Dental Machining Unit Force Sensor Placement
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Solution Overview
Problem
Dental machining apparatuses face inaccuracy in measuring machining forces due to a time delay between force changes and current changes, leading to dead time and inaccuracy in measurement processes.
Innovation Solution
A force sensor is positioned between the tool spindle and the bearing housing to directly detect machining forces, using strain-gage elements or piezo elements, ensuring no relative movement and accounting for sensor-side deformations, allowing for independent detection of cutting forces from motor-driven spindle and current uptake.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If machining force is determined indirectly via motor current uptake, then the measurement system remains simple, but measurement accuracy deteriorates due to dead time between force changes and current changes
Solution Approach 1:
A force sensor is introduced as an intermediary element between the tool spindle and bearing housing to directly measure machining forces. This mediator provides accurate force data without requiring complex motor current analysis, eliminating the dead time problem while maintaining system simplicity.
Solution Approach 2:
The indirect electrical measurement method (motor current uptake) is replaced with a direct mechanical measurement approach using a force sensor. This substitution eliminates the time delay inherent in electrical response while providing immediate force data.
2Measurement precision
If a force sensor is introduced to directly measure machining forces, then measurement accuracy improves, but device complexity increases
Solution Approach 1:
The force sensor is merged with the bearing housing structure, integrating the measurement function into the existing support structure. This combination eliminates the need for separate mounting components and reduces overall device complexity while maintaining measurement accuracy.
Solution Approach 2:
The bearing housing serves dual functions: supporting the tool spindle mechanically and housing the force sensor for measurement. This multi-functionality reduces the number of separate components needed, thereby simplifying the overall device structure.
3Stability of the object's composition
If the force sensor is rigidly connected to prevent relative movements, then measurement stability improves, but sensor deformation from elasticities increases measurement error
Solution Approach 1:
The connection characteristics are optimized by adjusting geometric parameters of the bracing members (thickness, length, material properties) to achieve the ideal balance between stability and minimal deformation. This parameter optimization ensures rigid enough connection for stability while flexible enough to minimize measurement error.
Solution Approach 2:
The bracing members are designed with specific local properties (varying cross-sections, strategic thickness variations) to distribute stresses appropriately and minimize deformation at the sensor location while maintaining overall connection stability.
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
This setup enables precise detection of all machining forces transmitted to the spindle holder, providing accurate cutting force measurement independent of motor current, enhancing the accuracy and reliability of dental machining processes.
Implementation Method 1
the force sensor has at least one sensor element in the form of a measuring bridge or a piezo element, in which case the measuring bridge is designed using thick film technology or as a strain-gage element
Implementation Method 2
the force sensor has at least one sensor element in the form of a measuring bridge or a piezo element
Data Source
AI summary
The present invention relates to dental machining apparatus (1) for blanks (3) comprising a tool spindle (2) having an axis of rotation (2.8) and mounted in a bearing housing (1.2) disposed on the machine housing side. A force sensor (5) is also provided, which is disposed between the tool spindle (2) and the bearing housing (1.2) for the purpose of detecting the machining force acting on the tool spindle (2), wherein the tool spindle (2) can be supported against the bearing housing (1.2) directly or indirectly via the force sensor (5).