EP4633916A1

EP4633916A1 - Apparatus and methods for forming curved films

Info

Publication number: EP4633916A1
Application number: EP23901865.8A
Authority: EP
Inventors: Ryan IRWIN; Shuai LAI; Yifei Li; Guangsen Wang; Jiao LIU
Original assignee: Neverfrost Inc
Current assignee: Neverfrost Inc
Priority date: 2022-12-16
Filing date: 2023-12-18
Publication date: 2025-10-22
Also published as: WO2024124361A1; EP4633916A4

Abstract

An apparatus and methods for forming curved films from flat films are disclosed. The apparatus includes a chamber having an opening and a sliding table moveable into and out of the chamber through the opening. The sliding table includes a mold cavity containing a mold and a cover for forming an airtight seal over the cavity. The apparatus includes a heater for heating the chamber and a vacuum pump for evacuating air from the cavity to pull the film onto the mold. A method for preforming films comprises placing a film into the mold cavity, sealing the cavity, gradually heating the film to a softening temperature; applying vacuum pressure to pull the film onto the mold, cooling the film while maintaining the vacuum pressure, equalizing pressure and unsealing the cavity and trimming the film to a final size before removing the film from the cavity.

Description

APPARATUS AND METHODS FOR FORMING CURVED FILMS

Technical Field

[0001] The embodiments disclosed herein relate to formed/shaped films for adhering to surfaces, and, in particular to an apparatus and methods for vacuum-forming flat films into curved films.

Introduction

[0002] Thin polymeric films have various applications as protective or functional coverings on a surface. For example, tinted film can be applied to a window to reflect sunlight and block radiant heat. As another example, a shock absorbing anti-abrasive film can be applied to a vehicle windshield to protect it from scratches or cracks. Such films are typically provided as a roll of material that is unwound, cut, heat formed and adhered to the surface.

[0003] Several methods of installing thin films to curved surfaces such as vehicle windshields have been described. One method disclosed in U.S. Patent No. 9,023,162, granted May 5, 2015, involves providing a film comprising a pressure-sensitive adhesive layer covered by a release liner. The film is first cut to a size slightly larger than the surface. The release liner is then removed, and the pressure-sensitive adhesive layer is pressed to the surface. A squeegee tool is used to position the film on the surface and remove air trapped between the surface and the film. Heat (e.g., by a heat gun) is also applied to shrink the film to its final size. Excess film is then cut off.

[0004] Another method described in U.S. Patent Publication No. 20200247102, published August 6, 2020, involves providing a flat moldable covering comprising a sacrificial layer and an underlying stack of functional layers. The moldable covering is pressed onto a vehicle windshield and heat and pressure is applied to conform the flat moldable covering to the contours of the windshield. The sacrificial layer acts as a female mold cavity to thermoform the underlying stack of lenses to the shape of the windshield. Then the sacrificial layer is peeled off. [0005] The above-noted methods of installation are time consuming and require specialized training. Thus, it is desirable to provide a formed film that is formed to size and contoured to fit a curved surface.

[0006] Vacuum thermoforming is a manufacturing process whereby male and female molds are used to stamp a material, often polymer, into the shape of the mold. Vacuum pressure is used to pull the material onto one half of the mold and the mold is closed. Heat is then applied to fix the polymer in the molded shape. While this stamping method is suitable for conventional plastics, polymer films are far thinner and may be damaged by conventional thermoforming techniques.

[0007] A further challenge is that non-uniform polymer films comprise various layers and deform in a non-uniform manner when heated. For example, some non- uniform films will stretch in one direction and shrink in another direction when heated. Additionally, some layers may expand when heated while another layer may shrink when heated.

[0008] Accordingly, there is a need for new methods and apparatus for forming curved films.

Summary

[0009] An apparatus and methods for forming curved films from flat films is described.

[0010] According to some embodiments, there is an apparatus for forming curved films. The apparatus includes a forming chamber having an opening and a sliding table that is moveable into and out of the chamber through the opening.

