Method and apparatus for forming curved glass by differential heating of glass sheets
阅读说明:本技术 通过玻璃板的差温加热形成曲面玻璃的方法和设备 (Method and apparatus for forming curved glass by differential heating of glass sheets ) 是由 阿努拉格·贾恩 尼古拉斯·潘泰利斯·克拉迪亚斯 郑哲明 于 2018-04-27 设计创作,主要内容包括:本文提供了一种用于由玻璃材料板形成曲面玻璃制品的方法和系统。所述方法和系统包括将玻璃板支撑在成型框架上并且然后在由所述成型框架支撑的同时加热所述玻璃材料板,以使得所述玻璃材料板的中心区域变形成弯曲框架的开放的中心空腔。所述方法和/或系统被配置成使得所述玻璃材料板的外部区域所经历的加热的方面小于所述玻璃材料板的所述中心区域所经历的加热的方面。所述加热的方面可以是申请人认为可以减少成型操作期间的某些缺陷的平均温度、最大温度和/或加热速率。(A method and system for forming a curved glass article from a sheet of glass material is provided herein. The method and system include supporting a glass sheet on a forming frame and then heating the sheet of glass material while supported by the forming frame such that a central region of the sheet of glass material is deformed into an open central cavity of a curved frame. The method and/or system is configured such that an aspect of heating experienced by an outer region of the sheet of glass material is less than an aspect of heating experienced by the central region of the sheet of glass material. The aspect of the heating may be that the applicant believes that the average temperature, maximum temperature and/or heating rate of certain defects during the forming operation may be reduced.)
1. A method for forming a curved glass article from a sheet of glass material, the method comprising:
placing an outer region of the sheet of glass material in contact with a support surface of a shaping frame, the shaping frame defining an open central cavity at least partially surrounded by the support surface;
supporting the sheet of glass material with the forming frame by contact between the sheet of glass material and the support surface such that a central region of the sheet of glass material is suspended over the open central cavity of the forming frame;
heating the sheet of glass material while supported by the forming frame such that the central region of the sheet of glass material deforms into the open central cavity in a direction away from the support surface of the forming frame, wherein an aspect of the heating experienced by the outer region of the sheet of glass material is less than an aspect of the heating experienced by the central region of the sheet of glass material; and
cooling the sheet of glass material after heating to form the curved glass article from the sheet of glass material.
2. The method of claim 1, wherein the aspect of heating is an average temperature during a heating step, and the average temperature during the heating step of the outer region of the sheet of glass material is less than the average temperature of the central region of the sheet of glass material during the heating phase.
3. The method of claim 2, wherein the average temperature during the heating step of the outer region of the sheet of glass material is at least 30 ℃ less than the average temperature of the central region of the sheet of glass material during the heating step.
4. The method of claim 2 or 3, wherein the different average temperatures between the outer region and the central region of the sheet of glass material during the heating step result from: heat is conducted from the outer region of the sheet of glass material and into the forming frame by the contact between the outer region of the sheet of glass material and the support surface.
5. The method of claim 1, wherein the aspect of heating is a heating rate during the heating step, and the heating rate during the heating step of the outer region of the sheet of glass material is less than the heating rate of the central region of the sheet of glass material during the heating step.
6. The method of claim 1, wherein the aspect of heating is a maximum temperature during the heating step, and the maximum temperature during the heating step of the outer region of the sheet of glass material is less than the maximum temperature of the central region of the sheet of glass material during the heating phase.
7. The method of any of claims 1 to 6, wherein the forming frame is formed of a material having a low thermal diffusivity.
8. The method of claim 7, wherein the low thermal diffusivity is less than 2 x 10-5m2/s。
9. The method of claim 7, wherein the low thermal diffusivity is less than 4 x 10-6m2/s。
10. The method of any one of claims 1 to 9, wherein the forming frame is formed from walls surrounding the open central cavity, the walls comprising an upper surface defining the support surface, an inner surface defining the open central cavity, an outer surface opposite the inner surface, and a bottom surface opposite the support surface, wherein an average width of the walls measured between the inner and outer surfaces is greater than 3mm and an average height of the walls measured between the support surface and the bottom surface is greater than 20 mm.
