Diagonal adjustment of printed products
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When the printed pattern has been registered on one side and the other end is inaccurate and inclined, then diagonal adjustment is required. In the actual imposition, printing, and loading, it is difficult to make the PS version of each group absolutely accurate, and the position is not oblique at all. So diagonal adjustment is necessary.
The diagonal adjustment of Heidelberg is the position of the head (operating surface) of the micro-moving plate by the eccentric sleeve, so that the PS plate is inclined or rotated relative to the paper, and the position of the PS plate is pulled.
The mechanism principle of the Speedmaster class is the same. The CD102 is taken as an example to illustrate the diagonal adjustment. As shown in Figure 1, the entire mechanism is on the outside of the operating panel. The data is input from the operation panel to control the rotation of the servo motor. The position feedback signal device is in the servo motor and is sent by the servo motor itself, and is transmitted to the telescopic adjustment rod through a pair of transmission gears. The telescopic adjustment rod is threaded, and the telescopic pull block moves up and down during the rotation. The telescopic pull block of this place 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 driven to rotate, and at this time, a slight movement occurs at one end of the plate cylinder, thereby achieving the purpose of diagonal adjustment.
The operating surface of the plate cylinder has a diagonal eccentric sleeve, which is a needle roller bearing inside and outside, so its rotation is very flexible. The axial direction is fixed and cannot be moved 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. There are two problems at this point: 1. The pressure between the plate cylinder and the inking roller will change; 2. The pressure between the plate cylinder and the blanket cylinder will vary.
The diagonal adjustment can move a small distance, a total of only 0.3mm, so the distance of the plate cylinder lateral movement is not large, also about 0.3mm. The maximum rotation distance of the diagonal eccentric outer ring is as long as 2 × 5 = 10 mm, which satisfies the requirements.
Friends who have opened the printing press must know that if there is a slight change in the rubber lining, it will not affect the quality of printing within a few microns; if the pressure of the inking roller changes, especially if the two sides are asymmetrical, most of the printed products are waste. This is because the plate cylinder moves laterally, that is, it moves approximately in the circumferential direction of the blanket cylinder. Therefore, although the plate cylinder moves at one end, the pressure change between them is negligible relative to the blanket cylinder; The smuggling of the inking roller is much smaller than that of the blanket cylinder. When there is a slight movement of the printing cylinder end (operating surface), the pressure change between the inking roller and the plate cylinder is not so small as the pressure change between the rubber blanket cylinder and the plate cylinder. At the same time, the inking roller is dispersed on the plate cylinder. When the plate cylinder moves laterally, the respective inking roller moves together with the plate cylinder, which can simplify the problem and solve the pressure change between the plate cylinder and the different inking rollers.
The graying part is the ink path linkage mechanism when the diagonal adjustment is performed. There are two sets of mechanisms to control the front and back of the ink path. The two sets of mechanisms are on the outside of the operating wall panel, one on the diagonal eccentric sleeve, the other end is transmitted to the ink path bracket through the mechanism, and the other end is transmitted to the ink path bracket through the mechanism. The specific structure, when the diagonal eccentric sleeve rotates, the operating surface 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 a series of transmission mechanisms in the middle, and finally The adjustment movement rod is moved axially, so that the plate-fed roller is weighed together with the plate cylinder.
Adjusting the axial movement of the moving rod, how can it be moved by the plate roller? Since the end of the adjustment moving rod close to the eccentric straight tooth is conical, its axial movement changes the angle of rotation of the inking roller holder, and finally the pressure of the printing plate against the printing plate is changed. The diagonal eccentric sleeve rotates, and the plate cylinder moves approximately laterally on the side of the operation surface. What is the change in the pressure of the blanket cylinder?
Schematic diagram of the rotation of the diagonal eccentric sleeve and the pressure change of the plate cylinder relative to the blanket cylinder. For the diagonal eccentric sleeve transmission, the inner circle running track is the thin circle circle with the smallest radius in the figure, and the 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 blanket cylinder, the trajectory of the movement of the plate cylinder is also the trajectory of the inner circle of the diagonal eccentric sleeve, and also the trajectory of the inner circle of the diagonal eccentric sleeve. It must be on the dotted circle with the largest radius. The circle is centered on the center of the blanket cylinder, and the radius of the blanket cylinder + the radius of the plate cylinder is the radius.
