Abstract: A gear spindle (3) obtained by inclining the axis of a spindle inner tube (10) provided at one end with an external cog inner tube gear section (40) at 0.6 degrees to 1.6 degrees with respect to the axis of a spindle outer tube (20) provided with an internal cog outer tube gear section (50) that meshes the inner tube gear section (40). On the teeth of the inner tube gear section (40) having a face width (B), a crowning of radius (Cr) is provided so that the center in the face width direction is expanded and both tooth ends are thin. The face width (B) and the crowning radius (Cr) are set within an area that is enclosed by graphs of (Cr)=1200 [mm], (Cr)=4000 [mm], (B)=0.0272×(Cr)+28 [mm], (B)=59.04×exp (0.0005×(Cr)) [mm], and (B)=32×(Cr)0.274 [mm].

Abstract: Provided is a gear spindle that is optimal for reducing diameter, that is capable of maintaining adequate strength and a high torque transmission capacity, and that maintains the sealing properties of an oil seal and prevents said oil seal from being damaged during operation at a high rotational speed.

Abstract: In order to provide a manufacturing device and a manufacturing method for a hot-rolled steel strip, which are capable of obtaining the desired quality of material by rapid uniform cooling immediately after rolling, and improving yield by early sheet tension and sheet shape measurements, a manufacturing device for a hot-rolled steel strip is provided with a finishing rolling mill line (11), a first cooling unit (13) installed just behind the exit side of the finishing rolling mill line, and a pinch roll (14) which is installed on the exit side of the first cooling unit and in contact with both the upper and lower surfaces of a strip (S), at least a wiping roll (15) located on the upper side of the strip (S) is disposed between the first cooling unit and the pinch roll, and a tension/shape measuring unit (16) for measuring the tension and shape of the strip (S); is installed between the wiping roll and the pinch roll.

Abstract: Provided is a cooling system for a hot-rolled steel strip capable of increasing the cooling rate for rapidly cooling a rolled steel immediately after rolling and suitable for an apparatus for manufacturing a hot-rolled steel strip having a fine-grained structure. For this purpose, guides (16A, 16B) having guiding surfaces (16a, 16b) to guide a rolled steel (W) exiting work rolls (12A, 12B) in the conveyance direction are provided at exits of the work rolls in a final stand (Sn) of a finish rolling mill line in a manner that the guides can follow a change in the diameter of the work rolls, a number of injection holes (21A, 21B) are formed in the guides, and a number of rolled steel cooling nozzles (23A, 23B) are provided to spray a large amount of cooling water through the injection holes directly onto the rolled steel.

Abstract: A partially-reduced iron producing apparatus includes: a supplying device laying ignition raw-material pellets on an endless-grate; a heating furnace heating the ignition raw-material pellets; another supplying device laying the raw material pellets on the ignition raw-material pellets; and an exhaust gas circulation device supplying an oxygen-containing gas to the raw-material pellets. The oxygen containing gas is made by circulating part of an exhaust gas discharged from the raw-material pellets and mixing it with air. A partially-reduced iron is produced by thermally reducing the raw-material pellets in a bed height direction thereof through separate combustion and heating regions. The combustion region formed on an upstream side in a travelling direction of the endless grate by supplying the oxygen-containing gas having a high oxygen concentration.

Abstract: A reduction furnace includes a pellet material supplying device forming on a grate an ignition carbon material layer having a predetermined height; an ignition device; and an exhaust gas circulation device supplying an oxygen-containing gas comprising circulated exhaust gas mixed with air, to a packed bed of the pellets heated by a combustion heat of the ignition carbon material layer. A partially-reduced iron is produced by thermally reducing the pellets through a combustion region for the ignition carbon material layer and a heating region, the combustion region formed upstream in a travelling direction of the grate by supplying a gas having a high oxygen concentration, the heating region formed downstream of the combustion region by supplying a gas having a low oxygen concentration.

Abstract: Provided is a method of controlling operation of a tandem rolling mill which enables large reduction rolling in the latter-stage stand of the tandem rolling mill necessary for manufacturing fine-grained steel, and so on. The method comprises: a step of determining a first exit-side sheet thickness in rolling a constant portion of a material to be rolled; and a step of determining a second exit-side sheet thickness in rolling a front end portion of the material, such that a pre-tightening load becomes a set value or less; the material is rolled into the second exit-side sheet thickness, until the front end portion is fed into the stands; the constant portion is rolled by the stand given a pre-tightening load into the first exit-side sheet thickness; and the second exit-side sheet thicknesses of the stands given the pre-tightening load are made larger than the first exit-side sheet thickness.

