Rotary Cutting Insert Axial Locking for Centering and Stress Relief
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Solution Overview
Problem
Existing drill tool assemblies face issues with insert centring and stress concentration at the mounting region, leading to potential separation during tool movement or vibrations, and compromised strength due to inadequate axial locking mechanisms.
Innovation Solution
The design incorporates radial projections on the cutting insert that extend between lobes, allowing for enhanced centring and secure axial locking without compromising torque transfer, featuring a configuration that maximizes the rearward neck portion for improved centring and minimizes stress concentrations by distributing axial forces along the ribs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If declined axial support surfaces are used to maximise axial lock, then axial locking strength is improved, but insert centring is worsened
Solution Approach 1:
The insert head is segmented into two diametrically opposed lobes with a gap between them, allowing the rearwardmost portions to extend beyond the axial support surfaces. This segmentation enables the lobes to provide both axial locking through the declined support surfaces and centring through their extended rearward portions, resolving the contradiction between axial lock strength and centring precision
Solution Approach 2:
The solution moves the centring function from the axial dimension (where the declined support surfaces operate) to the radial dimension (where the lobes extend beyond the support surfaces). By projecting the lobes radially outward beyond the axial support surfaces, the insert achieves centring in the radial direction while maintaining axial locking through the declined surfaces, thus resolving the dimensional conflict
2Strength
If axial support surfaces are declined to transfer loading forces, then axial lock is improved, but stress concentration at support body is worsened
Solution Approach 1:
The insert is segmented into lobes that distribute the axial loading forces across multiple contact points with the support body. The declined axial support surfaces on each lobe transfer forces to different regions of the support body, dispersing stress concentrations rather than concentrating them at a single location, thus resolving the contradiction between axial lock strength and stress concentration
Solution Approach 2:
The declined axial support surfaces dynamically redirect axial forces at an angle rather than transmitting them directly perpendicular to the support body. This angular force redirection allows the axial locking function to be maintained while the force vectors are distributed to reduce stress concentration at the mounting region
Data Source
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AI summary
A cutting insert for a rotary drill tool and drill tool assembly in which an insert and a support body are coupled axially via a complementary shaped projection extending radially outward from the insert and received with a recess indented at a radially inward facing surface of the support body.