US20030039933A1

US20030039933A1 - Burner-log element

Info

Publication number: US20030039933A1
Application number: US09/953,475
Authority: US
Inventors: David Lyons; Gary Butler; Ted Schroeder
Original assignee: HNI Technologies Inc
Current assignee: HNI Technologies Inc
Priority date: 2000-01-13
Filing date: 2001-09-14
Publication date: 2003-02-27
Also published as: US7470729B2; JP2004525055A; US7098269B2; US20050165160A1; US20050119397A1; WO2002062723A2; WO2002062723A3; CA2437191C; AU2002242143B2; CA2437191A1; EP1399395A2; US20030049575A1

Abstract

Method of forming artificial logs made of an inorganic fiber material using compression molding are described. One method includes providing a molding composition comprising inorganic fiber and an inorganic binder, compression molding the molding composition into an artificial log, and providing a passageway that is defined by the artificial log and at least one burner aperture that is also defined by the artificial log to pass combustible gas to an outer surface of the artificial log. Artificial log elements and burner structures made by the use of such methods and a molding composition for use in compression molding are also described.

Description

FIELD OF THE INVENTION

This invention relates generally to artificial log elements. More particularly, the invention relates to artificial log elements which also serve as gas burners. The invention also relates generally to a method of compression molding, and to log elements produced using compression molding.

BACKGROUND OF THE INVENTION

Fireplaces have been used for centuries as a means for providing heat, for cooking and for simply decorative purposes. In recent years, fireplaces using gaseous fuels, for example natural gas, manufactured gas, and propane, have become very popular due to their efficiency, ease of operation, and cleanliness. One potential drawback of such gas fires, however, is that they tend not to be as aesthetically pleasing as natural wood fires.

Artificial solid ceramic logs for use in gas fireplaces are generally known to help provide an aesthetically pleasing appearance to such fireplaces and to simulate a wood-burning fireplace. Such artificial logs were typically placed over a conventional gas burner element to help hide the burner element from view and to simulate a natural wood fire. While such artificial logs have been somewhat effective in improving the aesthetics of gas fires, they have not been entirely effective in simulating a wood burning fire wherein a flame comes directly from the burning logs.

In an attempt to remedy some of the deficiencies of known artificial logs, some artificial burning log assemblies have been produced. For example, U.S. Pat. No. 5,655,513 to Whitfield (the “'513 Patent”) discloses a gas burning imitation log assembly including an imitation log carried by a gas supply conduit. The assembly includes openings or slots that extend through both the gas supply conduit and the imitation log material. Gas is fed through the supply conduit and diffuses through the slots for combustion to create flames coming from the log. However, as disclosed by the '513 patent, the artificial log material is cooler than the flame generated by the combustion gas, and thereby acts to cool the flame and hinder complete combustion of the gas. Partial combustion is undesirable for many reasons, for example, because it results in the production of noxious carbon monoxide and the buildup of soot on the log. To achieve complete combustion in the burner log disclosed by the '513 patent, the thickness of the log and the shape and position of the slots must be selectively chosen. Additionally, artificial log materials, such as ceramic or refractory materials, are not as durable as traditional burner material when used as a burner surface as employed in present burner constructions.

Vacuum formed articles made of ceramic or refractory fibers are generally known. For example, it is known to mix chopped dry ceramic fibers with water and various fillers to form a slurry, and then vacuum form the slurry into various articles composed mainly of chopped ceramic fibers. Such articles are often used in high temperature environments, and can withstand high temperatures without decomposition or deformation of the articles. For example, fireplace boxes and artificial fireplace logs have been produced by using such vacuum forming techniques.

Vacuum forming techniques of forming ceramic fiber log elements have been very useful, but it would be desirable to provide additional methods of forming ceramic fiber articles that do not involve vacuum forming. Vacuum forming techniques can be slow, dirty, and relatively complicated. Additionally, it would be desirable to provide ceramic fiber articles that have increased strength, dimensional stability, and thermal conductivity properties as compared to those formed using vacuum forming techniques.

Thus, there is still a need for additional innovations in artificial log elements to help improve burn efficiency and burner durability while still providing a realistic simulation of flame coming from a log.

SUMMARY OF THE INVENTION

The invention provides a method of forming artificial log elements made of an inorganic fiber material using compression molding. The use of compression molding to form inorganic fiber articles is distinctly different from vacuum forming techniques of making such articles. Additionally, in at least some embodiments, the use of compression molding to form inorganic fiber artificial log elements provides for an improvement over vacuum forming techniques, and in some embodiments, provides for inorganic fiber artificial log elements having desirable strength and integrity characteristics.

In one aspect, the invention is directed to a method of forming an artificial log. The method comprises the step of providing a molding composition comprising an inorganic fiber and an inorganic binder. The method also includes the steps of compression molding the molding composition into the artificial log, and providing a gas passageway defined by the artificial log and at least one burner aperture defined by the artificial log to pass combustible gas to an outer surface of the artificial log.

In another aspect, the invention is directed to a method of forming an artificial log comprising the steps of providing a molding composition comprising inorganic fibers and a binder, compression molding the molding composition into the artificial log, wherein at least 75% by weight of the molded article is inorganic material, and providing a passageway defined by the artificial log and at least one burner aperture defined by the artificial log to pass combustible gas to an outer surface of the artificial log.

Another aspect of the invention is directed to a method of forming an artificial log, the method comprising the steps of providing a molding composition comprising inorganic fibers and a binder, compression molding the molding composition into the artificial log such that the binder transforms into a cured binder, wherein the cured binder is capable of withstanding temperatures of at least 600° F., and providing a passageway defined by the artificial log and at least one burner aperture defined by the artificial log to pass combustible gas to an outer surface of the artificial log. In another respect, the invention is directed to a method of forming an artificial log, the method including the steps of providing a molding composition comprising inorganic fibers and a binder, compression molding the molding composition into the artificial log, wherein the artificial log is capable of withstanding temperatures of at least 600° F., and providing a passageway defined by the artificial log and at least one burner aperture defined by the artificial log to pass combustible gas to an outer surface of the artificial log.

