[0001] This application claims the benefit of priority under 35 USC 119(e) of U.S.

Provisional Application Serial No. 61/227/515 filed on July 22, 2009.

Background

[0002] The present invention relates generally to heat-and-quench scoring for separating a piece of glass into portions. More specifically, the present invention relates to methods and apparatuses for producing a quench zone useful in heat-and-quench scoring.

TECHNICAL BACKGROUND

[0003] Heat-and-quench scoring is a controlled fracturing process which draws a median crack across a piece of glass starting at an initiation flaw. Heat-and-quench scoring may be used to separate sheets of glass from a continuously formed ribbon, or may be used to separate the bead-containing edges from the remainder of the ribbon. Additionally, heat-and- quench scoring may be used to separate portions of a sheet of glass, hi any event, heat-and- quench scoring is a thermal shock process involving controlled heating of the glass, using a laser beam of specific prescription for example, followed by a rapid thermal quench with a quench zone. Laser scoring has been discussed in many references, but little discussion has been addressed to the quench zone itself. Typically, a quench zone includes a solid stream of cooling fluid that tracks the path of the laser beam and impinges on the glass to create the necessary thermal stresses. This design dictates that the alignment between the laser beam and the impinging fluid jet be strictly maintained, leaving little room for error. Additionally, it would be desirable to evaporate all the cooling medium dispensed before it has a chance to run down into the quality area of the glass and compromise it. In practice, however, substantially more fluid is used than is theoretically needed, so that all the available heat of vaporization is not efficiently used. This leads to the undesired need for excess fluid management.

SUMMARY

[0004] The present disclosure is directed to methods and apparatuses for forming a quench zone in which cooling medium is distributed in a heated zone in a heat-and-quench scoring operation. Distributing the cooling medium in the heated zone may relax the strict alignment requirement, may more efficiently utilize the cooling medium so as to reduce the amount of cooling medium actually used in a heat-and-quench scoring process, and/or may allow the quench zone to be shaped. [0005] Relaxing the strict alignment requirement allows a broader process window. By distributing the cooling medium in the heated zone, the area on the glass on which the quench zone impinges is increased. With a larger impingement area, the cooling medium will be delivered to the appropriate portion of the heated zone to produce the required thermal shock, and thus propagation of an initial flaw, even if the cooling medium nozzle is not strictly aligned with the heating spot. That is, there can be tolerated more offset between the cooling medium nozzle and the heated spot.

[0006] Reducing the amount of cooling medium actually used may, in turn, reduce or eliminate the need for excess water runoff management and thereby protect the quality area of the glass. The amount of cooling medium actually used may be reduced due to the more efficient use of the cooling medium. That is, by distributing the cooling medium in the heated zone, there is a greater likelihood that the cooling medium distributed to one point will be allowed to boil off more completely before additional cooling medium is again delivered to that spot. And allowing a more complete boil-off takes greater advantage of the heat of vaporization of the cooling medium, whereby a reduced amount of cooling medium may be used to achieve the necessary thermal shock.

[0007] Distributing the cooling medium in the heating zone can be done so that the quench zone takes on a desired shape. Shaping the quench zone allows varying amounts of cooling to be provided to various parts of a heated zone as desired. Accordingly, the shape of the quench zone can be suited to the thermal profile of the heating spot so as to more efficiently use the cooling medium to produce the required thermal shock. By more efficiently using the cooling medium, less cooling medium may be used thereby further reducing or eliminating the need for excess cooling medium management.

[0008] According to one aspect, cooling medium may be distributed in a heated zone in a heat-and-quench scoring operation by oscillating a target position at which the cooling medium is directed. The cooling medium may be directed toward the target position as a series of droplets, or as a stream. As used throughout the specification, the term "oscillate" and its variants, is meant to broadly include any back and forth type of movement including, but not limited to, dithering, fluctuating, quivering, shaking, shifting, shivering, swaying, swinging, trembling, and vacillating, for example. Additionally, the oscillation taken either alone or with other movement may, but need not, cause the target position to trace a sinusoidal pattern; in fact it may cause the target position to trace a square wave, a saw tooth wave, any other suitable wave or pattern, or no particular pattern at all. [0009] According to another aspect, cooling medium may be distributed in a heated zone in a heat-and-quench scoring operation by intermittently delivering droplets in a

predetermined repeated pattern to the heated zone. The pattern of droplets may be formed by a stream or streams of cooling medium that are provided by a nozzle or bank of nozzles, wherein the stream or streams are interrupted. The stream or streams may be physically interrupted, by passing a blocking element in front of a continuous stream or streams for example, or may be produced as interrupted stream or streams, by intermittently delivering cooling medium to the nozzle or bank of nozzles for example.

[0010] Various aspects of embodiments of the present invention include:

Aspect 1. A method of scoring glass, comprising:

heating the glass along a line along which the glass is to be scored, wherein the line extends in a first direction; and

quenching the heated glass along the line, wherein the quenching comprises:

ejecting cooling medium so as to impinge on a target position on the heated glass, wherein the target position moves in the first direction relative to the heated glass, and further wherein the target position oscillates with a predetermined frequency and amplitude as the target position is moved in the first direction.

