm. As the electrode is burned, it is pulled out of the lips down. The width of the groove during cutting exceeds the diameter of the electrode by 1-3 mm. The surface of the metal at the site of the cut is flat and smooth.
For mechanized airborne surface cutting, a semiautomatic device PVD-2-67 of VNIIAVTOGENMASH structures is used. The following operations are performed by this automatic: cutting sheets for welding; melting defective sections of the seams on a flat and cylindrical or spherical surface; smelting the root of the weld from the back; Removing the surface on the sheets of bimetall and others for welding. When working with this automatic, there are no shortcomings characteristic of manually surface air-anthews; The instability of the burning of the arc, uneven speed, change in the depth and width of the groove, a varying degree of vegetation of the metal along the length
cut and low performance. The semiautomatic device consists of a cutting head 3, with the help of which a coal (graphite) electrode 1 is supplied down to excite and maintain arc burning, and a stream of air is created to remove molten metal. The head is installed on a cart 5 moving along the guide rail 4. The head is removable and can be installed on other transportation devices that have the corresponding limits of changing speeds. To control the cutting process, the semiautomatic device is equipped with a portable control panel of 2 and a mobile cabinet with a start-up and control and measuring equipment.
Technical characteristics of the semiautomatic device PVD-2-67 as follows:
It is recommended to use high.power converters and high.power rectifiers as direct current sources that allow the use of current to 400-500 A. When cutting on alternating current to increase the resistance of arc burning, it is necessary to use an oscillator. In the absence of an oscillator, you have to work at an increased idle voltage, using a sequential connection of transformers. You can also work on increased current load, using a parallel connection of two single welding transformers of the same type. The last method provides the best quality of the cut edges.
The coals produced, according to GOST 10720–64, with a diameter of 6 are used as electrodes; eight; 10 and 12 mm. Outside, the coals are covered with a layer of copper with a thickness of 0.18-0.25 mm. Rod length 300 mm.
Airborne method is cut by carbon and alloy steel, cast iron, brass and difficult to have 5-25 mm thick alloys; Defective sections of welds are cut out, rivets are cut off, holes are pierced, steel casting is cut off, founded in foundry.
The diameter of the electrode is selected depending on the thickness of the time
cut metal, namely:
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
Lectures “arc cutting (welding)
The arc cutting of metals can be performed by metal melting, electrode, coal electrode and non.melted tungsten electrode.
The arc cutting with a metal electrode This cutting method is that the current strength is set 30-70% more than when welding; As a result, the metal is melted with a powerful electric arc. The electric arc is ignited at the beginning of the cut on the upper edge and during the cutting process the arc is moved down along the cut edge, as shown in the rice. 91.
The resulting drops of the melt of the linen metal are pushed out
With a metal electrode, the visor of the electrode coating.
The electrode visor also serves as an insulator from the closing to the metal.
The main drawback of this method of cutting is small performance and low cut quality.
Manual arc cutting modes of steel with a metal melting electrode are available in the table. thirty.
With this method of cutting, the separation of the metal is achieved by melting it along the section line. The method is used for cutting cast iron and non.ferrous metals. Steel is cut in this way, if it is not required to provide accurate dimensions, and the width and quality of the cut do not matter.
Cutting in this way is performed from top to bottom, and a certain angle of inclination of the melted surface to the horizontal plane must be observed. This is necessary to facilitate the flow of metal. Cutting is carried out at direct or alternating current.
In table. 31 is an example of the cutting mode of steel became a coal electrode.
Arc cutting tungsten (non.melting) electrode is carried out in the protective environment of the argon. This type of cutting is rarely used. It is mainly used in the processing of alloy steels or non.ferrous metals.
Cutting modes have become a coal electrode
The essence of the method is that an increased current is created for cutting on the electrode (20-30% higher than when welding) and the metal is melted through and through.
The essence of this method of cutting is that the metal first melts with an electric arc, and then burns in the incoming stream of oxygen and blown out.
