2G: horizontal welding or vertical fixing
3G: Valve stem welding
4G: overhead welding
5G: Horizontal fixation
6g: 45 fixation
5GX: Vertical welding (downward)
⊥: fillet weld (various positions)
Question 2: What are the skills of welding? To be an excellent welder, you need to be careful, steady, sharp-eyed and serious! Practice more. Here are some related knowledge: 1: the arc temperature of argon arc welding is generally between plasma arc and manual arc welding, with the arc temperature of 9000- 10000K, plasma arc of 16000-32000K, manual arc of 5000-6000K, and argon arc welding of melting electrode of. Electric welding arc light causes myopia of eyes; Noise causes hearing loss. 2. Electric welding is the heteropolar (positive or negative) between the workpiece and covered electrode power supply. The instantaneous contact between covered electrode and the workpiece ionizes the air to generate an arc, and the arc temperature is very high, about 5000-6000K, which melts the surface of the workpiece to form a molten pool. After melting, the coated covered electrode metal is coated on the surface of the workpiece to form metallurgical bonding. 3. "Oxyacetylene Flame" refers to acetylene in oxygen (acetylene is commonly known as calcium carbide gas, which reacts with water). In this reaction, a lot of heat is released, so that the temperature of oxyacetylene flame can reach above 3000℃, and steel will melt soon when it comes into contact with oxyacetylene flame. Using this characteristic, oxyacetylene flame is often used to weld or cut metal in production, which is usually called gas welding and gas cutting. Gas welding; The high temperature of oxyacetylene flame is used to fuse two metals together. The key is to prevent metals at high temperature from being oxidized by oxygen in the air. Therefore, the amount of oxygen must be controlled to make acetylene burn insufficiently. In this way, the flame is reducible because it contains carbon monoxide and hydrogen produced by incomplete combustion of acetylene. This kind of flame makes the metal parts and covered electrode to be welded not be oxidized to change their composition when melting, and the weld will not be polluted by oxides ... 4. Water welding should be a welding process under special conditions. 5. The temperature of oxyhydrogen flame can be as high as 2500~3000℃, and even the high melting point (melting point is 17 15℃) can be melted under oxyhydrogen flame combustion. Therefore, oxyhydrogen flame can be used to process timely products. C2H2 flame and HO flame have different applications. O of HO flame is strongly oxidizing. In some cases, HO flame is not used to prevent metal from being oxidized during welding. On the contrary, C with valence of-1 in C2H2 is reducible. C2H2 flame can be used not only for welding metal, but also as a protective gas to prevent O in the air from oxidizing the welding metal. Covered electrode: E43 and E50 series welding machines are commonly used. The working principle of ordinary welding machine is similar to that of transformer, both of which are step-down transformers. At both ends of the tooth and coil are welded workpieces and covered electrode, which ignite the arc and melt the gap between the workpiece and covered electrode at the high temperature of the arc. Welding transformer has its own characteristics, that is, the voltage drops sharply. Covered electrode voltage drops after ignition; When the covered electrode is short-circuited due to adhesion, the voltage also drops sharply. The reason for this phenomenon is the iron core characteristics of welding transformer. The working voltage of the welding machine can be adjusted not only by a 220/380 voltage conversion, but also by the tap of the secondary coil. At the same time, it can be adjusted by iron core. The more the iron core enters, the smaller the welding voltage will be. The working schematic diagram is similar to that of transformer, so it is not drawn here. Suggestions on becoming an excellent welder: 1. First of all, there are more than 100 welding methods, mainly manual welding (that is, the one that burns covered electrode); Resistance bump welding; Gas shielded welding (carbon dioxide and argon arc welding, etc. ); Flame welding; Ultrasonic welding, friction welding, etc. Commonly used welding technologies are argon arc welding, carbon dioxide welding and manual welding. You need to go through formal welding training and obtain a welder's certificate before you can go to work. 3。 Due to certain technical and skill requirements, the effect and quality of products welded by welders of different levels vary greatly. The salary of a truly high-level welder (national level) is very high. The average welder in Guangdong has a minimum income of about 1.500 yuan, and the piece rate may be higher. Welders should have good occupational protection measures when operating, such as gloves, masks, shoes, aprons, underwear, glasses, etc. So don't worry about danger. As long as you follow the rules, it is safe. Welding is a good skill, but to be a good welder, you really need to study hard.
