The present disclosure generally relates to apparatuses and methods for processing a glass sheet. More particularly, it relates to stabilization of a glass sheet, such as a vertically oriented glass sheet, in conjunction with other processing steps, such as cleaning of the glass sheet.
In a typical glass manufacturing system, various raw constituents or batch materials are introduced or “charged” into a melting furnace. The batch materials are melted to form a viscous molten material that can be flowed to a fabrication portion of the system. The viscous molten material, when cooled, forms a glass.
The manufacture of glass sheets or other glass articles by melting raw materials is known. In one such process, known as a fusion process, molten glass overflows the sides of a trough in a forming body. The separate flows then re-unite, or fuse, at the bottom of the forming body to form a continuous ribbon of glass. Separate sheets of glass are then separated (e.g., cut) from the glass ribbon. For example, with some techniques, beads can be formed at opposing edges of the glass ribbon and serve as handling surfaces for the separation (and perhaps other) processes. Where provided, the beads are subsequently separated (e.g., cut) from a remainder of the glass sheet. Fusion processes are used in glass manufacturing operations to produce thin glass sheets that are used in a variety of products including flat panel displays.
Regardless of how the glass ribbon is formed or how the glass sheets are separated from the glass ribbon, debris (e.g., glass chips and particles) are oftentimes generated during the separation (e.g., cutting) step(s). Further, environmental conditions associated with the glass ribbon and/or glass sheet forming stations may have air-borne particles from other sources. These debris and particles can land on the surface(s) of the glass sheet. Initially, these glass chips and particles are bonded to the glass sheet surface(s) via van der Walls, electrostatic, and capillary interactions, which are relatively weak. Upon aging during transportation and storage, however, much stronger covalent bonds form between the glass sheet surface and the glass chips/particles and as a result, such glass chips/particles can become extremely difficult to remove and may pose quality concerns.
In light of the above, some glass sheet production systems or lines include one or more washing station(s) and drying station(s) that clean the glass sheet shortly after the separation process(es). Conventionally, the washing station sprays water (or other liquid) onto the opposing major surfaces of the glass sheet, for example via liquid spray orifices (e.g., water bearings). To effectuate washing at both major surfaces of the glass sheet, opposing sets of liquid spray orifices are typically provided, with the sets arranged to spray liquid onto a respective one of the glass sheet's two major surfaces. In other words, a gap is established between the opposing sets of liquid spray orifices; the glass sheet passes through this gap during a washing operation. To achieve a desired level of washing, the liquid spray orifices are desirably located in close proximity to the glass sheet. Thus, the gap between the opposing sets of liquid spray orifices can be relatively small in some instances. Under circumstances where the glass sheet is less than fully supported (e.g., when the glass sheet is held in a vertical orientation by an edge gripping device), an effective thickness of the glass sheet (e.g., deviations in flatness, vibration of the glass sheet, etc.) may be greater than the size of the gap. Similar concerns can arise with respect to the drying station (in which, for example, opposing air knives are arranged to direct a stream of gas onto a corresponding one of the glass sheet's two major surfaces).
Accordingly, alternative apparatuses and methods for processing a glass sheet, for example as part of a glass sheet manufacturing process, are disclosed herein.
Some embodiments of the present disclosure relate to a method of processing a glass sheet. The glass sheet comprises or defines opposing, first and second major surfaces. The glass sheet is delivered to a pre-positioning station. The pre-positioning station is operated to spray a liquid onto the first major surface to stabilize the glass sheet. The stabilized glass sheet is delivered to a washing station. The washing station is operated to wash the glass sheet. The washed glass sheet is delivered to a drying station. The drying station is operated to dry the glass sheet. With some methods of the present disclosure, by stabilizing the glass sheet at the pre-positioning station immediately prior to the washing station, the likelihood of physical contact between the glass sheet and components of the washing station are minimized. In some embodiments, the step of operating the pre-positioning station includes directing a gas stream onto the second major face. In other embodiments, the step of operating the pre-positioning station includes the sprayed liquid maintaining the glass sheet in a vertical orientation. In other embodiments, the step of delivering the glass sheet to the pre-positioning station includes engaging an edge of the glass sheet with a gripping device and moving the gripping device toward the pre-positioning station; in related embodiments, the step of operating the pre-positioning station includes disengaging the gripping device from the glass sheet, followed by re-engaging the glass sheet with the gripping device.
