Numerical Controller Synthesis Speed for Rotary Axis Stability
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Solution Overview
Problem
Conventional numerical controllers for multi-axis machining devices often result in high-speed rotary axis movements that are impractical, leading to machining errors, vibrations, and servo alarms due to the lack of consideration for the movement amount of the rotary axis in speed instructions.
Innovation Solution
A numerical controller with a synthesis speed control unit that sets a speed instruction as a synthesis speed for the relative moving distance between the workpiece and the tool center point, along with a tool-direction changing distance due to the relative change in the tool direction, allowing for stable movement of the rotary axis by interpolating positions of linear and rotary axes based on this synthesis speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the path of the tool center point is interpolated on a table coordinate system based on speed instruction, then the tool center point can follow the instructed path, but the rotary axis movement speed becomes excessively high leading to machining errors and vibrations
Solution Approach 1:
The patent transforms the coordinate system from a rotating table coordinate system to a fixed machine coordinate system. This parameter change in the reference frame eliminates the excessive speed calculations that occur when interpolating on a rotating coordinate system, thereby preventing machining errors and vibrations while maintaining tool center point path accuracy
Solution Approach 2:
The patent introduces a coordinate transformation mechanism that acts as an intermediary between the tool center point path instruction and the actual axis movements. By transforming coordinates from the rotating table system to the fixed machine system before interpolation, it mediates the conflict between path accuracy and machining stability
2Extent of automation
If the rotary axis is interpolated together with the tool center point path, then both movements are synchronized, but the rotary axis speed becomes impractically high causing servo alarms
Solution Approach 1:
The patent changes the parameter of the coordinate system from rotating to fixed, which fundamentally alters the speed calculations for the rotary axis. This parameter change reduces the rotary axis speed to practical levels while maintaining synchronization with the tool center point path through the coordinate transformation mechanism
3Manufacturing precision
If speed instruction is given without considering rotary axis movement amount, then the tool center point path can be followed, but the rotary axis cannot move stably leading to servo alarms
Solution Approach 1:
The patent changes the coordinate system parameter from rotating to fixed, which automatically adjusts the speed distribution between linear and rotary axes. This parameter change enables both accurate tool center point path following and stable rotary axis movement without requiring complex speed adjustment mechanisms
Data Source
AI summary
When a numerical controller executes a tool-center-point control in which a path of a tool center point with respect to a workpiece is instructed, and the workpiece is machined along the instructed path based on a speed instruction, the numerical controller sets the speed instruction so that the speed instruction is a synthesis speed with respect to a synthesis distance of a relative moving distance between the workpiece and a tool center point and a tool-direction changing distance due to a relative change in a tool direction with respect to the workpiece by a rotary axis. The numerical controller interpolates a position of a linear axis and a position of a rotary axis by the tool-center-point control according to the synthesis speed and drives the linear axis and the rotary axis to the position of the linear axis and the position of the rotary axis created by the interpolation.