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457 results about "Contact fatigue" patented technology

Steel rail with excellent contact fatigue performance and production method thereof

ActiveCN104120354AGood resistance to rolling contact fatigueRolling contact fatigueRoom temperature
The invention relates to a steel rail with excellent contact fatigue performance and a production method thereof. The steel rail with excellent contact fatigue performance comprises the following elements in percentage by weight: 0.68-0.75% of C, 0.2-0.8% of Si, 0.4%-1% of Mn, 0.3%-0.7 % of Cr, 0.04%-0.12% of V, less than or equal to 0.01% of S, less than or equal to 0.02% of P and the balance of Fe and inevitable impurities. The production method comprises the following steps of carrying out LF refining and RH vacuum treatment in a converter to obtain a square billet, rolling the square billet to form a steel rail of which the cross section is 50-75kg/m, and carrying out accelerated cooling on the rail head part by using the waste heat of the steel rail and adopting a water spray mixed gas with a cooling speed of 5-8 DEG C/s; and when the temperature of the surface of the rail head is cooled to 500-550 DEG C, continuously cooling the rail head by virtue of compressed air with a cooling rate of 2-4 DEG C/s until the temperature of the surface of the rail head is cooled to below 400 DEG C, stopping the accelerated cooling and carrying out air-cooling to room temperature. According to the steel rail disclosed by the invention, the interlamellar spacing in pearlite colonies located at a position from the steel rail head tread to 20mm beneath is 0.07-0.1mu m, the tensile strength of the steel rail is greater than or equal to 1200MPa, the elongation of the steel rail is greater than or equal to 12% and the steel rail has excellent rolling contact fatigue resistance.
Owner:PANZHIHUA IRON & STEEL RES INST OF PANGANG GROUP

Bidirectional final motion test fixture and bidirectional final motion test method thereof

The invention relates to a bidirectional micro motion test fixture and a bidirectional micro motion test method thereof. The fixture is mainly in the structure that: a planar test-piece fixture (2) is in an inversed V shape, the opposite surfaces of the left and right sides of the lower part are all opened with a groove (4) fit to a planar test-piece (13), and the wall of the groove (4) is provided with a puller screw (3); a spherical test-piece fixture (8) is opened with a spherical test-piece cavity (7) fit to a spherical test-piece (5), and the wall of the spherical test-piece cavity (7) is provided with a puller screw (6); and the vertical axes of the spherical test-piece cavity (7), a piston (9) and the planar test-piece fixture (2) are coincided. One side of the upper part of the planar test-piece fixture (2) is connected with an upper vertical screw (10) while the spherical test-piece fixture (8) is connected with a lower vertical screw (12), and a displacement sensor is connected with the upper vertical screw (10) and the lower vertical screw (12). The test fixture can effectively simulate bidirectional fretting under spherical / surface contact condition, test tribology properties and estimate contact fatigue life of a coating under spherical / surface bidirectional micro motion condition on the existing hydraulic servo micro motion test platform.
Owner:SOUTHWEST JIAOTONG UNIV

High-speed rolling contact fatigue testing machine

The invention discloses a high-speed rolling contact fatigue testing machine. The high-speed rolling contact fatigue testing machine is characterized in that a driving pulley (6) arranged on the upper end of the output shaft of a servo motor (9) is in transmission connection with a driven pulley (8) arranged on the upper end of a static pressure main shaft (5), and the static pressure main shaft (5) is fixed on an upper beam (30) arranged on a rack (3); a servo electric cylinder (2) is connected with a pressure sensor (36) fixed on the lower surface of a moving beam through a connecting piece (15) of the pressure sensor; the upper end of a hydraulic supporting platform (4) is fixed on a sphere base lower part (18), a lower test specimen base (21) is connected with a sphere base upper part (20), and the lower test specimen base (21) is connected with a test specimen base ring (45) in a clearance fit mode. The high-speed rolling contact fatigue testing machine provided by the invention has the advantages that the rolling contact of a bearing material under a high speed and heavy load working condition is simulated, the key parameter of rolling contact fatigue of a testing material can realize accurate detection, and finally, the data support is provided for evaluating the rolling contact fatigue property of the bearing material.
Owner:YANSHAN UNIV

Heat treatment method for diesel engine cam

The invention discloses a diesel engine cam thermal treatment method comprising a carburizing step, a quenching step and a tempering step.After the carburizing step, a pit cooling method is adopted for reducing the deformation of the cam because of the heat treatment process, two times of alkaline bath quenching are adopted for not only reducing thermal stress and deformation, but also having functions of thinning heart crystal grains and eliminating network carbide for satisfying metallography requirement in the first quenching process of the cam, and having a function of assuring to obtain cryptocrystal martensite, residual austenite and partial of granule carbide on the surface for satisfying performance requirements of rigidity, wearing resistance property, contact fatigue degree and the like of the cam surface in the second quenching process of the cam;simultaneously, the cam heart can obtain lath martensite and fine homogeneous ferrite, and the mechanical property of the cam heart can be improved; according to the invention, design requirements of heat rigidity, wearing resistance property, fatigue strength, mechanical property of the cam heart and deflection can all be satisfied, therefore, the manufactured cams can be extensively used in large-scale heavy-duty mechanical equipment.
Owner:CHONGQING YUEJIN MACHINERY

Steel rail with surface decarburized layer smaller than 0.3mm and manufacturing method of steel rail

