A printing machine inker assembly with a new ink transfer mechanism

Abstract

The invention relates to an inker assembly for a printing machine. The inker assembly includes a fountain roll, a multi-piece ductor roller with multiple rollers covered in rubber for ink transfer, and some double acting pneumatic jack assembly that enables the independent movement of each roller between a fountain roll and a steel roll. The rollers' movement is controlled by electro-pneumatic valves located outside of ductor roller space, which are operated by a Programmable Logic Controller (PLC). The PLC processes input data regarding ink tone and density to control the ink transfer rate precisely. Sensors, including ultrasonic sensors, monitor ink thickness and provide feedback to the PLC, ensuring accurate ink distribution. The assembly also features a compressed air converter manifold that manages the air paths for pneumatic jacks, optimizing space efficiency and improving the system's overall functionality. This design enhances ink transfer control, improves accuracy, and extends the lifespan of the inker components by preventing premature wear and contamination.

Description

DescriptionTitle of Invention : A printing machine inker assembly with a new ink transfer mechanismTechnical Field

[0001] The present invention relates to an ink supply device for a printing machine, and more particularly to a device which supplies ink to a printing surface through an ink fountain, an ink fountain roller, an ink transfer roller, and a plurality of ink distribution rollers.Background Art

[0002] Background description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.

[0003] Offset and letterpress printing machines use a ductor roller to transfer ink between an ink fountain roller and an ink distribution roller. The ductor roller alternates contact between these two rollers to receive and deliver ink, controlling the ink supply to the plate cylinder. When multiple individual ductor rollers are used, they can move independently to adjust the ink supply more precisely along the ink fountain roller’s axis. These rollers are mounted on a fixed shaft and move towards the ink fountain roller using pneumatically driven pistons. Springs and contact pieces bias the rollers towards the ink distribution roller, and they return to this position when the air supply is cut off. Electromagnetic valves which locked and placed inside ductor roller housing control these movements.

[0004] The US.App.No. US20200338881 discloses a ductor roller for printing machines consists of a shaft with an air supply pipe, multiple individual ductor rollers, and electromagnetic valves, all connected to the shaft. The ductor rollers, which move forward and backward to transfer ink, are pneumatically advanced by the electromagnetic valves housed within their structures. These rollers have housings associated with the shaft, roller members that contact the ink fountain and distribution rollers, and bearings connecting the roller members to the housings. To protect the electromagnetic valves from contamination by cleaning liquids, oil-resistant protection members with circularly cylindrical or arc-likecovers are used. These covers, positioned in the gaps between the individual ductor rollers, guide cleaning liquids away from the valves along troughs, ensuring the valves’ proper operation without needing replacement.

[0005] The US. Pat.No.9446581 describes an ink supply device for printing machines that ensures accurate ink supply to achieve the desired concentration without requiring fine adjustments by the operator. The said device uses multiple ink transfer rollers positioned along the ink fountain roller. These rollers can switch between contact and non-contact positions with the ink fountain roller. The control system adjusts the position and rotational angle of these rollers to control the amount of ink transferred, ensuring consistent ink supply and concentration.Summary of Invention

[0006] The summary of disclosed invention is intended to provide an overview of the subject matter of the invention, and is not intended to identify essential elements or key elements of the subject matter, nor is it intended to be used to determine the scope of the claimed implementations.

[0007] The invention focuses on an advanced inker assembly for a modern can printing machine. The inker assembly features a fountain roll and a multi-piece ductor roller system with several independently movable rollers covered in rubber for efficient ink transfer. Each roller's movement is controlled by a double acting pneumatic jack -piston system, activated by electro-pneumatic valves managed by an electronic controller such as a Programmable Logic Controller (PLC) . The said valves are outside of ductor roller housing and fully available. The controller adjusts the ink transfer rate by processing input data on ink tone and density, allowing precise control over the ink application. Various sensors, such as ink thickness and distance control sensors, provide feedback to the PLC to ensure accurate ink distribution and check correct operation of pneumatic jacks. The assembly's design includes a compressed air converter manifold to optimize space efficiency and streamline the air paths for the pneumatic jacks, enhancing overall performance and reducing component wear.Technical Problem

[0008] One of the problems that exists in the design of the ink transfer mechanism in previous inventions is the problem of delay or jamming of the actuator spring orits pneumatic jacks, which becomes apparent due to the operation and passage of time. This problem arises due to the use of a spring in one-way pneumatic jacks, so that the use of a spring in this system causes, in the rollers (the areas that require maximum ink transfer), the speed of the pneumatic jack movement - due to the fatigue of the spring due to the operation cycle and the working time is not under control.

