Drill Bit Diameter Enlargement for CFRP Bore Precision
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Solution Overview
Problem
Drilling tools struggle to produce bores in composite materials with consistent diameters within tight tolerances due to differing machining properties of layered materials, leading to diameter deviations and chip clogging issues, especially in abrasive materials like CFRP.
Innovation Solution
A drilling tool with a geometrically defined cutting edge and a diameter enlargement feature that mimics chip formation similar to a geometrically undefined cutting edge, allowing for grinding or honing-like machining, reducing chip size and preventing clogging, and featuring a diamond coating for enhanced material removal in composite materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional drilling tools with geometrically defined cutting edges are used, then drilling speed and productivity are improved, but diameter precision and consistency across different material layers deteriorate
Solution Approach 1:
The drilling tool is divided into two distinct functional regions: a first region with a geometrically defined cutting edge for rapid material removal, and a second region with a geometrically undefined cutting edge for precision diameter control. This segmentation allows each region to perform its specialized function optimally without compromising the other.
Solution Approach 2:
Different portions of the drilling tool are given different cutting edge geometries tailored to their specific functions. The first region has a sharp, geometrically defined cutting edge optimized for efficient cutting, while the second region has a rounded, geometrically undefined cutting edge optimized for diameter control and consistent material removal across layers with different elasticity.
2Manufacturing precision
If reaming is performed to achieve tight tolerances, then bore diameter precision is improved, but chip space capacity deteriorates leading to chip clogging
Solution Approach 1:
The function of separate reaming is extracted and integrated into the drilling process itself. The second region of the drilling tool performs the diameter-finishing function that would traditionally require a separate reaming operation, eliminating the need for additional chip spaces and avoiding chip clogging issues.
Solution Approach 2:
The drilling and reaming functions are merged into a single tool and a single operational step. The multi-region drilling tool combines roughing (first region) and finishing (second region) operations, allowing both functions to be performed simultaneously during one drilling pass without requiring separate chip spaces.
3Loss of time
If drilling and reaming are combined in one tool, then operation time is reduced, but chip space becomes even smaller causing severe chip clogging
Solution Approach 1:
The second region of the drilling tool is designed with a rounded, geometrically undefined cutting edge that removes material in a controlled, gradual manner similar to honing or grinding. This partial material removal approach prevents excessive chip formation while achieving the required diameter precision, effectively avoiding chip clogging even in combined drilling-reaming operations.
4Productivity
If drilling in composite materials with different material layers is performed, then productivity is maintained, but bore diameter consistency deteriorates due to different elasticity of materials
Solution Approach 1:
The cutting edge geometry parameter is changed between the two regions: the first region uses a sharp, geometrically defined cutting edge for efficient cutting, while the second region uses a rounded, geometrically undefined cutting edge. This parameter change allows the second region to accommodate the different elasticity of various material layers and maintain consistent bore diameter across all layers.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables the production of bores with precise diameters in composite materials in a single operation, minimizing wear and ensuring accurate tolerances without post-processing, even in abrasive materials like CFRP, by converting material removal into fine dust rather than long chips.
Implementation Method 1
The drilling tool has a long service life even in very abrasive materials such as CFRP... grinding or honing-like machining preferably takes place in the areas mentioned... no long shavings can form which could clog the chip spaces
Data Source
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AI summary
The invention relates to a drilling tool for producing drill holes, in particular in composite materials, having a tip (3) and a shaft (5) disposed opposite the tip (3) as seen in the direction of a longitudinal axis (7) of the drilling tool, wherein the drilling tool (1) comprises at least one geometrically defined cutting edge in the area of the tip (3), and having an expanded diameter (23) trailing the tip (3) as seen in the longitudinal direction from the tip (3), wherein the drilling tool (1) comprises a first area (25) preceding the expanded diameter (23) and having a first diameter, and a second area (27) trailing the expanded diameter (23) having a second diameter, the second diameter being greater than the first diameter. The drilling tool (1) is characterized in that the expanded diameter (23) and/or the second area (27) are designed such that chip formation takes place in the area of the expanded diameter (23) and/or in the second area (27) when machining a workpiece, said chip formation corresponding to that of machining a workpiece with a geometrically undefined cutting edge.