Aspect 2. The method of aspect 1, wherein ejecting cooling medium so as to impinge on the target position comprises ejecting liquid so as to form droplets impinging on the target position.

Aspect 3. The method of aspect 2, wherein ejecting liquid so as to impinge on the target position comprises ejecting liquid from a nozzle, and oscillating the nozzle at a nozzle frequency and nozzle amplitude, wherein the nozzle includes an orifice including a diameter, and the liquid is ejected from the orifice at a flow rate, and further wherein the nozzle frequency, nozzle amplitude, orifice diameter, and flow rate are such that the liquid ejected from the nozzle forms droplets impinging on the target position.

Aspect 4. The method of aspect 3, wherein:

the target position moves relative to the heated glass in the first direction at a speed of from 100 mm/s to 1000 mm/s;

the nozzle frequency ranges from 30 Hz to 20 KHz;

the orifice diameter ranges from 0.1 mm to 0.4 mm; and

the flow rate ranges from 5 cm ³ /min to 70 cm ³ /min. Aspect 5. The method of aspect 4, wherein the nozzle amplitude ranges so that the droplets hit the glass within boundaries separated from one another from 1 to 25 mm when a distance from the nozzle to the glass ranges from 60 to 80 mm.

Aspect 6. The method of aspect 1, wherein ejecting cooling medium so as to impinge on the target position comprises ejecting the cooling medium from a nozzle and oscillating the nozzle at a nozzle frequency and nozzle amplitude, wherein the nozzle includes an orifice including a diameter, and the cooling medium is supplied to the nozzle at a pressure, and further wherein the nozzle frequency, nozzle amplitude, orifice diameter, and pressure are such that the cooling medium ejected from the nozzle forms a stream impinging on the heated glass.

Aspect 7. The method of claim 6, wherein the cooling medium is a liquid, and further wherein:

the target position moves relative to the heated glass in the first direction at a speed of 100 mm/s to l000 mm/s;

the nozzle frequency ranges from 20 Hz to 200 Hz;

the orifice diameter ranges from 0.1 mm to 0.4 mm; and

the fluid pressure ranges from 40 psi to 50 psi.

Aspect 8. The method according to any one of aspects 1-7, wherein the target position is oscillated in two directions.

Aspect 9. The method of aspect 8, wherein the two directions of oscillation are orthogonal to one another.

Aspect 10. The method of aspect 9, wherein one of the two directions of oscillation is substantially parallel to, or coincident with, the first direction.

Aspect 11. The method according to any one of aspects 1-10, wherein at least one of the frequency and amplitude is varied as the target position moves in the first direction.

Aspect 12. The method according to any one of aspects 1-11, wherein ejecting cooling medium so as to impinge on a target position comprises ejecting liquid from a plurality of nozzles.

Aspect 13. A method of scoring glass, comprising:

heating the glass along a line along which the glass is to be scored, wherein the line extends in a first direction; and

quenching the heated glass along the line, wherein the quenching comprises:

ejecting cooling medium from a nozzle so as to impinge on the heated glass; and manipulating the ejecting so as intermittently to produce a repeated pattern of droplets at a predetermined frequency.

Aspect 14. The method of aspect 13, wherein manipulating the ejecting so as intermittently to produce a repeated pattern of droplets at a predetermined frequency comprises at least one of: oscillating the nozzle at a predetermined frequency and a predetermined amplitude; intermittently disposing a chopper physically between the nozzle and the glass so as to interrupt a flow of cooling medium from the nozzle; and changing a pressure and/or a flow rate of the cooling medium as delivered to the nozzle.

Aspect 15. An apparatus for scoring glass, comprising:

a heating device configured and arranged to move relative to the glass in a first direction parallel to a line along which the glass is to be scored; and

a quenching device disposed adjacent to the heating device and configured and arranged to move relative to the glass in the first direction following the heating device, wherein the quenching device comprises:

at least one nozzle;

a driver coupled to the at least one nozzle to oscillate the at least one nozzle at a predetermined nozzle frequency and nozzle amplitude.

Aspect 16. The apparatus of aspect 15, wherein the driver is coupled to the at least one nozzle to oscillate the nozzle in a second direction, and further comprising a second driver coupled to the at least one nozzle to oscillate the at least one nozzle in a third direction at a predetermined second nozzle frequency and at a second nozzle amplitude.

Aspect 17. The apparatus of aspect 16, wherein the driver and second driver are coupled to the at least one nozzle so that the second direction is orthogonal to the third direction.

Aspect 18. The apparatus of aspect 17, wherein one of the second and the third directions is substantially parallel to, or coincident with, the first direction.

Aspect 19. The apparatus according to any one of aspects 15-18, wherein the nozzle includes an orifice, the orifice including a diameter in the range of 0.1 mm to 0.3 mm.

Aspect 20. An apparatus for scoring glass, comprising:

a heating device configured and arranged to move relative to the glass in a first direction parallel to a line along which the glass is to be scored; and a quenching device disposed adjacent to the heating device and configured and arranged to move relative to the glass in the first direction following the heating device, wherein the quenching device comprises:

at least one nozzle; and

means for intermittently producing a repeated pattern of cooling-medium droplets from the at least one nozzle so that the droplets impinge on the glass.

