This disclosure relates generally to corrugated pipe, and more particularly to corrugated pipe with a reinforcing stiffener. The corrugated pipe may include an axially extended bore defined by a corrugated outer wall having axially adjacent, outwardly-extending corrugation crests, separated by corrugation valleys. In some embodiments, a stiffener may be positioned within the corrugation valleys. In other embodiments, a stiffener may be positioned within the corrugation crests.

This disclosure relates generally to corrugated pipe, and more particularly to corrugated pipe with a reinforcing stiffener. The corrugated pipe may include an axially extended bore defined by a corrugated outer wall having axially adjacent, outwardly-extending corrugation crests, separated by corrugation valleys. In some embodiments, a stiffener may be positioned within the corrugation valleys. In other embodiments, a stiffener may be positioned within the corrugation crests.

A head is disclosed for use with a continuous manufacturing system. The head may have a housing configured to receive a matrix and a continuous fiber, and a diverter located at an end of the housing. The diverter may be configured to divert radially outward a matrix-coated fiber. The head may also include a cutoff having an edge configured to press the matrix-coated fiber against the diverter.

A method is disclosed for continuously manufacturing a composite hollow structure. The method may include continuously coating fibers with a matrix, and revolving matrix-coated fibers about a non-fiber axis. The method may also include diverting the matrix-coated fibers radially outward away from the non-fiber axis, and curing the matrix-coated fibers.

This disclosure relates generally to corrugated pipe, and more particularly to corrugated pipe with an outer wrap. In one embodiment, a pipe includes an axially extended bore defined by a corrugated outer wall having axially adjacent, outwardly-extending corrugation crests, separated by corrugation valleys. The pipe also includes an outer wrap applied to the outer wall. The outer wrap may include fibers and plastic. The outer wrap may span the corrugation crests producing a smooth outer surface.

A concrete dowel placement system and methods for making the same. The system allows for accurate and easy substantially-parallel or parallel placement of slip dowels within sections of concrete so that adjacent sections of concrete may be allowed to undergo thermal expansion and contraction while remaining in a common plane without cracking or faulting. The system includes a coupler and a sheath. The sheath is configured to be slidably extensible over the coupler and may be held to the coupler by friction. An outer surface of the sheath may be textured. Additionally, a method of constructing the concrete dowel placement system includes extruding material to form two tubes of different sizes. The tubes are then attached to each other, then material is extruded or injection molded to form a sheath. Alternatively, construction may include extruding material to form a tube, then removing some of the material from the tube in order to form a coupler.

A die for a polymer mixing machine includes first and second opposing surfaces. Each defines first cylindrical portions and second V-shaped portions interspaced between each first portion. The first and second opposing surfaces produce a ply with first portions thicker than second portions and throated portions therebetween.

A sizer for cooling an extrudate includes a core and a housing. The core includes an extrusion channel which accommodates the extrudate, a core cooling channel, and a core vacuum channel in fluid communication with said extrusion channel. The housing includes a housing cooling channel, a housing vacuum channel, a cooling intake, and a cooling exhaust. The housing cooling and vacuum channels having curved segments. The cooling intake and exhaust being in fluid communication with said housing cooling channel.

Embodiments described herein relate to apparatus for extruding a material. The apparatus comprises an extrusion die arranged to receive material to be extruded from a first direction and from a second direction. The extrusion die comprises an orifice from which material is extruded in a third direction. The first, second and third directions are not all in the same plane. None of the first, second and third directions is parallel to any other of those directions.

A curable sheath fluid and a core fluid are simultaneously introduced from a hydrodynamic nozzle to form a co-flowing extrusion, depositing at least a portion of the co-flowing extrusion on a material bed, and causing relative motion between the hydrodynamic nozzle and the material bed to form an extruded shape. The method comprises curing part or all of the external curable fluid. The method may introduce co-flowing extrusion to pressure to remove the internal core fluid from the external curable fluid, and may receive the core fluid into the fluid drain system. The extruded shapes may form a tube or plurality of tubes in a bundle or porous substrate. The ability to form concentric tubes and complex shapes provides a means forming high strength materials controlled release materials, and self-repair materials.