How to use electric welding. What does a novice welder need to get started?

To be able to carry out work at any time in a home workshop or on personal plot work related to connecting elements metal structures, it is enough to purchase a modern welding machine and learn how to weld welding inverter.

Welding work has long been widespread not only in serious production, but also in everyday life.

Design and advantages of inverter welding machines

The great popularity of inverter equipment among home craftsmen is explained by the fact that with the help of such compact devices, which are also lightweight, it is possible to make high-quality, reliable and accurate welded joints, even without high qualifications.

The design of any welding inverter consists of such elements as:

• power supply with rectifier unit and filter;
• inverter unit that converts direct current into high-frequency alternating current;
• transformer for reducing the voltage of high-frequency current;
• power rectifier designed to obtain direct current at the device output;
• an electronic unit that performs device control functions.

Innovative technologies implemented in the design of inverters make it possible to obtain high-quality welded joints without any problems. Due to their compactness, such devices do not take up much space, and due to their light weight (5–15 kg), they can be moved anywhere without much difficulty.

If you learn how to work correctly, you can use it to weld any metal structures. Each new inverter comes with instructions, from which the owner of the equipment can glean a lot of useful information: how to properly connect the device, which electrode to choose in order to weld products from a particular metal, etc.

Patterns of electrode movement depending on the type of seam (click to enlarge)

However, often an inverter device falls into the hands of a home craftsman, the instructions for which are not translated into Russian or are missing altogether. It is very important to learn correctly, because if you act at random, it will be difficult to weld metal well. In addition, you may encounter equipment failure.

However, if you follow generally accepted rules, you can work on any model of inverter and effectively solve all the tasks. After carefully studying these rules, watch the training video, which will help reinforce the theoretical material with visuals.

How to prepare equipment for operation

Before you start welding metal, prepare all the necessary equipment to ensure your safety: a welding mask, special clothing made of thick fabric, work shoes and gloves, which should also be made of dense material.

In order for the weld to be of high quality, it is necessary to select the correct electrodes. Their type and diameter are selected depending on the metal from which the parts being joined are made, the thickness of the latter, as well as the welding modes. Since the surfaces of the workpieces to be welded must be thoroughly cleaned, you also need to prepare a brush with metal wire bristles.

Before connecting the inverter to the electrical network, you need to check whether the network parameters correspond to the characteristics of the connected equipment.

These parameters include strength electric current and the voltage value, which must be within the range specified in the inverter passport. The device should be connected to the power supply through an automatic circuit breaker, which will prevent equipment breakdown if a short circuit occurs in its electrical circuit or the voltage increases sharply for another reason.

Before starting welding, it is necessary to take care of the condition of the working site. The inverter should be installed on a flat surface, and there should be enough space around its body to ensure free movement of air, due to which natural ventilation devices. Do not cover the device body with fabric, which will restrict the flow of air to its ventilation grilles.

The welding process is accompanied by high temperatures and splashing of molten metal, so there should be no flammable, fire or explosive substances on the work site.

After everything preparatory activities completed, the safety requirements are met, you can proceed to the following actions:

• connection power cable and ground cable to the corresponding connectors of the inverter;
• fixing the mass cable on the parts to be welded (a special clamp is used for this);
• connecting the device to the power supply and setting welding operating modes on it;
• fixing the electrode in the welding holder.

The sequence and correctness of performing such actions is well demonstrated by the training video. Now that the inverter is connected to the electrical network and the electrode in its holder is ready for use, you can begin welding.

Features of welding work using inverter devices

The first thing you need to do to start cooking with an inverter is to light an electric arc between the surface of the part and the tip of the electrode. To do this, the latter makes a scratching movement along the surface of the workpiece, as a result of which a bright flash should appear. The metal in the arc zone will begin to melt. You can learn how to light an arc correctly and do it quickly by watching a training video.

When performing welding, it is important to monitor the length of the arc, which should approximately correspond to the diameter of the electrode used (in this case, the parts will be evenly melted, which will allow the formation of a high-quality weld). It is necessary to ensure that such penetration occurs evenly throughout the entire welding process.

The quality and reliability of the weld is also influenced by the polarity of connecting the inverter power cable and the ground cable. To choose this polarity correctly, you need to know exactly what material the parts being connected are made of. Most grades of steel and other metals are best welded with direct polarity; only some alloys are combined with reverse polarity.

The design of modern welding inverters ensures smooth and efficient regulation of the operating current, which makes working with such devices simple and comfortable even for novice welders. You can judge that the welding current is selected incorrectly based on a number of factors. So, if it is too small, then the weld seam turns out to be too convex and narrow, and the parts in such cases are poorly fused. If the current is too high, then intense spattering of molten metal occurs, and burns may appear on the surface of the parts being connected.

The choice of welding current depends on the diameter of the electrode you are going to weld with. Thus, when welding metal with a thickness of one to three millimeters with electrodes with a diameter of up to 1.5 mm, the welding current strength is selected in the range of 20–60 A. In the event that larger diameter rods are used, which can be used to weld metal 4–5 mm thick, the strength welding current is selected within 100 A.

By watching a training video or following the work qualified specialist, novice welders are often interested in why slag is knocked off the surface of the finished weld. This is done in order, firstly, to check the quality of the weld, and secondly, to give the finished joint an attractive appearance. A seam cleared of slag shows all the mistakes made during welding.

Of course, you should not expect that novice welders (or so-called dummies) will immediately produce beautiful and high-quality welds. Mastery, including in welding, does not come immediately after familiarizing yourself with theoretical material and watching videos; it is developed only through experience.