11. The method of any one of claims 1 to 9, wherein the forming frame is formed from walls having an upper surface defining the support surface, an inner surface defining the open central cavity, an outer surface opposite the inner surface, and a bottom surface opposite the support surface, wherein the walls have a tapered shape such that an average outer width measured across the support surface is less than an average outer width measured across the bottom surface.
12. The method of claim 11, wherein the wall is formed from a solid continuous section of metallic material.
13. The method of claim 11, wherein the wall is formed from a plurality of panels removably coupled together to form the wall.
14. The method of any of claims 1 to 13, wherein gravity causes the sheet of glass material to deform during heating and the support surface is an upwardly facing surface.
15. The method of any of claims 1-14, wherein the glass panel is sized to form an automotive window.
16. A system for forming a curved glass article from a sheet of glass material, the system comprising:
a support ring including an inner surface facing radially inward, the inner surface defining an open central cavity; a surface facing radially outward; an upper surface surrounding the open central cavity at an upper end of the support ring; and a bottom surface opposite the upper surface, wherein the sheet of glass material is supported from the upper surface of the support ring with a central region of the sheet of glass material suspended over the open central cavity of the support ring; and
a heating stage having a heating chamber, the support ring being located within the heating chamber and the heating stage being configured to heat the support ring and the sheet of glass material such that a central region of the sheet of glass material flows downwardly under gravity into the open central cavity;
wherein the support ring is configured to conduct heat away from the sheet of glass material by contact with the sheet of glass material at the upper surface such that an aspect of heating experienced by a portion of the sheet of glass material in contact with the upper surface of the support ring is less than an aspect of heating experienced by the central area of the sheet of glass material.
17. The system of claim 16, wherein the support ring is formed of a material having a low thermal diffusivity.
18. The system of claim 17, wherein the low thermal diffusivity is less than 2 x 10-5m2/s。
19. The system of claim 17, wherein the low thermal diffusivity is less than 4 x 10-6m2/s。
20. The system of any of claims 16 to 19, wherein an average width of the support ring measured between the radially inward facing surface and the radially outward facing surface is greater than 3mm, and an average height of the support ring measured between the upper surface and the bottom surface is greater than 20 mm.
21. The system of any of claims 16 to 20, wherein the support ring has a tapered shape such that an average outer width measured across the upper surface is less than an average outer width measured across the bottom surface.
22. The system of any of claims 16 to 21, wherein the support ring is formed from a solid continuous section of metallic material.
23. The system of any of claims 16 to 21, wherein the support ring is formed from a plurality of panels removably coupled together to define the support ring.
24. A curved glass article made by the method and/or system disclosed herein, made by the method of any one of claims 1-15, or made by the system of claims 16-23.
Background
The present disclosure relates generally to forming curved glass articles, and in particular to methods of forming curved glass articles with a forming frame using differential heating. Curved glass sheets or articles may be used in many applications, particularly for vehicle or automotive window glass. Typically, curved glass sheets for such applications are formed from relatively thick sheets of glass material. Applicants have discovered that conventional forming processes can produce a variety of undesirable characteristics in curved glass sheets (e.g., edge wrinkling, excessive sagging at the glass edges, etc.) that appear to increase in severity as the thickness of the glass sheet decreases.
Disclosure of Invention
One embodiment of the present disclosure is directed to a method for forming a curved glass article from a sheet of glass material. The method includes placing an outer region of a sheet of glass material in contact with a support surface of a forming frame defining an open central cavity at least partially surrounded by the support surface. The method includes supporting a sheet of glass material with a forming frame by contact between the sheet of glass material and a support surface such that a central region of the sheet of glass material is suspended over an open central cavity of the forming frame. The method includes heating a sheet of glass material while supported by a forming frame such that a central region of the sheet of glass material deforms into an open central cavity in a direction away from a support surface of the forming frame. An outer region of the sheet of glass material experiences a lesser aspect of heating than a central region of the sheet of glass material. The method includes cooling the sheet of glass material after heating to form a curved glass article from the sheet of glass material.
