QCr0.8 Tapered Cylindrical Ring Forming With Radial-Axial Rolling
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Solution Overview
Problem
The traditional forging method for QCr0.8 alloy tapered cylindrical rings is inefficient, requiring large and expensive equipment, excessive raw materials, and resulting in low yield strength and non-uniformity due to chromium segregation, which affects the reliability of thrust chamber components in liquid propellant rocket engines.
Innovation Solution
A method involving multiple steps: heating and upsetting-stretching a standard cylindrical QCr0.8 alloy raw material to form a primary blank, followed by heating and chamfering to create a secondary blank, then backward extrusion and machining to form a preform, local bulging to match the drive roller shape, and finally radial-axial ring rolling to produce a tapered cylindrical ring, reducing material consumption and enhancing structural uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If traditional forging method with 800,000 KN squeezing press machine is used, then large-size tapered cylindrical ring can be formed, but equipment cost and complexity increase significantly
Solution Approach 1:
The forming process is divided into multiple stages: pre-forming stage using a small-tonnage press (100-500 KN) to create a preform, followed by a ring rolling stage to achieve the final tapered cylindrical shape. This segmentation allows each stage to use appropriately-sized equipment, avoiding the need for a single large 800,000 KN press while still producing large-size products.
Solution Approach 2:
A preform is created in advance with a shape close to the final product before the ring rolling process. This preliminary action prepares the workpiece in a suitable form that reduces the complexity and tonnage requirements of the subsequent forming operation, enabling the use of smaller, more manageable equipment.
2Volume of moving object
If traditional forging method is used, then tapered cylindrical ring can be formed, but raw material consumption exceeds 1.4 tons with utilization rate less than 5%
Solution Approach 1:
The pre-forming stage creates a preform that closely matches the final product geometry, minimizing excess material from the beginning. This preliminary shaping action ensures that subsequent ring rolling operates on material that is already optimally positioned, dramatically reducing scrap and improving utilization rate.
Solution Approach 2:
The process uses controlled plastic deformation parameters during pre-forming and ring rolling to achieve the desired shape with minimal material removal. By carefully controlling deformation parameters and using material reuse mechanisms, the process achieves high material utilization rates compared to traditional forging.
3Temperature
If QCr0.8 alloy is used, then excellent thermal conductivity is achieved, but Cr segregation occurs reducing yield strength to below 90 MPa
Solution Approach 1:
The alloy undergoes periodic heating and plastic deformation cycles during the pre-forming and ring rolling stages. These periodic thermal-mechanical treatments promote uniform Cr distribution by repeatedly breaking up segregation zones and redistributing alloying elements, thereby maintaining both thermal conductivity and yield strength.
Solution Approach 2:
The process utilizes controlled temperature parameters during forming operations to influence Cr diffusion and distribution. By optimizing the temperature range and holding times during pre-forming and ring rolling, the process prevents Cr segregation while maintaining the alloy's excellent thermal conductivity properties.
4Volume of moving object
If subsection welding method is used, then large-size component can be assembled, but operation complexity increases and structural uniformity cannot be ensured
Solution Approach 1:
Instead of welding separate subsections, the process segments the forming operation itself into pre-forming and ring rolling stages, creating a single integrated component. This approach achieves large-size production without the complexity of assembly operations, maintaining structural uniformity while using manageable equipment tonnage at each stage.
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 improves the yield strength of the QCr0.8 alloy to meet specific requirements, reduces raw material usage by half, and enhances surface quality and structural uniformity, achieving a yield strength of 105-120 MPa while minimizing equipment tonnage and material waste.
Implementation Method 1
By means of the repeated upsetting-stretching severe plastic deformation, the structural uniformity of the raw material is improved, and the segregation of Cr is mitigated
Implementation Method 2
heating a raw material followed by upsetting and stretching at least twice to obtain a primary blank
Implementation Method 3
The radial and axial ring rolling technology is used to roll the profiled ring blank, and the continuous local plastic deformation is realized by a sectional tooling
Data Source
AI summary
A method for forming a QCr0.8 alloy tapered cylindrical ring, including: heating a standard QCr0.8 alloy cylindrical part followed by upsetting and stretching at least twice to obtain a primary blank; heating the primary blank followed by upsetting and chamfering to obtain a secondary blank, where a diameter of a top end is greater than that of a bottom end; subjecting the secondary blank to backward extrusion to form a preform; machining the preform to remove a flash and a bottom residue; subjecting a bottom end of the preform to local bulging to enable a shape and a size thereof to match that of a drive roller in a forming tooling, so as to form a profiled ring blank; and rolling the profiled ring blank by a radial-axial ring rolling machine with the forming tooling to form the tapered cylindrical ring.