Pneumatic design of the paper feeding mechanism of

2022-10-19
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Pneumatic design of paper feeding mechanism of sheet fed offset press

based on the analysis of the paper feeding mechanism of J2108 sheet fed offset press, this paper puts forward the pneumatic design scheme of the paper feeding mechanism, and puts forward a specific solution to solve the synchronization between the paper feeding mechanism and the printing system by using PLC and the corresponding travel switch, and gives the PLC ladder diagram to realize the movement of the paper feeding mechanism

key words: sheet fed offset press; Paper separation mechanism; In recent years, with the rapid development of science and technology, the printing industry has also made historic innovations. Optical fiber technology and computer technology continue to penetrate the printing industry. The popularization and application of a large number of new technologies with digitalization and networking as the core in the printing industry has made great changes in the international printing industry. Especially in terms of printing equipment, the printing machine simplifies its complex institutional structure, and light, electricity, liquid, gas, and computer are applied to modern printing equipment. Therefore, high speed, automation and high quality are the common direction of the development of traditional printing equipment. In order to meet the needs of modern printing, the paper feeding device of sheet fed printing machine is also constantly developing in the direction of pneumatic, electric and other automation

pneumatic technology uses compressed air as the medium to drive and control machinery. Door special technology. Because it has the advantages of energy saving, no pollution, high efficiency, low cost, safety and reliability, simple structure and so on, it is widely used in various industrial departments. It is precisely because of the advantages of pneumatic, in the field of foreign printing machine manufacturing industry, the pneumatic design of machine equipment has increasingly become a trend. For example, in the paper feeding mechanism of Roland printing press, a large number of pneumatic control systems are used to replace traditional mechanical devices. It uses vacuum paper feeding, variable speed suction belt and pneumatic side pull gauge, which greatly reduces the mechanical mechanism and reduces the difficulty of mechanical manufacturing, installation and debugging. The left and right positions of the paper stack and the rear closing position of the paper feeder can be accurately controlled by the pneumatic switch, so as to ensure the accurate overprint position of double-sided printing

l working principle of the original paper separation mechanism of the sheet fed offset press

people know that the paper feeding mechanism of the sheet fed offset press is a very important component of the offset press, and its function is to separate the paper and transfer it to the paper feeding device. It is composed of inner suction nozzle mechanism, paper pressing mechanism and paper delivery suction nozzle mechanism, and the mechanism and motion principle of J2108 machine paper feeding mechanism

the working principle of the movement of each part in the printing engineering is:

1) the paper separation nozzle moves downward, sucks the top piece of paper, lifts it up and tilts it back, so as to prevent double sheets and facilitate the insertion of the paper pressing nozzle

2) insert the paper pressing blowing nozzle, press the lower paper and turn on the air blowing path to separate the upper and lower paper, and detect the height of the paper stack at the same time

3) the paper transfer nozzle moves to the right to absorb the paper. When comparing, the paper separation nozzle and the paper transfer nozzle control the paper at the same time to transfer the paper, that is, from the paper separation nozzle to the paper transfer nozzle

4) the paper separation suction nozzle cuts off the suction air path to discharge the paper, completes the paper handover, and then rises. At this time, the paper pressing blow nozzle stops blowing and leaves the paper stack. At this time, the paper delivery suction nozzle moves to the left to output the paper. In order to ensure the correct handover and transportation of paper, the paper delivery suction nozzle should achieve a certain trajectory. The motion trajectory of the paper delivery suction nozzle is divided into four stages according to different motion characteristics

cd segment: the paper delivery suction nozzle rises and returns to the right during the experimental process

dn segment: the paper delivery suction nozzle drops to. Point to the lowest position to suck paper

n6 segment: the paper delivery suction nozzle sucks the paper up and completes the paper handover with the paper separation suction nozzle, that is, when the paper delivery suction nozzle sucks the paper up, the paper separation suction nozzle also rises and discharges the paper before reaching point B, so the motion track of N6 segment is the paper handover. This material is jointly produced with BVB matrix, a Dutch greenhouse gardening expert. In N6 segment, the paper delivery suction nozzle and the paper separation suction nozzle suck the paper at the same time. Section 6C: when the paper separation suction nozzle releases the paper at point B, the paper delivery suction nozzle sucks the paper and moves to the left to feed the paper. When the paper delivery suction nozzle reaches point C, the left edge of the paper has passed through the paper feeding shaft to release the paper, and then enter a working cycle. It can be seen from the movement principle diagram of the paper separation mechanism in Figure 1b that the movement track of each mechanism of the paper conveyor is mainly realized by the cam mechanism. Due to the characteristics of the cam mechanism, the paper feeding mechanism of the current sheet fed offset press has the following disadvantages:

compared with other operation links in industrial and agricultural production

1) due to the manufacturing and assembly error adjustment of various parts of the mechanical cam is very difficult, time-consuming and laborious

