Segmented Drill Flute Geometry for Stable Chip Curl and Discharge

Solution Overview

Problem

Conventional drills face challenges in curling chips at a small radius of curvature, leading to chip clogging and reduced chip discharge performance due to the design of the twisted flute, where a small convex curved surface hinders chip curling at the front end and a large surface compromises chip flow at the rear end.

Innovation Solution

The drill design incorporates a main body with a cutting edge and two flutes, where the first flute features a concave curvilinear shape on the rear side and a convex curvilinear shape on the front side in cross-section, allowing chips to be curled at a small radius of curvature for stable discharge, while the second flute has a concave shape to prevent clogging by maintaining a larger space for chip flow.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the convex curved surface is made small in the twisted flute, then chip discharge performance is improved, but it becomes difficult to curl chips at a small radius of curvature on the front end side

Engineering Contradiction:

Improvechip discharge performanceVSAvoidchip curling capability

Core Design Contradiction:

ProductivityVSEase of operation

Solution Approach 1:

The flute is divided into multiple segments along the rotation axis: a first flute portion near the cutting edge with a convex curved surface for chip curling, a second flute portion in the middle with a concave curved surface for stable chip flow, and a third flute portion at the rear end with a convex curved surface for final chip discharge. This segmentation allows each portion to optimize for its specific function, resolving the contradiction between chip curling and discharge performance.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different portions of the flute are given different cross-sectional shapes tailored to their specific functions: the front portion has a convex shape optimized for initiating chip curl, the middle portion has a concave shape optimized for maintaining stable chip flow at small radius, and the rear portion has a convex shape optimized for chip discharge. This local differentiation resolves the contradiction by allowing optimal geometry in each zone.

Inventive Principle:

Principle #3Local quality

2Ease of operation

If the convex curved surface is made large in the twisted flute, then chip curling at small radius of curvature is improved, but chip discharge performance is lowered on the rear end side due to narrow space

Engineering Contradiction:

Improvechip curling capabilityVSAvoidchip discharge performance

Core Design Contradiction:

Ease of operationVSProductivity

Solution Approach 1:

The flute is divided into multiple segments along the rotation axis: a first flute portion near the cutting edge with a convex curved surface for chip curling, a second flute portion in the middle with a concave curved surface for stable chip flow, and a third flute portion at the rear end with a convex curved surface for final chip discharge. This segmentation allows each portion to optimize for its specific function, resolving the contradiction between chip curling and discharge performance.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different portions of the flute are given different cross-sectional shapes tailored to their specific functions: the front portion has a convex shape optimized for initiating chip curl, the middle portion has a concave shape optimized for maintaining stable chip flow at small radius, and the rear portion has a convex shape optimized for chip discharge. This local differentiation resolves the contradiction by allowing optimal geometry in each zone.

Inventive Principle:

Principle #3Local quality

3Ease of manufacture

If the twisted flute has a uniform cross-sectional shape, then manufacturing is simplified, but chip flow speed decreases away from the cutting edge leading to chip clogging

Engineering Contradiction:

Improveflute manufacturing simplicityVSAvoidchip flow speed

Core Design Contradiction:

Ease of manufactureVSProductivity

Solution Approach 1:

The flute cross-sectional shape varies locally along the rotation axis to match the specific requirements at each position: convex near the cutting edge for chip curl initiation, concave in the middle for stable chip flow maintenance, and convex at the rear for chip discharge. This local optimization prevents chip clogging while remaining manufacturable through standard processes.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The flute geometry transitions dynamically along the rotation axis rather than remaining static and uniform. The cross-sectional shape changes continuously from convex to concave to convex, adapting to the varying chip flow conditions at different positions from the cutting edge to the rear end, thereby maintaining optimal chip flow speed throughout.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS11872641B2Drill and method for manufacturing machined product

Publication Date: 2024.01.16 KYOCERA CORP

AI summary

A drill may include a main body having a bar shape extending from a first end to a second end. The main body may be rotatable around a rotation axis. The main body may include a cutting edge, a first flute extending from the cutting edge, and a second flute extending from the first flute. The first flute may include, in a cross section orthogonal to the rotation axis, a first portion having a concave curvilinear shape located at a rear side in a rotation direction, and a second portion having a convex curvilinear shape located at a front side in the rotation direction. The second flute has a concave curvilinear shape from an end portion located at a front side in the rotation direction to an end portion located at a rear side in the rotation direction in the cross section.