How to choose the right welding inverter and electrodes for it

Correctly selected electrodes play a big role in the formation of a high-quality and reliable welded joint. It is impossible to learn how to choose them from a video; to do this, you should adhere to generally accepted recommendations and the following principles.

• When working with medium and low carbon steels, carbon electrodes are used.
• Alloy steels are welded using electrodes produced in accordance with GOST 10052-75 and 9466-75.
• For welding cast iron products, OZCh-2 grade products are used.

Classification of electrodes by type and purpose (click to enlarge)

Proficiency in electric welding is a skill that is always useful in construction and everyday life. At the moment there is no other way to connect metal elements like welding. You can learn this craft on your own by mastering the basic skills of a welder and performing simple welding work. Let's look at where to start learning electric welding for beginners and what you will need for this.

Electric welding training is a practical process that requires some preparation. First of all, you need to take care of safety. The work of a welder is quite dangerous:

• Possibility of burns from splashes of molten metal;
• Poisoning by toxic secretions at high temperatures;
• Possibility of electric shock;
• Eye injury due to failure to wear safety glasses.

The correct choice of equipment and equipment for electric welding is the key to the safety of the process. For welding work required:

1. A suit made of thick fabric that completely covers the body, arms and legs;
2. Special glasses can be used to protect your eyes, but we recommend paying attention to masks. They will also protect the face and are safer during the welding process;
3. High-quality welding equipment;
4. Electrodes;
5. A bucket of water to eliminate possible fires;
6. The correct location for welding. Preferably located at outdoors and remove all nearby flammable objects.

The modern market offers a wide selection of electric welding machines, the variety of which comes down to three main types:

• A transformer that converts alternating current for welding work. This type of welding machine often does not produce a stable electric arc, but consumes a lot of voltage;
• The rectifier converts into direct current from the consumer network. These devices allow you to obtain an electric arc of high stability;
• The inverter allows you to convert current from the household network into direct current for welding. These units are characterized by ease of arc ignition and high performance.

Welding for beginners: video lessons - watch and learn the nuances.

Beginners are advised to choose solid rod type electrodes that are coated with a melting compound. With such electrodes it will be easier for a novice welder to make an even seam. The size of the rods for a beginner is 3 mm.

Electric welding training

Connecting the electrode and striking the arc

The electric welding process for beginners and experienced welders begins with connecting the electrode and igniting the arc. It is more convenient to start welding lessons with universal electrodes with a diameter of 3.2 mm. Such electrodes have a higher price, but they greatly facilitate the welder’s work.

First stage of training: rollers

You must begin your training in the basics of electric welding with beads - welding seams on thick pieces of metal, where the skills of using an electric arc and welding seams are practiced.

The sequence for creating rollers is as follows:

• For testing, a thick sheet of metal is taken, cleaned of rust and dirt;
• All manipulations with welding machine and arc are produced in a suit and with glasses for the eyes!
• After ignition, the arc is brought to the metal at a distance in the range of 3-5 mm. It is important to ensure that the distance between the workpiece and the arc is the same; this is the key to an even and uniform seam. The electrode is held at an angle;
• It is important to understand whether the current supplied by the welding machine is sufficient. If the arc goes out, then the voltage must be added. If the voltage is too high, the arc will not melt, but cut the metal;
• Let's consider the structure of the metal in contact with the arc. It is important to understand where the weld pool is formed during welding and monitor it. This area of ​​molten metal will have a whitish color with characteristic ripples. liquid metal on a surface;
• When a weld pool appears under the ignited arc, you can begin to make a seam by moving the electrode. The bath will follow the arc, and the pressure of the arc will force the bath to also move in the opposite direction, resulting in a roller;
• When creating rollers, it is necessary to adhere to certain patterns of movement of the electrode - these can be translational movements with a small and always equal amplitude to create an even and beautiful seam.

After the metal has cooled, it is necessary to use a hammer to chop off the slag from the surface of the bath and make a detailed inspection of the work done. If there are uncooked elements, then it is necessary to add current. If the current is excessively high, this will be visible by large burning of the metal.

Welded joints

Do-it-yourself electric welding involves creating welded joints. You can start practicing them after mastering rollers. This requires practical skill in using a welding machine, which is why it is so important to practice your movements on workpieces before moving on to welding elements.

It is recommended to start welding joints of metal elements on small workpieces. The sequence of work is as follows:

• Before welding, the parts are fastened in the required position using auxiliary tools;
• First of all, tacks are made - spot seams in increments of 8-10 cm, which fasten metal elements in certain places. This is necessary in order to give the workpiece a certain strength and the metal does not warp when making a long seam. Making such tacks also makes it much easier to create the main long seam. As a rule, tacks are made on both sides of the part;
• After the tacks are completed, a common seam is created that welds the edges of the two metal elements. Here it is important to move the electric arc with sufficient amplitude, raking the molten metal into the weld pool from both planes to be welded.

After cooling, the seam is hammered off the slag and checked for quality. If there are defects or uncooked areas, they must be brewed again.

Let's sum it up

Electric welding is a useful skill in everyday life and construction. It is possible to master it on your own. Such training will be based on:

• understanding the theory of the welding process, necessary for correctly setting up the welding machine and carrying out metal welding work;
• compliance with safety rules when welding, which boils down to the use of a protective suit, goggles or mask, and welding away from flammable objects;
• practical experience, which begins with the ability to strike an arc and weld beads.

