Troubleshooting of a misaligned and stuck offset printing press, take a quick look!
In the production process, stable paper input is closely related to the stability of production quality. If the paper flow is not smooth, it can bring many troubles, such as inability to increase machine speed, inability to guarantee production capacity, inability to maintain ink balance, etc., which ultimately leads to the inability to guarantee the quality of printed products.
Recently, the CD102-5+L Heidelberg split five color printing machine used by our company experienced the following malfunction: when the machine speed exceeded 7000 sheets per hour, the paper output appeared skewed, which continuously caused problems such as skewed sheets and stuffiness, making production unable to proceed smoothly.
In response to the above malfunction, we first checked the paper output time, clicked the open paper feeding button, and slowly advanced to 40.3 °. Then, we inserted a detection pin at the Feida wall panel and found that the detection pin could smoothly pass through the two cam holes and insert into the Feida wall panel hole (Figure 1), which indicates that the paper output time is correct. Then we checked the single-sided adjustment of the paper feeding speed device and found no problem. Later, we checked whether the pressure of the paper output roller was consistent, and there was no problem. After turning on the air pump, it was observed that the paper feeding nozzle was also working synchronously. Continue to check and let the equipment continuously output paper while in a slow state, but no problems can be seen.
Figure 1 Detecting the position of the pin passing through
We spun on the paper feeding button again and accelerated to 11000 sheets per hour, occasionally feeling a slight vibration. After slowing down and stopping, we checked Feida again and finally found the problem. When holding the two paper feeding nozzles with my hand, I unexpectedly noticed slight back and forth shaking. After further inspection, I found that the problem lies in the connecting component between the paper feeding nozzle rod and the transmission rod, which has worn out (Figure 2), causing a gap in the fit between the transmission rod and the paper feeding nozzle rod, resulting in shaking. At low speeds, small shaking amplitude does not affect normal paper feeding, but as the speed increases, the shaking amplitude increases, ultimately affecting normal paper feeding. The problem location is shown in Figure 3.
Figure 2 Worn components
To verify our judgment, we grabbed one side of the paper feeding nozzle with a rubber band and used the elasticity of the rubber band to counteract the impact of the shaking on the single-sided speed of the paper feeding nozzle. At the same time, we increased the machine speed to 11000 sheets per hour, and the equipment was able to smoothly feed paper.
The problem was found and we immediately solved it by replacing the parts and thoroughly cleaning and maintaining the internal components of the Feida head. When the paper feeding speed was adjusted to 13000 sheets per hour during the trial run, there was no pressure (Figure 4), and the problem was successfully resolved.
Figure 4 Adjusting and restoring machine speed