TECHNICAL FIELD

[0001] The present disclosure relates generally to a glass bending machinery, it particularly relates to an improved apparatus for bending of glass sheet and a method thereof.

BACKGROUND

[0002] Background description includes information that may be useful in understanding the present disclosure. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed disclosure, or that any publication specifically or implicitly referenced is prior art.

[0003] Curved or bent sheets of glass are commonly used in the field of automotive such as a front or rear windshield of a vehicle. Generally, glass shaping or bending of glass sheet into curved structure is done with the help of some special purpose tools or machine. The complex bending of the glass sheet is being done by means of much complex tools capable of providing the desired shape of the glass. The glass shaping takes place by heating the glass sheet to a high temperature such that the glass is then viscoelastic in nature, thereby making the process of shaping the glass easy. During the shaping process, the desired shape of the glass is provided by a punch from a bending tool. This punch imparts the glass sheet the required shape.

[0004] Reference is made to FIG. 1 A that provides an overview of the glass sheet bending process in a manufacturing line as known in the art. It includes three main units, commencing with the furnace 102 in which the glass sheets 104 are heated to a viscoelastic state, followed by the bending station or unit 106 where it would be bent and given a desired shape and further into the quenching station 110 where the now hot bent glass sheets 104 are cooled. The transport of the glass sheets from one unit to another is mostly by means of rollers. It would be appreciated by one skilled in the art that there are multiple other units present along these units and the diagram is to merely present an understanding of a glass bending apparatus.

[0005] Glass is shaped (or bent) by way of special purpose machine which constitutes of various elements including and not limited to elements such as a male member (generally termed to as ‘form’), pressing ring and rollers. This form in general is a solid metallic element which is manufactured in accordance to a glass sheet size which is to be bent. The curved surface in the form is mostly machined and being used for glass shaping. The form is fixed on the top side of said special purpose machine and corresponding female member is placed on the lower half of the machine. There are two main purpose of the tool which includes member for shaping the glass surface and additionally to hold it for transferring to the next station. The glass is taken from the furnace at elevated temperature and is placed in the tool for bending operation. The bending takes place by combination of gravity sagging and also by the tool form surface. During the bending operation, the top and bottom assembly closes with glass placed in between and bending occurs by the reflecting the profile from two members the form and the ring. On bending, the glass is lifted along with the top half by suitable suction means which lifts the glass along with the top half of said special purpose machine. The form has series of suction holes made all across the surface which is machined/drilled and connected to a central suction unit of the bending machine. This suction holes exerts smaller suction zones all across the glass surface and on bending, the glass the suction force is activated which causes the glass to lift along the top half. This glass lifted is being transferred by placing it on the transportation shuttle which further carries for the further glass conveying.

[0006] Reference is made to a US6321570 that discloses a method of bending and tempering a sheet of glass having a perimeter and a central portion. The pressing member of the apparatus disclosed therein includes a conformable pressing element which permits a manifold to be positioned between the rigid mold and the pressing member to direct a gas to cool the heated sheet of glass during bending. Further, the rigid mold and a conformable pressing element of the apparatus may each include a cover to increase the heat transfer from the heated sheet to the bending and tempering apparatus. Furthermore, the covers may have increased thermal conductivity in their peripheral regions for increased cooling of the edge of the sheet of glass.

[0007] Again, reference is made to US20120055197 that discloses a device for bending sets of superposed sheets of glass. Said device includes a first convex top form including first means for generating a first suction, creating an upward airflow blowing over a rim of the sheets, the first suction being sufficient to lift and hold the superposed sheets against the first top form. Further, said device includes a bottom solid concave mold including openings on its main face and means for generating a second suction through the openings. The top form and the bottom mold have complementary shapes and are configured to move toward one another along a vertical axis to press the sheets of glass. [0008] Another reference is made to US20170210663 that discloses a bending tool for bending at least one glass pane by means of suction. Said bending tool comprises a frame-like, convex contact surface and a cover having a peripheral air guide plate that surrounds the convex contact surface at least in regions. The bending tool is configured to generate a first, reduced pressure in a first pressure region between the peripheral air guide plate and the convex contact surface, and a second, reduced pressure in a second pressure region. The tool is configured such that the second pressure is less than the first pressure, and a third pressure in a third pressure region, such that the third pressure is greater than the first pressure.

