Thermoforming machine and method

Abstract

The thermoforming machine (30) comprises a thermoforming chamber (32) having at least one hot air inlet (34) through which hot air flows into the thermoforming chamber (32) at a controlled pressure. The air inlet (34) cooperates with a hot air flow distribution regulator (40) located in the thermoforming chamber (32) and through which hot air flows out of the thermoforming chamber (32) at a predetermined temperature. The regulator (40) comprises a hot air flow regulation mask (42) which receives the hot air flow and has a plurality of flow restriction elements providing different air flow restrictions.

Description

Technical Field

[0001] The present disclosure relates to a thermoforming machine and method. Such thermoforming can be used, for example, in a process for laminating a functional multilayer film onto an optical article such as an ophthalmic lens by using increased pressure and temperature. Background Art

[0002] "Functional film" refers to a film that provides at least one of the following features to an optical article, including hard coating, anti-scratch properties, anti-reflective coating, polarizing film, tint, reflector or filter for specific wavelengths, impact resistance, anti-fouling, anti-fog, self-healing, self-cleaning or anti-static properties, etc.

[0003] "Laminating" a film on an optical article refers to an operation involving depositing the film on the surface of the optical article to be laminated. Typically, the lamination operation is performed by first providing the film disposed on a support. The film and support are then pressed onto the surface to be laminated by applying a pressure difference between one side of the support having both the film and the optical article and the other side, or by applying a force from the optical article side.

[0004] An adhesive, such as a pressure-sensitive adhesive, is usually pre-disposed on the face of the film that is intended to be pressed against the surface in order to maintain the film on the surface.

[0005] In alternative processes, the adhesive is positioned on the optical article before pressing the film onto the optical article and / or the film is pressed onto the optical article without being secured to a carrier, but for example by applying pressure directly on the film or using a punch or blown film or balloon.

[0006] In the field of optical product manufacturing, film lamination processes typically require pre-processing or "forming" of the consumable or laminate composite so that the film can be formed to have a given curvature to conform and match the curvature of the surface-treated prescription ophthalmic lens so that it can be laminated better than a flat film, whether on the convex or concave side of the lens.

[0007] To laminate the lens, in order to introduce the desired curvature with a customized radius such as Figure 1 In the illustrated membrane composite or consumable 10, the consumable 10 comprises a carrier 12 and a membrane patch 14 glued to the carrier 12, the consumable 10 being clamped and inflated, typically by thermoforming. Figure 2 Shown from top to bottom Figure 1 Three consecutive stages of thermoforming of the consumable 10.

[0008] When thermoforming, it is desirable to have a Figure 2 The heat distribution in the patch 14 is uniform.

[0009] Furthermore, it is desirable to maintain a controlled pressure within the thermoforming chamber.

[0010] When hot air is introduced into the thermoforming chamber, the hot air flow is directed and directed towards the patch to heat it by convection. The air temperature must be maintained within a predetermined range, such as between 100 degrees Celsius and 115 degrees Celsius, depending on the desired sag or curvature of the laminated film.

[0011] If the air flows only to the center of the patch and heats it from the center outwards, this will cause a large temperature gradient in the film, with the area of ​​the film under the air flow being hotter than other areas. This is not suitable for thermoforming. Summary of the invention

[0012] The object of the present disclosure is to overcome the above-mentioned disadvantages of the prior art.

[0013] To this end, the present disclosure provides a thermoforming machine, which includes a thermoforming chamber having at least one hot air inlet, through which hot air flows into the thermoforming chamber at a controlled pressure, wherein the air inlet cooperates with a hot air flow distribution regulator located in the thermoforming chamber, and through the hot air flow distribution regulator, the hot air flows out of the thermoforming chamber at a predetermined temperature, the regulator including a hot air flow regulation mask, which receives the hot air flow and has a plurality of flow restriction elements providing different air flow restrictions.

[0014] This makes it possible to reduce the temperature gradient in the component being hot-formed during hot-forming, thereby significantly improving the curvature accuracy of the component.

