Shaft Diameter Enlargement Below Holder Tempering Temperature
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Solution Overview
Problem
Existing methods for enlarging shaft diameters, such as cutting or welding, are inefficient and can lead to material waste and deformation issues, while heating methods can compromise the durability of the apparatus due to tempering effects.
Innovation Solution
A shaft diameter enlarging method that involves holding the shaft between holders, applying compression and alternating loads, and heating the shaft above its blue brittleness temperature while keeping the holders below their tempering temperature, to achieve increased enlargement rates without cracking and reduce running costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the shaft is heated to warm or hot temperature range (700°C to 950°C or above) to increase enlargement rate, then the plastic deformability is improved and enlargement rate increases, but the holders undergo tempering which reduces their hardness and durability
Solution Approach 1:
The patent changes the temperature parameter from warm/hot forging range (700-950°C) to a lower range (580-650°C) that avoids holder tempering while still achieving adequate plastic deformability for high enlargement rates. This parameter optimization resolves the contradiction between improving productivity and maintaining reliability.
Solution Approach 2:
The shaft is heated to the optimal temperature range (580-650°C) before the enlargement process begins, ensuring the material is in the best state for deformation while the holders remain at safe temperatures. This preliminary heating action allows the subsequent enlargement to proceed with high enlargement rate without compromising holder durability.
2Productivity
If high compression force is applied to achieve desired shape quickly, then the number of rotations is reduced and processing time decreases, but the apparatus becomes large-sized
Solution Approach 1:
By changing the temperature parameter to 580-650°C, the material exhibits improved plastic deformability, allowing moderate compression forces to achieve high enlargement rates. This eliminates the need for large-sized apparatus while maintaining high processing speed.
3Strength
If the shaft is heated to blue brittleness range (around 400°C), then the deformation resistance increases due to blue brittleness effect, but the enlargement rate is not improved and cracking damage may occur
Solution Approach 1:
The patent explicitly avoids the blue brittleness temperature range (around 400°C) by setting the heating temperature to 580-650°C. This parameter selection ensures the shaft material has adequate plastic deformability without excessive deformation resistance, preventing cracking while achieving high enlargement rates.
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 allows for higher enlargement rates, prevents cracking, and extends the lifespan of the apparatus by maintaining holder hardness, thus reducing operational costs and material waste.
Implementation Method 1
When enlarging the intermediate portion, a temperature of the intermediate portion is set to be above a blue brittleness temperature range of the shaft, and a temperature of the holders is set to be below a tempering temperature range of the holders
Implementation Method 2
the compression force and the bending force is applied to the shaft under a condition in which compression stress continuously acts at an outer side of the bending, whereby the shaft between the holders is plastically deformed in a radial direction
Data Source
Figure 1
Figure 2~3B
Figure 3C~7
AI summary
To radially enlarge an intermediate portion of a shaft, the shaft is held by a pair of holders with a gap between the pair of holders in an axial direction of the shaft, compression force is applied in the axial direction to the intermediate portion arranged between the pair of holders, and alternating load is applied in a direction intersecting the axial direction to the intermediate portion to enlarge the intermediate portion. When enlarging the intermediate portion, a temperature of the intermediate portion is set to be above a blue brittleness temperature range of the shaft, and a temperature of the holders is set to be below a tempering temperature range of the holders.