Problem description:
What are the welding types? Such as full welding, continuous welding ...
Where do you need to find these? You'd better answer them directly. Thank you.
Analysis:
Tell me in detail.
There are many welding forms, such as brazing, arc welding, resistance welding, laser welding and electron beam welding.
The following are introduced respectively:
I. Brazing
Brazing is to use a metal with a lower melting point than the base metal as the brazing filler metal. After heating, the solder melts, but the weldment does not. The liquid solder is used to wet the base metal, fill the joint gap and diffuse with the base metal to firmly connect the weldments.
According to the different melting point of solder, brazing can be divided into soldering and brazing.
(1) Soft soldering: The melting point of soft soldering solder is lower than 450℃, and the joint strength is lower (less than 70 MPa).
(2) Brazing: The melting point of the solder is higher than 450℃, and the joint strength is higher (above 200 MPa).
The bearing capacity of brazed joint is related to the size of joint connection surface. Therefore, lap joints and sleeve joints are generally used in brazing to make up for the lack of brazing strength.
Second, arc welding
The fusion welding method using electric arc as heat source is called arc welding. It can be divided into manual arc welding, automatic submerged arc welding and gas shielded welding. The biggest advantage of manual automatic welding is its simple equipment, flexible and convenient application and wide application, and it can weld various welding positions, straight seams, circumferential seams and various curved welds. Especially suitable for frequent operation and welding of short welds; Automatic submerged arc welding has the characteristics of high productivity, good weld quality and good working conditions. Gas shielded welding has the characteristics of good protection effect, stable arc and concentrated heat.
Third, resistance welding.
Resistance welding is a welding method which uses the resistance heat generated between the workpiece and the welding contact surface to heat the workpiece to a plastic or local melting state, and then applies pressure to form a welded joint.
Resistance welding can be divided into spot welding, seam welding and butt welding.
(1) Spot welding: the weldment is pressed between two columnar electrodes, electrified and heated, so that the weldment melts at the contact point to form a nugget, then the power supply is cut off, and solidified and crystallized under pressure to form a welded joint with compact structure.
Spot welding is suitable for welding thin plates (lap joints) and steel bars below 4 mm, and is widely used in the production of automobiles, airplanes, electronics, instruments and daily necessities.
(2) seam welding: seam welding is similar to spot welding, except that the rotating disc electrode is used instead of the cylindrical electrode. The superimposed workpiece is energized between the disks under pressure and fed to form a continuous weld with the rotation of the disks.
Seam welding is suitable for welding overlapping thin plates with thickness below 3 mm, mainly used for producing sealed containers and pipelines.
(3) Butt welding: According to different welding processes, butt welding can be divided into resistance butt welding and flash butt welding.
The process of 1) resistance butt welding is to apply upsetting pressure (10 ~ 15 MPa) to make the joint of the workpiece closely contact, and then apply upsetting pressure (30 ~ 50 MPa) and cut off the power supply at the same time, so that the weldment can be welded under pressure to produce plastic deformation.
Resistance butt welding is simple in operation and smooth in joint shape, but it requires high processing and cleaning of butt welding parts, otherwise the contact surface will be unevenly heated, resulting in defects such as oxide inclusion and incomplete penetration, which will affect the welding quality. Therefore, resistance butt welding is generally only used for welding workpieces with a diameter less than 20 mm, a simple cross section and small stress.
2) Flash butt welding process is to electrify first, and then make two weldments slightly contact. Because the surface of the weldment is uneven, the current density passing through the contact point is very high, and the metal melts, gasifies and explodes quickly, splashing sparks and producing flash phenomenon. Continue to move the weldment, resulting in new contact points, and the flash phenomenon continues to occur. When the end faces of the two weldments are completely melted, the pressure is applied quickly, and then the power supply is cut off to continue the pressure welding of the weldments.
Flash is good for the quality of welding joint, and the requirement of cleaning the joint surface before butt welding is not high. It is often used to weld important workpieces with high stress. Flash butt welding can weld not only the same metal, but also different metals such as aluminum steel and aluminum copper, such as 0.0 1 mm metal wire, 500 mm diameter pipe and 20 000 mm2 plate.
Fourthly, laser welding.
Laser welding uses the focused laser beam as energy to bombard the workpiece for welding.
Laser welding has the following characteristics:
1) The laser beam has high energy density, extremely short heating process, small solder joint, narrow heat affected zone, small welding deformation and high dimensional accuracy of weldments;
2) It can weld materials that are difficult to be welded by conventional welding methods, such as refractory metals such as tungsten, molybdenum, tantalum and zirconium;
3) Non-ferrous metals can be welded in air without additional shielding gas;
4) The laser welding equipment is complicated and the cost is high.
Laser welding can weld low-alloy high-strength steel, stainless steel, copper, nickel, titanium alloy and so on. Heterogeneous metals and nonmetallic materials (such as ceramics and plexiglass). ); At present, it is mainly used in electronic instruments, aviation, aerospace, atomic nuclear reactors and other fields.
Verb (abbreviation for verb) electron beam welding
Electron beam welding uses focused high-speed electron beams to bombard the welding surface in vacuum, so that it melts instantly and forms a welded joint.
Electron beam welding has the following characteristics:
1) High energy density and strong electron penetration;
2) the welding speed is fast, the thermal influence is cancelled, and the welding deformation is small;
3) Good vacuum protection and high welding quality, especially suitable for welding live wave metals.
Electron beam welding is used to weld low alloy steel, nonferrous metals, refractory metals, composite materials, dissimilar materials and so on. Both thin and thick plates can be used. It is especially suitable for welding thick parts and weldments requiring small deformation, devices used in vacuum, precision micro devices, etc.
It is estimated that the owner refers to the method of manual arc welding. (It is the kind that we usually see construction workers holding welding guns. )
Simply list a few:
Spot welding: After the parts are fixed at the beginning of welding, covered electrode is used to spot several welding spots on the contact seam, so that the parts are simply welded together, which is called spot welding, which is convenient for reshaping the welding parts when welding continues. However, spot welding can be re-tapped in the case of poor shape and position and offset.
Full welding: all the contact points of two workpieces to be welded are welded together. For example, two steel plates are spliced and one weld is fully welded, which is used when high welding strength is required.
Flower welding: under the condition that the connection strength is not too high, welding can be carried out intermittently, that is, one section is welded, and the other section is flower welding.
Surfacing: After the parts are damaged, they can be welded without manufacturing new parts, and surfacing is carried out at the damaged parts. If the damaged part is too large, filler can also be added to the gap for surfacing welding (without affecting the use strength requirements).