[0009] In the prior art solutions, the punch or the members or shaping element that facilitate the glass bending are mostly solid entity with shaping element similar to the glass size and the bending of the glass into desired shape would require maximum surface area of the glass sheet coming in contact with said bending tool or element, thereby increasing the chance of occurrence of defects especially because during the time of bending the glass sheet is viscoelastic in nature. The punch rework is difficult and needs complete replacement in case of any damage. The tools known from the prior art solutions are complex in regard of the construction of the tool since there are too many components to be integrated. Further, such conventional punch is considerably heavier due to it being composed of denser material which can result in higher energy consumption during the bent glass sheet forming operation. As a result, when a repair or any sort of rework is needed on the punch in case of damage or the like, a complete replacement would be required and by part working may not be possible. The manufacturing or the maintenance cost of the mold adds as overhead to the manufacturing cost of glazing, especially for glazing with lower volumes since it is not cost effective.

[0010] In view of the prior art solutions disclosed hitherto, there is a requirement for an improved cost effective and simplified glass bending tool or apparatus having minimized surface area such that it facilitates the bending process with minimal contact on the glass sheet.

SUMMARY OF THE DISCLOSURE

[0011] An object of the present invention is to provide an improved solution overcoming the drawbacks of the prior art.

[0012] Another object of the present invention is to provide a simple, easy to handle and maintain, cost effective glass bending tool for a glazing manufacturing line. [0013] Yet another object of the present invention is to provide a glass bending tool for a glazing manufacturing line having minimized surface area such that the contact points on the glass surface is minimized.

[0014] Still another object of the present invention is to provide a glass bending tool for a glazing manufacturing line capable of optimizing the bending process to an improved level with fine-tuned suction pressure being exerted for glass bending.

[0015] A further object of the present invention is to provide a glass bending tool for a glazing manufacturing line capable of withstanding the structural load during the glass sheet shaping process.

[0016] A further object of the present invention is to provide a glass bending tool for a glazing manufacturing line capable of bending the glass sheet with optimal force on the glass sheet.

[0017] These and other objects of the invention are achieved by the following aspects of the invention. The following disclosure presents a simplified summary of the invention in order to provide a basic understanding of some aspects of the invention. This presents some concept of the invention in a simplified form to a more detailed description of the invention presented later. It is a comprehensive summary of the disclosure and it is not an extensive overview of the present invention. The intend of this summary is to provide a fundamental understanding of some of the aspects of the present invention.

[0018] In an aspect of the present invention is disclosed an apparatus for bending or shaping and lifting at least one glass sheet. The apparatus comprises a top unit and a bottom unit. The top unit further comprises an arrangement of one or more rings with said rings having plurality of suction holes on them at predetermined locations and the arrangement being configured for shaping the at least one glass sheet and for lifting said glass sheet for releasing it onto a transportation unit to a next station in a manufacturing line, wherein said suction holes are adapted to apply optimal pressure for bending and lifting the glass. It further includes a frame placed over the arrangement of the one or more rings adapted to hold the arrangement and to attach said arrangement with an installing member of a bending station and a screw set up capable of adjustably attaching said arrangement of the one or more rings to the frame. The number of rings, the number of suction holes on the one or more rings and the predetermined locations of holes on the ring, the shape of each of the rings and the pressure to be applied through the suction holes are based on one or more parameters of the glass sheet. [0019] In another aspect of the present invention is disclosed a method for glass bending in manufacturing of an automotive glazing. The method comprises heating a glass sheet in a furnace at around a bending temperature; optionally pre-bending the glass sheet by means of bend rollers and/or by gravity sagging; placing and focalizing the glass sheet on a bottom unit of a bending station, such that the glass sheet is brought in contact with an apparatus for bending or shaping it, in which said apparatus is one disclosed in the above aspect; shaping the glass sheet by pressing a top and bottom surfaces of the glass sheet; lifting and holding the glass sheet by said apparatus by application of pressure and the bottom unit recede to prepare for glass sheet transfer to a next station; and transferring the glass sheet to a transportation shuttle unit for tempering process; or transferring the glass sheet for lamination process.

