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Basic knowledge of electrode manual welding

Categories:Company News Time of issue:2021-02-24 13:24:07

Manual arc welding is a welding method developed *earlier and still used* in various arc welding methods. It uses a welding rod coated with paint as the electrode and filler metal. The arc burns between the end of the welding rod and the surface of the workpiece. The coating (welding flux) can generate gas to protect the arc under the action of arc heat, and on the other hand, it can generate slag covering the surface of the molten pool to prevent the molten metal from interacting with the surrounding gas. The more important role of slag is to produce physical and chemical reactions with molten metal or add alloying elements to improve the properties of weld metal.

(1) What does the J422 welding rod mean? What materials can be welded? Which electric welder should be used for welding?

Answer: J422 model represents: J structural steel electrode; 42 represents the tensile strength of the weld metal is not less than 42 kg force per square millimeter; 2 represents the titanium calcium type coating, * adapt to DC reverse current welding (that is, if using a DC welding machine When the welding handle is connected to the positive electrode of the DC welding machine); because the arc stabilizing agent is added to the coating of the J422 electrode, the slag fluidity is good, the slag removal is easy, the arc is stable, and the welding wave is neat. It is suitable for all-position welding and is suitable for welding. Most low-carbon steel (wrought iron), and some medium-carbon steel structures with low welding requirements. And AC, DC positive connection and DC reverse connection can achieve better welding results.

(2)..J506 (7) What does the welding rod mean? What materials can be welded? Which electric welder should be used for welding?

Answer: J506(7) electrode is commonly known as medium carbon steel electrode or alkaline low-hydrogen electrode; model representative: J structural steel electrode; 50 represents the tensile strength of weld metal not less than 50 kilograms per square millimeter; 6 (7 ) Represents low-hydrogen potassium or low-hydrogen sodium type coating; this type of electrode is generally suitable for occasions with slightly higher welding requirements (higher tensile strength and wear resistance than J422 electrode), and due to the stability of alkaline coating The arc is poor. At the same time, because the power frequency alternating current is 50HZ, that is to say: within one second, the current crosses the zero point one hundred times, and then re-ignites the arc, and sometimes after the zero point, if there is no re-ignition Arc breaking occurs, so arc breaking, gasping, sticking, etc. are likely to occur when using AC welding machines to weld alkaline electrodes. Therefore, it is generally required to use DC welding power supply for welding, and DC reverse connection is required during use. (The 506 electrode is a low-hydrogen potassium type, it can barely be welded by AC welding, and 507 is a low-hydrogen sodium type coating, it is almost impossible to use AC welding.)

(3). What is a DC welding machine? Does the DC welding machine use DC power? What is its scope of use? What is an AC welding machine? What is its scope of use?

Answer: The meaning of the DC welding machine series ZX: Z stands for rectification and X stands for drop characteristics. It means that the DC welding machine of this machine is after the AC power (220V/380V AC) is input, the high voltage of the power supply is changed to low voltage through the transformer; then the rectification part in the welding machine rectifies the AC power into a DC current (DC) output suitable for welding . The general silicon rectifier welding machines are DC welding machines, and the models generally include ZXE1 (AC/DC dual-purpose welding machine, using moving iron core stepless current adjustment), ZXG (magnetic amplification stepless current adjustment), ZX5 (SCR without The current can be adjusted by remote control.), ZX6 (shift current adjustment), ZX7 (inverter DC welding machine, stepless current adjustment, remote control adjustment) and AX series rotary DC power generation welding machine (the country recommends eliminating Products, power consumption and noise are relatively large.) and other series, except for the ZXE1 model uses two-phase 380V AC, the others use three-phase 380V power supply. Because the current flow of the DC welding machine is fixed, there is no frequent reversal of the current direction of the AC machine, and the current is not zero during normal welding, so the DC welding machine can use almost all brands of welding rods without generating AC machine welding alkaline low hydrogen The phenomenon of arc-breaking, gasping, sticking, etc. when the welding electrode is formed, and stable welding with very small current can be used.

AC welding machines are common BX1 (moving iron core stepless adjustment current), BX3 (moving coil type stepless adjustment current), BX6 (tap gear type adjustment current) and common portable welding machine series, B stands for transformer, X stands for Decline characteristics. Usually use two-phase 380V power supply or 220V power supply. AC welding machine can use ordinary acid electrode, part of alkaline electrode and part of non-ferrous metal and alloy electrode, but its welding current stability is poor, so in some welding situations, such as alkaline low hydrogen electrode and some alloy electrode , Cannot be applied normally. However, due to the simple structure and low price of the AC welding machine, it is still widely used.

