What are the basics and skills of electric welding? Please, 3Q

The basic aspects of electric welding are learning: flat welding, vertical welding, and vertical welding. The key point of the exam is that flat welding means that the two interfaces should be smooth, no trachoma, no hand shaking during the welding process, and the electrode molten iron should be evenly distributed.

In terms of learning: vertical welding is simpler than vertical welding, and vertical welding is simpler than flat welding. The usual techniques used are:

Cross method and take the figure 8. Learning theory is only a learning process, and the key is practice and operation. Generally speaking, for experienced grade masters, flat welding is the most difficult.

It's also difficult to operate.

In our country, welding operations need to be licensed, welders are the type of work that belongs to the access category, in the professional qualifications of skilled personnel, only five of the 81 types of work in the access category, welders are one of them, and the actual situation is that most of the industry practitioners are unlicensed operations. With the continuous standardization of technology and the relevant requirements of the industry, more and more people want to take a welding certificate, the advantage of the certificate is still very large, first of all, the salary of the certificate and the non-certificate are very different, often able to reach more than double or higher level. Therefore, the issue of short-term welder training has naturally become a concern for practitioners.

Welding as an industrial "tailor" is a very important means of processing in industrial production, the quality of welding plays a decisive role in the quality of the product, so, what is the future development of welding technology?

Industry outlook. With the development of production, welding is widely used in aerospace, aviation, nuclear industry, shipbuilding, construction and machinery manufacturing and other industrial sectors, in China's economic development, welding technology is an indispensable means of processing. After entering the 21st century, welding is an important part of the manufacturing industry, and the rapid development, so it has brought unprecedented development opportunities to the welding industry.

At present, China consumes 300 million tons of steel every year (about tons of welded structure), and needs about 750,000 welding machines, and the welding industry will continue to grow in the next 8 10 years.

Beginner welding basics:

1. The welding power supply is the equipment that supplies the electrical energy required for welding and has the electrical characteristics suitable for welding in the welding machine, which is called the welding power supply.

2. In order to ensure the stable combustion of the welding arc and adapt to the requirements of various welding processes, the arc welding power supply has the following special requirements:

The static characteristics (or external characteristics) of arc welding power supply - that is, the relationship between the steady-state output current and the output voltage, there are falling characteristics (constant current characteristics) and flat characteristics (constant voltage characteristics).

Dynamic characteristics of arc welding power supply - when the load state changes instantaneously (such as: short-circuit transition of molten droplets, particle transition, jet transition, etc.), the relationship between the output current and output voltage of the arc welding power supply and time is used to characterize the response ability to load transients (i.e., dynamic reaction ability), referred to as "dynamic characteristics".

No-load voltage – the voltage displayed by the power supply before arc starting.

Regulation Characteristics – Change the external characteristics of the power supply to suit the requirements of the welding specification.

3. When the arc length changes, the arc voltage will also change: determined by the external characteristics of the arc welding power supply, the longer the arc, the higher the arc voltage; The shorter the arc, the lower the arc voltage.

4. When CO2 welding, when the length of the wire extension changes, the reason why the current display value will also change: the longer the length of the wire extension (i.e., the dry extension length), the greater the resistance of the welding wire, the greater the current consumed by the resistor, the smaller the welding current display value, and the actual welding current will also be smaller. Therefore, the length of the welding wire is generally set in the range of 12-20mm.

5. When CO2 mag mig welding, the welding current and arc voltage should be strictly matched: when CO2 mag mig welding, adjust the welding current - that is, adjust the feeding speed of the welding wire; Adjust the arc voltage – i.e. adjust the melting speed of the wire; Obviously, the melting speed of the welding wire and the feeding speed must be equal to ensure stable arc welding.

Precautions for basic knowledge of electric welding:

First, the length of the arc.

The length of the arc is related to the type of electrode coating and the thickness of the coating. However, short arcs should be taken as much as possible, especially low-hydrogen electrodes. Long arcs can cause stomatosis.