Question 3: What are the common arc welding methods? What are their characteristics? Common welding methods are 1. Manual arc welding: A manual welding method using electric arc as a heat source to melt the coating covered electrode and form a weld with the base metal. The arc temperature is about 6000-8000℃. Suitable for welding ferrous metals and some non-ferrous metals, with a wide range of applications, especially for short welds and irregular welds. 2. Submerged arc welding: (automatic and semi-braking) the arc burns under the flux area, and the granular flux is used as the covering layer of the metal molten pool to isolate the air from entering the molten pool. The welding wire is continuously fed into the arc area by the wire feeder, and the welding direction and moving speed of the arc are completed manually or mechanically. Suitable for welding straight and regular welds of carbon steel, low alloy steel, stainless steel and copper of medium and heavy plate. 3. Gas welding: (gas shielded welding and argon arc welding) Arc welding using shielding gas to protect the welding area. Protective gas is used as a protective layer of metal bath to isolate air. The gases used are inert gas, reducing gas and oxidizing gas, which are suitable for welding carbon steel, alloy steel, copper, aluminum and other non-ferrous metals and their alloys. The oxidizing gas is suitable for the alloy of carbon steel and alloy steel. 4. Ion arc welding: after the gas is ionized in the arc, it is welded by the ultra-high temperature heat source generated by thermal contraction effect, mechanical contraction effect and magnetic contraction effect, and the temperature can reach about 20,000℃.
Question 4: What is welding? What are the methods? I am also a college student majoring in welding. Welding is that two objects are bonded together by squeezing and heating substances! Manual arc welding, argon arc welding, electroslag pressure welding, flash butt welding, oxyacetylene flame gas welding and cutting, and carbon dioxide shielded welding.
Question 5: What are the common industrial welding methods? Welding can be divided into melting electrode welding and non-melting electrode welding.
Covered electrode arc welding, submerged arc automatic welding and inert gas (such as carbon dioxide and argon) shielded welding are very common melting methods.
Non-melting is very common, such as brazing, resistance welding,
Others are also common, depending on the industry, such as explosive welding, underwater welding,
Question 6: What are the welding methods?
It is described in detail in the welding engineer's manual. Come to the email number, I'll send it.
Question 7: What kinds of welding are there? There are many kinds of welding. At present, the commonly used types are as follows. If you want to learn, you'd better be an apprentice first, so it will be easier to get started by combining theory with practice.
