In the process of automobile manufacturing, laser technology is mainly used for bodywork assembly of unequal thickness plates, bodywork welding and auto parts welding. Laser welding applied to automobiles can reduce the weight of the body and achieve the purpose of fuel saving; improve the assembly accuracy of the body, so that the stiffness of the body is improved, thus improving the safety of the body; reduce the stamping and assembly costs in the manufacturing process of the car body, reduce the number of body parts and improve the integration of the body.
Laser self-fusion welding
Laser self-fusing welding, in which two or more parts of a weld melt and eventually cool to form a single unit, does not require the addition of auxiliary fluxes or fillers and uses the workpiece's own material to fuse together.
Laser self-fusion welding in auto body manufacturing is divided into two main parts: body assembly welding and assembly welding.
Body assembly welding
But with the development of technology, laser welding is more and more widely used in this part of the welding, only Volvo is still insisting on using laser self-fusion welding; for the side surrounds, Ford SUV and sedan have a laser self-fusion welding, and many models of Volkswagen are also using it.
Automotive laser welding
Tailor-welded blank (TWB) is made of different strength, different thickness or different coating of steel welding, due to the advantages of laser welding efficiency, good weld seam forming, etc., the current automotive welding plate are made of laser welding.
Compared with ordinary steel plates, the advantages of welded panels are mainly in the following three aspects: 1:
1. reducing body weight - applying the welding method to optimize the thickness of the sheet to reduce weight;
2. improve body service and crash performance - mainly including safety, driving performance, fatigue and corrosion resistance and body rigidity;
3. cost reduction - mainly in terms of material reduction, process reduction and tooling reduction.
The use of laser welding plate in body manufacturing can reduce the number of parts, molds and welding tooling, reduce the weight and cost of the body, and improve the competitiveness of the product market. Figure 3 shows the main applications of the welding plate in the automotive body-in-white, mainly in the coverings, but also some use in the structural parts.
Automotive manufacturing laser welding technology applications
Welding seam form
Automotive welding plate according to the type of welding seam classification can be divided into three categories: 1:
1. single linear weld seam;
2. plural linear welds;
3. non-linear welding seam.
Among them, the single linear weld type is the most used, and the production process is relatively simple. Non-linear welds are the most complex, and are generally designed according to the shape of the stamped part after forming, so as to improve the strength and stamping performance of the product.
Since the subsequent stamping and forming of automotive welded plates is required, the quality of the welded plates and the control of defects are particularly strict. The main requirements include appearance (scars, cracks, inclusions, holes and scratches, etc.), weld formation (weld width, tumor protrusion, effective depth of weld, back break and weld misalignment, etc.) and mechanical properties (tensile, cupping, hardness and bending tests on the weld). For example, it is required that the tensile properties test fracture in the non-weld area, and that the cracked area in the cupping test cannot be in the weld or have a cupping value greater than the specified value.
