DEVICE COMPRISING A FURNACE AND METHOD FOR THE USE THEREOF

Abstract

A furnace (2) has at least one furnace chamber (20) delimited by a wall (25); at least one opening (5) is provided in the wall (25). The opening is provided with at least one nozzle (50), configured to generate a sealing air flow. A glass semi-finished product (4) can be introduced into the furnace chamber.

Claims

1. Device (1) comprising a furnace (2) having at least one furnace chamber (20), being is delimited by a wall (25) and being adapted to receive a semi-finished glass product (4), wherein the wall (25) has at least one opening (5), which is provided with at least one nozzle (50), said nozzle being adapted to generate a sealing air flow.

2. Device according to claim 1, wherein the nozzle (50) is a ring nozzle.

3. Device according to claim 1, wherein the furnace (2) has a plurality of furnace chambers (20, 21, 22, 23), which are configured to be passed through sequentially by the semi-finished glass product (4), each furnace chamber configured to be brought to a different temperature.

4. Device according to claim 1, further comprising at least one thermal camera, configured to determine temperature variation on a surface of the semi-finished glass product (4).

5. Device according to claim 1, further comprising at least one embossing die (6) configured to re-shape the semi-finished glass product (4).

6. Device according to claim 5, wherein the embossing die is located in a partial volume (250) of the furnace chamber (20), and the device is configured to control temperature in the furnace chamber (20) such that a temperature of the partial volume (25) differs from a temperature of the remaining volume within the furnace chamber (20).

7. Device according to claim 5, wherein a complementarily shaped counter embossing die (60) is arranged opposite the at least one embossing die (6).

8. Device according claim 1, further comprising at least one laser (3) configured to generate a laser beam (30), wherein the device is configured to direct the laser beam onto one or more predetermined partial areas (40) of the semi-finished glass product (4).

9. Device according to claim 8, further comprising at least one movable mirror (35) configured to direct the laser beam onto said one or more predetermined partial areas (40) of the semi-finished glass product (4).

10. Device according to claim 1, further comprising a transport pallet (7) having three contact points (71, 72, 73) which define a triangle and are configured to be received in an interlocking fashion in associated receiving devices (8) of the furnace chamber (20).

11. Device according to claim 10, wherein the transport pallet has a center of gravity located within the triangle defined by the three contact points.

12. Device according to claim 10, wherein the contact points have a V-shaped support body and the receiving devices have a round outer cross-section.

13. Device according to claim 10, wherein one of the furnace chamber's receiving devices receives a plurality of contact points.

14. Device according to claim 1, wherein the furnace has at least one air circulation system configured to circulate air in the furnace chamber.

15. Device according to claim 1, wherein the furnace comprises at least one sheet metal heat deflector which is arranged inside the furnace chamber and covers at least part of the wall, the heat deflector having a line of sight to the semi-finished glass product.

16. Device according to claim 15, wherein the furnace comprises at least one heating unit configured to bring the at least one sheet metal heat deflector to a predetermined temperature.

17. Device according to claim 15, wherein the air circulation system is configured to generate an air flow which flows behind at least part of a sheet metal heat deflector.

18. Device according to claim 1, comprising at least one positioning system configured to move the semi-finished glass product about at least one axis, within the furnace chamber.

19. Device according to claim 1, comprising at least one positioning system configured to rotate the semi-finished glass product about at least one axis, within the furnace chamber.

20. A furnace (2) configured to accommodate a semi-finished glass product (4), the furnace comprising: at least one furnace chamber (20) delimited by a wall (25); at least one opening (5) formed in a ceiling of the furnace chamber (20); at least one laser (3) configured to generate a laser beam (30); at least one movable mirror (35) configured to direct the laser beam onto one or more predetermined partial areas (40) of the semi-finished glass product (4); and a ring nozzle positioned at the opening and configured to create a sealing air flow to promote heat retention in the furnace chamber.

