JPH10317955A - Damping material and manufacture of damping material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a damping material capable of maintaining its damping property for a longer period and a productive manufacturing method of such a damping material with the reduced number of pressing processes. SOLUTION: A damping material comprises a first member 1, a second member 2 and a pellet material 3 interposed therebetween. The damping material is manufactured by applying adhesive 4 to either side of at least either of the first and the second members 1 and 2, overlapping the first and the second members 1 and 2 with the pellet material 3 held therebetween, and pressing the integrated members.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molded part capable of suppressing noise (hereinafter referred to as a vibration damping material) and a method for manufacturing the vibration damping material.

[0002]

2. Description of the Related Art An exhaust manifold made of a steel plate undergoes membrane vibration due to pulsation of exhaust gas, thereby producing noise. Therefore, a technology in which a heat insulator provided outside the exhaust manifold is provided with a ceramic fiber interposed between an outer plate and an inner plate to provide sound insulation so as to prevent noise from propagating is disclosed in, for example, Japanese Utility Model Application Publication No. 92
No. 422.

[0003]

SUMMARY OF THE INVENTION Since ceramic fibers are brittle in shape, they may be broken into small powders in a heat insulator due to exhaust vibration and may be scattered, and the vibration damping effect is maintained for a long time. In some cases, the noise prevention effect of the heat insulator cannot be obtained for a long time. Further, the conventional heat insulator is manufactured by press-molding each of the inner plate and the outer plate into a desired shape and then interposing ceramic fibers therebetween, so that many press working steps and press machines are required. An object of the present invention is to provide a vibration damping material that can maintain vibration damping properties for a long time, and a method for manufacturing a vibration damping material having high productivity and reduced press working steps.

[0004]

The present invention to achieve the above object is as follows. (1) A vibration damping material in which pellet materials (small pieces) are spread between the first member and the second member. (2) a step of applying an adhesive to one surface of at least one of the first member and the second member;
A method for producing a vibration damping material, comprising: a step of superimposing the above members via a pellet material; and a step of press molding.

[0005] The vibration damping material of (1) comprises a first member and a second member.
Pellets (spheres, columns, scales, etc.) that are less likely to break in shape than the fiber material are laid between the members, so that the vibration damping property can be kept long. In the method for manufacturing a vibration damping material according to the above (2), the first member and the second member are simultaneously pressed in a state where the pellet material is sandwiched between the first member and the second member, so that the desired shape is obtained. Thus, the first member and the second member do not have to be separately pressed, so that the number of pressing steps can be reduced. Also, since the adhesive is applied to one of the first member and the second member, when the first member and the second member are conveyed to the press in a state of being overlapped, and during press molding. In addition, the pellet material between the first member and the second member does not easily fall off.

[0006]

1 and 2 show a damping material according to an embodiment of the present invention, and FIG. 3 shows a method of manufacturing the damping material according to the embodiment of the present invention. In the following description, an example in which the damping material of the present invention and the method for manufacturing the damping material are applied to an exhaust manifold made of a steel plate for an internal combustion engine will be taken as an example, but not limited to the exhaust manifold, for example, provided outside the exhaust manifold. It can be applied to a heat insulator and the like.

As shown in FIGS. 1 and 2, the exhaust manifold is made of a steel plate, for example, a stainless steel inner tube 1.
(A first member) and an outer tube 2 (a second member). The inner tube 1 and the outer tube 2 have a gap of, for example, about 3 mm. Are spread all over. Preferably, the inner pipe 1 is provided with a plurality of holes communicating from the inner side, which is the exhaust passage, to the outer side with the pellet material 3. The shape of the pellet material 3 is substantially spherical or cylindrical.
Or, it is an arbitrary shape such as a scale. Desirably, the material of the pellet material 3 has heat resistance, and is made of, for example, cast iron or ceramics. The pellet material 3 can be obtained by manufacturing or by selecting an arbitrary shape from commercially available cast iron powder or ceramic powder. Desirably, the size of the pellet material 3 is 1 to 3 mm.

