Machine Tool Motion Control for Continuous Eccentric Circular Cutting
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Solution Overview
Problem
In true-circular machining eccentric from a spindle axis, intermittent cutting occurs when the cutting edge separates and contacts the workpiece, leading to tool damage and reduced accuracy, affecting various machine tools including machining centers.
Innovation Solution
A machine tool with a control unit that determines an intermediate center position and eccentric radius for each divided spindle rotation angle, ensuring continuous contact between the cutting edge and workpiece by moving the spindle and tool post in a direction perpendicular to the spindle axis within a predetermined feed speed, thereby avoiding intermittent cutting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If true-circular machining eccentric from spindle axis is performed with conventional methods, then machining of eccentric features is achieved, but intermittent cutting occurs causing tool damage and reduced accuracy
Solution Approach 1:
The machining process is segmented into multiple discrete steps, each handling a specific angular range of the spindle rotation. The control unit divides the rotation into sectors and calculates intermediate center positions for each sector, ensuring continuous cutting engagement within each segment while transitioning smoothly between segments.
Solution Approach 2:
The control unit performs preliminary calculations to determine intermediate center positions and intermediate eccentric radii before executing the machining operation. This advance planning ensures that the cutting edge maintains continuous contact with the workpiece by pre-positioning the tool and spindle at appropriate locations for each angular sector.
2Reliability
If the cutting edge path is kept inside the workpiece to avoid intermittent cutting, then tool damage is prevented, but the machining accuracy and circularity may be compromised
Solution Approach 1:
The system dynamically adjusts the intermediate center position and intermediate eccentric radius for each angular sector based on the spindle rotation angle. This dynamic adaptation allows the cutting path to optimally follow the workpiece contour while maintaining continuous engagement, achieving both tool stability and high circularity accuracy.
Solution Approach 2:
The control unit uses feedback from the spindle rotation angle to continuously determine the appropriate intermediate center position and eccentric radius for each angular position. This closed-loop control ensures that the cutting edge follows the precise circular path required for accurate eccentric machining while maintaining continuous contact with the workpiece.
Data Source
AI summary
A technology capable of improving the accuracy of true-circular machining while avoiding an occurrence of intermittent cutting. A control unit of a machine tool determines an intermediate center position (Pi) in the moving direction for each divided rotation angle (E) smaller than a single rotation of the spindle and an intermediate eccentric radius (ri) around the intermediate center position (Pi) according to an initial position (Po) of the cutting edge in contact with the workpiece in the moving direction, the eccentric center position (Pc), and the eccentric radius (rc) to keep the cutting edge in contact with the workpiece as the moving object moves in the moving direction within a predetermined maximum feed speed (F) until a true-circular machining around the eccentric center position (Pc) is complete on the workpiece.