Piercing Plug Oscillation for Seamless Steel Pipe Eccentricity
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Solution Overview
Problem
Existing methods for producing seamless steel tubes struggle to maintain low eccentricity in wall thickness during the piercing process, leading to increased production costs and material waste due to uncontrollable shifting of the piercing plug axis, resulting in high eccentricity values of 5 to 10% or more.
Innovation Solution
The method involves controlling the rotational motion of the piercing plug axis by superimposing vibrations of different frequencies and amplitudes, without altering the plug's rotation, using a freely rotating shaft with low friction gliding surfaces and an eccentric connection between the piercing plug and plug bar, and applying a high-frequency rotational motion to compensate for wall thickness deviations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the piercing plug axis is allowed to shift freely during rotation, then the device complexity is reduced and ease of operation is improved, but the manufacturing precision of wall thickness deteriorates with eccentricity values of 5 to 10% or more
Solution Approach 1:
The patent applies dynamics by allowing the piercing plug axis to perform controlled oscillatory movements around the billet center line during rotation, rather than being rigidly fixed. This dynamic positioning enables the plug to adapt to varying forces while maintaining sufficient control to prevent excessive eccentricity, resolving the contradiction between operational freedom and manufacturing precision
Solution Approach 2:
The patent changes the parameter of plug axis position from a fixed state to a dynamically varying state with controlled oscillations. By controlling the amplitude and frequency of these oscillations, the system maintains wall thickness uniformity while allowing the plug to respond to operational forces, thus resolving the contradiction between ease of operation and manufacturing precision
2Reliability
If greater wall thickness is produced to safely maintain minus tolerance, then the reliability of the tube is improved, but the loss of substance increases due to additional material expenditure
Solution Approach 1:
The patent employs hydraulic or pneumatic actuators to control the oscillatory movement of the piercing plug axis. These fluid-based systems provide precise, controllable forces that maintain the plug position within optimal ranges, ensuring wall thickness uniformity and allowing production of tubes with minimal wall thickness while maintaining reliability
Solution Approach 2:
The patent implements feedback control by monitoring the position of the piercing plug axis and adjusting its oscillatory movement accordingly. This feedback mechanism ensures that the plug remains properly positioned despite varying operational forces, maintaining wall thickness uniformity and enabling production of tubes with minimal wall thickness that still meet reliability requirements
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 reduces eccentricity in the rolled tubes, minimizing wear on the piercing plug and preventing inner defects, while maintaining stable material flow and reducing production costs by keeping wall thickness deviations within tighter tolerances.
Implementation Method 1
low friction gliding surfaces
Implementation Method 2
superimposing vibrations of different frequencies and amplitudes
Data Source
AI summary
The invention relates to a method for producing seamless steel tubes in a rolling mill train with one or more consecutively positioned longitudinal or cross-rolling units and an inside tool which is used as mandrel bar or piercing plug during the rolling process. The aim is to provide a method to reduce the eccentricity of the rolling stock considerably.To achieve this, the longitudinal axis of the inside tool is forced by means of an apparatus to a movement in a distance to the longitudinal axis of the rolling stock. Simultaneously the rotation of the tool around its axis is kept, driven by the rolling stock during rolling.