Air-Bearing Spindle Gap Control for Thermal Deformation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The spindle unit in grinding apparatuses is prone to thermal deformation during initial operation, leading to contact between the spindle and housing, which can result in scratching and reduced rotation due to the formation of a narrow air bearing gap, compromising its ability to resist grinding loads.
Innovation Solution
Incorporating a thrust bearing with a piezoelectric actuator that adjusts the gap distance between the spindle and housing, allowing for non-contact air-supported rotation, and a voltage control unit to manage the air pressure, ensuring continuous operation and high load resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the gap between the spindle and housing is narrowed to form a high load resistance air bearing, then the resistance to grinding load is improved, but thermal deformation causes contact between the spindle and housing leading to scratching and rotation failure
Solution Approach 1:
The air bearing gap is made dynamically adjustable through a piezoelectric actuator that can change the gap distance in real-time. During idle periods, the gap is widened to prevent thermal contact, and during grinding operations, the gap is narrowed to provide high load resistance, thus resolving the contradiction between load resistance and continuous rotation capability
Solution Approach 2:
The physical parameter of the air bearing gap distance is changed based on operational conditions. The piezoelectric actuator enables precise control of the gap distance, transitioning from a fixed narrow gap to a variable gap that can be optimized for both thermal stability and load resistance requirements
2Reliability
If the air bearing gap is widened to prevent thermal deformation and contact, then continuous rotation is maintained, but the load resistance and rigidity of the air bearing deteriorates
Solution Approach 1:
The system dynamically adjusts the air bearing gap based on operational state. The piezoelectric actuator widens the gap during idle periods to ensure continuous rotation, then narrows it during grinding operations to restore high load resistance, effectively resolving the trade-off between reliability and strength
Solution Approach 2:
The air bearing gap is periodically adjusted according to the operational cycle of the spindle. During idle periods, the gap is maintained wide for safe rotation, and during grinding periods, the gap is narrowed for high load resistance, creating a periodic adjustment pattern that balances both requirements
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 solution enables continuous spindle rotation by widening the gap during temperature stabilization and narrowing it during grinding, preventing contact and maintaining high rigidity, thus ensuring reliable operation and reducing idle time.
Implementation Method 1
the adjusting unit has a piezoelectric actuator disposed in the spindle and configured to move the outer surface of the spindle forming the thrust bearing, in the axial direction of the spindle
Implementation Method 2
the spindle unit includes a spindle housing that surrounds an outer circumferential surface of the spindle with a gap formed therebetween and an air supply portion that supplies air to the gap. An air bearing is formed by filling the gap with air and pressurizing the air
Data Source
AI summary
A spindle unit includes a spindle having a processing tool fitted to a distal end of the spindle; and a spindle housing having a thrust bearing and a radial bearing configured to support the spindle by air in a rotatable and noncontact manner, the thrust bearing including an air supply portion configured to supply air to a gap between an outer surface of the spindle, the outer surface being in a direction orthogonal to an axial direction of the spindle, and an inner surface of the spindle housing, and an adjusting unit capable of adjusting a distance of the gap in a direction perpendicular to the outer surface of the spindle.