[0020] This invention provides a simpler tool or apparatus for glass bending. The disclosed solution overcomes the complexities of the bending apparatus or tool of prior art and provides much effective functionalities from manufacturing perspectives. The ring arrangement is much simpler in construction as there is only a thin metal band being used on the peripheral portion of the glass. The ring element only interfaces with the glass on the peripheral area which is not critical with respect to optical quality as compared to the portion in the middle. The waviness in the final bent glass is reduced using the disclosed apparatus, since the minimal areas of the bending apparatus are in touch with the glass.

[0021] The significant features of the present invention and the advantages of the same will be apparent to a person skilled in the art from the detailed description that follows in conjunction with the annexed drawings.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

[0022] The following briefly describes the accompanying drawings, illustrating the technical solution of the embodiments of the present invention or the prior art, for assisting the understanding of a person skilled in the art to comprehend the invention. It would be apparent that the accompanying drawings in the following description merely show some embodiments of the present invention, and persons skilled in the art can derive other drawings from the accompanying drawings without deviating from the scope of the disclosure.

[0023] FIG. 1A illustrates an overview of the glass sheet bending process in a manufacturing line as known in the art; [0024] FIG. IB illustrates an exemplary embodiment of a tool or punch for bending glass according to prior art;

[0025] FIG. 2 illustrates an apparatus for bending or shaping and lifting at least one glass sheet, in accordance with an embodiment;

[0026] FIG. 3 illustrates a configuration of a top unit, in accordance with an embodiment;

[0027] FIG. 4A illustrates an apparatus for bending or shaping and lifting at least one glass sheet, in accordance with an embodiment;

[0028] FIG. 4B illustrates a top view of an apparatus for bending or shaping and lifting at least one glass sheet, in accordance with an embodiment;

[0029] FIGs. 5A-5C illustrates the application of negative pressure on the glass sheet for different bending profiles;

[0030] FIG. 6 illustrates the construction of an apparatus for bending or shaping and lifting at least one glass sheet, in accordance with an embodiment;

[0031] FIG. 7 illustrates a configuration of the ring structure, in accordance with an embodiment;

[0032] FIG. 8 illustrates a concentric arrangement of the rings, in accordance with an embodiment;

[0033] FIG. 9 illustrates an arrangement of the ring including a zonal ring, in accordance with an embodiment;

[0034] FIG. 10 is a free-body diagram illustrating the forces acting on the glass sheet during the bending process; and

[0035] FIG. 11 is a flowchart illustrating the method of bending and lifting the glass sheet, in accordance with an embodiment.

[0036] Persons skilled in the art will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the disclosure.

DETAILED DESCRIPTION [0037] The present disclosure is now discussed in more detail referring to the drawings that accompany the present application. It would be appreciated by a skilled person that this description to assist the understanding of the invention but these are to be regarded as merely exemplary.

[0038] The terms and words used in the following description are not limited to the bibliographical meanings and the same are used to enable a clear and consistent understanding of the invention. Accordingly, the terms/phrases are to be read in the context of the disclosure and not in isolation. Additionally, descriptions of well-known functions and constructions are omitted for clarity and conciseness.

[0039] In a general manufacturing line such as the one shown in FIG. 1A , the bending tool 108 of the apparatus in the glass bending station 106 is in full form, implying that it is usually a solid tool with means for application of pressure for facilitating the bending and shaping of the glass sheet. An exemplary embodiment of such a tool or punch 108 has been depicted in FIG. IB. The existing full form of the tool is capable of performing multiple functions such as bending the glass or glass sheet, suction of the glass with a top half of the apparatus, hold the glass and transferring it to a next station such as a quench station. The conventional tool 108 defines suction holes 112 throughout the entire surface of the tool 108. Therefore, the tool 108 makes contact with the entire surface of the glass sheet for bending and lifting the glass sheet. This is highly undesirable and may result in undulations on the surface of glass sheet because of the increased area of contact between the tool 108 and the glass sheet. The transfer of the glass sheet from one station or unit in the manufacturing line to another is usually next quench shuttle, where the glass sheet may be cooled or further processed for lamination or tempering. The solutions known from the prior art are full form type tool and the punch which provides the shape to the glass considerably increases the cost of the manufacturing tool, and its maintenance as well. This invention mainly focuses on reducing the cost involved in making the tools by providing an alternate design by modifying the form for the tool member.

