Basic operation methods of welders

1. Basic operating knowledge of welders

Basic knowledge of welder operation 1. Basic knowledge of welding operation

Original publisher: wanilu 1

Basic knowledge of electric welding operation Manual arc welding (referred to as manual arc welding) is a welding method that uses a manually operated covered electrode and a workpiece to be welded as two electrodes, and uses the arc heat between covered electrode and the workpiece to melt metal. 1. Process principle of manual arc welding: Manual arc welding consists of welding power supply, welding cable, electrode holder, covered electrode, weldment and arc. When welding, use covered electrode to contact the workpiece to ignite the arc, then lift covered electrode and keep a certain distance. Under the condition of suitable arc voltage and welding current provided by welding power supply, the arc burns stably, resulting in high temperature, which locally heats covered electrode and weldments to a molten state. The molten metal at the end of covered electrode and the molten weldment metal fuse together to form a molten pool. When welding, the arc moves with covered electrode, and the liquid metal in the molten pool gradually cools and crystallizes to form a weld, and the two weldments are welded together. During the welding process, the covered electrode flux core melts and is transferred to the molten pool in the form of droplets, while the covered electrode flux core produces a certain amount of gas and liquid slag. The generated gas fills the arc and molten pool to isolate the air. The density of liquid slag is less than that of liquid metal and floats on the molten pool, thus protecting the molten pool. When the metal in the molten pool cools and solidifies, the slag also solidifies to form welding slag covering the weld surface, which prevents the high-temperature weld metal from being oxidized and reduces the cooling speed of the weld. In the welding process, complex metallurgical reactions such as deoxidation, desulfurization, dephosphorization and dehydrogenation are carried out between liquid metal and liquid slag and gas, so that the weld metal can obtain appropriate chemical composition and structure. Second, the arc initiation method contact short circuit arc initiation method is used for manual arc welding. The process of contact short circuit arc initiation method is shown in the following figure.

2. Welding operation essentials

Technical essentials of electric welding (for reference only) 1. Adjust the soldering iron temperature before welding and keep it clean.

And adjust the temperature of the medicine (about 280 degrees). 2. Hold the solder in the left hand and the soldering iron in the right hand.

First, the welding head is pointed at the intersection of the pin and pad of the soldered component, and then the solder is sent to the intersection and the welding head. 3. The welding time is 2-3 seconds.

4. The solder joint is firm and smooth, and the size is moderate, which is generally controlled at more than 2/3 of the size of the pad. 5. The welding iron is firm and bright, and the device will not be damaged during welding.

6. There shall be no false welding, false welding or missing welding. 7. The contact angle between the solder and the metal pin of the welded part is 45-60 degrees.

8. The surface of solder joint should be smooth, free of sharp points, wrinkling, blowing, slag inclusion and pockmarks. 9. The transition from the solder to the metal pin of the welded part should be smooth and smooth, wet and concave-convex.

Welder safety knowledge and methods, the operating steps are as follows: 1. You should master general electrical knowledge, observe the general safety regulations of welders, and be familiar with fire fighting technology, electric shock first aid and artificial respiration. 2. Check whether the power cord, lead-out wire and connection point of the electric welding machine are in good condition before work, and the line crossing the roadway should be overhead or covered with protective cover; The secondary circuit and shell of electric welding machine must be well grounded; The covered electrode clip must be well insulated.

3. Open-air welding is not allowed in rainy days. When working in wet areas, you should stand where insulating articles are placed and wear insulating shoes. 4, mobile welding machine from the power grid wiring or inspection, grounding work must be carried out by an electrician.

5. When pushing the knife switch, the body should be skewed, and the feet should be pushed at one time, and then the welding machine should be turned on; The welding machine must be turned off first, and then the power switch can be unplugged. 6, mobile welding machine position, must first stop the power supply; If welding stops suddenly, please turn off the welding machine immediately.

