Arc-Sprayed Plug Film Adhesion via Segmented Angle Control
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Solution Overview
Problem
Conventional plugs for piercing-rolling in seamless steel tube/pipe production experience reduced durability due to unstable film adhesiveness, especially when piercing long billets or high-temperature strength billets, leading to frequent replacements and inefficiencies.
Innovation Solution
A method involving arc-spraying iron wires onto the plug base metal, dividing the surface into sections, and maintaining an intersection angle of 35 to 90 degrees between the spraying stream and the surface to form a film with enhanced adhesiveness and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If arc-spraying is performed on the entire plug surface simultaneously using multiple spray guns, then production efficiency is improved, but film adhesiveness becomes unstable leading to premature plug failure
Solution Approach 1:
The plug surface is divided into multiple sections (tip end portion, front-half body portion, rear-half body portion), and arc-spraying is performed sequentially on each section rather than simultaneously on the entire surface. This segmentation approach maintains stable film adhesiveness by ensuring proper intersection angles while preserving production efficiency through optimized sequencing
Solution Approach 2:
The spray gun position and orientation are dynamically adjusted during the arc-spraying process to maintain the optimal intersection angle (35° to 90°) between the spraying stream and the plug surface. This dynamic adjustment ensures consistent film quality across different sections of the plug while accommodating the curved surface geometry
2Ease of manufacture
If the intersection angle between spraying stream and plug surface is not controlled, then the arc-spraying process is simpler, but film adhesiveness deteriorates causing early plug exhaustion
Solution Approach 1:
The intersection angle between the spraying stream and the plug surface is controlled within a specific range (35° to 90°) to optimize film adhesiveness. By establishing this parameter range, the process achieves reliable film formation without excessive complexity, as the angle control can be implemented through standard positioning mechanisms
3Reliability
If scale film is used on plug surface, then thermal insulation and seizing prevention are provided, but the film abrades quickly especially with high alloy steel billets
Solution Approach 1:
Instead of using conventional scale film, an arc-sprayed composite film containing both metal particles and oxide particles is formed on the plug surface. This composite structure provides superior wear resistance compared to scale film, especially when processing high alloy steel billets, while maintaining the thermal insulation and seizing prevention functions
Solution Approach 2:
The chemical composition and microstructure of the protective film are changed from scale film to arc-sprayed metal-oxide composite film. This parameter change in film composition significantly enhances wear resistance and extends plug durability life when processing high alloy steel products
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 method secures firm adhesiveness and significantly enhances the durability life of the plug, allowing for longer piercing operations without film peeling or seizing, thereby improving production efficiency.
Implementation Method 1
an arc-spraying step in which iron wires are melted, and molten material is sprayed onto a surface of a base metal of a plug by use of an arc-spray gun, so as to form a film containing Fe oxide and Fe on the surface of the base metal of the plug
Implementation Method 2
the scale film on the surface of the plug insulates heat transfer from the billet to the base metal of the plug
Implementation Method 3
the scale film on the surface of the plug insulates heat transfer from the billet to the base metal of the plug, and also prevents seizing between the billet and the plug
Data Source
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AI summary
A method for producing a plug for use in a piercing rolling mill for producing a seamless steel tube/pipe includes an arc-spraying step of melting iron wires, and spraying molten material thereof onto a surface of a base metal of a plug by use of an arc-spray gun, so as to form a film containing oxide and Fe on the surface of the base metal of the plug. In the arc-spraying step, the surface of the base metal of the plug is divided into plural sections along an axial direction of the plug (for example, two sections: the tip end portion and the body portion), and in turn, the arc-spraying is separately carried out in each of the plural sections while an intersection angle between the center line of a spraying stream from the arc-spray gun and the surface of the plug base metal is maintained within a range of 35 degrees to 90 degrees. This method secures firm adhesiveness of the arc-sprayed film formed on the surface of the plug, and realizes steady enhancement of durability life of the plug.