[0015] The present disclosure also provides a thermoforming method using a thermoforming machine as briefly described above, for imparting a predetermined curvature to a film to be applied to an optical article, the film being placed below the mask so as to be centered relative to the mask, wherein hot air flows from a hot air inlet into a thermoforming chamber at a controlled pressure and flows out of the thermoforming chamber at a predetermined temperature by passing through the hot air flow regulating the mask, thereby generating a uniform heat distribution within the film until a predetermined target curvature is obtained.

[0016] The present disclosure further provides an optical article comprising a front face and a back face, wherein at least one of the front face and the back face is coated with a film thermoformed by implementing the thermoforming method as briefly described above.

[0017] The present disclosure further provides an assembly comprising a thermoforming machine and a film and / or a film patch and / or an active film and / or an adhesive to be thermoformed by the thermoforming machine, the thermoforming machine comprising a thermoforming chamber having at least one hot air inlet through which hot air flows into the thermoforming chamber at a controlled pressure, wherein

[0018] The air inlet cooperates with a hot air flow distribution regulator located in the thermoforming chamber, and through which the hot air flows out of the thermoforming chamber at a predetermined temperature, the regulator comprising a hot air flow regulation mask, which receives the hot air flow and has a plurality of flow restriction elements providing different air flow restrictions,

[0019] In one embodiment of the assembly, the membrane and / or the membrane patch and / or the active membrane and / or the adhesive has a non-circular predetermined shape, and the plurality of flow restriction elements have a geometric shape that is the same as or similar to the predetermined shape of the membrane and / or the membrane patch and / or the active membrane and / or the adhesive,

[0020] Alternatively, the membrane and / or membrane patch and / or active membrane and / or adhesive has a predetermined shape and a plurality of flow restricting elements are distributed over the center of the hot air flow conditioning mask and a predetermined number of concentric shapes having the same geometry as the predetermined shape of the membrane and / or membrane patch and / or active membrane and / or adhesive.

[0021] In the above context, the non-circular predetermined shape of the film and / or film patch and / or active film and / or adhesive corresponds to the contour of the film, the thermoforming cavity for the strong thermoforming shape, and the minimum features that may be present in the film between patches that are thereafter destined to be transferred to an ophthalmic lens.

[0022] In the above context, a non-circular shape means that more than 3% or preferably more than 5% of the effective surface of the membrane and / or membrane patch and / or active membrane and / or adhesive lies outside the largest inscribed circle that can be inscribed in the shape of the patch. In this context, the effective surface of the membrane patch corresponds to the surface of the membrane patch excluding one or more possible treatment flaps or strips.

[0023] Since the method, optical article, and assembly according to the present disclosure have the same advantages as the thermoforming machine, they will not be described in detail here. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] For a more complete understanding of the description provided herein and its advantages, reference is now made to the following brief description taken in conjunction with the accompanying drawings and detailed description, wherein like reference numerals represent like parts.

[0025] Figure 1 is a schematic diagram of a prior art consumable to be thermoformed.

[0026] Figure 2 is a set of three schematic diagrams showing Figure 1 State of the art thermoforming of consumables in successive stages.

[0027] Figure 3 is a schematic diagram of a thermoforming machine according to the present disclosure in certain embodiments.

[0028] Figure 4 is a schematic diagram of an air flow conditioning mask included in a thermoforming machine according to the present disclosure in certain embodiments.

[0029] Figure 5 is a set of two schematic cross-sectional views of an air flow conditioning mask included in a thermoforming machine according to the present disclosure in certain embodiments.

