Papers by Keyword: Dynamic Balance

Abstract: The vibration of a generator in a power plant and the cause of rotor cracking wereanalyzed. The causes of generator rotor cracking were analyzed from the rotor raw material andheat treatment process. The results show that the brittleness and notch sensitivity of the rotormaterial are large due to the unreasonable heat treatment process of the rotor. When the stress isconcentrated, a cracking accident occurs. The generator rotor was returned to the manufacturingcompany for operation. At 3000 r•min-1, the generator's overhanging end vibrated greatly, and thefault was successfully eliminated by the dynamic balance test.

Abstract: Aiming at the dynamic unbalance problem of high speed motorized spindle, an online dynamic balance detection method based on Fourier transform, polynomial curve fitting and Hooke's law is proposed, at the same time, based on virtual instrument LabVIEW software platform, programming deal with the vibration spectrum image of the motorized spindle. Combined with the detection method, output signal of the size, displacement and vector direction of unbalance force of the motorized spindle are obtained, the output signal would be transmit to dynamic balancing device to complete regulation of high speed motorized spindle online dynamic balance and achieve the real-time monitoring, analysis and timely adjustment of dynamic balance of high speed motorized spindle by using the programming of virtual instrument. We verified detection method by the experiment of online dynamic balance adjustment of the motorized spindle. Detection method of dynamic balance of motorized spindle based on LabVIEW can intuitively test vibration characteristics, the accurate detection of online dynamic balance is helpful to improve the rotation precision of the high speed spindle and realize high quality parts processing.Key words: Motorized spindle; the dynamic balance; Online detection; LabVIEW

Abstract: Steam turbine generator unit, water pump and other high speed revolution symmetric flexible rotor were regarded as research objects in this paper. According to variation characteristic of rotor shaft in rigid and flexible working mode, nine-reel high pressure water pump rotor was analyzed. The former four-order intrinsic frequency of flexible rotor was obtained by modal analysis and harmonic response analysis. The methods of reaction force response and unbalance response were been studied after first order and second order resonance region eliminating in different modes of simple harmonic exciting force. Based on above theoretical research results, trapezoid counterweight method was proposed for dynamic balance of flexible rotor. This method solved problem that rigid dynamic balance of low speed rotor was destroyed after first order and second order resonance region counter weight in dynamic balance of flexible rotor. The dynamic balancing techniques of flexible rotor could be improved the qualities of rotor and its relative products by this method, eliminating the vibration of unbalance mass of products radically.

Abstract: With the development of power electronic devices, the market demand for acid etched wafers of monocrystalline silicon, which has good surface properties and minimum surface roughness, increases rapidly. But there has been rarely report about the impact of acid etching process on the wafer surface roughness. This paper studied the surface roughness of the wafer, which was etched by mixture of HNO₃, HF and HAC. The results showed that the surface roughness became smaller with the increase of wafer remove amount, while the roughness became worse with the service life extension of the acid; however, fluid infusion discharge method could be adopted in the etching process so that the etching acid system could achieve a relatively balanced state and wafer roughness became stabilized. The process mechanism was studied and analyzed in this investigation.

Abstract: Silicon is the essential element to phytoplankton, determining the growth of phytoplankton. Phytoplankton is the basis of the marine food chain, as well as phytoplankton has tremendous capacity to absorb carbon. Phytoplankton and human determine the change of atmospheric carbon collectively, so the earth system is able to maintain the dynamic balance of the emission of anthropic carbon and the absorption of carbon by phytoplankton. This paper analyzed the effects of Silicon to the growth of phytoplankton, the absorption of CO₂ by phytoplankton, the biogeochemical process of silicon, and revealed the effects of silicon to the change of phytoplankton growth and atmospheric carbon.

Abstract: This paper proposes a method of balancing the shaking force of a crank-rocker mechanism which rotates at a constant angular speed with zero-unbalanced angle. In this approach, the kinematic synthesis and dynamic behavior of the mechanism are combined. The method is realized by modeling the mass of the connecting rod to represent two concentrated masses placed at the crank and rocker pins. The shaking forces balancing are done by adding counterweight masses to the crank and the rocker. The verification and numerical computation of the proposed balancing technique were carried out using ADAMS Software. The results showed that the sum of all the resultant forces was completely eliminated for the newly-balanced crank rocker mechanism.

Abstract: MapReduce is one of the core framework of Hadoop, it’s computing performance has been widely concerned and researched. In heterogeneous environment, unreasonable map task assignments and inefficient resource utilization lead to multiple backup tasks and the job total execution time is poor.For these problems, this paper proposes a new map task assignment strategy, which is map task dynamic balancing strategy based on file label. The strategy marks on job according to the different types, estimates node computing capabilities and historical processing efficiency of each label task, ensures map task which was assigned can execute successfully. Experiments show that, the strategy can effectively reduce number of backup tasks in map phase, and to some extent optimize the total execution time of the job.

Abstract: Firstly, according to the structure characteristics of precision centrifuge, the mathematical model of its dynamic balancing system was set up, and the dynamic balancing scheme of double test surfaces, double emendation surfaces were established. Then the dynamic balance system controller of precision centrifuge was designed. Simulation results show that the controller designed can completely meet the requirements of precision centrifuge dynamic balance control system.

Abstract: crankshaft is one of the most important parts and crankshaft fatigue fracture is a major failure. In order to alert fatigue fracture of crankshaft to prevent accidents, diesel engine crankshaft dynamic monitoring based on the actual situations of diesel engines, significance of dynamic balance for marine diesel engine crankshaft system is discussed and as well vibration monitoring and field dynamic balance system for diesel engine crankshaft system is constructed. The least square method is applied to fit fundamental frequency vibration signals of crankshaft system and the field dynamic balance strategy is designed on the basis of the influence coefficient method. The feasibility of the dynamic balance system is tested through experiments in the paper.

Abstract: The paper analyzes the rotor imbalance of cooling fan for the engine, and come to influence coefficient per unit quality. We can easy count the practice balancer cooling fan rotor. This method is very simple.