Arc-Sprayed Plug Coating for Seamless Tube Piercing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing plug designs for piercing-rolling mills face issues with inner surface flaws in seamless tube production due to high friction and wear, leading to reduced plug life and inefficient lubrication, particularly with scale coating formation and reprocessing heat treatments.
Innovation Solution
A plug design featuring a convex front edge, cylindrical, and trunk portions with a lubricant ejection hole on the cylindrical surface, coated with oxides and Fe using arc spraying, optimizing the oxide ratio and coating thickness to enhance lubrication and prevent wear, while avoiding scale formation and deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a plug is used in piercing-rolling without optimized coating, then inner surface flaws occur due to high friction and wear, but adding conventional scale coating requires lengthy heat treatment (several hours to tens of hours) and causes clogging of the ejection hole
Solution Approach 1:
The invention changes the coating formation method from conventional heat treatment to arc spraying, and optimizes the oxide ratio parameter in the coating composition. By controlling the oxide ratio to be 20-80%, the coating provides effective lubrication and wear protection without requiring lengthy heat treatment processes, reducing fabrication time from several hours to tens of hours to just arc spraying operation time.
Solution Approach 2:
The invention uses a composite coating material consisting of metal particles and oxide particles where the oxide ratio is controlled at 20-80%. This composite structure combines the lubrication properties of oxides with the metallic properties of the base material, achieving both wear protection and reduced fabrication time without the clogging issues of conventional scale coatings.
2Strength
If conventional scale coating is formed by heat treatment, then wear protection is provided, but the ejection hole becomes clogged due to scale formation during heat treatment
Solution Approach 1:
The invention changes the oxide ratio parameter in the coating to 20-80%, which is lower than conventional scale coatings. This optimized oxide content provides sufficient wear protection while preventing excessive scale formation that would clog the ejection hole during heat treatment or arc spraying processes.
Solution Approach 2:
The coating is applied selectively to specific regions of the plug: the front edge portion, cylindrical portion, and trunk portion. By controlling the coating distribution and oxide ratio in these specific areas, the invention provides wear protection where needed while avoiding ejection hole clogging in the cylindrical portion where the ejection hole is located.
3Temperature
If the oxide ratio in the coating is increased to improve heat insulation, then heat insulation performance improves, but the coating may peel off more easily
Solution Approach 1:
The invention optimizes the oxide ratio parameter to a specific range of 20-80%, balancing heat insulation performance with coating adhesion. This optimized ratio ensures sufficient heat insulation for the piercing process while maintaining strong bonding between the coating and the plug base material, preventing coating peeling during repeated use.
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 inner surface flaws, extends plug life, and reduces fabrication time by ensuring consistent lubrication and improved heat insulation, with the arc-sprayed coating maintaining effectiveness through multiple piercing cycles.
Implementation Method 1
a coating comprising oxides and Fe that is formed on the base metal surface of each of the front edge portion as well as the trunk portion by arc spraying using an iron wire
Implementation Method 2
a lubricant ejection hole that runs through the trunk portion from the mandrel joint and that opens on the surface of the cylindrical portion
Data Source
Figure 1~2
Figure 3(a)~3(b)
Figure 4~5
AI summary
A plug includes a front edge portion having a convex curvature; a cylindrical portion having a truly or nearly cylindrical shape; a trunk portion having an outer diameter gradually increasing toward a rear edge thereof; a mandrel joint provided in a rear edge portion of the plug; a lubricant ejection hole running through the trunk portion from the mandrel joint that opens on the surface of the cylindrical portion; and a coating comprising oxides and Fe that is formed on the base metal surface of each of the front edge portion as well as the trunk portion by arc spraying using an iron wire. In this way, the plug can prevent inner surface flaws from occurring in a hollow blank that is deformed by piercing-rolling, and can extend its life without requiring a long time for making it.