Yet other embodiments of the present disclosure relate to an apparatus for processing a glass sheet. The glass sheet comprises or defines opposing, first and second major surfaces. The apparatus comprises a pre-positioning station, a washing station, and a drying station. The pre-positioning station comprises a liquid spray assembly configured to spray liquid. Further, the pre-positioning station is configured to spray a liquid onto a first major surface of the glass sheet to stabilize the glass sheet. The washing station is downstream of the pre-positioning station and is configured to wash the glass sheet. The drying station is downstream of the washing station and is configured to dry the glass sheet. With the apparatuses of the present disclosure, the washing station can comprise opposing, first and second sets of liquid dispensers, the first set of liquid dispensers being transversely separated from the second set of liquid dispensers by a gap, and the pre-positioning station is configured to reduce an effective transverse dimension of the glass sheet to a dimension less than the gap.
Yet other embodiments of the present disclosure relate to a method for making a glass sheet. The method includes forming a glass web. A glass sheet is separated from the glass web and comprises opposing first and second major surfaces. The glass sheet is delivered to a pre-positioning station. The pre-positioning station is operated to spray a liquid onto the first major surface to stabilize the glass sheet. The stabilized glass sheet is delivered to a washing station. The washing station is operated to wash the glass sheet. The washed glass sheet is delivered to a drying station. The drying station is operated to dry the glass sheet. In some embodiments, with these and other methods of the present disclosure, a glass sheet can be formed, stabilized and cleaned on an in-line basis.
Additional features and advantages will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the embodiments described herein, including the detailed description which follows, the claims, as well as the appended drawings.
It is to be understood that both the foregoing general description and the following detailed description describe various embodiments and are intended to provide an overview or framework for understanding the nature and character of the claimed subject matter. The accompanying drawings are included to provide a further understanding of the various embodiments, and are incorporated into and constitute a part of this specification. The drawings illustrate various embodiments described herein, and together with the description serve to explain the principles and operations of the claimed subject matter.
Reference will now be made in detail to various embodiments of apparatuses and methods for processing a glass sheet and glass sheet manufacturing operations. Whenever possible, the same reference numerals will be used throughout the drawings to refer to the same or like parts. However, this disclosure may be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein.
Glass sheets are commonly fabricated forming a glass ribbon with a glass ribbon forming apparatus, separating a glass sheet from the glass ribbon by a separating apparatus, and cleaning the separated glass sheet by a handling apparatus. Glass ribbons are commonly fabricated by flowing molten glass to a forming body whereby a glass ribbon may be formed by a variety of ribbon forming processes including float, slot draw, down-draw, fusion down-draw, up-draw, or any other forming processes. The glass ribbon from any of these processes may then be subsequently divided to provide one or more glass sheets suitable for further processing into a desired application including, but not limited to, a display application. For example, the one or more glass sheets can be used in a variety of display applications including liquid crystal displays (LCDs), electrophoretic displays (EPD), organic light emitting diode displays (OLEDs), plasma display panels (PDPs), or the like. Glass sheets may be transported from one location to another. The glass sheets may be transported with a conventional support frame designed to secure a stack of glass sheets in place. Moreover, interleaf material can be placed between each adjacent glass sheet to help prevent contact between, and therefore preserve, the pristine surfaces of the glass sheets.
It is to be understood that specific embodiments disclosed herein are intended to be exemplary and therefore non-limiting. As such, the present disclosure relates to methods and apparatus for processing at least one of a glass ribbon and a glass sheet. In some embodiments, the glass ribbon to be processed can be formed from a glass manufacturing apparatus, can be provided as it is being formed from a glass manufacturing apparatus, can be provided from a spool of previously-formed glass ribbon that can be uncoiled from the spool, or can be provided as a freestanding glass ribbon. In some embodiments, the glass sheet to be processed can be formed by a glass manufacturing apparatus, can be provided as a glass sheet separated from a glass ribbon, can be provided as a glass sheet separated from another glass sheet, can be provided as a glass sheet uncoiled from a spool of glass sheets, can be provided as a glass sheet obtained from a stack of glass sheets, or can be provided as a freestanding glass sheet.
One embodiment of the handling apparatus 34 is shown in greater detail in
The pre-positioning station 50 includes a liquid spray assembly 80 that is configured and arranged to spray a liquid onto the first major surface 60 (
In some embodiments, the pre-positioning station 50 can optionally include an actuator device 90 connected (directly or indirectly) to the bars 82 (and in particular the orifices 84 formed or carried thereby) and operable to translate or move the orifices 84 in a direction transverse to the travel direction T. For example,
Returning to
Though not shown in
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The pre-positioning station 50 can include one or more additional components. For example, a pan 130 can be provided for collecting liquid dispensed by the liquid spray device 80. Further, a controller 132 can be provided that is electronically connected to, and controls operation of, one or more of the liquid spray device 80, the actuator device 90, the support apparatus 100, the gas stream directing assembly 110, and the conveyor device 56. The controller 132 can be or can be akin to a computer, and can include a memory operating on software or hardware programmed to perform the operational steps described below. The controller 132 can optionally further be programmed to control operations of other components of the handling apparatus 34, for example components of the washing station 52 and/or the drying station 54.
