[Submerged Arc Welder]Working Principle of Submerged Arc Welder Features of Submerged Arc Welder Maintenance
Working Principle of Submerged Arc Welder strong>
A submerged arc welding machine is a welding machine that uses an arc to burn under the flux layer for welding. Its inherent advantages of stable welding quality, high welding productivity, no arc light and little smoke make it the main welding machine in the production of pressure vessels, pipe section manufacturing, box-beam-column steel structures, etc. In recent years, although many new types of high-efficiency and high-quality welding machines have appeared successively, the application field of submerged arc welding machines has not been affected in any way. From the perspective of the weight share of deposited metal of various fusion welding machines, submerged arc welding machines account for about 10% and have not changed much over the years.
Submerged arc welding can be divided into automatic submerged arc welding and semi-automatic submerged arc welding. In the former, the relative movement of the arc and the feeding of the welding wire are done mechanically, while the latter is moved by the operator holding the welding torch, and the feeding of the welding wire is automatic. Submerged arc welding is a mechanized fusion welding method using arc as a heat source. Due to the low labor intensity of automatic submerged arc welding, it is widely used in production, while semi-automatic submerged arc welding is rarely used.
The arc heat locally melts the wire, flux and base metal and partially evaporates. Metal vapor and flux vapor form a cavity in the arc area. The molten metal pool formed by the molten wire and base metal is located at the bottom of the cavity; the slag formed by the molten flux is located at the top of the cavity. This cavity not only protects the arc and weld pool from contact with air, but also shields the arc.
As the arc moves forward, the arc force pushes the liquid metal backward and gradually cools and solidifies into a weld, and the slag solidifies into a slag shell covering the weld surface. During the welding process, the slag not only protects the molten metal pool and the weld metal, but also has a metallurgical reaction with the molten metal, thereby affecting the chemical composition and mechanical properties of the weld metal, preventing defects such as cracks and pores in the weld, and not melting after welding. The flux is cleaned and recycled separately.
During submerged arc welding, since the wire feeding mechanism continuously feeds the welding wire, and the end of the welding wire is continuously melted under the action of the arc heat, in order to maintain the normal welding process, the feeding speed of the welding wire and the melting speed are To be balanced. According to the different application of the welding wire, the welding wire has single wire, double wire and multi wire. Sometimes a flux-cored wire can be used instead of bare wire, or a steel strip can be used instead of wire.
Submerged arc welding machine classification
Submerged arc welding machine is divided into automatic welding machine and semi-automatic welding machine Two categories.
Semi-automatic submerged arc welding machine
The semi-automatic submerged arc welding machine is composed of a welding trolley and a submerged arc welding machine. tune. The main functions of the semi-automatic submerged arc welding machine are:
(1) The welding wire is continuously fed into the arc area through the wire guide tube;
(2) The welding current is transmitted;
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(3) Control welding start and stop;
(4) Apply flux to the welding area.
So it is mainly composed of wire feeding mechanism, control box, welding handle with hose and welding power source. Semi-automatic submerged arc welding machine combines the advantages of automatic submerged arc welding with the mobility of manual arc welding. This welding machine can be used for welding on workpieces that are difficult to achieve automatic welding (such as irregular centerline welds, short welds, workpieces with narrow welding space, etc.).
Automatic submerged arc welding machine
The automatic submerged arc welding machine is composed of submerged arc welding machine and auxiliary equipment, which can achieve automatic welding and automatic submerged arc welding. The main functions of the welding machine are:
(1) Continuously feed welding wire to the welding area;
(2) Transfer welding current;
(3 ) to move the arc along the seam;
(4) Control the main parameters of the arc;
(5) Control the start and stop of welding;
(6 ) Apply flux to the welding area;
(7) Adjust the position of the wire end before welding.
Automatic submerged arc welding machines are made into different forms according to the needs of the work. Common ones are: welding car type, suspension type, machine tool type, cantilever type, gantry type, etc.
Structural Design
Submerged arc welding machine consists of welding power source, welding head and auxiliary equipment. Its power supply can use AC, DC or both. Submerged arc welding equipment consists of three parts: power supply, control cable and trolley. Each part is very important, only with good cooperation can the advantages of submerged arc welding be fully utilized
The power supply requirements are divided into AC and DC. There are magnetic amplifier type, thyristor type and inverter type for DC power supply. The thyristor type is widely used because of its moderate size, high efficiency, reliable operation and low price. The characteristics of the DC power supply: the arc is stable, the reverse polarity connection is adopted, the penetration depth is large, and the molding is beautiful.
Control cable submerged arc welding is in motion for a long time, and the cable is bent for a long time and is easily damaged. The quality of the cable is particularly important, and the welding of the cable and the plug must be reliable. There are countless examples of the equipment not working due to the internal disconnection of the cable, which should attract the attention of the majority of users.
The trolley (welding trolley) is composed of an electrical control box, a motor, and a mechanical transmission device. The trolley works smoothly and reliably.
Welding Features
The submerged arc welding power source can be AC (Arc Welding Transformer), DC (Arc Welding Generator or Arc Welding Rectifier) or AC/DC use together. It should be selected according to specific application conditions, such as welding current range, single or multi-wire welding, welding speed, flux type, etc.