In another respect, the invention is directed to articles made by the use of such methods.

In another respect, the invention is directed to an artificial log comprising an inner surface defining a passageway in fluid communication with at least one burner aperture defined by the artificial log, wherein the artificial log is compression molded.

In another respect, the invention is directed to an artificial log comprising an outer surface, wherein the outer surface of the artificial log defines at least one burner aperture to provide combustible gas to the outer surface, wherein the artificial log is compression molded.

In some preferred embodiments, the compression molded inorganic fiber artificial log elements are intended for use in high temperature environments. For example, some embodiments are contemplated for use as a component of a fireplace assembly, a grill assembly, a campfire assembly, a burner assembly, or the like. However, as will be understood by those of skill in the art and others, while certain specific embodiments of the invention will be illustrated in describing preferred embodiments of the invention, the invention is not to be limited to use in such embodiments. The invention is contemplated for use in a broad variety of applications and industries, and to create inorganic fiber articles made of any desired shape or size. These and other modifications of the invention will be understood by those skilled in the art in view of the following description of the invention, with reference to specific embodiments thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring to the figures, wherein like numerals represent like parts throughout the several views: [0016]
FIG. 1 is a perspective view of a burner apparatus embodying the invention; [0017]
FIG. 2 is a perspective view of another burner apparatus embodying the invention; [0018]
FIG. 3 is a cross-sectional side view of an artificial log system including burner apparatuses embodying the invention; [0019]
FIG. 4 is a cross-sectional view of a mold used to create a burner apparatus embodying the invention showing the mold in an open position and having a burner structure positioned therein; [0020]
FIG. 5 is a cross-sectional view of the mold of FIG. 4 in a closed position and having a burner structure positioned therein and being partially filled with mold material; [0021]
FIG. 6 is a cross-sectional view of the mold of FIG. 4 in a closed position and having a burner structure positioned therein and showing the mold filled with mold material; [0022]
FIG. 7 is front view of another burner apparatus embodying the invention; [0023]
FIG. 8 is a cross-sectional side view of the burner apparatus of FIG. 7; [0024]
FIG. 9 is a cross-sectional view of the compression mold used to mold the artificial log element of FIG. 7 showing the mold in an open position with unmolded inorganic fiber composition in the bottom portion of the mold; [0025]
FIG. 10 is a cross-sectional view of the compression mold of FIG. 9 showing the mold in a closed position and molding the inorganic fiber composition; and [0026]
FIG. 11 is a cross-sectional view of the compression mold of FIG. 9 showing the mold in an open position and the compression molded artificial log element in accordance with one embodiment of the invention.[0027]
The organization and manner of the structure and operation of the invention, and advantages thereof, may best be understood by reference to the following description of preferred embodiments, taken in combination with the above referenced accompanying drawings, wherein like reference numerals identify like elements throughout the descriptions and views. [0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The invention relates to the use of compression molding techniques to mold a matrix including inorganic fibers into useful articles. In some embodiments, methods of the invention generally include providing a molding composition including inorganic fibers and a binder, and compression molding the molding composition into a burner-log element. [0029]
Burner-Log Element Structure [0030]
FIG. 1 illustrates one embodiment of the invention including a [0031] gas burner apparatus 10. Gas burner apparatus 10 includes a gas burner structure 14 and an artificial log 18 disposed at least partially around the burner structure 14. A burner portion 34 of the burner structure 14 is exposed adjacent the outer surface 44 of the artificial log 18 such that at least a portion of burner apertures 38 in the burner portion 34 are spaced from the artificial log material to reduce the effect of the log material on the burn efficiency, while still providing a realistic simulation of a burning log.
In this particular embodiment, the [0032] gas burner structure 14 includes a generally hollow conduit member 22 having a first end 24, a second end 25, an outer surface 26, and a hollow inner conduit 30. The burner structure 14 is preferably in the shape of a hollow tube, having a generally circular cross-section. However, as will be understood by those of skill in the art and others, a broad variety of burner structure configurations may be used, and the invention is not limited to any particular burner structure, configuration, or shape. Any burner structure, configuration, or shape that can be disposed within an artificial log as discussed herein is suitable for use with the invention.
The [0033] outer surface 26 of the burner structure 14 includes a first burner portion 34 having at least one burner aperture or jet 38, therein. The burner portion 34 is exposed to the external environment of the log 18, and is not covered by the material of the artificial log 18, as will be discussed more fully below. The burner aperture or apertures 38 extend through the burner portion 34 and thereby connect the outer surface 26 to the hollow interior of conduit 30. As such, at least a portion of the burner apertures 38 are not defined by or in contact with the artificial log 18.
In this particular embodiment, a plurality of [0034] burner apertures 38 are shown, but it should be understood that the number of burner apertures 38 within the burner portion 34, as well as the size of the burner portion 34, and the size of the burner apertures 34 may vary from one embodiment to the next, limited only by the available space and desired appearance and function of the finished burner apparatus 10.
The [0035] outer surface 26 also includes a second non-burner portion 40 adjacent and abutting the first burner portion 34. The second portion 40 does not include any burner apertures therein, and can generally be defined as the portion of surface 26 that abuts and is about the burner portion 34. Preferably, the second portion 40 includes most or all of the surface 26 that is disposed within the artificial log 18, and is not exposed to the external environment, as will be discussed more fully below.
The [0036] burner structure 14 is generally made of a non-combustible material. The burner structure 14, and especially the burner portion 34 of the burner structure 14, is preferably made of a material that is known to be useful as an efficient burner surface for a gas burner. For example, the burner structure 14 can be made from non-combustible metals, and other such material. Preferably, the combustion structure is made of a non-combustible metal such as steel, aluminum, iron or other such metals. Most preferably, the burner structure 14 is stainless steel or an aluminized metal.
In some embodiments, the [0037] burner structure 14 can include a retaining member 41. The retaining member 41 is an elongated flange extending from the surface 26 of the burner structure 14 that acts to retain the burner structure 14 within the artificial log 18 when the log 18 is formed around the burner structure 14.
The [0038] hollow conduit member 22 is adapted to be a gas supply conduit from a gas supply source (not shown) to the burner apertures 38. A gas supply source (not shown) can be provided for communication with the first end 24 to supply a fuel gas or a fuel gas/air mixture to the burner structure 14. Any gas supply source or structure, such as a gas supply line, or a gas supply line including a venturi or mixing valve, that is generally known in the art, may be used and connected to the first end 24.
