The goal of rotor balancing is to reduce unbalance enough such that it can operate properly once installed on site. The farther apart these corrective planes are, the smaller, in general, may be the corrective weights. Basic principles of rigid and flexible rotor balancing are quite different. This measurement is not needed for balancing the rotor, but will be used later as a check on. In the past, balanclng was achieved only through flexlble shaft and rotor balancing techniques or fleld balancing of the turbomachlnery shafting. Balancing machines and systems according to din iso 19401. Rotating machinery rotor balancing lifetime reliability solutions. Active balancing and vibration control of rotating machinery. A drive motor is required, and possibly a vacuum system, depending on rotor. Application notes static and dynamic balancing of rigid. Field balancing techniques are also readily available for various. This explains why many engine builders have experimented with techniques such as overbalancing, and why theyre often topics of intense debate. That is, flexible rotor balancing procedures take into account rotor flexibility, while rigid rotor balancing procedures do not.
Piedmont chapter vibration institute training symposium 10. Balancing of rotating machinery vibration institute. The process of balancing a part without taking it out of the machine is called inplace balancing. Rotor balancing motor repair best practices youtube. Understanding the basics of balancing and measuring techniques. The control variable in davc techniques is a lateral force generated by a force actuator such as the magnetic. Teach special balancing techniques required on overhung rotors. Ogunoh4 1department of mechanical engineering, nnamdi azikiwe university pmb 5025awka, nigeria 2department of metallurgical and materials engineering, nnamdi azikiwe universityawka. Latham, new york prepared for lewis research center under contract nas318520. Balancing rigid rotors in the field reliable plant. The analysis of a smart jeffcott rotor with direct. For this reason the term center of gravity can be thought of as being the same as the center of mass. Balancing is the process of aligning a principal inertia axis with the geometric axis of rotation through the addition or removal of material. Balancing rigid rotors in the field bill hillman, ludeca, inc.
Rotor balancing is a type of analysis that compares the vibration profile with the rotation of a mechanical element to characterize inconsistent weight distribution around the diameter while calculating the amount and position of. Balancing techniques for highspeed flexible rotors ntrs nasa. Piedmont chapter vibration institute training symposium 10 may, 2012 field balancing of rotating. Balancing, rotor, vibration, phase angle, influence coefficient method i. The most important change is the introduction of reference planes for balance tolerances instead of using the correction planes as tolerance planes. An overview of active techniques has been provided by zhou and shi1. Pdf practical balancing of flexible rotors for power. A method of balancing an assembly of rotary parts of a gas turbine engine 10 comprising measuring at least one of the concentricity and parallelism of each component and considering globally all possible component stacking positions to generate an optimized stacking position for each component of the assembly to minimize assembly unbalance. For such cases, low speed balancing can satisfy all balancing requirements. The discussion in site and factory methods includes influence. Several techniques for flexible shaft and flexlble rotor balancing are readily avallable. The purpose of producing this handbook is to provide basic information and guidelines for the implementation of good shaft alignment for. Use handson demonstrations to teach how to properly balance a variety of machinery using both graphical methods and data collectors with balancing programs.
The most common lowspeed balancing standard that applies to turbines is iso 1940, but there are other balancing standards from api and the military. The methods employed in shop balancing can have a profound impact on the resulting balance condition of the rotor. In the balancing operation, rotor unbalance sensitivities interference coefficients are determined for a sampling of rotors and stored. This study introduced a novel liquid transfer active balancing system for the hollow rotors, and compensation mass was performed by balance. An applicational process for dynamic balancing of turbomachinery shafting vincent g. Rotor balancing crystal instruments leading innovation in.
Shop balancing methods the methods employed in shop balancing can have a profound impact on the resulting balance condition of the rotor. Facilities instructions, standards, and techniques volume 22. To investigate unbalance on a rigid rotor, a laboratory test was done on an unbalanced rigid rotor and both static and dynamic balancing procedures were performed on the rotor. Multiplane balancing of the rotor assembly may be done conveniently in a balancing fixture that simulates dynamically the actual environment in which the rotor will operate.
