Air spring isolator for precision equipment base

Abstract

The application discloses an air spring vibration isolator for a precision equipment base, which comprises a bearing plate and a circular ring-shaped air bag body, the lower end of the bearing plate is swingably hinged to an air bag upper sealing plate of the air bag body, an air chamber is arranged in the ring of the air bag body, air flows between the air chamber and the air bag body, and a horizontal stiffness adjusting mechanism and a vertical stiffness adjusting mechanism for adjusting the horizontal and vertical self-vibration frequencies of the vibration isolator are arranged above the air chamber. The air spring vibration isolator has good bearing capacity and stability, and can adjust the horizontal and vertical self-vibration frequencies, thereby realizing three-dimensional ultra-low frequency vibration isolation.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of vibration isolators, in particular to an air spring vibration isolator for a precision equipment base. BACKGROUND

[0002] In the semiconductor production and laboratory environment, especially in the aspects involving display semiconductors and integrated circuits, etc., a slight vibration can have a negative impact on the normal operation of precision equipment, and thus affect the yield of products or experimental results. In order to reduce the adverse effects of environmental vibration on precision equipment, a vibration isolation base is usually used. In these vibration isolation bases, the air spring is an effective vibration isolation element. However, some air springs for precision equipment currently have a difficult balance between load capacity and stability.

[0003] Specifically, if the load capacity of the air spring is to be large, a larger air chamber is needed. Generally, the air bag and the air chamber of the air spring adopt a double-under tandem structure, which increases the load capacity of the spring, but also leads to an increase in the height of the spring, making the stability of the equipment worse because the center of gravity is raised. Conversely, if the stability is to be improved, the air chamber cannot be integrated, which will reduce the load capacity of the air spring. In addition, some air springs cannot adjust the vertical and horizontal stiffness at the same time, so that three-dimensional ultra-low frequency vibration isolation cannot be achieved. SUMMARY

[0004] The purpose of the present application is to provide an air spring vibration isolator for a precision equipment base with better load capacity and stability, and capable of adjusting the horizontal and vertical natural frequencies.

[0005] Technical solution: In order to achieve the above-mentioned purpose, the air spring vibration isolator for a precision equipment base according to the present application comprises a load bearing plate and a circular ring-shaped air bag body, the lower end of the load bearing plate is swingably hinged to the air bag upper cover plate of the air bag body, an air chamber is arranged in the ring of the air bag body, there is air flow between the air chamber and the air bag body, and the upper part of the air chamber is provided with a horizontal stiffness adjusting mechanism and a vertical stiffness adjusting mechanism for adjusting the horizontal and vertical natural frequencies of the vibration isolator.

[0006] Among them, the load bearing plate is a rotating body formed by rotating a T-shaped structure around its longitudinal center axis, including a horizontal plate and a stand, and the lower end of the stand is a conical structure for hinging with the middle part of the air bag upper cover plate.

[0007] Among them, the air bag upper cover plate is provided with a cylindrical recess in the center for placing the stand, the depth of the recess is less than the height of the stand, and the inner diameter of the recess is greater than the diameter of the stand, so as to support and swing the load bearing plate.

[0008] The air bag main body is a circular ring cavity structure composed of an air bag upper sealing plate, an air bag outer wall, an air bag inner wall and an air bag lower sealing plate.

[0009] The piston damping structure comprises a damping guide ring and a damping cylinder, both of which are circular ring assemblies, the upper end surface of the damping guide ring is fixed on the air bag upper sealing plate, the lower end surface of the damping cylinder is fixed on the air bag lower sealing plate, the lower end of the damping guide ring is located inside the damping cylinder, and high-damping liquid is injected into the damping cylinder.

[0010] The air chamber is a cylindrical cavity structure composed of an air chamber side wall, an air chamber upper plate and the air bag lower sealing plate, the air chamber side wall is provided with an air damping hole, and the inner cavity of the air chamber is communicated with the inner cavity of the air bag main body through the air damping hole.

[0011] The horizontal stiffness adjusting mechanism comprises a plurality of flexible columns which are uniformly arranged on the upper surface of the air chamber upper plate in the radial direction, and the upper end surface of each flexible column is fixed with a horizontal stiffness adjusting bolt, the upper end of the horizontal stiffness adjusting bolt penetrates through the air bag upper sealing plate through a threaded hole in the air bag upper sealing plate.

