Drill Point Geometry for Chip Flow and Misalignment Control
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Solution Overview
Problem
Conventional drills with point thinning suffer from reduced drilling performance and potential damage due to compacted chip flow and increased point angles, leading to misalignment and reduced service life.
Innovation Solution
The drill design features main and central cutting edges with inclined flanks and chip faces, where the central cutting edges have obtuse angles with the main cutting edges, and the first flanks have partial sections at obtuse angles to each other, ensuring a constant point angle and improved chip flow, with the inner chip face forming an acute angle with the central axis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If point thinning is applied to shorten the chisel edge, then the central cutting edges become shorter and easier to cut, but the point angle in the central area increases, causing chips to compact and cannot flow off freely
Solution Approach 1:
The patent applies different point angles to different regions of the drill: a smaller point angle (60-80°) at the central cutting edges for easier cutting and chip flow, and a larger point angle (90-110°) at the main cutting edges for structural stability. This local differentiation resolves the contradiction by optimizing each region's geometry for its specific function.
Solution Approach 2:
The drill point is segmented into distinct zones with different geometric characteristics: central cutting edges with one point angle and main cutting edges with another. This segmentation allows independent optimization of chip flow (central) and structural integrity (main), resolving the contradiction between edge length and chip flow reliability.
2Ease of manufacture
If the chisel edge is shortened through point thinning, then central cutting edges are easier to cut, but drilling performance is reduced due to compacted chips
Solution Approach 1:
The patent differentiates the point angle geometry between central and main cutting edges, creating locally optimized surfaces. The central area has a smaller point angle for ease of cutting and chip evacuation, while maintaining overall drill strength through the larger point angle at the main edges, thus preserving drilling performance.
3Strength
If a larger point angle is used in the central area, then the drill structure is more stable, but chips are compacted and cannot flow off freely
Solution Approach 1:
The patent assigns different point angles to different functional zones: the central cutting edges use a smaller point angle (60-80°) optimized for chip flow and ease of cutting, while the main cutting edges use a larger point angle (90-110°) optimized for structural stability. This local differentiation resolves the contradiction by allowing each zone to have the geometry best suited to its primary function.
Data Source
Figure 1~2
Figure 3~3b
Figure 4~4b
AI summary
The invention relates to a drill having at least two face-side primary cutting surfaces (3, 3'), swarf surfaces (11, 11') adjacent thereto that slope in a first direction, first free surfaces (15a, 15'a) adjacent to the at least two primary cutting surfaces (3, 3') sloping in the opposite direction to that of the swarf surfaces (11, 11'), at least two face-side point taperings formed by the respective central cutting surface (25, 25') adjacent to each primary cutting edge (3, 3'), to which the swarf surfaces (27, 27') sloping in the first direction are adjacent, a transverse cutting surface (7) running between the at least two central cutting surfaces (25, 25'), and auxiliary cutting surfaces (19, 19')provided in the region of a circumferential surface (17) of the drill (1). One auxiliary cutting surface (19, 19') is associated with each primary cutting surface (3, 3'), the at least two primary cutting surfaces (3, 3') being formed by the cutting lines of the swarf surfaces (11, 11') with the first free surfaces (15a, 15'a), and the swarf surfaces (11, 11') being associated with the primary cutting surfaces (3, 3') and the swarf surfaces (27, 27') being associated with the central cutting surfaces (25, 25') at an obtuse angle to one another. Said drill is characterized in that the first free surfaces (15a, 15'a) comprise partial sections (29a, 29'a; 31a, 31'a) disposed at an obtuse angle to one another, wherein the partial sections of the first free surfaces (15a, 15'a) are associated with the swarf surface (27, 27') of the central cutting surface (25, 25') and the swarf surface (11, 11') is associated with the primary cutting surface (3, 3'), wherein central cutting surfaces (25, 25') are adjacent to the primary cutting surfaces (3, 3'), and wherein the first free surfaces (15a, 15'a) are angled opposite the swarf surfaces (11, 27) such that the primary cutting surfaces (3, 3') and central cutting surfaces (25, 25') run outwards in the direction of a circumferential surface (17) of the drill (1) at a constant acute angle a.