Analysis of several problems related to static ele

Analysis of several problems related to static electricity in film production (Part 2)

comparison of common eliminators

film manufacturers and application manufacturers generally used hard bristle electrostatic brushes (anti-static brushes) in the past. Now, many manufacturers with high requirements have chosen some new eliminators, such as DC high-voltage eliminators and soft bristle electrostatic brushes

taking the bristle electrostatic brush as an example, the electricity elimination mechanism mainly refers to that because of the electrostatic induction of the conductor, a positive charge opposite to the negative polarity of the film is generated near the film. Through air ionization, corona current is formed, and a large number of positive and negative ions are generated in the corona area. As shown in Figure 3, under the action of electric field, negatively charged particles move strongly towards the direction of discharge needle B, coke and coking coal; The positively charged particles move towards the negatively charged film C, neutralizing the negative charge of the film. Because the electric field near the tip B "wangwanjie said depends on the potential of the film C itself and the distance from the tip to the film, the higher the voltage of the film C, the closer the distance from the tip B to the film C, the greater the charge density induced on the tip B, the stronger the electric field formed nearby, the more ionized charged ions, and the better the effect of eliminating static electricity (but it is easy to produce an arc if it is too close). There are two main indicators to investigate the performance of this electrostatic brush: critical voltage and corona current. The former can make the discharge needle produce the lowest voltage of corona discharge, of course, the lower the better; The larger the latter, the more charges are eliminated per unit time. In practical application, use a multimeter to test the resistance of the electrostatic brush. Generally, the resistance of the electrostatic brush with good quality is less than 1n/m. you can also use the eld-1 static voltage to gradually and slowly apply a load like the tail end of the hammer handle to test the potential before and after the installation of the electrostatic brush. There are many factors that determine the performance of the electrostatic brush. The longer the tip of the discharge needle is, the better the conductivity of the material is, and the better the performance of the electrostatic brush is

from Figure 3, it can be seen that since the power dissipation effect of the bristle electrostatic brush depends on the static voltage of the film, and the power dissipation effect is not complete, people have made improvements. By adding a DC high-voltage power supply with the opposite performance of the electrostatic charge of the film to the grounding a, the power dissipation effect is greatly improved, which is the principle of the direct current eliminator

if the hard hair at B in Figure 3 is replaced with soft hair without damage to the film, it can directly contact the film C; The "softness" of tonger soft hair can be tightly attached to the film due to the attraction of the charge after electrostatic induction, and the negative charge can be blindly connected to the earth through the soft hair electrostatic brush, which greatly improves the power dissipation effect

the problem that cannot be ignored - the installation of the consumer

take the bristle electrostatic brush as an example, its installation is as important as its performance. If the installation is uneasy, it will reduce the power dissipation effect, sometimes aggravate the static electricity, and even cause more harm to people. In general, as shown in Figure 5. Avoid positions a, D, C, D/L. It is best to be in front of the part that needs to eliminate static electricity, such as the part as close as possible to the part before printing and bag making or the part with the strongest electrostatic potential. The installation angle is perpendicular to the moving direction of the film, and the brush should be firmly supported and reliably pressed to the ground

there is a static electricity generation source at a in Figure 5, which is eliminated in the front and generated in the back, making the elimination work show that the dialog box of setting the loading speed is twice as effective as half. There is a grounding body at the back of u, close to the grounding body at C, and other power dissipation devices at D, all of which interfere with the induction of the electric field, making it unable to achieve the desired elimination effect

the test results show that using the installation method recommended by the installation manufacturer, the soft bristle electrostatic brush can eliminate more than 95% of static electricity at most

author/Wang Jiaju information source: Flexible Packaging News