21. The furnace (2) according to claim 20, further comprising: at least one sheet metal heat deflector which is arranged inside the furnace chamber and covers at least part of the wall, the heat deflector having a line of sight to the semi-finished glass product.

22. The furnace (2) according to claim 21, further comprising: a transport pallet (7) having three contact points (71, 72, 73) which define a triangle and are configured to be received in an interlocking fashion in associated receiving devices (8) of the furnace chamber (20).

23. The furnace (2) according to claim 22, further comprising: at least one positioning system configured to rotate the semi-finished glass product about at least one axis, within the furnace chamber.

24. The furnace (2) according to claim 23, further comprising: at least one embossing die (6) arranged on one side of a semi-finished glass product (4) located in the furnace chamber; and at least one complementarily shaped counter embossing die (60) arranged on an opposite side of the semi-finished glass product (4).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0050] The invention shall be explained in more detail below with reference to the attached drawings without limiting the general concept of the invention, wherein

[0051] FIG. 1 shows a first embodiment of a device according to the invention.

[0052] FIG. 2 shows a schematic diagram of a second embodiment of a device according to the invention.

[0053] FIG. 3 explains the positioning of the semi-finished glass product in a first embodiment.

[0054] FIG. 4 explains the positioning of the semi-finished glass product in a second embodiment.

[0055] FIG. 5 explains the positioning of the semi-finished glass product in a third embodiment.

[0056] FIG. 6 shows a positioning aid of a transport pallet.

[0057] FIG. 7 shows the top view of a third embodiment of a device according to the invention.

[0058] FIG. 8 shows a further view of the third embodiment of a device according to the invention.

[0059] FIG. 9 shows the cross-section of a fourth embodiment of a device according to the invention.

DETAILED DESCRIPTION

[0060] FIG. 1 shows a first embodiment of a device according to the invention. The device comprises a furnace 2. The furnace 2 comprises a furnace chamber 20, which is surrounded by a wall 25. The wall can have thermal insulation in order to reduce heat losses to the surroundings. The material of the wall can comprise or consist of a metal or an alloy or a mineral material, such as fireclay or ceramics. A metal or an alloy may be provided with a heat-insulating coating comprising an oxide or a nitride, for example. In addition, the furnace 2 comprises heating units (not shown) being configured to heat the furnace chamber 20. In some embodiments of the invention, the temperature inside the furnace chamber 20 may be selected from about 400 C. to about 800 C. or from about 500 C. to about 700 C.

[0061] FIG. 1 further illustrates a semi-finished glass product 4. The semi-finished glass product may be a flat glass, for example. In other embodiments of the invention, the semi-finished glass product 4 may also have a different shape, for example be a cylinder, a sphere or have any other geometry.

[0062] An opening 5 is provided in the ceiling of the furnace chamber 20. The opening 5 may be closed by means of a movable gate valve to reduce or prevent heat losses resulting from hot air escaping from the furnace chamber 20. For this purpose, the movable gate valve may be made of or comprise a metal or an alloy or a mineral material. The gate valve can likewise be provided with a coating.

[0063] When the device is operated, the semi-finished glass product 4 is heated to a predetermined temperature below the glass transition temperature. In a subsequent method step, additional heat may be supplied to predetermined partial areas 40 of the semi-finished glass product 4. This is done by infrared radiation, which is directed to the desired partial areas 40.

[0064] In some embodiments, a laser 3 may be used to generate the infrared radiation. The laser may be a CO.sub.2 laser in some embodiments of the invention. The laser 3 generates a laser beam 30. Laser beam 30 may have a power between about 100 W and about 5000 W or between about 1000 W and about 2500 W.

[0065] In the illustrated embodiment, the laser beam 30 is directed into the interior of the furnace chamber 20 by means of a scanner 350. The scanner 350 has a movable mirror 35, which may be moved and/or rotated by actuators as known to those skilled in the art. In some embodiments, piezo actuators and/or electric motors may be used to move and/or rotate the mirror 35. In some embodiments, the mirror 35 of the scanner 350 may be controlled by a computer system 36, having a computer program stored inside that is configured to influence the position of the laser beam 31 deflected at the mirror 35 and thus selects predetermined partial areas 40 of the semi-finished glass product 4.