The [0039] artificial log 18 is disposed at least partially around the gas burner structure 14, and includes an outer surface 44, an inner surface 48, a first end 52 and a second end 56. The end 24 of the burner structure 14 extends through the outer surface 44 of the log 18 for connection to a gas supply source (not shown). In the embodiment shown, the end 24 of the burner structure 14 extends through the outer surface 44 at the first end 52, but it should be understood that in other embodiments, the end 24 of the burner structure 14 may extend through the surface 44 of the log 18 at other locations, depending only upon the desired structure and use of the burner apparatus 10.
Preferably, the inner surface of the [0040] log 18 is at least partially disposed around and is in communication with or abuts at least a part of the outer surface 26 of the burner structure 14. More preferably, the log 18 is molded or formed to burner structure 14 such that at least part of the second portion 40 of the outer surface 26 is in intimate contact with or abuts at least a part of the inner surface 48 of the log 18.
The [0041] log 18 is disposed around the burner structure 14 such that the burner portion 34 is not covered by the log, thereby leaving the burner portion 34 exposed to the external environment. Preferably, the burner portion 34 includes enough surface such that the artificial log 18 is substantially spaced from the burner apertures 38. Therefore, the burner apertures 38 on the burner portion 34 include at least a portion thereof that is not surrounded by, defined by, or in contact with, the material of the artificial log 18. As such, the artificial log material is generally spaced from the functional burner surface 34, and the cooling effect of the artificial log material on the flame generated by the combustion gas at the burner surface 34 is reduced. Therefore, there is a more efficient burn and more complete combustion of the gas as compared to prior art log burners where the artificial log material defined the burner apertures, and thereby cooled the flame.
The [0042] artificial log 18 can be made of any generally non-combustible materials known in the art for making artificial logs. Preferably, the artificial log is made of ceramic or refractory materials generally known in the art, and is made using molding, forming, or casting techniques to mold, form, or cast the artificial log 18 onto the burner structure 14 such that the burner portion 34 is exposed. More preferably, the artificial log is made from a moldable slurry of ceramic fibers, preferably vitreous aluminum silicate fibers, and a binder, preferably amorphous silica, to form strong fiber reinforced ceramic logs. The preferred methods for making the artificial log are discussed in more detail below in reference to FIGS. 4-6.
The [0043] outer surface 44 of the log 18 is preferably shaped, textured and colored to imitate a burning log or piece of wood. It should be understood that different embodiments can have different log shapes, colors, and sizes, just as natural logs have different shapes, colors and sizes. The outer surface 44 also preferably defines at least one burning zone 60 where the burner portion 34 is exposed, as discussed above. The burning zone 60 generally defines a slot or gap in the outer surface 44 of the log, and therefore, in one respect, the burner portion 34 can be described as being exposed adjacent to or contiguous with the outer surface 44 of the artificial log 18.
The exposed [0044] burner portion 34 can be colored to match the color of the log to provide a more realistic look. For example the burning zone 60 and the burner portion 34 can be colored black to simulate burnt or burning wood.
The [0045] burner apparatus 10 can be used wherever it is appropriate and desirable to simulate a burning log or piece of wood using a gas flame. The apparatus 10 is particularly well suited for burning in the combustion chamber of a gas fireplace, stove, grill, or other such applications.
FIG. 2 illustrates a second embodiment of a [0046] burner apparatus 10 that is similar to the one shown in FIG. 1, wherein like reference numerals identify like elements. However, in the embodiment shown in FIG. 2, the end 24 of the burner structure 14 extends through the outer surface 44 of the log 18 for connection to a gas supply source at a side of the log 18. As discussed above, it should be understood that in other embodiments, the end of the burner structure may extend through the surface of the log at other locations, depending only upon the desired structure and use of the burner apparatus 10.
Although the above remarks described embodiments of the invention in relation to a [0047] single burner apparatus 10, it is to be understood that the burner apparatus can be used in conjunction with other artificial logs or burner assemblies. Additionally, a plurality of burner apparatuses embodying the invention can be used together in a burner system.
For example, referring to FIG. 3, a partial cross-sectional end view of one embodiment of a burner system, or log set [0048] 70, using a plurality of burner apparatuses is illustrated. Specifically, a front burner apparatus 10 a, a rear burner apparatus 10 b, and a transverse burner apparatus 10 c are shown. The burner apparatuses 10 a, 10 b, and 10 c are supported on a non-combustible grate 84, for example a ceramic or metal grate.
Each of the [0049] burner apparatuses 10 a, 10 b, and 10 c includes the same general structures as the burner apparatus 10 as described above in reference to FIG. 1, with the only potential difference being the shape, size, texture, color or configuration of the outer surface of the artificial log 18. Such features can be changed depending upon the desired look and feel of the system. Therefore, each of the burner apparatuses 10 a, 10 b, and 10 c includes a gas burner structure 14 including a generally hollow conduit member 22, and an artificial log 18 disposed at least partially around the burner structure 14. Furthermore, each burner structure 14 includes a surface 26 having a burner portion 34 (not shown in 10 a and 10 b) that is exposed adjacent the outer surface of the artificial log 18, and the burner portions 34 include burner apertures 38 for burning gaseous fuel.
The [0050] system 70 further includes a control box 74 which is connected to a source of gaseous fuel (not shown). Gas inlet pipes 78 a, 78 b and 78 c extend from the control box, and are in communication with the generally hollow conduit members 22 of the burner apparatuses 10 a, 10 b and 10 c. A fuel/air mixing system 82, such as a mixing valve, or a venturi cap, can be disposed in the pipes interconnecting the control box and the conduit members 22 for adjusting the air to fuel ratio. The structure of such mixing valve or venturi cap systems can be of any generally known in the art. Fuel is supplied through the control box 74, through the gas inlet pipes 78 a, 78 b and 78 c, into the hollow conduit members 22, and through burner apertures 38 wherein combustion takes place about the burner portions 34.
The system can include a pilot [0051] 94 to assist in lighting. It will be understood that the pilot will connect to the control box 74 via a gas line 98. It is optional to supply a lighter tube (not shown) between the burner portions 34 and the pilot 94. The pilot arrangement 94, however, may be replaced with an electronic spark ignition system (not shown) using a ground plate or spark plate on the rear of the burner apparatuses adjacent the burner portions 34 where the spark module would not be seen from the front.
The system can also include an [0052] ember simulating element 102 disposed below the grate for simulating glowing embers from a wood fire. Any such ember simulating elements that are generally known may be used. Typically, such elements 102 require a gas supply, and are thus connected to the control box 74 via a gas line 104. The element includes a structural member 108 that defines a hollow area 112 and small burner jets 114 that are generally termed glowing ember jets and do not emit long flames. The surface 116 of the structural member 108 can be adapted or shaped to look like embers or ashes from a wood fire. Optionally, emberizing material, such as rock wool, mineral wool, vermiculite, or other such ember or ash simulating material may be placed about the emberizing jets to further simulate ember or ash material.
Refer now to FIG. 7 and FIG. 8 showing front and cross-sectional views of a second embodiment of a [0053] gas burner apparatus 210. Gas burner apparatus 210 includes an artificial log 218. The artificial log 218 defines a gas passageway 229 and at least one burner aperture 238 and includes an outer surface 244 and an inner surface 248.
