Machine Tool Spindle With Balancing Mass for Vibration Decoupling
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Solution Overview
Problem
Conventional spindle arrangements for machine tools experience reduced machining accuracy and increased positioning errors due to vibrations introduced into the machine structure, leading to defects and reduced tool life during vibration-assisted machining.
Innovation Solution
A spindle arrangement with a compensating device featuring an annular balancing mass operatively connected to the spindle, driven by actuators, which actively decouples inertial forces, allowing the spindle to move independently and minimizing vibrations introduced into the machine structure, thereby enhancing machining accuracy and tool life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If vibration-assisted machining is implemented using conventional spindle arrangements, then productivity and tool life are improved through enhanced chip breaking and cooling lubricant supply, but machining accuracy deteriorates due to vibrations introduced into the machine structure causing increased positioning errors
Solution Approach 1:
A compensating device with a balancing mass is coupled to the spindle arrangement. The balancing mass is actuated to generate counter-vibrations that oppose the vibrations introduced during vibration-assisted machining, thereby compensating for the inertial forces and preventing vibration transmission to the machine structure, thus maintaining machining accuracy while enabling productivity improvements
Solution Approach 2:
The compensating device acts as an intermediary between the spindle arrangement and the machine structure. It decouples the vibration source from the machine structure by introducing a balancing mass that absorbs and counteracts vibrational energy, preventing the transmission of harmful vibrations to the machine structure while allowing the spindle to maintain its vibration-assisted machining function
2Productivity
If vibration-assisted machining is implemented using conventional spindle arrangements, then chip breaking and chip removal are improved, but tool life is reduced due to defects and failures caused by force components introduced into the machine structure
Solution Approach 1:
The balancing mass in the compensating device generates counter-vibrations that cancel out the force components transmitted to the machine structure during vibration-assisted machining. This prevents defects and failures in both the machine structure and tooling, thereby extending tool life while maintaining the improved chip breaking and chip removal characteristics
Solution Approach 2:
The vibrational forces that would normally be harmful to the machine structure and tool life are converted into a beneficial effect by using them to drive the balancing mass. The balancing mass utilizes these same vibrational frequencies to generate counteracting forces, transforming the harmful vibration transmission into a useful compensation mechanism that protects the system while maintaining productive machining
3Productivity
If a mechanical cam drive is used to vibrate the spindle in the Z-direction, then vibration-assisted machining is achieved, but path accuracy is reduced and positioning error around the axis of movement is increased
Solution Approach 1:
The compensating device with balancing mass counteracts the positioning errors and path accuracy degradation caused by mechanical cam drive vibrations. By generating opposing vibrational forces, the balancing mass cancels out the detrimental effects on path accuracy while preserving the vibration-assisted machining capability, thereby maintaining high positioning precision around the axis of movement
4Speed
If rolling element bearings are used in the spindle arrangement subjected to vibration-induced force components, then the spindle can operate at high speeds, but defects and failures occur due to the force components introduced by vibrations
Solution Approach 1:
The balancing mass in the compensating device counteracts the force components that would otherwise be transmitted to the rolling element bearings during vibration-assisted machining. By canceling these vibrational forces, the bearings operate under more stable conditions, preventing defects and failures while allowing the spindle to maintain high-speed operation
Solution Approach 2:
The compensating device serves as an intermediary that protects the rolling element bearings from the harmful effects of vibration-induced force components. It decouples the vibration source from the bearing system, allowing the bearings to function at their designed high speeds without the detrimental impacts of transmitted vibrations, thereby improving reliability
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
The solution significantly increases positioning accuracy and tool life by decoupling vibrations, improving process parameters and reducing energy requirements, while maintaining a compact and efficient design.
Implementation Method 1
an actuator or an actuator arrangement for exciting this tool or the tool spindle to vibrate... the vibrations are in the range of more than 5 kHz via vibration units for vibration-assisted machining
Implementation Method 2
The oscillating device is designed with a balancing mass, which oscillates in the opposite direction to the vibration of the tool cutting edge, so that pulses are decoupled and the desired processing frequency can therefore be set independently of the natural frequency of the device
Implementation Method 3
an active decoupling of pulses in at least two axes of the machine tool, so that the spindle arrangement can move outwards... Due to this pulse decoupling, the vibrations affecting the tool and the workpiece during hybrid machining are not introduced into the machine structure
Data Source
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AI summary
The invention relates to a spindle arrangement for a machine tool, comprising a spindle (2) for driving a tool (6) and at least one actuator (20) for exciting vibration of the tool (6), characterized in that the spindle arrangement (2) is provided with a compensation device (30) for at least partly compensate the inertia forces produced by the vibration excitation in the spindle region.