The characteristics of gravure proofer (on)

(1) Gravure proofer proofing procedure Sequence of proofing installation material 10 Adjust the pressure of the proofing material → Insert the positioning pin → Adjust the ink → Check the ink viscosity → Install the plate cylinder → Set the squeegee pressure → Plate cylinder positioning → Apply Proofing ink → Monochrome and multicolor proofing → Detecting proofs

(2) When the gravure proofer proofing process is used for proofing, the impression cylinder presses the substrate on the surface of the printing plate by pressure, and the substrate absorbs the ink in the intaglio network cavity to form an image when the substrate is separated.

The quality of image transfer depends to a large extent on the rubber on the outermost layer of the impression cylinder. The hardness of the outer rubber on the gravure roller of the gravure proofer is generally 65 Shore, which is slightly lower than the hardness of the impression cylinder used by the printing company.

The pressure distribution produced by different hardness imprinting cylinders is not the same. The deformation of the cylinder with low hardness under the action of the same pressure is greater than that of the cylinder with large hardness. The elasticity produced by the deformation of the rubber can make the substrate elastically deformed. This results in a large area of ​​contact between the substrate and the gravure plate cylinder, which attracts more ink to the surface of the substrate. The hardness of the impression roller produced by the large deformation is small, the contact area with the gravure printing plate cylinder is small, the ink absorption of the substrate is also less.

The rubber hardness is not the same, and the difference in the performance of the printed product in the high light part is also obvious, especially when the paper is proofed, it will produce a blank point in the high light part. This phenomenon has a lot to do with the V-shaped structure of the electronic engraving version.

The British machine added an auxiliary electrostatic ink-absorbing device during the proofing, which can solve the high-light white point problem. The register device occupies a very important position in the concave prototype, first of all it requires a very good registration accuracy. Once the registration error is greater than 0.2mm, the effect of the concave pattern on the power map will be greatly affected. In general, the first circle of the concave machine must not have registration errors.

After each finish, a positioning stop below the impression cylinder will stop the impression cylinder at its last stopped position. When the impression cylinder is again close to the gravure cylinder, their squeezing points are the same as the last time. The position of the pinch points is the same, which ensures the accuracy of proofing.

One of the major drawbacks of domestic imitation machines is that they are not accurate in terms of register accuracy. Second, the registration device is required to have great flexibility. The length of the gravure plate cylinder varies greatly, the short is only 400mm, the long one may reach 1600mm, and the platen lines on the plate cylinder do not have a fixed position, and some are on the pattern, and some simply have no platen line . As long as these plate cylinders can be mounted on the proofing machine, accurate proofs are required to be printed. Therefore, the flexibility of the proofer registering device is relatively high.

The registration lens of the Japanese machine is fixed on the crossbar on the upper part of the plate cylinder. The register lens can slide left and right on the cross bar, and the right half of the plate cylinder can be registered. The British machine's register mirror is independent, it can focus on any part of the plate cylinder, flexibility is better than the Japanese machine. (To be continued)