Don’t despair if your first electric welding experiments don’t please you beautiful seams. Believe me, every experienced welder has similar welding skeletons. The ability to create not only high-quality, but also visually attractive seams will come with experience and frequent welding practice.

Current page: 1 (book has 17 pages in total)

Evgeniy Maksimovich Kostenko

Welding work: Practical guide for electric and gas welder

Introduction

In the context of scientific and technological progress, the development of the areas of science, technology and production that define it is especially important. These may include welding and cutting of metals, which in many industries are one of the main factors determining the pace of technical progress and have a significant impact on the efficiency of social production. There is practically no branch of mechanical engineering, instrument making and construction in which welding and cutting of metals are not used.

The welded design of many types of metal structures has made it possible to most effectively use workpieces obtained by rolling, bending, stamping, casting and forging, as well as metals with different physical and chemical properties. Welded structures, compared to cast, forged, riveted, etc., are lighter and less labor-intensive. Using welding, permanent joints of almost all metals and alloys are obtained various thicknesses– from hundredths of a millimeter to several meters.

The founders of electric arc welding of metals and alloys are Russian scientists and inventors.

In terms of the level of development of welding production, the USSR was the leading country in the world. And for the first time he carried out an experiment on manual welding, cutting, soldering and spraying metals in outer space.

Work is being successfully carried out at a specialized institute for welding profiles - the Institute of Electric Welding named after. E. O. Paton Academy of Sciences of Ukraine (IES).

The growth of technical progress - the introduction of complex welding equipment, automatic lines, welding robots, etc. - increases the requirements for the level of general educational and technical training of welding workers. The purpose of this book is to help students of vocational schools, training centers, as well as students preparing for production to master the profession of an electric and gas welder.

Section one

GENERAL INFORMATION ABOUT WELDING, WELDED JOINTS AND SEAMS

BRIEF CHARACTERISTICS OF THE MAIN TYPES OF WELDING

1. General information about the main types of welding

Welding is the process of obtaining permanent connections by establishing interatomic bonds between the parts being welded when they are heated or plastically deformed, or the combined action of both (in accordance with existing standards).

There are two main, most common types of welding: fusion welding and pressure welding.

The essence of fusion welding consists in the fact that the metal along the edges of the parts being welded is melted under the influence of the heat of the heating source. The heating source can be an electric arc, gas flame, molten slag, plasma, or laser beam energy. In all types of fusion welding, the resulting liquid metal of one edge is combined and mixed with the liquid metal of the other edge, creating a total volume of liquid metal, which is called the weld pool. After the metal of the weld pool has solidified, a weld is formed.

The essence of pressure welding consists of plastic deformation of the metal along the edges of the parts being welded by compressing them under load at a temperature below the melting point. The weld is produced as a result of plastic deformation. Pressure welding can only weld plastic metals well: copper, aluminum, lead, etc. (cold welding).

Among the great variety various types In fusion welding, the leading place is occupied by arc welding, in which the heat source is an electric arc.

In 1802, the Russian scientist V.V. Petrov discovered the phenomenon of an electric arc discharge and pointed out the possibility of using it to melt metals. With his discovery, Petrov laid the foundation for the development of new branches of technical knowledge and science, which later received practical use in electric arc lighting, and then with electric heating, melting and welding of metals.

In 1882, scientist-engineer N.N. Benardos, working on the creation of large batteries, discovered a method of electric arc welding of metals with a non-consumable carbon electrode. He developed a method of gas-shielded arc welding and arc cutting of metals.

In 1888, the scientist-engineer N. G. Slavyanov proposed welding with a consumable metal electrode. The name of Slavyanov is associated with the development of the metallurgical foundations of electric arc welding, the creation of the first automatic regulator arc length and the first welding generator. They were offered fluxes to obtain high-quality weld metal. (The Moscow Polytechnic Museum has an authentic Slavyanov welding generator and exhibits samples of welded joints.)

In 1924-1935. They mainly used manual welding with electrodes with thin ionizing (chalk) coatings. During these years, under the leadership of Academician V.P. Vologdin, the first domestic boilers and hulls of several ships were manufactured. From 1935-1939 Thickly coated electrodes began to be used. Alloy steel was used for electrode rods, which made it possible to use welding for the manufacture of industrial equipment and building structures. In the process of developing welding production, under the leadership of E. O. Paton (1870-1953), submerged arc welding technology was developed. Submerged arc welding made it possible to increase the productivity of the process by 5-10 times, to ensure good quality welded joint by increasing the power of the welding arc and reliable protection of the molten metal from the surrounding air, mechanize and improve the production technology of welded structures. In the early 50s, the Electric Welding Institute named after. E. O. Paton developed electroslag welding, which made it possible to replace cast and forged large parts with welded ones; blanks have become more transportable and convenient for assembly and installation.

Since 1948, arc welding methods in inert shielding gases have been industrially used: manual - with a non-consumable electrode, mechanized and automatic - with a non-consumable and consumable electrode. In 1950-1952 at TsNIITmash with the participation of MVTU and IES named after. E.O. Paton developed welding of low-carbon and low-alloy steels in a carbon dioxide environment - a highly productive process that ensures good quality of welded joints. Welding in a carbon dioxide environment accounts for about 30% of the volume of all welding work in our country. The development of this welding method was led by Doctor of Sciences, Professor K.F. Lyubavsky.

During these same years, French scientists developed the new kind electric fusion welding, called electron beam welding.

