1、October 2012 Translation by DIN-Sprachendienst.English price group 12No part of this translation may be reproduced without prior permission ofDIN Deutsches Institut fr Normung e. V., Berlin. Beuth Verlag GmbH, 10772 Berlin, Germany,has the exclusive right of sale for German Standards (DIN-Normen).IC
2、S 21.120.40!$l+“1917308www.din.deDDIN ISO 21940-14Mechanical vibration Rotor balancing Part 14: Procedures for assessing balance errors (ISO 21940-14:2012),English translation of DIN ISO 21940-14:2012-10Mechanische Schwingungen Auswuchten von Rotoren Teil 14: Verfahren zur Ermittlung von Abweichunge
3、n beim Auswuchten(ISO 21940-14:2012),Englische bersetzung von DIN ISO 21940-14:2012-10Vibrations mcaniques quilibrage des rotors Partie 14: Modes opratoires dvaluation des erreurs dquilibrage (ISO 21940-14:2012),Traduction anglaise de DIN ISO 21940-14:2012-10SupersedesDIN ISO 1940-2:1998-02www.beuth
4、.deDocument comprises pagesIn case of doubt, the German-language original shall be considered authoritative.2009.12 A comma is used as the decimal marker. Contents Page National foreword .3 National Annex NA (informative) Bibliography 4 Introduction .5 1 Scope 6 2 Normative references 6 3 Terms and
5、definitions .6 4 Balance error sources .6 4.1 General 6 4.2 Systematic errors.7 4.3 Randomly variable errors .7 4.4 Scalar errors .8 5 Error assessment 8 5.1 General 8 5.2 Errors caused by balancing equipment and instrumentation 8 5.3 Balance errors caused by component radial and axial runout .8 5.4
6、 Assessment of balancing operation errors 9 5.5 Experimental assessment of randomly variable errors 10 5.6 Experimental assessment of systematic errors 11 6 Combined error evaluation 11 7 Acceptance criteria . 12 Annex A (informative) Error examples, their identification and evaluation . 13 DIN ISO
7、21940-14:2012-10 2National foreword This standard has been prepared by Technical Committee ISO/TC 108 “Mechanical vibration, shock and condition monitoring”, Subcommittee SC 2 “Measurement and evaluation of mechanical vibration and shock as applied to machines, vehicles and structures” (Secretariat:
8、 DIN, Germany). The responsible German body involved in its preparation was the Normenausschuss Akustik, Lrmminderung und Schwingungstechnik im DIN und VDI (Acoustics, Noise Control and Vibration Engineering Standards Committee in DIN and VDI), Working Committee NA 001-03-06-01 (NALS/VDI C 6.1) Ausw
9、uchten und Auswuchtmaschinen. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. DIN shall not be held responsible for identifying any or all such patent rights. The DIN Standards corresponding to the International Standards referred
10、 to in this document are as follows: ISO 1925 DIN ISO 1925 ISO 1940-1 DIN ISO 1940-1 ISO 11342 DIN ISO 11342 ISO 21940-32 DIN ISO 21940-32 The German standards are listed in the National Annex NA. ISO 21940 consists of the following parts, under the general title Mechanical vibration Rotor balancing
11、: Part 1: Introduction1) Part 2: Vocabulary2) Part 11: Procedures and tolerances for rotors with rigid behaviour3) Part 12: Procedures and tolerances for rotors with flexible behaviour4) Part 13: Criteria and safeguards for the in-situ balancing of medium and large rotors5) Part 14: Procedures for a
12、ssessing balance errors6) Part 21: Description and evaluation of balancing machines7)1) Revision of ISO 19499:2007, Mechanical vibration Balancing Guidance on the use and application of balancing standards 2) Revision of ISO 1925:2001, Mechanical vibration Balancing Vocabulary 3) Revision of ISO 194
13、0-1:2003 + Cor.1:2005, Mechanical vibration Balance quality requirements for rotors in a constant (rigid) state Part 1: Specification and verification of balance tolerances 4) Revision of ISO 11342:1998 + Cor.1:2000, Mechanical vibration Methods and criteria for the mechanical balancing of flexible
14、rotors 5) Revision of ISO 20806:2009, Mechanical vibration Criteria and safeguards for the in-situ balancing of medium and large rotors 6) Revision of ISO 1940-2:1997, Mechanical vibration Balance quality requirements of rigid rotors Part 2: Balance errors 7) Revision of ISO 2953:1999, Mechanical vi
15、bration Balancing machines Description and evaluation 3 DIN ISO 21940-14:2012-10 Part 23: Enclosures and other protective measures for balancing machines8) Part 31: Susceptibility and sensitivity of machines to unbalance9) Part 32: Shaft and fitment key convention10)Amendments This standard differs
16、from DIN ISO 1940-2:1998-02 as follows: a) the number of the standard has been changed; b) the scope has been extended to include rotors with flexible behaviour; c) data used to check the influence coefficient method have been deleted; d) the standard has been editorially revised and updated. Previo
