CN107598379A - A kind of slab double-sided laser MIG composite weldings and MIG cover welding new methods - Google Patents

Abstract

The invention discloses a new method for double-sided laser MIG composite welding and MIG cover welding of thick plates, which comprises the following steps: step 1, simply processing the inclusions and oxide films on the blunt edge of the thick plate to be welded; step 2, using a laser to Perform the first welding on the front side of the thick plate; step 3, turn over and fix the thick plate, and use the laser to perform the second welding on the reverse side of the thick plate; step 4, remove the laser, and use MIG welding to obtain the results obtained in steps 2 and 3 The surface of the weld seam is covered by welding. A new method of double-sided laser MIG composite welding and MIG cover welding of thick plates of the present invention greatly simplifies the preparatory work before welding, simplifies the complicated welding process as much as possible, improves production efficiency; improves weld formation, avoids and eliminates welding Defects, eliminate pores, improve the quality and strength of welded joints, and the plate thickness suitable for welding is larger.

Description

A new method for double-sided laser MIG hybrid welding and MIG cover welding of thick plates

technical field

The invention relates to the field of material processing, in particular to a new method for double-sided laser MIG composite welding and MIG cover welding of thick plates.

Background technique

Thick plate welding is widely used in engineering, such as ships, pipelines, pressure vessels and so on. The difficulty of thick plate welding is that it is impossible to penetrate the thick section at one time, so multi-layer multi-pass welding is required. This leads to complex and trivial groove processing and preparation; root cleaning and grinding during welding, resulting in a reduction in welding efficiency and deterioration of mechanical properties.

At present, there are three main implementation schemes for thick plate welding, namely submerged arc welding (SAW), gas metal arc welding (GMAW), laser beam welding (LBW) and laser arc hybrid welding. Welding (hybrid laser-arc welding, HLAW).

1. Submerged arc welding. Submerged arc welding is a welding method in which an arc burns under a layer of flux. The plate needs to be processed into a K-shaped groove, and the gap between the plates must also be controlled. The welding heat input is large, and the performance of the welded joint decreases.

2. MIG shielded welding. Gas metal arc welding is a welding method that uses the arc generated between the welding wire and the workpiece as a heat source to melt the metal. Complicated X-shaped bevels need to be processed before welding, polished before welding, and root cleaned after the first pass of welding. Six alternate welds are required to complete the connection of the two boards.

3. Laser welding. Laser welding is a high-efficiency and precise welding method in which focused laser beams are used as energy to bombard weldments with heat generated by welding. Through the optimization of laser power and welding speed, medium-thickness plates of various materials such as low-carbon steel, low-alloy high-strength steel, aluminum alloy, titanium alloy, nickel-based alloy, etc. can be successfully welded by laser single-pass penetration welding, and the welding thickness can reach 20mm. But laser welding has a lot of spatter and is a welding method without filler material. When welding thick plates, the laser power is generally very large, which increases the generation of spatter. Therefore, the surface profile is generally poor during laser welding of thick plates. Moreover, during laser deep fusion welding, the collapse of the keyhole can easily lead to the generation of pores. reduce the mechanical properties of the joint.

4. Laser arc hybrid welding. Laser arc hybrid welding is a new welding method that combines two independent heat sources of laser and arc. It combines the advantages of both and avoids the disadvantages of both. For example, a laser beam with high energy density can achieve a large penetration depth, while the electric arc can fill the metal material and improve the weld shape. However, due to the complex coupling between the laser and the arc, there are many process parameters that need to be adjusted, so the spatter during the welding process is also very large, the weld shape is worse, and defects such as undercut, unfilled, and hump are prone to occur. Porosity is also often prone to occur in welds. For example, when aluminum alloy is welded by laser arc hybrid welding, the surface of the weld is poorly formed, the root is severely drooped, and there are also large pores in the weld section, which eventually leads to a significant decrease in tensile strength.

At present, there are mainly four methods for thick plate welding. Although they can achieve the purpose of thick plate welding to a certain extent, their disadvantages are very obvious, such as heavy and complicated preparation of test plate, complicated welding process, low welding efficiency, many defects of welded joints obtained, and low strength.

Therefore, those skilled in the art are committed to developing a new method for thick plate double-sided laser MIG composite welding and MIG cover welding, which greatly simplifies the preparation work before welding, simplifies the complicated welding process as far as possible, and improves production efficiency; Seam forming, avoid and eliminate welding defects, eliminate air holes, improve the quality and strength of welded joints, and the plate thickness suitable for welding is larger.