The oxygen-duma cutting scheme is shown in the rice. 92.
There are several ways of oxygen-dug cutting, one of them is a method of cutting using steel tubular electrodes.
In this method of oxygen-duging cutting, the metal is heated by an electric arc excited between the processed product and the tubular electrode. The stream of oxygen is supplied through the hole of the tube and, falling on the heated surface of the metal, oxidizes it throughout the thickness.
The electrodes with this method are pipe made of low-carbon or stainless steel (external diameter-5-7 mm, hole diameter-1-3.5 mm). The outer surface of the electrode has a special coating to protect it from closing to the processed metal when moving and supporting.
Another variety of oxygen-dug cutting is carbon electrode cutting.
The essence of this method of cutting is that the metal is melted with an arc excited between the product and the coal electrode. Metal removal is carried out by a stream of compressed air.
The circuit of the air-pound cutting is shown in the rice. 93.
Air-fiber cutting is carried out on a direct current of reverse polarity. This is due to the fact that with an arc of direct polarity, the metal heats up on a too wide area and the removal of the metal is difficult. Sometimes alternating current is also used.
For airborne cutting, special cutters of two varieties are used: with an annular arrangement of the air stream and with a sequential location. In the cutters with a sequential arrangement of the air jet relative to the electrode, compressed air flows only on one side.
Coal or graphite electrodes with a round or plate shape are used for air-antigrous cutting.
The value of the current during air-fiber cutting is determined by the formula:
K. a coefficient depending on the thermophysical properties of the electrode material. For graphite electrodes K = 60-62 a/mm, for coal-46-48 a/mm. Thus, a slightly smaller current requires coal electrodes.
Power supply for airborne cutting is provided with standard welding DCR-current converters or transformers. Compressed air is supplied either from the workshop network or from mobile compressors.
Air-fiber cutting is divided into two varieties: dividing cutting I superficial string. Surface string is used to cut defective areas in metal and welds, for picking the root of the seam, as well as to remove chamers. At the same time, the chamfer can be removed simultaneously on both edges of the sheet. The width of the groove, which is formed with a surface strip, is 2-3 mm larger than the diameter of the electrode.
In table. 32 and 33 some characteristics of the air-anthog cutting are given (in the table. 32 shows the data when cutting the root of the seam, which is made VSTK with the X-shaped preparation of the edges).
Таблица 32. Режимы поверхностной воздушно-дуговой резки
Таблица 33. Режимы разделительной воздушно-дуговой резки
Воздушно-дуговая резка чаще всего применяется для обработки нержавеющей стали и цветных металлов. Она имеет целый ряд преимуществ по сравнению с другими способами обработки: более проста, дешева и более производительна.
Плазма — это газ, состоящий из смеси электрически нейтральных молекул, положительно заряженных ионов и электронов, и нагретый до очень высокой температуры.
Тема: Технология ручной дуговой резки плавящимся электродом.
Задачи занятия: Проверить знания предыдущего занятия, освоить новый материал.
Умения : специальные (правильно спланировать работу подобрать материалы, для разных видов резки плавящимся электродом)
Оборудование к уроку : Классная доска, проектор, интерактивная доска, компьютер.
Электродуговую резку применяют исключительно в том случае, если нет необходимого оборудования для резки газом. Таким методом избавляются от небольших излишеств металлических заготовок и исправляют дефекты путём их поверхностной выплавки. Дуговой резке электродом поддаются цветные изделия, высоколегированные стали, а также чугун и различные сплавы. Применяемые способы
Электрическую дугу активно используют не только при сварке, но и при резке металла. Существует несколько разновидностей дуговой резки металлических деталей: ручная дуговая резка плавящимся и неплавящимся электродами, а также воздушно- и кислородно-дуговая резка.
Дуговая резка неплавящимся электродом
При данном способе работа проводится как на переменном, так и на постоянном токе прямой полярности. Сила тока должна составлять 400-800 А. При этом используются угольные и графитовые электроды.
