Type High Speed Research Articles

Adhesion of Aluminum Alloy to Tip of Nozzle Plate of Vertical Type High Speed Twin Roll Caster

In a vertical type high-speed twin-roll caster, the adhesion of solidified aluminum alloy to the nozzle (ASAN) makes problems with the quality of the strip surface. The effects of the Si content of Al–Si alloys and the casting conditions on the ASAN were investigated. Alloys with Si contents of 0%, 0.5%, 1%, 2%, 3%, 6% and 10% were considered. The ASAN was high for Si contents of 0.5%, 1%, and 2%. This demonstrates that there is a relationship between the quasi-solid state and the ASAN. As the roll speed and molten metal temperature increased and solidification length decreased, the ASAN decreased. On the basis of these results, the stagnation of molten metal near the nozzle plate was investigated. A gap of 5 mm was introduced between the nozzle plate and the roll surface to eliminate the stagnation of molten metal, resulting in reduction of the ASAN.

Effect of Roll Diameter on Temperature of Aluminum Alloy Strip during Casting Using a Vertical Type High Speed Twin Roll Caster

The temperature of an aluminum alloy (Al-6%Si) strip cast using a vertical-type high-speed twin-roll caster was measured by inserting a K-type thermocouple into the strip. The effects of the roll diameter on supercooling, cooling rate, and temperature at the roll bite were investigated. It was found that the roll diameter affects the cooling condition of the strip. The thickness of the thermocouple was 0.1 mm and the sampling rate was 100 Hz. Copper rolls with diameters of 300 and 600 mm, respectively, were used. The roll width was 100 mm and the roll speed was 30 m/min. The roll load was 5 or 20 kN.

Effects of Plasma Nitriding Temperature on the Properties of 1.3207 Type High Speed Steel

Active screen plasma nitriding on HS 10-4-3-10 high-speed steel specimens was performed at three different low nitriding temperatures while trying to keep the other nitriding parameters uniform. In addition, two extra samples were made to increase the treatment time. Optical microscopic investigation and microhardness testing were performed on the segments of the samples, and their qualitative composition was determined by energy-dispersive X-ray spectrometry. Based on the measurements, it is stated that the hardness of the surface can be increased 50% with active screen plasma nitriding.

Effects of Plasma Nitriding Temperature on the Properties of 1.3207 Type High Speed Steel

Kutatásunk során 1.3207 (HS10-4-3-10) gyorsacél próbatesten végeztünk aktív ernyős plazmanitridálást három különböző, kicsinek számító nitridálási hőmérsékleten, miközben a nitridálás további paramétereit egységesen tartottuk. Azt követően további két kezelést végeztünk eltérő nitridálási idő mellett. Az elkészült próbatestek keresztmetszetén mikroszerkezeti vizsgálatokat végeztünk, a felületi összetételüket energiadiszperzív röntgenspektrometriával határoztuk meg. Továbbá a keresztmetszeten és a felületeken vizsgáltuk a keménységet. Vizsgálataink eredményeként elmondható, hogy az aktív ernyős plazmanitridálás technológiájával jelentősen, akár 50%-kal is növelhető a kutatás során használt minta felületi keménysége.

Temperature of Aluminum Alloy Strip During Casting Using a Vertical Type High Speed Twin Roll Caster

The temperature of a strip cast using a vertical type high-speed twin-roll caster was measured by inserting a k-type thermocouple into the strip. The effects of the roll speed and roll load on the cooling rate and temperature at the roll gap were investigated using two aluminum alloys: A383 and Al–4.8%Mg. The thickness of the thermocouple was 0.1 mm, and the sampling time was 0.01 s. The cooling rate increased and the temperature at the roll bite decreased with decreasing roll speed and increasing roll load. The positions of the liquidus and solidus lines were measured, and the reduction of the thickness of the strip was inferred from the roll gap at the solidus line.

