Indexable Center Drill Dual-Screw Locking Against Insert Oscillation
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Solution Overview
Problem
Conventional center drills face issues with restricted insert movement due to a large holder diameter and oscillation caused by single screw locking, leading to reduced machining efficiency and surface roughness when drilling steps or narrow grooves, and increased oscillation frequency at higher speeds.
Innovation Solution
An indexable center drill structure with a holder and insert featuring a dual-screw locking mechanism, including positioning posts and notches, which enhances locking strength and stability, allowing the insert to be securely fixed in both longitudinal and transverse directions, thereby resisting torque and preventing oscillation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single screw locking mechanism is used, then the device complexity is reduced, but the insert oscillates and wobbles during cutting operations
Solution Approach 1:
The locking mechanism is segmented into multiple independent screws (at least two screws arranged along the longitudinal direction) instead of using a single screw. Each screw independently contributes to holding the insert, distributing the locking function across multiple elements. This segmentation provides redundancy and stability while preventing the oscillation and wobbling that occurs with a single screw mechanism.
2Adaptability or versatility
If the holder diameter is reduced, then the adaptability to workpieces with steps or narrow grooves is improved, but the insert becomes more restricted during drilling
Solution Approach 1:
The solution addresses the spatial constraint by changing the dimensional arrangement of the screws from a single-point locking to a distributed arrangement along the longitudinal direction. This dimensional redistribution allows the holder diameter to be reduced for better adaptability to narrow workpieces, while the longitudinal screw arrangement maintains sufficient insert support and drilling capability without interference.
3Manufacturing precision
If a single screw locks the insert, then the manufacturing precision is maintained within tolerance, but the insert oscillates at higher cutting speeds
Solution Approach 1:
The oscillation and wobbling caused by a single screw at high speeds is counteracted by introducing additional screws arranged along the longitudinal direction. These additional screws act as counterbalancing support elements that resist the oscillatory forces generated during high-speed cutting, thereby maintaining manufacturing precision and dimensional accuracy even at elevated cutting speeds.
Data Source
AI summary
An indexable center drill structure comprises a holder, an insert, and at least two screws. The screws are locked to at least two screw holes of the holder and at least two positioning holes of the insert. Through cooperation of two positioning posts and two positioning notches of the holder and the insert, the insert is fixed and locked to an insert attachment seat of the holder in a longitudinal direction and in a transverse direction. Thus, the locking strength between the insert and the holder is increased, and the overall structure is simplified.