[0040] FIG. 2 illustrates an apparatus 200 for bending or shaping and lifting at least one glass sheet, in accordance with an embodiment. The apparatus 200 may comprise a bottom unit 204 and a top unit 202. The bottom unit 204 may be configured to receive the glass sheet 206 to be bent from the furnace. The top unit 202 may comprise an arrangement of one or more rings 208, a suction unit 306 (refer FIG. 3) and a plurality of hoses 304 (refer FIG. 3).

[0041] Referring to FIG. 3, the one or more rings 208 may define a plurality of suction holes 302 at predetermined locations. Further, each of the plurality of hoses 304 may be connected between one among the plurality of suction holes 302 and the suction unit 306. Therefore, the suction unit 306, when operated, causes a negative pressure at the suction holes 302 of the rings.

[0042] During operation, the glass sheet 206 from the furnace may be received by the bottom unit 204. The glass sheet 206 may be in a viscoelastic state. Further, the bottom unit 204 with the glass sheet 206 may move towards the top unit 202. Upon the bottom unit 204 getting in proximity to the top unit 202, the suction unit 306 may be operated. The suction unit 306 may exert negative pressure on the glass sheet 206 via the suction holes 302. The negative pressure may cause the glass sheet 206 to bend, wherein the peripheral portion of the glass sheet 206 may come in contact with the ring 208 by the action of the negative pressure. Further, the glass sheet 206 may be lifted by the top unit 202 and transferred to a subsequent station.

[0043] In an implementation, the ring 208 may be configured to apply pressure by means of vacuum suction on the peripheral portions of a glass sheet for bending and lifting the glass sheet. The glass sheet may be for instance and not limited to a glass for glazing like windshield, backlite, quaterlite, sidelite, sunroof and any other curved glass. The apparatus may be used for any type of glass such as tempered, annealed, laminated, non-laminated and the so on.

[0044] FIG. 4A illustrates an apparatus 400 for bending or shaping and lifting at least one glass sheet 206, in accordance with an embodiment. The apparatus 400 may comprise a bottom unit 402 that may be configured as a ring-like structure. Such a configuration may cause the glass sheet 206 to partially bend during the movement of the bottom unit 402 towards the top unit 202 because of the weight of the glass sheet 206 acting on the central portion of the glass sheet. Further, the full bending of the glass sheet 206 may be accomplished upon operating the top unit 202 to apply negative pressure on the glass sheet 206 via the suction holes 302.

[0045] FIG. 4B illustrates a top view of an apparatus 400 for bending or shaping and lifting at least one glass sheet 206, in accordance with an embodiment. As can be seen, the ring 208 is configured to interface with only the peripheral portion of the glass sheet 206 thereby minimizing the area of contact between the ring 208 and the glass sheet 206. This reduction in the contact area in turn reduces the deformations and undulations caused during the bending of the glass sheet as compared to the conventional bending tool.

[0046] In an embodiment of the present invention is disclosed the bending apparatus not preferred for sag bending in which the bending of the glass takes place as a result of gravity. In the disclosed invention, the curved profile of the glass is attained by actively forming the heated glass, in which suction produced by the vacuum unit is exerted on the glass sheet and the shaping of the glass is done by the ring arrangement. This is followed by lifting the glass with the top unit of the apparatus. The arrangement of one or more rings has to lift the glass which was lifted by having the complete full surface form in prior solutions. The suction holes are evenly distributed all across the form in case of the full surface as there is much material to have provision evenly on all across the glass surface. This not only increases the amount of pressure on the glass but also increases the number of contacts on the glass surface and the bending tool apparatus or apparatus, thereby increasing the chance of occurrence of defects.

[0047] The plurality of suction holes 302 may be adapted to apply optimal pressure for bending and lifting the glass. In an implementation negative pressure may be applied by way of vacuum suction. The number of rings, the number of suction holes on the one or more rings and the predetermined locations of holes on the ring, the shape of each of the rings and the pressure to be applied through the suction holes may be based on one or more parameters of the glass sheet.