Next, the operation will be described. Since the pellet material 3 is located between the inner pipe 1 and the outer pipe 2, a plane (pellet material non-contact portion) where the membrane vibration of the inner pipe, which has been conventionally caused by the exhaust gas pulsation, becomes small, and the membrane vibration frequency becomes lower. As the frequency rises to a high frequency range, film vibration due to exhaust gas pulsation becomes difficult.
Further, even if there is vibration transmitted to the outer tube, the vibration frequency is in a high-frequency range deviating from the auditory zone, and does not become a factor for increasing noise. Then, at the contact surface between the inner tube 1 and the pellet material 3, the energy transmitted by the frictional phenomenon at the time of vibration suppresses the vibration that propagates to the outer tube, thereby reducing noise. In particular, in the case of a pellet material made of cast iron, the sound transmitted to the outer tube can be further reduced because the cast iron material itself has a high damping property. Unlike the fiber material, the pellet material 3 is hard to be broken, so that it does not break and scatter as powder, so that the effect of suppressing the propagation of sound from the inner tube to the outer tube can be maintained for a long time. In particular, if the pellets are 1 mm or more, the problem of cracking hardly occurs. However, pellets larger than 3 mm are not preferable because the gap between the inner tube and the outer tube becomes large, and the vibration damping property becomes poor. FIG. 4 shows the relationship between the engine speed and the radiation sound of the exhaust manifold. The solid line (a) shows a dashed line (b) in the case of an exhaust manifold composed of only the inner tube 1 and the outer tube 2.
In the case of the exhaust manifold in which the cast iron pellet material is spread between the inner pipe and the outer pipe of the embodiment of the present invention, the dotted line (c) indicates that the ceramic pellet material is spread between the inner pipe and the outer pipe of the embodiment of the present invention. In the case of the exhaust manifold shown in FIG. In the case of the exhaust manifold according to the embodiment of the present invention, b and c have smaller radiated sound than a in the case of the exhaust manifold including only the inner tube and the outer tube. In particular, in the case of an exhaust manifold in which cast iron pellets are laid between the inner pipe and the outer pipe, the effect of reducing the radiation noise of b is high. Although not shown in FIG. 4, a similar radiated sound level test was performed using an exhaust manifold in which ceramic fibers or steel wool was inserted between the inner tube and the outer tube. As a result, at the start of the test, in the case of the exhaust manifold of the embodiment of the present invention, the emission sound levels were almost the same as those of b and c. However, during the repetition of the test, the exhaust manifold in which the ceramic fibers were interposed was used. In this case, the ceramic fibers are cracked, the ceramic fibers fall off between the inner tube and the outer tube, and in the case of an exhaust manifold in which steel wool is inserted, the elasticity of the steel wool decreases due to thermal cycling. In the case of the exhaust manifold of the embodiment, the radiated sound may be larger than b and c, and in the case of the exhaust manifold including only the inner tube and the outer tube, the radiated sound may be larger than a. When the shape of the pellet material 3 is substantially spherical, the contact surface between the pellet material 3 and the inner tube 1 and the outer tube 2 is small, and the heat transfer coefficient is suppressed to be small. Therefore, the temperature of the exhaust gas flowing through the exhaust passage is suppressed from lowering, and the exhaust gas has a high effect of keeping the exhaust purification catalyst mounted downstream of the exhaust manifold at the activation temperature. The plurality of micro holes formed in the inner tube 1 can prevent abnormal deformation of the inner tube 1 and the outer tube 2 caused by volume expansion of air between the inner tube and the outer tube.

Next, a method for manufacturing a vibration damping material according to an embodiment of the present invention will be described by taking an exhaust manifold as an example. It should be noted that the present invention is also a method for manufacturing the exhaust manifold according to the embodiment of the present invention. As shown in FIG. 3, a method of manufacturing the exhaust manifold is as follows: a plurality of minute holes 5 are formed in a flat plate 1 ′ (first member) for the inner tube 1 (), and the flat plate 1 ′ and the outer tube 2 are formed.
The adhesive 4 is applied to both one surface of each of the two flat plates 2 '(the second member) or one surface of one of the flat plates, and the adhesive of the flat plate 1' or the flat plate 2 'to which the adhesive 4 is applied is applied. The pellet material 3 is arranged on the surface on which the adhesive 4 is applied (), and the flat plate 1 ′ and the flat plate 2 ′ are overlapped with the adhesive material 4 applied on the inner side via the pellet material 3 () and pressed. It is formed into a half-shaped member (), the ends of the inner tube and the outer tube of the half-shaped member are welded (), and the half-shaped member is combined to form an exhaust manifold having a circular cross section. Welding () consists of a process. Adhesive 4
Is preferably highly ductile. For example, a rubber-based adhesive is used. The shape of the pellet material 3 is an arbitrary shape such as a substantially spherical shape, a columnar shape, or a scale shape. In any case, when the flat plate 1 'and the flat plate 2' are pressed at the same time, their shapes do not hinder the deformation (formability) of the flat plate 1 'and the flat plate 2'. Desirably, the material of the pellet material 3 has heat resistance, and is made of, for example, cast iron or ceramics. The pellet material 3 can be obtained by manufacturing or by selecting an arbitrary shape from commercially available cast iron powder or ceramic powder. Desirably, the size of the pellet material 3 is 1 to 3 mm. When the engine is mounted and operated, the exhaust manifold becomes hot. The adhesive 4 is gasified when kept at a high temperature. For example, if the adhesive is a rubber-based adhesive, the adhesive is gasified by holding at about 500 ° C. for 10 minutes. The gasified material is the fine holes 5 of the first member 1.
Get out of.

