JP2013117256A - Vibration isolation material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small, inexpensive and simple vibration isolation material that isolates a floor vibration or causes no machine vibration or the like to be transferred to a floor.SOLUTION: In a vibration isolation device, a pair of rubber elastic bodies 1, 2 is provided which surrounds a region corresponding to an outer diameter of a coil spring 20 other than a connection part at both end sides of the coil spring in an axial direction, and on which a pair of slits facing each other is formed which forms an island part corresponding the region thereinside. Further, the rubber elastic bodies 1, 2 are integrally fixed by a screw nut 3a penetrating the rubber elastic bodies 1, 2 at the island parts thereof and outside the slits while compressing the coil spring 20 between the island parts.

Description

  The present invention relates to a vibration isolation material for isolating a semiconductor manufacturing inspection apparatus, an electron microscope, an air compressor, a vacuum pump, a press machine, a precision instrument such as a piano, an industrial machine, an acoustic instrument, and the like.

  Anti-vibration rubber, coil springs, air springs, etc. are used as vibration isolation materials. Anti-vibration rubber consists of two elements, metal fittings and rubber, and is a vibration-damping material that is small, inexpensive, and widely used.

  Air springs have a soft spring action and excellent vibration isolation performance, but are not widely used because their structures are large, complex, and expensive.

  The coil spring has a soft spring action and has excellent vibration isolation performance similar to that of an air spring, but has a small damping capacity and a large mechanical amplitude when passing through the resonance point. Also, the convergence of the machine shake due to the external force of the machine operation becomes slow and difficult to use. For example, the convergence of mechanical shake due to manual operation of a microscope or stage operation of a semiconductor manufacturing inspection apparatus becomes slow, and problems such as work efficiency decrease occur. Mechanical vibration due to external force or stage movement is called impact response amplitude.

  The vibration transmissibility and impact response amplitude of the system supported by the vibration isolator shown in FIG. 6 are shown in FIGS. 7 and 8 are graphs showing the damping characteristics of the vibration damping material having a characteristic damping ability. a is a system having a small damping ability, b is a system having a damping ability which is usually widely used, and c is a system having a strong damping ability. The softer the spring action and the smaller the dynamic spring constant, the lower the natural frequency, the lower the vibration transmissibility, and the better the vibration isolation performance. The vibration transmissibility is a measure of vibration isolation performance, and the smaller this value, the more the vibration is cut off. The loss factor is a parameter indicating vibration damping. The larger the value, the smaller the resonance magnification when passing through the resonance point, and the faster the impact response converges.

Hereinafter, the vibration isolation action of the vibration isolation material will be described for the system shown in FIG. In the figure, Ma represents a supporting machine, D represents a vibration isolator, and Floor represents a floor. The vibration frequency of the supporting machine Ma or the floor floor frequency is f (Hz), the dynamic spring constant of the vibration isolation material is k _d , the static spring constant is k _s (N / M), and the loss factor of the vibration isolation material is η , Assuming that the support mass is m (kg), the natural frequency f _n (Hz) of the system, the dynamic magnification α, the vibration transmissibility Tr, the resonance magnification β, and the initial value of the impact response amplitude is z ₀ (M). The shock response amplitude z (M) is expressed by equations (1), (2), (3), (4), and (5), respectively. However, M in parentheses is meter. The initial value zo is obtained by storing the momentum of impact in the momentum of the entire machine.

