The drum is one of the important parts of the offset printing machine, and its vibration directly affects the quality of the printed matter. For example, common ghosting, paper-feeding rule errors and streaks in life are generally caused by abnormal vibration of the offset printing machine drum. The vibration of the drum accelerates the wear of the offset press components, resulting in a decrease in the print durability. In order to achieve beautiful printing on high-speed offset presses, it is necessary to ensure smooth running of the rollers.
In the printing process of the offset printing machine, the printing unit is responsible for the main function of image transfer, which can be said to be the core of the offset printing machine. The printing unit of the offset printing machine comprises a plate cylinder, a gear transmission part, a clutch pressing mechanism, a blanket cylinder, an impression cylinder, a paper conveying device and related control devices. There are many reasons for inducing the vibration of the offset printing machine drum, mainly including the following aspects:
1. The transmission of the offset printing machine is unbalanced
Generally, the offset printing machine transmits power through the helical gear of the shaft end of the drum. When the transmission mechanism is unbalanced, the offset printing machine drum is subjected to the combined action of the axial force and the radial force, thereby causing the forces at both ends to be inconsistent and generating vibration.
2. Offset or intermittent motion structure of the offset press is impacted
There are many reciprocating or intermittent motion structures in the structural composition of the offset press. These structures are susceptible to varying degrees of impact when the cams in the offset press are operating at acceleration. In particular, the impact generated by the clutch press structure will more seriously affect the operation of the offset cylinder, resulting in vibration of the drum.
3. Offset roller bearing wear
The wear condition of the roller bearing of the offset printing machine directly affects the amplitude of the vibration of the drum. The inconsistent stiffness of the support at both ends of the offset roller bearing causes the vibration of the drum to become more complicated during the printing process. The greater the clearance between the bearing and the journal, the more severe the wear of the bearing and the more intense the drum vibration.
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