China's printing industry has long referred to lithography as offset printing. In fact, it originated from the lithographic printing machine is an indirect printing method. After the printing plate produces the print, it does not directly contact the paper to transfer the ink printing, but uses a blanket to install On the blanket cylinder, as the medium for transferring printing ink in the middle, the printing ink on the printing plate is picked up, and then transferred (written) on the printed paper medium, so the blanket plays a role in the lithographic printing machine The extremely important role, therefore, does not call the layout as lithography, but instead renames its indirect printing blanket media as offset printing, but there are very few letterpress printing that must be indirectly printed on the hard material surface, and also use the blanket to transfer Whether the pattern is still called offset printing is unknown. Before the 1960s, all blankets used natural rubber as the material to transfer the printed blankets. However, since the 1950s, because natural plant-based linseed oil was replaced by petrochemical mordant ink, the original natural rubber was obviously already intolerant. Due to the invasion of petrochemical solvents and resins, abnormal swelling and bumping occurred. Therefore, in the 1960s, the surface of the blanket had to use synthetic rubber. The material of the ink roller and water roller was also changed to synthetic rubber. DuPont invested more than 1 billion US dollars Completion of synthetic rubber research is only ten years after World War II. However, the blankets up to this point are all solid and do not have the structure of bubble sponge compression, and the pressure generated by them will rise sharply as the speed of the printer becomes higher. At that time, there was a very different theory. The earliest school believed that both the printing plate and the pressure roller (plus printing paper) were hard, so the surface of the rubber roller should be raised so that the diameter was greater than the diameter of the two hard rollers. The same diameter is running, but in 1937, the American Miller Miller Printing Company found that the round length of the hardware cylinder imprinting is a fixed length of diameter × π, but the soft surface of the rubber cylinder rolls a circle equal to the diameter × π plus The elasticity and pressure coefficient mean that even if the rubber cylinder is under the same diameter, it is imprinted with the plate cylinder and the pressure cylinder, the rotation length is greater than the two hard cylinders, and the cylinder diameter method intentionally increases the compressed rubber cylinder, so The length of the rubber roller is long and the running speed is fast, so the rubber cloth and the printing plate have unnecessary friction, so the plate roller pad is changed to 0.1 ~ 0.15mm above the gear joint circumference, and the rubber cylinder pad is made of rubber The same height around the cloth section to maintain the same speed of surface imprinting and printing ink transfer during imprinting. This method of roller pad height called rolling length method has been used to this day. But at the time, it was also found that the rubber cloth on the rubber cylinder, when pressed by the plate cylinder, would protrude forward and backward to counteract the pressure. The effect of this flange is like a rubber ink roller. Use a wire to tighten the wire It must be submerged in the rubber, and the fallen rubber will bulge on both sides. This effect is the same as the flange caused by the pressure mentioned above. In order to solve the printing marks and dots produced by the flange, sometimes there will be drag marks and ghosting. Therefore, when the rubber factory manufactures the blanket, there are four interwoven textile yarn layers under the blanket surface. Between the layers, a sponge layer of bubbles is sandwiched like a sandwich, and the hardness of the surface rubber layer is also slightly increased to compensate for the sponge layer's effect of softening the depression, but this sponge layer is independent of each bubble. It has greater resistance to compression and can provide better rebound strength when decompressing. If the bubble holes are connected through each other, once the sponge layer overflows with compressed air, on the contrary, the supporting force is very weak after decompression, and only the elastic force of the rubber structure is doing a soft rebound. Therefore, it is very important to seal the non-connected sponge bubble layer in order to provide support and recovery elasticity. Then this layer is an average of about 0.4mm sponge air cushion layer, which provides the blanket directly under the pressure of the sponge air cushion layer to obtain downward compression space, without having to move forward and backward to create a flange, causing Unnecessary creeping, to avoid the phenomenon of smearing to superimposing the quality of the printed patterns. At the same time, because of the compression, there will be no rolling length of the elastomer, and the height of the pad of the blanket must be increased to maintain the concept of close to the same diameter method. In turn, under the extra elasticity provided by the air-cushion blanket, it is no longer possible to make the traditional blanket completely inelastic. The plastic liner or hard liner paper under the blanket is called the effect of the hard liner because the air cushion layer Provide additional flexibility. Later, some manufacturers moved the sponge layer of the air cushion blanket down one layer, close to the way between the third and fourth layers of the roller body. In addition, there was also an upward movement of the air cushion layer under the rubber surface layer, directly attached to the surface layer of the rubber cloth Below, provide greater flexibility to absorb pressure. But around 2005, an ultra-thick air cushion blanket was developed. The bubble sponge layer that absorbed the printing pressure was increased from 0.4mm to 0.8 ~ 1.4mm, especially the blanket with a total thickness of 2.4mm. It can accommodate 1.4mm bubble sponge layer, which can greatly reduce the printing pressure, and at the same time increase the contact between the plate cylinder and the rubber cylinder, and even the rubber cylinder and the printing paper and the transfer ink time. However, there will be no excessive pressure peaks, which means that the contact width of the entire contact is widened, but the pressure is smaller and smoother. It has little effect on the tail effect of the thin paper printing on the mainframe, and there is no benefit of inaccurate overprinting of the paper. Otherwise, like a large flat printing machine with a width of more than 1450mm, the printing paper is under pressure, especially the thin paper below 80g / m2 accumulates the tail extension, which is 1.6, 1.7 times larger than 1000mm, and Unable to register and have good outlet reproduction. In addition, in the printing of corrugated paper, if the elasticity of the rubber blanket is insufficient, the corrugated streaks of the ribs will be generated under the rubber stamping, which is also the pressure of the corrugated peak. The bottom surface of the central sheet is suspended, but because the blanket is not soft enough and the contact pressure is not long enough, the transfer of the printing pattern is insufficient to produce a strip of ribs. Therefore, the ultra-thick air cushion blanket is produced for the giant flat printing machine, and Corrugated paper develops more evenly under pressure. Leather Gaming Chair,Leather Office Gaming Chair,Leather Swivel Gaming Chair,Comfortable Leather Gaming Chair Taihe Fangyuan Muye Co.,Ltd , https://www.fangyuanfurniture.com