ACTIVE AIRBEARING DEVICE

Abstract

The present invention discloses an active airbearing device, including a airbearing body, a gas film active adjusting unit, a support body detection unit and a drive control unit, wherein the support body detection device measures a state of airbearing, the drive control system generates a control signal according to a detection signal, drives and controls the gas film active adjusting device to generate an active action, and dynamically adjusts the form of gas films on a airbearing surface, so as to dynamically adjust pressure distribution of gaps between the gas films of the airbearing device, thereby improving dynamic stiffness characteristics of the airbearing. Through the present invention, the dynamic stiffness characteristics of the airbearing can be improved significantly, and the purpose of stabilizing the airbearing is achieved; in addition, the active airbearing device according to the present invention also has the characteristics of a compact structure, convenient operation and control, and high precision, and thus is especially suitable for occasions such as ultra-precision machining or high speed spindle which has high requirements for dynamic stiffness of support.

Claims

1. An active airbearing device for supporting a precise moving component, wherein the device comprises a airbearing body, a gas film active adjusting unit, a support body detection unit and a drive control unit, wherein: the airbearing body is a bearing structure internally provided with a gas channel, and is mounted with a throttler in a gas outlet of the gas channel facing a gas suspension guide rail; the gas film active adjusting unit includes a plurality of piezoelectric actuators, which is fixedly mounted to the side of the gas outlet of the airbearing body and is machined with the side of the gas outlet to form a continuously flat surface to be jointly used as a working face of airbearing; when compressed gas flows into a gap between the working face and the gas suspension guide rail through the throttler, a gas suspension gas film is formed, and the airbearing body and a moving component fixed therewith are suspended above the gas suspension guide rail; the support body detection unit comprises one of a position sensor with a measurement precision of more than 0.2 m, one of a velocity sensor and an acceleration sensor with a frequency measurement range of more than 50 Hz, which are fixedly arranged on the airbearing body or the precise moving component, and are respectively used to detect in real time a position variation value and a velocity variation value or an acceleration variation value of the airbearing body relative to a supporting direction of the gas film, thereby obtaining a thickness variation value of the gas film of the airbearing; and the drive control unit is respectively connected to the gas film active adjusting unit and the detection device by wire, the drive control unit is configured to filter, amplify and process a signal sensed by the detection device so as to generate a corresponding drive signal to drive the gas film active adjusting unit to execute an expanding or contracting action, thereby changing the overall shape of the working face of airbearing, which acts as the gas suspension gas film, and changing pressure distribution on the gas suspension gas film in the meantime so as to achieve a process of actively regulating dynamic stiffness of airbearing.

2. (canceled)

3. The active airbearing device according to claim 1, wherein, when the airbearing body is a cylindrical bearing structure, the gas film active adjusting unit is preferably composed of a plurality of piezoelectric actuators jointly and is designed as a coaxially distributed ring body; and when the airbearing body is a rectangular bearing structure, the gas film active adjusting unit is composed of a plurality of piezoelectric actuators jointly and is designed as an array-distributed rectangular body.

4. The active airbearing device according to claim 1, wherein the plurality of piezoelectric actuators complete fixing and adhesion between each other and between the piezoelectric actuators and the airbearing body through an adhesive material.

5-7. (canceled)

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] FIG. 1 is a schematic diagram of a main structure of an active airbearing device constructed according to a first preferred implementation of the present invention; and

[0023] FIG. 2 is a schematic diagram of a main structure of an active airbearing device constructed according to a second preferred implementation of the present invention.

[0024] In all the drawings, the same reference signs are used to represent the same elements or structures, wherein:

[0025] 1airbearing body 2gas film active adjusting unit 3support body detection unit 4drive control unit 5moving component 6gas suspension guide rail 11bearing structure

[0026] 12throttler 21piezoelectric actuator 22adhesive material 13bearing structure 23piezoelectric actuator

DETAILED DESCRIPTION

[0027] In order to make the objectives, technical solutions and advantages of the present invention more comprehensible, the present invention is further described below in detail with reference to the accompanying drawings and embodiments. It should be understood that specific embodiments described herein are merely used to explain the present invention instead of being used to limiting the present invention. In addition, technical features involved in various implementations of the present invention described in the following can be combined with each other as long as they do not conflict with each other.

[0028] FIG. 1 is a schematic diagram of a main structure of an active airbearing device constructed according to a first preferred implementation of the present invention. As shown in FIG. 1, the active airbearing device mainly includes a airbearing body 1, a gas film active adjusting unit 2, a support body detection unit 3 and a drive control unit 4, wherein an active adjusting device is used to directly change the shape of gas films of airbearing, and adaptive adjustment is executed for gas source pressure fluctuations at the same time, so that dynamic stiffness characteristics of the airbearing are improved significantly and the purpose of stabilizing the airbearing is achieved.

