Partially Removed Tip Coating for Longer-Life Cutting Tools
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Solution Overview
Problem
Cutting tools like drills and ball end mills experience reduced lifespan due to micro-brittle wear in the ultra-low speed region, particularly at the center portion, which is exacerbated by high-pressure conditions during high-feed drilling.
Innovation Solution
A wear-resistant layer is formed on the tip end of cutting tools, and a portion or the entirety of this layer is selectively removed within a distance of 0.01 R to 0.8 R from the center of the tip end through polishing, to prevent micro-brittle wear and its propagation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a wear-resistant layer is formed on the tip end of the cutting tool, then wear resistance is improved, but micro-brittle wear occurs in the ultra-low speed region at the center portion
Solution Approach 1:
The patent applies local quality by creating different surface conditions in different regions of the tip end. The center portion (within radius R1) has the wear-resistant layer removed to prevent micro-brittle wear, while the outer region (between R1 and R2) retains the wear-resistant layer for wear protection. This spatial differentiation of material properties resolves the contradiction between wear resistance and prevention of micro-brittle wear.
Solution Approach 2:
The tip end surface is segmented into three distinct zones based on radial distance from the center: the center portion (radius ≤ R1) where the wear-resistant layer is removed, the intermediate region (R1 < radius ≤ R2) where the wear-resistant layer is retained, and the outer region (radius > R2) for reference. This segmentation allows each zone to serve its specific function, resolving the contradiction between needing wear resistance and avoiding micro-brittle wear.
2Reliability
If the wear-resistant layer is removed from the center portion, then micro-brittle wear is restrained, but the wear-resistant layer coverage is reduced
Solution Approach 1:
The patent applies local quality by creating different surface conditions in different regions of the tip end. The center portion (within radius R1) has the wear-resistant layer removed to prevent micro-brittle wear, while the outer region (between R1 and R2) retains the wear-resistant layer for wear protection. This spatial differentiation of material properties resolves the contradiction between wear resistance and prevention of micro-brittle wear.
3Adaptability or versatility
If a cover layer is formed on the wear-resistant layer for decoration or identification, then additional functionality is added, but the cover layer must be easily removed without damaging the wear-resistant layer
Solution Approach 1:
The patent introduces a separation layer as an intermediary between the wear-resistant layer and the cover layer. This separation layer has different thermal expansion coefficients or bonding characteristics that allow the cover layer to be easily removed without damaging the underlying wear-resistant layer, thus resolving the contradiction between adding functionality and ease of manufacture.
Data Source
AI summary
The present invention relates to a cutting tool, which performs, like a drill or a ball end mill, cutting while rotating in a state in which the center of the tip end is in contact with a work material, and includes a wear-resistant layer formed at the tip end thereof, wherein a portion of the wear-resistant layer is selectively removed through tip end polishing from the center of the tip end of the drill or the ball end mill to a predetermined area, so as to restrain micro-brittle wear generated in an ultra-low speed region, and thus remarkably improving the cutting lifespan of the cutting tool such as the drill or the ball end mill.