Abstract:
A flanged plumbing fixture having two planar fabric mortar-bondable face layers fused to opposite sides of a planar plastic core layer is made by aligning two preformed fabrics on top of each other, with connecting elements positioned between the fabrics and bonded to each of the two fabrics, positioning the connected two fabrics in a mold and centering the connected fabrics inside the mold by the connecting elements, injecting a plastic material through openings in the connecting elements, and filling the space between the two fabrics with the plastic material.

Description:
RELATED APPLICATIONS 
     This application is related to application Ser. No. 13/934,284, filed concurrently herewith for “Integrated Bonding Flange Support Disk for Prefabricated Shower Tray” granted on Apr. 12, 2016, as U.S. Pat. No. 9,307,869. 
     BACKGROUND 
     The present invention relates to the construction of waterproof systems in the mortar-bonded environment. Such environments typically include tiled floors and walls and associated fixtures and drains (e.g., in showers). 
     Conventional methods of installing ceramic tile shower floors have typically included several steps. First, a sloped mortar bed is installed that slopes from an edge (e.g., a wall, a curb, or some other border) to the position of a drain in a subfloor. This mortar bed is typically referred to as sloped fill, or “pre-slope”. A waterproof barrier, commonly referred to as a shower pan liner, is subsequently positioned over the sloped mortar bed and fixed to the drain. Conventional shower pan liners are not designed to bond to a substrate or to ceramic or stone tile and thus a second non-bonded (“floating”) mortar bed must be overlaid to provide a load distribution layer and bonding surface for the tile. To have sufficient strength and mass, such non-bonded mortar beds for shower floors should have a minimum thickness of at least about 1.50-inches and should be reinforced with galvanized wire mesh to comply with industry standard guidelines. This method of shower floor construction has proven over time to be reliable when properly built, but requires a high degree of trade knowledge and skill and takes considerable time to construct. 
     More recently, changing consumer preferences, designer influences, and in some cases the unavailability of craftsmen skilled in these techniques have driven changes in consumer preferences, and in the manner in which such showers (or equivalent structures) are constructed. In particular, the trends point toward simplified shower installation methods and systems. 
     To facilitate these trends, integrated systems have recently been developed that use lighter materials, and that can be installed using quicker, simplified methods. Much of this progress has been made possible with the advent of a new generation of materials that allow each layer to be bonded to the previous. Many of these materials that have been developed in recent years have incorporated fabric faces which are integrally molded onto component faces. In particular, because the relevant mortar materials mechanically lock to the open three dimensional structure of the fabric face, the fabric faces enable waterproofing membranes, drains and other components to be mortar bondable. In some cases these systems are formed of a prefabricated shower tray (typically formed of polymer foam) which is mortar bonded to the subfloor. In some typical systems, a waterproofing membrane, referred to as a load bearing, bonded waterproof membrane, is fixed to the foam tray with thin set mortar. The tile is then bonded over the membrane, again using thin set mortar. Thus, a typical integrated system could include (in order) substrate/initial mortar layer/shower tray/second mortar layer/membrane/third mortar layer/tile. 
     As a further convenience, a pre-manufactured flanged drain fixture can be positioned on the mortar on the tray to provide a structural location for the drain grate, to provide ample surface adhesion for the waterproofing membrane, and to connect the drain to the remainder of the plumbing. In many circumstances, the flanged drain fixture is formed to include a circular, square or rectangular flange with the drain opening in the desired location (typically the center). This flange is typically pressed against the thin set mortar on the tray and provides the necessary surface for adhering and bonding the waterproofing membrane. The flange also helps provide structural support for the final drain fixture and its grate. In a typical construction, after the flanged drain fixture is positioned on the foam tray (and mortar), another layer of thin set mortar is applied over the entire surface, following which a load bearing, bonded waterproof membrane is added. The final tile surface is added over the membrane, again using thin set mortar. 