[0066] In order to allow the laser beam 30 to reach the interior of the furnace chamber 20, an optional gate valve is removed from the opening 5. This can cause hot air escaping from the furnace chamber 20 through the opening 5. According to the invention it is suggested to provide at least one nozzle 50 to generate a sealing air flow. The nozzle 50 may be designed as a ring nozzle in an exemplary embodiment. The sealing air flow generated by the nozzle 50 counteracts the air flow rising by convection, so that the escape of hot air from the furnace chamber 20 is at least reduced or may be completely prevented. This feature may have the advantage that the scanner 350 is exposed to a lower thermal load. In addition, the energy consumption for heating the furnace 2 may be reduced and/or the temperature distribution of the semi-finished glass product 4 may be more uniform.

[0067] Although FIG. 1 only shows a single opening 5 with a single scanner 350, some embodiments of the invention may have a furnace 2 with a plurality of openings 5 each opening 5 having associated lasers and scanners 350. This feature may have the technical effect that the area of the semi-finished glass product 4 being covered by a plurality of deflected laser beams 31 may be enlarged, so that even large semi-finished glass products may be re-shaped, for example truck windows or architectural glass.

[0068] FIG. 2 shows a second embodiment of the invention. Like features are denoted with like reference numbers, so that the following description may be restricted to the main differences. FIG. 2 shows a device 1 comprising a furnace 2. The furnace 2 has a plurality of furnace chambers 20, 21, 22 and 23. The furnace chambers are arranged relative to one another in such a way that a semi-finished glass product 4, which starts from the first furnace chamber 2, can pass continuously and sequentially through the other furnace chambers 20, 22 and 23. The furnace chambers may be kept at different temperatures so that the semi-finished glass product 4 undergoes different processing in each furnace chamber. The individual furnace chambers do not have to be structurally separate in all embodiments. In some embodiments of the invention, a single furnace chamber may be divided into different functional zones having different temperatures so that each zone forms one of the furnace chambers 20, 21, 22 and 23.

[0069] In the first furnace chamber 21, the semi-finished glass product 4 may be preheated. For this purpose, the furnace chamber may have a temperature between 250 C. and about 550 C. or between about 400 and about 500.

[0070] The semi-finished glass product 4 is then transferred to the second furnace chamber 20. This chamber may be at a temperature between about 400 and about 600. The re-shaping may be carried out by local heating using infrared radiation, as described above in connection with FIG. 1. In particular, laser radiation 30 may be used.

[0071] Alternatively or additionally, embossing dies 6 may be used, which emboss and thus reform the semi-finished glass products 4 at predetermined parts of the surface. For this purpose, the embossing dies 6 may be moved by actuators 65, for example push rods, pneumatic actuators, piezo actuators or other actuators known in the art. The embossing dies 6 may be preheated to a working temperature which is above the temperature of the semi-finished glass product 4 and/or above the temperature of the furnace chamber 20. For this purpose, the embossing dies 6 may be arranged in a part 250 of the furnace chamber 20, having a different temperature than the remaining parts of the furnace chamber 20 accommodating the semi-finished glass product 4. For example, the partial volume 250 can comprise additional heating units which may be selected from infrared radiators or resistance heaters. In other embodiments of the invention, the embossing dies 6 may be equipped with electric heating units.

[0072] In some embodiments of the invention, complementarily shaped counter embossing dies 60 may be disposed opposite the embossing dies 5. In this way, an unwanted deformation of the semi-finished glass product 4 under the action of the embossing die 5 may be avoided by applying an opposite force by the counter embossing die 6. Alternatively, the counter embossing die 6 may be configured to give the side of the semi-finished glass product 4 that is opposite the embossing die 5 a desired complementary shape.

