Improvement of Automatic Paper Feeding for Offset Press

Our factory purchased a YP2A1 folio two-color offset press from Henan Xinxiang Machine Tool Factory in 1996. The control system of the machine adopts Japanese Mitsubishi F1-60MR programmable controller, which has the advantages of simplified electrical device, reliable performance, and easy maintenance. Etc. However, the automatic raising mechanism of the paper feeding pile is still similar to the single and two-color offset printing machines produced by "Northren", and a combination of an electromagnet and a machine is used. That is, during the printing process, the paper on the paper stack is gradually reduced until the paper sensing lever touches the micro switch SQ07, and the programmable controller causes the automatic lifting electromagnet to pull in and drives the mechanical crank connecting rod, the ratchet wheel, and the pawl to complete the paper stack successively. The biggest drawback of this kind of electromagnet to control the automatic rise of the paper stack is that frequent operation of the electromagnet not only brings unpleasant pull-in shock noise, but also the electromagnet coil is easily burned.
Sometimes the coil is replaced by up to 7 to 8 coils per month. Each time the coil is replaced, it is difficult to ensure the electrical performance of the electromagnet due to technical differences. Instead, the electromagnetic coil is damaged, and the solenoid's suction stroke must be adjusted repeatedly. normal work. Therefore, not only does it seriously affect production, but the maintenance costs increase accordingly. As a result, we made some improvements to the paper automatically. After the improvement, the use effect is good and it is welcomed by the operating workers. The introduction is as follows, for printing colleagues reference.
Automatic lifting circuit of the paper stack is shown in Fig.1. Working principle: The paper bed safety lever controls the X513 to close. Press the paper feed button, X504, M204 closes, and the paper feed starts. M204 also turns on the paper stack automatic rise control circuit. The paper sensing lever touches the micro The switch SQ07 is controlled by the X011 point of the programmable controller, and the output is Y534 to control the relay KA4. The KA4 then controls the automatic lifting magnet YA01 to pull in and drive the crank connecting rod to make the paper stack rise once.
The improved circuit is shown in Fig. 2. Within the dashed line, the program is added. Using the F1-20P simple programmer, the program can be easily written in the field. Remove the automatic rising magnet outside the programmer and raise the micro The short circuit of the switch is connected to ensure that the paper stack is manually lowered quickly. Another card-mounted AC contactor KM is used to replace the relay KA4. The card is mounted on the rail and controls the lifting motor of the paper stack. Working principle: In the paper feeding process, a paper probe lever touches the micro switch SQ07, and through the program controller X011 point input, the internal controller M203 of the programmable controller is closed, the output relay Y534 and the time relay D are also closed at the same time, the relay Y534 controls the AC contactor K suction Together, the paper stack lift motor is rotating forward, the stack is up, and the time relay T is delayed by 0.2 s and the Y534 is disconnected. The AC contactor KM is powered off, and the paper stack stops rising. This continuously operates in a cyclic manner so that the paper stack is always maintained at the working height of the paper feed.
In the absence of programming capabilities and conditions, the circuit shown in Figure 3 can also be used. This circuit is simple, easy to install, retain the relay KA4, another increase of a card-mounted AC contactor and a billion 20-type, adjustable time delay of More than 0.1s relay, the AC contactor card installed on the track, And fix the time relay in proper position, insert the circuit according to the solid 3, adjust the time relay, in order to meet the delay time of automatic rise of the paper stack, it can work normally. This circuit is also applicable to other offset presses that use electromagnets to control the automatic rise of paper stacks, such as single and two-color offset presses produced by “Northren”, as long as the automatic rising electromagnets are disconnected in the control box, and ab will be shown in Figure 3. Pick people up and fix contactors and time relays in place. Removing the electromagnet can also cause the paper stack to rise automatically.
Practice has proved that because the improved circuit removes the electromagnet, not only the problems caused by the electromagnet are completely eliminated, but also the mechanical parts of the original automatic paper lifting such as a ratchet wheel, a ratchet pawl, a moon plate, a cam, a crank connecting rod, etc. Can be removed, this is for offset press manufacturers. It can not only improve the existing problems of the machine, but also reduce the production cost.

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