Classifications

• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
  • C03B23/00—Re-forming shaped glass
  • C03B23/02—Re-forming glass sheets
  • C03B23/023—Re-forming glass sheets by bending
  • C03B23/03—Re-forming glass sheets by bending by press-bending between shaping moulds
  • C03B23/0307—Press-bending involving applying local or additional heating, cooling or insulating means
• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
  • C03B23/00—Re-forming shaped glass
  • C03B23/02—Re-forming glass sheets
  • C03B23/023—Re-forming glass sheets by bending
  • C03B23/035—Re-forming glass sheets by bending using a gas cushion or by changing gas pressure, e.g. by applying vacuum or blowing for supporting the glass while bending
  • C03B23/0352—Re-forming glass sheets by bending using a gas cushion or by changing gas pressure, e.g. by applying vacuum or blowing for supporting the glass while bending by suction or blowing out for providing the deformation force to bend the glass sheet
  • C03B23/0357—Re-forming glass sheets by bending using a gas cushion or by changing gas pressure, e.g. by applying vacuum or blowing for supporting the glass while bending by suction or blowing out for providing the deformation force to bend the glass sheet by suction without blowing, e.g. with vacuum or by venturi effect

Definitions

• the present invention relates to a device and method for bending a glass sheet.
• Curved glass sheets can have various applications. They can be used in particular as glazing in vehicles, for example motor vehicles, as a windshield, side windows, rear window or roof. These glazings can be toughened or laminated. For such applications it is necessary that the bending device allows the glass sheets to be formed precisely, without causing optical defects.
• the frame may be either discontinuous so as to be able to pass through the bed of rollers on which the glass sheet initially rests, or preferably, continuous, and in this case, the conveyor at this location may consist of rollers.
• the frame then raises the glass sheet to apply it against the surface of an upper shape (also called counter mold or male press).
• the shape is complementary to the frame and therefore corresponds to the desired shape for the glass sheet.
• the glass sheet can be placed on a frame before entering the oven, and progresses in the latter while being supported by the frame.
• the pressing on the upper form is operated by means of the same frame or a frame which replaces it in the raising and pressing of the sheet.
• the glass sheet can be pressed against the upper form by suction through this form.
• This is achieved for example using a multiplicity of conduits connected to means ensuring a certain depression on the surface of the form. These conduits are for example in communication with a central chamber at reduced pressure.
• Such an arrangement makes it possible to aspirate the glass sheet and thus cooperates with the movement of the frame in the forming of the glass sheet. After pressing, the frame descends to a conveying level.
• the frame retracts under the roller bed and thus redeposit the glass sheet on said roller bed, or the frame resumes its path by carrying the sheet.
• the lower frame descends while the glass sheet is still held against the upper press by the suction force of the latter, a second "shuttle" frame is positioned under the glass sheet and the suction is stopped. so that the glass sheet is placed on the shuttle.
• This shuttle frame corresponds at its periphery to the profile of the final curved sheet.
• the curved glass sheet is led to the cooling or tempering station.
• the type of bending technique described above is characterized in that the pressing operation takes place outside the oven or at least outside a temperature-controlled zone. This type of technique must therefore be considered as cold technology, this qualifier defining the location of the pressing station outside an enclosure maintained at temperature. It is also known to place a heating system in the upper press of so as to compensate for the loss of temperature due to the fact that the bending takes place outside the oven. This heating system can be, for example, heating resistors.
• the pressing operation takes place in the oven.
• the presses can be heated by the oven.
• the two complementary pressing elements should be manufactured, the solid upper form, also called the male press, and the lower frame, also called the ring or female press.
• the male press consists of a block whose shape must be of great precision. Furthermore, in current practice, this press includes all the functional elements such as the means ensuring the suction of the sheet or the heating elements of the press when it is necessary to heat the press to prevent the glass sheet from Thermal shock. In practice, therefore, the machining of this part is relatively restrictive, long and costly.
• the model of curved glass manufactured on the bending line must be changed to another model, it is necessary to change both the male and the female press. The production is stopped long enough to correctly position the pressing elements opposite and long enough to reach the right temperature of the presses. However, this time can be relatively long, especially for the male press which is characterized by a certain thermal inertia mainly due to its mass.
• the present invention consists of a device for bending a glass sheet as claimed in claim 1.
• the other claims define alternative and / or preferred aspects of the invention.
• the invention can make it possible to limit the cost and the time associated with the manufacture of the male pressing element and can also make it easier to make and faster the change of this element, when the model of curved glass manufactured on the line changes. It can also have the advantage that most of the male press remains in place and at the right temperature and that only part of the male press must be handled and reach the appropriate temperature.
• one of the pressing elements making up the bending / pressing station is formed from at least two distinct resilient parts, adapted to be fixed to one another. These two parts are called base and forming complement or complement.
• the base and the complement can be made either both in cast iron or in refractory steel, that is to say a steel resistant to high temperatures, or one in steel and the other in cast iron. Preferably, they are both made of the same material, they constitute rigid parts.
