Workpiece Alignment Using Extracted Nominal Points
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Solution Overview
Problem
Existing methods for aligning workpieces on machine tools are complex and cumbersome, requiring CAD data at the machine tool and relying on external features for alignment, which is not suitable for workpieces with critical internal features or free-form surfaces.
Innovation Solution
A method that uses geometric design data to select nominal measurement points, create command codes for measured data points, and align the workpiece coordinate system with the machine tool coordinate system, allowing for alignment based on internal features and reducing the need for CAD data at the machine tool.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If CAD data is used to determine nominal surface points and align coordinate systems, then alignment accuracy is improved, but the process becomes complex and cumbersome requiring CAD information at the machine tool
Solution Approach 1:
The patent extracts only the essential nominal surface point data from the complete CAD model, separating the critical alignment information from the full geometric design data. This allows alignment to be performed using minimal data points rather than requiring the entire CAD dataset at the machine tool, thereby reducing process complexity while maintaining alignment accuracy.
Solution Approach 2:
The alignment process is segmented into two distinct phases: first, determining nominal surface points from CAD data during the design phase; second, using only these extracted nominal points for alignment at the machine tool. This segmentation allows the complex CAD data processing to be separated from the simpler measurement and alignment operations, reducing the computational burden at the machine tool.
2Ease of operation
If external features are used for workpiece alignment, then the alignment process is simplified, but alignment accuracy deteriorates when workpieces have free-form surfaces or lack suitable external features
Solution Approach 1:
The patent makes the alignment method universal by enabling it to work with any workpiece type, whether having external features, internal features, or free-form surfaces. By using nominal surface points that can be selected from any location on the workpiece (internal or external), the method eliminates the limitation of requiring specific external alignment features while maintaining ease of operation.
Solution Approach 2:
The patent creates a simplified representation (copy) of the workpiece geometry in the form of nominal surface points, which captures the essential alignment information without requiring the complete CAD model or physical external features. This digital copy of critical surface locations enables accurate alignment regardless of the workpiece's physical characteristics.
3Manufacturing precision
If all CAD data is processed and fitted at the machine tool, then comprehensive alignment is achieved, but software requirements and processing time increase
Solution Approach 1:
The patent performs the complex data processing and nominal point extraction in advance during the CAD design phase, before the workpiece reaches the machine tool. This preliminary action prepares the alignment data beforehand, so that only simple measurement and comparison operations are needed at the machine tool, significantly reducing processing time while maintaining comprehensive alignment capability.
Solution Approach 2:
The patent extracts only the essential nominal surface point information from the complete CAD data, separating the critical alignment parameters from the full geometric model. This extraction reduces the data volume that needs to be processed at the machine tool from millions of CAD surface points to a manageable set of nominal measurement points, thereby reducing software requirements and processing time.
Data Source
AI summary
Apparatus and method for fitting a workpiece to geometric design data of a workpiece. Nominal data points are selected from the geometric design data. Command codes are created to generate measured data points. The measurement data points have associated nominal measurement points which are used to fit the workpiece to the geometric design data. The apparatus and method may also be used to determine whether a workpiece is within tolerance and for process control.