Drill Shoulder Cutting Edge Geometry to Prevent Welding
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Solution Overview
Problem
The existing drills with maximized honing width in the shoulder cutting edge portion are prone to welding, leading to potential defects and increased cutting resistance, which can result in a shortened drill life and burrs during through-hole drilling.
Innovation Solution
A drill design with a chip discharging flute and a cutting edge having a negative rake angle on the outer peripheral end of the cutting edge shoulder portion, combined with reduced honing size, to enhance cutting edge strength and prevent welding, while maintaining cutting quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the honing width of the shoulder cutting edge portion is maximized, then the cutting edge strength is improved, but welding damage is likely to progress and drill life is shortened
Solution Approach 1:
The patent applies different honing widths to different portions of the cutting edge. The shoulder cutting edge portion has a smaller honing width (0.05-0.15mm) compared to the main cutting edge portion (0.2-0.5mm), creating local quality differences that prevent welding damage while maintaining necessary cutting edge strength where required.
2Strength
If the honing width of the shoulder cutting edge portion is maximized, then the cutting edge strength is improved, but cutting resistance increases and burr formation occurs
Solution Approach 1:
The patent creates local quality differences by applying smaller honing width (0.05-0.15mm) to the shoulder cutting edge portion compared to the main cutting edge portion. This local differentiation reduces cutting resistance and prevents burr formation in the shoulder portion while maintaining overall cutting edge strength.
Data Source
AI summary
A chip discharging flute is formed in a tip outer peripheral portion of a drill body rotated around an axis in a drill rotation direction. A cutting edge is formed in an intersection ridgeline portion between a wall surface of the chip discharging flute facing the drill rotation direction and a tip flank. The cutting edge includes a main cutting edge portion extending from an inner peripheral side toward an outer peripheral side of the drill body, and a cutting edge shoulder portion extending from an outer peripheral end of the main cutting edge portion to an outer periphery of the drill body, and is subjected to honing. Compared to the outer peripheral end of the main cutting edge portion, in an outer peripheral end of the cutting edge shoulder portion, a true rake angle is increased on a negative rake angle side, and a size of the honing decreases.