Machine Tool Changer Control Using Tool Image-Based Load Detection

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Solution Overview

Problem

Existing tool changing methods are inefficient in reducing the time required for tool changes due to suboptimal rotation of the tool magazine and biased load calculations, especially when dealing with tools of varying weights.

Innovation Solution

A tool changing method that utilizes an image capturing device to determine operation parameters for the changing arm, allowing for precise measurement and calculation of tool mass and center of gravity, thereby optimizing the rotational speed and reducing the time needed for tool changes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the rotational speed of the tool magazine is optimized based on centrifugal forces, then the operation of the tool magazine is optimized, but the time required to change tools is not effectively reduced because the rotation time is small compared to the tool changing time

Engineering Contradiction:
Improvetool magazine operation efficiencyVSAvoidtotal tool change time
Core Design Contradiction:
ProductivityVSLoss of time

Solution Approach 1:

The patent extracts the tool magazine rotation operation from the critical path of tool changing. By pre-rotating the tool magazine independently before the tool changing arm operates, the rotation time is separated from the tool changing time, making it non-critical and allowing parallel execution of operations.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The tool magazine is rotated to the required position in advance before the tool changing arm begins its operation. This preliminary action ensures that when the tool changing arm needs to access a specific tool, the magazine is already positioned correctly, eliminating waiting time and enabling parallel execution of magazine rotation and tool changing operations.

Inventive Principle:
Principle #10Preliminary action

2Reliability

If a higher safety factor speed is used to account for large weight differences between tools, then safety is improved, but the rotational speed of the tool changing arm cannot be sufficiently increased

Engineering Contradiction:
Improvesafety factorVSAvoidtool changing arm rotational speed
Core Design Contradiction:
ReliabilityVSSpeed

Solution Approach 1:

The patent implements feedback control by measuring the actual weight of each tool and using this information to dynamically adjust the tool changing arm's rotational speed. The control unit receives weight information from the measurement unit and optimizes the rotational speed accordingly, allowing higher speeds when weight differences are small and maintaining safety when weight differences are large.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The rotational speed of the tool changing arm is made dynamic rather than fixed. The speed is adjusted in real-time based on the actual weight difference between tools being exchanged, allowing the system to operate at higher speeds when conditions permit and reducing speed only when necessary for safety, thereby optimizing overall tool changing time.

Inventive Principle:
Principle #15Dynamics

3Device complexity

If the weight of each tool is not accurately obtained due to simultaneous drawing of two tools, then calculation simplicity is maintained, but the rotational speed optimization is insufficient

Engineering Contradiction:
Improveload calculation complexityVSAvoidtool changing speed
Core Design Contradiction:
Device complexityVSProductivity

Solution Approach 1:

The patent segments the tool changing operation into two separate phases: first, one tool is drawn from the magazine and its weight is measured; then the second tool is drawn and its weight is measured. This segmentation allows individual weight measurement for each tool, providing accurate data for rotational speed optimization without requiring complex simultaneous measurement systems.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The weight measurement of tools is performed in advance before the actual tool changing operation. By measuring and storing the weight of each tool beforehand, the system has accurate weight information available when needed, eliminating the need for complex real-time calculations during the tool changing process itself.

Inventive Principle:
Principle #10Preliminary action

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

Significantly reduces the time required for tool changes by accurately determining operation parameters based on captured images, ensuring efficient and safe handling of tools with varying weights.

Implementation Method 1

an image of the tool is captured by an image capturing device

Methodology Applied
Scientific EffectImage capturing: Photography

Data Source

PatentEP3330042B1Tool exchange method and tool exchange device
Publication Date: 2021.03.10 MAKINO MILLING MASCH CO LTD
  • EP3330042B1 patent drawingFigure 1
  • EP3330042B1 patent drawingFigure 2
  • EP3330042B1 patent drawingFigure 3

AI summary

This tool exchange device (40) for a machine tool uses an exchange arm (43) to exchange tools (5) between a processing area (61) and a tool accommodation area (62). In the tool exchange device, an imaging device (24) is used to capture an image of a tool in the tool accommodation area (62), operation parameters for the exchange arm (43) when the exchange arm (43) is used to exchange the tools (5) are determined from the captured image of the tool, and the exchange arm (43) is operated on the basis of the operation parameters to exchange the tools (5).