WO2017091990A1

WO2017091990A1 - Vacuum-molding apparatus for bend molding glass and methods for the use thereof

Info

Publication number: WO2017091990A1
Application number: PCT/CN2015/096224
Authority: WO
Inventors: Eric Chan; Frank Hung; Jack Y. DING; Jason Yan; David Chang
Original assignee: Kornerstone Materials Technology Co Ltd
Current assignee: Kornerstone Materials Technology Co Ltd
Priority date: 2015-12-03
Filing date: 2015-12-03
Publication date: 2017-06-08
Anticipated expiration: 2018-06-03
Also published as: CN108137371A; TWI705944B; TW201722871A; HK1255043A1

Abstract

A vacuum-molding apparatus for bend molding glass and a method of bend molding glass are disclosed. The vacuum-molding apparatus includes a mold protection device that protects a mold from oxidation and increases the life span of a mold. Injection of inert gas can also increase the life span of the mold.

Description

VACUUM-MOLDING APPARATUS FOR BEND MOLDING GLASS AND METHODS FOR THE USE THEREOF

Field of the Invention

The present invention relates to a vacuum-molding apparatus for bend molding glass and methods of bend molding glass using the vacuum-molding apparatus. The vacuum-molding apparatus may find application in manufacturing curved glasses and flat glasses having curved portions.

Background

Touch glass, large screens, and their applications have achieved wide market coverage. As such, there is an increasing demand for curved formed glass. The formation of curved glass is largely controlled by the glass transition temperature (T_g) and the softening temperature (T_s) of the glass in question. Generally, T_g is lower than 545℃and T_s is lower than 765℃.

One of the most common techniques for forming curved glass is bend molding. During typical bend molding, the portion of a glass object to be bent is softened by heating, and then a gas injection system applies a force to change the shape of the glass object. A bend molded object is formed as the glass cools. Bend molding by injection system, however, requires precise injection control. Otherwise, the process will affect the physical properties of the glass. A precise injection control system, however, is costly and will rapidly deteriorate due to operation at high temperatures for long periods of time.

Another method is to soften the glass first, bend the glass object using upper and lower molds, and then cool the glass object to form the bent glass. Bend molding by mold press, however, requires alignment of the upper and lower molds and complete lamination between the glass and mold, which increases the difficulties associated with the mold design and process.

Vacuum-assisted molding is widely applied in forming plastics. In vacuum-assisted molding, the object is preheated to a certain working temperature, a vacuum is formed between the mold and the object by a vacuum system, force is used to shape the object, and the object is finally cooled or annealed according to the properties, conditions, and material requirements of the object to achieve design requirements.

The life span of the mold and effects on the mold due to high temperatures and high pressures are rarely considered in vacuum-molding technology. The mold can be easily damaged when it is heated to high temperatures during vacuum-molding. Accordingly, there is a need for an apparatus and method that is designed to bend mold glass, while protecting the mold.

Summary

According to several exemplary embodiments, the present invention provides a vacuum-molding apparatus. The vacuum-molding apparatus includes a mold having a shaped surface and a plurality of suction holes, a mold protection device that covers the mold, a vacuum system that creates a vacuum in an inner space of the mold, and a glass heating device that heats a glass object.

According to several exemplary embodiments, the present invention provides another vacuum-molding apparatus. The vacuum-molding apparatus includes a mold having a shaped surface and a plurality of suction holes disposed non-uniformly on the mold, a mold protection device that covers the mold and is movable to adjust a positive pressure applied to a glass object, a vacuum system that creates a vacuum in an inner space of the mold, and a glass heating device configured to heat the glass object with more thermal energy on the edges of the glass object.

According to several exemplary embodiments, the present invention further provides a method of bend molding a glass object. The method includes covering a mold with a mold protection device, protecting the mold from oxidation by forming an inert gas environment, heating a glass object to a working temperature to provide a heated glass object, creating a vacuum in an inner space of the mold while a positive pressure is present in an outer space of the mold to bend form the heated glass object to provide a molded glass object, and cooling the molded glass object.