Contents of the invention

In view of the above-mentioned defects of the prior art, the technical problem to be solved by the present invention is to develop a new method for double-sided laser MIG composite welding and MIG cover welding of thick plates, which greatly simplifies the preparatory work before welding and simplifies complex welding as much as possible. process, improve production efficiency; improve weld formation, avoid and eliminate welding defects, eliminate air holes, improve the quality and strength of welded joints, and the plate thickness suitable for welding is larger.

To achieve the above object, the present invention provides a new method for double-sided laser MIG composite welding and MIG cover welding of thick plates, comprising the following steps:

Step 1. Simple treatment of inclusions and oxide films on the blunt edge of the thick plate to be welded;

Step 2. Use a laser to perform the first welding on the front side of the thick plate;

Step 3. Flip and fix the thick plate, and use the laser to perform the second welding on the reverse side of the thick plate;

Step 4, remove the laser, and use MIG welding to cover the surface of the weld seam obtained in steps 2 and 3.

Further, step 1 also includes simply scrubbing the thick plate once or twice with alcohol or acetone as needed.

Further, use a wire brush to simply clean the inclusions and oxide film on the thick plate.

Further, the laser is preferably an IPG fiber laser, the laser power is set to 10kw, and the welding speed is set to 0.6m/min.

Further, the welding power source is preferably Fronius TransPuls Synergic 5000CMT, and the robot is preferably KUKA KR60HA.

Further, the weld bead obtained by the first welding pass in step 2 overlaps with the weld bead obtained by the second pass welding in step 3 by at least 2 mm.

Further, the thickness of the thick plate is set to be 20mm-40mm.

Further, the thickness of the thick plate is preferably 30mm.

Further, the welding parameters of MIG welding in step 4 are set as welding current: 136A; welding speed: 0.6m/min.

technical effect

1. Greatly simplify the preparation work before welding, simplify the complicated welding process as much as possible, and greatly improve the production efficiency;

2. Improve weld formation, avoid and eliminate welding defects, eliminate air holes, and improve the quality and strength of welded joints as much as possible;

3. Propose a new welding method to make the plate thickness suitable for welding larger.

The idea, specific structure and technical effects of the present invention will be further described below in conjunction with the accompanying drawings, so as to fully understand the purpose, features and effects of the present invention.

Description of drawings

Fig. 1 is the schematic diagram of a kind of thick plate double-sided laser MIG hybrid welding and MIG cover welding new method of a preferred embodiment of the present invention.

detailed description

As shown in Figure 1, a preferred embodiment of the present invention provides a kind of thick plate double-sided laser MIG composite welding and new method of MIG cover welding, comprises the following steps:

Step 1. Simple treatment of inclusions and oxide films on the blunt edge of the thick plate to be welded;

Step 2. Use laser 1 to perform the first welding on the front side of the thick plate;

Step 3. Flip and fix the thick plate, and use the laser to perform the second welding on the reverse side of the thick plate;

Step 4, remove the laser, and use MIG welding to cover the surface of the weld seam obtained in steps 2 and 3.

Specifically, in this embodiment, the plate thickness used is 30 mm. In order to simplify the preparation work before welding as much as possible, there is no need to process the groove of the test plate to be welded before welding, and there is no need to leave a gap during welding. In step 1, use a wire brush to simply clean the inclusions and oxide film on the thick plate. Also, briefly scrub the slab one or two times with alcohol or acetone as needed.

As shown in 1, in steps 2 and 3, the laser power is set to 10kw, and the welding speed is set to 0.6m/min. Specifically, in a preferred embodiment of the present invention, the laser 1 is preferably an IPG fiber laser with a maximum output power of 10kW. The welding power source is Fronius TransPuls Synergic 5000CMT. Welding robot 2 is KUKAKR60HA. At present, the maximum laser power of industrial lasers commonly used in welding is very limited. Therefore, in order to increase the weldable plate thickness as much as possible under the limitation of limited laser power, a new method of the present invention is proposed: First, through laser arc hybrid welding The method is to weld the first pass on the front side, then turn the board over and fix it, and then weld the second pass on the reverse side. It is worth noting that in order for the boards to be connected effectively, an overlap of at least 2mm should be ensured between the two weld beads. Moreover, since the first pass cannot penetrate the entire test plate during double-sided welding, the defect of root drooping can be effectively avoided.

