GB2286799A - Apparatus for decorating ceramic tiles - Google Patents

Description

2286799 1 A Decorating Device for Ceramic Tiles.

The invention relates to a decorating device for ceramic tiles.

Ceramic tiles are decorated by means of matrices or plates of various types, on which the design to be transferred on the tiles is made. Such devices then transfer glaze on to the tiles themselves.

Rotary cylindrical silk screens are well known in this field, wherein the matrix is constituted by the lateral holed surface of the screen. The tiles advance on a conveyor towards the drum of the screen, which latter then rolls on the surface of the tile and deposits the glaze thereon.

The glaze contained inside the screen drum is pushed externalwise (through the holes in the screen) by spatula devices so that the glaze then passes on to the surface of the tiles.

By synchronizing the motion of the screen-drum and the tile advancement along the conveyor any possible dragging between a portion of the external surface of the cylinder and the face of the tile to be decorated is obviated.

other known realizations include those where the 2 decoration of the tile is performed with a transfer system, widely used in publishing and paper printing, wherein the decoration is etched either directly on a roller which then contacts the tile surface, or on a rotary copper plate, which is supplied with glaze and which is in contact with an underlying intermediate transfer roller, also rotary, which comes directly into contact with the tile and transfers thereon the decoration as received from the copper plate roller.

All of the above-illustrated decorating devices, both those using the transfer device and those using a rotary cylindrical silk screen, present some drawbacks.

In silk screen devices, for example the relevant area of external surface of the screen must be constantly cleaned of all traces of glaze (which inevitably remain there), so that a next application will be guaranteed free of defects.

Transfer-type devices, which as has already been mentioned derive from printing machines which operate on continuous supports and have their rollers in continuous movement, are suitable for use only with certain applications. In particular 3 they are utilizable almost exclusively for veining stone-type materials, or marble, or the like. Use with tiles, which in effect present a discontinuous surface, plays havoc with these devices due to great difficulty in exactly positioning the image or decoration on the tile surface.

The main aim of the present invention is to eliminate the above-mentioned drawbacks by providing a decorating device presenting no cleaning problems such as those characteristic of silk-screening devices, and which achieves perfectly defined and accurate decorations on the tile surface.

A notable advantage of the invention is that various different images can be printed on a same production line.

These aims and advantages and others besides are all attained by the present invention, as it is characterized in the accompanying claims, which comprises a conveyor for the tiles and a drum, provided with discontinuous rotary motion which is synchronized with the conveyor motion, on the surface of which drum exhibits a lateral surface whereon are arranged decorations to be printed 4 etched on pads, between which pads channels are provided: a roller glazing device, provided with a glazing roller having a parallel axis to an axis of the drum, transfers the glaze to the pads arranged on the drum, and is arranged at such an angle to the drum as to be positioned over one said channel whenever the drum stops.

Further characteristics and advantages of the present invention will better emerge from the detailed description that follows, of an embodiment of the invention, illustrated in the form of a non-limiting example in the accompanying drawings, in which:

figure 1 shows a schematic vertical elevation of the decorating device of the invention; figure 2 is a schematic view from above of the decorating device.

The decorating device of the invention comprises a conveyor 1 which is inserted along a conveyor line bearing tiles 2 (conveyor line not illustrated). The conveyor 1 is provided with collecting and drawing elements 3 which position the tile 2 correctly on the conveyor 1. A drum 4 is arranged above the conveyor 1, which drum 4 has an axis arranged perpendicular to an axis of the t_ advancement direction of the conveyor 1, and which drum 4 is provided with discontinuous rotary motion synchronized with the conveyor 1 motion. The images or decorations to be printed are arranged on the lateral surface of said drum 4.

Known-type synchronization means produce said discontinuous rotation of the drum 4 such that when a tile 2 arrives in proximity of the drum 4, said drum 4 rotates, coming into contact on one of its generatrices with the tile 2 such as to transfer the image etched on the drum on to the tile 4 itself. Usually a sensor 7 is provided to verify the presence or otherwise of a tile 2 and to set the drum 4 in movement accordingly, should a tile 4 not be present, the drum 4 does not rotate but remains in waiting for a tile 4.

This synchronization mechanism of the conveyor 1 and the drum 4 is of known type and is normally used for slik-screening of a tile surface; the drum 4 of the invention differs from that used in silkscreening in that it is not provided with screens but is a simple drum on which lateral surface a pad or pads 4a exhibiting patterns are arranged, of the type used in the technique known as transference.

1 6 Between one pad 4a and a successive pad 4a, or between the start and the end of the pad 4a in a case where only one such is arranged on the drum 4, channels 4b are sunk, arranged along the generatrices of the drum 4. Briefly, at the channel 4b position, the drum 4 exhibits a slightly smaller diameter than at the drum plus pad 4a position. The channels 4b can be sunk very simply by arranging the pads 4a at a distance one from a next. Should the pad 4a not be thick enough for this, or if the pad is so long as to cover the entire length of the drum 4 lateral side, said channels 4b can be obtained by mechanical or chemical means, or the like.

