ISO 1940 Mechanical vibration – Balance quality requirements of rigid rotors – Part 1:Determination of permissible residual unbalance

ISO 1940

 Mechanical vibration – Balance quality requirements of rigid rotors – Part 1: Determination of permissible residual unbalance (1986 edition)

This part of IS0 1949 gives recommendations for determining unbalance and for specifying related quality requirements of rigid rotors; it specifies

1. A representation of unbalance in one or two planes;
2. Methods for determining permissible residual unbalance;
3. Methods for allocating it to the correction planes;
4. Methods for identifying the residual unbalance state of a rotor by measurement;
5. A summary of errors associated with the residual unbalance identification.

In table 1 and figure 2 recommendations are given, based on worldwide experience, concerning the balance quality requirements of rigid rotors, according to their type, mass and maximum service speed.

This part of IS0 1949 is also intended to facilitate the relations between manufacturer and user of machines. Terminology specified in this part of IS0 1940 may be used for establishing technical specifications. (For definitions, see IS0 1925.) Detailed consideration of errors associated with the determination of residual unbalance is not included in this part of IS0 1940 (IS0 1940/2 will deal with these errors). This part of IS0 1940 does not define permissible residual unbalances for flexible rotors; these are covered in IS0 5343. The methods for balancing are not described. The recommended balance quality grades are not intended to serve as acceptance specifications for any rotor group, but rather to give indications of how to avoid gross deficiencies as well as exaggerated or unattainable requirements; they may also serve as a basis for more involved investigations, for example, when a more exact determination of the required balance quality by measurement in the laboratory or in the field is necessary. If due regard is paid to the recommended limits, satisfactory running conditions can most probably be expected. However, there may be cases when deviations from these recommendations become necessary, e.g. because of unusual construction or geometry.

Contents:

National foreword
Committees responsible
Method
0 Introduction
1 Scope and field of application
2 References
3 Pertinent aspects of the balancing problem
4 Permissible unbalance related to rotor mass
5 Quality grades relating service speed and
permissible residual specific unbalance
6 Determination of balance quality requirements
7 Allocation of permissible residual unbalance to each
correction plane on the basis of Uper
8 Determination of the residual unbalances
9 Sources of errors in balancing
Annex
Example for the general method described in 7.3.3.1
for two-plane balancing
Tables
1 Balance quality grades for various groups of
representative rigid rotors
2 Typical examples of recommended deviations
Figures
1 Different representations of the same state of
unbalance of a rigid rotor
2 Maximum permissible residual specific unbalance
value corresponding to various balance quality
grades
3 Rotor dimensions to be used for simplified method
4 Rotor with overhung discs at both ends
5 Rotors with couple correction planes I and II at a
distance b less than one-third of the bearing span l
6 Rotor dimensions to be used for general method
calculations
7 Determination of the reponse of the permissible
residual unbalance to a trial mass
8 Test procedure for determining the residual
unbalance in one plane
9 Error sources in end-drive elements
10 Rotor dimensions

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