Abstract: A cluster-type multistage rolling mill includes: a top inner housing a top roll group; a bottom inner housing a bottom roll group; an entry-side outer housing provided at entry sides of the inner housings and having an opening portion which a strip is allowed to pass through; a delivery-side outer housing provided at delivery sides of the inner housings and having an opening portion which the strip is allowed to pass through; sets of pass line adjusters provided in upper portions of the opening portions, and pressing an entry-side pressing portion and a delivery-side pressing portion of the top inner housing, respectively; and sets of roll gap controlling cylinders provided in lower portions of the opening portions, and pressing an entry-side pressing portion and a delivery-side pressing portion of the bottom inner housing, respectively.

Abstract: Provided is a cooling apparatus discharging water smoothly corresponding to increase of volume density of cooling water securing a high cooling capability. The apparatus disposed on downstream side from a row of hot finish rolling mill, supplying cooling water from above toward a pass line, includes a plurality of cooling nozzles arranged parallel in a pass line direction, and an upper surface guide disposed between the pass line and the cooling nozzles, wherein a predetermined relation is satisfied when defining: a volume density of cooling water sprayed as qm(m3/(m2·sec)); a pitch of the cooling nozzle in the pass line direction as L(m); a distance between a lower surface of the upper surface guide and the pass line as hp(m); a uniform cooling width as Wu(m); and a cross-sectional area of virtual flow path of discharging water flowing in a width direction of steel sheet as S(m2).

Abstract: A rolling mill, which can use work rolls of a smaller diameter for rolling a hard material and a thin strip material, and can obtain strips of high product quality with high productivity, is provided. For this purpose, a six-high rolling mill includes upper and lower work rolls (2) as a pair for rolling a strip (1), upper and lower intermediate rolls (3) as a pair for supporting the paired upper and lower work rolls, and upper and lower back-up rolls (4) as a pair for supporting the paired upper and lower intermediate rolls, but has no supporting rolls inside and outside the rollable strip width of the work rolls. The work rolls have a small diameter, and use a material having a high longitudinal modulus, such as a hard metal or a ceramic.

Abstract: A partially-reduced iron producing apparatus includes: an exhaust gas circulating device supplying an oxygen-containing gas to raw-material pellets to be heated by ignition of raw-material pellets, the oxygen-containing gas made by circulating part of an exhaust gas by use of the heat of the ignition raw-material pellets and mixing the discharged exhaust gas with air; and a liquid-tar separating device which is provided in the exhaust gas circulating device. A partially-reduced iron is produced by heating and reducing the whole of the raw-material pellets in a bed height direction thereof through a combustion region for the raw-material pellets and a heating region for the raw-material pellets, the combustion region formed on an upstream side of an endless grate by supplying the gas having a high oxygen concentration; and the heating region formed downstream of the combustion region of the endless grate by supplying the gas having a low oxygen concentration.

Abstract: Provided are hot rolling equipment and a hot rolling method for precisely controlling the meandering and plate shape of a steel strip, thereby making it possible to prevent tail end squeezing of the steel strip. Hot rolling equipment (10) for this purpose, for sequentially passing a steel strip (1) through rolling machines (11, 12) and thereby rolling the steel strip (1), wherein a plurality of split rolls (63) capable of contacting the steel strip (1) is provided between the rolling machines (11, 12), and, when the split rolls (63) contact the steel strip (1), detection torques (Td, Tw) acting on the left and right ends of the split rolls (63) are detected by torque detectors (67a, 67b), the reduction leveling of the rolling machines (11, 12) being adjusted on the basis of the detected detection torques (Td, Tw) to control the meandering and plate shape of the steel strip (1).

Abstract: In a gas wiping apparatus for blowing a gas on the front side and the back side of a strip, which exits from a hot-dip plating bath and travels upward, from wiping nozzles to adjust the amount of a plating deposit, the wiping nozzles are supported to be linearly movable beyond the width of the nozzles in the plate width direction of the strip.

Abstract: In an inspection device for inspecting front and back surfaces of a strip material rolled by a rolling machine, both ends of the strip material along a longitudinal direction of the strip material are claimed by two pairs of clamping devices and the front surface of the back surface of the strip material is pressed at an optional position between the two pairs of the clamping devices by at least one pressing device. Thus, after clamping the strip material, the two pairs of the clamping devices are not displaced along the longitudinal direction of the strip material. A function for applying tensile stress to the strip material and a function for clamping the strip material are individually and separately provided so that the inspection device can be simplified. By pressing the strip material at a point between the two pairs of the clamping devices, at least one of pressing devices can be down sized. It is superior in view of an economical reason.

