Method and apparatus for shaping a sheet of glass

Abstract

Methods of shaping a glass sheet are described comprising the steps: (i) heating the glass sheet to a temperature for shaping; (ii) supporting the glass sheet on a first bending tool; (iii) pressing the glass sheet between the first and a second bending tool; and thereafter (iv) pressing the glass sheet between a third bending tool and the first or second bending tool. Apparatus for carrying out such methods is also described comprising first and second bending tools for pressing a heat softened glass sheet therebetween; retaining means for retaining the heat softened glass sheet on the first bending tool; and control means for aligning a third bending tool with the heat softened glass sheet retained on the first bending tool and for positioning the third bending tool relative to the first bending tool to press the heat softened glass sheet between the first and third bending tools.

Description

[0001] METHOD AND APPARATUS FOR SHAPING A SHEET OF GLASS

[0002] The present invention relates to a method of shaping a sheet of glass and to an apparatus for shaping a sheet of glass.

[0003] It is well known in the art to bend or shape a heat softened flat sheet of glass between a pair of bending tools having complementary shaping surfaces. Typically a heat softened sheet of glass is supported on a ring mould and is bent between the ring mould and an upper unitary full surface mould.

[0004] Glass bending processes and associated apparatus are described in US2019 / 0127260A1, US2020 / 0156985A1, WO2015 / 064978A1 and JPH03164440A.

[0005] A press bending station is described in W02005 / 033026A1 that includes an annular mould and a full-face mould. Holes, selectively connected to a negative pressure source, are placed in portions of the full-face mould that are determined by the configuration of the annular mould when the annular mould comes into contact with a heated sheet of glass during the press bending process. The heated sheet of glass is drawn by negative pressure through the holes towards the full -face mould and thus acquires its shape. The full-face mould may be covered by at least one fine mesh cloth i.e. woven stainless steel.

[0006] Glass sheet bending processes including more than one bending step are also known, such processes often being used to bend a sheet of glass to a more complex shape. For instance, it is sometimes not possible to bend a sheet of glass to a desired shape using a unitary press bending member.

[0007] It is described in US5, 122, 177 how the edge of a sheet of glass to be bent is supported on a shaping frame, the sheet of glass being first clamped at the peripheral edges thereof, following which the central region of the sheet of glass is pressed to the desired curvature.

[0008] US5, 108,480 discloses a bend-shaping press mold comprising a pair of pressing dies for bending a glass plate into a shape having a convex surface and a concave surface in a plane by pressing the glass plate with the pair of pressing dies, wherein each of the pressing dies has at its part a convex surface portion to shape the glass plate by pressing it from each side which is finally shaped to have a concave surface portion, and the convex surface portion of one of the pressing dies is not substantially in contact with the glass plate in pressing operations when the convex surface portion of the other die is in contact with the glass plate.

[0009] For some products, the bending processes described above are not able to shape a sheet of glass with sufficient precision to produce surface details in the final bent sheet of glass. The present invention aims to at least partially provide a solution to this problem.Accordingly, from a first aspect the present invention provides a method of shaping a sheet of glass, the sheet of glass having a first major surface and a second opposing major surface, the method comprising the steps: (i) heating the sheet of glass to a temperature suitable for shaping; (ii) depositing the sheet of glass on a first bending tool for supporting the sheet of glass thereon; (iii) pressing the sheet of glass between the first bending tool and a second bending tool; and thereafter (iv) pressing the sheet of glass between a third bending tool and the first bending tool or the second bending tool.

[0010] During step (ii) preferably the first major surface of the sheet of glass faces a shaping surface of the first bending tool.

[0011] Preferably the first bending tool has at least one shaping rail for supporting the sheet of glass thereon during step (ii).

[0012] Preferably the first bending tool has two spaced apart shaping rails for supporting the sheet of glass thereon during step (ii)

[0013] Preferably the first or second bending tool is configured as a ring.

[0014] Preferably the first or second bending tool is configured as a full surface bending tool.

[0015] Preferably the first bending tool is configured as a full surface bending tool and the second bending tool is configured as a ring.

[0016] Preferably the second bending tool is configured as a full surface bending tool and the first bending tool is configured as a ring.

[0017] Preferably the first bending tool has a convex shaping surface, and the second bending tool has a complementary concave shaping surface.

[0018] Preferably the first bending tool has a concave shaping surface, and the second bending tool has a complementary convex shaping surface.

[0019] Preferably the third bending tool is a full surface bending tool.

[0020] Preferably the third bending tool has a shaping surface complementary with at least a portion of a bending surface of the first or second bending tool.

[0021] Preferably the third bending tool has a shaping surface for introducing at least a first detail to the sheet of glass shaped following step (ii) such that during step (iv) the first detail produces at least a first region of the sheet of glass having a radius of curvature preferably less than 1000 mm, more preferably less than R mm, wherein R is 900, or 800, or 700, or 600, or 500, or 400, or 300, or 200, or 100, or 90, or 80, or 70, or 60, or 50, or 40, or 30, or 20, or 10.Preferably at least one of the first bending tool, the second bending tool and the third bending tool is a heated bending tool and preferably comprises at least one electrical resistance heating element. By providing a heated bending tool the temperature thereof may be maintained and / or adjusted at / to a desired level.

[0022] Preferably during step (iii) a vacuum is drawn through at least one passage formed in the first bending tool and / or second bending tool.

[0023] Preferably first bending tool has an outer periphery and at least a portion of the outer periphery of the first bending tool is alignable with at least a portion of an outer periphery of the third bending tool.

[0024] Preferably the first bending tool has a shaping surface complementary with a shaping surface of the second bending tool.

[0025] Preferably the sheet of glass has a thickness of at most 25 mm, more preferably at most 10 mm, even more preferably at most 6 mm.

[0026] Preferably the sheet of glass has a thickness of at least 0.3 mm, more preferably at least 0.5 mm, even more preferably at least 1 mm.

[0027] Preferably the sheet of glass has a soda-lime-silica glass composition.

[0028] A typical soda-lime-silica glass composition is (by weight), SiC>269 - 74 %; AI2O3 0 - 3 %; Na2O 10 - 16 %; K2O 0 - 5 %; MgO 0 - 6 %; CaO 5 - 14 %; SO3 0 - 2 %; Fe2O30.005 - 2 %. The glass may also contain other additives, for example, refining aids, which would normally be present in an amount of up to 2 %. The soda-lime-silica glass composition may contain other colouring agents such as CO3O4, NiO and Se to impart to the glass a desired colour when viewed in transmitted light. The transmitted glass colour may be measured in terms of a recognised standard such as BS EN410.

[0029] During step (i) the sheet of glass is heated to temperature where the sheet of glass has a suitably low viscosity to be able to be shaped by press bending, in particular by press bending between a pair of complimentary shaping members. Preferably during step (i) the sheet of glass is heated uniformly, although selected regions of the sheet of glass may be heated to different temperatures.

[0030] Preferably during step (i) the sheet of glass is heated to a temperature between 580 °C and 800 °C, more preferably between 600 °C and 780 °C, even more preferably between 650 °C and 750 °C.

[0031] Preferably the sheet of glass is heated before depositing the sheet of glass on the first bending tool. However the sheet of glass may be deposited on the first bending tool and then heated. The sheet of glass may be heated to a first temperature before being deposited on the first bending tool, and subsequently heated whilst supported on the first bending tool to a second temperature.

[0032] Preferably the sheet of glass is one sheet in a stack of glass sheets, in particular a nested pair.Preferably following step (iv), the shaped sheet of glass is thermally toughened by quenching the shaped sheet of glass with jets of cooling fluid directed towards at least one of the major surfaces of the shaped sheet of glass.

[0033] Preferably following step (iv) the shaped sheet of glass is laminated to another sheet of glass using an interlayer structure comprising at least one sheet of interlayer material. Suitable interlayer material includes polyvinyl butyral, ethylene vinyl acetate copolymer, polyurethane, polycarbonate, polyvinyl chloride, or a copolymer of ethylene and methacrylic acid.

