Expanded Graphite Yarn Twisting for Uniform Gland Packing Thickness
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Solution Overview
Problem
Yarns with elongated expanded graphites packed in tubular members often result in uneven thickness due to entanglement issues, leading to inadequate sealing performance in gland packings.
Innovation Solution
The yarns are made by twisting and packing elongated pieces of expanded graphite sheets within a tubular member formed from knitted or braided fibers, which prevents relative movement and maintains uniform density, thereby ensuring consistent thickness and enhanced sealing performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If elongated expanded graphites are packed straight in the tubular member, then the packing process is simple, but the yarn exhibits uneven thickness and poor sealing performance
Solution Approach 1:
The patent applies curvature by twisting the elongated expanded graphite pieces into a helical or curved configuration within the tubular member. This twisting transforms the straight, rigid structure into a curved, entangled arrangement that naturally interlocks with adjacent pieces, preventing relative movement and ensuring uniform density distribution throughout the yarn cross-section, thereby achieving consistent thickness and improved sealing performance
2Ease of manufacture
If elongated expanded graphites are packed straight in the tubular member, then the packing process is simple, but the sealing performance is insufficient
Solution Approach 1:
The twisting of expanded graphite pieces creates a curved, interlocked structure that resists relative movement under external forces, maintaining uniform density and preventing void formation. This entangled configuration ensures continuous contact between graphite pieces and the tubular member wall, providing reliable sealing performance while the twisting process remains relatively simple to implement
3Manufacturing precision
If pieces of expanded graphite sheet are twisted with excessive turns, then the entanglement and uniformity improve, but fractures and piece failures occur during shaping
Solution Approach 1:
The patent optimizes the twisting parameter by specifying that pieces of expanded graphite sheet be twisted at five turns or less per 100 mm. This parameter change balances the competing requirements: sufficient twisting to create entanglement and prevent relative movement (improving density uniformity), while limiting the twist intensity to avoid excessive stress that would cause fractures or piece failures during the shaping process
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 ensures uniform thickness of the yarns, preventing fractures and improving the sealing performance of gland packings by entangling the expanded graphite sheets, thus maintaining their density and preventing voids.
Implementation Method 1
That structure can easily entangle one piece of expanded graphite sheet with another, and thus, it can prevent each piece of expanded graphite sheet from moving relative to others
Data Source
AI summary
A yarn includes elongated pieces of expanded graphite sheet and a tubular member made of knitted or braided fibers. In the tubular member, the pieces of expanded graphite sheet are twisted and packed. The yarns are knitted, or bundles of the yarns are twisted to form a gland packing.