Gravure printing is a printing method commonly used in flexible packaging . The printing mechanism is an important part of the gravure printing machine, and its performance will directly affect the quality of the final printing. This paper mainly introduces the main structure and characteristics of the gravure printing mechanism.
Main structure of the imprinting mechanism
The main structure of the gravure printing mechanism can be divided into the following two types: a swing arm type imprinting mechanism and a direct pressing type imprinting mechanism. The direct-pressing embossing mechanism can be further divided into a direct-press embossing mechanism with a back pressure roller, a three-roll direct-pressure embossing mechanism, and a direct-press embossing mechanism that does not change the material length.
1. Swing arm type imprinting mechanism
The swing arm type embossing mechanism is mainly composed of a set of swing arm, embossing rubber roller, embossing cylinder, electromagnetic valve and pressure reducing valve. One end of the swing arm is provided with a guiding roller, and the other end is provided with an embossing rubber roller. , the whole rotation around the swing arm mandrel
To achieve the clutch pressure function. When the embossing mechanism is pressed and pressed, the material length changes little, so when the pressure is recompressed, the stretching of the printing material is small, which is favorable for printing, and the change of the material length is related to the diameter of the device such as the embossing roller. .
2. Direct pressure stamping mechanism
(1) A direct-pressing embossing mechanism with a back pressure roller, which includes a rack and pinion, a back pressure roller, an embossing roller, a linear guide, a cylinder, a solenoid valve, a pressure reducing valve, etc., which are used for synchronization. It is mainly used in gravure printing machines with large embossing force and wide width, and the manufacturing cost is high.
(2) Three-roller direct pressure type imprinting mechanism
The embossing mechanism is relatively common on gravure printing machines produced abroad, and the main feature is that there are three embossing rubber rollers mounted on the same disc. When replacing the embossing roller, just turn the handwheel and the embossing roller on the disc will rotate around the A axis and will automatically position when it is in place. Therefore, if the company has three short-run jobs in the regular order, then the use of this imprinting mechanism can greatly save work preparation time and improve production efficiency.
(3) Direct pressure type imprinting mechanism that does not change the material length
The biggest feature of this mechanism is that the material length between the units will not change during the clutch pressure, so there will be no problem of overprinting due to pressure and recompression. When the substrate is a stretchable film, the advantages of the embossing mechanism will be more apparent. At present, the embossing mechanism has been applied for patents by people in the northwest of Shaanxi, and has been widely used in the high-end gravure printing machine of people in northwestern Shaanxi.
The main form of the embossing roller
The main form of the embossing roller can be divided into an integral embossing roller and a sleeve embossing roller.
Rubber layer hardness and roll core rigidity of embossing rubber roller
The hardness of the adhesive layer of the embossing roller also directly affects the quality of the printed product. Generally speaking, the Shore hardness of the low-speed film gravure press embossing rubber roller layer is 65-70, and the high-speed film gravure press embossing rubber roller layer has a Shore hardness of 70-75, and the paper is concave. The Shore hardness of the adhesive layer of the printing machine is 80 to 90. In the case where the imprinting force is constant,
If the hardness of the rubber layer of the embossing roller is low, the deformation of the rubber layer will increase, and the dot will be more easily deformed; if the hardness of the rubber layer is high, the deformation of the rubber layer will decrease, and the ink transfer rate will also follow. reduce. The roll core rigidity of the embossing roller is also particularly important. The embossing roller is in contact with the plate cylinder under the action of the embossing force. In the axial direction of the embossing roller, the printing pressure of the embossing roller core itself is uneven in the axial direction of the embossing roller. The roll core, which is usually close to the support portion, has small deformation and large deformation in the middle. This will result in a quality failure in the print that is partially false or overprinted but can be registered on both sides. This problem is more prominent in high-speed, wide-format gravure presses. In order to solve this problem, we can make the embossing rubber roller into a medium-high roller. The medium-high value should be determined according to the material mechanics theory and the specific force.
　　 The above content is selected from the third issue of 2011, Printing and Printing , Packaging and Decoration, and more journal content. Please pay attention to the journal channel.
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