[0048] According to an embodiment of the present invention is disclosed that the ring form has the peripheral profile similar to that of the desired bent glass profile or the desired curved profile of the glass. This peripheral profile of the ring may provide the glass, which would be in viscoelastic state, the final intended bent shape or curved shape. Besides, shaping the glass sheet, the shape and the peripheral profile of the ring may also help in lifting up the glass with the top unit of the apparatus by using suction pressure provide from the top unit of the apparatus

[0049] In an exemplary embodiment of the present invention, the plurality of suction holes (104) for lifting the glass is only present at pre-determined locations of the ring preferably on the peripheral portion of the ring. The number of rings, the number of suction holes on the one or more rings and the predetermined locations of holes on the ring, the shape of each of the rings and the pressure to be applied through the suction holes (104) are based on one or more parameters of the glass sheet such as at least weight, width, thickness, surface area of the glass, optical requirements and a required curved profile. In an implementation of the invention, the thickness of the glass sheet to be bent is at least 0.8 mm.

[0050] FIGs. 5A-5C illustrates the application of negative pressure on the glass sheet 502 for different bending profiles. As can be seen, a first bending profile 504 has a prominent curvature, a second bending profile 506 has a lesser prominent curvature than the first bending profile 504, and a third bending profile 508 has a lesser prominent curvature than the second bending profile 506.

[0051] As an example, the pressure required to bend the glass sheet 502 to the first bending profile 504 may be Pl a, P2a and P3a. The pressure required to bend the glass sheet 502 to the second bending profile 506 may be Plb, P2b and P3b. Similarly, the pressure required to bend the glass sheet 502 to the third bending profile 508 may be Pic, P2c and P3c.

[0052] The pressure required for bending the glass sheet to different bending profiles is in the order of,

Pla>Plb>Plc; P2a>P2b>P2c; P3a>P3b>P3c

[0053] Therefore, the pressure may be varied based on the bending profile of the glass sheet.

[0054] FIG. 6 illustrates the construction of an apparatus for bending or shaping and lifting at least one glass sheet, in accordance with an embodiment. In an implementation of the invention, the ring 208 may be provided with a cross member 606. The cross member 606 may provide structural rigidity to the ring 208.

[0055] Said apparatus comprises an arrangement of one or more rings 208. The bending may be applicable for regular and deep bend glasses of minimum radius of 500 mm or less, however not limited to said radius. The apparatus may include an installing member 608 configured for affixing it on a bending station. The installing member 608 includes an assembly plate member 616 to attach the arrangement of one or more rings 208 in the bending station. It further comprises a distributor plate (610 for enabling vacuum suction and further adapted for enabling cooling of the arrangement. The installing member 608 may have a closing plate 612 for sealing together plurality of attaching means 614 of the installing member 608. The attaching means 614 may be and not limited to holes and screws or means for clamping the plates and holding them together. The apparatus may further include a frame 602 placed over the arrangement of the one or more rings 208 adapted to hold the arrangement and to attach said arrangement with an installing member 608 of a bending station. Coupling members 604 are provided in the apparatus which is adapted for adjustably attaching said arrangement of the one or more rings 208 to the frame 602. By way of usage if the ring arrangement with the frame loosens, then said coupling members 604 are used further for fastening the ring arrangement with the frame. The arrangement of one or more rings 208 are configured for shaping at least one glass sheet and for lifting said glass sheet for releasing it onto a transportation unit to a next station in a manufacturing line. The transportation unit may be shuttle structure comprising rollers capable of transferring the glass sheet from one station to another in the manufacturing line.