[0034] In embodiments where the third bending tool is a full surface bending tool, preferably the third bending tool has a shaping surface configured to face at least 50% of the first or second major surface of the sheet of glass.

[0035] Preferably the third bending tool is a full surface bending tool having a shaping surface configured to face at least 55%, or at least 65%, or at least 70%, or at least 75%, or at least 80%, or at least 85%, or at least 90%, or at least 95% of the first or second major surface of the sheet of glass.

[0036] In embodiments where the third bending tool is a full surface bending tool, the third bending tool has a shaping surface configured for shaping a first region of the sheet of glass, and preferably the shaping surface of the third bending tool is coextensive with the first region of the sheet of glass.

[0037] Each of the first and second major surfaces of the sheet of glass has a respective area.

[0038] Preferably the first region of the sheet of glass is at least 50% of the area of the first or second major surface of the sheet of glass.

[0039] In some embodiments, during step (iv) the sheet of glass is pressed between the third bending tool and the first bending tool.

[0040] Preferably during step (iv) a vacuum is drawn through at least one passage formed in the first bending tool.

[0041] Preferably the first bending tool remains static, and the third bending tool is moved towards the first bending tool to press the sheet of glass therebetween.

[0042] Preferably the third bending tool remains static, and the first bending tool is moved towards the third bending tool to press the sheet of glass therebetween.

[0043] Preferably the first and third bending tools are both moved toward each other to press the sheet of glass therebetween.

[0044] In some embodiments, during step (iv) the sheet of glass is pressed between the third bending tool and the second bending tool.Preferably during step (iv) a vacuum is drawn through at least one passage formed in the second bending tool.

[0045] Preferably the second bending tool remains static, and the third bending tool is moved towards the second bending tool to press the sheet of glass therebetween.

[0046] Preferably the third bending tool remains static, and the second bending tool is moved towards the third bending tool to press the sheet of glass therebetween.

[0047] Preferably the second and third bending tools are both moved toward each other to press the sheet of glass therebetween.

[0048] In some embodiments during (iii) the sheet of glass is pressed to a first shape having a first radius of curvature, and during step (iv), the sheet of glass is pressed to a second shape, the second shape having at least a first region having a second radius of curvature smaller than the first radius of curvature.

[0049] The region of the sheet of glass having the second radius of curvature is produced by at least a first detail in or on a shaping surface of the third bending tool. It is preferred that the shaping surface of the third bending tool in regions not including the or each detail is generally complementary with a shaping surface of the first bending tool or a shaping surface of the second bending tool.

[0050] Preferably the first radius of curvature is at least 300 mm and / or at most 20,000 mm.

[0051] Preferably the second radius of curvature is less than 300 mm, preferably less than 200 mm, more preferably less than 100mm, even more preferably less than 50mm.

[0052] In some embodiments, after step (iii) and before step (iv) there is a spacing step (iii)’, wherein during the spacing step (iii)’ a spacing of the first bending tool and the second bending tool is increased to remove contact of the sheet of glass with the first bending tool or the second bending tool while keeping the sheet of glass in contact with the other of the first bending tool and the second bending tool such that during step (iv) the sheet of glass is shaped by pressing between the third bending tool and the other of the first bending tool and the second bending tool still in contact with the sheet of glass after the spacing step (iii)’.

[0053] In some embodiments having a spacing step (iii)’, following the step (iii)’ the sheet of glass is kept in contact with the second bending tool by at least one region of low pressure between the sheet of glass and the second bending tool, and wherein the first bending tool is spaced apart from the second bending tool such that the first bending tool is not in contact with the sheet of glass.

[0054] In such embodiments, at the completion of step (iii)’, the sheet of glass is in contact with the second bending tool and not in contact with the first bending tool.

[0055] Preferably the second major surface of the sheet of glass is in contact with a shaping surface of the second bending tool.In some embodiments the second bending tool has at least a first passage extending therethrough and wherein a vacuum source is connectable to the first passage to produce at least a first region of low pressure preferably at a shaping surface of the second bending tool.

[0056] In some embodiments having a spacing step (iii)’ , following step (iii)’ the sheet of glass is kept in contact with the second bending tool by an auxiliary bending tool being pressed against the sheet of glass.

[0057] In such embodiments, at the completion of step (iii)’, the sheet of glass is in contact with both the second bending tool and the auxiliary bending tool and not in contact with the first bending tool.

[0058] Preferably the second major surface of the sheet of glass is in contact with a shaping surface of the second bending tool and the first major surface of the sheet of glass is in contact with the auxiliary bending tool.

[0059] Preferably the auxiliary bending tool has at least one shaping rail for contacting the sheet of glass during step (iii)’.

[0060] Preferably the auxiliary bending tool has two spaced apart shaping rails for contacting the sheet of glass during step (iii)’, preferably wherein the auxiliary bending tool is configured as a ring for contacting the sheet of glass during step (iii)’.

[0061] In some embodiments having a spacing step (iii)’, following step (iii)’ the sheet of glass is kept in contact with the first bending tool and the second bending tool is spaced apart from the first bending tool such that the second bending tool is not in contact with the sheet of glass.

[0062] Preferably the first bending tool is a full surface bending tool.

[0063] Preferably the first bending tool has a convex shaping surface.

[0064] Preferably the second bending tool is a full surface bending tool.

[0065] In some embodiments, during step (iv) the sheet of glass is pressed between the second bending tool and the third bending tool, and the first bending tool is pressed against the third bending tool.

[0066] In such embodiments a pressing force is applied to the third bending tool by the first bending tool, and this helps shape the glass during step (iv).

[0067] Preferably the first bending tool comprises at least a first strengthening member to increase the strength and / or rigidity thereof when the first bending tool is being pressed against the third bending tool. It is preferred that the first bending tool is configured such that the first strengthening member does not contact the sheet of glass during step (ii).Preferably the first bending tool is in direct contact with the third bending tool when the first bending tool is pressed against the third bending tool.

[0068] In a preferred embodiment, during step (iv) the third bending tool is in direct contact with the sheet of glass on a first side of the third bending tool and in direct contact with the first bending tool on a second side of the third bending tool, the second side of the third bending tool being opposite the first side of the third bending tool.

[0069] Preferably the first side of the third bending tool is concave, and the second side of the third bending tool is convex.

[0070] The pressing force applied to the third bending tool by the first bending tool is particularly beneficial when the third bending tool is coupled to a moving means for moving the third bending tool from a parked position to a position for bending the sheet of glass between the third bending tool and the second bending tool. Suitable moving means includes a shuttle mechanism which may comprised a shuttle frame. When the third bending mould is at the parked position the third bending mould is positioned not to interfere with the shaping step (iii). When the third bending tool is coupled to a moving means the coupling therebetween may introduce a degree of flexibility such that the third bending tool coupled to the moving means is not able to provide sufficient resistance for the pressing that is required during step (iv) and this may be overcome by using the first bending tool to press against the third bending tool during step (iv).

[0071] In some embodiments, during step (iv) the sheet of glass is pressed between the first bending tool and the third bending tool, and the second bending tool is pressed against the third bending tool.

[0072] In such embodiments a pressing force is applied to the third bending tool by the second bending tool, and this helps shape the glass during step (iv).

[0073] Preferably the second bending tool comprises at least a first strengthening member to increase the strength and / or rigidity thereof when the second bending tool is being pressed against the third bending tool. It is preferred that the second bending tool is configured such that the first strengthening member does not contact the sheet of glass during step (ii).

[0074] Preferably the second bending tool is in direct contact with the third bending tool when the second bending tool is pressed against the third bending tool.

[0075] In some embodiments, during step (iv) the third bending tool is in direct contact with the sheet of glass on a first side of the third bending tool and in direct contact with the second bending tool on a second side of the third bending tool, the second side of the third bending tool being opposite the first side of the third bending tool.