[0011] The sliding table includes a cavity containing a mold for placing an unformed film thereon. The sliding table further includes a cover for forming an airtight seal over the cavity. According to some embodiments, the bottom of the cover may include a silicone membrane mounted on a jacking frame for pressing the film onto the mold when the cover is closed. The jacking frame may include a top pane and a bottom pane configured to clamp the film therebetween to stretch the film under tension. [0012] The chamber further includes a heater for heating the chamber. The heater may be configured to direct heat to specific areas of the chamber, the mold and/or the film. The apparatus further includes a vacuum pump for evacuating air from the cavity, when the cover is closed, to pull the film onto the mold.

[0013] According to other embodiments, there is a method for forming curved films. The method comprises aligning an unformed film with a mold in a forming chamber, such that a natural direction of the film is aligned parallel to a region of greatest curvature on the mold; gradually heating the unformed film to a transitory state between 160-200 degrees Celsius; conforming the unformed film to the mold to form a curved film; and extracting the curved film from the mold.

[0014] Aligning the unformed film with the mold may further comprise stretching the unformed film under tension; forming an airtight seal around the unformed film and the mold and/or orienting a functional layer of the unformed film to face away from the mold.

[0015] Gradually heating the unformed film to a transitory state may comprise gradually heating the mold; and/or gradually heating the forming chamber. Heat may be applied differentially to one or more sections of the unformed film to achieve more or less curvature. The forming chamber and/or the mold may be preheated to a temperature above room temperature prior to placing the film into the chamber.

[0016] Extracting the curved film from the mold may comprise cooling the curved film to room temperature; equalizing the vacuum pressure to atmospheric pressure; trimming the curved film to a final size; and removing the curved film from the mold.

[0017] The method may further comprise providing the unformed film as a roll of material and cutting the unformed film to an approximate final size. The method may further comprise storing the curved film by stacking the curved film, rolling the curved film or wrapping the curved film on a curved spool.

[0018] The method may further comprise scanning a curved surface to create a template for the mold; forming the mold using the template; and performing a curvature check on the mold to ensure the mold accurately models the curved surface. [0019] Other aspects and features will become apparent, to those ordinarily skilled in the art, upon review of the following description of some exemplary embodiments.

Brief Description of the Drawings

[0020] The drawings included herewith are for illustrating various examples of articles, methods, and apparatuses of the present specification. The drawings are not drawn to scale and are for illustration purposes only. In the drawings:

[0021] FIG. 1 is a perspective view of an apparatus for forming curved films, according to an embodiment;

[0022] FIG. 2A is a side view diagram of an apparatus for forming curved films, according to another embodiment;

[0023] FIG. 2B is front view of the apparatus shown in FIG. 2A;

[0024] FIG. 20 is a top view of the apparatus shown in FIG. 2A;

[0025] FIG. 3 is a flow chart of a method for forming curved films;

[0026] FIG. 4 is a scanner device arrangement, according to an embodiment;

[0027] FIG. 5 is a surface scan of a windshield, according to an embodiment;

[0028] FIG. 6 is a mold created from the surface scan shown in FIG. 5;

[0029] FIG. 7 is a heat map showing differences in curvature of a surface and a mold, according to an embodiment;

[0030] FIG. 8A is a perspective view of a mold, according to an embodiment;

[0031] FIG. 8B is a side view of the mold shown in FIG. 8A;

[0032] FIG. 9 is a diagram showing alignment of a film with a mold, according to an embodiment;

[0033] FIGS. 10A and 10B are diagrams showing alignment of a film with a symmetric mold, according to an embodiment; and

[0034] FIG. 10C is a diagram showing alignment of a film with an asymmetric mold, according to an embodiment. Detailed Description

[0035] Various apparatuses or processes will be described below to provide an example of each claimed embodiment. No embodiment described below limits any claimed embodiment and any claimed embodiment may cover processes or apparatuses that differ from those described below. The claimed embodiments are not limited to apparatuses or processes having all of the features of any one apparatus or process described below or to features common to multiple or all of the apparatuses described below.

