Abrasive Coated Bit for Hard Brittle Material Cutting

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Solution Overview

Problem

Existing rotary tool accessories are ineffective for cutting hard and brittle materials like granite or glass due to their inability to efficiently penetrate and make clean cuts, as they are designed for softer, ductile materials.

Innovation Solution

A rotary tool bit with a steel shaft made of HRC 50-55 hardness steel, coated with a bonding material embedding diamond abrasive particles (20-120 grit) that protrude 30-55% from the surface, allowing for controlled binding strength and abrasive coverage, enabling efficient cutting of hard, brittle materials.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional cutting bits with helical flutes are used, then they work well for soft ductile materials, but they are ineffective for hard brittle materials like granite or glass

Engineering Contradiction:
Improvecutting effectivenessVSAvoidmaterial type compatibility
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent changes the fundamental cutting parameters by transitioning from a helical flute geometry to a spherical tip with radial abrasive particles. This parameter change enables the cutting bit to effectively process hard brittle materials by creating a grinding action rather than a shearing action, thus resolving the incompatibility with materials like granite and glass.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The cutting bit employs a composite structure combining a steel shaft with a spherical tip coated with bonding material and embedded abrasive particles. This composite design integrates the strength of steel with the cutting capability of abrasives, enabling effective cutting of hard brittle materials that conventional single-material bits cannot handle.

Inventive Principle:
Principle #40Composite materials

2Strength

If abrasive particles are embedded too deeply in bonding material, then binding strength is improved, but abrasive exposure is reduced leading to poor cutting performance

Engineering Contradiction:
Improvebinding strengthVSAvoidabrasive exposure control
Core Design Contradiction:
StrengthVSManufacturing precision

Solution Approach 1:

The patent optimizes the embedding depth parameter of abrasive particles within the bonding material. By controlling particles to protrude 30-55% from the surface, the design achieves an optimal balance where sufficient binding strength is maintained while adequate abrasive exposure ensures effective cutting performance on hard materials.

Inventive Principle:
Principle #35Parameter changes

3Productivity

If cutting edges are designed for shearing soft materials, then they work well for ductile materials, but they cannot efficiently penetrate hard brittle materials

Engineering Contradiction:
Improvecutting efficiencyVSAvoidpenetration capability
Core Design Contradiction:
ProductivityVSForce

Solution Approach 1:

The patent replaces conventional sharp cutting edges with a spherical tip geometry. This curved surface distributes the penetration force across multiple abrasive particles, enabling efficient penetration of hard brittle materials through a grinding mechanism rather than concentrated shearing, thus improving both productivity and penetration capability.

Inventive Principle:
Principle #14Spheroidality (Curvature)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The bit effectively cuts hard, brittle materials by maintaining high abrasive exposure and controlled binding, reducing heat generation and facilitating debris removal and cooling, thus enabling precise bore creation and linear cuts with reduced material hardness issues.

Implementation Method 1

A rotary tool bit with a steel shaft made of HRC 50-55 hardness steel, coated with a bonding material embedding diamond abrasive particles (20-120 grit) that protrude 30-55% from the surface

Methodology Applied
Scientific EffectAbrasion: Abrasion

Data Source

PatentEP2072186B1Abrasive coated bit
Publication Date: 2012.05.02 ROBERT BOSCH GMBH
  • EP2072186B1 patent drawingFigure 1~3
  • EP2072186B1 patent drawingFigure 4~6
  • EP2072186B1 patent drawingFigure 7

AI summary

A rotary tool accessory (104) and method for shaping hard, brittle material is disclosed. In one embodiment a rotary tool accessory (104) for cutting hard, brittle material, includes a shaft (106) for coupling with a rotary tool (100), a work portion (108) extending outwardly from the longitudinal axis of the shaft (106), the work portion including a cylindrical portion (110) and a spherical portion (112), a nickel based bonding material (114) affixed to the work portion (108), and a plurality of abrasive particles (120) extending outwardly of the bonding material (114).