CN100575887C - Horizontal gas/gas two-phase compound linear datum method and device based on gravity balance - Google Patents

Abstract

The horizontal gas/gas two-phase composite linear reference method and device based on gravity balance belong to the field of precision instruments and measurement technology; the method is: construct a balanced guide rail under the guide rail to form an open external gas support and act on the air flotation guide sleeve On the thrust plate at the lower part, the gravity balance design of the guide rail and the balance guide rail is carried out according to the load gravity. Under the condition of satisfying the bearing gravity of the balance guide rail, the rigidity of the air film support reaches the maximum value or is within the determined range of the rigidity of the air film support. Inside; the device includes a thrust plate fixed on the lower part of the air bearing guide sleeve, a thrust air bearing couple surface is formed between the thrust plate and the balance guide rail, and a throttling structure facing the balance guide rail is provided on the thrust plate, The balance guide rail is parallel to the guide rail; the invention makes the air bearing guide sleeve have excellent stability, greatly improves the bearing capacity and support rigidity of the guide rail, ensures the high linear accuracy of the guide rail under large load and large stroke, simple structure and wide application range .

Description

Horizontal gas/gas two-phase compound linear datum method and device based on gravity balance

technical field

The invention belongs to the technical field of precision instruments and measurement, and in particular relates to a horizontal gas/gas two-phase compound linear reference method and device based on gravity balance.

Background technique

With the rapid development of advanced manufacturing and measurement technology, more and more large-scale, precision processing equipment and measuring instruments are required to have a large stroke and high load capacity for horizontal linear datums used in high guiding accuracy . Although the traditional sliding friction guideway pair has a large load-carrying capacity, it has been gradually replaced by gas-lubricated guideway due to the defects of low guiding precision, poor motion sensitivity and easy crawling. At present, most of the horizontal linear datums commonly used in high-end instruments and equipment are hydrostatic gas-lubricated guide rails, but there are two problems in practical applications: First, the structure of the guide rail is a fixed beam structure at both ends, that is, the guide rail In the working state, it is in a state of fixed support at both ends and a suspension in the middle. The load gravity all acts on the guide rail. guide rail bending deformation schematic diagram), and this type of deformation is mostly plastic deformation, which directly damages the working accuracy of the guide rail; second, due to the low viscosity of the gas and the compressibility of the gas, the stiffness of the gas support in the vertical direction is relatively small, and the bearing capacity is not high. Large, the thickness of the air film in the vertical direction decreases sharply when bearing an excessive load or impact, which can easily cause direct contact between the air bearing guide sleeve and the guide rail, and the phenomenon of "shaft holding" will occur, seriously damaging the structure of the guide rail. The above-mentioned problems have greatly limited the use of horizontal gas-lubricated guide rails in large-travel, high-load workplaces.

At present, from the perspective of improving the support stiffness and bearing capacity of static pressure gas lubricated guide rails, passive compensation membrane pressure guide rails, active internal throttle air static pressure guide rails, surface throttle air static pressure guide rails, and static pressure control throttles have been proposed. Air static pressure guide rail, electric control throttling air static pressure guide rail, exhaust control air static pressure guide rail and other new air static pressure guide rails. These methods are to take some control measures on the guide rail structure to obtain higher stiffness or controllable stiffness, but their structures are very complicated, and the control and adjustment are also complicated; in addition, these methods have not solved the problem of large travel, large load or Bending deformation of guide rail beam under super load.

The new aerostatic guide rail using porous throttling proposed by the National University of Defense Technology, its basic principle is to use the microstructure of porous materials to throttling, and at the same time set shallow grooves on the surface of the guide rail that communicate with the porous throttling device. Using the impedance of the groove to form a secondary throttling can achieve the purpose of improving the stiffness and bearing capacity of the air guide rail, but this structure is easy to block, and also cannot solve the problem of bending deformation of the guide rail beam under large load and large stroke.

Contents of the invention

The purpose of the present invention is to solve the problems in the above-mentioned prior art, to propose a horizontal gas/gas two-phase composite straight line reference method based on gravity balance, and to build an open external gas support on the basis of a closed internal gas support. And according to the size of the load, the stiffness and bearing capacity of the external gas support should be reasonably designed so that it can balance the force generated by the large load gravity or large impact, so as to significantly improve the stiffness and bearing capacity of the horizontal gas-lubricated guide rail, reduce or eliminate The purpose of bending deformation of guide rail under heavy load. The present invention also provides a horizontal gas/gas two-phase composite linear reference device based on gravity balance based on the method.

