MXPA97007268A - Article of three-dimensional surface formed enva - Google Patents

Abstract

The present invention relates to a vacuum forming process for molding a thin sheet of a thermo-formable plastic selected in an exact reproduction of three-dimensional relief of an original work of art, said sheet of plastic having printed on one side thereof a permanent image of said original work of art, said method being characterized in that it comprises the steps of: (i) supporting said printed sheet of plastic next but not in contact with a female mold forming vacuum with said mold side, female having a relief of surface in the same as a pre-production of the relief of surfaces of said original work of art, said image coinciding with the surface relief of said mold, a multitude of vacuum forming holes provided in said mold, (ii) heating said sheet plastic at a first temperature at which said plastic sheet is flexible and about to bend, but without bending , which minimizes the movement of said image in relation to said female mold due to the heating of said sheet, (iii) contacting said female mold with said sheet while said sheet is heated up to a first temperature, immediately applying a vacuum to said holes in said mold to begin to stretch said plastic sheet inside said mold and thereby fix said sheet in relation to said relief of the mold to further minimize the movement of the image on said sheet in relation to said mold; ) continuing to heat said plastic sheet to a second temperature that is greater than said first temperature and to which said plastic sheet will be thermoformed while keeping said holes in said female mold empty. To complete the formation of said three-dimensional in said sheet, (v) stop heating said plastic sheet once the second temperature has been reached while continuing to empty said holes in said female mold, cooling said sheet after it is stop heating, to cool said sheet below said first temperature to a third temperature to make said three-dimensional relief formed in said sheet; and (vi) stop the cooling of said sheet and remove said sheet from said mold.

Description

ARTICLE OF TRIDIMENSIONAL SURFACE FORMED IN VACUUM FIELD OF THE INVENTION This invention relates to a vacuum forming method and related apparatus for molding a thin sheet of thermoformal plastic into a precise three dimensional relief reproduction of an original artistic work, where the plastic sheet carries a permanent image of the original work.

BACKGROUND OF THE INVENTION The renewed interest of society in works of art has resulted in the demand for inexpensive reproductions of the original. For many years, society > We have to contend with the bidunsional reproductions that were often reproduced by a photographic procedure. These two-dimensional reproductions could not reproduce what was often an essential feature of the work, relief. For some paintings, for example, part of the genius of the work depends not only on the image produced, but on the texture of the work, such as the brushstroke that, for example, can reflect light in a particular way. One of the first obstacles to achieving this goal is the way in which the third dimension of the work of art can be reproduced. However, several methods have been developed to recreate that third dimension, and some of these methods involve obtaining a matrix from the original work itself, pouring a substance onto the original work to copy its relief; (US Patent 4,285,744; 4, 971, ('43; French Patents 1,493,516 and 1,548,337) Unfortunately, this procedure is simply not acceptable when the originals are reproduced, as it can compromise the physical integrity of the work and, with masterpieces , simply can not be used.From the matrix, a female molding die and possibly a male molding die are obtained.These dies constitute the molds against which the image bearing the substrate will be pressed. press, a vacuum device or other device that exerts pressure on the substrate The problem faced when pressing the substrate is to find a medium capable of adequately reflecting the desired definition, it has been found that PVC is a means that can deform properly under controlled conditions Unfortunately, this material must be heated before pressing and this often causes displacement and deformation it is of the image contained in it. Traditional procedures have tried to solve the above problems in the following way. The application for Canadian Patents 2,020,206 and its counterparts of E.U.A. 5,182,063 and 5,201,548, propose an alternative method to form a matrix that reflects the three-dimensional characteristics of the work of art, without compromising the original work. A similar procedure is also described in the U.S. Patent. A. 4,001,062. Two photographs of the original work were taken, and they are placed side by side on a vehicle. The transparent substrate, on which the three-dimensional elements are reproduced, is placed on one of the images. The artist then begins to recreate the relief (for example, brush strokes) in relation to the image below the substrate. When it becomes difficult to see the image below the substrate because it is covered with paste, then the artist can simply refer to the other image next to it. Taking the artist to reproduce the three-dimensional elements of the original work on a matrix, and then forming the mold from that available matrix, the original work of art is never touched. On the other hand, one of the drawbacks of this procedure is that after the artist begins to trust the image on the side of the substrate, and not on the one below, the faithful reproduction of the relief becomes less precise. To ensure proper definition during the pressing procedure, many previous procedures (4,971,743; 5,116,562 and 4,285,744) require that the imaging vehicle, which is most often a PVC hobby, be heated to its softened state immediately before embossing. PVC; it is often heated to 110 ° 0 to 130 ° C. As it softens, the PVC sheet bends over the female embossing die, but does not come into contact with it. The press is then raised, so that the softened PVC fills-all the notches and indentations of the die, and the pressure is then applied for the necessary amount of time. Unfortunately, heating the PVC sheet to its softened state inevitably results in uneven softening, so that some sections of the PVC will soften more quickly than others and, consequently, will bend earlier than others, which gives As a result the image shift. Therefore, the molded relief does not correspond to the image. In the procedure of the U.S. Patent. No. 5,182,063, the canvas is impregnated with a resinous material to form a substrate. The material of the PVC sheet with the image is melted and then pressed onto the substrate to adhere the PVC sheet to the substrate. The pressing operation requires the use of dies that press the embossed relief in the PVC and the substrate filling. Although the image appears to be stable on the substrate, additional processing is required to ensure such stability. For this reason, some inventions such as the US Patent. 4,285,744, provide means for molding a PVC substrate, while maintaining the quality of the image, rapidly heating it to its softened state, moni toring the heat distribution, and, consequently, quickly mounting it. In other words, trying to reduce the amount of time during which the PVC softens and bends down on the die. However, in light of the inherent structure of PVC, it is impossible to predict the manner in which it will soften, even when the heat is regulated. A vacuum thermoforming process is described in Braund, Patent of F.U.A. 3,010,152, for the outer shell of a geographical sphere. The outer shell is obtained by vacuum thermoforming a plastic sheet in a hemispherical shape, where the surface of the lining has protuberances formed in the same pair to give the surface relief the feeling of mountains in the mountainous regions of the sphere indicated by the image on the plastic sheet. However, Braund has to heat the blade until it softens or plasters, so that the blade folds or buckles. The male Braund mold exerts pressure through the softened sheet to form in vacuo the surface protuberances and the general hemispherical shape of the male mold in the ho a. The present invention in accordance with one aspect seeks to overcome the disadvantages of the prior art in the following manner. When the original characteristics of the original work of art are recreated on a matrix, this invention ensures that the image on the substretch remains visible at all times, so that the artist does not have to make a calculated assumption about the location of a particular relief. This is accomplished by projecting the image onto the substrate, either through the use of a photographic lens pattern enlarger or its equivalent. Through projection of the image, the artist is always able to see the work regardless of the amount of paste that covers the substrate, which also increases the reliability of the three-dimensional reproduction. Furthermore, prior to the pressing procedure, this invention does not require that the PVC be heated to such a degree that the sheet is bent, folded down or bent over the die, where said inclination, buckling or the like increases the probability of deformation or displacement of the image in relation to the relief that is going to form on the sheet. Rather, the plastic sheet is heated to a first tempera ura, the vacuum mold is applied and the temperature is continuously increased, where the vacuum ensures the sheet and, consequently, fixes the image with respect to the surface of the mold. In other words, the optimum temperature necessary to form the plastic sheet is still reached, but this final softened state is only achieved after the plastic sheet is secured or contained in the female mold, at which point there is no remaining any possibility of deformation or displacement of the image in relation to the relief of the mold casing. The present invention uses vacuum, in opposition to prior art presses, to apply the necessary pressure to mold the PVC sheet. Although a vacuum forming machine may be less effective than the opposing pressing of coupling dies as described in the US Patent. No. 4,285,744, this invention overcomes most of the disadvantages, allowing the perforation of a multitude of tiny holes in the female die, which will result in the increased effectiveness of vacuum suction on the vehicle substrate of the image and, consequently, this will result in a greater definition of the embossed relief. Although the Patent of E.U.A. 4,308,224 describes the use of microscopically small air channels in the die, they are for a completely different purpose that allows the air to escape during the melting of the sheet. The ho a in its molten state takes the shape of the mold as the molten sheet flows into the mold and pulls the bottom au-e out of the sheet through the air channels. Although the method according to this invention may not result in a three-dimensional reproduction that is as high quality as in some other methods, the method provides a significant reduction in production time.

