WO2000053432A1

WO2000053432A1 - Method for engraving glass

Info

Publication number: WO2000053432A1
Application number: PCT/IT2000/000061
Authority: WO
Inventors: Eugenio Magnani
Original assignee: Bormioli Rocco & Figlio S.P.A.
Priority date: 1999-03-10
Filing date: 2000-02-25
Publication date: 2000-09-14
Also published as: AU3190800A; ITPR990019A1; IT1308520B1

Abstract

The present invention relates to a method for engraving glass. This method involves a step involving application of a mask onto the glass surface to be engraved, a step involving formation of the design on the mask and removal of the parts to be engraved, a step involving sandblasting of the glass surface with engraving of the zones left uncovered by the said mask and a step involving removal of the mask. The step involving formation of the design on the mask is performed in an original manner directly on the mask applied to the glass surface, using means for removal of the zones to be engraved, such as a laser.

Description

METHOD FOR ENGRAVING GLASS

TECHNICAL FIELD AND BACKGROUND ART.

The present invention relates to a method for engraving glass. The present invention is classifiable within the sector relating to the decoration, in particular artistic decoration, of glass articles where more or less deep layers are removed in order to obtain ornamental or written patterns.

Numerous glass engraving methods are known, said methods generally belonging to two categories: glass engraving methods which use a mask or other substances to protect the glass surface not to be treated, and engraving methods which use tools or a laser and which do not require masks in order to define the design and protect the zones which are not to be engraved.

Of the sand-engraving methods, the most widely known method is the one which involves the use of metal or rubber masks containing the shape of the design or the writing to be formed.

According to this method, the mask is applied to the glass surface so that a jet of sand strikes the said glass, passing through the recesses in the mask.

The abovementioned method has mainly the aim of engraving writing, such as capacity measurements, on glass articles such as glasses, goblets or bottles and has numerous drawbacks. Firstly the mask, in particular a metal mask, does not adhere perfectly to the surface to be treated, with the result that the contours of the figure to be reproduced are not clear and therefore it is not possible to perform deep incisions in order to prevent an even greater degree of imprecision. Secondly, the mask may be used several times and, during use, the contours which define the image to be reproduced are worn by the jet of sand. Consequently, the result cannot be repeated with precision and the image tends to become larger in relation to the number of times the same mask is used. In addition to the abovementioned drawbacks relating in particular to the quality of the images obtained, it is necessary to add that the abovementioned images must be very simple and, in particular in the case of writing, the characters must be discontinuous to ensure the unity of the metal or rubber surface of the mask and increase its duration and resistance to wear.

In order to overcome the drawbacks associated mainly with the use of masks, a sand- engraving method involving the use of photosensitive emulsions was developed. According to the abovementioned method, a photosensitive emulsion is applied onto the glass surface to be treated; the emulsion is subjected to a photographic process so that, by washing the surface, emulsion is removed from the areas to be engraved. The jet of sand then strikes the glass and engraves it in those areas where the emulsion has been removed. Finally, it is necessary to perform removal of the residual emulsion. This method has the advantage that the emulsion adheres well to the glass and therefore the characters or the designs do not need to be discontinuous, as in the case of the masks. Said method, however, is very laborious and costly and may be used only where there are flat surfaces or few curves.

Engraving methods which use disposable masks composed of several layers are also known. Initially the mask is composed of a paper or cardboard backing layer and a flexible plastic self-adhesive sheet. Incisions are made in the flexible plastic sheet using a cutting plotter, following the design to be reproduced, and then the sections of the design which are to be sand-engraved are removed. In order to be able to apply the mask to the glass surface, ensuring the unity thereof, an additional sheet of self-adhesive transparent paper must be applied onto the flexible plastic sheet. At this point the paper backing is removed and the mask is applied manually onto the glass surface before carrying out sand-engraving. After engraving has been performed, the self-adhesive mask must be removed.

With this method it is possible to obtain images having very clear contours and deep incisions, although it is a method which is very laborious and difficult, if not impossible, to implement in the case of fairly complex designs.

Moreover, the sand-engraving methods are unable to produce a finished part, and further cleaning operations are necessary.

In addition to the abovementioned drawbacks, it must be added that, with none of the abovementioned sand-engraving methods is it possible - where required - to finish figures already formed in the glass by means of a mould, with different depths along the various points of the figure and with highly defined contours.

Of the engraving methods which use tools, methods using diamond-tipped or widia- coated tools which are manually operated or mounted on pantographs or numerical- control milling machines are known. The characters or designs do not have to be discontinuous, but it is impossible to achieve uniform engraving over large areas or perform deep incisions. Moreover, a final operation involving cleaning of the part is always required.

It is also possible to perform the engraving of glass surfaces using a laser; the characters or designs do not have to be discontinuous and the production speed is very high, but, owing to the variation in temperature to which the glass is exposed, a deep incision cannot be made.

Moreover, the engraved surface is not smooth and has dangerous burrs which pose a risk for the user and cannot be totally eliminated even after further processing with abrasive rubber or sponges. DISCLOSURE OF INVENTION.

