1、 Reference number ISO 6621-2:2003(E) ISO 2003INTERNATIONAL STANDARD ISO 6621-2 Second edition 2003-11-15 Internal combustion engines Piston rings Part 2: Inspection measuring principles Moteurs combustion interne Segments de piston Partie 2: Principes de mesure pour inspection ISO 6621-2:2003(E) PDF
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6、y of the requester. ISO copyright office Case postale 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Published in Switzerland ii ISO 2003 All rights reservedISO 6621-2:2003(E) ISO 2003 All rights reserved iiiContents Page Foreword iv Introdu
7、ction v 1 Scope 1 2 Normative references . 1 3 Terms and definitions. 1 4 Measuring principles 1 4.1 General measuring conditions 1 4.2 Ring characteristics and their measurement. 2 4.2.1 Ring width(in millimetres) 2 4.2.2 Radial wall thickness, a 1(in millimetres) 4 4.2.3 Total free gap m, p(in mil
8、limetres) . 5 4.2.4 Closed gap, s 1(in millimetres) 6 4.2.5 Tangential force, F t(in newtons). 7 4.2.6 Diametral force, F d(in newtons) 13 4.2.7 Ovality, U (in millimetres) . 13 4.2.8 Point deflection, W (in millimetres) 14 4.2.9 Light tightness (percentage of ring circumference) 14 4.2.10 Taper on
9、peripheral surface (in micrometres or degrees) . 15 4.2.11 Barrel on peripheral surface, t 2 , t 3(in millimetres) 16 4.2.12 Land width, h 4 , h 5(in millimetres) 18 4.2.13 Land offset (in millimetres) 18 4.2.14 Plating/coating thickness (in millimetres) 19 4.2.15 Nitrided case depth (in millimetres
10、) 20 4.2.16 Keystone angle (in degrees) . 21 4.2.17 Obliqueness (in degrees) 24 4.2.18 Twist (in millimetres). 24 4.2.19 Unevenness T er , T eu25 4.2.20 Helix (axial displacement of gap ends) (in millimetres) 27 4.2.21 Free flatness (in millimetres) 27 4.2.22 Surface roughness Ra, Rz (in micrometres
11、) 28 Bibliography . 29 ISO 6621-2:2003(E) iv ISO 2003 All rights reservedForeword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO tec
12、hnical 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. ISO collaborates closel
13、y 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 International Standards. Draft
14、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 elements of this documen
15、t may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO 6621-2 was prepared by Technical Committee ISO/TC 22, Road vehicles. This second edition cancels and replaces the first edition (ISO 6621-2:1984), which has been technically re
16、vised. ISO 6621 consists of the following parts, under the general title Internal combustion engines Piston rings: Part 1: Vocabulary Part 2: Inspection measuring principles Part 3: Material specifications Part 4: General specifications Part 5: Quality requirements ISO 6621-2:2003(E) ISO 2003 All ri
17、ghts reserved vIntroduction ISO 6621 is one of a series of International Standards dealing with piston rings for reciprocating internal combustion engines. Others are ISO 6622 4, 5 , ISO 6623 6 , ISO 6624 7, 8, 9, 10 , ISO 6625 11 , ISO 6626 12, 13and ISO 662714 . The common features and dimensional
18、 tables presented in this part of ISO 6621 constitute a broad range of variables, and the designer selecting a particular ring type must bear in mind the conditions under which it will be required to operate. It is also essential that the designer refer to the specifications and requirements of ISO
19、6621-3 and ISO 6621-4 before completing a selection. INTERNATIONAL STANDARD ISO 6621-2:2003(E) ISO 2003 All rights reserved 1Internal combustion engines Piston rings Part 2: Inspection measuring principles 1 Scope This part of ISO 6621 specifies the principles to be used in the measuring for inspect
20、ion purposes of piston rings for both reciprocating internal combustion engines and compressors working under analogous conditions. It is applicable to all such rings of a diameter u 200 mm. 2 Normative references The following referenced documents are indispensable for the application of this docum
21、ent. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 4287-1:1984, Surface roughness Terminology Part 1: Surface and its parameters ISO 4287:1997, Geometrical Product Specifications (GP
22、S) Surface texture: Profile method Terms, definitions and surface texture parameters ISO 6507-3, Metallic materials Vickers hardness test Part 3: Calibration of reference blocks ISO 6621-1, Internal combustion engines Piston rings Part 1: Vocabulary 3 Terms and definitions For the purposes of this d
23、ocument, the terms and definitions given in ISO 6621-1 and in 4.2 apply. 4 Measuring principles 4.1 General measuring conditions The following general conditions are applicable to all measuring principles, unless otherwise specified. a) The ring shall rest on the reference plane in the free or open
24、condition. No additional force shall be applied to load the ring on the reference plane, except when measuring unevenness in accordance with 4.2.19 or helix in accordance with 4.2.20. b) Certain measurements are made with the ring in the closed condition in a gauge of nominal cylinder bore diameter.