[0036] Reference herein to “film(s)” means thin (< 1 mm) polymeric films having one or more layers. At least one layer is a functional layer providing some material property to the film. For example, the functional layer may be a shock absorbing layer, an abrasion protecting layer, or a tint layer. Other functional layers may also be present. The film may have an adhesive layer for adhering the film to a surface or substrate. The film may have a protective layer for protecting the functional and/or adhesive layers of the film during manufacture, installation and/or during use of the film from environmental factors such as abrasions and UV radiation.

[0037] Reference herein to “unformed film(s)” means a thin polymeric film comprising one or more layers, that is substantially flexible and remains flat when placed on a flat surface.

[0038] Reference herein to “curved film(s)” means a thin polymeric film comprising one or more layers that is sized and contoured to match the size and curvature of a surface, such as a vehicle windshield, and is semi-rigid and substantially retains its contours when placed on a flat surface.

[0039] Referring to FIG. 1 , shown therein is an apparatus 100 for forming curved films. The apparatus 100 includes an insulated forming chamber 102 and a sliding table 104. The apparatus 100 includes rails 106 on which the sliding table 104 is mounted. The rails 106 span the length of the forming chamber 102 and extend through an opening 108 of the forming chamber 102 to allow the sliding table 104 to slide into, and out of, the forming chamber 102 through the opening 108. According to some embodiments, the sliding table 104 includes an end plate 120 that covers the opening 108 when the sliding table 104 is moved into the forming chamber 102.

[0040] The sliding table 104 may be manually moved along the rails 106 or may be driven by a motor or actuator.

[0041] The sliding table 104 includes a mold cavity 110 for containing a mold (not shown). The mold is a formed 3D shape preferably constructed of CNC-cut aluminum, CNC-cut Steel, Glass, Fiberglass, Kevlar, Carbon Fibre, or 3D printed plastic. According to other embodiments, the mold may be constructed of other materials that have suitable heat conductance. The mold has a substantially concave or convex shape. Generally, the mold has dimensions and curvature corresponding to the surface or substrate onto which the film will be installed. The mold may have dimensions and curvature corresponding to a vehicle windshield.

[0042] According to other embodiments, the sliding table 104 is omitted and the mold cavity 110 (and the mold) are disposed within the forming chamber 102 at all times. In such embodiments, the apparatus 100 further includes a jacking frame (described below) for loading the unformed film into the forming chamber 102, aligning the unformed film atop the mold, and moving the curved film out of the forming chamber 102 after thermoforming.

[0043] The sliding table 104 includes a cover 112 for covering the mold cavity 110 and forming an airtight seal. The cover 112 may include a membrane, preferably made of silicone, on a bottom surface of the cover 112, that can be used to apply pressure to the film and the mold when the air is evacuated from the cavity 110. Alternatively, the cover 112 absent a membrane can be clamped directly to the film and evacuate the air directly to the cavity under the film. The cover 112 is raised to expose the mold cavity 110 and insert a film between the mold and the cover 112. The sliding table 104 includes pneumatic or hydraulic piston arms 114 for raising and lowering the cover 112. The sliding table 104 may further include clamps 116 for securing the cover 1 12 in a closed position to form an airtight seal around the cavity 110.

[0044] The sliding table 104 may include a jacking frame (not shown) to raise or lower the cover/membrane to provide enough working area to access the cavity 110 and mold therein. The jacking frame includes one or more linear actuators, hydraulic jacks, or the like, to raise/lower the cover/membrane. According to embodiments wherein the mold is within the forming chamber 102 at all times, the jacking frame is configured to move the film into and out of the forming chamber. In these embodiments, the jacking frame includes a top pane and a bottom pane configured to clamp the film therebetween and stretch the unformed film under tension between the panes to prevent damage/kinking to the film as it is loaded into the forming chamber 102.

