Abstract:
A process for making an artificial mineral or ceramic panels that can be used in gas fireplaces. The process uses a screen mold having simulated pattern elements to impart a realistic exterior surface to the article. A slurry of mineral fibers is injected under pressure into the mold forcing excess water therethrough leaving the fibers impinged within the mold. The article thus formed is dried in an oven and can be processed for additional decorative coatings.

Description:
This is a CIP of U.S. patent application Ser. No. 09/318,688, filed May 25, 1999, now abandoned. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Technical Field 
     This invention is directed to a process of molding artificial and decorative panel and logs for use in gas equipped fireplaces. 
     2. Description of Prior Art 
     Prior art processes for artificial log and constructing panels manufacturing typically use a screen mold with textured surface elements on the screen that is form fitted into an apertured support mold cavity into which a slurry of mineral or ceramic fibers is deposited. A vacuum is then applied to the mold drawing the liquid therefrom, leaving the mineral fibers collected on the screen surface. The log or panel is removed from the mold and dried in an oven to eliminate the remaining moisture present after molding of approximately 50%. After an extended drying time in the oven the log is removed and color coded for realism and then redried ready for use. See for example U.S. Pat. Nos. 4,877,417, 5,271,888, 5,284,686, 5,612,266, 5,700,409 and 5,800,875. 
     In U.S. Pat. No. 4,877,417, an artificial fireplace log is disclosed which is partially combustible having a clay carrier and consumable wood fiber portions. 
     U.S. Pat. No. 5,271,888 is directed towards a ceramic log molding process for forming lightweight synthetic ceramic logs having a flexible porous pattern screen using a vacuum source for withdrawing water from the mold slurry forming a log representation within the mold. 
     A combustible artificial log is disclosed in U.S. Pat. No. 5,284,686 having a composite log formed of ceramic concrete with ceramic fiber sections. 
     U.S. Pat. No. 5,612,266 shows a decorative non-combustible synthetic fire log formed my mineral foam in a mold shape as a nature wood log. The mineral foam composition is claimed. U.S. Pat. No. 5,700,409 discloses a method of molding an article in which a flexible mold having an article forming cavity is affixed to a suction chamber so as to release their article within the mold after the molding process. 
     Mineral fiber log processing is disclosed in U.S. Pat. No. 5,800,895 wherein a screen mold is used to impart an exterior log surface. A slurry containing mineral wool fibers is drawn into the mold by a vacuum leaving the mineral fibers within the mold. 
     SUMMARY OF THE INVENTION 
     An improved process for molding synthetic fiber logs and decorative panels used in gas fireplaces. The process uses a textured screen with a mold body into which a slurry of synthetic mineral wool fiber is injected under pressure and then molded under increased air pressure by driving the liquid out of the mold through a plurality of apertures. Once molded, continued air pressure partially dries the formed article to low moisture content in a shortened cycle time. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an exploded perspective view of an open log mold with fixed mesh lining and separable flexible porous screen to be positioned within the mold; 
     FIG. 2 is a cross-sectional view of the closed log mold illustrating a slurry inlet opening and plurality of grooves elongated longitudinally aligned grooves for liquid removal; 
     FIG. 3 is a partial cross-sectional view of the log mold within a mold station capture enclosure illustrating slurry inlet and liquid outlet portals in the mold base; 
     FIG. 4 is a block diagram of the required components of the pressure injection drawing process of the invention; 
     FIG. 5 is a cross-sectional view of an alternate mold base having a plurality of liquid clear apertures therein; 
     FIG. 6 is an exploded perspective view of a heat resisting fireplace construction panel illustrating support frames and mold screens; 
     FIG. 7 is a cross-sectional view of a closed mold shown in FIG. 6 within a mold station aperture enclosure with multiple slurry supply inlets and outlet portions in the base of the enclosure; and 
     FIG. 8 is a perspective view of a molded decorative panel. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     In the present improved process for molding synthetic logs for use in gas fireplace environments, a first step is illustrated in FIGS. 1-3 of the drawings wherein a two-piece mold assembly  10  can be seen having a base body member  11  and a removable top portion  12 . Both the base body member  11  and removable top portion  12  have hollowed out interior surfaces  11 A and  11 B respectively for the formation of a log shaped cavity therebetween. The base and top members  11  &amp;  12  have a plurality of elongated aligned surface grooves  14  connecting the interior surface  11 A to its exterior surface  11 C through outlet apertures  14 A. A non-corrosive metal mesh  15  is contoured within the inner surface  11 A of the base body member  11  and acts as a first channel diffuser of liquid in the process. 
