Pneumatic design of sheet feeding machine paper feeding mechanism (two)
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2 Pneumatic design
It can be seen from the working principle of the above original paper feeding mechanism that the movement of the paper feeding mechanism is composed of the paper pressing motion, the paper separating motion and the paper feeding motion. The main motion occurs when the paper is in contact, while the trajectories of other time periods have no effect on the print quality. Therefore, according to the movement characteristics of the original paper feeding mechanism, pneumatic paper is used to pneumatically design the paper blowing nozzle mechanism, the paper separation nozzle mechanism and the paper feeding nozzle mechanism of the paper feeding mechanism.
1) Pressing the mouthpiece movement.
The paper-pressing nozzle mechanism is an important mechanism in the paper feeding mechanism. It is an important part of ensuring the output of a single sheet of paper. The J21O8 machine guarantees its function through two cams. Here, the function can also be guaranteed by using two cylinders. The cylinder I controls the swing of the platen nozzle to avoid interference between the platen nozzle and the paper when the separation nozzle and the transfer nozzle feed the paper. The small cylinder II ensures that the movement of the paper blowing nozzle is straight up and down when the paper is pressed, so as not to shake the paper and cause paper jam.
2) Movement of the separation nozzle.
The separation nozzle mechanism completes the separation of the paper with the assistance of the paper blowing nozzle, and has specific requirements for its movement. The mechanism can well replace the cam-controlled paper separation nozzle mechanism of the original J21O8 machine to realize its function. As can be seen from Fig. 4, the cylinder I controls the up and down movement of the separation nozzle to ensure that the separation nozzle reliably contacts the paper and separates it from the stack. Cylinder II ensures that the separation nozzle can quickly flip an angle (shaking head) immediately after it has been sucked, to avoid double and multiple sheets.
3) Transfer paper and paper movement.
The movement of the transfer nozzle mechanism is the most complicated movement relative to the platen nozzle mechanism and the separation nozzle mechanism, where three cylinders are used to achieve the necessary motion trajectory. Firstly, the cylinder I acts to control the transfer nozzle to descend to the paper surface. At this time, the suction valve is opened, and the suction nozzle sucks the paper; then the cylinder III controls the suction nozzle to realize the movement of the paper upward and the separation nozzle to make two The paper between the nozzles is slackened to prevent the paper from tearing; the cylinder II controls the transfer nozzle to complete the transfer of the paper to the paper feed table. The above three pneumatic mechanisms are fully capable of realizing the movements required for the sheet feeding mechanism of the sheetfed offset press. For sheetfed offset presses, the movement of the paper feeding mechanism must be synchronized with the movement of the printing components, so as to ensure the smooth operation of EO and ~U. The J2108 is secured by a jaw clutch. This method is not possible for the pneumatic mechanism designed. Here, a switch cam can be mounted on the impression cylinder shaft to control a stroke switch to ensure synchronization.
Since this mechanism uses a large number of cylinders, the relay crab system undoubtedly increases the unreliability of the control system, while the PI C control is compact, fast, and safe to use. Therefore, the coordination between the platen nozzle mechanism, the separation nozzle mechanism, and the transfer nozzle mechanism is controlled by the PLC.
The input end except the 0001 is connected to the cam-driven travel switch, and the other is the magnetic switch of each cylinder, thereby ensuring the sequential operation of the cylinder. Stopping the suction of the transfer nozzle and blowing is controlled by the cam switch to ensure that the transfer speed is synchronized with the gripper row and the front gauge.
It can be seen from the above that the pneumatic structure is simple and easy, not only can ensure the movement performance of the paper feeding mechanism, but also technically ensure the synchronization with other components. Due to the simplification of the structure, the cost of the printing mechanism will be greatly reduced, and the cam mechanism is cancelled for some reason, which can improve the dynamic characteristics of the system and reduce the hidden troubles.