2) the cam is easy to break down due to its fast wear and short service life during long-term operation

3) if its weight is only half the movement of glass, the cam must be redesigned when the process changes. Based on the motion track characteristics of the paper feeding mechanism and the inconvenience of the original mechanism in processing and use, we think it is necessary to improve this mechanism, and pneumatic components are the ideal choice

2 pneumatic design scheme

it can be seen from the above working principle of the original paper feeding mechanism that the motion of the paper feeding mechanism is composed of paper pressing motion, paper separation motion and paper delivery motion respectively. Its main motion occurs when it contacts the paper, while the motion trajectories in other time periods have no impact on the printing quality. Therefore, according to the motion characteristics of the original paper conveying mechanism, pneumatic components are used to pneumatically design the paper pressing and blowing nozzle mechanism, the paper separating nozzle mechanism and the paper delivering nozzle mechanism of the paper conveying mechanism

1) paper pressing and blowing mouth movement

the paper pressing and blowing mechanism is an important mechanism in the paper feeding mechanism, which is an important link to ensure the output of single sheet paper. J21o8 machine ensures its function through two cams. Here, the realization of its function can also be guaranteed by using two cylinders

it can be seen that cylinder I controls the swing of the paper pressing blowing nozzle to avoid the interference between the paper pressing blowing nozzle and the paper when the paper is fed by the paper separation suction nozzle and the paper delivery suction nozzle. Small cylinder II ensures that the movement of the paper pressing blowing nozzle is straight up and down when pressing paper, so as to avoid rubbing the paper and causing confusion

2) paper separation suction nozzle movement

the paper separation suction nozzle mechanism completes the paper separation work with the help of the paper pressing and blowing nozzle, and has specific requirements for its movement. The mechanism can well replace the cam controlled paper separation suction nozzle mechanism in the original j21o8 machine to realize its function. Cylinder I controls the up and down movement of the paper separation suction nozzle to ensure that the paper separation suction nozzle reliably contacts the paper and separates it from the paper stack. Cylinder II ensures that the paper separation suction nozzle can quickly turn an angle (shake your head) after absorbing the paper, so as to avoid the occurrence of double sheets and multiple sheets

3) paper transfer and suction movement

the motion of the paper delivery suction nozzle mechanism is the most complex compared with the paper pressing and blowing nozzle mechanism and the paper separation suction nozzle mechanism. Here, three cylinders are used to realize its necessary motion trajectory. First, cylinder I controls the paper delivery suction nozzle to drop onto the paper surface. At this time, the suction valve is opened and the suction nozzle sucks the paper; Then, the air cylinder III controls the suction nozzle to realize the upward movement of the paper and the direction of the paper separation suction nozzle, so as to relax the paper between the two suction nozzles and avoid tearing the paper; Cylinder II controls the paper delivery suction nozzle to complete the transfer of paper to the paper feeding table. The above three pneumatic mechanisms can fully realize the movement required by the paper feeding mechanism of the sheet fed offset press. For the sheet fed offset press, the movement of the paper feeding mechanism should be synchronized with the movement of the printing parts, so as to ensure the smooth progress of EO, ~u work. J2108 machine is synchronized through the jaw clutch. For the designed pneumatic mechanism, this method is impossible. Here, a switch cam can be installed on the embossing cylinder shaft to control a travel switch to ensure its synchronization

because this mechanism uses a large number of cylinders, the relay control system undoubtedly increases the reliability of the control system, while the PI C control is compact, fast, safe and reliable. Therefore, PLC is used to control the coordination between the paper pressing and blowing mechanism, the paper separating and sucking mechanism and the paper delivering and sucking mechanism. Set up the ladder diagram of PLC

except that 0001 is connected to the travel switch driven by the cam, other input terminals are magnetic switches of each cylinder, so as to ensure the sequential action of the cylinders. Stopping the suction and blowing of the paper delivery suction nozzle by the cam switch can ensure that the speed of paper delivery can be synchronized with the paper taking teeth and the front gauge

3 conclusion

it can be seen from the above that the pneumatic structure is simple and easy to operate, which can not only ensure the motion performance of the paper feeding mechanism, but also technically ensure the synchronization with other parts. The simplification of its structure will greatly reduce the rising cost of the printing mechanism, and the cancellation of the cam mechanism for some reason can improve the dynamic characteristics of the system and reduce the hidden trouble of failure

information source: must win

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