Дуговая резка металлов выполняется металлическим плавящимся электродом, угольным электродом и неплавящимся вольфрамовым электродом в защитной среде аргона.
Дуговая резка металлическим плавящимся электродом
Сущность способа резки металлическим плавящимся электродом заключается в том, что сила тока подбирается на 30—40% больше, чем при сварке, и металл проплавляют мощной электрической дугой. Электрическую дугу зажигают у начала реза на верхней кромке и в процессе резки перемещают ее вниз вдоль разрезаемой кромки.
Схема резки металлическим электродом
Drops of the resulting molten metal are pushed out by the visor of the electrode coating. The visor simultaneously serves as an electrode insulator from the latter to close to metal. The main disadvantages of this cutting method are low performance and poor cut quality. Manual arc cutting modes of steel with a metal melting electrode are given in the table.one.
Sometimes automatic cutting is used under the flux of alloy steels having a thickness of up to 30 mm. Cutting is performed on conventional welding machines for welding wire SV-08 or SV-08A using the flux An-348 (table. 2).
Cutting with a steel electrode is based on the melting of the metal from the cutting zone with the heat of the electric arc excited between the electrode and the cut metal. This method is widely used for rough metal cutting. Cutting is carried out by steel electrodes with a high.quality coating, but more refractory than for welding. This coating provides when cutting the formation of a small visor covering the arc area.
The visor protects the electrode from a short circuit into the cut metal, and also contributes to a more concentrated heating of the metal. The electrodes are made of wire brand SV.08 or SV.08 A with a diameter of 2.5–6 mm and a length of 250–350 mm.
Apply coating that contributes to the improvement of the cutting process consisting of manganese ore (98 %) and Potash (2 %) or manganese ore (94 %), marble (3 %) and kaolin (3 %). Coating thickness. 1–1.5 mm. Current is constant or alternating. Idle voltage of at least 65 V. With the thickness of the cut metal of 6–25 mm and the diameter of the electrode 2.5 mm, current 130–140 A is used. Cutting speed is 3–12 m/h. With a diameter of the electrode 5 mm, the current reaches 300–350 A, and the cutting speed. 7–25 m/h/h. Recommend electrodes like OZR.1, allowing you to cut metals in any spatial position.
Oxygen-duging cutting differs from ordinary arc in that a stream of pure oxygen is served by a heated section of the metal surface to melting. Oxygen burns the metal of the cutting area and blews out the resulting oxides and molten metal from the cutting cavity. When the metal is combined, additional heat is released, which accelerates the process of melting and cutting the metal. This method is used to perform short cuts in various building structures.
With manual oxygen-dug cutting with a cutter type RGD, a cutter in the right hand holds an electroder, and in the left-a cutter. Having excited the arc and heating the metal before melting, the cutter presses the oxygen valve handle and directs a stream of oxygen to a warmed metal. Then, during the cutting process, the arc and the cutter are moved along the cut line. Electrodes are steel rods with a diameter of 4–5 mm with the coating of CM.7, OMM.5, OPS.3, etc. The welding current, depending on the diameter of the electrode, reaches 250 A. In this way you can cut metal up to 50 mm thick. Metal 10–20 mm thick is cut with an electrode with a diameter of 4 mm at a speed of 450-550 mm/min. Oxygen consumption is 100–160 l/min. Carbon and low.alloy steels 50 mm thick are cut with an electrode with a diameter of 5 mm at a speed of 200 mm/min at oxygen consumption up to 400 l/min.
The thickness of the cut.down doped steel, mm
The method of arc welding is based on the creation of a closed electric circuit. Between the electrode and the part, an arc is created, melting its edges and the end of the rod. The electric circuit includes a power source, a welding cable, an electrode with a holder, a grounding, a return cable and a processed part. The current begins to leak through the entire circuit after the formation of an arc. It is important to include the processed part in the electric circuit in the process of welding or cutting. The temperature of the arc is 60000C.