Brief Description of the Drawings

Figure 1A is a schematic depiction of an embodiment of a vacuum-molding apparatus for making curved glass according to the present invention；

Figure 1B is a schematic depiction of a vacuum-molding apparatus with a movable protection device for making curved glass according to the present invention；

Figure 2 illustrates a mold having a shaped surface and suction holes for making curved glass according to the present invention.

Figure 3 is a stereogram of an embodiment of a glass heating apparatus of a vacuum-molding apparatus for making curved glass according to the present invention； and

Figure 4 contains a flow chart of an embodiment of a vacuum-molding method using a vacuum-molding apparatus for making curved glass according to the present invention.

Detailed Description

The term “working temperature” refers to the temperature at which a heated glass object can be safely bent and molded. Unless otherwise noted, the working temperature is between the glass transition temperature (T_g) and the softening temperature (T_s) of the glass being molded.

The term “shaped surface” refers to a surface area of the mold that is at least partially curved or non-planar. The phrase “on the shaped surface” refers to a location that is within the area defined by the shaped surface and on the surface of the shaped surface, such that the part of the mold in question is capable of interacting with the glass being bend molded.

The term “2 D” refers to a surface that is flat.

The term “2.5 D” refers to a surface that is predominately flat, but contains at least one curved portion.

The term “3D” refers to a surface that is predominately curved.

The terms “2 D, ” “2.5 D, ” and “3D” can be applied to glass sheets, where the terms will refer to a flat glass, a predominately flat glass, and a predominately curved glass, respectively.

The vacuum-molding apparatus described herein is capable of bend forming glass into a shape by using heat to soften the glass and differential pressure (suction and/or injected air) to force the softened glass into contact with the shaped surface of a mold. The mold is encased in a mold protection device that is capable of providing a vacuum, injecting inert gas, and applying localized heat to the glass during the molding process. A benefit of providing a vacuum or inert gas during bend molding is to reduce the oxidation and damage that would occur to the mold when bend molding glass at high temperatures in open air. The vacuum-molding apparatus and its associated methods of use protect the mold by forming an inert gas environment or vacuum around the mold to increase the life span of the mold.

Referring now to the drawings, a vacuum-molding apparatus 100 is shown in FIG. 1A. As shown in FIG. 1A, the vacuum-molding apparatus 100 includes a mold 110 having a shaped surface with one or more suction holes disposed in the shaped surface and a mold protection device 120. According to several exemplary embodiments, the mold 110 includes graphite, silicon carbide, stainless steel, or a combination thereof. In other exemplary embodiments, the mold 110 is made of a suitable material (such as steel) with a coated surface of a different material, such as a coated surface of graphite, silicon carbide, stainless steel, or a combination thereof. These materials can help prevent adhesion between the mold 110 and a molded glass object.

FIG. 2 illustrates a mold 200 having a shaped surface 210 and having suction holes 220 on the mold 200. In some embodiments, the suction holes 220 are designed with a non-uniform distribution for an enhanced molding effect. Particularly, on the shaped surface, a region with a higher curvature is a region that needs more bending during the molding and is designed to have more suction holes. Higher curvature means a higher bending (or curving) level. For example, the shaped surface 210 has a first region with a first curvature and a second region with a second curvature that is less than the first curvature. The density of the suction holes in the first region is greater than the density of the suction holes in the second region. The density of the suction holes in a region is defined as a number of the suction holes over the area of the region. As shown in FIG. 2, the shaped surface 210 includes a first region 210A (defined by two dashed lines) with a first curvature C1； a second region 210B (defined by two dashed lines) with a second curvature C2； and a third region 210C with a third curvature C3, where C3<C2<C1. The densities of the suction holes in those regions are D1, D2 and D3, respectively. Accordingly, D3<D2<D1. This advantageously creates a higher vacuum (therefore lower pressure) between the glass and the mold in a higher curvature region so that the glass is pressed with a greater force against the mold to more closely conform to the shape of the mold. The force on the glass is determined by a difference between pressures that are respectively applied to two surfaces of the glass.

Turning back to FIG. 1A, the mold 110 includes a mold main part 112 and a plurality of air passages 114 distributed in the mold main part 112. Mold protection device 120 covers the mold 110 and defines a closed space so that the shaped surface 210 is protected therein. When a glass object 115 (such as a flat glass object) is placed on the shaped surface 210, the glass object 115 divides the space between the mold protection device 120 and mold 110 into upper space 121 and lower space 118. The upper space 121 and lower space 118 can connect through a gap (not shown) between the flat glass object 115 and the mold 110.

