Vacuum system for securing items in printing machines

Abstract

The invention relates to a vacuum system for securing items in printing machines, comprising a printing table (2) with a perforated surface and, in relation thereto, a vacuum system for securing the items to be printed, which comprises a box structure (8) connected to a suction system and provided with a perforated wall in relation to the surface of the printing table (2), said box structure (8) having lateral panels that vertically close the interior thereof, which panels can be moved in order to adjust the gap between them in relation to the width of the items to be printed.

Claims

1. A vacuum system for securing items in printing machines, comprising a printing table having a perforated surface, in relation to which there is arranged a vacuum system for securing on said printing table the items to be printed, wherein the vacuum system comprises a box structure connected through nozzles with a suction system from the intermediate area of its transversal width, said box structure having an upper perforated wall opposite the perforated surface of the printing table, whereas in the interior thereof there are arranged lateral panels that vertically close in a sealed manner said interior of the box structure, which lateral panels can be moved transversally to move them closer to and farther away from one another inside the box structure, an actuation system being linked to said panels in order to move them, wherein a longitudinal extension of the box structure is divided into a plurality of independent successive chambers in which different vacuum pressures are applied for securing items to be printed, a first force being applied in an inlet area where the items are positioned on the printing table, a second force weaker than the first force being applied in a printing area where the items are printed, and a third force weaker than the second force being applied in a removal area where the items that are removed after having been printed.

2. The vacuum system for securing items in printing machines according to claim 1, wherein the actuation system for moving the lateral panels comprises a motor driving a transmission shaft which is linked by means of couplings with screws moving the lateral panels.

3. The vacuum system for securing items in printing machines according to claim 1, wherein the drive of the actuation system for moving the lateral panels is controlled automatically depending on the dimensions of the items to be printed by means of coordinates provided by a detection system through which the items pass when they are located on the printing table.

Description

DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows a side elevational schematic view of an embodiment of a printing machine provided with the vacuum system object of the invention.

(2) FIG. 2 shows a corresponding plan view with respect to the preceding figure.

(3) FIGS. 3 and 4 show respective schematic plan views of the box structure of the vacuum system of the invention in respective positions for regulating application of the vacuum for items having two different widths.

(4) FIG. 5 shows a perspective view of an embodiment of a printing table with the vacuum system object of the invention.

(5) FIG. 6 shows a perspective longitudinal section view of the printing table in the preceding figure.

(6) FIG. 7 shows an enlarged cross-section view of the same printing table, according to a corresponding section through the area of a nozzle of the suction system.

(7) FIG. 8 shows a cross section of the printing table through an area corresponding to a screw for moving the lateral partitions for vertically closing the vacuum box structure.

DETAILED DESCRIPTION OF THE INVENTION

(8) The present invention relates to a vacuum system for securing items (1) in printing machines, for example of the type comprising a printing table (2) formed by a conveyor belt (3) which is operated by a drive motor (4) and determines a perforated support surface for supporting the items (1) to be printed, there being arranged above said printing table (2) a printing ink propelling system (5), whereas a vacuum system is arranged below the perforated support surface for supporting the items (1) to be printed; there being arranged in front of the printing table (2) a feed system (6) for feeding the items (1) to be printed, which can be independent items or a continuous sheet, and there being arranged behind said printing table (2) a delivery system (7) for delivering the printed items (1).

(9) The vacuum system comprises a box structure (8) connected by means of nozzles (9) with a suction system from the intermediate area of its transversal width, said box structure (8) having an upper perforated face which is located below the perforated surface of the printing table (2) on which the items (1) are arranged for printing, such that the vacuum produced by the suction system in said box structure (8) causes suction through the upper face thereof and through the support surface for supporting the items (1), securing said items (1) on said support surface to keep them in place during the printing process.

(10) Inside the box structure (8) there are arranged lateral panels (10) that vertically close said interior of the box structure (8) in a sealed manner, said lateral panels (10) being incorporated in a sliding assembly for moving the box structure (8) transversally by means of an actuation system, such that said lateral panels (10) can be moved closer to and farther away from one another.

(11) The actuation system for actuating the moving lateral panels (10) that vertically close the box structure (8) comprises a motor (11) driving a transmission shaft (12) arranged on one side along the box structure (8), said transmission shaft (12) being linked by means of couplings (13) with transverse screws (14) associated with the lateral panels (10) of the interior of the box structure (8), in relation to which said screws (14) generate inverse coupling relations, such that when rotated in one direction, they cause said lateral panels (10) to move closer to one another and, by rotation in the opposite direction, they cause said lateral panels (10) to move farther away from one another. To that end, the screws (14) are linked with the lateral panels (10) through threaded couplings (15) having opposite thread directions.

(12) Therefore, in order to adapt the vacuum system in the printing table (2) according to the width of the items (1) to be printed, the screws (14) are driven by means of the motor (11) through the transmission shaft (12), which screws (14) move the lateral panels (10) transversally through the interior of the box structure (8) to the position corresponding with the width of the item (1) arranged on the printing table (2), thereby determining that the action of the vacuum only affects the area covered by the item (1) to be printed, the lateral areas of the surface of the printing table (2) not being covered by the item (1) unless the vacuum is applied therein.

(13) In the inlet area for arranging the items (1) to be printed on the printing table (2), there is arranged a detection system (16) which determines the length, width and position of said items (1) as they pass therethrough, generating coordinates that allow precisely controlling the propelling of the inks for the printing to be done, as well as automatically controlling the positioning of the lateral partitions (10) in the interior of the box structure (8) in order to adjust the vacuum system to the width of the items (1) arranged on the printing table (2) to be printed.

(14) According to a practical embodiment, in order to assure perfect positioning of the items (1) when they are placed on the printing table (2) and to determine precise conditions for securing same as they pass through the printing area and when they are released in the delivery area, it is envisaged that the longitudinal extension of the box structure (8) is divided into three independent successive chambers, each one connected with the suction system by means of one or more nozzles (9), to determine, by means of a control for regulating said suction system, different vacuum pressures in the successive chambers for securing the items (1) in the inlet area where the items are positioned on the printing table (2), greater force being applied than in the printing area and less force being applied in the area where the printed items (1) are removed.