Single-Flute Indexable Drill Structure for Stable Chip Evacuation
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Solution Overview
Problem
Existing drilling tools experience instability and unbalanced cutting forces due to varying chip formation and transportation requirements between radially inner and outer cutting inserts, leading to vibrations and wear, especially in smaller diameter tools.
Innovation Solution
A drilling tool design with a single flute portion transitioning at an axially forward location, featuring a first flute portion that opens into the tool body and a second flute portion that opens to the peripheral surface, enhancing chip transport and torsional rigidity, while being manufactured as a single-piece body for economic production and improved stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a drilling tool has two separate flute portions running separately along the length of the tool, then chip transport is enabled, but the tool exhibits reduced stability and torsional rigidity
Solution Approach 1:
The patent merges two separate flute portions into a single integrated flute structure. The first flute portion extends from the radially inner cutting insert and the second flute portion extends from the radially outer cutting insert, but they are connected to form one continuous flute that runs along the tool body. This merging provides sufficient chip transport capacity for both inserts while significantly improving tool stability and torsional rigidity compared to having two separate flutes.
2Productivity
If cutting inserts are arranged at different radial positions, then chip formation varies, but this causes unbalanced cutting forces and vibrations
Solution Approach 1:
The patent applies local quality by providing different flute characteristics at different radial positions. The first flute portion (for the radially inner insert) and the second flute portion (for the radially outer insert) can have different geometries, depths, and configurations optimized for the specific chip formation characteristics at each radial position. This allows each insert to operate with optimal chip evacuation while the unified flute structure maintains overall force balance and reduces vibrations.
3Ease of operation
If the transition area is located at an axially forward location, then chip transport of smaller chips is improved, but the structural integrity may be compromised
Solution Approach 1:
The patent resolves the conflict between chip transport and structural integrity by utilizing the axial dimension strategically. The transition area is positioned in the axially forward region of the tool body, where it can effectively interact with and transport smaller chips generated by the radially inner insert. The transition is designed to occur within the robust tool body structure, maintaining sufficient material and structural integrity while still providing the desired chip transport function in the critical forward region.
Data Source
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AI summary
The present invention is related to a drilling tool (1) comprising a tool body (2) having a center axis (A) defining a longitudinal direction of the drilling tool (1), the tool body having an axially forward end (3) and an axially rearward end (4), the distance in the longitudinal direction between the forward end (3) and the rearward end (4) defining a length (L) of the drilling tool (1), and at least two indexable cutting inserts (5, 6), which are arranged at the axially forward end (3), a first indexable cutting insert (5) being arranged at a radially inner position (7) and a second indexable cutting insert (6) being arranged at a radially outer position (8), the tool body (2) comprising a first flute portion (9) extending axially rearward from the first indexable cutting insert (5), and a second flute portion (10) extending axially rearward from the second indexable cutting insert (6). The first flute portion (9) transitions into the second flute portion (10) at an axially forward transition area (11) of the tool body (2), thereby forming only one flute (12) of the drilling tool (1).