Tool for shaping a hot matrix

Abstract

The invention relates to a forming tool comprising a film (600) made of a polymeric material, said film having a forming surface, characterized in that the tool comprises a thermalization device (700) inserted into the film.

Description

TECHNICAL FIELD

[0001] The present invention relates to a technique for bending a glass sheet, followed by a cooling step. The technique according to the invention is either suitable for bending a glass sheet intended to be tempered in particular, or for bending a glass sheet which will subsequently be cooled then assembled in pairs to form a laminated glazing. BACKGROUND

[0002] Several techniques exist for shaping a hot substrate such as a glass sheet. Among these techniques, one consists in conveying the glass sheet one after the other through a furnace to raise its temperature to a temperature close to the softening temperature, where the glass sheet is conveyed on a roller bed. Once it exits the furnace, the glass sheet is then conveyed to a bending station. In the bending station, the glass sheet is lifted off the conveyor by a frame, which has the shape that is desired to be imparted to the glass sheet. This frame is usually called a "pressing frame" or "pressing ring". Depending on the configuration of the roller bed, the frame is continuous or discontinuous so as to be able to pass through the roller bed on which the glass sheet is initially located. The frame then lifts the glass sheet and presses it against a solid upper mold, called a bending mold, which has a shape that matches the shape of the frame, and thus corresponds to the desired shape of the glass sheet. After pressing, the glass is sucked and held against the mold, then the glass is released onto the roller bed or onto another frame, called a transfer carriage, to be transferred to a cooling zone. In the former case, the rollers then start moving again to convey the glass sheet to a tempering station.

[0003] The two tools (pressing frame and bending mold) are usually covered with a layer of sandwich material to avoid thermal shock on the glass sheet when it comes into contact with the tools. These materials are usually textile, woven or knitted fabrics based on refractory fibers (such as silica), metal fibers or high-temperature resistant polymers (such as fibers).

[0004] In addition to the specific features of the lower frame that passes through the roller bed, which serves as a conveyor, this type of technique is characterized in that the bending operation is performed outside the furnace, or at least outside the chamber that maintains a high temperature. By "high temperature", it is intended to mean a temperature that is generally greater than 250-300°C. This technique should therefore be considered as a cold technique, which qualifier qualifies the location of the bending station outside the chamber that maintains a high temperature: this means that the control of the position of the bending tools is simpler than in the case of hot techniques, and conversely, the bending method is a race against time, since the glass sheet cools down as soon as it exits the furnace. Therefore, modifications to the bending operation or to the bending conditions are tricky and limited.

[0005] One disadvantage of this method is that the upper mold and the frame are specific parts. This means that for each glass shape, the upper mold and the frame have to be machined to the exact dimensions of the glass shape to be produced.

[0006] In order to make the upper mold available for different glass shapes, the upper mold is deformable. One solution is to use an upper mold in the form of a film made of a polymeric material. This material has the advantage of being flexible and can therefore be deformed to the desired curvature.

[0007] However, a polymeric film used as an upper mold for a bending station is not obvious, since the high temperatures in the bending station would damage the film. SUMMARY

[0008] One object of the present invention is to solve the problems of the prior art by providing an upper mold for a bending station, which is changeable, i.e. which can allow the production of glass sheets with different degrees of curvature while being subjected to the temperature limitations inherent in bending.

[0009] The present invention therefore relates to a forming tool comprising a film made of a polymeric material, said film having a forming surface, characterized in that the tool comprises a thermalization device inserted into the film.

[0010] According to one example, the tool further comprises a device for increasing the thermal conductivity of the film.

[0011] According to one example, the thermalization device comprises at least one conduit passing through the film according to the profile of the film, and a heat transfer liquid flowing in the conduit.

[0012] According to one example, the thermalization device comprises a series of conduits passing through the film according to the profile of the film and a liquid flowing through the conduits, the conduits extending parallel to each other.

[0013] According to one example, the heat transfer liquid in two adjacent conduits flows in opposite directions.

