Saddle-Shaped Cutting Edge for Reinforced Concrete Demolition

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Solution Overview

Problem

Existing flat chisels are not well-suited for demolishing steel-reinforced concrete due to their design, which fails to effectively engage and cut reinforcement steel without slipping, especially as the cutting edge wears.

Innovation Solution

A flat chisel with a saddle-shaped cutting edge oriented crosswise to the longitudinal axis, featuring a first concave curvature between the longitudinal and transverse axes and a second concave curvature parallel to the longitudinal axis, preventing slipping off reinforcement steel and maintaining its shape even at advanced wear stages.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional flat cutting edge is used, then the chisel is simple in design and easy to manufacture, but it slips off reinforcement steel and cannot effectively cut steel-reinforced concrete

Engineering Contradiction:

Improveengagement stability on reinforcement steelVSAvoidcutting edge geometry

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The cutting edge is designed with a saddle shape featuring dual concave curvatures: a first concave curvature in a first plane and a second concave curvature in a second plane. This curved geometry allows the cutting edge to conform to cylindrical reinforcement steel, preventing slippage while maintaining manufacturability through standard forming processes.

Inventive Principle:

Principle #14Spheroidality (Curvature)

2Duration of action of moving object

If a straight cutting edge is used, then the chisel structure is simple, but the cutting edge loses effectiveness quickly due to wear and deformation

Engineering Contradiction:

Improveservice life of cutting edgeVSAvoidcutting edge configuration

Core Design Contradiction:

Duration of action of moving objectVSDevice complexity

Solution Approach 1:

The saddle-shaped cutting edge with its dual concave curvatures maintains structural integrity during wear. The curved geometry distributes stress more evenly and prevents the edge from deforming flat during use, thereby extending service life while the complexity remains limited to the initial forming step.

Inventive Principle:

Principle #14Spheroidality (Curvature)

3Adaptability or versatility

If a convex-chevron shaped cutting edge is used, then the chisel achieves high demolition capacity on general substrates, but it is not well-suited for steel-reinforced concrete demolition

Engineering Contradiction:

Improvesuitability for steel-reinforced concreteVSAvoiddemolition capacity

Core Design Contradiction:

Adaptability or versatilityVSProductivity

Solution Approach 1:

The cutting edge features different curvatures in different planes: a first concave curvature in a first plane and a second concave curvature in a second plane. This localized variation in geometry allows the edge to adapt specifically to cylindrical reinforcement steel while maintaining overall structural integrity for effective demolition work on steel-reinforced concrete.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS11673246B2Flat chisel

Publication Date: 2023.06.13 HILTI AG

AI summary

A flat chisel (1) having a longitudinal axis (7), a shank (2) and a blade-shaped working section (5). The shank (2) has a striking surface (4) perpendicular to the longitudinal axis (7). The working section (5) has a cutting edge (3) that is crosswise to the longitudinal axis (7). The cutting edge (3) is configured so as to be saddle-shaped.