Segmented Drill Cutting Edges for High-Feed Chip Control
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Solution Overview
Problem
Conventional drilling tools with chip dividers struggle with high drilling feeds, leading to band chips that can jam and cause tool damage, especially in large diameter drilling applications, and fail to effectively manage feed forces in carbon fibre-reinforced plastics, resulting in delamination and fraying.
Innovation Solution
A drilling tool design featuring multiple offset drill cutting edges with strategically placed chip dividers that interrupt the cutting edges, allowing for high axial drilling feeds of at least 9% of the diameter per revolution, and chip removal grooves that extend beyond the bore depth to evacuate chips, combined with a guide area for self-guidance and lubrication, preventing chip jamming and improving feed control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If chip dividers are provided in large diameter drilling tools, then wide drilling chips are divided into narrower chips, but significantly longer and less curled band chips are produced that can get jammed between the tool and bore wall causing tool breakage
Solution Approach 1:
The drill cutting edge is segmented into multiple partial cutting edges (first, second, third partial cutting edges) separated by grooves. This segmentation allows the cutting edge to create chips of controlled length and curl, preventing band chip formation while maintaining effective chip division for large diameter drilling applications.
Solution Approach 2:
Different sections of the drill cutting edge have different properties - the first partial cutting edge has specific geometry for initial cutting, the second partial cutting edge (at the groove end) has different orientation for chip curling, and the third partial cutting edge completes the cut. Each section is optimized for its specific function to produce controlled chip morphology.
2Productivity
If high axial drilling feeds are used, then drilling efficiency is improved, but chip jamming occurs leading to tool damage
Solution Approach 1:
The cutting edge is divided into multiple partial cutting edges that work in sequence during high feed drilling. This segmentation creates natural chip breaking points that prevent long band chips from forming, even at high axial feed rates, thereby maintaining tool safety while maximizing productivity.
Solution Approach 2:
The periodic interruption of the cutting edge by grooves creates regular chip breaking zones. As the drill rotates, this periodic structure ensures that chips are continuously broken into manageable lengths, preventing jamming during high-speed drilling operations.
3Productivity
If conventional drill cutting edges are used in carbon fibre-reinforced plastics, then drilling proceeds, but delamination of fibre layers and drilling burrs occur causing edge fraying
Solution Approach 1:
The segmented cutting edge with multiple partial cutting edges and intervening grooves creates a more controlled cutting action in carbon fibre-reinforced plastics. This segmentation reduces feed forces and prevents delamination by distributing the cutting load, while the groove geometry controls chip formation to minimize burrs and edge fraying.
Solution Approach 2:
The second partial cutting edge at the groove end is specifically oriented to reduce feed forces on the workpiece surface, preventing delamination. The groove geometry is optimized to control chip evacuation and minimize burr formation, addressing the specific requirements of composite material drilling.
Data Source
AI summary
A drilling tool for producing a bore with a cylindrical inner wall can be rotatable in a rotary movement with a predetermined rotational direction (VD) about a tool axis (A) extending through the drilling tool, and at the same time is movable in an axial forward movement (VB) in a forward direction axially to the tool axis. The drilling tool comprises at least one drilling area (3) arranged in a forwardly located region of the drilling tool at a forward or free end, but preferably not having a thread forming region. The drilling area has a number n of drilling edges which are arranged offset to each other in the rotational direction, and at least one chip divider is arranged on at least one or each of the n drill cutting edges, where the chip divider forms an interruption of the respective drill cutting edge.