JP4347273B2 - Isolation device, isolation base and isolation cart equipped with the isolation device - Google Patents

Description

  The present invention relates to a vibration isolation device, a vibration isolation rack including the vibration isolation device, and a vibration isolation cart.

  2. Description of the Related Art As a transportation carriage for precision parts such as wafers in a semiconductor factory, a transportation carriage provided with a vibration isolator is known so that precision parts such as wafers are not damaged by vibrations generated during acceleration / deceleration (see Patent Document 1).

JP 63-203464 A (FIG. 1)

However, the above-described transport cart has a spring element and a damping element as the basic configuration of the vibration isolator, and the problem is that the resonance point cannot be lengthened and the response to a long period of 1 Hz or less becomes large. is there.
On the other hand, as a technique for increasing the period of the resonance point, a technique for constructing a two-mass system by adding rotational inertia additional weight is known. However, there is a problem that even if the period can be increased by the two-mass point system, the response to high frequencies cannot be reduced.
In particular, when the semiconductor manufacturing equipment is disassembled into parts and transported by airplane, the above-mentioned two-mass system vibration isolator can sufficiently reduce the response to high-frequency vibration caused by impact during landing. However, there is a problem of causing damage to parts of the semiconductor manufacturing equipment.

  The present invention has been made in view of such circumstances, and it is possible to achieve a long period of the resonance point and to sufficiently reduce the response even for a high frequency input of, for example, 1 Hz or more. It is an object of the present invention to provide a device, a vibration isolation gantry equipped with the device, and a vibration isolation cart.

In order to solve the above-described problems, the vibration isolator of the present invention, the vibration isolation rack including the same, and the vibration isolation cart employ the following means.
That is, the vibration isolator according to the present invention includes a first spring element and a first damping element which are provided between two relatively displaced objects and are arranged in parallel, and are parallel to the first spring element and the first damping element. And a rotary inertia added mass that obtains an added mass by a rotary inertia moment obtained by converting the relative displacement into a rotary motion, and is connected in series to the rotary inertia added mass. An additional mass, a second spring element and a second damping element that are arranged in parallel to the additional mass in series and on the opposite side of the rotational inertia additional mass, and in parallel with the rotational inertia additional mass And a third spring element disposed on the surface.

By providing the second spring element and the second damping element in series with the rotational inertia added mass, the resonance point is lengthened and high-frequency vibration isolation is possible.
The “additional mass” of the present invention is distinguished from the “rotational inertia addition mass”, and the addition mass is the mass it has. For example, a significantly smaller mass, for example, a mass of about 0.5% is set with respect to the mass of the heavy object to be isolated.

  Furthermore, in the vibration isolator of the present invention, the second spring element and the second damping element are vibration-proof rubbers or viscoelastic bodies, the rotational inertia added mass is a disk, and the disk is a ball screw nut. It is fixed to a ball screw shaft that rotates with the displacement of the ball screw nut and is fixed to a ball screw nut that is screwed to the ball screw shaft and rotates with the displacement of the ball screw shaft. .

  Since the second spring element and the second damping element are made of vibration-proof rubber or a viscoelastic body and the rotary inertia added mass is a disk that rotates together with the ball screw shaft or the ball screw nut, the vibration isolator can be made compact.

  Moreover, the vibration isolator of the present invention includes a rack that supports an object, and any one of the above-described vibration isolator is provided.

  In addition, the vibration isolation cart according to the present invention includes a gantry that supports the object, and the gantry is provided with any of the above-described vibration isolation devices and traveling wheels.

  Since the second spring element and the second damping element are provided in series with the rotational inertia added mass, not only the period of the resonance point is lengthened but also the response to the high frequency input can be reduced.

Embodiments according to the present invention will be described below with reference to the drawings.
[First Embodiment]
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.
FIG. 1 (a) shows a vibration isolator 1 according to the present invention.
In the present embodiment, a vibration isolator 1 configured to support a heavy object 3 having a mass M1 on a base BS is shown.
The vibration isolator 1 has a first vibration isolation element I and a second vibration isolation element II arranged in parallel between the base BS and the heavy load 3.

  The first vibration isolation element I includes a first spring element 5 having a spring constant of K1 and a first damping element 6 having a damping coefficient of C1. A specific configuration example of the first vibration isolation element I is shown in FIG. That is, the first vibration isolation element I includes a first compression coil spring 15 corresponding to the first spring element 5 and a first oil that is disposed inside the first compression coil spring 15 and is erected on the substantially central axis thereof. And a damper 16. The first oil damper 16 corresponds to the first damping element 6 shown in FIG.