Next, the operation will be described. The adhesive 4 fills the gap between the flat plate 1 'and the flat plate 2'. Pellet material 3
Is buried in the adhesive 4 or adhered to the flat plate 1 'or the flat plate 2', so that the flat plate 1 'and the flat plate 2' It does not fall out from between. The pellet material 3 buried in the adhesive 4 acts as a bearing between the flat plate 1 ′ and the flat plate 2 ′, and the adhesive 4 has high ductility. Even if there is a difference in the amount of deformation, the difference in the amount of deformation is absorbed, and the two flat plates can be press-formed simultaneously with the pellets interposed therebetween without generating press wrinkles in the R portion and the like. In particular, the pellet material 3 is 1 to
If it is 3 mm, it is easy to follow the deformation of the flat plates 1 ′ and 2 ′ when press-forming the flat plates 1 ′ and 2 ′, and it is easy to press-form the flat plates 1 ′ and 2 ′. In addition, even if the flat plates 1 ′ and 2 ′ are press-formed, the pellet material 3 is kept uniformly disposed between the flat plates 1 ′ and 2 ′ and is hardly unevenly distributed. Conventionally, the flat plates 1 'and 2' were separately pressed using different presses. However, according to the method of the embodiment of the present invention, the flat plates 1 'and 2' can be press-formed at the same time. can do. Also, the number of press machines can be reduced. When the exhaust manifold is maintained at a high temperature, the adhesive is gasified and discharged to the atmosphere through the minute holes 5 formed in the flat plate 1 'for the inner tube 1 through the exhaust passage of the engine.

[0011]

According to the vibration damping material of the first aspect, between the first member and the second member, there is provided a pellet material having a vibration damping property that is less likely to be broken in shape than a fiber shape such as ceramic fiber. Because it is laid, the vibration damping property can be maintained for a long time. According to the method for manufacturing a vibration damping material of the second aspect, the first member and the second member are simultaneously press-formed in a state where the pellet material is sandwiched between the first member and the second member, and the desired shape is obtained. Thus, the first member and the second member do not have to be separately pressed, so that the number of times of pressing can be reduced. In addition, since the adhesive is applied to one of the first member and the second member, the pellet material is moved between the first member and the second member during transportation to the press and during press molding. Hard to fall off.

[Brief description of the drawings]

FIG. 1 is a front view of an exhaust manifold according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a view showing a method of manufacturing an exhaust manifold according to an embodiment of the present invention in the order of steps.

FIG. 4 is a diagram showing a relationship between an engine speed and a radiation sound of an exhaust manifold.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 1st member 2 2nd member 3 Pellet material 4 Adhesive

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yuji Kono 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Automobile Co., Ltd. (72) Eiichi Higuchi 1 Tenno Takamachi Shinmachi, Toyota City, Aichi Prefecture Aisin Takaoka Corporation (72) Inventor Hisashi Miwa 1st Tenno, Takaokashinmachi, Toyota City, Aichi Prefecture Inside Aisin Takaoka Co., Ltd.

Claims (2)

[Claims] 1. A vibration damping material in which a pellet material is spread between a first member and a second member. A step of applying an adhesive to at least one surface of at least one of the first member and the second member; a step of superimposing the first member and the second member via a pellet material; Press forming, and a method for producing a vibration damping material.