Reduced Head Tail Piece for Drill Bit Shear Failure
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Solution Overview
Problem
Existing extendable drill bit assemblies face issues with shear failure due to lack of clearance between reduced dimension sections and chuck or collet surfaces, leading to stress concentrations and potential shearing of components under rotational and flexing forces, without effective retention of locking mechanisms.
Innovation Solution
A tail piece with a male coupler having a head with reduced outer dimensions relative to its body, providing a clearance space when mounted in a quick-release drill or head, shifts forces to the body, reducing the likelihood of shear failure and incorporating a locking mechanism with a flute for secure engagement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the head of the male coupler is reduced in dimension to facilitate mounting in the quick-release mechanism, then the ease of operation is improved, but the strength is worsened due to stress concentration and potential shearing under rotational and flexing forces
Solution Approach 1:
The patent introduces a clearance space (dimensional feature) between the male coupler head and the quick-release mechanism walls, shifting forces from the head to the body of the male coupler. This dimensional change resolves the contradiction by maintaining reduced head dimensions for ease of mounting while preventing stress concentration that would compromise strength.
2Device complexity
If the reduced dimension section is positioned close to the mounting interface, then the device complexity is reduced, but the reliability is worsened due to lack of clearance causing stress concentration and shearing
Solution Approach 1:
The clearance space acts as a protective buffer that prevents direct contact and stress concentration on the male coupler head before forces are applied during operation. This beforehand cushioning resolves the contradiction by maintaining structural simplicity while preventing reliability failures under rotational and flexing forces.
3Volume of moving object
If the head of the male coupler has reduced outer dimensions, then the volume of the male coupler is reduced, but the strength is worsened due to lack of clearance between the head and the quick-release mechanism
Solution Approach 1:
The patent introduces a clearance space (dimensional feature) between the male coupler head and the quick-release mechanism walls, shifting forces from the head to the body of the male coupler. This dimensional change resolves the contradiction by maintaining reduced head dimensions for ease of mounting while preventing stress concentration that would compromise strength.
Data Source
AI summary
An assembly includes a quick-release head, a tail piece and a flexible metal rod. The tail piece includes a shaft and a male coupler formed of a head, body, and flute. At least a portion of the male coupler head has a reduced outer dimension relative to an outer dimension of the body. When the male coupler is mounted in a second quick-release head or drill, a clearance space is provided between the reduced outer dimension portion and the second quick-release head or drill. During use, the assembly may undergo bending which results in significant forces applied in particular to the male coupler head. By providing the clearance space, these forces are predominantly shifted to the male coupler body, thereby reducing the likelihood that the male coupler head will shear from the remainder of the male coupler.