25、 When orientated rings are measured in this way, they shall be so placed that the top side of the ring is towards the reference plane. c) Measurements shall be made using instruments with a resolution not exceeding 10 % of the tolerance of the dimension being measured. ISO 6621-2:2003(E) 2 ISO 2003
26、All rights reserved 4.2 Ring characteristics and their measurement Characteristic/Definition Measuring principle/method 4.2.1 Ring width(in millimetres) 4.2.1.1 Parallel-sided rings, h 1distance between the sides at any particular point perpendicular to the reference plane measured in millimetres (s
27、ee Figures 1 and 2) Measure with spherical measuring probes, each of radius 1,5 mm 0,05 mm, exerting a measuring force of approximately 1 N (see Figure 3). In the case of slotted oil rings, the measurement shall be made between the slots and not across them, i.e. across a solid portion of the ring c
28、ross section (see Figure 2). Figure 1 Figure 2 Figure 3 4.2.1.2 Keystone rings, half-keystone rings, h 3distance between the sides at a distance a 6from the peripheral surface (see Figure 4), or, alternatively, width controlled by a 6at a specified width h 3(see Figure 6) Method A This method determ
29、ines h 3for a specified value of a 6(see Figure 4). Figure 4 ISO 6621-2:2003(E) ISO 2003 All rights reserved 3Characteristic/Definition Measuring principle/method Measure with spherical measuring probes, each of radius 1,5 mm 0,05 mm, exerting a measuring force of approximately 1 N (see Figure 5). I
30、f the measuring equipment is set up with parallel gauges instead of keystone gauges, the use of spherical measuring probes will give rise to an error, as follows: for 6 keystone angle: 0,004 mm (ring types: T, TB, TBA, and TM); for 7 keystone angle: 0,012 mm (ring types: HK, and HKB); for 15 keyston
31、e angle: 0,026 mm (ring types: K, KB, KBA, and KM). To obtain the correct measured width of the keystone ring, the above values shall be deducted from the measured values. NOTE Values of a 6are given in ISO 6624-1 to ISO 6624-4. Dimensions in millimetresFigure 5 ISO 6621-2:2003(E) 4 ISO 2003 All rig
32、hts reserved Characteristic/Definition Measuring principle/method Method B This method determines a 6for a specified value of h 3(see Figure 4). Measure with a flat face probe exerting a measuring force of approximately 1 N. The ring shall be placed between two sharp edged (radius u 0,01 mm) circula
33、r discs which are spaced apart at the specified gauge width h 3(see Figure 6). NOTE Values of h 3are given in ISO 6624-1 to ISO 6624-4. Dimensions in millimetresFigure 6 4.2.2 Radial wall thickness, a 1(in millimetres) radial distance between the peripheral surface and the inside surface of the ring
34、 measured in millimetres (see Figure 7) a) Measure radially between a flat measuring surface on the peripheral surface and a special measuring surface with a radius of approximately 4 mm on the bore using a measuring force of 3 N to 10 N (see Figure 8). Figure 7 ISO 6621-2:2003(E) ISO 2003 All right
35、s reserved 5Characteristic/Definition Measuring principle/method Figure 8 b) Measure radially between cylindrical inserts or rollers of radius approximately 4 mm with a measuring force of 3 N to 10 N. The peripheral surface of the rollers shall be perpendicular to the reference plane. The length of
36、the rollers shall be greater than the axial ring width (see Figure 9). Figure 9 4.2.3 Total free gap m, p(in millimetres) chordal distance between the gap ends of the ring in a free unstressed state, measured at the centre line of the radial wall thickness measured in millimetres (see Figure 10); fo
37、r rings with an internal notch for a peg chordal distance marked as p in Figure 11 Measure with a steel rule to the nearest 0,25 mm. Optionally, this feature may be measured with callipers. Figure 10 ISO 6621-2:2003(E) 6 ISO 2003 All rights reserved Characteristic/Definition Measuring principle/meth