[0012] The flexible column is made of carbon fiber.

[0013] The vertical stiffness adjusting mechanism comprises a plurality of curved beams which are uniformly arranged above the air chamber upper plate and a plurality of curved beam fixing walls which are uniformly arranged on the upper surface of the air chamber upper plate in the radial direction, one end of each curved beam is provided with a through hole and is fixed on the air bag upper sealing plate through a half-dental bolt, the other end of each curved beam is fixed with a vertical stiffness adjusting bolt, each vertical stiffness adjusting bolt corresponds to a curved beam fixing wall and penetrates through the curved beam fixing wall vertically through a threaded hole in the upper part of the curved beam fixing wall.

[0014] The curved beam is a flat beam section in the transverse direction, the height-width ratio of the flat beam section is less than 0.3, and the material of the curved beam is high-elasticity steel, preferably Q345B.

[0015] Advantages: the air spring vibration isolator has the following advantages: 1. The air spring vibration isolator adopts the air chamber and air bag inner and outer ring parallel structure form, which can ensure the large bearing capacity without increasing the gravity center of the vibration isolator;

[0016] 2. The air spring vibration isolator comprises a vertical stiffness adjusting mechanism composed of symmetrically arranged curved beams, which can reduce the vertical natural frequency of the air spring vibration isolator and ensure that the air spring vibration isolator has good vibration isolation effect in the vertical direction during use;

[0017] 3. The air spring vibration isolator of the present invention forms a horizontal stiffness adjustment mechanism through symmetrically arranged flexible columns, which can reduce the horizontal natural frequency of the air spring vibration isolator and ensure that the air spring vibration isolator has a good vibration isolation effect in the horizontal direction during use.

[0018] 4. The bearing plate utilizes the inverted pendulum effect to further reduce the horizontal natural frequency of the air spring vibration isolator described in this invention;

[0019] 5. The air spring vibration isolator of the present invention obtains viscous damping based on the viscous force between the damping guide ring and the damping fluid in the damping cylinder, and obtains air damping based on the flow of air between the air chamber and the air bag. Thus, through the superposition of viscous damping and air damping, the air spring vibration isolator has high damping characteristics. Attached Figure Description

[0020] Fig. 1 This is a planar schematic diagram of the present invention;

[0021] Fig. 2 This is a schematic cross-sectional view of the present invention (1-1).

[0022] Fig. 3 This is a schematic cross-sectional view of the present invention (2-2).

[0023] In the diagram, 1-bearing plate; 2-airbag upper sealing plate; 3-airbag body; 301-airbag outer wall; 302-airbag inner wall; 4-airbag lower sealing plate; 5-vibration isolator lower support plate; 6-air chamber; 7-damping guide ring; 8-damping cylinder; 101-flexible column; 102-horizontal stiffness adjusting bolt; 201-curved beam; 202-vertical stiffness adjusting bolt; 203-curved beam fixing wall; 204-half threaded bolt; 205-window; 601-air chamber side wall; 602-air chamber upper plate; 603-air damping hole. Detailed Implementation

[0024] The technical solution of the present invention will be described in detail below with reference to the embodiments and accompanying drawings.

[0025] like Figs. 1-3 As shown, the air spring vibration isolator includes a support plate 1, an annular airbag body 3 consisting of an upper sealing plate 2, an outer wall 301, an inner wall 302, and a lower sealing plate 4, and a cylindrical air chamber 6 consisting of a side wall 601, an upper plate 602, and a lower sealing plate 4.

[0026] The bearing plate 1 is a rotating body formed by rotating a T-shaped structure around its longitudinal central axis. It includes a horizontal plate and a column. The horizontal plate serves as the upper component of the rotating body, and its upper end face directly contacts the bottom of the equipment to bear the load of the equipment. The column serves as the lower component of the rotating body, and its lower end is a conical structure for hinged connection with the middle of the airbag upper sealing plate 2.

[0027] The upper cover plate 2 of the air bag is a circular panel, and a cylindrical recess is arranged in the center of the circular panel, the depth of the recess is less than the height of the column, and the inner diameter of the recess is greater than the diameter of the column, so that the column is placed in the recess to provide stable support and appropriate swing space for the bearing plate 1. Further, a conical positioning groove can be arranged in the center of the bottom surface of the recess, and the conical end surface of the column is placed in the conical positioning groove, so that the bearing plate 1 swings in the limited space of the recess with the conical end surface as the origin.