[0076] Preferably the first side of the third bending tool is convex, and the second side of the third bending tool is concave.The pressing force applied to the third bending tool by the second bending tool is particularly beneficial when the third bending tool is coupled to a moving means for moving the third bending tool from a parked position to a position for bending the sheet of glass between the third bending tool and the first bending tool. Suitable moving means includes a shuttle mechanism which may comprised a shuttle frame. When the third bending mould is at the parked position the third bending mould is positioned not to interfere with the shaping step (iii). When the third bending tool is coupled to a moving means the coupling therebetween may introduce a degree of flexibility such that the third bending tool coupled to the moving means is not able to provide sufficient resistance for the pressing that is required during step (iv) and this may be overcome by using the second bending tool to press against the third bending tool during step (iv).

[0077] In embodiments where the first bending tool presses against the third bending tool during step (iv), the first bending tool may press against the third bending tool at any time during step (iv).

[0078] Preferably the first bending tool presses against the third bending tool for the entire length of the step (iv).

[0079] Preferably the first bending tool presses against the third bending tool with the same force during the entire length of step (iv).

[0080] Preferably the first bending tool presses against the third bending tool with a first force and then a second force, the first force being different to the second force.

[0081] The first bending tool may contact the third bending tool at any time after step (iii) has been completed.

[0082] The first bending tool may contact the third bending tool after step (iii) has been completed and still be in contact therewith when step (iv) begins.

[0083] In embodiments where the second bending tool presses against the third bending tool during step (iv), the second bending tool may press against the third bending tool at any time during step (iv).

[0084] Preferably the second bending tool presses against the third bending tool for the entire length of the step (iv).

[0085] Preferably the second bending tool presses against the third bending tool with the same force during the entire length of step (iv).

[0086] Preferably the second bending tool presses against the third bending tool with a first force and then a second force, the first force being different to the second force.

[0087] The second bending tool may contact the third bending tool at any time after step (iii) has been completed.The second bending tool may contact the third bending tool after step (iii) has been completed and still be in contact therewith when step (iv) begins.

[0088] From a second aspect the present invention provides apparatus for shaping a sheet of glass comprising: a first bending tool and a second bending tool for pressing a heat softened sheet of glass therebetween; retaining means for retaining the heat softened sheet of glass on the first bending tool; and control means for aligning a third bending tool with the heat softened sheet of glass retained on the first bending tool and for positioning the third bending tool relative to the first bending tool to press the heat softened sheet of glass between the first bending tool and the third bending tool.

[0089] The retaining means keeps the sheet of glass in contact with the first bending tool.

[0090] Apparatus according to the second aspect of the present invention is particularly useful for carrying out a method according to the first aspect of the present invention.

[0091] Preferably the retaining means is configured for retaining the heat softened sheet of glass on the first bending tool when the heat softened sheet of glass is not being pressed between the first bending tool and the second bending tool.

[0092] Preferably the first bending tool has a convex shaping surface, and the second bending tool has a complementary concave shaping surface.

[0093] Preferably the first bending tool has a concave shaping surface, and the second bending tool has a complementary convex shaping surface.

[0094] Preferably the first or second bending tool is a ring mould having a shaping surface for contacting at least a portion of a periphery of the sheet of glass.

[0095] Preferably the retaining means comprises a portion of the first bending tool.

[0096] Preferably the retaining means comprises an auxiliary bending tool.

[0097] Preferably the apparatus comprises a vacuum source in communication with at least one passage formed in at least one of the first, second and third bending tools.

[0098] Preferably the first or second bending tool is a ring.

[0099] Preferably the first and second bending tools are configured for bending a heat softened sheet of glass to a first shape having a first radius of curvature and the third bending tool is configured to shape at least a portion of the heat softened sheet of glass having the first shape to a second shape having at least one portion with a second radius of curvature less than the first radius of curvature.In embodiments where the apparatus comprises a vacuum source, preferably the vacuum source is used to retain a heat softened sheet of glass on the first bending tool when the sheet of glass is not being pressed between the first bending tool and the second bending tool.

[0100] In some embodiments the third bending tool is coupled to a moving means for moving the third bending tool from a parked position to a position between the first bending tool and the second bending tool.

[0101] In some embodiments the apparatus is configured such that the first bending tool is able to press against the third bending tool when there is relative movement between the second bending tool and the third bending tool for pressing a sheet of glass between the second bending tool and the third bending tool.

[0102] In such embodiments the apparatus is configured such that when the sheet of glass is pressed between the first bending tool and the third bending tool, the sheet of glass is shaped to a desired shape.

[0103] In some embodiments the apparatus is configured such that the second bending tool is able to press against the third bending tool when there is relative movement between the first bending tool and the third bending tool for pressing a sheet of glass between the first bending tool and the third bending tool.

[0104] In such embodiments the apparatus is configured such that when the sheet of glass is pressed between the first bending tool and the third bending tool, the sheet of glass is shaped to a desired shape.

[0105] Embodiments of the present invention will now be described by way of example only with reference to the accompanying drawings (not to scale), in which:

[0106] Figure 1 shows a schematic side view of a portion of a press bending station for bending a sheet of glass; Figure 2 shows a schematic side view of first and second complementary bending tools of figure 1 just before bending a sheet of glass;

[0107] Figure 3 shows a schematic side view of the first and second complementary bending tools of figure 2 press bending a sheet of glass therebetween;

[0108] Figure 4 shows a schematic side view of the first and second complementary bending tools of figure 2 and a third bending tool;

[0109] Figure 5 shows a schematic side view of a sheet of glass being bent between the second and third bending tools of figure 4;

[0110] Figure 6 shows a schematic side view of the shaped sheet of glass supported on the second bending tool of figure 1 with a carrier ring positioned below the shaped sheet of glass;Figure 7 shows a schematic side view of a shaped sheet of glass supported on the carrier ring shown in figure 6;

[0111] Figure 8 shows a schematic side view of a shaped sheet of glass supported on the carrier ring as shown in figure 7 positioned between a pair of blastheads for quenching the shaped sheet of glass;

[0112] Figure 9 shows a schematic side view of a shaped sheet of glass supported on the carrier ring shown in figure 6 beneath a vacuum platen;

[0113] Figure 10 shows a schematic side view of a shaped sheet of after having been deposited onto a conveyor from the vacuum platen shown in figure 9;

[0114] Figure 11 shows a schematic side view of a shaped sheet of glass supported on a third bending tool before being removed therefrom by a vacuum platen;

[0115] Figure 12 shows a schematic side view of a shaped sheet of glass after being deposited on a roller conveyor section;

[0116] Figures 13 - 15 show schematic side views of another embodiment where a sheet of glass is first shaped between a first bending tool and a second bending tool and also between the second bending tool and a third bending tool;

[0117] Figures 16 - 19 show schematic side views of another embodiment where a sheet of glass is first shaped between a first bending tool having a convex shaping surface and a second bending tool and also between the first bending tool and a third bending tool;

[0118] Figure 20 shows a schematic isometric perspective view of a shaped sheet of glass having three details in a major surface thereof;

[0119] Figure 21 shows a cross sectional view through the plane B-B' of figure 20;

[0120] Figure 22 shows a plan or side view of an assembly of two sheets and a shaped sheet of glass therebetween; Figure 23 shows a schematic side view representation of a press bending station for carrying out the present invention;

[0121] Figure 24 shows a schematic side view representation of the press bending station of figure 23 wherein a sheet of glass is being pressed between a first bending tool and a second bending tool;

[0122] Figure 25 shows a schematic side view representation of the press bending station of figure 24 wherein the shaped sheet of glass is retained on the second bending tool and a third bending tool is between the shaped sheet of glass and the first bending tool;Figure 26 shows a schematic side view representation of the press bending station of figures 23 - 25 pressing a shaped sheet of glass between the second bending tool and the third bending tool; and Figure 27 shows a schematic side view representation of the press bending station of figures 23 - 26 further showing a vacuum platen for removing the shaped sheet of glass after the step shown in figure 26 from the third bending tool to a conveyor section.

[0123] Figure 1 shows a side view schematic representation of a portion of a press bending station for bending a sheet of glass according to the present invention.