Abstract: A rolling mill, which can use work rolls of a smaller diameter for rolling a hard material and a thin strip material, and can decrease edge drops and improve surface gloss, is provided. For this purpose, a rolling mill, which includes upper and lower work rolls (2) as a pair for rolling a strip (1), upper and lower intermediate rolls (3) as a pair for supporting the upper and lower work rolls as the pair, and upper and lower back-up rolls (4) as a pair for supporting the upper and lower intermediate rolls as the pair, is configured such that the upper and lower work rolls as the pair are supported by a plurality of supporting bearings (8a to 8f and 9a to 9f) arranged vertically zigzag on an entry side in a rolling direction, and a plurality of supporting bearings (10a to 10f and 11a to 11f) arranged vertically zigzag on an delivery side in the rolling direction, at positions outward of a rollable strip width, and the plurality of supporting bearings lap over each other vertically.

Abstract: In order to provide a manufacturing device and a manufacturing method for a hot-rolled steel strip, which are capable of obtaining the desired quality of material by rapid uniform cooling immediately after rolling, and improving yield by early sheet tension and sheet shape measurements, a manufacturing device for a hot-rolled steel strip is provided with a finishing rolling mill line (11), a first cooling unit (13) installed just behind the exit side of the finishing rolling mill line, and a pinch roll (14) which is installed on the exit side of the first cooling unit and in contact with both the upper and lower surfaces of a strip (S), at least a wiping roll (15) located on the upper side of the strip (S) is disposed between the first cooling unit and the pinch roll, and a tension/shape measuring unit (16) for measuring the tension and shape of the strip (S); is installed between the wiping roll and the pinch roll.

Abstract: Provided is a cooling system for a hot-rolled steel strip capable of increasing the cooling rate for rapidly cooling a rolled steel immediately after rolling and suitable for an apparatus for manufacturing a hot-rolled steel strip having a fine-grained structure. For this purpose, guides (16A, 16B) having guiding surfaces (16a, 16b) to guide a rolled steel (W) exiting work rolls (12A, 12B) in the conveyance direction are provided at exits of the work rolls in a final stand (Sn) of a finish rolling mill line in a manner that the guides can follow a change in the diameter of the work rolls, a number of injection holes (21A, 21B) are formed in the guides, and a number of rolled steel cooling nozzles (23A, 23B) are provided to spray a large amount of cooling water through the injection holes directly onto the rolled steel.

Abstract: A partially-reduced iron producing apparatus includes: a supplying device laying ignition raw- material pellets on an endless-grate; a heating furnace heating the ignition raw-material pellets; another supplying device laying the raw material pellets on the ignition raw-material pellets; and an exhaust gas circulation device supplying an oxygen-containing gas to the raw-material pellets. The oxygen containing gas is made by circulating part of an exhaust gas discharged from the raw-material pellets and mixing it with air. A partially-reduced iron is produced by thermally reducing the raw-material pellets in a bed height direction thereof through separate combustion and heating regions. The combustion region formed on an upstream side in a travelling direction of the endless grate by supplying the oxygen-containing gas having a high oxygen concentration.

Abstract: Mash seam welding is performed to weld metal plates with thicknesses of 2 mm or more to stabilize the strength of a joint portion, reduce uneven parts of the joint portion, and ensure high strength and reliability of the joint portion. First, two metal plates, clamped with first and second clamping devices, are placed to overlap each other at their end portions. The overlapping portions (L) of the metal plates are pressed together with a pair of upper and lower electrode wheels while welding currents flow to continuously weld the overlapping portions (L) and join the metal plates. The pressing forces applied to the electrode wheels are controlled so that upper and lower welding forces acting upon the overlapping portions are equal to each other during the time when the overlapping portions are continuously welded.

Abstract: A reduction furnace includes a pellet material supplying device forming on a grate an ignition carbon material layer having a predetermined height; an ignition device; and an exhaust gas circulation device supplying an oxygen-containing gas comprising circulated exhaust gas mixed with air, to a packed bed of the pellets heated by a combustion heat of the ignition carbon material layer. A partially-reduced iron is produced by thermally reducing the pellets through a combustion region for the ignition carbon material layer and a heating region, the combustion region formed upstream in a travelling direction of the grate by supplying a gas having a high oxygen concentration, the heating region formed downstream of the combustion region by supplying a gas having a low oxygen concentration.