Piercing Plug Coating Structure to Prevent Peeling and Seizure
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Solution Overview
Problem
Conventional plugs used in the Mannesmann pipe-making method experience premature wear and seizure due to the peeling off of iron and iron oxide coatings during piercing of high-strength alloy billets, leading to reduced efficiency and short plug life.
Innovation Solution
A plug with a body coating and a denser surface-layer coating formed by arc spraying iron wire, where the surface-layer coating has a lower porosity and higher tensile strength than the body coating, preventing deformation and peeling, and is applied at a shorter spray distance to enhance adhesion and heat insulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a coating of oxidized scale is formed on the plug surface by heat treatment, then heat insulation and seizure resistance are improved, but the coating wears off quickly during piercing/rolling operations
Solution Approach 1:
The invention applies a composite coating structure consisting of an inner layer made of iron and iron oxides deposited by electric-arc spraying, and an outer layer of oxidized scale formed by heat treatment. This composite structure combines the high adhesion and wear resistance of the sprayed coating with the heat insulation and seizure resistance of the oxidized scale layer, resolving the contradiction between coating durability and functional performance.
Solution Approach 2:
The invention performs electric-arc spraying to form the iron and iron oxides coating on the plug surface before heat treatment. This preliminary action creates a robust foundation layer that prevents premature wear and exposure of the base material, allowing the subsequent oxidized scale coating to maintain its protective functions for longer periods.
2Reliability
If heat treatment is performed to form oxidized scale coating, then seizure resistance is improved, but the process requires several hours to several tens of hours
Solution Approach 1:
The invention performs electric-arc spraying to form the iron and iron oxides coating on the plug surface before heat treatment. This preliminary action creates a robust foundation layer that prevents premature wear and exposure of the base material, allowing the subsequent oxidized scale coating to maintain its protective functions for longer periods.
Solution Approach 2:
The invention changes the coating formation method from purely thermal (heat treatment only) to a combination of mechanical deposition (electric-arc spraying) and thermal oxidation. This parameter change in the coating formation process significantly reduces the total time required while maintaining or improving coating performance.
3Productivity
If billets made of stainless steel are pierced, then production is performed, but the coating wears off significantly leading to very short plug life
Solution Approach 1:
The invention applies a composite coating structure consisting of an inner layer made of iron and iron oxides deposited by electric-arc spraying, and an outer layer of oxidized scale formed by heat treatment. This composite structure combines the high adhesion and wear resistance of the sprayed coating with the heat insulation and seizure resistance of the oxidized scale layer, resolving the contradiction between coating durability and functional performance.
Solution Approach 2:
The invention performs electric-arc spraying to form the iron and iron oxides coating on the plug surface before heat treatment. This preliminary action creates a robust foundation layer that prevents premature wear and exposure of the base material, allowing the subsequent oxidized scale coating to maintain its protective functions for longer periods.
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 effectively prevents coating peeling and seizure, extending the plug's life by maintaining coating integrity and reducing heat-related issues during piercing, allowing for longer service life and improved efficiency.
Implementation Method 1
forming a body coating on a surface of the plug body by performing arc spraying using iron wire
Implementation Method 2
forming a surface-layer coating on the body coating by performing arc spraying using iron wire at a spray distance shorter than that at completion of the formation of the body coating
Data Source
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AI summary
A plug that achieves prevention of peel-off of the coating and a method of manufacturing such a plug are provided. A plug (10) is used for piercing a billet. The plug (10) includes a plug body (1), a body coating (2), and a surface-layer coating (3). The body coating (2) is provided on a surface of the plug body. The body coating (2) contains iron and iron oxides. The surface-layer coating (3) is provided on the body coating (2). The surface-layer coating (3) contains iron and iron oxides. The surface-layer coating (3) has a porosity lower than that of a region of the body coating (2) adjacent to the surface-layer coating (3) and having a thickness equal to that of the surface-layer coating (3).