Thin-Walled Ring Shell Hot-Press Bending with Internal Gas Pressure
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Solution Overview
Problem
Current methods for forming large-scale thin-walled ring shells, such as tailor welded, stamping, dieless hydro-bulging, and rotary draw bending, face issues like stress concentration, poor dimensional accuracy, high manufacturing costs, limited size suitability, and difficulty in bending ductile alloys like aluminum, magnesium, and titanium alloys at room temperature, which restrict their application in high-pressure and large-scale applications.
Innovation Solution
An apparatus and method utilizing hot-press bending with internal gas pressure, featuring a sealed pipe assembly, die with controlled temperature zones, electrodes for heating, and a compressed gas source to improve heating efficiency and reduce costs, allowing for the formation of large-scale thin-walled ring shells with controlled temperature and pressure to prevent cracking and wrinkling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by stationary object
If conventional furnace heating is used for large-scale ring shells, then the heating is comprehensive, but the equipment cost is high and heating efficiency is low
Solution Approach 1:
The heating process is segmented into two distinct phases: first, resistance heating elements concentrate energy at specific locations to raise the material to forming temperature; second, induction heating zones provide localized thermal energy during the forming operation. This segmentation eliminates the need for a single large furnace, reducing equipment cost while maintaining heating effectiveness.
Solution Approach 2:
The conventional mechanical furnace heating system is replaced with an electrical heating system using resistance heating elements and induction heating zones. This substitution provides more precise temperature control, faster heating rates, and reduced equipment complexity, thereby improving heating efficiency and lowering equipment costs.
2Ease of manufacture
If aluminum alloy, magnesium alloy or titanium alloy is bent at room temperature, then the process is simple, but the material is difficult to bend and easy to crack
Solution Approach 1:
The material temperature parameter is changed from room temperature to elevated temperature during the bending process. By heating the aluminum alloy, magnesium alloy, or titanium alloy to appropriate temperatures, the material exhibits improved ductility and formability, allowing complex bending operations without cracking while maintaining process simplicity through automated heating and forming integration.
3Ease of manufacture
If stamping method is used for ring shell, then the ring shell can be formed, but the springback is large resulting in poor dimensional accuracy
Solution Approach 1:
The temperature parameter is changed from cold stamping to hot forming. By performing the stamping operation at elevated temperatures, the material exhibits reduced elastic recovery (springback) and improved plastic deformability, resulting in better dimensional accuracy while maintaining the forming capability provided by the stamping method.
4Ease of manufacture
If dieless hydro-bulging method is used, then the ring shell can be deformed, but the inner surface is easy to lose stability and wrinkle
Solution Approach 1:
The temperature parameter is changed from cold hydro-bulging to hot forming. At elevated temperatures, the material exhibits improved ductility and reduced tendency for wrinkling and surface instability during deformation. This allows the hydro-bulging method to achieve the required deformation capability while maintaining surface stability and manufacturing precision.
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 enhances heating efficiency, reduces manufacturing costs, and ensures coordinated deformation without cracks or wrinkles, enabling the formation of large-scale thin-walled ring shells with improved dimensional accuracy and ductility, particularly suitable for high-temperature alloys like titanium.
Implementation Method 1
the convex part of the first die is provided with a plurality of first cooling channels and a plurality of first heating devices, and both the first cooling channels and the first heating devices are used to adjust the temperature of the first die cooperatively; the concave part of the second die is provided with a plurality of second cooling channels and a plurality of second heating devices, and both the second cooling channels and the second heating devices are used to adjust the temperature of the second die cooperatively
Implementation Method 2
heating the sealed pipe assembly by the current self-resistance improves the heating efficiency of pipe assemblies
Implementation Method 3
a compressed gas source device connected with the first head or the second head, and the compressed gas source device is used to charge the compressed gas into the sealed pipe assembly
Implementation Method 4
the sealed pipe assembly, in which the compressed gas has been charged, is placed between the convex part of the first die and the concave part of the second die of a die with different controlled temperature zones, and temperatures of the first die and the second die are controlled to perform a press bending
Data Source
AI summary
The present disclosure discloses an apparatus and a method for forming a large-scale thin-walled ring shell by hot-press bending with internal gas pressure. The method comprises: welding a first head and a second head to the pipe; arranging a first electrode and a second electrode at the two ends of the pipe; charging compressed gas to the heated sealed pipe assembly; placing the sealed pipe assembly between the convex part of the first die and the concave part of the second die, controlling the temperatures of the first and second dies to perform press bending; increasing the gas pressure in the bent sealed pipe assembly, to attach the bent sealed pipe assembly to the die cavity profile; discharging the compressed gas, cutting the first head, second head and extra material to obtain a formed ring shell segment; welding formed ring shell segments to obtain a large-scale thin-walled ring shell.