1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI Standards PublicationPlain bearings Pad materials for tilting pad bearingsBS ISO 14287:2012National forewordThis British Standard is the UK implementation of ISO 14287:2012.The UK participation in it
2、s preparation was entrusted to Technical CommitteeMCE/12, Plain bearings.A list of organizations represented on this committee can be obtained on request to its secretary.This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct ap
3、plication. The British Standards Institution 2013.Published by BSI Standards Limited 2013.ISBN 978 0 580 71615 7 ICS 21.100.10Compliance with a British Standard cannot confer immunity from legal obligations.This British Standard was published under the authority of the Standards Policy and Strategy
4、Committee on 31 January 2013.Amendments issued since publicationAmd. No. Date Text affectedBRITISH STANDARDBS ISO 14287:2012 ISO 2012Plain bearings Pad materials for tilting pad bearingsPaliers lisses Matriaux des patins pour paliers patins oscillantsINTERNATIONAL STANDARDISO14287First edition2012-0
5、2-01Reference numberISO 14287:2012(E)BS ISO 14287:2012ISO 14287:2012(E)ii ISO 2012 All rights reservedCOPYRIGHT PROTECTED DOCUMENT ISO 2012All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical,
6、 including photocopying and microfilm, without permission in writing from either ISO at the address below or ISOs member body in the country of the requester.ISO copyright officeCase postale 56 CH-1211 Geneva 20Tel. + 41 22 749 01 11Fax + 41 22 749 09 47E-mail copyrightiso.orgWeb www.iso.orgPublishe
7、d in SwitzerlandBS ISO 14287:2012ISO 14287:2012(E) ISO 2012 All rights reserved iiiContents PageForeword ivIntroduction v1 Scope 12 Normative references . 13 Requirements . 13.1 General . 13.2 Metallic materials . 13.3 Polymer materials . 23.4 Back metal materials 33.5 Pivot materials . 3Annex A (in
8、formative) Guidance on properties and selection of materials 4BS ISO 14287:2012ISO 14287:2012(E)ForewordISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carri
9、ed out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. I
10、SO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.The main task of technical committees is to prepare Internation
11、al Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote.Attention is drawn to the possibility that some of the eleme
12、nts of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights.ISO 14287 was prepared by Technical Committee ISO/TC 123, Plain bearings, Subcommittee SC 7, Special types of plain bearings.iv ISO 2012 All rights reservedBS ISO
13、 14287:2012ISO 14287:2012(E)IntroductionTilting pad bearings support loads equally with their pads, which are pivoted at the supporting points on their back surfaces. This configuration allows the pads to tilt freely; it serves to keep the shape of the oil film on the sliding surface in optimum cond
14、ition and improve load-carrying capabilities.Such bearings are normally used as thrust and journal bearings for rotating machineries; they operate under static load conditions with lubricating oil applied. They have been used for many years and have a long history. As a result of developments in hig
15、h-speed, high-performance rotating machineries, many various types of pad materials have been put into practical use. ISO 2012 All rights reserved vBS ISO 14287:2012Plain bearings Pad materials for tilting pad bearings1 ScopeThis International Standard specifies requirements for materials based on m
16、etals, polymers, back metals and pivots for the manufacture of tilting pad bearings. 2 Normative referencesThe following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of th
17、e referenced document (including any amendments) applies.ISO 4381, Plain bearings Tin casting alloys for multilayer plain bearingsISO 4383, Plain bearings Multilayer materials for thinwalled plain bearings3 Requirements3.1 GeneralThe sliding surface of a pad may be composed of a metal bearing materi
18、al or a polymer material, which is typically bonded to the back metal, depending on the conditions for operation of the bearing. Alloys are in accordance with ISO 4381; materials are in accordance with ISO 4383. Guidance for the selection of pad surface layer materials is given in Annex A.3.2 Metall
19、ic materials3.2.1 Typical materialsThe chemical composition of some typical materials based on metal are given in Table 1.3.2.2 Tinbased whitemetalsTin-based whitemetals are used as general-purpose metallic materials. They are provided with linings by casting, in general.Whitemetals are characterize