The need to balance a large rotating machine should be evaluated on an individual basis. Often by necessity, sometimes by preference, it may become necessary to balance a rotating machine or part under conditions where a phase measurement is either impossible or unavailable. This book is a practical account of such balancing techniques e. Flexible rotor a flexible rotor might be defined as a rotor which runs above a flexible rotor critical speed or within 25 percent below that speed with sufficient rotor deflection to alter rotor balance behavior.
Single and multiplane balancing of rotor in static and. The angles refer to the trial weight positions on the rotor relative to an arbitrary zero. Elevation view of a rotor having an imbalanced mass. According to their line of reasoning everyone should throw away their rigid body balancing machines and use the modal technique which they have developed. The objective was to apply the theory of rotor balancing, gain skills on rotor balancing and get to know how to operate the balancing machine. The survey present theory used in computational algorithms related to eigensystem realization. Dynamic balancing accommodates any cause for imbalance in the entire rotating system.
When balancing such a rotor in a balancing machine, the rotor may be mounted elastically in such a way that it is pivoted to oscillate about some chosen radial axis. This measurement is not needed for balancing the rotor, but will be used later as a check on calculations. Correction takes place by counterweights which are to be attached at the opposite side of the unbalance. Static and dynamic balancing using portable measuring equipment by john vaughan foreword 2 many people are needlessly appre hensive of performing their own dy namic balancing procedure.
The impact of shop balance technique is most important when the rotor is relatively flexible andor long as is common with most turbomachinery. Dynamic balancing of rotating machinery in the field. These generic titles refer to whether or not rotor flexibility is taken into account. Singleplane balancing handson exercises using a rotor kit, vector method, singleplane balancing. Pdf practical balancing of rotating machinery download. I he balancing procedure tor flexible rotors is more complicated, because of the elastic deflections of the rotor. Crankshaft balancing will always be a compromise, but to get a better handle on how to more effectively balance an engine, we will first outline the basics of the balancing process. Design of the production rotor balancing process begins with an analytical optimization process, usually best conducted during system. Vector techniques the process of determining the required balance weights and locations can be simplified by using. The discussion in site and factory methods includes influence coefficient, conventional software, no phase and frequency response methods to balance rotors.
To improve the balance condition of most high speed flexible rotors, the following. Rotating machinery rotor balancing the aim of rotor balancing is to achieve satisfactory running when installed on site. Aug 26, 2015 eeco can help you increase your motor life with proper rotor balancing. Dynamic balancing of rotating machinery experiment technical.
Dynamic balancing of rotating machinery experiment technical advisor. An31e application note vibrometra system balancing system vmbal measuring technique vmbal uses a relative measurement technique. Most simple rotors systems can be balanced by applying this technique iteratively. The survey present theory used in computational algorithms related to eigensystem realization algorithm era and. The answer is to balance the affected parts of the machine so that it operates smoothly and efficiently. Rigid and flexible balancing techniques as applied to a. Balancing of multistage pump using the coupling hub. Reducing unbalance reduces vibration and increases efficiency and life of the rotor and bearings. Understanding the basics of balancing and measuring. Ny nasa contractor report 2975 balancing techniques for highspeed flexible rotors a.