BRIEF DESCRIPTION OF THE INVENTION In accordance with an aspect of the invention, a vacuum forming process for molding a thin sheet of thermoformable plastic, and a reproduction in precise geometric relief of an original work, the sheet of plastic having printed on one side of the same a permanent image of the original work, the procedure includes: i) Keep the sheet of printed plastic next to a female mold of vacuum formation with the printed side facing the mold, the female mold having a surface relief in the same one that is a reproduction of the surface relief of the original work, the image coinciding with the relief of surface of the mold, a number of holes of formation of vacuum being provided with the mold; 11) heating said plastic sheet; iii) contacting the olde with the sheet while the sheet is heated to a first temperature that is lower than the normal thermoforming temperatures, where at the first temperature the movement of the image with respect to the mold due to the heating of the sheet is r-educate to the minimum, immediately applying a vacuum to the holes in the mold to begin the extraction of the plastic sheet in the mold and thus keep the sheet with respect to the relief of the rnolde to further minimize the movement of the image, on the ho with respect to the mold; iv) continue to heat the plastic sheet to a second temperature that is greater than the first temperature and to which the plastic sheet will be thermoformed, while maintaining the vacuum in the holes in the mold to complete the formation of the three-dimensional relief in the sheet; v) stop heating the plastLco sheet once a second temperature has been reached on the scale of the normal thermoforming temperatures, while continuing to apply vacuum to the mold holes, applying cooling to the sheet after the heating ceases, to cool the sheet below the first temperature to a third temperature to cause the three-dimensional relief formed in the sheet to be permanent; vi) stop cooling the blade and remove the blade from the blade. According to another aspect of the invention, an apparatus for forming in vacuum a thin sheet of thermoformable plastic in three dimensional reproduction in relief of an original work, the sheet of plastic having printed on one side thereof? Na permanent image of the original work, the apparatus comprising: i) a vacuum-forming female mold having a surface relief thereon which is a reproduction of the surface relief of the original work, a multitude of 20 vacuum-forming holes being provided in the mold; li) means for keeping the printed plastic sheet close to the mold, with the printed side facing the mold, the support means maintaining the image coinciding with the surface relief of the mold; Iii) means for heating the plastic sheet, the heating means being mounted on means for reciprocally moving the heating means from a first position Lclon away from the mold to a second position above and spaced from the non-printed side of the plastic sheet; iv) means for relatively moving the plastic sheet and the mold to contact the plastic sheet with the mold when the heating means in the second position heat the plastic sheet at a first temperature which is lower than the temperatures normal of moformaci n; v) meios to seal a perimeter of the plastic sheet to a corresponding perimeter of the mold; vi) means for applying vacuum to the multitude of holes in the mold when the sealing means seals the plastic sheet and the plastic sheet is at the first temperature; vile) the reciprocal means carrying the heating means back to the second position when the plastic sheet eet a second thermoforming temperature; vin) means for cooling the plastic sheet with the heating means in the second position; i) means for removing the vacuum from the multitude of holes when the plastic sheet is cooled by the heating means at a third temperature, the sealing means releasing a seal between the mold and the plastic sheet to allow the removal of the plastic sheet formed from the mold. li According to another aspect of the invention, a method for producing a male rnolde that is used to obtain a female mold, which is used to vacuum form a thermoformable plastic sheet to form a precise three-dimensional relief reproduction of a original work, includes: i) mounting a sheet of s? bst r-ato; 11) project an ungin of the original work on the substrate sheet; 111) apply a molding compound to the substrate to duplicate the brushstrokes of the original image, where the projection of the image on the substrate guides the application of the compound; and iv) allow the compound to harden to provide the mold from which the female mold is obtained. According to another aspect of the invention, there will be provided a method for producing a male mold that is used to obtain a female mold, which is used to vacuum form a thermoformable plastic sheet to form a napkin. reproduction in precise three-dimensional relief of an original work, and comprising: i) therm orm r a relief of the canvas in a thermoformable plastic sheet that has an image of the original work printed on it; n) apply a moldable compound to the printed surface of the sheet to duplicate on the image the brushstrokes of the original image, the printed image guiding the application of the compound; and 111) allowing the compound to harden to provide the male mold from which the female mold can be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS Preferred embodiments of the invention are described in relation to the drawings, wherein: The Figur-a 1 is a perspective view of the imaging system for projecting an image onto a substrate; Figure 2 is a perspective view of the application of a molding compound to the substrate to duplicate the brushstrokes of the origin; Figure 3 is a perspective view of the male rnolde formed to be mounted on a solid support; Figure 4 is a section along the section lines of Figure 3; Figure 5 demonstrates the pouring of a curable material from which the female mold is obtained; Figure 6 is a section through the male and female molds or are contained in a mold box; Figure 7 is a section through the female mold; Figure 8 shows the perforation of a multitude of holes in the female rnolde; Figure 9 is a perspective view of a portion thereof removed to show details thereof; Figure 10 is an enlarged section of the female rnolde, showing the holes of relative miniscule size provided on the relief surface; Figure 11 is a perspective view showing the assembly of the female mold in the vacuum box of the vacuum forming machine; Figure 12 is a section showing the support of the thin plastic sheet above the female mold, and the relative position of the heating device; Figure 13 shows the movement of the vacuum box upwards to seal against the heated thermoformable sheet, with the application of vacuum to form a relief on the sheet; Figure 14 is a perspective view of the vacuum forming machine; Figures 15A, 15B and 15C show the sequence of application of heat and the extraction of a vacuum on the sheet; Figure 16 is a top view of the sheet showing the temperatures of the sheet before the vacuum is applied in Figure 15C; Figures 17A, 17B and 17C show the sequence of events where the heating is removed, the vacuum is continued and cooling is applied to the thermoformed sheet; Figure 18 is a top view showing the temperatures of the sheet at the moment of removing the heating means, as shown in Figure 17A; Figure 19 is a view of the thin plastic sheet having an image printed thereon; Figure 20 shows the vacuum forming a rel i eve of the canvas on the printed plastic sheet of Figure 1; Figure 21 is an enlarged view showing the l Lenzo mounted on the vacuum box on which the sheet of Figure 19 is placed in the vacuum forrn of Figure 20; Figure 2? shows the ho a of plastic having the r-the? eve of the thermoformed canvas in it; Figure 23 shows the application, to the sheet of Figure 22, of a moldable compound to duplicate on the surface the brushstrokes of the ori inal; Figure 24 shows the application of a curable compound to form the female mold from the male rnolde of Figure 23; and Figure 25 is a section through the rim box of Figure 24, with the female mold being formed on the upper part of the male mold of Figure 23.