An additional embodiment of the present disclosure is directed to a system for forming a curved glass article from a sheet of glass material. The system includes a support ring. The support ring includes an inner surface facing radially inward, the inner surface defining an open central cavity; a surface facing radially outward; an upper surface surrounding an open central cavity at an upper end of the support ring; and a bottom surface opposite the upper surface. The sheet of glass material is supported from an upper surface of the support ring with a central region of the sheet of glass material suspended over an open central cavity of the support ring. The system includes a heating station having a heating chamber. The support ring is positioned within the heating chamber and the heating stage is configured to heat the support ring and the sheet of glass material such that a central region of the sheet of glass material flows downwardly under the force of gravity into the open central cavity. The support ring is configured to conduct heat away from the sheet of glass material by contact with the sheet of glass material at the upper surface such that an aspect of heating experienced by a portion of the sheet of glass material in contact with the upper surface of the support ring is less than an aspect of heating experienced by a central area of the sheet of glass material.
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 as described in the written description and claims hereof, as well as the appended drawings.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and are intended to provide an overview or framework for understanding the nature and character of the claims.
The accompanying drawings are included to provide a further understanding, 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 operations of the various embodiments.
Drawings
FIG. 1 is a cross-sectional view showing a glass sheet supported by a high thermal mass bending ring according to an example embodiment.
FIG. 2 is a cross-sectional view showing a glass sheet supported within a heating stage by a high thermal bend ring according to an exemplary embodiment.
FIG. 3 is a detailed view of a contact location between a glass sheet and a high thermal mass bending ring according to an example embodiment.
FIG. 4 is a perspective view of a high thermal mass flex ring according to an exemplary embodiment.
FIG. 5 is a perspective view of a high thermal mass flex ring according to an exemplary embodiment.
Detailed Description
Referring generally to the drawings, various embodiments of a system and method for shaping, bending or sagging glass material are shown and described. Generally, the systems and methods discussed herein provide differential heating between the center of the glass sheet and the outer portions of the support of the glass sheet. As will be discussed in detail herein, applicants believe that such differential heating will improve the quality of the shaped or curved, curved glass article.
In some glass forming methods, one or more glass sheets are supported on a bending ring and the glass sheets are heated to near their softening temperature. The glass sheet is formed into a curved shape as gravity pulls the center of the softened glass down into the curved ring. Applicants have discovered that certain defects, such as edge wrinkling and sharp sagging (commonly referred to in the industry as "bathtub defects") near the edges of glass sheets, can be a problem during gravity sagging of large thin glass sheets (e.g., thin chemically strengthened glass, such as gorella glass from ComingIncorporated, inc., can be used in a variety of applications, such as vehicle or automotive windows). Applicants have discovered that defects such as edge wrinkles and bathtub defects can be reduced by reducing the heating aspects (e.g., temperature, heating rate, etc.) experienced by the outer portions of the glass sheet rather than the central portion of the glass sheet.
In particular, the applicant has carried out studies relating to the cause of bathtub defects which show that the film stress present during bending is highest in the centre of the glass sheet and decreases to zero at the edges. These film stresses stiffen the middle of the sheet, resulting in insufficient sag at the center relative to the edges. On the other hand, the edges of the glass sheets sag excessively due to low film stress under gravity load. In general, applicants have found that bathtub defects can be addressed by: the glass sheet is differentially heated at a higher center region temperature and a lower edge region temperature, resulting in an overall thermal gradient from center to edge.
Edge wrinkling (also known in the industry as buckling) is a mechanical instability that manifests as a sudden change in structure due to bifurcations associated with a loss of structural stability. Wrinkling is triggered by compressive stress reaching above a critical threshold that depends primarily on the stiffness of the glass edges, which in turn depends on the thickness of the glass sheet and the modulus and viscosity of the glass at that temperature. Applicants have utilized numerical modeling to show that wrinkling can be mitigated by increasing edge stiffness by establishing a local thermal gradient near the glass edge, where the glass edge area is locally cooler than the center of the glass sheet. The local gradient at the edge of the glass effectively increases the glass viscosity and modulus at the edge of the glass and thus increases its bending stiffness under edge compressive stress. This, in turn, reduces the likelihood of edge wrinkles forming.
While a variety of methods and processes for generating different temperatures between the edge and the center of the glass sheet can be used, in the particular embodiments discussed herein, the temperature gradient is generated by supporting the glass sheet on a high thermal mass bending ring. The flex ring discussed herein is designed to have a relatively large thermal mass as compared to common flex rings that are typically intentionally designed to have a low thermal mass (e.g., small, lightweight, made of materials with low thermal conductivity, having a variety of vias, etc.). The high thermal mass bending ring conducts heat away from the area near the edge of the glass sheet due to contact with the edge of the glass sheet, resulting in a lower glass temperature at the edge than at the center. As discussed above, this temperature gradient is believed to reduce both edge wrinkling and bathtub defects.