[0030] Figure 6 is a schematic diagram of an air flow conditioning mask included in a thermoforming machine in accordance with the present disclosure in certain embodiments and a corresponding film patch included in an assembly in accordance with the present disclosure in certain embodiments. DETAILED DESCRIPTION

[0031] In the following description, although making and using different embodiments are discussed in detail below, it should be understood that many inventive concepts that can be implemented in a variety of environments are provided as described herein. The embodiments discussed herein are merely representative and do not limit the scope of the present disclosure. It is also obvious to those skilled in the art that all technical features defined in relation to the process can be transposed to the device alone or in combination, and conversely, all technical features related to the device can be transposed to the process alone or in combination, and the technical features of different embodiments can be exchanged or combined with the features of other embodiments.

[0032] The terms "comprise" (and any grammatical variations thereof, such as "comprises" and "comprising"), "have" (and any grammatical variations thereof, such as "has" and "having"), "contain" (and any grammatical variations thereof, such as "contains" and "containing"), and "include" (and any grammatical variations thereof, such as "includes" and "including") are open-ended linking verbs. They are used to indicate the presence of the features, integers, steps or components or groups thereof, but do not exclude the presence or addition of one or more other features, integers, steps or components or groups thereof. Thus, a method or step in a method that "comprises", "has", "contains" or "includes" one or more steps or elements possesses those one or more steps or elements, but is not limited to possessing only those one or more steps or elements.

[0033] like Figure 3 As shown, a thermoforming machine 30 according to the present disclosure includes a thermoforming chamber 32 .

[0034] The thermoforming chamber 32 has at least one hot air inlet 34, through which hot air flows from the air inlet 31 at room temperature through the inline heating tube 33 into the thermoforming chamber 32 at a controlled pressure. To this end, the thermoforming chamber 32 may include a back pressure regulating diaphragm 36 and a pressurized air inlet 38 for back pressure regulation. The thermoforming chamber 32 may further include a thermocouple 35 for controlling the temperature. The thermocouple is further capable of controlling the process of reaching or maintaining a predetermined temperature.

[0035] The hot air inlet 34 cooperates with a hot air flow distribution regulator 40 located in the thermoforming chamber 32. The hot air flows out of the thermoforming chamber 32 through the air flow distribution regulator 40 at a predetermined temperature. The hot air flow distribution regulator 40 can control the air flow distribution within the thermoforming chamber 32. Since the air flow is hot air, the temperature distribution within the chamber can be controlled. In fact, the air flow is heated before entering the thermoforming chamber 32, and the air flow temperature is easily controlled and predetermined. Further, controlling the temperature within the thermoforming chamber 32 becomes associated with controlling the hot air flow rate within the thermoforming chamber 32.

[0036] According to an embodiment of the present disclosure, the hot air flow distribution conditioner 40 is oriented toward the opening in the thermoforming chamber 32 that is destined to be closed by the film to be thermoformed.

[0037] In another embodiment, the hot air flow profiler 40 is positioned relatively parallel to the opening, or such that if the film to be thermoformed is substantially flat prior to thermoforming, the film is substantially parallel to the hot air flow profiler 40 prior to thermoforming.

[0038] According to the present disclosure, the conditioner 40 includes a hot air flow conditioning mask 42 that receives the hot air flow and has a Figure 4 A plurality of flow restriction elements 44 are shown, thereby providing different air flow restrictions.

[0039] In one embodiment, the plurality of flow restricting elements 44 are distributed from the periphery to the center of the mask 42 in such a manner that a first one of the flow restricting elements 44 restricts air flow less than a second one of the flow restricting elements 44 .

[0040] This causes a reduction in direct air flow in the periphery of the patch, which balances the effect of indirect air flow heating caused by hot air flowing from the center of the patch to its periphery. Thus, uneven heating is avoided.

[0041] For example, the size of the first flow restriction element in the flow restriction element 44 may be larger than the size of the second flow restriction element in the flow restriction element 44 .

[0042] In one embodiment, the first flow restricting element 44 is closer to the center of the mask than the second flow restricting element 44 .

[0043] In another embodiment, in contrast, the second flow restricting element 44 is closer to the center of the mask than the first flow restricting element 44 .