The combined characteristics of coil spring and damping material are: a. Having a small damping capacity, b. Normal and widely used damping ability, c. Three types of representative characteristics of strong damping ability, with specific values for a, b, and c, and the characteristics expressed in decibels of vibration transmissibility are shown in FIG. Is shown in FIG.
a. Example of small damping capacity (small loss factor)
k _s = 11.4 (N / mm)
k _d = 14.8 (N / mm) (dynamic magnification α = 1.3)
Loss factor η = 0.03
b. Example of normal and widely used damping capacity (normal loss factor)
k _s = 11.4 (N / mm)
k _d = 18.2 (N / mm) (dynamic magnification α = 1.6)
Loss factor η = 0.16
c. Example of strong attenuation (large loss factor)
k _s = 11.4 (N / mm)
k _d = 28.5 (N / mm) (dynamic magnification α = 2.5)
Loss factor η = 0.33

The characteristics and general applications of the three types of attenuation capabilities a, b, and c in FIGS. 7 and 8 are as follows.
a. Example of small damping capacity (loss factor: η = 0.03)
This is a case where a natural rubber rubber viscoelastic body is used, and the friction and viscous resistance between molecules are small, and the dynamic magnification is about 1.3 times. Used for well-balanced rotating machines such as pumps. The natural frequency is small and the vibration-proof performance is good.
b. Example of normal and widely used high damping capacity (loss factor: η = 0.16)
High damping synthetic rubber is used. Used when the resonance magnification β is a problem in machines with large excitation force such as compressors, centrifuges, and vibratory conveyors. The dynamic magnification is around 1.6 times.
c. Example of strong damping ability (loss factor: η = 0.33)
A rubber viscoelastic body with a particularly strong damping capacity is used when convergence of mechanical shake becomes a problem, such as a semiconductor manufacturing inspection facility with a stage or a microscope with manual operation. The dynamic magnification is over 2 times.

  Various methods for adding a damping capability to a coil spring have been proposed. When the rubber viscoelastic body is used in the compression direction, the rubber viscoelastic body is compressed and the spring action becomes hard, and the vibration isolation performance is impaired. In addition, there are many methods in which a rubber cylinder is inserted between the upper and lower metal fittings to give vibration damping by friction, but there is a problem that the damping capacity varies. Japanese Patent Application Laid-Open No. 2004-147528 (Patent Document 1) requires a mechanism for canceling deformation in order to avoid an increase in spring constant due to a load, and the structure becomes complicated. Moreover, a dimension also becomes large. In Japanese Patent Application Laid-Open No. 2004-324654 (Patent Document 2), a damping material is used for bending deformation, but the structure is also complicated and the outer dimensions are increased.

JP 2004-147528 A JP 2004-324654 A

  An object of the present invention is to obtain a vibration isolating material having a minimum increase in dynamic magnification and consisting of minimum elements that add damping capability. According to the vibration isolator of the present invention, the plate-like rubber viscoelastic body is fitted into both ends of the coil spring, and the beam part is mainly bent and deformed, the dynamic magnification is suppressed, the natural frequency does not increase, A small vibration transmissibility is expected to be obtained.

  In order to achieve the above object, one vibration isolator according to an embodiment of the present invention includes a coil spring interposed between a pair of opposed rubber elastic plates in a compressed state, and an edge portion of the set of rubber elastic plates. And a central region having a similar shape to the outer shape including a region in contact with both ends of the coil springs of each rubber-like elastic plate; Along the outer peripheral area, a pair of slits facing each other is formed, and the outer peripheral area corresponding to the middle point of each slit is fixed with a screw nut, and the outer side of each slit of the rubber-like elastic plate is fixed. A beam portion that holds the central region against the elastic force of the coil spring is formed by an outer peripheral region.

  In another embodiment of the present invention, a pair of metal plates having a fitting portion for fitting an end portion of a coil spring on one side of a rectangular or square metal plate is arranged with the fitting portions facing each other. Each end of the metal plate is fitted with a strip-shaped rubber viscoelastic material in which both ends of the coil springs are fitted into the respective metal plates, and flat portions are formed on the upper and lower sides, and the slits are formed over the entire length leaving the coupling portions on the side surfaces. The upper and lower flat portions are attached to the opposing surfaces of each metal plate, and are expanded at the slit portion by the elastic force of the coil spring, and the elastic force of the rubber viscoelastic material It is characterized by applying tension to the rubber viscoelastic body.

