Indexable Drill Insert Asymmetric Cutting Edge Geometry
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Solution Overview
Problem
Conventional quadrangular indexable drill inserts with rectangular cutting edges tend to drift away from the center during drilling, leading to narrow walls and rubbing issues, especially when drilling holes with diameters less than the desired value.
Innovation Solution
A quadrangular indexable drill insert with four identical cutting edges, each comprising multiple part edges and a transitional edge, directing forces to the center and backend of the drill body, and featuring a smaller bottom surface and larger top surface for positive cutting geometry, along with a nose portion and clearance faces to prevent drifting and ensure accurate hole creation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If rectangular cutting edges are used in conventional quadrangular indexable drill inserts, then the manufacturing and assembly process is simple, but the drill drifts away from its center during drilling
Solution Approach 1:
The patent applies asymmetry by designing cutting edges that are not rectangular but have specific angular configurations (first angle α and second angle β) relative to the drill axis. This asymmetric geometry ensures that cutting forces are directed along the drill axis rather than causing lateral drift, thereby improving hole accuracy while maintaining manufacturability through standardized angular features.
Solution Approach 2:
The patent changes the geometric parameters of the cutting edges from simple rectangular shapes to configured edges with specific angles (α and β) and radii (R). These parameter changes optimize the force distribution during cutting, preventing drill drift and improving positioning accuracy without significantly complicating the manufacturing process.
2Device complexity
If rectangular cutting edges are used in conventional quadrangular indexable drill inserts, then the structure is simple, but narrow walls are created which are not feasible in practical applications
Solution Approach 1:
The asymmetric cutting edge geometry with angles α and β creates more favorable chip flow patterns and force distributions that prevent excessive lateral pressure on the workpiece walls. This results in better wall quality and more feasible narrow wall configurations compared to simple rectangular edges.
3Loss of time
If conventional indexable drill inserts are used, then the cutting insert can be quickly changed upon wear, but the drill hole diameter is less than the pre-desired value and rubbing occurs
Solution Approach 1:
The optimized cutting edge parameters (angles α and β, radius R) ensure that the drill produces the correct hole diameter and prevents rubbing. The geometric configuration is designed to maintain proper clearance and cutting action throughout the insert's life, ensuring accurate hole dimensions are achieved consistently.
Solution Approach 2:
The cutting edges are pre-configured with optimal angles and radii to ensure correct hole diameter and prevent rubbing from the beginning of the cutting process. This preliminary geometric optimization ensures that no rubbing or diameter deviation occurs during the insert's service life.
4Device complexity
If forces are not directed to the center of the drill body, then the cutting action is simple, but the drill body drifts away from its center
Solution Approach 1:
The asymmetric cutting edge geometry is specifically designed to direct cutting forces along the drill axis toward the center of the drill body. The angles α and β are configured to balance the force components, ensuring stable drilling without lateral drift while maintaining a relatively simple overall structure.
Data Source
AI summary
A quadrangular indexable drill insert includes: a top surface, a bottom surface, a side surface adjoining the top and bottom surfaces from four sides of the insert, four cutting edges configured at the intersection of the side surface and the top surface, and a screw hole disposed at the center of the insert. Each cutting edge includes: a first part edge; a second part edge extending from the first part edge; a third part edge extends away from a reference axis, a nose portion adjoins the first part edge with the third part edge of a succeeding cutting edge and a transitional edge joining the second and third part edges. The transitional part edge forms an angle of about 10° to about 90° with respect to the reference axis and forms a convex curve with the second part edge and a concave curve with the third part edge.