     In order to provide adequate adhesion and form a water tight seal between the membrane, thin set mortar, and the flanged drain assembly, the top surface of the drain assembly has typically included an incorporated fabric layer. For a number of reasons, including conventional manufacturing techniques, the bottom of the flanged drain fixture, which likewise must be set with thin set mortar, has not included such an integrated fabric face. As a result, such drain flanges lack an adequate bonding surface between the bottom of the drain flange and to the thin set mortar that supports the drain flange assembly. Providing and maintaining support beneath the drain is nevertheless quite important because the drain area tends to experience much of the loading forces in this type of structure. 
     Accordingly, a need exists for a drain flange fixture that includes an integrated fabric on all surfaces (typically upper and lower) that receive or contact thin set mortar. 
     SUMMARY 
     In one aspect the method of the invention includes the steps of aligning two preformed fabrics on top of each other, with connecting elements positioned between the fabrics and bonded to each of the two fabrics, positioning the connected two fabrics in a mold and centering the connected fabrics inside the mold by means of the connecting elements, injecting a plastic material through openings in the connecting elements, and filling the space between the two fabrics with the plastic material. 
     In another aspect the invention is a method of forming a double fabric faced injection molded fixture. The method includes the steps of superimposing a first temperature resistant fabric on a rigid temperature resistant fixture plate, positioning a temperature resistant spacer on the first fabric opposite the fixture plate, placing an alignment pin in the spacer on the fabric overlying the fixture plate, superimposing a second fabric over the first fabric and spaced from the first fabric by the spacer while aligning the second fabric on the alignment pin, removing the alignment pins and adding a melted thermoplastic or thermosetting resin into the spacer, and through the spacer and between the fabrics while the fabrics and plate are clamped in a mold. 
     In another aspect the invention is a double fabric faced plumbing fixture. The fixture includes two planar fabric layers separated by a planar thermoplastic or thermoset core layer with each planar fabric layer fused to the plastic core layer. 
     In another aspect the invention is a spacer for injection molding. The spacer includes a support plate, a plurality of spacing uprights on the support plate for defining the spacing characteristics of the spacer, and with the spacing uprights defining an injection opening there between, and a pin cylinder depending from the support plate opposite the spacing uprights. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a gate button spacer according to the invention. 
         FIG. 2  is a perspective view of the aluminum fixture plate used in the method of the invention. 
         FIG. 3  is a perspective view of the fixture plate with the bottom face fabric positioned upon it. 
         FIG. 4  is a perspective view of the fixture plate with the bottom face fabric and the gate button spacers. 
         FIG. 5  is a perspective view of the fixture plate with the bottom face fabric and the gate along with the spacers and the alignment pins. 
         FIG. 6  is a perspective view of the fixture plate with the bottom face fabric, the gate spacer buttons, the alignment pins, and the top face fabric. 
         FIG. 7  is the same view as  FIG. 6  but showing the alignment pins removed after the top face fabric is positioned. 
         FIG. 8  is a perspective view of the completed fabric sandwich structure. 
         FIG. 9  is a partial perspective view of the top and bottom face fabric separated by the gate button spacer 
         FIG. 10  is a cross-sectional view corresponding to  FIG. 9 . 
         FIG. 11  is a partial perspective, partial cross-sectional view of stacked gate spacer buttons. 
         FIG. 12  is a partial perspective view of the top and bottom face fabrics, a gate spacer, and an injected plastic. 
         FIG. 13  is a perspective view of a finished flange. 
         FIG. 14  is another perspective view of a finished flange and a cutaway portion illustrating the fabric sandwich. 
         FIG. 15  is a cross sectional view of the gate button spacer and the top face fabric. 
         FIG. 16  is a cross sectional view of the gate button spacer and fabric in an injection mold. 
         FIG. 17  is another cross sectional view of the gate button spacer and fabric in an injection mold. 
         FIG. 18  is a perspective view of a drain alignment fixture. 
         FIG. 19  is a perspective view of the fabric layers for the drain alignment fixture. 
         FIG. 20  is a perspective view of a niche fixture. 