Aspect 21. The apparatus of aspect 20, wherein the means for intermittently producing a repeated pattern of droplets comprises at least one of: a driver that oscillates the at least one nozzle at a predetermined frequency and a predetermined amplitude; a chopper physically disposed between the at least one nozzle and the glass, and a driver that causes the chopper to intermittently interrupt a flow of cooling medium from the at least one nozzle; and a pressure changing device that causes droplets intermittently to be ejected from the nozzle.

Aspect 22. A method of producing a glass sheet comprising: producing a glass ribbon; scoring the glass ribbon according to any one of aspects 1-14; and bending the glass ribbon about the score line to separate one portion of the glass ribbon from another.

Aspect 23. The method of aspect 22, wherein the score line is perpendicular to a centerline of the glass ribbon.

Aspect 24. The method or apparatus according to any of the above aspects, wherein the cooling medium includes a surfactant.

[0011] For example, for a heated spot traveling at 100 to 1000 mm/s relative to a glass sheet, for sufficient quenching there may be used a quenching device having: a nozzle with an orifice diameter of from about .14 mm to about .294 mm; a cooling medium flow rate of from about 5 cm ³ /min to about 66 cm ³ /min; a distance between the nozzle and the glass of from about 62 mm to about 80 mm. Further, for example, with the above parameters if it is desired to oscillate the nozzle, such may be done at a frequency of between about 10 Hz and 20 KHz.

[0012] Additional features and advantages of the invention will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from the description or recognized by practicing the invention as described in the written description and claims hereof, as well as the appended drawings.

[0013] It is to be understood that both the foregoing general description and the following detailed description are merely exemplary of the invention, and are intended to provide an overview or framework to understanding the nature and character of the invention as it is claimed.

[0014] The accompanying drawings are included to provide a further understanding of principles of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate one or more embodiments, and together with the description serve to explain the principles and operation of the invention. It is to be understood that the various features of the invention disclosed in this specification and in the drawings can be used in any and all combinations.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] FIG. 1 is a schematic illustration of an apparatus for making a glass ribbon and separating it into sheets.

[0016] FIG. 2 is a schematic view of a heating spot and a target position for cooling medium on a glass ribbon or sheet during a scoring process.

[0017] FIG. 3 is a schematic side view of a quenching device according to one embodiment, wherein droplets of cooling medium impinge on a glass ribbon or sheet.

[0018] FIG. 4 is a schematic plan view of an arrangement similar to that shown in FIG. 3.

[0019] FIG. 5 is a schematic side view of a quenching device, wherein a stream of cooling medium impinges on a glass ribbon or sheet.

[0020] FIG. 6 is a schematic plan view of a quenching device similar to that shown in FIG. 3.

[0021] FIGS. 7-9 are sinusoidal patterns traced by a target position at which cooling medium is directed.

[0022] FIGS. 10-16 are Lissajous patterns traced by a target position at which cooling medium is directed.

[0023] FIG. 17 is an irregularly shaped pattern traced by a target position at which cooling medium is directed.

[0024] FIG. 18 is a schematic plan view of a quenching device according to another embodiment.

DETAILED DESCRIPTION

[0025] In the following detailed description, for purposes of explanation and not limitation, example embodiments disclosing specific details are set forth to provide a thorough understanding of the principles of the present invention. However, it will be apparent to one having ordinary skill in the art, having had the benefit of the present disclosure, that the present invention may be practiced in other embodiments that depart from the specific details disclosed herein. Moreover, descriptions of well-known devices, methods and materials may be omitted so as not to obscure the description of the principles of the present invention. Finally, wherever applicable, like reference numerals refer to like elements.

[0026] Ranges can be expressed herein as from "about" one particular value, and/or to "about" another particular value. When such a range is expressed, another embodiment includes from the one particular value and/or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent "about," it will be understood that the particular value forms another embodiment. It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint.

[0027] As noted above, heat-and-quench scoring may be used to separate a sheet of glass from a continuously formed ribbon of glass, or may be used to separate the bead-containing- edges of a ribbon from the remainder of the ribbon. The present disclosure is directed to improving the quench zone by distributing cooling medium in a heated zone. Distributing cooling medium in the heated zone may relax the strict alignment requirement between the heating spot and cooling spot target position, may more efficiently utilize the cooling medium so as to reduce the amount of cooling medium actually used in a laser scoring process, and/or may allow the quench zone to be shaped advantageously to suit the thermal profile of the heating spot. Heat-and-quench scoring, and thus the improved quench zone discussed herein, may be used with various manners of producing a glass ribbon, for example, a fusion draw method, a slot draw method, a float process, or the like. From here on, the present disclosure will discuss heat-and-quench scoring in terms of laser scoring in connection with a fusion draw process by way of example only, it being understood that the methods and apparatuses for scoring may be applied to other manners of making a glass ribbon, or even to a sheet of glass itself being cut into smaller portions.