[0014] According to one example, the tool comprises another series of conduits extending in a direction orthogonal to the direction in which the first series of conduits extends.

[0015] According to one example, the device for increasing the thermal conductivity of the film comprises metal particles or carbon-based particles embedded in the polymeric material.

[0016] According to one example, the device for increasing the thermal conductivity of the film comprises metal fibers or carbon-based fibers.

[0017] According to one example, the device for increasing the thermal conductivity of the film comprises a textile.

[0018] According to one example, the textile fabric consists of metal fibers or spun yarns, or is a knitted fabric.

[0019] According to one example, the heat transfer liquid is cooled or heated.

[0020] The invention also relates to a glass sheet bending device comprising a pressing frame arranged to adapt to a glass sheet and to press the glass sheet against an upper die which is a shaping tool according to the invention.

[0021] The invention also relates to a method for building a membrane comprising the following steps:

[0022] providing a mold having the shape of the membrane to be manufactured and a polymeric material constituting the membrane;

[0023] injecting said material into the mold;

[0024] crosslinking the material;

[0025] characterized in that it comprises a step of placing a thermalization device and at least one step of placing a device for increasing the thermal conductivity.

[0026] According to one example, the method comprises several steps of injecting said material into the mold and several steps of crosslinking the material, each step of injecting the material into the mold being followed by a step of crosslinking said material.

[0027] According to one example, the step of placing a thermalization device comprises providing a thermalization device and placing it in the mold before the membrane material is injected.

[0028] According to one example, the step of placing a thermalization device comprises providing a thermalization device and providing an intermediate mold having a surface similar to that of the membrane to be manufactured but a smaller thickness, placing the thermalization device in said intermediate mold and injecting a portion of the membrane material into the intermediate mold, then crosslinking the material to form an intermediate portion, placing this intermediate portion in the mold of the membrane during the step of injecting said membrane material.

[0029] According to one example, the step of placing a device for increasing the thermal conductivity comprises providing a device for increasing the thermal conductivity in the form of metal or carbon particles or fibers and mixing them with the membrane material before it is injected.

[0030] According to one example, the step of placing a device for increasing the thermal conductivity comprises providing a device for increasing the thermal conductivity in the form of metal or carbon particles or fibers and mixing them with the membrane material after it is injected.

[0031] According to one example, the step of placing the means for increasing the thermal conductivity comprises providing the means for increasing the thermal conductivity in the form of a textile and placing it in the mould while the film material is being injected.

[0032] According to one example, the step of placing the means for increasing the thermal conductivity in the form of a textile comprises providing a textile and providing an intermediate mould, the surface of which is similar to the surface of the film to be built but of smaller thickness, placing the textile therein and injecting a portion of film material into the intermediate mould, the material then being cross-linked to form an intermediate portion,

[0033] During the step of injecting the film material, the intermediate portion is placed in the mould of the film.

[0034] According to one example, the means for increasing the thermal conductivity are magnetic and wherein at least one of the steps of placing the means for increasing the thermal conductivity uses magnets to position them.

[0035] According to one example, the method is such that it comprises, before the steps of placing the thermalization means and placing the means for increasing the thermal conductivity, at least one step comprising injecting a portion of film material and a step comprising cross-linking the material.

[0036] The application also relates to a tool thermalization method according to the application, said method comprising continuously measuring the temperature of the tool by means of temperature measuring means and comparing the measured temperature with a defined working temperature, the thermalization means heating the tool if the measured temperature is lower than the defined working temperature and the thermalization means cooling the tool if the measured temperature is higher than the defined working temperature. BRIEF DESCRIPTION OF DRAWINGS

[0037] Other particular features and advantages will become clear on reading the following description, given by way of indication and in no way limiting, with reference to the attached drawings wherein:

[0038] - Figure 1 An upper mould of a bending station according to the application is shown;

[0039] - Figure 2 A bending station according to the application is shown;

[0040] - Figure 3 A film for a bending station according to the application is shown;

[0041] - Figure 4 and Figure 5 A film thermalization means according to the application is shown;

[0042] - Figure 6 、 7Figures 8, 9, 9', 10a and 10b show different methods of increasing the thermal conductivity of the film according to the application. DETAILED DESCRIPTION

[0043] In Figure 1 Fig. 1, a forming tool according to the application is shown. This forming tool comprises a film 600 made of a polymeric material and associated with translation members in the form of mechanical actuators 71. One end of each translation member 70 is connected to the film 600 and the other end is connected to a rigid base 40.

