JP6147114B2 - Vibration isolator - Google Patents

Description

  The present invention relates to a vibration isolator formed by supporting a surface plate on which equipment is mounted with a plurality of gas springs with respect to a foundation.

  2. Description of the Related Art Conventionally, a vibration isolator for insulating a device (for example, a precision device such as an electron microscope) from minute vibrations of a floor (foundation) is known. An example of this type of vibration isolator is disclosed in Patent Document 1.

  In the vibration isolator disclosed in Patent Document 1, a plurality of air springs are disposed between a base fixed to a foundation and a surface plate on which equipment is placed, and these air springs provide vibration isolation for the surface plate. Is done. The vibration isolator is provided with a clamp device in order to prevent an excessive vibration damping load from being applied to the air spring due to the vibration of the surface plate during transfer of the vibration isolator. This clamping device is disposed between the base and the surface plate, is fixed on the base, and has a gate-shaped restricting member having a through-hole formed in the upper wall. The bolt extends and penetrates the through-hole, and has a pair of nuts that are screwed into the bolt and are arranged above and below the upper wall of the restriction member. The clamp device clamps and fixes the upper wall of the base from above and below by both nuts during transfer of the vibration isolator, and restricts the movement of the bolt by the regulating member to maintain the distance between the surface plate and the foundation. On the other hand, when using the vibration isolator, the nuts are separated to release the clamping and allow the surface plate to move.

Japanese Patent No. 4235246 (paragraphs 0020, columns 0034 to 0036, FIG. 1)

  However, in the vibration isolator of Patent Document 1, when the mounted device vibrates during use, the gas pressure of the air spring cannot resist the load of the surface plate and the mounted device, the surface plate sinks, and the air spring May come into contact with the case.

  Therefore, in order to suppress the sinking of the surface plate, it is conceivable to add mass to the surface plate on the supported body side (that is, on the spring) and increase the air pressure of the air spring. Is required, and material costs and manufacturing costs increase.

  This invention is made | formed in view of this point, The place made into the objective is to suppress the displacement on a spring, without changing on a spring.

  In order to achieve the above object, the present invention adds a load applied to the gas spring by pulling the surface plate toward the base side.

  Specifically, the present invention is directed to a vibration isolator that supports a surface plate on which equipment is placed with a plurality of gas springs with respect to a foundation, and has taken the following solution.

That is, the invention of claim 1 is provided between the surface plate and the foundation, and includes load applying means for applying a load downward to the surface plate, and the load adding means has a linear spring constant. A tension member that pulls the surface plate downward, the tension member is formed of a coil spring, and the load applying means is a clamp device that maintains a distance between the surface plate and the foundation, The clamping device is fixed to the base side and protrudes upward, a bolt extending downward from a position corresponding to the restriction member of the surface plate, and a bolt penetrating the upper wall portion of the restriction member, A pair of nuts threadedly engaged with the bolts on the upper and lower sides of the upper wall part, and disposed in a pre-compressed state between the upper wall part and the lower nut, and surrounding the bolts; The upper end is fixed to the upper wall, and Urges the lower side of the nut downward, has the coil spring to pull the platen downwardly, the upper nut is characterized in that spaced from the upper wall.

  According to the first aspect of the present invention, a load acting on the gas spring is applied from the surface plate by the load adding means, and the gas pressure of the gas spring increases against the applied load. Therefore, since the gas pressure of the gas spring can resist the load on the spring, the displacement on the spring can be suppressed.

  According to the first aspect of the present invention, since the load adding means is disposed between the surface plate and the foundation, it is not necessary to change the surface plate on the spring.

  As mentioned above, according to invention of Claim 1, the displacement on a spring can be suppressed by raising the gas pressure of a gas spring, without changing on a spring.

According to the first aspect of the present invention, the load adding means has the tension member that pulls the surface plate downward, and the spring constant thereof has a linear characteristic. Even if changes, the natural frequency does not change, and stable vibration isolation performance can be maintained.

According to the invention of claim 1 , since the tension member is constituted by a relatively inexpensive coil spring among the members having a linear spring constant, the manufacturing cost can be suppressed.

