CNC Feedrate Control for Faster Machining Without Precision Loss
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Solution Overview
Problem
Existing numerical control devices for machine tools face challenges in shortening machining time without compromising machining precision, as adjusting deceleration parameters can lead to errors in tool movement and reduced accuracy.
Innovation Solution
A numerical control device that includes a limit setting storage unit, limit velocity calculation unit, feedrate determination unit, and adjustment effect calculation unit, which calculates and adjusts movement velocities and times based on parameters like acceleration and jerk to optimize machining efficiency and precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If deceleration control is performed to maintain machining precision, then manufacturing precision is improved, but machining time increases
Solution Approach 1:
The system dynamically changes the limit values of movement parameters (acceleration, jerk, instantaneous velocity variation) based on the machining program and movement path characteristics. By adjusting these parameters according to the specific machining conditions and path curvature, the system optimizes the balance between machining precision and machining time, allowing faster movement where precision requirements are lower while maintaining precision where required.
Solution Approach 2:
The system performs dynamic feedrate adjustment by calculating appropriate feedrates at each position along the movement path based on real-time evaluation of path curvature, acceleration limits, and jerk limits. This dynamic control allows the tool to move at optimal speeds varying along the path, rather than using a constant conservative feedrate, thereby reducing overall machining time while maintaining precision at critical positions.
2Productivity
If the limit value of deceleration parameters is increased to shorten machining time, then productivity is improved, but manufacturing precision deteriorates
Solution Approach 1:
The system changes the limit values of movement parameters dynamically based on the machining context. Instead of using fixed conservative limit values, the system calculates appropriate limit values for acceleration, jerk, and instantaneous velocity variation at each position along the movement path, allowing higher values where they don't compromise precision and lower values where precision is critical.
Solution Approach 2:
The system performs preliminary calculation of appropriate feedrates and parameter limits before actual machining by analyzing the entire movement path and machining program. This advance planning allows the system to identify positions where higher parameter values can be used safely and positions where precision requires stricter limits, optimizing the overall machining time while guaranteeing precision requirements are met.
3Manufacturing precision
If multiple parameters are controlled for accurate tool movement, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The system merges the control of multiple parameters (acceleration, jerk, instantaneous velocity variation) into a unified feedrate adjustment mechanism. By calculating the appropriate feedrate based on all these parameters simultaneously and using this single feedrate value to control the tool movement, the system achieves accurate tool movement control without the complexity of managing multiple independent control systems.
Data Source
AI summary
A numerical control device according to the present invention is for a machine tool which causes a tool to move along a movement path decided according to a machining program, and includes: a limit setting storage unit in which limit values of a plurality of parameter related to movement of the tool are set; a limit velocity calculation unit which calculates a plurality of limit velocities which are movement velocities of the tool, which respectively correspond to the limit values of the plurality of parameters at each position of the movement path; a feedrate determination unit which defines a minimum value among an ideal velocity of the tool and the plurality of limit velocities at each position on the movement path as a feedrate of the tool at each position on the movement path; and an adjustment effect calculation unit which calculates variation in movement time required in order to cause the tool to move an entirety of the movement path at the feedrate, in a case of changing the limit value of the parameter.