arc welding
Arc welding is the most widely used welding method. Including: manual arc welding, submerged arc welding, tungsten gas shielded welding, plasma arc welding, metal gas shielded welding, etc. Most arc welding uses arc combustion between electrode and workpiece as heat source. When forming the joint, filler metal may or may not be used. When the covered electrode used is the welding wire melted in the welding process, it is called submerged arc welding, such as manual arc welding, submerged arc welding, gas shielded welding, tubular wire arc welding, etc. When the electrode used is a carbon rod or a tungsten rod that does not melt in the welding process, it is called non-melting electrode arc welding, such as argon tungsten arc welding and plasma arc welding. Related books
(1) Manual arc welding Manual arc welding is the earliest welding method among various arc welding methods, and it is still widely used at present. It uses covered electrode coated with paint as covered electrode and filler metal, and the arc burns between the end of covered electrode and the surface of the workpiece to be welded. On the one hand, the coating can produce gas shielded arc under the action of arc heat, on the other hand, it can produce slag to cover the surface of molten pool and prevent the interaction between molten metal and surrounding gas. The more important function of slag is to produce physical and chemical reaction with molten metal or add alloying elements to improve the properties of weld metal. Manual arc welding equipment is simple, portable and flexible to operate. It can be used for short weld welding in maintenance and assembly, especially for hard-to-reach parts. Manual arc welding and corresponding covering electrodes can be applied to most industrial carbon steel, stainless steel, cast iron, copper, aluminum, nickel and their alloys. (2) Submerged arc welding (SAW) is a welding method that continuously feeds welding wire as covered electrode and filler metal. When welding, the welding area is covered with a layer of granular flux, and the arc burns under the flux layer, melting the welding wire end and local parent metal, forming a weld. Under the action of arc heat, the upper part of flux melts slag, and metallurgical reaction occurs with liquid metal. On the one hand, the slag floats on the surface of the metal bath, which can protect the weld metal, prevent air pollution, and produce physical and chemical reactions with the molten metal to improve the performance of the weld metal; On the other hand, the welding metal can be quenched slowly. Submerged arc welding can use larger welding current. Compared with manual arc welding, its biggest advantages are good weld quality and fast welding speed. Therefore, it is especially suitable for the welding of straight seams and circular seams of large workpieces. And most of them use mechanized welding. Submerged arc welding has been widely used to weld carbon steel, low alloy structural steel and stainless steel. Submerged arc welding can also be used for some high-strength structural steels and high-carbon steels because the slag will reduce the cooling rate of the joint. (3) Tungsten gas shielded arc welding This is a kind of non-molten gas shielded arc welding, which uses the arc between the tungsten electrode and the workpiece to melt the metal and form a weld. Tungsten electrode does not melt during welding, but only acts as an electrode. At the same time, argon or helium is sent to the nozzle of the welding torch for protection. Additional metals can be added as needed. It is called TIG welding internationally. Tungsten gas shielded welding (GTAW) can control the heat input well, and it is an excellent method to connect metal plate and backing weld. This method can be used to connect almost all metals, especially to weld refractory oxides such as aluminum and magnesium and active metals such as titanium and zirconium. This welding method has high weld quality, but compared with other arc welding, its welding speed is slow. (4) Plasma arc welding Plasma arc welding is also a kind of non-melting electrode arc welding. It uses the compressed arc (called transfer arc) between the electrode and the workpiece to realize welding. The electrode used is usually a tungsten electrode. The plasma gas used to generate the plasma arc can be argon, nitrogen, helium or their mixture. At the same time, through the nozzle with inert gas protection. When welding, filler metal can be added or not. In plasma arc welding, the arc is straight, the energy density is high and the arc penetration ability is strong. The keyhole effect produced in plasma arc welding can be used for the butt joint of most metals in a certain thickness range, and can ensure the penetration depth and weld uniformity. Therefore, plasma arc welding has high productivity and good welding quality. However, plasma arc welding equipment (including nozzle) is more complicated and requires higher control of welding process parameters. Most metals that can be welded by gas tungsten arc welding can be welded by plasma arc welding. In contrast, for the welding of ultra-thin metals below 1 mm, equal spacing is adopted. & gt
Question 8: What are the welding technologies? According to the different states of metals in the welding process, welding methods can be divided into three categories: fusion welding, pressure welding and brazing.
First, fusion welding
In the welding process, the weldment joint is heated to a molten state, and the welding is completed without pressure. Under the heating condition, the atomic kinetic energy of metal is enhanced, which promotes the mutual diffusion between atoms. When the welded metal is heated to a molten state to form a liquid molten pool, atoms can fully diffuse and closely contact, so after cooling and solidification, a solid welded joint is formed (ice can be used as an analogy). Common gas welding, arc welding, electroslag welding and gas shielded welding are all fusion welding methods.
Second, pressure welding.
