INTRODUCTION Field of the Invention

The invention relates to decorative glass products, especially "brilliant cut glass" products, and to their manufacture. Prior Art Discussion

Brilliant cutting of glass has been used since the 1800's to decorate glass; the process involves a highly skilled individual cutting a design into glass using a diamond-coated wheel. The result of this practice is to produce visually appealing glass. However given the time and skill involved this type of glass is very expensive.

US4068441 (Shaffer) describes manufacture of a cut glass panel, in which pieces of glass are bonded together. Adhesives are used, which are mixtures of organic materials and inorganic fillers. US5631057 (Sundet) describes adhering an applique to a glass panel, with a layer of transparent polymeric material. DE3022920 (Goralnik) describes making a cut glass panel with multiple glass pieces, and mouldable material is used to fill grooves.

The invention is directed towards providing a product which has the appearance of a traditional brilliant cut glass product, but is manufactured with fewer requirements for skill and time.

SUMMARY OF THE INVENTION

According to the invention, there is provided a method of manufacturing a simulated brilliant cut glass product, the method comprising the steps of:

providing a transparent sheet of glass or plastics material;

providing a mould with a three-dimensional pattern recess,

bringing the mould and the transparent sheet together with a curable liquid between said mould and sheet; curing the liquid to become a three-dimensional transparent solid bonded to the transparent sheet; and

removing the mould. In one embodiment, the liquid cures to become a clear transparent solid. In one embodiment, the liquid is cured by irradiating it with radiation having a curing wavelength. In one embodiment, the radiation is UV and wavelength is preferably in the range of 356nm to 400nm. In one embodiment, the liquid is a resin. In one embodiment, the radiation is selectively applied through a mask with an opening in the two-dimensional shape of the image, said mask being manufactured from a two-dimensional version of the design.

In one embodiment, the two-dimensional version is an initial two-dimensional design from which the three-dimensional design is developed by a computer. Preferably, the mask is supported on the side of the transparent sheet that is opposed to that of the mould.

In one embodiment, the mask lies between the transparent sheet and a transparent supporting table. In one embodiment, the mould is applied onto the liquid in a rolling action to avoid bubbles arising. In one embodiment, the mould is applied with features engaging registration features of a support frame surrounding the liquid resin. In one embodiment, the mould is pressed towards the transparent sheet by a pressure plate during resin curing.

In one embodiment, the mould includes a raised bead around at least part of an outer periphery of the pattern recess, and the pressure which is applied to the mould is such as to ensure that there is no liquid adjacent to the pattern recess outer periphery.

In one embodiment, the bead has a height in the range of 0.05mm to 1.0mm and preferably 0.1 to 0.25 mm. In one embodiment, the bead has a width in the range of 1.0 mm to 3.0mm, preferably, 1.5mm to 2.0mm.

In one embodiment, in the mould includes a transparent material over the pattern recess and an opaque material surrounding the pattern recess, and curing radiation is directed through the transparent material in addition to or instead of through the underlying transparent sheet. Preferably, the opaque material is in a layer forming a lower surface of the mould around the pattern recess.

In one embodiment, the method comprises the further steps of manufacturing a master relief, pouring a liquid into the master relief, and curing the liquid to provide the mould. In one embodiment, the master relief is manufactured by generating a virtual design using an image processor and routing a substrate according to the virtual design.

In one embodiment, the design is generated by initially generating a two-dimensional design and transforming it into a three-dimensional design having a desired maximum thickness.

In one embodiment, the method comprises the further step of applying a reflective coating on at least part of the cured liquid and/or the glass or plastics sheet, to provide a decorative mirror.

In one embodiment, the method comprises the further step of applying one or more additional transparent sheets to provide a multiple glazed product.

In another aspect, the invention provides a simulated brilliant cut glass product comprising a transparent sheet and cured liquid bonded to the sheet in a three-dimensional decorative design.

In one embodiment, the cured liquid is cured resin.

In one embodiment, the cured liquid has a transparency equivalent to that of the transparent sheet.