This welding method is also used in our industry. For the first time in outer space, automatic welding and cutting was carried out in 1969 by cosmonauts V. Kubasov and G. Shonin. Continuing this work, in 1984, cosmonauts S. Savitskaya and V. Dzhanibekov carried out manual welding, cutting and soldering of various metals in outer space.

Fusion welding also includes gas welding, in which the heat of the flame of a mixture of gases burned with a torch is used for heating (in accordance with existing standards). The gas welding method was developed at the end of the last century, when the industrial production of oxygen, hydrogen and acetylene began. During this period, gas welding was the main method of welding metals and ensured the most durable joints. Gas welding using acetylene is most widely used. With the development of the network railways and car building, gas welding could not provide structures with increased reliability. Arc welding is becoming more widespread. With the creation and introduction into production of high-quality electrodes for manual arc welding, as well as the development various methods automatic and mechanized submerged arc welding and shielding gases, resistance welding, gas welding was forced out of many industries. However, gas welding is used in many industries in the manufacture and repair of products made of thin sheet steel, welding of products made of aluminum and its alloys, copper, brass and other non-ferrous metals and their alloys; surfacing works. A type of gas-flame processing is gas-thermal cutting, which is widely used when performing procurement operations when cutting metal.

Welding using pressure includes resistance welding, which also uses the heat generated in the contact of the parts being welded during the passage of electric current. There are spot, butt, seam and relief contact welding.

The main methods of resistance welding were developed at the end of the last century. In 1887, N. N. Benardos received a patent for methods of spot and seam contact welding between carbon electrodes. Later, these resistance welding methods, improved by the use of electrodes made of copper and its alloys, became the most widespread.

Resistance welding occupies a leading place among mechanized welding methods. In the automotive industry, resistance spot welding is the main method of joining thin-sheet stamped structures. Body of a modern passenger car welded at more than 10,000 points. A modern airliner has several million weld spots. Butt welding is used to weld joints of railway rails and joints of main pipelines. Seam welding is used in the manufacture of gas tanks. Relief welding is the most highly productive method of welding reinforcement for building reinforced concrete structures.

The peculiarity of contact welding is the high heating rate and the formation of a weld. This creates conditions for the use of high-performance production and automatic assembly lines for automobile components, heating radiators, elements of devices and radio circuits.

Control questions:

1. What is called welding and what are the main two types of welding do you know?

2. Explain the essence of fusion welding and pressure welding.

3. Tell us about new types of welding.

4. What do you know about the use of gas welding?

5. What do you know about resistance welding and its advantages?

2. Classification of fusion welding

Fusion welding, depending on the various methods, the nature of the heating sources and melting of the welded edges of the parts, can be divided into the following main types:

electric arc, where the heat source is an electric arc;

electroslag welding, where the main source of heat is molten slag through which electric current flows;

electron beam, in which the heating and melting of the metal is carried out by a flow of electrons;

laser, in which heating and melting of the metal occurs with a focused powerful beam of microparticles - photons;

gas, in which the heating and melting of the metal occurs due to the heat of the flame of a gas burner.

A more detailed classification can be carried out according to other characteristics, highlighting welding with a consumable and non-consumable electrode, direct and indirect arc; open arc, submerged arc, shielding gas, arc plasma.

Arc welding is also classified depending on the degree of mechanization of the welding process, the type and polarity of the current, etc.

According to the degree of mechanization, welding is divided into manual, mechanized (semi-automatic) and automatic. Each type of welding in accordance with this classification is characterized by its own method of igniting and maintaining a certain arc length; manipulation of the electrode to give the welded seam the desired shape; a method of moving the arc along the seam line and stopping the welding process.

In manual welding, these operations are performed by a welder manually without the use of mechanisms (Fig. 1).

When welding semi-automatically with a consumable electrode, the operations of feeding the electrode wire into the welding zone are mechanized, and the remaining operations of the welding process are carried out manually by the welder (Fig. 2).

During automatic welding, operations are mechanized to excite the arc and move it along the seam line while simultaneously maintaining a certain length of the arc (Fig. 3). Automatic welding with a consumable electrode is usually performed using welding wire with a diameter of 1-6 mm; at the same time, welding modes (welding current, arc voltage, arc speed, etc.) are more stable. This ensures the quality of the weld along its length, but more careful preparation is required for assembling parts for welding.

Rice. 1. Scheme of manual welding with a covered electrode: 1 – welding arc; 2 – electrode; 3 – electrode holder; 4 - welding wires; 5 – power source (welding transformer or rectifier); 6 – part to be welded, 7 – weld pool; 8 -weld seam; 9 – slag crust

Rice. 2. Scheme of mechanized (semi-automatic) welding under a layer of flux: 1 – holder; 2 – flexible hose, 3 – cassette with welding wire; 4 – feeding mechanism; 5 -power supply (rectifier), 6 – part to be welded; 7 – weld seam; 8 – slag crust; 9 - bunker for flux

Rice. 3. Scheme of automatic submerged arc welding: 1 – arc; 2 – gas bubble (cavity); 3 – welding head; 4 – trolley (welding tractor); 5 - Remote Control; 6 - cassette with welding wire; 7 – part to be welded; 8 – weld pool; 9 – weld seam; 10 – slag crust; 11 – molten flux; 12 – unmelted flux

Control questions:

1. Name the main types of fusion welding.

2. What do you know about mechanized welding methods?

3. What are the features of automatic welding?

3. The essence of the main methods of fusion welding

In electric arc welding, the energy required to form and maintain the arc comes from DC or DC power sources. alternating current.

