Scraper Force-Position Control for Catch Detection in Machining

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Solution Overview

Problem

Conventional machining devices rely solely on reaction force feedback, leading to excessive scraping when the scraper tool catches on convex portions, resulting in decreased productivity due to the inability to detect such occurrences.

Innovation Solution

A machining device equipped with both position detection and force sensing units, which acquire and correlate displacement and machining force data to control the scraper's operation, ensuring accurate scraping by matching the force and displacement relationship with a predetermined normal correlation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If only reaction force feedback is used for controlling the scraper tool, then the control system remains simple, but the machining accuracy deteriorates due to inability to detect scraper catch

Engineering Contradiction:
Improvecontrol system complexityVSAvoidmachining accuracy
Core Design Contradiction:
Device complexityVSManufacturing precision

Solution Approach 1:

The patent combines position detection (via camera) and force detection (via force sensor) systems into a unified control framework. The control unit integrates both detection signals to comprehensively monitor scraper tool status, enabling accurate detection of catch conditions through the combination of positional stagnation and force spike indicators rather than relying on force feedback alone.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent implements dual feedback mechanisms: position feedback from the camera tracking scraper location and force feedback from the force sensor measuring reaction forces. The control unit processes both feedback streams simultaneously, using position feedback to detect stagnation and force feedback to detect abnormal force spikes, thereby achieving precise catch detection and preventing excessive scraping.

Inventive Principle:
Principle #23Feedback

2Productivity

If the scraper tool catches on convex portions and continues machining, then the control system operates continuously, but productivity decreases due to excessive scraping requiring rework

Engineering Contradiction:
Improvemachining efficiencyVSAvoidprocess stability
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The control unit continuously monitors both position and force feedback during machining operations. When catch conditions are detected through the dual-parameter monitoring system (position stagnation combined with force spike), the control unit immediately terminates the machining process, preventing excessive scraping and eliminating the need for rework, thereby maintaining both productivity and process stability.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The system performs preliminary detection of catch conditions by continuously tracking scraper position and force parameters before excessive scraping occurs. The control unit identifies catch situations early through the combination of position stagnation and force spike indicators, allowing for timely process termination and preventing the development of problematic machining conditions that would reduce productivity.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP4005716B1Machining device, control device used thereby, and machining device control method
Publication Date: 2024.05.08 CITIZEN WATCH CO LTD
  • EP4005716B1 patent drawingFigure 1
  • EP4005716B1 patent drawingFigure 2A~2C
  • EP4005716B1 patent drawingFigure 3

AI summary

A machining device (1, 100) for scraping a workpiece (2) is provided. The machining device (1, 100) includes: a drive unit (10, 103) for driving a scraper (3); a first detection unit (20) for detecting the position of the scraper (3); a second detection unit (30) for detecting the machining force of the scraper (3) with respect to the workpiece (2); a first acquisition unit (60a) for acquiring information relating to displacement of the scraper (3); a second acquisition unit (60b) for acquiring information relating to the machining force of the scraper (3); and a control unit (60c) for driving the drive unit (10, 103) based on the information relating to the displacement of the scraper (3) by the first acquisition unit (60a) and the information relating to the machining force of the scraper (3) acquired by the second acquisition unit (60b), so the displacement and the machining force of the scraper (3) satisfy a prescribed relationship. A control device (60) and a control method for the machining device (1, 100) are also provided.