Additional Statements

According to the invention, there is provided a method of manufacturing a simulated brilliant cut glass product, the method comprising the steps of:

providing a transparent sheet of glass or plastics material;

depositing liquid resin onto the transparent sheet,

placing a mould with a recess in the shape of a three-dimensional design onto the liquid resin;

curing the resin; and

removing the mould. In one embodiment, the resin is cured by irradiating it with radiation having a curing wavelength.

In one embodiment, the radiation is UV. In one embodiment, the wavelength is in the range of 356nm to 400nm.

In one embodiment, the radiation is selectively applied through a mask with an opening in the two-dimensional shape of the image. In one embodiment, the mask is manufactured from a two- dimensional version of the design.

In one embodiment, the two-dimensional version is an initial two-dimensional design from which the three-dimensional design is developed by a computer.

In one embodiment, the mask is supported on the side of the transparent sheet that opposed to that of the mould. Preferably, the mask lies between the transparent sheet and a transparent supporting table.

In one embodiment, the mould is applied onto the liquid resin in a rolling action to avoid bubbles arising. Preferably, the mould is applied with features engaging registration features of a support plate surrounding the liquid resin.

In one embodiment, the mould is pressed towards the transparent sheet by a pressure plate during resin curing. In one embodiment, the method comprises the further steps of manufacturing a master relief, pouring a liquid into the master relief, and curing the liquid to provide the mould.

In one embodiment, the master relief is manufactured by generating a virtual design using an image processor and routing a substrate according to the virtual design.

In one embodiment, the design is generated by initially generating a two-dimensional design and transforming it into a three-dimensional design housing a desired maximum thickness. In one embodiment, the method comprises the further step of applying a reflective coating on at least part of the cured resin and/or the glass or plastics sheet, to provide a decorative mirror.

In one embodiment, the method comprises the further step of applying one or more additional transparent sheets to provide a multiple glazed product.

In another aspect, the invention provides a simulated brilliant cut glass product comprising a transparent sheet and cured resin applied to the sheet in a decorative design. DETAILED DESCRIPTION OF THE INVENTION

Brief Description of the Drawings

The invention will be more clearly understood from the following description of some embodiments thereof, given by way of example only with reference to the accompanying drawings in which :-

Fig. 1 is a two-dimensional (2D) representation of a sample design for a brilliant cut glass product, and Fig. 2 is a diagram showing in 2D a contact bead area and an excess resin reservoir;

Fig. 3 is a perspective view of a master relief, routed from a blank according to the three- dimensional (3D) design;

Fig. 4 shows pouring of a compound onto the master relief to make a mould, and the mould is shown in perspective view in Fig. 5;

Fig. 6 is a front view of a mask for use in a downstream manufacturing step;

Fig. 7 shows irradiation of spaces exposed by the mask to UV radiation to cure exposed resin within pattern recesses of the mould, to provide a cured resin 3D profile bonded onto glass;

Fig. 8 is a perspective view of the final product; Figs. 9 to 14 are a series of cross-sectional views of steps of an alternative process; and

Fig. 15 is a perspective view showing pouring of a first (opaque) rubber compound for mould manufacture, and Fig. 16 shows pouring of a second (transparent) rubber compound to complete the mould manufacture.

Description of the Embodiments The invention provides a product having the appearance of a traditional brilliant cut glass product, and a method for its manufacture. The following are the steps with reference to the drawings listed above.

A two dimensional (2D) image 1 is chosen for production of cut glass, Fig. 1. This may have any desired design, there being complete design flexibility.

Referring to Fig. 2, a computer aided design (CAD) system incorporates registration features 10 and excess resin reservoirs 11 and a contact bead area 12 that is 1.5mm to 2.0mm wide surrounding the 2D image. The width of the contact bead area in this drawing is exaggerated, for clarity.

The design is completely virtual at this stage, a computer representation. The depths of the excess resin reservoirs are chosen to suit the size of the pattern to be manufactured as this dictates the likely extent of excess resin as is described in more detail below.