In the process of electric arc welding, the main part of the heat required to heat and melt the metal is obtained due to the arc discharge (arc) that occurs between the metal being welded and the electrode. When welding with a consumable electrode, under the influence of the heat of the arc, the edges of the parts being welded and the end (end) of the consumable electrode melt and a weld pool is formed. When the molten metal solidifies, a weld is formed. In this case, the weld is formed by the base metal and the electrode metal.

Consumable electrodes include steel, copper, aluminum; non-consumable - coal, graphite and tungsten. When welding with a non-consumable electrode, the weld is obtained only by melting the base metal and the metal of the filler rod.

When the arc burns and melts the welded and electrode metals, it is necessary to protect the weld pool from exposure atmospheric gases– oxygen, nitrogen and hydrogen, as they can penetrate the liquid metal and deteriorate the quality of the weld metal. According to the method of protecting the weld pool, the arc itself and the end of the heated electrode from the effects of atmospheric gases, arc welding is divided into the following types: welding with coated electrodes, gas shielding, submerged arc welding, self-shielding flux-cored wire and mixed shielding.

A coated electrode is a metal rod with a coating applied to its surface. Welding with coated electrodes improves the quality of the weld metal. Protection of the metal from the effects of atmospheric gases is carried out by slag and gases formed during the melting of the coating (coating). Coated electrodes are used for manual arc welding, during which it is necessary to feed the electrode into the arc burning zone as it melts and at the same time move the arc along the product in order to form a seam (see Fig. 1).

When submerged arc welding, the welding wire and flux are simultaneously fed into the arc combustion zone, under the influence of the heat of which the edges of the base metal, the electrode wire and part of the flux melt. A gas bubble is formed around the arc, filled with vapors of metal and flux materials. As the arc moves, the molten flux floats to the surface of the weld pool, forming slag. The molten flux protects the arc combustion zone from the effects of atmospheric gases and significantly improves the quality of the weld metal. Welding under a layer of flux is used to join medium and large thicknesses of metal using semi-automatic and automatic machines (see Fig. .3).

Welding in a shielding gas environment is performed both with a consumable electrode and with a non-consumable electrode with the supply of filler metal to the arc combustion zone to form a weld.

Welding can be manual, mechanized (semi-automatic and automatic. Carbon dioxide, argon, helium, and sometimes nitrogen for copper welding are used as shielding gases. Gas mixtures are more often used: argon + oxygen, argon + helium, argon + carbon dioxide + oxygen, etc. During the welding process, shielding gases are supplied to the arc combustion zones through the welding head and push aside atmospheric gases from the weld pool (Fig. 4). During electroslag welding, the heat that goes into melting the metal of the product and the electrode is released under the influence of an electric current passing through the slag. Welding is carried out, as a rule, with a vertical arrangement of the parts being welded and with forced formation of the weld metal (Fig. 5). The parts to be welded are assembled with a gap. To prevent liquid metal from flowing out of the gap space and forming a weld, water-cooled copper plates or sliders are pressed against the parts being welded on both sides of the gap. As the seam cools and forms, the sliders move from bottom to top.

Rice. 4. Scheme of welding in a shielded gas environment with a consumable (a) and non-consumable (b) electrode. 1 – welding head nozzle; 2 – welding arc; 3 – weld seam; 4 – part to be welded; 5 – welding wire (consumable electrode); 6 – feeding mechanism

Rice. 5. Electroslag welding diagram:

1 – parts to be welded; 2 – fixing brackets; 3 – weld seam; 4 – copper sliders (plates); 5 – slag bath; 6 - welding wire; 7 – feeding mechanism; 8 – current-carrying guide mouthpiece; 9 – metal bath; 10 – pocket – cavity for forming the beginning of the seam, 11 – lead strips

Typically, electroslag welding is used to join parts of the casings of blast furnaces, turbines and other products with a thickness of 50 mm to several meters. The electroslag process is also used to remelt steel from waste and produce castings.

Electron beam welding is carried out in a special chamber in a high vacuum (up to 13-105 Pa). The energy required to heat and melt the metal is obtained as a result of intense bombardment of the welding site by electrons rapidly moving in vacuum space. A tungsten or metal-ceramic cathode emits a stream of electrons when exposed to current low voltage. The flow of electrons is focused into a narrow beam and directed to the place where the parts are welded. To accelerate the movement of electrons, it is supplied to the cathode and anode. constant pressure up to 100 kV. Electron beam welding is widely used in welding refractory metals, chemical active metals, to obtain narrow and deep seams with high welding speeds and low residual deformations (Fig. 6).

Laser welding is a fusion welding that uses laser radiation energy for heating. The term “laser” got its name from the first letters English phrase, which translated means: “amplification of light through stimulated emission of radiation.”

Modern industrial lasers and material processing systems have shown significant advantages of laser technology in many special branches of mechanical engineering. Industrial CO2 lasers and solid-state lasers are equipped with a microprocessor control system and are used for welding, cutting, surfacing, surface treatment, piercing holes and other types of laser processing of various structural materials. Using a CO2 laser, cutting is carried out as metal materials, and non-metallic: laminated plastics, fiberglass, getinax, etc. Laser welding and cutting provide high quality and productivity.

