Visit：4686 Date：2020-08-11

Control of surface temperature of UV lamp tube

Generally, the surface temperature of the UV lamp tube should be controlled at 200°C. If the surface temperature of the UV lamp tube is too high, it will shorten the life of the UV lamp tube, cause the UV lamp tube to expand and deform, produce "self-fogging" phenomenon, and even cause the reflective aluminum plate of the UV lampshade to melt and deform. However, the surface temperature of UV lamps should not be too low. When the surface temperature of some UV lamps is lower than 170℃, the UV radiation energy will decrease, which will cause the current of the UV lamps to increase. The transformer or capacitor burned out due to overload of current. In order to prevent a series of undesirable problems caused by the high surface temperature of the UV lamp, the following measures can be taken.
(1) A UV-LED light source is adopted, which can emit high-purity monochromatic ultraviolet light with a wavelength of 365 nm by converting light energy, which belongs to a cold light source. When the surface temperature of the UV lamp tube rises, the radiant energy of this light source can be highly concentrated in the ultraviolet band for curing, and the curing effect can be comparable to that of a high-pressure mercury lamp.
(2) Install a reflector to concentrate the ultraviolet radiation energy emitted by the UV lamp tube on the surface of the substrate, so as to be fully utilized and achieve the purpose of reducing the surface temperature of the UV lamp tube.
(3) UV cooling device that uses air cooling and water cooling at the same time. First, by installing a water jacket, water cooling is used to keep the UV lamp at a suitable working temperature; second, air cooling is used to cool the surrounding ambient temperature to ensure a suitable printing temperature without damaging the surrounding parts. The air-cooling method needs to use an air pump and a suitable air path system, and ensure that the fan power is consistent with the UV lamp power. The exhaust air volume is generally calculated according to the following formula: exhaust air volume (m3/h) = 150 (m3/h) ×UV lamp power (kW). Whether the air-cooling effect is effective needs to be judged by whether the exhaust pipe is damaged, leaking, deformed, or whether there are obstructions in the air outlet, etc. In actual production, high-temperature-resistant special exhaust pipes are often used.

Control of the surface temperature of the substrate
Even if the surface temperature of the UV lamp tube is kept within a reasonable range, the substrate of certain materials will become embrittled or deformed. In severe cases, it will damage the surrounding parts and cause a fire.
Therefore, when the substrate is too thin or the temperature resistance is too low, it is first necessary to determine whether it can meet the requirements of UV printing production through a light curing test; for the substrate that is not greatly affected by temperature, you can make full use of the UV radiation heat. Accelerate the curing speed. It can be seen that the surface temperature of the substrate is not as low as possible, but should be controlled within a reasonable range. Effective measures to reduce the surface temperature of the substrate are as follows.
(1) Use an optical sheet to isolate the radiation energy of the UV lamp tube from the substrate. This method is usually used for UV printing of easily deformable substrates.
(2) Add a water cooling device at the supporting board. The common method is to improve the internal structure of the supporting board and inject cold water. On the one hand, this method can avoid overheating of the surface of the substrate, and on the other hand, it does not affect the temperature of the coating.