[0045] The apparatus 100 includes at least one and preferably two vacuum pumps 118. The vacuum pumps 118 are operably connected to the mold cavity 110 to pump air out of (i.e., evacuate) the mold cavity 110. Generally, the vacuum pumps 118 pump air out from the bottom of the mold cavity 110 such that a film placed between the mold and the cover 112 within the mold cavity 110 will be pulled downward onto the mold by the evacuating air. The pumps 118 are capable of generating a vacuum pressure of 0.3 - 1 MPa sufficient to pull the film tightly onto the mold without leaving air pockets between the film and the mold. A stronger vacuum pressure may cause the film to kink, crack, or deform on the mold.

[0046] The forming chamber 102 further includes a heater (not shown) for heating the chamber 102 and the film therein. Preferably, the heater is an infrared heater, however convection heating means may be used. The heater is generally disposed at the top 122 of the forming chamber 102 and directs heat downward onto the film/mold. The heater is capable of heating the forming chamber 102 to at least 200 degrees Celsius. The heater is electrically controlled for gradual and fine temperature adjustments.

[0047] The heater may include a plurality of heating elements configured to direct heat to specific areas within the forming chamber 102 or onto specific parts of the mold/film. For example, the heater may be configured to alternatingly direct heat to the center or the periphery of the mold/film. This may be advantageous for bringing permanent curvature to a non-uniform film (e.g., a film comprising multiple layers) by heating and deforming specific regions of the non-uniform film. [0048] According to some embodiments, a second heater may be disposed within the mold itself to heat the film from below. The second heater may comprise silicone heating pads or a heat exchanger system using a working fluid (e.g., water).

[0049] According to some embodiments, a silicone heating pad is disposed within the cover 112 membrane to heat the film from above.

[0050] The forming chamber 102 may further include one or more fans for circulating air through the forming chamber 102 to maintain a uniform temperature therein. A fan may also expel hot air from the chamber 102 for cooling the chamber after use.

[0051] A further fan may be disposed on an exterior of the forming chamber 102 to direct air onto the sliding table 104 to cool the film and mold after the table 104 is moved out of the forming chamber 102.

[0052] The apparatus 100 includes a spool holder 124 for holding roll of unformed film (not shown) for feeding into the mold cavity 110. The apparatus 100 may include a cutting blade (not shown) positioned adjacent to the spool holder 124 to cut a length of unformed film into an approximate final size before it is fed into the mold cavity 110.

[0053] The apparatus 100 includes adjustable legs 126 for keeping the apparatus 100 level.

[0054] To load an unformed film for forming, the sliding table 104 is moved out of the forming chamber 102 (as shown) and the cover 112 is raised. A mold is positioned into the mold cavity 110. A roll of film is unspooled (i.e., straightened), and a rectangular piece of unformed film is cut to an approximate size of a final curved film. The piece of unformed film is then fed into the mold cavity 110.

[0055] According to embodiments wherein the cover 112 includes a silicone membrane, the unformed film is suspended over the mold cavity 110 containing the mold and the cover 112 is closed. The silicone membrane is pressed atop the unformed film and forms an airtight seal against the mold with the unformed film interposed between the membrane and the mold. According to embodiments wherein the cover 112 does not include a membrane, the unformed film is clamped to the exterior edges of the cover 112 and the cover 112 is closed and secured by the clamps 116 to form an airtight seal.

[0056] The sliding table 104 is moved through the opening 108 into the forming chamber 102 until the end plate 120 covers the opening 108. The film is then formed to a curved shape by the combination of the mold, vacuum pressure and heat as described below. Operation of the apparatus 100 after the sliding table is moved into the forming chamber 102 is generally automated and does not require direct user intervention. The apparatus 100 may be connected to a control device (e.g., a computer) for setting operating parameters and inputting commands for controlling the heat and vacuum pressure in the forming chamber 102. To unload the curved film, the sliding table 104 is moved out of the forming chamber 102 and the cover 112 is raised.

