A switchable intaglio printing mechanism and method of controlling the same

Abstract

A switchable gravure printing mechanism and a control method thereof, the mechanism comprising an independently driven engraved gravure roll, a rubber roll, a smooth steel roll, an ink groove and a doctor blade assembly; the engraved gravure roll is provided with a first doctor blade station and a second doctor blade station on both sides respectively, and the smooth steel roll is close to or away from the rubber roll through a moving mechanism. When the engraved gravure roll and the rubber roll are pressed together and the smooth steel roll is away, a two-roll direct gravure printing mechanism is formed, the printing substrate passes between the engraved gravure roll and the rubber roll, and the doctor blade assembly is located at the first doctor blade station; when the engraved gravure roll, the rubber roll and the smooth steel roll are pressed together, a three-roll indirect gravure printing mechanism is formed, the printing substrate passes between the rubber roll and the smooth steel roll, and the doctor blade assembly is located at the second doctor blade station. Through moving the smooth steel roll and switching the doctor blade station, the direct gravure printing and the indirect gravure printing can be flexibly switched on the same equipment without replacing the core components.

Description

Technical Field

[0001] This invention relates to the field of printing machinery technology, specifically to a switchable gravure printing mechanism and its control method. Background Technology

[0002] Gravure printing is one of the most widely used printing methods in packaging, publishing, decoration, and other fields. A conventional gravure printing unit mainly consists of an engraved gravure roller (plate roller) and a pressure roller (rubber roller). Its printing principle is as follows: halftone dots (i.e., cells) required for the image are formed on the surface of the plate roller through fine engraving or laser engraving. When the plate roller rotates, ink is applied from the ink trough. After the excess ink is scraped off by a doctor blade, the ink in the cells is directly transferred to the surface of the substrate under the pressure of the pressure roller, forming a solid or full-page image printing effect.

[0003] Observing the printed substrate surface with a magnifying glass of a certain magnification reveals that the ink layer is composed of countless tiny dots, each dot resembling a "small hill," with microscopic gaps between the dots. To achieve high opacity (solid printing), the amount of ink applied needs to be increased. The usual practice is to replace the ink rollers with engraved rollers that have different cell depths or line counts. In other words, every time the required amount of ink is changed, the machine needs to be stopped, the rollers changed, and the plate re-registered, resulting in reduced production efficiency. Furthermore, the equipment needs to be equipped with multiple plate rollers of different specifications, increasing equipment costs and operational complexity. Summary of the Invention

[0004] The present invention aims to provide a switchable gravure printing mechanism and its control method to solve the problems of existing gravure printing mechanisms that require frequent replacement of printing rollers to adjust the ink amount and cannot flexibly switch printing modes.

[0005] To solve the above-mentioned technical problems, the technical solution of the present invention is: a switchable gravure printing mechanism, including an independently driven engraved gravure roller, a rubber roller that cooperates with the engraved gravure roller, a smooth steel roller that cooperates with the rubber roller, an ink trough, and a doctor blade assembly. The engraved gravure roller has a first doctor blade station and a second doctor blade station on both sides respectively. The smooth steel roller moves closer to or away from the rubber roller through a moving mechanism. When the engraved gravure roller and the rubber roller are pressed together and the smooth steel roller moves away, a two-roll direct gravure printing mechanism is formed, and the substrate passes between the engraved gravure roller and the rubber roller. The doctor blade assembly is located at the first doctor blade station. When the engraved gravure roller, the rubber roller, and the smooth steel roller are pressed together, a three-roll indirect gravure printing mechanism is formed, and the substrate passes between the rubber roller and the smooth steel roller. The doctor blade assembly is located at the second doctor blade station. The principle of this invention is as follows: By using a screen roller with an appropriate line count and depth, and through an independently driven ink coating roller, under the condition of maintaining appropriate contact pressure, the linear speeds of the screen roller and the ink coating roller are adjusted to crush, even out, and thin the ink layer transferred from the screen roller, thereby achieving a method for controlling indirect printing with different thicknesses or reduced ink application for solid printing.

