When one side of the printed pattern has been registered, the other side is misaligned and oblique, then diagonal adjustment is required. In the actual imposition, printing, and layout, it is difficult to make the PS versions of each group absolutely accurate, and the position is not oblique at all. So diagonal adjustment is necessary.
Heidelberg's diagonal adjustment is to move the position of the head (operation surface) of the micro version plate through an eccentric sleeve, so that the PS version has a tilting or rotating action relative to the paper to straighten the position of the PS version.
figure 1
The mechanism principles of Speedmaster are the same, and CD102 is still used as an example to illustrate the diagonal adjustment. As shown in Fig. 1, the whole mechanism is outside the operation panel. Input data from the operation panel to control the rotation of the servo motor. The position feedback signal device is in the servo motor, which is sent out by the servo motor itself, and is transmitted to the telescopic adjusting rod through a pair of transmission gears. There are threads on the telescopic adjustment rod, which drives the telescopic pull block to move up and down during the rotation process. The telescopic pull block here can only move and swing, and cannot rotate with the telescopic adjustment rod. When the telescopic pull block moves up and down, the diagonal eccentric sleeve is rotated, and a small amount of movement will occur at the end of the plate cylinder, so as to achieve the purpose of diagonal adjustment.
figure 2
It can be seen from FIG. 2 that the operating surface of the printing plate cylinder is provided with a diagonal eccentric sleeve, and the inside and outside are needle roller bearings, so its rotation is very flexible. The axial direction is fixed and cannot move casually. With the rotation of the diagonal eccentric sleeve, the plate cylinder is driven to move laterally at one end of the operation surface, thereby achieving diagonal adjustment. At this time, there will be two problems: 1. The pressure between the plate cylinder and the inking roller will change; 2. The pressure between the plate cylinder and the rubber cylinder will change.
The distance that the diagonal adjustment can move is very small, only a total of 0.3mm, so the distance of the lateral movement of the plate cylinder is not large, also about 0.3mm. As shown in Figure 3, the maximum turning distance of the outer ring of the diagonal eccentric sleeve is only 2 × 5 = 10mm, which meets the requirements.
image 3
Friends who have run a printing machine must know that if there is a slight change in the rubber bag liner, it will not affect the quality of the printing within a few microns; if the pressure of the inking roller changes, especially the asymmetry on both sides, most of the printed products are waste products. This is because the plate cylinder moves laterally, that is, approximately along the circumferential direction of the rubber cylinder, so although the plate cylinder moves at one end, compared with the rubber cylinder, the pressure change between them is minimal and can be ignored; and The smuggling of the inking roller is much smaller than that of the rubber cylinder. When there is a slight movement on one end (operation surface) of the plate cylinder, the pressure change between the inking roller and the plate cylinder is not as small as the pressure change between the rubber cylinder and the plate cylinder. At the same time, the inking rollers are scattered on the plate cylinder. When the plate cylinder moves laterally, each inking roller moves with the plate cylinder, which can simplify the problem and solve the pressure change between the plate cylinder and different inking rollers. .
Figure 4
As shown in Fig. 4, the grayed-out part is the ink path interlocking mechanism during diagonal adjustment. There are two sets of mechanisms to control the two parts of the ink path. The two sets of mechanisms are on the outside of the operating surface wall panel, one end is on the diagonal eccentric sleeve, the other end is transmitted to the ink path support through the mechanism, and the other end is transmitted to the ink path support through the mechanism. The specific structure is shown in Figure 5. When the diagonal eccentric sleeve rotates, the operating surface end of the plate cylinder moves approximately laterally to achieve the purpose of diagonal adjustment. At this time, the diagonal eccentric sleeve drives the push-pull rod to push or pull through the middle one. The series transmission mechanism finally moves the adjustment moving rod axially, so that the plate ink roller and the plate cylinder are weighed together.
Figure 5
How to adjust the moving rod to move axially? Because the end of the adjustment moving rod close to the eccentric straight tooth is conical, its axial movement changes the angle of the ink roller holder rotation, and finally changes the pressure of the printing ink roller against the printing plate. When the diagonal eccentric sleeve rotates and the plate cylinder moves approximately laterally on the operation surface side, how does the pressure on the rubber cylinder change?
Figure 6 is a schematic diagram of the structure of the pressure change of the plate cylinder relative to the rubber cylinder when the diagonal eccentric sleeve rotates. For diagonal eccentric sleeve transmission, the inner circle running track is a thin line circle with the smallest radius in the figure, and its radius is the eccentric distance of the diagonal eccentric sleeve.
