Emerald Group Publishing Limited
Copyright © 2000, MCB UP Limited
Keywords: Robots, Fabrication Applicant: Paul A. CraftonPatent number: US5167468Publication date: 1 December 1992Title: System for the robotic fabrication of pipelines and tunnels along unlimited three-dimensional curvilinear paths
The invention is a system for the robotic fabrication of a set of parallel pipelines or tunnels along a curvilinear path without limitation as to distance, direction and depth. A large diameter bore is made by a boring unit as the boring unit moves tangentially along the path through the earth. Prefabricated segments of the pipeline body or tunnel body are then installed by the system at a plurality of locations in the bore, such that their axes are instantaneously parallel to each other and to the large diameter bore, as extensions of the duct body already installed. The annular space between the extensions and the large diameter bore is then occasionally filled along the ducts with a composite material thereby supporting the several smaller diameter structurally independent permanent ducts in the large diameter bore. The prefabricated duct segments function as the structural body of the ducts. Along those segments of the path not through solid material, the prefabricated segments, as successively installed, structurally function as a cantilever bridge through the non-solid region of the path. When the system is operating in a solid region of the subterrain, the earth is initially cut away by the boring unit in a large diameter bore as the boring unit moves ahead. Special conveyor units convey to the boring unit the prefabricated liners of appropriate material (for example, metal, composite), and as the ducts are formed the special conveyor units convey the prefabricated structural segments in the ducts to the location immediately aft of the boring unit and there install them. The prefabricated segments as successively installed thus function in the aggregate as the structural body of each duct. The installation of the prefabricated segments is a continual procedure as the ducts are extended. The interior surface of the duct body is a helical thread or alternatively a wrap-around cylindrical spur rack. The conveyor units convey surplus earth and navigational information from the boring unit to the mouth of the ducts. They also convey the prefabricated structural segments to be installed, material for the optional filling-in of the annular space between the permanent ducts and the initially cut large-diameter earthen bore, navigational and other control commands, and energy from the mouth of the ducts to the boring unit. The conveyor units move one-way in a pair of ducts; the pair is joined at the boring unit by a U-tube and correspondingly by a fixed U-tube at the beginning of the path. Each pair of ducts and its two U-tubes thereby constitute a closed circuit for the rapid movement of the conveyor units. Propulsion of the boring unit is provided by hollow traction units in at least three of the parallel ducts. Each traction unit has wheels that are gears that mesh positively with the helical interior surface of the ducts, thus providing positive traction regardless of the instantaneous direction of the ducts. The differential motion of the traction units causes a change in the directional aspect of the boring unit, and thus the boring unit is omnidirectionally steerable. The wheels of each traction unit are both at the top of the unit and at the bottom of the unit. Each conveyor unit also has gear wheels which mesh with the interior surface of the ducts and the U-tubes. Similarly to the traction units, the gear wheels of the conveyor units are on the top of the unit and also on the bottom of the unit. The conveyor units are thus able to move in the duct regardless of its instantaneous direction. The interior surface of the hollow traction units is similar to the interior surface of the ducts in order to enable the conveyor units to pass through them.