How to cut a thick metal with a gas cutter. Negative deformation
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 today, 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.
Advantages and cons
Gas cutting and welding of metals have many advantages, but we are only interested in cutting that has such advantages:
- In demand when the metal of a large thickness is cut or the clipping is needed along the stencil, and the corner grinder with curved areas does not cope.
- The gas analogue is much more convenient for work, has a small weight, acts twice as fast as equipment with a gasoline engine.
- Propane at a cost below acetylene and gasoline, so its use is more profitable.
- The cut of the cut is much already, and the structure is cleaner than from corner grinding or gas equipment.
Disadvantages. a narrow circle of metals subject to similar processing.
Principal design of a gas cutter
Injector or two.pipe cutter
This is the most popular model in its design. The name “two-pipe” is due to the separation of technological oxygen into two streams. This is done for the functional separation of oxygen work.
The second stream of oxygen goes straight to the injector. The procedure in the injector chamber is as follows: oxygen enters the chamber under high pressure and at high speed, as a result of which a sparse pressure zone is formed in this space. Oxygen is in this case injective.
Through the special side holes in the walls of the camera, combustible gas is drawn into it. it is in this case an ejective. The gases are mixed, the speed is leveled, as a result, at the exit from the chamber, a stream of gas mixture is formed, which has a speed lower than that of injected oxygen, but higher than that of the ejected combustible gas.
At the next stage, the formed mixture of gases enters the tip. first into its head, and then through the nozzle between the mouthpieces it goes and forms the very flame in the form of a torch that heats the metal to the temperature of its combustion. All gas flows are regulated by their own valves on the outside of the case. for the supply of oxygen and separately for supplying combustible gas to the injector.
Non.zero or three.pipe gas cutter
In this case, the device of the gas cutter is more complicated. Oxygen gets into it in two pipes, combustible gas is rightfully occupied by the third pipe. In this welding cut, the gases are mixed inside the head, there is no camera here. Such a system is safer than a two.chamber model.
This model has the cost is much higher. In addition to this drawback, the three.pipe cutter has another nuance: in working with it you need very high fuel gas pressure. higher than with the injector apparatus.
The design of the gas cutter
The device of the gas cutter is quite simple. The main nodes are:
The trunk, in turn, consists of an ejector, input pipes for connecting hoses, nipples, shutoffs. adjusting and connecting reinforcement.
All units, despite the various performance and other characteristics, have a similar principle of work. Combustible gas and oxygen are supplied to the mixing chamber, after which they expire through the pressure through the working injector. The rate of gas flow rate and the proportion of their mixing are regulated by two independent valves at the input to the device. This determines the intensity of the flame and its temperature.
The torch, getting on the metal of the workpiece, quickly warms it to the melting point. Part of the metal is evaporated and carried away with the products of combustion into the atmosphere, the part is oxidized and turns into a slag, part flows in the form of drops. A cut is formed in the metal. If the burner is smooth along the intended line, the warm.up area will move, and the incision will increase until the desired part of the workpiece is cut off.
Portable portable cutters with oxygen and propane cylinders
Oxygen gas cutting for metal with 40-liter cylinders on a heavy trolley significantly limits the mobility of the gas cutter. There are enough heavy hoses to reach each point of a small workshop, and when working on open areas, a gas welder is more a cart of a cart than it works. A portable portable propane cutter helps to get out of the situation. It is equipped with meek light hoses, a five-liter cylinder for oxygen and allows you to connect two-, three- or five-liter cylinders with propane. For carrying, there are a plastic container-moper or rubberized bag, reinforced with metal corners and stripes.
The device is easily placed in the rear seat of the car and is widely used for the subordinate repair of air conditioners, refrigerators and heating and water supply systems. Such a gas cutter is very convenient for a home workshop.
How to use a gas cutter
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Oxygen-acetylene burner is a dangerous method of cutting metal, but with training and observing precautions you can use it to cut steel in shape or size. In order to use a gas cutter, read the instructions given below.
Learn the basics of the cutting process. The initial ignition of acetylene heats steel to a molten state. By adding a stream of oxygen under pressure, the cutter sets fire to steel, which burns through the slot of the cut. That is why the process is called burning steel, and steel and carbon steel are the only materials that you can cut. Aluminum, stainless steel and other metals and alloys cannot be cut with a gas cutter.
- Fire extinguisher. In most cases, a fire extinguisher with compressed air and water is suitable, however, if there is oil, plastic or other flammable materials nearby, a powder fire extinguisher is recommended.
- Tools for marking and measuring. They will help you make the right cut diagram and include a pencil of soap stone, a square and a ruler.
- Protective equipment, including metal cutting glasses and thick leather gloves.
