JPH0128700B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a composite steel pipe, and particularly to a composite steel pipe with excellent vibration absorption performance. In recent years, steel pipes have often been used as supports and shafts for machines and structures because of their ability to reduce weight and provide high rigidity. However, the supports and shafts of machines and structures have drawbacks such as the fact that when the machine or the like vibrates, the vibrations cause resonance and, as a result, they tend to generate noise. Moreover, the column is functionally firmly connected to the machine, etc., and it is functionally impossible to couple it to the machine, etc. via rubber or the like, that is, to prevent vibrations from being transmitted to the column. Measures that have been adopted so far to reduce the vibration of supports in machines, etc. include means to shift the resonant frequency of the steel pipes provided to the supports to a point different from the frequency of the vibration source; However, it is not possible to obtain practical effects on all machines. Furthermore, it is impossible to shift the resonance point out of the audible range, and a slight change in the resonance point causes problems such as resonance occurring at a new point. On the other hand, in the case of steel plates, many methods are known as means for imparting vibration energy absorption performance to the structural member itself. As one of these, it is widely known that a so-called Sanderch-type damping steel plate, in which a viscoelastic material with a high mechanical loss rate is sandwiched between two steel plates, has an extremely high vibration absorption performance. However, unlike the case of steel plates, a composite pipe with a structure in which a viscoelastic material 3 is sandwiched between an inner pipe 1 and an outer pipe 2 as shown in Fig. 1 by applying such a sandwich-shaped structure to a steel pipe is expensive. Vibration absorption performance cannot be obtained. The present invention was made as a result of many detailed experiments on this point, and found that extremely high vibration absorption performance can be obtained by making either the inner or outer tube of the composite tube have an opening in the longitudinal direction. I discovered that. That is, the composite steel pipe of the present invention with excellent vibration absorption performance uses a steel pipe as a base pipe, and has an intermediate layer of a viscoelastic material having a mechanical loss rate of 0.1 or more and adhesion to steel on the inner or outer surface of the base pipe. at least 1/ of
It is characterized in that a metal or hard plastic tube having a wall thickness of 5 or more, adhesive to the viscoelastic substance, and having an opening in the longitudinal direction is joined as a restraining tube. The present invention will be described in detail below with reference to Examples. FIG. 2 shows an embodiment of the composite steel pipe of the present invention, in which 2 is a steel pipe serving as a base pipe, and a viscoelastic substance 3 having adhesive properties with the steel pipe 2 forms an intermediate layer of the steel pipe 2. The inner tube 1 is provided on the inner surface, and an inner tube 1 made of metal or hard plastic that is adhesive to the viscoelastic substance is joined as a restraining tube. The inner tube 1 is provided with an opening 4 along its longitudinal direction, and the wall thickness of the inner tube 1 is at least 1/5 or more than that of the steel tube 2. The dimensions and shape of the restraint tube were chosen as described above for the following reasons. First, if the restraint tube has a simple double tube structure as shown in Fig. 1, the loss coefficient will be lower than that of a single tube even if the viscoelastic material 3 is provided as an intermediate layer.
The openings were created based on the knowledge that, while the loss coefficient is only about 10 times higher, if an opening is provided in the longitudinal direction of the constrained pipe, the loss coefficient becomes about 1000 times higher than that of a single pipe. Moreover, as in another embodiment shown in FIG. 3, the inner tube 1 may be used as the base tube and the outer tube 2 may be used as the restraining tube, with the opening 4 provided on the outside in the longitudinal direction, contrary to the embodiment shown in FIG. The effect remains the same in either of the embodiments shown in FIGS. 2 and 3. The material of the pipe used as the restraining pipe may be metal or hard plastic as long as it has adhesive properties with the viscoelastic substance. Metals include steel, aluminum, copper, etc., and hard plastics include hard vinyl chloride, acrylic, and methacrylic. , etc. can be used. Also, regarding the wall thickness of this constrained pipe, if it is at least 1/5 of the wall thickness of the steel pipe that is the base pipe, great vibration absorption performance can be obtained, but if the ratio to the wall thickness of the base pipe is less than this, vibration absorption will not be possible. Performance is decreasing. Therefore, the wall thickness of the restraint tube needs to be 1/5 or more. There is no particular upper limit to the thickness, but 1/1 is desirable in order to minimize weight increase and maximize the effect. Examples of viscoelastic substances used as the intermediate layer include plastic viscoelastic substances made of resins such as vinyl acetate, vinyl chloride, and acrylic, plasticizers, and pigments, and rubber-based substances made of polyisobutylene, polybutene, pigments, etc. A viscoelastic material that has adhesive properties with the inner and outer tubes and has a mechanical loss rate of 0.1 or more. Here, the mechanical loss rate η is a value defined from the logarithmic damping rate δ in damped vibration as η = δ/π, and this is set to 0.1 or more because the steel pipe using the viscoelastic material The loss coefficient of
This is because a value of 0.01 or more is a practically effective loss coefficient value, whereas a value less than 0.01 has no practical effect. Also, regarding the effect of the thickness of the viscoelastic material,
A sufficiently large loss coefficient can be obtained if the thickness is 20μ or more, and even if the thickness is further increased, the effect will not become much higher. The effect of the present invention is that shear deformation acts on the viscoelastic material in the intermediate layer when the pipe vibrates, whereas in the case of a pipe with no openings in the longitudinal direction, no shear deformation acts on the viscoelastic material. It seems to be for a reason. By having such a structure, when the composite steel pipe of the present invention is used as a support for a machine or a structure, it adds excellent vibration absorption performance to the steel pipe, and as a result, the steel pipe itself absorbs vibration energy. Vibration is reduced, making it possible to reduce noise and vibration of the structure, etc., and the industrial effect thereof is extremely large. Next, the effects of the present invention will be described in more detail with reference to Examples. Example: Table 1 shows the relationship between frequency and loss coefficient regarding the vibration absorption performance of various steel pipes.

