摘要
离心泵是食品冶金、能源动力和石油化工等诸多领域中广泛使用的一种流体输送机械,随着现代工业生产力的不断发展,离心泵的转速和精密度要求也日趋提高,由此带来的振动问题一直是人们关注的重点。振动是离心泵的一种高发故障形式,其产生的主要原因是转子系统质心发生了偏移,而想要消除这种振动,就需要改变转子系统的质量分布,也即是我们所说的转子平衡。
本文首先对离心泵结构与工作原理进行了研究,并对其产生振动的原因和机理进行了分析；另一方面着重对离心泵转子平衡技术的原理进行了深入研究,给出了转子平衡技术的一些基础定义和平衡精度等级等具体平衡操作中的概念,并对实现转子动平衡的操作技术进行了探讨；最后本文以离心泵转子按支撑形式分为悬臂式离心泵和与其对应的双支撑式离心泵两种为例,对每种支撑形式的转子按其不同的结构进行了转子动平衡技术的试验研究。
通过理论和试验研究,本文得出的主要结论如下：
一、离心泵由于本身构造和工作使用原理产生不平衡的原因归纳起来主要有两大方面：一方面是物料对叶轮长时间的冲击、冲刷以及浸泡导致的叶轮局部变形、表面磨损以及腐蚀而引发的转子质心偏移,此种原因只能够依靠转子动平衡来进行校正以保证其正常工作；另一方面则是在制造过程中产生的如铸造缺陷、叶轮对心程度不够等,此种原因在一定程度上可以依靠提高制造精度优化设计来降低,但是在各部件组装后还是需要进行动平衡校正才能投入工作。
二、基于转子的校正面与支撑之间的位置关系,离心泵转子分为悬臂式和与之对应的双支撑式,由于转子的结构形式不同,所选择的校正方案也不同。
1、悬臂式离心泵转子系统只有一个或者两个叶轮,如果不是叶轮特别厚或者转子不平衡量特别小,通常情况都要考虑对轮系进行辅助动平衡校正。
叶轮校正面校正手段主要是磨削,单级时如果不平衡量非常大而叶轮流道又比较宽,则可以考虑在流道内焊接加重；两级时除非转子的不平衡量非常大,才会考虑进行焊接加重,否则校正手段只选取磨削去重。
对轮校正面手段就比较多样,如果不平衡量非常小,可以在对轮内侧非配合面上进行少量磨削；如果不平衡量非常大则优先考虑在轮毂上进行焊接加重；其余的情况通常选择在轮毂上钻孔这一手段。
2、双支撑式离心泵转子级数通常较多,因此校正面大多选择在叶轮上。
当该类转子只有一个叶轮时,除非不平衡量非常大,才会考虑到焊接加重,一般都选择在叶轮的两侧磨削去重；当该类转子有两个叶轮时,各选取一个作为校正面,校正手段主要是磨削,尽量不使用焊接加重,一些有条件的叶轮可以考虑钻孔去重；当叶轮数量超过两个时,要尽量选取远离中心的叶轮作为校正面,并可选取多个叶轮将不平衡量平均分解,校正手段大多采取磨削去重。
通过具体的试验研究,将不同类型转子的平衡方案进行了分类,为进一步完善动平衡校正过程提供了一定的参考依据。
The centrifugal pump is a kind of fluid transport machinery widely used in many areas of food and metallurgy, energy and power, and petrochemical. With the continuous development of modern industrial productivity, speed and precision requirements of the centrifugal pump is rising, the resulting vibration problem has been the focus of attention. Vibration of centrifugal pump is a high risk of failure, the main causes is the offset center of mass of the rotor system, and want to eliminate this vibration, you need to change the mass distribution of the rotor system, and that is what we call the rotor balance.
This article first has conducted the research to the centrifugal pump structure and the principle of work, and had the vibration reason and the mechanism to it has carried on the analysis; On the other hand focus on the principle of centrifugal pump rotor balancing technology for in-depth study, has given in rotor balance domain some foundation definition and the balance precision class and so on in the concrete balance operation concept, and the realization of the rotor balancing operating techniques have been explored; finally this paper to centrifugal pumps in the form of rotor for cantilever centrifugal pumps and its corresponding double-support, centrifugal pump two as examples, for each of the forms of the element by its different structure for the rotor balancing technology pilot studies.
Through the theory and the experimental study, the main conclusion which this article obtains are as follows:
Thus first, because of the centrifugal pump's construction and use of a causes of imbalance in the theory can be summarized in two major areas:the one hand, the impact of material on the impeller for a long time, washed and soaked impeller caused local deformation, surface wear and corrosion caused by the rotor center of mass offset, such reasons can only be corrected for rotor balancing to ensure their normal work; the other is the defects in the manufacturing process such as casting, impeller inadequate extent of heart, this kind of reason may depend upon the enhancement manufacture precision optimization design to a certain extent to reduce, but needs to carry on the transient equilibrium after various parts assembly to adjust can invest the work.
Second, based on the positional relationship between the adjustment surface and the support of the rotor, the centrifugal pump rotors are divided into the cantilever and the corresponding dual support type, the rotor structure of different forms, the choice of correction programs are also different.
First, the cantilever centrifugal pump rotor has only one or two impellers, if not the impeller particularly thick or rotor unbalance is very small, typically must take into account the auxiliary balancing wheel correction.
The impeller adjusts surface adjustment method mainly is the grinding, when it is single-stage, if the unbalance amount is great and the impeller flow channel quite is wide, then may consider welding in the flow channel; when two-stages only if the rotor unbalance amount extremely is big, only then can consider carries on the welding to aggravate, otherwise the adjusts method only to select the grinding.
The shaft coupling surface adjusts methods quite to be diverse, if the unbalance amount is extremely small, can grind in the shaft coupling non-fitting surface; if unbalance amount is very big, then first considered carries on the welding on the wheel hub; other situation usual choice on wheel hub drill hole.
Second, the double brace centrifugal pump rotor impeller are usually many, therefore the adjustment surface mostly all chooses on the impellers.
When the kind of rotor is only one impeller, unless the amount of unbalance is very large, will take into account the welding, are generally chosen on both sides of the impeller grinding; when this kind of rotor has two impellers, make each one as the adjustment surface, the adjustment method mainly is respectively the grinding, does not use the welding as far as possible, some conditions to consider the drill hole; when impeller quantity surpasses two, must select the impeller which far away from the center as the adjustment surface, and might select many impellers to decompose the unbalance amount, the adjustment method mostly will adopt the grinding.
Through the concrete experimental study, has carried on the different type rotor balanced plan the classification, for further balance adjustment process to provide certain reference.
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