7. When welding in crowded places, a fence should be installed to block the arc light. When there is no fence, remind people around you not to look directly at the arc light. 8. Wear gloves when replacing covered electrode, and don't lean on iron plates or other conductive objects.

Wear protective glasses when tapping slag. 9, when welding non-ferrous metal equipment, should strengthen ventilation detoxification, use filter gas mask when necessary.

10. In case of gas leakage, when repairing the gas pipeline or welding, you must inform the gas station and the fire and safety department in advance and get permission before you can start working. Before work, the gas source must be turned off and ventilation should be strengthened to eliminate the blown gas. 1 1. Turn off the welding machine after work, and then disconnect the power supply.

3. Common sense and methods of welder's safety operation procedures

The welder's common sense and methods are safe, and the operating procedures are as follows:

1, should master the general electrical knowledge, observe the general safety regulations of welders, and be familiar with fire extinguishing technology, electric shock first aid and artificial respiration methods.

2. Check whether the power cord, lead-out wire and connection point of the electric welding machine are in good condition before work, and the line crossing the roadway should be overhead or covered with protective cover; The secondary circuit and shell of welding machine must be well grounded; The covered electrode clip must be well insulated.

3. Open-air welding is not allowed in rainy days. When working in wet areas, you should stand where insulating articles are placed and wear insulating shoes.

4, mobile welding machine from the power grid wiring or inspection, grounding work must be carried out by an electrician.

5. When pushing the knife switch, the body should be skewed, and the feet should be pushed at one time, and then the welding machine should be turned on; The welding machine must be turned off first, and then the power switch can be unplugged.

6, mobile welding machine position, must first stop the power supply; If welding stops suddenly, please turn off the welding machine immediately.

7. When welding in crowded places, a fence should be installed to block the arc light. When there is no fence, remind people around you not to look directly at the arc light.

8. Wear gloves when replacing covered electrode, and don't lean on iron plates or other conductive objects. Wear protective glasses when tapping slag.

9, when welding non-ferrous metal equipment, should strengthen ventilation detoxification, use filter gas mask when necessary.

10. In case of gas leakage, when repairing the gas pipeline or welding, you must inform the gas station and the fire and safety department in advance and get permission before you can start working. Before work, the gas source must be turned off and ventilation should be strengthened to eliminate the blown gas.

1 1. Turn off the welding machine after work, and then disconnect the power supply.

4. The use of welding and matters needing attention

Safety precautions and preventive methods of electric welding. Electric welding, also called arc welding, is a technological method that the cross section of the welded metal is locally heated and melted to a liquid state by the arc thermal effect generated by welding equipment, so that the originally separated metals are combined into a solid and inseparable joint.

According to different welding processes, arc welding can be divided into automatic welding, semi-automatic welding and manual welding. Automatic welding and semi-automatic welding are mainly used in the manufacture of large-scale mechanical equipment, most of which are installed in factories with relatively fixed workplaces; Manual welding has good flexibility because it is not limited by workplace conditions. At present, it is widely used in open-air construction.

Because the workplaces are very different, electricity, light, heat and open flames will be generated during work, so there are various hazards in welding operations. A, easy to cause electric shock accident 1, in the process of welding, because the welder should often change the covered electrode and adjust the welding current, the operation should directly contact the covered electrode and the electrode plate, and the welding power supply is generally 220 V/380 V When the electrical safety protection device fails, the labor protection articles are unqualified, and the operators operate illegally, electric shock accidents may be caused.

If welding is carried out in metal containers, pipelines or wet places, the risk of electric shock is greater. 2. When the welder is unloaded, the voltage of the secondary winding is generally 60~90V, which is easily overlooked by the welder because of its low voltage, but its voltage exceeds 36V in safe voltage, which is still dangerous.

