24 Mar 2022
Speaking of carbon dioxide gas shielded welding, how much do you know? When the carbon dioxide gas shielded welding machine is working, does the welding power source you choose meet the requirements? Are the wire feeders and welding guns you purchased flexible and easy to operate? And is the air supply system running smoothly? With these questions, let's learn the classification, composition, welding power source, wire feeding mechanism, welding torch and gas supply system of carbon dioxide gas shielded welding from the equipment of the carbon dioxide gas shielded welding machine, and solve our questions one by one.
First of all, let's talk about the classification and composition of carbon dioxide gas shielded welding machines. First, classification. Carbon dioxide gas shielded welding machines can be divided into semi-automatic welding machines and automatic welding machines. The semi-automatic welding machine adopts thin welding wire (ф≤1.2mm), which is suitable for welding with short length and irregular seam; the automatic welding machine adopts thick welding wire (medium ≥1.6mm), which is suitable for long-length, regular welding seam and circular seam welding. Commonly used semi-automatic carbon dioxide gas shielded welding machines are C-350-1, NBC-500, YM-500KR1, YM-500CL4, DYNA AUTO XC-350, DYNA AUTO XC-500 and NBC-630. Second, composition. Carbon dioxide gas shielded welding machine is mainly composed of welding power source, wire feeding mechanism, welding torch and walking mechanism (automatic welding machine), control system, gas supply system and water cooling system (see Figure 2).
Next, let's talk about the welding power source for carbon dioxide gas shielded welding. Carbon dioxide gas shielded welding usually uses a DC power supply, the no-load voltage is 55~85V, the welding current is 50~500A, and the load duration of the power supply is 50%~60%. Carbon dioxide gas shielded welding adopts the reverse polarity connection method of DC power supply. External characteristics of the welding power source: when the diameter of the welding wire is less than 1.6mm, the flat characteristic power source is widely used. This is because it is more convenient to adjust the welding parameters of the flat characteristic power supply with the constant speed wire feeding system, the automatic adjustment of the system is strong, and the arc ignition is also more convenient; when the diameter of the welding wire is > 2.0mm, usually the descending characteristic power supply is used to match the variable speed transmission. wire system. The first is the requirements for the external characteristics of the power supply. Since the no-load voltage of the completely flat-hard external characteristic power supply is too low, it is not conducive to the ignition of the arc. Therefore, at present, the filament carbon dioxide gas shielded welding adopts an ideal L-shaped external characteristic power supply, that is, a high no-load voltage is convenient for the ignition of the arc. Arc ignition and appropriately limited short-circuit current. When in the normal welding parameter area, it has flat and hard characteristics. The second is the requirements for the dynamic characteristics of the power supply. According to the characteristics of drop short-circuit transition, the power supply is required to have a suitable short-circuit current growth rate. Usually in filament carbon dioxide gas shielded welding, the short-circuit current growth rate is 70~150kA per second. Within this range, the growth rate of the short-circuit current can generally be adjusted by connecting an inductor in series in the DC loop, and the inductance value is determined according to the needs of the welding process. Third, the requirements for the adjustment characteristics of the welding power source. In order to obtain the required different welding current values, the external characteristics of the power source must have countless sets of external characteristic curves that can be uniformly changed, so as to intersect with the arc static characteristic curve at the required operating point to obtain a series of stable operating points.
Then talk about the wire feeding mechanism, welding torch and gas supply system of carbon dioxide gas shielded welding. First, the wire feeding mechanism. It is mainly composed of hose, wire feed roller, deceleration mechanism and remote control. There are three types of wire feeding methods: pull type, data type and push-pull type. Push wire feeding is commonly used. Although the pull-type wire feeding can be operated in a large range, the welding torch is heavy, and it is not convenient to connect, and it is only suitable for filaments below ф0.8mm; and the push-pull wire feeding also has the problem of complicated structure of the welding gun. . Second, the welding gun. Welding torches for carbon dioxide gas shielded welding can be divided into semi-automatic welding torches and automatic welding torches according to the operation mode; air-cooled and water-cooled welding torches according to the cooling method; gooseneck and pistol-type welding torches according to the structure. The welding torch is composed of a contact tip, a nozzle, a spring tube, a conductive rod, a switch, a handle, a trigger, an air intake pipe and a gas valve. Semi-automatic welding guns usually come in gooseneck and pistol styles. Gooseneck torches are the most widely used, as shown in Figure 4. It is suitable for thin welding wire and is flexible and convenient to use. The basic structure of the automatic welding gun is the same as that of the semi-automatic welding gun, but its current carrying capacity is larger and the working time is longer, and water cooling is generally used. Third, the air supply system. The gas supply system consists of gas cylinders, decompression flowmeters (with preheaters), electromagnetic gas valves, and leather pipes. Since carbon dioxide gas absorbs a lot of heat when it changes from liquid to gas, it is easy to cause local severe cooling. In addition, when the gas volume expands after passing through the pressure reducer, the gas temperature will also drop, so it is easy to cause the pressure reducer to appear hoarfrost, freeze, cause gas circuit blockage, and affect the smooth progress of the welding process. Therefore, carbon dioxide gas must be Preheat before depressurizing.
It can be seen that in carbon dioxide gas shielded welding work, in order to obtain a good welding effect, the selection of welding equipment is very important, especially the choice of carbon dioxide gas shielded welding welding machine. The welding machine produced by our Kingsiri is an innovative product in traditional welding technology, which is very suitable for the development needs of modern welding. So as to obtain better welding effect.
Keywords: welding machine
Originally published 24 Mar 2022, updated 24 Mar 2022.