Drill Cutting Insert Geometry for Side-Wall Scratch Prevention
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Solution Overview
Problem
When using throwaway drill inserts, swarf can be brought into contact with the side wall of the drilled hole, leading to scratches and deterioration of the hole's side wall quality.
Innovation Solution
A cutting insert design with a parallelogram-shaped cutting edge and inclined boundary lines that extend along a concentric circle of the mounting hole, allowing swarf to be effectively rounded and prevented from contacting the side wall, thereby maintaining hole quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional throwaway insert with a chip breaker is used, then the cutting function is provided, but swarf contacts the side wall of the drilled hole causing scratches and deterioration of hole quality
Solution Approach 1:
The second boundary line is designed with curved portions (first and second curved portions) that extend along a concentric circle of the mounting hole, creating a rounded geometry. This curvature allows swarf to be guided away from the side wall in a smooth arc, preventing direct contact and scratches, while maintaining effective chip breaking functionality
Solution Approach 2:
The boundary line between the rake face and clearance face is segmented into multiple portions (first straight portion, first curved portion, second curved portion, second straight portion) with different functions. The curved portions specifically address swarf control, while other portions maintain structural integrity and cutting performance, allowing targeted optimization of the swarf discharge path
2Manufacturing precision
If the cutting edge is designed with a parallelogram shape and inclined boundary lines, then swarf is prevented from contacting the side wall, but the device complexity increases
Solution Approach 1:
The boundary line geometry is optimized locally at specific portions (curved portions extending along concentric circles) where swarf contact with the side wall occurs, while other portions maintain simpler geometries. This localized optimization prevents side wall contact without requiring complete redesign of the entire cutting insert, thereby limiting the increase in device complexity
Data Source
AI summary
When seen in a direction perpendicular to a seating surface, the second boundary line has a first portion and a second portion, the first portion having an inclination relative to the second cutting edge portion in a counter clockwise direction, the first portion being located between the first boundary line and an intersection between the second boundary line and a straight line passing through a center of a mounting hole and perpendicular to the second cutting edge portion, the second portion being located opposite to the first portion relative to the intersection, the second portion having an inclination relative to the second cutting edge portion in a clockwise direction.