Graphite Electrode Nipple Geometry to Reduce Screw Loosening

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Solution Overview

Problem

Graphite electrodes suffer from defects such as loosening of screws between the nipple and socket, and high manufacturing costs due to the need for precise shaping of graphite components.

Innovation Solution

The graphite electrode design includes specific effective diameter and taper angle differences between the nipple and socket, along with controlled linear expansion coefficients, to reduce screw loosening and manufacturing costs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the socket and nipple are formed into special shapes to prevent stress concentration, then breakage of the nipple is prevented, but manufacturing cost increases greatly

Engineering Contradiction:

Improvenipple breakage resistanceVSAvoidmanufacturing cost

Core Design Contradiction:

StrengthVSEase of manufacture

Solution Approach 1:

The invention changes the dimensional parameters of the nipple and socket, specifically setting the effective diameter difference to 0.03 to 0.5 mm and the taper angle difference to -1 to -5 minutes. These parameter optimizations prevent stress concentration and nipple breakage while avoiding the need for complex special shapes, thus controlling manufacturing cost.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If the effective diameter difference and taper angle difference are optimized, then screw loosening is reduced, but manufacturing precision requirements increase

Engineering Contradiction:

Improvescrew connection stabilityVSAvoiddimensional accuracy

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The invention optimizes the effective diameter difference to 0.03 to 0.5 mm and taper angle difference to -1 to -5 minutes. These parameter ranges are carefully selected to ensure reliable screw connections and prevent loosening while remaining achievable through conventional manufacturing processes, balancing reliability with manufacturing precision requirements.

Inventive Principle:

Principle #35Parameter changes

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 design reduces screw loosening and maintains a high loosening/fastening torque ratio, minimizing defects and manufacturing costs while ensuring reliable connections.

Implementation Method 1

the value obtained by subtracting a linear expansion coefficient of the nipple from a linear expansion coefficient of the pole is -0.4 to +0.5 (10‑6)

Methodology Applied

Scientific EffectLinear expansion coefficient: Thermal Expansion

Data Source

PatentEP4287774B1Graphite electrode and electric furnace

Publication Date: 2025.07.16 TOKAI CARBON CO LTD

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AI summary

A graphite electrode includes a pole having a socket in an internal screw shape at an end portion, and a nipple in an external screw shape that can be fastened to the socket, wherein a value obtained by subtracting an effective diameter on a small diameter end side of the nipple from an effective diameter on a small diameter end side of the socket is 0.05 to 0.7 mm, and a value obtained by subtracting a taper angle of the socket from a taper angle of the nipple is -2 minutes to -3 minutes 30 seconds.