With the continuous expansion of the automotive industry, many new technologies related to automobile manufacturing have entered the field of vision. Some new terms such as the application of laser tailor welded brackets to the bodywork, aluminum bodywork and continuous welding of bodywork have gradually become familiar to everyone . Tailor-made welding plate is the earliest by the domestic auto industry to introduce new technology, which does not reduce the body under the premise of a substantial reduction in body weight and reduce fuel consumption. However, the stamping process of 200mw laser pointer blanking the process of deep drawing of the cracking process has plagued the OEMs.

Laser tailor welded plate technology is the use of laser energy to different materials, thickness, plating plate together and welding together to form a piece of the overall plate technology. The emergence of Tailor welded plate technology solves the problem of different process performance requirements of extra wide plate and different parts and plays an important role in reducing body weight, reducing vehicle cost, and saving energy and protecting environment.

Currently mainly used in the side walls, doors, stringers, floor and other body parts. The domestic OEM laser welding machine made by the basic sheet metal manufacturers to provide sheet metal, laser welding tailor-welded tailor-made plant sent to the stamping process. Japanese automobile companies more than 90% of the door panels using 500mw laser pointer tailor welded plate.

In the use of laser tailor-made board when the door, often in the debugging phase of the parts without cracking, but after a period of mass production often appear tailor welded parts cracking. This cracking generally occurs in the area of 2 to 3 mm near the sheet for welding, and no problems are found in the investigation of the material and the welding process. However, the actual processing of cracking occurs from time to time, compared to the performance data of the cracking material and good material there is no big difference between the larger place. Parts in the stamping process in the emergence of defects, the general search direction for the mold, materials (sheet and welding), automation, equipment and other four aspects.

Forming theory analysis. Mold stability is very high, drawing mold in the stable production of a good period of adjustment, the parts appear bulk abnormalities less. However, due to special tailor-welded plate caused by the physical and chemical processing instability.

We all know that drawing die is different from the main features of the forming die is forming a 50mw laser pointer binder, the first blank holder and die compacted material, punch and die for material forming. Ordinary materials in the forming process with the closing height decreases, the drawing force gradually increased, the material will also increase the internal stress, strain will be from the elastic deformation into plastic deformation to uniform plastic deformation Individual or even appear necking (dark crack ) And cracking.

Material Theory Analysis. Cracking caused by the main reason is that the welding wire parts of the material and process conditions. We know the material is divided into brittle materials and plastic materials. The brittle material is the material with small elongation at break, such as brick in building materials, glass, cast iron in metal materials, etc., and the 30mw laser pointer welding seam in the tailor-welded plate belongs to the brittle material. Plastic materials for the elongation at break and the reduction of cross-sectional area are larger materials, generally low-carbon steel are plastic materials, body parts are cold-pressed plastic materials.

In the drawing process of plastic deformation plastic deformation has a certain elongation, brittle material is basically no elongation. The physical properties of the material near the weld are the brittle material and the plastic material, because the material of the welded part of the wire is basically no elongation due to the brittle material, and its existence interferes with the extension of the thick material to a certain extent. So that the material in the outer sheet region of the weld during the deep drawing process is stressed and stretched, there will be obvious extension blocking on the weld side, which can not obtain the extension replenishment that should have come from the weld side material, resulting in cracking, this is the reason that the welding line department is easy to crack in the debugging stage of the vehicle.

The laser cutting machine uses different auxiliary gases to cut different materials. The thickness of cutting material is different. The pressure of auxiliary gas and the required flow rate are different. The pressure of auxiliary gas has a direct effect on the result of laser cutting. Laser working gases are used to produce laser pointer; protective gases are used to protect optical devices and drive sluice. Laser gas by helium, nitrogen and carbon dioxide are mixed according to a certain proportion, the proportion of reservation in the factory, to ensure the best performance; the auxiliary gas can timely slag blow away, also play a role and cooling the workpiece cleaning the lens, using different auxiliary gas, can change the cutting speed and the cutting surface quality the special metal cutting, is of great significance to assist gas type oxygen, air, nitrogen and argon. Air nitrogen is used as a protective gas for cutting to prevent oxide film from occurring, and argon is used for titanium metal cutting.

Compressed air. The air is suitable for cutting aluminum, non-metal and galvanized steel, to a certain extent it can reduce the oxide film and save the cost. In general the cutting plate is relatively thick, the cutting face requirements is not very high, in some metal cabinet cabinet products industry application.