[0028] FIG. 1 is a schematic illustration of an apparatus 10 for melting and forming glass, by a fusion draw process, into a ribbon 40 from which glass sheets are separated. The apparatus 10 includes a melting chamber 12 into which batch materials are introduced, and in which initial glass melting occurs. The apparatus 10 further includes components for processing and conveying the glass. The components for processing and conveying the glass may include one or more of a finer 16 in which bubbles are removed from the glass, a stir chamber 18 in which the glass is mixed and/or homogenized, and a bowl 20 which delivers the glass to an inlet 22. The finer 16, stir chamber 18, and bowl 20, are connected by pipes 14 that convey the glass from one component to the next. From the inlet 22, the glass flows into a fusion pipe 24 which forms a glass ribbon 40. More particularly, the fusion pipe 24 includes a trough 26, sides 28, and a root 30. The glass flows from the inlet 22 into the trough 26 of the fusion pipe 24, overflows from the sides of the trough 26, and subsequently down opposite sides 28 of the fusion pipe 24, before re-combining at the root 30 to form ribbon 40 having a centerline 42.

[0029] To separate a glass sheet 50 from the ribbon 40, the ribbon 40 is scored and bent along a line 44 that is substantially orthogonal to the centerline 42. The edges, including beads, of the ribbon 40 may be separated from the remainder of the ribbon 40 by scoring and bending the glass along lines 46 that are substantially parallel to the centerline 42. The lines 44 and 46 along which a score is formed to separate portions of the ribbon 40 may hereinafter be referred to as score lines. Alternatively to bending, other manners of manipulating the ribbon 40 may be used in conjunction with scoring to separate the sheet 50, or the edges of the ribbon, from the remaining portion of the ribbon 40.

[0030] One manner of scoring the ribbon 40 is by producing an initial flaw in the ribbon 40 (for example, by a mechanical scoring wheel, or by application of heat as with a laser for example), and propagating the flaw along the ribbon (along any of lines 44, 46). The initial flaw can be propagated by heating the ribbon 40 along a score line 44, 46, and subsequently quenching the ribbon 40. The ribbon 40 can be heated by a heating device 100, and quenched with a quenching device 200.

[0031] The heating device 100 may include any device that suitably directs a sufficient amount of heat at the ribbon 40, for example a laser, a flame, an electrical resistance heater, or the like. The details of the heating device 100 are not necessarily limited for purposes of this application. As shown in FIG. 2, the heating device 100 produces a heating spot 110 on the glass 40, 50 to thereby locally heat the glass 40, 50 (for ease in description, although the glass maybe the ribbon 40 and/or a sheet 50, the term ribbon maybe used hereinafter to refer to both). In order to heat the ribbon 40 along the desired length of the score line 44, 46, the heating device 100— and/or the heating spot 110— are made to travel by any suitable device relative to the ribbon 40 in the direction of arrow A so as to move the heating spot 110 across the ribbon 40 and produce a heated zone 115, which is shown as bounded by lines 120, 130. For example, the heating device 100 may be moved relative to the ribbon 40 at a speed of from about 100 mm/s to about 1000 mm/s. Moving the heating spot 110 in the first direction A can be done by moving the heating spot 110 with respect to glass stationary in that direction, by moving the glass with respect to a stationary heating spot 110, or by moving both the heating spot 110 and the glass.

[0032] The quenching device 200 directs cooling medium at a target position 210 within the heated zone 1 15 to quench the ribbon 40. The cooling medium, as used throughout the specification, may be any suitable fluid, either a liquid or a gas, for example water, alcohol, liquid nitrogen, or mixtures thereof. In essence, any fluid or fluid mixture that has a high heat of vaporization and does not leave a detrimental residue could be used. Additionally, a surfactant may be added to the fluid or fluid mixture to change the surface tension of a stream formed thereby. Changing the surface tension of the stream will then change the conditions under which the stream will breakup into droplets. Another possible cooling medium that may be used is carbon dioxide snow pellets, which may exist as a solid or a gas under normal atmospheric conditions. In order to propagate the initial flaw along the desired length of the score line 44, 46 by a heat-and-quench process, the target position 210 travels relative to the ribbon 40 in the direction of arrow A, and follows the heating region 110 across the ribbon 40. Moving the target position in the first direction A parallel to the score line 44, 46 can be done by moving the quenching device 200 with respect to glass stationary in that direction, by moving the glass with respect to a stationary quenching device 200, or by moving both the quenching device 200 and the glass. The direction of arrow A may correspond with that of either of the score lines 44, 46. Typically, the quenching device 200 will travel relative to the ribbon 40 at the same speed as does the heating device 100. For example, the quenching device may travel at a rate of from about 100 mm/s to about 1000 mm/s.

[0033] The quenching device 200 can distribute cooling medium in the heated zone 115 by directing cooling medium to impinge on a moving target position 210. By moving the target position 210, the effective area of the cooling spot increases which, while maintaining the cooling-medium flow, may be one way to relax the alignment requirement and broaden the laser scoring process window. Additionally, moving the target position 210 through the heated zone 115 may subject more of the cooling medium to vaporization thereby leading to a more efficient utilization of the cooling medium and, perhaps, a reduction in the amount of cooling medium necessary. Further, moving the target position 210 through the heated zone 115 allows the cooling medium to be delivered in a controllable impingement area that may be adjusted to suit the thermal profile of the heating spot.