The invention provides a steel rail with a surface decarburized layer smaller than 0.3mm and a manufacturing method of the steel rail. The steel rail comprises the following chemical components in percentage by weight: 0.60-0.66% of C, 0.10-0.30% of Si, 0.8-1.2% of Mn, 0.2-0.5% of Cr, less than or equal to 0.020% of P, less than or equal to 0.015% of S, less than or equal to 0.0002% of hydrogen, less than or equal to 0.0020% of oxygen and the balance of Fe and unavoidable impurities. The manufacturing method comprises the steps of smelting and continuously casting; refining, and carrying out vacuum treatment by using VD for longer than 25min, wherein the content of hydrogen is lower than 2.0PPm; and carrying out blank casting treatment, namely carrying out hot delivery and hot charging, wherein the blank casting temperature is higher than 760 DEG C, a heating zone in a heating furnace is at a weak-oxidative atmosphere, the furnace temperature at the heating zone is 1250-1320 DEG C, the air coefficient at the heating zone is 1.0-1.20, a soaking zone is at a reducing atmosphere, the furnace temperature at the soaking zone is 1150-1250 DEG C, and the air coefficient at the soaking zone is 0.80-1.00. The surface decarburized layer of the steel rail is smaller than 0.3mm, so that the polishing quantity of an upper rail of a high-speed rail can be reduced; and the structure of the surface layer of the steel rail is refined, so that the hardness of the surface layer can be favorably improved, the surface contact fatigue injury of the steel rail can be reduced, and the service life of the steel rail can be prolonged.
Owner:ANGANG STEEL CO LTD

Forging method of bearing ring

The invention relates to a forging method of a bearing ring. The forging method is characterized by comprising the following steps of heating, raising the temperature, preserving the temperature, forging, quickly cooling and naturally cooling, wherein in the heating step, a bearing ring blank is heated from common temperature to the temperature of 900 DEG C; in the temperature raising step, the temperature of the bearing ring blank is raised from 900 DEG C to 1150 DEG C; in the temperature preserving step, the temperature of the bearing sleeve blank is preserved for 0.5 to 1 hour at 1150 DEG C; and in forging step, the bearing ring forged is at 930 to 980 DEG C; and in the quickly cooling step, the forged bearing ring is dipped into a cooling medium for being quickly cooled to reach 700 DEG C. According to the forging method, the cooling medium is water; the quick cooling is carried out for 7 to 18 seconds; the heating is carried out for 4 to 7 seconds; and the temperature raising time is 2 to 3 seconds; and the forging is carried out for 4 to 7 seconds. With the adoption of the forging method, spherical, small and uniformly distributed quenching structures of carbide can be obtained, and the dimension of carbide particle is not greater than 5 um to the maximum, thus reaching the value below the critical value of cracking initiated by amorphous impurity; and the contact fatigue life of a bearing is prolonged.
Owner:DEQING TIANMA BEARING CO LTD

Mine vehicle axle wheel reductor planetary gear and manufacture method thereof

The invention relates to a mine vehicle axle wheel reductor planetary gear and a manufacture method thereof. The manufacture method comprises the following processing steps of: (1) forging to obtain a gear ring; (2) roughly turning; (3) carrying out preheat treatment; (4) finely turning; (5) carrying out ultrasonic flaw detection; (6) hobbing; (7) boring a plurality of oilholes in the wall of a planet wheel inner hole in the middle of the gear ring along the radial direction of the planet wheel inner hole; (8) carburizing for heat treatment; (9) performing plain grinding on two end faces of the gear ring to the required size and then grinding the planet wheel inner hole of the gear ring to the required size; (10) grinding the gear; (11) carrying out magnetic powder inspection; (12) strengthening shot peening at gear root; and (13) carrying out manganese phosphating. The planetary gear produced by adopting the manufacture method, disclosed by the invention has the advantages that the contact fatigue strength is better, the reliability is greatly enhanced and the service life is greatly prolonged; and according to the manufacture method provided by the invention, shot peening strengthening is adopted in processing the gear root, and the stress state of the gear root is changed, so that the gear root bending strength of the planetary gear is remarkably enhanced, the strength of the planetary gear is enhanced and the service life of the planetary gear is prolonged.
Owner:WUXI WEIFU CHINA ITAL GEAR

Hub reductor for mine electric drive heavy-duty car

The invention is suitable for the field of mechanical transmission devices, in particular to the field of transmission devices for large-tonnage mining dump trucks with electric wheels, and provides a hub reductor for a mine electric drive heavy-duty car. The hub reductor is characterized by adopting three stages of planetary reducing mechanisms; the first-stage and the second-stage planetary reducing mechanisms are differential gear trains; the third-stage planetary reducing mechanism is an ordinary gear train; in first-stage transmission and second-stage transmission, sun gears are power input components, and planet carriers and gear rings are power output components; and in third-stage transmission, a sun gear is a power input component, a planet carrier is fixed, and a gear ring is a power output component. The invention has the benefits that the transmission ratio changes within a large range, so as to transmit even larger torque; one more stage of planetary reducing mechanism is adopted for providing driving torque required by driving the heavy duty car, so that the bending fatigue stress and the contact fatigue stress of a last stage gear are reduced, which ensures higher safety factor; and the axial space utilization rate of the whole hub reductor is improved while the radial space is fully used, so that the integral radiating area is enlarged to achieve integral thermal balance better.
Owner:UNIV OF SCI & TECH BEIJING
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