Drill Thinning Structure for Low-Resistance Chip Evacuation
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Solution Overview
Problem
Drills with thinning edges experience increased cutting resistance due to chips stagnating in narrow spaces, particularly in high-efficiency machining, where the intersection angle between thinned faces and tip flank faces is acute, restricting the use environment and machining performance.
Innovation Solution
A drill design featuring a chip discharge flute on the outer periphery with a thinning edge and rake face, where the intersection angle between the thinning edge and first thinning ridgeline is greater than 95°, and the second thinning ridgeline is bent opposite to the drill rotation direction, connected via concave curves, allowing for smooth chip discharge and maintaining drill rigidity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the intersection angle between thinned faces and tip flank face is set to 75°-95° (acute angle), then the drill structure is compact and easy to manufacture, but chips stagnate in narrow spaces causing increased cutting resistance
Solution Approach 1:
The patent changes the intersection angle parameter from the conventional 75°-95° acute angle to an obtuse angle greater than 95°. This parameter modification fundamentally alters chip flow characteristics, allowing chips to be discharged smoothly along the thinned face without stagnation, thereby reducing cutting resistance while maintaining manufacturing feasibility
Solution Approach 2:
The patent introduces a concave curved surface connecting the thinning edge and the first thinning ridgeline, replacing conventional sharp edges and ridgelines. This curvature design creates a smoother chip discharge path, preventing chip jamming at critical transition zones and reducing cutting resistance during high-efficiency machining
2Productivity
If thinning is performed extensively on the inner peripheral portion to improve chip discharge, then chip discharge performance is improved, but the thickness at the tip of the drill main body is reduced compromising strength and rigidity
Solution Approach 1:
The patent applies different geometric characteristics to different regions of the thinned face. The first thinning wall surface has a specific inclination angle optimized for chip discharge, while the second thinning wall surface connects via a concave curve to maintain structural integrity. This localized differentiation allows effective chip discharge in the cutting zone while preserving drill strength in the tip region
Solution Approach 2:
The patent introduces a third dimension by bending the second thinning ridgeline toward the side opposite to the drill rotation direction. This creates a three-dimensional chip discharge path that increases the effective discharge volume without compromising the tip thickness, allowing chips to escape in multiple directions rather than being constrained to a single plane
Data Source
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AI summary
A drill has a thinning rake face (6) formed in the front end. An intersection ridgeline between the thinning rake face (6) and the tip flank face (2) is the thinning edge (4a). On the opposite side of the rotation direction (T), the first and second thinning wall surfaces (6b, 6c) and are formed. Viewed from the front, an intersection angle between the thinning edge (4a) and the first thinning ridgeline (L1) is larger than 95°. The second thinning ridgeline (L2) is bent to the opposite side of the rotation direction (T). The thinning edge (4a) and the first thinning ridgeline (L1) are connected via a concave curve line (N1). The first and second thinning wall surfaces (6b, 6c) are connected via a concave surface, and a curvature radius (R1) of the concave curve line (N1) is smaller than a curvature radius (R2) of the concave surface.