Ellipsoidal Shell Forming via Self-Resistance Heating
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Solution Overview
Problem
The conventional forming methods for large-diameter aluminum alloy ellipsoidal shells face challenges due to low room temperature formability and high manufacturing costs, particularly with the risk of rapture defects in weld zones during dieless hydroforming at normal temperatures.
Innovation Solution
A gas pressure forming method utilizing current self-resistance heating to improve the formability of aluminum alloy ellipsoidal shells, where polar plates and side petal plates are assembled and welded into a closed polyhedral shell, then heated and pressurized with compressed gas to achieve the desired curvature, avoiding the need for large-sized heating furnaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If dieless hydroforming is performed at room temperature, then equipment cost is reduced, but rapture defects occur in weld zones due to low formability
Solution Approach 1:
The patent changes the temperature parameter from room temperature to elevated temperature (heating the workpiece to 200-500℃) to improve the formability and ductility of aluminum alloy and its welded joints, preventing rapture defects during dieless hydroforming while maintaining equipment simplicity
2Temperature
If heating is carried out in a large-sized heating furnace, then temperature uniformity can be controlled, but equipment cost and technical risk increase significantly
Solution Approach 1:
The patent replaces the mechanical heating system (large-sized heating furnace) with an electrical heating system (current self-resistance heating), where electrodes are directly contacted with the workpiece to generate heat through electrical resistance, achieving uniform temperature distribution without requiring complex large-scale furnaces
Solution Approach 2:
The workpiece itself serves as the heating element through current self-resistance heating, where the material's own electrical resistance generates heat when current passes through it, eliminating the need for external heating equipment and achieving self-heating with uniform temperature distribution
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 enhances the formability of aluminum alloy ellipsoidal shells by efficiently and uniformly heating the materials, reducing manufacturing costs and technical risks associated with large-diameter shell production, while preventing rapture defects in weld zones.
Implementation Method 1
disposing an electrode on the closed polyhedral shell to form a closed current loop, and energizing and heating the closed polyhedral shell to a preset forming temperature
Implementation Method 2
the closed polyhedral shell is pressurized into an ellipsoidal shell by using compressed gas under a heating condition
Data Source
AI summary
The present invention discloses a gas pressure forming method of an ellipsoid. The formability of a closed polyhedral shell including polar plates, ellipsoidal side flap plates, and welded joints is improved, and the closed polyhedral shell is pressurized into an ellipsoid by using compressed gas under a heating condition, specifically comprising: assembling and welding two polar plates and ellipsoidal side flap plates into a closed polyhedral shell; disposing an electrode on the closed polyhedral shell, energizing and heating to a preset temperature, and then inflating compressed gas into the shell; deforming the closed polyhedral shell under the action of internal gas pressure, stopping inflating gas until a desired curvature shell is obtained, discharging gas, and removing the electrode to obtain a formed ellipsoid.