Drawn Hollow Shaft Structure for Precise Small Inner Diameters
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Solution Overview
Problem
Conventional hollow shaft production by drawing processing faces challenges in achieving high shape precision and rigidity due to deformation and stress concentration when attempting to create a small internal diameter with a large drawing ratio.
Innovation Solution
The hollow shaft design involves forming cut faces on the inner periphery of the main body and base portion of the extremity drawn part before drawing, with a non-cut face at the tip portion and tapered cut faces that gradually decrease in diameter, along with curved faces to smoothly connect these areas, to maintain a low drawing ratio and reduce stress concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a large drawing ratio is used to achieve a small internal diameter in the extremity drawn part, then the internal diameter is reduced, but the main body part and extremity drawn part become deformed
Solution Approach 1:
The patent applies preliminary cutting processing to the inner peripheral face of the base portion before drawing processing. This preliminary action creates a stepped structure that allows the drawing force to be applied more effectively to the extremity drawn part without transmitting excessive stress to the main body part, thereby preventing deformation while achieving the desired small internal diameter.
Solution Approach 2:
The patent creates different structural qualities in different regions: the base portion has a cut inner peripheral face forming a step, while the tip portion maintains a non-cut inner peripheral face. This local differentiation allows the base portion to withstand drawing forces while the tip portion achieves the required small internal diameter, resolving the contradiction between internal diameter reduction and overall shape precision.
2Manufacturing precision
If a large drawing ratio is used to achieve a small internal diameter, then the internal diameter is reduced, but stress concentration occurs at the border part between the extremity drawn part and main body part
Solution Approach 1:
The preliminary cutting processing creates a stepped structure at the base portion that acts as a stress distribution feature. This step prevents stress concentration at the border part by providing a gradual transition zone, allowing the extremity drawn part to achieve a small internal diameter without compromising the strength of the border region.
Solution Approach 2:
The patent converts the potentially harmful stress concentration at the border part into a beneficial stress distribution pattern. By creating a stepped structure through preliminary cutting, the stress that would normally concentrate at a sharp transition is instead distributed across the stepped interface, maintaining border part strength while achieving the desired internal diameter reduction.
3Manufacturing precision
If cutting processing is applied to the entire inner peripheral face before drawing, then shape precision is improved, but the drawing ratio must be increased to achieve the small internal diameter
Solution Approach 1:
The patent applies cutting processing selectively only to the base portion's inner peripheral face, leaving the tip portion's inner peripheral face uncured. This local quality approach maintains high shape precision at the critical border region while allowing the tip portion to be formed efficiently through drawing alone, avoiding the need for a high drawing ratio across the entire structure.
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 allows for high shape precision and increased rigidity by preventing deformation and stress concentration, enabling the production of hollow shafts with a predetermined small internal diameter while maintaining structural integrity.
Implementation Method 1
an extremity drawn part that is integrally connected to one end of the main body part on the same axis and whose diameter is made smaller than a diameter of the main body part by drawing processing
Data Source
AI summary
A hollow shaft includes a cylindrical main body part and an extremity drawn part that is integrally connected to one end of the main body part on the same axis and whose diameter is made smaller than a diameter of the main body part by drawing processing, wherein an inner peripheral face of the main body part and an inner peripheral face of a base portion, which is continuous with one end side of the main body part, of the extremity drawn part are formed as cut faces that are subjected to cutting processing before the drawing processing, and an inner peripheral face of a tip portion, which is continuous with an extremity side of the base portion, of the extremity drawn part is a non-cut face. Accordingly, the hollow shaft can be molded with high shape precision while maintaining a low drawing ratio for an extremity drawn part.