According to invention of Claim 1 , a load addition means can be comprised using the existing clamp apparatus. That is, when the vibration isolator is transferred, the upper and lower pair of nuts are brought close to each other and the upper wall portion of the restriction member is clamped and fixed by the upper nut and the coil spring, and the restriction member restricts the vertical movement of the bolt. While restricting the movement of the board, when the vibration isolator is used, the movement of the surface plate is permitted by releasing the clamping and fixing by separating the pair of upper and lower nuts. When the vibration isolator is used, the coil spring urges the lower nut downward, whereby the surface plate can be pulled downward and a load acting on the gas spring from the surface plate can be applied.

  As mentioned above, according to this invention, the load which acts on a gas spring from a surface plate is added by a load addition means, and the gas pressure of a gas spring increases against this added load. Therefore, since the gas pressure of the gas spring can resist the load on the spring, the displacement on the spring can be suppressed. Further, since the load adding means is disposed between the surface plate and the foundation, it is not necessary to change the surface plate that is on the spring. From the above, the displacement on the spring can be suppressed by increasing the gas pressure of the gas spring without changing the spring top.

It is a top view of the vibration isolator which concerns on embodiment of this invention. It is a front view of the vibration isolator which concerns on embodiment of this invention. It is a side view of the vibration isolator which concerns on embodiment of this invention. It is a schematic diagram which shows schematic structure of an air spring unit. It is the VV sectional view taken on the line of FIG. It is a top view which shows typically the testing apparatus used for the performance evaluation test. It is a figure which shows the time change of the downward displacement of a surface plate at the time of changing the spring constant of a compression coil spring. It is a figure which shows the relationship between the deflection amount of a compression coil spring, and its tensile force.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The following description of the preferred embodiments is merely exemplary in nature and is not intended to limit the invention, its application, or its application.

  1 to 3 are views showing a vibration isolation device 1 according to the present embodiment. FIG. 1 is a plan view, FIG. 2 is a front view, and FIG. 3 is a side view. The vibration isolator 1 is equipped with a precise device that is easily affected by vibration, such as a semiconductor-related manufacturing device, a test device, an atomic force microscope (AFM), and a precision measuring device such as a laser microscope. They are intended to be installed in a state insulated as much as possible from the vibration of the floor. More specifically, the vibration isolator 1 shown in the figure includes a base 5 installed on the floor surface 4, more specifically on a dedicated table or table, and air springs disposed at four corners of the upper surface. A precision device (not shown) and the like are mounted on a surface plate 9 made of a rectangular steel plate supported by these four air spring units 7, 7,. Further, four clamping devices 11, 11, 11, 11 are disposed between the adjacent air spring units 7, 7,. In addition, the said surface plate 9 is abbreviate | omitted in FIG. 1 to 3 schematically show the air spring units 7, 7,...

  The base 5 is made of a rectangular steel plate and is installed on the floor surface 4.

  As schematically shown in FIG. 4, the air spring unit 7 is provided with an air spring 13 that supports a load in the vertical direction, sensors 15, 17, 19, a controller 21, a servo valve 23, and the like. The vibration in the vertical direction and the height position are controlled. Although the same configuration is provided for horizontal vibration and position control, only the configuration of the vertical air spring 13 and the like will be described below for convenience.

  A piston 25 is inserted in an airtight manner through a diaphragm in the upper opening of the air chamber of the air spring 13, and a top plate 27 is disposed on the upper surface of the piston 25. On the other hand, the base plate 29 at the lower end of the case of the air spring 13 is fixed on the base 5. Since the static load is supported by the air spring 13 in this way, the air spring units 7, 7,... Basically have excellent vibration isolation performance. In this embodiment, the internal pressure of the air spring 13 is further increased. And an appropriate control force is applied to the vibration isolation object.

  For this purpose, the acceleration sensor 15 is first detected in the air spring unit 7 so as to detect the vertical acceleration z ″ of the top plate 27 and the relative displacement z−z0 of the top plate 27 with respect to the base plate 29, respectively. (Vibration sensor) and a displacement sensor 17 are also provided, and an acceleration sensor 19 (foundation-side vibration sensor) for detecting the vertical acceleration z0 ″ (foundation-side vibration state) of the base plate 29 is also provided. The output signals from the sensors 15, 17 and 19 are input to the controller 21, respectively.