The image is scanned or imported into a CAD software program which creates three-dimensional (3D) reliefs from the flat 2D image 1. A designer uses this program to choose at least part of the image to be raised. The maximum height of the relief is 2mm in one example. The 3D pattern preferably has ridges which simulate ridges which appear in many cut-glass designs.

The software then digitally creates a 3D file. The raised feature has around its outer edge a bead recess which is much shallower than the feature height. An example is in the range of 0.05 mm to 1.0 mm, or preferably 0.1mm to 0.25mm deep. The bead width is in the range of 1.0mm to 3mm, and preferably 1.5mm to 2.0mm. The information and file from the CAD software is fed into a CNC (computer numerical controlled) routing machine. This machine uses the 3D relief design information to route an aluminium, brass or acrylic blank. In addition to routing for the design, registration holes 35 are also routed, as are ridges 34 for moulding of excess resin reservoirs. This routing provides a master relief 30. The master relief 30 has a main body 31, a 3D raised pattern 32, a contact bead trench 33, and reservoir ridges 34, and registration recesses or trenches 35. This is shown in Fig. 3. The master relief 30 is then polished to a mirror finish. This ensures that the subsequent mould generated has a very smooth surface, ensuring high glass quality.

Referring to Figs. 4 and 5, liquid silicone rubber 50 is now poured onto the master relief 30 to make a silicone rubber mould 51. The liquid silicone rubber 50 is of a platinum condensation type, having a Hard A Shoreness of 55. It is a hard rubber that reproduces the master relief surface shape in fine detail, as a negative. The mould 51 has a recess 52 corresponding to the designed raised profile (3D) 32, excess resin slots or trenches 53, and raised registration ridges 54. The mould 51 also has a raised bead 55 around the peripheral edge of the design pattern recess 52. As noted above, the bead has height which is very small, in the range of 0.1 to 0.25 mm, as compared to the design pattern depth of up to 2 mm. Its purpose is to ensure that there is full contact between the mould and a glass plate around the edge of the relief.

Using the original 2D image a mask 60 is created (Fig. 6). The mask 60 is used in the casting process to ensure that only the required 3D image is cast onto glass. To create the mask the 2D image is imported into a software program that drives a cutting device. The shape of the design is cut into a self-adhesive black vinyl material. The design is removed and the remaining material is applied to a clear polycarbonate foil. This provides a mask that only allows UV light to penetrate the 2D design area. Now that the mould 51 and the mask 60 have been made, the simulated brilliant cut glass pane can be manufactured.

Referring to Fig. 7, the mask 60 is placed on a glass table top 70. A sheet of glass 80 is placed on top of the mask. A metal frame 90 with a rectangular centre aperture is placed on top of the glass sheet 80. The underside of the metal frame has a rubber sheet attached to prevent leakage of UV Resin. The top side of the metal frame has registration slots 91 identical to those in the master relief 30, and so the registration ridges 54 of the mould fit 51 into them.

A water clear UV resin 100 is now poured onto the glass sheet 80, ensuring that the image area within the frame 90 is covered. Care is taken to ensure that no air bubbles are created while pouring the resin.

The physical characteristics of the UV resin 100 are important in ensuring that imperfections are avoided.

- The material is water clear with a refractive index of 1.49

- The curing radiation is at a UV Spectral output of 365nm

- The material has a low viscosity of 20 CPS to ensure that bubbles are easily avoided and to ensure that the material can be easily displaced under pressure from the contact bead area.

- The material contains UV inhibitors to ensure that it does not yellow over time.

The rubber mould 51 is now applied onto the UV resin-covered glass. This is done with a rolling technique to ensure that no air bubbles are contained within the rubber mould. The registration ridges 54 of the rubber mould are placed into the corresponding recesses 91 in the metal frame 90. This ensures that the image contained within the mould matches that of the mask 60. All excess material will flow into the excess resin reservoirs 53 of the mould 51.

A metal pressure plate 110 is now placed on top of the rubber mould 51 and pressure is applied downward. This pressure ensures that the bead 55 around the pattern recess 52 of the mould 51 makes contact with the glass 80 and ensures that no UV resin 100 exists in the bead area surrounding the pattern recess 52. More detail is provided in the enlarged detail part of Fig. 7.

