WO2012074513A1

WO2012074513A1 - A method of glass molding and polishing

Info

Publication number: WO2012074513A1
Application number: PCT/US2010/058398
Authority: WO
Inventors: Christopher Cosma
Original assignee: Christopher Cosma
Priority date: 2010-11-30
Filing date: 2010-11-30
Publication date: 2012-06-07

Abstract

A method of forming a glass panel (16) incorporates a mold cavity (24) in a refractory mold (22) having a textured surface (26) with refractory mold edges (28) and refractory mold recesses (30). Semi-molten glass (34) is maintained in the mold cavity until a surface (35) of the semi-molten glass suspended between the refractory mold edges slumps into the refractory mold recesses and the suspended surface has been heat polished. The semi-molten glass is cooled into a glass panel (16) where portions of the glass surface (20) are heat polished and the remainder of the glass surface has a textured surface (38).

Description

A METHOD OF GLASS MOLDING AND POLISHING

FIELD OF THE INVENTION

The present invention relates to a method for glass molding and polishing, and more particularly to a method for glass molding and polishing wherein a portion of the surface of the molded glass is polished and another portion of the surface is unpolished.

BACKGROUND OF THE INVENTION

The use of molds for forming glass panels has been well known in the prior art. Typically, the surface of the glass panels is either completely smooth or rough and unfinished. The molds used in forming the glass panels typically determine the quality of the surface of the glass panels. In the event that the glass surfaces are rough and unfinished, time consuming and expensive processes are required to smooth the glass to the desired surface quality.

A method of controlling the nature of the surface of the glass panels formed in molds is required to overcome the manufacturing problems heretofore encountered in the prior art.

SUMMARY OF THE INVENTION

According to one embodiment of the present invention, a method of forming a glass panel includes providing a mold cavity in a ref actory mold having a textured surface with refractory mold edges circumferentially about a plurality of refractory mold recesses. Semi-molten glass is maintained in the mold cavity until a surface of the semi-molten glass suspended between the refractory mold edges slumps into the refractory mold recesses and the suspended surface has been heat polished. The semi-molten glass is cooled into a finished glass panel where portions of the glass surface are heat polished and the remainder of the glass surface has a textured surface. In another embodiment of the present invention, a method of forming a glass panel includes constructing in the cavity of a mold a positive form having a textured top surface with edges circumferentially about positive form projections. A refractory mold of the positive form is created with a mold cavity having a textured surface and with refractory mold edges corresponding to the edges of the positive form disposed about refractory mold recesses. A panel of solid glass is heated in the mold cavity to a semi-molten state, thereby forming semi-molten glass. The semi-molten glass is maintained at an operational temperature above a glass transformation temperature until the semi-molten glass surface suspended between the refractory mold edges slumps into the refractory mold recesses and the suspended surface has been heat polished. The semi-molten glass is cooled into a finished glass panel where portions of the glass surface within the mold recesses are heat polished and the remainder of the glass surface has a textured surface.

In another embodiment of the present invention, a glass panel is formed by the method of providing a mold cavity in a refractory mold having a textured surface with refractory mold edges circumferentially about a plurality of refractory mold recesses. Semi-molten glass is maintained in the mold cavity until a surface of the semi-molten glass suspended between the refractory mold edges slumps into the refractory mold recesses and the suspended surface has been heat polished. The semi-molten glass is cooled into a finished glass panel where portions of the glass surface are heat polished and the remainder of the glass surface has a textured surface.

BRIEF DESCRIPTION OF THE DRAWINGS

The structure, operation, and advantages of the present invention will become further apparent upon consideration of the following description taken in conjunction with the accompanying Figures (FIGs.). The Figures are intended to be illustrative, not limiting.

[08] Certain elements in some of the Figures may be omitted, or illustrated not-to-scale, for illustrative clarity. The cross-sectional views may be in the form of "slices", or "near-sighted" cross-sectional views, omitting certain background lines which would otherwise be visible in a "true" cross-sectional view, for illustrative clarity.

[09] Often, similar elements may be referred to by similar numbers in various

Figures (Figs) of the drawing, in which case typically the last two significant digits may be the same, the most significant digit being the number of the drawing figure (Fig).