[0028] Due to the support of the air bag body 3, the upper cover plate 2 of the air bag can realize a low natural frequency in the horizontal direction, and the bearing plate 1 is hingedly supported on the upper cover plate 2 of the air bag, and the horizontal swing amplitude of the bearing plate 1 can be further increased based on the inverted pendulum effect, so that the natural frequency of the air spring vibration isolator in the horizontal direction can be reduced.

[0029] The lower cover plate 4 of the air bag is a flat circular panel, and the outer wall 301 and the inner wall 302 of the air bag are located between the upper cover plate 2 and the lower cover plate 4 of the air bag, so as to form a circular ring-shaped air bag body 3 with the upper cover plate 2 and the lower cover plate 4 of the air bag. In order to make the air bag body 3 have more effective damping effect, a piston damping structure is arranged in the air bag body 3, including a damping guide ring 7 and a damping cylinder 8, both of which are circular ring-shaped components. The upper end surface of the damping guide ring 7 is fixed on the upper cover plate 2 of the air bag, the lower end surface of the damping cylinder 8 is fixed on the lower cover plate 4 of the air bag, the lower end of the damping guide ring 7 is located inside the damping cylinder 8, and high-damping liquid is injected into the damping cylinder 8. When the air spring body is deformed due to force, the damping guide ring 7 and the damping liquid in the damping cylinder 8 move relative to each other, and this movement produces a damping effect under the viscous action of the damping liquid. Preferably, the thickness of the damping guide ring 7 is 2mm, the wall thickness of the damping cylinder 8 is 3mm, the distance between the inner ring and the outer ring of the damping cylinder 8 is 100mm, the height is 55mm, and the high-damping liquid is weakly volatile silicone oil.

[0030] The air chamber 6 is located in the ring of the air spring body, and the height of the air chamber 6 is lower than the vertical distance between the recess and the lower cover plate 4. An air damping hole 603 is arranged on the side wall 601 of the air chamber 6, and the inner cavity of the air chamber 6 is communicated with the inner cavity of the air bag body 3 through the air damping hole 603. The air bag body 3 and the air chamber 6 are filled with pure air of a certain air pressure by an air compressor, and the preferred air pressure is 0.3~0.7MPa.

[0031] Under the structure design, the air bag body 3 and the air chamber 6 form the parallel structure of outer ring and inner core. On the basis of large volume inflation and load capacity of the air spring isolator, the height-diameter ratio is small, thereby having good stability. Preferably, the height-diameter ratio of the air spring isolator is less than 0.5. When the airflow flows through the air damping hole 603 in the air chamber 6 and the air bag body 3, the gas damping is generated, thereby further increasing the overall damping ratio of the air spring isolator on the basis of the viscous damping generated in the piston damping structure. Preferably, the air damping hole 603 is opened in three rows in the longitudinal direction, and is opened in a row every 60 degrees in the horizontal direction. Preferably, the damping ratio is not less than 0.3.

[0032] The lower surface of the air bag lower sealing plate 4 is fixed on the lower support plate 5, and the lower support plate 5 provides a stable support platform for the air bag body 3 and the air chamber 6. The above-mentioned load bearing plate 1, air bag upper sealing plate 2, air bag lower sealing plate 4, lower support plate 5, damping guide ring 7, damping cylinder 8, air chamber side wall 601, and air chamber upper plate 602 are all made of steel, preferably Q235B steel.

[0033] The air bag outer wall 301 and the air bag inner wall 302 are made of rubber material. The upper end of the air bag outer wall 301 is pasted on the air bag upper sealing plate 2, and the lower end is pasted on the air bag lower sealing plate 4. The upper end of the air bag inner wall 302 is pasted on the air bag upper sealing plate 2, and the lower end is pasted on the air chamber side wall 601.

