Boric Acid Lubricant for Seamless Steel Pipe Plug Life
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Solution Overview
Problem
The existing methods for producing seamless steel tubes/pipes using the Mannesmann process face challenges in extending the life of the plug during piercing-rolling without reducing production efficiency, especially when dealing with high alloy steels, as the oxide scale film wears quickly, leading to increased friction, seizing, and reduced plug lifespan.
Innovation Solution
A method involving the application of a boric acid-based aqueous solution as a lubricant on an arc-sprayed protection film formed on the plug surface, which includes boron oxide, boric acid, and amine borate, applied when the plug cools to a specific temperature, enhances the plug's life and piercing efficiency by reducing friction and preventing seizing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a water glass-based aqueous solution is applied as lubricant on the scale film, then friction resistance is reduced and seizing is prevented, but the scale film peels off excessively and production efficiency is reduced due to long evaporation time
Solution Approach 1:
The patent changes the chemical composition parameters of the lubricant from water glass-based to boric acid-based (specifically boron oxide, boric acid, and amine borate), and optimizes the application temperature parameter (applying when plug surface temperature is 100-200°C). This parameter change resolves the contradiction by providing effective lubrication without the peeling and long evaporation issues of water glass-based solutions.
2Productivity
If the plug is used repetitively for piercing-rolling, then production efficiency is maintained, but the scale film wears out and plug life is reduced
Solution Approach 1:
The patent applies lubricant to the plug surface before each piercing operation (when the plug has cooled to 100-200°C). This preliminary action of lubrication before use prevents scale film wear and extends plug life, allowing the plug to be used repetitively without degradation.
3Reliability
If high alloy steel such as stainless steel is produced, then product quality is improved, but the scale film wear is intensified and plug life is tremendously decreased
Solution Approach 1:
The patent introduces a boric acid-based lubricant as an intermediary substance between the plug and the high alloy steel billet. This lubricant film prevents direct contact and severe wear caused by high alloy materials, thereby extending plug life while maintaining the ability to produce high quality stainless steel and other high alloy 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
This approach significantly increases the plug's life and maintains the efficiency of the piercing-rolling process by improving thermal insulation and reducing friction, allowing for more efficient production of seamless steel tubes/pipes, especially those made from high alloy steels.
Implementation Method 1
a film of oxide scale is formed on the surface of the base metal in advance by heat treatment before the plug is used for piercing-rolling. During piercing-rolling, the scale film on the plug surface blocks the heat transfer from the billet to the plug base metal, and serves as a protection film for preventing seizing
Implementation Method 2
a lubricant is used and laminated onto the scale film on the plug surface so that the friction resistance between the plug and the billet is reduced and seizing therebetween is prevented
Implementation Method 3
when the plug is cooled after piercing-rolling and is successively used for piercing-rolling in a repetitive manner, the cooling is interrupted at the moment when the surface temperature of the plug becomes not more than 150°C
Data Source
AI summary
When performing piercing-rolling by use of a plug with a protection film on its surface, applying a lubricant made of an aqueous solution containing a total of 5 to 30% mass% of one or more of boron oxide, boric acid, and amine borate to the protection film on the plug surface, and using this plug for piercing-rolling makes it possible to realize the increase of the life of plug for piecing-rolling without reducing the efficiency of piercing-rolling, consequently allowing the efficient production of a seamless steel tube/pipe. Moreover, it is preferable that the plug is cooled after the piecing-rolling, the application of the above described lubricant is performed when the surface temperature of the front edge of plug decreases to 100°C or less, and the plug is reused for the piercing-rolling. In this occasion, it is preferable that the protection film on the plug surface is formed by arc spraying iron wire material onto the surface of the base metal of plug, and comprises oxides and Fe.