17、us editions DIN ISO 1940-2: 1998-02 National Annex NA (informative) Bibliography DIN ISO 1925, Mechanical vibration Balancing Vocabulary DIN ISO 1940-1, Mechanical vibration Balance quality requirements for rotors in a constant (rigid) state Part 1: Specification and verification of balance toleranc
18、es DIN ISO 11342, Mechanical vibration Methods and criteria for the mechanical balancing of flexible rotors DIN ISO 21940-32, Mechanical vibration Rotor balancing Part 32: Shaft and fitment key convention 8) Revision of ISO 7475:2002, Mechanical vibration Balancing machines Enclosures and other prot
19、ective measures for the measuring station 9) Revision of ISO 10814:1996, Mechanical vibration Susceptibility and sensitivity of machines to unbalance 10) Revision of ISO 8821:1989, Mechanical vibration Balancing Shaft and fitment key convention DIN ISO 21940-14:2012-10 4 IntroductionThe balance qual
20、ity of a rotor is assessed in accordance with the requirements of ISO 1940-1 or ISO 11342 by measurements taken on the rotor. These measurements might contain errors which can originate from a number of sources. Where those errors are significant, they should be taken into account when defining the
21、required balance quality of the rotor.ISO 1940-1 and ISO 11342 do not consider in detail balance errors or, more importantly, the assessment of balance errors. Therefore this part of ISO 21940 gives examples of typical errors that can occur and provides recommended procedures for their evaluation.5
22、DIN ISO 21940-14:2012-10 Mechanical vibration Rotor balancing Part 14: Procedures for assessing balance errors 1 ScopeThis part of ISO 21940 specifies the requirements for the following:a) identifying errors in the unbalance measuring process of a rotor;b) assessing the identified errors;c) taking t
23、he errors into account.This part of ISO 21940 specifies balance acceptance criteria, in terms of residual unbalance, for both directly after balancing and for a subsequent check of the balance quality by the user.For the main typical errors, this part of ISO 21940 lists methods for their reduction i
24、n an informative annex.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 the referenced document (including any amendments) applies.ISO 1
25、925, Mechanical vibration Balancing Vocabulary11)ISO 1940-1, Mechanical vibration Balance quality requirements for rotors in a constant (rigid) state Part 1: Specification and verification of balance tolerances12)ISO 11342, Mechanical vibration Methods and criteria for the mechanical balancing of fl
26、exible rotors13)ISO 21940-21, Mechanical vibration Rotor balancing Part 21: Description and evaluation of balancing machines3 Terms and definitionsFor the purposes of this document, the terms and definitions given in ISO 1925 apply.4 Balance error sources4.1 GeneralBalancing machine balance errors c
27、an be classified into:a) systematic errors, in which the magnitude and angle can be evaluated either by calculation or measurement;b) randomly variable errors, in which the magnitude and angle vary in an unpredictable manner over a number of measurements carried out under the same conditions;11) To
28、become ISO 21940-2 when revised.12) To become ISO 21940-11 when revised.13) To become ISO 21940-12 when revised.6 DIN ISO 21940-14:2012-10 c) scalar errors, in which the maximum magnitude can be evaluated or estimated, but its angle is indeterminate.Depending on the manufacturing processes used, the
29、 same error can be placed in one or more categories.Examples of error sources which may occur are listed in 4.2, 4.3, and 4.4.Some of these errors are discussed in greater detail in Annex A.4.2 Systematic errorsExamples of balancing machine systematic error sources are:a) inherent unbalance in the d
30、rive shaft;b) inherent unbalance in the mandrel;c) radial and axial runout of the drive element on the rotor shaft axis;d) radial and axial runout in the fit between the component to be balanced or in the balancing machine mandrel (see 5.3);e) lack of concentricity between the journals and support s
31、urfaces used for balancing;f) radial and axial runout of rolling element bearings which are not the service bearings and which are used to support the rotor;g) radial and axial runout of rotating races (and their tracks) of rolling element service bearings fitted after balancing;h) unbalance due to
32、keys and keyways;i) residual magnetism in the rotor or mandrel;j) reassembly errors;k) balancing equipment and instrumentation errors;l) differences between service shaft and balancing mandrel diameters;m) universal joint defects;n) temporary bend in the rotor during balancing;o) permanent bend in t
33、he rotor after balancing.4.3 Randomly variable errorsExamples of balancing machine randomly variable error sources are:a) loose parts;b) entrapped liquids or solids;c) distortion caused by thermal effects;d) windage effects;e) use of a loose coupling as a drive element;f) transient bend in the horiz
