Seamless Large Dome Forming with Staged Hot Preform Deformation
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Solution Overview
Problem
Existing methods for manufacturing large-sized domes, such as cryogenic tank domes, are costly and require specialized equipment or are limited by the dimensions of forging presses, necessitating welding and rigorous ultrasonic inspection, or are restricted to small pieces due to force requirements.
Innovation Solution
A method involving hot forging and shaping of a semi-finished product to create a preform with distinct convexities and thicknesses, followed by hot deformation under a press to form a seamless dome without welding, using available forging presses with limited dimensions and forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If closed-die forging is used to manufacture single-piece domes, then the number of shaping operations is reduced to one, but the method is limited to small pieces due to limited dimensions of existing forging presses and very high forces required
Solution Approach 1:
The manufacturing process is segmented into multiple sequential stages: initial upsetting to form a blank, hot shaping to create a preform with distinct convexities and thicknesses, and final hot deformation under a press. This segmentation allows each stage to be performed on equipment with limited dimensions and forces, while achieving a final large-sized dome that would be impossible to produce in a single operation.
Solution Approach 2:
The preform is created in advance with specific geometric characteristics (distinct convexities and thicknesses in different portions) that facilitate the final deformation step. This preliminary shaping prepares the material distribution and geometry so that the subsequent hot deformation can efficiently produce the final dome shape using limited press capacity.
2Length of stationary object
If sheets are stamped and assembled to form domes, then large-sized domes can be manufactured, but costly operations including welding and rigorous ultrasonic inspection are required
Solution Approach 1:
Multiple sheet metal components that would traditionally be stamped, assembled, and welded together are merged into a single seamless dome produced by progressive hot deformation. The process integrates forming, shaping, and final deformation into one continuous operation, eliminating the need for separate welding and inspection operations.
Solution Approach 2:
The material undergoes progressive parameter changes through controlled hot deformation: temperature maintenance throughout the process, progressive shape transformation from blank to preform to final dome, and controlled thickness distribution. These parameter changes enable the material to be formed into large complex shapes without welding while maintaining structural integrity.
3Adaptability or versatility
If available forging presses with limited dimensions and forces are used, then equipment accessibility is improved, but manufacturing large-sized domes without welding becomes challenging
Solution Approach 1:
The process utilizes the third dimension (thickness variation) to solve the two-dimensional limitation of press size. By creating a preform with distinct thicknesses and convexities in different portions, the process enables material redistribution during final deformation, allowing large surface area domes to be formed from smaller initial blanks that fit within limited press dimensions.
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
Enables the production of large-sized seamless domes efficiently, reducing the need for welding and specialized equipment, while ensuring homogeneous mechanical properties and grain orientation, thus lowering costs and improving manufacturing feasibility.
Implementation Method 1
hot forging by upsetting the semi-finished product to form a blank
Implementation Method 2
hot forging by upsetting the semi-finished product
Implementation Method 3
hot shaping of the blank to create a preform having a developed surface less than or equal to the developed surface of the wall
Implementation Method 4
hot shaping of the blank
Implementation Method 5
hot deformation of the preform under a press between a die and a punch to form the wall
Implementation Method 6
hot deformation of the preform under a press between a die and a punch
Data Source
AI summary
The method comprises the following steps:providing a semi-finished product (11);hot forging by upsetting the semi-finished product (11) to form a blank (13) with a developed surface greater than that of the semi-finished product (11) and less than the developed surface of the wall (3) of the dome;hot forming of the blank (13) to create a preform (15) having a developed surface less than or equal to the developed surface of the wall (3), the preform (15) comprising at least two consecutive portions (19, 21) extending radially in the continuation of one another away from the central axis (A-A), such that for all the portions (19, 21), the average thicknesses and/or convexities of two consecutive portions (19, 21) are distinct;hot deformation of the preform (15) under a press between a die and a punch to form the wall (3).