The one or more suction holes in the mold 110 are operatively connected to the air passages 114 to exert suction on flat glass object 115. The suction exerted on flat glass object 115 can force the flat glass object 115 to conform to the contours of the shaped surface of the mold 110. By applying suction to flat glass object 115, a molded glass object is produced that has more precise angles and thickness than if suction is not applied.

Also, as shown in FIG. 1A, the vacuum-molding apparatus 100 includes a pneumatic pump 130, upper vacuum system 140, and lower vacuum system 150. To protect main mold part 112, pneumatic pump 130 can selectively inject inert gas (e.g., nitrogen or argon) into upper space 121 and lower space 118 through air passage 131. Upper vacuum system 140 can create a vacuum in upper space 121 and lower space 118 through upper vacuum system passage 141 to protect main mold part 112 from oxidation. Lower vacuum system 150 can create a vacuum in lower space 118 through air passage 151 for molding, as described above.

In some embodiments, as shown in FIG. 1A, the vacuum-molding apparatus 100 includes pneumatic pump 160, heating device 170, glass heating device 180, and assisted jet device 190. According to several exemplary embodiments, pneumatic pump 160 can inject inert gas into upper space 121 and lower space 118 through air passage 161. According to several exemplary embodiments, the inert gas is heated before it is injected. In some embodiments, the pneumatic pump 160 is implemented to cool down the molded glass object and may alternatively function as a supplemental force to separate the molded glass object after or during cooling of the molded glass. Heating device 170 is disposed outside of the space (upper space 121) in between the mold protection device 120 and the mold 110 and heats the upper spacer 121. Glass heating device 180 is disposed in the upper space 121 and partially heats flat glass object 115. According to several exemplary embodiments, glass heating device 180 provides non-uniform thermal energy to the flat glass object 115 and heats certain portions (such as the edges or bending portions) of flat glass object 115 with more power for compensating for the temperature variations or enhancing the molding effect. In some embodiments, certain parts of glass heating device 180 have a higher temperature than other parts of glass heating device 180. According to several exemplary embodiments, glass heating device 180 includes one or more infrared (IR) heating devices for heating the glass object 115 at particular positions, such as the edges of the glass object 115.

Without being bound by theory, it is believed that a difference in temperature between flat glass object 115 and the air around flat glass object 115 produces thermal shock, which can cause flat glass object 115 to break. The use of more heating devices allows for a more accurate adjustment of temperature distributions. By heating the space in between mold protection device 120 and mold 110, the temperature difference is minimized and reduces thermal shock.

Assisted jet device 190 is disposed in the vacuum-molding apparatus 100 and configured to inject gas toward the glass object 115, especially toward the locations with more bending (e.g., the locations corresponding to high curvature regions of the shaped surface 210 of the mold) , to assist in shaping glass, and particularly to get a better curvature in 3D glass. According to several exemplary embodiments, the assisted jet device 190 provides a force of more than about 762 Torr.

In the process of bend molding, lower vacuum system 150 can create a vacuum in air passage 151, thereby reducing the pressure of lower space 118. Upper space 121, on the other hand, will have a positive pressure. With the pressure difference between upper space 121 and lower space 118, the flat glass object 115 is bent to a desired shape. The pressure of lower space 118 will differ based on a variety of factors such as arrangement of the suction holes on the mold 110, the temperature in the mold protection device 120, the composition of flat glass object 115, and the size of flat glass object 115. According to several exemplary embodiments, lower vacuum system 150 reduces the pressure of lower space 118 to about 1 Torr to about 670 Torr.

