Asymmetric Cutting Insert Mounting for Stable Ball Nose End Mills
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Solution Overview
Problem
Indexable ball nose end mills face issues with the cutting insert not being firmly fixed to the tool body due to insufficient support from screws, leading to deformation or breakage, and additional manufacturing processes increase costs and fatigue from concentrated cutting vibrations.
Innovation Solution
A cutting insert with a ridge portion on its lower surface and asymmetric inclined surfaces to prevent rotation and ensure stable fastening, combined with a rotary cutting tool design featuring specific insert pockets and screws for secure mounting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a screw is used to fasten the cutting insert to the tool body, then the cutting insert can be mounted, but the screw cannot sufficiently support the reaction force generated by the cutting force
Solution Approach 1:
The lower surface of the cutting insert is divided into multiple inclined surfaces (first inclined surface, second inclined surface, third inclined surface) with different orientations. Each inclined surface distributes the reaction force generated by cutting in different directions, preventing concentration of force on a single screw connection point and thereby improving fixing reliability.
Solution Approach 2:
The cutting insert employs asymmetric inclined surfaces with different angles and orientations on its lower surface. This asymmetric design optimizes the distribution of cutting forces according to the specific machining conditions and insert orientation, enhancing the overall fastening effectiveness and reliability beyond what symmetric designs could achieve.
2Reliability
If a protrusion and concave groove structure is added to prevent rotation, then the cutting insert can be firmly fixed, but additional manufacturing processes are required increasing cost
Solution Approach 1:
Instead of adding complex protrusion and concave groove structures, the invention modifies the local geometry of the lower surface by creating multiple inclined surfaces with specific angles. This local geometric optimization provides both rotational prevention and force distribution without requiring additional manufacturing processes, thereby maintaining ease of manufacture while improving fixing reliability.
3Device complexity
If the cutting insert is fixed only with a screw, then the structure is simple, but the cutting insert rotates around the screw due to reaction force
Solution Approach 1:
The invention transitions from a single-point fastening approach (screw only) to a multi-dimensional force distribution system. By creating inclined surfaces at different angles and orientations, the solution distributes forces across multiple dimensions and directions, preventing rotational movement while maintaining relative structural simplicity.
4Reliability
If protrusion and concave groove are used to prevent rotation, then the cutting insert is firmly fixed, but cutting vibration and force are concentrated to these coupling portions causing fatigue
Solution Approach 1:
The lower surface is segmented into multiple inclined surfaces that distribute cutting forces and vibrations across different areas and directions. This segmentation prevents concentration of stress at single coupling points, thereby improving fatigue resistance while maintaining fixing reliability through the collective action of all inclined surfaces.
Data Source
AI summary
A cutting insert includes an upper surface, a lower surface opposite to the upper surface, a first side surface and a second side surface configured to connect the upper surface and the lower surface, a mounting hole formed to penetrate the upper surface and the lower surface, a first cutting edge formed at an edge of the upper surface that meets the first side surface, and a second cutting edge formed at an edge of the upper surface that meets the second side surface. The lower surface includes a ridge portion, and a first inclined surface and a second inclined surface positioned on both sides of the ridge portion as a boundary. When looking at the lower surface, the first inclined surface and the second inclined surface have asymmetric shapes with respect to the ridge portion.