Pneumatic design of sheet feeding machine paper feeding mechanism (on)
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Based on the analysis of the J2108 sheetfed offset printing machine, the paper proposes a pneumatic design scheme for the paper feeding mechanism, and proposes a specific solution to solve the synchronization between the paper feeding mechanism and the printing system by using PLC and corresponding stroke switch.
In recent years, with the rapid development of science and technology, the printing industry has also undergone historic innovation. Fiber optic technology, computer technology continues to penetrate the printing industry. The promotion and application of a large number of new technologies centered on digitalization and networking in the printing industry has brought about tremendous changes in the international printing industry. Especially in terms of printing equipment, the printing machine simplifies its own complex structure, and the light, electricity, liquid, gas, and computer are all applied to modern printing equipment. Therefore, high speed, automation and 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 sheetfed printing press is also developing in the direction of automation such as pneumatics and electric motors.
Pneumatic technology uses compressed air as a medium to drive and control machinery. Door expertise. Because it has the advantages of energy saving, pollution-free, high efficiency, low cost, safety and reliability, and simple structure, it is widely used in various industrial sectors. Due to the advantages of various aspects of pneumatics, in the field of foreign printing machine manufacturing industry, the pneumatic design of machinery and equipment has become a trend. For example, the Roland printing press uses a pneumatic control system to replace the traditional mechanical device in the paper feeding mechanism. It uses vacuum paperboard, variable speed suction belt and pneumatic side pull gauge, which greatly reduces the mechanical mechanism, reduces the mechanical manufacturing and installation, and debugs. Difficulty. The left and right positions of the paper stack and the rear closing position of the paper feeder can be precisely controlled by a pneumatic switch, thereby ensuring accurate overprinting position of the double-sided printing.
1. The working principle of the original paper separation mechanism of sheetfed offset printing machine
It is known that the paper feed mechanism of a sheetfed press is an important component in an offset press, and its function is to separate the paper and transfer it to the paper feeding device. The nozzle mechanism, the paper-pressing mechanism and the paper-feeding nozzle mechanism, the mechanism of the J2108 paper feeding mechanism and its movement principle.
The working principle of each part of the movement in the printing project is:
1) The paper blowing nozzle moves downward, sucking the top piece of paper, lifting it up and then tilting it to prevent double sheets and facilitating the insertion of the paper blowing nozzle;
2) Insert the pressure paper nozzle, press the paper below and open the air blowing air to separate the upper and lower papers, and simultaneously detect the height of the paper stack;
3) The paper conveying nozzle moves to the right and sucks the paper. When compared, the paper separating nozzle and the paper feeding nozzle simultaneously control the paper, and the paper is handed over, that is, the paper feeding nozzle is delivered to the paper feeding nozzle;
4) The separation nozzle cuts off the suction air path to release the paper, and then the paper is handed over, and then rises. At this time, the pressure paper blowing nozzle stops blowing and leaves the paper pile. At this time, the paper feed nozzle moves to the left to output the paper. In order to ensure the correct transfer and transportation of the paper, the transfer nozzle should achieve a certain trajectory as shown in Figure 2. The movement path of the transfer nozzle is divided into four stages according to the characteristics of the movement.
Cd segment: the transfer nozzle rises and returns to the right;
Dn segment: The transfer nozzle drops to. Pick up the paper at the lowest position;
Section n6: The paper feed nozzle sucks up the paper and completes the paper transfer with the paper feed nozzle. That is, when the paper feed nozzle sucks the paper up, the paper feed nozzle also rises and proceeds before the point b is reached. Paper is discharged, so the movement track of the n6 segment is the process of paper transfer. In the n6 segment, the paper feed nozzle and the paper separation nozzle simultaneously suck the paper. Section 6c: When the b-point paper nozzle is reached to release the paper, the paper feed nozzle sucks the paper to the left to feed the paper. When the transfer nozzle reaches point c, the left edge of the paper has been released through the paper feed shaft and then enters a work cycle. It can be seen from the motion schematic diagram of the paper separation mechanism of Fig. 1b that the movement path of each mechanism of the paper feeder is mainly realized by the cam mechanism. Due to the characteristics of the cam mechanism, the paper feeding mechanism of the sheetfed offset printing machine exists. The following disadvantages:
1) It is very difficult, time-consuming and laborious to adjust the manufacturing and assembly errors of the mechanical cam components;
2) The long-term operation of the cam is fast, the life is short, and the fault is easy to occur;
3) Redesign the cam if its motion process changes. Based on the characteristics of the trajectory of the paper feeding mechanism and the inconvenience of the original mechanism in processing and use, we believe that it is necessary to improve the mechanism, and pneumatic components are the ideal choice.