[0057] Referring to FIGS. 2A-2C, shown therein are diagrams of an apparatus 200 for forming curved films, according to an embodiment. The apparatus 200 is substantially similar to the apparatus 100 in FIG. 1 and includes a forming chamber 202, a sliding table 204 mounted on rails 206, a cover 212 and a mold 211 within a mold cavity 210. FIGS. 2A-2C show the sliding table 204 positioned within the forming chamber 202. Certain parts of the apparatus 200 have been omitted and the forming chamber 202 is shown transparent for ease of illustration.

[0058] The apparatus 200 may include a hoist 230 for loading and unloading the mold 211 into the mold cavity 210. The apparatus 200 may include a membrane 219 on a bottom side of the cover 212 for pressing the film onto the mold 211 when the cover 212 is closed.

[0059] Referring to FIG. 3, shown therein is a flow chart of a method 300 for forming curved films. The method 300 may be performed using the apparatus 100 or the apparatus 200. In the description of the method 300, the elements from FIGS. 1 and 2 are indicated in parenthesis for reference.

[0060] At 302 a surface that a curved film is to be adhered to is scanned to create a template for a mold. The surface is a curved surface, for example, a vehicle windshield. According to various embodiments, the surface can be “scanned” by contacting or contactless means. Contact scanning is performed using a mechanical probe or by forming a casting of the surface using known techniques. According to another embodiment, a CAD file or other design file of the surface is provided by a manufacturer as the template for the mold.

[0061] According to preferred embodiments, contactless scanning using a scanner device is used to scan the surface to create the template for the mold. The scanner device uses LIDAR or a 3D camera to scan the surface. The scanner device may be a tablet, smartphone, or the like, installed with an application configured for LIDAR or 3D scanning (e.g., an iPad installed with a 3D scanning application). Preferably, the scanner device provides a scanning resolution of at least 0.5 mm and outputs the scan of the surface as a CAD file or other design file type.

[0062] As shown in FIG. 4, the scanner device 402 is positioned at a fixed distance from the surface 404, for example on a tripod 406, such that the entirety of the surface 404 can be viewed by the cameras/sensors of the scanner device 402. For optimal scan results, the scan should be performed indoors, away from sunlight. The surface 404 to be scanned should also be free of dirt and moisture. Transparent surfaces such as a windshield 404 must be covered with an opaque covering/fabric 408 prior to scanning. Wrinkles in the covering/fabric 408 must be minimized when draping over the surface 404 for optimal scan results. Alternatively, the transparent surface 404 can be sprayed with an opaque coating (e.g., Magnaflux White Developer) prior to scanning.

[0063] FIG. 5 shows an exemplary surface scan 410 of a windshield generated by a scanning device. It should be noted that the surface that is scanned may be symmetric or asymmetric. The exemplary surface scan shown in FIG. 5 is a scan of an asymmetric windshield from a Telsa® Model 3. The surface may also be curved in more than one direction e.g., having longitudinal curvature (left to right) and transverse curvature (top to bottom).

[0064] Referring back to FIG. 3, at 304, a mold (211 ) of the surface is created from the surface scan template. The mold may be formed of any suitable material having the requisite heat conductance. Molds formed of metal (e.g., steel, aluminum) are typically created by CNC machine cutting. Molds formed of composite materials (e.g., fiber glass) may be machined, cast or 3D printed. Generally, a different metal or composite mold must be made for each surface a film is to be adhered to.

[0065] FIG. 6 is a diagram of a mold 416 created from the surface scan shown in FIG. 5. The mold 416 may include guide/alignment markings 418 for aligning an unformed film atop the mold 416.

[0066] According to some embodiments, the mold is a sandwich mold comprising a positive mold and a negative mold. In these embodiments, the unformed film is stamped between the positive and negative molds in a manner similar to stamping metal.

[0067] The mold must accurately model the curvature of the surface to be useful in creating curved films. After the mold is formed, the curvature of the mold is compared to the curvature of the surface to ensure the mold is an accurate reproduction of the surface. The curvature check can be performed in several ways. One method is to make a buck frame aligned to the curvature of the surface. The buck frame is then placed atop the mold and spaces or gaps between the buck frame and the mold are indicative of differences in curvature between the surface and the mold.