[0124] The press bending station comprises a roller conveyor 104 comprising a plurality of spaced apart rollers, two of which are labelled 104’ and 104”. A sheet of glass 100 is conveyed on the roller conveyer 104 in a direction of conveyance 102 for positioning on a plurality of conveyor rollers 106 located between a first bending tool 108 and a second bending tool 112. Suitable stopping means (not shown) may be located between the first and second bending tools 108, 112 to stop the sheet of glass at a desired position therebetween.

[0125] The first bending tool 108 is configured as an annular ring having an upper shaping surface 110. The second bending tool 112 is configured as a male die having a lower shaping surface 114. The upper shaping surface 110 is concave and the lower shaping surface 114 is convex, being complementary with the upper shaping surface 110. The upper shaping surface 110 may comprise a plurality of shaping surfaces or a single shaping surface. The lower shaping surface 114 is a full-surface shaping surface. The first and second bending tools 108, 112 may be a heated bending tools using embedded heating means such as electrical resistance heaters to keep the temperature thereof at a sufficiently high temperature for shaping, such as at least above 550 °C , for example around 600 °C. The first bending tool 108 may be made from steel and a suitable material for the second bending tool 112 includes ceramic and stainless steel. The shaping surfaces of the first and / or second bending tools may be covered with a fine mesh cloth i.e. woven stainless steel. The first bending tool 108 and the second bending tool 112 are entirely conventional in the art.

[0126] The conveyor rollers 106 includes rollers 106’, 106” and 106’” which are configured as dropdown rollers such that when the sheet of glass 100 is positioned at the desired position between the first and second bending tools 108, 112, the rollers 106’, 106” and 106”’ move downwards in the direction of the arrow 107 thereby depositing the sheet of glass 100 on the upper shaping surface 110 of the first bending tool 108. Alternatively, or as well as, the first bending tool 108 may move towards the second bending tool 112 thereby lifting the sheet of glass 100 from the rollers 106’, 106” and 106’”.

[0127] The sheet of glass 100 is heated to a temperature suitable for shaping between the first and second bending tools 108, 112. The first and second bending tools 108, 112 may be suitably heated to help maintain the temperature thereof.Figure 2 shows a side view representation of the first and second bending tools 108, 112 with a heated sheet of glass 100 therebetween. The heated sheet of glass 100 has been deposited onto the first bending tool 108 and is in contact with the upper shaping surface 110 thereof. The sheet of glass may be positioned on the first bending tool 108 after having been deposited thereon, for example as described in WO2016 / 189319A1 or WO2018 / 096339A1.

[0128] The second bending tool 112 is moved towards the first bending tool 108 with the heated sheet of glass 100 thereon by moving in the direction of arrow 113. Alternatively, or as well as, the first bending tool 108 with the heated sheet of glass 100 thereon may move towards the second bending tool 112.

[0129] Figure 3 shows a side view representation of the first and second bending tools 108, 112 shaping the heated sheet of glass by pressing therebetween. The shaped sheet of glass is labelled 101. The second bending tool 112, for example as described in W02005 / 033026A1, has passages formed therein having openings in the upper shaping surface 114 (not shown). During shaping the passages are communicated with a low-pressure source, such as a vacuum pump, to draw air through the passages thereby creating regions of negative pressure at the lower shaping surface 114 to draw the heated sheet of glass towards the lower shaping surface 114 to help acquire its shape.

[0130] Figure 4 shows a side view representation of the first and second bending tools 108, 112 after the shaped sheet of glass 101 has been shaped by pressing between the first and second bending tools 108, 112 as shown in figure 3.

[0131] The first bending tool 108 has been moved away from the second bending tool 112 such that the upper shaping surface 110 is no longer in contact with the shaped sheet of glass 101 and the shaped sheet of glass 101 is retained on the second bending tool 112 by maintaining the regions of negative pressure at the lower shaping surface 114. Instead of moving the first bending tool 108 away from the second bending tool 112, the second bending tool 112 may be moved away from the first bending tool 108 i.e. in the direction of arrow 117, and the shaped sheet of glass 101 may be retained on the second bending tool 112 by maintaining the regions of negative pressure at the lower shaping surface 114. Alternatively both the first and second bending tools 108, 112 may be moved away from each other to increase the spacing thereof, and the shaped sheet of glass 101 may be retained on the second bending tool 112 by maintaining the regions of negative pressure at the lower shaping surface 114.

[0132] As shown in figure 4, a third bending tool 116 has been positioned by suitable moving means between the first bending tool 110 and the shaped sheet of glass 101. The third bending tool 116 has a fullsurface shaping surface 116’ that is complementary with the lower shaping surface 114 and has details 116” thereon or therein, each detail having portion with a radius of curvature less than the radius of curvature of the lower shaping surface 114.Figure 4 therefore illustrates an embodiment having a spacing step wherein a spacing of the first and second bending tools 108, 112 has been increased such that the shaped sheet of glass 101 is kept in contact with the second bending tool 112 but is no longer in contact with the first bending tool 108.

[0133] Figure 5 shows the shaped sheet of glass 101 being pressed between the second bending tool 112 and the third bending tool 116.

[0134] In an embodiment the third bending tool 116 has an actuator means (not shown) to move the third bending tool 116 towards the shaped sheet of glass 101 to further press the shaped sheet of glass 101 between the third bending tool 116 and the second bending tool 112.

[0135] In another embodiment, when the third bending tool 116 has been moved into the position as illustrated in figure 4, the position thereof is locked by suitable locking means (not shown). The second bending tool 112 with the shaped sheet of glass 101 retained thereon is then moved toward the third bending tool 116 in the locked position to further press the shaped sheet of glass 101 between the third bending tool 116 and the second bending tool 112. Since the third bending tool 116 is in a locked position, the position of the third bending tool remains static when the sheet of glass is pressed between the second bending tool 112 and the third bending tool 116.

[0136] In another embodiment, when the third bending tool 116 is in contact with the shaped sheet of glass 101, the first bending tool 108 may be moved in the direction of arrows 119 towards the third bending tool 116 to press against the convex surface 116”’ of the third bending tool 116. The addition of an extra pressing force provided by the first bending tool 108 pressing against the convex surface 116’” of the third bending tool 116 may help better form the details 116” in the shaped sheet of glass 101. The extra pressing force provided by the first bending tool 108 as just described is helpful when the third bending tool 116 is not able to provide enough resistance to allow the sheet of glass to be sufficiently pressed during step (iv). For example, if the third bending tool is coupled to a moving means (not shown) for moving the third bending tool 116 from a parked position to a position for bending the sheet of glass 101 between the third bending tool 116 and the second bending tool 112 (i.e. as shown in figure 4), the coupling may introduce a degree of flexibility such that the third bending tool 116 coupled to the moving means is not able to provide sufficient resistance against the second bending tool 112 being moved toward the third bending tool 116 for the pressing that is required during step (iv).

[0137] The details 116” are pressed into the convex surface of the shaped sheet of glass 101 to further shape the sheet of glass and this shaping step may be referred to as a “detailing step”. The further shaped sheet of glass having the details 116” pressed therein is labelled 101’ and the convex major surface thereof is no longer smooth (like a major surface of a vehicle windscreen) because of the details therein.

[0138] Throughout this subsequent shaping step, the regions of negative pressure at the lower shaping surface 114 are preferably maintained to continue to draw the sheet of glass to the lower shaping surface 114.Note that figure 5 shows two possible detailing steps. In the first detailing step the first bending tool 108 is displaced relative to the third bending tool 116 such that there is no contact therewith. The shaped sheet of glass 101 is pressed between the second bending tool 112 and the third bending tool 116 as previously described.

[0139] In the second illustrated detailing step, the first bending tool 108 has been moved in the direction of arrows 119 toward the third bending tool 116 and the first bending tool 108 presses against the convex surface 116”’ of the third bending tool 116. In this embodiment the position of the first shaping tool 108 is shown in phantom and labelled 108’.

