The automobile windshield adopts curved glass, firstly from the aerodynamic point of view. Because the normal speed of modern cars mostly exceeds 100 km, the oncoming airflow passing through curved glass can reduce eddy current and turbulence, thus reducing air resistance. Coupled with the smooth transition between the edge of the window frame and the surface of the car body, the glass and the car body are integrated, which not only visually feels the overall harmony and beauty, but also reduces the wind resistance coefficient of the whole car. In addition, the curved glass has high strength, and thinner glass can be used, which is of certain significance to the lightweight of automobiles.
The curved windshield of modern automobile should have high flatness at the corner, and there should be no optical distortion, and the objects outside the driver's seat should not be deformed or dazzled at any angle. In the past, automobile glass was usually decorated or protected with neat strips along the edge of the glass, but now the glass on the automobile is ceramic glazed and called "black frame". Many car windshields are also coated. By adopting reflective coating technology or improving the composition of glass, only the visible light of the sun can enter the carriage, blocking ultraviolet rays and infrared rays, greatly reducing the heat suffering of passengers. This kind of modern automobile glass called "green glass" has been widely used.
The safety performance of automobile windshield is very important. Not to mention that if the safety performance is low, it is dangerous to the health of the occupants, even to the car itself. If the windshield cracks or has obvious occlusion points, it will seriously damage the appearance and image of the whole vehicle, just like facial disfigurement. Therefore, the safety requirements of automobile windshield are very high. General automobile glass is made of silica glass, in which the content of silica is above 70%, and the rest is made of sodium oxide, calcium oxide, magnesium and so on. Through the floating process. In the manufacturing process, the material is melted when heated to 1500℃, and the solution is poured into a suspension tank (liquid tin) after passing through a refining zone of about 1300℃, and cooled to about 600℃. At this stage, a parallel double-sided planar body with particularly good quality is formed (the solution plane is above and the liquid tin plane is below), and then glass is formed after passing through a cooling zone. Then, the glass is further processed into tempered glass (TSG) or laminated glass (LSG).
The appearance of finished automobile glass should be free of obvious bubbles and scratches. In order to ensure the quality of automobile glass, automobile glass is divided into four categories: Class A and Class B laminated glass, regional tempered glass and tempered glass, among which Class A laminated glass has the highest safety performance. According to the national standards, the front windshield must use Class A laminated glass, Class B laminated glass or regional tempered glass, and their codes in the certification mark are LA, LB and Z respectively. The certification mark is permanently marked on the lower corner of the glass through screen printing, sand blasting and other processes. The code name of tempered glass is T, which can only be used outside the front windshield, while the glass marked with LA, LB and Z can be used in all glass positions of automobiles.
With the development of automobile glass technology, new windshield technology emerges one after another. For example, it can reduce the influence of sunlight on the carriage and improve comfort. At present, the widely used "green glass" is to adopt reflective coating technology or improve the composition of glass, so that only visible light in the sun can enter the carriage and block ultraviolet and infrared rays. At present, there is a silver-plated glass that can prevent infrared radiation. The infrared reflectivity of multilayer laminated glass is 48% by adding silver-plated film. When sunlight passes through this seemingly ordinary glass, light and heat will be reduced by 23%. In fact, this kind of glass also plays the role of heat insulation and energy saving, which can relatively reduce the energy loss of air conditioning. In addition, the automobile windshield in the cold area in the north is easy to fog and freeze, and a heatable automobile glass can solve this problem. This kind of glass makes tiny, almost invisible heating wires into waves, which are placed on the plastic mucosa in laminated glass and connected to the circuit through resistors. The window heating wire has a certain heating range, and the thermal power can reach 3-5 watts per square centimeter, which plays the role of frost prevention, atomization prevention and icing prevention.