[0006] As an improvement, in the two-roll direct gravure printing mechanism, the substrate passes between the engraving roller and the rubber roller, and runs at the same speed as the two rollers while being held by the two rollers.

[0007] As an improvement, in the two-roll direct gravure printing mechanism, different sizes of engraving rollers are used to achieve different amounts of ink.

[0008] As an improvement, in the three-roll indirect gravure printing mechanism, the rubber roller and the smooth steel roller rotate at the same speed, the substrate passes between the rubber roller and the smooth steel roller, and runs at the same speed as the two rollers while being held by the two rollers.

[0009] As an improvement, in the three-roll indirect gravure printing mechanism, different ink amounts are applied by changing the speed relationship between the engraving roller and the rubber roller.

[0010] Switching steps for two-roll direct gravure printing mechanism (1) The smooth steel roller is moved from the working position to the idle position and separated from the main drive, and its drive motor stops working; (2) The rubber roller is separated from its transmission system to become a passive roller, which contacts the engraving concave roller and rotates with the engraving concave roller under appropriate pressure. During the operation, the two maintain the same speed and select the scraper assembly of the first scraper station to link. (3) The printing substrate passes between the engraving roller and the rubber roller, and runs at the same speed as the two rollers while being held by the two rollers; (4) The engraving roller is immersed in ink in the ink trough and after passing through the doctor blade assembly of the first doctor blade station, the ink is directly transferred to the printing substrate and finally enters the drying or curing system to complete the drying and curing of the ink layer. Switching steps for a three-roll indirect gravure printing mechanism (1) The engraving roller, rubber roller and smooth steel roller are all placed in the working position; (2) The engraving roller, rubber roller and smooth steel roller are connected to the transmission system and can all be driven independently; (3) The rubber roller and the smooth steel roller rotate at the same speed. The substrate passes between the rubber roller and the smooth steel roller and runs at the same speed as the two rollers while being held by the two rollers. (4) The engraving roller is immersed in ink in the ink trough and then passes through the doctor blade assembly of the second station and then indirectly transfers the ink to the printing substrate through the rubber roller. Finally, it enters the drying or curing system to complete the drying and curing of the ink layer.

[0011] The beneficial effects of this invention compared to the prior art are: 1. One machine for two uses, flexible switching: By moving the smooth steel roller and changing the doctor blade position, two-roll direct gravure printing and three-roll indirect gravure printing can be achieved on the same machine without changing the core components, adapting to different printing substrates and printing quality requirements. 2. Multiple ways to adjust the ink amount: In direct gravure printing mode, the normal ink amount can be obtained by changing the engraving roller of different specifications; in indirect gravure printing mode, the ink amount can be changed by adjusting the speed relationship between the engraving roller and the rubber roller, avoiding frequent roller changes and significantly improving production efficiency. 3. Compact structure and low modification cost: By simply adding a movable smooth steel roller and a dual-station doctor blade to the traditional two-roll gravure printing machine, two modes can be achieved, which is convenient for upgrading existing equipment. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the present invention.

[0013] Figure 2 This is a schematic diagram of a two-roll direct gravure printing mode.

[0014] Figure 3 This is a schematic diagram of a three-roll indirect gravure printing mode. Detailed Implementation

[0015] The present invention will now be further described with reference to the accompanying drawings.

[0016] like Figure 1 As shown, a switchable gravure printing mechanism includes an independently driven engraving roller 1, a rubber roller 2 that cooperates with the engraving roller 1, a smooth steel roller 3 that cooperates with the rubber roller 2, an ink trough 4, and a doctor blade assembly 8. The engraving roller 1 has a first doctor blade station 5 and a second doctor blade station 6 on both sides. The smooth steel roller 3 moves closer to or away from the rubber roller 2 through a moving mechanism.

