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Analysis of New, Energy-Efficient Hydraulic Unit for Machine Tools
Christian Brecher,David Jasper,Marcel Fey 한국정밀공학회 2017 International Journal of Precision Engineering and Vol.4 No.1
In machine tools, hydraulic units are one of the main consumers of energy. Hydraulically driven functionalities of machine tools include tool clamping, tool change, work piece clamping or palette change operating. For these functions, two pressure circuits (60 bar and 200 bar) are necessary. This paper introduces a novel, energy-efficient hydraulic unit that combines a variable displacement pump with a variable speed controlled drive and hydraulic booster. The result is a lower overall energy consumption and decreased operating temperatures of the hydraulic unit. Hydraulic fluids contain up to 85% mineral oil. This paper also introduces a mineral oil-free, water-based hydraulic fluid, which will be replacing a conventional mineral oil-based hydraulic fluid (ISO-VG 46) within the novel energy-efficient hydraulic unit. The effects on the unit’s performance (operating temperature, pressure, flow rate, power consumption, efficiency) will be evaluated.
Design and Development of a High Efficiency Air Turbine Spindle for Small-Part Machining
Paul Harris,Michael Wintterer,David Jasper,Barbara Linke,Christian Brecher,Stephen Spence 한국정밀공학회 2020 International Journal of Precision Engineering and Vol.7 No.5
This paper reports on the development of a high efficiency and low inertia miniature pneumatic turbine for ultra-high-speed manufacturing spindle applications. It is proposed that radial-inflow/axial-outflow type turbines are well suited for micromachining spindles. To validate the turbine performance potential, a proof-of-concept prototype turbo-spindle was developed and experimentally tested. The prototype spindle produced a net mechanical power output of over 60 W at a speed of 90,000 rpm. The experimental results demonstrate a micro-turbine efficiency of over 50% and a turbine power output of approximately 100 W. This compares to a typical turbine efficiency of around 20% in commercial micro-machining spindles. Further potential improvements to both turbine and spindle energy efficiency are outlined.
( Elipane Levi Esteban? ),( Esteban Jessie ),( Sanchez Janry ),( Coro Gina ),( Gibaga Annaliza ),( Dalupang Jane ),( David Dennis ),( Elipane Jasper ) 한국수학교육학회 2013 수학교육 학술지 Vol.2013 No.-
This paper is a report on the foreseen benefits and challenges on mathematics teacher professional development as the teachers in a small private school in Antipolo City, Philippines were sensitized to the notion of Lesson Study. Utilizing the Anthropological Theory on Didactics as an analytical tool, the teacher’s utterances regarding their lived and imagined experiences during a two-week training on Lesson Study were analysed. Three main issues emerged: 1) The importance of having concrete images of non-traditional mathematics teaching; 2) The affordances brought about by having supportive leadership; and 3) Collaboration as an empowering factor for teachers.