DETAILED DESCRIPTION OF THE PREFERRED MODALITIES The vacuum forming process according to this invention greatly accelerates the production time to produce a printed image on a plastic sheet which has formed therein a precise three-dimensional relief reproduction of the original work where the relief matches the image. The method and apparatus of this invention can be applied to obtain a variety of art reproductions that are used in several different fields. The conventional use is to form art reproductions that can have canvas support, asonite support or cardboard support where the reproduction, instead framed, seems to be essentially identical to the original. This reproduction of art can also be used in industry of the dress, where the work of different sizes and shapes, as it is produced by means of invention, can adhere to garments in the form of sheets, shirts, jackets, cotton pants and caps. Vacuum formed material can also be laminated to make sports bags, duffel bags, baseballs, footballs, footballs and other sporting goods. In the packaging industry, the vacuum formed images according to this invention can be applied to the package of products such as packaged foods, fragrances, clothing and clothing packages, and the like. These packages can then have a work surface surface that improves the marketing of the product. Other fields of use of the invention include in the application of the work formed in a vacuum in puzzles, painting by number, table games, maps and the like. Although techniques have been described for forming male and female molds from the original work, as previously discussed, this can greatly damage 1? original work, which may result in having to dispose of the original work or require extensive touches by the arti ta. In accordance with an aspect of this invention, as described in FIGS. 1 to 7, a female mold is obtained to carry out the unique aspects of the vacuum forming process and apparatus which do not require contacting the original work with any form of molding material. As shown in Figure 1, a substrate 10 is mounted on a solid support 12. The substrate 10, in accordance with this embodiment, comprises a sheet of canvas 14 mounted on a solid support 16. The solid support can be masonry? , cart n other piano material s? bstancialmen e rigid. A projection system 18 is separated from the substrate 10. The imaging system includes a slide 20 which is the positive of a negative exposure of the original work. This positive is developed in the normal technique of film processing, where the original is photographed with a camera, often a camera using the standard format of 10.16 crn x 12.70 cm. The image on the slide 20 is projected towards the projector 10 by a projection lamp 22. The image is focused on the substrate 10 by the usual focusing lens 24 on the projector 18. The image, once focused, it appears as a scene represented by a mountainous topography 26 on the canvas 14. It is understood that the projection of the image can be horizontal to allow it to work on a vertical surface, or the projection can be vertical to allow that can be worked on a horizontal surface. The objective is to reproduce now on the image, and on the upper part of the canvas, the brushstrokes similar to those of the original artist. As shown in figure 2, the brush strokes can be duplicated on the canvas using the image 26 lane guide. A mouldable compound is applied to the canvas by the use of a brush 28 and / or a spatula 30. The person applying the compound has artistic ability and is able to interpret the original work as shown by the image to apply a turbulent tex a surface on the canvas that duplicates the strokes and the sculptural ability of the original artLsta. There are several moldable compounds available to achieve this goal. For exampleAs the container 32 is supplied, a moldable acrylic polymer molding compound and / or acrylic polymer gel can be used. The operator slowly accumulates on the surface of the substrate the moldable compound to duplicate the strokes and the sculptural ability. The continuous projection of the image on the surface of the canvas 14 allows the operator to perfect the duplication of the brushstrokes over a prolonged period, where the projected image serves as a guide to ensure that the brushstrokes are applied properly to reproduce as accurately as possible. possible the surface texture in relief of the original work l. To help the artist reproduce the brushstrokes, the moldable material can be opaque and of a white color to increase and delineate the work reproduced. Using a white material, the projected image continues to appear clearly over the areas that have been covered with the compound. As shown in Figure 3, the finished reproduction of the brushstrokes 34 is mounted on a solid base 36. The solid base can be plywood? another rigid material of 1,905 crn. As shown in FIG. 4, the canvas 14 has on its surface the hardened molding compound 38. In section, the relief of the hardened compound 38 duplicates the brush strokes and sculptural ability of the original work. The hardened compound 38 thus forms on the canvas carrier 16, as it is mounted on the plywood 36, a male mold from which a female mold can be obtained. As shown in Figure 5, a frame 40 can be secured to the base 36 to provide sides 42 and vertical ends 44. A curable ream 46 is then poured from a container 48 to cover the male mold 34. The ream 46 in its uncured state immediately returns the surface relief of the male mold 34, as defined by the hardened compound 38. Sufficient resin is poured from the container 48 to completely cover the male mold 34 and up to a level in the framed mold to provide a female mold of a thickness on the scale of 0.635 cm x 1,905 crn. The section of figure ñ shows the female mold 50 having a retaining rnur 52 and contained within the frame 40. The male mold, as provided in the frame 40, has the support 36, the solid substrate 16 and the layer of canvas 14. Preferably, the hardened compound 38 is coated with an appropriate release agent to allow rowing <? on del del del del del del del del del del molde molde molde;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; For example, a preferred resin is an epoxy resin having up to 80% by weight of aluminum as well as a ter oconductive filler. The resin is cured by cyclic heating for 20 minutes and then for another 20 minutes without heating. An epoxy ca-feride resin can be obtained from Chetnque of Q? Ebec, and sold under the tradename Chemcast 402. After the ream is properly cured to a hardened state, the chassis 40 is removed and the mold 50 it is separated from the male mold 34. This provides in section the female mold 50 free of the male mold and carrying on its surface indentations 54 in relief which, in essence, is the negative of the positive image of the original brush strokes. As shown in Figure 8, the female mold 50 has perforated through its section a multitude of tiny holes. The holes can be formed by using a bore 56 with a drill 58. The drill bit is preferably 0.079 to 0.039 cm in diameter or less. The number of holes drilled to tr-birds of the female mold 50 will vary depending on the surface texture of the female mold. Normally, the holes are drilled every 1.27 cm to provide the scale of 9 holes for 6.45 crn of the surface of the female rnolde. Care is taken to drill the holes considering the fragile nature thereof so as not to chip the surface of the mold and also to judiciously locate the holes in the surface in the manner shown in relation to FIG. 10. The enlarged section of the female mold 50 shows a number of cuts 60 or fissures 62 on the surface. Therefore, the holes are not only drilled in the flatter portions 64, but also, careful steps are followed to ensure that the fine holes are also provided in the cuts or fissures 60 and 62. As shown in Figure 10, the very thin tiny holes extend through the body 66 of the female rnolde to the rear side 52 thereof. An exemplary hole is shown through the body 66 in 60. The female mold is then of a size that corresponds to the size of the work to be reproduced. A vacuum forming box 70, as shown in Figure 9, is provided with a cooling coil 72. The female mold 50 is inserted into the vacuum forming box 70 and is allowed to rest on the inner projection 74, Thus, the higher surfaces of the female mold 50 are below the perimeter edge and upper outer surface 76 of the mold box. The cooling coil 72 has an appropriate refrigerant introduced through the inlet 78 and desired coil through the outlet 80. Cooling water, gaseous refrigerant or the like thereof can be used, depending on the required cooling graph. F? The cooling coil is located in the vacuum forming box 70 so as to be immediately below and preferably in contact with the bottom side of the female mold 50. This ensures optimum cooling of the mold as required, particularly when the rnolde is used on a continuous basis and in the vacuum formation of the art reproductions. To facilitate vacuum formation, a vacuum is drawn through the conduit 82, and enters a full space below the female mold 50 as defined by the interior partition 84. The vacuum conduit 82 is in communication with the space filled, as defined by division 84 through an enlarged inlet 86. With the female mold 50 secured in the vacuum box 70 on top of the projection 74, a seal will be provided around the perimeter of the mold 50 so The vacuum, as it is drawn into the full space above division 84, maintains a vacuum over the hole 68 that is in communication with the surface of the female rnolde. The vacuum box 70, as shown in Figure 11, is assembled and ready to receive the thermoformable plastic sheet 88 having an image 26 printed thereon that is identical to the image 26 projected onto the substrate 10 of Figure 1. The objective it is now thermo ormar in the plastic sheet 88 the surface relief in order to duplicate the brushstrokes of the original. As is appreciated by those skilled in the art, there are several thermoplastic abl plastics that can be used in the vacuum forming process. The preferred thickness of the leaves is in the range of 10 to 12 inrn. Preferred plastic materials include copolymers of polyvinyl chloride, where the surface of the plastic sheets can be rationed in order to receive the printed image and permanently retain the image on its surface. Titanium dioxide and the like can also be included in the plastic material to impart a paper-like feel to the material, as well as to provide an appropriate base on which printing can be applied. The printing of the sheet can be carried out in accordance with any of the well known printing techniques, where the image, as printed on the sheet, is essentially identical in color and definition as the one found in the original. The ho a 88 is located on the vacuum ca 70 with the image 26 facing the female mold 50. Although it could be possible to locate the foil 88 on the female mold where the image 26 coincides with the gaps, cuts and grooves in the mold surface, it is best to insure the registration by using appropriate guides. As shown in the 21 figure 11, guide * ', in square 90 are provided in the corners and are of a s ^ c larnt that corresponds to the dimensional space of the corners 92 of the printed page 88. This ensures that the definition of the image colored on the sheet 88 coincides with the recesses of the female rnolde 50, so that when the sheet is thermoformed, the relief provided on the sheet 88 coincides with the image; therefore, when the completion of the sheet has been completed, the general effect is essentially identical to that of the original in that it duplicates the brush strokes and the sculptural ability of the original work. The Applicant has found that the female mold is the best attempt in the vacuum formation of the surface relief in the plastic sheet. This procedure is opposite to the standard technology of thermoforming in vacuum, when the inscription of the relief with the image on the sheet or-a important. For example, the Patent of F.U.A. The aforementioned Braund demonstrates the use of the accepted technology of the male mold to vacuum form a relief on the sheet that matches the printed image. Rather, the use of a female mold by the applicant will produce a number of significant benefits as it will be evident from the following discussion. For effecting the sheeting 88, it is supported slightly above the female mold 50 in the mold box 70. Being slightly up, it is intended that the sheet 88 be close to the coldly-filled female mold 50, but slightly separated from it. to facilitate rapid heating of the blade surface. The mold is supported by opposed fastening members 94 and 96. The fastening member 96 has a raised projection portion 90 about its perimeter where the edge portion 90 is identical to the boring dimension of 92. the plastic sheet 88. This ensures, with the proper placement of the fastening member 96, that the image on the underside of the sheet 88 coincides with the relief of the rim 50. Then, the fastening members 94 hold the sheet 88 against the members lower fasteners 96. A heating device 98 is carried on the upper part of the blade 88. The heating device can be mounted by means of rollers 100 on the rails 102 to allow reciprocal movement of the heating device on the blade 88. and away from it. The heating device 98 may include heating elements 104 which are electrically actuated to irradiate the sheet 88 with infrared radiation. Said heating of the sheet is controlled in a manner with respect to the sequence of events described with reference to Figures 15, 16, 17 and 18. In any event, the heating of the sheet 88 does not cause it to tilt, warp or hangs on the female mold 70, but softens it to a degree where it is about to lean towards, or on, the mold 50. This controlled heating of the sheet ensures that the printed image on the sheet does not move , so that once the mold makes contact with the sheet, the image still matches the relief of the female mold. As shown in Figure 13, during the continuous heating of the sheet 88, the roll case 70 is or Cam in the direction of the arrow 106 where the mold box includes a higher outer perimeter edge 76 which makes contact with the blade 88 around its corresponding outer perimeter edge B8A. At this time vacuum is applied to the conduit 82 to make a vacuum on the holes 68. The sheet is at a temperature at which it has softened slightly, so that the vacuum can pull the hole 88 downwardly on the relief surface 108 of the female mold 50. Due to the contact between the upper edge of the rim of the vacuum box 78 with the sheet in the region 88A, a seal is formed between the vacuum box and the sheet. Therefore, the vacuum made through the holes 68 pulls the sheet downwardly because no air enters between the sheet and the brake of the mold 100. Although the vacuum continues to be applied, the heating device 98 remains on the sheet. 