A coupler for mounting to externally threaded reinforcing bar for use in concrete construction, the comprising a body having a portion with an internal thread for engagement with the thread of the reinforcing bar, wherein the thread form at the inner end portion of the internal thread includes on one of its flanks an enlargement of progressively increasing extension, the enlargement extending towards an opposing flank of the thread to provide an increasing friction fit with the thread of the bar. Various embodiments provide the enlargement being only on a part of the face of the flank whereby the remainder of the face of the flank forms, in conjunction with the adjacent flank of the bar thread during tightening, a void for receiving material displaced during tightening.

A system includes a coupler-journal including a central body portion and a coupling portion. The coupler-journal is configured for attaching with a first torque tube and a second torque tube. A bearing is configured for placement around the central body portion.

An apparatus and method of manufacturing silicon seed rod in which two silicon seeds are joined into one long silicon seed rod by mechanical coupling. A mechanical seed coupler is a body in having an outer wall, an upper surface with an upper aperture, a lower surface with a lower aperture, and an inner wall surrounding an inner space. The mechanical seed couple can be of a shape including a cylinder shape, an elliptical tube shape, a rectangular tube shape and a square tube shape. Furthermore the mechanical seed coupler can be of unitary construction, made from one solid piece of material, or it can be composed of subparts.

An insert-and-twist building block structure includes a connection bar and a connection terminal unit. The connection bar has an end from which a combination projection section extends and has a conic shape. The combination projection section has an external circumferential surface formed with a bead ring including multiple raised beads intermittently arranged in a ring configuration. The connection terminal unit includes a connection terminal having an end inward recessed to form a combination cavity in a conic shape. The combination cavity has an internal circumferential surface formed with a groove ring including multiple recessed grooves intermittently arranged in a ring configuration. The recessed grooves each a middle portion forming a deep trough section and two ends each forming a shallow trough section, and a depth is decreased from the deep trough section toward the shallow trough sections.

An assemblable structural column joint connection using fiber-reinforced concrete filled round double steel tubes, including an outer high-strength round steel tube, an inner high-strength round steel tube and a round separation plate. The wedge-shaped teeth are provided at two sides of the outer and inner high-strength steel tubes, and wedge-shaped teeth spaced are uniformly distributed along circumferences of the inner and outer high-strength round steel tubes. The round separation plate includes a round plate provided with a central through-hole, and vertical separation walls are provided with on upper and lower surfaces of the round plate. The vertical separation walls are provided with wedge-shaped sliding grooves matching the wedge-shaped teeth. The inner and outer high-strength round steel tubes are fixedly connected to the round separation plate by matching the wedge-shaped teeth with the wedge-shaped sliding grooves.

An insert-and-twist building block structure includes a connection bar and a connection terminal unit. The connection bar has an end from which a combination projection section extends and has a conic shape. The combination projection section has an external circumferential surface formed with a bead ring including multiple raised beads intermittently arranged in a ring configuration. The connection terminal unit includes a connection terminal having an end inward recessed to form a combination cavity in a conic shape. The combination cavity has an internal circumferential surface formed with a groove ring including multiple recessed grooves intermittently arranged in a ring configuration. The recessed grooves each a middle portion forming a deep trough section and two ends each forming a shallow trough section, and a depth is decreased from the deep trough section toward the shallow trough sections.

A system includes a coupler-journal including a central body portion and a coupling portion. The coupler-journal is configured for attaching with a first torque tube and a second torque tube. A bearing is configured for placement around the central body portion.

An assemblable structural column joint connection using fiber-reinforced concrete filled round double steel tubes, including an outer high-strength round steel tube, an inner high-strength round steel tube and a round separation plate. The wedge-shaped teeth are provided at two sides of the outer and inner high-strength steel tubes, and wedge-shaped teeth spaced are uniformly distributed along circumferences of the inner and outer high-strength round steel tubes. The round separation plate includes a round plate provided with a central through-hole, and vertical separation walls are provided with on upper and lower surfaces of the round plate. The vertical separation walls are provided with wedge-shaped sliding grooves matching the wedge-shaped teeth. The inner and outer high-strength round steel tubes are fixedly connected to the round separation plate by matching the wedge-shaped teeth with the wedge-shaped sliding grooves.

A rebar movement-prevention-type one-touch coupler is configured to allow rebars to be fixed without a movement of the rebars after performing a one-touch insertion. A fixation of the rebars is completed by performing an additional tightening operation to housing units into which the rebars are inserted. The coupler increases both the fixation stability of the rebar and the safety of a structure employing the rebar.

A coupler for mounting to externally threaded reinforcing bar for use in concrete construction, the comprising a body having a portion with an internal thread for engagement with the thread of the reinforcing bar, wherein the thread form at the inner end portion of the internal thread includes on one of its flanks an enlargement of progressively increasing extension, the enlargement extending towards an opposing flank of the thread to provide an increasing friction fit with the thread of the bar. Various embodiments provide the enlargement being only on a part of the face of the flank whereby the remainder of the face of the flank forms, in conjunction with the adjacent flank of the bar thread during tightening, a void for receiving material displaced during tightening.