Why can't machine tools be illuminated by fluorescent lamps?

Fluorescent lamps are widely used in offices and homes. Compared with incandescent lamps, fluorescent lamps have many advantages, such as simple structure and low price. It has a high efficiency of converting electric energy into light energy, saving nearly 2/3 of electricity compared with incandescent lamps with the same power, so that the room can be better illuminated; At the same time, the service life of fluorescent lamps is about 2~3 times longer than that of incandescent lamps. Fluorescent lamps have so many advantages, but when you walk into the machine tool workshop of the factory, what you see on the machine tool is not fluorescent lamp lighting, but incandescent lamp lighting. What is the reason? Generally speaking, the power supply used in factories is alternating current with a frequency of 50 Hz. When the fluorescent lamp is connected to the AC circuit, it will produce obvious stroboscopic effect. That is, with the periodic alternation of voltage and current, the luminous flux of fluorescent lamps also alternates periodically, which makes people's eyes feel flashing. When the illuminated object is rotating, it will make people's eyes have an illusion about the recognition of the rotating state. When the rotating frequency of the illuminated object is an integer multiple of the shining frequency of light, the rotating object looks as if it is not rotating, which is electrically called stroboscopic effect. Because of stroboscopic effect, it is easy for operators to have illusions and cause accidents. Therefore, it is not appropriate to use fluorescent lighting on machine tools, but incandescent lighting.

Why do fluorescent lamps have stroboscopic effect and incandescent lamps have no stroboscopic effect? Fluorescent lamps rely on ultraviolet radiation emitted by mercury vapor discharge to excite fluorescent substances on the inner wall of the lamp tube to emit visible light. Tungsten wire electrodes are sealed at both ends of the cathode fluorescent lamp, and thermionic emission materials are coated on the top. In addition, there are ballasts and upconverters. The lamp tube is used in conjunction with up converter, which is mainly used to heat the filament and provide enough voltage to emit electrons between the two poles. When electrons hit the solar tube wall, the fluorescent powder on the tube wall turns short-wave radiation into visible light. The brightness of the lamp tube depends on the number of electrons hitting the phosphor, and the number of electrons depends on the voltage of the electrode (filament). Although the fluorescent lamp is connected to the ballast, the voltage between the electrodes is still alternating current. Therefore, the voltage at both ends of the electrode changes with the frequency, which leads to the emission of electrons and the emission of electrons on the phosphor, and the luminous flux of the lamp flickers, which is the reason why the fluorescent lamp produces stroboscopic effect.

An incandescent lamp emits light by heating the filament to an incandescent state by an electric current, and the filament is made of tungsten. Because tungsten itself is thermally inert (it takes a certain time for the temperature to rise and fall, and some materials can't change when the heating voltage changes rapidly), the stroboscopic effect of incandescent lamps is very low, which is not easy for human eyes to feel.