Analysis of Selection of Gravure Printing Machine from the Perspective of Printing Technology (III)

The installation position should be reserved on each color group. When the position of the printing color group is changed, the electrostatic ink transfer device can switch between the color groups. Now, the function of the domestic electrostatic transfer ink device has been very satisfactory, and it can also be exchanged with foreign devices, the price is only about 1/5 of imported devices.
8, no shaft drive mode

The gravure printing machine generally adopts the universal shaft drive, but the linear speed of the printing plate cylinder in the drive changes greatly, and even affects the overprint accuracy. In the past two years, the non-shaft drive technology has developed rapidly. The high-end gravure printing press basically adopts the non-shaft drive, which greatly improves the accuracy of multi-color gravure printing machine transmission and overprinting, and can fundamentally realize the transmission control of single units. , is the main method of multi-color unit transmission in the future. Now more non-shaft transmission mode is used. Each unit is directly driven by a DC motor, and then centralized control is implemented on the basis of the control of the subunits. For example, the speed change of a single unit can be achieved, and the unused monochrome can be controlled. The unit is shut down to reduce wear and energy consumption, and it is also critical to improve the accuracy of overprinting at high speeds.

9, tension control mode

Previously the whole gravure press production line used only one tension control system, placed behind the last printing unit, and adjusted the tension of the entire production line by controlling the relative speed difference between the feed speed and the paper exit speed. The range of tension changes is relatively large, generally more than 50 Newtons, plus the adjustment of the position of the plate cylinder to achieve overprinting, the tension change between the color groups is greater, so the stability of overprint between the colors is also very poor. Now basically changed to the tension control of the color separation group, and the tension control of the entire production line is distributed to various color groups. The tension variation range is greatly reduced. In general, the tension change of each color group is about 5 Newtons. Accurate overprinting laid a good foundation. In the entire production line, the tension value of each color group should be consistent as much as possible. Generally, according to the difference of the paper, a fixed value between 200 and 300 newtons should be selected, so that the tension of the paper during the printing process is even and to a certain extent Deformed paper.

10, online quality monitoring

On-line quality monitoring can be divided into three levels: on-line partial overprint monitoring, on-line product pattern monitoring and alerting, on-line product patterning and ink color monitoring. On-line local overprint monitoring is to partially overprint a crosshair or a key fine pattern on a printing surface, pass a digital camera, and then perform an enlargement process, which is generally enlarged by 15 to 20 times and synchronously tracked. The operator can monitor the overprint effect of the entire printing format and find problems in a timely manner. On-line local overprint monitoring is the most basic and necessary on-line quality monitoring mode. Generally, one or two parts are installed. The price of a system is about 50,000 to 80,000 yuan. On-line product pattern monitoring and alarm is to enter the sample pattern into the computer, the online print is also scanned, and compare the print pattern position and sample pattern position changes, if there is a change, the alarm, remind the operator to adjust and online The product is marked or rejected. This method is now used more often. The price of a system is about 800,000 yuan. On-line product pattern and ink monitoring is based on the second online quality monitoring method. It adds automatic adjustment of equipment and control of ink color. This method is used very rarely, mainly in the banknote printing industry, because monitoring The cost of equipment is relatively high.