[0034] The target position 210 can move along one or more of the directions B and C, as the target position 210 also moves along direction A within in the heated zone 115. The movement of the target along direction A is provided by the relative movement of the quenching device 200 and the glass. The movement of the target position 210 along directions B and/or C may be any desired movement, for example an oscillating movement. Although the direction C is shown as being substantially parallel to the direction A, it need not be. That is, the direction C may be at any angle with respect to the direction A. Further, although the directions B and C are shown as perpendicular to one another, again, they need not be; instead, they may be at any desired angle with respect to one another. However, having the directions B and C substantially orthogonal to one another, wherein one corresponds with the direction of the score line 46, and the other corresponds with that of the score line 44 offers advantages. For example, in such a case, one quenching device may be used in connection with either a horizontal sheet, or a vertical bead, separation process along score lines 44, 46 respectively. That is, as directions are shown in FIG. 1 for example, the quenching device 200 may be used to produce a score along line 44 by moving the target position 210 in the B direction as the quenching device 200 moves relative to the ribbon 40 in the A direction, and then also to produce a score along line 46 by moving the target position 210 in the C direction with the quenching device 200 being stationary while the ribbon 40 moves in the B direction. The quenching device 200 may direct the cooling medium toward the target position 210 as a series of droplets, or as a stream.

[0035] As shown in FIGS. 3-5, embodiments of the quenching device 200 include a nozzle 220 having an orifice with a diameter 222. FIG. 3 is a schematic side view, whereas FIGS. 4 and 5 are schematic plan views. The nozzle 220 is connected to a cooling medium supply (not shown) so as to deliver cooling medium from the orifice at a desired flow rate or pressure. The nozzle 220 is positioned at a distance 224 from the ribbon 40. The nozzle 220 is connected to a driver 230 which drives the nozzle 200 in the direction of arrow B, i.e., up and down as directions are shown in FIG. 3, over a range or nozzle amplitude 232. The nozzle 220 is also connected to a second driver 240 which drives the nozzle 220 in the direction of arrow C, i.e., into and out of the page as directions are shown in FIG. 3.

[0036] Each of the drivers 230 and 240 may provide the nozzle 220 with an amplitude and frequency of oscillation in the respective directions B and C. Additionally, the amplitude and frequency in each direction B and C independently may vary as the quenching device moves relative to the glass ribbon 40 in the direction A. The amplitude 232 and flow rate of the cooling medium from the nozzle 220 may be selected so that the cooling medium can at least reach the upper 120 and lower 130 bounds of the heated zone 115. That is, more generally, for any given height of desired cooling medium impingement (for example the distance between boundaries 120, 130 of the heated zone 115), with ribbon 40 at a given distance 224 from the nozzle 220, a suitable range of nozzle amplitudes 232 and flow rates can be determined so that the cooling medium can reach the desired points on the ribbon 40 (for example boundaries 120, 130). Although only one nozzle 220 is shown, any suitable number of nozzles 220 may be used in any suitable positional arrangement with respect to one another. When using multiple nozzles 220, they may either have the same flow rate and orifice diameter 222, or these parameters may vary between nozzles.

[0037] By way of non-limiting example, each of the drivers 230, 240 maybe a voice coil, an ultrasonic horn, or any other driver and coupling that allows the nozzle 220 to be oscillated or driven. With a given size voice coil as a driver, for a given nozzle and mount set-up, higher frequencies generally lead to lower nozzle amplitudes because the nozzle and mount act as a damper. However, using different drivers 230, 240 would allow a wide range of amplitudes and frequencies to be attained.

[0038] One example of a coupling allowing the nozzle 220 to oscillate in two directions is shown in FIG. 6. As shown in FIG. 6, the coupling includes a nozzle mount 250, a rear bar 251, a flexible section 252, and a pivot pin 254. The nozzle 220 may be mounted on nozzle mount 250 by any suitable structure. The nozzle mount 250 is connected to a rear bar 251 by flexible section 252. The rear bar 251 includes a pivot pin 254 that is mounted to the quenching device 200 so that the rear bar 251 is restricted to pivot about the axis of the pivot pin 254. The flexible section 252 allows the nozzle mount 250 to move in the C direction while also pivoting about the pin 254 for movement in the B direction.

[0039] Cooling medium ejected from the nozzle 220 may be made to trace a two dimensional pattern in the heated zone 115. Either one or both of the drivers 230, 240 may be used to create various two dimensional patterns and, thereby, distribute cooling medium in the heated zone 115 in any desired manner. Due to the flexibility in distributing cooling medium in the heated zone 115, the cooling profile may be made to advantageously suit the thermal profile of the heating spot 110.

