Rotary Cutting Tool Flute Geometry for Delamination-Free Composite Machining
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Solution Overview
Problem
Existing rotary cutting tools face challenges when machining composite materials, including delamination, fiber pullout, and poor surface finish, due to non-point or linear contact between the cutting edge and the material.
Innovation Solution
The disclosed rotary cutting tool features a unique flute system with continuous major flutes and discontinuous minor flutes, forming teeth with first and second cutting edges that meet at an apex. This design includes true relief surfaces radially inward from an imaginary cylinder, preventing surface contact with the workpiece and optimizing cutting dynamics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional rotary cutting tools with continuous flutes are used, then material removal is efficient, but fiber pullout and delamination occur due to non-point contact between cutting edge and material
Solution Approach 1:
The continuous flute is segmented into multiple discrete cutting elements (teeth) arranged along the flute path. Each tooth has a defined apex and cutting edges, transforming the continuous cutting action into a series of discrete point contacts. This segmentation allows material removal while preventing the non-point contact that causes fiber pullout and delamination.
Solution Approach 2:
The invention introduces a new geometric dimension by positioning the cutting edges at specific radial distances from the tool axis, creating a three-dimensional cutting path. The apex of each tooth contacts the material first, followed by the cutting edges at different radial positions, creating a controlled point-contact cutting mechanism that eliminates harmful surface contact.
2Force
If the cutting edge contacts the workpiece over a large area, then cutting forces are distributed, but fiber pullout and delamination occur due to non-point contact
Solution Approach 1:
The cutting tool is designed with locally optimized contact geometry where only specific points (apex and cutting edges) contact the workpiece. The face portion of each tooth is shaped so that the apex contacts first, followed by the cutting edges at precisely controlled locations. This local point-contact quality prevents the distributed non-point contact that causes fiber damage while maintaining effective cutting forces.
3Strength
If the face portion of the tooth contacts the workpiece, then support is provided during cutting, but surface contact causes fiber pullout and delamination
Solution Approach 1:
The harmful surface contact function is extracted from the tooth face portion by designing it with a specific geometry where the apex and cutting edges are positioned radially inward from the outer surface of the face. This extraction removes the harmful surface contact capability while preserving the supportive function through the controlled point contacts of the apex and cutting edges during the cutting stroke.
Data Source
AI summary
Rotary cutting tool (100) having plurality of major flutes (130) arranged helically opposite to plurality of discontinuous minor flutes (135) and intersecting to form plurality of teeth. Each tooth includes a first cutting edge formed with the major flute and a second cutting edge formed with the minor flute, the first and second cutting edges meeting at an apex and form part of a periphery of a quadrilateral-shaped face portion. The face portion has non-planar surfaces extending from the respective first and second cutting edges that define a relief surface of each cutting edge. First and second cutting edges are arranged on an imaginary cylinder having a center axis coaxial with the axis of rotation of the tool and respective relief surfaces are radially inward of a surface of the imaginary cylinder such that the first and second cutting edges each have a clearance in a rotational direction of the tool.