CN101737426B - Vacuum negative pressure gas-static super-precision guide rail - Google Patents

Abstract

A vacuum negative pressure gas static pressure ultra-precision guideway structure belongs to the technical fields of precision measurement, ultra-precision processing, micro-machines, nanotechnology and the like. The guide rail is fixed on the upper surface of the base through the guide rail pad; the slider surrounds the guide rail, and there is a compressed gas film gap between the two sides of the guide rail and the inner surface of the slider, forming a static pressure air floatation state; the lower bottom surface of the slider There are small holes for compressed gas flow and a vacuum chamber, and there are vacuum adsorption airflow holes in the slider; it is characterized in that: the slider is designed as a symmetrical closed structure, and the vacuum chamber and the slider have the same symmetrical centerline; the slider and the base There is a compressed gas film gap between the upper surface; the gap size between the upper surface of the guide rail and the inner upper surface of the slider is c, and the gap size between the lower surface of the guide rail and the inner lower surface of the slider is d; c and d are not less than the guide rail itself The amount of deformation due to weight. The guiding precision of the guide rail is high, the precision retention is good, and the rigidity is high.

Description

A vacuum negative pressure gas static pressure ultra-precision guide rail

technical field

The invention relates to an ultra-precision guide rail and a positioning technology and device, and belongs to the technical fields of precision measurement, ultra-precision machining, micro-machines and nanotechnology.

Background technique

Precision guide rails are the foundation and key of precision positioning systems. Due to its high precision and cleanliness, the gas static pressure precision guide rail has been widely used in the technical fields of modern precision measurement, ultra-precision machining, micro-mechanics and nanotechnology. There are two types of gas static pressure precision guide rails: closed type and open type.

The principle of the existing closed gas hydrostatic guideway is shown in Fig. 1a and Fig. 1b. In Fig. 1a and Fig. 1b, 1 is a slider, 2 is a guide rail, and 3 is a guide rail pad. The slider 1 floats on the guide rail 2 through the compressed gas film to form a closed gas static pressure guide rail. The compressed gas pressure in the opposite direction forms a balance, maintains the fixed gap between the slider and the guide rail, and ensures the guiding accuracy of the guide rail.

In the existing closed gas static pressure guide rail, due to the influence of the self-weight of the guide rail, the weight of the slider and the weight of the load on the slider, the guide rail is prone to bending deformation, which affects the accuracy. The change of the position of the slider leads to the change of the stress point of the guide rail, the deformation of the guide rail also changes, and the precision retention of the guide rail is poor.

The gas static pressure precision guide rail with vacuum negative pressure and the gas static pressure precision guide rail with magnetic force adsorption are two common forms of the existing open gas static pressure guide rail. The principle of the existing vacuum negative pressure gas static pressure precision guide rail is shown in FIG. 2 . In Fig. 2, 4 is a slider, 5 is a guide rail, arrows a and b are vacuum negative pressure airflow, and other arrows indicate the direction of compressed gas airflow. In Figure 2, the slider 4 floats on the guide rail 5 through the compressed gas film, and the vacuum negative pressure airflows a and b form a vacuum adsorption force, which is balanced with the weight of the slider, the weight of the load and the pressure of the compressed gas to maintain the sliding The fixed gap between the block and the guide rail ensures the guiding accuracy of the guide rail.

The principle of magnetic adsorption gas static pressure precision guide rail is shown in Figure 3a and Figure 3b. In Fig. 3a and Fig. 3b, 6 is a slider, 7 is a guide rail, 8 is a magnetic pole S, 9 is a magnetic pole N, and the arrow indicates the direction of the compressed gas flow. In Figure 3a and Figure 3b, the slider 6 floats on the guide rail 7 through the compressed gas film, and the two opposite magnetic poles 8 and 9 form an attractive magnetic force, and the attractive magnetic force, the weight of the slider, the weight of the load and the pressure of the compressed gas are kept in balance. , maintain the fixed gap between the slider and the guide rail, and ensure the guiding accuracy of the guide rail.