Referring to fig. 1 and 2, a system and method for forming a curved glass article according to an exemplary embodiment is shown. Generally, the
As shown in fig. 1, the
To begin the forming process, the
The
After a period of time is determined that allows the
In a common process, the glass sheet and the support bending ring are heated at substantially the same rate and to the same temperature during the heating phase of the forming process. As discussed above, applicants have determined that by differentially heating the outer and
In certain embodiments, the
In another particular embodiment, the
While there are a number of potential ways to produce these differential heating aspects, particularly the particular embodiments discussed herein, the bending
In a particular embodiment, the high thermal
TABLE 1
Instead of, or in addition to, utilizing a low thermal diffusivity material, the bending
As shown in fig. 3, the
As shown in fig. 3, the
In addition to increasing the material used to form the
Further, as shown in fig. 4, the bending
Referring to FIG. 5, in another embodiment, the
In various embodiments, the
The
In particular embodiments,
Examples of glass materials and Properties
In various embodiments, the
Another example of a suitable glass composition for use in
Another example of a suitable glass composition for use in
In certain embodiments, alkali aluminosilicate glass compositions suitable for use in
In another embodiment,
In an alternative embodiment,
In other embodiments, the
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In some embodiments,
In some embodiments, the glass composition of
The
In one or more embodiments, when the
In one or more embodiments, the
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Unless expressly stated otherwise, it is intended that any method set forth herein be construed in no way as requiring that its steps be performed in a specific order. Thus, where a method claim does not actually recite an order to be followed by its steps or it is not otherwise specifically stated in the claims or descriptions that the steps are to be limited to a specific order, it is no way intended that any particular order be inferred. In addition, as used herein, the articles "a" and "an" are intended to include one or more than one component or element, and are not intended to be construed as meaning only one.
It will be apparent to those skilled in the art that various modifications and variations can be made in the disclosed embodiments without departing from the spirit or scope of the embodiments. Since modifications, combinations, sub-combinations and variations of the disclosed embodiments incorporating the spirit and substance of the embodiments may occur to persons skilled in the art, the disclosed embodiments should be construed to include everything within the scope of the appended claims and their equivalents.
An aspect (1) of the present disclosure relates to a method for forming a curved glass article from a sheet of glass material, the method comprising: placing an outer region of a sheet of glass material in contact with a support surface of a forming frame, the forming frame defining an open central cavity at least partially surrounded by the support surface; supporting the sheet of glass material with a forming frame by contact between the sheet of glass material and a support surface such that a central region of the sheet of glass material is suspended over an open central cavity of the forming frame; heating the sheet of glass material while supported by the forming frame such that a central region of the sheet of glass material deforms into the open central cavity in a direction away from the support surface of the forming frame, wherein an outer region of the sheet of glass material experiences a lesser aspect of heating than a central region of the sheet of glass material; and cooling the sheet of glass material after heating to form a curved glass article from the sheet of glass material.
Aspect (2) of the present disclosure relates to the method of aspect (1), wherein the aspect of heating is an average temperature during the heating step, and an average temperature during the heating step of the outer region of the sheet of glass material is less than an average temperature of the central region of the sheet of glass material during the heating step.
Aspect (3) of the present disclosure relates to the method of aspect 2, wherein an average temperature during the heating step of the outer region of the sheet of glass material is at least 30 ℃ less than an average temperature of the central region of the sheet of glass material during the heating stage.
Aspect (4) of the present disclosure relates to the method of aspect (2) or aspect (3), wherein the different average temperatures between the outer region and the central region of the sheet of glass material during the heating step are produced by: heat is conducted from the outer region of the sheet of glass material and into the forming frame by contact between the outer region of the sheet of glass material and the support surface.
Aspect (5) of the present disclosure relates to the method of aspect (1), wherein the aspect of heating is a heating rate during the heating step, and the heating rate during the heating step of the outer region of the sheet of glass material is less than the heating rate of the central region of the sheet of glass material during the heating step.
Aspect (6) of the present disclosure relates to the method of aspect (1), wherein the aspect of heating is a maximum temperature during the heating step, and the maximum temperature during the heating step of the outer region of the sheet of glass material is less than the maximum temperature of the central region of the sheet of glass material during the heating step.
