JPS62110041A - Vibration control body - Google Patents

Abstract

PURPOSE:To obtain a vibration control body having high vibration control characteristic in the wide range of frequency by forming the vibration control body by two kinds of viscoelastic layers different in elastic modulus. CONSTITUTION:The first viscoelastic layer 2 having a desired elastic modulus of 10<9>dyn/cm<2> or more is stuck to a vibration controlled body 1, whereby substantially constant vibration control action is caused to the frequency by the expansion deformation of the layer. The second viscoelastic layer 3 having elastic modulus smaller than that of the viscoelastic layer 2 is stuck to the surface of the viscoelastic layer 2, whereby high vibration control action is caused by the deformation of the thickness.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is applicable to office automation equipment such as machine tools, home appliances, printers, etc.
Used in ships, automobiles, audio equipment, precision equipment, etc. to reduce vibration and
This invention relates to a vibration damper that reduces noise.

[Conventional technology]

In the ultra-PN @ processing industry, including IC-LSI and optical communications, minute vibrations in factories have come to affect the quality of products.

Furthermore, as opportunities for using highly accurate equipment mounted on ships and cars increase, damage to the equipment due to imaging of these moving objects has become a problem. On the other hand, from the aspect of the living environment, as office automation equipment becomes more widespread in offices and homes, the deterioration of the environment due to the noise generated by these equipment has become a problem.

In order to suppress these vibrations and noises, it is important to eliminate their sources, but countermeasures are often not easy. Therefore, an allocation method using a viscoelastic material is required in order to reduce the imaging and noise generated.

Conventional vibration damping methods using viscoelastic materials reduce vibration energy by deforming the viscoelastic material, but there are two methods: a restraining type in which a viscoelastic layer and a restraining layer are provided on the damped body. A non-restricted type with only a viscoelastic layer was used. The vibration damping mechanism is characterized by the deformation that occurs as the viscoelastic body vibrates. The vibration damping @ structure that occurs in each vibration allocation method is a damping mechanism mainly based on shear deformation in the constrained type, and a damping mechanism mainly based on expansion and contraction deformation depending on the elastic modulus of the viscoelastic layer in the non-constrained type. It is a vibration damping mechanism that mainly uses deformation.

The allocation characteristics obtained by each damping mechanism are different.

Allocation mechanisms based mainly on shedding deformation and thickness deformation can achieve high allocation performance, but the usable frequency range is limited because the performance changes with frequency. Then, 1 for the frequency
Although it is possible to obtain damping performance that is constant at about 1, it is difficult to obtain high damping performance.

[Problem that the invention seeks to solve]

As described above, the conventional vibration damping mechanism has the drawback that it is difficult to obtain high vibration allocation performance over a wide frequency range from low frequencies to high frequencies. For this reason, there is a troublesome problem in that it is necessary to know the frequency percentage of the target vibration in advance and select and use a vibration damping method suitable for the characteristics.

The present invention is intended to solve the above-mentioned problems, and its purpose is to provide a vibration damping body that achieves high vibration damping characteristics over a wide frequency range.

[Failure to solve the problem]

The present invention provides a vibration damping device characterized in that a second viscoelastic layer having a smaller elastic modulus than the viscoelastic layer is attached to the surface of the first viscoelastic layer attached to the vibration damped body. It is the body.

[For production]

In the non-restrictive damping method, depending on the magnitude of the elastic modulus of the viscoelastic material used, there are two types of vibration damping mechanisms: one mainly based on expansion/contraction deformation, and the other based on thickness deformation.

When expansion and contraction deformation is the main component, the allocation performance is generally expressed by the following equation.

From equation (1), in order to increase the damping performance ζ, it is necessary to increase 1, the loss coefficient η2, the elastic constant E2, and the thickness h2. Also, since the damped body is generally made of metal such as iron or aluminum, the elastic modulus E is 10" to 10" dyr/
yys". Therefore, a certain amount of vibration damping property (ζ
= 0.1 ts), a material with an elastic modulus of "B 10'dyn/" or more is required for the viscoelastic layer.

When the main focus is thickness deformation, the allocation performance is generally expressed by the following equation.

It is.

From equation (2), it can be seen that the allocation characteristic ζ takes a maximum value and changes with frequency. The maximum values of the frequency and allocation characteristics in this case are expressed by the following equations.

According to equation (3), the damping characteristics are better as the weight of the viscoelastic layer attached to the damped object is larger and the loss coefficient η2 is larger. Since the frequency for vibration reduction is generally 10 kHz i, it is desirable that fo be 10 kHz or less. For this purpose, the elastic modulus E2 of the viscoelastic layer is ~10'
It is necessary that it is dyn/c- or less.