[0044] exist Figure 4 In the particular embodiment shown, the plurality of flow restriction elements 44 are distributed on a predetermined number of concentric circles 46, the center of the concentric circles being the center of the mask 42. In addition, at least one flow restriction element 44 may be disposed in the center of the mask 42.

[0045] A circle is a non-limiting example of a geometric shape that can be replaced by another shape. In another embodiment, the plurality of flow restriction elements 44 are distributed on a predetermined number of concentric contours, which may be related to the shape of the patch 14, such as an elliptical shape, such as Figure 6 shown.

[0046] exist Figure 4 In the particular embodiment shown, the flow restriction elements 44 located on the same shape of the concentric shapes (i.e., in this non-limiting example, located on a given same circle of the concentric circles 46) have the same size. Moreover, the flow restriction elements 44 located on the same shape of the concentric shapes (i.e., in this non-limiting example, located on a given same circle of the concentric circles 46) can be equidistant from each other.

[0047] By way of non-limiting example, the number of concentric shapes can be 5 and the value of the angular sector between two adjacent flow restriction elements 44 on the same shape can be between 9° and 60°, in particular approximately 9° for the outermost concentric shape and approximately 60° for the centermost concentric shape.

[0048] In one embodiment, the at least two concentric shapes are such that the angular sectors described above are larger for the concentric shapes that are closer to the center of the mask 42 .

[0049] exist Figure 4 In the particular embodiment shown, the flow restriction element 44 is a circular opening. By way of non-limiting example, the diameter of the opening may be between 1 mm and 10 mm, particularly about 1 mm for the opening of the outermost concentric shape and about 10 mm for the opening at the center of the concentric shape.

[0050] However, the flow restricting element 44 may have any other geometric shape, such as a square, a rectangle, a triangle, an oval, a patch-like profile, etc., and may have any suitable size.

[0051] In one embodiment, the hot air flow distribution conditioner 40 may have a flat surface.

[0052] In one embodiment, the hot air flow distribution conditioner 40 may have a curved surface.

[0053] Moreover, the flow restriction element 44 can have a variable volume. In other words, the volume of a given element 44 (e.g., the volume of the opening in a given element 44) can be different from the volume of the opening in another element 44 in the same regulator 40. In addition, the air flow can be controlled by the size of the cross-sectional area of ​​the flow restriction element 44, because a small cross-sectional area may result in high friction, but the air flow can also be controlled by the depth or height of the flow restriction element 44 and / or the form of the air path through the flow restriction element 44. Figure 5 Two non-limiting examples of masks 42 are shown in cross-section. Figure 5 In the example on the right, one of the elements 44 has a path where the air flow direction changes, and the flow restriction element 44 has a variable volume.

[0054] A thermoforming method using a thermoforming machine as described above makes it possible to impart a predetermined curvature to a film to be applied to an optical article.

[0055] The film is placed under the mask 42 so as to be centered relative to the mask 42. Securing the film under the mask 42 enables the thermoforming chamber 32 to be sealed.

[0056] Then, the hot air flows from the hot air inlet 34 into the thermoforming chamber 32 at a controlled pressure and enters the initial pressure zone 50 of the thermoforming chamber 32 (see Figure 3 The hot air is directed to zone 50 in the film and begins to flow out of the thermoforming chamber 32 at a predetermined temperature through the mask 42 through the hot air flow distribution regulator 40 at a predetermined low threshold pressure, thereby producing a uniform heat distribution within the film until a predetermined target temperature is reached, which target temperature depends on the material and / or the final curvature or sag desired for the film.

[0057] Once the target temperature is obtained, the back pressure regulating diaphragm 36 for controlling the pressure increases the pressure in the upper heating chamber or the lower chamber (if any), for example by 0.03 bar / sec, up to, for example, 5 bar.

[0058] The pressure is increased until the target thermoforming curvature is achieved or until the maximum allowable pressure (predetermined high threshold pressure) is reached.

