Tool Head Loose-Mass Damping for Regenerative Chatter
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Solution Overview
Problem
Cutting machines with rotating tool heads experience regenerative chatter due to natural vibration stimulation by surface waviness, leading to quality losses and potential unusability of workpieces, with existing solutions being complex and requiring intensive maintenance.
Innovation Solution
A method and cutting machine design that incorporates a loose additional mass on the tool head, which randomly changes its vibration behavior by touching and then disconnecting from the tool head, altering the natural frequency and counteracting regenerative chatter without mechanical control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If active damping systems or passive damping systems with hydraulic dampers or spring-mass systems are used to prevent regenerative chatter, then regenerative chatter is reduced, but the system becomes extremely complex and maintenance-intensive
Solution Approach 1:
The invention extracts the essential function of damping (mass addition) from complex hydraulic or spring-mass systems, isolating only the necessary element (additional mass) to achieve chatter reduction without the accompanying complexity of full damping systems
Solution Approach 2:
The additional mass is designed as a simple, replaceable component that can be easily installed or removed from the tool head, replacing complex maintenance-intensive damping systems with a simple disposable-like element
2Reliability
If vibration dampers are mounted along the circumference of a tool body with precise position determination, then vibration damping is optimized, but the positioning and installation becomes complex and time-consuming
Solution Approach 1:
The additional mass is deliberately positioned asymmetrically or randomly within the tool head rather than requiring precise symmetric positioning, eliminating the need for complex measurement and positioning procedures while still achieving effective chatter reduction
Solution Approach 2:
The additional mass automatically assumes its optimal position through simple installation without requiring external measurement, calculation, or adjustment procedures, making the system self-configuring
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Effectively reduces regenerative chatter, preventing wave-like irregularities in machined surfaces, and simplifies the solution by eliminating the need for complex systems and intensive maintenance.
Implementation Method 1
The tool head exhibits a first vibration behavior in first positions and a second vibration behavior in second positions
Implementation Method 2
If the load changes are within the range of the natural frequency of the tool head mounted on the spindle, undesirable chatter can occur
Implementation Method 3
a loose additional mass, which can assume various positions relative to the tool head and which touches the tool head in first positions and has no connection with the tool head in second positions
Data Source
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AI summary
The invention relates to a method for reducing regenerative chatter in that a workpiece (1) rotates in relation to a tool head (2) having at least one chip-removal tool (3, 3a, 3b, 3c) arranged at one end of the tool head (2), the tool head (2) machines walls of the workpiece (1) by means of the at least one chip-removal tool (3, 3a, 3b, 3c), the tool head (2) is vibrationally excited during the machining, a loose additional mass (mz) is moved by the vibration, which additional mass randomly touches the tool head (2) in first positions or randomly has no connection to the tool head (2) in second positions, and thus the total mass of the tool head (2) is randomly changed by the amount of the additional mass (mz) and the vibrational behavior of the tool head (2) is changed because of the mass change and thus counteracts regenerative chatter, and in that a receptacle (51), by means of which the tool head (2) can be exchangeably placed onto a spindle, is arranged at another end of the tool head (2) opposite the one end.