Aug 20, 2012 balancing a large impeller, for dewatering pump from a submarine dry dock located at pearl harbor, hawaii. The mass changes are done at a rotor radius of 300 mm. Scope for future work on online balancing has been identified. Ep2019185a2 method of balancing a gas turbine engine. Quality control systems for jet engine balancing michael schonfeld senior applications engineer. Rotor balancing methods and instrumentation springerlink. As a result, the component is subjected to one or more balancing steps. This paper suggests for a new look at flexible rotor balancing for online balancing techniques. Compressor rotor repairs as they pertain to the two styles of rotors, the builtup and the drum type version, are being examined by discussing manufacturing techniques and overspeed testing of impellers, their material of construction, attachment methods to the shaft, design problems, balancing procedures, and special difficulties. Having a good grasp of vibration analysis will help to ensure that the technician performs balancing only when the problem is unbalance. Dynamic balancing should not be a substitute for poor machining or other compromise manufacturing practices. Field balancing large rotating machinery fist 009 08022016 new release minor revisions approved 09162016. Rotor balancing methods may be separated into two categories.
A threemass test rotor with a flattened shaft was designed to evaluate the feasibility and problems of. Procedures and tolerances for rotors with rigid behaviour 1 scope this document establishes procedures and unbalance tolerances for balancing rotors with rigid behaviour. The decision has to be made about how to mount the rotor in the balancing machine. The other alternative is to mount the fan blade on the end of the shaft in an overhung configuration, with the fan blade outboard of both balancing machine pedestals. Pdf practical balancing of flexible rotors for power generation.
Rotating machinery rotor balancing lifetime reliability. It specifies a the magnitude of the permissible residual unbalance, b the necessary number of correction planes. Application notes static and dynamic balancing of rigid rotors. Single and multiplane balancing of rotor in static and dynamic. One of the most representative balancing method is the influence coefficient method icm, which. Further, future imbalance on the rotor is permanently rectified using this method. In the case of a flexible rotor, it also means that not more than an acceptable magnitude of deflection occurs in the. Details of the software products used to create this pdf file can be found in the general info relative to the file. Rotor balancing crystal instruments leading innovation. Various types of practical balancing techniques have been proposed 1732. The basics of balancing 202 balance technology inc. Inplace balanc ing eliminates costly, time consuming disassembly and pre1 vents the possibility of damaging the rotor during its removal, transportation to and from a balancing facility, and, finally, reinstallation in the machine. It means no more than an acceptable magnitude of vibration is caused by the unbalance remaining in the rotor.
Therefore, after working on rotor blades and in new wind turbines, the balancing grade should be checked and, if necessary, improved. Balancing machines types, classification, and methods. When a is the acceleration due to gravity, the resultant force is the weight of the body. Ep2019185a2 method of balancing a gas turbine engine rotor. Teach singleplane and twoplane field balancing techniques using a variety of todays data collectors.
Fist volume 22, field balancing large rotating machinery. Balancing procedure an overview sciencedirect topics. Practical balancing of flexible rotors for power generation. Becoming proficient at rotor balancing requires having good tools and being knowledgeable in their use. Active balancing and vibration control of rotating. The method used to produce a balanced roll with minimum deflection or whip over its operating speed range is a multiplane technique. Most simple rotorssystems can be balanced by applying this technique iteratively. Subcommittee sc 1, balancing, including balancing machines. A fundamental knowledge of balancing theory and balancing procedures is also critical for success. A practical guide to shaft alignment plant services. Twoplane balancing techniques basic influence coefficient and staticcouple methods, oneshot balancing, twoplane balancing, strategy, and procedures. A rigid rotor can be balanced by making cor rections in any two arbitrarily selected i rnr u i a.
Rotor balancing is a type of analysis that compares the vibration profile with the rotation of a mechanical element to characterize inconsistent weight distribution around the diameter while calculating the amount and position of the weight necessary to offset the net imbalance. In the manufacturing process, if proper care is taken to ensure that castings are sound and machining is concentric, then it follows that the two axis will coincide and the assembled rotor will be in a state of balance. This survey covers the computational algorithms as well as the physical concepts involved in balancing rotating equipment. A relatively new approach to the reduction of the vibration of rotating systems is to use piezoelectric patch sensors and actuators together with an active control device. The incremental rotor balancing procedure turbomachinery. This second edition cancels and replaces the first edition iso 19401.
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