Large-Diameter Sliding Member Surface Control to Inhibit Seizure
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Solution Overview
Problem
The manufacturing of large sliding members for ships faces challenges in achieving sufficient dimensional accuracy and inhibiting seizure between shaft and bearing members due to deflection during mechanical processing, which increases manufacturing costs and makes precise surface control difficult.
Innovation Solution
A sliding member design that includes a shaft diameter of at least 180 mm with a bearing member having an inner peripheral face, where the arithmetic mean roughness of the outer peripheral face is controlled to satisfy a specific contact rate formula (A ≥ 3.04 * Ra^0.78), allowing for effective inhibition of seizure without precise surface shape control, thereby reducing manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If mechanical processing is used for large sliding members, then manufacturing efficiency is improved, but dimensional accuracy deteriorates due to deflection
Solution Approach 1:
The invention changes the parameter focus from controlling surface shape (traditional approach) to controlling surface roughness and contact rate. By specifying that the contact rate shall be 10% or more without requiring precise surface shape control, the patent enables mechanical processing to achieve sufficient accuracy while maintaining high productivity.
2Manufacturing precision
If manual polishing is used to improve surface accuracy, then manufacturing precision is improved, but manufacturing cost increases
Solution Approach 1:
The invention changes the controlled parameter from surface shape to surface roughness and contact rate. This parameter change allows mechanical processing to produce acceptable surfaces without expensive manual polishing, thereby reducing manufacturing cost while maintaining sufficient precision.
Solution Approach 2:
The invention accepts that some surface imperfections are acceptable if the contact rate is sufficient. This approach replaces expensive precision polishing with cheaper mechanical processing that produces good enough surfaces for reliable operation.
3Reliability
If surface roughness is reduced to prevent seizure, then reliability is improved, but manufacturing complexity increases
Solution Approach 1:
The invention simplifies the control approach by focusing on two key parameters (surface roughness and contact rate) rather than multiple surface shape parameters. This reduction in complexity makes the manufacturing process more manageable while still achieving reliable seizure prevention.
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
The solution effectively inhibits seizure between the shaft and bearing members while suppressing manufacturing costs by controlling the contact rate and arithmetic mean roughness, ensuring reliable operation without the need for precise surface shape control.
Implementation Method 1
a lubricating liquid is supplied to a gap between the shaft member and the bearing member. The lubricating liquid forms a lubricating film between the shaft member and the bearing member to inhibit seizure therebetween
Implementation Method 2
manual polishing of the outer peripheral face after the mechanical processing
Data Source
Figure 1
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AI summary
A sliding member according to one aspect of the present invention includes: a shaft member having a shaft diameter of greater than or equal to 180 mm; and a bearing member having an inner peripheral face which slidably supports an outer peripheral face of the shaft member, wherein in a case in which an arithmetic mean roughness of the outer peripheral face is denoted by Ra1 [µm], a contact rate Aat between the outer peripheral face and the inner peripheral face satisfies the following formula 1. Aat≧3.04Ra10.78