Plasma Pre-Bored Cover Layer Joining for Hard Sheet Assemblies

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Solution Overview

Problem

Conventional methods for connecting two plate-like components via a through hole are limited, particularly when dealing with high-strength or ultra-high-strength materials like 22MnB5, as they result in high wear and contamination during pilot hole machining, and restrict the use of connection methods.

Innovation Solution

A method using a plasma jet to create a pilot hole in the top layer, which is temporarily fixed over the base layer, allowing for precise hole formation without deforming the base layer, and enabling various connection methods such as friction welding, riveting, or screwing by inserting a connecting element through the pilot hole.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If conventional methods (milling, drilling, cutting, punching) are used to create pilot holes in high-strength or ultra-high-strength sheets, then the top layer can be pre-punched, but this results in high wear and contamination of the environment

Engineering Contradiction:
Improvepilot hole productionVSAvoidwear and contamination
Core Design Contradiction:
Ease of manufactureVSObject-generated harmful factors

Solution Approach 1:

The patent replaces conventional mechanical pilot hole creation methods (milling, drilling, cutting, punching) with a plasma jet process. The plasma jet uses ionized gas to melt and eject material, eliminating mechanical contact and thus reducing wear on tools and machinery while minimizing contamination from metal chips and dust that would otherwise be generated by mechanical processes.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the physical state and properties of the processing system by using plasma (ionized gas) instead of mechanical tools. By controlling plasma parameters such as gas composition, power input, and jet velocity, the process can precisely remove material from high-strength sheets without the wear and contamination associated with mechanical methods.

Inventive Principle:
Principle #35Parameter changes

2Adaptability or versatility

If a through hole is made in both layers, then connection can be established, but this limits connection methods to self-tapping screws only

Engineering Contradiction:
Improveconnection method flexibilityVSAvoidbase layer integrity
Core Design Contradiction:
Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The patent applies local quality by creating a pilot hole only in the top layer rather than punching through both layers. This localized pre-punching allows the base layer to remain intact with full material properties, enabling various connection methods (friction welding, riveting, screwing) while the top layer's pilot hole facilitates easy insertion of connecting elements.

Inventive Principle:
Principle #3Local quality

3Ease of manufacture

If the cover layer is harder than the base layer, then the top layer can be pre-punched, but this causes deformation of the assembly

Engineering Contradiction:
Improvepilot hole creationVSAvoidassembly deformation
Core Design Contradiction:
Ease of manufactureVSShape

Solution Approach 1:

The patent replaces mechanical punching methods with a plasma jet process that melts material through thermal energy rather than mechanical force. This substitution eliminates the deformation issues that would arise from mechanical punching of hard top layers, as the plasma process can precisely remove material without applying excessive mechanical stresses that would deform the softer base layer or the overall assembly.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

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

This approach minimizes wear and contamination, allows for connection of hard top layers with softer base layers without deformation, and provides flexibility in hole diameter adjustment, enabling efficient and versatile joining of components with reduced process forces.

Implementation Method 1

the pilot hole in the form of a through hole is made exclusively by a plasma jet in the at least one cover layer

Methodology Applied
Scientific EffectPlasma jet heating: Plasma

Implementation Method 2

the plasma jet is generated by a non-transferred arc, the cover layer being melted by the hot plasma jet

Methodology Applied
Scientific EffectArc heating: Electric Arc

Implementation Method 3

the cover layer being melted by the hot plasma jet and the melted material being displaced by the plasma pressure

Methodology Applied
Scientific EffectPlasma pressure: Pressure Increase

Implementation Method 4

connected to the base layer in a positive and/or material and/or non-positive manner

Methodology Applied
Scientific EffectFriction connection: Friction

Data Source

PatentEP3500391B1Method of connecting at least two component layers, with plasma jet pre-bores in the cover layer, device for joining a workpiece arrangement, and workpiece arrangement
Publication Date: 2021.08.18 EJOT GMBH & CO KG
  • EP3500391B1 patent drawingFigure 1~2
  • EP3500391B1 patent drawingFigure 3~4
  • EP3500391B1 patent drawingFigure 5a~5b

AI summary

The invention relates to a method for connecting at least two component layers (12, 14) by means of a connection element, said connection comprising at least one cover layer (12) and at least one base layer (14), wherein a pre-bore in the form of a through-hole is introduced into the at least one cover layer (12), and the at least one base layer (14) is not pre-bored in the region of said pre-bore, a connection element with a shoulder being connected to the base layer (14) through the pre-bore in the cover layer (12), and said connection element (34) holding the cover layer (12) by means of its shoulder. The pre-bore is made only in the at least one cover layer (12), which is held so as to be at least temporarily secured over the base layer (14), and, once the pre-bore has been made in the cover layer (12), the connection element is guided through the cover layer (12) and connected to the non-pre-bored base layer (14), said pre-bore being formed by a plasma jet (20).