Gas Pressure Vessel Thread Root Stress Reduction
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Solution Overview
Problem
In gas pressure vessels, wrinkles on the inner surface of the dome part can lead to cracking, especially at the root of the female thread, due to increased stress when the inner diameter of the neck part is small, making it difficult to perform machining and increasing the risk of gas leakage.
Innovation Solution
A gas pressure vessel design with a dome part opening diameter of 90 mm or greater, where the innermost root of the female thread is positioned inside an imaginary plane extending from the dome's outer surface, reducing stress on the thread root and allowing for easier machining to remove wrinkles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the inner diameter of the neck part is increased to enable machining of the dome part inner surface, then the ease of manufacture is improved, but the load on the lid and stress on the female thread part increase leading to cracking
Solution Approach 1:
The patent applies parameter changes by optimizing the inner diameter of the neck part to a specific range (90 mm or greater) that enables machining operations on the dome part inner surface while controlling stress levels. Additionally, the position of the female thread root is strategically placed inside the imaginary plane extending from the dome outer surface, creating a geometric parameter optimization that reduces stress concentration at the thread root despite the increased diameter
2Strength
If the inner diameter of the neck part is kept small to reduce lid load, then the strength of the neck part is improved, but it becomes difficult to perform machining to remove wrinkles on the inner surface of the dome part
Solution Approach 1:
The patent resolves this contradiction by establishing a minimum inner diameter parameter (90 mm or greater) that is sufficient to allow machining tools to access and process the dome part inner surface, while simultaneously optimizing the thread root positioning parameter inside the imaginary plane to maintain adequate strength
3Reliability
If machining is performed to remove wrinkles on the inner surface of the dome part, then the reliability is improved by preventing cracking, but the inner diameter of the neck part must be increased which increases stress on the female thread part
Solution Approach 1:
The patent addresses this contradiction through parameter optimization: the inner diameter is set to 90 mm or greater to enable wrinkle removal machining for reliability, while the female thread root position is placed inside the imaginary plane extending from the dome outer surface. This specific geometric configuration reduces stress concentration at the thread root, counterbalancing the increased stress from the larger diameter and enabling both reliability improvement and stress control
Data Source
AI summary
A gas pressure vessel capable of performing processing of removing wrinkles on an inner surface of a dome part and preventing cracking starting from a root of a thread of a neck part is provided. In a gas pressure vessel according to one embodiment, a dome part (12) has an opening whose diameter is 90 mm or greater, and the innermost root of the thread in a female thread part (10a) into which a lid (20) is screwed is provided inside an imaginary plane (B) formed by extending an outer surface of the dome part (12) toward an opening.