Assuming that the no-load voltage of the electric welding machine is 70V, people work in a high temperature and humid environment. At this time, the human body resistance R is about1600Ω. If the welder's hand touches the lower jaw, the current I passing through the human body is: I=V/R=70/ 1600=44Ma. Under the action of this current, the welder's hand will spasm, which is easy to cause electric shock accidents. 3. Because the welding operation is mostly carried out in the open air, the welding machine, the welding handle wire and the power cord are mostly in high temperature, high humidity (construction site) and dust environment, and the cooker is often overloaded, which is easy to make the insulation of the power cord and the electrical circuit aging, and the insulation performance is reduced, which is easy to lead to leakage accidents.

Second, it is easy to cause fire and explosion accidents. Because there is arc or open flame during welding, it is easy to cause fire when working in places with flammable materials. Especially in flammable and explosive device areas (including pits, ditches, grooves, etc.). ), it is more dangerous to weld containers, towers, tanks and pipelines that have stored flammable and explosive media.

Third, it is easy to cause burns. Arc and metal slag will be produced during welding. If the welder does not wear special protective work clothes, gloves and leather shoes for welding, especially when welding at high places, welding sparks will splash out. If protective isolation measures are not taken, it is easy to cause skin burns to the welder himself or the construction personnel below the working face. Fourth, it is easy to cause electro-optic ophthalmia. Due to the strong visible light and a large number of invisible ultraviolet rays generated during welding, it has a strong harmful effect on people's eyes. Long-term direct exposure can cause eye pain, photophobia, tears and fear of wind. , it will easily lead to inflammation of conjunctiva and cornea (commonly known as electro-optic ophthalmia).

Verb (abbreviation of verb) The arc produced by welding with light radiation function contains infrared rays, ultraviolet rays and visible light, which has radiation effect on human body. Infrared ray has the function of heat radiation, and welding in high temperature environment can easily lead to heatstroke of workers; Ultraviolet rays have photochemical effects and are harmful to human skin. At the same time, long-term exposure to the outside skin will also make the skin desquamate, and long-term exposure to visible light will cause eye vision decline.

Six, easy to produce harmful gases and smoke. Because the arc temperature generated in the welding process reaches more than 4200℃, the coated electrode core, coating and metal weldment will vaporize, evaporate and condense after melting, resulting in a large number of manganese-chromium oxides and harmful smoke and dust; At the same time, the high temperature and strong radiation of arc light will also produce toxic gases such as ozone and nitrogen oxides in the surrounding air. Engaged in welding work under poor ventilation for a long time, these toxic gases and smoke are inhaled by human body, which has a certain impact on human health.

Seven, easy to cause falling Due to the needs of construction, welders should often climb the welding work. If the anti-falling measures are not done well, the scaffolding is not standardized and will be used without acceptance; Take isolation measures when crossing up and down to prevent objects from hitting; Welders have a weak sense of personal safety protection, and they don't wear safety helmet or safety belt when climbing. In case of careless walking and accidental object collision. , may cause a fall accident. Eight, easy to cause poisoning, suffocation welders often enter metal containers, equipment, pipelines, towers, storage tanks and other closed or semi-closed places for welding. If toxic and harmful media and inert gases are stored, transported or produced, once the work management is poor and the protective measures are not in place, it is easy to cause poisoning or suffocation of the operators. This phenomenon mostly occurs in oil refining, chemical industry and other enterprises.

Nine, the general principle of electric shock prevention measures is to take safety measures such as insulation, shielding, isolation, leakage protection and personal protection to prevent human contact with charged bodies. The specific methods are: 1 to improve the insulation performance of welding equipment and lines.

Welding equipment and power cables used must be qualified products, and their electrical insulation performance should be suitable for the voltage level, surrounding environment and operating conditions used; Arrange special personnel to carry out daily maintenance and maintenance of the welder to prevent sun and rain, so as not to reduce the electrical insulation performance of the welder. 2. When the welding machine breaks down and needs maintenance, moving the work place, replacing the connector or replacing the safety device, the power supply must be cut off before operation.

3. Don't forget to install the leakage protector when installing the power supply for the electric welding machine, so that the guarantor will automatically cut off the power supply in case of electric shock. When welding on wet or metal containers, equipment and parts, a leakage protector with rated working current not greater than 15mA and rated working time less than 0. 1 s must be selected.