[0068] A preferred method for the curvature check is to scan the mold and compare the scan of the mold to the scan of the surface created at step 302. Differences in the mold scan data and the surface scan data are indicative of differences in the curvature of the mold and the surface. FIG. 7 shows a heat map 420 comparison of differences in curvature of the surface and the mold. Z coordinates corresponding to at least nine (9) XY positions 422a-422j in the surface scan data and the mold scan data are compared. The positions 442a-442i should cover the top, bottom, middle and sizes of the surface and the mold. It is preferable to avoid using scan data from XY positions that are at the perimeter of the surface and the mold.

[0069] The Z-coordinate of the mold scan data is subtracted from the Z-coordinate of the surface scan data at each XY position to obtain a difference in curvature (Az) at that position. A positive Az indicates that the mold has lower curvature than the surface at that position (thus the mold must be raised at that position to match the surface); a negative Az indicates the mold has higher curvature than the surface at that position (thus the mold must be lowered at that position to match the surface). Generally, an average Az of ±3 mm is an acceptable tolerance for the mold.

[0070] An “overcurved” mold is preferable to an “undercurved” mold. It should be noted that whether the mold is overcurved or undercurved at a given position depends on the particular position on the mold. For example, a positive Az at the position 422j in the center of the mold would err toward undercurved; whereas a positive Az at a position 422d in a corner of the mold would err toward overcurved.

[0071] According to some embodiments, as shown in FIGS. 8A and 8B, the mold 430 includes a plurality of openings or channels (for ease of illustration only one channel 432 is referenced) passing between a top 434 to a bottom 436 of the mold 432. According to some embodiments, the mold 430 includes a base 438. The base 438 is generally flat, without any contours. Openings 450 may also be disposed in the base 438.

[0072] When vacuum suction is applied to the bottom 436 of the mold 430 air is drawn from the top 434 of the mold 430 through the channels 432 and openings 450. This aids in pulling the unformed film tightly onto the mold 430 without air pockets forming between the film and the mold 430. The plurality of channels 432 are dispersed evenly across the mold 430. The openings of the channels are less than 1 inch in diameter) to prevent imprinting onto the film when vacuum pressure is applied.

[0073] Referring back to FIG. 3, steps 302 and 304 are typically performed days or weeks in advance of the rest of the method 300. Molds that are created can be stored for later use.

[0074] At 306, an unformed film is aligned with the mold (211 ). The unformed film may be provided as an unformed film cut to an approximate final size that is slightly larger than the mold (211 ). The unformed film may be provided as a spooled roll of material held on the spool holder (124) that is unspooled and cut to the approximate final size of a curved film.

[0075] The unformed film is moved into the mold cavity (110) containing the mold (211 ) and the cavity (110) is sealed. According to some embodiments, the sliding table (104) containing the mold (211 ) is moved outside the forming chamber (102) and the cover (112) is raised exposing the mold (211 ). The cut unformed film is then placed atop the mold (211 ). The mold cavity (110) is sealed with the airtight cover (112) and secured with clamps (116). The sliding table (104) is slid along the rails (106) into the forming chamber (102).

[0076] According to embodiments wherein the mold is positioned within the forming chamber (102) at all times, the unformed film is mounted on a jacking frame which moves the unformed film into the forming chamber (102), aligns the film atop the mold (211 ) and seals the mold cavity (e.g., the jacking frame lowers the film to form an airtight seal around the mold cavity).

[0077] As shown in FIG. 9, the unformed film 440 is aligned with the mold 442 such that a natural direction of the film 440 is aligned to the region(s) of greatest curvature of the mold 442. The natural direction of the film refers to the directionality of the polymer fibers in the unformed film 440 that are the result of how the unformed film 440 is stretched and pulled during manufacture; the film 440 tends to stretch/shrink more in the natural direction than a direction perpendicular to the natural direction. Typically, the top 444 and/or the bottom 446 of a windshield mold 442 has the greatest curvature. Accordingly, the unformed film 440 is fed into the apparatus such that the natural direction of the film 440 is aligned parallel to the top 444 and bottom 446 of the mold 442.

