Precision Seamless Pipe Forming with Warm Rolling and Expansion
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Solution Overview
Problem
Conventional methods for preparing high-performance difficult-to-deform metal precision seamless pipes face challenges such as high production costs, low efficiency, and poor precision, making it difficult to achieve stable and continuous production of pipes with specific dimensions and performance requirements.
Innovation Solution
A method involving heat treatment, large rolling angle drilling, external and internal grinding, straightening, four-roller warm-rolling, and precise cold-rolling, along with optional warm-drawing and warm-expansion processes, to reduce diameter and wall thickness while ensuring high dimensional accuracy and crystal grain size, is employed to produce high-performance seamless pipes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional multiple forgings and cold-rolling are used to obtain finer crystal grain size and high metal plasticity, then material performance is improved, but production efficiency deteriorates due to slow hammerhead speed and multiple heating treatments
Solution Approach 1:
The patent changes the temperature parameter from cold state (conventional) to warm state (200-500°C) during rolling, which reduces metal resistance and improves plasticity. This allows achieving fine crystal grain size and high metal plasticity without requiring multiple slow forging passes, thereby improving production efficiency while maintaining material performance.
Solution Approach 2:
The patent performs preliminary heating of the metal blank before rolling to achieve uniform temperature distribution throughout the workpiece. This preliminary thermal preparation ensures that the metal is in the optimal state for deformation during rolling, eliminating the need for multiple subsequent heating treatments and improving production efficiency.
2Device complexity
If conventional cold-rolling mill is used for forming, then equipment simplicity is maintained, but deformation amount per pass is limited requiring large number of passes
Solution Approach 1:
The patent changes the operating temperature parameter from cold to warm state (200-500°C), which fundamentally alters the metal's deformation characteristics. This parameter change enables much larger deformation amounts per pass compared to conventional cold-rolling, reducing the number of required passes from multiple to just one or two, thereby improving productivity without significantly increasing equipment complexity.
3Ease of manufacture
If conventional cold-rolling is used, then process simplicity is maintained, but wall thickness reduction is insufficient and process flexibility is poor
Solution Approach 1:
The patent introduces warm-rolling temperature (200-500°C) as a new parameter that fundamentally changes the deformation capabilities. This enables sufficient wall thickness reduction and accommodates various product specifications (Φ3mm-Φ800mm diameter, 0.5mm-30mm wall thickness) while maintaining relatively simple equipment, thus improving both process flexibility and ease of manufacture.
4Strength
If multiple forgings and heating treatments are performed, then metal plasticity is improved, but production cost increases
Solution Approach 1:
The patent changes the temperature parameter from cold to warm state, which improves metal plasticity and enables sufficient deformation in fewer passes. This single warm-rolling process replaces multiple conventional cold-rolling passes and heating treatments, reducing energy consumption and production costs while achieving the required metal plasticity and material performance.
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 method significantly improves production efficiency, reduces costs, and enables the flexible production of pipes with precise dimensions and material characteristics, achieving high-performance and high-precision seamless pipes.
Implementation Method 1
performing a heat treatment: heating a solid metal blank after sizing to reduce a metal resistance
Implementation Method 2
processing the straightened hollow blank pipe with the four-roller warm-rolling to perform large-deformation isothermal-rolling, thereby obtaining a metal seamless pipe with a reduced diameter
Data Source
AI summary
A method for preparing a high-performance difficult-to-deform metal precision seamless pipe includes steps of performing a heat treatment; drilling; externally grinding; internally grinding; straightening; performing four-roller warm-rolling; performing warm-drawing to reduce a diameter; performing warm-expansion to reduce a wall thickness and increase the diameter; performing precise cold-rolling; degreasing; brightening; performing surface grinding; cleaning dust; detecting flaws; testing metal structure performance; and sizing and packaging. By cycling the warm-drawing, the warm-expansion, and the precision cold-rolling, key indicators such as product dimensional accuracy, surface quality, material properties, and crystal grain size can be collaboratively controlled, to achieve higher accuracy, better performance, and more outstanding extreme specifications. Product requirements of different hard-to-deform metal materials and different product specifications can be satisfied, to flexibly prepare metal pipe products with different material characteristics, which greatly improves production efficiency and effectively reduces production costs.