welding process

 

Welding process

  The welding process in this way is divided into" right "and" left " techniques.

 The most common is the "left" method. It can be used when connecting metals that do not have too high a melting point and a small thickness. The "right" method is used to connect metal products with a thickness of more than three millimeters, which have increased thermal conductivity. Thanks to the better protection of the metal, the seam turns out to be of higher quality, the process speed is increased, and the gas consumption is 10% less.

 With the "right" method, the direction of movement of the burner is from left to right, and the filler wire is moved after the burner. At the same time, the flame is directed to the already prepared section of the seam, and the filler wire is moved after the burner. With the" right " method of thick parts, preliminary cutting of the edges of the parts is necessary.

 The mouthpiece is used to oscillate with a small amplitude, except when thin-walled sheets are welded. The flame of the burner is directed in such a way that the edges of the parts are located in the recovery zone and are at a distance of 2-6 millimeters from the end of the flame. The mouthpiece of the burner can be perpendicular to the surface or be inclined to it.

 The technical process for gas welding assumes that before starting work, it is necessary to check the working condition of the burner:

 The quality of the hose connection.

The presence of a vacuum.

Gas tightness.

Before connecting oxygen and acetylene hoses to the burner, they must be purged. To check the reliability of the hose connection, follow these steps:

 

connect the oxygen supply hose to the burner nozzle;

check the burner for vacuum in the channel where acetylene is supplied;

attach the acetylene supply hose;

check the reliability of fixing the hoses with the clamps designed for this purpose.

Instead of clamps, you can fix the hoses with wire. Cap nuts with right or left threads are also used.

 Checking for rarefaction or otherwise "suction" should be carried out as follows:

 secure the tip with a cap nut;

attach the oxygen supply hose to the nipple;

following the readings of the pressure gauge, set the oxygen pressure;

open the valves - first acetylene, and then oxygen;

bring your finger to the acetylene nipple.

If the finger is sucked, it will mean that there is a vacuum. In its absence, you should:

 close the oxygen valve and disconnect the tip;

turn the injector out of the mixing chamber by half a turn;

assemble the burner and re-check it;

if there is still no vacuum, then you will have to remove the tip, remove the injector and the mouthpiece, and check whether the holes in them are not clogged;

if necessary, clean the holes with soft wire and blow with air;

check the tight fit of the injector to the seat of the burner body and, if necessary, strengthen it.

Then a gas tightness check is carried out:

 connect the oxygen supply hose alternately to the acetylene and oxygen nipples;

apply oxygen under pressure;

lower the mouthpiece into the water for a few moments.

 In the absence of gas impermeability, bubbles should not appear on the water surface. Gas best portable welding machine shows itself well when welding by the butt method. However, it is not recommended to use it for the formation of joints by the overlap method and the T-shaped method, since this requires strong heating of the parts.

 The welding process should be carried out when the burner moves only in one direction - along the axis of the seam. The absence of vibrations leads to the formation of a narrower seam than when welding is carried out with coated electrodes. To avoid splashing, the end of the wire should be fed smoothly into the bath. The degree of penetration can be judged by the appearance of the bath. With normal penetration, it will be stretched along the direction of the seam, and with a bad shape of the bath will have a round or oval shape.

 The end of welding and welding of the crater is carried out, gradually reducing the current strength with the help of a rheostat included in the welding circuit. By extending the arc, removing the burner, it is not recommended to stop welding, since this method will worsen the protection of the seam with gas. The gas supply should be stopped only after a few seconds after the arc gorenje stops.

 Semi-automatic welding

All types of welding work include another popular type-welding with a semi-automatic machine. Semi-automatic welding can be called a kind of arc welding. The difference lies in the fact that at the same time the wire is fed into the welding zone and the gas is exposed, which protects all materials from the negative effects of the surrounding air, which can slow down the process or even completely stop it.

When welding with semi-automatic machines takes place in carbon dioxide, this type is called MAG, and if in inert, then MIG. Semi-automatic welding machines belong to a simple type of equipment. Its main parts consist of a direct current source that provides voltage supply, and a special mechanism for supplying a wire that plays the role of an electrode to the welding zone. The wire is wound on a special bobbin. The speed of its supply is adjustable.

 The advantages of this method include the ability to work in hard-to-reach places, a small amount of waste, obtaining a thin and strong seam, and the speed of the process. Aluminum or steel wires are used in semi-automatic machines. Protection of the resulting seam is possible in the following ways: flux; protective gases; using a powder type of wire. Protective gases are most often used. There are stationary devices and household ones that are more convenient for home use.

  In the case of the semi-automatic there is a control unit and a power source. With the help of cables, a wire feed mechanism wound on a coil and a welding torch are connected to the device.

 Wire feeding is carried out in one of three ways:

 

Pulling. The drive is located on the burner handle. The wire is pulled from the bobbin on which it is wound.

Pushing. The drive pushes the wire towards the burner.

