Space mechanisms and tribology

Space mechanisms and tribology

Hou, Chen and Zheng - tribology of machine tool slideways plane figures of the two kinds of scraped surface, while Figs 13(a) and (b) show the profil...

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Hou, Chen and Zheng - tribology of machine tool slideways

plane figures of the two kinds of scraped surface, while Figs 13(a) and (b) show the profiles in vertical section as recorded using a Talysurf 5P surface measuring system. Analysing the measuring results it is obvious that: W-S surfaces possess a shallow scraping mark of only 1-2/am depth; N-D surfaces have 10-20/am deep marks • W-S possesses a larger scraping mark than N-D. The average slope of proftle is about 0.5 minutes, whereas N-D is about 0.5 degrees. So W-S should offer a much better hydrodynamic effect than that of N-D • The percentage of lapping contact area of W-S is about 30-70%, while N-D is about 5% only. This makes quite a large difference in real contact pressure • In W-S, high planes surround the low-lying areas. In N-D the opposite is true, with isolated high spots being surrounded by deep low-lying areas. Thus, the oil-f'tim retaining ability of N-D must unquestionably be destroyed. •

The ftrst two of the above f'mdings explain why W-S surfaces possess good oil-film forming ability; the last two demonstrate why they also possess good oil-fdm retaining ability. These two aspects complement each other. The authors believe that good results can be obtained if guideway surface topography has been designed reasonably. The choice of scraping parameters should depend on the average operating pressure, sliding speed, lubricant, and guideway materials. In addition, it also depends on other operating conditions (travel distance, time interval, etc) and on the requirements of guideway performance (antifriction, stick-slip resistance, anti-wear, rigidity of oil ftlm, etc).

Cairo Conference The 3rd Cairo University Conference on Mechanical Design and Production will be held on 28-30 December 1985. It is intended to cover two specific subject areas of the broad title: analysis and design of mechanical systems and components, including tribology, materials and stresses; and production technology and industrial engineering. Information available from: Dr Maher Y.A. Younan, MDP-3 General Secretary, Dept of Mechanical Design & Production, Faculty of Engineering, Cairo University, Giza, Egypt

Space mechanismsand tribology The Second European Space Mechanisms and Tribology Symposium is scheduled for 9-11 October 1985 in

TRI BO LOGY international

Summary It seems that striking results could be obtained by properly researching for an outstanding guideway topography. This could also reduce the amount of labour involved in scraping. For scraped guideway surfaces, attention must be paid to the form, size, arrangement, and interval of the scraping marks. in principle, machined guideways could offer as good a performance as scraped guideways if their surface topographies are under control.

Acknowledgement

The authors are grateful to Shoudu Machine Works, Tian-jin University, and National Metrology Institute for their enthusiastic support, and to Mr Zhang Zhaori, Assistant Professor Lu Daojiang and other people who provided assistance.

References 1. ZhangZlmotiet al. Machine tools, 1980, No 4, 28 (in Chinese)

2. Naluud~imaK., Ueno T. sad Morita H.Res. Rep. of Kyushi Ind. Univ., 1977, No 35, 125 fin Japanese)

3. Kato S., Marui E., KobayashiA. and blatsubayashi T. ASME Paper No. 79-WA/PROD-6 and ASME Paper No. 79-WA/

PROD-7, 1979 4. Napoka S. Lubrication, 1978, 23 (5), 317 (in Japanese) 5. Leehle~ G. lndustrie Anzeiger, 1980, 102 (28), 35 6. Ernst P. and Theimert P.-H. Werkstatt und Betrieb, 1977, 110 [4), 203

Schloss Meersburg, Germany. The Symposium is to be sponsored jointly by the European Space Agency (ESA), Dornier System and DFVLR, and the organizers expect papers from most of the ESA member states as well as Canada and USA. Among the topics to be covered are: tribology of bearings, gears, contacts and lubricants, test techniques and results, and descriptions of experience with flight hardware. Mr D. Wyn Roberts, ESA/ESTEC, Div. TPA, 2200 AG Noordwijk, The Netherlands. ESA, 8-10 rue Mario.Nikis, 75738 Paris Cedex 15~ France

SummerSession High friction and wear is thought to account for more than 6% of US gross national product. Yet the average US

University mechanical engineering course features less than two hours instruction on wear. Against these revealing statistics, the Massachusetts Institute of Technology is holding a course entitled, Tribology: Friction and Wear, as part of its Summer Session in Europe. The course is to run from 17 to 21 June, 1985 at Stirling University, Scotland and will be presented by Professor E. Rabinowicz and Professor N.P; Suh of MIT An up to date insight into tribology will be given featuring the concepts of surface energy and delamination, experimental techniques and qualitative tribological relationships, and the tribological properties of polymers and composites. Further details on Program Number 2.81e are available from: Office of the Summer Session, Room E 19-356, Massachusetts Institute of Technology, Cambridge, MA 02139, USA 129