The existing vacuum negative pressure gas static pressure guide rail and magnetic adsorption gas static pressure precision guide rail, due to the non-closed structure of the slider, the slider rigidity is low, and the deformation of the slider results in poor precision retention of the guide rail. The existing vacuum negative pressure gas static pressure guide rail cannot guarantee thermal symmetry, and thermal deformation has a great influence on the guiding accuracy.

To sum up, it is necessary to study an ultra-precision guide rail with high rigidity of the slider, and the guiding accuracy is not affected by the weight of the guide rail, the slider weight and the weight of the load.

Contents of the invention

The purpose of the present invention is to design a vacuum negative pressure gas static pressure ultra-precision guiding principle with high rigidity and guide accuracy not affected by the weight of the guide rail, the slider weight and the weight of the load. Pressed ultra-precision guide rail.

As far as the structure and guiding principle of the guide rail is concerned, it forms a static pressure air bearing guide on both sides of the guide rail, and the direction of the air buoyancy force on both sides is opposite to maintain balance and maintain a fixed gap between the slider and the side of the guide rail; the bottom plane design of the slider It is an air-floating guide surface, and a vacuum cavity is designed on the air-floating guiding surface. The vacuum adsorption force is generated by the vacuum generation and adjustment device. The vacuum adsorption force, the gravity of the slider, the gravity of the load and the compressed gas pressure are kept in balance, maintaining The fixed gap between the slider and the upper surface of the base ensures the guiding accuracy of the guide rail.

The technical solution of the present invention is shown in schematic diagrams in Figure 4a and Figure 4b, a vacuum negative pressure gas static pressure ultra-precision guide rail structure of the present invention, the guide rail is fixed on the upper surface of the base through the guide rail pad; the slider is surrounded on the guide rail , There is a compressed gas film gap between the two sides of the guide rail and the inner surface of the slider, forming a static pressure air flotation state; there are compressed gas flow holes and vacuum chambers on the lower bottom surface of the slider, and there are vacuum adsorption airflow holes in the slider ;

It is characterized in that: the slider is designed as a symmetrical closed structure, the vacuum chamber and the slider have the same symmetrical center line; there is a compressed gas film gap between the slider and the upper surface of the base; the upper surface of the guide rail and the inner surface of the slider The gap size on the upper surface is c, and the gap size between the lower surface of the guide rail and the inner and lower surface of the slider is d; c and d are not less than the deformation caused by the weight of the guide rail itself.

The guiding accuracy guarantee feature of the present invention is that the slide block 10 moves along the X axis, and the rotation of the slide block 10 around the X axis, the Y axis and the Z axis axis and the movement along the Y axis and the Z axis are the key factors determining the guide accuracy; The gravity of the object acts on the slider 10, and the air buoyancy force is generated by the air film formed between the bottom plane of the slider 10 and the upper surface of the base due to the compressed gas. A vacuum adsorption force is formed between the bottom plane of the base and the upper surface of the base, and the vacuum adsorption force, air buoyancy, slider gravity, and weight of the load are kept in balance, maintaining a fixed gap between the slider 10 and the upper surface of the base, and limiting the slider 10. Move along the Z axis and rotate around the X and Y axes; the slider 10 is surrounded by the guide rail 11, the two sides of the guide rail 11 and the inner surface of the slider 10 form a static pressure air flotation state, and the compressed gas pressure in the opposite direction forms a balance, maintaining The fixed gap between the slider 10 and the guide rail 11 restricts the movement of the slider 10 along the Y axis and the rotation around the X axis and the Z axis; the aforementioned movement and rotation restrictions improve the guiding accuracy.

The inner upper surface of the slider 10 has no compressed gas flow holes, so no compressed gas film is formed between it and the upper surface of the guide rail 11; A compressed gas film is formed between the lower surfaces of the guide rails 11 . The gap dimension c between the upper surface of the guide rail 11 and the inner and upper surface of the slider 10 is designed to be not less than the amount of deformation caused by the weight of the guide rail 11 itself, and the gap dimension d between the lower surface of the guide rail 11 and the inner and lower surface of the slider 10 is designed not to It is smaller than the deformation of the guide rail 11 due to its own weight, avoiding the weight of the slider 10 acting on the guide rail 11, thereby avoiding the bending deformation of the guide rail 11 caused by the weight of the slider 10 and the weight of the load; the deformation of the guide rail 11 due to its own weight is not The change occurs due to the change of the position of the slider 10 on the X axis, so that the guide accuracy is maintained well.

