What is multi layer multi pass welding? What is the concept of this thing?

When welding the size of the welding legs.

When the weld is larger than 10mm, if multi-layer welding is used, the molten metal is easy to sag due to the wide surface of the weld and the large slope, which brings certain difficulties to the operation. Therefore, multi-layer multi-pass welding is used in actual production.

When the size of the welding leg is 10 12mm, it is generally completed with two layers and three passes. When welding the first layer (first pass), a smaller diameter electrode and a larger welding current can be used, and the linear strip method is used to finish the same as the first layer of multi-layer welding. Remove the slag after welding.

When welding the second weld, it should cover not less than 2 3 of the first layer of weld, and the angle between the electrode and the horizontal plate should be slightly larger (a in Fig. 2), generally 45 ° 55 °, so that the molten metal and the horizontal plate are well fused.

The angle between the welding rod and the welding direction is still 65° 80°, and the speed of the rod is the same except for the point C and point E in Figure 2-9. When welding, it should be noted that the molten metal and the horizontal plate should be well fused, and when the third weld is welded, 1 3 1 2 of the second weld should be covered.

The angle between the welding rod and the horizontal plate is 40° 45°, and the angle is too large to cause the deviation of the welding foot. Generally, the linear strip method is adopted, and the welding speed should be uniform, not too slow, because the slow speed is easy to produce welding tumors, so that the weld forming is not beautiful.

1. Multi-layer welding

1. Refers to the deposition of more than two weld layers to complete the welding of the whole weld, and each layer of the weld is completed by a weld bead, and the deposition of more than two weld layers completes the welding of the whole weld, when the weld is relatively large in the welding process, multi-layer welding is required, and multi-layer welding is often associated with multi-pass welding.

Second, the advantages of multi-layer welding:

2. The advantage of multi-layer welding is that it can weld large-walled structures, and compared with single-layer welding in the same situation, it can also reduce the heat input, reduce deformation, and reduce the probability of defects.

Multi-pass welding: Welding of the entire weld seam by two or more weld beads.

Multi-layer welding: Two or more weld layers are deposited to complete the welding of the entire weld.

The above two are added up to be called multi-layer multi-pass welding.

Just send you a picture to see.

Multi-layer refers to the welding weld with more than one layer, and multi-layer refers to more than one weld.

The number of layers is more than 2, and each layer has more than 2 beads

It's an advanced technology.

Dear, hello, we are glad to answer for you: what should be paid attention to in the joints of multi-layer multi-pass welding? A, pro:

1. Welding of the base layer. When the base material is welded first, the root or surface of the weld bead should be 1-2mm away from the composite interface. The residual height of the weld should be in line with the relevant standards.

Depending on factors such as substrate thickness, steel grade, and structure, appropriate preheating treatment can be applied if necessary. 2. Welding of transition layer. When welding the transition layer, it is necessary to minimize the amount of melting into the base metal and reduce the fusion ratio on the premise of ensuring good fusion.

For this purpose, a smaller diameter electrode or wire should be used, as well as a small amount of wire energy. The thickness of the transition layer should not be less than 2mm. 3. Welding of multiple layers.

When welding the lamination, it is necessary to pay attention to protecting the surface of the lamination, preventing welding spatter from damaging the surface of the lamination, and shall not arbitrarily trigger the arc, weld karan, lifting ring and temporary bracket on the surface of the lamination. The surface of the laminated weld should be as smooth and smooth as possible with the laminated surface. The residual height of the butt weld is not greater than.

1. Multi-pass welding: the welding of the entire weld is completed by more than two welds.

Multi-layer welding: Two or more weld layers are deposited to complete the welding of the entire weld.

Multi-layer welding includes multi-layer single-pass welding and multi-layer multi-pass welding, a layer of weld can be composed of a number of weld passes, if the groove angle is small, the deposition can be a layer, the groove angle is larger, and the deposition of two or more weld passes can form a layer of weld, which is multi-pass welding.

Thick plate vertical welding, multi-layer multi-pass surfacing welding, which is implemented in the industry, and the use of robot automation welding is a very difficult welding technology.

2. Reduce labor intensity: people in the industry know that a weld of thick plate surfacing sometimes needs to be continuously welded for half an hour or more than 1 hour, light radiation, thermal radiation, smoke and on-site temperature are extremely harmful to the human body, and the use of robot surfacing can reduce the labor intensity of workers, and hand over the repetitive simple actions to the robot to do, and release workers to do other processes.

3. Save costs and improve work efficiency: It has been emphasized that it is impossible for robots to completely replace manual labor for the time being. In the actual production of robots, the output is increased without reducing the number of personnel, that is, the efficiency is improved and the cost is saved.

4. Reduce equipment costs: To achieve automatic welding of large equipment, it is sometimes necessary to match a positioner to cooperate with the welding action of the robot to solve the problem of vertical welding. The application of vertical welding multi-layer multi-channel technology reduces the conversion of this equipment.

In the production and manufacturing of electronic components, soldering work is often required. Among them, wave soldering and selective wave soldering are two common welding methods. Although they both use thermal energy to connect electronic components to circuit boards, there are certain differences between them in practical applications.

Wave soldering is a traditional type of welding. In the wave soldering process, the solder is glued to the circuit board where the electronic components are already installed, and then the solder is melted by heating so that it can be bonded to the electronic components and the circuit board to form a complete connection. During the soldering process, the soldering equipment immerses the circuit board in molten solder so that it is connected to the surface of the solder joints covered by the electronic components.

As the solder cools, the solder joints and electronic components are firmly connected to the circuit board....

When welding, any layer of the cover surface is filled with a base, which is a welding method formed by more than one welding bead.

There is a contradiction in this definition! Multi-pass welding: Welding of the entire weld seam by two or more weld beads. If according to this definition, multi-layer welding must belong to multi-pass welding, so how can multi-layer welding also derive multi-layer multi-pass and multi-layer single-pass welding?

The standard just looked at, the whole weld is composed of multiple welds, so multiple layers belong to multiple channels.

Multi-pass welding:

The entire weld is welded by two or more weld beads.

Multi-layer welding: Two or more weld layers are deposited to complete the welding of the entire weld.

The above two are added up to be called multi-layer multi-pass welding.

Multi-layer multi-pass welding skills:

1. Control the welding current, especially when the current is too small, it is easy to contain slag. Therefore, the current should be slightly higher when welding.

2. No or less transport strips to reduce deformation.

3. After each weld is welded, the welding slag must be carefully cleaned to reduce the welding defects of the weld.

For more information, please refer to.

The multi-layer and multi-pass welding techniques of pipes and steel plates have been learned, and you no longer have to look at other people's faces.

If you require a weld size of 10mm, and it's such a large welding specification, then you must not be able to weld well.

The 2-4mm you said should be the post-weld weld margin height requirement is in this range.

First of all, your specification is not adjusted well, the welding current determines the depth of the weld, that is, the thickness of the weld, the simple point is that the current is too large, the welding pool can not be spread, so the most likely problem is that it is not dissolved, and it directly leads to the large residual height of the weld.

Yes, the heat input is reduced, and the temperature between the layers is controlled similarly to other welding methods.