[010] Figure 1 is a three dimensional view, with a partial cutaway section, of a positive form disposed within the cavity of a mold, according to an embodiment of the present invention.

[01 1] Figure 1 A is a side view in cross section of a section of the positive form, according to an embodiment of the present invention.

[012] Figure 2 is a three dimensional view of a refractory mold with a cavity and a textured bottom formed from the positive form disposed within the cavity of the mold shown in Figure 1 and disposed within a kiln, according to an embodiment of the present invention.

[013] Figure 2 A is a three dimensional top view of the representation of an actual refractory mold.

[014] Figure 3 is a partial, cross sectional view of the refractory mold of Figure 2 showing the peaks and the valleys in the surface of the refractory mold.

[015] Figure 4 is a partial, cross sectional view of the refractory mold of Figure 2 showing the semi-molten glass on the surface of the refractory mold.

[016] Figure 5 is a three dimensional, cross sectional view of the refractory mold of

Figure 2 with the glass panel formed after glass has been placed into the refractory mold, heated to the semi-molten state in the kiln, and cooled to a solid state glass panel, according to an embodiment of the present invention.

Figure 6 is an enlarged, three dimensional, cross sectional view of the refractory mold with solidified glass panel of Figure 5, according to an embodiment of the present invention.

[018] Figure 7 is an enlarged, three dimensional view of the surface of the solidified glass of Figure 6 which was in contact with the textured bottom of the mold, according to an embodiment of the present invention.

[019] Figure 8 is a flowchart indicating process steps to perform a method according to an embodiment of the present invention.

DETAILED DESCRIPTION

In the description that follows, numerous details are set forth in order to provide a thorough understanding of the present invention. It will be appreciated by those skilled in the art that variations of these specific details are possible while still achieving the results of the present invention. Well-known processing steps are generally not described in detail in order to avoid unnecessarily obfuscating the description of the present invention.

In the description that follows, exemplary dimensions may be presented for an illustrative embodiment of the invention. The dimensions should not be interpreted as limiting. They are included to provide a sense of proportion. Generally speaking, it is the relationship between various elements, where they are located, their contrasting compositions, and sometimes their relative sizes that is of significance.

According to the present invention, a method is provided to form a glass panel in a single heating and cooling cycle wherein portions of the surface of the glass panel are textured and other portions, projecting above the textured surface are polished.

The first step in forming a glass panel, according to the present invention is to create a positive form which corresponds to the finished glass panel. As shown in Figure 1 , a mold 10 has walls 10a, 10b, 10c and lOd and a base surface 1 1 to form a cavity 12. Within the cavity 12 is disposed a positive form 14. The positive form 14 is the original model of a finished glass panel 16, as shown in Figure 7. The positive form 14 has a textured top surface 18 and thickness "a" that are substantially identical to the textured top surface 20 and thickness "e" of the finished glass panel 16. In addition, positive form 14 has a plurality of forms 21 of any desired shape which project above the textured surface 20. These forms 21 will be the polished surfaces of the forms 40 projecting above the textured surface 38 of the finished glass panel 16.

While the positive form 14 is typically constructed of clay, foam and/or rubber in the dimension of the finished glass panel 16, it is within the terms of the present invention to construct the positive form 14 of any desired material.

In constructing the positive form 14, so that the finished forms 40 of the finished glass panel 16 has the desired texture, a number of considerations are taken into account. These include the length, width, thickness and weight of the finished glass panel 16, the type of glass used for the glass panel, the depth of the relief needed between the finished forms and the surface 20 of the finished glass panel and its relationship to the glass type being used.

Basically, as shown in Figure 1 A, the textured surface 18 of the positive form 14 has positive form edges 19 on the textured surface which circumferentially surround the positive forms 21 projecting above the textured surface 18, as discussed hereinafter. The relatively smooth positive form surface 15 of the textured surface 18 is that part of the surface which doesn't include the positive form projections 21 surrounded by the positive form edges 19, as discussed hereinbelow. Preferably, any type of glass can be used to construct the glass panel of the present invention. The height "c" of the positive form projections 21, from the positive form edges 19 surrounding positive form projections 21, to the highest point or top 21a of the positive form projections 21 above the surface 15 of the positive form 14, can vary between about 1.27 centimeters (cm) (0.5 inches) and 25.4 cm (10 inches). A height "c" of less than about 1.27 cm (0.5 inches) is not enough to ensure heat polishing of the glass and more than about 25.4 cm (10 inches) would cause a weight problem that would weaken the refractory mold. Preferably, the depth "c" of the positive form height 21 can vary between about 5.08 cm (2 inches) and 15.24 cm (6 inches) depending on the weight capacity of the finished glass panel 16.