Welding cutting, like any technology, has its advantages and disadvantages, accounting for which will make the work quickly and achieve the expected result. The main disadvantages of the method include:
- low performance, which is due to low speed;
- poor cut quality obtained as a result of hardening the leakage from the back of the workpiece.
The listed shortcomings make the method inconsistent in conditions when it is required to withstand accurate marking during metal cutting.
The main advantages that distinguish this method:
- lack of the need to purchase special expensive equipment, tools;
- lack of special requirements for surrounding conditions;
- quick training in working techniques and equipment development;
- the ability to work with direct or alternating current.
Many organizations of construction, repair, automotive spheres, as well as home craftsmen successfully use electric welding, since this method is designed for simple, inexpensive cutting of various metal surfaces.
Is it possible to cut metal with electric welding?
Metal is widely used at a construction site, as well as during household and repair work. Therefore, there is a need not only for the combination of metal blanks, but also to cut them through electric welding.
Often the same question is asked on welding forums and sites. how to cut metal inverter? Whether the usual inverter will pull metal cutting with electrodes?
Cut metal with electric welding only in cases where there are no special requirements for the quality of work. Of course, with this approach, it will not be possible to make perfectly even edges and cut, as is the case in the case of a corner grinder.
However, in the presence of appropriate experience and knowledge, you can still achieve smooth and even edges of the cut. To do this, you need to adhere to the following rules.
Cutting became small, medium and large thicknesses
The cutting of steel of small thicknesses (especially less than 5 mm) is usually accompanied by significant overheating of the metal with a heating flame, which leads to enhanced melting of the upper edges and to an increase in the slag of non.acidified (melted) iron. Such a slag is welded to the lower cuts of the cut and requires significant labor costs to remove it.
In addition, during cutting of steel thickness, warping increases from the plane of the cut sheet, leading to the formation of bays, as well as to a stronger distortion of the forms of cut parts and blanks.
The normal cutting process using conventional equipment is performed with a thickness of sheets of at least 4 mm. With thinner sheets, the best results are given by cutting with the sequential location of the heating flame and cutting oxygen (see. rice. 78, a), however, in this case, cutting sheets with a thickness of less than 3 mm is difficult and does not give good results. High quality cutting sheets of small thicknesses can be obtained with package cutting, especially effective in the serial manufacture of the same cut parts. Package harsh can cut sheets with a thickness of 1 mm.
The essence of the package cutting process is as follows. The sheets are folded into a package and are cut by an oxygen stream in one passage of the cutter into the bag is typed up to 50 or more sheets, depending on their thickness, the amount of the necessary identical details and means for assembling bags. In some cases, it turns out to be advisable to collect sheets of such thicknesses in packages that can be cut separately (8-10 mm or more).
Package cutting has some features. When cutting ordinary equipment, a tight assembly of sheets with minimal gaps between them is very important. In the presence of gaps, heating of the underlying sheet worsens, and the oxygen stream, without cutting it out, begins to spread to the sides, carrying with him a hot slag, heating and burning the already cut parts and the underlying sheets. In order to avoid this, the sheets are pre.straightened and pulled together either with clamps or welding rollers applied to the ends. When compressing a package of thin sheets, presses are sometimes used sometimes.
Due to the fact that the power of the heating flame is taken in accordance with the total thickness of the package, the upper sheet overheats greatly and troops with a low thickness, moving away from the underlying and creating a gap and creating a gap. As a result, cutting may stop. Therefore, often a sheet of larger thickness (usually 6-8 mm, even if parts are cut out of thin metal) is applied to the bag on top).
To some extent damaged, the part of the lower sheet (with thicknesses of up to 3 mm), on which a large amount of draining slag, leading to mourning of the edges is assembled. The assembly of the package when cutting it from the edge is useful to perform with a displacement of the edges. The package can be assembled without displacement, but then cutting should begin, according to Rin pre.melted, the end of the edges of the roller. In the center of the package, you can start cutting, having previously drilled a through hole. After the cutting ends to facilitate the separation of cut parts, their rapid cooling is recommended (sometimes with water).