     It will be evident from the above description that the base and top body members  11  and  12  respectively are removably secured by conventional molding processes together as will be well understood by those skilled within the art. The base and top body members  11  and  12  are typically made from castable synthetic compound as is illustrated in this example. 
     A flexible metallic mesh  16  preferably with a 46% open porosity rate is used as the actual molding surface  17  and has a realistic texture imparted thereon by the employment of synthetic appliques  17 A bonded thereto for imprinting the natural look surface to the molded article. Typically, these appliques are applied to represent realistic exterior surface of naturally occurring logs thus imitating a bark consistency with various textures employed therein. 
     The assembled mold  10  has an inlet opening at  18  in the top body member for registration of an injection pipe  19 , best seen in FIG. 3 of the drawings. The entire mold assembly  10  is mounted within a retainment enclosure  20  defining a mold station  21 . The retainment enclosure  20  defines a liquid containment and collection structure having multiple upstanding sidewalls  22  with an integral base  23  and access lid  24  hingeably secured thereto so that an operator (not shown) can readily open and access the mold assembly  10  within for removal of the molded article after the molding process. The retainment enclosure&#39;s integral base  23  has a plurality of drain openings  25  communicating with a return pipe  27  for liquid associated with the molding process. 
     Referring now to FIG. 4 of the drawings, a systematic sequence steps can be seen wherein a storage and supply batch tank  28  is filled with a well known mold slurry formulation MS comprising; water, ceramic fiber, starch, and coloidal cilica/sol components. Such slurry formulations are typically set forth in the following batch ratios by weight; water 2,075 lb., ceramic fiber 30 lb., coloidal cilica/sol 3.125 lb. and chromite 1.50 lb. and starch 1.375 lb. 
     The ceramic fiber is manufactured by a number of companies, an example of same is brand name Fiber Frax, produced by the Carboriadue Company. The fibers are non-combustible with a stable reactivity and are made from alumina and silica and maintains their properties up to a temperature gradient of 2,300 Farenheit. 
     The coloidal cilica/sol has a positive charge for imparting adherence to themselves. 
     The chromite compound is generally made up of an iron chromite ore with a 3,800 degree Farenheit in this example chosen for illustration. The starch component preferably comprises a starch material made by Chemstar Products Company under the brand name Glucopus having a negative charge and is used to enhance the handling properties of the composition and formed log. 
     The hereinbefore described disclosed fiber slurry is discharged into a batch injection tank  29  by gravity flow through valve means  29 A. The batch injection tank  29  is pressurized by a source of air pressure  30  by a supply line  30 A and valving means  30 B. An injection control valve  31  opens imparting the batch injection tank content slurry under a positive pressure range of 10-20 psi into the mold assembly  10  via a supply line  31 A as best seen in FIG. 3 of the drawings, filling the mold cavity within. The injection control valve  31  is then closed and a drying control valve  32  is opened to a second source of compressed air  33 . Air pressure supply to the mold assembly  10  in the range of 35 to 40 psi forces the liquid L out through the drain openings  25  within the mold base  23 . 