[027] In creating the positive form projections 21 of the textured top surface 18 of the positive form 14, a determination of the design or pattern of the polished surface areas and the textured surface areas of the surface of glass panel 16 is required. The positive form projections 21 and the flat surfaces 15 of the textured top surface 18 of the positive form 14 ultimately create the finished glass panel 16 where the textured top surface 20 has polished projections 40 projecting above the flat textured surfaces 38. The shape of the glass panel 16 can be substantially the same as the original positive form 14. In practice, the thickness "e" of the glass panel 16 is more than the thickness "a" of the original positive form 14.

[028] The making of a fiber reinforced, air entrained refractory mold 22 for glass melting, as shown in Figure 2, is the next step in the process after creating positive form 14 within the mold 10. The refractory mold 22 is constructed by pouring air entrained, fiber reinforced, castable refractory liquid, such as example HYDROPERM^® gypsum cement by USG Corp., over and down the sides of the positive form 14. The air entrained, fiber reinforced, castable refractory material is particularly useful because it allows for the escape of gases caused during the rapid heating process, as discussed in more detail hereinafter. Further, the air entrained, fiber reinforced, castable refractory liquid is useful because it is lightweight and quick and easy to mix and pour. Moreover, the air entrained, fiber reinforced, castable refractory liquid dries rapidly, such as for example in two hours as compared to a week or more for other types of refractory material. Once the air entrained, fiber reinforced, castable refractory liquid dries, the resulting refractory mold 22, as shown in Figure 2, has a cavity 24 with a textured bottom surface 26 that is the negative shaped form of the desired finished glass panel 16. It is also within the terms of the invention to construct the refractory mold 22 from high temperature fiber board, blanket or paper. Moreover, the mold 22 could be made directly from one of the moldable fiber based refractories, such as for example an alumina paste with ceramic fiber.

[029] Referring to Figure 2 A, there is shown a three dimensional top view of the representation of an actual refractory mold 23. Note that the textured bottom surface 26 is the negative shaped form of a desired finished glass panel with a landscape of ridges and depressions. The refractory recesses or depressions 30 of the present invention meet a minimum and maximum distance requirement from the refractory edges 28 disposed circumferentially around recesses or depressions until the lowest point or bottom surface 30a of refractory recesses 30 as set forth hereinafter and illustrated in Figure 2A.

[030] As shown in Figure 3, a partial cross section of the refractory mold 22, the textured bottom surface 26 has relatively flat surfaces 27 and refractory edges 28 disposed circumferentially around refractory recesses or depressions 30 extending downward from the relatively flat surface 27 of textured bottom surface 26. The distance "d" between the refractory circumferential edges 28 and the lowest point or bottom surface 30a of refractory recesses 30 can be between 1.27 cm (0.5 inches) and 25.4 cm (10 inches) and preferably between about 10.16 cm (4 inches) and 15.24 cm (6 inches), which corresponds to the height "c" of the positive form projections 21, as shown in Figure 1 A.

[031 ] Regarding the relationship between the positive form 14 and the refractory mold 22, the positive form projections 21 of the textured top surface 18 correspond to the refractory recesses 30 and the positive flat surfaces 15 correspond to the refractory flat surfaces 27 of the refractory mold 22 of Figure 2, a section of which is shown in Figure 3.