The vibration isolator of the present invention has a moderate vibration damping capability according to the application, and is capable of vibration isolation of a machine of approximately 15 Hz or less, which is difficult to be vibration-isolated with a vibration-proof rubber. This is particularly remarkable when the supporting load is 100 kg or less. Moreover, it replaces the air spring which cannot be applied in terms of cost and space. Furthermore, the vibration isolator structure is simple and easy to use in terms of price and space.
In addition, the vibration isolation performance and impact response of the vibration isolation material may be adjusted after the machine trial operation, but in this embodiment, this work is easier than the vibration isolation rubber and the air spring.

  The rubber viscoelastic body placed around the coil spring suppresses the occurrence of buckling of the coil spring, and a higher spring height than the standard can be applied to the coil spring center diameter. it can.

It is a figure which shows the structure of Embodiment 1 of this invention. It is a figure which shows the rubber viscoelastic body of the vibration isolator which is a deformation | transformation of Embodiment 1 of this invention. 6 is a diagram illustrating a structure of Embodiment 2. FIG. It is a figure which shows the structure of the modification of Embodiment 2. FIG. 4 is a graph showing a vibration transmission rate in the vertical direction in Example 1; It is a figure which shows the system of a vibration isolator. It is a graph which shows the vibration transmissibility of a perpendicular direction in the system of the vibration isolator of FIG. It is a graph which shows the impact response of a perpendicular direction in the system of the vibration isolator of FIG. It is a figure which shows the structure used as the foundation of the vibration isolator of this invention. It is a figure explaining the method of calculating | requiring the vertical spring constant of the rubber viscoelastic body of FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 9 is a diagram showing a structural model that is the basis of the vibration damping material of the present invention, and FIG. 10 is a diagram for explaining a method for obtaining the vertical spring constant of the rubber viscoelastic body of the embodiment of FIG. The basic vertical spring constant is calculated using FIG. 9 and FIG. FIG. 9A is a plan view of the two rubber viscoelastic bodies 1 and 2, and FIG. 9B is a side view of the two rubber viscoelastic bodies 1 and 2. Two plate-like rubber viscoelastic bodies 1 having circular recesses into which the coil spring 20 is fitted in the center are arranged with the recesses facing each other, and both ends are fastened with screw nuts (3a, 3b). . A portion that is bent and sheared according to the displacement 2a is called a beam. In FIG. 9, there are four beams (11a, 11b, 12a, 12b) in two layers on the left and right and two layers on the upper and lower sides. FIG. 10 shows a portion of the rubber viscoelastic body shown in FIG.
As shown in FIGS. 9 and 10, a vertical load 2p acts to generate a displacement 2a. Therefore, the load acting on one beam is p, and the displacement is a. Find the relationship between displacement and force for one beam.
p: Dynamic load (N) acting on one beam out of the vertical load 2p acting on the vibration isolation material
k: Dynamic vertical spring constant of one beam (N / mm)
a: Dynamic deflection of the beam (mm)
a _s : Dynamic lateral deflection of the beam (mm)
a _c : Dynamic vertical deflection of the beam (mm)
p _s : Dynamic lateral force acting on one beam (N)
p _c : Dynamic longitudinal force acting on one beam (N)
k _s : Dynamic spring constant in the transverse direction of one beam (N / mm)
k _c : Longitudinal dynamic spring constant of one beam (N / mm)
θ: Beam angle η: Loss factor of vibration isolator η ₀ : Loss factor of rubber viscoelastic material itself
k ₀ : Static spring constant of coil spring (N / mm)
As shown in FIG. 10, the deflection a indicates the cos θ component of the beam horizontal deflection a _s and the vertical deflection a _c .
This is the sum of sin θ components.
The procedure for obtaining the spring constant k per beam is shown below.
a ＝ a _s cosθ + a _c sinθ
The lateral deflection a _s is a _s = p _s / k _s obtained by dividing the lateral load by the lateral spring constant,
The lateral deflection is a _c = p _c / k _c obtained by dividing the longitudinal load by the longitudinal spring constant.
Therefore
a ＝ (p _s / k _s ) cosθ + (p _c / k _c ) sinθ
According to FIG. 10, p _s is the cos θ component of p, and is the sin θ component of p.
a = (p / k _s ) cos ² θ + (p / k _c ) sin ² θ = p (cos ² θ / k _s + sin ² θ / k _c )
Therefore, the spring constant k of one beam is obtained as follows.
k = p / a = k _s k _c / (k _c cos ² θ + k _s sin ² θ) (6)