Referring now to FIG. 1B, another embodiment of a vacuum-molding apparatus 100 is shown. The apparatus 100 in FIG. 1B is substantially similar to the apparatus 100 in FIG. 1A. In FIG. 1B, however, apparatus 100 includes a motor 122 and connecting rod 123, which are designed to move the mold protection device 120. The mold protection device 120 includes a cover 120A configured to be movable relative to other portions of the mold protection device 120. Motor 122 drives the cover 120A of mold protection device 120 through connecting rod 123 to change the volume of upper space 121, thereby changing the pressure in upper space 121 to help bend form flat glass object 115 into a 3D glass form. In the present embodiment, the cover 120A of mold protection device 120 is moved in a vertical direction, the volume of upper space 121 changes and the pressure exerted on flat glass object 115 changes. Thus, the pressure in upper space 121 can be adjusted by moving mold protection device 120. Advantageously, mold protection device 120 provides an air-tight cover around mold 110, and apparatus 100 prevents air from leaking into the space between mold 110 and mold protection device 120.

Turning now to FIG. 3, illustrated is an embodiment of glass heating device 380 for heating particular positions of the flat glass object 115. The heating device 380 is designed with a shape, size and thermal radiation distribution such that certain portions (such as the edges or corners) of the glass object 115 receive more thermal energy. In the present embodiment, heating device 380 is a ring structure, although other shapes are also suitable. In the bend molding process, the heating device 380 heats the edges of the glass object 115 so that the temperature of the forming corners 384 of the glass object 115 is higher than other parts of the glass object 115. This can help prevent glass warping during bend forming, thus increasing glass quality.

FIG. 4 shows a method 400 for making curved glass using a vacuum-molding apparatus. At step 402, the mold 110 is protected. For example, pneumatic pump 130 injects inert gas such as nitrogen through air passage 131 into the area (e.g., upper space 121) between mold protection device 120 and mold 110. In another example, upper vacuum system 140 creates a vacuum in the space (e.g., upper space 121) between mold protection device 120 and mold 110.

At step 404, heating device 170 and glass heating device 180 collectively heat flat glass object 115 to a working temperature. At step 406, lower vacuum system 150 creates a vacuum in air passages 114 through air passage 151, which lowers the pressure of lower space 118. Upper space 121, on the other hand, is at a positive pressure. The pressure difference between upper space 121 and lower space 118 enables bend forming of the flat glass object 115 so as to conform it to the contours of mold 110. Thereby, flat glass object 115 is bend formed to produce a molded glass object with a curved surface (2.5D or 3D) . According to several exemplary embodiments, assisted jet device 190 is used to inject gas in a corner to assist in shaping flat glass object 115.

At step 408, the bent glass object is cooled. Cooling and release of the molded glass from the mold can be accelerated through natural cooling or using pneumatic pump 130, pneumatic pump 160 or both to blow or inject inert gas on the bent glass. The use of inert gas can release the glass from the mold 110 quickly and increase the mold’s life. According to several exemplary embodiments, the injected inert gas used to cool the glass is heated to a temperature lower than the working temperature of the glass. According to several exemplary embodiments, the temperature of the injected inert gas is about 50℃to about 150℃lower than the working temperature. In other exemplary embodiments, both

pneumatic pumps

130 and 160 are operated to provide heated inert gas for cooling. In furtherance of the exemplary embodiments, the release of the glass from the mold 110 is subsequently performed by utilizing pneumatic pump 160 and the vacuum pump 140 such that a pressure difference exists between upper space 121 and lower space 118. A vacuum is created in the upper space 121, while a positive pressure is provided in lower space 118. This pressure difference forces the molded glass object 115 to be released from the shaped surface 210 of the mold.

According to several exemplary embodiments, the present invention provides a vacuum-molding apparatus for making curved glass using bend molding. The vacuum-molding apparatus includes a mold having a shaped surface for bend molding glass, a mold protection device for protecting the mold from oxidation and damage, a vacuum system for creating a vacuum in an inner space of the mold, and a glass heating device for heating a glass object. The mold is protected through the formation of an inert gas environment or vacuum to increase the life span of the mold. According to several exemplary embodiments, the mold includes graphite, silicon carbide, stainless steel, or a combination thereof. According to several exemplary embodiments, the mold includes one or more suction holes disposed on one or more edges of the mold. According to several exemplary embodiments, the one or more suction holes have a higher density on portions of the mold that have a greater curvature. According to several exemplary embodiments, the mold protection device is movable in a vertical direction to change or adjust a positive pressure applied to the glass object.

