Conical Centering Drill Geometry for Vibration-Stable Metal Drilling
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Solution Overview
Problem
Conventional metal drilling tools experience vibrations and reduced service life due to pendulum movements, leading to poor hole quality and increased wear, especially when producing cylindrical holes.
Innovation Solution
A metal drilling tool with a centering portion featuring a conical surface and multiple edges that replaces the chisel edge, providing improved self-centering and stability, minimizing torsional and axial vibrations, and enhancing drilling precision and surface quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a chisel edge is provided between primary cutting edges to enable self-centering, then self-centering capability is improved, but pendulum movements and vibrations occur along the chisel edge extension
Solution Approach 1:
The invention removes the chisel edge from the drilling tool design. By extracting this problematic component that causes pendulum movements and vibrations, the tool achieves stable drilling without self-centering capability provided by the chisel edge. The self-centering function is replaced by other means such as guide surfaces or initial penetration by primary cutting edges.
Solution Approach 2:
Instead of using a chisel edge to provide self-centering (conventional approach), the invention inverts the approach by using the primary cutting edges themselves or guide surfaces to achieve centering. The tool may use a different geometry where the primary cutting edges are positioned to naturally guide the drill to the center, or where guide surfaces perform the centering function before cutting begins.
2Object-generated harmful factors
If three primary cutting edges with three chisel edge segments are provided to improve tool guidance, then pendulum movements are partially suppressed, but relatively large pressing forces are required during machining
Solution Approach 1:
The invention removes the chisel edge entirely from the tool design, replacing it with a different configuration of primary cutting edges. This extraction eliminates the need for chisel edge segments that would require large pressing forces, while still achieving stable tool guidance through alternative means such as optimized primary cutting edge positioning or guide surfaces.
Solution Approach 2:
The invention changes the geometric parameters of the cutting edges, specifically the arrangement and angles of the primary cutting edges. By optimizing these parameters, the tool achieves effective guidance and stable drilling with reduced pressing forces compared to conventional three-edge designs with chisel segments.
3Length of moving object
If the length of the metal drilling tool is increased, then the ability to drill deeper holes is improved, but inherent stability decreases leading to increased vibrations
Solution Approach 1:
The invention removes the chisel edge that amplifies vibrations in long drills. By eliminating this component, the tool maintains better stability at increased lengths, as the primary cutting edges and guide surfaces provide more stable cutting action without the pendulum movements characteristic of chisel-edge designs.
Solution Approach 2:
Instead of relying on a chisel edge for centering in long drills (which causes instability), the invention uses alternative centering methods such as guide surfaces or optimized primary cutting edge positioning that maintain stability even when the tool length is increased for deeper drilling applications.
Data Source
AI summary
A metal drilling tool comprising includes a middle axis, a front side and an opposite end, with at least two cutting edges arranged in a region of the front side, a first free surface being associated with each cutting edge. The at least two cutting edges lie on an imaginary first conical surface arranged concentrically in relation to the middle axis, with a first conical angle that opens up towards the opposite end and reaches a maximum of 180°. A centering section includes at least three edges, at least three side surfaces and an imaginary base surface. At least two of the edges lie on an imaginary second conical surface which is arranged concentrically in relation to the middle axis and has a second conical angle that opens up towards the opposite end. The second conical angle is smaller than the first conical angle, such that the imaginary second conical surface, seen from the opposite end, projects opposite the front surface.