The longitudinal spring constant k _c of the beam is proportional to the beam cross-sectional area (where the beam width is b and the thickness is h) bh and the dynamic longitudinal elastic modulus E _ap and inversely proportional to the length L. E _ap is an apparent elastic coefficient obtained by adding a shape coefficient to the Young's modulus E of the rubber viscoelastic body itself. However, in the case of FIG. 10, since the length is larger than the cross-sectional area of the beam, E _ap is substantially equal to the dynamic longitudinal elastic modulus E as the material of the rubber viscoelastic body itself.
k _c = Ebh / L (7)
The lateral spring constant of the beam is
k _s = (Gbh / L) (1 + L ² / 3h ² ) ^-1 (8)
In FIG. 10, in the case of the present invention, since L ² / 3h ² > 7, 1 in parentheses is omitted.
k _s = 3Gbh ³ / L ³ (9)
Equation (9) indicates that the deformation in the transverse direction of the beam is mainly bending deformation, and k _s is determined by the soft bending deformation.
However, E: Dynamic longitudinal elastic modulus (N / mm ² ), G: Dynamic lateral elastic modulus (N / mm ² )
h: beam thickness (mm), b: beam width (mm), L: beam length (mm)
Here, the ratio k _s / k _c is obtained from the equations (7) and (9), and the following equation is obtained because E = 3G is substantially satisfied.
k _s / k _c = h ² / L ² (10)
Substituting equation (10) into equation (6), the beam one spring constant k is ^{_{k = k s / (cos 2}} θ + (h 2 L 2) sin 2 θ) = k s / (cos 2 θ (1+ (h ² / L ² ) sin ² θ / cos ² θ))
In FIG. 10, since L ² / 3h ² > 7 as described above, h ² / L ² <1/21
And since θ <35 °,
(h ² / L ² ) sin ² θ / cos ² θ << 1.
Therefore,

The spring constant K, dynamic magnification α, and loss factor η of the vibration isolator are obtained as follows.
K: Dynamic spring constant of vibration isolator
η: Loss factor of vibration isolation material η ₀ : Loss factor of viscoelastic body itself α: Spring constant dynamic magnification of vibration isolation material
k ₀ : As described above, static spring constant of coil spring (almost equal to dynamic spring constant)
k _st : Static spring constant of one beam
n: Number of beams on one stage on each side
1/2: 1/2 when the upper and lower beams overlap.
K = k × n × 1/2 + k ₀ (12)
η = (k × n × 1/2) η ₀ (k × n × 1/2 + k ₀ ) (13)
α = (k × n × 1/2 + k ₀ ) / (k _st × n × 1/2 + k ₀ )
Here, k _st is obtained by replacing the dynamic lateral elastic modulus G of the equation (11) with the static lateral elastic modulus G _st . In the high damping material of the present invention, k _st << k from G _st << G.
In the present invention, the dynamic spring constant of the beam is not significantly different from the spring constant k _{0 of the} coil spring. Therefore, k _st << k ₀ .
k _st × n × 1/2 << k ₀ has also been confirmed in actual measurement. Therefore α = 1 + (k × n × 1/2) / k ₀ (14)
The properties desired as a rubber viscoelastic body are that it has static elasticity capable of fitting a coil spring, has a small static motion ratio, and has a large damping capacity. As the damping capacity increases, the static / dynamic ratio also increases, the dynamic spring constant increases, and the vibration isolation performance tends to decrease.

