Field of the Invention

The present invention relates to plate handling apparatus, and related plate handling methods.

Background the Invention

The flexographic printing process, also referred to flexography or simply flexo is a printing process which utilizes a flexible relief plate in forming the image to be printed. Such flexo plates are formed from a thin sheet of flexible material, typically a photopolymer material, and carry a positive mirrored master of the required image as a 3D relief. When in use, the plate is mounted around a cylinder in a printing press and transfers ink to a substrate that carries the printed image. The printing press can be efficiently set up to print different images by use of different plates. Between printing operations, it is important to clean any residual ink or other contamination from flexo plates so that high print quality can be maintained in future print runs. Since the plates typically comprise fine detail, and are made from materials that could be damaged by aggressive mechanical or chemical cleaning processes, ultrasonic cleaning baths are employed. However, a problem arises in handling flexo plates in the cleaning process. The nature of the materials, typical sizes, thicknesses and the inherent susceptibility to damage of flexo plates means that handling multiple plates and ensuring a regular and controlled supply of plates into an ultrasonic cleaning bath is difficult.

Summary of the Invention

A plate handling apparatus comprising: a plurality of plate supports; an actuator; and a plate delivery outlet, characterised in that the actuator arranged to move the plate supports relative to the plate delivery outlet to thereby enable delivery of plates from the plate supports to the plate delivery outlet.

In one example, the actuator is arranged to move the plurality of plate supports relative to the plate delivery outlet such that the plate delivery outlet remains stationary. In one example, the actuator is arranged to move the plurality of plate supports linearly. In one example, the actuator is a linear actuator. In one example, the actuator is arranged to move the plurality of plate supports upwardly and/or downwardly, for example in a vertically upward direction and/or in vertically downward direction. In one example, the actuator is arranged to move the plurality of plate supports together in unison. In one example, the actuator is arranged to move the plurality of plate supports between plate delivery positions, wherein, in each plate delivery position a plate support of the plurality of plate supports is aligned with the plate delivery outlet. In one example, the plurality of plate supports comprises 3 or more plate supports, for example 5 or more, such as 15 or 20 plate supports.

In one example, the actuator is under processor control. In one example, the plate handling apparatus comprises a position sensor for the plate supports, to thereby enable feedback control for the actuator.

In one example, the plurality of plate supports comprises a plurality of support surfaces arranged with one another in a rack. In one example, the plurality of plate supports comprises a plurality of support surfaces arranged offset from one another in one direction, for example in one direction only. In one example, the plurality of plate supports comprises a plurality of support surfaces arranged offset from one another in a direction parallel to the movement direction of the actuator. In one example, the plurality of one direction, of plate supports comprises a plurality of support surfaces arranged offset from one another in a generally vertical direction.

In one example, the plate supports are removable and re-fitable with respect to the rack. In one example, the plate supports are removable and re-fitable with respect to the rack by sliding in and out between rails that engage the edges of the plate supports in use. In one example, the plate supports comprise a support surface on which a plate may rest, in use.

In one example, the plurality of plate supports comprises a plurality of support surfaces arranged offset from one another by more than 15mm, for example by more than 20mm. In one example, the plurality of plate supports comprises a plurality of support surfaces arranged offset from one another by less than 35mm, for example by less than 30mm. In one example, the separation between plate support surfaces is 25mm. In one example, the plate support surface of one plate support is separated from the adjacent plate support by between 3mm and 10mm, for example by 5mm. In one example the plate supports each comprise a plate support surface. In one example, the plate support surfaces are generally planar surfaces. In one example, the plate the plate support surfaces are inclined to the horizontal. In one example, the plate support surfaces are aligned at more than 20 degrees to the horizontal, for example more than 25 degrees, or more than 28 degrees. In one example, the plate support surfaces are aligned at less than 35 degrees to the horizontal, for example less than 30 degrees or less than 29 degrees. In one example, the plate support surfaces are aligned at between 25 and 30 degrees to the horizontal, for example between 28 and 29 degrees. In one example, the plate support surfaces are aligned at 28.35 degrees to the horizontal.

In one example, the plate supports are passive supports, in the sense of comprising no moving parts. In one example the plate support surfaces comprise a low friction material or coating of low friction material. In one example, the low friction material comprises a fluoropolymer, for example PTFE.

In one example, the plate supports comprise an introductory section. In one example the introductory section comprises a tapering element which serves to guide a plate onto the plate support surface and/or between adjacent plate supports.

In one example, the plate supports comprise a rack on which a plate may rest, as an extension of the plate support surface. In one example the introductory section and/or rack comprise a low friction material or coating of low friction material. In one example, the low friction material comprises a fluoropolymer, for example PTFE.

In one example, the actuator is arranged to move the plate supports relative to the plate delivery outlet to align the plate supports with plate delivery outlet. In one example, the plate delivery outlet comprises an opening defined in an outlet surface. In one example the opening comprises a slot.

In one example, the actuator is arranged to move the plate supports between a plurality of delivery positions, corresponding to positions in which a plate support is aligned with the plate delivery outlet.

In one example, the plate supports are arranged to abut an outlet surface, when not aligned with the plate delivery outlet. In one example, the plate supports are arranged such that a plate supported thereon is biased by gravity to move across the plate support surface and toward the plate delivery outlet. In one example, the plate supports are each arranged such that a plate supported thereon is biased by gravity to move across the plate support surface and through the plate delivery outlet when the plate support is aligned with the plate delivery outlet. In one example, the plate supports are each arranged such that a plate supported thereon is biased by gravity to move across the plate support surface and into contact with the outlet surface when the plate support is not aligned with the plate delivery outlet. In one example, the plate handling apparatus comprises a plate mover, such as a conveyor. In one example, the plate handling apparatus comprises a cleaning unit, for example an ultrasonic cleaning tank. In one example, the plate handling apparatus is arranged to deliver plates from the plate supports to the cleaning unit. In one example, the plate delivery outlet is arranged with a plate mover adjacent thereto. In one example, the plate delivery outlet is arranged with a plate mover to receive plates from the plate delivery outlet and to deliver them to the cleaning unit.

In one example, the plate handling apparatus comprises an outlet sensor arranged to sense plates at the plate delivery outlet. In one example the actuator, position sensor and outlet sensor are in operative communication with a processor. In one example, the processor is arranged to control movement of the plate supports by the actuator. In one example, the outlet sensor comprises an optical sensor, or plurality of optical sensors, arranged to detect the presence of a plate at the plate delivery outlet. In one example, the outlet sensor is arranged to detect delivery of a plate at the plate delivery outlet. In one example, the outlet sensor is arranged to detect delivery of a plate to the plate delivery outlet, and passage of a plate away from the plate delivery outlet. In one example, the processor is arranged to control the actuator to move the plurality of plate supports in response to a plate having been delivered from the plate delivery outlet, such as in response to a signal from the outlet sensor. In one example, the processor is arranged to control the plate mover to move a plate delivered to the plate delivery outlet away from the plate delivery outlet.

A plate handling method comprising: loading a plurality of plate supports with plates; and controlling an actuator to move the plate supports relative to a plate delivery outlet, to deliver a plate from the plate supports to the plate delivery outlet.

In one example, the method is performed using a plate handling apparatus as described herein.

In one example the plate handling method comprises moving the plurality of plate supports so that another plate is delivered to the plate delivery outlet from a second plate support from the plurality of plate supports.

In one example the plate handling method comprises: sensing a plate moving from the plate delivery outlet, and in response moving the plurality of plate supports so that a plate is delivered from the next plate support to the plate delivery outlet. In one example the plate handling method comprises: sensing a plate moving from the plate delivery outlet, and in response moving the plurality of plate supports so that another plate is delivered to the plate delivery outlet.

In one example, the method comprises moving the plurality of plate supports relative to the plate delivery outlet such that the plate delivery outlet remains stationary. In one example, the method comprises moving the plurality of plate supports linearly. In one example, the method comprises moving the plurality of plate supports upwardly and/or downwardly, for example in a vertically upward direction and/or in vertically downward direction. In one example the method comprises moving the plurality of plate supports in one direction only during plate delivery, for example upwardly, for example in a vertically upward direction.

In one example, the method comprises moving the plurality of plate supports together in unison. In one example, the method comprises moving the plurality of plate supports between plate delivery positions, wherein, in each plate delivery position a plate support of the plurality of plate supports is aligned with the plate delivery outlet.

In one example, the method is performed under processor control. In one example, the plate handling apparatus comprises a position sensor for the plate supports, and wherein the method comprises providing feedback control for the actuator.

In one example the method comprises loading the plate supports each with a plate that is thus supported on a plate support surface.

In one example, the method comprises moving the plate supports relative to the plate delivery outlet to align the plate supports with plate delivery outlet.

In one example, the method comprises moving the plate supports between a plurality of delivery positions, corresponding to positions in which a plate support is aligned with the plate delivery outlet.

In one example, the method comprises delivering plates from the plate supports to a cleaning unit. In one example, the method comprises operating a plate mover that receives plates from the plate delivery outlet, to deliver plates to a cleaning unit.

In one example, the method comprises detecting the presence of a plate at the plate delivery outlet. In one example, the method comprises detecting delivery of a plate at the plate delivery outlet. In one example, the method comprises detecting delivery of a plate to the plate delivery outlet, and passage of a plate away from the plate delivery outlet. In one example, the method comprises moving the plurality of plate supports in response to a plate having been delivered from the plate delivery outlet. In one example, the method comprises operating a plate mover to move a plate delivered to the plate delivery outlet away from the plate delivery outlet.

Other features of the invention will be apparent from any appended claims, and from the description of example embodiments which follows.

Brief Introduction to the Drawings

For a better understanding of the invention, and to show how embodiments of the same may be carried into effect, reference will now be made, by way of example, to the accompanying diagrammatic drawings in which:

FIG. 1 shows a plate handling apparatus according to an example embodiment, and a plate mover;

FIG. 2 shows the plate handling apparatus of FIG. 1 with all but one plate support of the plurality of the plate supports removed to aid understanding of the construction of the plate handling apparatus;

FIG. 3 shows a plate support for use in the example embodiment of FIG. 1 ; and

FIG. 4 illustrates steps in a method according to an example embodiment.

Description of Example Embodiments

FIG. 1 shows a plate handling apparatus 1 according to an example embodiment, in a perspective view from one side and above. The plate handling apparatus 1 is shown adjacent to a plate mover 100.

The plate handling apparatus 1 comprises a plurality of plate supports 10, an actuator 20 and a plate delivery outlet 30. The plate handling apparatus 1 is set up with a plurality of flexo plates on the plate supports, for example on each plate support 10. By using the actuator 10 to move the plate supports 10 relative to the plate delivery outlet 30, plates are delivered in from the plate supports 10 to the plate delivery outlet 30. From the plate delivery outlet 30 the plates are moved by the plate mover 100, to be delivered into a cleaning unit such as an ultrasonic cleaning tank (not shown). In this way, the proper sequential delivery of plates into the cleaning unit can be automated, with no manual intervention required after the plates to be cleaned are loaded onto the plate supports. In the configuration of FIG. 1 the actuator 20 is extended, and thus able to move the plurality of plate supports 10 downwardly. The plate delivery outlet 30 remains stationary. As the plate supports 10 move down, the lowermost one first achieves a plate delivery position. In the plate delivery position the lower end of the plate support is aligned with the delivery outlet 30.

The plate supports comprise a low-friction PTFE plate support surface that is aligned to the horizontal, such that gravity acts on a flexo plate supported thereon and causes the pate to slide under its own weight to the lowermost part of the plate support. In this position, the flexo plate abuts an outlet surface 12 (see FIG. 2). The outlet surface 12 comprises a slot that forms the plate delivery outlet 30, through which the flexo plate may start to slide when the actuator 20 brings the lowermost plate support 10 down as the actuator 20 moves the plate supports 10 into the first plate delivery position.

The plate support surfaces are aligned at 28.35 degrees to the horizontal in the example embodiment, which has been found to provide optimum performance in facilitating sliding, without causing incidence of folding/bending and while maintaining plate capacity within the plate handling apparatus.

Once the flexo plate has been delivered to the plate delivery outlet 30 from the lowermost plate support 30, in the plate mover 100 carries it away and clear of the plate delivery outlet 30. The actuator 20 then moves the plate supports 10 down to the next plate delivery position, repeating the process of plate delivery to, and then through the plate delivery outlet 30.

To give flexibility in automation, the plate handling apparatus 1 comprises a processor (not shown) in the form of a microcontroller. The processor is coupled to a position sensor (not shown) for the plurality of plate supports 10 that produces a signal representative of the position of the actuator 20, and to an outlet sensor (not shown) at the plate delivery outlet 30 which is arranged to sense flexo plates at the plate delivery outlet 30. The processor is configured to to control the actuator 20 to move the plurality of plate supports 10 after a flexo plate has been delivered out of the way of from the plate delivery outlet 30, as determined by the outlet sensor. The processor is arranged to cooperate with the plate mover 100 to enable the flexo plate delivered to the plate delivery outlet 30 is moved away from the plate delivery outlet 30. As shown, the plate mover 100 is integral with the plate handling apparatus 1 .

As can be seen in FIG.2 and FIG. 3, the plate supports 10 comprise an array of support surfaces 14 arranged with one another in a rack 16. The plurality of plate supports 10 are removable and re-fitable with respect to the rack 16 by sliding in and out between rails 18 that engage the edges of the plate supports 10 in use. Ease of removal and re-fitting the plate supports 10 is helpful for easy inspection and cleaning of the plate handling apparatus 1.

To aid in an initial loading process, the plate supports 10 comprise an introductory section 22 that comprises a tapering element 24 which serves to guide a flexo plate onto the plate support surface from a rack 26 associated with that plate support 10.

FIG. 4 illustrates steps in a method according to an example embodiment. At step S101 the method comprises load a plurality of plate supports with flexo plates. At step S102 the method comprises controlling an actuator to move the plate supports relative to a plate delivery outlet, to thereby deliver a plate from a plate supports to the plate delivery outlet. The method may further comprise step S103 of controlling the actuator to stop as the first plate clears the plate delivery outlet, then to move the plate supports relative to a plate delivery outlet to deliver a plate from a second plate support to the plate delivery outlet. As will be appreciated, the method is conveniently performed with a plate handling apparatus as described herein.

The plate handling apparatus and methods described herein are useful in eliminating the requirement for individual manual handling of flexo plates over a period when flexo plates are to be provided into a cleaning process. The apparatus has minimal moving parts and provides reliable delivery of flexo plates even accounting for different size, thicknesses and degree of ink residue on the plates.

Attention is directed to all papers and documents which are filed concurrently with or before this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

All the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features. The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.