How to cut metal with gas welding correctly. Video on the topic: cutting metal with cutter

Metal gas cutting technology

In this article you will learn about the features of gas cutting of metal, the advantages and disadvantages of this method, the principle of equipment operation and its types.

To date, gas cutting is the most popular method, due to the lack of strict requirements for the place of work and the simplicity of operations. In this article you will learn about the features of the technology, advantages and disadvantages of this method, principle of operation of equipment and its types.

Gas metal cutting is a technology that is used to date widely, since it involves the simplicity of the operation, does not require additional sources of energy and complex equipment.

It is these method that experts use specialists in repair, construction and agricultural work. Almost all devices designed for metal cutting are mobile, they are easy to transport and use in another place.

Metal cutting technology gas

The essence of the process of oxygen cutting is as follows. The heater heats the metal on average to a temperature of 1100 degrees C. Then a stream of oxygen is supplied to the working area. The flow, in contact with the heated metal, is ignited.

A burning stream easily cuts a metal sheet, provided that the gas is constant and stable and stable.

The metal temperature should be less than the melting temperature. Otherwise, molten but not burned masses are difficult to remove from the working area.

Thus, the cutting operation is performed by combustion of the material in the gas stream. The main module of the gas cutting tool is the cutter. It provides an accurate dosage of mixing gases or vapor of liquid fuel with oxygen masses in the gas.air mixture.

The cutter also provides ignition of the resulting mixture, and a separate supply of oxygen to the workplace.

Gas cutting belongs to thermal methods of metal processing. Its advantages are that you can work with a material of any thickness, and with high performance. The volume of daily production of the welder can be measured in tons.

Experts note the advantages of this technology in the fact that gas.plasma cutting is completely autonomous and does not depend on the presence/absence of power sources. Since the welder often should conduct work in the field or he does not have the opportunity to connect to the power source at a particular object.

Manual gas acid cutting of metal is available for working with a wide range of materials, with the exception of brass, stainless steel, copper and aluminum.

Features of gas welding

In the process of performing work, it is possible to adjust the composition of the mixture, which the gearbox helps. The power and temperature of the flame is regulated depending on the types of work. There are several types of gas welding:

In the molten bath during welding processes, two main processes occur, restoration and oxidation. The structure of the adjacent metal is mainly coarse.grained, for a more durable connection.

For improved strength, heating is performed to maximum temperatures, a kind of metal forging.

Several basic features during gas equipment:

• Gas welding of steel materials of low.carbon type is carried out by various types of gas, the filler element consists of steel wire, with a small amount of carbon content.
• Doped steels are welded by materials that interact with the composition. For example, heat.resistant stainless steel details are welded using nickel wire, some of the brands of material will require the use of molybdenum.
• Copper products are welded at elevated temperatures, a large fluidity of the metal will require the minimum clearance of the compounds. The filler material consists of copper wire and flux, which is used to deoxidize the seam.
• Lature compounds are made by applying additives from identical material. Due to the volatility of zinc, to avoid the formation of pores, when welding, a larger amount of oxygen is supplied.
• Bronze alloys are welded by the recovery type of flame, without burning the main components of the metal. For adding, identical material using silicon, contributing to the deoxidation of the seam and metal.

It is worth noting that when working with aluminum or magnesium, oxidation processes flow faster. The processing section and seam have various parameters and characteristics located in the immediate vicinity of the fitting area is characterized by reduced strength, prone to premature deformations.

The principle of gas welding

Oxygen and combustible gas are supplied to the device through nozzles, ignition through the nozzle occurs, valves are adjusted by the power of the flame. The flame consists of several main parts, torch, recovery process and nucleus. The highest temperature parameters are observed in the core, the process occurs part of the flame between the core and restoration.

The effects of high temperatures on the surface of materials entail the protection of the welding area from excess air, in which there are impurities of heavy gases. High indicators during metal cutting allow you to perform work with high accuracy, to produce the necessary products. There are various types of gas welding.

Gas for welding plays a large role in density, quality of the connection, popular gas when used indicates acetylene.