38、od Figure 11 4.2.4 Closed gap, s 1(in millimetres) distance between the gap ends of the ring measured at the narrowest point, which the ring would have when fitted in a gauge of nominal cylinder bore size (see Figure 12) NOTE The closed gap s 1is related to the nominal diameter d 1 . Measure in a bo
39、re gauge of nominal diameter using a wedge gauge or feeler gauges and using a measuring force of approximately 1 N (see Figure 12). The diameter of the bore gauge shall comply with 1 0,001 1 0 d d +Correction shall be made for any deviation of thebore gauge from the nominal ring diameter. Figure 12
40、ISO 6621-2:2003(E) ISO 2003 All rights reserved 7Characteristic/Definition Measuring principle/method 4.2.5 Tangential force, F t(in newtons) 4.2.5.1 Single-piece rings (not recommended for rings d 1 50 mm see 4.2.6.) force necessary to maintain the ring at the closed gap condition by means of a tan
41、gential pull on the ends of a circumferential metal tape or hoop (see Figures 13 and 14) Tape method (see Figure 13) Carry the encircling steel tape of thickness 0,08 mm to 0,10 mm around 10 mm diameter rollers set 20 mm apart (see Figure 13). In tightening the tape, close the ring to the point wher
42、e the gap ends touch and then open to the closed-gap dimension previously measured. Then read off the ring force from the precision measuring scale. The gap of the ring shall be symmetrically disposed between the rollers. An alternative method to set up the tangential loading of the force measuring
43、instrument is using a solid disc of nominal bore diameter 0,005 mm to set up the length of the tape. Insert the gauge disc into the tape and adjust the tape length until the specified mean limit tangential force is indicated. Key 1 measuring scale 2 diameter of roller = 10 mm Figure 13 ISO 6621-2:20
44、03(E) 8 ISO 2003 All rights reserved Characteristic/Definition Measuring principle/method Hoop method (see Figure 14) Place the ring in a correctly sized hoop with its gap aligned to the gap of the hoop. Then close the hoop in a precision loading machine until the loading pins are at a predetermined
45、 distance apart at which point the hoop is precisely at the cylinder bore diameter appropriate to the ring (see Figure 14). Read the force from the display. Key 1 measuring scale aLoading-pin spacing to suit machine. Figure 14 Encircling tape method A steel tape 0,08 mm to 0,1 mm in thickness encirc
46、les the ring crossing at the gap (see Figure 13). The tape is tightened until the ring is closed to the closed gap previously measured. The ring force is then read off the precision measuring scale. NOTE No vibration when measuring single-piece rings according to the three methods. ISO 6621-2:2003(E
47、) ISO 2003 All rights reserved 9Characteristic/Definition Measuring principle/method 4.2.5.2 Multi-piece rings force which is necessary to maintain the ring at the closed gap condition by means of a tangential pull on the ends of a circumferential metal tape or hoop (see Figure 15) NOTE Vibration is
48、 used to reduce friction during or prior to measurement. For the measurement of coil-spring-loaded rings or similar rings where the spring is supported in the bore of the ring, the gap of the spring shall be positioned at 180 to the gap of the ring. For the measurement of expander/segment oil-contro
49、l rings, the ring assembly shall be mounted in a carrier simulating the piston-ring groove. The gap of the spring element shall be placed at 180 to the gap of the rails, both of which shall be in line. Choice of ring carrier type (see Table 1) to be decided between manufacturer and client. For the measurement of a ring provided with a wavy spring, or other spring which is groove-root supported, the ring assembly shall be mounted in a carrier simulati
