NC Oscillation Cutting Control for Cutting Speed Limits
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Solution Overview
Problem
In oscillation cutting processes, the cutting speed often exceeds safe limits, leading to issues like surface roughness, excessive load on machine tools, and abnormal wear due to chattering vibrations, which existing technologies have not adequately addressed.
Innovation Solution
A numerical control device and method that calculate and adjust the spindle speed and oscillation frequency to prevent excessive cutting speed by setting an upper limit for the oscillation frequency, ensuring the cutting speed remains within safe parameters through a reference speed calculation unit, oscillation command calculation unit, and adjustment unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If oscillation cutting is performed with high oscillation frequency to improve chip breaking, then chip length control is improved, but cutting speed becomes excessive causing surface roughness and chattering vibration
Solution Approach 1:
The system dynamically adjusts the oscillation frequency based on real-time calculation of cutting speed. The control device continuously monitors the relationship between oscillation frequency and cutting speed, modifying the oscillation parameters adaptively to maintain optimal cutting conditions without exceeding speed limits that cause chattering vibration.
Solution Approach 2:
The invention changes the oscillation frequency parameter within a controlled range to achieve chip breaking while preventing excessive cutting speed. By carefully adjusting this parameter and setting upper limits, the system optimizes chip length control without inducing surface roughness or vibration issues.
2Object-generated harmful factors
If oscillation frequency is increased to reduce chip coiling around cutting tool, then chip evacuation is improved, but excessive load and fatigue occur on drive mechanism
Solution Approach 1:
The control device implements feedback control by calculating cutting speed based on oscillation frequency and comparing it against safe operating limits. When the calculated cutting speed approaches dangerous levels, the system automatically adjusts the oscillation frequency downward, preventing excessive load on the drive mechanism while still achieving effective chip breaking.
3Stability of the object's composition
If oscillation frequency is suppressed to prevent excessive cutting speed, then cutting stability is improved, but chip breaking capability is reduced
Solution Approach 1:
The system applies partial oscillation frequency suppression by setting an upper limit rather than completely eliminating oscillation. This partial action maintains enough oscillation frequency to achieve chip breaking while suppressing excessive frequencies that would cause instability, finding an optimal balance between the two requirements.
Data Source
AI summary
A numerical control device according to an aspect of the present disclosure includes: a reference speed calculation unit configured to calculate a spindle speed which is a rotation number of the spindle in accordance with a machining program, and a feed speed which is a movement speed of the feed axis in accordance with the machining program; an oscillation command calculation unit configured to calculate an oscillation command, which is a periodic variation component superimposed on a command of the feed axis, based on the spindle speed and the feed speed, as well as an oscillation frequency magnification set in advance; a setting acquisition unit configured to acquire an upper limit value for frequency of the oscillation command; and an adjustment unit configured to adjust the frequency of the oscillation command, or adjust at least either of the spindle speed and the oscillation frequency magnification, so that the frequency of the oscillation command does not exceed the upper limit value.