As shown in FIG. 1, the second vibration isolation element II is provided on the side of the first vibration isolation element I and includes an additional mass 8 having a mass M2. On one side of the additional mass 8 (downward in the figure), a second spring element 10 having a spring constant K2 and a second damping element 11 having a damping coefficient C2 are provided. Further, on the other side (upward in the figure) of the additional mass 8, a third spring element 13 having a spring constant K3 and a rotational inertia additional mass 14 are provided. The rotary inertia additional mass 14 is rotated by converting the relative displacement between the heavy object 3 and the base BS into a rotary motion, and a large equivalent additional mass is obtained by the rotary inertia moment due to the rotary motion. It is.
As described above, the second vibration isolation element II includes the additional mass 8, the second spring element 10, the second damping element 11, the third spring element 13, and the rotational inertia additional mass 14.

FIG. 3 shows a specific configuration example of the second vibration isolation element II.
That is, the second vibration isolation element II includes an anti-vibration rubber 20 disposed at the top, a connection flange 22 disposed below the anti-vibration rubber 20, and a third compression coil spring disposed below the connection flange 22. And a rotary inertia mass adding mechanism 25 provided inside the third compression coil spring 23.

  The anti-vibration rubber 20 is disposed between the lower surface of the heavy article 3 and the upper surface of the connection flange 22. This anti-vibration rubber 20 has a spring component and a damping component, and therefore corresponds to the second spring element 10 and the second damping element 11 shown in FIG. The spring constant K2 of the second spring element 10 and the damping coefficient C2 of the second damping element 11 are appropriately adjusted by changing the material, diameter, height, and the like of the vibration-proof rubber.

  Instead of the anti-vibration rubber 20, a viscoelastic body having a spring component and a damping component may be used similarly to the anti-vibration rubber. The viscoelastic body is used by adhering between the lower surface of the heavy object 3 and the steel plate meshed in a comb-like shape from the upper surface of the connection flange 22, and the spring constant K2 and the damping coefficient C2 are determined based on the bonding area and thickness. It adjusts suitably by changing.

  In FIG. 1, the second spring element 10 and the second damping element 11 are attached below the rotational inertia added mass 14, but the second spring element 10, the second damping element, and the rotary inertia added mass 14 The upper and lower positional relationship is not limited to this, and as shown in FIG. 2, the second spring element 10 and the anti-vibration rubber 20 as the second damping element 11 are arranged upward, and the rotary inertia mass adding mechanism 25 is arranged downward. May be.

The connection flange 22 connects the upper anti-vibration rubber 20 to the lower third compression coil spring 23 and the rotary inertia mass adding mechanism 25. The connection flange 22 has a mass corresponding to the additional mass 8 shown in FIG.
The connection flange 22 has three flanges, that is, an upper flange 22a, a middle flange 22b, and a lower flange 22c from the upper side to the lower side.

  The upper flange 22a is fixed to the flange 20a of the vibration isolating rubber 20 by a plurality of bolts 27a and nuts 27b.

  The middle flange 22b is integrally connected to the upper flange 22a by the first cylindrical portion 22d. The diameter of the middle flange 22b is made larger than the diameter of the upper flange 22a, so that a plurality of long bolts 29a arranged on the outer periphery of the middle flange 22b do not interfere with the upper flange 22a. Each long bolt 29a penetrates the middle flange 22b, and its lower end is fixed to the lower flange 22c.

The lower flange 22c has a larger diameter than the middle flange 22b. A hole 22c1 is formed at the center of the lower flange 22c, and a second cylindrical portion 22e connected to the lower surface of the intermediate flange 22b and extending downward is inserted into the hole 22c1. Therefore, a predetermined gap is formed between the outer periphery of the second cylindrical portion 22e and the inner peripheral edge forming the hole 22c1 of the lower flange 22c. The upper end of the third compression coil spring 23 is in contact with the lower surface of the lower flange 22c.
The distance between the lower flange 22c and the intermediate flange 22b can be arbitrarily changed. That is, the distance between the lower flange 22c and the intermediate flange 22b can be changed by changing the position of the retaining nut 29b that is positioned on the upper surface side of the intermediate flange 22b and screwed into the long bolt 29a.