- Corresponding clothes. prerequisite. Do not put on the clothes of free cut, clothes made of flammable synthetic fabrics or clothes with well.worn or torn edges, which lights up easier than tight and filled things. It also implies that you can not wear clothes with free s, cuffs into which slag can get and burn them. Fireproof clothing is recommended, but if you do not have it, put on a well.adjacent cotton. Nylon and most traditional synthetic fabrics quickly burn out from contact with fire!
- It is recommended to shoe strong working boots with a leather sole, since shoes with a rubber sole will burn very quickly under the influence of hot slag. The shoes are preferred, since slag can fall beyond the front edge of the shoes without fasteners, for example, engineering boots or cowboy boots.
- Lighter for a cutter for proper settings of the flame of the cutter. Using matches or lighters for cigarettes is very dangerous; Sensac lighters are designed specifically for this purpose, and their use reduces the risk of serious injuries.
How to use a cutting torch
Provide yourself safe working conditions. It is strongly recommended to work on bare ground or on a concrete slab, since sparks from the cutting place fly by meters. Dry materials, for example, paper, chips, cardboard and dry leaves of plants can light up, even if they are at a distance of 4.5 meters or more. Do not let the flame touch the concrete, especially fresh, as this will lead to its expansion and intensive cracking, as a result of which small pieces of concrete take off into the air.
Put the steel that you want to cut on a support located at a working height convenient for you. A steel table is ideal because you can prepare and align the torch, heating and using it. Never use a flammable surface or surface on which flammable materials are spilled. In addition, beware of materials that have oxide.metal coatings, for example, lead paints, chromatic soils and galvanizing. Their couples can be poisonous.
Gas cutting steel, Propane torch cutting set up for thick steel cutting.
Mark the seats with a pencil of soap stone, leaving a place for grinding, if accuracy is needed. If you do not have a pencil of soap stone, then you can use a permanent marker, but its marks will disappear right in front of the flame of the cutter. In the event that you need accurate cuts, a special saw can give good results, but this is a topic for a separate article.
Connect the tubes to the corresponding cylinders. Bounds and hoses for oxygen, usually green, hoses for acetylene are red, they are pairnly separated so as to connect them to the corresponding cylinders. On the hose for acetylene Reverse thread, And connecting reinforcement is included in the tank to prevent the random rearrangement of these two hoses or tubes. Since the connecting reinforcement is made of bronze, which is easy to damage, twist it with a key with a correctly selected diameter.
- After unlocking the main valve of the cylinder with acetylene, open the control valve, turning the handle clockwise. This must be done very slowly, watching Manometer on the side of low pressure. Open until the displayed pressure is within 0.34. 0.54 atm.
- To blow the air from the acetylene hose, open the gas valve of the cutter until you hear how the gas comes out, and then look at the testimony of the pressure gauge on the side of the low pressure. In the process of purging, the pressure should remain stable. Make sure you have installed this regulator correctly.
- Close the acetylene valve on the cutter.
Standards and dimensions
Welding using a welding burner with gas.
All standard measurements regarding gas cutters are stipulated in GOST 5191-79. Naturally, the weight and size of the devices are directly related to their power. Weight, for example, can only be in two values: the cutters of the models P1 and P2 weigh 1.0 kg, and the high.power model P3 weighs 1.3 kg and not less or less gram.
By the way, the type of combustible gas is also associated with power and size. If powerful p3 cutters operate only on a mixture of oxygen with propane, then a smaller type P1 and P2 device may well function with any type of gas.
Insert gas cutters:
In addition to classic models with different power, there is a separate category. the so.called insert gas cutters with a special labeling of RV. According to GOST, they are called very strange: tips to a gas burner for cutting metal. In general, they differ from traditional cutters: mixing the combustible mixture and oxygen is carried out in the tip itself.
By weight, these devices are much lighter than cutters. RV1 weighs 0.6 kg, and RV2 and RV3. only 0.7 kg. But let this apparent elegance not mislead you. Let’s not forget that these are the tips to the burner, in the kit with which they will weigh no less than ordinary cutters. What is then the advantage?
The fact that they can be purchased for an existing burner and, thus, save some money. And the compactness of the entire kit packaged in a special case. And another important detail that concerns the nature of combustible gas. The fact is that acetylene is much more expensive than propane.
But for welding metal, it is more desirable to acetylene: the burner with it gives a flame with a temperature higher by 400 ° C than the same with a mixture of oxygen with propane.
Portable models: Small ship. Small swimming
There are now many portable options for autogens on the market. this is how they are positioned. They are sold in the form of a nozzle for a compact zani gas cylinder. But in essence and the principle of work, this is a burner. Most of them provide a torch temperature not higher than 1300 ° C.
