Concave Rake Face Single-Lip Drill for Higher Feed Rates
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Solution Overview
Problem
Single-lip drills face limitations in increasing feed rate due to high cutting forces and chip jamming issues, which can lead to tool breakage, and they often require chip breakers for effective chip removal.
Innovation Solution
A single-lip gun drill design with a concave rake face over 75% of its width and a positive rake angle, eliminating the need for a chip breaker, reduces cutting forces and allows for higher feed rates while maintaining drill longevity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional single-lip drill with standard grind geometry is used, then the drill structure is simple and easy to manufacture, but high cutting forces occur and chip removal is problematic leading to tool breakage
Solution Approach 1:
The invention applies a concave curvature to the rake face of the drill, replacing the conventional flat grind geometry. This concave shape modifies chip flow characteristics and reduces cutting forces, preventing chip jamming and tool breakage while maintaining manufacturing feasibility through standardized grinding processes
Solution Approach 2:
The invention changes the geometric parameters of the drill by implementing a positive rake angle (5° to 15°) and concave rake face curvature. These parameter modifications optimize chip formation and evacuation, reducing cutting forces and improving tool reliability without complicating the manufacturing process
2Productivity
If the feed rate is increased to improve productivity, then manufacturing speed increases, but cutting forces become excessive causing tool overload and breakage
Solution Approach 1:
The concave rake face geometry redistributes cutting forces more favorably along the cutting edge, reducing peak forces and enabling higher feed rates without tool overload. The curved surface promotes smoother chip flow and reduces friction, allowing increased productivity
Solution Approach 2:
By implementing a positive rake angle and concave curvature, the invention changes the mechanical parameters of chip formation. This reduces specific cutting energy and allows higher feed rates to be sustained without exceeding tool strength limits, directly improving productivity
3Object-generated harmful factors
If a chip breaker is added to improve chip removal, then chip evacuation effectiveness increases, but the drill structure becomes more complex and manufacturing difficulty increases
Solution Approach 1:
The invention extracts and eliminates the chip breaker component from the drill structure. Instead of adding a separate chip-breaking element, the concave rake face geometry itself performs the chip control function, simplifying the overall drill structure while maintaining effective chip evacuation
Solution Approach 2:
The concave rake face serves multiple functions simultaneously: it acts as the cutting surface, controls chip formation through its geometry, and facilitates chip evacuation. This multi-functionality eliminates the need for separate chip breakers, reducing structural complexity
Data Source
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AI summary
A single-lip drill (2, 3) comprising at least one cutting edge (211, 311) on a drill head (21, 31) has a face (21, 213) which is concave along at least 75 percent of the width thereof and substantially along the entire length thereof, all the way to, and inclusive of, the cutting edge (211, 311).