• the complement which is removable and interchangeable according to the shape to be given to the glass sheet, comprises a fixing surface adapted to be fixed to a fixing surface of the base and a forming surface adapted to be pressed against the glass sheet and give it a desired shape.
• the shape given to the glass sheet at this stage of the bending process is not necessarily the final final shape of the glass sheet.
• the glass sheet may loosen a bit after pressing.
• the complement is a resilient piece, capable of being fixed to the base, by screws for example.
• the complement is fixed to the base as contiguously as possible so that the heat of the base can communicate to the complement by simple conduction.
• the attachment surfaces of the base and of the complement may be non-planar and / or discontinuous surfaces. Indeed, discontinuities of the orifices or grooves type for example, may be present on the fixing surfaces of the base el or of the complement.
• the forming surface of the complement i.e. the surface which gives the glass sheet a particular shape, is non-planar and can also be discontinuous.
• a flexible metallic fabric can cover the forming surface of the male press. This can help avoid or reduce marks in the glass during pressing.
• the male press comprises means making it possible to generate a reduced pressure on the forming surface of the complement.
• These means can make it possible to attract the glass sheet to the male press or at least to aid in the movement of the glass sheet towards the male press. They can also allow the glass sheet to remain against the male press while the female press moves away and gives way, for example, to a shuttle frame. The reduced pressure can then be cut off and the glass sheet deposited in the shuttle.
• the base comprises in its center a chamber connected to suction means. It can be a vacuum pump system so as to create a reduced pressure in the chamber, that is to say a pressure below atmospheric pressure. In communication with the chamber, there may be conduits which can also operate at reduced pressure and which open onto the forming surface.
• the male press is formed of a base and of a complementary forming, it is important that these means making it possible to generate a reduced pressure are continuous through these two parts.
• the orifices of the conduits present on the fixing surface of the complement coincide with orifices present on the fixing surface of the base.
• the complement does not entirely cover the base, that is to say that the attachment surface of the complement is smaller than the attachment surface of the base.
• elements to the base so as to block the holes in the base not covered by the supplement.
• these elements are resistant stainless steel plates or sheets. at high temperatures.
• the complement itself may comprise portions which do not constitute a forming surface, allowing me to plug the suction orifices.
• the base and the complement it is possible to create one or more grooves on the fixing surface either of the base or of the complement or of both, and to fill them with a seal resistant to high temperatures, which, by crashing when tightening the fixing screws, will ensure -tightness.
• the invention can be used either in the case where the pressing station is located in the oven or in an enclosure maintained at temperature, or in the case where the pressing station is outside the oven or outside of a controlled zone in temperature.
• the base of the male press preferably comprises heating means. These can be formed for example of electric heating resistors included in the solid mass of the base.
• the male press can comprise more than one forming complement, identical to each other, or different.
• the male press can for example be formed of a base and two forming accessories.
• the complements are both adapted to be fixed to the base, are removable and interchangeable according to the shapes to be given to the glass sheets, each include a fixing surface suitable for being fixed to the fixing surface of the base and each, a forming surface adapted to be pressed against the glass sheets and give them a desired shape.
• the female press can then also include more than one frame, for example, two frames, each complementary to one of the two forming supplements of the male press. This can advantageously increase the production of the line by making it possible to press two or more sheets of glass in a single operation.
• the invention also relates to an industrial installation for bending glass sheets comprising a tunnel oven, a pressing station which can be located in or outside the oven, various pairs of complementary male and female presses according to the various models of curvature of glass sheets, and a cooling or tempering station, characterized in that at least one of the male presses which can be used in the pressing station is formed of at least two distinct resilient parts, a base and at least a forming complement, adapted to be fixed to each other, and characterized in that the complement, which is removable and interchangeable according to the shape to be given to the glass sheets, comprises a fixing surface adapted to be fixed to a base fixing surface and a forming surface adapted to be pressed against the glass sheets and give them a desired shape.
• the installation thus includes all the male and female presses which can be stored in the vicinity of the pressing station and which can be used alternately in the pressing station itself, in the manner of spare parts.
• the installation can use both traditional male presses, in one piece, as well as male presses according to the invention, formed from at least two resilient pieces.
• the invention also relates to a method of bending a glass sheet comprising a pressing step between two opposite and complementary presses according to the invention.
• the pressing step can be carried out either inside an oven, or outside of it or of an enclosure maintained at temperature.
• One of the advantages of the pressing step being carried out outside the oven is the better accessibility to the tool and therefore greater ease of changing and adjusting it.
• the male press when the pressing is carried out outside the oven, the male press comprises heating means. It is not necessary that the additional pressing according to the invention also includes such heating means. This can facilitate its manufacture and reduce the cost.
• the complement can be heated by conduction in contact with the base which includes the heating means.