Types of metal cutting gas

The gas acid cutting has several varieties. Scientists and engineers have developed these methods based on the features of application in specific conditions. The following cutting methods are most used:

• Propane. This fairly popular way is applicable for titanium, low.alloy alloys and steels with low cargone. For carbon and high.carbon steels it is not suitable. For greater performance and energy efficiency, propane can be replaced with methane or acetylene.
• Air. arc. In addition to combustion of the material in a jet of oxygen, honey blanks and an electric shower built into the cutter with an electrode is excited by an electrode. She melts metal in the area of ​​the cut line, and the gas flow takes its remnants. The method does not allow you to cut thick products, but makes it possible to make cuts of large width. This is very useful when performing shaped cutting and can significantly reduce the complexity of the operation.
• Oxygen-fluish. With this method, flux powder is fed to the working area. This component is involved in physico-chemical processes and ensures increased plasticity and supplement of material during cutting. The method is applicable for cutting alloys, on the surface of which strong and heat.resistant oxide films are formed. The use of flux allows you to get rid of them by shifting the temperature balance in the zone of higher temperatures. This method is especially effective for cast.iron, copper, bronze and brass products, blanks with a high degree of slagging and for reinforced concrete.
• Spear. It is used in disassembling metal structures, technological waste, cutting massive bulky blanks. A stream of oxygen is passed through a thin steel tube. a gas spear. A spear is a consumable, it burns out during the process, increasing the temperature and effectiveness of the main reaction and allows you to additionally concentrate the cutting torch. As a result, the cutting speed increases significantly.

Technologically, the process of gas acid cutting involves the maintenance of the cutting with a gas cut manually.

The gas supply is controlled by one common or two separate valves. The use of separate valves allows you to accurately configure the composition of the mixture and quickly rebuild equipment for another type of work.

The cutter of the cutter is equipped with three rogues with connectors. Oxygen, propane (or acetylene) and cooling fluid are brought down on them. Oxygen pressure is installed on the cylinder gearbox and can reach 12 atmospheres.

After the ignition is performed in the cutting torch, oxygen is supplied. The combustion of propane heats the surface of the workpiece to such a temperature that the chemical reaction of its oxidation begins. It goes so intensively that the part is burned through a stream of cutting oxygen and the gas flow takes the burning particles of the metal into the incision.

Conditions for gas acid cutting

For the successful use of gas acid technology of metal cutting, a number of prerequisite should be observed:

• The melting temperature (tlav) should exceed the combustion temperature (tvospl) in the oxygen medium. The difference should be at least 50 ° C to exclude the flow of the melt and unjustified expansion of the section of the section. So, for structural alloys tplav = 1540 ° C, and tvospl = 1150 ° C. With an increase in carbon content, the melting temperature decreases. This makes it difficult to cut cast iron and high.carbon alloys with an ordinary cutter.
• The tplaw of the cut material should exceed the tplaw of oxide films on its surface. The refractory oxide film will prevent oxygen access to the metal surface and the combustion reaction cannot begin. So, chromium oxides and structural steel 3 have melting temperatures, respectively 2270 and 1540 ° C, respectively. The way out of this situation may be the use of flux powder, which reacts with an oxide film and converts it into a substances with a lower melting point.
• Oxides arising during the cutting process should have a high fluid. If the fluidity is low, then they put on the edges of the cut line, preventing the burning of the main material. A specially selected flux powder also helps to solve this problem, increasing the fluidity of oxides. But this leads to a rise in the cost of the process.
• The cut material should have low thermal conductivity. Otherwise, heat will be removed from the working area and the temperature of the metal fire at the venue will not be achieved. The reaction will not begin to begin or will proceed unstable, increasing gas consumption, reducing the accuracy and quality of the cutting surface.

How to set up a gas cutter

Immediately before the start of actions, it is necessary:

• carefully check the tightness of all compounds so that there is no gas leak;
• Make sure that nothing and no one will hurt you (animals, strangers, children, objects at hand);
• put on protective equipment.

For the subsequent correct and safe operation of the cutter, it is necessary to correctly connect it. This is performed in several stages:

• Connecting a cutter to a gas source is a can of combustible gas (propane or acetylene) and an oxygen cylinder through a high.pressure sleeve gearbox. Strictly according to GOST hoses for acetylene (propane) and oxygen differ in color (red and blue, respectively), so it is quite difficult to confuse them. In order to avoid improper connection of hoses to the cutter or gearbox, nuts with left thread for combustible gases are used and with the right thread. For oxygen.
• Check if the propane or acetylene supply gearbox is open.
• Set up the oxygen supply. This is necessary:

• Open the main gearbox of the oxygen cylinder until it stops;
• Slowly rotate the supply regulator until the pressure necessary for work is set on the low pressure pressure gauge;
• open the oxygen valve of the cutter and remove the air from the hose;
• Close the front valve.