The [0054] outer surface 244 of the artificial log 218 includes the at least one burner aperture 238, therein. The burner aperture 238 extends through the artificial log 218 and thereby extends between the outer surface 244 and inner surface 248 to provide communication between passageway 229 and the surroundings of the artificial log 218.
The gas passageway [0055] 229 may be formed during the process of molding the artificial log 218 or may be drilled or machined after forming and processing the artificial log 218. The passageway 229 can pass through the entire length of or can partially pass through the artificial log 218. In an embodiment in which the passageway 229 passes through the entire artificial log 218, a plug or cap (not shown) can be provided at the ends of one of the gas passageway 229 to prevent the escape of gas. Alternatively, the artificial log can be constructed without a passageway and not be used as a gas burner.
In this particular embodiment, a plurality of [0056] burner apertures 238 are shown, but it should be understood that the number of burner apertures 238 within the artificial log 218, as well as the size of the burner apertures 238 may vary from one embodiment to the next, limited only by the available space and desired appearance and function of the finished burner apparatus 210.
The [0057] outer surface 244 also includes a coupling portion 245. The coupling portion 245 includes an aperture that allows for fluid communication between the gas passageway 229 and a hollow tube member 222. The hollow tube member 222 can be a piece of aluminum tubing or other metal tubing that is coupled to the coupling portion 245.
The [0058] hollow tube member 222 is coupled to the coupling portion 245 with any suitable attachment means, such as, for example, adhesive, screws, bolts, nails, rivets, pins, pressure fitting, and thermosetting. Alternatively, the hollow tube member can be threaded and the coupling portion machined so that the hollow tube member can be screwed into the artificial log element.
The [0059] coupling portion 245 can be located at any position on the outer surface 244 for coupling the hollow tube member 222 to the passageway 229.
The [0060] hollow tube member 222 is adapted to be a gas supply conduit from a gas supply source (not shown) to the passageway 229 and the burner apertures 238. The gas supply source (not shown) can be in communication with the passageway 229 and burner apertures 238 to supply a fuel gas or a fuel gas/air mixture to the outer surface 244 for combustion. Any gas supply source or structure, such as a gas supply line, or a gas supply line including a venturi or mixing valve, that is generally known in the art, may be used and connected to the hollow tube member 222.
The [0061] outer surface 244 of the log 218 is preferably shaped, textured and colored to imitate a burning log or piece of wood. It should be understood that different embodiments can have different log shapes, colors, and sizes, just as natural logs have different shapes, colors and sizes. The outer surface 244 also can define at least one burning zone 260 that surrounds burner aperture 238. Optionally, the burning zone 260 can surround multiple burner apertures. The burning zone 260 can be colored to match the color of the log to provide a more realistic look. For example the burning zone 260 can be colored black to simulate burnt or burning wood.
The [0062] burner apparatus 210 can be used wherever it is appropriate and desirable to simulate a burning log or piece of wood using a gas flame. The apparatus 210 is particularly well suited for burning in the combustion chamber of a gas fireplace, stove, grill, or other such applications.
Vacuum Molding Burner-Log Elements [0063]
With reference now generally to FIGS. [0064] 4-6, an example of one method for making one embodiment of a gas burner apparatus 10 of the invention will be described. As discussed briefly above, the artificial log 18 is preferably made of ceramic or refractory materials generally known in the art, and is made using molding, forming, or casting techniques to mold, form, or cast the artificial log 18 onto the burner structure 14.
The [0065] artificial log 18 can be made of any generally non-combustible materials known in the art for making artificial logs. Preferably, the artificial log is made of ceramic or refractory materials generally known in the art, and is made using molding, forming, or casting techniques to mold, form, or cast the artificial log 18 onto the burner structure 14 such that the burner portion 34 is exposed. More preferably, the artificial log is made from a moldable slurry of ceramic fibers, preferably vitreous aluminum silicate fibers, and a binder, preferably amorphous silica, to form strong fiber reinforced ceramic logs. The preferred methods for making the artificial log are discussed in more detail below in reference to FIGS. 4-6.
The [0066] artificial log 18 is made from a moldable slurry of ceramic fibers, preferably vitreous aluminum silicate fibers, and a binder, preferably amorphous silica. The moldable slurry is molded onto the burner structure 14 such that the burner portion 34 is exposed to make the burner apparatus 10. It is pointed out that U.S. Pat. No. 5,941,237 (the “'237 patent”), which is hereby incorporated herein by reference for all purposes, discloses a method of making fiber reinforced combustion chamber structures of the same general material. Therefore, the molding process used in the '237 patent to make combustion chamber structures is generally the same process used to mold the artificial log 18.
Initially, the moldable slurry of ceramic fibers must be made. The fibers of alumina silicate are mixed with a binder solution which is in aqueous form. The high temperature reinforced fibers preferably are made from a mixture of silica and alumina (SiO[0067] ₂and Al₂O₃) which are mixed and then melted and formed as fibers. The fibers are formed by blowing drops or portions of the melted mixture to form fibers that are graded by length and preferably are in a form of ½ to 1½ inches in length when mixed with amorphous silica. The preferred aqueous solution is a binder of amorphous silicate which may be purchased from Nalco Chemical Inc., in Naperville, Ill. under the designation Nalco 1140.
After the combination of fibers and binder solution are mixed together, they are agitated so that the fibers completely adsorb the binder solution. After the mixing and agitation occurs, a slurry or paste is formed that is of a consistency which permits the mixture to be used to fill molds or casts, and is ready to be molded or cast onto the [0068] burner structure 14. Although many casting or molding techniques may be used, preferably the burner apparatus 10 of the invention is formed using vacuum molding.
Referring to FIG. 4, a cross section of a [0069] vacuum mold 120 in an open position is shown, including a top 122 and a bottom 124 which together define a mold opening 126 in the desired shape of the artificial log 18. The mold opening 126 includes an upper surface 135 and a lower surface 136. The mold bottom 124 includes mold injection ports 128, and a vacuum evacuation port 130. The evacuation port 130 is interconnected with evacuation area 132 within the mold bottom 124, which is below screen member 134. The screen member 134 defines the lower surface 136 of the mold opening 126.
The top [0070] 122 and bottom 124 mold portions define an aperture 140 in the walls thereof in which a burner structure 14 can extend through to be properly positioned in the mold. The mold opening 126 is of such a shape, and the aperture 140 is of such an angle that when the burner structure 14 is properly placed in the aperture 140 and extends into the mold opening 126, a portion 144 of the upper surface 135 of the mold comes into contact with a portion of the outer surface 26 of the burner structure (FIG. 5). Specifically, the portion 144 of the upper surface 135 of the mold comes into contact with the burner portion 34 including at least one burner aperture 38 therein.
As seen in FIG. 5, once the [0071] burner structure 14 is properly positioned within the mold opening 126, and the mold is closed, the slurry or paste of mold material prepared above is forced into the mold through injection ports 128. As the mold fills with the mold slurry, water from the slurry is able to pass through the screen member 134, into the evacuation area 132 and out the evacuation port 130. Fiber from the slurry, however, cannot pass through the screen member 134, and is maintained in the mold opening 126. A vacuum is created at the vacuum port 130 to help evacuate water from the mold and dry the fiber when the mold is full. The fiber is maintained within the mold, and forms the artificial log 18 around the burner structure 14 (FIG. 6). Because a portion 144 of the upper surface 135 is in contact with the burner portion 34, the fiber cannot form artificial log 18 around the burner portion 34, thereby leaving the burner portion 34 exposed in the finished burner apparatus 10.
