EP1350621A2

EP1350621A2 - Improved drum for flexographic printing

Info

Publication number: EP1350621A2
Application number: EP02027045A
Authority: EP
Inventors: Francisco Sanchez Beltran; Luis Rios Segura
Original assignee: Grupo Basgra Maquinaria Ceramica SL
Current assignee: Grupo Basgra Maquinaria Ceramica SL
Priority date: 2002-04-01
Filing date: 2002-12-03
Publication date: 2003-10-08
Also published as: EP1350621A3

Abstract

Improved printing drum for flexographic printing that is made up of a drum (1) covered with a printing sheet (2) fixed to the drum by a retaining device (3), said printing sheet (2) having a rim arranged on the longitudinal edges of the outer face of same. The rims coinciding with the with edge of the pottery in order to paint said edge.

The retaining device (3) is held longitudinally on the drum (1) and consists of a lower support element (4) and some retaining plates (5) that fix the edge of the printing sheet to the lower support element (4). In turn, the device is fitted with an upper cover (6), which is made of a sheet element that respectively has a tab bent over on its two longitudinal sides.

Description

AIM OF THE INVENTION

The aim of this application is to register an improved drum for flexographic printing that incorporates significant innovations and advantages compared to the present printing drums.
More specifically said drum consists of a printing sheet capable of printing on the edge of the pottery and a system of retaining same.

BACKGROUND TO THE INVENTION

At the present time there are differing techniques available on the market for printing onto surfaces such as silk-screening, photogravure and others. Specifically, in recent times there has been a great surge in the technique of flexography as a result of its speed in production and the quality obtained.
For the printing and drawings or designs onto the pottery, printing machines are used that are made up of one or more drums. Said drums have the inked flexographic sheet rolled onto their outer surface. This sheet is made up mainly of a polymer or similar compounds.
One disadvantage that these sheets have, is the difficulty in the retaining of the sheet onto the drum; which in general is by means of clamps, bolts, etc., which makes subsequent handling of the sheet difficult when its re-use is required, even the drum itself.
Another disadvantage is that the sheets have an external arrangement that does not allow for the printing of designs onto the edges or rims of pottery. This limits the type of drawing that can be printed or requires the need for a second process for the painting of same.

DESCRIPTION OF THE INVENTION

The improved drum, object of this present registration, for flexographic printing, eliminates the above stated disadvantages, both in regards the retention of the sheet and equally the printing onto the edges of pottery. This is because the drum has a reliable and convenient retaining device for the printing sheet, and a printing sheet capable of being used to print onto the edge of pottery.
The retaining device is held longitudinally on the drum for the housing of the elements that will retain the ends of the sheet. This will be carried out in such away that these elements do not protrude the shape. Said retaining elements are made up of a lower support element, which is screwed directly onto the drum, and has tow rows of openings for the anchoring of some plates that retain the edge of the printing sheet with the lower support element.
Each fixing plate or element is made up of an element that extends along the length of the printing sheet.
More specifically each plate has some openings with countersinking for the insertion of an anchoring bolt for this plate to the support element. Along the lower outer edge of the support there is an stepped arrangement to receive the edge of the printing sheet. On the opposite side of this arrangement there is a protruding rib, in such a way that as the screws are tightened the plate progressively applies pressure to the stated edge of the sheet.
In order to protect the device from the ink and from contact with the piece, an upper cover has been provisioned that is made up of a sheet element and which has its two longitudinal sides respectively bent over in a tab. This means that the retaining device remains below the surrounding level generated by the continuity of the external surround of the sheet in the cradle in which it is held.
In order to make the centring of the sheet easier, a series of protrusions have been provisioned on the edge and arranged at regular intervals. These protrusions are arranged in a combined manner with some hollows located in the groove for the trapping of the plate that holds said edge. In this way, on assembling the sheet onto the drum, it will be perfectly centred and said protrusions fitting into the corresponding countersinks and mortises.
On the other hand, the printing sheet is fitted with two rims arranged on the longitudinal edges of the outer face of same. On the internal face of said rims, in contact with the pottery, there is a shape, which coincides with the edge of the pottery, thus enabling the painting of same. The rim diminishes in thickness in a progressive way towards the edge of the sheet.
In order to complete the description that is going to be made below and for the purpose of helping to give a greater understanding of its characteristics, the present description is accompanied by a set of drawings, which are by way of illustration and not by way of limitation, where the most significant details of the invention are represented.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1. Showing a perspective view of the drum of the new invention.
Figure 2. Showing a section view of the improved drum.
Figure 3. Showing a section view in detail of the retaining device of the printing sheet.
Figure 4. Showing a partial view in elevation of the retaining plate.
Figure 5. Showing a partial profile view of the retaining plate.
Figure 6. Showing a view in elevation of the printing sheet.
Figure 7. Showing a partial profile view of the printing sheet.

DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION

In light of the commented on figures and in accordance with the adopted numbering, a preferred embodiment of the invention can be seen in same, however it is not by way of limitation on the invention. This consists of an improved printing drum (1) for flexographic printing that is made up of a printing sheet (2) and a retaining device (3) for the printing sheet (2).
The retaining device (3) is held longitudinally on the drum (1) for the housing of the elements that retain the edges of the sheet (2). Said retaining elements consist of a lower support element (4), which is screwed directly to the drum (1), and which has a series of openings (7) for the anchoring of the plates (5) that hold the edge of the printing sheet (2) with the lower support element (4).
Each fixing plate or element is made up of an element that extends along the length of the printing sheet.
More specifically each plate has some openings with countersinking (8) for the insertion of an anchoring bolt (9) for this plate to the support element. Along the lower outer edge of the support there is an stepped arrangement (10) to receive the edge of the printing sheet (2). On the opposite side of this arrangement (10) there is a protruding rib (11), in such a way that as the screws are tightened the plate progressively applies pressure to the stated edge of the sheet.
The plate has a series of spaced slots (12) centred on the bottom of the mentioned groove (10). Some protrusions (13) on the edge of the printing sheet (2) are housed in these slots (12).
The device is fitted with an upper cover (6), which is made of a sheet element that respectively has a tab bent over on its two longitudinal sides.
On the other hand, the printing sheet (2) is fitted with two rims arranged on the longitudinal edges of the outer face of same. On the internal face of said rims, in contact with the pottery, there is a shape, which coincides with the edge of the pottery, thus enabling the painting of same. The rim diminishes in thickness in a progressive way towards the edge of the sheet.

Claims

Improved drum for flexographic printing, which comprises of at least a drum (1) with a covering of a printing sheet (2) held onto the drum by means of a retaining device (3) that is characterised in that the printing sheet (2) has a rim on both longitudinal sides in order to paint the edge of pottery.
Improved drum for flexographic printing according to the previous claim, characterised in that the retaining device (3) is cradled longitudinally on the drum (1).
Improved drum for flexographic printing according to the previous claims, characterised in that the retaining device (3) is made up of a lower support element (4), which is screwed directly onto the drum (1).
Improved drum for flexographic printing according to the previous claims, characterised in that the lower support element (4) has a series of opening (7) for the anchoring of the plates (5) that retain the printing sheet (2) edge with a lower support element (4).
Improved drum for flexographic printing according to the previous claims, characterised in that each plate is comprised of some countersunk openings (8), and because an anchoring bolt (9) is inserted into each countersunk opening.
Improved drum for flexographic printing according to the previous claims, characterised in that each support element has a groove (10) present on the lower outside edge for the housing of the edge to the printing sheet (2), and because on the opposite side there is a protruding rib (11).
Improved drum for flexographic printing according to the previous claims, characterised in that the plate has a series of slots (12) arranged on the rear of the groove (10); and because some protrusions (13) in the edge of the printing sheet (2) are housed in these slots.
Improved drum for flexographic printing according to the first claim, characterised in that the retaining device (3) has an upper cover (6); and because the upper cover (6) is made up of a sheet element, which respectively has a tab, bent over on its two longitudinal sides.
Improved drum for flexographic printing according to the first claim, characterised in that the printing sheet (2) is fitted with two rims, arranged longitudinally on the outer edge of same; and because these rims on the internal face, in contact with the pottery, have a shape which coincides with that of the edge of the pottery.
Improved drum for flexographic printing according to the first and ninth claim, characterised in that the rims progressively reduce in thickness towards the edge of the sheet (2).