[0044] This forming tool is shown upside down with respect to the situation in which it is used (for example Figure 2 as shown in the following figures).

[0045] This forming tool according to the application is used for the forming of a hot substrate or for the forming of a substrate that can be heated during said forming. An example of a hot substrate is a glass sheet coming out of a furnace in order to be formed.

[0046] Figure 2 A furnace 1 is shown in which a glass sheet V passes on a roller conveyor 3. When it is in the furnace 1, the glass sheet 2 reaches its softening temperature. The glass sheet is then conveyed to a forming device 4, still supported by the conveyor 3.

[0047] This forming device 4 is the position at which the softened glass sheet is manipulated in order to actually take its final shape.

[0048] In the forming device 4, a press frame 5 is arranged below the plane defined by the roller conveyor 3. When the glass sheet V reaches above this frame, means not shown in the figures make it possible to ensure the precise positioning of said glass sheet, then the movement of the glass sheet is stopped by stopping the rollers in the bending zone. Then, the press frame 5 passes through the roller bed 3 to lift the glass sheet.

[0049] As mentioned previously, the press frame 5 has the shape that it is desired to impart to the glass sheet V and is adapted to the glass sheet. The press frame is designed to be able to pass through the roller bed 3.

[0050] With the press frame 5 having taken over the glass sheet V, the press frame moves to press the glass sheet against a bending mould 6 positioned above the press frame 5. Thus, the glass sheet V is formed by pressing the glass sheet between the bending mould and the press frame 5. The bending mould 6 is associated with translation members 70 in the form of mechanical actuators 71, as Figure 1 shown.

[0051] The bending die 6 is preferably solid, and its shape is adaptable, allowing for the construction of glass sheets with different curvatures. The bending die may optionally be covered with refractory fibers (such as silica), metal fibers, or high-temperature resistant polymers (such as...). A woven sandwich material made of fibers. This sandwich material does not have... Figure 2 and Figure 3 And as shown in the following figures. The upper mold 6 is a forming tool according to the invention.

[0052] Another application involves the forming of metal sheets in forming apparatus 4. The metal sheet is heated to a softening temperature and then shaped by a pressing frame and a bending die.

[0053] In another application, the forming tool is used as part of a method during which the substrate to be formed undergoes heating. For example, such methods involve constructing parts from composite materials reinforced with fibers of any nature (metal, carbon, glass, or ceramic) from a fiber pad and a material to form the product mold (applied in liquid form, such as a resin type), or from a sheet. In this application, the forming tool is positioned in a manner similar to... Figure 1 The same applies; the forming surface itself appears at the top of the device. Different types of materials are stacked in continuous layers on the surface of the forming tool. The entire stack either forms naturally under its own weight, or is formed manually by pressing the different layers of the stack against the forming surface, or, when the components of the stack have a natural rigidity that does not allow them to form spontaneously or manually under their own weight, is formed by means of an upper inverse shape in the form of an outer ring. If residual air is to be removed so that no pores are formed in the final material, the entire stack can be placed in a flexible bladder in which the remaining air can be extracted. The bladder itself remains in contact with the forming tool. The article then undergoes a step in which the impregnated fiber mold e is cured on the forming tool to form a composite material with the desired shape. This curing can be carried out chemically by applying a curing agent or by special pressure or temperature conditions. This curing can be exothermic, that is, it can release heat.