Of course, there are also portable models of the “professional” series-the zangi cutters that give the torch temperature above-up to 2000-2500 ° C, which is generally close in terms of indicators to classic oxygen-propyed cutter. But physics is physics: even in these models there is no main component that cuts the metal. an oxygen jet that oxidizes this very metal.
Where is a portable gas cutter good? When cutting easily smooth metals or alloys such as tin, brass, bronze, copper. But even these “children’s” options are not cut, but melt. Therefore, compact nozzles. cutters are used more for soldering or welding of small blanks from non.ferrous metals. These can be parts of household devices like a refrigerator or air conditioner. Welding, not a cut, in a word.
In any case, be careful when choosing such models, far from always their proposed “portable” is ultimately justified.
How to choose a better cutter?
We offer a block of useful information that will help you better navigate the specifications and technical characteristics of the cutters in advance:
- Nipples are brass aluminum. Brass options are more durable.
- If possible, choose models with aluminum rather than plastic handles, no matter what the plastic is heat.resistant, it will “swim” in any case faster than aluminum.
- The handle should be massive enough: a diameter of at least 40 mm.
- Valves should work well. This means to turn unnecessarily.
- Devices with levers are more convenient and economical to use, they save gas.
- Ventile spindles must be made of stainless steel, and not from brass, which are too short.lived. There are “combined” options, they are in their durability in the middle position.
- The best material for the cutting case is metals: brass, copper, stainless steel.
- We remember that acetylene cutters are more expensive. We monitor the material from which the parts are made with direct contact with combustible gas before mixing in the chamber. Attention! They should not be made of copper or its alloys, where copper is at least 65%.
- If the design of the device is collapsible, it is better: it is easier to clean and repair.
- Only copper! Only copper outer mouthpiece!
- The correct internal mouthpiece for the gas cut of acetylene type should also be made of copper. But in an oxygen cut on metal. from brass. These are the nuances.
- Be sure to check with the seller a state of affairs with spare parts and consumables.
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.
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 the 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.
As in the case of any other operation, even before the cutting of the metal, the necessary equipment should be prepared with gas:
- Block with propane and oxygen. 1 pc.;
- High pressure hoses;
- A mouthpiece that should have certain sizes.
A prerequisite is the presence of a gearbox on all cylinders, with which it will be possible to configure gas supply. It should be remembered that the balloon with propane has a reverse thread, because of which an additional gearbox will not work on it.
In general, gas equipment for metal cutting has a similar device, regardless of the manufacturer. Three valves can be distinguished in the design:
- The first provides the receipt of propane;
- the second valve allows you to change the supply of oxygen;
- The latter is the valve of cutting oxygen.
To designate oxygen valves, blue marking is usually used, and for valves that provide propane. red or yellow.
The cutting of the metal is provided by a stream of hot flame, which affects the metal, which is created using a cutter. When it is included, in a special mixing chamber, propane and oxygen mixing, which leads to the appearance of a combustible mixture.
With the help of a propane cutter, you can cut metal, the thickness of which does not exceed 300 mm. A detailed installation is equipped with elements, which for the most part are interchangeable. For this reason, when failing of a particular part, the operator will not be difficult to carry out repairs directly at the workplace.
With particular care, you should approach the choice of a mouthpiece. The key parameter to which you need to pay attention is the thickness of the metal. If you have to deal with an object involving elements of different thicknesses located in the range from 6 to 300 mm, then you will have to prepare mouthpieces with internal numbers from 1 to 2, and external ones. from 1 to 5.
Preparation for work
Even before gas cutting, it is necessary to examine the device, make sure that the propane cutter is in working condition. Next, you need to perform the following operations:
- Preparation of the cutting device begins with the connection of the hoses to it. Even before the sleeve is joined, it is blown with gas. this will remove garbage and dirt from it.
- The oxygen hose must be connected to the fitting with the right thread, for this purpose the nipple and nut is used. As for the hose through which propane will act, it is attached to the fitting with the left thread. Be sure to find out before connecting the sleeve with gas, whether the suction is present in the cutter channels. This problem can be solved by connecting an oxygen hose to the oxygen fitting, while you need to make sure that the gas fitting will remain free.
- Then you need to set the level of oxygen supply to 5 atmospheres, after which you need to open valves that regulate the flow of gas and oxygen. Touch your finger at a free fitting. so you will learn about the presence of air leaks. In the absence of it, you will have to clean the injector and blow the channels of the cutter.
- After that, you need to make sure whether the detachable compounds are tight. If you manage to identify a leak, it is eliminated by pulling the nuts or replacing the seals. You should also make sure that the fasteners of gas reducers are tight enough, whether the manometers are in the working state.
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 “sniffling” or flame is unstable, it should be slightly reduced to the volume of oxygen supplied.
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.
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.