- Email: [email protected]
Sealing swivels and couplings
Wang, Cai and Zhang - failure analysis of a heavily loaded gear
Appendix 3. Calculation of the oil film thickness and related parameters Dowson's equation used for the calculation of the oil film thicknesses is as follows: h = 1.60t°'6T/o0"7U°'Tp°'43Et°'°a(L/P) 0"13 h is off film thickness, ~/o is dynamic viscosity of oil (rio = PoP, where Vo is kinematic viscosity and p is specific gravity of the oil, p = 0.9 g/cm 3), E ' is composite Young's modulus (E' = El(1 - u 2) = 2.3 x 107 N/era 2 , where E is Young's modulus of the steel and u is Poisson's ratio), U is the velocity of oil involvement (U = (Ux + U2)/2, where Ul and U2 are tangential velocity of driving and driven gear at the contact point).
Sealing swivels and couplings A set of data sheets on use of polycrystalline diamond for tooling, is available from De Beers Industrial Diamond Division. The set of 13 A4 sheets is divided into three subject areas: tool preparation, tool performance and edge quality. A question is posed on each sheet and the answer is supported by graphs, tables and photographs. Although aimed mainly at the toolmaker, the data sheets should also prove useful to end-users. Free copies of the publications are available in English; French, German and Italian versions will soon follow. De Beers Industrial Diamond Division (Pry) Ltd, Charters, Sunninghill, Ascot, Berkshire SL5 9PX, UK
Polycrystalline diamond tooling Technical Information Sheet 18 des-
cribes the Lotork range of seals from James Walker. The seals are based on an 'elastomer energised' ptfe shell within which the elastomeric contact is completely protected from contact. The result, says James Walker, is a range of seals for rotary swivels, couplhags, actuators and valves which combines low friction, leak tightness and compact housing dimensions.
TRIBOLOGY international
Uz = cozr;
U2 = 6o2r
where 6~z and 602 are angular velocities for driving and
driven gear respectively, and • is composite curvature radius of gears at the contact point. It can be obtained from: r = l[(1/r I + l [ r 2 ) , w h e r e r z andr2 are curvature radius of driving and driven gears, respectively. is viscosity/pressure exponent of oil (o~ = 2.1 x 10-4 cm 2/N) L is contact width of gears (L = 8 cm) P is normal force at contact point. A 1.3 coefficient has been timed for the dynamic loading and the stress concentration of the gear set. The composite curvature radius r and the velocity at the different contact locations under the different loadings are shown in Table A1.
Originally developed for marine unloading arm swivels and offshore buoys where radical reductions in operating torque have been achieved, Lotork seals offer similar benefits, it is claimed, in a variety of services where partial rotation applies. Seal bonding under pressure is eliminated, particularly where long periods in a static position are involved prior to actuation. Materials are available which cater for a temperature range from -90 ° to 250°C and pressures up to 350 bar. Sizes from 25 mm to 1500 mm are available to suit both axial and radial mounting. James Walker & Co Ltd, Lion Works, Woking, Surrey GU22 8AP, UK
Reliability of engineering materials 'Engineering materials encompass a vast spectrum of characteristic types destined for performance in an equally vast spectrum of operating environm e n t s . . . A new discipline of "materials reliability", spawned from the application of reliability engineering techniques to materials science, is rapidly developing' The above extract is taken from the Editor's Preface to the Proceedings of the First European Symposium on Materials Reliability. The meeting, held in Baden, Switzerland, on 26 October 1983 aimed to lay the foundations for
'the definition, assessment and applications of materials reliability', and so to assist the furtherance of the discipline in Europe. Eight papers were presented*, and these have been edited by A.L. Smith to produce consistency, and then arranged in a logical sequence. The Proceedings - Reliability of Engineering Materials - are published at £18.00 by Butterworths, Borough Green, Sevenoaks, Kent TN15 8PH, UK (ISBN 408 01507 1)
* Contents Smith A.L. THe reliability of engineering materials - an introduction and overview Plstone V., Venzi S. and Re G. Structural integrity modelling Lucia A.C. Assuring the reliability of structural components - experimental data and non-destructive examination requirements Buresch F.E. Reliability aspects of non-metallic structural materials Hoffelner W. Metallurgical factors affecting the reliability of materials in high-temperature applications of turbines Kr6ckel H. Materials properties data bases for materials reliability Gavelli G., Scala C. and Colombari V. Materials reliability data banking an example from the chemical industries Miiller R. The reliability of materials in heat-exchanger applications
99
Appendix 3. Calculation of the oil film thickness and related parameters Dowson's equation used for the calculation of the oil film thicknesses is as follows: h = 1.60t°'6T/o0"7U°'Tp°'43Et°'°a(L/P) 0"13 h is off film thickness, ~/o is dynamic viscosity of oil (rio = PoP, where Vo is kinematic viscosity and p is specific gravity of the oil, p = 0.9 g/cm 3), E ' is composite Young's modulus (E' = El(1 - u 2) = 2.3 x 107 N/era 2 , where E is Young's modulus of the steel and u is Poisson's ratio), U is the velocity of oil involvement (U = (Ux + U2)/2, where Ul and U2 are tangential velocity of driving and driven gear at the contact point).