Above-mentioned purpose realizes through following technical scheme:

A horizontal gas/gas two-phase composite linear reference method based on gravity balance, specifically comprising the following steps:

a. Construct guide rails to form a straight line reference, which is realized by a conventional fully enclosed horizontal gas static pressure lubrication guide rail;

b. Build a balance guide rail under the guide rail to form an open external gas support;

c. The open external gas support acts on the thrust plate at the lower part of the air bearing guide sleeve, and the gravity balance design of the guide rail and the balance guide rail is carried out _according to the load gravity W;

d. Adjust the air supply pressure of the guide rail to a fixed value P _guide between 0.3 and 0.5MPa, and find the air pressure when the support stiffness is the largest according to the "stiffness-air film thickness" relationship curve corresponding to this pressure. Film thickness H _guide ;

e, then obtain the bearing capacity W _guide of the guide rail at this time from the "load-gas film thickness" relationship curve corresponding to _{the guide} P;

f. According to W _total , the load gravity borne by the balanced guide rail is designed as: W _flat = W _total - W _guide ;

g. Adjust the air supply pressure P _level of the balance guide rail within the range of 0.4 ~ 1.5 MPa. Under the condition that the load of the balance guide rail is W _level , make the air film support stiffness reach the maximum value or be within the determined range of the air film support stiffness Inside.

A horizontal air/air two-phase composite linear reference device based on gravity balance, including an air-floating guide sleeve, a guide rail, a support seat and a balance guide rail, wherein the air-floating guide sleeve and the guide rail form a guiding reference, and the air-floating guide sleeve and the An open external air bearing is formed between the balance guide rails, and the device also includes a thrust plate fixed on the lower part of the air bearing guide sleeve, and the thrust plate is located on the open external air support formed between the air bearing guide sleeve and the balance guide rails Inside, a thrust air-floating couple surface is formed between the thrust plate and the balance guide rail; the thrust plate is provided with a throttling structure B facing the balance guide rail; the balance guide rail is arranged parallel to the guide rail.

The throttling structure B on the thrust plate and the throttling structure A on the air bearing guide sleeve adopt separate air supply structures, or adopt a unified air supply structure after being connected; the throttling structure B on the thrust plate adopts small hole throttling, Slit throttling or porous throttling structure, or mixed throttling structure.

The present invention has following characteristics and beneficial effect:

1. The method of the present invention constructs a double gas support for the size of the external load, and by rationally designing the air bearing force of the guide rail and the balance guide rail, while balancing the load gravity, the internal gas support formed by the guide rail and the balance guide rail are formed. The external gas support achieves the maximum support rigidity at the same time, so that the air bearing guide sleeve and the load placed on it have excellent stability, which is one of the innovation points different from the existing technology;

2. The device of the present invention establishes a balance mechanism for large loads or super-large loads by configuring a balanced guide rail under the guide rail, effectively balancing the load gravity, and can increase the bearing capacity and support rigidity of the guide rail by more than several times according to the actual application situation. To overcome the shortcomings of the existing horizontal gas-lubricated guide rails with low rigidity and low load, this is the second innovation point that distinguishes the existing technology;

3. The gas balance support formed by the balance guide rail in the present invention has the characteristics of synchronous movement with the movement of the air flotation guide sleeve, which is equivalent to installing a "moving support seat" under the air flotation guide sleeve, which can overcome the existing gas lubrication guide rail The lack of rigidity in the middle part significantly reduces or eliminates the bending deformation of the guide rail under heavy load, ensuring that the guide rail still has high linear accuracy under heavy load or large impact, which is the third innovation point that distinguishes the existing technology;

In addition, the present invention has simple structure, simple and convenient design and installation, and wide application range.