  Further, a servo valve 23 is connected to the air chamber of the air spring 13 via a pipe, and the operation of the servo valve 23 adjusts the flow rate of the compressed air supplied from the reservoir tank 31 to the air chamber. Adjust the flow rate of air exhausted from the air chamber. Note that a compressor (not shown) is connected to the reservoir tank 31, and the air pressure in the reservoir tank 31 is maintained at a set value by its operation.

  Then, the servo valve 23 is controlled by the controller 21, and the internal pressure of the air spring 13 is adjusted by adjusting the flow rate of compressed air supply / exhaust to the air spring 13, so that the object of vibration isolation is obtained. A control force to be added can be generated. Although not shown in detail, the controller 21 has a conventionally known structure including a microcomputer, an I / O interface, a data bus, and a memory such as a RAM, a ROM, or an HDD.

  The clamp device 11 is for preventing an excessive vibration damping load from being applied to the air spring 13 when the surface plate 9 vibrates on the base 5 when the vibration isolator 1 is transferred. is there.

  The clamp device 11 includes a lower plate 33 made of a rectangular steel plate bolted to the base 5, and a regulating member 35 formed by bending the rectangular steel plate into a U shape. Both ends of the lower plate 33 are fixed to both ends of the lower plate 33 and protrude upward. A through hole 35b is formed in the upper wall portion 35a of the regulating member 35 so as to penetrate in the vertical direction.

  The clamp device 11 has an upper plate 37 made of a rectangular steel plate installed at a position corresponding to the restriction member 35 on the lower surface of the surface plate 9, and a bolt 39 extends downward from the lower surface of the upper plate 37 and the restriction plate 35. The through hole 35b of the member 35 is penetrated.

  A pair of nuts 41 and 43 are screwed onto the upper and lower sides of the upper wall portion 35a of the bolt 39. A metal washer 42 is disposed between the upper nut 41 and the upper wall portion 35 a of the restricting member 35, and the bolt 39 is inserted through the washer 42. On the other hand, between the lower nut 43 and the upper wall portion 35a, a metal compression coil spring (tensile member) 45 and a metal washer 46 are disposed in order from the top. The compression coil spring 45 is disposed in a compressed state so as to surround the bolt 39, and the upper end is fixed to the lower surface of the upper wall portion 35 a, while the lower side is interposed via the washer 46. The nut 43 is urged downward.

  In the clamp device 11 having the above-described configuration, when the vibration isolator 1 is transferred, the pair of upper and lower nuts 41 and 43 approach each other, and the upper nut 41 and the compression coil spring 45 are used to The upper wall portion 35a is sandwiched from above and below, and the restriction member 35 restricts the vertical movement of the bolt 39. Thereby, the movement of the surface plate 9 is restricted, and the distance between the surface plate 9 and the base 5 is maintained.

On the other hand, when the vibration isolator 1 is used, the clamp device 11 is configured such that the pair of upper and lower nuts 41 and 43 are separated from the upper wall portion 35a , and the compression coil spring 45 lowers the lower nut 43 downward. Energize to. As a result, the surface plate 9 is pulled downward, so that the air springs 13, 13,... Have a load F (=) obtained by adding a tensile load Ft (N) to the load Mg (N) of the surface plate 9. Mg + Ft) (N) acts (see FIG. 2). Since the air springs 13, 13,... Are evenly arranged at the four corners of the vibration isolator 1, the load acting on each air spring 13 is F / 4 (= (Mg + Ft) / 4). (N). Therefore, the clamp device 11 constitutes a load applying means for applying a load acting on the air springs 13, 13,.

  Then, the controller 21 controls the servo valve 23 to adjust the supply amount of the compressed air supplied to each air spring 13, and the air pressure P (N / m 2) of each air spring 13 is adjusted as described above. From the pressure Mg / 4A (N / m2) (A is the pressure receiving area) balanced by the load Mg / 4 (N) of the panel 9 against the load addition by the load adding means (Mg + Ft) / 4 (N Increase to / m2). As a result, each air spring 13 sufficiently supports the supported body because the air pressure P (N / m2) is high even if the supported body (that is, the surface plate 9 and the mounted device) vibrates in the Z direction. And the displacement can be kept small.

