Workpiece Support Force Control for Thin-Wall Machining

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Solution Overview

Problem

Machining low-rigidity workpieces such as thin plates or thin-wall cylinders often results in cutting errors due to vibration and deformation caused by machining reaction forces, leading to reduced machining precision and efficiency.

Innovation Solution

A machining assistance system featuring an articulated arm robot and a workpiece supporting force control device that generates and controls a supporting force to counteract machining reaction forces, ensuring the force matches the reaction force, thereby preventing deformation and maintaining precision while avoiding reduced production efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If cutting conditions are reduced (amount of cutting, feed speed) to prevent vibration and deformation, then machining precision is improved, but production efficiency deteriorates

Engineering Contradiction:
Improvemachining precisionVSAvoidproduction efficiency
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The invention applies counterweight principle by generating a workpiece supporting force that opposes the machining reaction force. The supporting force generating unit creates a force approximately equal and opposite to the machining reaction force, thereby preventing workpiece deformation and vibration without requiring reduction of cutting conditions. This resolves the contradiction by maintaining both high machining precision and production efficiency.

Inventive Principle:
Principle #8Anti-weight (Counterweight)

Solution Approach 2:

The invention implements preliminary anti-action by preemptively applying a supporting force to counteract the machining reaction force before it causes deformation. The control device generates supporting force based on detected machining reaction force, creating an opposing action that prevents the harmful effect of vibration and deformation, thus allowing normal cutting conditions to be maintained.

Inventive Principle:
Principle #9Preliminary anti-action

2Manufacturing precision

If cutting-to-zero (cutting the same portion twice) is adopted to improve machining precision, then manufacturing precision is improved, but loss of time increases

Engineering Contradiction:
Improvemachining precisionVSAvoidmachining time
Core Design Contradiction:
Manufacturing precisionVSLoss of time

Solution Approach 1:

By applying the counterweight principle through the supporting force generating unit, the invention prevents workpiece deformation during a single pass of machining. This eliminates the need for cutting-to-zero operations, as the workpiece remains stable throughout the machining process, thereby achieving high precision without additional machining time.

Inventive Principle:
Principle #8Anti-weight (Counterweight)

3Manufacturing precision

If a rigid support is used to prevent workpiece deformation, then machining precision is improved, but device complexity increases

Engineering Contradiction:
Improvemachining precisionVSAvoidsupport system complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The invention applies dynamics principle by using a supporting force generating unit that can dynamically adjust its output force in real-time based on the machining reaction force. Unlike fixed rigid supports, this dynamic system adapts to varying machining conditions, providing optimal support throughout the machining process while maintaining simpler overall system architecture.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The invention implements feedback control by detecting the machining reaction force and using this information to control the supporting force generating unit. The control device continuously monitors the machining reaction force and adjusts the supporting force accordingly, creating a closed-loop system that maintains machining precision without requiring complex rigid support structures.

Inventive Principle:
Principle #23Feedback

Data Source

PatentEP3090832B1Low-rigidity workpiece machining assistance system
Publication Date: 2020.09.23 KAWASAKI JUKOGYO KK
  • EP3090832B1 patent drawingFigure 1
  • EP3090832B1 patent drawingFigure 2
  • EP3090832B1 patent drawingFigure 3A~3B

AI summary

A machining assistance system (1) for assisting a machining apparatus (2) includes: a workpiece supporting force generating unit (6), which generates workpiece supporting force against machining reaction force that is exerted on a machining portion of a workpiece W by a working tool (4a); a supporting device (7), which moves the supporting force generating unit (6) while supporting the supporting force generating unit (6); and a workpiece supporting force control device (8), which controls operation of the workpiece supporting force generating unit (6) and operation of the supporting device (7) based on machining reaction force related data related to the machining reaction force and machining position related data related to a machining position of the working tool (4a), such that the workpiece supporting force generating unit (6) exerts the workpiece supporting force on the workpiece W against the machining reaction force.