Description of drawings

Figure 1 is a schematic diagram of the bending deformation of the existing horizontal gas-lubricated guide rail;

Figure 2 is a schematic structural diagram of a horizontal gas/gas two-phase composite linear reference device based on gravity balance;

Fig. 3 is the A-A direction sectional view of Fig. 2;

Figure 4 is a schematic diagram of the three-dimensional structure of the thrust plate;

Fig. 5 is the B-B direction sectional view of Fig. 4;

Fig. 6 is a C-C cross-sectional view of Fig. 4;

Fig. 7 is a schematic diagram of the structure when the thrust plate and the throttling structure on the air bearing guide sleeve are connected.

In the figure: 1. Air bearing guide sleeve; 2. Guide rail; 3. Support seat; 4. Thrust plate; 5. Balance guide rail; 6. Throttle structure A; 7. Air supply pipe A; 8. Load; 9. Air supply pipe B; 10, throttling structure B; 11, exhaust cavity; 12, exhaust hole; 13, horizontal air channel; 14, longitudinal air channel.

Detailed ways

Embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings.

As shown in Figure 2, the air-floating guide sleeve 1 and the guide rail 2 constitute the basic structure of the horizontal hydrostatic gas-lubricated guide rail. On the guide rail 2, the mating surfaces of the two are precisely ground and assembled, and a closed internal supporting air film is formed between the mating surfaces. As shown in Figure 3, a throttling structure A 6 is provided around the air flotation guide sleeve 1, and an air supply pipe A 7 is connected to the throttling structure A 6, and the external pressure regulator, oil-water separation system and other devices are used as the guide rail 2 Provide the required pressure gas, the pressure gas is sprayed to the corresponding surface of the guide rail 2 to form gas support and lubrication, and then driven by the motor and other drives to drive the air bearing guide sleeve 1 and the load 8 placed on it to move horizontally along the guide rail 2 .

The thrust plate 4 is fixedly connected to the lower part of the air bearing guide sleeve 1, as shown in Figure 4, on which a throttling structure B 10 is arranged, and the throttling structure B 10 is symmetrically distributed with respect to the exhaust chamber 11, and each row is provided with 8 throttling structures, 4 rows are established, and there are transverse air passages 13 and four rows of longitudinal air passages 14; All are connected, and the air is supplied to the guide rail 2 by an integral communication method to ensure that the pressure of each air supply point is balanced; the middle part of the exhaust chamber 11 is provided with a through exhaust hole 12, which helps to quickly discharge the outflowing gas into the atmosphere. Avoid phenomena such as excitation; the gas supply pipe B 9 is connected to the longitudinal air channel 14 to provide the pressure gas required to balance the guide rail; the size of the thrust plate 4 is determined by the load weight and the distribution and setting of the throttling structure B 10.

The balance guide rail 5 is installed parallel to the guide rail 2, and is arranged under the thrust plate 4. The upper surface of the balance guide rail 5 and the thrust plate 4 form a thrust air-floating couple surface, which is opposite to the air-flotation guide sleeve 1 and the parts placed on it. The load 8 forms an upward gas bearing, the lower part of which is fixed on a solid base.

The working principle and working process of the device are as follows: according to the gravity W of the load 8, the gravity balance design of the guide rail 2 and the balance guide rail 5 is _always carried out. First, the pressure gas is led to the throttling structure A 6 through the air supply pipe A 7 to spray the guide rail 2 air flotation working face, and adjust the air supply pressure to a fixed value P _guide between 0.3 and 0.5MP _a , and find the support stiffness according to the corresponding "stiffness-gas film thickness" relationship curve under this pressure as The air film _thickness H at the maximum time; then the load-carrying capacity W of _the guide rail ₂ is obtained from the "load-air film thickness" relationship curve corresponding to P; the load borne by the guide rail 5 _will be balanced according to the gravity W of the load 8 The gravity design is: W _level = W _total - W _guide ; then adjust the air supply pressure P _level of the balance guide rail 5 within the range of 0.4 ~ _1.0MPa , and make the air film under the condition that the load of the balance guide rail 5 is W _level The support stiffness reaches the maximum value or is within the determined range of the air film support stiffness, where P _level is controlled by the pressure regulator connected to the air supply pipe B9; P _guide and P _level control the intake pressure independently.

