Application of laser cutting technology in glass industry

Glass is an important material, which is widely used in many industries in the national economy such as the automobile industry, construction industry, medical treatment, display and electronic products, and used for large glass panels in large manufacturing files such as the automobile industry or construction industry. In the industrial field, filters as small as a few microns, glass substrates for laptop flat panel displays.

There are many types of glass. The most common is soda lime glass, also known as alkaline glass, which is mainly used in the automotive industry, construction industry and household appliances. The thickness is generally 1.6-10 mm, and the glass of 1 mm or less is called borosilicate glass or non-alkaline glass, which is mainly used in the field of flat panel displays and electronic products.

Glass is hard and brittle, which brings great difficulties to processing. Traditional glass cutting uses cemented carbide or diamond tools. The cutting process is generally as follows: first use a diamond tip or a cemented carbide grinding wheel or a high-hardness metal grinding wheel to make a scratch on the glass surface, and then mechanically split the glass along the score line.

When scribing a line on the glass with a grinding wheel or mechanical wheel, tangential tension is generated along the cutting direction, causing the glass to crack along the scratch. Smooth, with tiny cracks and residual fragments on the material. For many applications, small cracks caused by debris and local stress can cause equipment failure, so the edges must be polished. In addition, auxiliary agents are needed to assist in the processing of the cutting mechanical wheel. The auxiliary materials may also stick to the edge of the finished product and require water cleaning or ultrasonic cleaning. Subsequent processing operations and low output (such as uncertain whether there are cracks) will increase the cost of making glass products.

At present, the quality requirements of glass products are getting higher and higher, and more precise and detailed processing effects must be achieved.

Because the traditional process is difficult to meet the requirements of micro-cracks and edge quality, there is an urgent need for technological innovation in glass cutting. Laser cutting technology has matured and has been successfully applied to the cutting of metal sheets, pipes, organic sheets and other materials, greatly changing and upgrading traditional manufacturing techniques.

Glass is an inorganic material with very low thermal conductivity. In theory, laser processing should have better results, which has also led to the development of laser cutting glass technology.

In principle, there are two methods for laser cutting glass: one is the melting (evaporation) cutting method, and the other is the crack control method.

(1) Melt cutting method: use glass with good plasticity and ductility at a softening temperature, and irradiate the softened glass surface with a focused CO2 laser or ultraviolet laser. The high energy density of the laser causes the glass to melt, and then the molten glass is blown away by airflow. In this way, a groove is formed, and the melting and cutting of the glass is realized.

(2) Crack control method is a commonly used laser cutting method. The first step is to heat the glass surface with a laser. The high energy causes the temperature to rise sharply, and the glass surface produces a larger compressive stress. But compressive stress will not cause the glass to break. In the second step, the area is rapidly cooled, usually using cooling gas or cooling liquid. The sharp temperature drop will cause a larger temperature gradient and larger tensile stress on the glass surface. This kind of tensile stress will cause the glass surface to crack along the predetermined score line, thereby realizing the cutting of the glass.

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