How to work with a gas cutter: an algorithm for performing an operation

When the cutting process begins, carefully move the cutter in accordance with the intended line. If you do everything right, slag and sparks will bend. When this does not happen, it is necessary to reduce the speed or take care of the better warming up of the metal. Continue the procedure until you cut off everything you need.

After the end of the cutting process, the product must be cool. If you have enough time, leave it naturally for cooling. You can speed up the cooling process by dipping in a container with cold water.

The last step is to remove the slag from the cut and sand it (if necessary).

These are all tips on how to cut a gas cutter. Always remember the safety precautions and suitable equipment, move the cylinders only vertically and follow the purity of the mouthpiece, replace it in a timely manner.

Instructions for use

The preparatory stage is concluded in the inspection of equipment. Check the correct connection of the hoses, tightening the mount, their tightness. It is recommended to lubricate the glycerin valle seals, and then start work.

• open a valve with oxygen, then with combustible gas;
• set fire to (a match, lighter) output mixture;
• adjust the stream with valves to the desired size and flow rate;
• warm the place of the cut;
• open a valve with cutting oxygen, perform surgery;
• block the valve with combustible gas, then with oxygen;
• Cool the tip in cold water if necessary.

Open valves on the cylinders open valves on the cutter set fire to the mixture

It is important to remember about PPE. gloves, closed hands, gas glasses, etc.D. It is advisable to have comfortable shoes, clothes are not made of synthetics, but the cut site is completely degreased, otherwise the explosion when contacting oxygen with oil is inevitable. The fact that smoking near the cylinders is impossible is not worth reminding.

Several useful tips

A number of recommendations before starting work:

• When choosing a mouthpiece, pay attention to the marking. they have letters (“a”. for acetylene, “p”. for propane, etc.D.);
• There are arrows on the valves with the direction and the letter indicating the side of rotation at the opening (“O”) and the closure (“Z”);
• The nutser nut for oxygen has the right thread, under combustible gas. left;
• Never direct gas equipment for cutting metal towards the sources of the mixture (cylinders);
• Follow the hoses; A good gas cutter connects them and has a side so that it does not interfere with the process.

In short, this is all that you need to know about the principle of operation and types of gas cutter for metal. Before buying, the user is determined with the type of equipment, evaluates the volume of work, wonders how much the gas cutting machine or a compact mini-executive will cost. If you are an experienced user who can give recommendations regarding the cutters, share this in the discussion to the article.

Cutting on the surface

Before work, it is necessary to inspect the device to make sure that the cutter is completely serviceable. Then take the following steps:

• First of all, hoses join the device for cutting. Before you attach the sleeve, you need to blow it with gas to remove garbage or dirt that gets there. The oxygen hose is attached to the fitting with the right thread with the help of nipples and nuts, the second hose (for propane). to the fitting with the left thread. Do not forget before you attach the sleeve with gas, check if there is a sucker in the channels of the cutter. To do this, connect the oxygen hose to the oxygen fitting, and the gas fitting must remain free. Set the level of oxygen supply to 5 atmospheres and open gas and oxygen valves. Touch your finger with a free fitting to make sure that there is an air leak. If not, you should clean the injector and blow the channels of the cutter.
• Next, check the detachable seals. Having discovered a leak, tighten the nuts or change the seals.
• Do not forget to control how hermetic fasteners of gas gearboxes are and whether the pressure gauges are working.

Ratio of propane and oxygen

In order to correctly cut metals with an oxygen-propeller cut, it is necessary to adjust the supply of gases to the hillock. Such adjustment is carried out according to the recommendations of reference books, where there are tables and diagrams, in the absence of the necessary literature, it is necessary to check with the technology indicated in the documents for the product. In the absence of regulatory documentation, one part of propane is used to ten parts of oxygen.

The nuances of cutting

The process of dissection provides for speed control, the selection of the parameter occurs visually, depends on the number of sparks and their fines. The stream of sparks formed by the cutting process should be formed at an angle of 90 ° in relation to the surface. The speed is regulated if the flow changes the direction, in this case the speed is low, requires configuration.

The thickness of the structure affects the process, in the case of a processed sheet, more than 6 cm thick, it must be placed at a small angle for draining slag. When processing thick products, it is important to withstand the angle of inclination by 15 °, control the speed. In case of cutting in the middle of the journey, the process does not resume at this point, but occurs first. In order to avoid alteration with actions with a thick product, it is necessary to conduct a cutter so that the metal is processed around the entire perimeter.

After the cutting of steel is completed, the supply of cutting gas is turned off. Then the valve is overlapped on the cylinder, the last burst is closed with the supply of a combustible mixture.