[032] Once the refractory mold 22 is completed, a panel of solid glass (not shown) of at least 1.27 cm (0.5 inches) thick is placed into the refractory mold cavity 24, see Figure 2, so as to rest on the refractory edges 28 of refractory recesses 30 of the refractory mold 22. Then, the refractory mold 22 and the solid panel of glass is placed within a refractory oven, not shown, and heated to the correct temperature profile so that the solid glass is transformed to the semi-molten glass 34, as shown in Figure 4. The semi-molten glass 34 is heated to an operational temperature in the range of about 12.22 degrees Centigrade (C) (10 degrees Fahrenheit (F)) to about 93.33 degrees C (200 degrees F) above the glass transformation temperature and preferably about 1.11 degrees C (30 degrees F) to 10 degrees C (50 degrees F) above the glass transformation temperature. The semi-molten glass 34 is held at the operational temperature for a period of about 15 to about 120 minutes and preferably about 30 to about 75 minutes or until the surface 35 of the semi-molten glass, suspended between the refractory edges 28 of refractory recesses 30, has slumped into the refractory recesses 30 for a desired distance without contacting the bottom surface 30a of the refractory recess. If the semi-molten glass 34 is held at the operational temperature for a period of less than about 15 minutes, the semi-molten glass would not have enough time to sag between the refractory edges 28 towards the bottom of the refractory recesses 30. Conversely, if the semi-molten glass 34 is held at the operational temperature for a period of more than 120 minutes, the semi-molten glass would substantially fill the refractory recesses 30 between the refractory edges 28 and to the bottom surface 30a of the refractory recesses 30.

[033] The restricted glass flow at the operational temperature set forth above causes the surface 35 of semi-molten glass 34 that is suspended between the refractory edges 28 and into refractory recess 30, to slump down without coming in contact with the bottom surface 30a at the bottom of the refractory recesses 30. The suspended surface 35 of the semi-molten glass 34 within the refractory recesses 30 will be polished by the heated gases from the heating process that are trapped between the suspended surface 35 of the semi-molten glass 34 that is slumped between the refractory edges 28 and the bottom surface 30a of the refractory recesses 30. The surface of the semi-molten glass that does contact the refractory mold surface 27, in locations other than over the refractory recesses 30, will have an imprint of the textured mold surface 27 and therefore also be textured. The gases from the heating process that are trapped between the surface 35 of the semi-molten glass sagging between the refractory edges 28 and the bottom surface 30a of the refractory recesses 30 will escape through the air entrained, fiber reinforced, castable refractory. If necessary, gas escape openings can be provided at or near the bottom of the refractory recesses 30 as required.

[034] After the semi-molten glass 34 is solidified into a finished glass panel 16, as shown in the cross section through the refractory mold 22 and glass panel 16 in Figures 5 and 6, the refractory recesses 30 of bottom surface 26 of refractory mold 22 form an air pocket 36 between the bottom surface 30a of refractory recess 30 and the glass panel 16 where the glass surface 38 has been heat polished. The remainder of the surface 40 of the glass panel 16, which is in direct contact with the surface 27 of the refractory mold 22, has a textured surface corresponding to the textured surface of the refractory mold 22.

[035] Referring to Figure 7, there is illustrated a finished glass panel 16 where the textured top surface 20 has relatively flat textured surfaces 38, corresponding to the positive form textured surface 15 of the positive form 18 and projections 40 projecting above the textured surface 38 with polished surfaces. The polished surfaces of projections 40 are not as deep as the recesses 30 because the process of the present invention substantially prevents the semi-molten glass from filling the recesses 30 which are the negative of the positive projections 21. The thickness "e" of the textured glass surface 38 of finished glass panel 16 is substantially the same as the thickness "a" of the textured surface 15 of positive form 14.

[036] The size of each glass panel 16, as seen in Figure 7, can be between 8.9 cm (3.5 inches) and 243.84 cm (96 inches) in length, between 8.9 cm (3.5 inches) and 81.3 cm (32 inches) in width, and between 5.1 cm (2 inches) and 15.2 cm (6 inches) inches in thickness. Typically , the size of each glass panel 16 can be between 8.9 cm (3.5 inches) and 81.3 cm (32 inches) in length, between 250.4 cm (10 inches) and 91.44 cm (36 inches) inches in width, and between 5.1 cm (2 inches) and 15.24 cm (6 inches) in thickness. Depending on the size of the glass panel 16, the weight of each glass panel can be between 22.7 kilograms (kg) (50 pounds (lb)) and 159.1 kg (350 lb) and preferably between 22.7 kg (50 lb) and 90.9 kg (200 lb).

[037] Referring to Figure 8, there is illustrated a flow chart of the process of the present invention.