[0054] According to the present invention, the membrane 600 for the forming tool has a length and width dimension of at least 100 × 100 mm, and can reach 2000 × 3000 mm or larger, and a thickness between 5 and 50 mm, preferably between 10 and 45 mm, and even more preferably between 15 and 40 mm. To enable the membrane 600 to withstand high temperatures, the forming tool includes a heating device 700, such as... Figure 3The thermalization device 700 comprises a plurality of conduits 702 in which a heat transfer liquid flows. The conduits 702 extend in the profile of the film along at least one direction of the film (length, width). Preferably, the conduits extend parallel to each other and parallel to the lower main face of the film 700 which is in contact with the glass sheet V to be formed.

[0055] More preferably, the thermalization device 700 comprises a first series of conduits 702 extending along the length of the film and a second series of conduits 702 extending along the width of the film.

[0056] The conduits 702 are made of a flexible material which allows the conduits 702 to deform without breaking when the film 600 is shaped. An example of material that can be chosen is Teflon or polyethylene.

[0057] The conduits 702 are arranged so as to allow the best possible heat exchange.

[0058] To this end, different rules or criteria are used to define the arrangement and the configuration of the conduits, these criteria being: the conduit diameter D wat , the conduit spacing DM and the distance E wat between the conduits and the lower face of the film, i.e. the face in contact with the hot glass, as illustrated in Figure 4 .

[0059] The criterion of the distance between the conduits and the lower face of the film is important because if the conduits 702 are too close to the lower face (in contact with the glass), then when the film is subjected to mechanical stresses, residual deformations appear on the lower surface of the film. These deformations are in the form of regular lines which create slight hollow grooves on the surface of the film and which can be transferred to the glass sheet during shaping.

[0060] The criterion of the distance DM between two adjacent conduits and the conduit diameter is such that: the distance between two adjacent conduits must be approximately twice the value of E wat . The idea is that each conduit discharges heat into a virtual tube inside the film having a square base whose side length d wat is approximately equal to 2 x E wat + D wat , where D wat is the diameter of the conduit containing the heat transfer liquid.

[0061] These criteria allow us to obtain the following values for the conduit geometry parameters:

[0062] - the distance E wat is between 2 and 10 mm, more preferentially between 2 and 7 mm, even more preferentially between 3 and 6 mm;

[0063] - the distance DM is between 2 and 20 mm, more preferentially between 3 and 15 mm, even more preferentially between 5 mm and 12 mm;

[0064] - diameter D of the duct containing the heat transfer liquid wat between 1 and 7 mm, preferably between 2 and 6 mm, even more preferably between 3 and 5 mm.

[0065] Other parameters related to the thermalization device are:

[0066] - the flow rate of the heat transfer liquid in the circuit is relatively moderate, generally between 1 and 10 L / min, but can be higher depending on the diameter of the ducts and the thermalization capacity required;

[0067] - the temperature of the heat transfer liquid depends on the difference between the measured temperature of the membrane and the working temperature defined for it. The temperature of the heat transfer liquid is between -10 and 250°C, preferably between 0 and 200°C, even more preferably between 10 and 200 degrees Celsius.

[0068] When the thermal matrix is formed, the membrane 600 needs to be cooled. For this purpose, the ducts 702 are used to transport a coolant to cool said membrane 600.

[0069] In one embodiment, the flow of heat transfer liquid in the ducts 702 is a bidirectional flow, as Figure 5 illustrated. It will be understood that the heat transfer liquid flows in opposite directions in two adjacent ducts 702. Indeed, if the circulation is always in the same direction, a temperature gradient appears since the cold heat transfer liquid enters the duct on the first side and exits the duct on the second side. This heat transfer liquid is heated by absorbing heat from the membrane, thus creating a temperature gradient between the first side and the second side. This tends to make the performance of the membrane more heterogeneous.

[0070] In the case of bidirectional flow and opposite directions of flow in two adjacent ducts, an interaction occurs between the ducts with different flow rates, thus making it possible to limit the surface thermal gradient at the membrane.

[0071] In the case where the membrane is to be cooled, the thermalization circuit 700 is used to dissipate the heat of the membrane, the application making it possible to cleverly direct the heat to the thermalization device 700. This is because the maximum amount of heat is at the surface of the membrane in contact with the thermal matrix, at the same time as these ducts are arranged in the membrane. Advantageously, the application makes it possible to direct the heat from the surface to the thermalization device, so that this heat can be dissipated.