[0056] The profiled peripheral ring 208 is attached through the coupling members 604 to the frame 602 and provided for support for specific applications. The installing member 608 is mostly common for a specific bending station set up. The ring arrangement 208, the coupling members 604 and the frame 602 is dependent on the desired curved profile of the glass. In an implementation of the present invention, for the suction, vacuum may be taken from the distributor plate 610 to the holes 302 in the ring through one or more flexible pipes or tubes or hoses. Said flexible hoses 304 may be permanently fixed in the distributor plate 610 and is configured to be locked at the holes 302 during production and it may then be removed and fixed to the hole in another arrangement for bending for another production process. Since only the coupling members 604, the frame 602 and the one or more ring 208 arrangement are adjustable as per the specifications of a glass and do not involve complex configurations or arrangements. However, with the full form solid bending tool or mould of the prior art involved complex re-arrangement and is difficult to replace as per glass specifics. Consequently, the cost involved for production also increases. But with the apparatus of the present invention, multiple bent glass may be efficiently produced with cost-effectiveness by making adjustments on said adjustable parts only.

[0057] FIG. 7 illustrates a configuration of the ring 700, in accordance with an embodiment. The ring defines suction holes defined at predetermined zones 702, 704 and 706.

[0058] The parameters of the ring and the further arrangement of the ring varies accordingly with respect to the complexity of the glass to be bent. The more complex the bending, there are additional rings provided at the centre portion to provide the improved bending capacity.

[0059] FIG. 8 illustrates a concentric arrangement 800 of the rings, in accordance with an embodiment. The rings may be arranged in concentric form 800 with the suction holes 302 on each of the rings being distributed uniformly throughout the ring or the suction holes 302 being disposed on specific zones of the ring for shaping and lifting the glass sheet. This advantageously facilitates for easy addition or removal of means for suction depending on the complexity of the glass thereby making the tool more modular. Further, the ring arrangement in concentric form 800 also provides flexibility in selecting the pressure to be exerted in each rings or each suction holes. The apparatus is configured to lift the glass sheet with minimal contact on the sheet and with optimal pressure distributed via the plurality of the suction holes. [0060] The ring only interfaces with the glass on the peripheral area of the glass sheet. From an application perspective in automotive glazing peripheral area of glass sheet may not be critical with respect to optical quality as compared to the portion in the middle of the glass. The peripheral ring on contact with the glass provides the shape of the glass at the periphery and the other centre curvature is obtained by sagging on the lower ring element or in case of complex bend by having additional concentric form rings inside, the bending curvature is being achieved. In such cases, the suction pressure in the outer ring is considerably higher than that of the other rings facilitating the lifting of the glass with the top unit of the apparatus.

[0061] In one embodiment, the suction holes 302 may either be uniformly distributed with a pitch in the range between 40-100 mm or disposed in accumulation in one or more substantially spaced zones and is so distributed to avoid sagging of the glass sheet. The diameter of each suction hole may be at least 1 mm to 10 mm.

[0062] The weight of the glass is directly proportional to the thickness of the glass. Therefore, for thick glass the pressure required to lift the glass is higher. However, increasing the pressure on specific suction holes may not be feasible as it might lead to other possible defects in the glass such as deformation in local zones. This deformation is minimized by providing additional rings especially in the centre of gravity of the glazing where the sagging is exponentially higher.

[0063] In an embodiment of the invention, the one or more rings may include a plurality of sensors configured for measuring parameters for assessing the performance of the apparatus. This may be regarded as further optimization of the apparatus. The one or more sensors may be configured to measure multiple parameters such as temperature, pressure etc. The data obtained from these sensors are critical as the values obtained are to closely monitor the performance. The tool performance is directly reflected on the glass being produced out from the apparatus. Any variations from the standard process parameter will result in the variation of the output with respect to the glass outcomes.

[0064] In an implementation, a temperature sensor may be placed close to the surface in contact with glass and a pressure sensor may be placed at the areas on ring closer to the holes to detect leakage of pressure. The incorporation of sensors on the apparatus improves the reliability of the apparatus.

[0065] The pressure gauge or sensor mounted in the concentric ring arrangements helps in regulating the necessary pressure to be exerted on each ring in such a way that apparatus is much more optimized with respect to the bending process. Further, in the event of occurrence of any sudden increase in temperature at certain location of the rings, with the location of sensors on the ring, the parameters affecting the stability of the apparatus are closely monitored. The data thus obtained from the sensors assists in responding to such constraints and appropriate action can be taken to respond to it. The inclusion of one or sensor for gauging critical parameters of the working of the apparatus thus helps in online or in-situ monitoring of the working of the apparatus and consequently, the quality of glass being produced from the apparatus is monitored, thereby increasing the quality level of the bent glass being produced.