The vibration damping method of the present invention includes a first viscoelastic layer attached to a damped object and a second viscoelastic layer attached to the surface of the first viscoelastic body.

The elastic modulus of the first viscoelastic layer is effectively 10 dyn/cy.
``The elastic modulus of the second viscoelastic layer is 10 dyn/cf.
n'' or less. In this case, the first viscoelastic layer produces an allocation mechanism mainly based on expansion and contraction deformation, and the second viscoelastic layer produces a vibration damping mechanism mainly based on thickness deformation.The first viscoelastic layer The vibration damping performance is shown in (1), which is the same as when the viscoelastic layer is used alone.

This is because the second viscoelastic layer has a small elastic modulus and does not affect the expansion/contraction deformation of the first viscoelastic layer.

The damping performance of the second viscoelastic layer is calculated using equation (2), considering the first viscoelastic layer and the damped body as a new damped body.

Therefore, the overall allocation performance is a combination of performance mainly based on expansion/contraction deformation and performance mainly based on thickness deformation. In other words, it has great damping performance over a wide frequency range.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the damping body of the present invention. 1 is a damped body, 2 is a first viscoelastic body, and 3 is a second viscoelastic body.

The first viscoelastic layer is attached to the damped body l, and the second viscoelastic layer 3 is attached to the first viscoelastic layer. The elastic modulus is first viscoelastic layer 2>second viscoelastic layer 3. The damped body 1 is a steel plate with a thickness of 10 cm, and the first viscoelastic layer 2 is a 10 m thick iron plate.
A material with an elastic modulus of 10" to 10"dyn/ctn", a thickness of the second viscoelastic layer 3 with an elastic modulus of 10 to 10
FIG. 2 shows the breakage characteristics when using a dyn/secondary material. The horizontal axis represents the frequency, and the vertical axis represents the allocation performance in terms of critical damping ratio (function).Curve 4 represents the example of the present invention, and curve 5 represents the case where the first viscoelastic layer 2 is used alone. The allocation performance of the embodiment is high over a wide frequency range.

FIG. 3 shows a comparison of damping performance with conventional damping methods.

The song fi16 shows the performance of an allocation mechanism that mainly causes deformation, which does not occur with the restraint-type vibration damping method. The viscoelastic layer has an elastic modulus of ~1 at a thickness of 3 days.
0 dyn/α1, the restraining layer has a thickness of 3 cm and has high elasticity of ~10
12 dyn/am'' was used.Curves 7 and 8 show the performance of the vibration damping mechanism mainly based on expansion and contraction deformation and the vibration damping mechanism mainly based on thickness deformation, which occur in the non-constrained damping method.Curve 7 shows the performance of the vibration damping mechanism mainly based on thickness deformation. The viscoelastic layer has a thickness of 5 m and an elastic modulus of ~1
O7dyV'- was used. Curve 8 is mainly due to expansion/contraction deformation, and the viscoelastic layer has a thickness of 5 m and an elastic modulus of ~10"
dyn/- was used.

All of the above vibration-damped bodies were made of aluminum plates with a thickness of 5 mm.

Although the damping performance of curve 8, which is mainly caused by expansion and contraction, is smaller than the others, it shows a nearly constant value with respect to frequency. It can be seen that curves 6 and 7, which are mainly caused by shear deformation and thickness deformation, have great damping performance, but change greatly with respect to frequency.

〔Effect of the invention〕

As described above, the present invention has a structure in which a second viscoelastic layer having a smaller elastic modulus than the viscoelastic layer is pasted on the surface of the first viscoelastic layer pasted on the vibration damping object. By taking
This has the effect of making it possible to realize a vibration damping body that has great damping performance over a wide frequency range.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing an embodiment of the vibration damping body of the present invention, FIG. 2 is a diagram showing the allocation performance of the vibration damping method of the invention, and FIG. 3 is a diagram showing the allocation performance of the conventional vibration damping method. It is. DESCRIPTION OF SYMBOLS 1... Vibration-damped body, 2... First viscoelastic layer, 3...
Second viscoelastic layer.

Claims (2)

[Claims] (1) A second viscoelastic layer having a smaller elastic modulus than the first viscoelastic layer is attached to the surface of the first viscoelastic layer attached to the vibration damping object. Vibration damping body. (2) The elastic modulus of the first viscoelastic layer is 10^9dyn/
cm^2 or more, the elastic modulus of the second viscoelastic layer is 10^9dy
The damping body according to claim 1, wherein the vibration damping body is set to n/cm^2 or less.