• the complement can be designed to be as bulky as possible and therefore be heated more quickly. It is preferably made of cast iron or high temperature steel, which allows the conduction of heat from the base to the complement. It is also possible to preheat the forming complement before placing it on the base in the pressing station.
• Fig. 1 perspective view of a male press according to the invention comprising heating means
• Fig. 2 Perspective and exploded view of a male press according to the invention comprising heating means
• Fig. 3 perspective view of a male press according to the invention not comprising heating means
• FIG. 4 Schematic sectional view of a male press according to the invention comprising a suction system and heating means
• FIG. 5 Schematic view of the underside of a male press according to the invention comprising a suction system and two forming accessories
• Example 1 Curved glazing is produced on a production line according to the following steps.
• a sheet of glass is transported on a roller conveyor and passes through a tunnel oven where it is brought to its softening temperature, for example around 650-660 ° C.
• a pressing station At the exit of the tunnel oven, there is a pressing station.
• the glass sheet is led, still on the rollers, to the pressing station where it is lifted from the conveyor by a frame whose shape corresponds to that which one wishes to give to the periphery of the sheet of glass.
• the frame is continuous and crosses the bed of pebbles on which the glass sheet initially rests.
• This frame also called female press, is adapted to be pressed against the periphery of the glass sheet and give it a desired shape.
• the frame therefore lifts the glass sheet to press it against an upper male press whose shape is complementary to the frame and therefore corresponds to the desired shape for the glass sheet.
• the lower frame descends to a level below the pebble bed and thus redeposits the curved glass sheet on the pebble bed. These then resume movement and lead the glass sheet to a cooling station.
• the glass sheet has the desired final curvature, which is generally not equivalent to the curvature given by the pressing step.
• the shape of the curvature given by the pressing between the male and female presses is in fact an intermediate curvature which must be calculated with precision, so that after the glass has slightly relaxed and is cooled, it gives the desired final curvature.
• the male press 10 is represented in FIG. 1.
• the base 11 consists of two distinct resilient cast iron parts: a base 11 and a forming complement 12.
• the forming complement, or complement is fixed to the base by screws 13.
• the base comprises heating means made of electrical resistances 14 which pass through it and which make it possible to confer on the base a temperature of approximately 300-400 ° C. This temperature is adjustable by means of thermocouples 14 'located in the base.
• the complement adapts to the base and is joined to it, so that the base can heat the complement by thermal conduction and thus the temperature of the complement is similar to that of the base. It is necessary that the press is at a sufficient temperature to avoid that cold spots appear in the glass, which could constitute fragile points. As seen in FIG.
• the forming complement 12 can be detached from the base 11 to be inverted with another complement when the curvature model is changed during manufacture on the production line.
• the additional forming 12 comprises a fixing surface 15 adapted to be fixed to the fixing surface of the base 16, and a forming surface 17 adapted to be pressed against the glass sheet to give it a desired shape. We can see the locations 18 provided for the fixing screws in the complement.
• Example 2 Curved glazing is manufactured on a production line as described in Example 1, except that the pressing station is located in the tunnel oven, that is to say in an environment at a temperature of approximately 700 ° C.
• the male press does not have internal heating means. It is this male press which is represented in FIG. 3.
• Example 3 Curved glazing is manufactured on a production line as described in Example 1, except that the movement of the glass during the pressing step is provided in a slightly different manner.
• the male press 10 includes means for generating reduced pressure on the forming surface 17 of the complement. These means are composed of a chamber 19 connected to a system (not shown) for creating the vacuum or at least a pressure below atmospheric pressure, and of conduits 20 which pass through the male press up to the forming surface 17. This system makes it possible to attract and / or hold the glass sheet against the forming surface, by suction.
• the reduced pressure system is activated and the glass sheet is sucked up by the male press at the same time as the female press frame lifts the glass sheet.
• the frame After pressing, the frame descends while the glass sheet is still held against the upper press by the suction force of the latter.
• a shuttle frame is positioned under the glass sheet and the suction is stopped so that the glass sheet is placed on the shuttle. It is the shuttle frame which leads the curved glass to the cooling station.
• Example 4 Curved glazings are produced on a production line as described in Example 3, except that two glazings are produced simultaneously, thanks to two forming accessories attached to the base.
• Figure 5 shows a bottom view of the male press. Two forming accessories 12 and 12 'are fixed to the base 11 by screws 13.
• the base has a dimension of 125 x 86 cm.
• two sheets of glass are conveyed in parallel on the roller bed and are lifted and pressed against the male press by two female frames.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Organic Chemistry (AREA)
• Re-Forming, After-Treatment, Cutting And Transporting Of Glass Products (AREA)

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• 2004
  • 2004-04-26 EP EP04101735A patent/EP1591425A1/de not_active Withdrawn
• 2005
  • 2005-04-19 JP JP2007510018A patent/JP5148269B2/ja not_active Expired - Fee Related
  • 2005-04-19 US US11/568,296 patent/US8413467B2/en not_active Expired - Fee Related
  • 2005-04-19 WO PCT/EP2005/051711 patent/WO2005102945A1/fr active Application Filing
  • 2005-04-19 EP EP05747770A patent/EP1742885A1/de not_active Withdrawn

Non-Patent Citations (1)

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