Rice. 6. Scheme of formation of an electron beam during electron beam welding: 1 – cathode spiral; 2 – focusing head; 3 – the first anode with a hole; 4 – focusing magnetic coil to regulate the diameter of the heating spot on the part; 5 – magnetic beam deflection system; 6 – part to be welded (anode); 7 – high-voltage direct current source; 8 – focused electron beam; 9 – weld seam

Control questions:

1. What is a weld pool?

2. What does the weld metal consist of when welding with consumable and non-consumable electrodes?

3. What functions do consumable and non-consumable electrodes perform?

4. Why is it necessary to protect the weld pool, arc and end of the heated electrode?

5. What types of electric fusion welding are divided into according to the method of protection?

6. Tell us what is the essence of welding with coated electrodes?

7. How is the arc combustion zone protected during submerged arc welding?

8. What is the essence of gas shielded welding?

9. Briefly describe electroslag welding.

10. What are the advantages of electron beam and laser welding?

Carrying out manual welding using an inverter is gaining increasing popularity among home craftsmen, due to the wide offer various models with different price ranges. To connect iron products using inverter welding, a minimum of equipment is required, characterized by its versatility along with low energy consumption and compact dimensions, which further attracts the attention of inexperienced craftsmen. Learning inverter welding technology for beginners will not be the slightest difficulty.

Operating principle of a welding inverter

A welding inverter is a powerful power supply, which in terms of energy conversion is similar to a switching power supply.

The main stages of energy conversion in the inverter:

1. Reception and rectification of network current with a voltage of 220 V and a frequency of 50 Hz.
2. Converting the resulting rectified current into alternating current with a high frequency from 20 to 50 kHz.
3. Reduction and rectification of high-frequency alternating current into a current whose strength is in the range of 100 ... 200 A, and a voltage from 70 to 90 V.

Converting high-frequency electric current to a current of the required value allows you to get away from the inconvenient dimensions and heavy weight of the inverter, which are found in conventional transformer devices, in which the current value is achieved by converting the EMF in an induction coil. Also, when the welding inverter is connected to the network, there will be no sudden jumps electrical energy, and moreover, the device contains in its circuit special storage capacitors that protect the device when welding during an unexpected power outage and allow the inverter arc to be ignited more gently.

Obtaining a high-quality weld when welding depends on many factors, therefore, before starting work, the master must familiarize himself with how to properly use the inverter according to the attached instructions, as well as the basic rules and nuances of performing welding work, which will be described in detail below.

Particular attention should be paid to the diameter of the welding electrodes. It is important to know that the amount of energy consumed directly depends on the thickness of the welding rods, and, accordingly, the larger their diameter, the higher the energy consumption. This information will help to correctly calculate the maximum electrical energy consumption of the inverter, which will prevent adverse consequences from its operation as reflected on household appliances. There is also a dependence of the diameter of the electrode on the current selected for the work, a decrease in which will lead to deterioration in the quality of the seam, and an increase - to an excessive combustion rate of the welded rod.

Inverter design for welding

In order to understand how to properly use a welding machine, a novice master should familiarize himself with the design of the inverter.

Welding inverter is metal box with an internal component, a total weight of about 7 kg, which is equipped with a handle and a shoulder strap for ease of carrying. The housing of the welding inverter may contain ventilation holes, which contribute to better air outflow when cooling the unit. The front panel has buttons for switching the operating state, knobs for selecting the required voltage and current, outputs for connecting work cables, as well as indicators indicating the presence of power and overheating of the inverter during welding. The cable for connecting the device to the power supply is usually connected to the connector located on the back of the inverter.

When the electrode comes into contact with the metal plates being welded during welding, a high-temperature arc is formed, as a result of which both the elements of the welded rod and the metal of the welded joint melt. The bath formed in the arc area by the molten metals of the plates and electrode is protected from oxidation by a liquefied coating of the electrode. After complete cooling of the metal, the upper surface of the seam, protected by electrode coating during welding, will turn into hardened slag, which can be easily removed by light mechanical action (for example, tapping). It is important to maintain the same distance-gap between the metal of the welded joint and the electrode (arc length), which will prevent its extinction. To do this, the supply of the electrode to the fusion area must be carried out at a constant speed, and the guidance of the welding rod along the weld joint must be smooth.

Safety precautions

Before starting home welding, the electric welder needs to take care of safety precautions:

• wear a protective suit made of durable, high-density natural fabric that is not subject to fire and melting when sparks hit it. The suit should cover the neck area and have sleeves that fasten tightly at the wrist.
• protect your hands with mittens made of rough fabric;
• put on comfortable shoes leather shoes with thick soles;
• Protect your eyes with a welder's mask with a light filter that depends on the current strength during welding.

The place where welding will be carried out must also be carefully prepared:

• laid down wood flooring, performing a protective function against possible electric shock;
• the welding site is cleared of anything unnecessary (to prevent welding splashes);
• lighting must be of high quality;
• The welder's movements should not be constrained.

Basics of welding with an inverter

Learning to weld with a welding inverter is not difficult. The very first stage of mastering welding techniques will be preparing the metal plates to be welded:

• cleaning the edges of the plates from traces of corrosion with a wire brush;
• degreasing the edge with a solvent.

Relying on the diameter of the electrodes, the choice of which is based on the grade of the metal being welded, it is necessary to select the current value for welding. The value of the welding current will also be determined by the cross-section of the elements being welded. To ensure that the quality of the seam is not affected when welding with an inverter, the pre-welded rods should be dried in an oven with a heating temperature of 200 º for 2-3 hours.

In order to weld metal, the ground terminal must be connected to the plane of the element being welded. Next you need to ignite the arc. You can do this in two ways:

• swiping on metal surface plates, similar to igniting a match head;
• tapping the electrode on the surface to be welded.

