Segmented Drill Cutting Edge for Deep-Hole Chip Discharge
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Solution Overview
Problem
Existing drills face issues with chip clogging and entanglement during deep hole drilling, leading to potential breakage of the drill main body or damage to the work material, especially when drilling through materials like stainless steel or aluminum, due to insufficient chip division and burr generation.
Innovation Solution
A drill design featuring a chip discharging flute that opens to the tip flank face and extends to the posterior end, with an inner and outer peripheral cutting edge that are inclined to the posterior end, having different point angles and radial widths, ensuring chips are generated in the same direction and guided for smooth discharge, preventing clogging and entanglement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the cutting edge extends to the posterior end side in the axial direction as approaching the inner peripheral side from the outer peripheral end (candle drill configuration), then burr suppression is improved in shallow hole drilling, but chip division becomes insufficient in deep hole drilling causing chip clogging and drill breakage
Solution Approach 1:
The cutting edge is divided into multiple segments: a tip-side extending portion and a posterior end-side extending portion, with different orientations. The tip-side portion extends forward to suppress burrs, while the posterior end-side portion extends backward to facilitate chip discharge. This segmentation allows each portion to perform its specific function without interfering with the other.
Solution Approach 2:
The invention introduces a radial width dimension constraint for the outer peripheral cutting edge (5%-20% of the total cutting edge diameter). By controlling the radial width in addition to the axial direction, the chip flow path is optimized to prevent entanglement while maintaining the candle drill's burr suppression capability.
2Manufacturing precision
If the radius R4 from the axis to the position where the first concavely curved cutting edge recedes most to the posterior end side is set to 0.25×D to 0.4×D, then two chips of approximately equal width are split and generated, but chip entanglement is likely to occur
Solution Approach 1:
The cutting edge is segmented into tip-side and posterior end-side extending portions with different orientations. The tip-side portion generates chips that flow forward, while the posterior end-side portion generates chips that flow backward, separating the chip flow paths to prevent entanglement while maintaining uniform chip width through the R4 parameter.
Solution Approach 2:
By adding radial width control (5%-20% of diameter) as an additional dimensional parameter, the invention optimizes the chip discharge path in the radial direction, preventing chip entanglement while maintaining the uniform chip width achieved by the R4 parameter setting.
3Ease of operation
If the cutting edge extends to the posterior end side and the outer peripheral surface intersect at an acute angle, then chip discharge is facilitated, but the strength is insufficient causing fracturing
Solution Approach 1:
The cutting edge structure is segmented into different functional portions: the tip-side extending portion for burr suppression and the posterior end-side extending portion for chip discharge. This segmentation allows the outer peripheral cutting edge to have a configuration that facilitates chip discharge while maintaining sufficient strength by not requiring an acute angle intersection.
Data Source
AI summary
In this drill, a cutting edge, which is formed at an intersecting ridge line part between a wall surface, facing a drill rotation direction, of a chip discharging flute formed at an outer periphery of a tip portion of a drill main body that is rotated around an axis, and a tip flank face, includes an inner peripheral cutting edge located on a radially inner peripheral side with respect to the axis; and an outer peripheral cutting edge connected to a radially outer peripheral side of the inner peripheral cutting edge. A point angle of a portion of the inner peripheral cutting edge on an inner peripheral side with respect to the axis is within a range of 90° to 170°.