EP0847546A1

EP0847546A1 - Method of moulding and applying marks on a surface

Info

Publication number: EP0847546A1
Application number: EP96926989A
Authority: EP
Inventors: Georges-André Leschot
Original assignee: Promatec Systems SA
Current assignee: Promatec Systems SA
Priority date: 1995-08-28
Filing date: 1996-08-23
Publication date: 1998-06-17
Anticipated expiration: 2016-08-23
Also published as: DE69618966T2; JPH11511258A; EP0847546B1; DE69618966D1; WO1997008592A1; CH689345B5; US6113726A; CH689345GA3

Abstract

The disclosure pertains to a method by which an elastomer is applied to a model (1) with relief marks to be reproduced; the purpose of the elastomer once set is to form a mould membrane (14) and incorporate within its own material the shape of the marks on the model. The mould membrane is then separated from the model and filled with a setting material, and the mould membrane is applied to a support in order to transfer the marks after preliminary pasting.

Description

Method for molding and applying signs on a surface

The present invention is in the field of fixing elements to supports and relates more particularly to a method of molding and applying three-dimensional signs on a surface such as a clock face which acts as a support.

Methods for fixing elements on supports have been known for a long time, such as the decal methods using an engraved plate and a buffer which give very good results when the signs to be reproduced are flat and thin, but becomes more difficult to use when one wants to obtain more substantial thicknesses. Other techniques such as insertion or gluing have so far made it possible to fix three-dimensional signs by placing them individually. There are other methods in which signs to be affixed to, for example, a dial are produced by cutting out a sheet formed from a mass possibly containing luminescent material, the signs obtained being of flat shape. This method does not however allow the production of signs of elaborate shape on the one hand and on the other hand supposes a manipulation performed by an operator to place them on the support.

The present invention aims to overcome all these drawbacks and more particularly to allow the creation of signs of any shape and / or thickness, while eliminating the manipulation of the signs by an operator during the process of laying on the support. The method for transferring signs on a surface according to the invention is characterized in that an elastomer intended, after having hardened to form a membrane, is applied to a model having at least one raised sign to be reproduced mold and to reproduce in negative the raised sign of the model, in that the membrane-mold is separated from the model, in that the membrane-mold is filled with a mass capable of hardening, in that apply the membrane-mold containing the sign filled with hardened mass or in the process of hardening on a support so as to transfer the sign after having previously glued the site or the visible surface of the sign.

The invention also extends to a tool for implementing this method, characterized in that it comprises a support piece having at least one orifice, the piece having at least one notch or a perfora¬ tion indexing, molding parts enclosing the support piece and model for making the membrane-mold by molding.

The invention also relates to the support obtained by the implementation of the method. The appended drawing represents, by way of nonlimiting examples, an embodiment as well as variations of the method according to the invention.

Fig. 1 shows a top view of an original model of a dial comprising raised signs which one wishes to reproduce and affix on a surface, the original model being in the form of a disc with an indexing notch.

Fig. 2 is a cross section along line II-II of the model of FIG. 1. Fig. 3 shows a ring of the same external dimension as the model in FIG. 1, also with an indexing notch.

Fig. 4 is a cross section along line IV-IV of the ring of FIG. 3, on an enlarged scale, in which there is a rectangular channel on the outside and a dovetail machining on the inside.

Fig. 5 shows a device for producing a membrane-mold intended to reproduce the raised signs.

Fig. 6 gives the detail of the connection between the membrane-mold and the ring.

Fig. 7 shows a way of filling the mold manually using a filling nozzle.

Fig. 8 gives another alternative of filling by deposition and scraping of the upper surface of the mold with a blade.

Fig. 9 shows the said membrane-mold filled with the molded masses. Fig. 10 shows a device used for decalculation and gluing of the surface intended to receive the molded masses, using an in¬ poured plate, a buffer and a sliding support. Fig. 11 shows the relative positioning of the previously glued surface and the membrane-mold containing the masses molded before the operation of plating the masses using a positioning tool.

Fig. 12 shows the contacting of the masses with the surface using an application tool.

Fig. 13 illustrates the deformation of the mem¬ brane-mold allowing the transfer of a molded mass with the application of a vacuum using a tool,

Fig. 14 shows the transfer of a molded mass having a shape with concave parts.

