Twist Drill Flank Geometry for Corner Wear and Stability
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Solution Overview
Problem
Rotary cutting tools, such as twist drills, experience significant wear and instability when machining hard materials like steel, particularly at the cutting corner due to high friction and stress, leading to reduced tool strength and inadequate bore quality.
Innovation Solution
A cutting tool design with a flank angle that increases radially outward from the main cutting edge to the cutting corner, providing more clearance and reducing friction, while maintaining stability through sufficient material at the main cutting edge, and optionally featuring a guide bevel and back-milling to prevent sticking and improve machining.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If the flank angle is increased radially outward to reduce friction and wear at the cutting corner, then the service life of the cutting tool is extended, but the stability of the cutting tool may be compromised
Solution Approach 1:
The patent applies local quality by varying the flank angle along the radial direction of the cutting tool. The flank angle is smaller near the cutting tip (providing stability) and increases toward the cutting corner (reducing friction and wear). This gradient approach allows each region of the cutting tool to have optimal geometric properties for its specific functional requirements.
Solution Approach 2:
The patent implements dynamics by making the flank angle a variable parameter rather than a constant. The flank angle changes dynamically along the radial direction, creating a progressive geometry that adapts to the different stress and friction conditions experienced at different radial positions during machining operations.
2Object-affected harmful factors
If the flank angle is increased to provide more clearance at the cutting corner, then friction and wear are reduced, but the material strength at the main cutting edge may be reduced
Solution Approach 1:
The patent applies local quality by creating different geometric conditions at different locations of the cutting tool. The main cutting edge retains a smaller flank angle to maintain material strength and structural integrity, while the cutting corner area has a larger flank angle to reduce friction and wear during operation.
Data Source
AI summary
Cutting tool for the rotary machining of workpieces, in particular a twist drill, with a cutting tip which has at least one main cutting edge and at least one free surface (24), wherein a flank face adjoins the main cutting edge radially to the outside, and wherein a flank angle of the flank face increases in a radially outward direction.