From the two movement trajectories mentioned above, the thin line circle and the dashed line circle know that only when they overlap each other, the pressure between the plate cylinder and the blanket cylinder does not change, and the coincidence is only one point, that is, the highest point. Fortunately, the range of eccentric movement is very small, and the eccentric outer ring has a large moving distance of only 10 mm at any time and place, so the two trajectories on both sides of the coincident point are very close, which can meet the requirements of constant pressure between the rollers. It can be seen from the figure that the upper eccentricity of the diagonal eccentric sleeve makes the two movement trajectories thin and the dashed circle close, so the Heidelberg machines adopt the upper eccentricity.
In order to achieve the constant pressure requirement, Heidelberg adopts the contact operation of the roller, that is, the roller on both sides of the plate cylinder and the blanket cylinder is in contact with each other. In normal operation, we should keep the roller as clean as possible, which is the machine precision. Guarantee.
Points to note when installing and debugging
1. The specific structure of the diagonal adjustment of different types of machines is different, but basically it is servo drive. After a series of mechanisms, the diagonal eccentric sleeve is finally rotated, and the operation surface of the plate cylinder is moved. The servo motor uses a DC motor with a brush 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. In general, servo motors are used for position adjustment and there is a problem of zero positioning. Different machines have different specific operating methods, but one thing is the same; 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 to make it on the console The display shows zero and then the entire set of mechanisms is fixed.
2. Eccentric bolts, in general, including changing the servo motor, disassembling the diagonal adjustment mechanism, etc., do not loosen it, because it has been adjusted at the factory. If it is not moving, pay attention to the parallelism between the plate cylinder and the blanket cylinder. Our daily adjustment is to press the ink bar to see the width is the most convenient.
3. The accuracy requirement of the whole set of diagonal adjustment mechanism is very high, especially the requirement of the ink path linkage mechanism is higher, so the flexibility and precision requirements of each mechanism must be paid attention to during installation, such as the matching gap can not be too large, etc. Measure to see if the design requirements are met.
Points of attention when designing machinery
1. The eccentricity of the diagonal eccentric sleeve is above, and the positions of the two motion trajectories (thin line circle and dashed circle) are relatively close. If the thin circle moves up a little further, then their position is closer, so in the design, the compensation of the two motion trajectories can be compensated for by the appropriate compensation.
2. The maximum distance of the diagonal eccentric outer ring rotation is 10mm, and the two sets of ink path linkage mechanisms move from the final transmission to the axial movement. There are many mechanisms in the middle, and other mechanisms are avoided, so the mechanism is reasonable. The accuracy of the parts and the location of the installation are very important, otherwise they will be abandoned.
3. As can be seen from the operation panel, there are four buttons for diagonal adjustment. In fact, only one servo motor is driving, and the plate cylinder is moving at one end. Therefore, in the electrical design, it is necessary to compensate for different diagonal adjustments by circumferential adjustment at the same time. . It is now controlled by industrial computer or PLC, so it can be done relatively easily.
design concept
Institutional unity. When multiple agencies are connected to each other, it is best to pass the power from a motive force. All of us have personal experience in the actual operation. The slight change of the pressure of the ink roller has a great influence on the ink volume and the ink balance. Therefore, adjusting the pressure of the ink roller is a very important skill. The diagonal adjustment makes one end of the plate cylinder move, which must change the pressure of the ink roller. Heidelberg handles this changing pressure and directly starts from the power of moving the plate cylinder, which can make the movement and pressure of the plate cylinder change very well. Coordination, uniform pace, in practical applications, reduce the possibility of error and increase stability. The difficulty is that the amount of pressure change between the ink roller and the plate cylinder is small, and the diagonal eccentric sleeve is rotated, and finally changes to a slight movement, so the mechanism is complicated and the manufacturing precision is high.