Application of laser welding in the automotive industry

Laser welding belongs to fusion welding, which uses laser beam as the energy source and impacts on the weld ment joint. Laser welding is non-contact welding. No pressure is required during the operation, but inert gas is required to prevent oxidation of the molten pool, and filler metal is occasionally used. Laser welding can carry out precise energy control, so it can realize the welding of precision micro devices, and it can be applied to many metals, especially to solve the welding of some difficult-to-weld metals and dissimilar metals.

Due to the fast speed of laser welding and the ease of remote control and automatic production, it is widely used in industries with a high degree of automation such as automobile manufacturing and new energy battery production. With the development of the new energy vehicle market in recent years, it has also driven market demand for laser welding equipment. The data shows that the market size of my country’s laser welding equipment has risen from 1.56 billion yuan to 10.13 billion yuan from 2013 to 2019. The main application processes in the automotive industry mainly include laser tailor welding of unequal thick plates, laser assembly and welding of body assemblies and sub-assemblies, and laser welding of auto parts. In the field of power batteries, laser welding is the best process for explosion-proof valve sealing welding, tab welding, soft connection welding, safety helmet spot welding, battery case sealing welding, module and PACK welding. The application of laser welding technology on the car body can reduce the weight of the car body to achieve the purpose of saving fuel; the firmness and lightness of the laser welding technology can improve the degree of integration of the car body; the high precision and high efficiency of the laser welding technology, It can ensure its safety and stability while improving efficiency in production. When the car is running, due to the bumps and squeezes of the ground, each component and structure is under different degrees of impact, which requires the overall structure of the car to be very precise and strong. Using the current laser welding technology, its dynamic and static stiffness can be increased by more than 50% compared with other welding processes, which reduces the noise and vibration during driving, improves the comfort of the ride, and also improves the safety performance of the car.

1. Body welding

Laser welding in the automotive industry is widely used in the assembly and joining of body stamping parts. The main applications include laser welding of the roof cover, laser welding of the trunk lid and laser welding of the frame; another important application of laser welding of the body is the laser welding of the body structure (including the door, the side frame of the body and the pillar, etc.) . The reason for using laser welding is that it can improve the strength of the body and solve the problem that some parts are difficult to implement conventional resistance spot welding. Laser self-fusion welding, that is, two or more parts to be welded are melted to form a whole without adding welding wire and other auxiliary materials, and multiple parts are self-fused into a whole after welding. Laser self-fusion welding is mainly divided into two parts in automobile body manufacturing, body assembly welding and tailor welding. Body assembly welding: body assembly welding mainly includes roof and side pillars, tailgate, body bracket and door welding. With the demand for product replacement, laser welding is more and more widely used in the automotive field. Assembly welding has been Accepted by most manufacturers, only Volvo still insists on using laser self-fusion welding; Ford SUV and sedan have side panels that use laser self-fusion welding, and many models of Volkswagen are also using laser self-fusion welding.

2. Unequal thickness laser welded blank

The use of laser tailor-welded blanks with different thicknesses in body manufacturing can reduce the weight of the car body, reduce the number of parts, improve safety and reliability, and reduce production costs; tailor-welded blanks are welded from steels with different strengths, thicknesses and coatings. It is widely used due to its high speed, high precision and small weld seam. Most of the current tailor-welded blanks for automobiles are welded by laser. Compared with the pure steel plate of the old car body, Tailored Welded Blank has three advantages. The body is light in weight, and the plate is thinner by welding to reduce the weight of the car body; the overall strength is high. After the car body is composed of welded plates, the strength even exceeds The main body of the base material increases the safety of the car body; the cost is relatively low, and the welding strength and precision are higher than traditional materials, reducing the use of parts and ensuring performance. The application of laser tailor welded blanks in body manufacturing can reduce the number of parts, molds and welding fixtures, reduce the weight and cost of the body, and improve the market competitiveness of products. The main application of Tailored Welded Blanks in automobile body is mainly used in cover parts, and some are used in structural parts.

The welds of tailor-welded blanks in automobiles are mainly divided into the following three types: single linear welds; multiple linear welds; non-linear welds. Among them, the single straight line weld type is the most widely used, and the production process is relatively simple. The non-linear weld is the most complicated, and the weld is generally designed according to the shape of the stamped part to improve the strength and stamping performance of the product. Since the tailor-welded blanks must be stamped and formed later, the requirements for the forming quality and defect control of the tailor-welded blanks are particularly strict. It mainly includes appearance (scars, cracks, inclusions, holes and scratches, etc.), weld shape (weld width, weld protrusion, effective depth of weld, back gap and weld misalignment, etc.) and mechanical properties, etc. (Tension, cupping, hardness and bending tests on welds). For example, it is required to break in the non-weld area in the tensile property test, and the cracked area in the cupping test cannot be in the weld or the cupping value is greater than the specified value.

3. Welding of gears and transmission parts

In addition, various parts of the gearbox can be welded on this equipment, especially the differential case and drive shaft in the car gearbox, which are often joined and welded after the production of individual parts made.

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