[0078] Depending on the symmetry of the surface/mold, the unformed film may be aligned such that a functional layer of the film (e.g., a hard coat layer for abrasion resistance) is facing toward the mold or away from the mold. As shown in FIGS. 10A-10B, with a symmetric mold 450, the film 454 can be aligned with mold 450 such that the functional layer 456 is facing toward (FIG. 10A) or away (FIG. 10B) from the mold 450 since the film 454 will conform to the mold curvature in either direction. As shown in FIG. 10C, with an asymmetric mold 452, the film 454 is aligned with the mold 452 such that the functional layer 456 facing away from the mold 452.

[0079] Referring back to FIG. 3, at 308, the chamber (102) is gradually heated to a temperature of 160-200 degrees Celsius to heat and soften the unformed film to a transitory state where it is easily conformed to the shape of the mold (211 ). Heat is applied gradually to prevent singeing or burning of the film. Generally, a higher temperature is used to bend the unformed film to a more aggressive curvature. The mold (211 ) may also be gradually heated. As noted above, different sections of the film/mold (211 ) may be differentially heated to aid in bending those sections, as required.

[0080] The chamber (102) and/or the mold (211 ) may be preheated to above room temperature prior to moving the sliding table (104) into the chamber (102). According to embodiments wherein the mold (211 ) is within the forming chamber at all times, the mold and/or the chamber may be preheated to above room temperature prior to moving the unformed film into the chamber (102).

[0081] At 310, the unformed film is conformed to the mold (211 ) to create a curved film. Preferably, vacuum pressure is used to pull the unformed film onto the mold (211 ). The unformed film is pulled onto the mold by the vacuum pumps (118) generating a vacuum pressure between 0.3-1 MPa in the mold cavity (110). This range of pressure is sufficient to ensure the unformed film is properly seated atop the mold (211 ) without tearing, wrinkling, creasing, or kinking the unformed film. It is preferable to gradually increase the vacuum pressure after the appropriate softening temperature is reached to ensure the film is pulled tight over the mold without tearing, wrinkling, creasing or kinking. The jacking frame may also be used to stretch the film under tension as it is pulled onto the mold to prevent wrinkling, creasing or kinking.

[0082] According to some embodiments, the cover membrane and the heating pad therein, apply a downward force on the film, by gravity, to push the film onto the mold to create the curved film by thermoforming using heating only, without vacuum.

[0083] According to an embodiment wherein the mold is a sandwich mold, the top mold and the bottom mold are brought together to stamp the unformed film therebetween to create the formed film by thermoforming using heating only, without vacuum.

[0084] At 312, the curved film is extracted from the forming mold (211 ). The sliding table (104) is moved out of the forming chamber (102), along the rails (106) and allowed to cool to room temperature. Cooling of the film is important to ensure conformity of the film to its final shape. It should be noted that the vacuum pressure in the cavity (110) is maintained until the film is cooled down sufficiently to ensure the film does not further deform/conform after it is removed from the mold, which may occur if the curved film is still warm/soft.Once the film is cooled, the pressure in the cavity (110) is then equalized to atmospheric pressure and the cover (112) is removed unsealing the cavity (110) and the curved film is removed from the cavity.

[0085] According to embodiments wherein the mold is within the forming chamber at all times, the forming chamber is cooled to room temperature by expelling hot air from the chamber. Pressure in the mold cavity is then equalized and the jacking frame is raised to lift the curved film off the mold and out of the forming chamber.

[0086] the cooled curved film is trimmed to a final size matching the exact dimensions of the mold. This cutting is generally done manually by a user with a cutting tool (e.g., a knife).