After the molding process is complete, the [0072] burner apparatus 10, including the artificial log 18 molded at least partially to the burner structure 14, is removed from the mold, and is dried by firing. In some embodiments, however, the artificial log material can be dried by being held in the mold, and heated. In the preferred embodiments the artificial log is dried by firing at a temperature between 350° F. and 1800° F. to drive off any of the remaining excess water from the mold solution.
After firing the [0073] burner apparatus 10, the artificial log 18 can be trimmed or machined to a final desirable shape, if needed, and colored as desired.
Compression Molding Burner-Log Elements [0074]
The first step involved in one embodiment of a compression molding method entails providing the molding composition. The molding composition generally includes inorganic fibers, binder, carrier solvent, and optional additives. A more detailed discussion of some embodiments of the molding composition will be provided below. [0075]
The next step entails compression molding the molding composition. Compression molding as used herein generally involves the use of a heated mold and compressive pressure produced by the mold to form the moldable composition into a desired shape. Many compression molding techniques may be used. For example, in some embodiments the mold comprises a plurality of matched dies, and in some embodiments, a pair of dies, for example male and female dies, that mate with each other to form a mold cavity or mold cavities. In some embodiments, the dies are attached to equipment that is designed to bring the dies together with enough compressive pressure to perform the molding. It is contemplated that in other embodiments, the weight of the dies can create enough compressive pressure to perform the molding. The dies are typically preheated to a molding temperature, and a measured quantity of moldable composition including inorganic fiber is placed in the heated mold. [0076]
In some embodiments, the moldable composition is placed in the heated mold when the mold is in the open position. The mold is then closed and the moldable composition, through pressure applied from the closing of the mold, fills the mold cavity. Continued heating at least partially cures the moldable composition within a relatively short period of time, in some embodiments within a matter of minutes, such that the molded article retains its shape. Pressure is then released, the dies are separated, and the molded article is removed from the mold. [0077]
It should also be understood that in some embodiments of compression molding, the moldable composition is forced into the heated mold through one or more injection ports using appropriate injection techniques when the mold is in the closed position. The moldable composition, through pressure from the injection process, and compression from the closed mold dies, fills the mold cavity, and is formed into the desired shape. Therefore, it will be understood that as used herein, the terms “compression molding” is intended to include embodiments using all types of known compression molding, including such injection techniques. [0078]
One particular embodiment of compression molding the moldable composition including inorganic fiber will now be described, with reference to FIGS. [0079] 9-11.
Referring to FIG. 9, a cross-sectional view of a [0080] compression mold 320 in an open position is shown, including a top die 322 and a bottom die 324 which together define a mold cavity 326 in the desired shape of an article 351 (FIG. 11) to be molded. The bottom die 324 includes a bottom member 325, a mold 327, and a bottom die press 328. The mold 327 includes a first portion 329 and second portion 331 that can be constructed to create any shape and/or texture to imitate a burning log or piece of wood. The mold 327 can include structures that create gas apertures in the molded article during the molding process.
The top die [0081] 322 includes a block portion 321 and a rod portion 323. The rod portion 323 can form a cavity within the article being molded, such as passageway 229 of artificial log 218. The rod portion 323 and the block portion 321 can be tapered to facilitate insertion into the mold cavity 326. Typically, a taper of about 2 to 5 degrees is used.
In the embodiment shown, the article to be molded is a burner-log element or artificial log for use in a fireplace assembly, for example, as part of a log set for a gas fireplace assembly. The [0082] mold cavity 326 includes an upper surface 335 and a lower surface 336. Typically, the mold surfaces 335 and 336 are hardened and highly polished. The mold may also include ejector pins (not shown), or other such structures as generally known in the art, to aid in the removal of the article when the molding process is complete. The dies are mounted on platens 340 and 342 of a press 344, for example a vertical hydraulic press. The press 344 is operated to open and close the mold 320, and typically is able to create the necessary compression pressure for molding.
The dies [0083] 322 and 324 are preheated to a predetermined molding temperature. In some embodiments, the molding temperature is over 400° F. in the range of 410° F. to 450° F., or in the range of 420° F. to 440° F., and typically at about 430° F. In some embodiments, the dies 322 and 324 are preheated using heated platens 340 and 342, and heat is transferred from the platens 340 and 342 to the dies 322 and 324.
The molding composition including [0084] inorganic fibers 350 is then introduced into the mold 327, and the press 344 is operated to close the mold 320 (FIG. 10). As the mold 320 is closed, the top die 322 inserts into the mold 327 and an appropriate amount of compression molding pressure is applied to achieve the desired molding. The necessary amount of molding pressure is dependent upon many variables, for example the size and complexity of the article being molded, the properties of the particular molding composition used, and other such parameters. In some embodiments, a compression pressure of up to 50 tons is applied. In other embodiments, a compression pressure in the range 1 to 20 tons, or in the range of 3 to 10 tons is applied.
The [0085] moldable composition 350, through pressure applied from the closing of the mold 320, fills and is formed into the shape of the mold cavity. Continued heating of the composition in the mold at least partially cures the moldable composition within a relatively short period of time, in some embodiments within a matter of minutes, such that the molded article retains its shape. The amount of time necessary can vary, depending upon the size and shape of the part, the properties of the particular molding composition used, and other such parameters.
Referring now to FIG. 11, the [0086] press 344 is operated to separate the dies 322 and 324. Bottom die press 328 is raised to allow for the separation of the first portion 329 and the second portion 331 and removal of the molded article 351, such as artificial log 18 and artificial log 218, from the mold 320.
During the separation of the dies [0087] 322 and 324, the rod portion 323 remains attached to the top die 322 to create a passageway 352, such as passageway 229, within the molded article 351. Alternatively, the rod portion can be disengagably attached to the top die. As the top and bottom dies are compressed through the closing of the mold, pressure exerted onto the rod portion from the forming article, such as an artificial log, places the rod portion and forming article into engagement. When the dies are separated the rod portion remains engaged with the artificial log and disengages from the top die to form a structure, such as gas burner structure 10. The rod portion can be a hollow tube, such as hollow conduit member 22, in which the embedded end of the tube is closed to prevent the moldable composition used to make the artificial log from filling the tube. The opposing end of the tube includes an aperture in which gas can pass from a gas source, into the burner structure, and out gas apertures that can be drilled or machined into the tube for combustion.
