In recent years, the advantages of laser welding machines in the field of automobile manufacturing have become increasingly obvious, and they have also received more and more attention. In the laser welding process, welding does not need to be carried out in a vacuum, and welding deformation can be avoided, and the welding seam has a comprehensive mechanical performance equivalent to or better than that of the base material, ensuring that the gear can transmit a large torque. Therefore, laser welding of automobile gears has become a major trend in today's manufacturing development.
Automobile gear welding process
The welding seam depth of gear welding with high energy density laser beam is relatively large, and the laser welding is generally deep penetration welding; laser welding has no contact processing, fast speed, small weld heat affected zone, small deformation of welding gear, and gear processing volume after welding Less, or even no processing; high welding strength, welds generally have mechanical properties equivalent to or better than those of the base material, so that the gear can transmit larger torque; high welding accuracy, no filler wire is needed during the welding process; and Compared with other beam welding methods, the laser welding of gears does not require a vacuum chamber, and the welding is performed in a natural environment, which is intuitive.
The main process of laser welding gear includes the following aspects
1. Welding process parameters. Laser welding generally uses a fundamental mode or low-level laser beam. The main process parameters for gear welding are laser power, welding speed and defocusing. For a certain spot diameter and a certain defocus amount, the welding penetration increases with the increase of beam power, and decreases with the increase of welding speed; the separation content has a great influence on welding penetration, penetration width and weld shape, and can even be determined The form of laser welding.
2. The weldment is cleaned and pressed before welding. Laser welding has certain requirements for the degree of cleaning of the weldment. The cleanliness of the cleaning directly affects the quality of the weld. If there are oil stains, rust and other impurities at the weld, it is easy to produce defects such as pores. In production, mechanized cleaning methods should be adopted, and cleaning should be carried out by dipping, spraying or a combination of the two. The cleaned gear weldments should be press-fitted before welding (press the weldments to be welded together). When press-fitting, pay attention to the tolerance matching and press-fitting accuracy of the press-fitting surface machining.
3. Welding protection. In order to ensure a deeper weld depth and prevent the weld from being oxidized, it is necessary to use shielding gas to blow away the plasma cloud on the upper part of the weld during laser welding, and to isolate the influence of excessive oxygen in the atmosphere. The laser beam is normally incident to the welding molten ground, and the welding process can be carried out continuously and evenly; at the same time, the shielding gas also has the function of protecting the focusing lens from boiling gas and liquid back spray pollution.
Laser welding of automobile gears is a development trend. At present, the world's major automobile manufacturers are competing to use laser welding gears to replace traditional welding methods such as resistance welding, induction welding, and electron beam welding. Laser welding of gears does not need to be carried out in a vacuum, which can avoid welding deformation. After welding, the gears do not need to be processed again, and the welds have comprehensive mechanical properties equivalent to or better than those of the base material, ensuring that the gears can transmit large torque.
In the design and manufacture of automobile transmission gears, in order to reduce the difficulty of cold and hot processing of gears and improve production efficiency, the gears are often divided into two independent parts for processing separately, and then the two parts are combined to form a whole. It constitutes a compound gear, also called a gear assembly, such as a gear assembly composed of a gear and a cone (engaging tooth).
There are two main ways to connect compound gears: spline connection and beam welding connection. The spline connection is realized through internal and external splines, the empty slot is large, the gear axial size is large, and the production efficiency is low: beam welding connection is mainly electron beam welding and laser welding, which is connected in a smooth cylindrical shape. Instead of spline connection, the empty slot is reduced, the volume of the gear is reduced, the weight of the vehicle is reduced, and the production efficiency is significantly improved.
The use of laser welding technology to connect the gear assembly can improve the product accuracy of the transmission gear, simplify the product structure and manufacturing process, and conveniently meet the needs of continuous adjustment of the component structure and sample manufacturing in product development and trial production. It is helpful for designers to rationally lay out the product structure and continuously improve the level of product development and manufacturing: At the same time, because of the compact structure of laser-welded gears, the accuracy and reliability are improved, which can reduce the failure rate of vehicles, improve vehicle handling flexibility, and improve product reputation . The technology has high production efficiency and good application effects.
