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Spiral groove bearings, thesis, 1964
progress reports which, at the time of writing, were not sufficiently advanced to be presented 111 technical journals. It is gratifying to read, once in a while, about research before it has become history. (Space limitations do not permit reproductionin Wear of the abstracts of all these papers. They are published, however, in STAR, I (IO) sect. 17 (Aug. 23. Ig63).) The fifty-eight papers were discussed in the following sections: gas turbine lubricants, liquid metal lubrication and the properties of liquid metals, greases, solid film lubricants and aerospace lubricants. There are also sections on hydraulic and other technical fluids. The design of machint parts was discussed in sections on gas bearings, aerospace bearings and bearing fatigue. From the point of view of materials science the systematic approach has not been changed by the introduction of high speeds and outer space conditions. Much of the work done is focusscd on the evaluation of laboratory tests and their relation to service performance. New and unconventional approaches are found in X-ray analysis of the decomposition of solid lubricants, in the study of thermophysical properties of alkali metals (proposed as working fluids in Kankine-cycle engines), and a first step in the study of liquid metal condensation problems. Among the bearing papers are several re-stating present experience and future requirements. The book is of intcrcst to workers actively engaged in research on advanced lubrication problems, but also to specialists in atomic (liquid metal) reactor design. Finally it is recommended to those who arc interested in learning the mechanics of cooperative research as an example of a highly efficient way to achieve the aim: co-operation. G.S. Weav, 7 (‘964)
559~560
Spiral Groove Bearings, Thesis, 1964 by E. A. MUYDERMAN, 196 pp. ; numerous figures and tables. Available as a Philips Research Supplement from: Natuurkundig Laboratorium der N.V. Philips Gloeilampenfabrieken, Kastanjelaan, Eindhoven, The Netherlands. This thesis has been written under the supervision of Professor H. BLOK, Delft. It covers work performed in the physics laboratory of Philips, Eindhoven. The following summary is self-explanatory. The work deals with calculations for and use of bearings which transmit a force in the direction of the axis of rotation, and whose rubbing surfaces are provided with spiral grooves; these bearings are spiral groove thrust bearings. Chapter I gives a survey of the previous references to bearings with spiral grooves in the literature, as far as these are known to the author. In Chapter 2, a pattern of inclined parallel grooves is discussed as a simplified model of a real spiral groove bearing, and a first approximate solution for the pressure and friction in such a bearing is derived from this model. Despite the fact that the geometry of a real spiral groove bearing differs from this parallel groove pattern, it seems reasonable to expect that a simple integration based on the results derived for the parallel-groove model will allow the mean radial pressure build-up and the friction in a real spiral groove bearing to be calculated. In Chapter 3 this assumption is tested. The pressure build-up in the spiral groove is accurately calculated for a certain case with the aid of conformal mapping, and it is shown that the simpler integration process, which is preferable from a practical point of view, may in fact be used. The formulae obtained by simple i.ntegration are refined in Chapter 4 by taking the effect of the finite number of grooves (the “end effect”) into account. This effect is determined with the aid of an electrical analogue of the groove pattern. The results obtained in Chapters 3 and 4 arc used in Chapter 5 to derive accurate formulae for the mean radial pressure build-up, the load-carrying capacity and the frictional torque to be expected with real bearings provided with spiral grooves in various ways. The numerical results are given in such a form as to be of direct practical use to those who are not in the first place interested in the theoretical background. Also in the interests of practice, sample calculations are included in the text. The limitations on the applicability of the formulae are discussed in Chapter 6. The theoretical results are compared with experiment in Chapter 7. One very accurate set of measurements gave a discrepancy of less than I .5% between theory and experiment.. The use and fabrication of spiral groove bearings is discussed in Chapter 8. .4s an example of the bearings discussed we may mention here a spherical spiral groove bearing with oil which can be used as a terminal bearing. Such a bearing with a diameter of only 3 mm is capable of taking a thrust load of I kgf at 3000 r.p.m. under full film lubricating conditions; the pressure built up in the centre of the bearing is then 25 atmospheres. Under comparable conditions, a flat thrust bearing with step-shaped depressions would have a load-carrying capacity of only r/z3 kgf. Wear, 7 (1964) 5Go-56r
WEAR
561
A further important property of these small spiral groove bearings is that they work under full film lubricating conditions when used with grease, due to their pump effect. Since grease does not leak away as easily as oil, no costly sealing devices are needed w&h such bearings; this opens interesting possibilities for the use of these bearings in regions where the load, the noise and the wear place limitations on porous bearings, which are still widely used at present. An example of an experimental replacement of porous bearings by spiral groove bearings is illustrated in Fig. 8.5 of this thesis. Chapter g discusses the use of spiral groove bearings for large constructions in which loads of from one to twenty tons are encountered. The problems with regard to the dissipation of heat and the question as to whether stable temperatures and clearances can be obtained under these conditions are briefly dealt with. Wear, 7 (‘964) 560-561
