Undercut Anchor Welded Cutting Elements for Stable Expansion

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Solution Overview

Problem

Existing undercut anchors lack stable cutting elements that effectively create and engage with the undercut in the anchor hole, leading to potential dislodging.

Innovation Solution

The undercut anchor features an expansion sleeve with outward-pivoting expansion elements and welded cutting elements, formed by weld strips applied in specific configurations to enhance stability and cutting efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If cutting elements are attached to expansion elements by weld overlay, then the anchor can create undercut in anchor hole, but the heat from welding may reduce strength of expansion elements

Engineering Contradiction:
Improvecutting element formationVSAvoidexpansion element strength
Core Design Contradiction:
Ease of manufactureVSStrength

Solution Approach 1:

The patent applies weld overlay only at specific locations on the expansion elements - specifically at the front end and at intermediate positions along the length - rather than uniformly across the entire surface. This localized welding approach enables cutting element formation while minimizing heat-affected zones and preserving the strength of the expansion elements in non-welded areas.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent uses multiple passes of weld overlay, applying weld material in successive layers to build up the cutting elements to the required thickness and geometry. This partial action approach allows controlled heat input in multiple stages rather than a single excessive heating event, maintaining expansion element strength while achieving the necessary cutting element dimensions.

Inventive Principle:
Principle #16Partial or excessive action

2Reliability

If expansion elements are pivoted outwards to expand into undercut, then positive locking is achieved, but cutting elements must remain stable during rotation and expansion

Engineering Contradiction:
Improveanchoring reliabilityVSAvoidcutting element stability
Core Design Contradiction:
ReliabilityVSStability of the object's composition

Solution Approach 1:

The cutting elements are pre-formed and securely attached to the expansion elements before the anchor is installed in the hole. The weld overlay process creates a strong bond between the cutting element material and the expansion element substrate, ensuring the cutting elements remain stable and properly positioned during the subsequent rotation and expansion operations that create the undercut and achieve positive locking.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent creates a composite structure where cutting element material (applied via weld overlay) is bonded to the expansion element substrate. This composite construction combines the structural integrity and pivoting capability of the expansion element with the cutting functionality of the overlay material, ensuring both stability during expansion and effective undercut creation.

Inventive Principle:
Principle #40Composite materials

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 solution provides a self-tapping anchor with enhanced stability and cutting performance, ensuring secure anchoring through positive locking and reduced heat-induced strength loss.

Implementation Method 1

A cutting element is attached to an outer side of at least one expanding element by weld overlay

Methodology Applied
Scientific EffectWelding: Welding

Implementation Method 2

the at least one expansion element comes into contact with the expansion body and is pivoted outwards away from the longitudinal axis of the undercut anchor by the expansion body

Methodology Applied
Scientific EffectMechanical Force: Mechanical Force

Data Source

PatentEP4522874B1Self-cutting undercut anchor
Publication Date: 2026.02.18 FISCHERWERKE ARTUR FISCHER GMBH & CO KG
  • EP4522874B1 patent drawingFigure 1
  • EP4522874B1 patent drawingFigure 2~3

AI summary

The invention relates to cutting elements (16) of a self-cutting undercut anchor (1) by laser deposition welding of a plurality of welding strips (17, 18) onto expansion elements (14) of an expansion sleeve (9) of the undercut anchor (1).