Numerical Control for Oscillating Cutting Speed Limits
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Solution Overview
Problem
In oscillating cutting processes, conventional machine tools face challenges in maintaining appropriate cutting speeds to prevent excessive cutting speed, which can lead to issues like surface roughness, mechanical fatigue, and tool wear, due to varying feed rates and material properties.
Innovation Solution
A numerical control device and method that includes an upper limit value acquisition unit, reference speed calculation unit, oscillation speed calculation unit, cutting speed calculation unit, and speed adjustment unit to dynamically adjust spindle revolution and feedrate to ensure the cutting speed does not exceed a predetermined upper limit, thereby preventing excessive cutting speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If oscillating cutting is performed with high feedrate to improve productivity, then machining efficiency increases, but cutting speed becomes excessively large causing surface roughness, mechanical fatigue, and tool wear
Solution Approach 1:
The patent applies dynamics by making the feedrate variable rather than constant. The feedrate is dynamically adjusted based on the oscillation cycle, being reduced during oscillation periods when cutting speed tends to increase and maintained or increased during non-oscillation periods. This dynamic adjustment prevents excessively large cutting speeds that cause surface roughness and tool wear, while still achieving high average productivity through oscillating cutting.
Solution Approach 2:
The patent changes the feedrate parameter dynamically during the oscillating cutting process. By modifying the feedrate according to the oscillation state and cutting speed conditions, the system optimizes the balance between productivity and manufacturing precision. The feedrate is adjusted as a controllable parameter to ensure cutting speed remains within appropriate ranges, preventing surface roughness and tool wear while maintaining high machining efficiency.
2Productivity
If oscillating cutting is performed with high feedrate to reduce machining time, then productivity improves, but excessive cutting speed causes abnormal wear of cutting tool
Solution Approach 1:
The patent uses dynamic feedrate adjustment to control cutting speed during oscillating cutting. The feedrate is reduced during oscillation cycles when cutting speed increases, preventing excessive speeds that would cause abnormal tool wear. This dynamic control maintains tool reliability while preserving the productivity benefits of oscillating cutting through periodic high-speed material removal.
Solution Approach 2:
The patent implements feedback control by monitoring the cutting speed and adjusting the feedrate accordingly. The system detects when cutting speed approaches excessive levels during oscillation and automatically reduces feedrate to maintain cutting speed within safe limits. This feedback mechanism prevents abnormal tool wear while maintaining high average productivity, as the system continuously adapts feedrate based on actual cutting conditions.
3Productivity
If oscillating cutting is performed with high feedrate to optimize production output, then productivity increases, but excessive cutting speed generates chattering vibration
Solution Approach 1:
The patent applies dynamics by dynamically adjusting feedrate based on oscillation state to prevent chattering vibration. During oscillation periods when cutting speed increases and vibration risk rises, the feedrate is reduced to maintain stable cutting conditions. During non-oscillation periods, feedrate can be higher, maintaining productivity. This dynamic adjustment eliminates chattering vibration while preserving high output rate.
Solution Approach 2:
The patent changes the feedrate parameter dynamically to control vibration stability during oscillating cutting. By adjusting feedrate according to oscillation phase and cutting speed, the system prevents the excessive cutting speeds that generate chattering vibration. This parameter change maintains production output by allowing high average feedrate while ensuring vibration stability through localized reductions during critical oscillation periods.
Data Source
AI summary
A numerical control device according to the present invention includes: an upper limit value acquisition unit which acquires an upper limit value for a cutting speed that is a relative speed of the cutting tool to the workpiece; a reference speed calculation unit which calculates a revolution number of the spindle, and a feedrate; an oscillation speed calculation unit which calculates an oscillation speed that is superimposed on the feedrate; a cutting speed calculation unit which calculates the cutting speed based on the revolution number of the spindle, the feedrate and the oscillation speed; and a speed adjustment unit which adjusts at least either one of the revolution number of the spindle and the feedrate, so that a maximum value of the cutting speed calculated by the cutting speed calculation unit does not exceed the upper limit value acquired by the upper limit value acquisition unit.