【table】

[Table] In the same table, Nos. 1 to 6 are comparative examples; No. 1 is a conventional single pipe, No. 2 is a normal double pipe without an intermediate layer, and No. 3 and No. 4 are conventional double pipes. Composite steel pipes having the conventional configuration as shown in Figure 1, in such cases No. 3, No.
Even if a viscoelastic material is provided as an intermediate layer as in No. 4, the loss coefficient is only about 5 times and 9 times higher than that of a single tube or a normal double tube without an intermediate layer, respectively. On the other hand, No. 5 and No. 6 are composite steel pipes having the structure of the present invention as shown in Fig. 2.
An epoxy adhesive with a mechanical loss factor of 0.1 or less is used in the intermediate layer, and in this case, the loss coefficient of the composite steel pipe is 6 times that of a single pipe or a normal double pipe without an intermediate layer. It is only 11 times more expensive. On the other hand, Nos. 7 to 12 are all composite steel pipes of the present invention, and their loss coefficients are about the same as No. 1 or No. 2 single pipes or ordinary double pipes without an intermediate layer. 300 times to 2000 times, the loss factor is approximately 300 times to 2000 times, compared to No. 3 and 4 composite steel pipes as shown in Figure 1 or No. 5 and 6 composite steel pipes whose intermediate layer has a mechanical loss factor of 0.1 or less. It can be seen that the value is 50 to 300 times higher.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a conventional composite steel pipe having a viscoelastic material as an intermediate layer, and FIGS. 2 and 3 are sectional views showing embodiments of the composite steel pipe of the present invention. 1... Inner tube, 2... Outer tube, 3... Viscoelastic substance, 4... Opening.

Claims (1)

[Claims] 1 A steel pipe is used as a base pipe, and a viscoelastic material with a mechanical loss rate of 0.1 or more and adhesiveness to the steel pipe is used as an intermediate layer on the inner or outer surface of the pipe, and the wall thickness is at least 1/5 or more of the steel pipe. A composite steel pipe with excellent vibration absorption performance, characterized in that a metal or hard plastic pipe that is adhesive to a substance and has an opening in the longitudinal direction is joined as a restraining pipe.