Brief analysis of the structure of the hottest CTP

2022-07-31
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A brief analysis of the structure of CTP plate making machine

offset CTP plate making machines are numerous. The total capital investment of the country with "one belt and one road" will reach more than US $3.26 trillion, but the core structure of the plate making machine is only platform type, inner drum type and outer drum type. Each of the three structures has its own characteristics. Platform structure

just as the name of this structure is defined, this plate making machine has a platform type plate carrier. The plate loading mechanism of the platform CTP plate making machine has a simple structure, and the printing plate can be easily and accurately clamped to the corresponding position. In the exposure system of most platform plate making machines, there is only one beam of exposure laser. The laser deflects through a rotating prism and hits the plate surface, as shown in Figure 1

in some platform type plate making machine systems, the prism is always suspended above the printing plate, does not move horizontally, but only rotates around the main axis through its center, so that the laser can deflect back and forth in the longitudinal direction. After each exposure unit is completed, the plate carrier moves one unit horizontally, so as to complete the exposure of the whole printing plate. In another type of platform CTP plate making machine structure, the plate loading platform always remains stationary. While the reflecting prism rotates, it moves laterally along the lead screw. Its effect is the same as that of the plate loading platform. Finally, the exposure of the whole printing plate can be completed

in the process of exposure imaging, since the reflective prism is used to reflect the laser beam onto the printing plate, rather than the laser transmitter to expose the printing plate from one end to the other, the length of the laser path projected onto the printing plate varies with the rotation angle of the prism. When the laser is vertically projected onto the printing plate, the optical path is the shortest, and when it is projected onto the edge part, the optical path is the longest. In order to ensure that the size and shape of the laser point will not change, the imaging laser needs to pass through a series of special prisms to compensate for the change of the optical path

the platform type plate making machine has efficient plate loading speed and production speed. However, due to the limitation of imaging technology, the width of the image and text area on the plate is limited. Most of the platform type plate making machines are used on CTP plates that are sensitive to visible light. Inner drum structure

the inner drum of the inner drum plate making machine is inward concave, which is very similar to the letter "C". The printing plate is loaded into the inner drum, curled and attached to the inner wall of the imaging drum. The vacuum caused by the air extraction device will be fixed at the imaging position. A single laser beam is used to expose and image on the printing plate. The laser is first reflected on a high-speed rotating prism, which deflects the projected excitation light vertically onto the printing plate of the inner drum. As the prism moves from one end to the other along the internal lead screw, Further, the exposure of the entire printing plate is completed. During the exposure process, the inner drum remains still. The image resolution on the printing plate is changed by changing the diameter of the laser beam. The inner drum structure is shown in Figure 2

when making plates on the inner drum plate making machine, necessary restrictions must be made on the rotation speed of the deflection prism. This is because the imaging material of the thermal CTP plate has a slow reaction speed and requires high energy, which means that the plate making speed will inevitably be reduced

external drum type plate making machine

is opposite to the internal drum type. In the external drum type plate making machine system, the printing plate is fixed on the outside of the imaging drum. With the rotation of the imaging drum, the laser head with multiple laser beams moves in a radial direction parallel to the drum, so as to complete the imaging of the entire printing plate

the external drum type plate making system does not need any deflection prism, and allows the imaging laser head to be closer to the imaging drum, which is very beneficial to thermal imaging, because the closer the distance is, the higher the laser energy is. As shown in Figure 3, the external drum type plate making machine

since a printing plate with non negligible quality is wrapped on the outside of the imaging drum, the centrifugal force generated may cause the high-speed rotating imaging drum to lose balance. Therefore, most external drum imaging systems need additional anti unbalance measures to compensate for this defect, so as to ensure that the rotation speed of the imaging drum is accurate and consistent, and the laser intensity hitting the printing plate will be consistent, thus ensuring the optimal imaging quality

some external drum CTP plate making machines are not equipped with an anti unbalance system. The rotation speed of the imaging drum of this kind of plate making machine is slow, and the centrifugal force can be ignored. In this case, Wanhua Ningbo High Performance Materials Research Institute will be mainly engaged in new polyurethane materials, special isocyanates, environmental protection surface materials The research and development of high-performance modified materials and other series and the industrialization of imaging laser exposure imaging ensure that the overall plate making speed is not slow. However, another common problem with the use of multiple lasers is that the laser spot formed by the first laser imaging is adjacent to the light spot of the last laser in the previous cycle. If the energy of the two lasers is not exactly the same, or the two laser spots are slightly overlapped, it is possible to form obvious traces on the final prints. Therefore, periodic detection and adjustment are very necessary for the multiple imaging laser head system. If it is necessary to change the resolution of the picture and text, the external drum imaging system cannot change the diameter of the laser beam, but can achieve this purpose by adjusting the distance between multiple laser beams

information source: printing quality and standardization

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