JPS63107549A - Vibration damper - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is used in machine tools, home appliances, OA equipment such as printers, ships, automobiles, audio equipment, precision equipment, etc. to reduce vibration and noise. This relates to vibration damping bodies.

[Conventional technology]

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

Furthermore, as the number of high-precision devices mounted on ships and cars increases, damage to the devices due to vibrations from these moving objects has become a problem. On the other hand, from the aspect of the living environment, as office automation equipment has become 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 vibrations and noise, it is of course important to eliminate their sources, but in general, countermeasures are often not easy.6 Therefore, vibration control methods are needed to reduce the generated vibrations and noises. It has become. One known method is to use a viscoelastic material.

Conventional methods of damping vibration using viscoelastic materials aim to reduce vibration energy by deforming the viscoelastic material, but this method consists of a viscoelastic layer and a constraint layer (elastic layer) on the damped object. ) and the non-restricted type, which has only a viscoelastic layer.

A vibration damping mechanism using a viscoelastic material is characterized by deformation that occurs as the viscoelastic body vibrates. In other words, the damping mechanism based on each damping method is a constrained type, which mainly uses shear deformation, and a non-constrained type, which uses mainly expansion and contraction deformation depending on the elastic modulus of the viscoelastic layer. This is a vibration damping mechanism that mainly uses deformation in the thickness direction.

The damping performance obtained by the damping mechanism is different between the constrained type and the non-constrained type. In other words, although high damping performance can be obtained with constrained or non-constrained vibration damping mechanisms that mainly deal with shear deformation or thickness deformation, the usable frequency range is limited to the extent of shear deformation because the performance changes with frequency. In case of thickness deformation, it is limited to low frequency, and in case of thickness deformation, it is limited to high frequency. Furthermore, although a non-restrictive vibration damping mechanism mainly based on expansion/contraction deformation can obtain damping performance that is substantially constant with respect to frequency, it is difficult to obtain high damping performance.

[Problem that the invention seeks to solve]

As described above, conventional restraint type and non-restraint type vibration damping mechanisms have the disadvantage that it is difficult to obtain high vibration damping performance over a wide frequency range from low frequencies to high frequencies. For this reason, there was a troublesome problem in that the frequency characteristics of the target vibration had to be known in advance and a vibration damping method suitable for the characteristics had to be selected and used.The present invention solves the above problems, and The objective is to provide a vibration damper that achieves high allocation performance over a wide frequency range.

[Means for solving problems]

The present invention includes a first viscoelastic layer attached to a vibration damped body;
The vibration damping body is characterized by having a laminated structure of an elastic layer attached to the surface of the vibration damper and a second viscoelastic layer attached to the surface of the elastic layer.

[Effect]

The performance of a damping mechanism mainly based on shear deformation is generally expressed by the following equation.

2(1+N)X/Xopt ζ350°″ma” 1+2N-X/Xopt+ X/
Xopt) (1) G, 11
, Hl H,2.

From equation (1), the damping performance ζ is better as the loss coefficient η2 of the viscoelastic layer is larger and as the Young's modulus and thickness of the constraining layer (elastic layer) are larger. Desirably Young's modulus is 1011 dyn/
It is more than cJ. The damping performance ζ is frequency dependent (
ω) in the formula, effectively takes a maximum at low frequency (IK) (below Iz) and changes.

When thickness deformation is the main component, vibration damping performance is generally expressed by the following equation.

It is.

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

Here, ζwax: Maximum value fo of vibration damping performance obtained:
Frequency at which the damping performance is maximized According to formula (3), the damping property is better as the density of the viscoelastic layer attached to the damped body is higher, for example, 1.5 g/cc or more, and the loss coefficient η2 is larger. Since the frequency for vibration reduction is generally up to 1 kHz, f is 10 K H
It is desirable to set it to z or less. For this purpose, it is necessary that the elastic modulus E2 of the viscoelastic layer is zlO″dyn/cxl or less.

The damping body of the present invention includes a first viscoelastic layer attached to the damped body, an elastic layer attached to the first surface, and a second viscoelastic layer attached to the surface of the elastic layer. It consists of three layers.

Since the Young's modulus of the second viscoelastic layer is small and does not significantly affect the rigidity of the elastic layer, the combination of the first viscoelastic layer and the elastic layer creates a vibration damping mechanism mainly based on shear deformation. The characteristics in this case are given by equation (1).

In the second viscoelastic layer, a vibration damping mechanism mainly based on thickness deformation occurs. The characteristics in this case are calculated using the density ρ and Hl when the three-layer structure of the damped body, the first viscoelastic layer, and the elastic layer is considered as one damped body (2) It can be approximated by Eq.

Therefore, the overall vibration damping performance is a combination of the characteristics of the vibration damping mechanism of shear deformation and thickness deformation. In other words, great vibration damping performance can be obtained 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.

Reference numeral 1 designates a damped body, 2 a first viscoelastic layer, 3 an elastic layer (restraint layer), and 4 a second viscoelastic layer. The first viscoelastic layer 2 is attached to the damped body 1, the elastic layer 3 is attached to the first viscoelastic layer 2, and the second viscoelastic layer 4 is attached to the elastic layer 3.

The damped body 1 is an aluminum plate with a thickness of 5 m, the first viscoelastic layer 2 is a material with a thickness of 3ITEI+ having a loss coefficient of ~1, the elastic layer 3 is an aluminum plate with a thickness of 2 m, and the second viscoelastic layer 4 density 2
Figure 2 shows the damping performance when using a 5 mm thick material with a Young's modulus of 5 x 10" dyn/i and a loss coefficient of ~1. The horizontal axis represents the frequency, and the vertical axis represents the vibration damping performance as the critical damping. ratio(
%). Curve 5 shows the performance of the embodiment of the present invention, curve 6 shows the performance of the damping body without the second viscoelastic layer 4, and curve 7 shows the performance of the damping body using the second viscoelastic layer 4 alone. As is clear from Figure 2, which shows the performance of the vibration dampers attached to Figure 1, the vibration damper of the present invention (curve 5) has a wider frequency range than the conventional vibration damper (curves 6 and 7). It can be seen that it has high vibration damping performance in this range.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to realize a vibration damping body that has high vibration damping performance over a wide frequency range, and can be used to damp the vibrations of equipment that dislikes minute vibrations, thereby preventing damage and malfunctions, and at the same time reducing the environmental impact caused by noise. This has the effect of solving the problem of deterioration.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an embodiment of the vibration damper of the present invention. FIG. 2 is a diagram showing a comparison between the damping performance of the damping body of the present invention and the damping performance of a conventional damping body. 1... Vibration-damped body 2... First viscoelastic layer 3... Elastic layer 4... Second viscoelastic layer Patent applicant: NEC Corporation ~, Yumi Agent: Susumu Uchihara, patent attorney ...' Figure 1

Claims (1)

[Claims] (1) Lamination of a first viscoelastic layer affixed to a vibration-damped body, an elastic layer affixed to the surface of the first viscoelastic layer, and a second viscoelastic layer affixed to the surface of the elastic layer. A vibration damping body characterized by having a structure.