Fig. 15 represents a succession of molded members injected into holes made on a flexible support in the form of a strip,

Fig. 16 is a section through a membrane-mold of the support along the line XVI-XVI of FIG. 15, and fig. 17 is a section through an injection device enclosing the strip of the support of FIG. 15 and allowing the succession of membrane-molds to be produced continuously. The model in fig. 1 is a model of the dial of a timepiece having three-dimensional signs showing a certain relief. The standard dial in fig. 1 represents a definitive model which will be used to produce the tooling devices and the molds used for the mass production of the timepieces to be reproduced. It includes a disc where the signs to be molded are produced either by machining or by gluing or welding on the surface. The model serves as a matrix for a first molding operation and positioning of the signs on surfaces appearing on the outline of the dials to be manufactured. Although the model represented is a timepiece, it is obvious that the method which will be described below is not limited to this application and that it can be applied to the production of dials or any surfaces supporting three-dimensional signs used in mechanics, electronics, etc.

The original model shown in fig. 1 is in the form of a disc 1, the surface of which has different signs 2, 3, 4, 5 which may have various three-dimensional shapes. This model will be used for the realization of one or more molds which will allow to manufacture and contain the signs conforming to the original. The signs contained in the molds can then be fixed on a support in a single operation. The edge of the disc 1 also includes an indexing notch 6.

With the model of fig. 1 and 2, the first operation to be carried out will be the manufacture of at least one membrane-mold. To support this membrane-mold, a ring 7, shown in FIGS, will advantageously be used. 3 and 4 and provided with an indexing notch 8 corresponding to the notch 6 of the disc 1. The ring will be machined with an internal profile in dovetail 9 so as to pou¬ see retain the membrane.

The disc 1 and the ring 7 will be placed free without play, as shown in FIG. 5, inside a molding device or matrix 11, the disc 1 and the ba¬ gue 7 being placed in superposition by making coincide the indexing notch 6 of the disc to the indexing notch 8 of the ring.

On this assembly, there is a cover 12 having a general form of funnel opening onto a central orifice 13 intended for the passage of a mass of silicone 14 poured over the assembly. The base of the cover being substantially flat, the excess silicone 15 will be recovered in the funnel of the cover 12. The product used in this case is a two-component silicone elastomer which has the most important characteristics of its elasticity and its mechanical and chemical resistance, its low shrinkage and the excellent temperature resistance. Other products of similar quality can be used.

In this way, an elastic membrane-mold 14 is obtained which is supported by a metal ring 7, as shown in FIG. 6. The membrane-mold 14 has hollow zones 16 formed during molding by the three-dimensional signs 2 to 5. This operation can be repeated several times in order to pour the desired number of membrane-molds 14 intended for production.

The next step in the process corresponds to the filling of the membrane-mold shown in FIG. 6. Several possibilities exist. In a preferred alternative illustrated in FIG. 7, one can opt for a filling system with a nozzle metering device 17 distributing a filling mass 18, this system being either manual, or controlled by a digital control machine not shown. In another variant, filling can be carried out by pouring a suitable quantity of filling mass 19 (FIG. 8) and then ara¬ santing the surface with a scraper blade 20 intended for born to remove excess material. Another alternative would be to perform the operation by a vibrating action, not shown.

In fig. 9 shows a membrane-mold 14 held in the ring, the hollow zones 16 being filled with the filling masses 18 or 19.

The filling mass 18 or 19 is in a preferential case composed of a transparent lacquer to which a luminescent or pigmented powder has previously been mixed which polymerizes in a few seconds with ultraviolet rays. Acrylic or other resins drying in air or in an oven can also be used. The luminescent powders can be based on sulphate and sulphite of zinc treated with tritium and which allow a night vision of the signs on the dial. Other alternative fillers are to be considered to play with the colors or to obtain other desired effects.

The molded masses 18 or 19, depending on their nature, are hardened by different processes: ultraviolet radiation, steaming, ambient air, etc. As mentioned above, one or more membrane-molds are necessary for production according to the ratio between the time of hardening of the molded masses and the time of application of these masses on the dial.

The next phase, illustrated in fig. 10, consists in the application of hardened molded masses on the surface 21 intended to receive them. For this it is necessary that said surface or the signs are previously pasted, either manually with a dispenser, or with a dispenser dispenser mounted on a numerically controlled machine or by a transfer system, a well-known process. in the manufacture of watch faces. In this latter case, a metal plate 22 will be used, with the signs to be stuck engraved 23 on its surface to a slightly smaller dimension. This engraving operation could be done by covering the plate 22 originally with a photosensitive film (photographic printing technique) and then treating the exposed parts with acid. Once fixed on its movable frame 24, the plate 22 is glued and, after scraping with a spatula, the impression is taken again with a pad 25 made of gelatin or silica cone. With said buffer, we will deposit the glue on the surface to be glued 21 (dial or sign). The movable frame 24, as well as the buffer 25, will be controlled by a device which is not shown, for example having translation slides and stops allowing the relative positioning of the surface 21 and of the plate 22 (fig. 10).

