CNC Machine Calibration for Dental Workpiece Precision

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Solution Overview

Problem

CNC machines used in dental manufacturing face limitations in accuracy due to clearance between moving parts and tolerance issues, leading to misalignment of machine axes, which affects the quality of machined dental workpieces.

Innovation Solution

A calibration method where a test body is used to check calibration parameters such as axis alignment and zero points, with correction values calculated to compensate for deviations, allowing precise machining by accounting for these inaccuracies.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If clearance is provided between moving parts for assembly, then ease of assembly is improved, but axis alignment accuracy deteriorates

Engineering Contradiction:
Improveease of assemblyVSAvoidaxis alignment accuracy
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent applies preliminary action by performing calibration before actual machining operations. A test piece is measured to detect axis alignment deviations, and correction values are calculated in advance. These correction values are then stored and automatically applied during subsequent machining operations, eliminating the need for physical reassembly or adjustment of components.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent changes parameters by transforming physical axis alignment parameters into digital correction values. Instead of physically adjusting the mechanical alignment of axes, the system measures the actual alignment state and represents it through numerical correction factors that are applied during control operations, thereby maintaining both assembly ease and machining precision.

Inventive Principle:
Principle #35Parameter changes

2Ease of manufacture

If tolerance is provided in machine components, then ease of manufacture is improved, but machining accuracy deteriorates

Engineering Contradiction:
Improveease of manufactureVSAvoidmachining accuracy
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent implements feedback by measuring the actual machining results on a test piece and using this measurement information to calculate correction values. This closed-loop feedback mechanism allows the system to detect deviations caused by component tolerances and compensate for them through software-based correction, thereby maintaining high machining accuracy despite the use of standard tolerance-ranged components.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The system transforms the physical dimensional parameters of machine components into corrected digital parameters through measurement and calculation. By representing tolerance-induced deviations as numerical correction values, the system can compensate for these variations without requiring tighter manufacturing tolerances on the physical components themselves.

Inventive Principle:
Principle #35Parameter changes

3Manufacturing precision

If calibration is performed to correct axis misalignment, then machining precision is improved, but operation time increases

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

Solution Approach 1:

The patent applies preliminary action by performing the calibration measurement and correction value calculation once during initial setup or periodic maintenance. The correction values obtained are then stored and automatically applied during all subsequent machining operations without requiring repeated calibration procedures, thereby minimizing the time impact to only the initial calibration phase.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP3255515B1Method for operating a CNC machine
Publication Date: 2020.07.01 STEGER HEINRICH
  • EP3255515B1 patent drawingFigure 1
  • EP3255515B1 patent drawingFigure 2~3
  • EP3255515B1 patent drawingFigure 4a~4b

AI summary

Method for operating a CNC machine (1) for machining a dental workpiece (2), wherein - when the CNC machine (1) is operated in a machining mode (BM) - the dental workpiece (2) clamped in a clamping device (3) is machined by a machining device (4) of the CNC machine (1), wherein - when the CNC machine (1) is operated in a calibration mode (KM) - at least one calibration parameter (K) of the CNC machine (1) is checked using a test piece (5) and at least one correction value (Q) is determined, wherein the CNC machine (1) is operated in machining mode (BM) depending on the at least one correction value (Q).