         FIG. 21  is a perspective view of the fabric layers for the niche fixture. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  is a perspective view of a gate button spacer or connecting element  20  according to the present invention. In order to accommodate the method of the invention as described herein, the gate button spacer is formed of a material that will withstand the temperature required for the injection molding step. In representative embodiments, the gate button spacer is molded from a thermoplastic or thermosetting resin that has a higher melting point than the melting point of the plastic injected to make the entire flange. The resin for the spacer can be any polymer resin that can withstand the structural stress of the mold and the temperature of the injection molded plastic for the flange. The selection is well understood by the skilled person, but (for example) thermoplastics with relatively high melting points can include fluoropolymers, liquid crystal polymers, polyamide, polyimide, polyarylate, polyether keytone, polyether imide and polysulfones. 
     In detail, the illustrated button spacer concludes a support disk  21  which carries a plurality (four are illustrated) of spacing cylinders  22  on its upper side. The spacing cylinders  22  each have an upper cylinder surface  23  and an inclined edge  24 . As illustrated in  FIG. 10 , the height of the spacing cylinders  22  defines the thickness of the eventual flange, and thus can be selected or designed for that purpose. 
     A pin  25  depends from the support disk  21  and terminates in a pin frustum  26 . The frustum  26  eases the alignment of the gate button spacer with the alignment openings ( FIG. 4 ) and helps make the spacers stackable ( FIG. 11 ). The geometry and positions of the spacing cylinders  22  define an injection opening  27  centered in the support disk  21  and that permits the melted resin to be added ( FIG. 12 ). 
     In some embodiments the pin  25  is cylindrical and in other embodiments the pin  25  has a square cross section. When a square cross section is used, the gate button spacer can be more easily oriented (or “clocked”) to position the spacing cylinders  22  in a predetermined position. This in turn fixes the flow path of the melted resin as it is injected between the spacing cylinders (e.g.,  FIG. 12 ). 
       FIG. 2  illustrates an embodiment of a fixture plate broadly designated at  30 . As illustrated, the plate is generally square with rounded corners, but it will be understood that the purpose of the plate is to define the eventual molded fixture. Thus, a different shape fixture plate can be used to produce a different shape of flange and the invention (method or structure) is not limited to the illustrated embodiments. The plate  30  is typically formed of aluminum, although any material that has the necessary structural strength, can be formed into the desired shape, and can withstand molding temperatures, will be appropriate. 
     The plate  30  includes a plurality of corner positioning holes  31  four of which are shown in the illustrated embodiment. The corner positioning holes  31  receive the gate spacer buttons  20  ( FIG. 4 ). 
     The plate  30  includes an incline  28  leading to a lower top surface  33  from the upper top surface  32 . The lower top surface  33  includes a tooling opening  34  illustrated in the center of the lower top surface  33  and in the center of the overall plate  30 . This position is exemplary rather than limiting, however, as is the circular shape of the tooling opening. 
       FIG. 3  is a perspective view similar to  FIG. 2 , but illustrating the bottom face fabric  35  superimposed on the upper top surface  32  and the incline  28  of the fixture plate  30 . In order to leave an opening for the eventual drain, the fabric does not need to cover most of the lower top surface  33  of the plate fixture  30 . Alternatively, if the fabric covers the lower surface initially, the fabric can be trimmed later. 
       FIG. 4  shows the fixture plate  30  in the next progressive step of the method in which the gate button spacers  20  have been inserted through the bottom face fabric  35  and into the corner positioning holes  31 . 
       FIG. 5  is a view identical to  FIG. 4  with the additional illustration of the alignment pins  36 . The alignment pins  36  serve to position the top face fabric  37  in a desired orientation ( FIG. 6 ). 
       FIG. 6  is the next step in the progression of the method.  FIG. 6  accordingly shows the fixture plate  30  in the same orientation as  FIGS. 2-5 , but also illustrates the top face fabric  37 . As will be seen with respect to  FIGS. 12-14 , the top and bottom face fabrics  37 ,  35  are named based upon their eventual position in the finished flange. In the view of  FIG. 6 , the bottom face fabric  35  is positioned underneath and spaced apart from the top face fabric  37  by a distance defined by the spacing cylinders  22  of the gate button spacers  20 . Additionally, the alignment pins help position the top face fabric  37  in the desired superimposed relationship over both the bottom face fabric  35  and the fixture plate  30 . 