[038] First, in step 50, a positive form 14 with a textured top surface 18 and a thickness "a", substantially identical to the textured top surface 20 and thickness "e" of a finished glass panel is 16, is constructed and disposed within the cavity 12 of a mold 10.

[039] In the next step 52, a determination of the design or pattern of the polished surface areas and the textured surface areas of the surface of glass panel 16 is determined so that the textured top surface of the positive form 14 creates the textured top surface 38 and the positive form projections 21 create the polished projections 40 of the finished glass panel.

[040] In the next step 54, a refractory mold 22 is constructed for glass melting by pouring air entrained, fiber reinforced, castable refractory liquid, over and down the sides of the positive form 14 so that the refractory mold has a textured surface with high points 28 surrounding recesses 30.

[041] In the next step 56, a panel of solid glass is placed into the mold cavity 24 of the refractory mold 22 so as to rest on the high points 28 surrounding the recesses 30 of the refractory mold 22. In the next step 58, the refractory mold 22 and the solid panel of glass are heated within a refractory oven so that the glass is transformed to the semi-molten state 34.

In the next step 60, the semi-molten glass 34 is maintained at an operational temperature of about 1.11 degrees C to 10 degrees C above the glass transformation temperature.

In the next step 62, the semi-molten glass 34 is held at the operational temperature for a period of time until the semi-molten glass suspended between the high points 28 of the surface 35 slumps into the recesses 30 without contacting the mold surface 30a at the bottom of the recesses 30 so that the surface 35 of the semi-molten glass in the suspended areas will be polished by the heated gases from the heating process that are trapped between the semi-molten glass and the bottoms 30a of the recesses 30.

In the next step 64, the semi-molten glass is cooled and solidified into a finished glass panel 16 where the glass surface 38 extending down into the recesses 30 between the high points 28 of the refractory mold 22 are heat polished and the remainder of the surface 40 of the glass panel 16 which is in direct contact with the surface 26 of the refractory mold has a textured surface. Then, the finished glass panel is de-molded from the refractory mold.

It can be appreciated that using the process of the present invention, up to about 90 percent of the semi-molten glass surface does not touch the surface of the refractory mold and is heat polished without requiring polishing by mechanical means after cooling and de-molding. Prior to the present invention, when melting glass into a mold, the glass surface facing into the mold contacted the surface of the mold and left an imprint of the mold texture that needed mechanical polishing to remove. Mechanical polishing is a labor intensive process employing the use of abrasives and rare earth polishing compounds. An alternative to mechanical polishing is acid polishing which has strict EPA restrictions, size and weight limitations and the acid polishes the entire surface into one uniform finish which is generally not desirable.

The advantage of the present invention is the ability to achieve a variety of surface finishes, both polished and textured translucent in a single process at very fast speeds due to the ability of the mold to dry and de-gas and anneal quickly with the glass panel inside.

Although the invention has been shown and described with respect to a certain preferred embodiment or embodiments, certain equivalent alterations and modifications will occur to others skilled in the art upon the reading and understanding of this specification and the annexed drawings. In particular regard to the various functions performed by the above described components (assemblies, devices, etc.) the terms (including a reference to a "means") used to describe such components are intended to correspond, unless otherwise indicated, to any component which performs the specified function of the described component (i.e., that is functionally equivalent), even though not structurally equivalent to the disclosed structure which performs the function in the herein illustrated exemplary embodiments of the invention. In addition, while a particular feature of the invention may have been disclosed with respect to only one of several embodiments, such feature may be combined with one or more features of the other embodiments as may be desired and advantageous for any given or particular application.

Claims

What is claimed is:

1. A method of forming a glass panel, comprising:

providing a mold cavity in a refractory mold comprising a textured surface with a plurality of refractory mold recesses projecting down into the textured surface;

maintaining semi-molten glass in the mold cavity until a surface of the semi-molten glass suspended over the refractory mold recesses slumps into the refractory mold recesses and the suspended surface has been heat polished; and

cooling the semi-molten glass into a finished glass panel where portions of the glass surface are heat polished and the remainder of the glass surface has a textured surface.

2. The method of claim 1 including:

constructing a positive form having a textured top surface with a plurality of positive form projections projecting outward from the textured top surface.

