Drilling Tool Centering via Marginal Edges and Central Recess
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Solution Overview
Problem
Drilling tools often break free or run untrue when drilling nonplanar surfaces, especially when dealing with cylindrical hollow bodies, due to the lack of effective centering and varying wall thickness, leading to inaccuracies and potential damage to the workpiece.
Innovation Solution
A drilling tool with two partial cutting edges at right angles to the center longitudinal axis, a central recess, and smooth radii transitions, which eliminates the need for a centering point at the drill end face, ensuring accurate drilling by centering via marginal cutting edges and a central clearance, and includes features like bevels, secondary cutting edges, and coolant passages for improved stability and concentricity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a centering point is arranged at the center of the drill end face, then the drilling tool can be centered on nonplanar surfaces, but the cutting speed at the center becomes zero causing the workpiece wall to be squeezed or damaged
Solution Approach 1:
The invention removes the harmful centering point from the drill end face and replaces it with a recess. This extraction eliminates the source of the problem (zero cutting speed causing workpiece damage) while maintaining the centering function through alternative means (marginal cutting edges and central clearance).
Solution Approach 2:
Instead of adding a protruding centering point at the center, the invention inverts the approach by creating a recess (clearance) at the center. This inversion transforms the harmful protruding element into a beneficial recess that eliminates workpiece damage while still enabling accurate centering through the marginal cutting edges.
2Productivity
If a traditional drill point is used, then the tool can penetrate through walls, but it breaks free or runs untrue laterally during drilling operations on nonplanar surfaces
Solution Approach 1:
The drill main cutting edge is segmented into two separate partial cutting edges positioned at the marginal regions of the end face. This segmentation allows each partial cutting edge to independently engage the workpiece wall, providing stable guidance and preventing lateral breakaway while maintaining drilling capability through the segmented cutting structure.
Solution Approach 2:
The central clearance acts as an intermediary element between the two partial cutting edges. It provides a reference plane for centering and ensures that the partial cutting edges remain properly positioned relative to each other, thereby maintaining drill hole accuracy while enabling effective cutting action.
Data Source
AI summary
A drilling tool includes a tool shank disposed about a center longitudinal axis. The tool shank having a holding region structured to be chucked in the chuck of a machine tool and an active region extending from the holding region. The drilling tool further includes at least two partial cutting edges formed on an end face of the active region and running at right angles to the center longitudinal axis and form a drill main cutting edge and a clearance formed in the end face between the partial cutting edges. The clearance being recessed axially along the center longitudinal axis toward the tool shank.