20、d by good castability. However, attention should be paid to quality problems, such as bonding strength with the back metal, segregation and blow holes.To ensure appropriate strength/softness of a whitemetal alloy, the combination of Sb and Cu described in Table 1 is used in many applications.Lead-ba
21、sed whitemetals are rarely used because of their effects on the environment.3.2.3 Aluminium bearing alloysAluminium-based bearing alloys are used for high-speed operation under high-load and high-temperature conditions. Al-Sn alloys, i.e. alloys which are made by adding tin to aluminium, are the mos
22、t commonly used aluminium bearing alloys. To improve sliding characteristics at high speed, 40 % Sn-Al alloy is typically used.The pad of a bearing manufactured from such an alloy is formed from a bimetal strip consisting of an aluminium alloy, which is roll-bonded to carbon steel. The pad of a jour
23、nal bearing made from such an alloy can have INTERNATIONAL STANDARD ISO 14287:2012(E) ISO 2012 All rights reserved 1BS ISO 14287:2012ISO 14287:2012(E)uneven alloy thickness along the slide direction because it is formed by bending; it is possible to correct the thickness to make it even.3.2.4 Leadbr
24、onze bearing alloysLead-bronze bearing alloys are used under operating conditions equivalent to those for aluminium-bearing alloys or under higher load and higher temperature conditions. However, lead-bronze bearing alloys have limited uses. Lead-bronze bearing alloys are high in hardness; they norm
25、ally require surface hardening (quench hardening, etc.) on the sliding surfaces of mating parts.The pad of a bearing manufactured from such an alloy, as in the case of an aluminium bearing alloy, is typically formed from a bimetal strip. Although it is a rare case, it can take the form of a copper a
26、lloy (solid or cast) with a steel backing.Table 1 Chemical composition of metal materialsChemical elementChemical compositionmass fraction, %Tinbased whitemetals Aluminium bearing alloysLeadbronze bearing alloysSn Remainder 35 to 42 8 to 12Al 0,01 Remainder Cu 3 to 5 0,7 to 1,3 RemainderSb 8 to 10 0
27、,5Pb 0,5 7 to 13Zn 0,01 0,75Ni 0,15 0,5Si 0,3 Fe 0,08 0,7 0,35Bi 0,08 As 0,01 3.3 Polymer materialsBearings with pads having polymer layers on their sliding surfaces, which are characterized by polymer-specific tribological characteristics, are in use.Polyether-etherketone (PEEK) and polytetrafluoro
28、-ethylene (PTFE) polymer materials are available. Bearings composed of such materials are provided with special measures to allow for bonding to the back metal. A porous metal layer is used as the bonding interface layer and its voids are impregnated with a polymer layer material to form a sliding s
29、urface layer. Thus, the metal interface layer is joined with the back metal. PEEK polymer materials contain some PTFE in order to improve sliding characteristics.The chemical composition of some typical polymer materials are given in Table 2.Two types of electrical conductivities are provided: condu
30、ctive and non-conductive, which are determined depending on the elements added. Non-conductive polymer materials have the advantage of preventing electro-erosion without an additional insulator.2 ISO 2012 All rights reservedBS ISO 14287:2012ISO 14287:2012(E)Table 2 Chemical composition of polymer ma
31、terialsChemical elementChemical composition mass fraction, %PEEK material PTFE materialPEEK Remainder Remainder PTFE 1 to 3 8 to 12 RemainderCF 27 to 33 10 to 20MoS2 4 to 6CF carbon fibreMoS2molybdenum disulfide3.4 Back metal materialsLow-carbon steels containing approximately 0,10 % C to 0,35 % C a
32、re often used as back metal materials. The carbon content of a back metal material is typically determined using a combination of a surface layer bearing material and a bonding process.In the case of bearings operating under high-speed and high-temperature conditions, a copper alloy may be used as a
33、 back metal, although it is a rare case. Back metals of the copper alloy are usually Cu-Cr (copper chromium) alloy, which are expected to decrease pad temperature by approximately 10 C to 20 C because of their excellent thermal conductivity.3.5 Pivot materialsPivots are subjected to concentrated loa
