Spindle Overload Detection via Intermediate Chamber Flow Sensing
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Solution Overview
Problem
Spindle devices for machine tools face challenges in effectively detecting and preventing overloads, which can damage bearings, especially with medium spindle power, and existing solutions with force sensors are complex and costly.
Innovation Solution
A spindle device with a sensor unit that detects changes in the volume flow of a medium within an intermediate chamber to monitor for overloads, combined with prestressed bearings and a sliding element to ensure constant preload and even force distribution, allowing for real-time monitoring and cost-effective overload protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If force sensors are attached to the spindle device for monitoring overloading, then overload detection capability is improved, but device complexity and cost increase significantly
Solution Approach 1:
The patent replaces complex mechanical force sensors with a pneumatic/hydraulic measurement system. A medium (gas or liquid) is supplied to an intermediate chamber, and changes in volume flow of the medium indicate spindle shaft displacement caused by overloads. This substitution achieves reliable overload detection while avoiding the complexity and high cost of traditional force sensors.
Solution Approach 2:
The patent utilizes pneumatic or hydraulic principles by supplying a medium to an intermediate chamber formed between the housing and spindle shaft. The sensor unit detects volume flow changes of this medium, which correlate with spindle shaft position changes under overload conditions. This approach provides a cost-effective and structurally simple solution compared to mechanical sensing systems.
2Ease of operation
If vibration elements are used to prestress bearings, then bearing smooth operation is improved, but device complexity increases
Solution Approach 1:
The patent employs vibration elements (such as springs) to prestress the bearings before operation begins. This pre-application of cushioning force ensures that the spindle shaft can operate smoothly from the start, absorbing tensile forces that act on clamped tools or workpieces and preventing direct contact between the spindle shaft and bearings under load.
3Stability of the object's composition
If a sliding element is added to transmit spring force evenly, then force distribution uniformity is improved, but device complexity increases
Solution Approach 1:
The patent introduces a sliding element as an intermediary component between the vibration element and the spindle shaft. This sliding element transmits the spring force from the vibration element to the rear bearing in a controlled manner, ensuring even distribution of forces and preventing excessive compressive forces on the vibrating element while optimizing spring force transmission.
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 enables early detection of overloads, prevents damage to the spindle and tool, extends bearing life, and maintains a compact structure while ensuring continuous machining without interruption, all at a lower cost compared to traditional force sensor systems.
Implementation Method 1
a sensor unit arranged in the intermediate chamber, which is set up to detect a volume flow of a medium fed into the intermediate chamber of the spindle device and a change in the volume flow of the medium in the intermediate chamber
Implementation Method 2
the spindle device comprises bearings arranged in the housing and prestressed by at least one vibration element
Data Source
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AI summary
The present invention relates to a spindle device 1 with a housing 2 for use on a machine tool 100, comprising an interface for clamping the spindle device 1 on the machine tool 100, a spindle shaft 3 arranged in the housing 2 for driving a tool and/or workpiece clamped on the spindle device 1, and an intermediate chamber 10 formed between the housing 2 and the spindle shaft 3. Furthermore, the spindle device 1 comprises a sensor unit arranged in the intermediate chamber 10, which is configured to detect a volume flow rate of a medium supplied to the spindle device 1 in the intermediate chamber 10 and to detect a change in the volume flow rate of the medium in the intermediate chamber 10 for monitoring against spindle and/or tool damage or workpiece damage when the spindle shaft 3 is displaced by a force acting on the tool or workpiece and/or the spindle device 1.