A method and system for nanosecond pulsed laser lift-off of metal plate coatings

Abstract

The invention discloses a method and system for stripping a coating of a metal plate with a nanosecond pulse laser. The above method is specifically as follows: the laser beam emitted by a nanosecond pulse laser is emitted to the surface of the coating to be stripped through a two-dimensional scanning vibrating mirror , the coating to be stripped will produce an explosive melting reaction after being ablated by nanosecond pulsed laser, and will be separated from the metal plate under the drive of the high-speed airflow generated on the surface of the coating; the above system includes nanosecond lasers, energy transmission optical fibers, collimation The laser beam emitted by the nanosecond laser passes through the energy transmission fiber, the collimation head and the two-dimensional scanning vibrating mirror sequentially and is emitted to the surface of the metal plate coating to be stripped. Compared with the existing stripping methods, the peeling method provided by the present invention has the advantages of being more environmentally friendly, process controllable, higher in precision and efficiency, and lower in cost.

Description

technical field [0001] The present invention relates to the application field of laser technology, more specifically, to a method and system for performing nanosecond pulse laser stripping on a metal plate coating. Background technique [0002] In order to reduce the weight of the automobile body and improve the rigidity of the body structure in terms of bending and torsion, high-strength steel processed by thermoforming technology is widely used in the automobile industry; however, the temperature of the thermoforming process is as high as 900°C, and the high temperature will Severe corrosive effects occur. In order to prevent this effect, the existing technology mostly adopts the Al-Si coating process on the surface of high-strength steel plates. Good antiseptic effect. [0003] Although the Al-Si coating has a good protective effect on the base material of the high-strength steel plate, it will have an adverse effect on the welding of the base material. If the coating ...

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Problems solved by technology

[0003] Although the Al-Si coating has a good protective effect on the base material of the high-strength steel plate, it will have a bad effect on the welding of the base material

If the coating is not removed before welding, the coating will melt and enter the molten pool at high temperature, and be distributed in different positions in the molten pool; moreover, Al and Si elements will segregate locally during the solidification process , showing a light gray microstructure in the optical metallography, which belongs to the brittle phase, which makes the weld prone to brittle fracture here, resulting in the adverse consequences of a significant decline in the tensile properties of the plate after welding, thus affecting the overall performance of the component Therefore, it is particularly important to remove the coating at the double-sided welding position before welding the Al-Si coated high-strength steel plate.

[0004] Al-Si coatings are usually difficult to remove by mechanical methods, such as using particle impact to force the coating to crack, and it is easy to cause mechanical damage to the substrate; using a strong inorganic acid to remove the coating is prone to over-corrosion, reducing the cross-section of the substrate , resulting in the adverse consequences of reducing the mechanical properties of the parts, and the NH in the solution 4 + 、Mo 7 o 24 6- and Cr 2 o 7 2- Improper treatment of such harmful ions will seriously pollute the environment; use a complex acid mixture of organic sulfonic acid, inorganic acid and other oxidizing and reducing reagents to remove the aluminide coating, and then use heated acetic acid to remove the corrosion products, but this method is too complicated , and the efficiency is low; the current method of using laser to remove the coating requires thousands of watts of laser power, and severe thermal effects will occur during the removal of the coating, which will cause unacceptable serious damage to the properties of the substrate that requires thermoforming impact, and the cost is very high

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