Scraper Motion and Force Control to Prevent Excessive Machining

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Conventional machining devices rely solely on reaction force feedback, leading to excessive local scraping when the scraper tool gets caught on the workpiece, necessitating re-scraping and reducing productivity.

Innovation Solution

A control device that integrates a camera for displacement detection and a force sensor for machining force detection, controlling the scraper's operation to maintain a predetermined relationship between displacement and machining force, adjusting the scraper's height to prevent excessive or insufficient cutting.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

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 catching

Engineering Contradiction:
Improvescraping accuracyVSAvoidcontrol system complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent combines position detection (via camera) and force detection (via force sensor) into a unified control system that processes both signals simultaneously. This merging of detection methods enables comprehensive monitoring of scraper behavior, allowing the system to detect catching conditions by analyzing the relationship between position and force data, thereby improving machining accuracy without requiring entirely separate control systems.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent implements dual feedback loops: one from the force sensor providing reaction force feedback, and another from the camera providing position feedback. By processing both feedback signals together and analyzing their correlation, the system can detect abnormal conditions such as scraper catching more reliably than with force feedback alone, thus improving scraping accuracy while maintaining manageable control complexity through integrated processing.

Inventive Principle:
Principle #23Feedback

2Productivity

If the scraper tool gets caught on the workpiece and machining continues, then the control system operates continuously, but productivity decreases due to excessive local scraping requiring re-work

Engineering Contradiction:
Improvescraping efficiencyVSAvoidsurface flatness
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The patent uses real-time feedback from both the force sensor and camera to monitor scraper behavior during machining. By continuously analyzing the relationship between scraper position and reaction force, the system can detect catching conditions as they occur and immediately stop or adjust the machining process, preventing excessive local scraping that would require re-work and thereby maintaining both productivity and surface quality.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent establishes predetermined relationships between scraper position and reaction force that represent normal machining conditions. By comparing real-time measurements against these pre-established criteria, the system can predict and prevent catching conditions before they cause excessive material removal, allowing corrective action to be taken in advance and maintaining machining efficiency without sacrificing surface quality.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP4371718B1Machining device, control device used thereby, and machining device control method
Publication Date: 2026.03.11 CITIZEN WATCH CO LTD
  • EP4371718B1 patent drawingFigure 1
  • EP4371718B1 patent drawingFigure 2A~2C
  • EP4371718B1 patent drawingFigure 3

AI summary

A control device (60) for a machining device (1, 100) that includes a scraper (3) driven by a drive unit (10, 103), for scraping a workpiece (2), a first detection unit (20) in the form of a camera for detecting the position of the scraper (3), and a second detection unit (30) in the form of a force sensor for detecting the machining force of the scraper (3) with respect to the workpiece (2). The control device (60) comprises: a first acquisition unit (60a) for acquiring information relating to displacement of the scraper (3) with respect to a reference position, based on data input from the first detection unit (20); a second acquisition unit (60b) for acquiring information relating to machining force of the scraper (3) with respect to the workpiece (2), based on data input from the second detection unit (30); and a control unit (60c) that controls the drive unit for controlling the operation of the drive unit (10, 103), based on the information relating to the displacement of the scraper (3) acquired 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 that the displacement and the machining force of the scraper (3) satisfy a predetermined relationship.