The slider 10 is designed as a symmetrical closed structure, forming symmetrical force deformation and thermal deformation, and the slider 10 has high rigidity.

Compared with the existing gas static pressure guide rail, the vacuum negative pressure gas static pressure ultra-precision guide rail of the present invention has the following obvious advantages and beneficial effects:

1. The weight of the slider and the weight of the load directly act on the high-precision surface of the base, and the guiding accuracy of the guide rail is not affected by the weight of the slider and the weight of the load;

2. The guiding accuracy of the guide rail is not affected by the position change of the slider, and the accuracy is maintained well;

3. The slider is a closed structure with high rigidity;

4. A force-symmetric and thermal-symmetric structure is formed, and force deformation and heat deformation have little influence on the accuracy of the guide rail.

Description of drawings

Figure 1a is a schematic diagram of the principle of a traditional closed gas hydrostatic guideway;

Fig. 1b is a sectional view along A-A of Fig. 1a;

In Fig. 1a and Fig. 1b, 1 is a slider, 2 is a guide rail, and 3 is a guide rail pad.

Figure 2 is a schematic diagram of the principle of a traditional vacuum negative pressure gas static pressure precision guide rail;

In Figure 2, 4 is the slider and 5 is the guide rail

Figure 3a is a schematic diagram of a traditional magnetic adsorption gas static pressure precision guide rail;

Fig. 3b is the left view of Fig. 3a;

In Figure 3a and Figure 3b, 6 is the slider, 7 is the guide rail, 8 is the magnetic pole S, 9 is the magnetic pole N,

Figure 4a is a schematic diagram of the vacuum negative pressure gas static pressure ultra-precision guide rail of the present invention;

Figure 4b is a sectional view along B-B of Figure 4a;

Fig. 4c is a view from arrow C of Fig. 4b.

In Fig. 4a, Fig. 4b and Fig. 4c: 10 is the slider, 11 is the guide rail, 12 is the guide rail pad, 13 is the vacuum chamber, 14 is the vacuum adsorption airflow hole, 15 is the compressed air flow hole; c is the size of the upper gap, d is the size of the lower gap, e is the gap between the guide rail 11 and the left side of the slider 10, f is the gap between the guide rail 11 and the right side of the slider 10, k is the air film between the bottom plane of the slider 10 and the upper surface of the base The gap, the direction indicated by the arrow is the airflow direction.

Detailed ways

Below in conjunction with accompanying drawing 4a, Fig. 4b, Fig. 4c will further illustrate the present invention:

Guide rail structure description: The guide rail 11 is fixed on the upper surface of the base through the guide rail pad 12; the slider 10 is surrounded by the guide rail 11, and the fixed gaps e and f are maintained between the two sides of the guide rail 11 and the inner surface of the slider; the slider 10 is air-floated On the upper surface of the base, there is a vacuum chamber 13 on the lower bottom surface of the slider 10, and a fixed gap k is maintained between the slider 10 and the upper surface of the base; the gap size between the upper surface of the guide rail 11 and the inner upper surface of the slider 10 is designed as c, the gap dimension between the lower surface of the guide rail 11 and the inner lower surface of the slider 10 is designed as d.