As mentioned above, the pre-positioning station 50 is configured to stabilize the glass sheet 42 prior to delivery to the washing station 52. As a point of reference, as initially provided to the pre-positioning station 50, the glass sheet 42 may exhibit deviations in flatness. For example, where the glass sheet 42 is separated from the glass ribbon 40 (
One non-limiting example of a method 150 for processing the glass sheet 42 by the pre-positioning station 50 is schematically shown in
At step 154, and with additional reference to
At step 158 (e.g., after a short dwell time at steps 154 and/or 156), and with additional reference to
With additional reference to
At step 162, and with addition reference to
At step 164, and with additional reference to
At step 166, while the glass sheet 42 may or may not continue to remain stationary, the liquid spray assembly 80 is operated to spray liquid L onto the first major surface 60. As mentioned above, the liquid spray assembly 80 can be operated to spray liquid L as part of one or more previous steps. Regardless, at step 166, and with the orifices 84 located at the final lateral spacing SF (e.g., optionally in the range of 0.1-10 mm, alternatively less than 10 mm, alternatively less than 5 mm, optionally on the order of 1 mm), the liquid spray assembly 80 sprays the liquid L onto the first major surface 60 at a flow rate appropriate for stabilizing the glass sheet 42. For example, in some non-limiting embodiments, a liquid flow rate in the range of 0.5-10 gal/min is evenly supplied across an entirety of the liquid spray assembly 80, alternatively less than 9 gal/min, alternatively less than 5 gal/min, and optionally in the range of 1-2 gal/min. Other flow rates are also envisioned. With optional embodiments including the gas stream directing assembly 110, a transverse distance between the outflow side of the gas stream directing assembly 110 (e.g., nozzles 112 in
With additional reference to
The methods implicated by
The washing station 52 and the drying station 54 can assume various forms appropriate for washing and drying the glass sheet 42, and in some embodiments can share a common housing 200. One non-limiting example of the washing station 52 and the drying station 54 is shown in
The washing station 52 can include the housing 200 with a first liquid dispenser 204 (e.g., a plurality of first liquid dispensers 204) including a first liquid nozzle 206 (e.g., a plurality of first liquid nozzles 206) oriented to dispense liquid against the major surfaces 60, 62 of the glass sheet 42. While not shown, an exemplary washing station 52 can dispense liquid against both the first major surface 60 of the glass sheet 42 and the second major surface 62 (
In some embodiments, the housing 200 can be substantially enclosed, although a side wall of
The drying station 54 can include a gas knife 218 positioned downstream (e.g., along the travel direction T) from the first liquid dispenser 204, such as within the second area 212b of the housing 200, as shown. The gas knife 218 can include a gas nozzle 220 (e.g., an elongated nozzle) oriented to extend along the entire length “L” of the glass sheet 42 and oriented to dispense gas against the major surfaces 60, 62 of the glass sheet 42 to remove liquid from the major surfaces 60, 62 of the glass sheet 42. The gas knife 218 may be oriented at a first angle “A1” relative to the travel direction T of the glass sheet 42 through the drying station 54. In some embodiments, the first angle “A1” can be about 90° (e.g., vertical), about 45°, from about 45° to about 90°, for example, from about 60° to about 85°, for example, from about 70° to about 80°, and all ranges and subranges therebetween. In some embodiments, the first angle “A1” can be about 135°, from about 90° to about 135°, for example, from about 95° to about 120°, for example, from about 100° to about 110°, and all ranges and subranges therebetween. The gas knife 218 can be designed to dispense gas against the major surfaces 60, 62 of the glass sheet 42 to remove liquid from the major surfaces 60, 62 of the glass sheet 42. Suitable gases include, but are not limited to, air, nitrogen, low humidity gases, and the like.