4, butt welding machine shell and the end of the secondary winding lead should take good protective grounding or zero measures. When the power supply is three-phase three-wire system or single-phase system, a protective grounding wire should be installed, and its resistance value should not exceed 4 Ω; When the power supply is a three-phase four-wire neutral grounding system, a protective zero line should be installed.

5. Strengthen the education of workers' electricity safety knowledge and self-protection consciousness, and require welders to wear insulating shoes and special insulating gloves when working. Open-air welding is prohibited in rainy days; When welding in a particularly humid place, people must stand on a dry wooden board or rubber insulating sheet.

6. It is forbidden to use metal structures, pipes, tracks and other metal connectors for wire connection. In a metal container.

5. Common sense and methods of welders. Safe operating procedure

Welder safety knowledge and methods, the operating steps are as follows: 1. You should master general electrical knowledge, observe the general safety regulations of welders, and be familiar with fire fighting technology, electric shock first aid and artificial respiration.

2. Check whether the power cord, lead-out wire and connection point of the electric welding machine are in good condition before work, and the line crossing the roadway should be overhead or covered with protective cover; The secondary circuit and shell of welding machine must be well grounded; The covered electrode clamp must be well insulated. 3. Open-air welding is not allowed in rainy days. When working in wet areas, you should stand where insulating articles are placed and wear insulating shoes.

4, mobile welding machine from the power grid wiring or inspection, grounding work must be carried out by an electrician. 5. When pushing the knife switch, the body should be skewed, and the feet should be pushed at one time, and then the welding machine should be turned on; The welding machine must be turned off first, and then the power switch can be unplugged.

6, mobile welding machine position, must first stop the power supply; If welding stops suddenly, please turn off the welding machine immediately. 7. When welding in crowded places, a fence should be installed to block the arc light. When there is no fence, remind people around you not to look directly at the arc light.

8. Wear gloves when replacing covered electrode, and don't lean on iron plates or other conductive objects. Wear protective glasses when tapping slag.

9, when welding non-ferrous metal equipment, should strengthen ventilation detoxification, use filter gas mask when necessary. 10. In case of gas leakage, when repairing the gas pipeline or welding, you must inform the gas station and the fire and safety department in advance and get permission before you can start working. Before work, the gas source must be turned off and ventilation should be strengthened to eliminate the blown gas.

1 1. Turn off the welding machine after work, and then disconnect the power supply.

6. What is the welder's knowledge of safe operation?

1. Welders must wear insulating shoes, gloves, protective masks and goggles when working, and must wear protective glasses when removing welding slag;

2. Before operation, check whether the welding machine and tools are in good condition. If leakage or power failure of the welding machine is found, an electrician should repair the shell in time, and the grounding wire must be connected.

3. Maintain the safety of the welding secondary circuit wiring, and at the same time keep the electrode holder and wires well insulated;

4. When working in a wet place, you should stand on an insulated object; When hot work is carried out in the limited space and high places which are easy to burn, it should be approved by dangerous operation, and safety measures such as monitoring, ventilation, prevention and monitoring should be strengthened;

5. The distance between the oxygen cylinder and acetylene shall not be less than 5m, and the distance between the gas cylinder and the open flame shall be greater than10m; Avoid cylinder exposure, and it is forbidden to pollute the cylinder body and welding and cutting tools with grease.

6. Acetylene cylinders must be equipped with backfire preventers;

7. When igniting, the gun is not allowed to be aimed at people, and the burning welding torch is not allowed to be placed on the workpiece or on the ground;

8. It is forbidden to weld on pressure vessels or pipelines, and the "ten no welding" regulations for welding and cutting shall be observed;

9. Welding and cutting live equipment must first cut off the power supply;

10. Fire fighting equipment must be available for open fire operation in the work shed, and special personnel shall be assigned for supervision;

1 1. When replacing the mobile handle, cut off the power supply first;

12. Don't climb a ladder or a mountain with the flashlight holding the handle and connecting the hose;

7. Introduction and skills of welders

To be a good welder needs 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 machines is similar to that of transformers, and they are step-down transformers.

