1. Field of the Invention
The present invention relates in general to the field of plastics. More particularly, the present invention relates to a pallet system and a pallet apparatus and a method of pallet manufacturing. Specifically, one preferred embodiment of the present invention relates to blow molding a first pallet piece and then inserting it into another mold to join it to a second blow molded pallet piece.
2. Discussion of the Related Art
Pallets are used for transporting and storing various types of cargo throughout the world. Therefore, it is important for a pallet to be lightweight, compact and strong. Traditionally pallets were made of wood, however, plastic pallets are now being used with increased frequency as they are lightweight, generally stronger, do not absorb moisture, and they can be cleaned and disinfected which is important in particular for the food industry. One disadvantage of plastic pallets is that they tend to break up with continued use over time. Therefore, for these and other various reasons it is important that plastic pallets be reinforced by a variety of means.
The below-referenced U.S. patents disclose embodiments that were at least in-part satisfactory for the purposes for which they were intended. The disclosures of all the below-referenced prior United States patents, in their entireties, are hereby expressly incorporated by reference into the present application for purposes including, but not limited to, indicating the background of the present invention and illustrating the state of the art.
U.S. Pat. No. 5,417,167 discloses a plastic shipping pallet of the type usually manufactured from wood which is made of hollow plastic stringers and deck boards. The stringers and deck boards are made of plastic materials that may be either virgin plastic, recycled plastics or mixes. The stringers and deck boards are hollow but have closed ends to prevent entry of dirt, fluids, insects and vermin. The stringers and deck boards may be made in a blow molding process or using continuous extrusion and molding processes similar to that used in the manufacture of corrugated pipe. Various connection configurations for affixing the deck boards to the stringers are described including fixation by screws as well as interlocking connections between the plastic parts themselves and the use of separate interlocking components which engage the deck board and stringers.
U.S. Pat. No. 5,845,588 discloses a pallet fabricated of a thermoplastic material which is produced by joining together individually fabricated structural components, each of which is individually thermoformed from an extruded plastic parison of a multilayer structure. The structural components include a deck in the form of a continuous sheet with longitudinal and transverse sides, one or more upper runner components fastened by their top side to the bottom of the deck, each of which includes a cross member with downward-facing posts, and one or more lower runner components, each of which includes a cross member with upward-facing posts and which is fastened by the tops of its posts to the bottoms of matching posts on the corresponding upper runner components.
U.S. Pat. No. 5,868,080 discloses a reinforced plastic pallet construction and assembly method wherein multiple reinforcing bars are employed. At least some of the reinforcing bars have an exposed surface at a topside surface, underneath surface or underside surface of the pallet. In addition to functioning as a reinforcing member, the exposed surfaces of the reinforcing bars comprise an anti-skid surface for maintaining positioning of payload on the pallet or facilitating transport of the pallet, e.g., via a forklift or automated transport system. Various techniques for retaining the reinforcing bars within channels formed in the plastic pallet body are described. The reinforcing bars preferably comprise composite structural members of fiberglass reinforced plastic fabricated from a pultrusion process.
U.S. Pat. No. 6,209,464 discloses a pallet that includes a rectangular support deck having a substantially planar upper supporting surface including a plurality of channels formed therein and extending across the pallet. The deck includes support members extending from an underside of the deck that nest in recesses formed in the upper surface of the deck. An alignment portion is formed at a center point along the first edge of the deck and a second alignment portion is formed at a center point of an opposed edge of the deck. The alignment portion includes angled sides for receiving a tapered member of a complementary device.