As further illustrated, the drying station 54 can optionally include a second liquid dispenser 222 including a second liquid nozzle 224 oriented to rinse the major surfaces 60, 62 of the glass sheet 42 at a location upstream (e.g., along travel direction T) from the gas knife 218. In some embodiments, the second liquid dispenser 222 can include a lower pressure liquid stream when compared to the pressure of the liquid stream generated by the first liquid dispenser 204 in the washing station 52. Indeed, the lower pressure liquid stream of the second liquid dispenser 222 can flood the major surfaces 60, 62 of the glass sheet 42 to remove any detergents, chemicals, debris, or other impurities remaining on the glass sheet 42. As shown, in some embodiments, a deflector 226 can be positioned downstream (e.g., along travel direction T) from the second liquid dispenser 222 and upstream from the gas knife 218. The deflector 226 can be oriented to direct an amount of liquid from the second liquid dispenser 222 away from the gas knife 218. As shown, the deflector 226, such as a wiper blade, may be oriented at a second angle “A2” relative to the travel direction T of the glass sheet 104. As shown, the first angle “A1” and the second angle “A2” can be substantially equal to one another; however, such a depiction, unless otherwise noted, should not limit the scope of the claims appended herewith as different angles (oblique, acute, etc. to the direction of travel) may be provided in some embodiments. Moreover, as shown, the second liquid dispenser 222 may likewise optionally include a second liquid nozzle 224 (e.g., an elongated liquid nozzle) oriented at a similar or identical angle of the deflector 226 and the gas knife 218 relative to the travel direction T of the glass sheet 42. The deflector 226 can direct liquid from the second liquid dispenser 222 downward and away from the gas knife 218, thereby reducing the amount of liquid that the gas knife 218 is required to remove from the glass sheet 42.
Although features of
Returning to
Upon exiting the drying station 54, additional processes can be performed on the dried glass sheet 42. For example, in some non-limiting embodiments, a coating can be applied to the glass sheet 42 as described, for example, in PCT Publication No. WO 2017/034978, published Mar. 2, 2017, the entirety of which is incorporated herein by reference. Other processing can optionally include packaging, storage and/or shipping.
Returning to
Referring now to
approximately the softening point of the glass to the strain point of the glass. Below the strain point, the glass is considered to behave elastically.
In operation, batch materials for forming glass are introduced into the melting vessel 250 as indicated by arrow 264 and are melted to form molten glass 266. The molten glass 266 flows into the fining vessel 252, which is maintained at a temperature above that of the melting vessel 250. From the fining vessel 252, the molten glass 266 flows into the mixing vessel 254, where the molten glass 266 undergoes a mixing process to homogenize the molten glass 266. The molten glass 266 flows from the mixing vessel 254 to the delivery vessel 256, which delivers the molten glass 266 through a downcomer 268 to an inlet 270 and into the forming apparatus 258.
The forming apparatus 258 depicted in
The separating apparatus 32 can include a glass separator 300. A variety of glass separators 300 may be provided in embodiments of the present disclosure. For example, a traveling anvil machine may be provided that can score and then break the glass ribbon 262 along the score line. In some embodiments, the glass separator 300 can include a robot (e.g., a robotic arm) oriented to bend the glass sheet 42 relative to the glass ribbon 262 to separate the glass sheet 42 from the glass ribbon 262 along a transverse separation path 301 corresponding to the score line. In some embodiments, a scribe 302 (e.g., score wheel, diamond tip, etc.) can be utilized as understood by those of ordinary skill. In some embodiments, a laser-assisted separation device 303 may be provided as described below and also in U.S. application Ser. No. 14/547,688, filed Nov. 19, 2014, the entirety of which is incorporated herein by reference. Such laser-assisted separation devices can include, but are not limited to, laser scoring techniques that heat the glass ribbon 262 and then cool the glass ribbon 262 to create a vent in the glass ribbon 262 to separate the glass ribbon 262. Such laser-assisted separation devices may also include laser cutting techniques that heat the glass ribbon 262 to produce a stressed region in the glass ribbon 262 and then apply a defect to the stressed region of the glass ribbon 262 to initiate a crack to separate the glass ribbon 262.
In some embodiments, the separation apparatus 32 can separate an outer portion 304 of the glass sheet 42 from a central portion 306 of the glass sheet 42 along a vertical separation path 308 that extends along a length “L” between a first transverse edge 310 of the glass sheet 42 and a second transverse edge 312 of the glass sheet 42. As illustrated, such a technique can be carried out in a vertical orientation, although horizontal orientations may be provided in some embodiments. In some embodiments, a vertical orientation may facilitate the carrying away of glass particles by gravity, thereby reducing or preventing contamination of the otherwise pristine major surfaces of the glass ribbon 262.