34、ds and may be separated from the pads. Pivot materials are very hard and are fixed to pads. A typical example of a pivot is a flat, cylindrical one. It is press-fitted on to the back surface of a pad and is then secured by caulking. High-carbon chromium bearing steels containing approximately 0,95 %
35、 C to 1,10 % C are commonly used pivot material and thermally treated, in general.The shape of a pivot is designed to have different curvatures with respect to the circumferential and axial directions to allow the pad to tilt freely in the circumferential and axial directions.Pivots may be installed
36、 on the bearing casing side on their designs. ISO 2012 All rights reserved 3BS ISO 14287:2012ISO 14287:2012(E)Annex A (informative) Guidance on properties and selection of materialsA.1 Additional information on metallic materialsWhitemetals are excellent in castability as well as in conformability,
37、seizure resistance, embeddability and so on. Therefore, they are often used as versatile materials in thrust and journal bearings.Gravity casting and centrifugal casting are used to produce thrust pads and journal pads, respectively. Centrifugal casting produces fine structures with high bonding pro
38、perty.Whitemetals are limited in strength and high-temperature characteristics; the maximum permissible sliding surface temperature of whitemetals is approximately 120 C to 130 C.Bearings are subjected to high temperatures due to the development of high-speed and high-performance rotating machinery.
39、 Some of them employ aluminium alloy. Aluminium bearings can be used at about 25 C to 30 C higher temperatures than the whitemetal bearings.Aluminium bearings are formed from bimetal strip materials by machining them. The size of a bearing depends on the size of the bimetal strip and the capability
40、of the machine which processes the bearing. In general, small or medium size bearings are produced.Lead bronze bearings can be used at about 30 C to 40 C higher temperatures than the whitemetal bearings. However, they are high in hardness and sensitive to seizure. Their uses are thought to be limite
41、d to special applications utilizing the high-temperature characteristics of copper materials.A.2 Additional information on polymer materialsIn general, PEEK and PTFE polymer materials are superior to metal materials in terms of tribological characteristics. They are excellent in low-friction coeffic
42、ient and seizure resistance. In recent years, PEEK and PTFE polymer materials utilizing those characteristics have been developed. Such materials are used to produce pads for both thrust and journal bearings.Although a thermal conductivity of polymer materials is small, this is beneficial to reduce
43、a thermal distortion of the bearing surface. PEEK materials have excellent load-carrying capabilities and little wear/creep deformation under high surface pressure conditions. In addition, they can be used at approximately 75 C higher temperatures than the whitemetal materials. Owing to the excellen
44、t load durability and low friction, the size of bearings can be reduced and the overall size of equipment can accordingly be reduced.The results of start-up friction coefficient experiment under vertical static load conditions are shown in Figure A.1. In some cases, the use of jacking oil for large-
45、size vertical thrust bearings can be eliminated by applying the PEEK thrust pads. The size of PEEK sheet materials which can be produced vary according to the capability of the equipment used. Sheet materials that measure approximately 1 000 mm 600 mm are available.4 ISO 2012 All rights reservedBS I
46、SO 14287:2012ISO 14287:2012(E)0 1 2 3 4 5 0,050,10,150,20,2512XYKeyX specific bearing load (MPa)Y friction coefficient at start-up 1 whitemetal 2 PEEK Test bearing size: tilting pad thrust bearing with eight pads under test; pad outside diameter of 457 mm and pad inside diameter of 246 mm.Figure A.1
47、 Example of start-up coefficient of friction on the vertical static load test machineA.3 Operation rangeA general chart, giving the operation range for metallic materials and polymer materials, is shown in Figure A.2.Load-carryingcapabilityGood Poor High-temperature property Poor Good Conformability
48、 Whitemetal AluminiumlPolymer Operating temperature (C)50 0 100 150 200 CopperFigure A.2 General chart concerning the operation range for metallic materials and polymer materials ISO 2012 All rights reserved 5BS ISO 14287:2012This page deliberately left blankBSI is the independent national body resp
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