Techs For Field Balance
Various types of machines used in the balance of more methods, such as single-plane balance (aka static balance) often use the balance frame, double-plane balance (aka dynamic balance) using a variety of dynamic balance testing machine. Static balance accuracy is too low and the duration is too long. Dynamic balance testing machine can do better balance to the rotor itself, but the rotor size difference has magnificent effect, which often need different size of the dynamic balancing machine and the test still need that the rotor is removed from the machine, which is obviously neither economical nor laborious (such as overhaul after the turbine rotor). In particular, the balancing machine cannot eliminate the vibration caused by the assembly or other follower components. Balancing the rotor under normal installation and operation conditions is often referred to as "field balance". The balance on the field can not only reduce the amount of labor that can be dismantled with the rotor, but also inquiry the large dynamic balancing machine. At the same time, the state of the test is the same as the actual working condition. It is helpful to improve the accuracy of the unbalanced measurement and reduce the vibration of the system. International standard ISOl940 a 1973 (E) "rigid body rotation of the balance of precision" provides that the balance accuracy of G=0.4 precision rotor, must use the field balance, otherwise the balance is meaningless.
Modern dynamic balancing technology developed at the beginning of this century with the advent of steam turbines. With the rapid development of industrial production, rotating machinery gradually to the precision, large-scale, high-speed direction, the mechanical vibration problem is more and more prominent. Mechanical vibration of the machine itself and its surrounding environment will bring a series of hazards. Although the causes of vibration are diverse, it is generally accepted that "imbalance" is the main reason. According to statistics, about 50% of the mechanical vibration is caused by the imbalance force. Therefore, it is necessary to change the mass of the moving part of the rotating machine and reduce the unbalanced force, that is, to balance the rotor.
There are many factors that cause the rotor imbalance, such as the no uniformity of the rotor material, the imbalance of the coupling, the asymmetry of the keyway, the error of the rotor processing, the corrosion, wear and thermal deformation of the rotor during the movement. The imbalance caused by these factors is generally random and cannot be calculated and needs to be measured and corrected by gravity test (static balance) and rotation test (dynamic balance) to reduce it to the allowable range. The most widely used balance method is the process balance method and the whole machine on-site dynamic balance method. As an important branch of the whole field dynamic balancing technology, online dynamic balancing technology is also in a vigorous development, very promising. Because the process balance method is the earliest one of the classic dynamic balance method.
Machine balancing technology is to solve the process of balance technology in the existing problems.