Comprehensive discussion on the technology of the

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Comprehensive discussion on web offset press technology paper system III

④ floating roller: including floating roller 24 and its spring force adjustment mechanism. Its main function is:

to eliminate most of the tension changes caused by the paper roll itself and some external factors, such as the non-circular paper roll. When the paper belt tension increases, the floating roller rises against the spring force, and the paper path shortens and the tension decreases. When the tension of the paper belt decreases, the floating roller moves downward under the action of spring force, the paper path is lengthened, and the tension increases. Because the floating roller plays a good role in buffering sample breakpoints and damping, it is also called damping roller or buffer roller

both ends of the floating roller are connected with the support through springs respectively, which can skew in the vertical plane, so the uneven tension and deviation caused by the elastic edge of the paper tape can be partially eliminated

⑤ sensing mechanism: this part includes damper with different scratch resistance levels 10, sensing mechanism 11, sensing roller 22, adjusting nut 26 and its tension spring 25, sensing gear and its connecting rod, etc. The function of this part is to send a feedback signal when the diameter of the paper roll changes to adjust the braking force of the magnetic powder brake, so as to ensure the stability of the tension. We know that the relationship between the paper tape tension F, the magnetic particle brake braking torque M and the paper roll radius R is m=f · R. when the paper roll radius r decreases, the magnetic particle brake braking torque M does not adjust, that is, m does not change, so the paper tape tension f increases, and the sensing roller 22 shifts to the left, sending a feedback voltage through the sensing resistor, and after a complete set of circuit processing, the magnetic particle brake current is reduced, thereby reducing its braking torque M, Reduce the tension of the paper tape; On the contrary, when the tension decreases (such as parking, deceleration, etc.), the sensing roller 22 swings to the right, and a feedback voltage is sent through the sensing resistor. After a set of circuit processing, the braking torque M of the magnetic particle brake is increased, and the tension is increased. This set of mechanism ensures that the diameter of the paper roll changes. When using the chemical properties of the latest Ingeo polymer to provide more stable processability for wire rod manufacturing, adjust the braking torque M in time to keep the tension of the paper tape unchanged

⑥ adjusting roll: including adjusting roll 12 and its spring force adjusting mechanism. Its main function is to adjust the tension change caused by the elastic edge of the paper tape and the deviation of the paper tape. The roll is supported by the spring bearing seat. Due to the unequal pressure of the paper belt on the roll due to the elastic edge or artificial adjustment, the center line of the roll can be skewed and not parallel to the center line of other paper passing rolls, so as to achieve the same tension when the paper belt has the elastic edge, so as to ensure that the paper belt does not deviate

⑦ paper feeding mechanism: including paper feeding steel rollers 13 and 16? The stepless speed regulation mechanism of the paper feeding rubber roller 14, the air cylinder 15, its connecting straw and the paper feeding steel roller? Its main function is to control the speed of the paper tape before entering the printing part by adjusting the linear speed of the paper feeding steel roller and the pressure of the paper feeding rubber roller 14 on the paper feeding steel roller, and make the paper tape enter the printing unit smoothly? Due to the improvement of technology, many paper feeders now cancel the paper feed roller, and some web offset presses add paper feed rollers in front of the printing unit to improve the stability of the paper tape entering the printing unit

⑧ brush mechanism: including brush 8, brush support roller 7, cylinder 5, dust pump and paper wool storage, etc. Its main function is to brush away the paper wool and paper powder on the surface of the paper tape, so as to reduce the loss of paper wool and paper powder during printing and improve the printing quality. Due to the improvement of paper quality, the paper wool and paper powder are reduced, and the function of the brush mechanism is not ideal. Now most paper feeders have canceled the brush mechanism

due to the magnetic powder brake controlling the tension of the paper belt, the braking force of this paper feeder is stepless adjustment, which is fast and convenient. At the same time, it is equipped with floating and dare to seek excellent rollers and paper feeding rollers, so that the paper belt tension control is stable and the change is very small. The paper feeding mechanism is controlled by air cylinder, which is convenient for paper feeding, sensitive and reliable, and its performance is much better than that of a simple paper feeder. Of course, relatively speaking, its structure is more complex than a simple paper feeder, and its operation and maintenance are also more complex

3) electric paper feeding machine

the figure shows the electric paper feeding machine. The main difference between this machine and the paper feeder shown in the figure (see the previous page) is the paper feeding mechanism. Its sensing mechanism, paper feeding mechanism and magnetic particle brake are the same as those in the figure. Other mechanisms, such as floating roller, adjusting roller (Figure 15, 17), brush mechanism, etc., although different from the specific structure of pneumatic paper feeding machine, have the same function

the paper feeding mechanism of the electric paper feeding machine includes the paper channeling tray (not shown in the figure), the paper feeding arm 1 and its supporting shaft, the electric lifting mechanism, the electric axial moving mechanism, the electric clamping mechanism, etc. The clamping mechanism of this paper feeder is equipped with fixed and movable plum blossom tips on the two upper paper arms respectively, which are electrically clamped. The paper roll does not need to go through the paper shaft, and the plum blossom center directly supports the paper roll. After the paper roll is clamped tightly, the paper arm rises, and the electric axial adjustment (see Chapter VI of this lecture for the specific structure) can be used after the position is appropriate. Because the paper roll does not need to wear the paper shaft, the labor intensity of the operator is reduced. (text/qifubin)

(to be continued)

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