Generally, DC power supply is used for small current range, fast arc ignition, short welding seam, high speed welding, the used flux has poor arc stability and there is a high requirement for the stability of welding process parameters. When using DC power, different polarities will produce different process effects. When DC positive connection is used (the wire is connected to the negative electrode), the deposition rate of the welding wire is the highest; when the DC reverse connection is used (the welding wire is connected to the positive electrode), the weld penetration is the largest.
When AC power is used, the welding wire deposition rate and weld penetration are between DC positive connection and reverse connection, and the magnetic deflection of the arc is minimal. Therefore, the AC power supply is mostly used for high-current submerged arc welding and occasions where the magnetic deflection is severe when using DC. Generally, the no-load voltage of the AC power supply is required to be above 65V.
In order to increase penetration and increase productivity, automatic multi-wire submerged arc welding is increasingly used in industry. Two-wire welding and three-wire welding are the most commonly used. The power source of multi-wire welding can be DC or AC, or AC and DC combined. There are various combinations of welding power source selection and connection during double-wire submerged arc welding and three-wire submerged arc welding.
Advantages of welding machine
High production efficiency: On the one hand, the conductive length of the wire is shortened, and the current and current density are increased, so the arc penetration and wire deposition are Efficiency is greatly improved. (Generally, one-side melting depth can reach 20mm without grooves.) On the other hand, due to the thermal insulation effect of flux and slag, there is basically no heat radiation loss on the arc, and there is little spatter, although the heat loss for melting the flux is increased, but the overall thermal efficiency is still greatly increased.
High quality of welding seam: The slag has a good protection effect against the air, and the welding parameters can be kept stable through automatic adjustment.
Good labor conditions: In addition to reducing the labor intensity of manual welding operations, it has no arc radiation, which is a unique advantage of submerged arc welding.
Automatic welding can be achieved. Continuously feed welding wire to the welding area, transmit welding current, move the arc along the seam, control the main parameters of the arc, control the start and stop of welding, apply flux to the welding area, and adjust the position of the wire end before welding.
When automatic welding: welding parameters can be kept stable by automatic adjustment. Compared with manual arc welding, the dependence of welding quality on the skill level of the welder can be greatly reduced.
Maintenance of Submerged Arc Welding Machine
Submerged arc welding machine is a more complicated and expensive welding equipment, maintenance is very important.
1. The equipment should be used by special personnel. The operator should have an understanding of the basic principles of the equipment, and reasonably use the welding process specification for welding. The personnel should be trained and assessed;
2. Submerged arc The welding equipment should be cleaned regularly and the contact tip and wire feeder should be replaced;
3. The inlet and outlet wires of the power supply and the grounding wire must be well connected;
4. The control cable is connected to the trolley The end should be fixed, so that it will not be severely bent and damaged, and it will fail.
Maintenance of submerged arc welding machine
If the equipment fails, it should be checked from three aspects: power supply, control cable, and trolley.
1. Welding power source inspection
a. Turn on the power switch, put the transfer switch to the manual welding position, the power output Whether the voltage is displayed within the specified value range, and if it does not reach the specified value, the control circuit board should be replaced for testing;
b. Check whether the fuse is in good condition, and whether the input three-phase voltage (380V110%) is normal, and check the control Whether the voltage of all levels of the transformer is within the specified value. If there is a problem, replace the control transformer;
c. Check whether the relays can operate normally, and replace the device if there is a problem.
d. Check whether the temperature relay is turned on at normal temperature, and the cooling fan Check whether the operation is normal, if there is a problem, replace the device; The resistance between the cathode and the anode should be greater than 1 megohm, less than when the insulation performance between the electrodes is poor, and a resistance value of zero indicates breakdown.
2, control cable inspection
The control cable is in motion for a long time, and it is easy to break. Measure the on-off condition according to the numbers at both ends of the cable, and there are spare lines available for connection if they are broken.
3, Checking the car failure
a. Press the car forward and backward button, whether the car can walk, adjust The speed knob can change the line ten degrees. Press the wire feed button to check whether the wire feed wheel can be forward or reversed. If there is any problem, check the fuse wire and whether the small relay is damaged;
b. The welding adjustment switch should be placed in the automatic welding position to check. When no welding wire is installed, press the welding button to feed the wire when no load Whether the wheel is spinning slowly. When the voltage drops to “v to 28V, the wire feeding wheel should rotate quickly
, when the short-circuit voltage is zero, the wire feeding wheel should be reversed (drawing wire), if it is not normal, the control circuit board should be replaced;
c. The wire feeding is unstable, check whether the teeth of the wire feeding wheel are damaged, and replace the damaged ones. Whether the pressing device is properly adjusted.
required by the repairer
The product quality of submerged arc welding machines is constantly improving, and the repair of equipment is very important. The conditions that repair personnel should have:
1. Understand the production process of the product;
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2. You should be familiar with the quality inspection, testing, testing and standards of the product;
3. Generally, you should have the electrical foundation of technical secondary school.
4. To Prepare some repair materials and tools, such as power control panels, trolley control panels, control transformers, relays, switches, fuses, etc. Only in this way can the repair work be carried out smoothly.