Working with a welding inverter will be more convenient if, when welding, the holder cable is pressed to the body, having first wrapped it around the forearm of the working hand. In this position, the cable will not pull towards the holders and adjusting its position will be more convenient. Therefore, when choosing an inverter Special attention it is necessary to pay attention to the length and flexibility of the cables, because the convenience of the welder will depend on these indicators.

After igniting the arc, the electrode must be moved away from the plane of the metal plate to a distance equal to the length of the arc (approximately 2-3 mm) and welding can begin. To make high-quality welding, you must constantly monitor the length of the electric arc. A short arc (about 1 mm) can cause a welding defect called “undercut.” This welding defect is characterized by the appearance of a shallow groove parallel to the weld, leading to a decrease in the strength of the weld. Long arc is unstable, provides more low temperature in the welding zone, and, as a result, such a seam has too shallow a depth and is “smeared”. A welder who knows how to properly adjust the arc length will receive a high-quality weld.

After welding is completed, you should carefully beat off the scale that has frozen on top of the seam with a hammer.

Polarity when welding with an inverter

Melting of a metal is caused by exposure to high temperature welding arc, which occurs as a result of connecting opposite terminals of the inverter to a metal plate and to a welding rod. Depending on the order of connecting the welding inverter terminals, a distinction is made between direct and reverse polarity.

Polarity is the setting of the direction of electron movement. Both direct and reverse polarity are used when welding with an inverter, so it is important for a novice welder to know the differences between these types of connections.

Straight polarity is the polarity that occurs after connecting the electrode to the minus terminal and the metal plate to the plus terminal. With this connection, the current flows from the electrode to the metal, as a result of which the metal heats up more intensely, and the melting zone becomes sharply limited and deep. The direct polarity of connecting the welding inverter is selected when welding thick-walled elements and when inverter cutting.

Reverse polarity is characterized by connecting the “minus” to the metal plate, and the “plus” to the electrode. The fusion zone with this connection is wider and has a shallow depth. The direction of current is directed from the metal workpiece to the electrode, resulting in greater heating of the electrode. This procedure reduces the risk of burn-through and is used when welding thin-walled metal products.

Working with thin metal

Welding of thin-walled metal products with an inverter is carried out by connecting the terminals according to a circuit corresponding to reverse polarity and placing the electrode at an angle forward. This welding technique provides a smaller heating zone with sufficient seam width.

Ignition of the electrode should be done extremely carefully, because the beginning of the pool when welding thin metal is often accompanied by a burn-through. Welding thin metal with an inverter must be carried out gradually, welding small areas with a short-term removal of the electrode from the bath. At this moment, you need to make sure that the yellow glow of the electrode tip does not go out.

The quality of the weld directly depends on the quality of the electrodes, which will help avoid excessive formation of slag in a small-section weld. Also, the use of small-diameter electrodes avoids burning through the metal.

When completing a weld, you should not abruptly tear off the electrode to extinguish the arc, because in this case a noticeable crater will form at the end of the seam, which will worsen the strength of the metal of the welded joint and the result of the welding equipment will be unsatisfactory.

Another defect that often occurs when welding thin metal is deformation of the product. To prevent its occurrence, it is necessary to carefully secure the parts being welded before welding.

A welder with little experience often wonders how to properly weld metal using electric welding. General tips for working with an inverter and rules for welding metal with an electrode will be given in the section below.

When welding metal with an inverter, you must carefully monitor that the weld is flush with the metal. An electric arc penetrating the metal with intense speed and sufficient depth causes the pool to move backward and creates a weld that can become defective if the speed of the electrode is too high. An ideal seam will be obtained if the electrode performs zigzag and circular vibrations.

When changing the direction of movement of the electrode, remember that the bath follows the heat. The formation of an undercut occurs against the background of insufficient metal of the electrode, so it is worth strictly monitoring and controlling the boundaries of the bath.

By placing the electrode at a certain angle, you can control the direction of movement of the bath, while the vertical position of the electrode will contribute to sufficient penetration. In this position, the bathtub will be pressed down and have good boundaries, and the seam will have less convexity. Too much tilt of the electrode will not allow you to control the bath.

Inverter welding is also applicable when performing pipe welding work. Welding takes place under rather difficult conditions, so it is necessary to pay great attention to the quality of penetration at rotary joints. An angle of 30º is the standard angle of inclination of the electrode to the pipe surface. On pipes made of low-alloy steels with a wall cross-section up to 12 mm, the seam will be single-layer. For pipes with a larger wall thickness, a second weld should be applied, which will increase the overall strength of the weld. After each new weld, it is imperative to clean the hardened slag. Pipes with a diameter of up to 0.5 m must be boiled continuously.

An inverter is a simple welding machine that is ideal for a novice welder to carry out welding work at home. When choosing an inverter, you must rely on your own needs and the compliance of the selected device with them, thus meeting your needs.

IN Everyday life V own home, on summer cottage or in the garage there are always many things that require welding skills. This skill is especially useful in DIY construction. In nature, there is no more reliable way to connect two metal parts than welding. And it is quite possible to learn this skill on your own and put the acquired skill to good use. Today we’ll figure out how to learn how to cook with electric welding and independently master the basics of this specialty.

To understand how to properly weld using electric welding, you first need to familiarize yourself with the theory of the welding process.

