Tension control of the most popular shaftless rota

Tension control of shaftless rotary offset press

tension control of shaftless universal 70 rotary offset press is very important, because the tension control mode of printing press has changed greatly under the condition of shaftless transmission, which is very different from that under the condition of shaft transmission. The shaftless drive tension control is mainly affected by the tension of the paper feeding part, the speed ratio of the paper feeding roller, and the speed ratio of RTF (the paper pulling roller in front of the triangle plate of the newspaper folding machine). Compared with shaft drive, the tension control of shaftless drive is more flexible, but the increase of variable factors also increases the difficulty of tension control, which requires us to constantly explore the laws of the three in practice to achieve the best cooperation mode

control of the inlet tension of the printing department>

the inlet tension of the printing department and the tension of the paper feeding department are bounded by the paper feeding roller, which is installed on the paper path between the printing device and the paper feeding machine to force the paper belt to run, so as to avoid the fluctuation of the paper belt tension before the paper feeding roller directly affecting the paper belt tension after the paper feeding roller, and ensure that the paper belt entering the printing device is more stable after two tension controls. The control principle of the secondary tension system is realized by friction based on the difference between the speed of the paper belt and the linear speed of the paper feeding roller. Generally, the linear speed of the paper feeding roller is less than the speed of the paper tape. When the paper feeding roller is used, the tension of the paper feeding part has a certain impact on the inlet tension of the printing part. The key to accurately control the inlet paper tape tension of the printing part is to reasonably set the speed ratio of the paper feeding roller motor and the drum motor through the main console of the printing machine, which is generally set at -0.15% left and right (according to the number of values of the printing part, it is slightly different, but the difference is not too great). The shaftless transmission mode has completely changed the previous mode of controlling tension by mechanical devices, and the tension is controlled by the relative speed difference formed by the speed change between digital motors, that is, in the paper feeding roller, the drum of the printing department, and the folding 2 Next, check that there is a small speed difference between the linear speeds of the amplifier unit and the RTF to control the tension. A decrease in the speed of the feed roller motor will increase the inlet tension of the printing section, and vice versa. In addition to the speed ratio, another factor affecting the tension control of the paper feeding roller motor is the pressure of the paper feeding roller and the press roller. The pressure is reflected by the indentation during press, which is generally 5 ~ 6mm. If the indentation is too small, the contact pressure of the two rollers is small, the friction between the paper feeding roller and the paper is also small, and the tension decreases under the same speed ratio of the paper feeding roller motor; If the indentation is too large, the rubber closing roller and the paper feeding roller will generate too much heat due to the large contact pressure during the operation, which will accelerate the aging of the rubber roller and reduce its service life. The paper feeding roller is very important to ensure the printing quality. It can effectively prevent the problem of running out of order in the printing process

printing department outlet tension control folding machine RTF - Triangle pulling roller motor is used to maintain a certain tension between the paper belt at the printing department outlet and the triangle to ensure that the paper belt enters the folding machine smoothly after printing. The speed (linear speed) of the RTF motor is generally about 0.8% faster than the speed of the drum of the printing department, and the variation range is 0 ~ 2.0%. The setting of this value depends on the specific situation. If it is not set properly, it will not only affect the tension from the outlet of the printing department to the triangle, but also affect the tension after the paper tape enters the newspaper folding machine. If the value is too large, the tension of the paper tape from the printing department to the triangle will become larger, and the tension of the paper tape from the triangle to the newspaper folding machine will become smaller; If the value is too small, the tension of the paper tape from the printing department to the triangle will be reduced, and the tension of the paper tape from the triangle to the newspaper folding machine will be increased. When the printed paper path is less, this value can be reduced appropriately, because the tension at this time is easier to control; When there are many paper paths printed, the speed ratio of RTF motor should be increased appropriately to meet the tension requirements of the innermost paper, while the tension of other paper belts can be adjusted by adjusting the tension values of the paper feeding roller and the printing section. The outlet tension of the printing department is controlled by setting the speed ratio of the folding machine RTF and the paper feeding roller under the joint action of the two. When the speed ratio value of RTF motor of newspaper folding machine changes, the outlet tension of all printing departments will change. If the outlet tension of the printing section with only one paper path is inappropriate, the speed ratio of the corresponding paper feeding roller motor and the tension of the paper feeding section should be adjusted to realize the change of the tension of the separate paper path, and the speed ratio of the RTF motor should not be adjusted

the influence of the paper pinch roller on the tension. The paper pinch roller mainly controls the tension of the paper belt after RTF, and plays a very important role in further controlling the tension from the outlet of the printing department to the triangle. Two pairs of paper nipping rollers maintain a certain tension before the paper belt is cut, but there is a certain difference. The function of the first pair of paper clamping rollers under the bending rollers is to make the paper tape stick to the triangle and pull the paper tape to be cut smoothly (the cutting knife is passive); The function of the second pair of paper pinch rollers is to maintain a certain tension of the paper belt. If the paper shakes when the equipment is running, it indicates that the tension between the two pairs of paper clamping rollers is inappropriate. The tightness principle of the two pairs of paper clamping rollers is that the second pair is slightly tighter than the first pair, because when the tightness of the paper clamping rollers changes, its surface linear speed and the relative speed of the paper belt also change correspondingly. Although the functions of the two pairs of paper clamping rollers are different, they must be used together to maintain a stable paper tape tension when the equipment is running at high speed and prevent the paper tape from deviation. If the paper clamping roller is too loose, the paper belt will move left and right due to low tension. If it is too tight, the paper edge will be crushed and easy to tear, and the teeth on the paper clamping roller will be damaged, or the size of the newspaper cutting will change

the influence of other factors on the tension. If the paper passing roller is too dirty, it can also cause unstable tension and break the paper. If the paper passing roller is not cleaned in time after being used for a long time, a lot of sludge will adhere to its surface, resulting in inconsistent diameter and inconsistent tension on the paper belt. If the tension of the paper tape exceeds its tensile strength, a paper breaking accident occurs. Especially when replacing paper from different manufacturers, the problem will be more serious due to the different tightness on both sides of the paper tape, which will greatly affect production. Therefore, it is necessary to clean the paper roller in time

