Shaft Diameter Enlargement Limits to Prevent Boundary Cracks
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Solution Overview
Problem
The existing shaft diameter enlargement methods often result in cracks at the boundary between the enlarged intermediate portion and the rest of the shaft, requiring time-consuming and costly inspections to detect these cracks in mass-produced products.
Innovation Solution
A method and apparatus that set conditions for shaft diameter enlargement by determining an allowable number of rotations and enlargement ratio based on test data, ensuring the crack occurrence probability is below a threshold value, using a controller to control the compressive force, bending angle, and rotation to enlarge the shaft workpiece within these set conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If shaft diameter enlargement is performed by rotating the shaft workpiece with axial compressive force and bending angle, then the intermediate portion can be enlarged to the predetermined outer diameter, but cracks may occur at the boundary between the enlarged intermediate portion and the shaft portion other than the intermediate portion
Solution Approach 1:
The patent performs preliminary actions by determining the allowable number of rotations and allowable enlargement ratio before the actual shaft diameter enlargement process based on test data. These predetermined limits are used to control the enlargement process, ensuring that the number of rotations and enlargement ratio do not exceed the thresholds that would cause cracks, thereby preventing crack occurrence before it happens.
Solution Approach 2:
The patent implements feedback by using test data that establishes the relationship between the number of rotations/enlargement ratio and crack occurrence probability. This feedback mechanism allows the system to adjust the enlargement process parameters based on the determined allowable limits, creating a closed-loop control that prevents crack occurrence while achieving the desired outer diameter.
2Reliability
If inspection methods such as visual inspection, magnetic particle inspection, or eddy current inspection are used to detect cracks, then crack presence can be identified, but time and cost increase for checking all mass-produced shaft products
Solution Approach 1:
The patent performs preliminary determination of allowable process parameters (number of rotations and enlargement ratio) before mass production based on test data. By controlling the enlargement process within these predetermined safe limits, the patent prevents crack occurrence in the first place, eliminating the need for subsequent time-consuming inspections of each product.
Solution Approach 2:
The patent converts the potentially harmful effect (crack occurrence during enlargement) into a beneficial control mechanism by establishing allowable limits based on test data. By using the relationship between process parameters and crack occurrence probability, the patent transforms the problem of crack detection into a preventive control approach, where the enlargement process itself becomes the means of ensuring crack-free products.
3Manufacturing precision
If the number of rotations is increased to enlarge the intermediate portion to the predetermined outer diameter, then the manufacturing precision improves, but the crack occurrence probability at the boundary increases
Solution Approach 1:
The patent applies parameter changes by determining the allowable number of rotations and allowable enlargement ratio as critical control parameters based on test data. By changing the control approach from unlimited enlargement to parameter-constrained enlargement, the patent achieves the desired outer diameter precision while maintaining crack occurrence probability below the threshold value.
4Productivity
If the enlargement ratio is increased to achieve the predetermined outer diameter, then the manufacturing efficiency improves, but the crack occurrence probability at the outer periphery increases
Solution Approach 1:
The patent applies parameter changes by establishing the allowable enlargement ratio as a critical control parameter based on test data. By controlling the enlargement ratio to be equal to or less than the allowable value, the patent achieves efficient enlargement while preventing cracks at the outer periphery.
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 approach reduces the time and cost associated with checking for cracks by determining acceptability immediately after enlargement, minimizing the likelihood of crack occurrence at the boundary and outer periphery of the shaft workpiece.
Implementation Method 1
an axially intermediate portion of a shaft workpiece is enlarged in a radial direction by rotating the shaft workpiece about an axis of the shaft workpiece with axial compressive force being applied to the intermediate portion
Data Source
AI summary
A method for setting conditions for a shaft diameter enlargement, a shaft diameter enlargement method, and a shaft diameter enlargement apparatus are provided. A controller of the shaft diameter enlargement apparatus controls a compressing section, a bending section, and a rotating section to enlarge an intermediate portion of a shaft workpiece to have a predetermined outer diameter by rotating the shaft workpiece about its axis with axial compressive force a bending angle being applied to the intermediate portion. The controller determines whether the shaft workpiece is acceptable, based on the number of rotations of die shaft workpiece required for enlarging the intermediate portion to have the predetermined outer diameter or based on an enlargement ratio of the intermediate portion.