Step Drill Bit with Deburring Recess for Accurate Hole Sizing

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Solution Overview

Problem

Step drill bits face challenges in efficiently drilling multiple hole sizes without enlarging the holes or causing marring, and existing designs lack effective deburring mechanisms to remove burrs without increasing hole diameter.

Innovation Solution

The step drill bit features a shank portion coupled to a power tool with a cutting head having progressively increasing diameter steps, each with conical and cylindrical portions, a depth stop flange, and a deburring recess to prevent marring and remove burrs, featuring specific angles and configurations to inhibit cutting and marring, and a deburring edge to smooth hole edges.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If step drill bits are used to drill multiple hole sizes, then versatility is improved, but manufacturing precision deteriorates due to hole enlargement and marring

Engineering Contradiction:

Improveability to drill multiple hole sizesVSAvoidhole diameter accuracy

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The cutting head is divided into multiple discrete steps, each with a specific diameter for drilling different hole sizes. Each step acts as an independent cutting element with its own primary and secondary cutting edges, allowing sequential drilling of multiple sizes while maintaining precise control over each hole's final diameter through the cylindrical portion that guides the step along the axis.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different portions of each step have specialized geometries: the conical tapered portion performs the primary cutting action, while the cylindrical portion provides guidance and maintains dimensional accuracy. The deburring recess with its specific angle creates a secondary cutting edge localized at the step's rear end, addressing the specific need for burr removal without affecting the primary hole diameter.

Inventive Principle:

Principle #3Local quality

2Productivity

If conventional step drill bits are used, then productivity is improved by drilling multiple sizes, but object-generated harmful factors worsen due to burr formation and surface marring

Engineering Contradiction:

Improvenumber of hole sizes drilled per bitVSAvoidburr formation and surface marring

Core Design Contradiction:

ProductivityVSObject-generated harmful factors

Solution Approach 1:

The deburring recess is positioned at the rear end of each step, allowing the secondary cutting edge to perform deburring action immediately after the primary cutting edge creates the hole. This preliminary deburring prevents burr formation before the workpiece is removed from the tool, eliminating the need for separate deburring operations.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The design converts the potentially harmful effect of the step's rear end contacting the workpiece surface into a beneficial deburring action. By positioning the deburring recess to create a secondary cutting edge at the rear, the contact that would normally cause marring is transformed into a controlled cutting action that removes burrs and smooths the surface.

Inventive Principle:

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

3Manufacturing precision

If depth stop flange is added to control drilling depth, then manufacturing precision is improved, but object-affected harmful factors worsen due to potential cutting and marring of workpiece

Engineering Contradiction:

Improvedrilling depth controlVSAvoidworkpiece cutting and marring

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The depth stop flange features a localized conical tapered portion with a smaller angle compared to the main cutting steps. This localized geometry creates a non-cutting surface that contacts the workpiece at a shallow angle, preventing the flange from acting as a cutting tool while still providing effective depth control through radial extension.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The angle of the depth stop flange's tapered portion is specifically designed to be smaller than the cutting angles of the main steps. This parameter change transforms the flange from a potential cutting element into a non-cutting depth stop, as the reduced angle prevents the flange edges from engaging the workpiece in a cutting manner while maintaining depth control functionality.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS20240051040A1Step drill bit

Publication Date: 2024.02.15 BLACK & DECKER CORP

AI summary

A step drill bit includes a cutting head portion with a rear end coupled to a shank portion. The cutting head portion incudes a front cutting tip, a plurality of steps of progressively increasing diameter from the cutting head to the rear end portion. Each step includes a conical tapered portion that flares radially outward from the axis and a generally cylindrical portion that extends axially rearward from the tapered portion. A flute extends through the steps generally parallel to or helically relative to the axis. Primary and secondary cutting edges are formed at junctions between the tapered portions and the generally cylindrical portions and the flute. A depth stop flange extends radially outward from a rearmost step and has a diameter greater than the diameter of the cylindrical portion of the rearmost step. A deburring recess is disposed within or between one of the steps and includes a deburring edge at a junction between the deburring recess and the flute to remove burrs from an edge of a hole.