[0040] For example, the driver 230 may be operated by itself with a forcing function (including an amplitude and frequency) to oscillate the nozzle 220 in the B direction while the quenching device 200 moves relative to the glass in the A direction; there being no additional movement of the nozzle 220 in the C direction. As a result, the target position 210 may be made to trace a sinusoidal pattern as shown in FIG. 7, wherein the A direction corresponds to one of the score lines 44, 46. Varying the amplitude and frequency of the forcing function can cause the pattern traced by the target position 210 to change. For example, as shown in FIG. 8, the pattern can be such that more cooling medium is delivered to the outer portions of the heated zone, i.e., those near the boundary lines 120, 130. In one alternative, as shown in FIG. 9 for example, the pattern can be such that more cooling medium is delivered to one of the outer portions of the heated zone 115, i.e., near either one of the boundary lines 120, 130. By making the amplitude of the movement in the B direction smaller, more cooling medium can be delivered to the central portion of the heated zone 115. Although the sinusoidal patterns of FIGS. 7-9 are shown as being centered on the A direction, i.e., on the score line 44, 46, they may be shifted either up or down in the B direction as desired. Further, although sinusoidal patterns are shown, any shape of wave form can be achieved by selecting a suitable driving function as input into the drivers 230, 240. For example, a square wave, a saw tooth wave, or any combination of waves, maybe used. Still further, by varying the period of the forcing function, the target position 210 may be made to trace a line as shown in FIG. 10. Then, as the quenching device 200 moves relative to the glass in the A direction, the line also may be made to traverse across the heated zone 115.

[0041] Whether cooling medium will impinge on the glass ribbon 40 within the heated zone 115, i.e., between the boundary lines 120, 130, depends upon the amplitude 232, flow rate of cooling medium emitted from the nozzle 220, and the distance 224. By appropriately selecting an amplitude 232 and flow rate for a given distance 224, the droplets 226 or stream 228 can be made to impinge on the heated zone 115. Similarly, if the distance 224 is varied, the amplitude 232 and flow rate may be adjusted so that the cooling medium still impinges on the heated zone 115.

[0042] Although the description above was made with respect to the driver 230 and the B direction, the same is equally applicable to the driver 240 and the C direction. That is, the driver 240 may be operated by itself with a forcing function to oscillate the nozzle 220 in the C direction while the movement of the quenching device 200 moves relative to the glass in the A direction; there being no additional movement of the nozzle 220 in the B direction.

[0043] Further, both of the drivers 230 and 240 may be operated at the same time with forcing functions to oscillate the nozzle 220 in both the B and C directions. As a result of the oscillation in the B and C directions (wherein B and C are orthogonal to one another), the target 210 may be made to trace classic Lissajous figures as shown in FIGS. 11-16 for example. The Lissajous figures may then be made to traverse across the heated zone 115 by movement of the quenching device 200 relative to the glass in the A direction. FIG. 17 shows another possible pattern that the target position 210 can trace by moving the nozzle 220 through the action of drivers 230, 240. In FIGS. 11-17, the horizontal of the figure can correspond to either the B or C directions, wherein the C and A directions correspond to one another, and the B direction is substantially orthogonal to the C direction. Further, by varying the angle between either the C or B directions and the A direction, the shapes shown in FIGS. 10-17 may be tilted with respect to the A direction. Still further, similarly to that as noted above, the patterns in FIGS. 11-17 may be positioned with their centers at about the same location as a score line 44,46, or they may have their centers shifted toward one side of a score line 44,46 to any degree. Such flexibility in the shape traced by the target position 210, and positioning thereof in the heated zone 115, allows great flexibility in tailoring the amount of cooling to the thermal profile of the heating spot 110. That is, a greater amount of cooing may be made to correspond with the hottest part of the heating spot 110, if so desired.

[0044] Moreover, the movements in the B and C directions may be varied as the quenching device 200 moves relative to the glass in the A direction. That is, the force functions input to the drivers 230 and 240 may be dynamically varied to even further control the pattern traced by the target position 210, whereby different patterns may be used for different portions along any one score line 44, 46.

[0045] The quenching device may deliver either a series of droplets 226 as shown in FIGS. 3 and 4, or a solid stream of cooling medium 228 as shown in FIG. 5, to the target position 210 as the target position traces any of the patterns shown in FIGS. 7-17. A series of droplets 226 may provide more advantageous cooling than a solid stream 228 of cooling medium, because the latter may not utilize as much of the available heat of vaporization available. That is, as stated in one paper, "a solid surface looses heat much more rapidly to small droplets of liquid impinging on it than it does to the same liquid flowing continuously over it" (The Effect of Dissolving Gases or Solids in Water Droplets Boiling on a Hot Surface, Qiang Cui, Sanjeev Chandra, and Susan McCahan, J. Heat Transfer 123, 719, 2001). Further, delivering the droplets 226 so that they trace a target pattern (for example any of the patterns shown in FIGS. 7-17), as opposed to being delivered to a fixed target spot, may allow each droplet to more fully vaporize thereby more efficiently using the cooling medium whereby less cooling medium may be needed. That is, by tracing a target pattern, one droplet may be delivered to a point on the glass and allowed to boil off before another droplet is again delivered to that same point. And in the interim, the nozzle may be used to deliver another droplet to a different point on the glass.

[0046] Appropriately choosing the nozzle frequency, nozzle amplitude 232, orifice diameter, and flow rate, will lead to either droplets 226 or a stream 228 of cooling medium impinging on the heated zone 115. The nozzle frequency and nozzle amplitude 232 are set by the frequency and amplitude of the oscillation imparted by drivers 230, 240. Again, these parameters may be set by the force function input to the drivers 230, 240.