3. The method of claim 2 including:

creating the refractory mold of the positive form with the refractory mold cavity having a textured surface with refractory mold edges corresponding to the positive form edges disposed on the textured surface circumferentially around the positive form projections and a textured refractory surface corresponding to the positive textured surface of the positive form.

4. The method of claim 3 including:

heating glass in the mold cavity to form semi-molten glass; and

maintaining the semi-molten glass at an operational temperature of about 12.22 degrees C to 93.33 degrees C above a glass transformation temperature until the semi-molten glass surface suspended between the refractory mold edges slumps into the refractory mold recesses and the suspended surface has been heat polished.

5. The method of claim 3 wherein the step of creating the refractory mold of the positive form, comprises:

forming the refractory mold recesses from the refractory mold edges to the bottom of the recesses at a depth of between about 1.27 cm and 25.4 cm.

6. The method of claim 5 wherein the step of creating the refractory mold of the positive form, comprises:

forming the depth of the refractory mold recesses from the refractory mold edges to the bottom of the recesses between about 10.16 cm and 15.24 cm.

7. The method of claim 2 wherein the step of creating the positive form, includes:

forming the positive form projections from the positive form edges to the top of the positive form projections with a height between about 1.27 cm and 25.4 cm.

8. The method of claim 7 wherein the step of creating the positive form, includes:

forming the positive form projections from the positive form edges to the top of the positive form projections with a height of between about 10.16 cm and 25.4 cm.

9. The method of claim 1 including forming the refractory mold of air entrained, fiber reinforced, castable refractory material.

10. The method of claim 4 including maintaining semi-molten glass in the mold cavity at the operational temperature for a period of about 15 minutes to about 120 minutes until the semi-molten glass has slumped into the refractory mold recesses between the high points without contacting the bottom of the recesses.

1 1. A method of forming a glass panel, comprising:

constructing in the cavity of a mold a positive form having a textured top surface with a plurality of positive form projections circumferentially surrounded by positive form edges; creating a refractory mold of the positive form with a mold cavity having a textured surface with a plurality of refractory mold recesses corresponding to the positive form projections;

heating a panel of solid glass in the mold cavity to a semi -molten state, thereby forming semi-molten glass;

maintaining the semi-molten glass at an operational temperature above a glass transformation temperature until the semi-molten glass surface suspended between the refractory mold edges slumps into the refractory mold recesses and the suspended surface has been heat polished; and

12. The method of claim 1 1 including:

13. The method of claim 11 wherein the step of creating the refractory mold of the positive form, including:

forming refractory mold recesses from the refractory mold edges to the bottom of the recesses with a depth of between about 1.27 cm and 25.4 cm.

14. The method of claim 13 wherein the step of creating the refractory mold of the positive form, including:

forming the refractory mold recesses from the refractory mold edges to the bottom of the recesses with a depth of between about 10.16 cm and 25.4 cm.

15. The method of claim 12 wherein the step of creating the positive form, includes:

forming the positive form projections from the positive form edges to the top of the positive form projections with a depth of between about 1.27 cm and 25.4 cm.

16. The method of claim 15 wherein the step of creating the positive form, includes:

17. The method of claim 13 including forming the refractory mold of air entrained, fiber reinforced, castable refractory material.

18. A glass panel having a surface with textured portions and polished portions formed by the process of:

providing a mold cavity in a refractory mold comprising a textured surface with a plurality of refractory mold recesses projecting down into the textured surface; maintaining semi-molten glass in the mold cavity until a surface of the semi-molten glass suspended over the mold recesses slumps into the refractory mold recesses and the suspended surface has been heat polished; and

19. The glass panel of claim 18 including:

heating glass in the mold cavity to a semi-molten state; and

maintaining the semi-molten glass at an operational temperature of about 12.22 degrees C to 93.33 degrees C above a glass transformation temperature until the semi-molten glass surface suspended between the refractory edges into the refractory mold recesses and the suspended surface has been heat polished.

20. The glass panel of claim 19 wherein the step of creating the refractory mold of the positive form, comprises:

forming the refractory mold recesses from the refractory edges to the bottom of the recesses to a depth of between about 1.27 cm and 25.4 cm.