According to several exemplary embodiments, the vacuum-molding apparatus also includes one or more pneumatic pumps for injecting inert gas into the mold protection device. According to several exemplary embodiments, the inert gas includes nitrogen, argon, or a combination thereof.

According to several exemplary embodiments, the vacuum system includes a pneumatic pump for injecting inert gas into the mold. According to several exemplary embodiments, the inert gas includes heated nitrogen or heated argon. According to several exemplary embodiments, the glass heating device includes one or more infrared (IR) heating devices for heating the glass object at particular positions. According to several exemplary embodiments, the glass heating device is configured so that the corners and edges of the glass object are heated to a higher temperature than other parts of the glass object.

According to several exemplary embodiments, the vacuum-molding apparatus further includes a heating device that heats a space between the mold protection device and the mold. According to several exemplary embodiments, the vacuum-molding apparatus further includes an assisted jet device that injects gas in a corner of the mold protection device to assist in shaping the glass object. According to several exemplary embodiments, the assisted jet device is designed to provide a better curvature in 3D glass. According to several exemplary embodiments, the assisted jet device provides a pressure greater than 762 Torr.

According to several exemplary embodiments, the present invention further provides a vacuum-molding apparatus for forming curved glass that includes a mold having a shaped surface and one or more suction holes disposed on one or more edges of the mold, a mold protection device that covers the mold and is movable in a vertical direction to adjust a positive pressure applied to a glass object, a vacuum system that creates a vacuum in an inner space of the mold； and a glass heating device that heats the glass object at particular positions. [0041]According to several exemplary embodiments, the vacuum-molding apparatus further includes one or more air pumps that inject inert gas into a space between the mold protection device and the mold. According to several exemplary embodiments, the one or more air pumps inject heated inert gas during cooling of the glass object.

According to several exemplary embodiments, the vacuum-molding apparatus further includes an assisted jet device that injects gas in a corner of the mold protection device to assist in shaping the glass object.

According to several exemplary embodiments, the present invention also provides a method of bend molding a glass object. According to several exemplary embodiments, the glass object can be a glass sheet or any glass material having proportions capable of being bend molded. According to several exemplary embodiments, the material of the glass object can be any glass. Examples of suitable glass include aluminosilicate glass, borophosphosilicate glass, fluorophosphate glass, fluorosilicate glass, quartz, phosphate glass, phosphosilicate glass, soda-lime glass, sodium silicate, and the like.

According to several exemplary embodiments, the method of bend molding a glass object includes covering a mold with a mold protection device, protecting the mold from oxidation by forming an inert gas environment or creating a vacuum in a space between the mold and the mold protection device, heating a glass object to a working temperature to provide a heated glass object, creating a vacuum in an inner space of the mold while a positive pressure is present in an outer space of the mold to bend form the heated glass object to provide a molded glass object, and cooling the molded glass object.

According to several exemplary embodiments, the pressure differential between the outer space of the mold and the inner space of the mold facilitates bend forming the glass object on the mold. According to several exemplary embodiments, the method further includes changing or adjusting the positive pressure by vertically moving the mold protection device.

According to several exemplary embodiments, the method further includes injecting heated inert gas on the molded glass object while cooling. According to several exemplary embodiments, the temperature of the heated inert gas is less than the working temperature. According to several exemplary embodiments, the working temperature is about 600℃to 950℃, including from about 700℃to 800℃. According to several exemplary embodiments, the temperature of the injected inert gas is about 50℃to about 150℃less than the working temperature.

According to several exemplary embodiments, the glass object includes at least one surface that is 2D. Examples of glass objects for molding include touchscreens and flat glass. According to several exemplary embodiments, the inventive method can be used to mold the at least one 2D surface into a molded glass object having at least one 2.5D or 3D surface. For example, the inventive method can produce curved glass suitable for curved displays.

The present disclosure provides a method and an apparatus to form curved glass with a high quality surface, which can be used in automotive systems, or portable mobile devices. While the present invention has been described in terms of certain embodiments, those of ordinary skill in the art will recognize that the invention can be practiced with modification within the spirit and scope of the appended claims.

