Single-Piece Cast Pump Power End Frame Eliminating Weld Fatigue

The patent merges multiple separate metallic pieces into a single integrated frame structure. The frame is constructed as one unified component with all structural elements (ribs, crosshead tube supports, lube rail mounts, nose plate) formed as integral parts, eliminating the need for weld joints between these components. This merging approach removes the weld line stress risers that caused fatigue failures while maintaining the structural functionality achieved through assembly of multiple pieces.

While the frame itself is unified, the patent strategically segments the structure through internal ribs and varying wall thicknesses to distribute stresses. The rib configuration divides the frame into functional zones that manage cyclical loading paths, and the non-uniform thickness segments material distribution to place more material where stresses are highest, reducing overall fatigue without requiring welds.

The patent applies local quality by varying the wall thickness of the frame structure. Thicker sections are positioned at locations experiencing higher cyclical stresses (such as near the crosshead tube and nose plate mounting areas), while thinner sections are used where stresses are lower. This localized material distribution optimizes fatigue resistance without requiring overall structural complexity, as each local region is tailored to its specific stress environment.

The patent incorporates curved transitions and rounded corners throughout the frame structure instead of sharp angles or abrupt geometry changes. These curved features eliminate stress concentration points that would occur at sharp transitions, allowing the simplified single-piece structure to distribute stresses more evenly. The curvature principle is applied to all junctions and thickness transitions to prevent crack initiation while maintaining manufacturing simplicity.

The primary application of merging is to eliminate welds entirely by forming the frame as a single cast or forged piece. All components that would traditionally be joined by welding (ribs, supports, mounting structures) are instead created as integral features of the unified frame body. This merging directly addresses the fatigue weakness of welds by removing the weld metallurgy and heat-affected zones that are prone to cracking under cyclical loading.

The patent treats the frame as a durable, long-lasting component by eliminating the weak link of welds. The single-piece construction creates a frame with uniform material properties throughout, ensuring consistent fatigue life and reliability. This approach prioritizes the longevity of the frame structure over the flexibility of modular assembly, creating a component designed for extended service life in the harsh hydraulic fracturing environment.