[0059] The back pressure mechanism maintains the pressure within the thermoforming chamber 32 by introducing pressurized air over the back pressure regulating diaphragm 36 through the pressurized air inlet 38. If the pressure within the thermoforming chamber 32 exceeds the back pressure on the diaphragm 36, the diaphragm 36 opens and releases air from within the thermoforming chamber 32, thereby reducing the pressure. This enables the pressure within the thermoforming chamber 32 to be controlled throughout the process while maintaining a constant flow of hot air from the hot air inlet 34 at a controlled temperature.

[0060] By way of non-limiting example, the temperature may be comprised between 100°C and 140°C and is preferably 120°C.

[0061] By way of non-limiting example, the pressure may be comprised between 0.2 bar and 8 bar, preferably between 0.5 bar and 6 bar.

[0062] Depending on the size of the thermoforming chamber 32 , the hot air may have a flow rate comprised between 20 l / min and 160 l / min, preferably 60 l / min.

[0063] Alternatively, the pressure in the thermoforming chamber 32 may be maintained at atmospheric pressure. In this case, the increased pressure for forming may be applied to the film from the opposite side of the film patch facing downward, the pressure from below introducing a convex shape suitable for front side lamination.

[0064] At least one of the front and back surfaces of an optical article, such as an ophthalmic lens, may be coated with a film thermoformed in the various ways described above.

[0065] In one embodiment of a component according to the present disclosure, comprising a thermoforming machine as described above and a film and / or a membrane patch and / or an active (functional) film and / or an adhesive to be thermoformed by the thermoforming machine, wherein the film and / or the membrane patch and / or the active film and / or the adhesive have a predetermined shape, the flow restricting element 44 included in the hot air flow regulating mask 42 can have a geometric shape that is the same as or similar to, or at least reminiscent of, the geometric shape of the shape of the film and / or the membrane patch and / or the active film and / or the adhesive.

[0066] Figure 6 A non-limiting example of such a flow restriction element 44 is illustrated (shown on the right side of the drawing).

[0067] like Figure 6 As shown, the contour of the set of flow restricting elements 44 has a geometry that generally matches the geometry of the shape of the membrane patch 14 .

[0068] In this particular example, the concentric shapes are not circles, but ellipses, as shown by the concentric ellipses 46'. The two concentric ellipses 46' are shown in dashed lines, which have been added to the drawing to better illustrate the concentric ellipses 46'.

[0069] In this particular embodiment, the concentric shapes are concentric ovals 46' and generally match the membrane patch 14 (shown on the left side of the figure).

[0070] In addition, the same Figure 6 As shown in the non-limiting example of , each flow restriction element 44 itself is elliptical.

[0071] However, features relating to the elliptical or circular or other geometric shape of the flow restriction element 44 itself and / or the concentric circles 46, respectively the ellipses 46' and / or the similarity between the shape of the membrane patch 14 and the contours of a set of flow restriction elements 44 may be presented in separate embodiments or in combination with each other in one or more embodiments.

[0072] In one embodiment, the above-described thermoforming method may use an assembly as described above for imparting a predetermined curvature to a film to be applied to an optical article, the film being placed below the mask so as to be centered relative to the mask. Hot air may flow from a hot air inlet into a thermoforming chamber at a controlled pressure and out of the thermoforming chamber at a predetermined temperature by passing through a hot air flow conditioning mask, thereby generating a uniform heat distribution within the film until a predetermined target curvature is obtained.

[0073] While representative systems and methods have been described in detail herein, those skilled in the art will recognize that various replacements and modifications may be made without departing from the scope as described and defined in the appended claims.

Claims

1. A thermoforming machine adapted for use in a process for laminating a functional multilayer film on an optical article by using increased pressure and temperature, the thermoforming machine comprising a thermoforming chamber having at least one hot air inlet through which hot air flows into the thermoforming chamber at a controlled pressure, wherein: A hot air flow distribution regulator is arranged in the thermoforming chamber, and the hot air flow distribution regulator includes a hot air flow regulation mask, which receives the hot air flow and has a plurality of flow restriction elements that provide different air flow restrictions to control the distribution of the hot air flow in the thermoforming chamber. The hot air inlet cooperates with the hot air flow distribution regulator so that the hot air flows out of the thermoforming chamber at a predetermined temperature.

