Patent Application
20130291766
The inventions disclosed here in relate generally to form structures used for manufacturing concrete products. More specifically the mention relates to composite pallets and the method of manufacturing the composite pallets, which are used for forming the end of a concrete product and supporting and transporting the concrete products, such as culverts, pipes, and the like during the manufacture and curing processes.
Concrete pipes are manufactured by casting a concrete mixture or slurry in a mold. The mold is mounted coaxially on a pallet or base for curing. Traditionally, pallets for concrete pipes are made from cast iron, cast steel, fabricated steel, or pressed steel. A steel base, however, is expensive because of the high cost of steel and the high cost of working it. In relatively large plants for making concrete pipe, the steel bases alone require a substantial capital investment.
A composite pallet is disclosed that provides a base that is relatively inexpensive compared to the prior art steel bases, and yet performs as well as the steel bases. The pallet includes an inner structural support with a bottom section and a top section. The top section has an upward facing, load bearing surface that is bonded with a substantially smooth polymer layer. More specifically, the bottom section includes an annular ring that supports a top section comprising an annular ring and a flange that supports the load. The top section is bonded with a polymer to form a smooth surface suitable for curing concrete.
Once formed as described above, the pallet 100 is then inserted into a mold or casting that contains a suitable polymer, to coat the top edge of ring 110 and the flange 105. The polymer coating is more described below. After the polymer has cured, the pallet 100 is removed from the casting leaving the top edge and outside surface of steel, ring 110 flange 105 coated with polymer lavers 112 and 114. Polymer layers 112 and 114 create a substantially smooth surface, which is required for the proper manufacture of quality concrete products.
In an alternative embodiment, the top section 104 of pallet 100 is formed from concrete. Concrete is cast inside a polymer mold with the required shape. The resulting, cured product has a polymer layer surrounding an inner concrete core of the pallet. Again, the outer polymer layer, and specifically top polymer surface 114 has a substantially smooth surface, which is required for the formation of quality concrete products and their release after the curing process.
In the foregoing embodiments, a low-friction polymer is used so the concrete products can be easily removed from the pallets. Examples of low-friction polymers include polymers with Teflon, PTFE, or graphite as a release agent. In such embodiments, an additional flange or protrusions (not shown) can be formed in the top section 104 of pallet 100 to prevent the polymer layer from sliding or shifting. The protrusions provide a void that fills with the polymer and acts as a “hook” to secure the polymer layer to the pallet structure. Alternatively, a frictional polymer is used. A releasing agent is coated on the surface after the polymer has cured and before pallet 100 and 200 are used.
In an alternative embodiment, flanges 206 and 208 are integral with support structure 202, so that the entire pallet 200 is made from high strength concrete. The choice of material for support structure 202 depends on the type of concrete structures, including their size and weight that are being manufactured. Lighter concrete structures can be positioned on a pallet 200 that doesn't include the extra plastic or steel reinforcements in support structure 202.
In manufacturing the pallet assembly 200, flanges 206 and 208 are positioned in the casting mold before the concrete is added, so the concrete support structure 202 and flanges 206 and 208 are secured together once the curing process is complete. Top latitudinal portion 202a of support structure 202 can be prone to cracking, without the addition of flange 206. A chamfer 212 on the end of flange 206 allows concrete to bind on both sides of flange 206 to secure the two together. Flange 208 provides additional structural strength to bottom latitudinal portion 202b of support structure 202, which also can be a structurally, weak point on pallet assembly 200.
The foregoing embodiments advantageously provide a pallet having a substantially smooth surface and finish within a precise tolerance without the need to machine the surface. This way the concrete pipe can be formed on the pallet and the tight tolerances and smooth finish of the pallet will allow the concrete pipe to cure and form without deformation.
While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it should be understood by those of ordinary skill in the art that various changes, substitutions and alterations can be made herein without departing from the scope of the invention as defined by appended claims and their equivalents.
The present invention claims priority to U.S. Provisional Patent Application No. 61/642,136 filed on May 3, 2012, the content of which are hereby incorporated b reference herein.
| Number | Date | Country | |
|---|---|---|---|
| 61642136 | May 2012 | US |
