摘要:

The friction characteristics of polyimide films bonded to metallic substrates were studied from 25 to 500 C. These results were interpreted in terms of molecular orientation and thermomechanical data obtained by torsional braid analysis (TBA). A large friction transition was found to occur at 40±10 C in a dry argon atmosphere (10 ppm H2O). It was postulated that the mechanical stresses of sliding transform or reorder the molecules on the surface into a configuration conducive to easy shear, such as an extended chain. The molecular relaxation which occurs in this temperature region appears to give the molecules the necessary freedom for this reordering process to occur. The effects of velocity, reversibility, and thermal prehistory on the friction properties of polyimide were also studied.Presented as an American Society of Lubrication Engineers paper at the ASLE/ASME Lubrication Conference held in Miami Beach, Florida, October 21–23, 1975

ISSN:0569-8197    

DOI:10.1080/05698197708982812

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

Eight different graphite fluoride (CFx)ncompounds with fluorine to carbon ratios varying from x = 0.25 to 1.1 were evaluated as burnished films in order to determine the effect of fluorine content on the solid lubricant properties of graphite fluoride. For comparison, similar experiments were conducted on graphite burnished films. It was found that even a small amount of fluorine in graphite fluoride (CF0.25)nimproved the lubricating Properties of graphite. However, such factors as burnishing atmosphere, burnishing technique, test atmosphere, and specimen temperature affected the results as much as varying the fluorine to carbon ratio of the compound. Best life was found for films that were machine-burnished in moist air and tested in moist air.Presented as an American Society of Lubrication Engineers paper at the ASLE/ASME Lubrication Conference held in Miami Beach, Florida, October 21–23, 1975

ISSN:0569-8197    

DOI:10.1080/05698197708982813

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

The absolute viscosities and densities of five lubricant base fluids (unformulated) were determined at pressures to 150,000 psig and temperatures to 300 F with a falling weight viscometer. The lubricants investigated were a sebacate ester, a TMP ester, SAE 20 mineral oil, a 5P4E polyphenyl ether, and a methyl chlorophenyl silicone. The falling weight viscometer and experimental procedures are discussed. Measured properties of the sebacate ester are in excellent agreement with the results of previous investigators. Computergraphics generated equations of viscosity, density, and pressure coefficient of viscosity vs pressure at each temperature are presented.Presented as an American Society of Lubrication Engineers paper at the ASLE/ASME Lubrication Conference held in Miami Beach, Florida, October 21–23, 1975

ISSN:0569-8197    

DOI:10.1080/05698197708982814

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

An object of the design of a concentric recoil bearing is to insure reliable full-film lubrication over as much of the recoil and counter recoil motions as possible. The surface profile has a great effect on the oil film produced in the bearing. A straight bearing profile produces only a thin and unreliable film. A small taper on the leading edge greatly improves the situation. However, a shallow blind slot in the loaded sector of the bearing was the best surface profile of those studied. Although the slot war less than a mil deep, it resulted in a faster acting bearing and an appreciable thicker oil film. At the highest bearing pressure, the 10 millisecond film thickness was almost twice that of the next best profile studied. This design holds great promise, not only for concentric recoil bearings, but also for bearings for reciprocating shafts where the bearings must be fast-acting and where they support large loads.Presented as an American Society of Lubrication Engineers paper at the ASLE/ASME Lubrication Conference held in Miami Beach, Florida, October 21–23, 1975

ISSN:0569-8197    

DOI:10.1080/05698197708982815

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

The friction and wear behavior of hard, nongraphitic carbons sliding against themselves has been studied over a wide range of sliding conditions. Transitions to high friction and wear occur at critical combinations of loads, speeds, and ambient temperatures, but the associated contact temperatures are much higher (>500 C) than those found earlier for graphitic materials (≃150C). In conditions of sliding less severe than those initiating transitions, the coefficients of friction and rates of wear vary appreciably with time, speed, and temperature. Large transient fluctuations in friction can also occur, and these appear to arise mainly from small misalignments of the surfaces induced mechanically or thermally. Explanations of the various trends and phenomena observed are suggested in terms of the relative roles of adhesion, deformation, and surface film formation in the friction and wear processes.Presented as an American Society of Lubrication Engineers paper at the ASLE/ASME Lubrication Conference held in Miami Beach, Florida, October 21–23, 1975

ISSN:0569-8197    

DOI:10.1080/05698197708982816

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

This paper presents a mixed lubrication model for cold rolling of metals. It considers both hydrodynamic lubrication and asperity contact between the roll and the metal. The calculated results show the essential characteristics of friction and the pressure distribution in the roll bite, which indicate that a constant coefficient of friction is a poor assumption. A weighting factor for the contribution of asperity contact is obtained, and the Hitchcock formula is found adequate for representing roll deformation in calculating the inlet lubricant film thickness.Presented as an American Society of Lubrication Engineers paper at the ASLE/ASNE Lubrication Conference held in Miami Beach, Florida, October 21–23, 1975

ISSN:0569-8197    

DOI:10.1080/05698197708982817

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

Solutions are obtained for a moving contact patch on the lip of a seal formed by the end contact of two tubes, on a thermal insulator and one a thermal conductor. It is postulated that a patch of uniform pressure [pbar] of width 21 is moving at a speed c on the lip of the conducting body, and that this gives rise to frictional heating, thermal expansion, wear and elastic deformation. Although the relative displacements produced by all of these effects must sum to zero in the contact patch, for this approximate solution the averages of these quantities will be allowed to sum to zero. Results are compared with prior accurate calculations for zero wear case, showing that the approximation is quantitatively reasonable.Presented as an American Society of Lubrication Engineers paper at the ASLE/ASME Lubrication Conference held in Miami Beach, Florida, October 21–23, 1975

ISSN:0569-8197    

DOI:10.1080/05698197708982818

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

Frictionally heated sliding contact similar to that of a dry or boundary-lubricated seal is investigated, regarding an instability in contact pressure. Above a critical sliding speed, this phenomenon causes the nearly uniform initial distribution to become one with localized high pressure patches. The threshold of instability is shown to be strongly influenced by wear rate. Above a critical wear w* contact is stable irrespective of sliding speed.

ISSN:0569-8197    

DOI:10.1080/05698197708982819

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

Modern industrial machinery is making increasing use of tapered roller bearings for shaft support systems. Tapered roller bearings combine the high radial load capacity of cylindrical roller bearings with the ability of ball bearings to accommodate thrust loading. This is accomplished, however, at the expense of increased geometric and kinematic complexity, with resultant stringent demands on manufacturing tolerance control. With industrial machinery being operated at ever increasing speeds to improve productivity and while manufacturing costs are increasing at a comparable rate, a balance must be effected between performance and geometry control in order to produce cost effective bearings.

ISSN:0569-8197    

DOI:10.1080/05698197708982820

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor