Balancing Machines - Description and Evaluation Horizontal, Two-Plane, Soft-Bearing Type for Gas Turbine Rotors
|Publication Date:||1 December 2012|
This Aerospace recommended Practice (ARP) specifies the requirements of balancing machines that make them suitable for the subject class of work. It was developed for soft-bearing balancing machines but may also be used for hard-bearing machines until ARP4048 is issued of that type of machine.
Particular note should be taken that this ARP examines only the capability of a balancing machine to indicate the correct amount of dynamic or static/couple unbalance in specified proving rotors. Such rotors are commonly used for testing balancing machines to provide precisely controlled and comparable test results. Further tests of a particular machine may be necessary to assess the capability to balance rotors of different weights and configurations, rotors with outboard c.g. and /or correction planes, and those with disturbance causing features, such as rotors subject to blade scatter, windage, etc.
This ARP specifies dimensional and performance requirements in the following areas:
a. Machine capacity relating to weight and physical dimensions of the rotors that can be balanced
b. Accuracy of amount and angle indication
c. Sensitivity and linearity of amount indication
d. Ability to separate dynamic unbalance into two places or into static and couple unbalance
e. Balancing speed and direction of rotation
f. Drive requirements
g. Proving rotors, test masses, and storage containers
This ARP delineates the technical specifications for the rotating type of soft-bearing, two-place (i.e., dynamic) balancing machine used for measuring the amount and angle of unbalance in one or more than one plane in aircraft type turbine engine, accessory and missile rotors.
This document also delineates performance tests to be used to ensure conformance with the requirements in this ARP.
This document was prepared to describe dimensional and performance requirements for machines capable of balancing most rotors either now in service or to be put into service in the foreseeable future. This will enable both rotor and balancing machine manufacturers to standardize, avoiding the need for separate tooling to adapt a particular rotor to a variety of machines of one capacity range. It can also be used as a general specification by purchasers ("Users") in procuring suitable balancing machines from manufacturers ("Suppliers").
To make this ARP sufficiently flexible so that it can be adapted to a variety of applications (such as rotors to be balanced by the accessory and missile industries, where a wide range of balance tolerances are specified), the test procedures have been written in terms of A units rather than fixed physical values such as ounces, ounce-inches, or micro inches.