Magnetic Encoder Zinc-Aluminum-Magnesium Plating Adhesion

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Solution Overview

Problem

Magnetic encoders using cold rolled steel plates with hot-dip zinc-aluminum-magnesium alloy plating face issues with low adhesive strength between the plated layer and the adhesive layer, leading to poor durability, especially in outdoor environments where corrosion is a concern.

Innovation Solution

A magnetic encoder design that includes a cold rolled steel plate core with a zinc-aluminum-magnesium alloy plated layer, a phosphoric acid salt film layer, and an adhesive layer, which improves the stability of the adhesive strength and prevents corrosion product generation, using phenol-based or epoxy-based adhesives and a silane-based or epoxy-based primer for enhanced bonding.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If hot-dip zinc-aluminum-magnesium alloy plating is applied to cold rolled steel plate to improve corrosion resistance, then corrosion resistance is improved, but adhesive strength between plated layer and adhesive layer deteriorates

Engineering Contradiction:
Improvecorrosion resistanceVSAvoidadhesive strength
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

A phosphoric acid salt film layer is introduced as an intermediary between the zinc-aluminum-magnesium alloy plated layer and the adhesive layer. This intermediate layer serves as a bonding bridge that maintains both corrosion resistance and adhesive strength, resolving the contradiction by adding a mediating substance that facilitates both functions simultaneously.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The solution creates a composite structure consisting of multiple layers: the cold rolled steel plate core, the zinc-aluminum-magnesium alloy plated layer for corrosion protection, the phosphoric acid salt film layer for bonding enhancement, and the adhesive layer. This composite material approach allows each layer to fulfill its specific function while working together to achieve both corrosion resistance and adhesive strength.

Inventive Principle:
Principle #40Composite materials

2Quantity of substance

If cold rolled steel plate is used for core metal to reduce material cost, then material cost is reduced, but corrosion resistance deteriorates

Engineering Contradiction:
Improvematerial costVSAvoidcorrosion resistance
Core Design Contradiction:
Quantity of substanceVSReliability

Solution Approach 1:

The solution creates a composite structure consisting of multiple layers: the cold rolled steel plate core, the zinc-aluminum-magnesium alloy plated layer for corrosion protection, the phosphoric acid salt film layer for bonding enhancement, and the adhesive layer. This composite material approach allows each layer to fulfill its specific function while working together to achieve both corrosion resistance and adhesive strength.

Inventive Principle:
Principle #40Composite materials

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 provides a magnetic encoder with improved adhesive strength and corrosion resistance, allowing it to withstand long-term use in outdoor environments without peeling of the plastic magnet section, even when exposed to high-speed rotation and corrosive conditions.

Implementation Method 1

by forming a film of a phosphoric acid salt on a surface of a plated layer including a zinc-aluminum-magnesium alloy

Methodology Applied
Scientific EffectPhosphoric acid salt film formation: Deposition (physical)

Implementation Method 2

an adhesive layer stacked on the phosphoric acid salt film layer

Methodology Applied
Scientific EffectAdhesion: Adhesive

Data Source

PatentEP3326805B1Magnetic encoder and method for producing the same
Publication Date: 2020.05.27 NAKANISHI METAL WORKS CO LTD
  • EP3326805B1 patent drawingFigure 1A~1B
  • EP3326805B1 patent drawingFigure 2
  • EP3326805B1 patent drawingFigure 3

AI summary

Disclosed is a magnetic encoder having, as a core metal, a cold rolled steel plate subjected to hot-dip zinc plating, the magnetic encoder being excellent in stability of adhesive strength between a plated layer and an adhesive layer, and a method for efficiently producing the magnetic encoder. The magnetic encoder includes a core metal made of a cold rolled steel plate; a substantially annular plastic magnet section magnetized multi-polarly in a circumferential direction; a plated layer containing a zinc-aluminum-magnesium alloy stacked on a surface of the core metal; a phosphoric acid salt film layer stacked on a surface of the plated layer; an adhesive layer stacked on the phosphoric acid salt film layer; and a plastic magnet layer stacked on the adhesive layer.