The best choice is UV curing lamp and transformer

2022-09-30
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The correct selection of UV curing lamps and transformers

the application of UV photochemistry in the printing industry has developed very rapidly. UV materials are widely used in forms, Naiju, plastics, lotteries, magnetic cards, labels and other products, and almost all printing methods and models are applied, and these printing machines need to be equipped with UV chemical machines. Due to the complexity of printing machine models, there are many kinds of curing models. The production of optional UV curing machines often confuses printing manufacturers

the core components of UV chemical machine are UV lamp and transformer. The key to the curing effect is the selection and matching of UV lamp and transformer parameters, so that the lamp can radiate 365nm ultraviolet light most effectively. The author has been engaged in this research work for many years, and experiments have confirmed that UV lamp transformer should be a well matched system, which cannot be purchased separately How to match it and how to choose its parameters? The author talks about some views based on his own experience and discusses with his peers

I. determination of UV lamp parameters

1. The main parameters of UV lamp

uv lamp parameters include: main wavelength (curing lamp wavelength and 365nm in general printing); Lamp arc length L (i.e. the effective length of emitting ultraviolet light); Lamp density P. (output power per cm, such as 80 W/cm); Total power of lamp p; Lamp voltage U; Lamp current I; Lamp tube diameter; Conductive substances in the lamp tube, etc

2. Determination of UV lamp parameters

1) lamp arc length L: the maximum width of the cured product plus 2 cm

2) lamp power density P.: With high power density, the ultraviolet efficiency of the lamp tube is high, so the power density should be selected according to the movement speed of the cured material and the characteristics of the cured material

3) lamp current I: generally, the lamp current is less than 10a, because the current is large, the secondary heat loss of the transformer is large, and the secondary winding wire of the transformer is thick, resulting in the large volume of the transformer. But the current should not be too small, usually 5A. The lamp current can be adjusted through the leakage gap of the electric transformer. Generally, the output current is adjusted to the maximum through the high-speed leakage pin, and then the current is adjusted to the minimum 1-2a through the capacitor, but the lamp current cannot be adjusted by the capacitor

4) total lamp power P = l times P

5) lamp diameter: experiments have proved that a high current density in the lamp results in a high output UV component. For example, a 160W/cm lamp adopts a 28mm tube wall, and the UV intensity is 390W/the graphene support called aerogel is a chemical bonding cm square between the ceramic layer and the process called atomic layer deposition, while with a 22.5MM tube wall, the UV intensity is 620W/cm square. When P. After determination, the energy load per unit area of the tube wall is large, the tube wall temperature is high, and the lamp life is low. The pipe wall temperature can be reduced by water cooling or air cooling to improve the service life

6) conduction in the lamp tube: UV in chemical lamps are generally used as mercury lamps, and there are also metal halide replacement lamps. Mercury lamps are generally used for low power density. The output of the mercury lamp is 365nm, with a wide line range. Generally, the energy with curing effect is 18% - 23% of the input energy, and the light is both visible and infrared light. Metal halide lamps, through the mixing of several halides, increase the output energy of ultraviolet light, improve the fixation efficiency, and reduce heat radiation. They are generally used in high-power density lamps. The service life of mercury lamp is long, generally 600-2000 hours, and that of halogen lamp is short, generally 200-1000 hours

II. Determination of transformer parameters

uv curing when selecting a transformer, the following parameters are more important: input voltage, output voltage, input current and current. Since the internal conductivity of the lamp is that the cathode emits hot electrons to excite the mercury molecules to vaporize and conduct electricity, which is specially designed for processing food preservation. The ionic conductivity in the lamp changes with the vaporization process of mercury molecules, so the above parameters also change, and generally reach stability after 3-5 minutes. The following introduces the change process and selection method of several main parameters

1) input voltage: 380V power is generally used for the input power of transformers above 3KW

2) output voltage: the output open circuit voltage is 120% - 125% of the design voltage of the lamp. In this way, the lamp can be excited. The following aspects should be focused on

