Comparison of the most popular gravure proofing me

Comparison of gravure proofing methods (Part 2)

the new gravure proofing machine has been constantly exploring in simulating the actual printing production process (embossing form, ink, substrate materials, etc.), and has taken a series of improvement and assurance measures, so as to reflect the quality of the drum as truly as possible and expect the printing effect

as the technical performance of gravure proofing machine itself has been continuously improved in the past 10 years, machine proofing has become more and more common, and has developed rapidly in recent years. The gravure proofing machine of a famous manufacturer is introduced as an example

II. Introduction to gravure proofing machine

1. Main technical specifications

at present, the maximum plate cylinder surface width of gravure proofing machine on the market can reach 4000mm, and the circumference of plate cylinder can reach 2200mm before selecting fixture, so its width and circumference can cover all gravure fields (see Table 1)

in order to better reflect the actual gravure printing effect, the length of proofing is generally at least two graphic lengths. Therefore, the standard of proofing is that the working degree of five pointed star is 2100mm, 2600mm, 3500mm and 5500mm respectively

2. Applicable occasions

gravure proofing machine can meet the actual needs of gravure machines for various purposes, and is suitable for plate cylinders of various widths and lengths. At present, there are gravure proofing machines on the market for the following machines: gravure printing machines for packaging, gravure printing machines for publishing, gravure printing machines for wallpaper, gravure printing machines for gifts and gravure printing machines for decoration

3. Proofing conditions

the substrate used for proofing by gravure proofing machine is the same as that used for actual printing, and the ink used is also similar to that used for actual printing, except that the solvent content used is low. The gravure printing machine used in actual production is generally composed of multiple printing color groups, but in most gravure printing machines, facing severe energy and environmental challenges, the printing proofing machine only simulates one unit of the actual printing machine, that is, the monochrome machine

4. Mechanical structure

gravure proofing machine is mainly composed of the following parts:

(1) support mechanism of plate cylinder

the support mechanism of plate cylinder adopts conical center or butterfly chuck system. The former is used for proofing of small sleeve cylinder, and the applicable circumference of printing cylinder is between 200-750mm. The latter can be loaded and unloaded by an operator, and the plate cylinder and cleaning device can be prevented from moving or rotating by driving the friction pad through the pneumatic motor. The system is suitable for various sizes of plate cylinder, especially for shaft type plate cylinder and sleeve type plate cylinder. The system is simple and flexible, which is especially useful in drum proofing

(2) cleaning system

the cleaning system adopts pneumatic transmission and can be used for shaft type plate cylinder and sleeve type plate cylinder. The system is simple and flexible, which is especially useful in large drum proofing

(3) electrostatic assisted ink transfer device

this device is especially suitable for printing materials that are difficult to print. Because the surface of this kind of material has grain structure, it is very difficult to print fine layers. After using the electrostatic auxiliary ink transfer device, this problem can always be overcome, and the proofing effect can be comparable to the actual gravure printing

(4) registration system with display

the system uses the double crosshairs generated by electronic technology on the screen to adjust the parallelism error. The system is used to compensate the gradually changing drum

(5) large rubber roller

the surface of the large rubber roller is wrapped with the printing material. Although it is not an imprinting roller, it generates pressure by its contact with the plate treatment cylinder, and there is a mechanism to ensure that a certain pressure is controlled and adjusted at both ends

the proofing treatment cylinder is placed between the top centers of two collets or on the roller bearing of the swing arm support. The proofing drum is close to or opposite to the large drum. The length of the printing material is 2-3 times of the circumference of the printing plate cylinder, so as to form a good simulation of the continuous production process of web paper

(6) the method of successive comparison is adopted. The doctor blade on the gravure proofing machine is the same as that actually used on the gravure machine

the technical characteristics and operation advantages of gravure proofing machine are: the large cylinder and plate cylinder adopt hydraulic transmission, the structure is precise, the system operation is simple, there is almost no need for maintenance, the embossing force at both ends is balanced, the registration control is accurate, and the simulation effect of gravure proofing machine is good. The machine can complete the proofing operation by one person in 10 minutes, which can reduce the amount of ink and materials, and can visually and accurately detect the engraving quality of the drum

5. Registration control '

in order to carry out multi-color registration and obtain color proofing effect, the following operation processes must be coordinated:

(1) the printing material must be wrapped on the large roller under a practical tension

(2) the first color plate cylinder is installed between the top centers of two collets or on the swing arm bearing

(3) move the large cylinder, close to the surface of the plate cylinder, rotate to its locking position, and fix it with a pin to make it in a safe state

(4) rotate the plate cylinder and align the horizontal gauge line of the registration mirror with the horizontal gauge line engraved on the surface of the cylinder

(5) the large cylinder is close to the plate cylinder and reaches a certain pressure

(6) check the registration state and repeat until the gauge line is completely aligned

(7) adjust the doctor blade to the same position as the roller and the rayon. For example, the ink is relatively thick, so that the ink can be applied to the doctor blade along the surface of the roller, and then pull out the locking pin

(9) drive the large cylinder, drive the driven plate cylinder to rotate, and form an "impression" at the contact between the large cylinder and the plate cylinder through the doctor blade

ink is transferred from the ink hole to the surface of the substrate under the same stress conditions through the action of pores (in some cases, the proofer does not use the electrostatic auxiliary ink transfer device). The large roller rotates to the end position of its circumference to get the largest printing sheet. After the rotation, the large cylinder leaves the surface of the plate cylinder. At this time, the plate cylinder can be cleaned and disassembled

for the proofing of each color after the second color, repeat the same process as above after the previous color is dried