       FIG. 7  illustrates the next step in the progression of the method in which the alignment pins  36  have been removed. This, together with the exposed injection openings  27  in the respective gate button spacers  20  provide a path to the volume between the fabric sheets  35 ,  37  for the injected melted plastic ( FIG. 12 ). 
       FIG. 8  illustrates the overlying relationship of the fabric layers  35 ,  37  with the combination being broadly designated at  40 . The portion of the fixture plate that was not covered by fabric (e.g.,  FIGS. 3-7 ) defines a drain plate opening  42  surrounded by a drain perimeter  43 . The gate spacer buttons  20  remain as a part of the illustrated combination. 
       FIG. 9  is a partial perspective view showing the relationship between and among the top face fabric  37 , the bottom face fabric  35 , the gate button spacers  20  and their pin cylinders  25 , the stepped incline  28 , the drain plate opening  42 , and the drain perimeter  43 . 
       FIG. 10  illustrates the same elements as  FIG. 9 , but in cross sectional orientation. 
     In the illustrated embodiment, the invention is shown as two fabric layers with one plastic layer in between. The gate spacer pins  20  are stackable in the manner illustrated in  FIG. 11  so that fabric assemblies can be (optionally) stacked together prior to molding. 
       FIG. 12  is a partial perspective view illustrating in more detail the relationship between the top face fabric  37 , the bottom face fabric  35 , the gate spacer button  20  and the molded plastic  41 . As  FIG. 12  illustrates, the melted plastic resin for the core is injected into the opening  27  in the gate spacer  20  in the direction illustrated by the arrow  44 . This permits the molten plastic to flow between the spacing cylinders  22  and then between the top and bottom face fabrics  37 ,  35 . In general, sufficient molded plastic  41  is added to fill the entire volume between the fabric faces  35 ,  37  as defined by the fixture plate  30 . Nevertheless, it will be understood that this is a step of efficiency and avoids waste rather than an absolute necessity. In some cases, it may be advantageous to inject slightly less resin  41  and trim excess fabric while in other cases it might be advantageous to inject surplus resin and trim it rather than the fabric. 
     The plastic core can be formed of any resin that has the appropriate structural strength (or can be molded to such strength and that does not otherwise adversely affect other materials in the overall structure (tile, mortar, membranes, etc.). Based upon the method, the resin for the core has a melting point lower than the melting point of the spacers  20  so that the spacers  20  maintain their structural integrity as the melted core resin is added. In exemplary embodiments, the core resin is selected from the group consisting of acrylic, nylon, polyethylene, polypropylene, polystyrene, polyvinyl chloride, PTFE, polyester, polycarbonate, polyurethane and acrylonitrile butadiene styrene (“ABS”). 
       FIG. 13  is a perspective view of a completed fixture broadly designated at  45 . In the illustrated embodiment, the fixture  45  includes the top face fabric  37 , the bottom face fabric  35 , and the molded core  41 . A pan  46  is molded to the drain opening  42  and includes a threaded nipple  47 . The pan and nipple are exemplary rather than limiting, however, of the overall structure and method. A comparison of  FIG. 13  with  FIG. 10  illustrates that in most circumstances the pin  25  is removed (typically sheared or clipped) from the finished fixture. 
       FIG. 14  is a slightly different perspective view of these same elements with an enlarged cut out portion more clearly illustrating the top fabric surface  37 , the bottom  35  and the core  41 .  FIG. 14  also shows the interior of the pan  46  and the interior of the threaded nipple  47 . 
     The invention also includes a method of forming a drain fixture. In this aspect, the method includes the steps of positioning two aligned preformed fabrics on top of each other, with connecting elements positioned between the fabrics and bonded to each of the two fabrics in a mold and centering the connected fabrics inside the mold by means of the connecting elements, and injecting a plastic material through openings in the connecting elements to fill the space between the two fabrics with the plastic material. 
     In somewhat more detail, the invention includes the steps of superimposing a first temperature resistant fabric on a rigid temperature resistant fixture plate, positioning a temperature resistant spacer on the first fabric opposite the fixture plate, placing an alignment pin in the spacer on the fabric overlying the fixture plate, superimposing a second fabric over the first fabric and spaced from the first fabric by the spacer while aligning the second fabric on the alignment pin, removing the alignment pins and adding a melted polymer resin into the spacer, and through the spacer and between the fabrics while the fabrics and plate are clamped in a mold. 