Any spatial references such as, for example, “upper, ” “lower, ” “above, ” “below, ” “between, ” “bottom, ” “vertical, ” “horizontal, ” “angular, ” “upwards, ” “downwards, ” “side-to-side, ” “left-to-right, ” “left, ” “right, ” “right-to-left, ” “top-to-bottom, ” “bottom-to-top, ” “top, ” “bottom, ” “bottom-up, ” “top-down, ” etc., are for the purpose of illustration only and do not limit the specific orientation or location of the structure described above.

The present disclosure has been described relative to certain embodiments. Improvements or modifications that become apparent to persons of ordinary skill in the art only after reading this disclosure are deemed within the spirit and scope of the application. It is understood that several modifications, changes and substitutions are intended in the foregoing disclosure and in some instances some features of the invention will be employed without a corresponding use of other features. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the scope of the invention.

Claims

A vacuum-molding apparatus for forming curved glass, comprising:

a mold having a shaped surface and a plurality of suction holes；

a mold protection device that covers the mold；

a vacuum system that creates a vacuum in an inner space of the mold； and

a glass heating device that heats a glass object.
The vacuum-molding apparatus of claim 1, wherein the mold comprises graphite, silicon carbide, or stainless steel.
The vacuum-molding apparatus of claim 1, wherein the plurality of suction holes have a non-uniform distribution on the mold.
The vacuum-molding apparatus of claim 1, wherein the mold protection device includes a cover portion movable for changing a positive pressure applied to the glass object.
The vacuum-molding apparatus of claim 4, further comprising a motor and a connection rod integrated with the mold protection device to move the cover portion of the mold protection device.
The vacuum-molding apparatus of claim 1, further comprising one or more pneumatic pumps that inject inert gas into a space between the mold and the mold protection device.
The vacuum-molding apparatus of claim 1, wherein the vacuum system further comprises a pneumatic pump for injecting inert gas into the inner space of the mold.
The vacuum-molding apparatus of claim 1, wherein the glass heating device comprises one or more infrared (IR) heating devices.
The vacuum-molding apparatus of claim 1, wherein the glass heating device is configured to provide thermal energy to the glass object with a non-uniform distribution so that corners of the glass object are t heated to a higher temperature than other portions of the glass object.
The vacuum-molding apparatus of claim 1, further comprising a heating device that heats a space between the mold protection device and the mold.
The vacuum-molding apparatus of claim 1, further comprising an assisted jet device that injects gas toward bending portions of the mold to assist in shaping the glass object.
A vacuum-molding apparatus for forming curved glass, comprising

a mold having a shaped surface and a plurality of suction holes disposed non-uniformly on the mold；

a mold protection device that covers the mold and is movable to adjust a positive pressure applied to a glass object；

a vacuum system that creates a vacuum in an inner space of the mold； and

a glass heating device configured to heat the glass object with more thermal energy on edges of the glass object.
The vacuum-molding apparatus of claim 12, wherein

the shaped surface of the mold includes a first region with a first curvature and a second region with a second curvature that is less than the first curvature； and

the suction holes are configured to have a first density in the first region and a second density in the second region, the second density being less than the first density.
The vacuum-molding apparatus of claim 12, further comprising

one or more pneumatic pumps that inject inert gas into a space between the mold protection device and the mold； and

an assisted jet device that injects gas toward a portion of the mold to assist in shaping the glass object.
A method of bend molding a glass object, comprising:

covering a mold with a mold protection device；

protecting the mold from oxidation by forming an inert gas environment；

heating a glass object to a working temperature to provide a heated glass object；

creating a vacuum in an inner space of the mold while a positive pressure is present in an outer space of the mold to bend form the heated glass object to provide a molded glass object； and

cooling the molded glass object.
The method of claim 15, further comprising changing the positive pressure by moving the mold protection device while creating a vacuum.
The method of claim 15, further comprising injecting heated inert gas on the molded glass object while cooling the molded glass object.
The method of claim 17, wherein a temperature of the heated inert gas is less than the working temperature.
The method of claim 18, wherein the working temperature is about 600℃ to 950℃； and the temperature of the heated inert gas is about 50℃ to about 150℃ less than the working temperature.
The method of claim 15, further comprising injecting gas toward bending portions of the mold to assist in shaping the glass object.