Aspect (7) of the present disclosure relates to the method of any one of aspects (1) to (6), wherein the mold frame is formed of a material having low thermal diffusivity.
Aspect (8) of the present disclosure relates to the method of aspect (7), whereinThe low thermal diffusivity is less than 2 x 10-5m2/s。
Aspect (9) of the present disclosure relates to the method of aspect (7), wherein the low thermal diffusivity is less than 4 x 10-6m2/s。
Aspect (10) of the present disclosure relates to the method of any one of aspects (1) to (9), wherein the forming frame is formed by walls surrounding an open central cavity, the walls including an upper surface defining a support surface, an inner surface defining the open central cavity, an outer surface opposite the inner surface, and a bottom surface opposite the support surface, wherein an average width of the walls measured between the inner and outer surfaces is greater than 3mm and an average height of the walls measured between the support surface and the bottom surface is greater than 20 mm.
Aspect (11) of the present disclosure relates to the method of any one of aspects (1) to (9), wherein the forming frame is formed by a wall having an upper surface defining a support surface, an inner surface defining an open central cavity, an outer surface opposite the inner surface, and a bottom surface opposite the support surface, wherein the wall has a tapered shape such that an average outer width measured across the support surface is less than an average outer width measured across the bottom surface.
Aspects (12) of the present disclosure relate to the method of aspect (11), wherein the wall is formed from a solid continuous section of metallic material.
Aspects (13) of the present disclosure relate to the method of aspect (11), wherein the wall is formed from a plurality of panels removably coupled together to form the wall.
Aspect (14) of the present disclosure relates to the method of any one of aspects (1) to (13), wherein gravity causes the sheet of glass material to deform during heating, and the support surface is an upwardly facing surface.
Aspect (15) of the present disclosure relates to the method of any one of aspects (1) to (14), wherein the glass sheet is dimensioned to form an automotive window.
Aspects (16) of the present disclosure relate to a system for forming a curved glass article from a sheet of glass material, the system comprising: a support ring including an inner surface facing radially inward, the inner surface defining an open central cavity; a surface facing radially outward; an upper surface surrounding an open central cavity at an upper end of the support ring; and a bottom surface opposite the upper surface, wherein the sheet of glass material is supported from the upper surface of the support ring, wherein a central region of the sheet of glass material is suspended over the open central cavity of the support ring; and a heating stage having a heating chamber, the support ring being located within the heating chamber and the heating stage being configured to heat the support ring and the sheet of glass material such that a central region of the sheet of glass material flows downwardly under gravity into the open central cavity; wherein the support ring is configured to conduct heat away from the sheet of glass material by contact with the sheet of glass material at the upper surface such that an aspect of heating experienced by a portion of the sheet of glass material in contact with the upper surface of the support ring is less than an aspect of heating experienced by a central region of the sheet of glass material.
Aspects (17) of the present disclosure relate to the system of aspect (16), wherein the support ring is formed of a material having a low thermal diffusivity.
Aspects (18) of the present disclosure relate to the system of aspect (17), wherein the low thermal diffusivity is less than 2 x 10- 5m2/s。
Aspect (19) of the present disclosure relates to the system of aspect (17), wherein the low thermal diffusivity is less than 4 x 10- 6m2/s。
An aspect (20) of the present disclosure relates to the system of any one of aspects (16) through (19), wherein an average width of the support ring measured between the radially inward facing surface and the radially outward facing surface is greater than 3mm, and an average height of the support ring measured between the upper surface and the bottom surface is greater than 20 mm.
An aspect (21) of the present disclosure relates to the system of any one of aspects (16) to (20), wherein the support ring has a tapered shape such that an average outer width measured over an entire upper surface is less than an average outer width measured over an entire bottom surface.
Aspects (22) of the present disclosure relate to the system of any one of aspects (16) to (21), wherein the support ring is formed from a solid, continuous section of metallic material.
Aspects (23) of the present disclosure relate to the system of any one of aspects (16) to (21), wherein the support ring is formed from a plurality of panels removably coupled together to define the support ring.
Aspects (24) of the present disclosure relate to a curved glass article made from the methods and/or systems disclosed herein, made from the method of any one of aspects (1) through (15), or made from the system of aspects (16) through (23).
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