[0087] At 318, the curved film may placed in storage or rolled for transport. The curved film is semi-rigid and substantially retains its curvature when placed on a flat surface or when rolled. Thus, the curved films may be stacked one on top of the other for storage or rolled (individually or stacked and rolled) for storage. The curved films may also be stacked and stored on the mold used to create the fcurved films.

[0088] Tightly winding the curved film onto a flat roll for storage for extended periods of time (> 1 month) may cause the curved film to deform and lose its curvature, at least partially. Accordingly, according to some embodiments the curved films are wrapped onto a curved roll/spool (similar to an elongated vase) to mitigate deformation during long term storage.

[0089] While the above description provides examples of one or more apparatus, methods, or systems, it will be appreciated that other apparatus, methods, or systems may be within the scope of the claims as interpreted by one of skill in the art.

Claims

Claims:

1 . A method for forming curved films, comprising: aligning an unformed film with a mold in a forming chamber, such that a natural direction of the film is aligned parallel to a region of greatest curvature on the mold; gradually heating the unformed film to a transitory state between 160-200 degrees Celsius; conforming the unformed film to the mold to form a curved film; and extracting the curved film from the mold.

2. The method of claim 1 , wherein aligning the unformed film with the mold further comprises: stretching the unformed film under tension;

3. The method of claim 1 , wherein aligning the unformed film with the mold further comprises: forming an airtight seal around the unformed film and the mold.

4. The method of claim 1 , wherein the mold is asymmetric and aligning the unformed film with the mold further comprises: orienting a functional layer of the unformed film to face away from the mold.

5. The method of claim 1 , wherein gradually heating the unformed film comprises: gradually heating the mold; and/or gradually heating the forming chamber. The method of claim 1 , wherein gradually heating the unformed film comprises: differentially heating one or more sections of the unformed film. The method of claim 1 , further comprising: preheating the forming chamber and/or the mold to a temperature above room temperature. The method of claim 1 , wherein conforming the unformed film to the mold comprises: gradually applying a vacuum pressure between 0.3-1 MPa to pull the unformed film tightly onto the mold. The method of claim 1 , wherein extracting the curved film from the mold comprises: cooling the curved film to room temperature; trimming the curved film to a final size; and removing the curved film from the mold. The method of claim 8, wherein extracting the curved film from the mold comprises: cooling the curved film to room temperature; equalizing the vacuum pressure to atmospheric pressure; trimming the curved film to a final size; and removing the curved film from the mold. The method of claim 1 , further comprising: storing the curved film by one of: stacking the curved film, rolling the curved film and wrapping the curved film on a curved spool. The method of claim 1 , further comprising: scanning a curved surface to create a template for the mold; forming the mold using the template; and performing a curvature check on the mold. The method of claim 12, wherein the curvature check comprises: scanning the mold to generate a scan of the mold; calculating an average difference in curvature from at least 9 positions in the scan of the mold and the template. A curved film manufactured using the method of any one of claims 1 to 14. An apparatus for forming curved films, comprising: a forming chamber comprising; an opening a heater for heating the chamber; a sliding table moveable into and out of the chamber through the opening, the sliding table comprising: a cavity containing a mold for placing a film thereon; a cover for forming an airtight sealing over the cavity and the mold; and a vacuum pump operably connected to the cavity for evacuating air from the cavity to pull the film tightly onto the mold. The apparatus of claim 15, wherein the cover comprises: a silicone membrane mounted on a jacking frame; and a heating pad disposed within the silicone membrane. The apparatus of claim 16, wherein the jacking frame further comprises: a top pane and a bottom pane configured to clamp the film therebetween to stretch the film under tension. The apparatus of claim 15, wherein the mold comprises a heating pad or a heat exchanger. The apparatus of claim 15, wherein the mold comprises a plurality of channels passing between a top and a bottom of the mold, wherein the vacuum pump is configured to apply vacuum pressure to the bottom of the mold. The apparatus of claim 15, wherein the heater is an infrared heater having a plurality of heating elements, each heating element configured for heating an area of the forming chamber or the mold.

21 . The apparatus of claim 15, wherein the heater is a convection heater.