超高压溢流阀静动态特性的研究

本文介绍了超高压技术的一些基本特点,对超高溢流阀的静动态特性进行了详细的理论分析与实验研究,阐明了在超高压领域中对单极直动溢流阀分析时与一般压力下的不同点和应注意,并进行了实验论证。     

浅论德国高压隔膜泵进出料阀的国产化改进

德国Ｅｍｍｒｉｃｈ泵厂生产的高压隔膜泵是中国长城铝业公司管道化溶出一水硬铝石攻关项目的心脏设备。在试生产过程中,因进出工损坏频繁,严重影响了试生产和攻关的进行。本文经过现场观察、理论分析及生产实践,初步确定了高压隔膜泵进出料阀的国产化改进方案,为提高设备的运转率、保证正常生产创造了条件。     

新型氧化铝工业用阀——双偏心式半球阀

氧化铝生产中，阀门的磨损和结垢是影响其使用寿命的主要问题。双偏心式半球阀以其独有的启闭方式与偏心结构的特点，关闭切除结垢，磨损自行补偿，开辟了解决常用阀门存在的问题的新途径。本文介绍了新型阀门的结构特点，总体设计和现场使用情况。     

海、淡水液压阀的研究

针对海、淡水介质的特点，总结了研制海、淡水液压阀的关键技术问题，分析了其气蚀的特点，并提出相应的预防措施，简要介绍了海、淡水液压阀的国内外研究概况，对适合合于海、淡水介质特笥的液压阀的结构型式和工程材料进行了探讨。     

Steel for valves in marine engines

Conclusion Steel 2Kh20N9V2GSM proposed for manufacturing heavily stressed valves, is superior to the previously used steel 2Kh18N8V2, since it is less susceptible to differences in grain size and has superior mechanical properties.Bryansk Machine Construction Plant, Central Scientific-Research Institute of Technology and Mechanical Engineering. Translated from Metallovedeniei Termicheskaya Obrabotka Metallov, No. 6, pp. 73–74, June, 1970.     

Development of permanent-mold cast TiAl automotive valves

This paper presents the results of an EMTEC funded project to develop low-cost TiAl automotive valves. The alloy studied was Ti-47Al-2Nb-1.75Cr (at %). Over 800 valves were cast, using several variations of the permanent-mold process, in a multi-cavity steel mold. Applying pressure during solidification improved the casting fill. However, none of the permanent-mold casting methods produced pore free as-cast valves. The as-cast microstructures of valves produced by permanent-mold casting were much finer than investment castings of similar section sizes. Of the permanent-mold casting methods, the injection cast method exhibited the finest as-cast structure showing a potential for a new high output method for producing fine-grained TiAl components. Room temperature tensile properties of the permanent-mold material were superior to those of investment castings with a similar microstructure. Two sets of valves were road tested for a total of 50000 km with average 2% fuel savings and no valve damage. There is a need to overcome few challenges before this technology can be implemented in the automotive industry.     

TiAl基合金发动机排气门的制备和台架试验

采用真空离心铸造 机加工工艺制备的TiAl基合金排气门在 483Q柴油发动机台架上进行了 48h耐久性试验。结果表明 :TiAl基合金排气门质量轻 ,约为 2 1 4材料排气门质量的 50 % ;TiAl基合金排气门与原气门座组成的摩擦副具有更好的磨合性和耐磨性 ,并且实际接触面积由原来的 30 %提高到 70 % ,相对下沉量由 8.0×1 0 - 3 m降低至 1 .0× 1 0 - 3 m ,说明TiAl基合金排气门可满足高性能发动机的服役要求。     

The development of low-cost TiAl automotive valves

This paper presents the results of a project funded by the Edison Materials Technology Center to develop low-cost titanium aluminide automotive valves. In the course of the project, more than 800 valves were produced using several variations of the permanent-mold casting process. Applying pressure during solidification improved the casting fill; however, none of the permanent mold casting methods produced pore-free as-cast valves. The as-cast microstructures of the valves were much finer than investmentcast microstructures of similar section sizes. The room-temperature tensile properties of the permanent mold castings were superior to those of investment castings of a comparable section size. M.M. Keller earned her M.Sc. in materials engineering at the University of Dayton in 1993. She is currently a Ph.D. student in materials engineering. She is also a member of TMS. P.E. Jones earned her M.Sc. in materials at the University of Dayton in 1993. She is currently a Ph.D. student in materials engineering. She is also a member of TMS. W.J. Porter III earned his M.Sc. in materials engineering at the University of Dayton in 1990. He is currently project engineer at the University of Dayton Research Institute. He is also a member of TMS. D. Eylon earned his D. Sc. in materials engineering at Technion, Haifa, Israel, in 1972. He is currently a professor of graduate materials engineering at the University of Dayton. He is also a member of TMS.     

Regeneration of marine engine valves using laser surfacing

This article presents an analysis of the applicability of laser surfacing of the exhaust valve face of a marine diesel engine using cobalt-based powder. After preparation by machining, the selected valves were subjected to laser surfacing using a high-power ROFIN DL020 laser. The EuTroLoy 16012 powder was used in the surfacing process. One of the valves was cut and subjected to metallographic examination and hardness measurements, while the other valves were assembled in the engine, which worked for approx. 3000 h. The tests conducted for the initial condition showed a dendritic structure of the surfacing weld, characteristic for surfaced layers with carbide inclusions uniformly deposited in interdendritic areas and a minimally changed structure of the steel substrate. Similar tests were carried out for the valves after their period of operation. The valves' faces showed little wear. The microstructure of the surface weld was found to have minor changes mainly due to the effects of diffusion processes occurring in the operating temperature and a decrease in hardness. The laser surfacing technique has proven very useful for the regeneration of marine engine valves.     

Noninvasive evaluation of Bjork-Shiley convexo-concave prosthetic heart valves

Prosthetic heart valves of the Bjork-Shiley convexo-concave (BSCC) type have been used extensively in implants; however, there have been reports of cases where one component of the valves failed, leading to the demise of the patient. This paper presents a new method for noninvasive electromagnetic evaluation for this type of valve, using an eddy current transducer with orthogonal coils. In vitro experiments on BSCC prosthetic heart valve replicas have shown that discontinuities of outlet strut with depths equal or larger than 0.4 mm can be detected with a probability of detection (POD) of 86.4%, and in the case of discontinuities with depth equal or larger than 0.6 mm with POD of 97%. Blind tests effectuated on 32 BSCC prosthetic heart valves have shown that, using the proposed method, the tested valves have been correctly classified.     

Diagnosis of austenitic steel valves with the magneto-optical method

Samples selected from damaged austenitic steel valves of diesel engines have been examined using the magneto-optical (MO) method. The method uses a magnetic excitation normal to the material surface and enables the assessment of two conditions of the originally non-magnetic austenitic steel, namely an integral one, when the coercivity H_c is measured, and a local one that concentrates on the detection and assessment of individual defects. The results have shown that the operational load increases H_c of these materials and a defect of the fatigue crack type has been detected in the position of the valve failure.