Welding: welding methods and technology.

Welding - is receipt of permanent joints by heating and melting the edges of the parts.Whereas previously it was only metals, but today this method is combined, and other materials such as plastic.

can talk about that a welded joint - this is something which was obtained by melting or welding pressure.Of course, there are lots of methods to obtain the desired result.For example, there is an element such as an electric arc, it is with her assistance and welding.Welding processes have a variety, we will consider them all.

bit of history.Classification

Forging metal - the first welding process.The need for repair of metal products, as well as the creation of more advanced parts was a prerequisite to the development of welding processes.Thus, in the years 1800-1802 was opened on the arc.Since it did various experiments.Eventually people learned how to make welded joints by means of an electric arc.On the territory of Russia is actively preparing skilled welders is constantly developing new technologi

es, fundamentally different approaches, etc.A striking example of an excellent theoretical and practical base is a training institute named after Bauman.

Currently, there are about 150 methods by which welding is carried out.Welding processes are separated by physical, technical and technological features.Thus, the physical parameters can be divided into three large groups:

  • Thermal - this type of welding carried out using thermal energy.These include gas, electric arc, laser and others. Welding.
  • thermomechanical - type of welding involves the use of not only the heat but also pressure.This can be a contact, diffusion, forge connections, etc.
  • Mechanical Welding .In such cases, the mechanical energy is used.The most widespread cold welding, explosion, friction and others.

Every single different kind of energy consumption, environmental friendliness, as well as the equipment used during the operation.

flame welding

In this case, the main source of heat acts flame, which is released in the combustion of fuel in a mixture with oxygen.Today we know more than a dozen gases that can be used.The most popular - is acetylene, IAF, propane and butane.The heat melts the surface with the filler material.

operator adjusts the character of the flame.It may be an oxidizing, neutral or reducing, depending on the amount of oxygen in the gas mixture.In recent years, the IAF used, which not only provides high welding speed, but also the excellent quality of the weld.But at the same time the need to use more costly wire with a high content of manganese and silicon.Today is the actual formula for gas welding, due to security and high temperature combustion in oxygen (2430 degrees Celsius).

Much depends on the composition of the metal, which is scheduled to be welded.Thus, according to the parameter number selected welding rods, and with allowance for the thickness of the metal - their diameter.With careful pre-preparation is obtained ideal welding.

all welding methods (gas) have in common, which is a smooth surface temperature.That is why they are suitable for steel sheets to 0.5-5 mm, nonferrous metals, as well as tool steel and cast iron.

Let's take a closer look at some ways of gas welding.They are quite a lot.

left, right and through-welding

sheet thickness of 5 mm is most often used form of left-gas welding.Accordingly, the burner is moved from right to left, and the filler rod is ahead.The flame is directed from the seam and well heated and processed place filler wire.Equipment varies depending on the thickness of the metal.If the sheet is less than 8 mm, the burner moves only along the seam.If more than 8 mm, it is necessary to simultaneously perform oscillating motion in the transverse direction for improved weld quality.The advantage of the left method is that the operator can clearly see a target place, and it can ensure uniformity.

principal difference between the right welding in that it is more economical.This is due to the fact that the flame is not directed against the seam, and to him.This approach allows the weld metals of the maximum thickness, wherein the opening angle of the edges is small.The burner moves from left to right, and behind it is the filler rod.

Of course, if we consider the methods of gas welding, it is certainly worth a mention through-welding roller.It is used when you need to get the vertical butt joint.The point is that the bottom of the joint is small through hole.When you move the upper part of the burner holes is melted, and when injected additive sealed lower part.When the thickness of the sheet is too large, the work is carried out on both sides and is performed by two operators.

Vanny method of welding reinforcement

Many of us are familiar with the valve, which is widely used in cast-frame construction.It is used in the blocks overlap, stilts, etc.Let's take a closer look at features such welding.Most often it is used for the horizontal bars.The method consists in the fact that at the joint is welded steel mold.Then it creates a pool of molten metal due to arc heat.It turns out that the ends of the welding fixtures are melted and form a common bath.Accordingly, during the cooling formed a complete connection.

But before the bathroom need to prepare welding rods.This is done as follows: the surface and stripped ends, with any kind of contamination is removed, for example, rust, scale and dirt.For this approach, metal brush.Incidentally, it is important to strip the valve to the length of 30 mm at the weld.The rods are mounted coaxially.When this gap should not exceed half the diameter of the electrode (at the end).

process takes place under high currents.For example, when the electrode is 6 mm welder working at a current of 450 amps.If it is a low temperature, the current is increased by 10-12%.In addition, the work can be performed by several electrodes.It is worth paying attention to the fact that this method allows to reduce the complexity of the process, the cost of the product, as well as power consumption.Today vanny method of welding reinforcement is the most popular and reliable.This is due to low power consumption and high quality connections.

Welding pressure (plastic)

This type of welding is also called cold.This is due to the fact that during a connection fails additional heating of the treated surface.This method relies on the plastic deformation of metals under compression or sliding.Works are carried out under normal or negative temperatures without diffusion.This method is one of the oldest.

To obtain high weld quality using special devices that cause deformation of the processed surfaces, which must be previously cleaned.The result is a monolithic and quite firm connection.There are various kinds of welding methods, and (plastic).Currently, there are three: Spot, seam and butt.

cold welding can be joined materials such as copper, lead, aluminum, cadmium, iron and others. The most preferred plastic welding is when it is necessary to perform work with dissimilar materials, which are quite sensitive to heat.