[0029] Specifically, the airbearing body 1, for example, is a bearing structure 11 internally provided with a gas channel, and is mounted with a throttler 12 in a gas outlet of the gas channel facing a gas suspension guide rail 6; the gas film active adjusting unit 2 is preferably in the form of at least one piezoelectric actuator, which is fixedly mounted to the side of the gas outlet of the airbearing body 1 and is machined with the side to form a continuously flat surface to be jointly used as a working face of airbearing; wherein, preferably, the piezoelectric actuator can be fixed and adhered onto the airbearing body 1 through an adhesive material 22, which are precisely machined together to then form a continuously flat gas suspension working surface; when compressed gas flows into a gap between the working face and the gas suspension guide rail 6 through the throttler 12, a gas suspension gas film is formed and the airbearing body 1 and a moving component 5 fixed therewith, for example, a moving stage, are suspended above the gas suspension guide rail 6.

[0030] The support body detection unit 3 includes one of a position sensor, a velocity sensor and an acceleration sensor, which are fixedly arranged on the airbearing body 1 or the moving component, and are respectively used to detect in real time a position variation value and a velocity variation value or an acceleration variation value of the airbearing body 1 relative to a supporting direction of the gas film, that is, the Z-axis direction shown in FIG. 1; in other words, they are used to detect variation quantity of the thickness of the gas film of airbearing. According to a preferred embodiment of the present invention, the sensors may be selected as a precise position sensor whose working specification is set as that measurement precision can reach more than 0.2 m, and a precise velocity sensor or a precise acceleration sensor whose working specification is set as that a frequency measurement range is more than 50 Hz.

[0031] The drive control unit 4 is respectively connected with the detection device 3 and the gas film active adjusting unit 2, for example, through a wire, and the signal measured by the detection device 3 is filtered, amplified and correspondingly processed, to generate a corresponding drive signal to drive the gas film active adjusting unit 2 connected therewith to deform, for example, for the piezoelectric actuator 21, a control voltage signal is generated to make it execute an expanding or contracting action; in this way, the overall shape of the working face of airbearing, that is, the shape of the gas suspension gas film, changes, and pressure distribution of the gas suspension gas film changes at the same time, so as to achieve a process of actively regulating dynamic stiffness of airbearing. The purpose of active regulation based on a position loop is to increase stiffness of the direction of the airbearing, so as to improve anti-disturbance capability of the airbearing; and the purpose of active regulation based on a velocity loop is to increase damping of the direction of the airbearing, so as to suppress or rapidly attenuate micro vibration of the airbearing.

[0032] For the active airbearing device shown in FIG. 1, as the lower surface is the working face of the gas suspension gas film, the effect of setting multiple groups of components in the gas film active adjusting device 2 is better than that of setting a single one. Shapes and the number of specific components are related to the shape and the dimension of the airbearing. According to a preferred embodiment of the present invention, when the airbearing body 1 is a cylindrical bearing structure, the gas film active adjusting unit is preferably composed of a plurality of piezoelectric actuators jointly and is designed as a coaxially distributed ring body; and when the airbearing body 1 is a rectangular bearing structure, the gas film active adjusting unit is also preferably composed of a plurality of piezoelectric actuators jointly and is designed as an array-distributed rectangular body.

[0033] FIG. 2 is a schematic diagram of a main structure of an active airbearing device constructed according to a second preferred implementation of the present invention. As shown in FIG. 2, upon comparison, the active airbearing device is mainly different from that in FIG. 1 in that specific structures and setting manners of the airbearing body 1 and the gas film active adjusting unit 2 vary.

[0034] Specifically, in a second implementation, the airbearing body 1 is an overall substantially I-shaped bearing structure 13, which is composed of an upper layer and a lower layer of disc-like structures and a middle portion coupled therebetween jointly and is internally provided with a gas channel, a gas outlet of the gas channel facing a gas suspension guide rail is disposed on a lower surface of the bearing structure to thus form a working face of airbearing, and a throttler is mounted in the gas outlet. The gas film active adjusting unit 2 is in the form of a piezoelectric actuator 23, which is fixedly mounted between the two layers of disc-like structures of the airbearing body; when compressed gas flows into a gap between the working face and the gas suspension guide rail through the throttler, a gas suspension gas film is formed and the airbearing body and a moving component fixed therewith are suspended above the gas suspension guide rail.

[0035] During working, the piezoelectric actuator 23 of the gas film active adjusting unit 2 actively expands and contracts to squeeze the bearing structure to deform, so as to dynamically adjust the form of gas films of airbearing and achieve the effect of actively regulating dynamic stiffness of the airbearing. In order to achieve a better active regulation effect, it is necessary to reasonably design structural shapes of the piezoelectric actuator 23 in the gas film active adjusting device 2 and the bearing structure 13 in the airbearing body 1 in a matching manner. The thickness of the disc-like structure at a lower end of the bearing structure 13 should not be too large or too small, if the thickness is too large, the piezoelectric actuator 23 is required to be capable of providing a very big force to effectively regulate the form of the gas film, and if the thickness is too small, the natural vibration frequency of the bearing structure is too low and dynamic stiffness of the airbearing is limited. Therefore, in the present invention, the thickness of the disc-like structure at the lower end is preferably set as 2 mm to 6 mm, and tests indicate that a better regulation effect can be achieved.

[0036] In addition, according to a preferred embodiment of the present invention, it is feasible that the piezoelectric actuator is designed as a ring structure and is assembled in a manner of matching the middle structure of the bearing structure 13.

[0037] It will be easily understood by those skilled in the art that the above descriptions are merely preferred embodiments of the present invention but are not used to limit the present invention, and any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present invention should be included in the protection scope of the present invention.