The object of the present invention is to eliminate the abovementioned drawbacks and provide a method for engraving glass which is simple and rapid, can be performed using both a manual or semi-automatic cycle and a totally automated cycle and is able to produce a substantially finished product without burrs or the need for further processing. A further object of the present invention is to be able to engrave even very complex designs which can be repeated in an identical manner on each part without variations in shape or size and with clear contour lines or deep incisions. Moreover, as a result of the abovementioned invention, it is possible to obtain incisions which are continuous, i.e. do not require discontinuous characters or designs, and are uniform in particular over large areas.

In addition to the already mentioned advantages, it must be added that, with the method in question, it is possible to sand-finish even very complex figures already formed in the glass by means of the mould and with different depths along the various points of the said figure, resulting in very high definition contours.

Said objects are fully achieved by the method for engraving glass according to the present invention, which is characterized by the contents of claims indicated below. In particular, said engraving method is characterized in that it comprises a step involving formation of the design provided, directly on a mask applied onto the glass surface, using means for removal of the zones to be engraved, such as a laser beam which reproduces the design on the mask, burning the latter. BEST MODE FOR CARRYING OUT THE INVENTION.

These and other characteristic features will emerge more clearly from the following description of the method. The method for engraving glass according to the present invention comprises the following steps: firstly, a self-adhesive protective layer is applied onto the glass surface to be engraved; the design is then directly reproduced on this protective layer, removing the said film using means for removal of the zones which are to be engraved subsequently. In particular, the step involving removal of the zones to be engraved is performed by means of a laser beam which reproduces the design on the mask, burning the latter.

Sand-engraving of the ornamental pattern and removal of the residual adhesive are then performed. The recommended adhesive is of the removable or even water-soluble type, so that, during the cleaning step, by immersing the part in water, elimination of the residual adhesive may be simultaneously performed. The abovementioned method may be performed as a semi-automatic cycle and, in this case, the following steps are performed.

Firstly, a self-adhesive flexible plastic sheet is manually applied onto the glass surface to be engraved. This step does not require a particular degree of precision since the design to be engraved has not yet been reproduced on the plastic surface. The glass product is then positioned in the laser machine and incision of the pattern on the flexible plastic sheet is performed by means of a laser beam. The glass product is then removed from the laser machine and is positioned in the sandblasting machine for sandblasting of the surface to be engraved. When engraving has been completed, the flexible plastic sheet is removed, if necessary immersing the part in water, if the adhesive is water-soluble, thereby also resulting in cleaning of the product and, therefore, in a substantially finished product. The engraving method may be performed, carrying out an automatic processing cycle. In this case, the plastic sheet acting as a mask is wound on reels and is applied onto the glass using labelling machines of the known type. Then the cycle performs the steps described above, where transfer of the product to the iaser machine, to the sandblaster and to the washing/drying machine is performed automatically.

The method according to the present invention may be used, in an original manner, for opacifying, i.e. sandblasting, figures which are already reproduced in the glass by means of the mould and which may have different depths along the various points of the said figure.

Generally, in this case the presence of a reference notch, positioned on the side opposite to the sanding side, is useful so as to be able to perform the cycle in semi-automatic or automatic mode. Firstly the flexible plastic having the function of a mask is applied on the side of the glass pre-formed by the mould, then the glass is aligned underneath the laser, using the reference notch located on the opposite side or in another useful position, and then the plastic with the outline of the design already rough-formed in the glass by means of the mould is cut. The plastic falling into the zones to be sandblasted is then removed by means of a vacuum suction cup and finally sandblasting and the successive operations in the programmed cycle are performed.

Claims

1. Method for engraving glass of the type comprising a step involving formation of the design by means of incision on a mask, a step involving application of the mask onto the glass surface to the engraved, a step involving sandblasting of the glass surface with engraving of the zones left uncovered by the said mask and a step involving removal of the mask, characterized in that the step involving formation of the design is performed directly on the mask applied onto the glass surface using means for removal of the zones to be engraved.

2. Method according to Claim 1 , in which the step involving formation of the design on the mask is performed using the removal means which comprise a laser beam suitable for reproducing the design on the mask, by burning the latter.

3. Method according to Claim 1 , in which the mask comprises a water-soluble adhesive and the step involving removal of the mask is performed at the same time as the cleaning step by immersing the part in water.

4. Engraving method according to Claim 2, in which the semi-automatic processing cycle comprises the steps of:

- manual application of a self-adhesive flexible plastic sheet onto the glass surface;

- incision of the design on the flexible plastic sheet by means of a laser beam;

- removal of the cut plastic;

- sandblasting of the surface to be engraved;

- removal of the flexible plastic sheet.

5. Engraving method according to Claim 1, in which the automatic processing cycle comprises the steps of:

- application of the self-adhesive flexible plastic sheet by means of labelling machines;

- positioning and centring of the part in a laser machine; - incision of the design on the flexible plastic sheet by means of a laser beam;

- removal of the cut plastic by means of a vacuum suction cup;

- sandblasting of the surface to be engraved;

- removal of the flexible plastic sheet.

6. Engraving method according to Claim 1 , comprising a step involving aligning of the glass, by means of a notch present in the said glass, so as to position correctly the glass surface in the case where it comprises an image obtained by means of the mould.