Superficial and curly cutting

The process of creating the relief on the surface of the metal is carried out in a slightly different way. Cutting is by nozzle, and molten slag, heats the lower part of the product. Heating is carried out to a temperature that does not exceed the inflammation of the material.

The opening of the cutting oxygen will provide a certain section of the combustion of the material, so that the clean edge and fishing line for the trimmer of the cut are produced.

The action is made at an angle of up to 80 °, after gas supply, the cutter is moved to angles from 18 to 45 °. The formation of grooves of the required size is carried out by adjusting the speed. The larger groove size is achieved both by a change in the angle of the mouthpiece, and a slowdown in speed, adjusting the level of oxygen. The width of the groove varies by setting up the flow of jet through the nozzle, the ratio of depth, width of the groove is equated 1 to 6. Width under this condition, the pre.emptive object, t.to. it is possible to form sunsets on the surface of the product.

Is metal deformation possible?

Gas cutting involves the thermal effect on the material, as a result of this deformation changes, it is not always possible to avoid. Deformation consists in lengthening, shortening or bending of the product. The cut part can be turned inside or out.

There are factors that contribute to metal deformations:

It is necessary to exclude the effect of these factors, otherwise you will have to correct the resulting defect. There are several simple ways that allow the preparation to return the correct shape: use firing or vacation, apply the editing of steel on rollers.

Deformations can be avoided if you pre.fix the product and warm it up, observe the speed of the gas mixture, and adhere to the correct cutting technology. It is important to sequentially fulfill all stages, choose a cutting mode based on the thickness and type of material. You can not start processing with high gas mixture supply speeds.

In the absence of extensive experience, you should start working with small blanks, and not with cutting out products from whole sheets.

Equipment

The main equipment for gas cutting is the cutter. The kit includes: nozzle for welding and swimming trunks.

Thanks to the cutter, you can control the dosage of the gas mixture and oxygen. Also, with the help of this equipment, the combustible mixture is ignited, flame supply to the processing site.

The cutter consists of two blocks: cutting and heating. The first is represented by the oxygen jet, valve and an internal.type mouthpiece.

The heating block includes valves that are designed to adjust the pressure of the gas mixture and oxygen. There is also a feed tube, an external.looking mouthpiece, a mixing chamber and an injector cell.

Cutters are manual and machine. The latter are stationary, therefore, it is preferable for repair work to use manual.

Additionally, the following gas.cutting equipment is used:

• gearbox. designed to reduce pressure;
• device for changes in pressure;
• a steel cylinder with gas and oxygen;
• Connecting hoses.

Before using the equipment, it is important to check its serviceability in order to avoid explosion of the cylinder or gearbox. The cutter is pre.blown with oxygen.

Harring the cutter and preparation of metal

This is the opening of the acetylene valve on the cutter and lower the oxygen located in the chamber-mixer. Then the valve adjusting the barely audible gas output is achieved. A special lighter is brought to the cutter and turns on. Before the cutter, a flame of small and yellow should occur.

For work, it is necessary that the flame length is 25 cm. This is achieved by the adjustment of the fluid acetylene.

The next stage is the launch of oxygen. It is carried out by the opening of the corresponding valve until the color of the flame is made of yellow blue. This means that the amount of oxygen is sufficient to fully burn the incoming acetylene.

For effective operation, the supply of oxygen increases until the moment the length of the blue flame located inside does not exceed the thickness of the steel that needs to be cut. If during the operation of the cutter a characteristic “sniffing” or flame is unstable, the volume of oxygen supplied should be slightly reduced slightly.

Before you start cutting the metal, its surface should be heated. For this purpose, the cutter is brought to the sheet so that the inner flame is from it at a distance of approximately 1 cm. The heating of steel is performed until the moment of the molten material appears on its surface.

Cutting metal

To start cutting the metal should be lowered down with a smooth slow motion handle of the cutting valve. As a result, oxygen will begin to flow to the place of combustion, which must set fire to pre.heated metal. If the material is sufficiently warmed up, the reaction will begin instantly, after which you can further increase the pressure until the metal is completely cut through the metal.

After that, you should gradually move the cutter in the intended direction of the cut. The speed of cutting motion must be selected so that the resulting slag, sparks and drops of hot metal are blown down or drained away from the flame of the burner.

After performing the cut, you should carefully inspect the place of work for the presence of large pieces of molten metal. You should not advance on them in any case, as this can lead to burning even a thick sole. A cut sheet or a piece of metal is cooled by water or naturally.