Progressive laser gas welding technology

In the laser gas shielded welding technology, with the launch of the laser beam, there are also two gas shielded welding arcs that also act in the molten pool, and the three welding nozzles are simultaneously integrated in an automatic welding welding head, with additional welding arcs. There is a fundamental difference between laser gas shielded welding technology and traditional laser hybrid welding technology.

There is a fierce competition between laser welding technology and arc welding technology. On the other hand, the combination of the two has innovative effects. In the so-called laser gas shielded welding technology, the combination of the two has a higher welding efficiency and also saves costs. During the professional exhibition of welding and cutting in 2001, Fronius demonstrated for the first time a practical and economic laser protective gas welding equipment. Since then, a total of 65 sets of such welding equipment have been put into industrial applications for mass production in the automotive industry. In the manufacture of automobiles, these laser protective gas welding devices are used for the welding of aluminum alloy and steel axles, doors, and roof frames. The maximum thickness of welded plates can reach 4mm.

Development of new laser gas shielded welding

In 2009, Fronius plans to market lasers and welding and cutting equipment for two welding electrodes. The laser gas protection welding technology adopted in this series of equipment integrates the advantages of both laser welding and gas welding. The versatility and specific advantages of its application arise from the fact that laser and gas shielded welding tips co-occupy one automatic welding head, while the laser welding beam and the two gas shielded welding arcs act together in the weld pool of the welding part.

The first welding test that incorporated laser welding with gas shielded welding dates back to the 1980s. But for 20 years, this technology has been paralyzed in the laboratory and has never taken the door to the laboratory. In this hybrid welding process, both the laser beam and the welding arc act at the weld of the weld. The laser beam melts deeply into the interior of the weldment with extremely high energy; the MSG gas shielded welding system continuously delivers the welding consumable while generating the welding arc, creating a flat, flat surface weld. This hybrid welding technology combines the advantages of laser welding (high welding speed, small welding heat affected zone, deep weld seam) with the advantages of gas shielded welding (very good weld joint capacity, high weld strength and can pass Consumables used, the ability to purposely improve weld quality).

According to laser gas welding application experience, users hope that the laser gas protection welding equipment is more powerful. The key point is to solve the welding of thicker steel plates, with better melting methods and faster welding speeds. According to the process analysis and use evaluation of Fronius's technicians, it is considered that the laser plus two welding electrodes for the welding electrode is the best solution. In this case, the main problem is that the laser welding tip and the two gas shielded welding tips are integrated in an as small automated welding head as possible. The distance between the laser welding beam and the arc should be as small as possible. (Figure 1). In addition to welding technology factors, the size and movement performance of the welding head and the accessible performance are all technical problems to be solved.

Figure 2 Workpieces with Laser Gas Welding

The main task of the laser light beam is to solve the problem of penetration depth. Before and after the two gas welding torches supplementing the welding material fill the weld seam with high melting power. With this welding process technology, steel plates with a thickness of 8 mm can be welded at a time during high-speed welding. In the manufacturing of machine tools and equipment, high-pressure vessels, and iron and steel industry and railway locomotives, this laser gas welding process can be used to weld structural steels, ferrite/austenite chrome-nickel steels, and dual-phase steels. 2) Fig. 2 is a steel plate workpiece with a length of 1m and a thickness of 2mm. The welding speed is 4.2m/min, and the laser power is 3.7kW.

The newly developed laser gas shielded welding head fully combines the respective advantages of the two welding process technologies. At the same time, the new control software will also better coordinate the simultaneous operation of the two welding technologies and control various parameters in the welding process. Compared with traditional laser welding heads and gas shielded welding heads, users expect this welding head to be used in 5 different welding processes: pure laser welding, laser + brazing, laser + a gas shielded welding, laser + Two gas shielded welds, one or two gas welds.

In the future, the size of the melting power will no longer be the main factor affecting the welding efficiency. The combination of new weld geometry, new weld head material, and tip material will be the main factors affecting penetration and weld length per unit time.

