Drill Insert Boundary Geometry for Scratch-Free Hole Side Walls
Find Innovative SolutionsGenerate Solutions
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
The cutting insert for drill features a second boundary line with inclined portions relative to the cutting edge, which increases the distance swarf needs to travel before hitting the boundary line, preventing swarf from scratching the hole's side wall.
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 may be brought into abutment with the side wall surface of the drilled hole forming scratches and deteriorating the side wall quality
Solution Approach 1:
The second boundary line is designed to extend in a direction that is not parallel to the second cutting edge portion, creating a dimensional offset that increases the distance swarf must travel before contacting the side wall. This dimensional change in the boundary line orientation effectively redirects swarf flow away from the harmful contact zone.
Solution Approach 2:
The second boundary line acts as an intermediary element between the second cutting edge portion and the side wall surface. By positioning and orienting this boundary line at an angle, it serves as a mediator that intercepts and redirects swarf before it can directly contact and scratch the side wall surface.
2Device complexity
If the second boundary line extends in parallel with the second cutting edge portion, then the structure is simple, but swarf can easily contact the side wall surface causing scratches
Solution Approach 1:
Instead of extending the second boundary line parallel to the second cutting edge portion (conventional approach), the invention changes the orientation to a non-parallel direction. This dimensional change in the boundary line's angular orientation increases swarf travel distance and prevents direct contact with the side wall, thereby improving surface quality despite increased structural complexity.
3Object-affected harmful factors
If the distance for swarf to travel before hitting the boundary line is increased, then swarf contact with side wall is prevented, but the boundary line structure becomes more complex
Solution Approach 1:
The invention achieves increased swarf travel distance by changing the angular orientation of the second boundary line relative to the second cutting edge portion. This dimensional change in orientation, rather than simply extending the boundary line length, effectively increases the path swarf must travel while maintaining a relatively compact insert structure.
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A top surface includes: a first rake face continuous to a first cutting edge portion; a first side surface continuous to the first rake face; a second rake face continuous to a second cutting edge portion; a second side surface continuous to the second rake face; a flat surface portion continuous to both a first side surface and a second side surface; a first boundary line that is a ridgeline between the first side surface and the flat surface portion and that has a straight line shape; and a second boundary line that is a ridgeline between the second side surface and the flat surface portion. 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.