[0073] After re-shaping has taken place, the semi-finished glass product 4 may be fed into a third furnace chamber 22, which, in turn, may have a temperature that differs from that of the preceding second furnace chamber 20. For example, the temperature of the third furnace chamber 22 may be between the temperature of the first furnace chamber 21 and the temperature of the second furnace chamber 20. In some embodiments of the invention, the temperature of the second furnace chamber 20 may be between about 200 and about 500 or between about 300 and about 400.

[0074] By storing the semi-finished glass product 4 in the third furnace chamber 22, the semi-finished glass product 4 may be cooled in a controlled way so that mechanical stress within the semi-finished glass product 4 is reduced. While the semi-finished glass product 4 undergoes a controlled cooling in the third furnace chamber 22, another semi-finished glass product may be re-shaped in the second furnace chamber 20 and a third semi-finished glass product 4 may be preheated in the first furnace chamber 21. Due to the continuous passage of the semi-finished glass products 4 through the furnace chambers 21, 20 and 22, the cycle time may be reduced and the throughput of the device 1 may be increased.

[0075] In the optional fourth furnace chamber 23, an optional shock cooling of the semi-finished glass product 4 may be carried out at a comparatively low temperature. In this way, for example, a glass article may be produced from tempered glass which, on the one hand, has a hardened surface and therefore becomes more resistant and, on the other hand, has a different fracture behavior, so that the occurrence of large, sharp-edged fragments is avoided. For this purpose, the fourth furnace chamber 23 can have a temperature between about 50 C. and 100 C., so that the semi-finished glass product may be rapidly cooled to a temperature below 350 C. However, it should be noted that the fourth furnace chamber 23 is optional and may be omitted in other embodiments of the invention. If the fourth furnace chamber 23 is used, the above described third furnace chamber 22 can have a temperature between about 650 C. and about 750 C. in preparation for thermal tempering.

[0076] In some embodiments of the invention, the device according to the invention may have a transport pallet and/or a mold being configured to move the semi-finished glass product inside the furnace chamber 20 and/or between a plurality of furnace chambers. In some embodiments of the invention, this transport pallet or mold has three contact points, said contact points configured to be positioned onto corresponding receiving devices of the furnace chamber in an interlocking manner. This allows a reproducible positioning so that the semi-finished glass product 4 is always positioned in the same relative position to the scanner 350 and/or to the embossing die 6. Thus, the same partial surfaces of the semi-finished glass product 4 are heated and/or re-shaped with high accuracy.

[0077] FIG. 3 shows a first embodiment of the contact points 71, 72 and 73 of a transport pallet. As further detailed in FIG. 6 below, the contact points 71, 72 and 73 are designed in such a way that they may be positioned exactly in two directions and may be movable in the third direction.

[0078] As an example, the corresponding receiving devices 8 of the furnace chamber may be made from a polygonal or round tube or rod. Thus, an elongated receiving device is provided to accommodate the contact points 71 and 73. These allow the transport pallet equipped with contact points 71 and 73 to be fixed in the X direction and being movable in the Y direction.

[0079] The further receiving device 82 for the contact point 72 is not arranged parallel to the first receiving device. In some embodiments of the invention, the receiving devices 8 and 82 can enclose an angle of about 60 to about 120 or about 90. The receiving device 82 allows the second contact point 72 to be moved in the X direction and fixed in the Y direction. Thus, transport pallets may be received in the furnace and positioned clearly by the interaction of the three contact points. However, transport pallets of different sizes can have different distances between the first and third contact points 71 and 72 and a different distance of the second contact point 72 from the connecting line of these first and third contact points. This allows the positioning of different transport pallets and/or molds, so that different products may be manufactures without any conversion work in the furnace chamber. Cooling of the furnace for production changeover may therefore be avoided.

[0080] Since the transport pallet is not firmly clamped at the contact points but is movable in the X and Y direction, even temperature changes, which are unavoidable when a cold semi-finished glass product on a cold transport pallet is placed in the heated furnace, cannot lead to the occurrence of mechanical stress which could endanger the dimensional accuracy of the glass component and/or lead to mechanical damage to the transport pallet and/or the furnace.