Effect of Casting Condition on Ripple Mark and Surface Crack of Roll-Cast Al-Mg Alloy

Effect of casting conditions on ripple mark and surface crack of as-cast Al-4.7%Mg strip was investigated. A vertical type high speed twin roll caster was used. A casting speed was 30 m/min. Casting conditions were tip-shape of a back-dam plate, gap between a roll and the back dam plate and texture on the roll-surface. The texture on the roll-surface was useful to reduce the ripple mark. In bending test conducted to investigate surface crack of as-cast strip, the texture on the roll surface was effective to the reduce the crack. The position of the crack was not coin side with the position of the ripple mark. This result shows that there is no correlation between the ripple mark and the ductility or the strength of as-cast strip. Small roll load was effective to reduce the crack and degree of the ripple mark. Effect of the roll load on the ripple mark was discussed including solidification delay and seepage of Magnesium.

Effects of Nozzle and Roll on Surface Condition of Al-1%Si Strip Cast Using Vertical type High Speed Twin Roll Caster

When a strip of Al-Si alloy with an Si content of 1% was cast using a vertical-type high-speed twin-roll caster, cracks form in its surface. The effects of the pouring method, the shape and position of the nozzle, and the roll surface texture on surface crack formation were evaluated with a roll caster. The rolls were made of a copper alloy, and the roll speed was 30 m/min. The as-cast strips were bent to investigate the degree of crack formation, and the outer surface of the strips was observed without magnification and with a stereomicroscope to determine the influence of the pouring method, the shape and position of the nozzle, and the roll surface. A roll machined to form V-shaped grooves 0.4 mm deep on the surface of the strips was most useful for reducing surface cracking. Changing the shape of the nozzle tip was second-most effective. There was a clear correlation between the roll surface condition and surface cracking in the Al-Si strip.

Performance of a Matrix Type High Speed Steel after Deep Cryogenic and Low Tempering Temperature

A matrix type high speed steel YXR3 designed for a combination of wear resistance and toughness is investigated for its mechanical properties after hardening by deep cryogenic treatment follow by tempering. The deep cryogenic quenching carried out at -200 °C for 36 hours and the single step tempering results in an obvious improvement in wear resistance while balancing the toughness, comparing with the conventional quenching followed by a double tempering treatment. The quantitative image analysis reveals little difference in the MC carbide size distribution between tempering at different temperatures. The synchrotron high energy XRD confirms the MC type carbide with some evolution in its orientation together with tempered martensite approaching the BCC structure at higher temperatures. In contrary to the conventional quenching and tempering, the lowest tempering temperature at 200 °C yields a moderate drop in hardness with increase in surface toughness proportionally while exhibiting exceptional wear resistance. Such thermal cycle can be recommended for the industry both for the practicality and improved tool life.

Structure optimization and flow field simulation of plate type high speed on-off valve

There is a relatively complex flow state inside the high speed on-off valve, which often produces low pressure area and oil reflux in the high-speed opening and closing process of the spool, causing cavitation and vortex and other phenomena. These phenomena will affect the stability of the internal flow field of the plate valve and the flow characteristics of the high speed on-off valve. Aiming at the problems of small flow rate and instability of internal flow field, a new spool structure was designed. The flow field models of two-hole and three-hole plate spools with different openings were established, and software Ansys Workbench was chosen to mesh the model. The standard k-e turbulence model was selected for numerical simulation using Fluent software. The pressure distribution and velocity distribution under the same pressure and different opening degree were obtained. The structure and parameters of the optimization model were also obtained. The stability analysis of flow field under different pressure was carried out. The results demonstrate that the three-hole spool has a similar flow field change with the two-hole spool, but it does not create a low pressure zone, and the three-hole spool can work stably at 2 MPa or less. This method improves the appearance of low pressure area and oil backflow in the process of high speed opening and closing of spool. The stability of flow field and the flow rate of high speed switch valve are improved. Finally, the products designed in this paper are compared with existing hydraulic valve products. The results show that the three-hole plate type high speed on-off valve designed in this paper maintains the stability of the internal flow field under the condition of 200 Hz and large opening degree, and realizes the increase of flow rate.