[0066] In an implementation of the invention is disclosed that the number of concentric rings in the arrangement is dependent on contour of the curved profile of the glass sheet. The solid bending tool of the prior art is now replaced with one or more rings (and in a concentric rings arrangement in case of requirement). For every 300 mm width of a glass sheet, 1 concentric ring is required. Thus, the number of concentric rings (n) is given by, n=width of the glass sheet (in mm)/300.

[0067] This concentric arrangement greatly reduces the complexity and cost involved of the bending apparatus as compared to its prior art.

[0068] FIG. 9 illustrates an arrangement of the ring 900 including a zonal ring 906, in accordance with an embodiment. The arrangement of the ring 900 may include a zonal ring 906 in applications where the tolerances are tight at specific zones. As an example, in HUD glass, in certain regions the optic requirements are higher and in turn the tolerances may be tight during bending. In such cases, the zonal ring 906 may be provided at the zones where the tolerances may be tight to ensure that the optical requirements are met.

[0069] In an implementation of the present invention a comparative study is performed between the regular full surface form of bending tool as known in prior art that includes the suction holes distributed all across and the form ring with holes on the peripheral portion of the glass as disclosed in the present invention. In order to find the required lifting pressure, the various forces acting over the glass are considered. The forces included the weight of the glass, suction force exerted for holding and ambient pressure. The ambient pressure is also considered as the surrounding pressure can also result in variation of the performance of the bending apparatus. Reference is made to FIG. 10 that further depicts a free body diagram of the various forces acting on the glass sheet. The suction forces S 1 and S2 act upward while the weight of the glass W and ambient pressure A act downward on the glass. [0070] Table 1 (a) and Table 1 (b) provided below depicts the calculation on the net holding weight acting on the glass and the required suction pressure needed to lift the glass to attain a desired curved profile. This calculation is also done by comparing the bending tool with the regular full form and the ring type structure disclosed herein. In this specific example considered, the regular full form consists of about 200 number of suction holes were compared with the ring structure containing about 43 number of suction holes.

Table 1 (a): Calculation of the net holding force for both regular full form bending tool and ring structured bending tool

Table 1 (b): Comparative table for suction force on full form bending tool and ring structured bending tool

[0071] As would be apparent from the calculations made above, the suction pressure exerted on the form ring is different from that of the regular full surface form bending tool. Further, the lifting of the glass is also enhanced by providing suction point only at certain locations of ring structure, thereby minimizing the contacts of the glass structure and the bending tool. The ring structure of the present invention is capable of providing the same lifting of glass but with minimal contact. Reference may be made to the zonal arrangement of the holes in which by three areas contact the pressure is distributed at the suction orifices holes for lifting the glass. With this, the orifices connected to a vacuum unit sometimes a central vacuum unit is adapted to provide sufficient suction pressure that overcomes the net force acting on the glass and thereby helping in lifting the glass with the top half of the bending tool or apparatus. The form rings arranged can be of any number and sometime can even be one single unit depending on the complexity of the curved profile of the glass.

[0072] In an implementation of the present invention, the peripheral ring in contact with the glass provides the shape of the glass at the periphery and the other center curvature may be obtained by sagging on the lower ring element or in case of complex bend by having additional concentric form rings inside, the desired bending curvature may be obtained. In some cases, the suction pressure in the outer ring is considerably higher than that of the other rings and thereby the lifting of the glass with the top half is achieved. [0073] In an embodiment of the present invention is disclosed a method for glass bending in manufacturing of glazing such as that of an automotive glazing. FIG. 11 is a flowchart 1100 illustrating the method of bending and lifting the glass sheet, in accordance with an embodiment. At step 1102, a glass sheet may be heated in a furnace at around a bending temperature. The bending temperature ranges of the glass sheet may be like around 300-580 °C. The glass comes out of the furnace at a temperature of over 600 °C. The glass sheet may optionally be pre-bend. The pre-bending may be performed by means of and not limited to bend roller and/or by gravity sagging.