There is now a body of liquid resin 100 between the mould 51 and the glass plate 80. The resin 100 is especially within the pattern recess 52 of the mould 51. This is the area which is visible from underneath, due to the mask 60. A light source 140 emitting a UV wavelength of between 356nm - 400nm is now introduced from under the glass table 70. The UV light passes through the mask 60 and only reaches the 3D image 52 area. The UV light cures the resin 100 within the pattern recess 52, and this resin takes the shape of the 3D pattern 52 in the mould. In addition, this cured resin also bonds to the glass sheet 80. Any excess resin resides in the wells 53 of the mould 51 and remains in liquid form as the mask 60 prevents the UV light from curing this resin.

The metal pressure plate 110 and the mould 51 are now removed. The unexposed and liquid UV resin 130 is removed and recycled for use again. The metal frame 90 with centre aperture is removed and the glass 80 is now washed to remove any residue from the unexposed UV resin. The glass sheet 80 now includes the clear 3D profile bonded to the glass sheet. As the clear 3D profile refracts light, the resulting visual appearance is similar to brilliant cut glass.

The final product, 150, is shown in Fig. 8. It has cured resin 151 in a raised 3D design profile bonded onto the glass sheet 80.

It will be appreciated that the process provides for highly automated production of decorative "brilliant cut glass" products. However, as the design is created with full versatility there is no limitation on artistic design imposed on the production process.

A major benefit is that the image can be easily chosen, and there is also versatility in development of the model choosing which areas to raise.

The resin has the same appearance, transparency, and durability as the substrate glass, and the bonding is such that the product appears like cut glass.

Referring to Figs. 9 to 14 the following are the manufacturing steps in another embodiment:

Fig. 9: A glass table 200 supports a mask 201, in turn supporting a glass sheet 202. The mask 201 has an opening 203.

Fig. 10: A metal frame 210 is placed on top. This has an opening or window 211, and registration recesses 212 in its upper surface.

Fig. 11: Resin 220 is poured onto the glass 202 within the frame 210 window 211.

Fig. 12: A mould 230 is carefully applied over the resin 220, in registry with the frame

210. The mould 230 has a lower opaque layer 232 outside of a 3D pattern recess 234. There is also a bead around the periphery of the recess 234. There are evacuation (excess resin) slots 233 in the lower surface of the mould 230.

Fig. 13: A glass pressure plate 250 is applied over the mould, and even pressure is applied downward.

Fig. 14: UV light is irradiated from two sources 260 below and above the assembly. The mask 201 and the opaque rubber layer 232 ensure that only the resin 220 within the 3D pattern recess 234 is cured.

In this embodiment, the curing operation is faster and it is easier to achieve uniformly comprehensive curing due to the fact that the resin is cured from both sides.

Fig. 15 shows how the mould is made. An initial opaque rubber composition 302 is poured onto a master relief 300, so that it surrounds a raised master pattern 301. As shown in Fig. 16 a transparent rubber 305 is then poured to cover the opaque resin (now cured) and the raised profile 301.

In this embodiment, comprehensiveness and repeatability of resin curing is easier to achieve because of curing from both sides. The invention is not limited to the embodiments described but may be varied in construction and detail. For example, the "brilliant cut glass" product may be a decorative mirror by application of a reflective coating to the side of the glass that contains the cured resin surface, or indeed the other side. Alternatively the final product may be a double or triple glazed unit with the cured resin being between the pane that it is adhered to and another pane. While it is preferred that the resin cure to a transparent solid, it may alternatively be translucent, and may be of a colour different from the underlying glass sheet. In the latter case, it may give the appearance of an insert. Also, it is envisaged that the method may involve curing by heat rather than or instead of irradiation. In this case, it must be ensured that curable liquid does not exist outside of the pattern recess. Of course, curing by exposure to radiation through a mask is a particularly effective way of ensuring that only liquid within the pattern recess is cured.