According to the equation (11), the spring constant k of one beam is determined by the ratio h / L, the width b, and the angle θ, and the loss factor η of the vibration isolation material is determined by the equation (13). If the volume of the beam is small, the absolute value of intermolecular friction and viscous force in the viscoelastic body is small and the damping capacity is insufficient.
Therefore, the ratio (2bLh) × n / k ₀ (mm ⁴ / N) between the beam volume 2bLh and the spring constant k ₀ of the coil spring needs to be a certain value or more. According to the measurement of the example, on average, (2bLh × n) / k ₀ > 1000 is required.

When the resonance magnification β is set to 15 dB or less with high attenuation, the loss factor increases, but the dynamic magnification α also tends to increase. However, a material with a small magnification is desirable. Further, if the viscosity is excessively increased so as to increase the damping capacity, the molding process becomes difficult. There is a need for a rubber viscoelastic body that increases the viscosity and increases the loss factor while maintaining the necessary elasticity.
For vibration damping materials that require a resonance magnification β of 20 dB or more, natural rubber-based viscoelastic bodies are used. In this case, the dynamic magnification α is 1.3 times or less.

(Embodiment 1)
Based on the above analysis of the beam, the first embodiment of the present invention, as shown in FIG. 1, has two rubber viscoelastic bodies 1 and 2 of a rectangular vibration isolator stacked on top and bottom, and the center portions of both ends are screw nuts 3a. 3b shows a bundled state. FIG. 1A is a plan view, FIG. 1B is a side view, and FIG. 1C is a perspective view in a state where both ends of a coil spring are fitted.
The recesses 5 and 6 at the center of the rubber viscoelastic bodies 1 and 2 are recesses into which both ends of the coil spring are fitted. The upper concave portion 5 and the lower concave portion 6 are combined to fit both ends of the coil spring. Four U-shaped slits 8a, 8b, 9a, 9b are provided outside the concave portions 5, 6 of the rubber viscoelastic body to form beams 11a, 11b, 12a, 12b. The joint of the two rubber viscoelastic bodies 1 and 2 is opened, and a predetermined coil spring is inserted into the space 7 with a precompression force.
For the small size of the vibration isolator, the beam length before insertion of the coil spring is provided in a U shape, so that the substantial beam length can be gained. The dynamic spring constant k _d of the vibration isolator having a small magnification α can be obtained.

(Modification of Embodiment 1)
FIG. 2 is a modification of FIG. 1, (a) is a plan view of a rubber viscoelastic body, and (b) is a side view. The shape of the rubber viscoelastic bodies 1 and 2 is a disk shape. In FIG. 1, the slit has a U-shape, whereas in FIG. 2, it has an arc shape, but it does not change in the sense of increasing the beam length. In any case, with a small external dimension, when a supporting load is applied, the beam angle θ decreases and a soft spring constant can be obtained.

In the vibration isolator shown in FIGS. 1 and 2, in order to obtain stability of load support without buckling, the tilt angle of the beam exceeds 40 ° at the time of load support, and cos θ is It is desirable to set the H ratio of the center diameter D and the height of the coil spring, H / D, to 2 or less so as not to make it smaller.
When θ = 40 °, k becomes 1.7 times k _s as shown in the equation (11) and becomes hard. Further, the pre-compression force required when inserting the coil spring increases, and it takes time to insert the coil spring when assembling the vibration isolator.

