There are three types of letterpress screen printing machines: flat press, round press and round press. Flat press letterpress printing machine is also called open rotary screen printer. It uses the common mechanism of screen printing and the application of mechanical transmission in printing machinery. The plate and embossing mechanism of the analytical version are flat. When working, the printing plate is in full contact with the embossing plate. The total pressure of the machine is compared at a time. Large, relatively long imprint time. This printing machine requires that the printing plate and the imprinted flat plate are flat, and the printing format is not large; the circular flattened relief printing machine, also known as a flatbed printing machine, is equipped with a flat plate for the printing plate, and the stamping mechanism is a circular cylinder . When the machine is working, the printing plate reciprocates, and the printing speed is limited, so the output is not high. The circular pressure relief printing machine is also called a rotary printing machine. The printing plate and the printing mechanism of the printing plate are round cylinders. When the machine is in operation, the impression cylinder moves with the printed matter and comes into contact with the plate cylinder. The impression cylinder and the plate cylinder continuously and rapidly rotate, so the productivity is high.
- Composition and working principle:
Chain conveying device: two of the chains of the chain conveying device adopt sleeve roller chains, one on each side of the printing machine. Two of the driving sprockets are installed at the end of the take-up roller, which is driven by the impression cylinder, and two driven sprockets are installed in front of the take-up table. 5~12 rows of gripper teeth rows are installed on the chain. The chain is controlled by a guide plate on the movement line so that it does not produce vibration and sag. When the gripper row wheel is turned to the opening cam block, the gripper row roller makes the gripper open and put paper under the action of the cam block. Adjust the position of the driven sprocket to adjust the tightness of the chain. The chain conveying device should reduce the length of the chain and the number of gripper rows under the condition that the structure sucks, and try to reduce the bending movement of the chain to prevent impact vibration. For special purposes, you can lengthen the paper collection chain. If you have a Hot Air Stenter, you need to install a drying device on the paper collection line. The length of the paper collection chain can reach more than 15m. The chain itself has the characteristics of speed reduction, which is conducive to accurate paper collection. The gripper is installed above the chain. On the circumference of the take-up cylinder, the gripper line speed is the same as that of the impression cylinder. The chain rotation radius is smaller than the gripper line rotation radius. The gripper line speed is higher than the chain line. Speed; when the chain moves from a circular motion to a linear motion, the running speed of the chain does not change, and the line speed of the gripper teeth is reduced from the linear speed of the impression cylinder to the running speed of the chain. Usually the speed is reduced by about 25%.