[0072] To do this, means 800 for increasing the thermal conductivity are arranged in the membrane 600.

[0073] The first solution is to increase the thermal conductivity of the membrane by increasing the thermal conductivity of the polymeric material.

[0074] To this end, a first solution consists in incorporating particles 802 into the material forming the film, the particles 802 being made of a material having a higher intrinsic thermal conductivity than the material forming the film, such as Figure 6 The material used for the particles is preferably a metallic material, such as aluminum, bronze, copper, soft iron or a carbon-based material, such as graphite or carbon black.

[0075] These particles 802 are thus mixed with the polymer before polymer shaping, then cross-linked.

[0076] To vary the thermal conductivity, the proposed particles 802 are variable, such that the higher the particle rate, the greater the thermal conductivity. The particle content can be as high as 60% by volume.

[0077] For example, it is thus easy to go from a thermal conductivity value of about 0.2 W-m"1-K"1of the raw elastomer-based mold to a thermal conductivity value of 0.48 W-m"1-K"1with a filling ratio of aluminum particles of 40% by volume.

[0078] In one embodiment, the distribution of particles 802 is made non-uniform so as to make only one area of the film more thermally conductive.

[0079] More particularly, it is envisaged to make the thermal conductivity of the area of the film 600 in contact with the thermal matrix and between the thermalization device 700 better, as Figure 7 illustrated. To this end, the metal particles 802 chosen have magnetic properties, i.e. they are able to be attracted by a magnet. This possibility makes it possible to exert a magnetic force via a magnet during the molding of the film-forming material 600, in which the particles 802 are mixed, in order to attract the magnetic metal particles 802 to a defined area and thus control this distribution.

[0080] In an alternative embodiment, two layers of material are deposited in succession, the first layer being loaded with thermally conductive particles 802, thereby improving the thermal conduction and constituting the lower part of the film 600 from the lower surface of the film to the level of the duct, while the upper part is made of a layer of material not loaded with thermally conductive particles.

[0081] A second solution to direct the heat from the surface to the thermalization device 700 is to incorporate an insert 804 into the film 600, as Figure 8 illustrated. This insert 804 is an insert made of a metallic material to increase the thermal conductivity of the film.

[0082] This insert 804 is a textile that can take different forms.

[0083] In a first form, the textile insert 804 comprises metal fibers or carbon fibers or a mixture of both. These fibers are good conductors of heat due to the material they are made of. Moreover, since these fibers are in the form of filaments, a high form factor also enables good electrical conductivity. Indeed, the higher the form factor of the introduced particles, the better the thermal conductivity of the membrane is improved. The form factor quantifies the extent to which a particle deviates from a sphere. Thus, one can define an elongation index, which is equal to the ratio of the length to the width of an elongated particle, such as a grain of rice, or a flatness index, such as the ratio of the diameter to the thickness of a coin. In practice, the use of cut and dispersed filaments, such as metal or carbon fibers, in an elastomer-based matrix is very effective in increasing its thermal conductivity.

[0084] In a second form, the textile is in the form of a knitted fabric, as illustrated in Figure 9 This knitted fabric is composed of a stack of stitches. Each stitch is in fact a loop of yarn of a certain length. In contrast to a woven fabric, the yarn in a knitted stitch is relatively expanded, which gives the knitted fabric as a whole a great flexibility and the ability to shape itself into various geometrical shapes. More precisely, each loop has the following two abilities: the ability to twist to a large extent when the knitted fabric is subjected to a macroscopic deformation; and the ability to recover its initial geometry when the macroscopic deformation stops.

[0085] Moreover, since the yarn forming each stitch has a good form factor, good thermal conductivity is obtained with the use of a knitted fabric, while having the flexibility to deform the membrane.