Oxygen cutting low pressure with large passing sections of equipment requires less accuracy of fitting sheets in the package on planes, allowing cutting with local gaps. In this case, the slow flow of slag facilitates the heating of the underlying sheet, since the slag, filling the gap, prevents the spreading of the oxygen stream to the sides and helps to maintain its direction. The method of packet cutting of low-pressure oxygen is especially appropriate when cutting sheets with a thickness of 8-20 mm; In this case, the gaps between the sheets can be 2-4 mm. When cutting bags of low pressure by oxygen, the number of squeezing packets of clamps can be reduced.
Cutting modes have become medium thicknesses
The best results in the quality of the cuts are given by oxygen cutting of medium thicknesses (approximately 12-100 mm). The oxygen cutting of such a metal does not cause technological difficulties and is easily performed by conventional gas.cutting equipment both manual and mechanical methods.
The cutting of steel of medium thicknesses with ordinary equipment should be done at the pressure of oxygen in the working chamber of the gearbox 2.5-6 kgf/cm 2, depending on the thickness of the cut metal.
Estimated technical speeds of machine dividing cutting steel of various thicknesses with oxygen purity of at least 98.5-99% are given in the table. twenty.
Using the best thermal preparation of the upper edge to reduce the probability of re.cutting, VNIIAUBOGEMASH developed a method of high.speed rectilinear cutting “angle forward”. F up to 50-70 ° Cutting speed at the perpendicular location of the cutter (normal cutting) and when the cutter is located “angle forward” (high-speed cutting) are presented in rice. 106. From the given data it follows that this method gives an increase in the performance of cutting with the thickness of the cut steel up to 30 mm.
It is economically very advisable to carry out an illiterate cutting. Currently, non.sorting modes based on the use of high purity oxygen (99.5%) have been developed, the choice of the optimal regime, direction and pressure of the jet of cutting oxygen, in which there is no flow of slag in the direction of reverse cutting (t. e. With a small lag a), the maximum decrease in the power of the heating flame and the replacement of acetylene by other combustible (kerosene, propane, etc.).
Non.game cutting modes for obtaining II class quality classes on the recommendation of VNIIABOGENMASH are given in the table. 21.
With small thicknesses (up to 12-15 mm), machine non-ghost cutting is possible and with somewhat less pure oxygen when the cutter is directed with an angle (see. rice. 105).
Cutting of the steel of medium thicknesses with oxygen of low pressure with cutters with an enlarged channel of cutting oxygen is inappropriate.
Cutting became large thicknesses
Normal gas cutting equipment, as a rule, is designed for cutting steel up to 300 mm thick, but already with thicknesses above 200 mm some difficulties appear when cutting. Even greater difficulties appear when cutting metal with a thickness of more than 300 mm. The cutting of steel of such thicknesses is used mainly in the metallurgical industry and at some enterprises of heavy engineering.
Electric and metal cutting technologies begins the same. Welding apparatus is connected to the network. With one cable it is connected to the details, and the second to the holder with the electrode. The value of the current is set depending on the thickness of the material and the size of the electrode. Tapping the electrode along the metal surface, arouse the arc. Metal under the influence of high temperature begins to melt.
In contact with air oxygen, an beginner firm metal is oxidized. This can lead to defects in the form of oxides. Inert protective gas is used to avoid this. Most often, Argon and Helium act in this role. Gas that is used for cutting and welding metals is supplied to the welding bath.
- Dividing. Implies the possibility of flowing molten metal from the resulting section. The diameter of the electrode is greater than the width of the leaf. If the sheet is located in a vertical plane, then welding is made by the method from top to bottom. The electrode is located perpendicular and move along the intended line. If through holes must be made, then you should start with them.
