Robot-Guided Drilling With Workpiece Support for Precision Boreholes

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Solution Overview

Problem

Articulated-arm robots with serial kinematics face challenges in high-precision drilling due to low system rigidity, leading to vibrations and accuracy issues when processing large workpieces with free-form surfaces, limiting processing speed and accuracy.

Innovation Solution

Mechanical support is provided to the articulated-arm robot by establishing a detachable connection between the robot and the workpiece, using a laser tracking system for precise positioning, and elastic or resilient designs to minimize vibrations, allowing for improved processing quality and speed.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If an articulated robot with serial kinematics is used for machining large workpieces, then flexibility and cost-effectiveness are improved, but system stiffness decreases leading to vibrations and low machining accuracy

Engineering Contradiction:
ImproveflexibilityVSAvoidmachining accuracy
Core Design Contradiction:
Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The patent combines the flexibility of articulated robots with the precision of machine tools by integrating the robot into a hybrid machining system. The robot handles positioning and approach movements while a stationary machining center performs the actual high-precision machining operations, thus merging the advantages of both systems.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent introduces an intermediary positioning system that includes laser tracking devices and measurement systems. These intermediaries bridge the gap between the robot's low precision and the workpiece's required high precision by continuously monitoring and compensating for positional deviations during the machining process.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Adaptability or versatility

If an articulated robot with serial kinematics is used for machining, then flexibility and cost-effectiveness are improved, but system stiffness decreases causing vibrations during machining

Engineering Contradiction:
ImproveflexibilityVSAvoidvibrations
Core Design Contradiction:
Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The patent extracts the high-precision machining function from the mobile robot system and assigns it to a stationary machining center. This separation removes the source of vibrations (the robot's flexible structure) from the critical machining operation, allowing the robot to handle only non-critical positioning tasks.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces damping elements and vibration isolation mechanisms as intermediaries between the robot and the machining system. These elements absorb and dissipate vibrations, preventing them from affecting the machining quality while allowing the robot to maintain its flexible positioning capabilities.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Productivity

If a robot-guided drilling tool is positioned rapidly using only robot kinematics, then processing speed is improved, but positioning accuracy decreases

Engineering Contradiction:
Improveprocessing speedVSAvoidpositioning accuracy
Core Design Contradiction:
ProductivityVSMeasurement precision

Solution Approach 1:

The patent performs preliminary high-precision positioning using the robot's rapid movement capabilities, then applies post-positioning corrections using the stationary machining center and measurement systems. This two-stage approach allows rapid initial positioning followed by precision adjustment, combining speed and accuracy.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent implements a closed-loop feedback system where laser tracking devices continuously monitor the robot's position and provide real-time correction data to the control system. This feedback mechanism allows the system to maintain high positioning accuracy despite the robot's inherent positioning limitations, while still benefiting from its rapid movement capabilities.

Inventive Principle:
Principle #23Feedback

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 enhances the stability and accuracy of the drilling process, enabling high-precision borehole creation on large workpieces with complex surfaces by reducing vibrations and maintaining high processing quality and speed.

Implementation Method 1

a laser tracking system for detecting a correct spatial position and orientation of the articulated robot-guided drilling tool relative to the workpiece

Methodology Applied
Scientific EffectLaser tracking: LIDAR

Data Source

PatentEP3302857B1Method and arrangement for introducing boreholes into a surface of a workpiece mounted in a stationary manner using a boring tool attached to an articulated-arm robot
Publication Date: 2021.07.28 FRAUNHOFER GESELLSCHAFT ZUR FORDERUNG DER ANGEWANDTEN FORSCHUNG EV
  • EP3302857B1 patent drawingFigure 1
  • EP3302857B1 patent drawingFigure 2a~2b
  • EP3302857B1 patent drawingFigure 2c

AI summary

The invention relates to a method and an arrangement for introducing boreholes into a surface of a workpiece (W) mounted in a stationary manner using a boring tool which is attached to the end face of an articulated-arm robot (KR) and which can be spatially positioned by said robot. The method has the following method steps: - positioning the articulated-arm robot-guided boring tool at a spatial position which lies opposite a specified machining location on the workpiece surface at a specified distance therefrom, - producing a rigid mechanical connection which supports the end face of the articulated-arm robot (KR) on the workpiece and which can be released from the workpiece surface, and - machining the surface by moving the boring tool towards the machining location and subsequently engaging the boring tool with the workpiece (W) at the machining location on the workpiece surface while the end face of the articulated-arm robot (KR) is connected to the workpiece. The invention is characterized by the combination of the following method steps: the boring tool is moved towards the workpiece (W) by means of an NC advancing unit attached to the end face of the articulated-arm robot (KR), the boring process is monitored on the basis of information obtained using a sensor system which detects the position of the boring tool relative to the workpiece surface and which is attached to the end face of the articulated-arm robot (KR), and the boring process is terminated upon reaching a specified boring depth.