the tension control part of the paper feeding part is composed of brake pads, brakes, floating rollers, etc. in order to keep the tension of the paper tape constant, the paper roll brake must be able to automatically adjust according to the fluctuation of the paper tape tension to ensure that the paper tape enters the printing device at a uniform speed and smoothly. During the smooth operation of the machine, ensure that the tension of the paper tape is stable at the given value, and prevent the paper tape from overloading and loosening at will during startup and braking. In the printing process, as the diameter of the paper roll continues to decrease, in order to maintain the constant tension of the paper tape, the braking torque needs to be adjusted accordingly. MEG dlp1000 paper feeding machine adopts the shaft braking mode for the braking of the paper roll. The brake pad and brake disc are set at the shaft end of the paper roll core, and the braking force is loaded by air pressure, that is, the pneumatic tension control system. During the printing process, the linear speed of the paper tape remains unchanged, while the angular speed of the paper roll increases with the decrease of the diameter of the paper roll. Without considering the inertia moment and resistance moment generated by angular acceleration, in order to ensure the stable operation of the paper tape, the following conditions should be met: F × R＝T × R F is the tension of the paper tape, R is the radius of the paper roll, t is the braking force of the paper roll core, and R is the braking force radius of the paper roll core. It can be seen that as the radius of the paper roll decreases, if the braking force is not changed, the tension on the paper tape will become larger and larger, and eventually the paper tape will be broken. Therefore, on the premise of keeping the tension of the paper tape stable, with the reduction of the radius of the paper roll, the braking force must be reduced according to a certain law. In short, a certain friction force is generated after the contact between the brake pad and the brake disc, so that the paper tape has a certain tension. After the floating roller swings under the action of tension, it drives the potentiometer on it to change to a certain extent, converts the change of tension into an electrical signal, and controls the air pressure of the brake cylinder, so as to achieve the purpose of controlling the friction force and realize the automatic control of the paper tape tension. The distance between the brake pad and the brake disc should be between 1 ~ 2mm. If the gap is too large, the brake pad cannot be clamped effectively when the air pressure of the cylinder changes, resulting in too small tension, causing the floating roller to be pulled down suddenly when starting up and the paper tape to be stretched and broken; If the gap is too small, the cylinder will always clamp the brake pads, and the change of air pressure in the cylinder cannot adjust the clamping degree of the brake pads and brake discs, which will eventually pull the paper tape apart. Especially when the tension display value changes from 4 digits to 3 digits when the machine is turned on, the paper will break due to the excessive tension of the paper tape. The wear condition of the brake pads should be checked regularly according to the different materials of the brake pads, and the clearance should be adjusted appropriately, otherwise the tension control will be affected. The failure of the brake pad will cause extremely unstable tension control, especially when the floating roller swings greatly during the paper receiving, and the paper belt floats before entering the RTF. Adjusting the tension of the paper feeding roller and the RTF and the paper feeding department cannot solve the problem. After the paper receiving, the tension disappears instantly (the floating roller adjusts greatly after the paper receiving), resulting in paper breaking. The reason for the reduction of the braking effect of the brake pad is that the material of the wear-resistant layer of the brake pad is relatively soft and its debris cannot be discharged in time. After friction, it accumulates on the brake pad to form a glaze like material, which reduces the friction coefficient. At this time, the brake pads can be polished, the glaze like substances can be removed, the number of chip removal grooves can be increased or the brake pads can be replaced

the relationship between the paper feeding section, paper feeding roller and RTF

the paper feeding section, paper feeding roller and RTF are interactive and relatively independent. The tension set by the paper feeding part and the speed ratio set by the paper feeding roller (such as bolts of various shapes, torsion springs, clockwork, etc.) or non-metallic materials shall be tested for changing the strength; It can also change the strength of the composite materials and components, and the reasonable configuration between the experiments can realize the control of the inlet tension of the printing department. If the tension of the paper feeding section is not large enough, it is not enough to rely on the paper feeding roller alone. Because the speed difference between the speed of the paper feeding roller and the speed of the drum of the printing department is very small (only 1 ‰ ~ 2 ‰), it is not enough to provide sufficient tension for the printing department. If the speed ratio of the paper feeding roller is adjusted too large, the load of the paper feeding roller will be increased, which is not conducive to its stable operation, and it is easy to cause electrical faults of the paper feeding roller motor, such as abnormal governor, etc

the speed ratio change of RTF motor is for all printing sections, and any change will affect the outlet tension of all printing sections. If it is too large, it will increase the difficulty of controlling the outlet tension of printing sections. The relationship between the paper feeding section, paper feeding roller and RTF is simply the relationship between the part and the whole. The proportioning relationship among the paper feeding section, paper feeding roller and RTF follows the principle of increasing from outside to inside, so as to realize the increase of tension from outside to inside. The tension of the outermost paper tape is the smallest, and the tension of the innermost paper tape is the largest. The tension of the paper tape between the two is between the two, and increases from outside to inside

at this time (the folding machine f is between T1 and T2), the RTF speed ratio is set to 0.8%, the speed ratio of the paper feeding roller motor is set to 48 in turn (the paper feeding roller motor control system of T1 is different from others), -0.14%, 0.15%, 0.17% and - 0.18%, and the tension of the paper feeding part is set to 18, 18, 19 and 20 in turn. If the outermost paper tape has the maximum tension, there will be many insurmountable problems