What are the welding techniques of electric welding technology?

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.

Generally speaking, the commonly used electric welding methods are as follows:

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.

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.

1. Arc welding.

Arc welding is currently the most widely used welding method. It includes: hand arc welding, submerged arc welding, tungsten gas arc welding, plasma arc welding, MIG/MAG welding, etc.

2. Resistance welding.

This is a class of welding methods that use resistance heat as energy source, including electroslag welding with slag resistance heat as energy source and resistance welding with solid resistance heat as energy source. Resistance welding includes: resistance spot welding, coating welding, seam welding, high-frequency welding, flash butt welding.

3. High-energy beam welding.

This type of welding method includes: electron beam welding and laser welding.

4. Brazing. The energy source for brazing can be either the heat of chemical reaction or indirect heat. It is the use of the melting point lower than the melting point of the welded material as the brazing metal, after heating to melt the brazing metal, by the capillary action of the brazing metal and into the joint contact surface of the gap into the wetting metal surface, so that the liquid phase and the solid phase diffuse each other to form a brazing joint.

5. Other welding methods.

These welding methods belong to different degrees of specialization, and their scope of application is narrow. It mainly includes electroslag welding and high-frequency welding with resistive heat as the energy source; Gas welding, pneumatic welding, and first-class welding with chemical energy as the welding energy source; Friction welding, cold pressure welding, ultrasonic welding, and diffusion welding with mechanical energy as the welding energy source.

Hello, the common welding methods are, flash butt welding, submerged arc welding, etc.

According to the welding position, it can be divided into vertical welding, horizontal welding, flat welding, vertical welding, etc.

Hello, the common welding methods are: manual arc welding, carbon dioxide gas shielded welding, argon arc welding, oxyacetylene welding, submerged arc welding, plasma welding, etc.

1. Brazing.

Brazing refers to the welding method in which the brazing metal below the melting point of the weldment and the weldment are heated to the melting temperature of the brazing material at the same time, and the liquid brazing material is used to fill the gap of the solid workpiece to make the metal connection. According to different temperatures, it can be divided into hard brazing and soldering.

During brazing, the oxide film and oil stain on the contact surface of the base metal should be removed first, so as to facilitate the capillary tube to play a role after the brazing metal is melted, and increase the wettability and capillary fluidity of the brazing metal. According to the different melting points of brazing metals, brazing is divided into hard brazing and soft brazing.

2. Fusion welding. Fusion welding refers to the process of welding the welded joint to a molten state under the action of high temperatures. Since the welded workpieces are tightly adhered to each other, under the action of temperature field, gravity, etc., without pressure, the molten liquid of the two workpieces will be mixed. After the temperature is lowered, the molten part is condensed, and the two workpieces are firmly welded together to complete the welding method.

3. Pressure welding. Pressure welding is to make two workpieces under pressure to achieve atomic bonding in a solid state, also known as solid welding. The commonly used pressure welding process is resistance butt welding, when the current passes through the connection end of the two workpieces, the temperature rises due to the large resistance, and when heated to the plastic state, it is connected under the action of axial pressure to become a whole.

4. Gas welding. Gas welding, English: oxygen fuel gas welding (abbreviated as OFW). It is a welding method that uses the flame generated by the mixed combustion of combustible gas and combustible gas as the heat source to melt the weldment and welding material to achieve interatomic bonding.

5. Electroslag welding.

Electroslag welding uses the resistive heat generated by the electric current through the slag as a heat source to melt the filler metal and the base metal, and solidify to form a firm connection between metal atoms.

At the beginning of welding, the welding wire and the welding groove are short-circuited and the arc starts, a small amount of solid flux is continuously added, and the heat of the arc is used to melt it to form liquid slag, and when the slag reaches a certain depth, the feeding speed of the welding wire is increased, and the voltage is reduced, so that the welding wire is inserted into the slag pool, and the arc is extinguished, so as to transfer to the electroslag welding process.

Hello 1, electrode arc welding: principle - arc welding method for welding with manual operation of electrode. A stable burning arc established between the electrode and the weldment is used to melt the electrode and weldment, resulting in a strong welded joint.