  The third compression coil spring 23 is disposed between the lower surface of the lower flange 22c and the upper surface of the lower end flange 30 constituting the lower end of the second vibration isolation element II. The third compression coil spring 23 corresponds to the third spring element 13 of FIG. The initial spring force (initial biasing force) of the third compression coil spring 23 is adjusted by changing the distance between the middle flange 22b and the lower flange 22c.

The rotary inertia mass adding mechanism 25 is erected between the connection flange 22 and the lower end flange 30 and substantially on the central axis of the third compression coil spring 23.
In the present embodiment, the rotary inertia additional mass mechanism 25 is configured such that a ball screw nut 25a fixed to the connection flange 22 side, a ball screw shaft 25b, a disk 25c fixed to the ball screw shaft 25b, and a lower end of the ball screw shaft 25b are rotatable. The bearing 25d to support is provided.
The ball screw nut 25a is fixed to the upper flange 22a and the middle flange 22b of the connection flange 22, and the upper end of the ball screw shaft 25b is inserted into the ball screw nut 25a.
The ball screw shaft 25b is supported at both upper and lower ends by a ball screw nut 25a and a bearing 25b, and rotates around the central axis between them. That is, when the connection flange 22 moves up and down, a plurality of balls accommodated in the ball screw nut 25a roll on the screw groove 25b1 of the ball screw shaft 25b, thereby rotating the ball screw shaft 25b.
Since the disk 25c is fixed to the ball screw shaft 25b, it rotates as the ball screw shaft 25b rotates. The disk 25c corresponds to the rotational inertia added mass 14 shown in FIG.
As described above, the disk 25c rotates based on the displacement in the vertical direction of the connection flange 22, that is, the relative displacement between the foundation BS and the heavy load 3. A rotational inertia moment is obtained by this rotational motion, whereby an additional mass of equivalent additional mass ΔM as shown in the following equation can be obtained.
ΔM = 2m _p (πR / L) ² ... (1)
Here, _{m p} is the mass of the disk 25c, R is the radius of the disk 25c, L is the lead of the screw groove 25b1 provided on the ball screw shaft 25b.
Thus, even with a small mass m _p of the disk 25c, it is possible to obtain a large equivalent added mass △ M. For example, the diameter of the disk 25c 200 mm and a thickness of 30mm Weight _{m p} is 7.4kgf next, when 20mm lead L, equivalent added mass △ M is, 3648Kg, and the approximately 500 times the equivalent additional mass of the disk mass Can be obtained. Thus, the disk 25c has an advantage that the apparatus can be configured in a compact manner.

  In FIG. 3, the disk 25c fixed to the ball screw shaft 25b is configured to rotate. However, the disk 25c may be configured as follows. The ball screw shaft is installed so that the rotation around the axis is restricted while the displacement in the axial direction is allowed. The ball screw nut is provided so as to be screwed onto the ball screw shaft, and a disk is fixed to the ball screw nut. As a result, the ball screw nut and the disk rotate in accordance with the axial displacement of the ball screw shaft, and a rotational inertia added mass is obtained.

Next, the effect of the vibration isolator 1 according to the present embodiment will be described with reference to FIG.
FIG. 4 shows a simulation result of the vibration isolator 1 according to the present embodiment together with another comparative example. FIGS. 1B and 1C show the configuration of the comparative example.
In the vibration isolator A shown in FIG. 1B, the spring element 100 and the damping element 102 are arranged in parallel between the heavy article 3 and the base BS.
A vibration isolator B shown in FIG. 1C is obtained by adding a rotational inertia added mass 104 in parallel to the vibration isolator A shown in FIG.

The table below shows the mass M, the spring constant K, and the damping coefficient C given to the vibration isolator 1, A, B during the simulation.

In the above table, case A and case A ′ indicate the vibration isolator A, and case B indicates the vibration isolator B. The difference between Case A and Case A ′ is the magnitude of the first attenuation coefficient C1, and the attenuation coefficient of Case A ′ is three times that of Case A.
The mass of the heavy object 3 is the same 1 for all the vibration isolator 1, A, B (kg, cm, sec, or unit system that can be appropriately selected according to the target scale, such as ton, m, sec) did. The spring constant K1 of the first spring element is also set to 5 which is the same for all the vibration isolation devices 1, A and B. The first damping coefficient C1 was 0.45 for cases A and B and the present invention, and was 1.35 only for case A ′. The second attenuation coefficient of the present invention is 0.9. For easy comparison, the sum of the first attenuation coefficient and the second attenuation coefficient is made to coincide with the attenuation coefficient 1.35 of case A ′.