88 continuing heating with infrared radiation 110 so that the sheet reaches s? normal temperature of termalization. As it will be discussed with resp >In the event cycle of Figure 17, the heat is finally removed, the vacuum is maintained, the sheet is cooled, and then the sheet is released by opening the fasteners 94 and 96 so that the sheet can be removed from the sheet. vacuum form box. Although it is understood that a variety of vacuum forming machines are available in which the vacuum forming box of this invention can be installed, a preferred apparatus is shown in Figure 14. The vacuum forming apparatus 112 comprises a base of support 114 on which a solid piece 116 is mounted. Dramatic cylinders 118 are used to raise and lower the solid piece 116, the movement is guided by guides 120. The holder for the sheet of plastic is in the form of fasteners 94 and 96 which are pivotally connected to a hinge mechanism at 122. The hinge mechanism 122 is secured to the base 114. The fasteners move toward each other and away from each other by hydraulic cylinders 124; the lower fastener 96 includes the flange area 90 to match the sheet 88 on the female mold 50 which is housed in the mold box 70. The inner perimeter of the fastener 96 is larger than the outer perimeter of the box of mold 70, as shown in Figure 13. The space between the outermost perimeter of the mold box, defined by the edge 76, is inside the interior 97 of the lower holder 96. In operation, the impression is placed in the lower fastener 96 and upper fastener 94 press against lower fastener by activating hydraulic cylinders 124. The device of 2? heating 98 on the rails L02 moves on the upper part of the sheet secured in the fasteners. Although the sheet is slowed to the first desired temperature scale, the roller box e? 0 moves upwardly within the holder 96 to extend the hydraulic cylinders 118. This performs, as described above, the sealing between the mold box and the hole 88. After finishing forming the sheet 88, the heating device 98 is retracted to its first position as shown in Figure 14, which then clears the arc so that cooling fans 126 are driven, mounted on the cross bar 128 to direct cooling air downwardly on the sheet 88. The sheet 88 is then cooled to the appropriate temperature to stabilize the integrity of the sheet so that it remains flat and essentially folds-free and ensures that the slight r-molding on the blade 88 is permanent. At that time the fasteners 94 and 96 are opened to allow removal of the sheet from the mold box 70. The cooling of the female mold 50 is preferentially effected on a continuous basis. Refrigerant is circulated through the coil 72 to continuously cool the mold 50. This cooling greatly decreases the cycle time of the vacuum forming machine 112 because the temperature of the mold surface 50 must be maintained below the temperature of the mold. temperature at which the sheet 88 cools before i-etn-aLa of the mold. However, it is understood that the cooling of the mold 50 may not be required when the cycle times of the machine are significantly increased. This provides enough time for the mold to cool after each cycle before it is re-applied to the sheet in the subsequent cycle. The cycle times for the machine are described with respect to Figures 15 to 18. In Figure 15A, the ho a 88 is held above the vacuum box 70 with the heater 98 in its first position. This is the beginning of the cycle. With the sheet 88 spaced slightly above the vacuum box 70, the heater 98 moves to its second position, as shown in Figure 15. Once the heater is located in its second position, this indicates time 0 of the cycle. Heat is applied to the sheet 88 until it reaches a first temperature which is below the normal temperature of formation for the selected thermoformable plastic. While this first temperature is reached, the vacuum box 70 moves upwardly in the direction of the arrow 106 and is emptied through the conduit 82. This pulls the sheet 88 against the female mold in the manner described with respect to the Figure 13. The temperatures for the sheet are illustrated in Figure 16. Thermocouples are located on the sheet to determine its surface temperature at the time the vacuum is applied and also provides an average value for the first temperature. As shown in Figure 16, the temperatures on the surface of the sheet are quite consistent and range from 95 ° C to 100 ° C. The preferred scale is therefore around 90 ° C to 100 ° C for this particular degree of plastic sheet which is made of PVC polymer. At this temperature, the PVC sheet is not considered to be thermoformable; however, it is sufficiently foldable so that when it is applied empty to the sheet it moves downwards on the surface of the mold. However, the sheet still has sufficient structural integrity so that it does not conform exactly to the surface of the mold in terms of taking the shape of all the cuts and slits in the mold. As previously described, in this first temperature scale, the sheet, although it is softened, does not lean, sag or hang appreciably and certainly does not lean to such an extent that it makes contact with a significant portion of the mold. At the first temperature, the leaf may arch slightly downward in the middle because the leaf is supported around its perimeter. This slight arching does not cause movement of the impure image on the underside of the sheet in relation to the relief of the surface of the mold, therefore the image remains aligned with the relief on the surface of the mold. As it is generally understood, as the plastic is heated, the plastic usually starts to move due to irregularities in physical properties through the length of the sheet and also due to the memory of the sheet with respect to deformation and stress. It has therefore been discovered that the application of a vacuum on the sheet before the image begins to move around the sheet, can maintain the consistent position of the image with the relief of the mold and can reduce to the minimum or essentially eliminate the dLstor-siori in the image of the final product. The vacuum is continued on the vacuum box 70 through the conduit 82 where the sheet 88 is against the face of the mold surface. As the heating of the blade continues its temperature rises to normal temperatures of the formation, which allows the blade to move then towards all the cuts, slits and other depressions of the relief in the female mold, thereby completing the formation of the relief seen on the surface of the sheet on the printed side. It has been found that the vacuum applied to the conduit 82 is within the normal range of approximately 1.4 kg / crn2 according to the vacuum indicator which provides an external pressure on the sheet 88 equivalent to the atmospheric pressure of 1.03 Kg / cm2 . When the sheet has reached a second temperature which is within the normal ranges of forming temperature, the heating device 98 is retracted towards the first position while keeping vacuum on the vacuum box 70. Co or shown in FIG. Figure 18, the temperature of the sheet at the time of retraction of the heating device 98, is approximately on the scale from 155 ° C to 160 ° C. Again, the discrepancies in temperatures across the sheet are due to the type of heating device used, as well as the space between the heating device and the sheet, air currents and the like that can cause regional cooling in the sheet. The second preferred temperature for this particular type of sheet is then in the range of 150 ° C to 170 ° C which is considered to be in the upper range of normal temperatures of the polymerization process for the selected polyvinyl chloride copolymer sheet Lo, One advantage of using a female mold is that the printed side of the sheet is against the surface of the mold. This ensures that the relief molded