[0017] Two-roll direct gravure printing mode like Figure 2 As shown, the switchable gravure printing mechanism includes an independently driven engraving roller 1, a rubber roller 2, a smooth steel roller 3, an ink trough 4, and a doctor blade assembly 8. The smooth steel roller 3 is moved away from the rubber roller 2 via a moving mechanism. The engraving roller 1 and the rubber roller 2 press against each other. The doctor blade assembly 8 is located at the first doctor blade station 5 on one side of the engraving roller 1.

[0018] The printing substrate 7 passes between the engraving roller 1 and the rubber roller 2, and runs at the same linear speed while being held between the two rollers. The lower part of the engraving roller 1 is immersed in the ink tank 4, and its rotation carries up the ink. The excess ink on the surface is scraped off by the doctor blade assembly 8 at the first doctor blade station 5, leaving only the ink in the cells. When the engraving roller 1 and the rubber roller 2 are pressed together, the ink in the cells is directly transferred to the surface of the printing substrate 7 to form a printed pattern. Subsequently, the printing substrate 7 enters a drying or curing system (not shown in the figure) to complete the drying and curing of the ink layer.

[0019] In this mode, if the ink application amount needs to be changed, the operator only needs to replace it with another engraving roller 1 that has a different cell depth or line count, while other components remain unchanged. Since the rubber roller 2 is a passive roller that follows the engraving roller 1, the two rollers always maintain the same speed. Therefore, there is no need to rematch the speed after changing rollers, making the operation simple.

[0020] Three-roll indirect gravure printing mode like Figure 3 As shown, the smooth steel roller 3 is pushed to the position where it presses against the rubber roller 2 by the moving mechanism, while the scraper assembly 8 is moved to the second scraper station 6 on the other side of the engraving concave roller 1. At this time, the engraving concave roller 1, the rubber roller 2, and the smooth steel roller 3 press against each other, and the three rollers are respectively connected to independent transmission systems (or at least the rubber roller 2 and the smooth steel roller 3 have independent drives).

[0021] The printing substrate 7 passes between the rubber roller 2 and the smooth steel roller 3, and runs at the same speed while being held between the two rollers. The rubber roller 2 and the smooth steel roller 3 maintain the same surface linear velocity. After the engraved concave roller 1 is dipped in ink, it is scraped by the doctor blade assembly 8 at the second doctor blade station 6, and then comes into contact with the rubber roller 2, transferring the ink in the cells to the rubber surface of the rubber roller 2. The rubber roller 2 then rotates to the pressing area with the smooth steel roller 3, transferring the ink onto the printing substrate 7. Because the ink undergoes a secondary transfer, the transfer pressure is more uniform, and direct contact between the engraved concave roller 1 and the substrate is avoided, making it suitable for printing on materials with rough surfaces, easily scratched surfaces, or pressure-sensitive surfaces.

[0022] In this mode, the amount of ink applied can be adjusted by regulating the speed relationship between the engraving roller 1 and the rubber roller 2. For example, when the linear speed of the engraving roller 1 is slightly higher than that of the rubber roller 2, the amount of ink transferred per unit time increases, thereby achieving higher opacity; conversely, the amount of ink applied decreases. This adjustment method does not require replacing the engraving roller 1 and can be dynamically adjusted online, making it particularly suitable for small-batch, multi-variety printing production.

[0023] Comprehensive Explanation of Control Methods Operators select the printing mode based on the production task: If a two-roller direct gravure printing is used, the following steps are performed: remove the smooth steel roller 3 and stop its motor; disengage the rubber roller 2 from the drive and make it a passive roller; place the doctor blade assembly 8 in the first doctor blade station 5; insert the printing substrate 7; start the engraving roller 1, which drives the rubber roller 2 to rotate synchronously, and start printing.

[0024] If a three-roller indirect gravure printing is used, the following steps are performed: move the smooth steel roller 3 to the pressing position; connect the independent drives of the three rollers and set the rubber roller 2 and the smooth steel roller 3 to the same speed; place the doctor blade assembly 8 in the second doctor blade station 6; the printing substrate 7 passes between the rubber roller 2 and the smooth steel roller 3; start all rollers and set the speed relationship between the engraving roller 1 and the rubber roller 2 according to the required ink amount, and start printing.