FIG. 4 shows the result obtained by performing the simulation under the above conditions. In FIG. 4, the horizontal axis represents the input frequency (Hz) and the vertical axis represents the absolute acceleration response magnification.
As can be seen from the comparison between cases A and A ′ and case B, the frequency of the resonance point is shifted to the low frequency side. That is, by adding the rotary inertia additional mass 104 to form a two-mass point system, the resonance point can be lengthened. However, Case B has a drawback in that the absolute acceleration response magnification becomes larger than other cases A and A ′ in a high frequency region of 1 Hz or more.
In the present invention, the resonance point is made longer than in the case B which is made longer, and the absolute acceleration response magnification is reduced to about ½. Furthermore, in the present invention, the acceleration response magnification at 1 Hz or higher is also greatly reduced. These are because the second spring element 10 and the second damping element 11 are connected in series to the additional mass 8 and the rotary inertia additional mass 14 after adding the additional mass 8. In particular, the parameters of the mass and spring constant may be set so that the resonance points of the heavy object 3, the additional mass 8 and the rotary inertia additional mass 14 are substantially matched. Specifically, each parameter may be set so that K1 / M1 = (K2 + K3) / (ΔM + M2).
Further, when comparing the present invention with case A ′ in which the attenuation coefficient is tripled with respect to case A, the response at the resonance point is slightly increased, but the resonance point is lengthened, and at 1 Hz or higher. The absolute acceleration is almost equivalent.
From the above, the vibration isolator 1 of the present invention has an effect that the response at a high frequency of 1 Hz or more can be reduced while realizing a long period of the resonance point.

  In addition, although the vibration isolator 1 concerning this embodiment was set as the structure which supports the heavy article 3 on base BS, this invention is not limited to this, For example, it provides between two objects which move relatively. It is good.

[Second Embodiment]
Next, a second embodiment of the present invention will be described with reference to FIG.
FIG. 5 shows a vibration isolation cart 50 according to an embodiment of the present invention. The vibration isolation cart 50 is a cart that places and conveys the conveyed product 4 on the top. The above-described first vibration isolation element I and second vibration isolation element II are used for the vibration isolation cart 50.
The vibration isolation cart 50 includes an outer frame 54 having a plurality of wheels 52 attached to a lower portion thereof, a horizontal vibration isolation frame 56 disposed inside the outer frame 54, and the horizontal vibration isolation frame 56 surrounded from above. And an upper and lower vibration isolation frame 58 disposed on the upper and lower sides.

The outer frame 54 is supported from below by a lower frame 54a assembled in a rectangular shape in plan view, a plurality of vertical bars 54b standing upward from the lower frame 54a, and the vertical bars 54b. An upper frame 54c having the same shape as 54a is provided. The lower frame 54a, the vertical bar 54b, and the upper frame 54c are fixed by welding.
Four wheels 52 are provided on the lower surface of the lower frame 54a. Further, two transverse members 54d are provided on the side of the lower frame 54a, and a plurality of horizontal sliders 54e are installed on the transverse members 54d. The horizontal slider 54e is slidable in the horizontal plane direction (xy direction). For example, the LM guide is arranged in each of the x direction and the y direction. The horizontal vibration isolation frame 56 is supported from below by the horizontal slider 54e.
A gripping portion 54f that can be gripped by an operator is fixed to both sides of the upper frame 54c.

As described above, the horizontal vibration isolation frame 56 is disposed on the inner side of the outer frame 54 and supported from below through a horizontal slider 54e so as to be movable in the horizontal direction.
The horizontal vibration isolation frame 56 has a configuration in which square bars are arranged on each side of the rectangular parallelepiped. A plurality of vibration isolation elements I and II are arranged between the outer side surface of the upper frame 56 c of the horizontal vibration isolation frame 56 and the inner side surface of the upper frame 54 c of the outer frame 54. That is, the second vibration isolation element II is provided at the center of the four sides of the upper frame 56c of the horizontal vibration isolation frame 56, and the first vibration isolation element I is provided at each corner of the upper frame 56c. . Accordingly, a total of four second vibration isolation elements II and eight first vibration isolation elements I are provided.
A horizontal link 60 is provided between the horizontal vibration isolation frame 56 and the vertical vibration isolation frame 58. With the horizontal link 60, the vertical vibration isolation frame 58 can move up and down while maintaining the horizontal direction with respect to the horizontal vibration isolation frame 56.

