BACKGROUND
Manholes are included in some sewer lines. Some manholes are formed in molds from materials such as concrete.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a top view of an embodiment of a preliminary mold.
FIG. 2 is a perspective view of an embodiment of a reinforcing structure positioned in the preliminary mold of FIG. 1.
FIG. 3 illustrates the preliminary mold of FIG. 1 being filled with urethane to a first extent with the reinforcing structure of FIG. 2 positioned therein.
FIG. 4 illustrates the preliminary mold of FIG. 1 being filled with urethane to a second extent with the reinforcing structure of FIG. 2 positioned therein.
FIG. 5 is a top view of an embodiment of a manhole mold produced removed from a preliminary mold.
FIG. 6 is a perspective view of an embodiment of a manhole mold.
FIG. 7 is a cross-sectional view of the manhole mold of FIG. 6.
FIG. 8 is a perspective view of an alternative embodiment of a manhole mold.
DESCRIPTION
Process embodiments are described herein for creating polyurethane molds that allow for the production of manhole bases, e.g., monolithic manhole bases with distinctive channel geometries. In one embodiment, the process includes forming a first, preliminary mold, positioning a reinforcing structure with respect to the preliminary mold and forming a second, reinforced mold with the reinforcing structure positioned therein. The second mold, in one embodiment, can be formed of polyurethane with an embedded plate (e.g., formed of steel), lifting eyes and hole former connectors. In some embodiments, the first and second molds are made of another material (e.g., plastic, rubber, polymer).
In order to form a mold that allows for production of monolithic manhole bases, a first or preliminary mold is made (e.g., milled such as by using a robot or CNC machine) to a desired geometry, which can include one or more channels. In some embodiments the mold is made out of a foam block (e.g., formed of polyisocyanurate). Next, the first or “preliminary” mold is sanded and prepared for coating.
The first mold is then coated (e.g., with a polyurethane coating or other coating which may be applied by spraying, rolling, brushing, etc.) to allow for the release of the polyurethane urethane. FIG. 1 shows an example first mold that has been formed with an example geometry and coated as discussed above.
A reinforcing structure that includes a steel plate (e.g., having a thickness of approximately 5/16″) can be fabricated that will be embedded into the urethane that forms the second mold. Elements can be built up off of the steel plate to follow the desired geometry in order to maintain a urethane thickness of approximately ¾″ along the desired geometry. Threaded couplers can be welded to the flat plate to be used for removing a final mode from the finished concrete structures.
As shown in FIG. 2, the steel plate can be leveled within the first mold such that, when urethane is poured into the first mold, as shown in FIGS. 3 and 4, connections are embedded in the second mold for hole former installation.
The finished polyurethane mold is removed from the preliminary mold. The final mold can then be cured as shown in FIG. 5. The second mold includes the steel plate and lifting eye embedded into urethane. Connections for hole formers are also optionally present.
A concrete manhole base can then be formed using the second mold, for example by placing the second mold within another structure and pouring concrete into the structure with the second mold in place. In some embodiments, hole formers are attached to the embedded connection described above before pouring the concrete.
Turning to FIGS. 6 and 7, an embodiment of a manhole mold 100 is illustrated in more detail. The mold 100 optionally includes a urethane body 200 and a reinforcing structure 300. The urethane body 200 optionally includes a generally disc-shaped portion 210. The urethane body 200 optionally includes a semi-cylindrical channel 230 extending from one side of the body 200 to an opposing side thereof. The urethane body 200 optionally includes a channel 250 extending arcuately from the channel 230 to another side of the body 200. The urethane body 200 optionally includes flanges 220 at outer ends of the channels 230, 250. Referring to FIG. 7, the reinforcing structure 300 optionally includes a plate 310 (e.g., metal plate, steel plate, circular plate, circular steel plate, circular metal plate, reinforcing disc, etc.). The plate 310 optionally has one or more lifting attachments (e.g., lifting eyes, embedded lifting eyes, embedded lifting eyes having attachment screw threads, etc.) mounted thereto and extending to an upper end of the urethane body 200. The plate 310 optionally has one or more hole mount supports 330 extending downward therefrom at least partially into each end of the channel 230 and/or the channel 250. In some embodiments the mount supports 330 additionally or alternatively extend at least partially into the flanges 220. The mount supports 330 optionally support one or more hole former connections 335 (e.g., threaded connection, etc.) for attaching one or more hole formers H (e.g., by extending a bolt or other fastener through an opening OH in the hole former H and attaching the fastener to the connection 335). The hole formers H may be made of rubber, urethane, metal or other material.
Referring to FIG. 8, an alternative embodiment of a manhole mold 100′ is illustrated without flanges 220. A modified reinforcing structure of manhole mold 100 optionally includes a connection 335′ for attaching a removable flange F which may be made of urethane, rubber, metal or other material and may include one or more embedded reinforcing structures (e.g., metal plates, etc.). Hole former H and flange F may be attached to connection 335′ by extending a bolt or other fastener through opening OH in the hole former H and through opening OF in the removable flange F and connecting the fastener to the connection 335′.
Although various embodiments have been described above, the details and features of the disclosed embodiments are not intended to be limiting, as many variations and modifications will be readily apparent to those of skill in the art. Accordingly, the scope of the present disclosure is intended to be interpreted broadly and to include all variations and modifications within the scope and spirit of the appended claims and their equivalents. For example, any feature described for one embodiment may be used in any other embodiment.
Patent Application
20220105663