[0047] The mechanism for droplet formation may vary such that droplets 26 may be formed over a range of nozzle amplitudes and frequencies. For a given orifice diameter and flow rate, a stream of liquid emitted from the nozzle 220 will start to spread after the product of oscillation amplitude and frequency passes a first certain level. Suffice it to say that the stream itself becomes unstable after the liquid's surface tension can no longer hold the oscillating stream together. As the product of oscillation amplitude and frequency increases further, the surface tension is no longer able to hold the stream together. The stream begins to fragment and the surface tension coalesces the fragments into discrete droplets. There is a transition from the heated zone 115 being constantly bathed by a solid stream to being impinged by discrete droplets of liquid. Eventually, as the product of oscillation amplitude and frequency passes a second level, there is enough energy transmitted to the liquid that the droplet actually forms as it is exiting the tip of the nozzle. If the nozzle is further excited to its resonant frequency, then the mechanism of drop formation changes to first forming a sheet of liquid at the nozzle tip to then breaking up the sheet into discrete droplets. The net result is still the same, i.e., discrete droplets of liquid are delivered to the ribbon 40 in the heated zone 115. The actual numerical values, for the levels at which the product of oscillation amplitude and frequency will form drops, depend upon the flow rate of cooling liquid from the nozzle and upon the orifice diameter.

[0048] Another manner of distributing cooling medium through the heated zone 115 is to intermittently deliver droplets in a predetermined pattern to the heated zone 115.

[0049] The quenching device 200 may include structure capable of intermittently delivering droplets in a predetermined pattern to the heated zone 115. The pattern of droplets may be formed by a stream or streams of cooling medium that are provided by a nozzle or bank of nozzles, wherein the stream or streams are interrupted. The stream or streams may be physically interrupted, by passing a blocking element in front of a continuous stream or streams for example, or may be produced as interrupted stream or streams, by intermittently delivering cooling medium to the nozzle or bank of nozzles for example. Cooling medium may be intermittently delivered to the nozzle or bank of nozzles by controlling the pressure of cooling-medium supply, for example. One manner of controlling supply pressure would be akin to that used in ink-jet printing.

[0050] FIG. 18 shows one embodiment of a quenching device 200 that delivers droplets to the heated zone by physically interrupting a stream or streams of cooling medium delivered by one or more nozzles 220. The cooling medium streams from the nozzles 220 are interrupted by a rotary chopper 260. The rotary chopper 260 includes alternating solid sections 262, and open areas 264. A motor 266 is connected to the rotary chopper 260 to drive the rotary chopper 260 in either a clockwise or counter-clockwise manner as indicated by arrow D. As an open area 264 passes an orifice of a nozzle 220, a discrete amount of cooling medium (droplet) is allowed to impinge upon the heated zone 115.

[0051] The amount of cooling medium delivered to the heated zone maybe controlled. The size of the open area 264, the rotation speed of the rotary chopper 260, the orifice size, and flow rate of cooling medium, determine the amount of cooing medium (or size of the droplet) delivered. In a sense, the amount of cooling medium may be thought of as a bullet. For a given rotation speed, open area, and flow rate, a larger orifice size will give a larger diameter bullet. Similarly, for a given rotation speed, open area, and orifice size, a higher flow rate will give a longer bullet. On the other hand, for a given orifice size, open area, and flow rate, a higher rotation speed will give a higher number of shorter bullets per unit time. Similarly, for a given orifice size, flow rate, and rotation speed, a smaller open area with give a shorter bullet. Moreover, using a higher percent of blockage (i.e., a smaller open area 264) with a higher flow rate (all other variables being equal) will lead to a stiffer, faster, bullet. Stiffer, faster, and/or larger, bullets may be less influenced by airflows which may exist in the region of the quenching device 200, and/or by gravity. That is, for example, a faster bullet will have less time for its trajectory to be influenced by gravity when traveling over the same distance as a slower bullet. Thus, by controlling the size of the open area 264, the rotation speed of the rotary chopper 260, the orifice size, and flow rate of cooling medium, one may control the amount of cooling medium delivered to the heated zone 115.

[0052] Although two nozzles 220 are shown as being aligned one above the other in the B direction, they may have any arrangement desired, i.e., so as to form a line at any angle to the B direction. Further, although only two nozzles 220 are shown, any suitable number may be used. And two or more nozzles 220 may be disposed at any suitable spacing from one another, i.e., any suitable distance, and either at the same or different distances from one another. Concerning spacing, in general, decreasing the nozzle spacing will increase the number of droplets on the glass thus allowing a lower flow rate to be used. Still further, when using more than two nozzles 220, they may be disposed so as to form a pattern of any desired shape, for example oval, circle, triangle, square, or irregular shape. The shape may be suited to the thermal profile of the heating spot 110. Yet still further, although the open areas 264 and solid sections 262 are shown as being of equal size, they need not be. And varying the sizes is another manner in which to vary the amount of cooling medium delivered. More specifically, the open areas 264 may be: either smaller or larger than the solid sections 262; and/or of a different number than the solid sections 262; of two or more different sizes in one rotary chopper 260. Moreover, the nozzles 220 may deliver the same or different flow rates of cooling medium, thus providing one more variable for tailoring the amount of cooling to the thermal profile of the heated zone 110.