In another alternative, the rod portion can be removed from the top die. An insert can be placed within the mold prior to compression of the molding composition. The insert can be made of polystyrene, urethanes, polyurethanes, or any other material that can burn at temperatures below 1000° F. As the mold composition is compressed, the molded article forms around the insert. Following removal from the mold, the molded article can be heated to bum off the material that forms the insert, leaving a passageway, such as passageway [0088] 229, within the artificial log. The insert can also be used to form gas apertures between the inner surface and outer surface of the artificial log.
After the molding process is complete, and the molded article is removed from the mold, it can be further dried by either air drying, or in some cases, by oven drying or firing. In some embodiments, however, the article can be dried by being held in the heated mold for a longer period of time to achieve the desired drying. [0089]
For larger articles, for example, a molded combustion chamber, additional drying can be achieved by oven drying after removal from the mold at a temperature in the range of 350° F. and 1800° F., more preferably in the range of 650° F. to 750° F. for a sufficient amount of time to drive off any of the remaining excess carrier solvent, for example water, from the mold composition. The dry time depends greatly upon the method of drying used, and the article being formed. [0090]
After the drying, the article can be trimmed or machined to a final desirable shape, if needed, and colored as desired. [0091]
Compression Molding Composition Formulation [0092]
The molding composition generally includes inorganic fibers, binder, carrier solvent, and optional additional additives. [0093]
The inorganic fiber is generally described as fibers made of one or more inorganic materials. Some examples of inorganic fibers include glass fibers, ceramic fibers, refractory fibers, refractory ceramic fibers (RCFs), mineral fibers, or other like inorganic fibers, or mixtures thereof. Such fibers can include, for example, staple fiber, spun fiber, continuous fiber, bulk fiber, filament fiber or wool fibers or the like, or mixtures thereof. Additionally, the fibers can be in a broad variety of forms, for example, in a crystalline or polycrystalline form, or the like, or mixtures thereof. RCFs, along with fibrous glass and mineral wool, are often times grouped as man-made materials generally referred to as synthetic vitreous fibers (SVFs). All these products are made from molten masses of raw materials, under controlled conditions. [0094]
In some embodiments the fibers are selected from chopped fiber glass, alumina silicate RCF, or mixtures thereof. In some embodiments, especially those for use in high temperature environments, it is preferable to use fibers that can withstand high temperatures. For example, in such embodiments, it is preferable to use fibers that can withstand temperatures of at least 800° F., more preferably at least 1000° F., more preferably at least 1200° F., and more preferably 1300° F., without significant degradation or deterioration due to the heat. Significant degradation results in a breakdown of structural properties of the compression molded components until the article being formed is unusable. [0095]
The size of the inorganic fibers can vary greatly, depending upon many variables, for example the particular article being molded, or the desired properties or characteristics of the molding composition or the finished article. In some embodiments, the fibers range in length from less than {fraction (1/16)} of an inch to two inches, preferably from {fraction (1/16)} of an inch to 1 inch, and more preferably from ⅛ of an inch to ½ of an inch. In some embodiments, the fibers have a diameter in the range of 1 micron to 30 microns, preferably in the range of 4 microns to 9 microns, and more preferably in the range of 5 microns to 7 microns. [0096]
The fibers can make up a major component of the composition, for example in some envisioned embodiments, up to 80% or more of the composition. However, in some embodiments, a significant amount of fillers, for example inorganic fillers, can be used, thereby reducing the necessary concentration of inorganic fiber. [0097]
The binder used acts to bind the components of moldable composition together when cured during the molding process. The binder includes inorganic or organic binders generally known, or mixtures thereof. Examples of binders include silica, sodium, calcium, and magnesium based binders, and the like, or mixtures thereof. Other examples include polymeric materials, petroleum distillate, polyethylene oxide, and the like, or mixtures thereof. In some embodiments, the binder can be hydrous, anhydrous, crystalline, or amorphous. In some embodiments, the binder within the molding composition is in the form of a dispersion, emulsion, slurry or solution with the carrier medium. [0098]
In some embodiments, especially those for use in high temperature environments, it is preferable to use binders that can withstand high temperatures. For example, in such embodiments, it is preferable to use binders that can withstand temperatures of at least 600° F., or at least 800° F., or least 1000° F., or at least 1200° F., and more preferably at least 1300° F., without significant degradation or deterioration due to the heat. The preferred binders include amorphous silica. [0099]
The carrier solvent typically acts to create a dispersion, emulsion, slurry or solution with the rest of the components. Preferably, the moldable composition is in the form of a slurry. In most embodiments, the carrier solvent is burned off or leaves due to the heat during the molding process, and little or none remains in the finished molded article. The preferred carrier solvent for most embodiments is water. In at least some embodiments, the moldable composition preferably includes water as the primary carrier solvent. The composition preferably has a moisture content in the range of 20 to 35%, more preferably 23 to 30%, and most preferably 25 to 27% by weight of the total composition. [0100]
Additional additives can optionally be included within the molding composition to provide the molding composition or the final molded article with desirable properties. For example, additives can be included to enhance the emulsion or dispersion of the components of the composition, to enhance the moldability of the composition or to enhance the appearance or physical properties of the molded article. Some examples of additives include inorganic or organic fillers, surfactants, diluents, thickeners, solvents, dyes or colorants, or other appearance enhancing materials, and the like, or mixtures thereof. [0101]
Fillers can be used, for example, to increase the volume of the composition and reduce the necessary amount of inorganic fiber. Additionally, some fillers can be added to impart desired properties to the final molded article. Examples of fillers include inorganic or organic fillers that are compatible with the other components in the composition. Preferred fillers include inorganic fillers, for example silica compounds, such as alumina silicate, crystalline silica, and the like. Another example of an inorganic filler includes ceramic microspheres, and the like. [0102]
In some embodiments, an example of a preferred emulsion or dispersion agent is petroleum distillate, hydrotreated light. This material can also act as a carrier in the formulation. Nonylphenol polyethylene oxide is another example of a dispersing or emulsifying agent that can also act as a surfactant. [0103]
In some embodiments, an organic polymer, such as an acrylic polymer, is added to the composition to act as a dispersing agent, and also to act as a molding thickener to help the composition hold shape when it is being molded. Typically, this type of material is burned off during the molding process. The organic polymer can be present in the composition in the range of about 0.1 to about 5%, more preferably in the range of 0.1 to 1%, and more preferably in the range of 0.1 to 0.5%, by weight of the total composition. It is contemplated that these, and many other additives, can be used in compositions embodying the invention. [0104]
Representative constituent concentrations for base components of some examples of moldable compositions embodying the invention can be found in Table 1, wherein the values are given in wt. % of the ingredients in reference to the total composition weight. [0105]