34、ontal rotor caused by gravitational effects when the rotor is stationary.7 DIN ISO 21940-14:2012-10 4.4 Scalar errorsExamples of balancing machine scalar error sources are:a) changes in clearance at interfaces that are to be disassembled after the balancing process;b) excessive clearance in universa
35、l joints;c) excessive clearance on the mandrel or shaft;d) design and manufacturing tolerances;e) runout of the balancing machine support rollers if their diameters and the rotor journal diameter are the same, nearly the same or have an integer ratio.5 Error assessment5.1 GeneralIn some cases, rotor
36、s are in balance by design, are uniform in material and are machined to such narrow tolerances that they do not need to be balanced after manufacture. Where rotor initial unbalance exceeds the permitted values given in ISO 1940-1 or ISO 11342, the rotor should be balanced.5.2 Errors caused by balanc
37、ing equipment and instrumentationBalance errors caused by balancing equipment and instrumentation can increase with the magnitude of the unbalance present. By considering unbalance causes during the design stage, some error sources can be completely eliminated (e.g. by combining several parts into o
38、ne) or reduced (e.g. by specifying decreased tolerances). It is necessary to weigh the cost due to tighter specified tolerances against the benefit of decreased unbalance. Where the causes of unbalance cannot be eliminated or reduced to negligible levels, they should be mathematically evaluated.5.3
39、Balance errors caused by component radial and axial runoutWhen a perfectly balanced rotor component is mounted eccentrically to the rotor shaft axis, the resulting static unbalance, Us, of the component, in gmm, is given by Formula (1):Us= me (1)wherem is the mass of the component, in g;e is the ecc
40、entricity of the rotor component relative to the rotor shaft axis, in mm.NOTE The mass can be stated in kg, the eccentricity in m, but the static unbalance remains in units of gmm.The static unbalance of the component creates an identical static unbalance of the assembled rotor. An additional moment
41、 unbalance results if the component is mounted eccentrically in a plane other than that of the centre of mass. The further the plane distance is from the centre of mass, the larger the moment unbalance.If a perfectly balanced component is mounted concentrically, but with its principal axis of inerti
42、a inclined to the rotor shaft axis, a moment unbalance results; see Figure 1.8 DIN ISO 21940-14:2012-10 For a small inclination angle, , between the two axes, the resulting moment unbalance. Pr, in gmm2, is approximately equal to the difference between the moments of inertia about the component x- a
43、nd z-axes, multiplied by the angle, , in radians; see Formula (2):Pr (Ix- Iz) (2)whereIxis the moment of inertia about the transverse x-axis through the component centre of mass, in gmm2;Izis the moment of inertia about the principal z-axis of the component, in gmm2; is the small angle between the c
44、omponent principal axis of inertia and the rotor shaft axis, in radians.Formula (2) is valid only if the component is symmetric about its rotational axis and is therefore particularly applicable to the balancing of disks on arbors.The effects of radial runout and axial runout of a component mounted
45、on the rotor can be calculated separately.For rotors with rigid behaviour, the separate unbalance components can be allocated to the bearing or correction planes and then combined vectorially.For rotors with flexible behaviour, a rigid balance quality might be maintained, but accumulated axial disk
46、runout errors (often described as skew) can lead to significant vibration due to the moment unbalance generated by the skewed disk(s).Key1 rotor plane, perpendicular to the rotor shaft axis x component transverse axis2 component plane y component transverse axisX rotor shaft transverse axis z compon
47、ent principal axisY rotor shaft transverse axisangle between the component principal axis of inertia and the rotor shaft axisZ rotor shaft axisFigure 1 Coordinates of the rotor shaft and component axes, showing a component inclined to the rotor shaft axis5.4 Assessment of balancing operation errorsT
48、he purpose of balancing is to produce rotors that are within specified limits of residual unbalance or vibration. To ensure that the set limits have been met, errors need to be controlled and taken into account.9 DIN ISO 21940-14:2012-10 When a balancing machine is used, various error sources exist, for example:a) the type of rotor to be balanced;b) the tooling used to support or drive the rotor;c) the balancing machine support structure (e.g. machine
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