- Superficial. It is used when it is required to lay various kinds of grooves on the surface of metal, as well as remove defects in the form of influxes. To obtain wide grooves by the electrode, transverse oscillatory movements are made. Moving is made with a slight immersion of the electrode deep into the metal.
- Cutting holes. First make a small hole, and then expand to the desired size. A slight deviation of the electrode from the perpendicular to the surface towards the circle is permissible.
What about welding current? As you already, I hope, understood, the more welding current, the more energy it is transmitted to the welding zone, the stronger and deeper the metal melts and the more thick ’products you can connect. And to transfer the current of greater strength, you need a thicker conductor. Accordingly, we can directly depend on: metal thickness. electrode thickness. current strength. Often on welding machines apply signs of compliance of the thickness of the electrode and welding current. I recommend that you do not perceive such tables as a dogma. this is just a starting point for you to be guided. For the household, you have enough current up to 160A, which allows you to use an electrode of 4 mm. In my memory, I very rarely used this diameter of the electrodes. Basically, it is 2 and 3 mm. There is still diameter 2.5 mm for the electrodes of the stamps of the UONI-13/45, 15/55, NIAT-3M (types for carbon steels). Tentatively, the welding current force can be defined by the formula: i = kdel. Where is the experimental coefficient equal to 40-60 mm for electrodes made of low-carbon steel and 35-40 mm for electrodes with high-voltage steel rods, and DEL is the diameter of your electrode.
Plasma Arc Cutting #plasmacutting #plasmacutter #plasmacuttingmachine
When welding and cutting metals, special electrodes are used. The difference from conventional electrodes lies in a larger amount of heat created by a welded arc, and increased heat resistance of coating.
Cutting metals using welding can be carried out by different types of electrodes:
- Unnecessary. It is made from tungsten. In the process with an unnecessary electrode, the incision is quite rude. In the process, a protective gas environment is required. Used for alloy steel and non.ferrous metals.
- Melting. To obtain a neat appearance, melting electrodes are used.
- Carbonic. Otherwise they are called graphite. Coal electrodes are used for non.incompatible details. Their dignity is a slower melting. A feature is that they do not melt, but burn. This reduces the amount of slag, and the cut is cleaner. Another feature is the ability to warm up to a very high temperature at a small current.
- Tubular. Tubular electrodes are used when cutting occurs in an oxygen-dugout way. The basis of the electrode is a special tube with thick walls of hollow from the inside.
When solving how to cut metal with welding, you should make a choice between these types of electrodes. Cutting can be carried out by conventional electrodes. In this case, the current should be increased by 30-40%. This will require more electricity consumption, and, accordingly, will increase the costs of the process.
Types of coal electrodes
When welding with a coal electrode at home and in production, different types of consumables can be used, which may differ in the form of section.
The following types of coal electrodes are the most optimal and in demand:
- Round. They can be used in unlimited mode. The diameter of the electrodes is from 3.2 to 19 mm.
- Round endless. The tips were called due to a small consumption, they are the most economical. The size of the diameter can be from 8 to 25 mm. For the welding process, these electrodes use a special machine.
- Flat. The cross section of the rods of this species has a rectangular shape sometimes a square. The size is from 8 to 25 mm. They are mainly used to seal external defects on the surface of the ebb from steel.
- Semicircular. They have a section size from 10 to 19 mm. They are popular coal rods that are used for welding and cutting metal elements. During the welding process, they contribute to the formation of the correct and even seam.
- Hollow. They allow you to form a U-shaped groove. Diameter is from 5 to 13 mm.
Methods of cutting
Methods of metal cutting are classified depending on the equipment used. This parameter allows you to highlight the following types:
- manual cutting;
- gas acid;
- cutting with a tape saw;
- using guillotine;
- with a disk machine.
Manual cutting of metal
This cutting method is not used in industry due to low efficiency. You can cut a metal sheet manually using scissors, jigsaw, hacksaw, corner grinder. The speed and accuracy of the work in this case completely depends on the master who cuts the material. It is worth considering that the tools used, especially scissors, are significantly limited in terms of technical characteristics. Not every metal will be cut manually. Nevertheless, this method is suitable for performing most household tasks.