on the surface of the sheet is a well-defined reproduction of the relief of the rnolde. This can not be achieved with a male mold because the printed surface is opposite the surface of the female mold, the definition of the mold relief is lost through the thickness of the sheet. With the heating device 98 in its second position, the surface of the sheet 88 is exposed, as shown in Figure 17B, with the continuous vacuum to be applied. As shown in Figure 17C, two cooling fans 126 are activated to direct cooling air in the direction of the arrows 128 on the surface of the sheet. As already noted, the vacuum box 70 includes cooling coils to ensure that the temperature of the female mold is below the desired third temperature at which the thermoformed embossing on the plastic sheet becomes perrnantonte. Preferably, the third temperature for the selected polyvinyl chloride-copolymer sheet is in the range of 50 ° C or less. It is possible to control the sequence of events for the vacuum forming machine by measuring the temperature of the surface of the sheet 88. It has been found that due to the consistency in the physical characteristics of the ho 88, it is possible to operate the vacuum forming machine 112 based on the cycle times. For the selected polyvinyl chloride copolymer sheet, it has been found that the ideal treatment times for the type of heating device used is to heat the sheet to the first temperature in 10 to 12 seconds. Vacuum application from approximately 17 seconds to 25 seconds. The heater is removed and moved to its first position after 25 seconds from the start. Vacuum is continued to apply and cooling is directed on the sheet for an additional 20 to 25 seconds to which, after a total of 32 to 50 seconds, the fasteners are released and the sheet is removed. Considering approximately a time setting of 15 seconds and locating the ho in the machine, and approximately 15 seconds to remove the sheet from the machine, a total cycle time of about 1.5 minutes is provided. It is appreciated that the vacuum forming machine can be automated to further reduce the cycle time. This cycle time is considerably shorter than CLCÍO's time for other plastic thermoforming machines to make artistic reproductions. Normal CLOC times for most of the prior art machines are in the range of 5 to 6 minutes. Therefore, by means of the method and apparatus of this invention, the cycle time is considerably reduced to realize a significant economy in production while continuing to produce an acceptable product for different segments of the market. Although the vacuum can remain applied to the vacuum box until the end of cooling, it has been found that in most applications with PVC sheet, the vacuum can be removed from the vacuum box approximately 45 seconds from the start , since with the appropriate cooling devices, the ho is cooled to a sufficiently low temperature, so that the thermoformed relief in the sheet remains in its defined pattern. However, if there are difficulties in this regard, it is advisable to maintain the vacuum until the end of the cooling cycle and the temperature is reduced to an acceptable level in the range of 49 ° C or less. As an alternative embodiment to the method described with respect to FIGS. 1 to 6, FIGS. 19 to 25 indicate another method for manufacturing the male mold. As shown in Figure 19, a plastic sheet 130 that can be made of PVC material has an image 132 printed thereon. The sheet is substantially flat and smooth and in essence is the same as the sheet 88 used with respect to the thermoforming process described in Figure 11. To modify the ho to 130 to resemble an original piece of art, a shape is formed. relief of canvas on the surface. This is achieved by holding the blade 130 in the fasteners 96 and 98 above a vacuum box 70. A cloth 134 is stretched over the vacuum box 170 where the edge of the perimeter 76 of the vacuum box elevates the portion. of edge 136 of the canvas sheet. With the vacuum box (O raised against the plastic sheet 130, the heating device 98 applies heat to the sheet 130. Vacuum is applied to the conduit 82 to pull the sheet 130 down on the canvas 134 where it is formed a seal in the region 138 as the sheet is pushed against the edge 76 with the canvas 134 sandwiched between them.The heating and vacuum are continued until the matrix of the canvas is formed in relief on the plastic sheet 130. The process of Heating is conducted from rn <;: It is important to ensure that the image 132 is not distorted, so that as the sheet cools and is removed from the vacuum forming mold, it resembles the sheet 140 as shown in FIG. 22, where a canvas matrix 142 is attached. on the surface of the sheet that has the image 132. To duplicate the brushstrokes on the thermoform sheet at 140, an artist uses a molding compound that is applied to the image in order to reproduce the brushstrokes of the original. Preferably, the molding compound applied to the surface of the sheet 140 is clear, so that the image 132 continues to be visible below the molding compound. A suitable molding compound which is in this respect is the clear acrylic polymer gel used by artists for certain artistic works in acrylic. The molding compound, supplied in the container 144, is applied with a brush 146 or blade blades, sponges, cloths or rubbing fabrics such as those commonly used by artists. The clear molding compound is allowed to harden and then forms the male mold to form the female mold. With the first embodiment of Figures 5 and 6, a curable resin 46 is poured onto the surface of the male mold 148 from the container 48. The male mold 148 is supported on a plywood backing or the like, as shown in FIG. made with respect to the embodiment of Figure 3, and surrounded by an appropriate frame 40. The curable ream 40 is poured into the roll case and is contained by the frame 40 to a level shown in Figure 25. After the ream 46 is cured to form a female mold body 150 which has a smooth rear face 152 and a three-dimensional relief face 154 which is the replica of the female mold of the surface of the male mold 148. As with the first embodiment , the male mold surface can be treated with a release material such as silicone. After the resin is cured to form a female mold hard body 150, the mold is opened and the female mold is released from male die 148. The female mold is now ready for treatment according to the embodiments of Figures 7 and 8 before installation in the vacuum box 70. In accordance with the second embodiment to form the female mold, a direct approach is achieved in the provision of brush strokes on the surface by the use of the molding compound. Assuming that the material selected for the sheet 130 is easily thermoformable, the canvas matrix is easily provided on the sheet. However, for selected materials or thicker materials that are desired in the manufacture of the male rnolde, the first mode is preferred since the artist reproduces the brushstrokes directly on the canvas material. In accordance with this invention, a quality is produced. consistency of product that constitutes a faithful reproduction of the original artistic work. The products made by the method and apparatus of this invention have many end uses as discussed above and are not limited only to the reproduction of original works that are framed, Although the preferred embodiments of the invention have been described in detail in the present, those skilled in the art will understand that variations may be made therein without departing from the spirit of the invention or the scope of the appended claims.

