Thread-Cutting Control with Alternating Oscillation Passes
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Solution Overview
Problem
Existing machine tool control devices face high load and incomplete cutting issues during thread cutting due to continuous oscillating operations, leading to increased cycle time and difficulty in shredding chips effectively.
Innovation Solution
A control device that coordinates spindle and feed axis operations, incorporating an oscillating operation execution determination unit to intermittently execute oscillating and non-oscillating cuts, generating oscillation commands to ensure previous cutting portions are included in subsequent operations, thereby reducing machine tool load and ensuring reliable chip shredding without extending cycle time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If continuous oscillating operation is performed during thread cutting, then chip shredding is achieved, but machine tool load increases and cycle time extends
Solution Approach 1:
The patent applies periodic action by alternating between oscillating cutting and non-oscillating cutting in a cyclic manner. The oscillating operation is performed for a predetermined number of passes to achieve chip shredding, then non-oscillating cutting is performed for a predetermined number of passes to reduce machine tool load and prevent overheating, creating a periodic cycle that balances chip removal effectiveness with productivity maintenance
2Reliability
If oscillating operation is continuously performed, then chip removal is improved, but positional deviation increases causing incomplete cutting
Solution Approach 1:
The patent uses periodic action to alternate between oscillating and non-oscillating cutting modes. During oscillating cutting, chips are effectively removed; during non-oscillating cutting, the machine tool stabilizes and positional deviation decreases. This periodic alternation ensures that by the time oscillating cutting resumes, the system has recovered from positional deviation, preventing incomplete cutting while maintaining chip removal effectiveness
Solution Approach 2:
The patent applies beforehand cushioning by inserting non-oscillating cutting passes between oscillating cutting passes. These non-oscillating passes act as a cushioning period that allows the machine tool to stabilize and reduce positional deviation before the next oscillating cutting operation, preventing the accumulation of positional errors that would lead to incomplete cutting
3Reliability
If oscillating operation is performed to shred chips, then chip removal is effective, but machine tool load becomes excessively large
Solution Approach 1:
The patent implements periodic action by cycling between oscillating cutting (which shreds chips effectively but creates high load) and non-oscillating cutting (which reduces load). This periodic alternation allows the machine tool to perform high-load oscillating cutting for chip shredding, then recover during low-load non-oscillating cutting passes, preventing excessive cumulative load and potential damage while maintaining effective chip removal
Solution Approach 2:
The patent maintains continuity of useful action by ensuring that during the non-oscillating cutting passes between oscillating operations, cutting continues to occur and material is still removed. This ensures that the machining process remains productive throughout the entire cycle, with no idle time, while still allowing the machine tool to recover from high load conditions during the non-oscillating portions
Data Source
AI summary
To provide a control device for a machine tool capable of performing thread cutting while reducing the load on the machine tool from the oscillating operation, without extending the cycle time, and capable of reliably shredding chips in a case of performing the non-oscillating operation in the present pass after the oscillating operation in the previous pass. A control device for a machine tool includes: an oscillating operation execution determination unit that determines whether to execute an oscillating operation that causes the cutting tool to oscillate in the radial direction of the workpiece; an oscillation command generation unit that generates an oscillation command of the oscillating operation based on a determination result; a control unit that superimposes the oscillation command on a position command of the feed axis to generate a drive command. The oscillating operation execution determination unit determines to intermittently execute the oscillating operation, and the oscillation command generation unit generates an oscillation command so that a non-oscillating cutting portion of a present pass includes a portion at which oscillating cutting was performed in a previous pass, or so that an oscillating cutting portion of the present pass includes a portion at which non-oscillating cutting was performed in the previous pass.