[0009] In previous art and current industry practices, an intelligent ink transfer control system is employed to measure a pre-determined amount of ink using sensors. This data is processed through defined functions to time the signals sent to the electromagnetic valves. Theoretically, this should result in precise control of the ink required along the ductor roller’s axis. However, in practice, this precision is not always achieved.

[0010] In the beverage can printing industry, various sensors are used to control ink thickness and density. Optical sensors utilize 3D image technology to measure thickness and density accurately. Laser sensors employ laser technology for precise measurements, with features like high accuracy and fast response times. Combined sensors, integrate both laser and optical technologies to measure ink thickness and density in real time.

[0011] In practice, because a spring is used to provide the moving force on one side of the ductor roller, its coefficient decreases with wear and tear. As a result, the spring force connecting the ductor roller to the next roller diminishes. Additionally, the pressure that keeps the ductor roller in contact with the next roller is significantly reduced. Consequently, the intelligent control system, through the mentioned sensors, detects that the thickness or amount of transfer ink is less than the predetermined amount. To compensate, the intelligent control system increases the number of signals sent to the electromagnetic valves per unit of time, allowing the ductor roller to transfer more ink per unit of time. However, this reduces the accuracy of ink transfer, leading to jamming of the pneumatic jacks or erratic movement of the ductor roller.

[0012] In existing systems, there is significant resisting force due to the shape of the seals — the protective members between the rollers or sheaths — against the force of the spring movement. In other words, the profile of the cross-section of theprotective members, according to the structure of their seat in previous inventions, creates a low elasticity coefficient and more resistance against the displacement of the spring force. This resistance force, known as a resistance force against the spring force, contributes to the depreciation and fatigue of the springs, as discussed in detail above.

[0013] It should be noted that, as evident in the designs of previous inventions, the severe limitation of space does not allow for the use of a larger or stronger spring to solve this problem as a simpler and less expensive solution. Therefore, the new design proposed in the present invention eliminates the use of a spring.

[0014] Another technical problem with existing systems is the placement of electropneumatic valves inside the multi-piece roller axis. Due to the need to fix defects, repair, service, or replace any internal components such as electro-pneumatic valves or electromagnetic coils, access is limited in conventional systems. To service, maintain, or replace any of these components, the entire roller set must be disassembled. This process is complicated and time-consuming, requiring significant time, high costs, and expert manpower to replace just one electropneumatic valve. For example, if a spring is stuck or broken in one of the oneway jacks, or if one of the electromagnetic coils of the pneumatic valves burns out, the entire assembly must be removed from the machine and for fixing according to the mentioned steps, it must be completely disassembled .Advantageous Effects of Invention

[0015] The configuration of electro-pneumatic valves outside the multi-piece ductor roller assembly allows for quick and easy service, reducing the costs and manpower needed for diagnosing and replacing valves. Standard electropneumatic valves respond to electrical signals within 10 milliseconds and can be replaced in few minutes with two small screws, unlike previous systems that required complete disassembly for any component damage or coil burnouts. This design eliminates issues related to fatigue, spring jamming, and lack of access for replacements, reducing service and maintenance stops through easy troubleshooting and quick valve access. Printing accuracy is improved by using double acting pneumatic jacks and removing springs from one-way jacks. The problem of coil burning in electro-pneumatic valves is eliminated by preventing confinement in a closed space, enhancing efficiency. The system's seals, with aU-shaped cross-section, provide stronger and longer-lasting sealing due to their high elasticity, significantly increasing the lifespan and protection of internal components compared to previous sealing systems. Overall, this design greatly extends the lifespan and reduces the need for repair and service of the printing machine.Brief Description of Drawings

[0016] The figures of the present document are intended to be illustrative, not limiting.

[0017] Fig.1 shows the location of an ink transfer mechanism of printing machines on the inkers of beverage can printing machines.

[0018] Fig. 2 shows a view of an ink transfer mechanism and 3D representation of its components.

[0019] Fig. 3 illustrates a section view presenting the components of an ink transfer mechanism of printing machines.

[0020] Fig. 4 shows a cross-sectional view of a roller.

[0021] Fig. 5 shows the multi-part (piece) block diagram of roller's control.Description of Embodiments

[0022] A modern aluminum beverage can printing machine typically features at least 8 inkers, known as 8-color machines. Each inker generally consists of at least one ink jet or fountain (4), a fountain roll (2), and a multi-piece ductor roller (1.1 ).

[0023] Each inker is responsible for transferring one color of ink to a printed design. The ink is placed in the fountain chamber, and then the fountain roll, which is dipped in the ink, starts to rotate. The multi-piece ductor roller (1.1 ) is positioned parallel between the fountain roll (2) and the steel roll (3). Under normal conditions, it is always in contact with the steel roll (3) and spins due to the rotating force of the steel roll (3).

[0024] The mechanism of the multi-piece ductor roller (1 .1 ) works such that each roller (1 .6) has a rubber cover for ink transfer. These rollers are completely separate and have free rotational movement through the bearings (1 .7) on which they are assembled. They also have the ability to move separately through thepneumatic jack piston (1.12), which can control reciprocating movement through electro-pneumatic valves (1 .2).

[0025] The working process is as follows: each pneumatic valve (1 .2), upon receiving a signal from a controller such as a Programmable Logic Controller (PLC) system (1 .20), causes the associated rollers (1 .6) to move independently from the steel roll (3). These rollers then come into contact with the fountain roll (2) and continue to rotate due to the rotational force of the fountain roll (2). This process allows the rollers to be coated with the ink present on the surface of the fountain roll (2).

[0026] Examples or substitutes for PLCs are as follows:

[0027] SCADA (Supervisory Control and Data Acquisition), RTUs (Remote Terminal Units), Soft PLCs (Software- Based PLCs) and microcontrollers.

[0028] In the next step, upon receiving a signal to the other side of the pneumatic valves (1 .2), the ductor roller (1 .6) separates from the fountain roll (2) and comes into contact with the steel roll (3). The ductor roller (1 .6) then rotates due to the movement of the steel roll (3), transferring the ink from the fountain roll (2) to the steel roll (3).

[0029] This procedure for the entire width of the ink transfer by each of the rollers (1 .6) of the multi-piece ductor roller (1.1 ) enables us to schedule the signals of the electro-pneumatic valves (1 .2) corresponding to each of them through the PLC program. This control allows us to manage the rollers (1.6) and ultimately control the ink transfer rate during the ink transfer process in the multi-piece ductor roller (1 .1 ) in the inkers of the printing machines.

[0030] In fact, a PLC controller system (1 .20) receives input data about the tone and density of the ink transfer, which is calculated in advance for each printed label. It then processes this data into signals to activate each of the electro-pneumatic valves (1 .2). As a result, each of the pistons(1 .12) of the pneumatic jacks(1 .30) is moved by compressed air, causing the rollers (1 .6) to move. This allows the speed and density of the ink transfer to be controlled completely separately, electrically, and automatically at several points across the width of the ink transfer.

[0031] For each of the rollers (1 .6), a distance control sensor (1.19) ensures the correct operation of the pistons (1.12) of the pneumatic jacks(1 .30) and pneumatic valves (1 .2). Several sensors or controller, such as ink thickness and density controller (1 .22), verify and control the density or thickness of the transfer ink on other inker rollers of the printing machine. In one embodiment of the present invention the controller (1 .22) is an ultrasonic sensor. These sensors send signals to the PLC (1 .20) and provide feedback to the PLC system. By processing this feedback, the system automatically adjusts the movement speed of the multi-part ductor roller (1.1 ). This closed-loop operation increases the accuracy of the ink transfer.

[0032] The ink transfer mechanism in the present invention includes a main axis(1.10) on which several distance control sensors (1.19) and roller position controls (1 .6) are installed. The main axis features multiple cylinders (1.11 ), each configured with a forward and return path for compressed air. A piston (1 .12) is installed in each cylinder along with a shaft to facilitate the movement of the rollers (1 .6). Each piston (1 .12) uses two seals (1.15 and 1.16) separately for each of the return paths. Each cylinder (1.1 1) is closed by a cylinder cap or cover (1.13), which includes a seal (1.17) that seals the piston shaft (1.12) while allowing movement.

[0033] In the seat of the flange corresponding to each cover (1.13) on the main axis(1.10), an O-ring (1.14) is configured for the static seal of the cover (1.13). Each pneumatic jack piston shaft is connected to a sheath (1 .8) through a connecting pin (1.18), which is the connecting interface for transferring the reciprocating movement of the pneumatic jack piston (1.12) to the sheath (1 .8) and a bearing(1 .7) is placed on each sheath (1 .8). On each bearing (1 .7) there is a roller (1 .6) with a rubber cover, which has a free rotational movement through the bearings(1 .7). Between the two covers or two sheaths (1 .9), a seal (1 .8) is designed in the shape of a U-shaped cross-section, which allows to achieve a high elasticity coefficient.

[0034] In the present document, the edges of the shields do not contact the seals when moved, preventing premature seal erosion and internal component damage from contaminants, ink, and solvents. This also avoids roller gearing lock-up. The electro-pneumatic valves (1 .2) outside the multi-piece ductor roller assembly (1.1 )control the pneumatic jack(1 .30) movement via their connection to the compressed air converter manifold on the manifold rail or base plate (1 .3) and the main axis compressed air converter manifold (1 .4). All compressed air paths for the pneumatic jacks can be connected to the electro-pneumatic valves in a coherent and integrated manner. This innovative design of compressed air path converter manifolds is crucial for space efficiency.

[0035] Due to the inconsistency between the compressed air paths of the jacks in the main axis and those in the sub-valve, these paths must be connected in a specific order. The first pneumatic valve should connect to the first jack, continuing sequentially to the last pneumatic valve and jack. Given space limitations, the manifold geometry of the compressed air paths should be compact. This design uses two compressed air converters to solve the problem, connecting the paths in two stages. One converter is the manifold of the compressed air converter, and the other is the manifold of the compressed air converter of the main axis.

[0036] In this invention, several structural changes have been made, including the configuration of electro-pneumatic valves (1 .2) outside the ductor roller assembly and the double acting pneumatic jack (1 .30) to eliminate the spring in one-way jacks.

[0037] Construction of the main axis with designed cylinders and return air path passageways for each pneumatic cylinder.The pneumatic jack covers to accommodate the double acting jacks, allowing for thread installation on each cylinder in the main axis, along with static seal locations, caps, and dynamic shaft jack seals.

[0038] V-shaped seals of piston and jack increase jack lifespan and reduce wear, significantly extending the system’s working time.

[0039] Manifold of the main axis compressed air converter to reorder the air paths of pneumatic jacks, converting forward paths to the bottom side and return paths to the top side, integrating with the sub-valve manifold of standard pneumatic direction control valves.

[0040] Design of the compressed air converter manifold under the tap to adjust the distance of air return paths from the main axis converter manifold to the valve itself, where standard pneumatic direction control valves are installed.Industrial Applicability

[0041] The mechanism described in the present document, is primarily used in the beverage industry for printing on cans for soft drinks, energy drinks, and alcoholic / nonalcoholic beverages like beer and hard seltzers. Its advanced design ensures high-quality, durable, and attractive labels directly on the cans, which is crucial for product branding and consumer appeal. Additionally, it finds applications in the packaging industry for various liquid products, promotional products for customized and limited-edition cans, craft breweries for unique can designs, the food industry for canned foods, and the cosmetics and personal care sector for products like hair sprays and deodorants. The machine’s efficient and easy-to-service design significantly reduces maintenance stops and enhances printing accuracy, making it a valuable asset across these industriesJ

Claims

Claims

1. A printing machine inker assembly with a new ink transfer mechanism comprising: a fountain(4) for holding ink; a fountain roll(2) positioned to rotate and contact the ink in the fountain; a multi-piece ductor roller assembly(1 .1 ) positioned parallel to the fountain roll comprising a plurality of rollers( 1 .6), each having a rubber cover for ink transfer; a pneumatic jack assembly(1 .30) for each cylinder(1 .11 ) configured to move each roller independently in a reciprocating manner between the fountain roll and a steel roll(3) wherein the pneumatic jacks are double acting allowing for two- way movement; and a plurality of electro-pneumatic valves(1 .2) which are located outside of the multi-piece ductor roller assembly space and controlled by an electronic controller^ .20) to actuate the pneumatic jack piston (1.12), wherein the electronic controller receives input data regarding the ink tone and density and processes this data to control the electro-pneumatic valves.

2. The printing machine inker assembly of claim 1 , further comprising at least one distance control sensor to monitor and verify the operation of each signal sent from the electronic controller to the pneumatic solenoid valves as well as plurality of ink thickness and density controller to monitor and verify the thickness and density of the created ink compared to the predetermined value and send the signals of the sensors to the electronic controller for processing and correcting possible deviations.

3. The printing machine inker assembly of claim 1 , wherein the pneumatic jack piston (1 .21 ) are connected to sheaths via connecting pins(1 .18), transferring the reciprocating movement of the pneumatic jack pistons to the sheaths and the rollers.

4. The printing machine inker assembly of claim 1 , wherein each piston (1.12) uses two seals (1.15 and 1.16) separately.

5. The printing machine inker assembly of claim 1 (1 .11 ) is closed by a cylinder cap or cover (1 .13), which includes a seal (1.17) that seals the shaft of puiston(1 .12).

6. The printing machine inker assembly of claim 1 , wherein the main axis of the multi-piece ductor roller assembly includes multiple cylinders, each configured with a forward and return path for compressed air to control the movement of the pneumatic jack pistons.

7. The printing machine inker assembly of claim 1 , wherein the electropneumatic valves are connected to the pneumatic jack pistons via a compressed air manifold on a base plate.

8. The printing machine inker assembly of claim 1 , features U-shaped cross-sectioned seals(1 .8) to space the edges of the sheaths from the seals, ensuring high elasticity by uniformly distributing the force applied to the surface of the seals.

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