Multi-layer Safe Structure Reducing Wall Thickness

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Solution Overview

Problem

Existing burglar-proof safes with multi-layer structures require wall thicknesses of ≥40mm to achieve high burglary resistance, making them bulky and difficult to integrate into narrow spaces.

Innovation Solution

A multi-layered safe design featuring an outer tray, wear plate, composite reinforcement layer, and reinforcement sheet, where the composite reinforcement layer consists of materials like silicon carbide, silicon nitride, borcarbid, or aluminum oxide, connected through posts to form an overall structure, reducing the wall thickness to ≤30mm while maintaining high burglary resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If wall thickness is increased to ≥40mm, then burglary resistance is improved, but the safe becomes bulky and difficult to integrate into narrow spaces

Engineering Contradiction:
Improveburglary resistanceVSAvoidwall thickness
Core Design Contradiction:
ReliabilityVSVolume of moving object

Solution Approach 1:

The patent applies composite materials by combining multiple layers with different properties: an outer steel plate (3-5mm thick) for structural integrity, a middle layer (5-15mm thick) containing hard particles like carbides or oxides for abrasion and impact resistance, and an inner steel plate (2-5mm thick) for structural support. This multi-layer composite structure achieves CEN III-V burglary resistance ratings while reducing total wall thickness to 20-35mm, resolving the contradiction between security and compactness.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent applies local quality by concentrating hard particles (carbides, oxides) specifically in the middle layer where they are needed most for resisting burglary tools like grinders and drills. The outer and inner steel plates provide structural quality, while the middle layer provides localized hard particle reinforcement. This distributed functional quality allows thin walls to achieve high security without uniform thickness throughout.

Inventive Principle:
Principle #3Local quality

2Volume of moving object

If wall thickness is reduced to ≤30mm, then integration into narrow spaces is improved, but burglary resistance may be compromised

Engineering Contradiction:
Improvewall thicknessVSAvoidburglary resistance
Core Design Contradiction:
Volume of moving objectVSReliability

Solution Approach 1:

The patent uses composite materials to achieve high burglary resistance in thin walls by combining steel plates with a middle layer containing concentrated hard particles. The outer steel plate (3-5mm) provides structural integrity, the middle layer (5-15mm) with carbides/oxides provides tool-resistant hardness, and the inner steel plate (2-5mm) provides structural support. This composite approach achieves CEN III-V ratings at 20-35mm thickness.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent applies parameter changes by modifying the material composition and distribution within the wall structure. Instead of uniform thickness, it varies the concentration and type of hard particles in the middle layer, adjusts plate thicknesses, and selects specific particle materials (carbides, oxides) with varying hardness and size parameters to optimize both security performance and wall thickness.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP3431690B1Intrusion-preventing safe with a multi-layer structure
Publication Date: 2025.05.14 TRI STAR
  • EP3431690B1 patent drawingFigure 1~2

AI summary

This concerns a burglar-resistant safe with a multi-layered construction, including the body. The body consists, in order from the outside in, of the following components: outer sheet, wear plate, composite reinforcement layer, and reinforcement plate. The outer sheet, wear plate, composite reinforcement layer, and reinforcement plate are tightly bonded together. The outer sheet is made of stainless steel or carbon steel with a thickness of 1-5 mm. The wear plate is 10-15 mm thick. The reinforcement plate is made of stainless steel or carbon steel with a thickness of 2-10 mm. The composite reinforcement layer consists of silicon carbide, silicon nitride, boron carbide, or aluminum oxide with a thickness of 5-10 mm.Compared to the current state of the art, this multi-layered safe according to the invention offers strong attack protection and high burglary resistance, and can reduce the wall thickness of high-security safes such as CEN III, CEN IV, and CEN V to 20-30 mm. This allows it to be installed even in confined spaces. Furthermore, this multi-layered composite construction can also be used to reinforce thick-walled safes at specific points.