Laser welding using high energy density laser as the heat source in the material connection, so that the separation of material absorption of laser energy after the rapid melting and even vaporization and the formation of pool together, in the subsequent cooling process together to solidify together. Figure 1 is the tube blue laser pointer welding process, the red region is roughly the laser propagation path, high brightness of the region after the metal heat generated by vaporization of the metal vapor. See here, Tell me what can not help but ask, where the laser, how I did not see. This is because there are two common high-power lasers for laser welding: CO2 laser and solid / fiber laser, the former wavelength is 10.6μm, or the wavelength is 1.06 / 1.07μm, all in the infrared band, so the naked eye is invisible of.

Laser welding mainly has the heating range centralized and precise controllable, the welding distortion is small, the welding speed is quick and so on the characteristic. In order to help you Tell me what the brain fill, we take the laser welding and common arc welding comparison. The 30mw laser pointer spot diameter can be controlled precisely. Usually, the diameter of the spot on the surface of the material is in the range of 0.2-0.6mm, and the energy near the center of the spot is exponentially decaying from the center to the edge. Weld seam width can be controlled below 2mm. The arc width of the arc can not be precisely controlled and far greater than the diameter of the laser beam, arc welding seam width is much larger than the laser welding, usually more than 6mm. As the laser welding of energy is very concentrated, so that the melting of the material less, the total heat required is small, so welding deformation is small, fast welding speed. You can write to the image of the analogy of laser welding and arc welding. Laser welding is like writing with a 0.3mm signature pen, the word must be so fine, write very quickly, finished the basic paper did not change, where it can be said to be where the fight; arc welding with a lot of brush writing, Not only thick, with the strength of the word is not the same as the thickness of the word is different, and write slowly, finished paper too much because of immersion deformation, can only say where to fight where. From the above description of laser welding we can see that the 20000mw laser pointer welding looks like a tall welding method, then use laser welding for body welding, and the current widespread use of resistance spot welding compared to who is more high strength ?

The laser welded joint is a slender continuous line, as shown in Figure 2, and the resistance spot welding joint is a row of slightly concave discrete dots, as shown in Figure 3. If the laser welding joints like a zipper, like the clothes of the two lapel together, then the resistance spot welding joints like buckle buttons. Then the laser welding and resistance spot welding in the end who is more high strength? Laser welding of the weld metal is obtained through rapid solidification, and its grains (the basic composition of metal elements, can be understood as metal cells) is more small, is conducive to improving the strength of the weld metal, so the weld metal weld strength Than the resistance spot weld metal a little higher strength. At the same time do not forget, the resistance spot welding joint is a string of discrete points, just take the welding part and 10000mw laser pointer welding than have been, but those who did not weld on the place but also "drag", that average Resistance spot welding is more than laser welding. Therefore, for the same length of welded joints, the intensity of laser welding is higher than resistance spot welding.

After the optimization of the welding parameters, the strength of the resistance spot welding joint is higher than that of the metal base metal, but the weakest part of the whole welded body is the welding heat affected zone on the base metal. In other words, the metal base metal (especially welding heat affected zone) is the weakest link, so once the body by a strong external force, the vast majority of cases are metal base metal damage, rather than welding joints. It is precisely because of the existence of the metal matrix of this short board, making the 3000mw laser pointer welding of the body and the resistance of the external body of the spot welding strength is almost no difference. Laser welding joint strength is high, but since the strength of the metal base material drag, there is no useless!

See here we certainly have to ask, since the laser welding can not improve the overall strength of the body, then why do some manufacturers have to spend a lot of money to introduce laser welding it? That's because laser welding has other advantages. First of all, the welding speed of laser welding is much faster than resistance spot welding. For example, 6s of the time, laser welding can weld 1m long weld, and resistance spot welding can only weld 1 point. Second, the 100mw laser pointer welding joints are continuous, naturally there will not be like the resistance spot welding joints as the problem of leakage, so you can save the process of coating the sealant.

In summary, the price and configuration similar circumstances, choose the laser welding of the body is no doubt. But there is no need to pay extra for laser welding, and the 50mw laser pointer welding as an important indicator of a car or even the first indicator is even more unnecessary.