Fluid End Tapered Bore Geometry for Stress Relief and Retainer Support
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Solution Overview
Problem
High stress concentrations at the intersection corners of bores in fluid ends of high-pressure reciprocating pumps lead to reduced fatigue life and increased manufacturing costs due to manual finishing, which also complicates valve retainer installation.
Innovation Solution
Implementing a fluid end design with tapered portions in adjacent bores to reduce stress concentrations and create a ledge for improved retainer support, using a combination of machining and minimal hand-finishing to enhance the intersection geometry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If hand-grinding is performed to create a transitional radius at intersecting corners, then stress concentration is reduced, but manufacturing time and cost increase
Solution Approach 1:
The transitional radius geometry is pre-designed into the intersecting bores before final machining, so that the stress-reducing feature is already in place and requires minimal or no hand-finishing work
Solution Approach 2:
The geometry of the intersecting bores is modified by introducing specific radius parameters at the corners, changing the shape parameters to reduce stress concentration while maintaining manufacturability
2Strength
If hand-finishing is performed to create a uniform radiused corner, then stress distribution is improved, but manufacturing cost increases
Solution Approach 1:
The radiused corner geometry is pre-planned and pre-machined using standard toolpaths, so that the beneficial stress distribution is achieved without requiring expensive and time-consuming hand-finishing operations
Solution Approach 2:
The machining process itself is designed to automatically create the radiused corners through programmed tool motion, eliminating the need for manual intervention and making the process self-sufficient
3Duration of action of stationary object
If improved corner geometry is implemented to extend fluid end life, then fatigue resistance is enhanced, but valve retainer installation becomes difficult
Solution Approach 1:
The corner geometry is designed with locally optimized features that provide both stress reduction and adequate space for retainer installation, with different regions of the intersection having different geometric characteristics to satisfy multiple requirements
Data Source
AI summary
A fluid end of a reciprocating pump includes multiple bores formed therein, and adjacent bores intersect each other. The intersection of two adjacent bores forms an intersection corner, which is where a concentration of high stress occurs during operation of the reciprocating pump. At least one of the bores includes a first tapered portion and a second tapered portion. The first tapered portion increases a cross-sectional area of the bore toward the crossbore to reduce the concentration of stress on the intersection corners. The second tapered portion decreases a cross-sectional area of the bore to provide a ledge having an extended arc length and forming a groove. The extended arc length of the ledge increases an available surface area to secure a valve retainer within the groove.