As illustrated in fig. 11, the membrane-mold 14 will be placed with exactness using an indexing device 26 on the surface 21 having dots of glue 27, reserving an adequate clearance 28 in height.

With an application tool 29, shown diagrammatically in FIGS. 12 and 13, the membrane-mold is pressed against the glued surface of the support 21 and the molded signs 18, 19 are released by the edges of the membrane by creating a vacuum in the suction chambers 30 provided in the tooling 29 , via conduits 30 a. The tool 29 can also advantageously be produced from the molding die of FIG. 1 according to the following operations: a) use of a membrane-mold 14 as produced and described with reference to FIG. 6, the membrane mold 14 being placed in the matrix of fig. 5 after being returned; b) filling the hollow zones 16 of the membrane-mold 14 with the aid of a non-elastic material capable of hardening, for example polyurethane, polyester resin or even an epoxy; c) the hardened masses are recovered on a rigid double-sided sticker, then transferred by gluing always using the matrix of FIG. 5 on a support disc which itself will be used as application tool 29 after being drilled so as to make the suction chambers 30 operational.

This way of doing things has the advantage of realizing all the tools with precision, starting from the model in FIG. 1 and using the matrix of fig. 5. Thus all the molding, positioning and transfer operations are carried out with the same matrix starting from the original model of FIG. 1.

Thanks to the suction chambers 30 the membrane-mold is released and the molded signs are applied at the desired location. Thereafter, the membrane-mold is released from the application tool and can be filled again.

In fig. 14 there is shown on an enlarged scale a molded sign 32, the height of which is particularly large and which also has a lateral clearance 31 authorized by the method described hitherto.

The process which has just been described offers the following advantages: - the signs are no longer touched during the production of a part, which is particularly advantageous in the case of the use of radioactive signs; - there is regular precision during molding, transfer, the positioning of the signs being carried out once and for all during an initial adjustment and all the operations being carried out using the membrane-mold and the matrix of fig. 5;

- The saving of time is considerable compared to the pro¬ cedures of the prior art, it being understood that one can work in series with several membrane-molds, all made with the same original model. The process described with reference to FIGS. 1 to 14, requires for continuous transfer of signs, the realization of 4 to 8 membrane-molds according to FIGS. 3 to 6. It is thus possible to provide the various stations allowing the filling of the membrane-molds, the drying, the gluing and the laying of the signs on a support.

In the variant of the method described with reference to FIGS. 15 to 17 the membrane-molds 40 are produced continuously on a flexible support in the form of a strip 41 having holes 42 on which said membrane-membranes 40 will be injected. The support 41 has between the holes 42 perforations 43 which will serve to position the strip 41 during the various operations for producing the membrane-molds 40, for filling the said membrane-molds and for placing the signs 44 (FIG. 16) on a support not shown. In order to make the band 41 integral with the membrane-molds 40 and to avoid any relative displacement between the two elements (band 41 and membrane-molds 40) anchoring perforations 45 placed around the holes 42, are provided on the band 41. Thus , during the production of the mold-membranes 40 by injection as shown in FIG. 17 the material injected between two jaws 46 and 47 of the molding enclosing the strip 41 will enter the perforations 45 and make each membrane-mold integral with the strip 41. The molding device of FIG. 17 is similar to that described with reference to FIG. 5 with its cover or upper part 12 (fig. 5) containing the original model or disc 48 corresponding to model 1 of fig. 1. The lower jaw 47 comprises a central orifice 13 intended for the passage of the mass of silicone which is injected and which, after hardening, is intended to form the membrane-molds 40. The positioning of the jaws 46, 47 of the device for molding the fig. 17 is produced using guide punch 49, entering the positioning perforations 43 of the strip 41.

The material used for the production of the mold membranes is as described above with reference to FIGS. 4 to 6 in two-component silicone injected cold into the jaws 46, 47 of the previously heated mold. At the bottom of one of the jaws 46, 47 will be placed a disc, not shown, similar to that of FIG. 1 showing the signs to permeate the membrane-mold. As a variant, the signs to be impregnated in the membrane-mold may be formed at the bottom of one of the jaws 46,47. The support used is a flexible support in the form of a polyester or polycarbonate strip. The strip 41 with its mold membranes obtained by overmolding is, after hardening of the mold membranes, used to proceed to the filling phase of the signs as shown in fig. 6 to 9, then at the gluing and transfer phase of the signs on a support. The variant which has just been described has the advantage that the different phases of overmolding of the membrane-molds, filling of the signs, gluing and transfer of the signed signs can be performed separately or continuously. The banners containing the signs can also be stored and the strips can be used in a lost mold process or be reused after the transfer of the signs which they contained.

