Laser Joining Thin Bars via Upper Part Inversion

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Solution Overview

Problem

Existing joining techniques struggle to effectively join thin or narrow workpieces with wider parts in a concealed manner, especially when access to the joining point is limited or not desired, and fail to ensure high operational reliability and quality.

Innovation Solution

A method and device utilizing a high-energy beam, such as a laser or electron beam, guided by a manipulator with integrated measurement and optical detection systems, allowing precise measurement and alignment of the joining path, focal spot adjustment, and beam deflection for optimal joint quality, even when the thin part is not visible during the process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If conventional joining techniques are used for thin or narrow workpieces with wider parts, then access to the joining point is required, but this limits the applicability to difficult configurations where access is not possible or not desired

Engineering Contradiction:
Improveapplicability to difficult configurationsVSAvoidaccess to joining point
Core Design Contradiction:
Adaptability or versatilityVSEase of operation

Solution Approach 1:

The patent inverts the conventional joining approach by performing the joining operation from the wider upper part rather than from the narrow lower part. The high-energy beam is directed onto the back side of the upper part, allowing the beam to pass through and join the parts from the opposite side, thereby eliminating the need for direct access to the narrow lower part's joining area.

Inventive Principle:
Principle #13The other way round (Inversion)

Solution Approach 2:

The patent transitions from a two-dimensional surface joining approach to a three-dimensional volumetric approach by using a high-energy beam that can penetrate through the workpiece. This allows joining to occur through the thickness dimension, enabling concealed joining where the beam passes through the upper part to reach the joint area on the lower part.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Reliability

If measurement and alignment are performed before beam joining, then the joining path can be reliably adhered to, but the thin or narrow lower part is no longer visible during joining and cannot be searched for or checked online

Engineering Contradiction:
Improvejoining path accuracyVSAvoidvisibility of narrow part during joining
Core Design Contradiction:
ReliabilityVSDifficulty of detecting and measuring

Solution Approach 1:

The patent performs measurement and alignment of the narrow lower part before the actual beam joining operation. The measuring device records the position, course, and dimensions of the lower part to establish the joining path. This preliminary measurement ensures that subsequent joining can proceed reliably along the predetermined path even though the lower part becomes invisible during the beam joining process.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent creates a digital representation or model of the narrow lower part through measurement before joining. This copied information about the lower part's geometry and position is stored and used to guide the beam along the correct joining path, replacing the need for direct visual detection during the joining operation itself.

Inventive Principle:
Principle #26Copying

3Manufacturing precision

If the focus diameter is adjusted to the wall thickness of the bar, then the quality of the joint is optimized, but additional measurement and adjustment steps are required

Engineering Contradiction:
Improvejoint qualityVSAvoidfocus adjustment mechanism
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent implements a feedback mechanism where the measuring device determines the wall thickness of the narrow lower part, and this measurement information is used to automatically adjust the focus diameter of the high-energy beam. The system closes the control loop by using the measured geometric parameters to optimize the beam parameters, ensuring optimal joint quality without manual intervention.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent dynamically changes the parameters of the high-energy beam, specifically the focus diameter, based on the measured wall thickness of the workpiece. By adapting the beam parameters to match the workpiece geometry, the system optimizes the energy distribution and melting characteristics to achieve high-quality joints for different wall thicknesses.

Inventive Principle:
Principle #35Parameter changes

4Object-affected harmful factors

If concealed joining is performed from the wider workpiece part, then the thin or narrow lower part is protected, but the connection cross-section must be kept very small

Engineering Contradiction:
Improveprotection of thin partVSAvoidconnection cross-section size
Core Design Contradiction:
Object-affected harmful factorsVSQuantity of substance

Solution Approach 1:

The patent applies local quality by concentrating the beam energy into a very small focal spot area that matches the narrow width of the lower part. The beam diameter is optimized to be slightly smaller than the web width, creating a localized connection zone that provides sufficient strength while minimizing the affected area and protecting the surrounding thin structure.

Inventive Principle:
Principle #3Local quality

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

Enables reliable and high-quality joining of difficult configurations with improved measurement accuracy, operational reliability, and quick processing, protecting the thin part from the upper workpiece while maintaining small connection cross-sections, suitable for various joining methods and coatings.

Implementation Method 1

A method and device for joining workpieces with at least one high-energy beam, in particular a laser beam

Methodology Applied
Scientific EffectLaser beam welding: Laser Beam Welding

Implementation Method 2

The beam is directed onto the lower part along a stored joining path

Methodology Applied
Scientific EffectMelting: Melting

Data Source

PatentEP2242623B1Method and device for joining
Publication Date: 2015.08.26 KUKA SYSTEMS GMBH
  • EP2242623B1 patent drawingFigure 1
  • EP2242623B1 patent drawingFigure 2~3
  • EP2242623B1 patent drawingFigure 4~5

AI summary

The invention relates to a joining device (1) and a method for joining workpieces (15) having a laser beam (3) guided by a multi-axis manipulator (6), wherein an upper part (17) of the workpiece (15) is joined to at least one bar-like base (16). The base (16) is first measured by means of a measuring device (9) carried by the manipulator (6), and the joint path (13) to be traced by the laser beam (3) is laid out according to the measurement result and saved. Subsequently, the upper part (17) is placed onto the base (16) and then joined thereto, wherein the laser beam (3) is guided along the stored joint path (13) and aligned on the back side (19) of the upper part (17).