Mechanical vibration - Balance quality requirements for rotors in a constant (rigid) state - Part 1: Specification and verification of balance tolerances
1 Scope
This part of GB/T 9239 gives specifications for rotors in a constant (rigid) state. It specifies:
a) balance tolerances;
b) the necessary number of correction planes;
c) methods for verifying the residual unbalance.
Recommendations are also given concerning the balance quality requirements for rotors in a constant (rigid) state, according to their machinery type and maximum service speed. These recommendations are based on worldwide experience.
This part of GB/T 9239 is also intended to facilitate the relationship between the manufacturer and user of rotating machines, by stating acceptance criteria for the verification of residual unbalances.
Detailed consideration of errors associated with balancing and verification of residual unbalance are given in GB/T 9239.2.
This part of GB/T 9239 does not cover rotors in a flexible state. The balance quality requirements for rotors in a flexible state are covered by GB/T 6557.
2 Normative References
The following normative documents contain provisions which, through reference in this text, constitute provisions of this standard. For dated references, subsequent amendments (excluding corrections), or revisions, of any of these publications do not apply to this standard. However parties to agreements based on this standard are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below. For undated references, the latest edition of the normative document referred to applies.
GB/T 9239.2 Mechanical Vibration - Balance Quality Requirements for Rotors in a Constant (Rigid) State - Part 2: Balance Errors (GB/T 9239.2-2006, ISO 1940-2: 1997, Mechanical Vibration - Balance Quality Requirements of Rigid Rotors - Part 2: Balance Errors, IDT)
ISO 1925: 2001 Mechanical vibration - Balancing - Vocabulary
3 Terms and Definitions
For the purposes of this part of GB/T 9239, the terms and definitions given in ISO 1925: 2001 apply. For the convenience of users, some of these definitions are cited below.
Note: some of these definitions are at present under review.
3.1
balancing
procedure by which the mass distribution of a rotor is checked and, if necessary, adjusted to ensure that the residual unbalance or the vibration of the journals and/or forces on the bearings at a frequency corresponding to service speed are within specified limits
[ISO 1925: 2001, definition 4.1]
3.2
unbalance
condition which exists in a rotor when vibration force or motion is imparted to its bearings as a result of centrifugal forces
[ISO 1925: 2001, definition 3.1]
Note: the term "unbalance" is used as synonym of "amount of unbalance" or "unbalance vector".
3.3
initial unbalance
unbalance of any kind that exists in the rotor before balancing
[ISO 1925: 2001, definition 3.11]
Foreword i
Introduction iii
1 Scope
2 Normative References
3 Terms and Definitions
4 Pertinent Aspects of Balancing
5 Similarity Considerations
6 Specification of Balance Tolerances
7 Allocation of Permissible Residual Unbalance to Tolerance Planes
8 Allocation of Balance Tolerances to Correction Planes
9 Assembled Rotors
10 Verification of Residual Unbalance
Annex A (Informative) Example of the Specification of Permissible Residual Unbalance Based on Balance Quality Grade G and Allocation to the Tolerance Planes
Annex B (Informative) Specification of Balance Tolerances Based on Bearing Force Limits
Annex C (Informative) Specification of Balance Tolerances Based on Vibration Limits
Annex D (Informative) Specification of Balance Tolerances Based on Established Experience
Annex E (Informative) Rules for Allocating Balance Tolerances from Tolerance Planes to Correction Planes
Bibliography