2. The thermoforming machine according to claim 1, wherein: The plurality of flow restricting elements are distributed in a predetermined manner from the periphery to the center of the mask, and a first flow restricting element among the flow restricting elements restricts air flow less than a second flow restricting element among the flow restricting elements.

3. The thermoforming machine according to claim 2, wherein: The first of the flow restricting elements is closer to a center of the mask than the second of the flow restricting elements.

4. The thermoforming machine according to claim 2, wherein: The second one of the flow restricting elements is closer to the center of the mask than the first one of the flow restricting elements.

5. Thermoforming machine according to claim 2, 3 or 4, wherein: The plurality of flow restricting elements are distributed over a center of the mask and a predetermined number of concentric shapes, the center of the concentric shapes being the center of the mask.

6. The thermoforming machine according to claim 5, wherein: The concentric shape is circular.

7. The thermoforming machine according to claim 5, wherein: The flow restricting elements located on a given one of the concentric shapes have the same size.

8. The thermoforming machine according to claim 5, wherein: The flow restricting elements located on a given one of the concentric shapes are equidistant from one another.

9. The thermoforming machine according to claim 8, wherein: The number of the concentric shapes is five, and the value of the angular sector between two adjacent flow restriction elements on the same shape is between 9° and 60°.

10. Thermoforming machine according to any one of claims 1 to 4, wherein: The flow restriction element is a circular opening.

11. The thermoforming machine according to claim 10, wherein: The diameter of the opening is between 1 mm and 10 mm.

12. Thermoforming machine according to any one of claims 1 to 4, wherein: The adjuster has a curved surface.

13. A thermoforming method using a thermoforming machine according to any one of claims 1 to 12, for imparting a predetermined curvature to a film to be applied to an optical article, said film being placed under said mask so as to be centered relative to said mask, wherein: Hot air flows from the hot air inlet into the thermoforming chamber at a controlled pressure and flows out of the thermoforming chamber at a predetermined temperature by passing through the hot air flow conditioning mask, thereby generating a uniform heat distribution within the film until the predetermined target curvature is obtained.

14. The thermoforming method according to claim 13, wherein: The temperature is between 100°C and 140°C.

15. The thermoforming method according to claim 14, wherein: The temperature was 120°C.

16. The thermoforming method according to claim 13 or 14, wherein: The pressure is between 0.2 bar and 8 bar.

17. An optical article comprising a front face and a back face, wherein: At least one of the front and rear faces is coated with a film thermoformed by carrying out the thermoforming method according to claim 13 , 14 , 15 or 16 .

18. A component comprising a thermoforming machine and a film and / or a film patch and / or an active film and / or an adhesive to be thermoformed by the thermoforming machine, the thermoforming machine being suitable for use in a process of laminating a functional multilayer film on an optical article by using increased pressure and temperature, the thermoforming machine comprising a thermoforming chamber having at least one hot air inlet through which hot air flows into the thermoforming chamber at a controlled pressure, and a hot air flow distribution regulator being arranged in the thermoforming chamber, and the hot air flow distribution regulator comprising a hot air flow regulation mask, the hot air flow regulation mask receiving the hot air flow and having a plurality of flow restriction elements providing different air flow restrictions to control the distribution of the hot air flow in the thermoforming chamber, wherein The hot air inlet cooperates with the hot air flow distribution regulator to enable the hot air to flow out of the thermoforming chamber at a predetermined temperature.

19. The assembly of claim 18, wherein: The membrane and / or membrane patch and / or active membrane and / or adhesive has a non-circular predetermined shape, and the plurality of flow restriction elements have the same geometric shape as the predetermined shape of the membrane and / or membrane patch and / or active membrane and / or adhesive.

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