Piercing Plug Oxide Scale Layer Removal via Controlled Thermal Treatment
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Solution Overview
Problem
The existing methods for manufacturing plugs used in piercing and rolling metal materials face challenges in easily removing the outer oxide scale layer with low load, leading to surface irregularities and defects in the metal pipes due to the high workload required for peeling off the outer scale layer.
Innovation Solution
A method involving thermal treatment of the plug in an atmosphere with at least 2.0 vol.% oxygen at temperatures between 950°C and 1000°C, resulting in an outer scale layer with pores that can be easily peeled off with a low load, while maintaining the inner scale layer's dense structure, thereby reducing the workload and surface defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the outer scale layer is made easily peelable by conventional thermal treatment, then the inner scale layer becomes too dense and difficult to remove, but if the outer scale layer is made too easily removable, then the inner scale layer structure deteriorates
Solution Approach 1:
The patent applies parameter changes by precisely controlling the oxygen concentration (1.0-20.0 vol.%, preferably 5.0-15.0 vol.%, more preferably 8.0-12.0 vol.%) and temperature (950-1050°C) during thermal treatment to create a differentiated oxide scale structure. This allows the outer scale layer to be easily removable while maintaining the inner scale layer's dense structure for adhesion during piercing and rolling operations.
Solution Approach 2:
The patent creates local quality differences within the oxide scale layer by forming an outer scale layer with different properties (easier to remove) than the inner scale layer (denser structure). The controlled thermal treatment in specific oxygen atmospheres creates this gradient structure where the outer portion has different composition and morphology from the inner portion, enabling selective removal characteristics.
2Ease of manufacture
If high load is applied to remove the outer scale layer in advance, then the outer scale layer can be removed, but the workload and complexity of the process increases significantly
Solution Approach 1:
The patent applies preliminary action by performing thermal treatment during the plug manufacturing process itself to create an oxide scale layer with predetermined removal characteristics. This preliminary structuring of the scale layer during manufacturing eliminates the need for complex post-manufacturing removal operations, as the outer scale layer becomes easily removable through simple mechanical or thermal actions during subsequent piercing and rolling processes.
3Reliability
If the oxide scale layer is formed on the plug surface to prevent wear and dissolution, then the plug surface protection is improved, but the outer scale layer peels off during piercing and rolling causing surface irregularities
Solution Approach 1:
The patent applies segmentation by dividing the oxide scale layer into distinct outer and inner scale layers with different functions. The inner scale layer provides protective adhesion to the plug surface during piercing and rolling, while the outer scale layer is designed to be easily removed. This segmentation prevents the entire scale layer from peeling off and causing surface defects, as only the outer layer is removed while the inner layer remains to protect the plug.
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 allows for the easy removal of the outer scale layer with a lower load, reducing surface irregularities and defects in the metal pipes, and maintaining the inner scale layer's dense structure for improved adhesion and wear resistance.
Implementation Method 1
an oxide scale layer which includes an inner scale layer formed on a surface of the plug material and an outer scale layer formed on the inner scale layer by thermally treating the prepared plug
Data Source
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AI summary
A plug material having a prescribed shape is prepared, the prepared plug material is thermally treated in a heat treatment atmosphere that contains at least 1.0 vol.% oxygen at a heat treatment temperature of at least 950°C and less than 1050°C and thus a plug having an oxide scale layer 30 on the surface is manufactured. According to the manufacturing method, pores PO that extend along the surface SF of the plug material are formed under outer scale layer 20 in the oxide scale layer 30, which allows cracks to be more easily propagated in the outer scale layer 20. Therefore, the outer scale layer 20 is more easily peeled off than the conventional one.