The short arc can avoid harmful gases such as O2 and N2 in the atmosphere from invading the weld metal and forming undesirable impurities such as oxides and affecting the quality of the weld.

Second, the welding speed.

The appropriate welding speed is based on the diameter of the welding rod, the type of coating, the welding current, the heat capacity of the welded object, the beginning of the structure and other conditions, and the corresponding changes can not be made. Maintain the right welding speed, and the slag can cover the molten pool well.

All kinds of impurities and gases in the molten pool have sufficient time to float out, so as to avoid the formation of slag inclusions and porosity of the weld. If the speed of the rod is too fast during welding, the shrinkage stress will increase when the welding part is cooled, causing cracks in the weld.

It's like this at the beginning, and if you practice more and practice your hands steadily, it's naturally fine.

There is no fixed posture during the operation of electric welding, but the following regulations should be noted; First, the size of the current should be mastered Second, find a position that you think is suitable and squat comfortably Third, the transport strip.

Good luck and familiarity. It is important to master the skills first, and the best way to learn is to practice and theory.

First, the basic knowledge of electric welding: it is a high-power transformer made of the principle of inductance, a power supply (which can be DC or AC) that turns 220V AC into low voltage and high current (can be DC or AC), the inductance will produce huge voltage changes when it is turned on and off, and the high-voltage arc generated by the positive and negative poles in the instantaneous short circuit is used to melt the solder on the welding rod to achieve the purpose of combining them. Welding transformers have their own characteristics, that is, the voltage drops sharply after the electrode is ignited.

The adjustment of the working voltage of the welding machine, in addition to the one-time 220 380 voltage conversion, the secondary coil also has a tap conversion voltage, and it is also adjusted with an iron core, and the adjustable iron core welding machine is generally a high-power transformer.

2. The details are as follows:

With the continuous development of industrial technology, the application of arc welding technologies such as manual arc welding and argon arc welding is becoming more and more extensive. The technical level of the welder plays a decisive role in the quality of the welding. At the same time, accidents caused by personal illegal operations are not uncommon.

Welding safety. 1. Risk factors of welding.

Welders should come into contact with electricity, flammable and explosive gases, flammable liquids, pressure vessels, and aerial work when working. In the welding process, harmful gases, metal vapors and fumes will also be generated; There is also the radiation of arc light, the high temperature of the welding heat source, etc. If safety operating procedures are not strictly followed, it may cause electric shock, burns, fires, **, and even occupational diseases.

Causing losses and harm to individuals, businesses, and countries.

2. Welder "six defenses":

During the welding work, it is necessary to prevent electric shock, fire prevention, explosion prevention, poison prevention, radiation prevention, and fall from height.

Protection against electric shock. Arc welding equipment must be grounded; The welding torch should have reliable insulation; The wiring, repair and inspection of arc welding equipment should be carried out by an electrician; The welder's work clothes, gloves, and insulated shoes should be kept dry; When replacing the welding rod, wear gloves and avoid contact between the body and the weldment; The welded cable must be well insulated, and the cable should be avoided from being burned or smashed when working;

Fire and explosion proof:

Before operation, flammable and explosive materials should be removed within 10 meters before and after the welding and cutting site, and non-combustible materials should be used to accept sparks.

The electrical welding operation site must be equipped with at least two 8kg dry powder fire extinguishers, fire extinguishing sand, and no less than 50 liters of fire extinguishing water.

The electrode head and the weldment after welding should not be thrown casually; Take cooling measures such as sprinkling water in a timely manner. You must carry a portable gas check alarm with you, and the alarm point of the portable meter is.

After the operation, the construction site must be thoroughly cleaned, sprinkled, and kept for 1 hour to confirm that there is no danger before leaving.

Prevention of harmful gas and soot poisoning:

During welding, the surrounding air is often polluted by some harmful gases and dusts, such as manganese oxide, zinc oxide, hydrogen fluoride, carbon monoxide, etc. Long-term breathing may cause occupational diseases such as welders' pneumoconiosis.

Anti-poison measures: The welding site should be well ventilated. Avoid multiple welders crammed together. Wear protective gear.