(Embodiment 2)
FIG. 3 is a diagram showing an example of Embodiment 2 of the present invention. FIG. 3 (a) is a plan view, FIG. 3 (b) is a side view, and FIG. 3 (c) is a state where both ends of a coil spring are fitted. FIG.
One set of cross-shaped fittings (31, 32) provided with recesses (5a-5d, 6a-6d) into which four coil springs (20a-20d) are integrally molded with a rubber viscoelastic body are mutually coil springs. The four corners are fastened with four screw nuts (3a, 3b, 3c, 3d).
In this case, four coil springs are fitted in the center of the four corner screw screws, with four slits in the upper and lower rubber viscoelastic bodies, a total of eight (8a-8d, 9a-9d). It is provided so as to surround (20a to 20d).
A total of 16 beams of rubber viscoelastic bodies formed by hook-shaped slits are formed, with 8 (11a to 11h) in the upper part and 8 (12a to 12h) in the lower part. In FIG. 3, b1 to b16 indicate beams.
In the case of FIG. 3, the number of coil springs fitted in the center is four, but may be one or three. In the case of one, the ratio H / D between the height H of the coil spring and the center diameter D needs to be 2 or less in order to avoid buckling, but if the number of beams is as large as 16, the horizontal direction of the beam The restraining force is increased and the occurrence of buckling is suppressed. As a result, the ratio H / D between the height H of the coil spring and the center diameter D can be increased to 3.5.

  It is also possible to omit the screw nut 3 for fastening the upper and lower rubber viscoelastic bodies 1 and 2 in FIG. 3 and to integrally mold the rubber viscoelastic body as shown in FIG. In this case, the size of the vibration isolator can be reduced by the amount that there is no screw nut. 4A and 4B are diagrams showing an example of Embodiment 3 of the present invention. FIG. 4A is a plan view and FIG. 4B is a side view.

(Embodiment 3)
A pair of metal plates (31, 32) having recesses (5a to 5b, 6a to 6b) for fitting both ends of the coil springs to the respective slit portions are arranged facing each other, and the four coil springs (20a to 20d) are fitted. A metal part corresponding to the center part of each rubber viscoelastic body divided into two parts by providing a slit part that bisects in the thickness direction of the rubber viscoelastic body by four screw nuts (3a, 3b, 3c, 3d) Secure to the board.
The slit portion is spread by a coil spring and divided into two, and each of the two divided rubber viscoelastic bodies forms two upper and lower beams. In FIG. 4, four rubber viscoelastic bodies (2a to 2d) are arranged along the four sides of the metal plates (31, 32), but the two rubber viscoelastic bodies are arranged on two opposite sides. It is good also as a structure arrange | positioned along.
In this embodiment as well, this provides a vibration isolator having a structure in which a preload is applied to the coil spring and a pretension is applied to the upper and lower rubber beams formed by the slits.

Example 1
A vibration isolator having a maximum normal load of 10 kg of the coil spring to be housed was made and evaluated using the rubber viscoelastic body shown in FIG.
Beam thickness h = 6 mm, width b = 8 mm, length L = 33 mm. The outer diameter is 50 × 50 mm, the material properties of the rubber viscoelastic body are the dynamic and transverse elastic coefficient G = 10.9 (N / mm ² ), and the loss factor is 0.8.
Table 1 shows the spring constant K and loss factor of the vibration isolation material obtained from the equations (11) and (12), and the natural frequency and resonance magnification obtained from the equations (1) and (4).
The ratio of the volume of 8 beams to the spring constant of the coil spring is 2,539 (mm ⁴ / N).
FIG. 5 shows a measurement graph of the vibration transmissibility (vertical direction) of the vibration isolator at a supporting load of 10 kg.

(Example 2)
As in Example 1, with the structure shown in FIG. 1 and an outer diameter of 50 × 50 mm, the maximum normal load of the coil spring is 20 kg, the beam thickness is h = 7.5 mm, and the width and length are the same as in Example 1, and production evaluation is performed. did. The rubber viscoelastic material is the same as in Example 1.
Table 2 shows the characteristic values. The ratio of the volume of 8 beams to the spring constant of the coil spring is 1,389 mm ⁴ / N).

