Electrically Assisted Tooth-Shaped Rolling for Crack-Free Gradient Sheets
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Solution Overview
Problem
Existing methods struggle to efficiently prepare gradient ultrafine-grained sheets from difficult-to-deform materials like TC4, GH4169, and Ti2AlNb-based alloys, which are prone to cracking and deformation springback, limiting their application in high-performance components such as aerospace parts.
Innovation Solution
An electrically-assisted tooth-shaped rolling process using rib-forming, rib-flatting, and straightening pressure rollers with controlled pressing and electrification to achieve multi-pass rolling, creating a gradient ultrafine-grained structure through localized deformation and recrystallization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If large plastic deformation method is used to prepare gradient ultrafine-grained sheet, then grain refinement and strength improvement are achieved, but cracking and deformation springback occur in difficult-to-deform materials
Solution Approach 1:
The patent applies electric field parameters (pulse current density, frequency, duty cycle) to change the material's deformation characteristics during rolling. The electric field parameters are optimized to reduce deformation resistance and prevent cracking in difficult-to-deform materials like TC4, GH4169, and Ti2AlNb alloys
Solution Approach 2:
The patent replaces part of the mechanical deformation system with an electric field system. Instead of relying solely on mechanical rolling pressure, an electric field is introduced to assist the deformation process, reducing the mechanical load and preventing material failure
2Manufacturing precision
If physical and chemical deposition method is used, then gradient layer is formed, but equipment requirements are high, process flow is complex, and preparation time is long
Solution Approach 1:
The patent replaces complex physical and chemical deposition systems with a simpler electrically-assisted mechanical rolling system. The electric field assists the rolling process to achieve gradient ultrafine-grained structure without requiring complex deposition equipment or multi-step processes
Solution Approach 2:
The patent changes the approach from controlling deposition parameters (in physical/chemical methods) to controlling electric field and rolling parameters. This simplifies the process by using readily controllable electrical parameters and mechanical rolling variables
3Ease of manufacture
If conventional rolling method is used on difficult-to-deform materials, then material is processed, but deformation resistance is high and cracking occurs
Solution Approach 1:
The patent introduces an electric field system to assist the mechanical rolling process. The electric field reduces the material's deformation resistance by affecting dislocation motion and crystal structure, making it easier to process difficult-to-deform materials without causing cracking
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 process enables high-performance and short-process preparation of gradient ultrafine-grained sheets with improved strength-plasticity matching, suitable for large-scale production of aerospace components, avoiding cracks and uneven deformation.
Implementation Method 1
local heating is caused at the different positions on the surface of the prefabricated sheet due to passage of current
Implementation Method 2
electrically-assisted tooth-shaped rolling process... electric field assisted processing method
Data Source
AI summary
An electrically-assisted tooth-shaped rolling process and device for preparing a gradient ultrafine-grained sheet is provided. A rib-forming pressure roller, a rib-flatting pressure roller and a straightening pressure roller are adopted to sequentially roll relative to a surface of a sheet under a preset pressing force. The surface of the sheet is driven, under a rib forming process, to generate large deformation in micro-area to crush and refine grains, and under a rib flatting process to generate reverse large deformation in micro-area. Large deformation areas in the rib forming process and the rib flatting process are staggered to further crush and refine the grains. A cold straightening process drives the sheet to be restored to an original shape, so that the sheet becomes the gradient ultrafine-grained sheet with a decreasing grain size gradient from an interior to a surface layer.