This is a welding method in which pressure (heating or not) must be applied to the weldment to complete welding. There are two forms of this welding. One is to heat the contact part of the welded metal to a plastic state or a local melting state, and then apply a certain pressure to combine the metal atoms to form a firm welded joint, such as forging welding, contact welding, friction welding, gas pressure welding, etc. Secondly, under the condition of no heating, only enough pressure is applied to the contact surface of the welded metal to make the atoms approach each other by plastic deformation caused by pressure, and a firm joint can be obtained. This method includes cold pressure welding, explosive welding, etc. (mainly used for composite steel plates).
Third, brazing.
It is a method to connect weldments by using metal materials with melting point lower than that of base metal, heating weldments and solders to a temperature higher than that of solder but lower than that of base metal, wetting base metal with liquid solder, filling gaps between joints and diffusing with base metal. Common brazing methods are soldering iron and flame brazing.
Basic principle and application of common welding methods
Classification of current welding methods
First, fusion welding
1, gas welding:
Use oxyacetylene or other gas flame to heat the base metal and solder to achieve the purpose of welding. The flame temperature is about 3000℃. Suitable for thin workpieces, small diameter pipes, non-ferrous cast iron and brazing.
2, manual arc welding:
Manual welding method using arc as heat source to melt covered electrode and base metal to form weld. The arc temperature is about 6000-8000℃. Suitable for welding ferrous metals and some non-ferrous metals, with a wide range of applications, especially for short welds and irregular welds.
3, submerged arc welding:
The (automatic and semi-braking) arc burns under the flux zone, and the granular flux is used as the covering layer of the metal molten pool to isolate the air from entering the molten pool. The welding wire is continuously fed into the arc area by the wire feeder, and the welding direction and moving speed of the arc are completed manually or mechanically.
Suitable for welding straight and regular welds of carbon steel, low alloy steel, stainless steel and copper of medium and heavy plate.
4 gas welding:
(Gas shielded welding) Arc welding in which shielding gas is used to protect the welding area. Protective gas is used as a protective layer of metal bath to isolate air. The gases used are inert gas, reducing gas and oxidizing gas, which are suitable for welding carbon steel, alloy steel, copper, aluminum and other non-ferrous metals and their alloys. Oxidizing gas is suitable for carbon steel and alloy steel alloys.
5, ion arc welding:
The ultra-high temperature heat source generated by thermal contraction effect, mechanical contraction effect and magnetic contraction effect after gas ionization in arc is used for welding, and the temperature can reach about 20000℃.
Second, pressure welding.
1, friction welding:
Welded joints are formed by using the heat energy generated by mutual friction between welded parts and the rotation of contact end faces, and applying certain pressure. Suitable for welding aluminum, copper, steel and dissimilar metal materials. 2, resistance welding:
The weldment (or base metal) is heated to a plastic state or a partially melted state by using the resistance heat generated by current passing through the weldment, and then pressure is applied to connect the weldments together. Suitable for welding thin plates, pipes and bars.
Third, brazing.
1, soldering iron welding:
Use an electric soldering iron or flame to heat the heat of the soldering iron. Heat part of the base metal to melt the solder into the gap, so as to achieve the purpose of connection. Suitable for solder with melting point of 300℃. Generally used for welding wires, circuit boards and original parts.
2, flame brazing:
The gas flame is used as a heating source to heat the base material and melt the filled metal material into the gap to achieve the purpose of connection. Suitable for small-size weldments such as stainless steel, cemented carbide and non-ferrous metals.
Question 9: What are the welding methods for steel structures? At present, more and more buildings adopt steel structures.
The welding methods of steel structure include covered electrode arc welding, carbon dioxide gas shielded welding, self-shielded arc welding, submerged arc welding, electroslag welding, gas-electric vertical welding, stud welding and the combination of corresponding welding methods.