[0140] In embodiments when the first bending tool 108 presses against the third bending tool 116 it is preferred that the outer peripheries of the first and third bending tools are alignable during the detailing step. Also in such embodiments it is preferred to provide the first bending tool with at least a first strengthening member to increase the strength and / or rigidity of the first bending tool when the first bending tool is being pressed against the third bending tool. The use of a first bending tool 108 having at least the first strengthening member may allow higher pressing force to be applied to the third bending tool 116 by the first bending tool 108, which may be beneficial in forming the details 116” in the shaped sheet of glass 101. It is preferred that the first strengthening member does not contact the sheet of glass during step (ii).

[0141] After a sufficient time, the subsequent shaping step (the detailing step) is discontinued, as shown in figure 6, wherein the third bending tool 116 is no longer in contact with the shaped sheet of glass 101’.

[0142] Figure 6 shows the arrangement of first, second and third bending tools 108, 112, 116 after the subsequent shaping step (the detailing step) shown in figure 5. The third bending tool 116 has been moved away from the second bending tool 112 such that the shaping surface 116’ is no longer in contact with the shaped sheet of glass 101’, and the shaped sheet of glass 101’ is retained on the second bending tool 112 by maintaining or restarting the regions of negative pressure at the lower shaping surface 114.

[0143] Thereafter, a carrier ring 118 has been positioned below the shaped sheet of glass 101’ between the second bending tool 112 and the third bending tool 116.

[0144] In figure 7, the shaped sheet of glass 101’ has been deposited on the carrier ring 118. With reference to figure 6, this may be achieved by moving the carrier ring 118 toward the second bending tool 112 to contact the shaped sheet of glass 101’ , after which the vacuum source in communication with the passages in the second bending tool 112 may be switched off such that the shaped sheet of glass 101’ is no longer retained on the lower shaping surface 114 and is deposited on the carrier ring 118. There may be a space between the shaped sheet of glass 101’ and the carrier ring 118 when the vacuum source is switched off, although if the space is too great, this may cause damage to the shaped sheet of glass 101’ when dropped onto the carrier ring 118.The shaped sheet of glass 101’ supported on the carrier ring 118 may be transported thereon for further processing. This is illustrated in figure 8.

[0145] In figure 8, the shaped sheet of glass 101’ supported on the carrier ring 118 has been transported between a lower blasthead 120 and an upper blasthead 122. A portion of the carrier ring prior to be transported between the lower and upper blastheads 120, 122 is shown in phantom and labelled 118’. That is, going from the arrangement shown in figure 7 to the arrangement shown in figure 8, the carrier ring 118 with the shaped sheet of glass 101’ supported thereon is transported in the direction of arrow 119.

[0146] The lower blasthead 120 is configured to provide an array of jets of compressed air 124 to strike a major surface of the shaped sheet of glass 101’ in contact with the carrier ring 118, said major surface being referred to as a lower major surface of the shaped sheet of glass 101’. The upper blasthead 122 is configured to provide an array of jets of compressed air 126 to strike a major surface of the shaped sheet of glass 101’ opposite the lower major surface of the shaped sheet of glass 101’, said surface being referred to as the upper major surface of the shaped sheet of glass 101’.

[0147] The jets of compressed air 124, 126 quench the shaped sheet of glass 101’ to toughen or semitoughen the shaped sheet of glass 101’.

[0148] The carrier ring 118 may be provided with a suitable porous cover such as Kevlar® to help with airflow during quenching the shaped sheet of glass 101’.

[0149] After being quenched, the carrier ring 118 with the quenched, shaped sheet of glass 101’ thereon is transported away from the lower and upper blastheads 120, 122. This is illustrated in figure 9.

[0150] In figure 9, the carrier ring 118 with the shaped sheet of glass 101’ thereon has been transported to a position between a roller conveyor 128 and a vacuum platen 130. The vacuum platen 130 is used to remove the shaped sheet of glass 101’ from the carrier ring 118 and has passages therein in communication with a vacuum source (not shown) for providing regions of negative pressure at the surface 131. By moving the vacuum platen 130 towards the shaped sheet of glass 101’ i.e. in the direction of arrow 132, the vacuum platen approaches or contacts the upper major surface of the shaped sheet of glass 101’ wherein the negative pressure regions at surface 131 of the vacuum platen causes the shaped sheet of glass 101 ’ to be lifted off of the carrier ring 118 to become attached thereto. With further reference to figures 9 and 10, the carrier ring 118 is able to be moved to a parked position (see figure 10) because the shaped sheet of glass 101’ is retained on the vacuum platen 130. The vacuum platen may then be moved towards the roller conveyor 128 to deposit the shaped sheet of glass 101’ thereon by terminating the vacuum source provided to the vacuum platen 130. The vacuum platen 130 may then be moved away from the roller conveyor 128 by moving in the direction of arrow 134. The shaped sheet of glass 101’ is then conveyed in the direction of conveyance shown by arrow 135.Accordingly, in an embodiment the sequence of shaping steps is illustrated by figures 1 - 10 in sequence figure 1, 2, 3, 4, 5, 6, 7, 8, 9 and then 10.

[0151] In another embodiment, the sequence of shaping steps as illustrated by figures 1 - 5 remains the same and in the sequence figure 1, 2,3, 4 and then 5, but in this embodiment a carrier ring 118 is not used for subsequent transport of the shaped sheet of glass 101’ as illustrated in figures 6 - 10. Instead, in this embodiment after the shaping step illustrated in figure 5, instead of a carrier ring 118 being provided, the shaped sheet of glass 101’ remains supported on the third bending tool 116 after the vacuum source in communication with the passages in the second bending tool 112 is switched after.

[0152] With reference to figure 11, the third bending tool 116 supporting the shaped sheet of glass 101’ thereon may then be moved away from the second bending tool 112 (as shown in phantom), and thereafter to a location between a roller conveyor 128 and a vacuum platen 130. The vacuum platen 130 may be as described with reference to figures 9 and 10. The vacuum platen 130 may be moved in the direction of arrow 132 towards the shaped sheet of glass 101’ to attach the shaped sheet of glass 101’ thereto as previously described with reference to figures 9 and 10. With the shaped sheet of glass 101’ attached to the surface 131 of the vacuum platen 130, the third bending tool 116 may be removed from supporting the shaped sheet of glass 101’ thereon. Alternatively, or as well as, the vacuum platen 130 with the shaped sheet of glass 101’ attached thereto may be moved away from the third bending tool 116.

[0153] Thereafter, the vacuum platen 130 with the shaped sheet of glass 101’ attached thereto is moved such that the shaped sheet of glass 101 ’ is no longer between the vacuum platen 130 and the third bending tool. The vacuum source in communication with the vacuum platen 130 may then be switched off such that the shaped sheet of glass 101’ can be deposited onto the roller conveyor 128.

[0154] In figure 12, the shaped sheet of glass 101’ has been deposited onto the roller conveyor section 128’ such that the shaped sheet of glass 101’ is downstream of the third bending tool that is at a parked position. The shaped sheet of glass 101’ may be deposited onto the roller conveyor section 128.

[0155] The vacuum platen 130 is moved away from the shaped sheet of glass 101’ by moving in the direction of arrow 134 after the vacuum source in communication with the vacuum platen 130 is switched off.

[0156] In another embodiment, the sequence of shaping steps as illustrated by figures 1 - 3 remains the same and in the sequence figure 1, then 2, then 3, but in this embodiment the shaped sheet of glass is retained on the second bending tool 112 by the first bending tool 108. The second bending tool 112 may still be provided with passages therein for communicating with a low-pressure source as previously described. This embodiment is further described with reference to figures 13 - 15.

[0157] In this embodiment, after the bending step as shown in figure 3 has been carried out, the shaped sheet of glass 101’ is retained on the second bending tool 112 by continued pressing, which may be bymoving the first bending tool 108 towards the second bending tool 112 and / or by moving the second bending tool 112 towards the first bending tool 108. With the shaped sheet of glass 101 retained on the second bending tool 112 by the first bending tool 108, a third bending tool 216 is provided that can fit inside the inner periphery of the first bending tool 108. As shown in figure 13, the third bending tool 216 is positioned beneath the opening in the first bending tool 108 and may be moved in the direction of arrow 136 to contact the shaped sheet of glass 101.

