Step Drill Rake Surface Geometry for Chip Discharge

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Conventional step drills suffer from inferior chip discharge performance, leading to clogged through holes and potential damage to the inner wall surface or fracture of the cutting edge during hole formation.

Innovation Solution

A drill design featuring a cylindrical cutting portion with a first region and a second region having a step, where the second region includes second cutting edges, flutes, and rake surfaces with specific geometries that enhance chip discharge by allowing chips to pass smoothly through the flute, preventing clogging and reducing the risk of cutting edge fracture.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a conventional step drill is used to form through holes, then stepped holes and chamfered holes can be formed at a time, but chip discharge performance is inferior causing hole clogging and potential damage

Engineering Contradiction:

Improvechip discharge performanceVSAvoidhole clogging and cutting edge damage

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent applies local quality by creating a specific geometric configuration of the second rake surface with different length characteristics in different regions. The second outward surface has a longer rake surface length than the second central surface, creating a localized geometry that specifically addresses chip discharge at the critical region near the second cutting edge. This local geometric optimization enables effective chip evacuation from the stepped portion without requiring a complete redesign of the entire drill structure.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent utilizes curvature principles by forming the second outward surface with specific geometric characteristics that create a curved or inclined surface profile. This curved geometry of the second rake surface facilitates smooth chip flow and discharge by reducing abrupt changes in chip direction, allowing chips to be efficiently evacuated from the hole through the flute structure.

Inventive Principle:

Principle #14Spheroidality (Curvature)

2Ease of manufacture

If conventional step drill geometry is used, then manufacturing simplicity is maintained, but chip discharge performance is poor leading to production issues

Engineering Contradiction:

Improvedrill structure simplicityVSAvoidchip discharge performance

Core Design Contradiction:

Ease of manufactureVSProductivity

Solution Approach 1:

The invention maintains overall manufacturing simplicity while introducing a localized geometric feature - the second outward surface with extended rake length. This local modification can be integrated into existing drill manufacturing processes without requiring complete redesign, thus preserving ease of manufacture while significantly improving chip discharge performance in the critical stepped region.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent applies parameter changes by modifying the rake surface length parameter specifically in the second outward surface region. By increasing the rake surface length in this localized area compared to the second central surface, the geometry is optimized for chip discharge while maintaining compatibility with standard manufacturing capabilities.

Inventive Principle:

Principle #35Parameter changes

3Manufacturing precision

If through holes are formed with conventional drills, then hole formation is attempted, but holes are prone to be clogged with produced chip causing damage

Engineering Contradiction:

Improvehole qualityVSAvoidchip clogging and wall surface damage

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The patent converts the potentially harmful accumulation of chips into a beneficial discharge flow by designing the second outward surface geometry. The extended rake surface length in the second outward surface creates a chip flow path that directs chips toward the flute opening, transforming what would be a clogging problem into an efficient chip evacuation system that protects the hole wall surface from damage.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The second outward surface with its specific geometry acts as an intermediary element between the second cutting edge and the flute opening. This intermediate geometric structure facilitates the transition of chips from the cutting zone to the discharge path, preventing direct contact between accumulated chips and the hole wall surface, thus avoiding damage.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS9623488B2Drill and method of manufacturing machined product

Publication Date: 2017.04.18 KYOCERA CORP

AI summary

A drill includes a substantially cylindrical cutting portion includes a first region located at a front end portion, and a second region which has a step whose diameter increases as going from the first region to a rear end in a sectional view perpendicular to a rotation axis, and which is continuous with the first region in an end of the second region on a side of the step, and using this drill, a method of manufacturing a machined product is provided.