MBcanique des Surfaces Series edited by R. COURTEL ThCorie et Pratique Industrielle du Frottement by J. J. CAUBET, preface by R. COURTEL; Technip, Paris, 1964, Dunod, Paris; 3go pp.; numerous figs. ; price not stated. The purpose of this book is to provide the technician with a practical introduction to the mechanics of surfaces and with a number of rules on the design of machine elements. The first part (about two thirds of the book) gives a highly efficient elementary introduction to the structure of polycrystalline materials, to properties of surfaces and their measurement, as well as to friction and wear. From the level of presentation it is assumed either that the reader has not had a technical college education or that he is not familiar with these particular aspects of technology. The second part is arranged into seven “principles”, advising the designer on check-lists for predicting and calculating the behaviour of a friction couple and to trace trouble, due to many possible sources of wear, in the production and application of machine parts. The educational value of the book must be judged by those familiar with the level of engineering education in France. Readers, and more particularly lecturers, in other countries will be interested in the attempt to compress workshop experience (part II of the book) into less than IOO pages by arranging the matter carefully as a number of “rules”. The method seems attractive for training technicians in countries where the literature written in either English or Russian is not readily available. The alphabetical list of literature is somewhat scanty and scarcely suitable to guide an inexperienced reader. The book is the first in a new series on surface mechanics, a timely synthesis of new concepts in production engineering. G.SA. Wear, 7 (1964) 561
559~560
Spiral Groove Bearings, Thesis, 1964 by E. A. MUYDERMAN, 196 pp. ; numerous figures and tables. Available as a Philips Research Supplement from: Natuurkundig Laboratorium der N.V. Philips Gloeilampenfabrieken, Kastanjelaan, Eindhoven, The Netherlands. This thesis has been written under the supervision of Professor H. BLOK, Delft. It covers work performed in the physics laboratory of Philips, Eindhoven. The following summary is self-explanatory. The work deals with calculations for and use of bearings which transmit a force in the direction of the axis of rotation, and whose rubbing surfaces are provided with spiral grooves; these bearings are spiral groove thrust bearings. Chapter I gives a survey of the previous references to bearings with spiral grooves in the literature, as far as these are known to the author. In Chapter 2, a pattern of inclined parallel grooves is discussed as a simplified model of a real spiral groove bearing, and a first approximate solution for the pressure and friction in such a bearing is derived from this model. Despite the fact that the geometry of a real spiral groove bearing differs from this parallel groove pattern, it seems reasonable to expect that a simple integration based on the results derived for the parallel-groove model will allow the mean radial pressure build-up and the friction in a real spiral groove bearing to be calculated. In Chapter 3 this assumption is tested. The pressure build-up in the spiral groove is accurately calculated for a certain case with the aid of conformal mapping, and it is shown that the simpler integration process, which is preferable from a practical point of view, may in fact be used. The formulae obtained by simple i.ntegration are refined in Chapter 4 by taking the effect of the finite number of grooves (the “end effect”) into account. This effect is determined with the aid of an electrical analogue of the groove pattern. The results obtained in Chapters 3 and 4 arc used in Chapter 5 to derive accurate formulae for the mean radial pressure build-up, the load-carrying capacity and the frictional torque to be expected with real bearings provided with spiral grooves in various ways. The numerical results are given in such a form as to be of direct practical use to those who are not in the first place interested in the theoretical background. Also in the interests of practice, sample calculations are included in the text. The limitations on the applicability of the formulae are discussed in Chapter 6. The theoretical results are compared with experiment in Chapter 7. One very accurate set of measurements gave a discrepancy of less than I .5% between theory and experiment.. The use and fabrication of spiral groove bearings is discussed in Chapter 8. .4s an example of the bearings discussed we may mention here a spherical spiral groove bearing with oil which can be used as a terminal bearing. Such a bearing with a diameter of only 3 mm is capable of taking a thrust load of I kgf at 3000 r.p.m. under full film lubricating conditions; the pressure built up in the centre of the bearing is then 25 atmospheres. Under comparable conditions, a flat thrust bearing with step-shaped depressions would have a load-carrying capacity of only r/z3 kgf. Wear, 7 (1964) 5Go-56r
WEAR
561
A further important property of these small spiral groove bearings is that they work under full film lubricating conditions when used with grease, due to their pump effect. Since grease does not leak away as easily as oil, no costly sealing devices are needed w&h such bearings; this opens interesting possibilities for the use of these bearings in regions where the load, the noise and the wear place limitations on porous bearings, which are still widely used at present. An example of an experimental replacement of porous bearings by spiral groove bearings is illustrated in Fig. 8.5 of this thesis. Chapter g discusses the use of spiral groove bearings for large constructions in which loads of from one to twenty tons are encountered. The problems with regard to the dissipation of heat and the question as to whether stable temperatures and clearances can be obtained under these conditions are briefly dealt with. Wear, 7 (‘964) 560-561
MBcanique des Surfaces Series edited by R. COURTEL ThCorie et Pratique Industrielle du Frottement by J. J. CAUBET, preface by R. COURTEL; Technip, Paris, 1964, Dunod, Paris; 3go pp.; numerous figs. ; price not stated. The purpose of this book is to provide the technician with a practical introduction to the mechanics of surfaces and with a number of rules on the design of machine elements. The first part (about two thirds of the book) gives a highly efficient elementary introduction to the structure of polycrystalline materials, to properties of surfaces and their measurement, as well as to friction and wear. From the level of presentation it is assumed either that the reader has not had a technical college education or that he is not familiar with these particular aspects of technology. The second part is arranged into seven “principles”, advising the designer on check-lists for predicting and calculating the behaviour of a friction couple and to trace trouble, due to many possible sources of wear, in the production and application of machine parts. The educational value of the book must be judged by those familiar with the level of engineering education in France. Readers, and more particularly lecturers, in other countries will be interested in the attempt to compress workshop experience (part II of the book) into less than IOO pages by arranging the matter carefully as a number of “rules”. The method seems attractive for training technicians in countries where the literature written in either English or Russian is not readily available. The alphabetical list of literature is somewhat scanty and scarcely suitable to guide an inexperienced reader. The book is the first in a new series on surface mechanics, a timely synthesis of new concepts in production engineering. G.SA. Wear, 7 (1964) 561