Rotary printing machine because of printing speed, high production efficiency and is widely used in the production of large orders, by printing firms. However, the folding stability of the rotary printing press is affected by many factors such as the quality of the paper rewinding, the stability of the tension control system, the stability and standardization of the printing pressure, the stability of the tape conveying system, and the tension balance of the conveyor belt. Its control has always been a major difficulty. Here, the author will discuss how to use the water-wet folding method to improve the stability of the last fold of the product of the rotary printing machine's triangular folding system.
Reasons for folding errors caused by rotary presses
At present, the folding mode of the rotary printing press is divided into strip folding and triangular folding. The strip type folding is to cut the printed paper into strips (3 to 5 strips) in the radial direction by cutting cutters, and the strips after slitting are superposed by a 45° angle steering rod, and then rolled. The knife is cut and the folding roller is superposed. Finally, the chopping board folds to form a three-sided opening signature. The triangular plate folding application is most common. It is to bend the paper printed by the rotary printing machine through the triangular plate, and divide it by the center line (folding), then cut it by the paper cutter, fold the roll to form 8 open signatures, and pass the tape. Transfer 8 open posts to the machete station, chopper folding to form 16 open posts, as shown in Figure 1.
Figure 1 Schematic diagram of the triangular plate folding method This article focuses on the reasons for the accuracy of the chopper folding that affects the folding of the triangle. After the paper is folded by the triangle plate and the folding roller, the signature is thicker. If the paper is printed by double paper path, it is 16P. For example, the paper with a basis weight of 55g/m2 is 0.5mm thick, and the chopping board is folded. The page is prone to errors, the specific reasons are as follows.
(1) The high speed movement of the yarn belt makes it difficult to stably hold the signature and form a folding error, as shown in Fig. 2.
Figure 2: High speed movement of the yarn belt causes folding error (2) The non-linear motion chopper causes the signature to have a lateral movement tendency, forming a folding deviation. As shown in Fig. 3, the chopper movement track is a circular arc shape, the blade edge is subjected to the force of X and Y directions, the X-axis direction FX force causes the signature to have a lateral force, and the lateral force causes the signature to have a lateral movement tendency. Therefore, the movement of the signature to the chopper and the signature before entering the squeezing roller is a compound movement, which causes the signature to be unstable and forms a folding deviation.
Figure 3 Analysis of the force of the chopper blade (3) The yarn tension and frictional force are inconsistent, resulting in folding error. If the tension of the yarn on both sides of the paper is inconsistent with the friction between the signatures, it will lead to inconsistencies in the lateral movement resistance of the signatures when the signatures are folded, and eventually the skews are skewed, as shown in Fig. 4.
Figure 4 Inconsistent tension and friction of the tape leads to lateral movement of the signature Crossbody Bag,Crossbody Purse,Designer Crossbody Bags,Mcm Crossbody Bag
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