[0158] The third bending tool 216 has a shaping surface 216’ with details 216” thereon or therein, similar to the third bending tool 116 previously described.

[0159] In figure 14, the shaped sheet of glass 101 is further shaped by moving the third bending tool 216 towards the second bending tool 112 to press the shaped sheet of glass 101 therebetween. The details 216” are then imprinted to the convex surface of the shaped sheet of glass 101 such that this step may be referred to as a detailing step.

[0160] In this embodiment there is no spacing step because the first and second bending tools 108, 112 are still in contact with the shaped sheet of glass 101 when the shaped sheet of glass 101 is being pressed between the third bending tool 216 and the second bending tool 112 during the detailing step.

[0161] Thereafter, as illustrated in figure 15, the first bending tool 108 and the third bending tool 216 are moved away from the second bending tool 112. The shaped sheet of glass 101’ is retained on the second bending tool 112 by provision of low-pressure through the passages therein. Alternatively, or as well as, the second bending tool 112 with the shaped sheet of glass 101’ retained thereon may be moved away from the first and third bending tools 108, 216. The movement of the first bending tool 108 and third bending tool 216 may be synchronised.

[0162] In an alternative embodiment, as illustrated with reference to figures 16 - 19, a heat softened sheet of glass 100 is initially deposited onto a first bending tool 312 having a convex shaping surface 313.

[0163] Disposed above the first bending tool 312 is a second bending tool 308 and a third bending tool 316. The first bending tool 312 comprises a full surface bending tool having a convex shaping surface 313. The second bending tool 308 comprises an annular ring having a concave shaping surface 309 complementary with the convex shaping surface 313. The third bending tool 316 is disposed inside the annular ring 308 and has a concave shaping surface 316’ with details 316” thereon or therein, similar to the third bending tool 116 previously described.

[0164] The heat softened sheet of glass 100 may also sag under the influence of gravity to gradually become shaped by contact with the shaping surface 313 of the first bending tool 312.

[0165] After the heat softened sheet of glass 100 has been deposited on the first bending tool 312, a second bending tool 308 being an annular ring having a concave shaping surface 309 complementary with the shaping surface 313 of the first bending tool 312 is moved towards the heat softened sheet of glass 100 (andalso the first bending tool 312) in the direction of arrow 320. In some embodiments the annular ring 308 comprises a first shaping rail and a second shaping rail such that the first shaping rail is moved in the direction of arrow 320 towards the heat softened sheet of glass 100 and the second shaping rail is moved in the direction of arrow 322 towards the heat softened sheet of glass 100.

[0166] Back to the embodiment illustrated, as shown in figure 17, the second bending tool 308 contacts the heat softened sheet of glass 100 to press between the first bending tool 312 and the second bending tool 308. The shaped sheet of glass is labelled 101.

[0167] Thereafter, a third bending tool 316 is moved toward the shaped sheet of glass 101 in the direction of arrow 324. The shaped sheet of glass 101 is further pressed by moving the third bending tool 316 towards the first bending tool 312 with the shaped sheet of glass 101 being further pressed in the peripheral region by the second bending tool 308, as illustrated in figure 18. When the shaped sheet of glass 101 is pressed between the third bending tool 316 and the first bending tool 312, the second bending tool 308 may be moved away from contacting the shaped sheet of glass 101.

[0168] As shown in figure 19, after a suitable time, the second and third bending tools 308, 316 are moved in the direction of arrow 326 away from the shaped sheet of glass with the details on or in the convex surface. The shaped sheet of glass with the details on or in the convex surface is labelled 101’.

[0169] The first bending tool 312 may have passages therein for communicating with a low-pressure source to assist with shaping the heat softened sheet of glass 100, 101 during any of the steps shown in figures 16 - 19.

[0170] The shaped sheet of glass 101’ may be removed from the first bending tool 312 using suitable means such as a suitably configured vacuum platen for subsequent processing.

[0171] In an alternative embodiment to that illustrated by figures 16 - 19 and described above, a third bending tool having an outer periphery alignable with an outer periphery of the second bending tool 308 is used instead of the third bending tool 316. Such a third bending tool has a concave shaping surface complementary with the convex shaping surface 313 with details 316” thereon or therein.

[0172] In such an embodiment the third bending tool is not disposed in the annular ring as illustrated in figures 16 - 19 but is instead initially at a parked position when the sheet of glass is being pressed between the first bending tool 312 and the second bending tool 308. Thereafter, the second bending tool 308 is spaced apart from the first bending tool 312 and the shaped sheet of glass is retained on the first bending tool 312 due to the convex shape thereof.

[0173] Thereafter, the third bending tool having an outer periphery alignable with an outer periphery of the second bending tool 308 is moved between the second bending tool 308 and the first bending tool 312 to a position suitable for pressing the shaped sheet of glass retained on the first bending tool 312 between thejust described third bending tool and the first bending tool 312. The second bending tool 308 may be used to apply additional force to the third bending tool of this embodiment thereby helping shape the sheet of glass.

[0174] Figure 20 shows a shaped sheet of glass 401 shaped according to the present invention. The shaped sheet of glass 401 has a convex major surface 403 and an opposing concave major surface 405. In the surface 403 are details in the form of three imprints 407, 409 and 411. A cross-sectional view of the shaped sheet of glass 401 through the plane B-B' is shown in figure 21. A zoomed in view of a portion of the convex surface 403 is also shown in figure 21.

[0175] With continued reference to figures 20 and 21, the shaped sheet of glass 401 has a radius of curvature 413. With reference to figures 1 - 3, the radius of curvature 413 was imparted to the sheet of glass by the lower shaping surface 114 of the second bending tool 112. In this particular example, the shaped sheet of glass 401 has been bent with cylindrical curvature such that the radius of curvature is the same at both lateral edges.

[0176] The imprint 407 is an elongate line extending between opposing peripheral edges of the shaped sheet of glass 401. The imprint 409 is also an elongate line but lies within the periphery of the convex major surface 403 of the shaped sheet of glass 401. The imprint 411 is triangular shaped and has a longest side substantially aligned with the imprint 407.

[0177] Each imprint has a depth which may be the same or different. Only the depth of the imprint 411 is labelled as 415.

[0178] The imprint 407 has regions 417 where the radius of curvature is much less than the radius of curvature 413 of the shaped sheet of glass 401.

[0179] Similarly, the imprint 409 has regions 419 where the radius of curvature is much less than the radius of curvature 413 of the shaped sheet of glass 401.

[0180] Similarly, the imprint 411 has regions 421, 423 where the radius of curvature is much less than the radius of curvature 413 of the shaped sheet of glass 401.

[0181] It is difficult to impart the imprints 407, 409, 411 into the major surface 403 at the same time as shaping the initially flat sheet of glass with the radius of curvature 413, which is much larger than the radius of curvature of regions 417, 419, 421 and 423. The present invention splits the shaping process into two steps, a first step to provide the sheet of glass with a large radius of curvature, and a second step (a detailing step) to provide the sheet of glass with the required surface detail or details.

[0182] Figure 22 shows an assembly 500 comprising a shaped sheet of glass 501 between first and second sheets 503, 505. The sheets 503, 505 may be curved and may be glass, plastic or metal or other suitable material.The shaped sheet of glass 501 is similar to the shaped sheet of glass 401 except there is only a single imprint 514 on a major surface thereof, which in this example is a convex major surface. The first and second sheets 503, 505 may be curved to the same extent as the shaped sheet of glass 501 such that the major surfaces thereof can be aligned when positioned in the assembly.

[0183] The first sheet 503 has a detail 512 thereon, which may be an imprint or raised portion.

[0184] The second 505 has a detail 516 thereon, which may be an imprint or raised portion.