Of course, it should be noted that the main and most important advantage of the pressure welding is that it is not necessary to connect a powerful source of electric power for preheating the surface.Furthermore, the seam, thus obtained, is not only durable, but also uniform and resistant to corrosion.Nevertheless, there are some drawbacks.They consist in the fact that you can work only with high ductility metals.If one pipe welding methods may be used, other - No need to use melting.This applies to water mains and gas lines.

Classification of welding methods.Continued

process itself proceeds as follows.Details to be connected, set in close proximity to each other.After that fed a powerful source of heat, which melts the mating parts.

molten metal (without any additional mechanical effects) is added to the common weld pool.When the heat source is removed from the weld seam is cooled, and the deposited metal forms a very strong connection.The main problem is that the heat source should have high power and temperature.For example, to work with the steel, cast iron or copper need device temperature 3000 degrees Celsius.If you deliberately lower the figure, the welding productivity will plummet, and the process will be ineffective.

Classification fusion welding methods, depending on the heat source there is the following:

  • Arc welding. as a heat source electric arc which burns between the electrode and the work piece.
  • Plasma welding. heat source - compressed electric arc.Through her at high speed (supersonic) gas is blown, which acquires the properties of plasma.
  • Electroslag - the metal is heated by the molten flux, through which electric current flows.
  • Electron beam welding - Heating is provided by the kinematic energy of the electrons.They move in a vacuum under the influence of an electric field.
  • Laser welding is performed by heating the metal through the optical beam maser.The range of radiation can be light or infrared.
  • Gas welding - melting surface to be treated by the combustion of gas-oxygen mixture.

Arc welding and its species

To date, the most important for many industries is arc welding.If you count the number of operating systems, employment of experts, as well as the number of products, such a method of producing high-quality joints in the lead all over the world.Let's consider the basic methods of arc welding.To date, there are several.

The most common is the automatic welding.Its essence lies in the fact that some movements are automated operator.For example, the supply electrode and its movement along the seam are made without human intervention (as opposed to semi-automatic mode).This is good in that the weld quality and productivity increase somewhat, and reduced risk of injury.Often used shielding gas, which is needed to prevent the nitriding and oxidation of the welded joint during the execution of works.

There is also a manual welding, which is that the melting edge of the touch and excite the arc (with non-consumable electrode).After the filler material is heated and melted, it turns bath which subsequently creates the seam.It is necessary to draw your attention to the fact that methods of welding electrodes using an electric arc are classified according to several technical features.For example, the type of gases used (active and inert), the degree of mechanization (manual, automatic, etc.) and on other grounds.

For more information on manual arc welding

We have already discussed in general terms the principle of producing a welded joint in the manual mode.Let's look at this issue in more detail.To date, there are ways of manual arc welding, each of which is unique in its own way.For example, the process can be used various electrodes: melt and non-consumable.If the second type is selected, the connection seam as follows: the edges is applied to each other, and graphite or carbon electrode brings to the treated surface and create the arc.The result is a bath which solidifies after some time and form the weld.This method is most relevant for working with non-ferrous metals and their alloys, and also used for surfacing.

Another way is to use a consumable electrode with a special daubing.This method can be called a classic, in terms of manual welding, as it is the most common and is used for a long time.The only difference from the method described above is that the electrode is melted together with the surface.The result is a total bath which solidifies after removal of the arc and forms a high quality weld.Selection of welding method depends on the particular situation, material, composition and much more.

few important points

We reviewed the main methods of welding.They are conventionally divided into three groups: cold and hot gas.However, it is worth noting that sometimes uses special methods of producing the seam.We need it if we are talking about reactive metals and their alloys.By the way, these materials are increasingly used in construction for the construction of critical parts.In such cases, the work is done at a low content of oxygen and nitrogen in the air, and the source must be a high temperature.A striking example is the plasma and beam welding.The second case is similar to the beam source has a voltage of kinescope and about 30-100 kV.

much more difficult and more interesting from the point of view of obtaining secure connections plasma welding.With its essence, we have a little understood.While there are some key features as electric conductivity of the plasma current.Gas plasma is formed, in addition to its main task also protects the weld from oxidation and nitration.It's safe to say that this method is worthy of attention, but there are some limitations.For example, the power source must have a voltage of 120 V, and the installation is very expensive and complex.

Conclusion

Here we deal with the fact that such welding.There are various methods of welding.In most cases, the task of the operator to obtain not only a qualitative, but also durable joint that will withstand the mechanical stresses for a long time.There are various methods of welding electrode, for example, consumable or not.In addition, the technology can vary depending on the technology wizard.Someone is convenient to carry out welding work left, someone - right.

even basic methods of welding reinforcement must be carried out according to the instructions.Agree, would not be very nice if the partition filled up because the welder shalturil and decided to save a little.

Today becoming more common types of complicated and expensive preparation of a compound.This is due to several factors.Firstly, the technological progress causes it is not always possible to use forge welding because of the fragility structure.Second, try to get a high quality weld, which are not destroyed during longer be dynamic and vibratory loads.It is not difficult to achieve, especially when you consider that shock and vibration - the most important enemies of the welded joint.But modern welding (welding process) is constantly being improved, develop new and innovative approaches to strengthening and getting strong and high-quality joints.