A, covered electrode arc welding
Covered electrode arc welding, also known as manual arc welding, manual arc welding or coated covered electrode arc welding, is an arc welding method using manual covered electrode. The principle of covered electrode arc welding is to use the arc heat generated by covered electrode and workpiece to melt metal for welding. During the welding process, the covered electrode coating melts and decomposes, producing gas and slag. Under the joint protection of gas and slag, the harmful effects of ambient air are effectively eliminated. The required weld can be obtained by metallurgical reaction, reduction and purification of molten metal and slag at high temperature.
Covered electrode arc welding is a highly adaptable welding method. Widely used in the construction of stirrup structure, it can be used for indoor, outdoor and high-altitude horizontal, horizontal and vertical welding. It requires simple welding equipment and flexible and convenient use. In most cases, the welded joint can reach the same strength as the base metal. Suitable for many kinds of welding steel. The minimum thickness of weldable steel plate is 1 mm.
The disadvantages of covered electrode arc welding are low production efficiency, high labor intensity and high requirements for welder's operation skills.
Second, carbon dioxide gas shielded welding
Carbon dioxide gas shielded welding is a welding technology developed in 1950s. According to the degree of automation, it can be divided into automatic co, submerged arc welding, semi-automatic co and gas shielded welding. Semi-automatic co gas shielded welding is mainly used in building steel structures and has become an important fusion welding method.
(1)CO: characteristics and welding requirements of gas shielded welding.
(2) The composition of semi-automatic gas shielded welding machine. Semi-automatic C0, gas shielded welding machine generally consists of arc welding power supply, wire feeder, welding wire, gas and other parts.
Third, submerged arc welding
Submerged arc marking is an automatic D-bonding method, in which the electrode I is burned in the cavity under the granular ch flux layer. The radiant heat of the arc makes the weldment, welding wire drops and flux melt and evaporate to form gas, and cleans the molten pool around the arc to form a closed cavity, in which the arc burns stably. The upper part of the cavity is covered with a layer of molten flux, that is, slag film, which can not only effectively protect the molten pool metal, but also prevent the arc that hinders the operation from radiating out.
The main difference between submerged arc welding and manual welding in steel structure engineering is that its actions such as starting arc, maintaining stable combustion of arc, conveying welding wire, moving arc and filling arc pit after welding are all realized by submerged arc welding itself.
Submerged arc welding can be divided into automatic submerged arc welding and semi-automatic submerged arc welding according to its own confidentiality. The difference is that the arc motion of automatic submerged arc welding is controlled by a special mechanism, while the arc motion of semi-automatic submerged arc welding is completed by hand.
Submerged arc welding machine can be divided into single-wire doffing machine and multi-wire welding machine, including in-line, in-line and vertical.
Question 10: What are the types of welding and how to distinguish the welding forms? There are mainly the following types: (1) gas welding. The so-called gas welding is to use the high-temperature flame produced by the mixed combustion of oxygen and acetylene gas to weld the base, so gas welding is also called oxygen acetylene welding or gas welding. (2) Arc welding. It is a welding method which uses electric arc to convert electric energy into heat energy, so that covered electrode metal and base metal can be melted to form a weld. Welding machines used in arc welding are divided into AC welding machines and DC welding machines, and AC welding machines are mostly used to weld carbon copper pipes. DC welder is mainly used for welding stainless acid-resistant steel and low alloy steel pipes. (3) argon arc welding. This is a welding method using argon as shielding gas. In the welding process, argon gas forms a gas protective layer around the arc, so that the welding position, tungsten electrode gap and welding wire are not in contact with air. Because argon is an inert gas, it does not react chemically with metals, so the alloy elements in weldments and welding wires are not easy to be destroyed during welding, and because argon does not melt in metals, there will be no pores. (4) argon arc welding. There are two different welding methods for the bottom and upper part of the weld, namely argon arc welding is used for backing the bottom of the weld and arc welding is used for covering the upper part of the weld. This welding method can not only ensure the weld quality, but also save money.