Sumitomo Electric Industries, Limited

Sumitomo (Sei) Steel Wire Corp.

Nippon Steel Corporation

Daiken Corporation

Katsuhito Oshima

Masato Yamada

Shuichi Tanaka

Jun Sugawara

Daisuke Hirakami

Makoto Okonogi

Shingo Nakajima

Yoshiyuki Matsubara

Yoshihiko Touda

Kiminori Matsushita

Kazuki Sakamoto

Koji Nagaoka

Yasushi Sugio

Shuhei Maeda

Toshihiko Niki

Motonobu Nishino

Takashi Ichiki

Tomoya Maekawa

Kazuhiro Hirata

Takahide Saiki

Provided is a strand board with improved strength and water resistance. Reduction in productivity is prevented and characteristics of the strand board can be varied as desired while achieving certain strength and water resistance of the strand board. A strand board B is formed by stacking and laminating five strand layerseach formed by a large number of strands. The strand board B has substantially constant density distribution in the lamination direction of the strand layers. Three of the five strand layersof the strand board B are high-density strand layershaving a higher density than the other strand layers, and the other strand layersare low-density strand layers

Wood laminate material and method for manufacturing same

A concrete structure includes a first concrete member, a second concrete member, a sheath that is disposed in a through hole extending from the first concrete member to the second concrete member, a tension part that is inserted over the entire length of the sheath and that is subjected to a tensile force, a fixing tool that fixes the tension part to the first concrete member or the second concrete member, and an anticorrosion part that covers the fixing tool. The tension part includes a stranded wire part and a first cover that covers an outer periphery of the stranded wire part. A space between the sheath and the tension part is not filled with a grout material.

Concrete structure

This method for manufacturing a high-density strand board enables high-density strand boards to be formed by using about the same press pressure as press pressures required to form strand boards with common densities, so that the high-density strand boards can be produced without using special facilities and equipment. A pretreatment process Pis performed on strandsbefore pressing. The pretreatment process Pis comprised of a first treatment process Pand a subsequent second treatment process P. At least one of beating, high-frequency treatment, high-temperature high-pressure treatment, high-water pressure treatment, repeated deaeration and dehydration treatment, and chemical treatment is performed in the first treatment process P, and roll pressing or flat press pressing is performed in the second treatment process P. A strand board B with a density of 750 to 950 kg/mis formed by using a press pressure of 4 N/mmor less.

Method for manufacturing high-density wood laminate material

This invention provides a high-strength PC steel wire having a chemical composition containing, in mass %, C: 0.90 to 1.10%, Si: 0.80 to 1.50%, Mn: 0.30 to 0.70%, P: 0.030% or less, S: 0.030% or less, Al: 0.010 to 0.070%, N: 0.0010 to 0.010%, Cr: 0 to 0.50%, V: 0 to 0.10%, B: 0 to 0.005%, Ni: 0 to 1.0%, Cu: 0 to 0.50%, and the balance: Fe and impurities. A ratio between the Vickers hardness (Hv) at a location (surface layer) that is 0.1D [D: diameter of steel wire] from the surface of the steel wire and the Vickers hardness (Hv) of a region on the inner side relative to the surface layer satisfies the formula [1.10&#x3c;Hv/Hv&#x2264;1.15]. An average carbon concentration in a region from the surface to a depth of 10 &#x3bc;m (outermost layer region) of the steel wire is 0.8 times or less a carbon concentration of the steel wire. The steel micro-structure in the region on the inner side relative to the outermost layer region contains, in area %, a pearlite structure: 95% or more. The tensile strength of the steel wire is 2000 to 2400 MPa. The method of producing this high-strength PC steel wire is simple, and the high-strength PC steel wire is excellent in delayed fracture resistance characteristics.

High-strength PC steel wire

This invention provides a high-strength PC steel wire having a chemical composition containing, in mass %, C: 0.90 to 1.10%, Si: 0.80 to 1.50%, Mn: 0.30 to 0.70%, P: 0.030% or less, S: 0.030% or less, Al: 0.010 to 0.070%, N: 0.0010 to 0.010%, Cr: 0 to 0.50%, V: 0 to 0.10%, B: 0 to 0.005%, Ni: 0 to 1.0%, Cu: 0 to 0.50%, and the balance: Fe and impurities. A ratio between the Vickers hardness (Hv) at a location (surface layer) that is 0.1D [D: diameter of steel wire] from the surface of the steel wire and the Vickers hardness (Hv) of a region on the inner side relative to the surface layer satisfies the formula [1.10&#x3c;Hv/Hv&#x2264;1.15]. The steel micro-structure in the region from the surface of the steel wire to 0.01D (outermost layer region) consists of, in area %, a pearlite structure: less than 80%, and the balance: a ferrite structure and/or a bainitic structure. The steel micro-structure in the region on the inner side relative to the outermost layer region contains, in area %, a pearlite structure: 95% or more. The tensile strength of the steel wire is 2000 to 2400 MPa. The method of producing this high-strength PC steel wire is simple, and the high-strength PC steel wire is excellent in delayed fracture resistance characteristics.

A pregrouted PC steel material () includes a 19-wire-twisted PC strand (), a pregrouted layer () disposed on an outer periphery of the PC strand (), and a sheath () configured to cover an outer periphery of the pregrouted layer (). A filling resin () is filled between steel wires (side wires) (). Since the filling resin () does not exude to the pregrouted layer () before tensioning of the PC strand (), an operation of tensioning the PC strand () is not hindered by curing of the pregrouted layer (). In contrast, since the gap between the steel wires is reduced when the PC strand () is tensioned, the filling resin () flows out (exudes) from between the steel wires to the pregrouted layer () to cure the pregrouted layer () only after the reduction.

Pregrouted PC steel material and curing method for pregrouted layer therein

Provided is a pregrouted PC steel material comprising a PC steel stranded wire composed of a plurality of steel wires, a pregrout layer disposed on the outer periphery of the PC steel stranded wire so as to accommodate the PC steel stranded wire, a sheath covering the outer periphery of the pregrout layer, and a capsule including a pregrout-hardening agent and a film with which the agent is covered, the capsule being interposed among the steel wires constituting the PC steel stranded wire. The capsule has a strength such that the capsule is not broken before tensioning the PC steel stranded wire but is broken by a tensile force during the tensioning. Also provided is a method for hardening the pregrout layer.

Pregrouted PC steel material and method for hardening pregrout layer thereof

There is provided a strand that can reduce the trouble in constructing an object to which compression force is applied by the strand and that can keep the construction cost down. A strandis placed in a bore hole provided in a wall or roof surface, and is gripped by a wedge in a tensioned state so as to apply a tensile force to the wall or roof surface. The strandof the present invention includes a pipe-shaped member (corrugated tube) made of metal, and a plurality of metal wiresarranged on the outer periphery of the corrugated tubeThe metal wiresare arranged to surround the corrugated tubeon the cross section of the corrugated tube

Growing community of inventors

Itami, Japan

Katsuhito Oshima