     The water is driven out of the mold assembly  10  leaving the ceramic fibers collected on the molding surface  17  of the synthetic mesh  16  within. The water is captured within the retainment enclosure  20  collected and returned to a recycled water storage tank  34 . After an express drying cycle of approximately three minutes, the retainment enclosure  20  is open and the log is retrieved from the mold assembly  10  having a highly reduced total moisture content in the range of approximately 30%. 
     The coalesce log L is transferred to an initial drawing chamber  35  to complete the initial formation of the ceramic fiber log. 
     Referring now to FIG. 5 of the drawings, an alternate mold assembly  38  is disclosed wherein an alternate mold base  39  can be seen having a plurality of liquid dispersion apertures  40  extending from an inner surface  41  to the outer exterior surface  42  of the mold base  39 . The alternate mold assembly  38  is used within the hereinbefore described retainment enclosure  20  and is injected with the mold slurry MS in the same manner as that of the previous mold assembly  10  described above. 
     Referring now to FIGS. 6-8 of the drawings, an artificial fiber panel mold  43  and associated molding process for decorative heat resistant fireplace panels  44  can be seen. The molding apparatus chosen to illustrate the process in this example has a pair of oppositely disposed support frames  45  and  46 . Each of the support frames  45  and  46  have a generally square metal frame  47  with a pair of spaced parallel transversely extending braces  47 A and  47 B extending therebetween. 
     An apertured non-corrosive metal mesh  48  extends across and is secured to each support frames  45  and  46 . A metallic mesh  49  having a 40% open surface being the actual molding surface extends over the respective apertured metal mesh  48  in abutting relation thereto. 
     In the example chosen for illustration, a raised brick mold pattern BP is bonded to the inner surface  49 A of one of the mesh surfaces  48  so as to imprint a brick pattern onto the side of the molded panel. The mold pattern BP consist of interengaging raised bands of metal which provide a negative impression illustrating the joints between the brick as would be found on a normal brick panel laid up with brick and mortar (not shown). 
     A mold frame  50  is removably positioned between the respective hereinbefore described support frames  45  and  46 . The mold frame  50  is formed from a plurality of interconnected frame bars  51 A,  51 B,  51 C and  51 D each which is cross-sectionally square having an inlet and outlet apertures  52  inwardly of one end thereof. Slurry supply lines  53  communicate with fittings  55  in each of the respective apertures  52  and are interconnected to a supply of the mold slurry formulation MS as hereinbefore described. 
     The assembled panel mold  43  is placed within a modified liquid containment and collection structure  54 , best seen in FIG. 7 of the drawings having multiple upstanding sidewalls  55  and integral base  56  with a hinged access lid  57  for operator access thereto as will be well known to those skilled in the art. 
     A plurality of drain and return apertures  58  are formed within the bottom  56  in communication with a product return pipe  59 . 
     In operation, the panel mold  43  is hooked up to the hereinbefore described batch injection tank  29  pressurized by the air pressure  30 , etc. The mold slurry MS is injected into the panel mold  43  by the multiple slurry supply lines  53  and the registering apertures therein. 
     The slurry is thus injected by the multiple aperture injection ports  52  imparting a vortex fill action within the cavity of the panel mold  43 . The mold slurry MS passes over and through the screen mold surfaces  49  depositing interlocking fibers thereon building up a solid mass within the cavity forming the synthetic fiber panel  44 , best seen in FIG. 8 of the drawings. 
     The panel  44 , in this example, has a brick pattern  60  on its exterior surface  61 . The panel thus formed has a greatly reduced moisture content by the mold steps reducing drying time and consequently production time. The result is a high quality finished heat resistant molded panel with a molded decorative surface. 
     It will thus be seen that an improved process for molding synthetic logs and panels for use in gas fireplaces wherein the logs and panels L have an initial lower moisture content by use of the pressure injection and drawing sequences which reduces the primary oven drying cycle. Additionally, it will be seen that by use of the pressure collation and primary drying steps a much finer texture detail is imparted to the finished surfaces than hereinbefore has been possible with traditional dip vacuum molding process. 
     It will be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit of the invention.