Hot Spinning of Large Titanium Cylinders for Crack-Free Precision
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Solution Overview
Problem
Large-diameter titanium alloy cylindrical parts are prone to cracking and exhibit poor straightness and roundness due to the poor plasticity, high strength, and low heat conductivity of titanium alloy at room temperature, and existing hot-spinning methods often result in diameter tolerance issues and curling during the spinning process.
Innovation Solution
A hot-spinning formation method involving heating the workblank to 600-650°C for 0.5-1 hour, then spinning it around a mandrel with a maximum clearance of less than 0.5 mm, using a pneumatic jack cylinder for removal, and employing a multi-pass spinning process with a vertical spinning lathe, without preheating the mandrel or spinning rollers, to achieve uniform deformation and improved cylindrical part quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If cold spinning is used to machine titanium alloy parts, then material utilization rate is high, but parts are likely to crack due to poor plasticity and high strength at room temperature
Solution Approach 1:
The patent applies parameter changes by heating the titanium alloy workpiece to 600-650°C before spinning operations. This temperature increase fundamentally changes the material parameters, improving plasticity from poor at room temperature to excellent at elevated temperature, thereby enabling crack-free forming while maintaining high material utilization rate through the cold-spinning process
2Reliability
If hot-spinning is used to improve plasticity, then cracking is reduced, but edge curling and poor straightness occur due to thermal effects
Solution Approach 1:
The patent applies preliminary action by pre-heating the workpiece to 600-650°C and maintaining it at this temperature throughout the spinning process. This preliminary thermal preparation ensures the material has optimal plasticity before forming begins, and maintaining the temperature prevents thermal gradients that would cause edge curling and dimensional inaccuracies
Solution Approach 2:
The patent utilizes thermal expansion effects by heating the titanium alloy to 600-650°C, causing controlled expansion that increases material ductility. The uniform thermal expansion across the workpiece prevents localized stress concentrations that would lead to edge curling, while the expanded state allows for better formability during spinning
3Device complexity
If room temperature spinning is used, then equipment complexity is low, but manufacturing precision deteriorates due to cracking and poor material behavior
Solution Approach 1:
The patent replaces the mechanical cold-forming system with a thermomechanical system by introducing a heating apparatus that maintains 600-650°C during spinning. This substitution fundamentally improves material behavior and manufacturing precision, as the thermally softened titanium alloy exhibits superior ductility and formability compared to room temperature conditions
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
The method ensures titanium alloy cylindrical parts with good straightness and roundness, high yield, and ease of mandrel change and workblank assembly, suitable for parts with outer diameters over 3 meters, effectively addressing the defects of prior art by ensuring proper recrystallization annealing and controlled spinning conditions.
Implementation Method 1
a to-be-machined workblank is placed in a resistance furnace to be heated to 600-650° C.
Implementation Method 2
the workblank is placed in a resistance furnace to be heated to 600-650° C., and is maintained at this temperature for 0.5-1 h
Implementation Method 3
spinning is started when a maximum clearance between the workblank and the mandrel is less than 0.5 mm
Data Source
AI summary
A hot-spinning formation method for large-diameter titanium alloy cylindrical parts. A workblank is placed in a resistance furnace to heated to 600-650° C., is maintained at this temperature for 0.5-1 h and is then taken out of the resistance furnace; after the workblank is heated, the inner diameter of the workblank becomes larger; the heated workblank is installed on a mandrel, and spinning is started when a maximum clearance between the workblank and the mandrel is less than 0.5 mm; the mandrel and the spinning rollers do not need to be preheated, and a multi-pass spinning process is adopted, such that the workblank can deform more uniformly. A vertical spinning lathe is used for spinning, the mandrel is easy to change, and the workblank is easy to assemble and disassemble.