Hollow, composite-material rebar structure, associated components, and fabrication apparatus and methodology

A method of making an elongate, composite-material, hollow rebar structure comprising

• forming an elongate, composite-material, hollow core,
• in association with said forming, preparing along the core's length an elongate, composite-material, core-circumsurrounding, hollow sleeve having inner and outer surfaces,
• in association with said preparing, creating, unitarily with the sleeve, and in a manner distributed along the length of the sleeve's outer surface, an external-purchase-enhancing structure possessing radial-dimensionality, and
• bonding the inner surface of the sleeve to the outer surface of the core.

A method of making an elongate, composite, hollow rebar structure comprising

• forming, in a pultrusion die, an elongate, composite-material, fibre-reinforced, curable-plastic-material-including, hollow core,
• applying heat within the pultrusion die to create, for the core's included plastic material as it emerges from the die, an outer-surface plastic condition which is less than 100% cured,
• in association with, and downstream from, said forming, preparing, in a rotational, continuous-transfer-molding die, on the less-than-100%-cured, outer-surface plastic of the emerging core and along its length, an elongate, hollow, composite-material, fibre-reinforced, curable-plastic-material-including, core-circumsurrounding sleeve,
• in relation to said preparing, and within the transfer-molding die, creating, unitarily with the sleeve, and in a manner distributed along the length of the sleeve's outer surface, an external-purchase-enhancing structure possessing radial-dimensionality, and
• within the transfer-molding die, applying heat to effect between the plastic material in the core and that in the sleeve a single-cure, plastic-material bond.

A method of making an elongate, composite-material, hollow rebar structure comprising

• forming, in a pultrusion die, an elongate, composite-material, fibre-reinforced, curable-plastic-material-including, hollow core,
• applying heat within the pultrusion die to create, for the core's included plastic material as it emerges from the die, an outer-surface plastic condition which is less than 100% cured,
• in association with, and downstream from, said forming, preparing, in a rotational, continuous transfer-molding die, on the less-than-100%-cured, outer-surface plastic of the emerging core and along its length, an elongate, hollow, composite-material, fibre-reinforced, curable-plastic-material-including, core-circumsurrounding sleeve,
• in relation to said preparing, and within the transfer-molding die, creating, unitarily with the sleeve, and in a manner distributed along the length of the sleeve's outer surface, an external-purchase-enhancing structure possessing radial-dimensionality, and
• within the transfer-molding die, applying heat to effect between the plastic material in the core and that in the sleeve a reverse-temperature-gradient-cure, plastic-material bond.

A method of making an elongate, composite-material, hollow rebar structure comprising

• forming, in a pultrusion die, an elongate, composite-material, fibre-reinforced, curable-plastic-material-including, hollow core,
• applying heat within the pultrusion die to create, for the core's included plastic material as it emerges from the die, an outer-surface plastic condition which is less than 100% cured,
• in association with, and downstream from, said forming, preparing, in a rotational, continuous-transfer-molding die, on the less-than-100%-cured outer-surface plastic of the emerging core and along its length, an elongate, hollow, composite, fibre-reinforced, curable-plastic-material-including, core-circumsurrounding sleeve,
• in relation to said preparing, and within the transfer-molding die, creating, unitarily with the sleeve, and in a manner distributed along the length of the sleeve's outer surface, an external-purchase-enhancing structure possessing radial-dimensionality, and
• within the transfer-molding die, applying heat to effect between the plastic material in the core and that in the sleeve both a single-cure, and a reverse-temperature-gradient-cure, plastic-material bond.

Apparatus for making an elongate, composite-material, hollow rebar structure, said apparatus having a long, rebar-formation axis, and upstream and downstream regions disposed at spaced locations on and along said axis, said apparatus, progressing therein, and therealong, from said upstream region toward said downstream region, comprising

• an elongate, hollow mandrel having a long axis which is substantially coincident with said rebar-formation axis, extending from adjacent said upstream region toward adjacent said downstream region,
• an elongate, hollow pultrusion die disposed operatively adjacent said upper region, having a long axis which is substantially coincident with said rebar-formation axis, circumsurrounding said mandrel, and operable to form an elongate, composite-material, hollow core in the region disposed between itself and said mandrel, and
• an elongate, hollow, continuous-transfer-molding die disposed downstream, and spaced, from said pultrusion die, having a long axis about which it is rotatable and which is substantially coincident with said rebar-formation axis, said transfer-molding die being operable to form, along the length of a core which has been formed upstream by said pultrusion die, (a) an elongate, composite-material, core-circumsurrounding, hollow sleeve having an outer surface, and (b), unitarily with the sleeve, and in a manner distributed along the length of the sleeve's outer surface, an external-purchase-enhancing structure possessing radial-dimensionality.