Thread Cutting Machine Spindle Speed and Feed Axis Control
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Solution Overview
Problem
Existing thread cutting machines face issues with maintaining a constant cutting amount when the rotation speed of the main spindle is changed, leading to potential tool damage due to varying cutting loads at thread-cutting-direction changing parts.
Innovation Solution
A thread cutting machine that computes and maintains a constant acceleration/deceleration delay time for the feed axis by ensuring the product of the main spindle's rotation speed and acceleration/deceleration time remains consistent across all thread cutting passes, using a main-spindle speed computing section and an acceleration/deceleration time computing section.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the rotation speed of the main spindle is changed to suppress chattering vibrations, then vibration suppression is improved, but the cutting amount varies at thread-cutting-direction changing parts causing tool damage risk
Solution Approach 1:
The patent applies dynamics by making the acceleration/deceleration time of the feed axis variable rather than fixed. The control device dynamically adjusts the acceleration/deceleration time based on the rotation speed of the main spindle, allowing the system to adapt to changing operating conditions. This resolves the contradiction by enabling vibration suppression through speed changes while maintaining consistent cutting amount through dynamic parameter adjustment.
Solution Approach 2:
The patent changes the parameter of acceleration/deceleration time to compensate for variations in cutting amount. When the rotation speed of the main spindle is changed, the control device simultaneously adjusts the acceleration/deceleration time of the feed axis to maintain a constant product relationship, ensuring consistent cutting amount at thread-cutting-direction changing parts while still allowing vibration suppression through speed variation.
2Device complexity
If the acceleration/deceleration time of the feed axis is kept fixed while changing main spindle speed, then control simplicity is maintained, but the amount of acceleration/deceleration delay varies causing inconsistent cutting amount
Solution Approach 1:
The patent changes the acceleration/deceleration time parameter from a fixed value to a variable that depends on the main spindle rotation speed. The control device computes and adjusts this parameter dynamically to maintain consistent cutting amount, resolving the contradiction between control simplicity and manufacturing precision by automating the parameter adjustment process.
3Stability of the object's composition
If multi-stage acceleration/deceleration with longer times in higher speed ranges is applied, then vibration suppression is improved, but the variation in acceleration/deceleration delay amount increases causing larger cutting amount variation
Solution Approach 1:
The patent applies parameter changes by computing and adjusting the acceleration/deceleration time based on the specific rotation speed of the main spindle. Rather than using fixed multi-stage acceleration/deceleration patterns, the system dynamically calculates the appropriate acceleration/deceleration time to maintain a constant product relationship, thereby suppressing vibrations while keeping cutting amount variation minimal.
Solution Approach 2:
The patent implements feedback control by continuously monitoring the rotation speed of the main spindle and adjusting the acceleration/deceleration time of the feed axis accordingly. The control device uses the actual rotation speed information to compute the appropriate acceleration/deceleration time, ensuring that the product relationship is maintained and cutting amount consistency is preserved while achieving vibration suppression.
Data Source
AI summary
A thread cutting machine for cutting a thread by rotating a main spindle and moving a feed axis includes a main-spindle speed computing section that computes and outputs a rotation speed of the main spindle based on a main-spindle rotation speed instruction for each thread cutting pass, and an acceleration/deceleration time computing section that computes and outputs an acceleration/deceleration delay time of the feed axis for each thread cutting pass so that a product of multiplication of the acceleration/deceleration delay time of the feed axis and the rotation speed of the main spindle is the same for all thread cutting passes.