Rotary Table Machining with Real-Time Workpiece Pose Compensation
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Solution Overview
Problem
Existing machining systems face challenges in accurately machining workpieces installed on rotary tables, particularly in maintaining precise positioning and orientation due to eccentricity or imperfect orientation of the workpiece relative to the rotational axis, which can lead to dimensional tolerance failures in high-precision machining operations.
Innovation Solution
A machining system that includes a machining assembly, a rotary table, a dimensional measurement assembly, and a controller. The system uses dimensional measurement sensors to identify the position and orientation of points on the workpiece, calculates updated positions and orientations after rotation, and controls the machining assembly to machine the workpiece accurately based on these updates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the workpiece is installed on the rotary table for machining, then the productivity is improved by enabling multi-position machining, but the manufacturing precision deteriorates due to eccentricity or imperfect orientation of the workpiece relative to the rotational axis
Solution Approach 1:
The system performs preliminary measurement of the workpiece position and orientation before machining operations. The measurement assembly captures the actual location and orientation of the workpiece on the rotary table, and this information is used to pre-calculate compensation values that are stored for subsequent machining operations, ensuring precision is maintained across multiple positions.
Solution Approach 2:
The system implements a feedback mechanism where the actual position and orientation of the workpiece are measured and fed back to the control system. This feedback information is used to update the machining parameters and compensate for any deviations, ensuring that dimensional tolerance is maintained even when the workpiece has eccentricity or imperfect orientation on the rotary table.
2Manufacturing precision
If the workpiece position and orientation are updated in real-time during rotation, then the manufacturing precision is improved, but the device complexity increases due to additional sensors and calculation requirements
Solution Approach 1:
The measurement assembly is designed to perform multiple functions: it measures both the position and orientation of the workpiece, and this single assembly serves for all measurement requirements during the machining process. The control system also handles multiple tasks including real-time calculation of updated position and orientation, storage of compensation values, and coordination of the rotary table and machining assembly, reducing the need for separate dedicated components.
Solution Approach 2:
The system uses the workpiece itself as part of the measurement process by measuring features on the workpiece surface to determine its position and orientation. The workpiece provides its own reference features for measurement, eliminating the need for separate reference artifacts or complex external measurement systems.
3Manufacturing precision
If dimensional measurement sensors are used to identify workpiece position and orientation, then the manufacturing precision is improved, but the measurement precision requirements increase which may be difficult to achieve
Solution Approach 1:
The system introduces an intermediary calculation process that transforms the raw measurement data into updated position and orientation values. The control system acts as an intermediary that receives measurements from the sensors, processes this information through mathematical calculations to determine the actual workpiece position and orientation, and then uses these calculated values to control the machining assembly, effectively bridging the gap between measurement and machining precision.
Solution Approach 2:
The system changes the measurement parameters by measuring multiple features on the workpiece surface and using these measurements to calculate the position and orientation parameters. By measuring at multiple locations and using mathematical relationships, the system can determine precise position and orientation even when individual measurements have limited precision, effectively transforming the measurement data into accurate positional information.
Data Source
AI summary
A machining system includes a machining assembly, a rotary table, a dimensional measurement assembly, and a controller. The controller is configured to control the dimensional measurement assembly to identify first position and a first orientation for a point on a surface of a workpiece with at least one dimensional measurement sensor, determine a first machine-workpiece vector and a first rotation-workpiece vector for the point, control the rotary table to rotate the workpiece about a rotational axis by a rotation angle, calculate a second position and a second orientation for the point subsequent to rotating the workpiece, update a workpiece position and a workpiece orientation in a part coordinate system (PCS) for the workpiece using the second position and the second orientation, and control the machining assembly to machine the workpiece using the updated workpiece position and the updated workpiece orientation.