In laser arc hybrid welding, the welding speed has a significant effect on the weld penetration. When welding thick plates, it is hoped to obtain as large a penetration depth as possible, so the welding speed should not be too fast. On the premise of ensuring welding stability, the welding speed should be slowed down appropriately. In addition, if the welding speed is too fast, the welding process will be unstable, keyhole collapse will occur frequently, and many air bubbles will be trapped under the molten pool. There are many pores. And there is overlap between the two weld beads, which ensures the complete fusion and good connection of the weld joint. When the process parameters and welding speed are adjusted, especially when the welding speed is slow, the air bubbles in the keyhole have enough time to run up and eventually become trapped by the solidified weld metal. It also laid the foundation for the subsequent complete elimination of pores. In addition, due to the presence of spatter, etc., the surface shape of the weld is relatively poor.

Therefore, we need to adjust the weld surface with step 4. Although the welded joint obtained by the double-sided welding method of step 2 and step 3 is connected, there are many small pores on the surface of the weld, and there are usually undercuts on the surface of the weld, welding defects such as unfilled. Defects such as undercut and unfilled are surface defects, but fortunately, all pores are controlled by the welding process so that they only appear on the surface of the weld bead. Therefore, a preferred embodiment of the present invention provides a method for eliminating air holes using an arc cover. The arc welding process is mature and stable. As long as the welding process is selected reasonably, the surface of the obtained weld seam is bright and clean, and there are no defects such as undercut. Arc welding will re-melt the surface of the weld bead, so the closed air bubbles existing on the surface of the weld bead are dissolved, and gradually escape from the liquid metal and enter the air under the action of factors such as buoyancy and molten pool flow, when the weld metal solidifies After coming down, all the pores are gone. Therefore, the method of covering the surface by arc welding simultaneously suppresses surface defects and eliminates welding porosity left by double-sided welding. Wherein, the welding parameters of MIG welding in step 4 are set as welding current: 136A; welding speed: 0.6m/min.

In another preferred embodiment of the present invention, the thickness of the thick plate is set at 20mm-40mm. The thickness of the slab is preferably 30 mm.

The preferred specific embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make many modifications and changes according to the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning or limited experiments on the basis of the prior art should be within the scope of protection defined by the claims.

Claims (9)

1. A new method for thick plate double-sided laser MIG composite welding and MIG cover welding, is characterized in that, comprises the following steps: Step 1. Simple treatment of inclusions and oxide films on the blunt edge of the thick plate to be welded; Step 2, using a laser to perform the first welding on the front side of the thick plate; Step 3, turning over and fixing the thick plate, and using the laser to perform a second welding on the reverse side of the thick plate; Step 4, removing the laser, and using MIG welding to cover the surface of the weld seam obtained in the step 2 and the step 3. 2. A new method for double-sided laser MIG composite welding and MIG cover welding of thick plates as claimed in claim 1, characterized in that said step 1 also includes simply scrubbing said thick plates with alcohol or acetone as required Once or twice. 3. A new method for double-sided laser MIG composite welding and MIG cover welding of thick plates as claimed in claim 2, characterized in that the inclusions and oxide films of the thick plates are simply cleaned with a wire brush. 4. A new method for double-sided laser MIG composite welding and MIG cover welding of thick plates as claimed in claim 1, wherein the laser is preferably an IPG fiber laser, the laser power is set to 10kw, and the welding speed is set to 10kw. Set to 0.6m/min. 5. A new method for double-sided laser MIG hybrid welding and MIG cover welding of thick plates as claimed in claim 4, characterized in that the welding power source is preferably Fronius TransPuls Synergic 5000 CMT, and the robot is preferably KUKAKR60HA. 6. The new method of double-sided laser MIG composite welding and MIG cover welding of a thick plate as claimed in claim 1, characterized in that, the weld bead obtained by the first welding in the step 2 is the same as that obtained in the step 3 The weld beads obtained by the second welding pass have at least 2 mm overlap. 7. A new method for double-sided laser MIG hybrid welding and MIG cover welding of thick plates according to claim 1, characterized in that the thickness of the thick plates is set to 20mm-40mm. 8. A new method for double-sided laser MIG hybrid welding and MIG cover welding of thick plates as claimed in claim 7, characterized in that the thickness of the thick plates is preferably 30mm. 9. a kind of thick plate double-sided laser MIG composite welding and MIG cover welding new method as claimed in claim 1, it is characterized in that, the welding parameter of the described MIG welding in the described step 4 is set to: welding current : 136A; welding speed: 0.6m/min.