The balancing machine plant started to produce process tooling for helicopter turbine rotors

A leading Russian manufacturer in the field of development and delivery of balancing machines and vibration measuring equipment for enterprises of various industries, Scientific and Technical Centre "Balancing machines factory" in 2020 carried out great work on designing and manufacturing of special technological equipment for turbine rotors and axial compressor GTE TVZ-117 and BK 2500 installed on helicopters MI-8 and MI-24.

"Considering that apart from production of these engines at ODK - Klimov in St. Petersburg, repair of such turbines is performed at many repair plants both in Russia and in other countries where such helicopters are operated, high demand of aircraft production and repair enterprises for machines of this type is expected, as use of special balancing machines with technological tooling is the most important factor guaranteeing high quality during production and subsequent repair of engines," - the company explained.

About balancing rotors

In aircraft engine industry, quality balancing of rotors of turbines, compressors, as well as disks, couplings and other parts is of great importance. Zavod Balancing machines are therefore vital in the development of balancing machines for aircraft engine manufacturers and engine overhaulers.

Rotor balancing is a final stage in the production or repair of rotors, its main purpose is to assure low-vibration operation of rotor machines, thus guaranteeing a long operating life of rotors, bearings, seals and other rotor-mating parts.

Balancing machines for aircraft GTEs can be of the preresonance type (rigid) or of the resonance type (supple). The main requirement in balancing of rotors on machines of any type is to ensure high accuracy, which is mathematically evaluated in specific units of residual unbalance gmm, referred to 1 kg of rotor mass.

A high balancing accuracy is equivalent to a specific residual unbalance value of 0.05 mm/kg in each correction plane. Such balancing accuracy is achieved on the machines produced by the "Scientific and Technical Centre "Balancing machines factory".

"Precondition for achieving high accuracy on the machine is the obligatory observance of the production technology of the machine units at each stage of the production cycle, continuous control of all assembly operations. In the production of high-precision balancing machines, the company's quality department performs bench-mounted multi-channel vibration control of all major units of the balancing machine, which allows identifying the smallest deviations that may occur in the units during manufacturing and assembly", - explained in the company.

To perform machine balancing of aircraft GTE rotors, it is necessary to use special technological tooling, as due to the design features of rotors and technological requirements, most of the rotors cannot be placed without it on the machine. Design and production of tooling is often a rather labour-intensive process and requires rotor drawings.

Balancing bench

Development of a special stand for dynamic balancing of the propellers of turboprop engines is an important area of activity of the "STC Balancing machines plant" in the aircraft industry. The propeller installed on the aircraft propeller engine is the source of engine vibration excitation. Quality balancing of the propeller leads to reduction of engine vibration and increase of its reliability and durability. Previously, the problem of dynamic propeller balancing was not given proper attention, and propellers were balanced only statically, i.e. without eliminating the moment imbalance.

However, the requirements for propeller balancing are increasing every year due to periodic revisions by the International Civil Aviation Organisation (ICAO) of the permissible ground noise generated by aircraft. Performing dynamic propeller balancing helps to meet the growing requirements for vibration and noise reduction, but requires the creation of a special stand.

The issue of manufacturing such a stand began to be discussed in June 2017 at the working meeting of specialists of "NPP "AEROSILA" and "STC "Factory of balancing machines". The terms of reference for the stand manufacturing was developed jointly. Already in December 2018, the factory tests of the balancing stand designed and manufactured by STC "BalanceMash" were started at "SPE "Aerosila", and in March 2019, the act of commissioning was signed.

The stand has an original design that allows for quick and accurate installation and removal of the propeller, a modern measuring part that uses highly sensitive vibration sensors and a measuring unit with a large dynamic range, new software with deployed functionality has been developed for the control unit, allowing the operator to quickly perform the balancing of the propeller.

"The use of such stands at the enterprises, which produce and repair aircraft propellers in Russia and abroad, allows repeatedly improving the quality of balancing of propellers, reducing vibration and noise, repeatedly extend the service life when operating the propellers," - said the representative of the company.