The working principle of the guide rail: the slider 10 moves along the X-axis, the rotation of the slider 10 around the X-axis, the Y-axis and the Z-axis axis and the movement along the Y-axis and the Z-axis are the key factors that determine the guiding accuracy. The gravity of the load acts on the slider 10, and the airflow hole on the bottom plane of the slider 10 is filled with compressed gas with a flow rate of 300 liters per minute and a pressure of 6 bar. The gap between the slider 10 and the upper surface of the base is compressed The gas film produces air buoyancy, and the vacuum generating and adjusting device generates a flow rate of 200 liters per minute at the vacuum adsorption airflow hole 16, thereby vacuumizing the vacuum chamber 13, so that the bottom plane of the slider 10 and the base A vacuum adsorption force is formed between the upper surfaces, and the vacuum adsorption force maintains a balance with the air buoyancy force, the gravity of the slider, and the gravity of the load, and maintains a fixed gap k between the bottom plane of the slider 10 and the upper surface of the base, (the value of k is 4~ A value between 20 μm, the present embodiment selects 8 μm), limit the movement of the slider 10 along the Z axis and the rotation around the X and Y axes; There is compressed gas with an adjustable flow rate of 300 liters/min in the small hole. The two sides of the guide rail 11 and the inner surface of the slider 10 form a static pressure air flotation state under the action of the compressed gas, and the pressure of the compressed gas in the opposite direction forms a balance. Maintain the fixed gaps e and f between the slider 10 and the guide rail 11 (the values of e and f take a value between 4 and 20 μm, 8 μm is selected in this embodiment), and limit the movement of the slider 10 along the Y axis and around the X axis and Rotation of the Z-axis; the aforementioned movement and rotation limitations improve guidance accuracy.

The inner upper surface of the slider 10 has no compressed gas flow holes, so no compressed gas film is formed between it and the upper surface of the guide rail 11; A compressed gas film is formed between the lower surfaces of the guide rails 11 . The gap c between the upper surface of the guide rail 11 and the inner upper surface of the slider 10 is designed to be no less than the deformation caused by the weight of the guide rail 11 itself. In this embodiment, the calculated and measured deformation of the guide rail 11 due to its own weight is 12.5 μm, and the value of c is designed to be 10 mm. The gap dimension d between the lower surface of the guide rail 11 and the inner lower surface of the slider 10 is designed to be no less than the amount of deformation of the guide rail 11 caused by its own weight. In this embodiment, the d value is designed to be 10mm. This design prevents the weight of the slider 10 from acting on the guide rail 11, thereby avoiding the bending deformation of the guide rail 11 caused by the weight of the slider 10 and the weight of the load; Changes in position, resulting in good retention of guiding accuracy. The slider 10 is designed as a symmetrical closed structure, forming symmetrical force deformation and thermal deformation, and the slider 10 has high rigidity.

There is a vacuum chamber 13 at the bottom of the slider 10, and the cross-sectional shape of the vacuum chamber can be a symmetrical rectangle, hexagon or circle, etc., and this embodiment is a circle. The upper part of the vacuum chamber 13 has a vacuum adsorption airflow hole 14, and the bottom of the slider 10 has an airflow small hole 15. The vacuum chamber 13 and the slider 10 have the same symmetrical center lines i-i' and j-j'. This structural design ensures that the slider has the characteristics of force symmetry and thermal symmetry, and has good precision retention.

The above embodiments are only used to illustrate the present invention and are not intended to limit the technical solutions described in the present invention. Although the specification has described the present invention in detail with reference to the above-mentioned embodiments, the present invention is not limited to the above-mentioned specific implementation methods, so Any modification or equivalent replacement of the present invention; and all technical solutions and improvements that do not deviate from the spirit and scope of the invention shall be covered by the claims of the present invention.

Claims (1)

1. the gas-static super-precision guide rail structure of a negative pressure of vacuum, guide rail is fixed on the pedestal upper surface by the guide rail pad; Slide block is encircled on guide rail, has pressurized gas air film gap between the bi-side of guide rail and the inner side surface of slide block, forms the static pressure air-bearing state; Pressurized gas air-flow aperture and vacuum chamber are arranged on the bottom surface of slide block, the vacuum suction airflow hole is arranged in the slide block;

It is characterized in that: slider designs is the enclosed construction of symmetry, and vacuum chamber has identical symmetrical center line with slide block; There is pressurized gas air film gap between slide block and pedestal upper surface; The interior upper surface gap size of the upper surface of guide rail and slide block is c, and the interior lower surface gap size of the lower surface of guide rail and slide block is d; C and d are not less than the amount of deformation that the guide rail own wt causes.

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