Plug Joining Tool With Path Compensation for Robot Tolerances

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Solution Overview

Problem

Existing plug joining technologies face challenges with inaccuracies in positioning and tolerances, leading to potential damage and reduced safety and quality in the joining process, especially when using position-controlled robots.

Innovation Solution

A plug joining tool equipped with a compensation device that allows for evasive movement of the setting plunger, which can compensate for deviations in the joining path and absorb reaction forces, featuring a counterholder with adjustable counterforce and a detection device for precise process monitoring.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a position-controlled robot is used for plug joining, then automation and productivity are improved, but positioning accuracy and joining quality deteriorate due to tolerances and programming inaccuracies

Engineering Contradiction:
ImproveautomationVSAvoidpositioning accuracy
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The plug holder is designed with axial deflection capability, allowing it to adapt its position within a tolerance range. This parameter change enables the system to accommodate positioning variations from the robot while maintaining proper joining contact, thus resolving the contradiction between automation and positioning accuracy

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The plug holder transitions from a static to a dynamic element by being mounted for axial deflection on the setting ram. This dynamic capability allows real-time adjustment during the joining process to compensate for positioning inaccuracies, enabling both high automation and acceptable joining quality

Inventive Principle:
Principle #15Dynamics

2Stability of the object's composition

If rigid fixing of the plug holder is used, then structural stability is improved, but damage risk increases due to reaction forces from positioning deviations

Engineering Contradiction:
Improvestructural stabilityVSAvoiddamage risk
Core Design Contradiction:
Stability of the object's compositionVSObject-affected harmful factors

Solution Approach 1:

The plug holder's axial deflection capability acts as a pre-designed cushioning mechanism. When positioning deviations occur, the plug holder can deflect axially to absorb reaction forces before they reach critical levels that would cause damage to the tool or workpiece

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The plug holder introduces a flexible element into the otherwise rigid tool structure. This flexibility allows the system to maintain structural stability while accommodating positioning variations, preventing the transmission of harmful reaction forces

Inventive Principle:
Principle #30Flexible shells and thin films

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 enhances the safety and quality of the plug joining process by compensating for inaccuracies and tolerances, reducing the risk of damage and ensuring a secure joining operation, applicable to both passive and active plug joining tools.

Implementation Method 1

The plug holder (22) is mounted for axial deflection relative to the setting ram (21) and can be acted upon by a return element (28)

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP3302899B1Plug joining tool and joining method
Publication Date: 2024.10.16 KUKA SYSTEMS GMBH
  • EP3302899B1 patent drawingFigure 1
  • EP3302899B1 patent drawingFigure 2
  • EP3302899B1 patent drawingFigure 3

AI summary

The invention relates to a robot-guided tool (6) and to a method for automatically joining plugs (5) on vehicle body parts (3). The plug joining tool (6) comprises a frame (12) having a connection (29) for an industrial robot (2), a plug magazine (14), and a setting unit (15) having a plug receptacle (16) and a setting plunger (21) for joining a plug (5) at a joining point (4) of the workpiece (3). The plug joining tool (6) further has a compensation device (8) for compensating deviations of the actual joining path from the target joining path, and optionally, for an evasive movement of the setting plunger (21) during the joining process.