When the diagonal eccentric sleeve rotates, in order to keep the pressure of the plate cylinder relative to the rubber cylinder unchanged, the trajectory of the plate cylinder movement is also the trajectory of the inner circle of the diagonal eccentric sleeve and the trajectory of the inner circle of the diagonal eccentric sleeve , Must be on the dotted circle with the largest radius in Figure 6, this circle takes the center of the rubber cylinder as the center and the radius of the rubber cylinder + plate cylinder radius as the radius.
From the above mentioned two trajectories of thin lines and dashed circles: only when they overlap each other can the pressure between the plate cylinder and the rubber cylinder not change, and there is only one overlap, which is the highest point. Fortunately, the range of eccentric movement is very small. The large movement distance of the outer ring of the eccentric sleeve is only 10mm at any time, so the two tracks on both sides of the coincidence point are very close, which can meet the requirement of constant pressure between the rollers. It can be seen from the figure that the use of the upper eccentricity for the diagonal eccentric sleeve can make the thin line circle and the dashed circle of the two trajectories closer, so the Heidelberg machine uses the upper eccentricity.
In order to better meet the requirements of constant pressure, Heidelberg uses roller pillow contact operation, that is, the roller pillows on both sides of the plate cylinder and the rubber roller are in contact with each other. We usually try to keep the roller pillow clean during operation. That is the accuracy of the machine. Guarantee.
Points for attention during installation and commissioning
1. The specific structure of the diagonal adjustment of different models of machines is different, but they are basically servo driven. After a series of mechanisms, the diagonal eccentric sleeve is finally rotated and the operating surface end of the plate cylinder moves. The servo motor uses a brushed DC motor and comes with a potentiometer. The DC voltage of the motor is 24VDC, the voltage of the potentiometer is 10VDC, and the resistance is 10kΩ. Under normal circumstances, the servo motor is used for position adjustment, there is a problem of zero positioning. Different machines have different specific operation methods, but one thing is the same; that is, first adjust the zero position of the machine, then rotate the potentiometer to make it in the middle position, install the potentiometer and servo motor so that it is on the operating table The upper display shows zero, and then fix the entire mechanism.
Image 6
2. As shown in Figure 3, 6 in the figure is an eccentric bolt. Under normal circumstances, including changing the servo motor, removing the diagonal adjustment mechanism, etc., do not loosen it, because it has been adjusted at the factory. If you have to, you must pay attention to the parallelism between the plate cylinder and the rubber cylinder. We adjust daily to press the ink bar to see its width is the most convenient.
3. The accuracy requirements of the entire set of diagonal adjustment mechanisms are very high, especially the ink-linkage linkage mechanisms are more demanding, so you must pay attention to the flexibility and accuracy requirements of each mechanism during installation, such as the cooperation clearance cannot be too large, etc., through the data Measure to see if it meets the design requirements.
Points for attention in mechanical design
1. As can be seen from Figure 6, the eccentricity of the diagonal eccentric sleeve is above, and the positions of the two motion traces (thin line circle and dashed circle) are relatively close. If the thin line circles move up a little bit, then their positions are closer, so in the design, proper compensation can be used to make up for the shortcomings of the large difference in the radius of the two trajectories.
2. As shown in Figure 4, the maximum distance of the rotation of the outer ring of the diagonal eccentric sleeve is 10mm, and the two sets of ink path linkage mechanisms, from the final transmission of the rotation to the axial movement, there are many mechanisms used in the middle, and others must be avoided Mechanism, so the reasonable use of the mechanism, the accuracy of the parts and the location of the installation are very important, otherwise the previous efforts will be abandoned.
3. It can be seen from the operation panel that there are four buttons for diagonal adjustment, but in fact only one servo motor is driving, and the plate cylinder is moving at one end, so in electrical design, it is necessary to compensate for different diagonal adjustments through circumferential adjustment at the same time. . Now they are controlled by industrial computers or PLC, so it can be done relatively easily.
The design concept introduced in this article
Organizational unity. When multiple agencies are in contact with each other, it is best to transfer power from a prime mover. We all have hands-on experience in actual operation. A slight change in the pressure of the ink roller has a great influence on the amount of ink and the balance of water and ink, so adjusting the pressure of the ink roller is a very important skill. Diagonal adjustment moves one end of the plate cylinder, which must cause a change in the pressure of the ink roller. Heidelberg handles this changed pressure and starts directly from the power of moving the plate cylinder, which can make the movement of the plate cylinder and the pressure change very good. The coordination effect of the program is unified, and in practical applications, it reduces the possibility of errors and increases stability. The difficulty is: the amount of pressure change between the ink roller and the plate cylinder is very small, and the diagonal eccentric sleeve rotates, and finally changes to a small amount of movement, so the mechanism is complicated and the manufacturing accuracy is high.
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