Strip casting of aluminum alloy for casting using a vertical type high speed twin roll caster and investigation of strip

Strip casting of aluminum alloy for casting using a vertical type high speed twin roll caster and investigation of strip

Fault Analysis and Tolerant Control for High Speed PEMS Maglev Train End Joint Structure with Disturbance Rejection

It is observed in test operation that for permanent magnet electro-magnetic suspension (PEMS) type high speed maglev train, when a single levitation unit in an end joint structure fails to work, the performance of the entire joint structure deteriorates rapidly, whereas in electro-magnetic suspension (EMS) type maglev system, there is no such phenomenon under the same failure. To solve this problem and to enhance system performance under faulty condition, firstly a comparative modeling of EMS and PEMS maglev end joint structure system was made to analyze the underlying reasons. Then a dynamic compensation method and a disturbance rejection method based on disturbance estimation and feedback linearization were proposed respectively. The performances of the proposed measures are verified and compared in simulations.

Fabrication Process of Al-SiCp Strip by Vertical Type High Speed Twin Roll Caster

Fabrication Process of Al-SiC_p Strip by Vertical Type High Speed Twin Roll Caster

Experimental Study on Super-Hydrophobic Copper Surface Fabricated by HS-WEDM

We present a method to fabricate superhydrophobic surfaces on copper substrate using reciprocating type high speed wire cut electrical discharge machining (HS-WEDM) and self-assembly technology. Herein, single factor experiment was used to investigate the influence of several major parameters of the wire electrical discharge machining processing, such as pulse width, pulse gap (pulse interval) and power tube, on the contact angle of resulting surface. Results show that a composite structure, composed of craters and projections, is fabricated on the copper surface, which is the key reason of superhydrophobicity. With the change of pulse width, pulse interval, and the number of the power tube, the hydrophobic properties of resulting copper surface was changed. This paper provided the theoretical support for industrialized fabrications of super-hydrophobic brass surface.

고속철도차량 갱웨이 통로연결막의 내구성 평가

To increase the riding comfort and running stability of articulated type high speed railway vehicles(HSRV), it is important that the gangway connections for the passenger car satisfied fire safety, sound proof and durability under triaxial angular displacement (rolling/yawing/pitching) modes. On the other hand, a domestic test standard on the durability of the rubber components has not been determined. In this study, the fatigue life was predicted using the results of the nonlinear finite element analysis and the fatigue properties. Moreover, a fatigue rig test of the component was constructed to examine the durability.

Mechanical Property of Roll Cast Al-11%Si Alloy

Al-11%Si (-0.44%Fe-0.16%Cu-0.14%Mg) was cast into the strip using a vertical type high speed twin roll caster at speed of 60m/min. Cooling rate of the strip was ranging from 2000OC/s at surface to 1000OC/s at center of thickness. The eutectic Si was smaller than 2μm. The homogenization, cold rolling down to 1mm, and annealing were carried out before the tension test, 180 degrees bending test and deep drawing test. Tensile stress was 192MPa, 0.2%proof stress was 84MPa, and elongation was 23.8%. Roll cast Al-11%Si had excellent elongation. The specimen was not broken by the 180 degree bending. LDR (Limiting Drawing Ratio) of the deep drawing test was 1.8. The ductility was drastically improved by the high speed twin roll caster. These results show that roll cast Al-11%Si has ability to be used for sheet forming. Moreover, Fe was increased up to 1.0% as the model of recycled alloy. The elongation was 15.9% and LDR was 1.7 in the condition that Fe content was 1.0%. Al-Si-Fe intermetallic became fine by the effect of rapid solidification. As the result, deterioration of the ductility was improved.

Experiment Investigation of Hole Accuracy and Surface Roughness in Femur Bone Drilling Using Different Parameters

Success indicators in bone drilling include clean, good accuracy drilled holes without damage at the surrounding tissue. This study investigates the influence of cutting parameters in bone drilling against hole accuracy (enlargement diameter, circularity error, and cylindricity error) and surface roughness (Ra). A series of bone drilling experiments was carried out using femur bovine bone and without irrigation. Variations of drill type (high speed steel and coated and uncoated carbide) and cutting speed (19 m/min and 94 m/min) were used as input variables, while the feed rate (0.025 mm/rev) was constant. It was found that coated carbide drill results minimum magnitude on all machining responses. Type of tool gives significant effect on diameter enlargement and surface roughness, yet not on circularity and cylindricity errors. The range of cutting speed evaluated does not give significant effect on any surface integrity measures.