TABLE 1

Exemplary wt. % Preferred wt. % More Preferred

Component Range Range wt. % Range

Inorganic Fiber up to 80%, 25% or less 10% or less

but preferably

75% or less

Binder

10 to 40% 15 to 35% 20 to 30%

Carrier Solvent 15 to 45% 20 to 40% 25 to 35%

Additives

0 to 70% 25 to 80% 33 to 54%

Some embodiments of moldable compositions comprise the constituent concentrations for base components as found in Table 2, wherein the values are given in wt. % of the ingredients in reference to the total composition weight.

TABLE 2


	Example wt. %	Preferred wt. %	More Preferred
Component	Range	Range	wt. % Range

Inorganic Fiber	25%	or less	10%	or less	5%	or less
Inorganic Binder	10	to 40%	15	to 35%	20	to 30%
Water	15	to 45%	20	to 40%	25	to 35%
Inorganic Filler	15	to 70%	20	to 60%	30	to 54%
Other additives	0	to 10%	0	to 5%	0.1	to 2%

In some embodiments, the molding composition is made by mixing the inorganic fibers and any filler with a binder solution that is in aqueous form and includes any additional additives. After the combination of fibers, filler and binder solution are mixed together, they are agitated so that the fibers completely adsorb the binder solution. After the mixing and agitation occurs, a slurry or paste is formed that is of a consistency that permits the mixture to be used to fill the compression mold, and is ready to be compression molded. [0107]

One specific example of a molding composition comprises the constituent concentrations for base components as found in Table 3, wherein the values are given in wt. % of the ingredients in reference to the total composition weight.