[0185] The detail 512 is aligned with the imprint 514 on one side. The detail 516 is aligned with the imprint 514 on the other side to provide the assembly 500 with an overall detail 510.

[0186] Figure 23 shows a portion of a press bending line for carrying out methods according to the present invention. The press bending line comprises a press bending station 1.

[0187] The press bending press station 1 includes a first bending tool 3 and a second bending tool 5. In this example the first bending tool 3 comprises a frame having a base 7 with first and second uprights 9, 11 extending upwards therefrom. An annular ring 13 is mounted on the first and second uprights 9, 11 and has an upper shaping surface 13’ for supporting a sheet of glass thereon. As is conventional in the art the sheet of glass may be supported about a peripheral region on the upper shaping surface 13’ of the annular ring 13.

[0188] Often in the art the first bending tool 3 is referred to as bending frame, or a female bending frame. The annular ring 13 may comprise multiple sections forming the upper shaping surface 13’. The annular ring 13 may also be referred to as a “shaping rail”, or simply a “rail”.

[0189] Instead of a substantially annular ring 13, a full surface mould may be mounted on the ends of the uprights 9, 11.

[0190] In the example illustrated in figure 23, the upper shaping surface 13’ of the annular ring 13 is concave.

[0191] Although only two uprights 9, 11 are shown in figure 23, in practice there may be a plurality of uprights on which the annular ring 13 is mounted.

[0192] The second bending tool 5 comprises a male die 15 having a shaping surface 15’ configured to be complementary with the upper shaping surface 13’ of the annular ring 13.

[0193] The upper shaping surface 13’ may be covered with a suitable cloth, which may be a fine mesh cloth of woven stainless steel of other suitable material. Similarly, the shaping surface 15’ may be covered with a suitable cloth, which may be a fine mesh cloth of woven stainless steel of other suitable material.The male die 15 is movable in a vertical direction 17 by means of linear actuator 19.

[0194] The linear actuator 19 is mounted to a suitable gantry 21, the gantry 21 being fixed spatially in relation to the first bending tool 3.

[0195] The movement of the linear actuator 19 may be controlled by suitable control means (not shown), such as a computer-based system having suitable software installed.

[0196] The press bending station 1 also has a conveyor system 23 for conveying a heated sheet of glass 25 in a direction of conveyance 27 to a position between the first bending tool 3 and the second bending tool 5 for press bending therebetween.

[0197] The conveyor system 23 has a plurality of conveyor rolls (only one of which is labelled 23’) leading to a conveyor section 123 for supporting a heated sheet of glass 125 above the shaping surface 13’. The conveyor section 123 has three conveyor rolls 123’, 123” and 123’” that are coupled together and configured to drop away in the direction of arrow 29 thereby depositing a heated sheet of glass 125 onto the upper shaping surface 13’ of the first bending tool 3. A portion of the annular ring 13 is between roller 123’ in the conveyor section 123 and roller 23” in the conveyor system 23 and the rollers 23” and 123’ are sufficiently spaced apart to allow the annular ring 13 to pass therethrough.

[0198] With continued reference to figures 23 and 24, figure 24 shows a portion of the press bending station 1 when the conveyor rolls 123’, 123” and 123’” have dropped away such that the heated sheet of glass 125 that was supported on the conveyor rolls 123’, 123” and 123” has been deposited onto the shaping surface 13’. Thereafter, the linear actuator 19 has been activated to move the male die 15 toward the first bending tool 3 to press the heated sheet of glass 125 between the shaping surface 15’ of the male die 15 and the shaping surface 13’ of the annular ring 13. The shaped sheet of glass shown in figure 24 is labelled as 125’.

[0199] Figure 24 also shows in more detail the male die 15, where there are passages 33, 35 formed in the male die 15. Each passage 33, 35 has a respective first opening in the shaping surface 15’ of the male die 15 and a second opening at the opposite end of the respective passage. Conveniently the second openings face the gantry 21. The passages 33, 35 are in fluid communication with a valve 37 via suitable conduits 39, which may comprise flexible pipes. The valve 37 is in fluid communication with a vacuum pump 41 via a pipe 43. When the valve 37 is open, the vacuum pump can be actuated to draw air through the passages 33, 35 thereby helping shape the heated sheet of glass 125 and causing the shaped sheet of glass 125’ to be supported on the male die 15. This is shown in figure 25.

[0200] In figure 25, with the valve 37 open and the vacuum source 41 actuated, the male die 15 is moved away from the first bending tool 3 i.e. in the direction of arrow 49. Due to the provision of the vacuum by the vacuum source 41, the shaped sheet of glass 125’ is kept against the shaping surface 15’ of the male die 15. That is, the shaped sheet of glass 125’ is retained on the male die 15 and the shaped sheet of glass 125’is no longer in contact with the shaping surface 13’ of the annular ring 13. When the male die 15 has been moved sufficiently away from the first bending tool 3, a full surface mould 45 is positioned between the shaped sheet of glass 125’ and the annular ring 13. The position of the full surface mould 45 before the male die 15 has been moved away from the first bending tool 3 is shown in phantom as 47. The position of the full surface mould 47 is shown in phantom at a “parked” position, which may be at anywhere that does not interfere with the press bending operation shown in figure 24.

[0201] The full surface mould 45 has a shaping surface 45 ’ that has a curvature that is generally complementary to the shaping surface 15’ of the male die 15. However, the shaping surface 45’ includes one or more region having a radius of curvature less than a corresponding radius of curvature of the shaping surface 15’. For example, if the radius of curvature of the shaping surface 15’ of the male die 15 is 10 metres (10 m), the shaping surface 45’ of the full surface mould 45 has one or more region having a radius of curvature less than 10 m, especially much less than 10 m, i.e. 1 m or less, for example 1-50 cm.

[0202] The shaping surface 45 ’ may also include one or more feature to provide a crease or line on or in the surface of the shaped sheet of glass 125’.

[0203] With further reference to figure 26, the male die 15 with the shaped sheet of glass 125’ retained thereon by the provision of the low-pressure regions at the shaping surface 15’ by the vacuum source 41 being actuated and the 37 being open, is moved towards the full surface mould 45 i.e. in the direction of arrow 51 until the shaped sheet of glass 125’ contacts the shaping surface 45’. Thereafter, the shaped sheet of glass 125’ is pressed between male die 15 and the full surface mould 45, wherein it is preferred that the vacuum source 41 remains actuated and the valve 37 remains open to urge the shaped sheet of glass 125’ towards the shaping surface 15’ during this subsequent pressing step (the detailing step).

[0204] With further reference to figures 26 and 27, after a desired length of time, the vacuum source 41 is turned off and / or the valve 37 is turned off. The male die 15 is then moved in the direction of arrow 53 away from the full surface bending tool 45, and because there are no longer regions of low pressure at the shaping surface 15’, the shaped sheet of glass 125’ with additional features due to the detailing step (such shaped sheet of glass being labelled 125”) remains on the full surface bending tool 45. This is shown in phantom in figure 27 and labelled 45 ” .

[0205] With further reference to figure 27, the full surface bending tool 45 with the shaped sheet of glass 125” thereon is then moved from between the male die 15 and the first bending tool 3 to a position downstream of the male die 15 i.e. in direction of arrow 55, to a location above a conveyor section 223 comprising a plurality of conveyor rollers 223’ (only one of which is labelled). A suitable vacuum platen 60 is then used to pick the shaped sheet of glass 125” from the full surface bending tool 45. The full surface bending tool 45 then moves to a parked position (not shown) for a subsequent detailing step.The vacuum platen 60 with the shaped sheet of glass 125” thereon is then moved close to the conveyer rollers of the conveyor section 223 and the vacuum of the vacuum platen 60 disengages so that the shaped sheet of glass 125” (shown in phantom attached to the vacuum platen 60) can be deposited on the conveyor rollers 223’ of the conveyor section 223. The shaped sheet of glass 125” deposited on the conveyor section 223 is then conveyed to another location for subsequent processing.