고속철도차량 갱웨이 벨로우즈의 비선형 해석

갱웨이 벨로우즈는 관절형 고속철도차량 객차 끝단부 사이에 다양한 변위차를 고려하여 갱웨이 프레임에 장착된 이중 주름구조 네오프렌 고무부품이다. 실제 운행중의 벨로우즈의 파손은 터널 통과시 기밀 파손으로 인한 이명현상 발생과 함께 소음 증가로 승객의 승차감에 심각한 영향을 미친다. 본 연구에서는 고속철도차량 갱웨이 벨로우즈의 안전성 연구일환으로서, 차량주행시 차량 끝단부의 3축 회전변위(롤링, 요잉, 피칭변위차)를 고려한 갱웨이 벨로우즈의 비선형 해석을 수행하였다. 본 고무의 비선형 재료 특성은 단축인장 및 등2축 인장시험을 수행하여 구하였다. 또한, 비선형 해석결과로부터 회전변위 및 마찰계수의 영향을 평가하였다. 【Gangway bellows in this study is the double wrinkled neoprene rubber component to accept various deviations between the carriage end parts of the articulated type high speed railway vehicle(HSRV). The fatigue failure of the bellows has a harmful effect on the riding comfort for the passengers with the increase of noise and ringing in the ears due to air-tightness failure during pass through a long tunnel. In this study, to assure the safety of gangway bellows of the HSRV, non-linear analysis of the gangway bellows considering triaxial angular displacement(rolling /yawing/pitching) between the carriage end parts are performed. The non-linear properties of the rubber are determined by uniaxial tension and equi-biaxial tension test. Moreover, from the results of non-linear analysis, the effects of the angular displacements and frictional coefficients are evaluated.】

503 Al合金用縦型高速双ロールキャスターにおけるインライン圧延(GS-4 軽合金)

503 Al合金用縦型高速双ロールキャスターにおけるインライン圧延(GS-4 軽合金)

Twin Roll Casting and Formability of Al-25%Si Alloy Strip

This study was aimed at investigating of Twin roll casting and formability of Al-25%Si alloy strip. Near net shape forming is able to produce that the initial production is very close to the final shape. Near net shape is applied a variety of materials. Twin roll casting process is one of near net shape forming. Hypereutectic Al-Si alloy has some useful advantage low thermal expansion, better thermal conductivity and wear registrant. Recently, the plate of hypereutectic Al-Si alloy which thickness is thinner than 1mm is demanded. The hypereutectic Al-Si alloy is hard and brittle. Therefore, only the many times of hot rolling were useful process to make thin plate. In the present study, the roll casting of Al-25%Si strip was tried by a vertical type high speed twin roll caster from the point of energy saving. The twin roll size of the roll was φ300×W100. Roll-load was set low enough to prevent the sticking of the strip. Casting material was Al-25%Si and Al-25%Si+4%Mg. The roll velocity was 20 m/min. As cast strip of Al-25%Si was 1.6 mm thickness, and Al-25%Si+4%Mg was 2.0 mm thickness. Primary crystal size of as cast Al-25%Si strip was 40-100 μm, as cast Al-25%Si+4%Mg strip was 40 μm. It was able to produce that as rolled strip of 1mm thickness at 1 pass. Primary crystal size of as rolled Al-25%Si strip was 15-40 μm, and as rolled Al-25%Si+4Mg was 15-20 μm.

705 溝ロールを装備した縦型高速双ロールキャスターによるAl合金薄板の作製(GS-4 機械材料)

705 溝ロールを装備した縦型高速双ロールキャスターによるAl合金薄板の作製(GS-4 機械材料)