Since the balance guide rail 5 and the guide rail 2 in this state not only balance the gravity of the load 8, but also obtain the maximum support rigidity at the same time, even when the air bearing guide sleeve 1 is subjected to a large impact, this structure can also be carried out effectively. Inhibit to avoid damage to the guide rail 2. Its working process is: when the impact destroys the original equilibrium state of the air-floating guide sleeve 1, the air-floating guide sleeve 1 deviates from the original equilibrium position, and at the same time the pressure and stiffness of the closed internal support and the established open external support are between Rapid rise in a short period of time until the impact is balanced, so that the air bearing guide bush 1 has high impact stability.

The thrust plate 4 and the balance guide rail 5 can be made of materials with good stability such as special alloy or granite.

In the present invention, the throttling structure B 10 on the thrust plate 4 and the throttling structure A 6 on the air-floating guide sleeve 1 can also adopt a unified air supply structure after being connected, as shown in Figure 7.

The horizontal linear datum constructed on the basis of the present invention establishes a balance mechanism for large loads or super-large loads, effectively balances the influence of load gravity on the guide rail 2, and can be designed according to actual usage conditions, so that the bearing capacity and support of the guide rail The rigidity is increased by more than several times, especially suitable for high-precision large-scale equipment and instruments with large strokes and large loads.

In addition, because the present invention adopts the method of adding external air support to improve the support rigidity and bearing capacity of the guide rail, it basically has no effect on the guiding accuracy of the original guide rail 2, and the structure is simple, and the design and installation are easy.

Claims (4)

1, a kind of horizontal gas/gas two-phase composite straight line reference method based on gravitational equilibrium specifically may further comprise the steps:

A, structure guiding rail form linear datum, and this benchmark is realized by the lubricated guide rail of the totally-enclosed horizontal gas-static of a conventional type;

B, below described guiding rail, make up the balance guide rail, form the supporting of open type extraneous gas; It is characterized in that:

C, this open type extraneous gas supporting role are on the anti-thrust plate of air supporting guide pin bushing bottom, and at load gravity W _AlwaysCarry out the gravitational equilibrium design of guiding rail and balance guide rail;

D, the supply gas pressure of guiding rail is adjusted to a certain fixed value P between 0.3～0.5MPa _Lead, and the air-film thickness H when finding its support stiffness maximum according to pairing under this pressure " rigidity-air-film thickness " relation curve _Lead

E, again by P _LeadCorresponding " load-air-film thickness " relation curve obtains the load-bearing capacity W of guiding rail this moment _Lead

F, according to W _AlwaysThe load gravity that the balance guide rail is born is designed to: W _Flat=W _Always-W _Lead

G, at 0.4～1.5MP _aAdjust the supply gas pressure P of balance guide rail in the scope _Flat, satisfying the W that is carried as of balance guide rail _FlatUnder the condition, make its air film support stiffness reach maximal value or be in this air film support stiffness and determine in the scope.

2, a kind of horizontal gas/gas two-phase composite straight line standard apparatus based on gravitational equilibrium, comprise air supporting guide pin bushing (1), guiding rail (2), supporting base (3) and balance guide rail (5), wherein air supporting guide pin bushing (1) and guiding rail (2) are formed oriention benchmark, form the supporting of open type extraneous gas between air supporting guide pin bushing (1) and the balance guide rail (5), it is characterized in that this device also comprises the anti-thrust plate (4) that is fixed on air supporting guide pin bushing (1) bottom, this anti-thrust plate (4) is positioned at the open type extraneous gas supporting that forms between air supporting guide pin bushing (1) and the balance guide rail (5), forms thrust air supporting idol face between anti-thrust plate (4) and the balance guide rail (5); Anti-thrust plate (4) is provided with the throttle structure B (10) towards balance guide rail (5); Balance guide rail (5) is parallel to guiding rail (2) and arranges.

3, a kind of horizontal gas/gas two-phase composite straight line standard apparatus based on gravitational equilibrium according to claim 2 is characterized in that throttle structure B (10) and the throttle structure A (6) on the air supporting guide pin bushing (1) on the anti-thrust plate (4) adopts separately gas-supplying structure separately.

4, a kind of horizontal gas/gas two-phase composite straight line standard apparatus according to claim 2 based on gravitational equilibrium, it is characterized in that the throttle structure B (10) on the anti-thrust plate (4) adopts orifice restriction, slit throttling or porous matter throttle structure, perhaps adopts and mixes throttle structure.

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