Analysis of the Causes of Overall Positioning of Carton Printing

The printing quality of carton printers is generally understood as two aspects. On the one hand is the clarity of printing, including the consistent color depth, pattern no adhesion, no ghosting, no bottom leakage. On the other hand, the overprint accuracy of multicolor printing should generally be within ±1mm, and a good printing press can be within ±0.5mm or even ±0.3mm.

In fact, the printing press also has a very important printing quality indicator - the overall printing position, that is, several colors of color registration is accurate, but they are inconsistent with the paperboard reference edge spacing, the error is larger. Due to the lax requirement of the general quality of the carton box, it is easily overlooked. If the overall walking error exceeds 3mm or 5mm, the problem is more serious.

Regardless of the chain feed or automatic feed (post feed or leading feed), the reference edge of the overall print position is perpendicular to the paper board transport direction, and the whole direction (paper feed direction) is less likely to generate an overall pass (unless The cardboard runs obliquely). This article will analyze the reason why the post-push paper automatic printing press prints the overall position.

In the automatic paper feeding printing machine, the paperboard is transported by pushing the paperboard to push the bottom sheet of the paperboard to the upper and lower conveying rollers, and is conveyed by the upper and lower conveying rollers forward to the printing department. paper. Analyzing the transport process of the cardboard can help us find the reason for the overall walk.

1. In the process of pushing paper, the drive chain of the push paper board must not have a large accumulation gap.

The automatic paper feed printing machine pushes the paperboard in a reciprocating linear motion. The majority of manufacturers use cranks (slider 1 guide mechanism plus rocker slider mechanism. In order to make the mechanism light and wear small, the slider of the crank slider guide mechanism is the bearing. The clearance between the bearing and the two slide plates is too large. The conference caused uncertainty in the movement of the paperboard, resulting in paper feeding error, which caused the printing to walk in its entirety.Therefore, how to ensure the bearing to make pure rolling between the two slides of the guide rod without making the bearings have large clearance with the two slides is The essential.

With the double bearing structure, whether the bearing moves down or moves up along the slide plate, the pure rolling without clearance between the two slide plates can be ensured, so that the mechanism can not only be lightly worn but also can eliminate the gap.

The connection between the guide rod and the rocker and the shaft is easy to be loose due to the alternating load, and it is also the reason that the clearance is caused to push the paperboard to push paper. Pushing the other gears in the cardboard drive chain to even gear transmission to improve the fineness of the gears (such as grinding teeth and dents) and improve the center-to-center accuracy of each pair of gears (such as machining center panels with a machining center) to reduce the accumulation of transmission Clearance improves the accuracy of push-pull paper pushing, thereby reducing the overall walking position of cardboard printing.

2. The moment when the cardboard is pushed into the upper and lower feed rollers, it is actually an instantaneous speed increase process in which the paperboard speed is increased from the linear speed of the paperboard to the speed of the upper and lower paper feed rollers.

The instantaneous line speed of the paperboard must be less than the upper and lower paper feed roller speeds (otherwise, the paperboard will be bowed). The smaller the number, the ratio of the two speeds matching relationship is very important. Directly affect the speed of the cardboard to slip, whether the paper is accurate, thus affecting the overall position of the printing. This is exactly what the press manufacturer can't notice.

When the speed of the main machine is constant, the line speed of the upper and lower feed rollers is a fixed value, while the linear speed of the push plate is a variable, from the zero of the rear limit position to the maximum of the front limit position of the front limit position of zero. Zero to the reverse maximum to the rear zero position, forming a loop.

Of course, the factors affecting the overall position of cardboard printing include the curvature of the paperboard, the surface roughness of the paperboard, the moisture content of the paperboard, and whether the gap between the upper and lower paper feed rollers is appropriate, but the factors of the equipment mainly manifest in the above two aspects.