Principle and technology of laser cutting glass
The micron-level beam obtained by the ultrafine laser focusing head has a peak power density.When the beam ACTS on the glass material, the light intensity at the center of the beam is lower than that at the edge, so that the refractive index at the center of the material changes more than that at the edge, the propagation speed at the center of the beam is slower than that at the edge, and the beam appears nonlinear optical Kerr effect to generate self-focusing, which continues to improve the power density.Until a certain energy threshold is reached, the material produces a low-density plasma that reduces the material's central refractive index and defocuses the beam.In the actual cutting glass, the focusing system and focal length can be optimized to realize the repetitive focusing/defocusing process and form a stable perforation.
Filament cutting is a feasible process. The laser industry has mature solutions. Meanwhile, it has been widely used in the display industry.When the ultra-fast laser beam propagates through the glass material, there is Kerr self-focusing and plasma defocusing at the same time. In the dynamic balance between the two, the beam can realize long distance propagation, and form micron-scale holes in the material, which can extend a few millimeters in the glass.The linear motor controls the motion of the glass workpiece relative to the laser beam to generate a number of evenly spaced filaments, and the microcracks along the diameter direction are generated by optimizing the spacing of filaments.By applying special action to the glass with microcrack, the stress at the microcrack can be increased and the glass can be broken along the microcrack to achieve the purpose of cutting off.
For glass processing, laser spot can be shaped into "long filamentous shape" by optical diffraction device. According to different glass thickness, cutting head with corresponding focal depth length is required.The laser focus position is adjusted by the z-axis of the equipment to confirm the focus of the laser cut glass sample.The software generates the cutting diagram file, and the glass sample moves along the path of the diagram file by linear motor for laser cutting, so as to obtain the bulk glass cutting sample under the corresponding graph.Then, the full-page glass cutting products are cleaned, strengthened, silk-screen and other glass post-processing technologies, and finally, a certain shape of small pieces of glass are obtained by adopting a specific split method.In addition, after product debugging, the parameters can be directly saved to the software parameter library, and then can be directly called according to the type and thickness of the corresponding glass sample, and the product can be cut.
Glass is a kind of important industrial material, used in many industries, such as automotive, construction, medical, display, electronic products, such as small small optical filter, a laptop to a few microns flat-panel glass substrate, big the auto industry or construction and large scale big size of the glass used in the manufacturing sector.
The remarkable characteristic of glass is its hardness and brittleness, which brings great difficulty to processing.The traditional glass cutting method USES carbide or diamond cutter, which is widely used in many applications. The cutting process is divided into two steps.Firstly, a crack is produced on the surface of glass by using diamond tool tip or carbide grinding wheel.After that, the next step is to mechanically separate the glass along the crack line.
There are some defects in using this method for marking and cutting.The removal of the material will lead to the formation of debris, fragments and micro-cracks, which will reduce the strength of the cutting edge and thus require another cleaning process.The deep cracks resulting from this process are usually not perpendicular to the surface of the glass because the dividing lines generated by the mechanical forces are generally non-perpendicular.Moreover, the production loss caused by mechanical force applied to thin glass is also a negative factor.