Replaceable Drill Cutting Head for FRP Delamination Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Drills used for machining layered sheets of FRP with metal laminated on CFRP face issues with bit chipping and delamination during machining, leading to reduced durability and product quality.
Innovation Solution
A bit exchangeable drill with a detachable cutting head featuring a linear cutting edge, negative axial rake angle, and a helical flute, along with a back taper and double margin design, reduces delamination and improves durability by minimizing heat generation and maintaining cutting sharpness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If bit strengthening treatment by applying negative land and honing is used, then bit chipping is prevented, but cutting sharpness becomes blunt and delamination occurs
Solution Approach 1:
The drill bit is divided into two separable parts: a reusable drill body and a replaceable cutting head. The cutting head can be detached and replaced when worn, while the drill body remains. This segmentation allows the cutting edge to be renewed without replacing the entire bit, maintaining sharpness while preventing chipping through proper design of the cutting head geometry.
Solution Approach 2:
The invention changes the geometric parameters of the cutting head, specifically providing a positive rake angle (5° to 15°) and optimized clearance angles, rather than using negative land and honing treatments. This parameter optimization maintains cutting sharpness while providing sufficient strength to prevent chipping during machining of laminated sheets.
2Manufacturing precision
If multi-stage point angle is used, then burr generation is suppressed, but bit chipping occurs when meeting pilot holes in laminated sheets
Solution Approach 1:
The cutting head is designed with different local geometries optimized for specific functions: the cutting edges have positive rake angles for sharp cutting and burr suppression, while the overall structure includes reinforced features like a tapered bore and specific margin designs to prevent chipping when encountering pilot holes in laminated sheet materials.
Solution Approach 2:
The cutting head is made from composite material comprising cobalt, chromium, and tungsten (Co-Cr-W alloy), which provides both the sharpness needed for clean cutting and the toughness required to resist chipping when meeting pilot holes, combining properties that cannot be achieved with single materials.
3Force
If solid drill with general configuration is used for pilot hole boring, then working force increase is suppressed, but bit chipping occurs when meeting the pilot hole
Solution Approach 1:
The drill design incorporates dynamic features including a helical flute configuration optimized for chip evacuation and reduced cutting resistance, allowing the drill to maintain lower working forces while the replaceable cutting head with optimized geometry resists chipping when encountering pilot holes in laminated materials.
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
A bit exchangeable drill includes a detachable cutting head (2) at the tip of a drill body (1), and the cutting head (2) includes a cutting edge (4) extending linearly from a rotation center to a radial outer end in axial end view, and a helical flute (5). At a rake face (9) continuous with the cutting edge (4), a thinning face (10) inclined relative to the rotation axis (CL) and rendering an axial rake angle of the cutting edge negative is formed entirely from a radial inner end to a radial outer end of the cutting edge.