Sealing swivels and couplings A set of data sheets on use of polycrystalline diamond for tooling, is available from De Beers Industrial Diamond Division. The set of 13 A4 sheets is divided into three subject areas: tool preparation, tool performance and edge quality. A question is posed on each sheet and the answer is supported by graphs, tables and photographs. Although aimed mainly at the toolmaker, the data sheets should also prove useful to end-users. Free copies of the publications are available in English; French, German and Italian versions will soon follow. De Beers Industrial Diamond Division (Pry) Ltd, Charters, Sunninghill, Ascot, Berkshire SL5 9PX, UK
Polycrystalline diamond tooling Technical Information Sheet 18 des-
cribes the Lotork range of seals from James Walker. The seals are based on an 'elastomer energised' ptfe shell within which the elastomeric contact is completely protected from contact. The result, says James Walker, is a range of seals for rotary swivels, couplhags, actuators and valves which combines low friction, leak tightness and compact housing dimensions.
TRIBOLOGY international
Uz = cozr;
U2 = 6o2r
where 6~z and 602 are angular velocities for driving and
driven gear respectively, and • is composite curvature radius of gears at the contact point. It can be obtained from: r = l[(1/r I + l [ r 2 ) , w h e r e r z andr2 are curvature radius of driving and driven gears, respectively. is viscosity/pressure exponent of oil (o~ = 2.1 x 10-4 cm 2/N) L is contact width of gears (L = 8 cm) P is normal force at contact point. A 1.3 coefficient has been timed for the dynamic loading and the stress concentration of the gear set. The composite curvature radius r and the velocity at the different contact locations under the different loadings are shown in Table A1.
Originally developed for marine unloading arm swivels and offshore buoys where radical reductions in operating torque have been achieved, Lotork seals offer similar benefits, it is claimed, in a variety of services where partial rotation applies. Seal bonding under pressure is eliminated, particularly where long periods in a static position are involved prior to actuation. Materials are available which cater for a temperature range from -90 ° to 250°C and pressures up to 350 bar. Sizes from 25 mm to 1500 mm are available to suit both axial and radial mounting. James Walker & Co Ltd, Lion Works, Woking, Surrey GU22 8AP, UK
Reliability of engineering materials 'Engineering materials encompass a vast spectrum of characteristic types destined for performance in an equally vast spectrum of operating environm e n t s . . . A new discipline of "materials reliability", spawned from the application of reliability engineering techniques to materials science, is rapidly developing' The above extract is taken from the Editor's Preface to the Proceedings of the First European Symposium on Materials Reliability. The meeting, held in Baden, Switzerland, on 26 October 1983 aimed to lay the foundations for
'the definition, assessment and applications of materials reliability', and so to assist the furtherance of the discipline in Europe. Eight papers were presented*, and these have been edited by A.L. Smith to produce consistency, and then arranged in a logical sequence. The Proceedings - Reliability of Engineering Materials - are published at £18.00 by Butterworths, Borough Green, Sevenoaks, Kent TN15 8PH, UK (ISBN 408 01507 1)
* Contents Smith A.L. THe reliability of engineering materials - an introduction and overview Plstone V., Venzi S. and Re G. Structural integrity modelling Lucia A.C. Assuring the reliability of structural components - experimental data and non-destructive examination requirements Buresch F.E. Reliability aspects of non-metallic structural materials Hoffelner W. Metallurgical factors affecting the reliability of materials in high-temperature applications of turbines Kr6ckel H. Materials properties data bases for materials reliability Gavelli G., Scala C. and Colombari V. Materials reliability data banking an example from the chemical industries Miiller R. The reliability of materials in heat-exchanger applications
99