3) output current and output voltage

this is the basic process of voltage and current from connecting the transformer to maintaining stable operation. When the transformer is turned on, the lamp voltage is the open circuit voltage of the transformer. At this time, the lamp current is zero. With the emission and conduction of hot electrons, the lamp voltage drops sharply, and the current rises accordingly. Electrons collide with mercury molecules to excite them, and the movement of electrons is negatively hindered. The current drops slightly, and the voltage rises. When all supersaturated mercury is vaporized and conductive, the current rises to a stable state, and the voltage drops to a stable value

III. general methods for selecting UV tubes and transformers

the purpose of correctly selecting UV tubes and transformers is to radiate ultraviolet rays with a wavelength of 365nm most effectively. The content of the following lecture is a brief introduction to some parameters in theory. When selecting lamps and transformers, practical experience is very important. The general selection methods are introduced below

1) determine the lamp parameters and select the power density according to the curing requirements. For example, the curing speed of the rotary machine is fast, the power is 120-160w/cm, the printing speed of the silk machine is slow, and the lamp density is low

2) select the lamp current. If the total power of the lamp is 3-12kw, the current is 4.5-10a

3) select the voltage, and divide the total power by the current to obtain the voltage value. For example, the total power is 4kw, the current is 5.2a, and the voltage is 770v

the parameters of the transformer should meet the requirements of the lamp, but the high current of the transformer should be greater than the peak current, which is generally 120% of the working current. The voltage should take more than three groups of taps, because the lamp tube has great randomness and unstable parameters in the manufacturing process. Try three groups of taps of the transformer respectively to make the output voltage of the transformer close to the actual voltage of the lamp tube

an example of dealing with the failure of the paper cutter on site

the tension spring (material diameter 10mm, spring pitch diameter 60mm, effective number of turns 35) in the pickup mechanism of the medium pressure paper machine in our factory QZK program-controlled paper cutter suddenly disconnected for a section, and the length of disconnection is 1/3 of the total length. This is because the paper cutter has been used in the frontier for a long time, and the spring material is fatigued and broken

at that time, there were no spare parts in the factory. In order to restore the equipment to use as soon as possible, we decided to put 2/3 of that into trial according to the material conditions. The method is to screw out a length of each of the two removable high-speed screws connected with the inner circle of the spring, so that the total length of the same is equal to the length of the broken spring. After this treatment, it can be installed and used. Only the distance of the paper pressing gate rising (that is, the distance of rising to the final point) is 5mm shorter than the original, but it does not affect the operation of the political party and can meet the use requirements of the hair. In this way, it took only two hours to restore the equipment to the place of shipment and meet the urgent needs of production. After such treatment, it took nearly a month for the border to be transported to the place of shipment before replacing the original specification accessories from Shanghai Youfeng

at an annual meeting of the local printing technology association, I learned that the protection switch is used to protect the heating pipe and humidifying pipe from air burn and water shortage alarm The set point of the cold and hot shock test box = the temperature set point +20 ℃ ~ 30 ℃. The colleagues of another printing factory learned that there was also a paper cutter of the same model as our factory in the third factory, which also had the rupture of the tension spring of the overpressure paper machine pick-up mechanism, and there were no spare parts at that time, This is how we deal with it: we temporarily use the combination of two tension springs of different specifications in stock at that time (one parameter is: material diameter 8mm, spring mid diameter 45mm, effective number of turns 43, the other is: material diameter 5mm, mid diameter 25mm, effective number of turns 48. Put the spring with mid diameter 25mm in the spring core with mid diameter 45mm, and the two of each spring are fixed with the non screw of the corresponding pitch, while the adjustable screw will fix the size of the screw (the external thread of the screw is connected with the inner circle of the spring, and the internal thread of the screw is connected with the thread of the adjustable screw) through connection. After such treatment, the operation of political parties was resumed in a relatively short time. This kind of thinking can be used by Jingdezhen if the load is large and the size is subject to the installation conditions. In the on-site treatment, we can try our best to refer to the relevant mechanical design data, design and use reasonably, in order to achieve better treatment effect

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