CROSS-REFERENCE TO RELATED APPLICATIONS
- STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH
- BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to doors made from extruded plastic. More specifically, it relates to bi-fold or half doors made from rigid plastic, such as polyvinyl chloride (PVC). The side stiles, horizontal rails, and slatted vanes that make up the door are individual pieces that are generally hollow, except for reinforcing interior cross-members. The individual pieces are formed by extruding plastic through a die. The invention contemplates that the door be assembled in a manner similar to that used for a conventional wooden bi-fold door.
2. Description of the Related Art
Traditionally, bi-fold or half doors have been made of wood, but the expense of wood has caused the industry to search for other suitable materials. Recently, manufacturers have turned to fabricating such doors from synthetic resins by injection molding, as described in U.S. Pat. No. 3,985,175. However, the injection molding process is limited in its application. Typically, the injection molding process involves making two rectangular hollow pans and joining the pans together by the edges to form a hollow door. U.S. Pat. No. 3,985,175 describes a particular type of construction wherein a front face is made of injection molded plastic and has reinforcing members on the back side but no back face. Such a construction, while serving to maintain rigidity, provides a door having only one good side. Such a door is unsuited for general applications in the home or office.
- SUMMARY OF THE INVENTION
One of the main problems with full length doors made from injection molded plastic is their lack of rigidity. Therefore, there is a need in the industry for a plastic door that has sufficient rigidity and is aesthetically pleasing from both sides.
BRIEF DESCRIPTION OF THE DRAWINGS
Full length bi-fold and half doors may be constructed from rigid plastic, such as PVC, that is extruded to form the various pieces used to construct the door. Rigid plastic has the advantage of being lighter in weight than wood because the interior of the rails, stiles, and vanes are basically hollow except for the reinforcing cross-members that are formed during the extruding process. This type of construction offers several advantages over wood. A rigid plastic door is much more fire resistant than wood, and it does not warp from humidity. Additionally, the finished product manufactured from plastic does not require painting and is a solid color throughout so scratches from ordinary use are not readily visible. Finally, rigid plastic is easier to clean, can be produced with a glossy finish, and is generally more durable than wood.
FIG. 1 is a schematic representation of a bi-fold door in accordance with the present invention.
FIG.2 is a schematic representation of a half door in accordance with the present invention.
FIG.3 is a cross-section view of a rail used for the top, middle and bottom horizontal support members.
FIG. 4 is a cross-section of the side support members or stiles.
DETAILED DESCRIPTION OF INVENTION
FIG. 5 is a cross-section of a slatted vane that fits between the side stiles.
The invention is directed to a full length bi-fold and half door constructed from synthetic resinous, rigid plastic that is extruded to form the various pieces used to make the door. Rigid plastic has the advantage of being lighter in weight than wood because the interior of the rails, stiles, and vanes are basically hollow except for the reinforcing cross-members that are formed during the extruding process. This type of construction offers several advantages over wood. A rigid plastic door is much more fire resistant than wood, and it does not warp from humidity. Additionally, the finished product manufactured from plastic does not require painting and is a solid color throughout so scratches from ordinary use are not readily visible. Finally, plastic is easier to clean, can be produced with a glossy finish, and is generally more durable than wood.
FIG. 1 and FIG. 2 show the preferred embodiment of the invention wherein extruded rigid plastic bi-fold and half doors have two side stiles and a top and bottom rail forming a generally rectangular configuration and have horizontal vanes covering the interior of the door. The stiles have mating cutouts formed along their interior edge for receiving the vanes and holding the vanes in a permanently fixed position relative to the stiles and rails when the stiles and rails are assembled into a rectangular configuration.
The preferred plastic material is PVC because of its strength, durability, and ease of extruding. However, other suitable materials, such as polyethylene and polypropylene could be used. The preferred formulation of PVC is about 65% to 75% PVC, about 12% to 18% calcium carbonate, about 8% to 12% stabilizer, and about 3% to 7% titanium dioxide. The especially preferred formulation is about 70% PVC, about 15% calcium carbonate, about 10% stabilizer, and about 5% titanium dioxide. The preferred ingredients include a tin stabilizer. Other ingredients include a paraffin wax lubricant, such as XL165, a process aid, such as methyl methacrylate which is commercially available as K-120N from Rohm & Haas, and an impact modifier, such as modified acrylic available as D-200 from Elf-Autochem. Titanium dioxide should be added in an amount sufficient to impart the desired shade of white, and pigment may be added to achieve other color variations.
The basis extrusion process is old and well known to a person skilled in the art. Various dies may be used to extrude the individual pieces with a variety of profiles, but FIG. 3 shows the preferred cross-section view of a rail used for the top and bottom of the horizontal rail section. Preferably, the door also has a middle rail of the same or similar configuration as the top and bottom rails. This middle rail provides extra stability for the door and also provides a means for attaching an opening mechanism, such a knob.
FIG. 4 shows the preferred construction of the side stiles. This construction also allows for hardware, such as hinges, to be securely attached. Of, course, other designs are acceptable so long as they provide the needed strength and rigidity.
FIG. 5 shows the preferred construction of the slatted vanes that cover the interior of the door. These vanes are basically hollow, but preferably have one or more cross-members for support. The vanes are designed to fit into the side stiles in a permanently fixed position when the door is fully assembled. The slatted vanes allow light and air to pass through the door yet provide a high degree of privacy. Because the vanes are somewhat flexible, an individual vane may be removed from the door and replaced with a new vane, if the need arises, without disassembling the door.
The stiles and rails may be fastened together by any suitable means, such as glue or screws. The preferred method of construction is a screw fastener. For aesthetic purposes, the screws should be countersunk so that the heads can be covered with a plug to make the assembly virtually invisible.
The hinges associated with mounting the bi-fold or two piece door could be standard metal hinges that attach to the stiles with screws. In order to securely fasten hardware to the doors, it is preferred that small plastic anchors be inserted into the stiles where the screws for the hinges and knob attach. These anchors will provide more support for the screws than the relatively thin wall of the stiles and will help prevent the screws from stripping during the final assembly.
This invention is directed mainly toward bi-fold and half doors, rather than full doors, because the vanes in a bi-fold and half door are relatively short and will maintain their structural integrity if pressure is applied on the vanes when the door is in use. However, this invention could be made to work well on a full size door by using a center stile that would permit the use of short vanes on both sides of the center stile. Without a center stile on a full size door, the rigid plastic vanes covering an expanse of about two feet would tend to be too flexible and would probably not be suitable. Alternatively, if additional supporting cross-members were added to the interior of the vanes or if the vanes were made thicker, they could be made to work on a larger expanse. The obvious disadvantage of this configuration would be the expense of the extra material needed to make the vanes and the additional weight of the door.
As is apparent from the foregoing description, there are various modes of carrying out the invention. It is to be fully understood that all of the foregoing is intended to be merely illustrative and is not to be construed or interpreted as being restrictive or otherwise limiting of the present invention.