Seismic Displacement Control Assembly With Adaptive Friction Damping
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Solution Overview
Problem
Semiconductor fabrication tools are vulnerable to damage from seismic vibrations due to the difficulty in optimizing friction forces in passive dampers, which can result in either insufficient damping or excessive impulse forces during earthquakes.
Innovation Solution
The use of displacement control assemblies with passive dampers that increase dampening with displacement magnitude and include inclined track portions to enhance frictional force, ensuring the damper returns to a central position after the seismic event, thereby preventing damage to the tools.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If passive dampers are used for seismic protection, then damping effect is provided, but friction force optimization is difficult resulting in either insufficient damping or excessive impulse forces
Solution Approach 1:
The patent applies dynamics by making the friction force adjustable rather than fixed. The normal force between the damper and track can be dynamically modified by changing the relative position of the support plate and brake plate, allowing the friction characteristics to adapt to different seismic conditions and avoid both insufficient damping and excessive impulse forces.
Solution Approach 2:
The patent changes the parameter of normal force in the friction interaction. By adjusting the vertical position of the support plate relative to the brake plate, the normal force pressing the damper against the track is modified, which directly changes the friction force. This parameter adjustment enables optimization of damping performance without increasing device complexity.
2Reliability
If friction force is increased to improve damping, then seismic displacement suppression is enhanced, but impulse force during earthquake may become excessive causing tool damage
Solution Approach 1:
The system dynamically adjusts the friction characteristics during seismic events. The relative motion between the support plate and brake plate automatically modulates the normal force, allowing the friction force to be high during steady displacement suppression but reduced during rapid impulse events, thereby protecting the tool from excessive impulse forces while maintaining damping effectiveness.
Solution Approach 2:
The damper is positioned and configured in advance to provide cushioning protection. By pre-setting the damper's engagement with the track and the normal force characteristics, the system is prepared to absorb and dissipate seismic energy before excessive impulse forces can reach the tool, effectively cushioning against potential damage.
3Reliability
If damper is positioned away from central position during seismic event, then displacement control is achieved, but damper may not return to central position after seismic event
Solution Approach 1:
The patent employs a counterweight mechanism where the relative motion between the support plate and brake plate creates a restoring force. When the damper moves away from the central position during a seismic event, the changing normal force and friction characteristics generate a counteracting force that pushes the damper back toward the central position after the seismic disturbance subsides, ensuring position stability.
Solution Approach 2:
The system inverts the typical damper behavior by using the friction force not only for displacement suppression but also for automatic recentering. The friction interaction, which normally resists motion, is utilized in reverse to provide a restoring force that returns the damper to its central position after seismic displacement, maintaining system readiness for future events.
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 effectively suppresses seismic displacement of semiconductor manufacturing tools, reducing the risk of damage by providing consistent and adaptive damping, ensuring the tools remain stable and operational during earthquakes.
Implementation Method 1
a damper secured to one of the support plate or the brake plate and frictionally engaging a track of the other of the support plate or the brake plate
Data Source
AI summary
A support platform is configured to support at least a portion of the weight of an associated semiconductor manufacturing tool, such as a furnace, when the associated semiconductor manufacturing tool is disposed on the support platform. The support platform comprises a base, a support plate disposed on the base and configured to move respective to the base, a brake plate arranged in fixed position respective to the base, and a damper secured to one of the support plate or the brake plate and frictionally engaging a track of the other of the support plate or the brake plate. The track includes a central track portion and inclined track portions extending away from the central track portion on respective first and opposite second sides of the central track portion. The inclined track portions are each inclined with respect to the central track portion.