摘要:
A ball screw is provided in which an outer circumferential formation is formed at a portion facing a ball circulating passage out of outer circumferential surface of a nut. The ball screw includes: a screw shaft having on its outer circumferential surface a screw groove; a nut having on its inner circumferential surface a screw groove facing the screw groove; a plurality of balls rollably loaded in a spiral ball rolling passage formed by both screw grooves; and a ball circulating passage to return the balls from a start point to an end point of the ball rolling passage for recirculation. The ball circulating passage is a concaved groove formed by concaving a groove on a part of the cylindrical inner circumferential surface of the nut by plastic working. Then, a flange is integrally provided at a portion facing the ball circulating passage and the screw groove.
摘要:
Since centers of a second gear, a fourth gear and a sixth gear coincide with each other and are disposed rotatably round a circumference of the same long shaft, a compact configuration can be realized while using a gear train of five gears to obtain a reduction gear ratio of a high gear ratio. The configuration in which the three gears have the same rotational center shaft in the way described above in an actuator which incorporates a plurality of gears is advantageous in that the number of center shafts is reduced and that the number of supporting holes in a housing which support center shafts is reduced.
摘要:
The present invention provides an ultra soft high carbon hot-rolled steel sheet. The ultra soft high carbon hot-rolled steel sheet contains 0.2% to 0.7% of C, 0.01% to 1.0% of Si, 0.1% to 1.0% of Mn, 0.03% or less of P, 0.035% or less of S, 0.08% or less of Al, 0.01% or less of N, and the balance being Fe and incidental impurities and further contains 0.0010% to 0.0050% of B and 0.05% to 0.30% of Cr in some cases. In the texture of the steel sheet, an average ferrite grain diameter is 20 μm or more, a volume ratio of ferrite grains having a grain diameter of 10 μm or more is 80% or more, and an average carbide grain diameter is in the range of 0.10 to less than 2.0 μm. In addition, the steel sheet is manufactured by the steps, after rough rolling, performing finish rolling at a reduction ratio of 10% or more and at a finish temperature of (Ar3−20° C.) or more in a final pass, then performing first cooling within 2 seconds after the finish rolling to a cooling stop temperature of 600° C. or less at a cooling rate of more than 120° C./sec, then performing second cooling so that the steel thus processed is held at 600° C. or less, then performing coiling at 580° C. or less, followed by pickling, and then performing spheroidizing annealing at a temperature in the range of 680° C. to the Ac1 transformation point.
摘要:
An ultra soft high carbon hot-rolled steel sheet has excellent workability. The steel sheet is a high carbon hot-rolled steel sheet containing 0.2 to 0.7% C, and has a structure in which mean grain size of ferrite is 20 μm or larger, the volume percentage of ferrite grains having 10 μm or smaller size is 20% or less, mean diameter of carbide is in a range from 0.10 μm to smaller than 2.0 μm, the percentage of carbide grains having 5 or more of aspect ratio is 15% or less, and the contact ratio of carbide is 20% or less.
摘要:
An ultra soft high carbon hot-rolled steel sheet has excellent workability. The steel sheet is a high carbon hot-rolled steel sheet containing 0.2 to 0.7% C, and has a structure in which mean grain size of ferrite is 20 μm or larger, the volume percentage of ferrite grains having 10 μm or smaller size is 20% or less, mean diameter of carbide is in a range from 0.10 μm to smaller than 2.0 μm, the percentage of carbide grains having 5 or more of aspect ratio is 15% or less, and the contact ratio of carbide is 20% or less.
摘要:
The present invention provides an ultra soft high carbon hot-rolled steel sheet. The ultra soft high carbon hot-rolled steel sheet contains 0.2% to 0.7% of C, 0.01% to 1.0% of Si, 0.1% to 1.0% of Mn, 0.03% or less of P, 0.035% or less of S, 0.08% or less of Al, 0.01% or less of N, and the balance being Fe and incidental impurities and further contains 0.0010% to 0.0050% of B and 0.05% to 0.30% of Cr in some cases. In the texture of the steel sheet, an average ferrite grain diameter is 20 μm or more, a volume ratio of ferrite grains having a grain diameter of 10 μm or more is 80% or more, and an average carbide grain diameter is in the range of 0.10 to less than 2.0 μm. In addition, the steel sheet is manufactured by the steps, after rough rolling, performing finish rolling at a reduction ratio of 10% or more and at a finish temperature of (Ar3−20° C.) or more in a final pass, then performing first cooling within 2 seconds after the finish rolling to a cooling stop temperature of 600° C. or less at a cooling rate of more than 120° C./sec, then performing second cooling so that the steel thus processed is held at 600° C. or less, then performing coiling at 580° C. or less, followed by pickling, and then performing spheroidizing annealing at a temperature in the range of 680° C. to the Ac1 transformation point.
摘要:
A high-carbon hot-rolled steel sheet with excellent width-direction homogeneity is provided. The steel sheet contains 0.2% to 0.7% carbon, 0.01% to 1.0% silicon, 0.1% to 1.0% manganese, 0.03% or less phosphorus, 0.035% or less sulfur, 0.08% or less aluminum, and 0.01% or less nitrogen, and the balance is iron and incidental impurities. The structure is such that the average ferrite grain size of edge parts of the steel sheet is less than 35 μm, the average ferrite grain size of a part closer to the center of the steel sheet than the edge parts is less than 20 μm, and the average carbide grain size is 0.10 μm or more and less than 2.0 μm. The steel sheet is produced by roughly rolling the steel, finish-rolling the steel at a finishing temperature of more than (Ar3+40° C.), cooling the steel at a cooling rate of more than 120° C./s within two seconds after the finish rolling to a cooling termination temperature of more than 550° C. and less than 650° C., coiling the steel at a temperature of 550° C. or less, pickling the steel, and subjecting the steel to spheroidizing annealing at a temperature of 670° C. to the Ac1 transformation point by a batch annealing method.