[0086] In a third form, the textile is in the form of a spun yarn, which itself is made of finely dispersed metal fibers having a diameter between 8 and 20 pm, in particular between 8 and 16 pm. A "spun yarn" has the characteristic of being formed of staple fibers. These are held together by twisting and form the elementary constituent called "strands". Several strands are then twisted together to form the spun yarn. The spun yarn has the property of being "fluffy", which means that there is a large number of elementary fiber ends protruding from the surface of the knitted fabric itself. This property is beneficial because when you have several layers of knitted fabric, these fiber ends protruding from the surface of the metal knitted fabric interpenetrate at the interface of two adjacent layers. This allows the establishment of thermal bridges between the different knitted layers, thus improving the thermal conduction capacity. In an alternative, the textile comprising metal fibers or spun yarn or knitted yarn is impregnated. The textile is impregnated with an elastomer material similar, preferably identical, to the material constituting the membrane. This impregnation improves the contact between the metal fibers and the membrane material. Indeed, without impregnation, the contact between the metal fibers and the membrane material can be incomplete due to the presence of gaps between said fibers and the membrane material. These air-filled gaps reduce the thermal conduction performance.

[0087] By being impregnated, the textile limits the possibility of open spaces between the fibers and the membrane material, thus limiting the reduction of the thermal performance.

[0088] The textile is preferably arranged between the lower surface of the upper mold and the thermalization means 700. This arrangement allows the heat to be conducted from the surface to the thermalization means 700, which removes the heat. This alternative is illustrated in Figure 9' where the thermal conductivity increasing means 800 are arranged under the membrane 600. These thermal conductivity increasing means 800 consist of a stack of three inserts 804, in this case, three layers of impregnated metal knitted fabric fill the space between the lower surface of the membrane in contact with the hot glass sheet V and the thermalization means 700 consisting of an array of parallel ducts 702 in which a heat transfer liquid flows. More precisely, the interface between the layers of the impregnated knitted fabric is illustrated by the dotted lines 805. The layers of the impregnated knitted fabric are even arranged on the array of thermalization means 700 to further increase the thermal conductivity of the membrane around each duct 702. The different layers of knitted fabric are advantageously impregnated with an elastomer, which itself is partially or totally filled with fine metal particles, which further improves the overall thermal conductivity.

[0089] In a third alternative, increasing the thermal conductivity of the membrane consists of incorporating metal or carbon fibers 806 into the membrane-forming material, as illustrated in Figure 10a Figure 10b and 10b These metal fibers 806 are in the form of sheets or strips with a good form factor, which allows good electrical conductivity. The length of these metal fibers is approximately 0.5 to 10 mm, and the width is approximately 0.05 to 0.5 mm.

[0090] The thermal conductivity increasing means 800 can include a variety of means: for example, textile-like inserts 804 and particles 802 or particles and fibers.

[0091] To manufacture the membrane according to the application, the basic method is to provide a membrane material and a mold having the shape of the membrane, and then to inject / cast the material into the mold. Once the material is injected, the whole is left to rest so that the elastomer can crosslink.

[0092] To incorporate the thermalization means 700, the mold is adapted to place the means in the desired position in the mold before the membrane material is injected into the mold.

[0093] In another alternative, the thermalization means 700 are incorporated beforehand in the layer of membrane material. This alternative consists of providing a secondary mold in which the thermalization means 700 are placed, and then casting the membrane material. This secondary mold has the same surface as the primary mold but a smaller thickness. Once the material is cast, it is left to rest so that it can crosslink. A "portion" of the membrane material is then obtained in which the thermalization means 700 are placed.

[0094] The remaining film material can then be injected into the mold of the film, while inserting the film material "part" where the thermalization device 700 is placed. The whole is then left to rest so that the remaining material can cross-link, thus obtaining the film.

[0095] In the configuration where the metal particles 802 or metal fibers 806 are embedded in the film 600, the method is modified with the addition of a step of embedding such particles or fibers.

[0096] First, the metal particles or fibers are incorporated into the elastomer film material before it is injected into the mold. In this case, the elastomer material is stored in a container. The particles or fibers are then injected into the container, which is mixed as a whole to a homogeneous concentration.