It belongs to the joint protection of gas slag. 2. Submerged arc welding (automatic welding): principle - the arc burns under the flux layer.

A weld is formed by melting the wire, flux, and base metal (weldment) using the heat generated by the burning arc between the wire and the weldment. Slag protection. 3. Carbon dioxide gas shielded welding (automatic or semi-automatic welding):

Principle: Melting electrode arc welding method using carbon dioxide as shielding gas. Atmospheric protection.

Main features - high welding productivity; Low welding cost; Small welding deformation (arc heating concentration); High welding quality; Simple operation; High spatter rate; It is difficult to solder with AC power; Poor wind resistance; Non-ferrous metals that are susceptible to oxidation cannot be welded.

It belongs to the classification of pressure welding, a branch of resistance welding.

It is a welding process in which the workpiece is assembled into a lap joint, pressed between the two electrodes, and the base metal of the pressurized electrode is melted by using low voltage, high current and short time, and the resistance heat is used to form a molten solder joint.

Resistance welding is divided into general-purpose type, special type, and special type according to the application.

According to different installation methods, it is divided into: portable, fixed and hanging.

According to the different power supply modes, it is divided into: AC type, low-frequency type, capacitor energy storage type, and secondary rectifier type.

According to the number of solder joints, it is divided into: single point, double point, and multi-point.

According to the different pressurized transmission mechanisms, it is divided into: pneumatic type, hydraulic type, electric cam type, composite type, and foot pedal type.

According to the different moving modes of the active electrodes, they are divided into: vertical stroke type and arc stroke type.

Classification by family method: welding methods can be divided into three categories: fusion welding, solid phase welding and brazing. Fusion welding is divided into arc welding, gas welding, thermite welding, electroslag welding, etc. according to the type of energy.

Metal welding refers to the joining method of connecting two separate metal objects (the same or different metals) into one by appropriate means.

1. Storage of welding rods:

1. All kinds of welding rods must be classified and stored in different grades to avoid confusion, and should be stored in a dry and well-ventilated warehouse, and should be placed at least 300mm away from the ground and wall to prevent moisture deterioration.

2. Because the coating is easy to be damp, the process performance of the welding rod after moisture deteriorates, and the hydrogen in the moisture is easy to cause porosity and cracks in the weld, so the welding rod must be dried before use to reduce the hydrogen content of the welding rod, generally using 350 450, heat preservation for 1 2 hours, drying.

2. Operation:

1. After the workpiece is combined, the spot welding is firm, and the weld is welded, the width and depth ratio of the weld is 2 3, and the width of the weld is generally doubled. The starting weld refers to the part that has just begun to be welded, and the arc should be slightly lengthened after the arc is struck, and the necessary preheating of the weld end should be carried out, and then the arc length should be appropriately shortened for normal welding.

2. Weld closure means that when a weld is welded, the arc pit at the end should be filled, if the arc is immediately pulled off at the end, the arc pit below the surface of the weldment will be formed, and the strength of the weld at the end will be weakened if it is too deep, resulting in cracks. Therefore, no craters are allowed at the end of the process, and the craters should be filled until they are filled.

3. Due to the limitation of the length of the welding rod, the joint can sometimes not complete a weld with a welding rod, and the beginning of the weld is required to be slightly lower, and the arc is slightly ahead of the beginning of the weld when the joint is welded, and the arc is slightly elongated to lead the arc to the beginning, and cover the end of the front weld, and then move along the welding direction after the weld at the beginning is flattened.

4. The width of the weld is generally made by zigzag or crescent-shaped strip method, the weld welded by this method has a higher reinforcement height, the metal melts well, has a long holding time, and is easy to make the gas precipitation and slag float to the surface, which is good for improving the quality of the weld.

Welding thickness The first layer of weld The other layers of welds, the diameter of the electrode Welding current (a) The diameter of the electrode Welding current (a).

5 220 280, when welding the second layer, first remove the first layer of slag, and then weld with a welding rod with a larger diameter and a larger welding current. In order to ensure quality and prevent deformation, the welding direction between the layers should be reversed, and the weld joints should also be staggered from each other.