[0034] The upper surface of the air chamber upper plate 602 is provided with a horizontal stiffness adjusting mechanism and a vertical stiffness adjusting mechanism. The horizontal stiffness adjusting mechanism includes four groups of flexible columns 101 evenly arranged in the radial direction on the upper surface of the air chamber upper plate 602 (the included angle between the adjacent flexible column 101 and the center line of the air chamber upper plate 602 is 90°). The lower end surface of the flexible column 101 is fixed on the air chamber upper plate 602, and the upper end surface of the flexible column 101 is fixed with a horizontal stiffness adjusting bolt 102. The air bag upper sealing plate 2 is provided with a threaded reserved hole at the position corresponding to each horizontal stiffness adjusting bolt 102, the horizontal stiffness adjusting bolt 102 is screwed with the reserved hole, and the bolt head of the horizontal stiffness adjusting bolt 102 protrudes from the air bag upper sealing plate 2, so as to facilitate the adjustment of the horizontal stiffness adjusting bolt 102.

[0035] The four groups of flexible columns 101 arranged symmetrically produce P-Delta effect under axial pre-stress and horizontal disturbance, i.e. produce force in the same direction as movement, and further produce horizontal negative stiffness. The size of the negative stiffness can be adjusted by the horizontal stiffness adjusting bolt 202, which can further reduce the horizontal natural frequency of the vibration isolator. Specifically, the horizontal stiffness adjusting bolt 202 is adjusted downward, the axial force of the flexible column 101 increases, the horizontal force in the same direction as the movement increases, thereby reducing the horizontal restoring force, thus reducing the horizontal stiffness, resulting in a decrease in the horizontal natural frequency of the vibration isolator. If the horizontal natural frequency of the air spring vibration isolator during use is greater than the design requirement, the horizontal stiffness adjusting bolt 202 can be adjusted downward to the appropriate position to produce horizontal negative stiffness, thereby reducing the horizontal natural frequency to meet the design requirements. The flexible column 101 is made of a material with high flexibility, preferably carbon fiber material.

[0036] The vertical stiffness adjusting mechanism includes four groups of curved beam fixed walls 203 evenly arranged radially on the upper surface of the air chamber upper plate 602 (the included angle between the adjacent curved beam fixed wall 203 and the center line of the air chamber upper plate 602 is 90°), and the curved beam fixed wall 203 is arranged in a spaced manner between the flexible columns 101 (the included angle between the adjacent curved beam fixed wall 203 and the center line of the flexible column 101 is 45°). The lower end surface of the curved beam fixed wall 203 is fixed on the air chamber upper plate 602, and the upper part of each group of curved beam fixed walls 203 is provided with a threaded hole (the axial direction of the threaded hole is consistent with the radial direction of the air chamber upper plate 602 where the threaded hole corresponds to the curved beam fixed wall 203), and a vertical stiffness adjusting bolt 202 is fixed through the threaded hole. The vertical stiffness adjusting bolt 202 penetrates the curved beam fixed wall 203, and the bolt head is located outside the corresponding curved beam fixed wall 203, and the other end is located inside the corresponding curved beam fixed wall 203. The vertical stiffness adjusting bolt 202 is fixed with a curved beam 201 at the inside end of the corresponding curved beam fixed wall 203.

[0037] The curved beam 201 has a flat beam cross section in the transverse direction, and the height-width ratio of the flat beam cross section is preferably less than 0.3, and the horizontal stiffness of the curved beam 201 is greater than the vertical stiffness under this structure. The curved beam 201 is made of high elastic modulus steel, preferably Q345B. The other end of the four groups of curved beams 201 is provided with a through hole, and is fixed to the outer bottom end of the recess through a half-dental bolt 204. The thread of the half-dental bolt only covers the front half of the bolt, and the rear half close to the bolt head is smooth rod-shaped. The through hole of the four groups of curved beams 201 is sleeved on the smooth rod-shaped segment of the half-dental bolt 204, and the threaded end of the half-dental bolt is fixed on the center of the outer bottom end surface of the recess through threaded cooperation (a threaded hole is provided on the center of the outer bottom end surface of the recess, and the threaded hole is not communicated with the tapered positioning groove).