	TABLE 3


	Component	Weight Percent

	Chopped Fiber Glass	3.3%
	Colloidal Silica (in a	60%
	50% water solution)
	Alumina Silicate	34%
	Acrylic Polymer	0.2%
	Ceramic Micro spheres	2.5%

Another specific example of a molding composition comprises the constituent concentrations for base components as found in Table 4, wherein the values are given in wt. % of the ingredients in reference to the total composition weight.

	TABLE 4


	Component	Weight Percent

	Chopped Fiber Glass	3.66%
	Colloidal Silica (in a	19%
	50% water solution)
	Alumina Silicate	48.35%
	Acrylic Polymer	0.22%
	Ceramic Micro spheres	2.77%
	Water
	26%

One preferred moldable slurry of ceramic fibers is a product named THERMOSEAL® Moldable P244, which is commercially available from Mid-Mountain Materials Incorporated of Seattle, Wash. Another preferred moldable slurry of ceramic fibers is a product named THERMOSEAL® Moldable P254, which is commercially available from Mid-Mountain Materials Incorporated of Seattle, Wash. [0110]
In some embodiments, the molding composition or the finished article, are made up of primarily inorganic materials. For example, in some embodiments, the molding composition or the finished article include at least 75% by weight inorganic material, or in other embodiments, at least 90% by weight inorganic material, and in still other embodiments, at least 95% by weight inorganic material, and sometimes at least 99% by weight inorganic material. It is also contemplated that in some embodiments, the molding composition, prior to molding, includes a mixture of inorganic and organic material, but that a significant portion of the organic material will be burned off, or leave during the molding process, leaving the final compression molded article to be made up of primarily inorganic materials. In some embodiments, especially those for use in high temperature environments, it is preferable that the final compression molded article comprises materials that can withstand high temperatures. For example, in such embodiments, it is preferable to use fibers, binders, or any other optional ingredients, such as fillers, that when molded into the final article can withstand temperatures of at least 600° F., or at least 800° F., or least 1000° F., or at least 1200° F., and more preferably at least 1300° F., without significant degradation or deterioration due to the heat. [0111]
The present invention should not be considered limited to the particular examples or materials described above, but rather should be understood to cover all aspect of the invention as fairly set out in the attached claims. Various modifications, equivalent processes, as well as numerous structures to which the present invention may be applicable will be readily apparent to those of skill in the art to which the present invention is directed upon review of the instant specification. [0112]

Claims

We claim:

1. A method of forming an artificial log, the method comprising the steps of:

providing a molding composition comprising an inorganic fiber and an inorganic binder;

compression molding the molding composition into the artificial log; and

providing a gas passageway defined by the artificial log and at least one burner aperture defined by the artificial log to pass combustible gas to an outer surface of the artificial log.

2. The method of claim 1, further comprising the step of coupling a hollow tube member to the artificial log.

3. The method of claim 1, wherein the molding composition comprises an inorganic fiber, an inorganic binder, and a carrier solvent.

4. The method of claim 3, wherein the inorganic fibers are glass fibers, ceramic fibers, refractory fibers, refractory ceramic fibers, mineral fibers, or mixtures thereof.

5. The method of claim 3, wherein the inorganic fiber comprises chopped fiber glass.

6. The method of claim 3, wherein the inorganic binder comprises silica, sodium, calcium, and magnesium based binders, or mixtures thereof.

7. The method of claim 3, wherein the inorganic binder comprises colloidal silica.

8. The method of claim 3, wherein the carrier solvent comprises water.

9. The method of claim 1, wherein the molding composition has a moisture content in the range of 20 to 35% by weight of the molding composition.

10. The method of claim 3, wherein the molding composition has a moisture content in the range of 25 to 27% by weight of the molding composition.

11. The method of claim 1, wherein the artificial log is an article for use in a fireplace assembly, a grill assembly, a campfire assembly, or a burner assembly.

12. A method of forming an artificial log, the method comprising the steps of:

providing a molding composition comprising inorganic fibers and a binder;

compression molding the molding composition into the artificial log, wherein at least 75% by weight of the molded article is inorganic material; and

providing a passageway defined by the artificial log and at least one burner aperture defined by the artificial log to pass combustible gas to an outer surface of the artificial log.

13. The method of claim 12, wherein at least 90% by weight of the artificial log is inorganic material.

14. The method of claim 12, wherein at least 95% by weight of the artificial log is inorganic material.

15. A method of forming an artificial log, the method comprising the steps of:

providing a molding composition comprising inorganic fibers and a binder;

compression molding the molding composition into the artificial log such that the binder transforms into a cured binder, wherein the cured binder is capable of withstanding temperatures of at least 600° F.; and

16. The method of claim 15, wherein the cured binder is capable of withstanding temperatures of at least 800° F.

17. The method of claim 15, wherein the binder comprises an inorganic binder.

18. A method of forming an artificial log, the method comprising:

providing a molding composition comprising inorganic fibers and a binder;

compression molding the molding composition into the artificial log, wherein the artificial log is capable of withstanding temperatures of at least 600° F.; and

19. The method of claim 18, wherein the artificial log is capable of withstanding temperatures of at least 800° F.

20. The method of claim 18, wherein the binder comprises an inorganic binder.

21. An artificial log made by the method of compression molding of claim 1.

22. An artificial log made by the method of compression molding of claim 12.

23. An artificial log made by the method of compression molding of claim 15.

24. An artificial log made by the method of compression molding of claim 18.

25. An artificial log comprising an inner surface defining a passageway in fluid communication with at least one burner aperture defined by the artificial log; and wherein the artificial log is compression molded.

26. An artificial log comprising an outer surface, wherein the outer surface of the artificial log defines at least one burner aperture to provide combustible gas to the outer surface; and wherein the artificial log is compression molded.