Claims (8)

NOVELTY OF THE INVENTION CLAIMS

1. - A vacuum forming process for molding a thin sheet of plastic ter oformahle in an exact reproduction of three-dimensional relief of an original work of art, said sheet of plastic has printed on one side thereof a permanent image of said work of art. original art; Said method comprises: (i) holding said printed plastic sheet next to a vacuum forming mold with the printed side facing the mold, said female mold having a surface relief therein which is a reproduction of the embossed pattern. surface of the original artwork, said image coincides with the surface relief of the mold, a multitude of vacuum forming holes are provided in the mold; (11) heating said plastic sheet; (in) contacting said mold with the sheet while the sheet is heated to a first temperature below normal thermoforming temperatures, wherein the first temperature minimizes the movement of said image relative to the mold due to heating of the sheet, by immediately applying a vacuum to the holes in the mold to begin to pull the plastic sheet towards the mold and thereby fix the sheet in relation to the relief of the mold to further minimize the movement of the image on the sheet. the sheet in relation to the mold; (iv) continue heating l o. plastic sheet while keeping empty on the holes in the mold to finish the formation of the three-dimensional relief on the sheet; (v) stopping the heating of said plastic sheet once a second temperature has been reached in the normal thermoforming temperature range while continuing to apply vacuum to the mold holes, cooling said sheet after stopping the heating or par ' to cool the sheet below the first temperature to a third temperature to make permanent the three-dimensional relief formed in the sheet, (vi) stop the cooling of said sheet and remove the sheet from the mold.

