Machine Tool Chatter Avoidance Through Operator-Defined Rule Sequences
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Solution Overview
Problem
Metal-cutting machining by machine tools often results in undesired vibrations, known as chattering, which lead to lower-quality surfaces, increased wear, and potential tool breakage, and existing methods to prevent chattering are not consistently effective or efficient.
Innovation Solution
A method where a control device in a machine tool receives predefined rules from an operator through a human-machine interface or memory device, allowing for the selection, parameterization, and specification of sequences to modify machining parameters like spindle speed and feed speed in response to chattering, ensuring the contour of the workpiece is not affected.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If feed speed and/or rotational speed are reduced to avoid chattering, then chattering is reduced, but machining time increases and productivity decreases
Solution Approach 1:
The patent applies dynamics by making the machining parameters (feed speed, rotational speed) dynamically adjustable during the machining process. The control device continuously monitors for chattering and automatically modifies parameters in real-time, transitioning from static pre-set parameters to dynamic adaptive control. This resolves the contradiction by allowing high productivity when no chattering occurs and automatically reducing speed only when necessary to suppress chattering.
Solution Approach 2:
The patent implements feedback control by using sensors to detect vibrations and chattering during machining, then feeding this information back to the control device. The control device processes this feedback and automatically adjusts machining parameters to eliminate chattering while maintaining optimal productivity. This closed-loop feedback system resolves the contradiction by making parameter adjustments based on actual machining conditions rather than conservative pre-reductions.
2Object-affected harmful factors
If operator intervenes using overrides to adjust feed speed and/or rotational speed, then chattering is quickly suppressed, but the process requires manual intervention and is not consistently effective across different machining processes
Solution Approach 1:
The patent applies self-service by enabling the machine tool system to automatically detect and correct chattering without operator intervention. The control device monitors vibrations, identifies chattering conditions, and autonomously adjusts machining parameters to suppress chattering. This resolves the contradiction by replacing manual operator overrides with automated self-correction, making the system both easier to operate and consistently effective across different machining processes.
Solution Approach 2:
The patent uses feedback control where sensors continuously monitor machining conditions and feed vibration data back to the control device. The control device automatically processes this feedback and adjusts parameters to eliminate chattering, replacing the need for manual operator intervention. This automated feedback loop ensures consistent effectiveness across different machining processes while improving ease of operation.
3Reliability
If predefined rules are stored in the control device for automatic modification, then operator knowledge is incorporated reliably, but the system complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-programming multiple predefined rules in the control device that cover various chattering scenarios and parameter adjustments. These rules are prepared in advance based on operator knowledge and different machining conditions. When chattering is detected, the control device automatically selects and applies the appropriate pre-prepared rule, resolving the contradiction by making the system reliable through comprehensive pre-planning while managing complexity through structured rule organization.
Solution Approach 2:
The patent segments the chattering avoidance function into multiple discrete predefined rules, each handling specific scenarios or parameter adjustments. This segmentation allows the complex control logic to be divided into manageable, independent rule modules that can be individually developed, tested, and maintained. The segmentation resolves the contradiction by organizing complexity into structured segments while maintaining high reliability through comprehensive rule coverage.
Data Source
AI summary
A control device of a machine tool receives a target machining, in accordance with which a workpiece should be machined by a tool of the machine tool. The control device also receives via a human-machine interface or via an interface to an external memory device a selection, a parameterization and/or a specification of a sequence of predefined rules, which define the manner in which the machining of the workpiece should be modified in the event of undesired vibrations during machining. When undesired vibrations do not occur, as determined from acquired sensor signals, machining is carried out in accordance with the target machining. When undesired vibrations occur, the machining is modified in accordance with the rules, wherein the control device selects the rules in accordance with the selection, parameterizes the rules in accordance with the parameterization and/or carries out the rules in accordance with the specified sequence.