O-Flute Multipurpose Bit Asymmetric Geometry for Plastic Cutting

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Solution Overview

Problem

Existing combination drill and milling bits fail to produce clean cuts and control when used in softer materials like plastics, often resulting in ridges and burrs due to loss of control over the cutting process.

Innovation Solution

A tool bit design featuring a working section with a longitudinally extending central axis, an O-flute, and a tooth offset from the central axis, along with specific angles and features like relief faces and a gash, which stabilizes the bit and improves control during plunge cutting and milling in plastics.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a standard drill bit with conventional flutes is used for plunge cutting in plastic materials, then the bit can penetrate the material, but it loses control and aggressively bites into the soft material causing off-axis forces

Engineering Contradiction:

Improvecontrol of bit during plunge cuttingVSAvoidstability of bit on axis

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The drill bit employs an asymmetric flute configuration where the first flute has a different geometry than the second flute. Specifically, the first flute has a larger included angle at its trailing edge compared to the second flute, creating asymmetric cutting forces that stabilize the bit on the axis during plunge cutting in plastic materials and prevent aggressive biting and off-axis forces.

Inventive Principle:

Principle #4Asymmetry

2Adaptability or versatility

If a combination drill and milling bit is used to shape plastic materials, then multiple functions are achieved, but ridges and burrs are formed along drilled holes and milled grooves

Engineering Contradiction:

Improvecombined drill and milling capabilityVSAvoidcleanliness of cut

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The drill bit incorporates relief faces on the outer periphery of the body that are localized to specific regions. These relief faces are positioned to contact the work piece at locations adjacent to the flutes during milling operations, providing localized support and control that prevents ridge and burr formation while maintaining the combined drill-mill functionality.

Inventive Principle:

Principle #3Local quality

3Reliability

If the bit geometry is modified to improve control in soft materials, then stability improves, but the complexity of the bit design increases

Engineering Contradiction:

Improvestability of bit during cuttingVSAvoidcomplexity of flute and face geometry

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The drill bit design segments the flute structure into distinct first and second flutes with different geometries, and divides the relief features into multiple relief faces positioned at different locations. This segmentation allows each element to perform a specific function: the asymmetric flutes provide axial stability while the distributed relief faces provide localized support during milling, achieving improved stability without excessive overall complexity.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS8740512B2‘O’ flute multipurpose bit

Publication Date: 2014.06.03 ROBERT BOSCH TOOL

AI summary

A tool bit providing a combined drill bit and milling bit is disclosed herein. The tool bit in one embodiment includes a working section having a longitudinally extending central axis, an O-flute extending along the working section, and a tooth formed at a tip portion of the working section, the tooth offset from the central axis.