Multi-Stage Pump Shaft Grooves for Fatigue Fracture Prevention
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Solution Overview
Problem
Multi-stage pumps, particularly in the power generation sector, experience shaft fractures due to mechanical stress at the retaining ring groove, which is exacerbated by frequent start-stop cycles, compromising fatigue resistance and safety.
Innovation Solution
The pump shaft incorporates multiple grooves along its length to distribute and redirect axial forces, reducing stress concentrations and increasing the contact area for the relief device, thereby enhancing fatigue strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single retaining ring groove is used to engage the relief device, then the shaft can maintain axial position, but the groove area becomes a weak point prone to fatigue fracture
Solution Approach 1:
The single retaining ring groove is segmented into multiple grooves (at least two) distributed around the circumference of the pump shaft. This segmentation distributes the axial load from the relief device across multiple engagement points, preventing stress concentration at a single groove location and thereby eliminating the weak point that led to fatigue fractures.
2Reliability
If the groove engages deeply to secure the relief device, then axial positioning is improved, but the shaft cross-sectional area is reduced and stress concentration increases
Solution Approach 1:
Multiple grooves allow the shaft to maintain adequate cross-sectional area while providing sufficient engagement depth collectively. The load is distributed across multiple shallower grooves rather than one deep groove, maintaining both positioning stability and structural strength.
Solution Approach 2:
The functional requirements of axial positioning and stress distribution are merged by using multiple grooves that collectively provide the necessary engagement while distributing the mechanical stress across multiple locations, combining the benefits of secure positioning with reduced stress concentration.
Data Source
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AI summary
The present invention relates to a pump shaft for a multi-stage pump, in particular a centrifugal pump, wherein the pump shaft comprises a peripheral groove region for the engagement of a relief device in order to introduce a force acting in the axial direction of the pump shaft. The pump shaft is characterized in that the groove region comprises in the longitudinal section of the pump shaft a plurality of grooves which are spaced apart in the axial direction.