JP2003323469A - Method for designing balance of rigid rotor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a highly accurate and efficient method for designing the balance of a rigid rotor while overcoming the drawbacks of conventional CAD- based design techniques. <P>SOLUTION: A model of the rigid rotor is created using a three-dimensional CAD and the positions of two or more balancing planes perpendicular to its axis are designated. The amount of residual unbalance on each of the balancing planes is calculated on the basis of the state of mass distribution and a determination is made as to whether or not a balancing operation is needed, based on the calculated value. If it is determined to be necessary, balancing factors of the model are calculated from the designated balancing position and the amount of residual unbalance and the shape of the model is changed using the balancing factors to calculate balancing factors of the shape that has been either added or removed. The amount of residual unbalance on each of the balancing planes is calculated on the basis of the state of mass distribution which is re-calculated from the three-dimensional CAD using the balancing factors calculated. Designing is complete once a state is reached where the calculated value is nearly zero. <P>COPYRIGHT: (C)2004,JPO

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a balancing design method for a rigid rotating body such as an impeller of a centrifugal pump. 2. Description of the Related Art Conventionally, when a rigid rotating body such as a pump impeller is designed by CAD, the unbalanced centrifugal force (F) and the unbalanced moment (N) of the rigid rotating body are eliminated. In order to dynamically correct the mass distribution so that ΔF = 0 and ΔN = 0, a method of creating a virtual model on paper or the like and reflecting the model on a design drawing has been adopted.
However, this method does not carry out detailed calculations and can only get an idea of the approximate value of residual imbalance even if it gets tired. And there is the regret that time is spent unnecessarily. Further, it is very difficult to eliminate minute residual unbalance such as simultaneous elimination of unbalance centrifugal force and unbalance moment at the conception stage. This tendency is due to the fact that the shape of the rigid rotating body is three-dimensional in the axial direction. The larger the change, the more noticeable it is. At present, the residual unbalance amount is corrected by removing or adding a considerable amount of unbalance to correct the imbalance. Alternatively, a portion in which a change in shape due to addition is not preferable, for example, a shape of a blade surface of a pump impeller or the like is finished to a shape different from that at the time of design, resulting in a result that predetermined performance cannot be ensured. An object of the present invention is to calculate a residual unbalance amount of a rigid rotating body based on a simulation model created by using three-dimensional CAD, and to perform a balancing operation based on the calculated value. By performing an arithmetic analysis process in accordance with the procedure of determining necessity, it is possible to eliminate the drawbacks of the conventional design technology as described above, and to provide a highly accurate and efficient balance design method for a rigid rotating body. It is in. In the method of designing a rigid rotating body according to the present invention, a model of the rigid rotating body is created by three-dimensional CAD to determine the origin of an orthogonal coordinate system, and to determine the origin of the orthogonal coordinate system. Specify the position of the correction surface equal to or larger than the surface, calculate the residual unbalance amount of each correction surface based on the mass distribution state calculated from the three-dimensional CAD, and if the calculated value is almost zero, no balancing work is required. The design is determined to be completed, but if not, it is determined that a balancing operation is required, and in order to correct the model, a radial position to be corrected is designated on each of the correction surfaces and the design is performed. The correction factors (mass and center of gravity) of the model are calculated from the specified correction position and the residual unbalance amount, and the correction factors (mass and center of gravity) of the added or removed shape are changed by changing the model shape using the correction factors. 3D CA
D, and after changing the model shape using the calculated correction factors, the residual unbalance amount of each correction surface is calculated again based on the mass distribution state calculated from the three-dimensional CAD. Is completed, the design is terminated. An example in which an impeller 2 of a centrifugal pump 1 is implemented as a concrete example of a rigid rotating body will be described below. First, a model of the pump impeller 2 to be manufactured is created by three-dimensional CAD, the origin O of the orthogonal axis system is determined, and the correction surface on the plane of the upper flange 2a and the lower flange 2b orthogonal to the axis Z is determined. Specify the positions of A and B. Then, the amount of residual unbalance in each of the corrected surfaces A and B is calculated from the mass distribution state calculated from the three-dimensional CAD, and when the calculated value is substantially zero, it is determined that no balancing work is required, and the design is completed. However, if not, it is determined that a balancing operation is required, and the procedure shown in FIG. 1 is repeated to correct the model, and the radial position to be corrected on each of the correction planes A and B is determined. , The correction factor (mass and center of gravity) of the model is calculated from the specified correction position and the residual unbalance amount, and the model shape is changed using the correction factor to add (increase the thickness) or remove (the thickness). The correction factors (mass and center of gravity) of the reduced thickness
The model is calculated by AD, and the model shape is changed using the calculated correction factor. Then, the residual unbalance amount of each of the correction surfaces A and B is calculated again from the mass distribution state calculated from the three-dimensional CAD, and if the residual unbalance amount after the change of the model shape becomes almost zero as in the previous case, the model is changed. It is determined that the balancing work is no longer necessary, and the design is completed. If it is determined that the residual unbalance amount is still large, the procedure shown in FIG. 1 is repeated to correct and balance the model. By carrying out the method of the present invention, the processing for correcting the residual unbalance is minimized, which leads to a reduction in processing time, a reduction in the labor burden of the balancing processor, and a reduction in processing cost. It is possible to realize a great improvement in processing efficiency. In addition, the systematization of the design method enables the formation of a rigid rotating body model with high accuracy and excellent balance at the design stage without relying on the experience and intuition of the designer, and there is a difference in results depending on the designer. Without this, it is possible to provide products with high quality and stable functions and performance. Furthermore, when applied to a pump impeller to minimize the removal or addition of parts that do not like the shape change, it can lead to stabilization of the pumping flow, and can be expected to improve erosion resistance against wear due to drift and cavitation. It is also effective in suppressing vibration due to cavitation.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a flowchart showing a procedure for implementing a method of the present invention. FIG. 2 is a vertical sectional side view of a centrifugal pump to which the method of the present invention is mainly applied. FIG. 3 is an outer side view of an impeller in the centrifugal pump of FIG. 2; FIG. 4 is a plan view seen from above in FIG. 3; FIG. 5 is a side view showing a portion and a range of a correction surface in the impeller. FIG. 6 is a plan view showing a portion and a range of a correction surface in the impeller. [Explanation of Signs] 2 Rigid rotating body (pump impeller) A Correction plane B Correction plane O Origin Z axis of orthogonal coordinate system

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Claims (1)

Claims: 1. A model of a rigid rotating body is created by three-dimensional CAD, an origin of an orthogonal coordinate system is determined, and positions of two or more correction planes orthogonal to an axis are specified. The residual unbalance amount of each of the corrected surfaces is calculated based on the mass distribution state calculated from the dimension CAD, and when the calculated value is substantially zero, it is determined that no balancing work is required, and the design is completed. Otherwise, in order to determine that a balancing operation is required and to correct the model, a radial position to be corrected on each of the correction surfaces is specified, and the model is determined from the specified correction position and the residual unbalance amount. The correction factors (mass and center of gravity) are calculated, and the correction factors (mass and center of gravity) of the shape added or removed by changing the model shape using the correction factors are calculated in three-dimensional CA.
D, and after changing the model shape using the calculated correction factors, the residual unbalance amount of each correction surface is calculated again based on the mass distribution state calculated from the three-dimensional CAD. A design method for balancing a rigid rotating body, characterized in that the design is terminated when the value reaches almost zero.