At both ends of the tooth and the coil are the welded workpiece and the coated electrode, which ignite the arc and fuse the gap between the workpiece and the coated 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.

8. Electric welding operation procedures

A, must wear the necessary labor insurance, welders must use welding makeup mask, slag removal should wear protective glasses, gas welding (cutting) workers should wear protective glasses.

Second, it is forbidden to weld on the pressure vessel pipeline, and it is forbidden to store inflammable and explosive articles within 5m of the welding site. When welding with flammable medium, the residual medium must be thoroughly cleaned with alkaline water or steam, and the operating hole or hand hole can be rotated only after it is confirmed.

3. Before welding and repairing the acetylene gas generator, it must be washed with clear water and tested with open flame. After confirmation, the rotary welding can be carried out.

Four, near the mobile acetylene gas generator, it is forbidden to contact the fire source, to keep 10 meters away from the welding site.

Five, acetylene gas generator should be equipped with explosion-proof and anti-flashback safety devices, often check the water injection of generator and anti-flashback device, should not be too high or too low, instruments and safety devices should be regularly checked to ensure sensitivity and reliability.

Six, acetylene gas generator should be equipped with explosion-proof and anti-flashback safety devices, often check the water injection of generator and anti-flashback device, should not be too high or too low, instruments and safety devices should be regularly checked to ensure sensitivity and reliability.

7. When the backfire prevention device is frozen, it can be heated by hot water or steam. It is forbidden to bake the parts and auxiliary tools on the acetylene gas generator with fire, and it cannot be made of copper to prevent the explosion caused by copper. First, before connecting the pressure reducer, you should first open the oxygen cylinder valve to blow off the dirt and dye on the bottle mouth. The high and low pressure pressure gauges of oxyacetylene bottles should be sensitive and reliable.

Second, oxygen acetylene bottles should be properly handled and stored to avoid collision and vibration. They should not be exposed to sunlight and avoid heat sources.

Third, after the pressure reducer is installed, open the gas cylinder first and then open the pressure reducer. After work, the gas cylinder should be closed first, and then the pressure reducer should be closed. When operating, the welder should stand on the side of the pressure reducer.

Four, the oxygen in the oxygen cylinder is not allowed to be completely discharged, and the pressure should be kept at 0. 1-0.2mpa.

Five, oxygen hose and acetylene hose shall not be replaced or substituted, pipe joints should prevent air leakage.

Six, oxygen cylinder and pressure reducer are strictly prohibited from contact with grease. A, tempering should quickly close the oxygen valve, and then close the acetylene gas valve.

Second, when the acetylene pipe is broken and caught fire, the hose in front should be quickly folded to put out the fire. When the oxygen pipe is on fire, the oxygen cylinder valve should be closed quickly. It is forbidden to put out the fire by folding the pipe.

Three, welding machine must have a reliable grounding.

Four, welding handle wire should have good insulation, broken skin leakage should be repaired in time.

Five, welding torch should prevent overheating.

9. The basic operation of welder

It is suggested to buy an introduction to welders (Zhejiang Science and Technology Publishing House) from the bookstore, which is easy to understand and illustrated, and is suitable for welders with junior high school education or above.

The joint form and groove form of welded parts are introduced. And the common methods of transporting strips; Professional knowledge of flat welding, vertical welding, horizontal welding, overhead welding, pipeline welding, etc. There are also various precautions.

The specific contents include: 1. Basic concepts and related knowledge of welding; 2. Welding arc, equipment, tools and maintenance; 3. Manual arc welding process; 4. Welding of common metal materials; 6. The generation and prevention of welding stress and deformation and welding defects; 7. Gas welding and gas cutting; 9. Manual TIG welding and welding and cutting safety technology.