The influence of five parts of printing machinery on registration

Registration is to evaluate the quality of sheetfed offset printing machines is an important performance indicator, with many processes are directly linked. Therefore, ensuring the registration is an important guarantee for determining the yield of printed products, and how to solve the problem of inaccurate printing is also a topic of great concern to printing companies.

Paper feeder

Failure of the paper machine is a major factor in the inaccuracy of overprinting. In the printing process, once the paper feed is skewed, it is necessary to check the flexibility and coordination of the paper feed nozzle and the paper feed nozzle, and also check the pressure of the paper feed roller and the tightness of the paper feed belt. In addition, if the lifting amount of the paper stack lifting device does not match the thickness of the paper, the paper suction nozzle is unstable, and the intermittent paper feeding skew phenomenon occurs, which may cause the overprinting to be inaccurate. Therefore, when there is a problem with paper feeding, the above factors should be considered. This will not only avoid the problem of overprinting, but also ensure the service life of the paper feeder.

2. Pre-regulation

The front specified plane and the paperboard should be perpendicular, and the positioning surfaces of all the front gauges must be on the same straight line. The height of the front gauge tongue should be 3 sheets. Only after the front gauge is stabilized, the paper can reach the front gauge for positioning, otherwise the front gauge will disturb the paper, causing the paper to arrive early or late. If the paper arrives late, there is no paper stabilization time in the front gauge. Therefore, before the paper is completely covered by the paper, the front gauge has left, which can easily lead to inaccurate paper positioning, which greatly affects the registration and even Causes paper to be deformed or torn.

3. Side gauge

The gauge surface of the side gauge is perpendicular to the requirement of the front specified plane, and the height of the side gauge tongue is also preferably 3 sheets. The paper pressing force of the side gauge pulling ball is appropriate. The pulling distance is generally 5~8mm. If the distance is too small, it is not easy to pull the paper straight. If the distance is too large, the paper will not be pulled.

4. Hand paper plate

The transfer plate should be kept flat and free from problems such as bumps and burrs to prevent the paper from being blocked during operation.

5. Transfer mechanism

The paper feeding mechanism should be stationary for a period of time before the paper is picked up to eliminate the influence of the inertial impact of the paper feeding mechanism on the paper, and then the paper picking paper can be closed to achieve zero speed paper picking, and finally the paper conveying mechanism is accelerated to realize the operation with the drum. Speed ​​the paper. The position of the paper transfer mechanism to transfer the paper is generally called zero point. If the zero point is not accurately positioned, the paper picking teeth will be advanced or delayed, and the front edge of the paper is far away from the tooth pad. Under the action of the gripper, The edges of the paper are prone to deformation, which in turn causes misregistration. In addition, when the components of the transfer mechanism are worn out, the registration will be affected by the increase of the gap and the lowering of the positioning accuracy.

The above content is selected from the 11th issue of “ Printing Technology·Packaging and Decoration ” of Keyin Media in 2013. For more journal content, please pay attention to the journal channel, and click on the latest journal content to enter the electronic journal channel of Keyin.com.

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