[0206] Once cooled, the shaped sheet of glass 125” may be used as a monolith or may be laminated to another sheet of glass or other glazing material such as polycarbonate. Suitable lamination material includes polyvinyl butyral, ethylene vinyl acetate copolymer, polyurethane, polycarbonate, polyvinyl chloride, or a copolymer of ethylene and methacrylic acid.

[0207] In the previous examples the sheet of glass 100, 401, 501, 25, 125 may be a sheet of soda-lime-silica glass that is preferably produced using a float process or a rolled process. The sheet of glass may have a thickness between 0.5mm and 25mm and is preferred to have a thickness between 1 mm and 6 mm.

[0208] The sheet of glass is heated to a temperature suitable for shaping and this temperature will vary depending upon the composition of the sheet of glass. For a typical sheet of soda-lime-silica glass, the temperature for shaping may be between 700 °C and 750 °C.

[0209] It has been found that by first shaping a sheet of glass between first and second bending tool, and thereafter shaping the sheet of glass between the first bending tool and a third bending tool, certain details can be imparted to the sheet of glass that would not be possible using only first and second bending tool. Such shaped sheets of glass may find particular use in applications not requiring the same level of optical clarity as required by a sheet of glass used in a vehicle windscreen.

Claims

CLAIMS1. A method of shaping a sheet of glass, the sheet of glass having a first major surface and a second opposing major surface, the method comprising the steps:(i) heating the sheet of glass to a temperature suitable for shaping;(ii) depositing the sheet of glass on a first bending tool for supporting the sheet of glass thereon;(iii) pressing the sheet of glass between the first bending tool and a second bending tool; and thereafter(iv) pressing the sheet of glass between a third bending tool and the first bending tool or the second bending tool.

2. A method according to claim 1, wherein after step (iii) and before step (iv) there is a spacing step (iii)’, wherein during the spacing step (iii)’ a spacing of the first bending tool and the second bending tool is increased to remove contact of the sheet of glass with the first bending tool or the second bending tool while keeping the sheet of glass in contact with the other of the first bending tool and the second bending tool such that during step (iv) the sheet of glass is shaped by pressing between the third bending tool and the other of the first bending tool and the second bending tool still in contact with the sheet of glass after the spacing step (iii)’.

3. A method according to claim 2, wherein following step (iii)’, the sheet of glass is kept in contact with the second bending tool by at least one region of low pressure between the sheet of glass and the second bending tool, and wherein the first bending tool is spaced apart from the second bending tool such that the first bending tool is not in contact with the sheet of glass.

4. A method according to claim 2, wherein following step (iii)’, the sheet of glass is kept in contact with the second bending tool by an auxiliary bending tool being pressed against the sheet of glass and wherein the first bending tool is not contact with the sheet of glass,preferably wherein the auxiliary bending tool has at least one shaping rail for contacting the sheet of glass during step (iii)’ .

5. A method according to claim 4, wherein the auxiliary bending tool has two spaced apart shaping rails for contacting the sheet of glass during step (iii)’, preferably wherein the auxiliary bending tool is configured as a ring for contacting the sheet of glass during step (iii)’.

6. A method according to claim 2, wherein following step (iii)’, the sheet of glass is kept in contact with the first bending tool and the second bending tool is spaced apart from the first bending tool such that the second bending tool is not in contact with the sheet of glass.

7. A method according to claim 6, wherein the first bending tool is a full surface bending tool and / or wherein the first bending tool has a convex shaping surface.

8. A method according to any of the preceding claims, wherein the first bending tool has at least one shaping rail for supporting the sheet of glass thereon during step (ii), preferably wherein the first bending tool has two spaced apart shaping rails for supporting the sheet of glass thereon during step (ii), more preferably wherein the first bending tool is configured as a ring.

9. A method according to any of the preceding claims, wherein the first bending tool has a shaping surface complementary with a shaping surface of the second bending tool.

10. A method according to any of the preceding claims, wherein the second bending tool has at least a first passage extending therethrough and wherein a vacuum source is connectable to the first passage to produce at least a first region of low pressure preferably at a shaping surface of the second bending tool.

11. A method according to any of the preceding claims, wherein the second bending tool is a full surface bending tool.

12. A method according to any of the preceding claims, wherein the third bending tool is a full surface bending tool.

13. A method according to any of the preceding claims, wherein the during step (iii) the sheet of glass is pressed to a first shape having a first radius of curvature, and wherein during step (iv), the sheet of glass is pressed to a second shape, the second shape having at least a region having a second radius of curvature smaller than the first radius of curvature.

14. A method according to claim 13, wherein the first radius of curvature is at least 300 mm and / or at most 20,000 mm; and / or wherein the second radius of curvature is less than 300 mm, preferably less than 200 mm, more preferably less than 100 mm, even more preferably less than 50 mm.

15. A method according to any of the preceding claims, wherein the first bending tool has an outer periphery and at least a portion of the outer periphery of the first bending tool is alignable with at least a portion of an outer periphery of the third bending tool.

16. A method according to any of the preceding claims, wherein third bending tool has a shaping surface for introducing at least a first detail to the sheet of glass shaped following step (ii) such that during step (iv) the first detail produces at least a first region of the sheet of glass having a radius of curvature preferably less than R mm, wherein R is 1000, or 900, or 800, or 700, or 600, or 500, or 400, or 300, or 200, or 100, or 90, or 80, or 70, or 60, or 50, or 40, or 30, or 20, or 10.

17. A method according to any of the preceding claims, wherein at least one of the first bending tool, the second bending tool and the third bending tool is a heated bending tool preferably comprising at least one electrical resistance heating element for adjusting and / or maintaining the temperature thereof.

118. A method according to any of the preceding claims, wherein during at least one of step (iv) and when present step (iii) ’ , a vacuum is drawn through at least one passage formed in the second bending tool; and / or wherein during step (iii) a vacuum is drawn through at least one passage formed in the first bending tool and / or second bending tool.

19. A method according to any of the preceding claims, wherein during step (iv) the sheet of glass is pressed between the second bending tool and the third bending tool, and the first bending tool is pressed against the third bending tool; or wherein during step (iv) the sheet of glass is pressed between the first bending tool and the third bending tool, and the second bending tool is pressed against the third bending tool.

20. Apparatus for shaping a sheet of glass comprising:a first bending tool and a second bending tool for pressing a heat softened sheet of glass therebetween;retaining means for retaining the heat softened sheet of glass on the first bending tool; andcontrol means for aligning a third bending tool with the heat softened sheet of glass retained on the first bending tool and for positioning the third bending tool relative to the first bending tool to press the heat softened sheet of glass between the first bending tool and the third bending tool, preferably wherein the retaining means is configured for retaining the heat softened sheet of glass on the first bending tool when the heat softened sheet of glass is not being pressed between the first bending tool and the second bending tool.

21. Apparatus according to claim 20, wherein the first bending tool has a convex shaping surface, and the second bending tool has a complementary concave shaping surface; or wherein the first bending tool has a concave shaping surface, and the second bending tool has a complementary convex shaping surface.

22. Apparatus according to claim 20 or claim 21, wherein the retaining means comprises a portion of the first bending tool or an auxiliary bending tool.2823. Apparatus according to any of the claims 20 to 22, comprising a vacuum source in communication with passages formed in at least one of the first, second or third bending tools, preferably wherein the vacuum source at least in part is used to retain a heat softened sheet of glass on the first bending tool.

24. Apparatus according to any of the claims 20 to 23, wherein the first and second bending tools are configured for bending a heat softened sheet of glass to a first shape having a first radius of curvature and wherein the third bending tool is configured to shape at least a portion of the heat softened sheet of glass having the first shape to a second shape having at least one portion with a second radius of curvature less than the first radius of curvature.

25. Apparatus according to any of the claims 20 to 24, configured such that the second bending tool is able to press against the third bending tool when there is relative movement between the first bending tool and the third bending tool for pressing a sheet of glass between the first bending tool and the third bending tool.29

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