NC Drilling Feed Control for High-Speed Low-Vibration Hole Opening
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Solution Overview
Problem
Conventional numerical control devices for machine tools experience reduced machining efficiency and increased vibration during drilling processes, especially when cutting holes at narrow spacings, due to the differences in servo control and acceleration/deceleration settings between fast feed and cutting feed controls, leading to extended machining times and tool wear.
Innovation Solution
A numerical control device that operates the machine tool in a single control mode for positioning, cutting, and retraction processes, using the cutting feed control to maintain continuous movement and switch to fast feed control based on predetermined positioning distances, thereby optimizing feed speeds and acceleration/deceleration settings to minimize vibration and maximize speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If fast feed control is used for positioning to improve machining speed, then positioning speed is improved, but vibration increases due to high acceleration/deceleration and stop of moving shaft
Solution Approach 1:
The system dynamically switches between fast feed control mode and cutting feed control mode based on the machining situation. When positioning distance is large, fast feed control is used for high speed. When positioning distance is small or during cutting, cutting feed control is used to reduce vibration. This dynamic adaptation resolves the contradiction between speed and vibration.
Solution Approach 2:
The control mode parameter is changed based on positioning distance and machining stage. The system monitors positioning distance and automatically switches control parameters (acceleration/deceleration settings, feed rate limits) between fast feed mode and cutting feed mode, optimizing both speed and vibration control.
2Measurement precision
If monitoring of tool arrival at command position is implemented to ensure positioning accuracy, then positioning precision is improved, but machining time is extended
Solution Approach 1:
The cutting feed control maintains continuous movement of the tool without stopping to monitor arrival, unlike fast feed control. This continuous action eliminates the time loss from monitoring and stopping, while still achieving adequate positioning through acceleration/deceleration control optimized for the specific distance.
Solution Approach 2:
For short positioning distances, the system uses cutting feed control which applies more conservative acceleration/deceleration settings than strictly necessary for speed, but this partial action (reduced acceleration) prevents the need for monitoring and stopping, actually saving time overall while ensuring smooth operation.
3Productivity
If switching between fast feed control and cutting feed control is performed to optimize both speed and vibration, then machining efficiency is improved, but device complexity increases due to multiple control modes
Solution Approach 1:
The numerical control device integrates both fast feed control and cutting feed control functions within a single unified control system. The same control unit handles both modes and automatically selects the appropriate mode based on positioning distance and machining stage, avoiding the need for separate independent control systems.
Solution Approach 2:
The system uses feedback from the positioning distance calculation and current machining stage to automatically determine which control mode to use. This closed-loop decision-making simplifies the control architecture by using programmed logic rather than complex hardware switching mechanisms.
4Object-generated harmful factors
If cutting feed control is used for all operations to maintain continuous movement, then vibration is reduced, but positioning speed decreases for long distances
Solution Approach 1:
The positioning process is segmented into different stages based on distance: long-distance positioning uses fast feed control for high speed, while short-distance positioning and cutting operations use cutting feed control for low vibration. This segmentation allows each stage to use the optimal control mode.
Solution Approach 2:
The control mode is periodically switched based on the positioning distance and machining stage. The system evaluates whether to switch between fast feed and cutting feed modes at each positioning step, creating a rhythmic pattern of mode switching that optimizes both speed and vibration control throughout the machining process.
Data Source
AI summary
The objective of the present invention is to provide a numerical control device and control method with which it is possible for hole opening to be performed at high speed and with low vibration. This numerical control device for performing hole opening continuously at prescribed intervals in a workpiece, using a machine tool, is provided with: a positioning unit for moving a hole opening tool of the machine tool to a hole opening position of the workpiece, and positioning the hole opening tool; a cutting unit; a retracting unit for retracting the hole opening tool from the workpiece; and a program executing unit for executing a machining program for causing the machine tool to continuously machine the workpiece, by sequentially executing movement axis operation using the same control scheme for the processing performed by the positioning unit, the cutting unit, and the retracting unit.