The upper and lower vibration isolation frame 58 is omitted from the lower frame member located on the side in FIG. 5, and thus has a portal shape when viewed from the side in FIG. 5. Accordingly, the upper and lower vibration isolation frame 58 is disposed so as to surround the horizontal vibration isolation frame 56 from above.
A plurality of vibration isolation elements I and II are provided between the lower surface of the upper frame 58 c of the vertical vibration isolation frame 58 and the upper surface of the upper frame 56 c of the horizontal vibration isolation frame 56.
That is, four first vibration isolation elements I are provided at the four corners, and two second vibration isolation elements II are provided below the projecting member 58d extending sideways from the upper frame 58c of the upper and lower vibration isolation frame 58. Is provided.

The vibration isolation cart 50 having the above configuration is used as follows.
When transporting a semiconductor manufacturing apparatus, the apparatus is divided into parts and transported for each part. Since each part is a precision part, there is a concern about damage due to vibration. Accordingly, each part is transported as a transported object 4 in a state where it is installed on the vibration isolation cart 50. The vibration isolation cart 50 on which the conveyed product 4 is placed is loaded on a truck or an airplane. Various vibrations occur during transportation on trucks and airplanes. In particular, in an airplane, an impact force is generated at the time of landing, and high-frequency vibration is input to the vibration isolation cart 50. Since the vibration isolation cart 50 is isolated in the horizontal and vertical directions by the first vibration isolation element I and the second vibration isolation element II, the response to high frequencies is greatly reduced (see the graph of FIG. 4). Therefore, the parts of the semiconductor manufacturing apparatus placed on the vibration isolation cart 50 are not damaged.
Moreover, since the resonance point of the vibration isolation bogie 50 is made longer by the first vibration isolation element I and the second vibration isolation element II (see the graph of FIG. 4), it is relatively slow in trucks and airplanes. Response to vibration is sufficiently reduced.
Further, as the rotary inertia additional mass 14 of the second vibration isolation element II, the disk 25c (see FIG. 3) that exhibits an equivalent additional mass several hundred times its own weight is used, so that the vibration isolation cart 50 is configured to be lightweight and compact. can do. Therefore, the cost during transportation is also reduced.

In the above embodiment, the vibration isolation cart 50 has been described. However, the wheel 52 of the vibration isolation cart 50 may be excluded and used as a vibration isolation frame.
In each of the above embodiments, the first vibration isolation element I is used as the configuration for realizing the first spring element 5 and the first damping element 6, and the rotational inertia additional mass 14, the additional mass 8, the second spring element 10, the second As the configuration for realizing the damping element 11 and the third spring element 13, the second vibration isolation element II is configured as two vibration isolation elements. However, the present invention is not limited to this, and each element is integrated into one. It may be configured as one unit, or may be configured as separate elements.

The vibration model of a vibration isolator is shown, (a) shows this invention, (b) and (c) shows a comparative example. It is the perspective view which showed the 1st vibration isolation element of this invention. It is the perspective view which showed the 2nd vibration isolator of this invention. It is the graph which showed the simulation result of this invention with the comparative example. It is the perspective view which showed one Embodiment of the vibration isolation trolley | bogie of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Isolation device 5 1st spring element 6 1st damping element 8 Additional mass 10 2nd spring element 11 2nd damping element 13 3rd spring element 14 Rotation inertia additional mass 50 Isolation cart

Claims (4)

A first spring element and a first damping element provided between two relatively displaced objects and arranged in parallel;
A rotary inertia additional mass that is arranged in parallel to the first spring element and the first damping element and obtains an additional mass by a rotary inertia moment obtained by converting the relative displacement into a rotary motion,
An additional mass connected in series to the rotational inertial additional mass;
A second spring element and a second damping element arranged in series with and in parallel to the additional mass and on the opposite side of the rotary inertia additional mass;
A third spring element disposed in parallel with the rotational inertia added mass;
A vibration isolator characterized by comprising: The second spring element and the second damping element are anti-vibration rubber or viscoelastic body,
The rotational inertia added mass is a disk,
The disk is screwed to a ball screw nut and fixed to a ball screw shaft that rotates with displacement of the ball screw nut, or is screwed to the ball screw shaft and fixed to a ball screw nut that rotates with displacement of the ball screw shaft. The vibration isolator according to claim 1, wherein It has a gantry to support the object,
A vibration isolator according to claim 1 or 2, wherein the vibration isolator is provided on the stand. It has a gantry to support the object,
The vibration isolation cart according to claim 1 or 2, wherein the frame is provided with a vibration isolation device and a traveling wheel.

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