The pull-push feed is a hybrid of the two previous methods.

With the help of a welding sleeve, gas, wire and, in some models, liquid for cooling are supplied to the work site. The length of the hose determines the possibility of working in hard-to-reach places. A unified connector is used to connect the welding sleeve.

 In the center there is a large fitting through which the output of the welding wire is carried out. At the top there are two contacts for switching modes. Wires for supplying current are connected to the connector. A burner is also connected to the hose. The contact tip is a replaceable part. It is selected depending on the diameters of the wire used. In turn, the size of the nozzle depends on the diameter of the tip.

 The wire is wound on the coils. They have different sizes depending on the diameter of the wire. The wire feeder has a roller mechanism. The rotation of the feed device is carried out by means of an electric motor. The wire tension is adjusted manually by the operator. The welding wire enters the welding zone continuously. An arc occurs between the wire and the parts to be welded. The nozzle is used to form a gas cloud.

 Semi-automatic welding is possible without the use of gas. In this case, it is necessary to use a special type of wire, inside which there is a flux. Such a wire is called powder wire. When the wire is burned, the released flux creates a protective environment. If you are going to weld critical structures, then you should choose gas welding, which is more reliable. A competent choice of welding wire is necessary.

 The main criterion is the correspondence of the wire composition to the material of the products being welded. Marking the wires will help this. The choice of the wire diameter depends on the thickness of the products. The theory of metal welding assumes the dependence of the exposed welding current on the thickness of the materials and the selected diameter of the electrodes.

 It is necessary to establish the speed at which the wire will be fed, as well as the gas flow rate, which is set using a valve on the gearbox. The main feature of using a semi-automatic machine is that at first the wire is fed mechanically towards the welding site, but then it is moved manually.

 

Automatic welding

This type of welding, which has many advantages, is often used in industrial production. It can be called the highest degree of mechanization of electric arc welding, performed under the protection of a flux.

The wire feed is fully mechanized. The welder only needs to know how to set up the equipment used and start it. The resulting seam is smooth and beautiful due to the fact that during the entire process, the arc is maintained evenly gorenje.

 TIG welding

It is one of the modern methods of welding various products. The essence of this method is the gorenje of an electric arc in argon - a gas that has a number of remarkable qualities. Since it is heavier than air, after penetration into the welding bath, argon begins to protect it from other gases living in the atmosphere. As a result, the seam is obtained without an oxide film.

 In this method, a tungsten electrode is used, which makes it possible to weld various types of steel. It requires constant care, which consists in regular sharpening of its tip. For ignition, an oscillator is required that generates a high-frequency current, which is connected to the inverter.

 The principle of operation of automatic argon arc welding is similar to the manual version with the difference that the control occurs automatically according to the program set by the operator. In this type of welding, an inverter is used. When welding with an inverter, the theory of the process is that such a device allows converting direct current into alternating current. In the future, the inverter can change the frequency of the received alternating current.

 Electroslag welding

It is characterized by very high performance and economy. Electroslag welding is applicable in industries of any scale. The essence of ESS is that the connection of elements occurs in a molten slag environment. An electrode is lowered into it, through which an electric current passes. Thus, heat begins to be generated in the slag.

 The equipment for ESS consists of a welding machine and additional devices for performing auxiliary functions.

 Electron beam welding

Metal welding methods include rapidly developing technologies. These include electron beam welding. Its essence lies in the fact that the heating of products and their further melting occurs under the influence of a stream of high-speed electrons that move in a vacuum under the influence of an electric field.

 Under the influence of a focused flow of electrons, the edges of the parts are melted and their connection occurs. The range of its capabilities is very extensive - refractory and chemically active metals, strong alloys.

 The features of this type of welding include the fact that since welding takes place in a vacuum, the surfaces of the parts remain clean, as well as the fact that the seam is obtained quickly and of minimal thickness. It retains an increased quality even if parts of different thicknesses are welded, having different composition and melting point. The welding equipment has simple operation and does not require long training.

 Diffusion welding

Modern welding methods also include such a type as diffusion welding. Its essence lies in the fact that there is a mutual penetration of the atoms of the connected parts when they are strongly squeezed and heated to a certain temperature.

 The heating temperature depends on the properties of the metal, but is not too high.

 Contact welding

During contact welding, an all-in-one connection is formed by heating the parts with an electric current passing through them and applying pressure. The field of use is industrial production, mass and serial.

 The following types of contact welding are available:

1.  point map;
2. butt;
3. suture;
4. relief;
5. suture-butt.

Spot welding has become the most widespread. The technical process of welding in this way consists in connecting parts in one or more places, depending on their length.

 Up to its melting point, the metal does not heat up along its entire length, but only at certain points. The seam turns out to be reliable and aesthetic. The use of this method reduces the time of the welding process. The number of controlled parameters is insignificant, so there are no special requirements for the qualification of a welder.