[0038] The air bag upper sealing plate 2 is provided with a window 205 at the corresponding position of each curved beam fixing wall 203, and the vertical stiffness adjusting bolt 202 can be adjusted by a wrench. The vertical stiffness of the curved beam 201 can be adjusted by the vertical stiffness adjusting bolt 202, which can further reduce the vertical natural frequency of the vibration isolator. Specifically, the curved beam that bends upward will generate a force in the same direction as the restoring force under the action of the axial force, thereby generating negative stiffness. When the vertical stiffness adjusting bolt 202 is tightened (adjusted towards the center of the vertical stiffness adjusting mechanism), the overall vertical restoring force in the vertical direction is reduced, thereby reducing the vertical stiffness of the air spring, and ultimately achieving the purpose of reducing the vertical natural frequency.

Claims

1. An air spring isolator for precision equipment base comprising a load plate (1), a circular ring shaped air bag body (3), characterized in that, The lower end of the bearing plate (1) is swingably hinged on the air bag upper sealing plate (2) of the air bag body (3), an air chamber (6) is arranged in the ring of the air bag body (3), air flows between the air chamber (6) and the air bag body (3), the upper portion of the air chamber (6) is provided with horizontal stiffness adjusting mechanism and vertical stiffness adjusting mechanism for adjusting the horizontal and vertical natural frequency of the vibration isolator; The bearing plate (1) is a rotating body formed by rotating a T-shaped structure around the longitudinal center axis, comprising a horizontal plate and a stand, the lower end of the stand is a tapered structure for hinging with the middle portion of the air bag upper sealing plate (2); The air chamber (6) is a cylindrical cavity structure composed of an air chamber side wall (601), an air chamber upper plate (602) and an air bag lower sealing plate (4); The horizontal stiffness adjusting mechanism comprises a plurality of flexible columns (101) uniformly arranged on the upper surface of the air chamber upper plate (602) in the radial direction, the upper end surface of the flexible column (101) is fixed with a horizontal stiffness adjusting bolt (102), the upper end of the horizontal stiffness adjusting bolt (102) penetrates the air bag upper sealing plate (2) through the threaded hole in the air bag upper sealing plate (2). The vertical stiffness adjusting mechanism comprises a plurality of curved beams (201) uniformly arranged above the air chamber upper plate (602) and a plurality of curved beam fixing walls (203) uniformly arranged on the upper surface of the air chamber upper plate (602) in the radial direction, wherein one end of each group of curved beams (201) is provided with a through hole and is fixed on the air bag upper sealing plate (2) through a half tooth bolt (204), the other end of each group of curved beams (201) is fixed with a vertical stiffness adjusting bolt (202), each group of vertical stiffness adjusting bolts (202) corresponds to a curved beam fixing wall (203) and penetrates the curved beam fixing wall (203) vertically through the threaded hole in the upper portion of the curved beam fixing wall (203).

2. The air spring isolator for a precision equipment base of claim 1, wherein, The air bag upper sealing plate (2) is provided with a cylindrical recess in the center for placing the stand, the depth of the recess is less than the height of the stand, and the inner diameter of the recess is greater than the diameter of the stand, so as to provide support and swing space for the bearing plate (1).

3. The air spring isolator for precision equipment pedestals of claim 1 wherein, The air bag body (3) is a circular ring cavity structure composed of the air bag upper sealing plate (2), an air bag outer wall (301), an air bag inner wall (302) and the air bag lower sealing plate (4), and a piston damping structure is arranged in the cavity.

4. The air spring isolator for precision equipment pedestals of claim 3, wherein, The piston damping structure comprises a damping guide ring (7) and a damping cylinder (8), both of which are circular ring assemblies, the upper end surface of the damping guide ring (7) is fixed on the air bag upper sealing plate (2), the lower end surface of the damping cylinder (8) is fixed on the air bag lower sealing plate (4), the lower end of the damping guide ring (7) is located inside the damping cylinder (8), and high-damping liquid is injected into the damping cylinder (8).

5. The air spring isolator for precision equipment pedestals of claim 1 wherein, The air chamber side wall (601) is provided with an air damping hole (603), and the inner cavity of the air chamber (6) communicates with the inner cavity of the air bag body (3) through the air damping hole (603).

6. The air spring isolator for precision equipment pedestals of claim 1 wherein, The flexible column (101) is made of carbon fiber.

7. The air spring isolator for precision equipment pedestals of claim 1 wherein, The curved beam (201) has a flat beam cross section in the transverse direction, the height-width ratio of the flat beam cross section is less than 0.3, and the material of the curved beam (201) is high-elasticity steel.

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