"Evaluation test"
Next, the inventors of the present application conducted an evaluation test of the vibration isolation device 1 according to the embodiment. Specifically, as shown in FIG. 6, when a square plate weight 47 is placed on one corner (the lower right corner in FIG. 6) on the surface plate 9, the corner of the surface plate 9. The displacement amount ΔZ (mm) of the sinking was measured. A displacement sensor (not shown) used for measuring the displacement amount ΔZ (mm) was installed in the air spring unit 7 disposed at the corner corresponding to the weight 47. The evaluation test was performed by changing the compression coil spring 45 of the clamp device 11. Specifically, the compression coil spring 45 having the same natural length and a spring constant of 80 (N / mm), 160 (N / mm), or 300 (N / mm) was used.

  The test results are shown in FIG. In the graph shown in FIG. 7, the vertical axis represents the displacement ΔZ (mm), and the horizontal axis represents the elapsed time (s) after the weight 47 is placed. In the graph, the solid line indicates the case where the compression coil spring 45 is not provided, the broken line indicates the case where the compression coil spring 45 having a spring constant k of 80 (N / mm) is provided, and the alternate long and short dash line indicates that the spring constant k is A case where the compression coil spring 45 having 160 (N / mm) is provided is shown, and a two-dot chain line shows a case where the compression coil spring 45 having a spring constant k of 300 (N / mm) is provided.

  As can be seen from the graph of FIG. 7, when the compression coil spring 45 is not provided, that is, when the load adding means is not provided, the displacement amount ΔZ (mm) into which the platen 9 sinks is the largest, 2.3 mm at the maximum. . On the other hand, when the compression coil spring 45 is provided, that is, when the load adding means is provided, the displacement ΔZ (mm) at which the surface plate 9 sinks is less than 1.1 mm at the maximum, and no load adding means is provided. Less than half. Therefore, it was found that the displacement of the surface plate 9 can be suppressed by providing the load adding means.

  Similarly, as can be seen from the graph of FIG. 7, it is found that the displacement amount ΔZ (mm) sinking into the surface plate 9 decreases as the spring constant k of the compression coil spring 45 increases. That is, as the spring constant k increases to 80 (N / mm), 160 (N / mm), and 300 (N / mm), the displacement ΔZ (mm) is 1.1 mm, 0.9 mm, and 0. It was as small as 7mm. This is because the force that the compression coil spring 45 pulls the platen 9 downward increases as the spring constant k increases, and the load acting on the air springs 13, 13,. This is because the air pressure P is increased.

  Further, the compression coil spring 45 is attached to the clamp device 11 in a pre-compressed state, but it is possible to adjust the tensile force downward of the surface plate 9 by appropriately adjusting the pre-compression amount. Become.

  FIG. 8 shows a precompression amount (deflection amount) ΔL (mm) at each spring constant k (N / mm) of the compression coil spring 45 and its elastic force, that is, tension that the compression coil spring 45 pulls the platen 9 downward. It is a graph which shows the relationship with force Fs (N). The vertical axis of the graph indicates the tensile force Fs (N), and the horizontal axis indicates the amount of deflection ΔL (mm). In the graph, the solid line, the broken line, and the alternate long and short dash line indicate the behavior of the compression coil spring 45 with spring constants k of 80 (N / mm), 160 (N / mm), and 300 (N / mm), respectively.

  As can be seen from FIG. 8, for example, when the amount of deflection ΔL is 3 mm, the tensile force Fs of the compression coil spring 45 with the spring constant k of 300 (N / mm) is the largest, 900 N, and the spring constant k is 160 (N / mm) and 80 (N / mm) in this order, the tensile force decreases to 480N and 240N. Therefore, at the same deflection amount ΔL (mm), the larger the spring constant k (N / mm), the greater the tensile force Fs (N). Therefore, for example, when the space between the base 5 and the surface plate 9 is small, by using the compression coil spring 45 having a large spring constant k (N / mm), the amount of deflection ΔL (mm) is relatively large. Even if it is small, the surface plate 9 can be pulled more strongly downward.

  On the other hand, for example, when the spring constant k is constant at 80 (N / mm), the tensile force Fs is 240 N when the deflection amount ΔL is 3 mm, and the tensile force is 480 N in the order of 6 mm and 11.25 mm. It becomes as large as 900N. Therefore, at the same spring constant k (N / mm), the larger the deflection amount ΔL (mm), the greater the tensile force Fs (N). Therefore, for example, when the space between the base 5 and the surface plate 9 is relatively large, a desired continuous tensile force can be obtained by appropriately adjusting the deflection amount ΔL (mm) of the compression coil spring 45. Fs (N) can be obtained.