(4). What are the advantages and disadvantages of the BX1, BX3, BX6 and other models in the AC series welding machine compared with each other? What should be paid attention to when choosing welding equipment? What are the advantages and disadvantages of the DC welding machine series ZXE1, ZXG, ZX5, ZX6, ZX7, AX and other types of welding machines?

Answer: The BX1 type electric welding machine is a moving iron core type of current adjustment method. Stepless adjustment of current can be realized. BX3 type electric welding machine is a moving coil type current adjustment method. BX6 type is the coil center tap type to adjust the current, generally there are six to seven gear adjustments. Sorting from the performance of the welding machine: BX3* is good, BX1 is second, and BX6* is poor. Because the circuit* of the moving coil adjustment method is complicated, it can increase part of the no-load voltage when the current is small. At the same time, the iron core is larger and the heat dissipation effect is very good. Therefore, the performance of the moving coil welding machine regardless of the current size is significantly better than the other two AC machines. The structure of the BX6 welding machine is relatively simple, the materials used for production are significantly less than the other two, and the price is relatively low. However, since there are only a few gears to adjust the current, current adjustment is very inconvenient. Especially when the current needs to be adjusted accurately, the BX6 machine cannot meet the needs. Regardless of the performance and price of the BX1 welding machine, it is between the above two; so when helping users choose the model, pay attention to it. If considering the performance, the order of sorting should be: BX3--BX1--BX6. And if considering the low price, the sorting order is: BX6--BX1--BX3. In general industrial enterprises, due to the large workload and high welding requirements, the BX3 and BX1 welding machines should be used as much as possible. However, when the welding requirements are not high and the work is not continuous, the BX6 welding machine can be used. Because of its low price and relatively portable equipment, it is widely used in civil applications such as small-scale manufacturing and maintenance.

Among the ZXE1, ZXG, ZX6, ZX5, ZX7, AX and other series of DC welding machines, the AX series of rotary DC generators have the disadvantages of complicated circuits, more materials, high power consumption, and high noise. Now the country has clearly recommended that they be eliminated. There are no domestic manufacturers, but you can still see them in user inventory.

The ZXE1 AC/DC dual purpose model adopts the step-down and regulating circuit of the BX1 electric welding machine, and then adds a single-phase bridge rectifier circuit, so the structure is simple and the current can be adjusted steplessly, but because it still uses It is a two-phase 380V power supply, which is not conducive to the three-phase balance of the power grid, so it limits its scope of use.

The ZX6 type machine adopts a current adjustment method similar to the BX6 type. After passing through the three-phase step-down transformer, a three-phase bridge rectifier circuit is used for rectification. However, due to the inconvenience of current adjustment, its application range is limited. It is also a low-end type among DC welding machines, which is basically suitable for civil occasions.

At present, the most widely used DC models in industrial enterprises are the ZXG and ZX5 electric welding machines. The ZXG type uses the saturation degree of the saturated reactor to control the output current, and the ZX5 type uses the conduction angle of the control thyristor to adjust the current, so it can Stepless adjustment of output current.

At the same time, the technology of these two models is relatively mature and there are fewer problems. In terms of performance, ZX5 is slightly better than ZXG. Since ZX5 adopts thyristor rectifier and electronic circuit adjustment, ZX5 type welding machine can realize remote control, thrust, arc ignition and other functions. Choose the appropriate model, with special welding tongs, which can be used as carbon arc gouging; at the same time, ZX5 The welding machine is better than the ZXG type in terms of volume, weight, and current dynamic response speed. (However, due to product reasons, the ZX5 type of some small factories is not good for carbon arc gouging. The Hugong ZX5 type can completely do carbon arc. Gouging.), but the price of the ZXG machine is slightly lower.

The ZX7 electric welding machine is composed of the current *advanced inverter circuit. Most of the circuits in the machine are composed of electronic components. Because the alternating current of the high frequency inverter can easily pass through the transformer, the transformer can be made extremely small, so the weight is very large. Lightweight, and because the power loss of the transformer part is small, it saves energy. Generally, the power consumption only needs to be less than 50% of the ordinary transformer type welding machine (ZXE1, ZX6, ZXG, ZX5, etc. are all transformer models), and the weight is even more A fraction of the transformer model. At the same time, because it uses advanced inverter electronic circuits, it has more advanced performance, adjustable arc ignition current, thrust current, remote control, current intelligent control, light weight, low power consumption, and particularly high power factor. It has been widely used at present In the field operation industry, at the same time, due to its high efficiency, low labor consumption, excellent performance, and the characteristics of saving manufacturing materials, it has become a development direction of the entire welding industry.