The decorating device further comprises a roller glazing device 5, provided with a glazing roller Sa and a fountain roller 5b, partially immersed in a bath Sc containing the glaze. A motor 6, independent of the means used to drive the drum 4 and the conveyor 1, continuously drives the glazing device 5 rollers; thus the glaze picked up by the roller 5b from the bath 5c is transferred, by non-dragging rotary contact, to the glazing roller 5a, which is thus continously covered by a thin film of glaze.

A 7 The motor 6 is however synchronized with the drum motion 4 such as to obtain the same peripheral speed for the glazing roller 5a as for the drum 4 when this latter is in motion.

The angular position of the glazing roller 5a with respect to the drum 4 is such that when the drum 4 stops the roller 5a is always positioned at one of the channels 4b. Obviously the arrangement of the pads 4a on the drum 4 will be such that the drum 4 always stops with the channels 4b at a same position.

For example, in figure 1 it can clearly be seen that the drum 4 is provided with two pads 4a divided by channels 4b arranged diametrically opposite each other. The drum 4, each time that the presence of a tile 2 is signalled, turns by half a revolution such as to transfer the alreadyglaze-loaded image on the right pad 4a on to the tile 2 situated under the drum 4, and at the same time to glaze the left pad 4a ready for contact with the next tile. At each half-revolution the channels 4b are alternatively arranged either at the position of the glazing roller 5a or in a diametrally opposite position thereto.

By increasing the drum 4 diameter, or when 8 is decorating small tiles, three, four or even more pads 4a can be arranged on the drum (all with channels 4b between them); the pads 4a can bear different designs, notwithstanding the fact they are situated on a same production line.

The decorating device of the invention does not emply silk screens, and therefore eliminates all problems connected with cleaning of screen holes typical of such screens.

The device further utilizes a transportersynchronized drum device which permits decoration of distinct, that is, non-continuous elements such as tiles, and positions the decoration to be reproduced on the tiles perfectly. Thus it is possible to transfer decorations constituted by precise figures or images, not only decorative patterns which are to be casually reproduced on the tiles, as was usually the case with transfer decoration devices of known type.

The presence of channels 4b, fundamental for obtaining good results, prevents, during the stop phase of the drum 4, the glazing roller Sa from depositing glaze on the drum 4, or in any case avoids the creation of a piled-up line of glaze on the contact generatrix, which eventuality would 9 lead to the glazed tiles' being of unacceptable quality, or at least would cause glaze overloading on the drum 4 and necessitate frequent and complicated (and sometimes inefficient) cleaning operations.

Noteworthy is the fact that the presence of the channels 4b prevents dragging between drum 4 and glazing roller 5a, which obviates, as mentioned above, any line-forming on the former, and which contact would in any case be unacceptable in a decorating device of this type.

Claims (1)

1. Claims.

   A decorating device for ceramic tiles, comprising a conveyor for tiles, provided with collecting and drawing elements for positioning each of said tiles correctly on said conveyor; a drum, arranged with an axis which is perpendicular to an advancement direction of the conveyor. which drum is provided with discontinuous rotary motion synchronized with a motion of the conveyor, on a lateral surface of which drum are arranged images for printing on the tiles; means, of known type, for synchronisedly coordinating an advancement of the tiles and a rotation of the drum in such a way as to bring one of said images arranged on said drum exactly on to a surface of one of said tiles; characterized in that said images are etched on at least one pad arranged on the lateral surface of the drum; said decorating device comprises at least one r, 7 11 channel, arranged along generatrices of said drum between one end of said at least one pad and another end of said at least one pad, or between one at least one pad and another at least one pad; said decorating device comprises a glaze roller device, of known type, provided with a glazing roller having an axis which is parallel to an axis of the drum, which glazing roller by means of a contact between a generatrix of said glazing roller and a generatrix of the drum, transfers glaze to said at least one pad arranged on said drum; said glazing roller is arranged at such an angular position in relation to the drum that when said drum stops rotating said glazing roller is always situated at a position corresponding to a position of a channel.

   A decorating device as in claim- 1, characterized in that it comprises a motor, independent of said means for synchronisedly coordinating an advancement of the tiles and a rotation of the drum, which motor sets the glazing roller in continuous rotation, with a peripheral speed equal to a peripheral speed of the drum when rotating.

   12 A decorating device as in claim 1, wherein the drum bears more than one said at least one pad, and wherein each of more than one at least one pad is etched with a distinct design.

   A decorating device for ceramic tiles, substantially as described herein with reference to the preceding claims and the accompanying figures of the drawings.

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