Drill Bit Center Cutting Edge Segmentation for Stability and Chip Space
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Solution Overview
Problem
Conventional drills face challenges in achieving both sufficient stability of the center cutting edge and a large enough chip space, particularly when machining tough materials like stainless steel, as these requirements are mutually exclusive due to the trade-off between wedge angle and chip space volume.
Innovation Solution
The drill features at least one main cutting edge and a central cutting edge with two partial cutting edges, where the radially inner partial cutting edge has greater stability with a smaller chip space and the radially outer partial cutting edge has a smaller wedge angle with a larger chip space, allowing optimal adjustment to cutting speed and chip volume requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the wedge angle of the central cutting edge is increased to improve stability, then the stability of the center cutting edge is improved, but the chip space is reduced
Solution Approach 1:
The central cutting edge is divided into multiple partial cutting edges (typically two or three) with different wedge angles. The radially inner partial cutting edge has a larger wedge angle for stability, while the radially outer partial cutting edge has a smaller wedge angle for larger chip space. This segmentation allows each partial cutting edge to be optimized for its specific functional requirements.
Solution Approach 2:
Different regions of the central cutting edge are given different geometric properties. The radially inner region (closer to the drill axis) has a larger wedge angle to provide stability and support for absorbing cutting forces, while the radially outer region has a smaller wedge angle to provide larger chip space for efficient chip removal. This local differentiation resolves the contradiction by allowing each region to optimize for its specific function.
2Force
If the center area is shortened through point thinning to reduce rotational resistance, then the rotational resistance is reduced, but the stability of the center cutting edge is compromised
Solution Approach 1:
The point thinning process is applied in multiple stages or with multiple grooves at different radial positions. Each thinning groove creates a partial cutting edge with appropriate wedge angle. The combination of multiple thinnings reduces the overall center area and rotational resistance while maintaining sufficient stability through the distributed geometry of multiple partial cutting edges.
Solution Approach 2:
The wedge angle parameter is varied along the radial direction of the central cutting edge. By changing the wedge angle from the radially inner region to the radially outer region, the design achieves both reduced rotational resistance (through overall point thinning) and maintained stability (through larger wedge angles in the inner region where forces are highest).
Data Source
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AI summary
The invention proposes a drill bit (1) having at least one main cutting edge (3, 3') and at least one center cutting edge (15, 15'), wherein the drill bit (1) comprises a longitudinal axis (13), and wherein the at least one main cutting edge (3, 3') and the at least one center cutting edge (15, 15') are each assigned a rake face (7, 7', 11, 11'). The drill bit (1) is characterized in that the rake face (11, 11') assigned to the at least one center cutting edge (15, 15') has at least two part faces (19, 19'; 21, 21') which - as seen as perpendicular to the longitudinal axis (13) of the drill bit (1) - form an obtuse angle with one another, so that the at least one center cutting edge (15, 15') comprises at least two part cutting edges (23, 23'; 25, 25').