Cast Iron Cylinder Surface Projections for Stronger Metal Bonding

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Solution Overview

Problem

Existing methods for enhancing the bonding strength between a cast iron cylindrical member and an outer peripheral metal material, such as those described in Patent Documents 1 and 2, do not effectively utilize the constricted shape of projections on the cast iron surface, leading to suboptimal integration.

Innovation Solution

Incorporating projections with a specific constricted shape on the outer peripheral surface of the cast iron cylindrical member, characterized by a constriction rate, average maximum and minimum thicknesses, and a defined anchor portion index, to improve the bonding strength when integrated with an outer peripheral member.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If conventional projections with uniform thickness are used on the cast iron cylindrical member, then the manufacturing process is simple, but the bonding strength with the outer peripheral metal is insufficient

Engineering Contradiction:
Improvebonding strengthVSAvoidprojection shape complexity
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The projection is designed with non-uniform thickness distribution, creating a constricted shape where the middle portion has smaller diameter than the top and bottom portions. This local variation in geometry concentrates stress and improves bonding strength at the critical interface between the cast iron cylindrical member and the outer peripheral metal, while maintaining overall structural integrity.

Inventive Principle:
Principle #3Local quality

2Strength

If the number of projections and their height are increased to improve bonding strength, then the bonding strength increases, but the manufacturing precision requirements become more stringent

Engineering Contradiction:
Improvebonding strengthVSAvoidprojection dimensional precision
Core Design Contradiction:
StrengthVSManufacturing precision

Solution Approach 1:

The invention optimizes specific geometric parameters of the projection, including the constriction rate (ratio of minimum diameter to maximum diameter), the height of the projection, and the distribution of thickness. By carefully controlling these parameters within specific ranges, the bonding strength is maximized while maintaining manufacturability and avoiding excessive precision requirements.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP3805545B1Cylindrical member
Publication Date: 2024.02.28 TEIKOKU PISTON RING CO LTD
  • EP3805545B1 patent drawingFigure 1
  • EP3805545B1 patent drawingFigure 2
  • EP3805545B1 patent drawingFigure 3

AI summary

To provide a cast iron cylindrical member capable of improving the bonding strength when metal on the outer peripheral side and the cast iron cylindrical member are integrated. For this objective, in a cast iron cylindrical member including a plurality of projections including constricted projections on the outer peripheral surface, the anchor portion index (I) represented by {(Aav2 - Bav2) × π/4 × Pn x Pr/100} × 0.35H/2 is set in a specific range.