2. A process according to claim 1, further characterized in that said mold is cooled to maintain the mold at a temperature below the third temperature to help cooling the sheet to the third temperature.

3. A method according to claim 2, further characterized in that said mold is continuously cooled during the vacuum forming process.

4. A method according to claim 1, further characterized in that said multitude of vacuum-forming holes are each of miniscule dimension to prevent vacuum dragging of said sheet in the holes. . - A method according to claim 4, further characterized in that the localization of said holes in the mold includes placing the holes in relatively deep holes in the mold relief to improve the formation of the relief desired in the ho a. 6. A method according to claim 1, further characterized in that said sheet is held within less than 2.5 cm. above said mold to provide rapid heating of the sheet and rapid contact with the blade once the sheet is heated to the first temperature. 7. A method according to claim 6, further characterized in that the sheet is held around its periphery on the mold when the sheet and the mold are in contact to ensure the application of vacuum to the printed sides of the sheet. 8. A method according to claim 4, further characterized in that said holes are 0.08 crn. or less in cross section. 9. A method according to claim 4, further characterized in that said plastic sheet is polyvinyl chloride, the first temperature is in the range of 90 ° to 100 ° C, the second temperature is in the scale 150 ° axis at 170 ° C, and the third temperature is less than 50 ° C. 10. An apparatus for the vacuum formation of a thin sheet of thermoformable plastic in an exact repi odion of three-dimensional relief of an original work of art, the plastic sheet has printed on one side of it a permanent ungen the original work of art, the apparatus comprises: (i) a vacuum-forming female mold that has a surface relief in it that is a reproduction of the surface relief of the original work of art, a multi-unit of forming holes of vacuum are provided in the mold; (??) means for holding the printed sheet of plastic next to said rnolde with the printed side facing the mold, said supporting means supporting the image coinciding with the surface relief of the rnolde; (111) means for heating the plastic sheet, said heating means being mounted on means for reciprocally moving the heating means of a first position away from the mold towards a position on, and separated from, the non-printed side of the mold. the plastic sheet; (iv) MEDALS to determine the temperature of the plastic sheet as it is heated with the heating means; (v) means for moving the plastic sheet and the mold in relation to one another to contact the plastic sheet with the mold when said temperature determining means determine that the plastic sheet is heated to a first temperature that is below normal thermoforming temperatures; (vi) means for sealing a perimeter of the plastic sheet to a corresponding perimeter of said mold; (vii) means for applying a vacuum to said multitude of holes in the mold with the sealing means sealing the plastic sheet; (vm) said reciprocal movement means move the heating means back to its mere end position when the temperature demining means determine that the plastic sheet is heated to a second temperature of mformation; (ix) means for cooling the plastic sheet with the heating means in the first position; (x) means for removing said vacuum from the multitude of holes when said determined means of temperature determine that the plastic sheet has been cooled by said cooling means to a third-at temperature, the sealing means release a seal between the mold and the ho a of plastic to allow the removal of the plastic sheet formed from the rnolde. 11. An apparatus in accordance with the claim 10, characterized in that means are provided for cooling the mold to maintain the mold at a temperature below the third temperature. 12.- An apparatus in accordance with the claim 11, further characterized in that a cooling coil is provided in contact with the rnolde below said surface relief. 13. An apparatus according to claim 12, further characterized in that said multitude of holes each have 0.08 cm. of diameter or less, means that enclose the holes to provide a plenum chamber behind said mold, empty vacuum is in communication with said plenum chamber. 1

5. An apparatus according to claim 14, further characterized in that said means of relative movement move the mass toward the plastic sheet and the sealing means seal a perimeter portion of the plastic sheet within said fastener. , to the corresponding perimeter of said mold., 16.- An apparatus according to the claim 10, further characterized in that said heating means comprise a heating element for radiation heating of the plastic sheet. 17. An apparatus according to claim 10, further characterized in that said cooling means comprise a cooling fan for directing air < - cooling on the plastic sheet when the means of reciprocal movement move said heating means back to the first p > ostion 18. An apparatus in accordance with the claim 10, further characterized in that a controller controls the axis time axis regulation the activation of said reciprocal movement means, said reciprocal movement means, said sealed axis means, said means for applying vacuum and said means to remove vacuum during the formation of empty axis for molding a relief on the plastic sheet. 19 -. 19 - An apparatus according to claim 10, further characterized in that means are provided for matching the image with the surface relief of said mole. 20. In a production method of a male axle to be used in the manufacture axis a cast mold that is used in the vacuum formation of a thermoformable plastic sheet to form an accurate relief reproduction tridi As part of an original work of art, said method includes: (i) mounting a substrate sheet; (n) project an image of the original work of art on said substr-ato sheet; (u) applying a mouldable compound to the substrate to duplicate brushstrokes of the original image wherein the projection of said image on the substrate guides the application of said compound; (iv) allow to harden said compound to provide the mold from which a female mold can be made. 21. In a method according to claim 20, said compound is selected from the group consisting of an acrylic polymer molding paste, an acrylic polymer gel and a mixture thereof. 22. In a method according to claim 20, said substr-ato is a canvas sheet mounted on a solid support. 23. In a male shaft production method for use in the manufacture of a female mass which is used in the vacuum formation of a thermoformable plastic sheet to form an accurate reproduction of a three-dimensional relief of a solid construction. Originally, said method comprises: (i) thermoforming a relief of canvas on a sheet of ter-rnoforma plastic that has an image of said original work of art on it; (11) apply a smerable compound to the printed surface of the sheet to duplicate on said image the brushstrokes of the original image, dThe printed image guides the application of said compound; (111) allow to strengthen said compound to provide said male olde to which it can be made a female rnolde. 24. In a method according to claim 23, said mold compound is transparent. 25. In a method according to claim 24, said molding compound is a g L of clear acrylic. 2

6. In a method according to claim 23, said sheet of plastic is polyvinyl chloride.