Multi-Flank Drill Design for CFRP Delamination and Heat Management
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Solution Overview
Problem
Drills used for drilling carbon fiber reinforced plastic (CFRP) face challenges in preventing inter-layer peeling and maintaining hole diameter accuracy, especially when frictional heat is not effectively released, and are difficult to produce in large quantities due to complex grindstone requirements.
Innovation Solution
A drill design featuring a first flank with a cutting edge, a second flank with a land portion, a third flank with a chisel edge, and a fourth flank surrounded by ridge lines from the first and third flanks, allowing frictional heat from the first flank to be quickly released via the fourth flank, which is produced by grinding an ordinary drill on a corner portion of a grindstone.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a fourth flank is designed to increase toward the outer peripheral direction to enhance swarf discharge, then swarf discharge ability is improved, but frictional heat from the first flank cannot be effectively released causing inter-layer peeling in high-density fiber materials
Solution Approach 1:
The drill flank is segmented into four distinct flanks (first, second, third, and fourth flanks) with specific functional assignments. The fourth flank is specifically designed as a heat release surface that is in contact with the first flank via a shared ridge line, creating a dedicated thermal management pathway separate from the swarf discharge function of other flanks.
Solution Approach 2:
Each flank is given different local qualities and functions: the first flank has a specific clearance angle for cutting, the second flank forms a land portion, the third flank has a different clearance angle for chip discharge, and the fourth flank is specifically designed as a heat release surface with contact to the first flank, optimizing each region for its specific purpose.
2Object-affected harmful factors
If the clearance angle of the third flank is made larger than the second flank using a grindstone with very small tip end, then inter-layer peeling is suppressed, but manufacturing complexity and skill requirements increase significantly
Solution Approach 1:
The invention specifies precise parameter ranges for the clearance angles (first clearance angle: 5-10 degrees, third clearance angle: 15-30 degrees) and the relative positioning of flanks. These parameter definitions enable standard grinding equipment to produce the required geometry without needing specialized small-tip grindstones, as the parameters are set within achievable ranges for conventional manufacturing.
3Manufacturing precision
If multiple flanks with specific clearance angles are designed to suppress inter-layer peeling, then hole diameter accuracy is improved, but the number of flanks and manufacturing precision requirements increase
Solution Approach 1:
The fourth flank serves multiple functions: it acts as a heat release surface for the first flank, provides structural support, and contributes to the overall geometry that enables accurate hole drilling. This multi-functionality reduces the need for additional specialized components while maintaining precision requirements.
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
The design effectively suppresses inter-layer peeling while maintaining hole diameter accuracy and simplifies the production process, enabling the drill to perform smoothly on CFRP without requiring skilled techniques for small tip end grindstones.
Implementation Method 1
the frictional heat generated in the first flank can be quickly released also from the fourth flank
Data Source
AI summary
A drill capable of suppressing inter-layer peeling (delamination) while keeping hole diameter accuracy even if the number of holed to be worked increases is provided. The drill includes a first flank which has a ridge line forming a cutting edge, a second flank which is adjacent to the first flank and has a ridge line forming a land portion, and a third flank which is adjacent to the first flank and has a ridge line forming a chisel edge. The drill further includes a fourth flank which is surrounded by a ridge line forming the first flank, a ridge line forming the third flank, and a trough line forming the second flank.