The principle and components of roll paper offset printing machine

The principle and components of roll paper offset printing machine

The working principle of roll paper offset printing machine is basically the same as that of single sheet paper offset printing machine, the difference is that roll paper offset printing machine is a printing machine that continuously supplies paper in the form of paper rolls to complete printing and folding processes. It is a combination of modern printing and post press machinery, characterized by high efficiency, good print quality, wide adaptability, and good economic benefits. It generally consists of a paper feeding device, a printing device, a drying and cooling device, a folding device, and a control mechanism. Although there are various structures of roll paper offset printing machines, the composition of each type of machine is basically the same, mainly including two types: stacked arrangement and horizontal arrangement. Commercial use is mostly arranged horizontally, while newspaper use is mostly arranged in a layered manner, consisting of the following parts

(1) Paper feeder

There are two forms of automatic paper feeding machines: zero speed automatic paper feeding machines and speed controlled automatic paper feeding machines. Generally, commercial printing roll paper offset printing machines use zero speed automatic paper feeding machines, while most news printing roll paper offset printing machines use high-speed automatic paper feeding machines, which mostly rotate two or three paper rolls to exchange paper. They are suitable for high-speed newspaper printing. The paper feeding mechanism is also commonly known as the secondary tension control mechanism, which is a unique part of commercial printing roll paper offset printing machines. In conjunction with zero speed automatic paper feeding machines, it controls the tension of the paper tape and lays the foundation for accurate overprinting.

(2) Printing unit

The printing units of the roll paper offset printing press are organic and satellite based. The arrangement of rollers includes three drum type, four drum type (also known as B-B type), five drum type, six drum type, seven drum type, etc. BB type printing unit is the most common type, which is divided into vertical BB type and horizontal B-B type. Each printing unit is standardized, and the number of printing units can be increased or decreased as needed to form various forms of roll paper offset printing machines. In recent years, roll paper offset printing machines have mostly adopted tower shaped vertical BB type printing units. Figure 2-5 shows the horizontal BB printing unit and the vertical BB printing unit, respectively

(3) Drying and cooling device

The general roll paper offset printing machine adopts a drying box drying device. When using thermosetting ink for multi-color printing, it needs to be dried to ensure that the ink dries quickly during high-speed printing. Most drying boxes are hot air drying boxes. There is a cooling mechanism behind the drying box, because the paper tape is heated inside the drying box. Although the ink is dried, the temperature of the paper tape rises, and the ink must be further solidified and dried through the cooling mechanism. At the same time, the temperature of the high-temperature paper tape is lowered, otherwise it will bring many problems when folding or cutting into single sheets of paper. Most cooling mechanisms consist of three or four cooling rollers, which are filled with cold water to cool the paper tape. Another function of the cooling roller is to control the tension of the paper tape. After drying, the gloss of ink is not as good as that of naturally dried ink. In order to achieve good glossiness of printed materials, a polishing device should be installed when high printing quality is required. Special printing technology (second edition) requires the printed paper tape to be first cut into the folded part according to requirements, and then folded into various sizes as needed. The folding machine also

The principle and components of roll paper offset printing machine

The principle and components of roll paper offset printing machine