Accessory Tool Shank Geometry for Reduced Torsional Stress
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Solution Overview
Problem
Conventional accessory tools often break due to localized regions of high stress and discontinuities in the shank, leading to reduced durability and operational lifetime.
Innovation Solution
Incorporating a reduced diameter portion between the tool engagement portion and the effector end of the shank, which extends 10% to 45% of the shank's length, to reduce stress concentrations and increase flexibility, along with induction tempering to disperse stress risers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a uniform diameter shank is used, then the manufacturing process is simple, but the shank is prone to breaking due to localized stress concentrations
Solution Approach 1:
The shank is designed with non-uniform diameter, featuring a reduced diameter portion at the transition zone between the effector end and tool engagement portion. This local modification reduces stress concentrations at critical locations without affecting the overall shank structure, thereby improving reliability while maintaining manufacturing feasibility.
2Reliability
If the reduced diameter portion is made longer, then stress concentrations are better reduced, but the tool engagement portion stability is compromised
Solution Approach 1:
The reduced diameter portion is optimized to specific dimensional parameters: its length is defined as 10% to 45% of the total shank length, and its diameter is 70% to 98% of the major diameter of the shank. These parameter ranges balance stress reduction benefits with maintaining sufficient stability for tool engagement.
3Reliability
If induction tempering is applied, then stress risers are dispersed and durability is improved, but the manufacturing process time increases
Solution Approach 1:
Induction tempering is applied as a preliminary heat treatment process to the shank, particularly to the reduced diameter portion, before final assembly. This preliminary action disperses stress risers and improves impact resistance early in the manufacturing process, preventing future failures and reducing the need for rework or repairs.
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 reduced diameter portion enhances the durability and impact resistance of the accessory tool, allowing the effector end to elastically deform and extend the operational lifetime by reducing torsional stress and stress concentrations.
Implementation Method 1
allowing the effector end to elastically deform and extend the operational lifetime by reducing torsional stress and stress concentrations
Implementation Method 2
along with induction tempering to disperse stress risers
Data Source
AI summary
An accessory tool includes an adapter end having a maximum outer dimension, and a shank coupled to the adapter end. The shank includes a tool engagement portion including a cross section having a maximum outer width, a first reduced portion disposed between the tool engagement portion and the adapter end and having a first minimum outer dimension and a first length, and a second reduced portion formed in the tool engagement portion between the first reduced portion and an end of the shank. The second reduced portion is engaged by the tool to secure the shank to the tool, and has a second minimum outer dimension and a second length. The maximum outer dimension is greater than the maximum outer width. The maximum outer width is greater than the first minimum outer dimension and greater the second minimum outer dimension. The first length is greater than the second length.