Other optional features provided or performed by the separation apparatus 32 are described, for example, in PCT Publication No. 2017/024978, published Mar. 2, 2017, the entirety of which is incorporated herein by reference. Regardless, following processing at the separation apparatus, the glass sheet 42 is delivered (e.g., immediately delivered) to the handling apparatus 34 (
Embodiments and advantages of features of the present disclosure are further illustrated by the following non-limiting examples, but the particular materials, amounts, dimensions, conditions and other details thereof recited in these examples should not be construed to unduly limit the scope of the present disclosure.
To evaluate the glass sheet stabilization apparatuses and methods of the present disclosure, a pre-positioning station akin to the pre-positioning station 50 described above with respect to
A test glass sheet was obtained and vertically oriented between the liquid spray assembly and the gas stream directing assembly. A first major surface of the test glass sheet faced the liquid spray assembly, and the opposing, second major surface of the test glass sheet faced the gas stream directing assembly. A distance between the first major surface and the orifices of the liquid spray assembly was 1 mm. A distance between the second major surface and the tips of the nozzles of the gas stream directing device was 5 mm. The Example pre-positioning station was then operated to direct water flow onto the first major surface (via the liquid spray assembly) and air flow onto the second major surface (via the gas stream directing assembly), including with different tests being performed at different flow rates of water provided to the liquid spray assembly as described below. During all testing, a total flow rate to the gas stream directing device was 500 SLPM (distributed evenly among the six air nozzles). The glass sheet was delivered to the Example pre-positioning station at a conveyance speed of 30 m/min, and was transported from the Example pre-positioning station at a conveyance speed of 20 m/min. The position of the first major surface relative to the liquid spray assembly was recorded at each of the six ultrasonic position sensors. Testing was performed at water flow rates of 1 gal/min, 1.5 gal/min and 2 gal/min. It was visually observed that in all instances, the glass sheet never touched the liquid spray assembly, and the liquid bearing established by the liquid spray assembly was able to support the glass sheet even when the overhead grippers were released. A summary of the test results is provided in Tables 1, 2, and 3 below (all numeric values are in mm). Negative position values are reported because the position sensors were mounted on the side facing the first major face of the test glass sheet, and the reading was reset to zero when the glass sheet was manually pushed toward the gas stream directing assembly.
From the results of Tables 1-3, the standard deviations were relatively small, indicating that the glass sheet was well stabilized. Among the three cases corresponding to the different water flow rates, testing performed at 1.5 gal/min resulted in the best overall sheet stability. Further increasing the flow rate to 2 gal/min offered minimal additional improvement in stability; it became difficult to engage the water bearing because the water jets impinging on the test glass sheet resulted in a large repulsive force as the water bearing approached the sheet from a greater distance, which had the tendency to push the glass sheet away.
Additional testing was performed using the Example pre-positioning station and testing protocols of Example 1, except that the engage position of the liquid spray assembly was offset by 1 mm towards the glass sheet undergoing testing so that the water bearing surface position coincided with a conveyor centerline position. With this arrangement, it was expected that the liquid spray assembly would come into contact with the glass sheet in the absence of liquid spray. A summary of the results of Example 2 are provided in Tables 4 and 5 below.
From the results shown in Tables 4 and 5, the water bearing provided adequate support to the glass sheet, and glass sheet did not come into contact with the liquid spray assembly.
The handling apparatuses, processing stations, glass manufacturing systems, and methods of the present disclosure provide a marked improvement over previous designs. By stabilizing a vertically oriented glass sheet immediately prior to delivery to a washing station, the likelihood of undesirable contact between surfaces of the glass sheet and components of the washing station can be avoided, and can be done on an in-line basis. The single-sided liquid bearing with optional gas stream delivery pre-positioning stations and methods of the present disclosure offer significant process capability and flexibility to achieve the stabilizing and flattening of glass sheet. The single-sided liquid bearing can provide both repulsive and attractive forces and is inherently stable once engaged. Further, a liquid bearing (e.g., water bearing) can provide more cooling capacity (as compared to an air bearing), which can be expected to facilitate flattening of an above room temperature glass sheet.
Various modifications and variations can be made to the embodiments described herein without departing from the scope of the claimed subject matter. Thus it is intended that the specification cover the modifications and variations of the various embodiments described herein provided such modifications and variations come within the scope of the appended claims and their equivalents.
This application claims the benefit of priority under 35 U.S.C. § 119 of U.S. Provisional Application Ser. No. 62/568,985 filed on Oct. 6, 2017, the content of which is relied upon and incorporated herein by reference in its entirety.
Filing Document | Filing Date | Country | Kind |
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PCT/US2018/053888 | 10/2/2018 | WO | 00 |
Number | Date | Country | |
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62568985 | Oct 2017 | US |