EXAMPLES

[0053] To further illustrate principles of the present disclosure, the following examples are put forth so as to provide those of ordinary skill in the art with a complete disclosure and description of how cooling medium may be distributed in a heated zone 115 in either a solid stream or as droplets. They are intended to be purely exemplary of the disclosure and are not intended to limit the scope of what the inventors regard as their disclosure. Efforts have been made to ensure accuracy with respect to numbers (e.g., amounts, temperatures, etc.);

however, some errors and deviations can occur. Unless indicated otherwise, temperature is at ambient temperature, and pressure is at or near atmospheric.

Example 1

[0054] A quenching device of an arrangement generally shown in FIGS. 3 and 4 was used, with a voice coil as a driver, to produce droplets 226 of water under the following conditions:

flow rate of 26 cm /min

distance 224 of 80 mm

orifice diameter 222 of .292 mm

oscillation frequency (1-axis) of from 550 Hz to 1200 Hz

distance between upper and lower bounds 120, 130 of where droplets landed on glass sheet of from 1 mm to 23 mm.

Thus, for a given flow rate, distance 224, and orifice diameter 222, a variety of oscillation frequencies and amplitudes 232 may be used to produce droplets 226. Example 2

[0055] A quenching device of an arrangement generally shown in FIGS. 3 and 4 was used, with an ultrasonic horn as a driver, to produce droplets 226 of water under the following conditions:

flow rate of 12 to 51 cm ³ /min

distance 224 of from 65 mm to 70 mm

orifice diameter 222 of from .14 mm to .394 mm

oscillation frequency (1 -axis) of 20 KHz

a variety of amplitudes 232 (varying by about 20%)

Thus, for relatively high frequencies, a variety of amplitudes 232, orifice diameters 222, distances 224, and flow rates, may be used to produce droplets 226.

Example 3

[0056] A quenching device of an arrangement generally shown in FIGS. 3 and 4 was used, with a motor and cam arrangement as a driver, to produce droplets 226 of water under the following conditions:

flow rate of from 5 cm ³ /min to 66 cm ³ /min

distance 224 of 72 mm

orifice diameter 222 of from .14 mm to .191 mm

oscillation frequency (1 -axis) of 33 Hz

fixed amplitude 232.

Thus, for a fixed amplitude 232, oscillation frequency, and distance 224, a variety of flow rates and orifice diameters may be used to produce droplets 226.

Example 4

[0057] A quenching device of an arrangement generally shown in FIGS. 3 and 4 was used, with a voice coil as a driver, at constant amplitudes with varying frequencies to produce either droplets 226 or a stream 228 of water under the following conditions:

constant flow rate

distance 224 of from 68 mm to 80 mm

orifice diameter 222 of .292 mm

(i) When the amplitude 232 was constant at 25% of maximum, the stream changed from solid to droplets as the frequency changed from 20 Hz to 550 Hz.

(ii) When the amplitude 232 was constant at 50% of maximum, the stream changed from solid to droplets as the frequency changed from 200 Hz to 400 Hz. (iii) When the amplitude 232 was constant at 100% of maximum, the stream changed from solid to droplets as the frequency changed from 200 Hz to 550 Hz.

Thus, for any given amplitude, as frequency increases, a steady stream of cooling fluid can be made to turn into droplets impinging on the heated zone 115.

[0058] In sum, the present disclosure and Examples set forth exemplary manners in which cooling medium may be distributed in a heated zone 1 15 in a heat-and-quench process for scoring glass. For example, the cooling medium can be distributed by (a) forming a solid stream directed at a target position that is oscillated in the heated zone; (b) forming droplets impinging upon a target position in the heated zone 115; (c) forming droplets and directing them at a target position that is moved (oscillated) in the heated zone, whereby droplets (as in either b or c) may be formed by: (d, i) moving a nozzle, in one or more directions; or (d, ii) using a plurality of nozzles aimed at different positions in the heated zone, and interrupting the streams of cooling medium from the nozzles, whereby the streams of cooling medium may be interrupted by (d, ii, a) physical interruption or (d, ii, b) by intermittent delivery of cooling medium to nozzles.

[0059] Distributing cooling medium in a heated zone in a heat-and-quench scoring process may lead to:

a) relaxation of the strict alignment requirement between a cooling medium nozzle and a heating spot;

b) reduction in the amount of water needed to propagate the initial flaw; and/or c) an increased ability to shape the quench zone so as to deliver different amounts of cooling to different parts of the heated zone to thereby suit the quench zone to the thermal profile of the heated zone.

[0060] It should be emphasized that the above-described embodiments of the present invention, particularly any "preferred" or "exemplary" embodiments, are merely possible examples of implementations, merely set forth for a clear understanding of principles of the invention. Many variations and modifications may be made to the above-described embodiments of the invention without departing substantially from the spirit and principles of the invention. All such modifications and variations are intended to be included herein within the scope of this disclosure and the present invention and protected by the following claims. [0061] For example, although the nozzle oscillation and stream interruption embodiments are discussed separately, they may be used together. Doing so may give greater flexibility in design, or in shaping/positioning of the quench zone.