Compared with the original generation of laser gas shielded welding technology, a new generation of laser gas welding process technology has a higher production capacity. It has multiple power supplies. From the point of view of the total power, the procurement cost is lower compared with the pure laser welding equipment; compared with the gas welding of double welding tips, the cost of its protective gas and welding accessories More provinces; based on the length of the welds for comparison, the labor costs paid are lower.

Saves the processing cost of weld bevels

The chemical composition of the welding consumables can be adjusted during smelting. For example, if the consumables are used only for gas shielded welding, the toughness can be increased by adding certain chemical components, and the cold cracking resistance of the weld can be significantly improved. At the same time, it also helps to increase the fluidity of the molten metal in the bath. The new laser gas shielded welding technology allows larger tolerances on the weld bead of the weldment, which also greatly facilitates the preparation of the weld seam, unlike strictly laser welding, which has strict tolerance requirements, thus saving on the preparation cost of the groove.

Compared with gas shielded welding, the new laser gas shielded welding technology also has less heat transfer into the parent metal, which reduces the deformation of the parent metal and reduces the amount of post-welding workpiece work. In the case of fillet welding, the weld volume of the new laser gas shielded welding is small with the same mechanical strength of the weld. Unlike traditional fillet welds where the weld seam is located on the surface of the fillet weld workpiece, the new laser gas shielded weld seam welds deep into the interior of the weldment under the action of the laser and is no longer merely welded to the surface of the fillet weldment. The same is true for a 4mm penetration. The size of an ordinary fillet weld is 4mm, whereas the new laser gas shielded weld has a size of only 2mm and an additional 2mm deep inside the workpiece (see Figure 3). This effect also brings about smaller welding distortions and better assembly of the weldment.

Fig. 3 Comparison of ordinary fillet welding and laser gas welding

In the direct comparison of the new and old laser gas shielded welding technology for single and double gas protection welding tips, the following data clearly demonstrates the advantages of the double welding tip: weldable weld width increases by 25%; welding speed increases by 50% to 100%; When the welding speed is the same, the welded weld volume increases by 50%.

In the most typical fillet welding in machinery manufacturing, this welding process technology significantly improves the welding quality of two 2 mm thick steel fillet welds. The highly concentrated laser beam forms a model-like deep pool, and the two gas-protected welding tips form the best surface-covering welds, one deep and one shallow, with perfect fit (Figure 4).

Figure 4 Corner welds of lap joints

New laser gas welding high efficiency

After a large number of laboratory tests, Fronius R&D designers also confirmed the economic advantages of the new laser gas shielded welding technology: Only one welding material, such as G3Sil material, can be used for investment in laser gas shielded welding. Recovered within ~10 years.

The high speed brought by the automatic welding equipment also adds a lot to the laser gas welding technology. For example, four gas protection welding equipments have been used for welding pressure vessels (see Figure 5) for a long time. Using laser gas welding technology requires only one welding device to complete all welding tasks, and the welding area is also reduced by 75. %, significantly reduces the cost of welding production. Coupled with the reduction of production operations personnel, from 4 individuals to 1 person can also reduce labor costs for the company. Considering the problem from the perspective of the entire fixed cost and variable cost, the investment recovery period for laser gas welding equipment is less than 2 years. Without considering the smaller production area occupied by laser gas shielded welding equipment, the comparison between gas shielded welding with double welding nozzles and laser gas shielded welding with dual welding nozzles is shown in Fig. 6.

Figure 5 Diameter of 400mm in diameter with laser gas shielded welding

Fig. 6 Cost comparison between MSG gas shielded welding (a) and laser gas shielded welding (b) per meter weld a: 2 welding equipments Welding speed is 2m/min b: 1 welding equipment Welding speed is 4m/min

At the 2009 welding and cutting technology exhibition, the audience will see the practical application of laser gas protection welding equipment under the command of the control program to complete the actual welding. The control program will further optimize welding parameters, welding procedures and welding equipment on the basis of the current stage. In the future, laser gas shielded welding systems for single-gas protection and dual-gas protection welding tips will be the focus of laser welding equipment investors. Because of higher laser work efficiency and new optical fiber and Shaben laser technology, the purchase cost of laser equipment will be reduced by 20% to 30%.