[0097] Second, the metal particles or fibers are incorporated into the elastomer film material after it is injected into the mold. In this case, there are two options: before the thermalization device 700 is installed, in which case the particles or fibers can be mixed in the elastomer material so as to have a homogeneous distribution. Alternatively, the particles 802 or fibers 806 are incorporated after the thermalization device 700 is installed and they extend through the thickness by gravity.

[0098] In both possibilities, if the particles or fibers have magnetic properties, magnetic devices (such as magnets) can be placed around the mold to control the distribution of the particles or fibers.

[0099] In another embodiment where a textile is arranged, the method is modified to include a step of incorporating the textile. The textile is incorporated when the elastomer material is injected into the mold before the thermalization device 700 is arranged in place.

[0100] According to a first solution, once the elastomer material is injected, the textile is placed in the mold. Gravity will send the textile to the bottom of the mold, which is the surface that is below or in contact with the glass.

[0101] In a second solution, the incorporation of the textile requires several repetitions to build the film. To do this, the first repetition consists in injecting in the mold an amount of elastomer such that its thickness is equal to 10% of the total thickness of the film. This amount of elastomer material is then left so that it can cross-link.

[0102] Then, in a second repetition, the remaining elastomer material is injected. The textile is then incorporated. The textile moves by gravity to come into contact with the elastomer that has cross-linked. This second solution prevents the textile from being too close to the surface to prevent the textile from causing surface defects to appear.

[0103] In an alternative to this second solution, a number of repetitions greater than two is possible. Thus, in addition to the first repetition, one repetition can be made per metal braid, one repetition for the thermalization device 700 and finally one repetition.

[0104] In this second solution, the thermal conductivity increasing device 800 in the form of particles can be mixed with the film material before or after it is injected.

[0105] Of course, if the textile has magnetic properties, a magnet can be placed around the mold to control the positioning of said textile.

[0106] In the thermal matrix formation method, the film 600 has a thermal profile such that its temperature increases over time. Thus, the thermalization device 700 using a cooling liquid is used to maintain said film at a working temperature, which depends on the film material. The temperature profile thus presents a transient profile in which the temperature is positively varying and a steady-state profile in which the film 600 is cooled and thus the temperature is regulated.

[0107] However, it has been noted that when the film 600 is in its transient profile, the shape of the matrix formed is variable because the temperature variation of the film 600 causes the film to vary in response.

[0108] To avoid this, the duct 702 of the thermalization device 700 is used to shorten the transient and preheating profile of said tool before the thermal matrix passes. To do this, the duct is used to circulate a heating liquid. This heating liquid is injected to increase the temperature of the film so as to reach the optimal operating temperature more quickly.

[0109] In this case, the duct 702 is connected to a cooling circuit and a heating circuit. The change from one to the other is done by a valve controlled by a control unit. This control unit is also connected to measuring means for measuring the temperature of the film. These measuring means comprise at least one sensor, which can be a thermocouple or a thermal camera or an infrared sensor. The measuring means thus allow the control unit to switch from the injection of a heating liquid into the thermalization device to a cooling liquid and vice versa.

[0110] Of course, the application is not limited to the examples shown, but is susceptible to various variants and modifications that will be obvious to those skilled in the art.

Claims

1. A forming tool for forming glass sheets, comprising a membrane (600) made of a polymer material, said membrane having a forming surface, characterized in that, The tool includes a heating device (700) inserted into the membrane.

2. The tool according to claim 1, wherein, The tool also includes a device (800) for increasing the thermal conductivity of the membrane.

3. The tool according to claim 1, wherein, The heating device (700) includes at least one conduit (702) passing through the membrane according to the contour of the membrane, and a heat transfer liquid flows in the conduit.

4. The tool according to the preceding claim, wherein, The heating device (700) includes a series of conduits (702) that pass through the membrane according to the contour of the membrane, and a heat transfer liquid flows through the conduits, which extend parallel to each other.

5. The tool according to the preceding claim, wherein, The heat transfer fluid flows in opposite directions in two adjacent conduits (702).

