Forged Piston Spherical Surface for Hydraulic Pump Durability
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Solution Overview
Problem
Conventional liquid-pressure pumps face increased manufacturing costs and material waste due to the need for additional cutting steps after forming, which can damage the concave spherical surface under high pressure loads.
Innovation Solution
A piston design featuring a concave spherical portion with an oil passage that spreads towards the concave spherical surface, formed by forging, allowing for a wider contact area and reduced surface pressure, along with a cylindrical hollow portion to distribute loads effectively, thereby reducing manufacturing costs and enhancing durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the contact surface between the concave spherical surface and the convex spherical portion is made large by accurately forming through cutting work, then the surface pressure is reduced and the concave spherical surface is protected from damage, but the manufacturing workload increases and material waste occurs
Solution Approach 1:
The invention changes the manufacturing method from cutting to forging, transforming the production process parameters. Forging allows the concave spherical surface to be formed directly during the forming step without requiring subsequent cutting operations, thereby reducing manufacturing workload and eliminating material waste while maintaining the required contact surface area and pressure distribution
Solution Approach 2:
The invention extracts and eliminates the unnecessary cutting step from the manufacturing process. By designing the piston body and concave spherical portion to be formable directly through forging, the patent removes the redundant cutting operation that previously caused material waste and increased workload, while still achieving the functional requirement of a large contact surface
2Power
If high pressure operating oil is used to improve pump performance, then the pump can eject higher pressure oil, but high load acts on the shoe and large reaction force damages the concave spherical surface
Solution Approach 1:
The invention utilizes the spherical geometry of the concave spherical surface to distribute reaction forces from the convex spherical portion uniformly across the contact area. The curved surface geometry naturally redirects and disperses the concentrated loads generated by high-pressure oil ejection, preventing localized stress concentration that would damage the surface
Solution Approach 2:
The invention changes the structural parameters of the piston by forming the concave spherical portion with sufficient thickness and optimized geometry through forging. This structural parameter optimization enables the concave spherical surface to withstand the large reaction forces generated during high-pressure oil ejection without compromising surface integrity
3Manufacturing precision
If conventional cutting work is performed to improve accuracy of the concave spherical surface, then the surface pressure is reduced, but the manufacturing cost for the piston increases
Solution Approach 1:
The invention changes the manufacturing process parameters from precision cutting to precision forging. By optimizing the forging process and die design, the concave spherical surface can be formed directly with the required accuracy and surface quality, eliminating the need for costly cutting operations and associated material waste
Data Source
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AI summary
A piston is cylindrical and includes: a concave spherical portion formed at one of end portions of the piston and having a partially spherical shape; a cylindrical hollow portion formed at the other end portion of the piston; and an oil passage formed between the concave spherical portion and the hollow portion, the concave spherical portion and the hollow portion communicating with each other through the oil passage. The concave spherical portion includes a concave spherical surface formed by forging and having a partially spherical shape. A convex spherical portion of a shoe is supported by the concave spherical surface so as to be slidable and rotatable. An area of contact between the concave spherical surface and a predetermined master ball corresponding to the convex spherical portion is 40% or more of an entire area of the concave spherical surface.