[0081] The transport pallets or the molds can rest by gravity on the receiving devices in the furnace chamber and can thus also be positioned in a clearly defined manner in the spatial direction Z orthogonal to the illustrated X and Y direction. In one embodiment of the invention, the center of gravity of the transport pallet and/or the mold may be located within the triangle defined by the contact points 71, 72 and 73. This ensures stable positioning of the transport pallet within the furnace.

[0082] FIG. 4 shows a second embodiment of the positioning unit according to the invention. Like parts of the invention are denoted with like reference numerals, so that the following description may be limited to the main differences.

[0083] As shown in FIG. 4, the receiving device 82 for the second contact point 72 is designed to be movable parallel to the receiving device 8, so that the angular relationship to the first receiving device of the contact points 71 and 73 remains unchanged. However, the receiving device 82 may be moved in a direction parallel to the first receiving device 8, so that either an adaptation to different transport pallets may be made and/or the transport pallet may be positioned and/or transported within the furnace by moving the receiving device 82. For the purpose of illustrating this feature, four possible positions of the second receiving device 82 are shown.

[0084] FIG. 5 shows a third embodiment of the positioning unit according to the invention. Like parts of the invention are denoted with like reference numerals, so that the following description may be limited to the main differences.

[0085] The third embodiment uses three receiving devices, 81, 82 and 83 arranged within the furnace chamber 20, which each engage in corresponding contact points 71, 72 and 73. The three receiving devices are again designed as elongated elements, which may have a polygonal or round cross-section, for example.

[0086] The longitudinal axes of the receiving devices enclose an angle of 120 relative to each other. Due to the longitudinal extension, transport pallets and/or molds of different sizes or with different distances between the receiving devices may be received without the need for conversion work. Nevertheless, the positioning unit allows a reproducible positional relationship of the transport pallet equipped therewith to the other units of the furnace, for example a scanner 350. This constant positional relationship includes both angle and location.

[0087] FIG. 6 shows a cross section of a segment of a transport pallet 7 with a contact point 71 and a receiving device 8. In the illustrated, highly simplified exemplary embodiment, the transport pallet 7 is a plane-parallel plate comprising a metal or an alloy or a ceramic material, for example. Optionally, the transport pallet 7 may be provided with a coating (not shown) which prevents the semi-finished glass product 4 from sticking and/or increases the temperature resistance.

[0088] On the side of the transport pallet 7 that is opposite the semi-finished glass product 4, a contact point 71 is shown, which has a polygonal cross-section. The illustrated cross-section is obtained by inserting an approximately V-shaped groove into a cuboid base body. The groove may have a flattened base.

[0089] The corresponding receiving device 8 comprises a rod or tube with an approximately circular outer cross-section. Due to the weight of the transport pallet 7, the V-shaped groove of the contact point 71 lies on the receiving device 8 in such a way that it rests on two dedicated contact points or contact lines 711 and 712. This results in a defined positioning in both the X direction and the Z direction which is orthogonal thereto.

[0090] In cooperation with other receiving devices and contact points, precise positioning can thus be achieved in all three directions and all three directions of rotation, as explained above with reference to the FIGS. 3 to 5.

[0091] FIG. 7 shows the top view on a furnace chamber 20, which is delimited by a wall 25. Inside the furnace chamber 20, four embossing dies 6 are located, which are arranged in a rectangular array concentrically around the target point of a laser beam 30.

