Twisted Graphite Yarn Structure for Uniform Gland Packing Sealing

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Solution Overview

Problem

Existing yarns with elongated expanded graphites in tubular members suffer from uneven thickness due to lack of entanglement, leading to inadequate sealing performance in gland packings.

Innovation Solution

The yarns are designed to entangle expanded graphite sheets within the tubular member by twisting them at a controlled number of turns, maintaining uniform density and thickness, thereby enhancing sealing performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If elongated expanded graphites are packed straight in a tubular member, then the packing process is simple, but the yarn exhibits unevenness in thickness

Engineering Contradiction:
Improvepacking process simplicityVSAvoidyarn thickness uniformity
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The expanded graphite pieces are twisted into a spiral or curved configuration rather than remaining straight. This curvature causes the pieces to entangle with each other when packed in the tubular member, preventing them from aligning in straight lines and thereby achieving uniform yarn thickness while maintaining ease of manufacture

Inventive Principle:
Principle #14Spheroidality (Curvature)

Solution Approach 2:

The physical state of the expanded graphite pieces is changed from straight to twisted by controlling the degree of twisting (e.g., 2-5 turns per 100 mm). This parameter change in the configuration of the graphite pieces enables them to entangle and pack uniformly, resolving the thickness uniformity issue without complicating the manufacturing process

Inventive Principle:
Principle #35Parameter changes

2Device complexity

If elongated expanded graphites are packed straight in a tubular member, then the structure is simple, but the gland packing fails to achieve sufficient sealing performance

Engineering Contradiction:
Improveyarn structure simplicityVSAvoidsealing performance
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

By twisting the expanded graphite pieces into a spiral configuration, the yarn structure becomes slightly more complex but achieves superior sealing performance. The twisted pieces entangle and interlock, creating a dense, uniform packing that effectively seals gland areas, thus improving reliability while accepting moderate increases in device complexity

Inventive Principle:
Principle #14Spheroidality (Curvature)

Solution Approach 2:

The yarn is formed as a composite structure combining twisted expanded graphite pieces with a tubular member. This composite construction enhances the sealing performance by creating a multi-component system where the twisted graphite provides density and uniformity, while the tubular member provides structural support, together achieving reliable sealing

Inventive Principle:
Principle #40Composite materials

3Stability of the object's composition

If expanded graphite sheets are twisted with excessive turns, then entanglement increases, but fracture and piece loss occur during shaping

Engineering Contradiction:
Improveentanglement densityVSAvoidresistance to fracture
Core Design Contradiction:
Stability of the object's compositionVSStrength

Solution Approach 1:

The degree of twisting is precisely controlled within an optimal range (2-5 turns per 100 mm). This parameter optimization ensures sufficient entanglement for uniform packing and stability, while avoiding excessive twisting that would cause fracture and piece loss during the shaping process

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

Instead of applying maximum twisting to achieve complete entanglement, the invention applies a partial amount of twisting (2-5 turns per 100 mm) that is sufficient to achieve the desired entanglement and uniformity without causing damage. This partial action prevents fracture while maintaining the benefits of entanglement

Inventive Principle:
Principle #16Partial or excessive action

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, significantly improving the sealing performance of gland packings by preventing movement and maintaining density of the expanded graphite sheets.

Implementation Method 1

This 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

Methodology Applied
Scientific EffectEntanglement:

Data Source

PatentEP3779003B1Yarn and gland packing
Publication Date: 2025.04.30 NIPPON PILLAR PACKING CO LTD
  • EP3779003B1 patent drawingFigure 1
  • EP3779003B1 patent drawingFigure 2
  • EP3779003B1 patent drawingFigure 3

AI summary

A yarn (1) includes elongated pieces of expanded graphite sheet (7) and a tubular member (5) made of knitted or braided fibers. In the tubular member (5), the pieces of expanded graphite sheet (7) are twisted and packed. The yarns (1) are knitted, or bundles of the yarns (1) are twisted to form a gland packing.