Hydroabraseic cutting of metal
When the separation is carried out with the aim of cutting the workpiece made of metal, one of the most suitable methods will be hydro.carbrease. A stream of water mixed with an abrasive substance affects the material under pressure, so that you can cut out parts of a complex shape. This is one of the first methods of cutting metals known to humanity. Modern equipment allows you to achieve high accuracy and reproduce lines of any curvature.
Other advantages of this method include:
- the ability to easily cut metal products of significant thickness;
- effective obtaining complex elements of non.standard configuration;
- minimum metal consumption during cutting due to the small cut width;
- Protection of the material from deformation and melting due to a low temperature regime in the cutting area.
Plasma Arc Cutting of Stainless Steel
With all the advantages of hydro.carbrane cutting of metals, only sheets from a certain alloy, having a small thickness, be processed in this way.
Thermal cutting of metal
Thermal cutting of the metal allows you to significantly accelerate the cutting. Thermal cutting happens:
Each type of thermal cutting has its own characteristics, however, a distinctive feature is the lack of direct contact between the processed surface and the tool. The contactless separation of the workpiece occurs using a jet of gas, laser beam or plasma, respectively.
Gas acid cutting
At high temperatures, the metal heats up, melts and burns out. It is this property that underlies gas acid technology.
The process of gas acid cutting takes place in two stages:
- First, a stream of flame is directed to the place of the future section, using acetylene as combustible material.
- After the metal has been warmed up, oxygen is supplied to the section. Under its influence, the soft surface is separated, and the oxides present in the material are removed.
This method allows you to cut metal blanks of large thickness, including titanium sheets. However, this method also has features that can be considered as disadvantages:
- metals of some species, including aluminum, copper and other non.ferrous metals, chromicillage steel, high.carbon steel, are not lending on processing;
- insufficiently high.quality cut;
- wide cut;
- the appearance of influxes and oxides in the process;
- You can not cut curved surfaces;
- In the cut zone, the physical properties of the material change.
The main difficulty in obtaining a cut of high quality arises due to the need to maintain an identical distance throughout the process. Unlike manual cutter, the automated device cuts the workpiece more accurately and quickly.
A cutting tool when using this method is a plasma stream. For such metal cutting, special equipment is used. plasmabron. A jet feed of plasma occurs through its nozzle, which is essentially ionized gas temperature gas gas.
Plasma cutting is indispensable when it is necessary to separate a thick metal sheet. The technology allows you to work with a material up to 150 mm wide.
By the type of exposure to the material, there may be:
- plasma-dug-the processed metal is melted using an electric arc between the product and the cutting tools;
- indirect. the separation of a metal workpiece occurs exclusively due to plasma.
Metal plasma cutting is characterized by:
- high speed of work;
- smooth cut;
- the ability to work with complex contours;
- heating the processed surface to a slight level;
- high price of this type of equipment;
- noise in the process of plasmotrons;
- the need for training;
- limited material thickness, which can be cut in this way.
Laser cutting of metal is a modern method of processing products using the exposure of a laser beam. By focusing the laser at a particular point of the cut material, you can warm up from above the melting temperature and evaporate the surface area. Moving the working head along a given path, a cut of the required shape and size is obtained on sheet metal.
Most often, the technology is used when processing:
However, laser cutting is unique in that it allows you to cut any metal products, as well as the details of their alloys and non.metals.
- the ability to cut out complex geometric contours;
- high accuracy of cutting;
- the evenness of the edge close to the ideal;
- high performance.
However, the disadvantages of such metal processing should be taken into account:
- limited thickness of surfaces that can be treated;
- significant energy costs;
- the need to study before the cut.
Mechanical cutting of metal
Mechanical technologies involve direct contact of the tool with metal. Such a tool can be: