EP3121017B1

EP3121017B1 - Machine for printing simultaneously on two parallel surfaces

Info

Publication number: EP3121017B1
Application number: EP16171933.1A
Authority: EP
Inventors: Victor LIMIÑANA OROBITG
Original assignee: VL Limitronic SL
Current assignee: VL Limitronic SL
Priority date: 2015-06-26
Filing date: 2016-05-30
Publication date: 2019-11-20
Anticipated expiration: 2036-05-30
Also published as: ES2550727A1; EP3121017A1; ES2769247T3; ES2550727B1

Description

OBJECT OF THE INVENTION

The present invention describes a printer for simultaneously printing decorative elements, graphics or informative legends on two parallel surfaces of a three-dimensional object. Moreover, the printer that is the object of the invention can be used on a wide range of products.
It is of particular use for printing on packaging, especially cardboard packaging.

TECHNICAL PROBLEM TO ADDRESS AND BACKGROUND OF THE INVENTION

There are a large number of printers and methods used by these machines in the state of the art. Although the advancements in the field of printing have been quite significant concerning the versatility of printers, accessibility and ease of use by staff who do not need to be highly qualified, that is by any kind of user, there are still several needs that have not been addressed and that represent a series of deficiencies in the technological advancement in the field.
There are known printers that are able to print on both sides of a flat surface. These printers are aimed at printing bi-dimensional components, typically paper, and they have seen great improvements.
However, printing three-dimensional objects has not seen the same improvements as bi-dimensional printers and, although it is a growing need in the industry, it still experiences a series of deficiencies such as the limitation of having to print graphics on a single surface, and the need to specifically regulate the format of the object by placing the printheads on the desired area so that the printout coincides with the object to be printed on.
In order to be able to adapt the printout to other surfaces, the printer must be readjusted beforehand.
If the opposite surfaces of an object need to be printed on, another printer set on the opposite side of the object must be used so that each printer operates on one of its surfaces.
All of this makes the printing processes slower and more difficult, especially when it comes to packaging, when the volume of units that need to be printed is generally quite high.
In the current state of the art, when boxes or packages normally made of cardboard need to be printed, printing companies do this by using conventional techniques in order to meet the large print runs. These techniques include flexography, tampography, screen printing, rotogravure, etc.
These large print runs affect the versatility of printers when the design of the packaging needs to be changed or modified when a new product is printed, due to the large volumes of models in stock of the different models and types of products being packaged.
Moreover, nowadays it is common to see even in retail stores the boxes of bulk products or secondary packaging, as display stands, which makes it advisable to incorporate some kind of design or graphic that relates to the contents of the box.
The machine that is the object of the invention makes it possible to decorate and customise packaging to the highest level since it is possible to decorate pre-decorated packaging or boxes with specific graphics for different products, saving manufacturers from having to store multiple stocks and also giving them the capacity to work with smaller batches without having to use other customisation methods such as adhesive labels.
The present invention addresses these problems that still have not been addressed by the current state of the art by introducing a printer for printing simultaneously on two surfaces, with a high capacity to print objects and a high adaptability for printing objects of multiple formats thanks to its ability to modify the structure of the machine so that it can print on surfaces of any size or kind, in a simple and easy way. There are no known devices in the state of the art that are capable of decorating packaging with the adaptability and versatility described herein.
Document US4814795 discloses an ink jet head holder supported from a frame that includes a transversely movable rod supporting an ink jet print head with a similar print head holder on the opposite side of the frame. A conveyor for conveying an object having opposed print-receiving surfaces between the print heads. Longitudinal channels are supported by the frame on opposite sides of the conveyor. The print heads are supported on the longitudinal channels and side guide rails are also supported on the channels. The channels are laterally movable to vary the width of the path of packages on the conveyor. The side guide rails are also adjustable laterally relative to the print heads. The print heads have cam faces for contacting the packages at a predetermined transverse distance from the print head nozzles. Biasing means hold the print heads with the cam faces bearing against the print-receiving surfaces that are printed by ink from the nozzles.
Document EP1974928 discloses a device (1) that has a printer (10) i.e. ink-jet printer, imprinting a surface of a three-dimensional article e.g. plate, and a conveyor bringing about a relative movement between the printer and the article to be imprinted. A surface of the article to be imprinted is brought into a predetermined relative relationship to the printer by a positioning unit (30). The printer has a set of printing units (12, 14) that are associated with respective stop elements e.g. stop rolls. The positioning unit has two stop elements, where one of the stop elements is movable. An independent claim is also included for a method for imprinting a container.
Document US5101224 discloses a pair of ink jet print heads that are arranged on opposite sides of a conveyor to apply ink markings to the opposed surfaces of material conveyed on the conveyor. The print heads support ink jet nozzle blocks having at least one ink jet nozzle and are pivotally biased out over the conveyor in the path of the conveyed material. A pair of cams positioned on opposite sides of the ink jet nozzle blocks maintain a critical spacing between the nozzle block and the surface of the material. Ramp surfaces and an exit cam control the rate at which the ink jet print heads are pivoted away from and toward the path of the conveyed material as the material is conveyed before the ink jet print heads.

DESCRIPTION OF THE INVENTION

The present invention describes a printer for printing simultaneously on two parallel surfaces of a three-dimensional object. The printer comprises a conveyor belt, a centring station, a printing area and a control unit.
The conveyor belt is in charge of transporting the objects to be printed and comprises means for extension in order to modify the height of the conveyor belt in relation to the printheads.
The centring station features two centring structures placed symmetrically in relation to the longitudinal axis of the conveyor belt, which overlaps the conveyor belt along its length. The function of the centring station is to collect the objects to be printed and centre them on the conveyor belt. In order to do so, the centring structures comprise centring components on which the objects slide while transported by the conveyor belt. The centring structures have the capacity to draw closer together or further apart by means of a fitting device that can be connected to each of the centring structures or to the assembly, so that both move simultaneously. The centring structures also comprise means for extension in order to modify the height of the guiding components.
The printing area comprises two mobile bases, each of them comprising at least one printhead. The mobile bases are located at each side of the conveyor belt and have the capacity to move in both the perpendicular directions to the longitudinal axis of the conveyor belt by means of an actuator and one lift respectively.
The assembly of the actuator and the lift can also operate on each of the mobile bases or on both bases at the same time if they are adequately connected.
The control unit comprises means to obtain data about the dimensions of the object to be printed, which have an effect on the actuation of the devices influencing the configuration of the centring station and the mobile bases. It also receives data from the photocells in order to activate the printheads and the light emitters.

BRIEF DESCRIPTION OF THE FIGURES

To complete the invention being described, and in order to help with better understanding of the characteristics of the invention, according to a preferred embodiment thereof, it is accompanied by a set of drawings in which the figures described below have been represented, for purely illustrative purposes and should not be construed as limiting:

Figure 1 is an upper front perspective view of the printer that is the object of the invention.
Figure 2 is a plan view of the printer that is the object of the invention.

A list of the references used in the figures is provided below:

1. Conveyor belt.
2. Centring station.
3. Centring structure.
4. Guiding components.
5. Mobile base.
6. Printheads.
7. Fitting devices.
8. Actuator.
9. Lift.
10. Light emitter.
11. Photocell.

DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION

The present invention describes a printer for printing simultaneously on the two lateral, parallel surfaces of a three-dimensional object.
As shown on figures 1 and 2, the printer that is the object of the invention comprises a conveyor belt (1), preferably placed horizontally, that transports the objects about to be printed. The objects enter the conveyor belt (1) through a centring station (2) that overlaps with it, and that comprises two centring structures (3) placed symmetrically in relation to the longitudinal axis of the conveyor belt (1).
The centring structures (3) are placed symmetrically in relation to the longitudinal axis of the conveyor belt (1) and separate significantly at the mouth in order to create a wider entrance point, so that the objects to be printed can easily enter the device. Each of the centring structures (3) comprises a series of guiding components (4) to position the object to be printed.
The guiding components (4) located on the centring structures (3) can be, for example, horizontal rows with a plurality of rollers positioned with their axes in vertical position, so that the products slide laterally on the surface of the rollers while the conveyor belt (1) transports them along, centring them in the desired position.
In one embodiment of the invention, several fitting devices (7) trigger the lineal movement of the centring structures (3) along guides, so that they can draw closer together or further apart depending on the transverse dimension existing between the surfaces of the object to be printed.
In another embodiment of the invention, with the aim of centring the object to be printed in relation to the longitudinal axis of the conveyor belt (1), the centring structures (3) are joined together so that a single fitting device (7) operates on the centring structures (3), which move symmetrically.
In another embodiment, the height of the structures (3) of the centring station (2) may be modified by extension means, which are not shown on the figures, and that modify the distance between the guiding components (4) along the length of several guides depending on the height of the object to be printed.
In another embodiment, the printer that is the object of the invention comprises extension means, which are not shown on the figures, which modify the height of the conveyor belt (1) all along the guides, allowing the height of the conveyor belt (1) to be changed so that the printer is adaptable to objects of different heights.
The printer comprises a printing area where two groups of printheads (6) are located on each of the respective mobile bases (5). Even though each group can comprise a single printhead (6), they will preferably comprise several printheads aligned preferably in relation to the direction the conveyor belt (1) moves. The mobile bases (5) are located facing each other at both sides of the conveyor belt (1), and although they are not necessarily symmetrical, they are separated symmetrically from the longitudinal axis of the conveyor belt (1).
In one embodiment, each of the mobile bases (5) comprises an actuator (8) and a lift (9) in order to move the object along a series of guides on the two directions perpendicular to the longitudinal axis of the conveyor belt (1) respectively, these directions preferably being vertical and horizontal respectively.
In another embodiment, with the aim of centring the object to be printed in relation to the longitudinal axis of the conveyor belt (1) as was the case for the centring structures (3), the mobile bases (5) are joined together so that a single actuator (8) and a single lift (9) operate on the mobile bases (5), them moving symmetrically along each of the two directions in relation to the longitudinal axis of the conveyor belt (1).
The printer that is the object of the invention also comprises light emitters (10) that will preferably emit ultraviolet light and that will activate once the printout has been performed. They will preferably be located on each of the mobile bases (5). The light emitters (10) are activated to cure the ink when printing on surfaces that are not very porous and when the ink requires an additional curing or drying treatment. For this reason, they should be located somewhere behind the groups of printheads (6) in relation to the direction the conveyor belt (1) moves.
In order to trigger the printheads (6) and the light emitters (10), the printer that is the object of the invention comprises a photocell (11) that detects the arrival of an object to be printed. The photocell (11) is located on a lane, preferably parallel to the conveyor belt (1), and is attached to a mobile base (5) so that it can be moved in order to determine how close it needs to be in relation to the printheads (6). Even though a single photocell (11) is normally enough, two photocells (11) can be included, one on each side of the mobile base (5), in order to trigger the printheads (6) and the light emitter (10), which are located on the respective sides of the conveyor belt (1).
The transverse dimension of the object between the two parallel surfaces to be printed and the vertical length of the surfaces to be printed are key data for programming the printer that is the object of the invention, since they allow it to have the versatility it seeks. This data is used to program the fitting devices (7) of the centring station (2), the means for moving the mobile bases (5), both the actuator (8) and the lift (9), and the means for extension in order to modify the height of the conveyor belt (1) or the existing centring structures (3) depending on the embodiment of the invention, so that they are positioned in the appropriate place for printing the object.
It should be taken into account that the movement and the position of the structures (3) of the centring station (2) are independent in relation to the mobile bases (5) of the printheads (6). Similarly, the movement and position of both the structures (3) of the centring station (2) and the mobile bases (5) are completely independent in relation to the conveyor belt (1). This gives it the capacity to place the structures (3) of the centring station (2) and the mobile bases (5) in the necessary position for each situation, granting them absolute freedom of movement.
The printheads (6) also have the capacity to move vertically all along the height of the object to be printed, and they are also capable of printing at zero level of the object, which is the level of the conveyor belt (1). This is the reason why the width of the conveyor belt (1) is smaller than the width of the object to be printed, which protrudes from the conveyor belt (1) on both sides.
This is also the reason why the centring station (2) is located before the printheads (6) in relation to the movement of the conveyor belt (1), so that they do not interfere with each other.
In one of the embodiments of the invention, the printheads (6) are aligned but positioned alternately so that there are two areas projecting ink at different heights.
The printer that is the object of the invention also comprises a control unit in charge of processing all the information regarding the positioning and activation of the different devices, which are controlled electronically.
The control unit comprises means to collect data about the object to be printed, primarily in relation to its dimensions. The information is then sent to the control unit by means of, for example, reading the dimensions of the object using a computer vision device, reading an identification code or sending the data from an external device or from a data base.
This information determines how the printer modifies its printing parameters in relation to the object about to be printed, regulating the devices in charge of positioning the centring station (2) and the mobile bases (5) and, more specifically, the fitting devices (7) of the centring structures (3), and the actuators (8) and the lifts (9) of the mobile bases (5), and the means for extending the height of the centring structures (3) or the conveyor belt (1).
The control unit is also connected to the light emitters (10), which will be triggered depending on the type of packaging to be printed, as described above, and the photocells (10), which will determine when the printheads (6) will be triggered.
Additionally, the printer can be programmed to only modify the printed design in those cases when the same object is used for different situations such as, for example, printing the same message in different languages.
The present invention is not limited by the embodiment disclosed herein. Other embodiments can be made by experts in the art following the present description. In consequence, the scope of the invention is defined by the following claims.

Claims

Machine for printing simultaneously on two parallel surfaces of a three-dimensional object, comprising:
- a conveyor belt (1),

- a centring station (2) comprising two centring structures (3) placed symmetrically in relation to the longitudinal axis of the conveyor belt (1), which overlaps the conveyor belt (1) longitudinally,

- a printing area comprising two mobile bases (5), each mobile base (5) having at least one printhead (6) and located at each side of the conveyor belt (1),

- two fitting devices (7),

- two actuators (8),

- two lifts (9), and

- a control unit,
wherein,

- the centring structures (3) have the capacity to draw closer together or further apart by means of the two fitting devices (7),

- the mobile bases (5) have the capacity to move in both directions perpendicular to the longitudinal axis of the conveyor belt (1) by means of the two actuators (8) and the two lifts (9), respectively, and

- the control unit comprises means to collect data about the dimensions of the object to be printed, said data determining the configuration of the centring station (2) and the location of the mobile bases (5) of the printheads (6), the collected data determining how the printer modifies its printing parameters in relation to the object about to be printed, the printing parameters regulating the following devices:
- the fitting devices (7) of the centring structures (3),

- the actuators (8) and the lifts (6) of the mobile bases (5), and

- means for extending the height of the centring structures (3) or of the conveyor belt (1); said different devices being controlled electronically.
Machine for printing simultaneously on two parallel surfaces according to claim 1, characterized in that it comprises at least one photocell (11) to detect an object to be printed.
Machine for printing simultaneously on two parallel surfaces, according to any of the claims 1 or 2, characterized in that it comprises at least one light emitter (10) in order to dry the printout.
Machine for printing simultaneously on two parallel surfaces, according to any of the claims 1 to 3, characterized in that it comprises extension means in order to modify the height of guiding components (4).
Machine for printing simultaneously on two parallel surfaces, according to any of the claims 1 to 3, characterized in that it comprises extension means in order to modify the height of the conveyor belt (1) in relation to the printheads (6).
Machine for printing simultaneously on two parallel surfaces, according to claim 2, characterized in that the at least one photocell (11) is in charge of triggering the printheads (5) and the light emitters (10).