The process which has just been described offers the following advantages:

1. Control of drying times during the production of membrane-molds and control of drying times during filling of signs.

2. Avoid manipulation by an operator, for example if the signs are radioactive. Possibility of storing the bands containing or not the signs. 3. No wear, the strips are simply thrown away after one or more uses. Guarantee of quality and precision. 4. The process can be completely automated and used continuously or in separate phases (drying, filling, etc.)

Finally, the process which has just been described gives the possibility, if desired, of placing inserts in the signs or of making multi-layer signs.

Claims

1. Method for transferring signs on a surface, characterized in that a model having at least one raised sign is applied to reproduce an elastomer intended after having hardened to form a membrane-mold and to reproduce the sign in negative relief of the model, in that the membrane-mold is separated from the model, in that the membrane-mold is filled with a mass capable of hardening, in that the membrane-mold containing the sign filled with hardened or hardening mass on a support so as to transfer the sign after having previously glued the site or the visible surface of the sign.

2. Method according to claim 1, characterized in that the membrane-mold is applied to a model comprising a set of signs to be reproduced and in that the set of signs is applied to the support with pre-gluing in a single operation.

3. Method according to claim 1, characterized in that the membrane-mold is produced so that the thickness of its layer can contain three-dimensional signs having a significant relief.

4. Method according to claim 1, characterized in that an application tool is produced for the transfer of signs having raised parts corresponding to the shape of the signs to be transferred and hollow parts surrounding the parts relief, the parts in relief having just pressed on the membrane-mold at the location of the signs and the hollow parts being re¬ linked to orifices allowing a vacuum to be created between the membrane-mold and the hollow parts, to press the membrane-mold against said hollow parts and thus identify the periphery of the signs.

5. Method according to claim 1, characterized in that a snapshot is produced having a negative reproduction of the locations of the signs to be transferred, in that these locations are glued, in that the adhesives are transferred to the using a gelatin or silicone pad on the model before transferring the signs.

6. Method according to claim, characterized in that the elastomer of the membrane-mold is a two-component silicone elastomer.

7. Method according to claim 1, characterized in that the membrane-mold serves as a basic member for all operations, in particular molding, positioning and transfer of signs.

8. Method according to one of claims 1 to 7, characterized in that several membrane-molds are produced intended to be used continuously in the phases of manufacturing the membrane, filling and transfer of signs.

9. Method according to claim 8, characterized in that the membrane-mold is overmolded on an orifice provided in a support piece, the piece having indexing notches or perforations.

10. Method according to claim 9, characterized in that the support piece is in the form of a plastic strip provided with a succession of orifices, a membrane-mold being overmolded on each orifice.

11. Tools for implementing the method according to claim 1, characterized in that it comprises a support piece (7,41) having at least one ori¬ fice, the piece having at least one notch or a per¬ indexing drilling (8,43), molding parts (11, 12; 46,47) enclosing the support part and the model to produce the membrane-mold by molding.

12. Tool according to claim 11, characterized in that the support piece is a ring (7) having an internal profile (9) in dovetail intended to rete¬ ny the membrane-mold, the ring comprising a notch 'indexing (8) to position it relative to the model or support.

13. Tool according to claim 11, characterized in that the support piece is a strip (41) presen¬ as a succession of orifices (42) on each of which is molded a membrane-mold (40), the strip having indexing perforations (43).

14. Tooling according to claim 9, characterized in that it comprises an installation consisting of a cli¬ ché (22) having hollow parts (23) reproducing the configuration of the signs of the model, a transfer station (24 ) intended to receive the support (21) on which the signs will be transferred and a gelatin or silicone pad (25) which can move from the plate (22) to the model, in order to transfer the glue contained in the hollow parts ( 23) of the photo.

15. Tool according to claim 9, characterized in that it comprises a suction tool (29) presen¬ as raised parts corresponding to the shape and location of the signs to be transferred and surrounded by suction chambers (30 ), the part coming to be placed above the membrane-mold (14) containing the signs to be transferred (18, 19).

16. Tool according to claim 15, characterized in that the suction tool (29) is produced from the membrane-mold.

17. Support obtained by implementing the method according to one of claims 1 to 10.

18. Support according to claim 17, characterized in that the transferred signs which it contains are realized from a hardening mass in air or in an oven or by polymerization.

19. Support according to claim 18, characterized in that a radio-luminescent material is incorporated in the hardening mass.

20. Support according to claim 17, characterized in that the support containing the transferred signs is a watch dial.