[0092] FIG. 7 illustrates further a semi-finished glass product 4 having an approximately rectangular shape. The semi-finished glass product 4 may be moved within the furnace chamber 20. Five possible positions are indicated in FIG. 7. As will be understood, the semi-finished glass product 4 may be brought, for example, into a position allowing all four embossing dies 6 to act simultaneously or sequentially on the semi-finished glass product 4, thereby reaching any point of the semi-finished glass product. In other embodiments of the invention, the semi-finished glass product 4 may be moved under the laser beam 30 in such a way that predetermined partial surfaces are sequentially heated by the laser beam 30 in order to re-shape the glass product. Due to the movement of the semi-finished glass product 4 within the furnace 2, the use of a scanner 350 may be avoided and a relative movement between the laser beam 30 and the semi-finished glass product 4 can nevertheless be realized.

[0093] FIG. 8 shows a further view of a furnace 2 as part of a device 1 according to the present invention.

[0094] FIG. 8 illustrates a top view of the bottom of a furnace chamber 20 of a furnace 2, which is delimited by a wall 25. FIG. 8 illustrates a mechanism configured to move the semi-finished glass product 4 within the furnace chamber 20. It consists of two receiving devices 85, which are arranged approximately parallel to each other. These receiving devices may be moved in two axes so that the semi-finished glass product 4 may be positioned within the furnace chamber 20. This feature allows the semi-finished glass product 4 to be moved into the operational range of the embossing dies 6 and/or a laser beam (not shown in FIG. 8). The semi-finished glass product may also be moved to different temperature zones, e.g. to carry out optional method steps of preheating, re-shaping or tempering.

[0095] FIG. 9 illustrates a cross-section through a furnace 2 according to a fourth embodiment of the invention. Like parts of the invention are denoted with like reference numerals, so that the following description may be limited to the main differences.

[0096] Again, a furnace chamber 20 is shown, in which a semi-finished glass product 4 is accommodated. The furnace 2 is designed as a circulating air furnace, i.e. a heating unit (not shown) heats the furnace air and feeds it to the furnace chamber 20 as an air flow 265 by means of a blower unit. The air flow 265 may allow for a more homogeneous and uniform heating of the semi-finished glass product 4.

[0097] Additionally, a line of sight 45 between individual partial areas of the semi-finished glass product 4 and the furnace walls 25 exists. This results in an additional exchange of radiant heat between the semi-finished glass product 4 and the wall 25 of the furnace chamber 20. Of course, the two lines of sight 45 illustrated in the figure are only to be understood as exemplary. In fact, there is a plurality of such lines of sight between individual partial areas of the semi-finished glass product 4 and respectively associated partial areas of the wall 24 of the furnace chamber 20.

[0098] If the wall 25 has a lower temperature than the semi-finished glass product in the furnace chamber 20, the exchange of radiant heat leads to a cooling of the semi-finished glass product 4. This may prevent a homogeneous heating of the semi-finished glass product 4.

[0099] According to the invention, it is suggested to place at least one sheet metal heat deflectors 255 inside the furnace chamber 20, which may be brought to a higher temperature than the wall. The sheet metal heat deflectors 255 may be heated, for example, by additional electric or gas-operated heating units. In other embodiments of the invention, the hot air flow 265 may be used for rear ventilation of a sheet metal heat deflector, so that they can absorb heat from the hot air flow 265. In this way it may be ensured that the half-space surrounding the semi-finished glass product 4 exchanges radiant heat evenly with the semi-finished glass product, so that non-homogeneous cooling or heating of the semi-finished glass product 4 is avoided. Thus, it is possible to get a better control of the temperature distribution of the semi-finished glass product 4 due to the controlled exchange of radiation between the semi-finished glass product and the inner walls of the furnace chamber. In some embodiments of the invention, all sheet metal heat deflectors 255 inside the furnace chamber 20 may have the same temperature. In some embodiments of the invention, this temperature may be equal to the temperature of the air in the furnace chamber 20.

[0100] It is noted that, the invention is not limited to the illustrated embodiments. The above description should not be regarded as restrictive but as explanatory. The following claims are to be understood in such a way that a cited feature is present in at least one embodiment of the invention. This does not exclude the presence of further features. Insofar as the claims and the above description define first and second embodiments, this designation serves to distinguish between two similar embodiments without determining an order.