Nitrogen. Nitrogen is an inert gas which prevents the oxidation of the cutting end of the product and prevents the combustion (when the material is thicker). Nitrogen can be selected for products that require high cutting end face and do not need to be treated. For example, some special parts such as decoration industry, aeronautics and Astronautics, etc.

Oxygen. Oxygen mainly plays the role of combustion, which can increase the speed of cutting and thicker the cutting thickness. Oxygen is suitable for thick plate cutting, high-speed cutting and very thin plate cutting. For example, some larger carbon steel plates and some thicker carbon steel structural parts can use oxygen.

Increasing the pressure of the gas can increase the cutting speed, but after reaching a maximum, increasing the pressure of the gas will cause the cutting speed to decrease. Under high auxiliary gas pressure, the reduction of cutting speed can not only be attributed to the enhancement of the airflow speed and the cooling effect of the hanging zone, but also to the interference of intermittent shock waves to the cooling zone of the burning laser zone.

There is an uneven pressure and temperature in the air flow, which will cause the change of the density of the airflow field. Such a density gradient leads to a change in the refractive index of the field, so as to draw the focus of the beam energy and cause the refocusing or the divergence of the beam. This interference will affect the melting efficiency, may sometimes change the mode structure, resulting in the decline in the quality of cutting, if the beam divergence is too much. Make the spot too large, and even cause serious consequences that can not be effectively cut.

Despite the faster cutting speed and higher productivity of high-power solid-state lasers for metal 2D cutting, most metal manufacturers are excited, but it is still costly to control and manipulate the power of such lasers. Machine tool manufacturers continue to introduce higher power lasers. But in order to give full play to this advantage, they need to design to meet the stringent requirements of the red laser pointer system. The machine itself must be able to control the changes that occur with this high power cutting to ensure that the machining is not only fast and reliable, so that the manufacturer can give full play to the performance of the laser.

Therefore, the scientists by measuring the material to reflect the change in light to achieve the purpose of indirect observation - first with high-power laser pulse irradiation material, causing the material state changes, lag after a period of time after the launch of a weak laser pulse and the reflected light measurement. The energy of the first most powerful laser will quickly heat the material, while the reflection of the photon changes. And when the material begins to cool, the reflection begins to move closer to the normal value. Therefore, scientists can according to the reflected light to infer the dynamic state of the material changes. When the weak laser irradiation material, the material surface of some of the electrons will be ejected, scientists use electron microscopy to collect these electrons and the formation of images. In the case of weak laser irradiation, these electrons will gradually accumulate and eventually form a photo that reflects the electron distribution inside the material.

With the development of die-cutting technology and laser technology, the combination of the two, the use of laser to replace the traditional die-cutting die has a clear advantage. Laser die-cutting machine is a fully automatic laser cutting, no vibration deviation, high precision and stability. No need to make knife mold, by the computer directly control the laser cutting, and not limited by the complexity of the graphics, you can cut the traditional die can not complete the cutting needs. As the laser die-cutting technology is directly controlled by the computer, without the need to replace the knife template, can achieve different layout between the fast switching between the parts, saving the traditional die-cutting tool change and adjust the time, especially for short version, Cut processing. Laser die-cutting machine with non-contact characteristics, change live fast, short production cycle, high production efficiency.

In the use of laser pulse spot welding, the solder joints are prone to crack, resulting in decreased welding strength, stability is also greatly reduced. However, the traditional blue laser pointer beam is poor in mass, bulky, high maintenance cost and low photoelectric conversion efficiency, which restricts its consumption on the consumer electronics products to a certain extent. The traditional laser beam, YAG and other continuous laser welding aluminum alloy can avoid the crack. Applications. In particular, the structural parts of consumer electronics products have the characteristics of thin thickness, small volume and high precision. The traditional continuous laser welding is easy to produce large deformation, welding and burning.

In recent years, high-power high-beam quality of the laser in the line of materials processing industry applications have been rapid development, a wide range of lasers: different structures are divided into gas laser, solid laser, fiber laser, semiconductor 100mw laser pointer materials to support the mainstream of the processing industry; From far infrared to deep ultraviolet can cover (200nm ~ 20um), different industries will also use a different power range, different beam quality, different laser output and so on. In order to reduce the thermal effect in the field of processing thin film non-metallic materials, semiconductor wafer cutting, plexiglass cutting, drilling, marking and other fields, it is hoped that the small aperture effect and the high peak power, the role and position of the ultraviolet laser is so good and not alternative.