6. The tool according to any one of claims 3 to 5, wherein, The tool includes another series of catheters that extend in a direction orthogonal to the direction in which the first series of catheters extend.

7. The tool according to any one of claims 1 to 5, wherein, The device (800) for increasing the thermal conductivity of the membrane includes metal particles or carbon-based particles (802) embedded in the polymer material.

8. The tool according to any one of claims 1 to 5, wherein, The device (800) for increasing the thermal conductivity of the membrane includes metal fibers or carbon-based fibers (806).

9. The tool according to any one of claims 1 to 5, wherein, The device (800) for increasing the thermal conductivity of the membrane includes a textile (804).

10. The tool according to the preceding claim, wherein, The textile is composed of metal fibers or short-fiber yarns, or is a knitted fabric.

11. The tool according to any one of claims 3 to 5, wherein, The heat transfer fluid is either cooled or heated.

12. A glass sheet bending device, comprising: A pressing frame (5) is configured to be adapted to a glass sheet and to press the glass sheet against an upper mold (6), the upper mold being a forming tool according to any one of the preceding claims.

13. A method for constructing a film for forming a forming tool for forming glass sheets, comprising the following steps: - Provide a mold having the shape of the membrane to be manufactured and polymer materials constituting the membrane; - Inject the material into the mold; - To crosslink materials; The method is characterized by comprising the steps of placing a heating device (700) and placing at least one device (800) for increasing thermal conductivity.

14. The method according to the preceding claim, wherein, The method includes several steps of injecting the material into the mold and several steps of cross-linking the material, with each step of injecting the material into the mold followed by a step of cross-linking the material.

15. The method according to claim 13 or 14, wherein, The step of placing the thermalizing device includes providing the thermalizing device and placing the thermalizing device in the mold before the membrane material is injected.

16. The method according to claim 13 or 14, wherein, The step of placing the thermalizing device (700) includes providing the thermalizing device and providing an intermediate mold, the surface of which is similar to the surface of the membrane to be manufactured but is thinner, placing the thermalizing device (700) in the intermediate mold, injecting a portion of the membrane material into the intermediate mold, and then crosslinking the material to form an intermediate portion, the intermediate portion being placed in the membrane mold during the step of injecting the membrane material.

17. The method according to claim 13 or 14, wherein, The step of placing the device for increasing thermal conductivity (800) includes providing the device for increasing thermal conductivity in the form of metal particles or carbon particles (802) or fibers (806) and mixing them with the membrane material before the material is injected.

18. The method according to claim 13 or 14, wherein, The step of placing the device for increasing thermal conductivity includes providing the device in the form of metal particles, carbon particles, or fibers, and mixing them with the membrane material after injection.

19. The method according to claim 13 or 14, wherein, The step of placing the device for increasing thermal conductivity includes providing the device in the form of a textile and placing it into the mold while the membrane material is being injected.

20. The method according to claim 13 or 14, wherein, The steps of placing a device for increasing thermal conductivity in the form of a textile include providing a textile and providing an intermediate mold, the surface of which is similar to the surface of the membrane to be constructed but less thick, placing the textile therein, injecting a portion of the membrane material into the intermediate mold, and then crosslinking the material to form an intermediate portion, which is placed in the membrane mold during the step of injecting the membrane material.

21. The method according to claim 13 or 14, wherein, The device for increasing thermal conductivity is magnetic, and at least one step of placing the device for increasing thermal conductivity uses a magnet to position it.

22. The method according to claim 13 or 14, wherein, The method comprises the following steps: prior to placing the thermalizing device (700) and the device for increasing thermal conductivity, including at least one step of injecting a portion of membrane material and a step of crosslinking the material.

23. A method for heating a tool according to any one of claims 1 to 11, the method comprising continuously measuring the temperature of the tool by means of a temperature measuring device and comparing the measured temperature with a defined operating temperature, wherein if the measured temperature is lower than the defined operating temperature, the heating device heats the tool, and if the measured temperature is higher than the defined operating temperature, the heating device cools the tool.

Images