Fluid End Bore Shot Peening for Deep Compressive Stress
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Solution Overview
Problem
Existing shot peening technologies face challenges in achieving uniform and deep compressive stresses on metal surfaces, particularly in confined spaces and maintaining surface coverage, which affects the wear and fatigue resistance of metal components.
Innovation Solution
The use of a shot peening tool with a venturi nozzle and deflector tip configured to distribute shot radially outward in a 360-degree pattern, combined with varying shot diameters and hardness levels, to create compressive stresses up to 100 ksi beneath the metal surface and achieve 100% coverage, especially in smaller diameters and complex geometries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If conventional shot peening methods are used, then surface coverage can be achieved, but uniform and deep compressive stresses cannot be achieved, especially in confined spaces
Solution Approach 1:
The shot peening process is segmented into multiple passes with varying shot diameters and hardness levels. The method applies smaller diameter shot first to achieve uniform coverage, then progressively uses larger diameter shot to achieve deeper compressive stresses. This segmentation allows the process to overcome the limitation of confined spaces while achieving both coverage and depth.
Solution Approach 2:
The invention applies different shot parameters (diameter, hardness, velocity) to different stages of the peening process. By varying the local quality of the shot applied at different depths and locations, the method achieves uniform surface coverage initially, then progressively deeper compressive stresses in subsequent passes, resolving the contradiction between coverage and depth.
2Strength
If higher compressive stresses are achieved, then wear and fatigue resistance improves, but the complexity of the shot peening process increases
Solution Approach 1:
The invention maintains continuous useful action by using multiple passes of shot peening without interrupting the overall process. Each pass builds upon the previous one, with shot of appropriate diameter and hardness applied sequentially to achieve progressively deeper compressive stresses. This continuous multi-pass approach achieves high strength without requiring complex single-step equipment.
Solution Approach 2:
The method systematically changes shot parameters (diameter, hardness, velocity, mass flow rate) between passes to optimize compressive stress depth. By controlling these parameters across multiple passes rather than using complex single-pass equipment, the invention achieves high wear and fatigue resistance while managing process complexity through parameter optimization.
3Duration of action of stationary object
If shot peening is applied to achieve deep compressive stresses, then component life increases, but surface coverage uniformity decreases
Solution Approach 1:
The invention applies preliminary action by using smaller diameter shot in initial passes to establish uniform surface coverage before applying larger diameter shot for deeper compressive stresses. This preliminary uniform coverage creates a foundation that maintains manufacturing precision while enabling subsequent deep peening to extend component life.
Solution Approach 2:
The shot peening process uses periodic action with multiple passes, alternating between different shot diameters and hardness levels. Each pass is periodic and builds upon the previous one, maintaining surface coverage uniformity in early passes while progressively achieving deeper compressive stresses in later passes, thus extending component life without sacrificing precision.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances the fatigue strength, wear resistance, and average life of metal components by achieving deep compressive stresses and uniform coverage, potentially doubling or tripling the average life and cycles to failure, while reducing turbulence and abrasive wear.
Implementation Method 1
the surface is bombarded with high-velocity shot, round metallic, glass or ceramic beads, discharged from a pneumatic nozzle. The resulting lightly hammered or 'peened' effect places the surface in residual, preferably uniform, compression.
Implementation Method 2
a shot peening tool with a venturi nozzle and deflector tip configured to distribute shot radially outward
Data Source
AI summary
A fluid end having a longitudinal bore less than about 36 inches in diameter has an internal surface that is cold-worked to have compressive stresses of at least 15 ksi (103.42 MPa) beneath the metal surface up to about 40 mils (1.016 mm).