Radiation protection: Radiation can stab the eyes and burn**. Wear an electric welding mask during construction; wear welder labor protection equipment;

Anti-Falling from Heights:

You can't be impetuous in electric welding, and then master the current, and then the angle, the most important thing is to find and know a good fulcrum that can make your hand hold the welding torch steady.

Hehe, pointing, bounty points are needed. ^_

The basic steps of electric welding technology.

1. When welding, the hand needs to be kept stable and welded, and the arms must be clamped tightly to avoid shaking, so that the welding can be uniform and beautiful.

2. When welding, the zigzag and dot type are generally used for welding, so that the welded weld texture is more gentle and clear.

3. When welding, the welding rod and the iron plate should be kept at an angle of 45 degrees, which is conducive to the uniform distribution of molten iron, and the weld will be smooth. When carrying out the upward welding operation, because the molten iron is easy to fall, it is necessary to take the form of spot welding, so that the soldering will be more firm.

After the arc is ignited, the welding rod generally has three basic actions, namely, gradually feeding towards the weld pool, gradually moving along the welding direction, and swinging laterally.

1. Linear transport method. When this method of transportation is adopted, the welding rod does not swing horizontally, but moves in a straight line along the welding direction. It is commonly used for butt flat welding of grooves, first layer welding of multi-layer welding or multi-layer multi-pass welding.

2. Straight-line reciprocating method. When welding with this strip method, the end of the electrode swings back and forth along the longitudinal direction of the weld. It is characterized by fast welding speed, narrow weld seam and fast heat dissipation. It is suitable for the first layer of multi-layer welding with large gaps between thin plates and joints.

3. Zigzag transport method. In this method of welding, the end of the electrode is zigzag and moves forward, and stops on both sides for a while. The purpose of the oscillation is to control the flow of the molten metal and obtain the necessary weld width to obtain a better weld formation.

This method of transporting bars is widely used in production, and is mostly used for the welding of thick steel plates, the butt joints of flat welding, vertical welding, vertical welding and the fillet joints of vertical welding.

4. Crescent-shaped transport strip method. When welding with this rod method, the end of the electrode swings left and right in a crescent-shaped shape along the welding direction. The speed of the swing is determined according to the position of the weld, the form of the joint, the width of the weld and the value of the welding current.

At the same time, it is necessary to stay on both sides of the joint for a short time to allow sufficient penetration at the edge of the weld to prevent undercut. The characteristics of this method are that the metal melts well, has a long holding time, the gas is easy to precipitate, and the slag is also easy to float to the surface of the weld, and the quality of the weld is higher, but the residual temperature of the welded weld is higher. The scope of application of this method is basically the same as that of the zigzag method.

5. Triangle transport method. When welding with this transport method, the end of the electrode moves in a continuous triangle and constantly moves forward. According to the different swing forms, it can be divided into two kinds of oblique triangle and regular triangle, and the oblique triangle transport strip method is suitable for the T-joint weld and the horizontal weld with groove in the position of flat welding and upward welding, and its advantage is that it can control the molten metal by the swing of the welding rod, and promote the weld to form well.

The regular triangle strip method is only suitable for the vertical welding of the butt joint and the T-joint weld of the bevel opening, and the characteristics are that it can weld a thick weld section at one time, and the weld is not easy to produce defects such as slag inclusion, which is conducive to improving production efficiency.

6. Circle-shaped transport method. When welding with this method of transporting bars, the end of the electrode continuously moves in a positive circle or oblique circle, and constantly moves forward. The positive circle transport strip method is suitable for welding flat welds of thicker weldments, and its advantages are that the molten pool exists for a long time and the metal temperature of the molten pool is high, which is conducive to the precipitation of oxygen, nitrogen and other gases dissolved in the molten pool, and is convenient for the slag to float.

The oblique circle strip method is suitable for the horizontal weld of T-joint weld and butt joint in flat and vertical positions, and its advantage is that it is conducive to controlling the molten metal from the influence of gravity and causing the phenomenon of spillage, which is conducive to the formation of weld.