     The relevant materials used in the method steps are, of course, those described with respect to  FIGS. 1-14 . 
       FIG. 15  is a cross-sectional view of the gate button spacer  20  in relationship to the top face fabric  37 . In particular,  FIG. 15  illustrates that the preformed fabric  37  covers the inclined edges  24  around the injection opening  27 . This helps provide additional sealing in the mold so that when melted thermoplastic plastic is injected into the mold, the pressure that the plastic exerts will not dislodge the fabric and the fabric will remain sealed against the gate button spacer  20 . 
       FIG. 16  is another cross-sectional view illustrating the gate button spacer  20  in the mold  50 . A feed opening  51  (also referred to as a “sprue”) is positioned in alignment over the injection opening  27 . After injection, the thermoplastic core  41  is positioned in the mold  50  between the bottom face fabric  35  and the top face fabric  37 .  FIG. 16  also illustrates that the pin  25  of the gate button spacer  20  is positioned in an appropriate opening  52  in the lower portion of the mold  50 . 
       FIG. 17  is a partial cross-sectional, partial perspective view of the fabric layers  35 ,  37  and the gates spacer in the context of the injection mold  50 . Most of the elements illustrated in  FIG. 17  are the same as those in  FIG. 16 , with the difference being that  FIG. 17  illustrates that in exemplary embodiments, enough fabric is included to form a fabric lip  53  that extends laterally between the upper and lower portions of the mold  50 . The fabric lip serves to enclose melted resin in the mold within the fabrics  35 ,  37 , but also provides a channel through which gas can escape from the mold (while blocking melted plastic) as the liquid plastic is injected from the sprue  51  into the gate spacer button  20 . 
     Although the invention has been described in terms of the double faced bonding flange for a shower drain, the method and resulting structural advantages are helpful for any plastic part that would normally not adhere well to mortar, but that is convenient in the mortar bond environment. 
     Accordingly,  FIG. 18  illustrates a drain alignment flange broadly designated at  54 . Such an alignment flange is typically used near the drain opening to provide an aligned position for a drain grate.  FIG. 18  shows a current conventional flange body  55  with a plurality of mortar openings  56 . The combination of the flange body  55  and the openings  56  define an overall drain opening  57 . 
       FIG. 19  illustrates a fabric sandwich entirely analogous to that illustrated in  FIGS. 8-10 , but in the form that will mold the drain alignment flange  54 . Accordingly, the bottom face fabric  35  and the top face fabric  37  are both illustrated along with the gate button spacers  20 . 
     As illustrated, the drain alignment flange  54  has a plurality of openings that permit mortar to set within and around the remainder of the structure, because otherwise the mortar tends not to adhere to the flange. Using the invention, however, the fabric present on both faces provides an advantageous improved adhesion to the thin set mortar. As a result, fewer openings are necessary, so that in turn the overall fixture is stronger. 
       FIGS. 20 and 21  are corresponding illustrations of a niche fixture broadly designated at  60 . The niche fixture  60  is exemplary of the type used to provide an indented shelf or similar opening in a tile and mortar surface. The niche  60  can be covered with fabric on both sides in the same manner as the previously illustrated drain and flange fixtures.  FIG. 20  illustrates that the niche fixture  60  includes a plurality of walls  61  and a floor  62 . The illustrated embodiment is typical of niche fixtures that has a width that conveniently fits between normal 16 inch center on center stud construction. In a similar manner the depth of the niche fixture (i.e., the width of the walls) is typical of the depth available between walls in stud based construction. As illustrated, the niche fixture  60  includes a flange  63  to help secure it in position. 
       FIG. 21  illustrates the preformed fabric components for molding that form the “sandwich” broadly designated at  64 . This is again formed of a lower fabric face  37 , a top fabric face  35 , the gate button spacers  20 , and the positioning holes  31 . 
     In the drawings and specification there has been set forth a preferred embodiment of the invention, and although specific terms have been employed, they are used in a generic and descriptive sense only and not for purposes of limitation, the scope of the invention being defined in the claims.