ゴム粘弾性体として天然ゴム系を使用した。引張強さなどの機械的強度は大きく、除振材の構成材としての機能に優れている。ロスファクタが小さく共振倍率は高いが、送風機、ポンプなどの回転機械は不平衡力が小さく、共振点通過時の振幅は小さい。
ゴム粘弾性体の水平方向のバネ作用により、コイルバネの座屈が抑制された結果、コイルバネの中心径16mmに対して高さ50mmのコイルバネが使用できた。柔らかいバネ定数が得られている。通常の設計標準であれば40mmが最大値である。製作評価の結果中心径に対して3.5倍までのコイルバネ高さが得られる。 (Example 3)
A vibration isolator as shown in FIG. 3 was manufactured and evaluated assuming the use of a blower or the like that does not require much suppression of the resonance magnification. The material of the rubber viscoelastic body is a natural rubber system.
Shape: Basic type 100 × 100 × 70 h
Dynamic transverse elastic modulus: 2.0 (N / mm ² )
Beam dimensions: b = 12 mm, h = 10 mm, L = 27 mm
Static spring constant of coil spring: 18.68 (N / mm) With 4 coil springs.
Inclination angle: 40 ° at 37.5kg load of one vibration isolator
The spring constant ratio between the volume of 16 beams and the coil spring is 2,775 (mm ⁴ / N).
Table 3 shows the characteristics of the vibration isolator: 37.5 kg applied to the one with the maximum normal load of 50 kg.

A natural rubber system was used as the rubber viscoelastic body. The mechanical strength such as tensile strength is large, and the function as a component of the vibration isolator is excellent. Although the loss factor is small and the resonance magnification is high, rotating machines such as blowers and pumps have a small unbalanced force and a small amplitude when passing through the resonance point.
As a result of suppressing the buckling of the coil spring by the horizontal spring action of the rubber viscoelastic body, a coil spring having a height of 50 mm could be used with respect to the center diameter of the coil spring of 16 mm. A soft spring constant is obtained. For normal design standards, 40mm is the maximum value. As a result of production evaluation, coil spring heights up to 3.5 times the center diameter can be obtained.

DESCRIPTION OF SYMBOLS 1, 2 ... Rubber viscoelastic body 3, 4 ... Screw nut 5, 6 ... Concave 7 ... Space 8 for fitting in both ends of a coil spring 8, 9 ... Slit 11, 12 ... Beam 20 ..Coil spring

Claims (6)

A coil spring is interposed in a compressed state between a pair of opposed rubber viscoelastic plates, and the edges of the rubber elastic plate are fixed to each other with a plurality of screw nuts to hold the coil spring in the compressed state. A vibration material,
A pair of slits are formed facing each other along the central region and the outer peripheral region of the rubber-like elastic plate including the regions in contact with both ends of the coil springs, and at the midpoint of each slit. Corresponding outer peripheral regions are each fixed with a screw nut, and a beam portion is formed by the outer peripheral region outside each slit of the rubber-like elastic plate to hold the central region against the elastic force of the coil spring. An anti-vibration material characterized by   2. The vibration isolator according to claim 1, wherein the beam portion outside the slit that imparts vibration damping to the coil spring is rectangular, square, circular, or the like, and has a structure that increases the length of the beam while suppressing external dimensions.   The vibration isolator according to claim 1 or 2, wherein the rubber viscoelastic body is integrally molded. A pair of metal plates having a fitting portion for fitting the end portion of the coil spring on one side of a rectangular or square metal plate is arranged with the fitting portions facing each other, and both ends of the coil spring are fitted into each metal plate. With
A strip-shaped rubber viscoelastic material having slits extending substantially along its entire length leaving flat joints on the sides and leaving the joints on the sides is disposed along each side of the metal plate, and the upper and lower flat parts are It is attached to the opposing surface of each metal plate, is expanded at the slit portion by the elastic force of the coil spring, and tension is applied to the rubber viscoelastic body by the elastic force of the rubber viscoelastic material. Anti-vibration material. When the width b, height h, and length L of each beam are set, the ratio of the spring constant (k ₀ ) of the coil spring to the volume bhL of each beam and the total volume of 2n of all beams {(bhL × 2n) / The vibration isolator according to any one of claims 1 to 4, wherein k ₀ } is 1,000 mm ⁴ / N or more.   The vibration isolator according to any one of claims 1 to 5, wherein the height is 2.5 times to 3.5 times the center diameter of the coil spring.

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