An Electro-magnetic Air Spring for Vibration Control in Semiconductor Manufacturing

Jeong

et al. 2018

Smart Mater. Struct.

In a previous work, magneto-rheological (MR) dampers were originally designed and implemented for reducing the vertical low-frequency vibration occurring in precise semi-conductor manufacturing equipment. To reduce the vibrations, an isolator levitated the manufacturing machine from the floor using pneumatic pressure which cut off the external vibration, while the MR damper was used to decrease the transient response of the isolator. However, it has been found that the MR damper also provides a damping effect on the lateral vibration induced by the high-speed plane motions. Therefore, in this work both vertical and lateral vibrations are controlled using the yield and shear stresses of the lateral directions generated from the MR fluids by applying a magnetic field. After deriving a vibration control model, an overall control logic is formulated considering both vertical and lateral vibrations. In this control strategy, a feedback loop associated with the laser sensor is used for vertical vibration control, while a feed-forward loop with the motion information is used for lateral vibration control. The experimental results show that the proposed concept is highly effective for lateral vibration control using the damping effect on multiple directions.

Section: Structure Of the Hybrid Mountmentioning

confidence: 99%

Lateral vibration control of a precise machine using magneto-rheological mounts featuring multiple directional damping effect

Jeong

et al. 2018

Smart Mater. Struct.

Advances in Mechanical Engineering

“…Kim et al 6 studied EMASVI for several years and in their design electromagnetic actuator was mounted in air chamber of air spring. It was concluded that after implementing active control, impulse response delay time decreased 77%, resonance frequency of the system improved, and the vibration peak reduced 62%.…”

Section: Introductionmentioning

confidence: 99%

The relationship between stiffness variation and performance of electromagnetic-air spring vibration isolator

Zhang

Shu

Song

et al. 2016

In order to isolate the structural vibration in high-frequency range effectively and constrain the peak response value near the natural frequency, an experience method using electromagnetic-air spring vibration isolator was put forward based on the respective advantages of electromagnetic actuator and air spring. In this article, a stiffness expression and a natural frequency of the system was worked out. A dynamic model of the electromagnetic-air spring vibration isolator system and an expression of the force transmission were established. Moreover, the relationship between stiffness variation and performance of the electromagnetic-air spring vibration isolator system was analyzed. The calculation and simulation analysis of the example demonstrated that in the condition of satisfying loading capacity with the increase in magnetic suspension isolator's displacement stiffness and the decrease in air spring's stiffness, the performance of vibration isolation is improved.

“…The air mount must satisfy the vibration criteria of the floor vibration, and should also absorb the machine vibration quickly. We have been developing air mounts based on pneumatic and EM forces for precision machines in clean rooms [12,13]. The air mount is a kind of active air spring in which EM actuators are present within a pneumatic system.…”

Section: Introductionmentioning

confidence: 99%

A novel triple-actuating mechanism of an active air mount for vibration control of precision manufacturing machines: experimental work

Choi

et al. 2014

Smart Mater. Struct.

Self Cite

With the goal of vibration control and isolation in a clean room, we propose a new type of air mount which consists of pneumatic, electromagnetic (EM), and magnetorheological (MR) actuators. The air mount is installed below a semiconductor manufacturing machine to reduce the adverse effects caused by unwanted vibration. The proposed mechanism integrates the forces in a parallel connection of the three actuators. The MR part is designed to operate in an air spring in which the EM part is installed. The control logic is developed with a classical method and a switching mode to avoid operational mismatch among the forces developed. Based on extended microprocessors, a portable, embedded controller is installed to execute both nonlinear logic and digital communication with the peripherals. The pneumatic forces constantly support the heavy weight of an upper structure and maintain the level of the air mount. The MR damper handles the transient response, while the EM controller reduces the resonance response, which is switched mutually with a threshold. Vibration is detected by laser displacement sensors which have submicron resolution. The impact test results of three tons load weight demonstrate practical feasibility by showing that the proposed triple-actuating mechanism can reduce the transient response as well as the resonance in the air mount, resulting in accurate motion of the semiconductor manufacturing machine.