Machine Tool Workpiece Positioning by Fluid-Force Sensing
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Solution Overview
Problem
Existing methods for calibrating workpieces with varying dimensions, such as cast workpieces, are complex and require manual intervention for accurate positioning and measurement, which complicates the definition of a zero point on a machine tool.
Innovation Solution
A method utilizing changes in the flow field between a tool and a workpiece due to relative movement, especially rotational components, to detect the distance between them by measuring the resulting force changes, which are then compensated by the machine tool's control system, potentially aided by machine learning for precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If manual calibration with a probe is used to determine workpiece position, then measurement accuracy is improved, but device complexity and operation time increase
Solution Approach 1:
The patent replaces the mechanical probe-based measurement system with a fluid dynamic system. A jet of fluid (liquid or gas) is directed at the workpiece surface, and the force exerted by the fluid jet on the workpiece is measured using a force sensor. This substitution eliminates the need for manual probe operation and complex coordinate system calculations, automatically determining workpiece position through force measurement while maintaining high precision.
Solution Approach 2:
The system enables automatic workpiece positioning through self-service calibration. The control unit automatically processes the force measurement data from the fluid jet interaction, calculates the workpiece position and orientation, and defines the zero point without requiring manual intervention. This self-service approach significantly reduces operation time and simplifies the calibration process.
2Measurement precision
If manual probe calibration is performed to define zero point, then positioning accuracy is improved, but productivity decreases
Solution Approach 1:
The mechanical probe calibration process is replaced with an automated fluid jet-based force measurement system. The fluid jet interacts with the workpiece surface, and the resulting force is measured and processed by a control unit to automatically determine the zero point and workpiece coordinates. This eliminates time-consuming manual operations while maintaining positioning accuracy, thereby improving productivity.
Solution Approach 2:
The system performs preliminary automatic calibration before machining begins. The fluid jet force measurement and zero point definition are completed automatically in advance, preparing the machine tool for immediate machining operations without requiring subsequent manual adjustments or measurements during the machining process.
3Measurement precision
If complex manual calibration procedures are used, then measurement accuracy is improved, but loss of time increases
Solution Approach 1:
The time-consuming manual probe measurement process is replaced with a rapid fluid jet force measurement system. The fluid jet can be quickly directed at different points on the workpiece surface, and the force sensor provides immediate measurements. The control unit rapidly processes this data to determine workpiece coordinates, significantly reducing calibration time while maintaining measurement precision.
Solution Approach 2:
The calibration process continues without interruption through automated fluid jet scanning. The control unit systematically directs the fluid jet across the workpiece surface in a continuous manner, collecting force measurement data without the start-stop manual operations required by probe methods. This continuous action eliminates idle time and accelerates the calibration process.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Simplifies the calibration process by automating the determination of the workpiece's position, reducing manual intervention and enhancing precision through force detection and compensation, thereby improving machining efficiency and reducing rework.
Implementation Method 1
A jet of fluid is directed at a surface of the workpiece WS facing the tool WZ, and a change in the force exerted by the jet of fluid on the surface of the workpiece WS is detected
Data Source
Figure 1a~1b
Figure 2~3
AI summary
The invention relates to a method and a measuring device for determining the position of a workpiece clamped in a machine tool, wherein the machine tool comprises a rotating tool and the workpiece and tool are surrounded by a fluid in which a flow field develops due to the rotation of the tool, wherein the force (Fx, Fy) acting on the tool (WZ) and the torque (MR) are determined by the fluid and the distance between the tool (WZ) and the surface of the workpiece (WS) facing the tool is determined from the change in the force and the torque.