  From the above, by setting the spring constant k (N / mm) and the deflection amount ΔL (mm) of the compression coil spring 45 in accordance with the constraints on the layout of the vibration isolator 1, the desired tensile force Fs (N) is set. Can be obtained.

-Effects of the embodiment of the invention-
According to the above embodiment, the load Ft is applied from the surface plate 9 to the air springs 13, 13,... By the load adding means, and the air of the air springs 13, 13,. The pressure P increases. Therefore, since the air pressure P of the air springs 13, 13,... Can resist the load on the spring, the displacement on the spring can be suppressed.

  Moreover, according to the said embodiment, since a load addition means is arrange | positioned between the surface plate 9 and the base 5, the change of the surface plate 9 on a spring is not required.

  As mentioned above, according to the said embodiment, the displacement on a spring can be suppressed by raising the air pressure P of the air springs 13, 13, ..., without changing on a spring.

  Further, according to the above embodiment, the load applying means has the compression coil spring 45 that pulls the surface plate 9 downward, and the spring constant k has a linear characteristic. Even if the length is changed by pulling 9, the natural frequency does not change, and the vibration isolation device 1 can maintain a stable vibration isolation performance.

  Furthermore, according to the embodiment, since the tension member is constituted by the relatively inexpensive compression coil spring 45 among the members having a linear spring constant, the manufacturing cost can be suppressed.

  Furthermore, according to the said embodiment, a load addition means can be comprised using the existing clamp apparatus 11. FIG. That is, when the vibration isolator 1 is transferred, the pair of upper and lower nuts 41 and 43 are brought close to each other, and the upper wall 41 a of the regulating member 35 is sandwiched and fixed by the upper nut 41 and the compression coil spring 45. While the movement of the surface plate 9 is restricted by restricting the vertical movement of the surface plate 9, when using the vibration isolator 1, the pair of upper and lower nuts 41, 43 are separated to release the pinching and fixing, thereby fixing the surface plate 9. Is allowed to move. When the vibration isolator 1 is used, the compression coil spring 45 urges the lower nut 43 downward, pulling the surface plate 9 downward, and from the surface plate 9 to the air springs 13, 13,. An acting load can be added.

In the above embodiment, the air springs 13, 13,... Are used as the gas springs. However, the present invention is not limited to this, and for example, a gas spring filled with nitrogen gas or the like can be used .

Also, in the above embodiment, although four disposed clamping device 11 is not limited to this, for example, it may be disposed over 1-3 group or 5 group.

  Furthermore, in the above-described embodiment, the compression coil springs 45 are disposed in all the four clamping devices 11, but the present invention is not limited to this. For example, the compression coil springs 45 are disposed in a pair of opposing clamping devices 11, 11. Also good.

  In addition, the air springs 13, 13,... May include a gimbal mechanism.

  As described above, the vibration isolator according to the present invention can be applied to applications that suppress displacement on a spring without changing the spring top.

1 Vibration isolation device 9 Surface plate 11 Clamp device 13 Air spring (gas spring)
35 Restriction member 35a Upper wall portion 35b Through hole 39 Bolt 41 Upper nut 43 Lower nut 45 Compression coil spring (tensile member)

Claims (1)

A vibration isolator comprising a plurality of gas springs that support a surface plate on which equipment is placed in a vertical direction with respect to the foundation,
It is disposed between the surface plate and the foundation, and includes a load applying means for applying a load downward to the surface plate ,
The load adding means has a linear spring constant, and has a tension member that pulls the surface plate downward,
The tension member is composed of a coil spring,
The load applying means is a clamp device that maintains a distance between the surface plate and the foundation,
The clamping device
A regulating member fixed to the foundation side and protruding upward;
A bolt extending downward from a position corresponding to the restriction member of the surface plate, and penetrating the upper wall portion of the restriction member;
A pair of nuts threadedly engaged with the bolts on the upper and lower sides of the upper wall, respectively;
It is arranged in a compressed state between the upper wall portion and the lower nut, surrounds the bolt, the upper end is fixed to the upper wall portion, and the lower nut is attached downward. The coil spring that pulls the surface plate downward,
The vibration isolation device , wherein the upper nut is separated from the upper wall portion .

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