Welding machine knowledge MMA/TIG/MIG

Welder

The purpose of the electric welding machine is to use the high-temperature arc generated when the positive and negative poles are short-circuited instantaneously to melt the solder on the electrode and the material to be welded, so as to combine the objects to be contacted. Its structure is very simple, it is a high-power transformer.

Welding machines are generally divided into two types according to the type of output power, one is AC power and the other is DC. They use the principle of inductance, the inductance will produce huge voltage changes when it is turned on and off, and use the high-voltage arc generated when the positive and negative poles are short-circuited to melt the solder on the electrode, so that they can achieve the purpose of atomic bonding . Features

Advantages of electric welding machine: electric welding machine uses electric energy to instantly convert electric energy into heat energy. Electricity is very common. Electric welding machine is suitable for working in a dry environment and does not require too many requirements. Because of its small size, simple operation, convenient use and fast speed , the advantages of strong weld after welding are widely used in various fields, especially for parts requiring high strength, which can instantly connect the same metal material (also dissimilar metals, but the welding method is different) permanent connection , After heat treatment, the welding seam has the same strength as the base metal, and the sealing is very good, which solves the problems of sealing and strength for the manufacture of storage gas and liquid containers

Disadvantages of electric welding machine: During the use of electric welding machine, a certain magnetic field will be generated around the welding machine. When the arc burns, radiation will be generated around it. There are infrared, ultraviolet and other light species in the arc, as well as harmful substances such as metal vapor and smoke. Therefore, adequate protective measures must be taken during operation. Welding is not suitable for the welding of high carbon steel. Due to the crystallization, segregation and oxidation of the weld metal, the welding performance of high carbon steel is poor, and it is easy to crack after welding, resulting in hot and cold cracks. Low carbon steel has good welding performance, but it needs to be handled properly in the process, and the cleaning of rust is cumbersome. Sometimes there will be defects such as slag inclusion, cracks, stomata and undercuts in the weld, but proper operation will reduce the occurrence of defects.

principle

It uses the high-temperature arc generated when the positive and negative poles are short-circuited instantaneously to melt the solder on the electrode and the material to be welded to achieve the purpose of combining them. The structure of the electric welding machine is very simple. To put it bluntly, it is a high-power transformer that converts 220/380V AC into a low-voltage, high-current power supply, which can be either DC or AC. The welding transformer has its own characteristics, that is, it has the characteristics of a sharp drop in voltage. After the electrode is ignited, the voltage drops. In the adjustment of the working voltage of the welding machine, in addition to the one-time 220/380V voltage conversion, the secondary coil also has a tap change voltage, and at the same time, it is adjusted by the iron core. The adjustable iron core electric welding machine is generally It is a high-power transformer, which is made of the principle of inductance. The inductance will produce a huge voltage change when it is turned on and off. It uses the high-voltage arc generated when the positive and negative poles are short-circuited to melt the electrode on the electrode. Solder. To achieve the purpose of making them together. A voltage is applied between the electrode and the workpiece, the arc is ignited by scratching or contacting, and the energy of the arc is used to melt the electrode and heat the base metal. As shown in "Welding Machine"

Operating procedures

A. Preparation before welding

1. The electric welding machine should be placed in a ventilated and dry place and placed stably.

2. Check that the welding mask should be free of light leakage and damage. Welders and auxiliary personnel should wear protective equipment.

3. The welding tongs, power cords and joints of the electric welding machine should be connected reliably and well insulated. Do not allow overheating at the wiring, and the power terminals must not be exposed, and should be wrapped with electrical tape.

4. The length of the wire between the welding machine and the welding tongs shall not exceed 30 meters, and shall not exceed 50 meters in special circumstances. If the wire is damp or broken, it should be replaced immediately.

5. When the electric welding wire passes through the road, it must be elevated or buried in the protective tube, for example, it must pass under the track when passing through the track.

6. The primary and secondary wiring of the AC welding machine should be accurate, and the input current should meet the equipment requirements. It is strictly forbidden to touch the live part of the primary circuit.

7. The secondary tap connection copper plate must be pressed tightly, and the terminal should have a coil. Before closing, check in detail that the contact bolts and other components are not loose or damaged.

B. Matters needing attention in welding

1. A reasonable welding process should be selected according to the technical conditions of the work. Overload use is not allowed, high current welding is not allowed, and electric welding machines are not allowed to perform metal cutting operations.

2. During load welding, the temperature rise of the welding machine should not exceed 60 degrees for class A and 80 degrees for class B, otherwise it should be stopped to cool down before welding.

3. The working place of the electric welding machine should be kept dry and well ventilated. When moving the electric welding machine, the power supply should be cut off, and the electric welding machine should not be moved by pulling the power source. If there is a sudden power failure during welding, the power should be cut off.

4. During welding, current regulation is not allowed. It must be adjusted with the adjustment handle when the welding is stopped, not too fast or too violent, so as not to damage the adjuster.

5. Welding work under the crane operating workpiece is prohibited.

6. If welding is performed in an area with crane wire ropes, care should be taken not to make the ground wire of the welding machine accidentally touch the lifting wire rope, so as to avoid sparks and accidents.

7. When it is necessary to work in a wet area, the welder must stand on an insulated wooden board, and are not allowed to touch the wires of the welding machine, and are not allowed to use the arms to hold the live welding tongs.

C. Matters needing attention after welding

1. After the welding operation is completed, the power supply should be cut off immediately, the switch of the welding machine should be turned off, and the power supply and ground wire of the welding tongs should be cleaned and rectified respectively, so as to avoid short circuit caused by closing the switch.

2. If the automatic stop point device is found to be invalid during welding, it should be shut down immediately for maintenance.

3. Wear glasses when removing weld slag. Pay attention to avoid the direction of the welding slag splashing on the head to avoid injury. Welding slag should not be tapped at those present.

4. After the open-air operation is completed, the welding machine should be covered to avoid rain.

5. When not welding (moving, repairing, adjusting, resting during work), the power supply should be cut off to avoid accidents.

6. Check whether the welding machine is grounded reliably once a month.

Auxiliary appliances for electric welding machines include gas welding glasses to protect the operator's eyes from ultraviolet, infrared or other rays generated by the welding arc or other welding energy sources, masks to protect the eyes, face and neck of the welder during arc welding, white overalls, welder gloves and protective gloves. feet etc.

How to choose?

Welders have a wide range of uses. Whether it is a large shipbuilding enterprise, industrial and mining enterprises and various construction enterprises, electric welding machine is an indispensable tool. Electric welding machine is used for material welding, and it is live when it is used, especially some small construction units buy cheap electric welding machines to save costs. It is easy to cause electric shock, fire, and desoldering when used in the harsh environment of the construction site. If the phenomenon occurs, it will endanger personal safety and property safety. Because the welding quality is not good, it will also cause "tofu slag" projects.