[0025] Both modes share the same set of ink tank, doctor blade assembly and drying and curing system, with short switching time and convenient operation.

Claims

1. A switchable gravure printing mechanism, characterized in that: The system includes an independently driven engraving roller, a rubber roller that cooperates with the engraving roller, a smooth steel roller that cooperates with the rubber roller, an ink trough, and a doctor blade assembly. The engraving roller has a first doctor blade station and a second doctor blade station on both sides. The smooth steel roller moves closer to or away from the rubber roller via a moving mechanism. When the engraving roller and the rubber roller are pressed together and the smooth steel roller moves away, a two-roller direct gravure printing mechanism is formed, and the substrate passes between the engraving roller and the rubber roller. The doctor blade assembly is located at the first doctor blade station. When the engraving roller, the rubber roller, and the smooth steel roller are pressed together, a three-roller indirect gravure printing mechanism is formed, and the substrate passes between the rubber roller and the smooth steel roller. The doctor blade assembly is located at the second doctor blade station.

2. The switchable gravure printing mechanism according to claim 1, characterized in that: In a two-roll direct gravure printing mechanism, the substrate passes between the engraving roller and the rubber roller, and runs at the same speed as the two rollers while being held in place by the two rollers.

3. The switchable gravure printing mechanism according to claim 1, characterized in that: In a two-roll direct gravure printing mechanism, different sizes of engraving rollers are used to apply different amounts of ink.

4. The switchable gravure printing mechanism according to claim 1, characterized in that: In a three-roll indirect gravure printing mechanism, the rubber roller and the smooth steel roller rotate at the same speed. The substrate passes between the rubber roller and the smooth steel roller and runs at the same speed as the two rollers while being held by the two rollers.

5. The switchable gravure printing mechanism according to claim 1, characterized in that: In a three-roll indirect gravure printing mechanism, different ink application amounts are achieved by changing the speed relationship between the engraving roller and the rubber roller.

6. A control method for a switchable gravure printing mechanism as described in claim 1, comprising the following steps: Switching steps for two-roll direct gravure printing mechanism (1) The smooth steel roller is moved from the working position to the idle position and separated from the main drive, and its drive motor stops working; (2) The rubber roller is separated from its transmission system to become a passive roller, which contacts the engraving concave roller and rotates with the engraving concave roller under appropriate pressure. During the operation, the two maintain the same speed and select the scraper assembly of the first scraper station to link. (3) The printing substrate passes between the engraving roller and the rubber roller, and runs at the same speed as the two rollers while being held by the two rollers; (4) The engraving roller is immersed in ink in the ink trough and after passing through the doctor blade assembly of the first doctor blade station, the ink is directly transferred to the printing substrate and finally enters the drying or curing system to complete the drying and curing of the ink layer. Switching steps for a three-roll indirect gravure printing mechanism (1) The engraving roller, rubber roller and smooth steel roller are all placed in the working position; (2) The engraving roller, rubber roller and smooth steel roller are connected to the transmission system and can all be driven independently; (3) The rubber roller and the smooth steel roller rotate at the same speed. The substrate passes between the rubber roller and the smooth steel roller and runs at the same speed as the two rollers while being held by the two rollers. (4) The engraving roller is immersed in ink in the ink trough and then passes through the doctor blade assembly of the second station and then indirectly transfers the ink to the printing substrate through the rubber roller. Finally, it enters the drying or curing system to complete the drying and curing of the ink layer.

7. The control method for the gravure printing mechanism according to claim 6, characterized in that: In a two-roll direct gravure printing mechanism, different ink amounts are achieved by changing the engraving rollers of different specifications; in a three-roll indirect gravure printing mechanism, different ink amounts are achieved by changing the speed relationship between the engraving roller and the rubber roller.

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