Causes of The Overall Movement of Corrugated Box Printing
The printing quality of corrugated box printing machine can usually be understood as two aspects: one is the clarity of printing, including consistent color depth, no adhesion of patterns, no ghosting, and no bottom leakage. On the other hand, the overprint accuracy of multi-color printing should generally be within ±1mm, and a good printing machine can reach within ±0.5mm or even ±0.3mm.
In fact, the corrugated box printing machine also has a very important printing quality index-the overall printing position, that is, the color registration of several colors is accurate, but they are all inconsistent with the cardboard reference edge distance, and the error is large. Because the quality index of general cartons is not strict, it is easy to be ignored by people. If the overall positioning error exceeds 3mm or 5mm, the problem is more serious.
Regardless of chain feeding or automatic paper feeding (backward paper or front edge paper feeding), the reference side of the overall printing position of the corrugated box printing machine is perpendicular to the direction of cardboard conveying, because the other direction (cardboard conveying direction) is not easy to produce The overall position (unless the cardboard runs obliquely). This article will analyze the reasons for the overall printing position of the automatic paper feeding printing machine with the paper push method.
The cardboard conveying of the automatic paper feeding printing machine is to push the bottom of the aligned cardboard forward to the upper and lower conveying rollers by pushing the cardboard, and then conveyed to the printing department by the upper and lower conveying rollers, and the automatic feeding is completed by repeating this Paper. Analyzing the conveying process of the cardboard can help us find the reason for the overall displacement of printing.
1. In the process of pushing the paper, the drive chain of the pushing board must not have a large accumulation gap.
The automatic paper feeding printing machine pushes the cardboard in a reciprocating linear motion. Most manufacturers use crank (slider 1 guide rod mechanism plus rocker slider mechanism. In order to make the mechanism light and wear-resistant, the slider of the crank slider guide rod mechanism is a bearing. Because the gap between the bearing and the two slides is too large The assembly will cause the uncertainty of the movement of the pushing cardboard, resulting in paper feeding errors and causing the overall printing position. So how to ensure that the bearing is purely rolling between the two slide plates of the guide rod without causing a large gap between the bearing and the two sliders is The essential.
The double bearing structure is adopted, no matter the bearing moves down or up along the slide plate, it can ensure the pure rolling of the bearing without gap between the two slide plates, so that the mechanism is light and wears little and can eliminate the gap. The connection between the guide rod and the rocker and the shaft is prone to loosening due to the alternating load, which is also the reason for the error of pushing the cardboard and paper due to the gap. The other mechanisms in the cardboard transmission chain drive the gears evenly, improve the processing precision of the gears (such as using gear grinding and honing), improve the center distance accuracy of each pair of gears (such as using a machining center to process wallboards), and reduce the accumulation of transmission Clearance, improve the accuracy of pushing the cardboard to push the paper, thereby reducing the overall movement of the cardboard printing.
2. Pushing the cardboard to push the cardboard into the upper and lower paper feed rollers is actually an instantaneous speed-up process in which the speed of the cardboard is increased from the linear speed of the cardboard pusher to the linear speed of the upper and lower paper feed rollers. The instantaneous linear velocity of the cardboard must be less than the linear velocity of the upper and lower paper feed rollers (otherwise, the cardboard will be bent and arched). And how much smaller, the ratio matching relationship between the two speeds is very important. It directly affects whether the cardboard will slip at the moment of speed up, and whether the paper feeding is accurate, thus affecting the overall printing position. And this is exactly what the printing machine manufacturer can't notice.
When the speed of the main machine is constant, the linear speed of the upper and lower paper feed rollers is a fixed value, but the linear speed of the cardboard is a variable, from zero at the rear limit position to the maximum in the forward direction to zero at the front limit position, from the front limit position to zero. From zero to the reverse maximum to zero at the rear limit position, forming a cycle. Of course, factors that affect the overall position of cardboard printing include the curvature of the cardboard, the surface roughness of the cardboard, the moisture content of the cardboard, and whether the gap between the upper and lower paper feed rollers of the corrugated box printing machine is appropriate, etc., but the factors of equipment accessories are mainly manifested in the above two aspects.
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