AFRP Drill Bit Geometry for Low-Delamination Hole Making
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Solution Overview
Problem
Drilling aramid fiber-reinforced plastic (AFRP) materials results in delamination and burrs due to high trust forces and anisotropic properties, leading to reduced bearing capacity and safety risks, and existing tools lack versatility and require extensive experimental testing for design.
Innovation Solution
A hole making tool with a step reversed point angle structure and optimized design method for diameter ratio and point angles, converting axial compression into tension to reduce trust force and improve cutting efficiency, featuring a multiple point angle drill tip, reversed point angle reaming region, and shank clamping region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a traditional metal cutting tool is used for drilling AFRP, then the tool structure is simple and easy to manufacture, but delamination and burrs occur easily at the outlet due to high trust force and anisotropic characteristics of AFRP
Solution Approach 1:
The drill bit is divided into multiple working regions with different functions: a drilling type tip region for initial penetration, a reversed point angle reaming region for fiber cutting and tension conversion, and a reaming region for final hole formation. This segmentation allows each region to address specific problems (delamination, burrs, fiber toughness) without requiring complete redesign of the entire tool.
Solution Approach 2:
The reversed point angle structure inverts the conventional drill geometry by using negative rake angles and inverted cutting edge configurations. This inversion converts the axial compression effect into an axial tension effect, which is particularly effective for cutting high-toughness aramid fibers and reducing delamination at the hole outlet.
2Manufacturing precision
If an aramid drill bit with outer cutting edge is used, then hole making quality is improved, but the trust force becomes excessively large causing delamination at the outlet
Solution Approach 1:
Different regions of the drill bit are assigned different geometric properties and functions. The drilling type tip region has positive rake angles for efficient material removal, while the reversed point angle reaming region has negative rake angles specifically designed to reduce trust force and prevent delamination. This local differentiation allows the tool to maintain high cutting efficiency while avoiding excessive trust force at critical locations.
3Manufacturing precision
If a stepped sawtooth tool with vertical edge is used for CFRP/aluminum alloy laminated structure, then processing damage is inhibited, but it is difficult to control processing damage of AFRP due to different material properties
Solution Approach 1:
The tool design incorporates variable geometric parameters including different point angles, rake angles, and radial widths across different regions. The step diameter ratio and point angles are specifically optimized for AFRP's unique properties (interlayer bonding strength, fiber toughness, anisotropic characteristics). This parameter optimization allows the tool to adapt to AFRP's specific requirements rather than using a generic design that works for other composites.
4Manufacturing precision
If existing hole making tool structural parameters are determined through experimental tests, then the tool can be optimized for specific applications, but human, financial and material resources are extremely consuming
Solution Approach 1:
The patent establishes preliminary design guidelines and theoretical frameworks for determining optimal tool parameters based on AFRP material properties and processing requirements. By pre-defining the relationship between material characteristics, tool geometry, and processing outcomes, designers can select appropriate parameters without conducting extensive experimental trials, significantly reducing development time and resources.
Data Source
AI summary
The present invention belongs to the technical field of composite material processing, and relates to a hole making tool for aramid fiber-reinforced plastic and a design method thereof. The drill bit has a step reversed point angle structure, which can reduce a trust force during drilling and effectively cut off a high toughness aramid fiber, thus to improve the hole making quality of an AFRP-related component. It is proved that the new tool can significantly improve the hole making quality of an AFRP component, improve the service life and safety degree, and greatly reduce the processing cost. Therefore, the present invention has a broad application prospect in the fields of aerospace, military industries and civil application.