Connecting metal parts into a monolith using welding is by far the most reliable and durable method. This is achieved by obtaining high temperature. The vast majority of welding machines use an electric arc to melt metals: this is the so-called electric arc welding of metals. At the point of impact, it heats the metal to its melting temperature and does this in a limited area.

The appearance of an electric arc occurs due to current - direct or alternating. The first is typical for inverter welding units, the second – for transformers. Let's take a closer look at them.

• The transformer greatly complicates the welding process. Due to alternating current, the welding arc constantly jumps, and the welding process is quite noisy. Another significant disadvantage of such devices is the strong impact on the electrical network, which results in voltage surges;
• The inverter is simpler and quieter to operate, powered by 220V. Because of the constant current, the arc is easier to control and move. If there is a need to learn how to cook with electric welding, then it is better to take lesson No. 1 on an inverter machine.

The formation of an electric arc becomes possible when there are two elements that conduct current and have opposite charges. When welding, it is metal and electrode. It makes sense for a novice welder to use a traditional electrode with a metal central element.

To understand how to properly weld metal, you need to clearly understand the processes taking place:

• An electric arc appears at the moment of contact between a metal part and an electrode;
• At the point where the arc is formed, the metal being welded melts;
• Together with the metal, the electrode itself is melted, its molten particles move into the weld pool;
• The protective coating that covers the electrode rod also burns and forms a gas cloud. It protects the bath from exposure to oxygen. This ensures that the melting temperature of the metal is maintained at the welding site;
• The slag formed during welding also helps maintain the temperature. It is necessary to ensure that the slag encloses the weld pool;
• A seam during welding is formed at the moment of movement of the electrode and movement of the bath;
• When the metal cools after welding, a slag crust remains on it. It is beaten with a hammer.

This is the theory of welding. It is impossible to understand how to weld metal correctly without experience, so let’s turn to practice.

Preparing the tools

Before electric welding, you need to prepare all the tools and uniforms for protection:

• Welding machine and electrodes for it. We recommend stocking up on enough electrodes for practice. The proverb “the first pancake is lumpy” in the field of welding training works without exception;
• Protection: welding mask, protective clothing and gloves made of thick materials. Protection should not be neglected during welding work. It's a matter of health and safety!
• Auxiliary tools - a hammer and a metal brush - to remove weld slag;
• Object for training – metal elements;
• Bucket with water. Literally, just in case of fire.

The choice of electrodes is made in accordance with the thickness of the metal being welded, and the setting of the current depends on the electrode. 1 mm of electrode takes about 30-40 A, it is important not to exceed these values, otherwise the arc will not cook, but cut metal.

Let's start welding

So, let’s figure out step by step how to properly weld metal. Probably, to obtain an acceptable result, you will have to repeat this algorithm more than once. But once you learn, you will quickly get used to the role of a welder and will be able to perform quite complex operations.

First of all, we place the electrode in a special holder. Now you need to light the arc. The electrode should be held at an angle of approximately 70° to the surface; this position is optimal.

1. Having set the angle between the electrode and the metal, draw a quick line, moving about 10 cm per second. If the position is correct, sparks and crackling sounds will appear - this is a sure sign.
2. Leaving optimal angle tilt the electrode, you need to touch the metal with it and immediately lift the electrode so that a path of 3-5 mm is formed. If everything is done correctly, the arc will burn and the metal will begin to melt.
3. It is not uncommon for the electrode to stick to the base. In this case, you need to slightly swing it and tear it off, and then ignite the arc again. Frequent sticking of the electrode may indicate too low current strength. Try increasing it and compare the results.
4. Once ignition of the arc and its holding in a stable state are mastered, you can begin to deposit the bead. The clamped arc moves smoothly along the weld. At the same time, movements are made that seem to rake in the molten metal. This is achieved by uniform oscillatory movements with an amplitude of about 2-3 mm. The more measured the movement, the more beautiful the welded seam will turn out. By the way, the uniformity of the seam indicates its high quality and strength.

At the first stage, it is best to train on a thick piece of metal and try to draw various paths with an arc - from simple measured movements with a small amplitude to more complex and patterned seams. These skills will be useful in subsequent work and will allow you to get a good feel for how to cook and what angle of the electrode is best to choose.

After finishing welding, you must wait until the metal cools down. The weld will be covered by slag. To make it fly off, just tap the part with a hammer or run a brush over the iron.

Some aspects of welding work

Of course, welding does not involve writing intricate patterns on a piece of metal. All of the above is just preparation and training for this rather difficult craft. The main purpose of welding is to reliably fasten metal elements and you should strive for it in your training.

Welding metal elements has many nuances, familiarity and understanding of which will come with experience. But there are some theoretical points, which you need to know before practice:

• It is incorrect to connect two parts at once with a continuous and long seam. In most cases, this distorts the metal, as the seam begins to pull the elements together;
• Before making the main seam, you need to tack the parts together. To do this, small spot seams are made at the joints of two parts in increments of 8-25 cm, depending on the size of the elements being fastened.
• It is better to make fastening seams on both sides of the welding surface, this way the possible stress on the metal is minimized.
• After completing the tacks, the main seam is made.

Let's sum it up

Welding work requires special knowledge, skills and special equipment. Please note that this is a rather complex and dangerous process that requires strict adherence to safety precautions.

Welding skills require some time and practice. There is nothing wrong with training on a piece of unnecessary metal. This allows you to gain experience and understand the essence of the welding process.

Before you start welding parts, you should hone your use of a welding machine and the ability to weld seams on workpieces and then move on to more complex elements.