Application of Laser Surface Hardening Technology in Mould Manufacturing

The use of laser surface treatment technology enables low-grade materials to achieve high-performance surface modification to achieve the best combination of low-cost parts manufacturing and high-performance surface, with considerable economic and social benefits. The laser hardening relies on the thermal conduction of the material matrix to perform self-cooled quenching without the need for cooling media and associated supporting equipment, which is low in cost and no pollution to the environment. The surface hardness of laser-hardened parts is 15%-20% higher than that of conventional quenching, and the depth of hardened layer is usually 0.3-0.5mm. If a laser with higher power is used, it can reach 1mm. The laser-hardened heat affected zone is small, the quenching stress and deformation are small, the subsequent machining allowance is small, and even some workpieces can be used directly after laser treatment.

The energy of the laser beam can be continuously adjusted, and there is no inertia. With the numerical control system, it is possible to perform partial hardening treatment on parts with complex shapes and parts that are difficult to handle in other conventional methods, and it is also possible to perform different laser hardening treatments on different parts of the parts. Because of the above characteristics of the laser surface treatment, it is particularly suitable for the surface of some parts and local parts that are difficult to be realized by conventional hardening treatments (such as carburizing and carbonitriding quenching, nitriding and high-frequency induction heating quenching, etc.) Enhanced treatment, so it has unique advantages in the mold manufacturing: can replace the high-grade mold steel with low-grade mold steel or cast iron; replace the imported mold steel with domestic mold steel; can enhance the mold repair (remanufacturing engineering), reduce mold manufacturing cost. The application of laser surface hardening technology in mold manufacturing can integrate design, material selection, mold making, inspection, repair and other technologies, greatly shorten the design and manufacturing cycle, reduce production costs, change mold manufacturing methods, and finally integrate and upgrade the entire mold industry. Level. These advantages are unmatched by existing traditional technologies, whether they are technical, economic or service-oriented.

For example, the SC6350 micro-vehicle longitudinal beam front-end thick plate drawing die has been made of Cr12MoV material in the past, and is composed of 12 insert blocks. Since the quenched deformation during the manufacture of the insert block is large, secondary processing is required because of the insert block. The influence of “joints” has made the molds expensive to process and have a long cycle, and parts are prone to “pulling and burning” and have not been solved. The surface of the mold was laser-quenched, and the 12 blocks of the original material such as Cr12MoV were changed to ductile cast iron QT600-2 for integral casting. The mold surface was laser-strengthened to a hardness of 58-62HRC, and the mold was not deformed after quenching. Simply polish the surface and put it into use. Compared with the original manufacturing process, the use of laser processing mold, the material saving of 40% to 60%, processing time and tool costs reduced by 30%, a substantial increase in service life. In particular, it is worth noting that the technical problems of drawing a part from a thick plate to make the parts “pull and burn” are not yet a good solution at the international level. The use of a laser surface strengthening process effectively solves this technical problem and improves the The surface quality and dimensional accuracy of the stamped parts, which meets the requirements for the use of thick sheet drawing dies, make the choice of materials for mold design more extensive.

For another example, the mini-car covered stampings originally used gray cast iron HT300, hardness only 28 ~ 32HRC. When the die is used, only a few dozen or even a few pieces of the workpiece need to be punched to repair the die, which will seriously affect the processing schedule and increase the labor intensity. After the quench hardening treatment of the mold surface by the laser, the hardness can reach 58HRC or more, which greatly improves the service life of the mold. The experiment shows that after 5000 consecutive punching times, it is possible to continue stamping without “glossy”.