[0074] Further, at step 1104, the glass sheet may be placed and focalized on a bottom unit of a bending station. The bottom unit is some means such as one having rollers or some simple holding provisions for supporting the glass for being placed. The glass sheet placed, is brought in contact with the apparatus for bending or shaping it.

[0075] At step 1106, shaping the glass sheet may be performed by pressing a top and bottom surfaces of the glass sheet using the top unit and the bottom unit of the apparatus.

[0076] At step 1108, the top unit may exert negative pressure on the glass sheet via the suction holes to bend the glass sheet as per the required profile.

[0077] At step 1110, the glass sheet may be held by the ring by the vacuum and the bottom unit may recede to prepare for glass sheet transfer to a next station.

[0078] At step 1112, the glass sheet may then be transferred to a transportation shuttle unit for tempering process or the glass sheet is transferred for lamination process. For lamination, two consecutive glasses may be assembled with an interlayer in a room, and is further processed for deairing to remove air trapped between the layer using vacuum. The lamination process may then be followed by an autoclave process.

[0079] As indicated, in the existing solutions for glass bending tools or apparatus’, there are lot many challenges with respect to tool complexity, cost, weight of the tool etc. The disclosed solution overcomes these limitations and is much effective in terms of its functional as well as manufacturing perspectives. The smaller ring structures are much simpler in construction as there is only a thin metal band being used on the peripheral portion for shaping the glass. The ring element only interfaces with the glass on the peripheral area of the glass mostly or at some specific areas only. The peripheral hood type of design discussed in the prior art is complex in terms of tool construction and therefore possibilities of suction air leakage is higher and moreover there are different pressure zones defined. The control of pressure at each specific area of the glass is complex as there can be very lesser chance to identify the same. This invention overcomes such complexity by providing a simpler tool intended to do similar function as of the full form tool. The disclosed apparatus is capable of being able to perform in elevated temperatures, is made of metal, has the ability to withstand the structural load during shaping of glass, is easy in terms of machinability, is easy to assemble, is lower in cost, is easy to handle the tool and is economical as well (with at least 30% cost saving). Manufacturing process of the bending mold or apparatus or tool in case of conventional bending tool involves complex machining steps whereas the present bending ring structure can be done by simple method like even hand bending or hammering or the like. Hence, the manufacturing of the tool is simple and economical. The maintenance of the apparatus disclosed herein also easy, and cost-effective. With the present apparatus, the cooling channel is not requirement as opposed to the conventional bending apparatus that uses aluminium which has to be maintained at certain temperature, for that, cooling channels are integrated within the rectangular block. In the present invention the ring structure may also be of stainless steel which has high temperature tolerance and any metal which has high temperature tolerance can be used and the requirement of cooling channel may thus be eliminated. The optical quality of glass formed is better with the present invention since the waviness gets reduced because only minimal portion of the glass surface is in contact with the bending apparatus.

[0080] Some advantages of the present invention are enlisted in the following:

• The manufacturing cost of the glass bending apparatus gets reduced. The punch is lighter as compared to the heavier punch disclosed in prior art references. This further results in reduced energy consumption during forming operation. The maintenance and punch rework is easy in the event of repair or replacement.

• The solid bulky bending tool of the prior art involved complex manufacturing constructs and for every specification of the glass, it need to be constructed as per the required curved profile of the glass. Further, the repair or maintenance of such tools were cost-driven as well. But the herein disclosed tool is simple and thus cost-effective as opposed to complex tool of prior art.

• Better quality bent glasses are produced as compared to the ones produced from the conventional apparatus at least since the waviness gets reduced because only minimal portion of the glass surface is in contact with the bending apparatus.

• The usage of the disclosed apparatus provides economic benefits with at least 30% of reduction in cost due to replacement of full form bending tool used typically in such apparatus. [0081] Features that are described and/or illustrated with respect to one embodiment may be used in the same way or in a similar way in one or more other embodiments and/or in combination with or instead of the features of the other embodiments.

[0082] List of reference numerals appearing in the accompanying drawings and the corresponding features:

200: apparatus

202: top unit 204: bottom unit

208: ring

302: suction holes

304: hoses

306: suction unit 606: cross member

904: peripheral ring

906: zonal ring