JPH07100171B2 - Composite damping steel plate - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a composite steel sheet having a good vibration damping property in which two steel sheets are stacked and vibrations are absorbed by a frictional action of their contact surfaces.

(Prior Art) It is known that noise and vibration adversely affect human health in civil engineering construction machines, ships, and the like. Therefore, some damping materials have been developed conventionally.

Vibration-proof alloys include magnesium, Cu-Mn alloy, flake graphite cast iron, Fe-Cr-Al alloy, and 12% Cr steel. However, these vibration-damping alloys show good performance in the unloaded state, but once incorporated into a structure as a strength member, their vibration-damping effect disappears due to static load or residual stress due to welding. Often. In addition, the vibration-proof alloy has a drawback that it is expensive and difficult to weld.

The composite type vibration damping steel plate is a composite plate in which a polymer resin having viscoelasticity and a steel plate are combined. It is incorporated into a structure and has an effect, and is used for automobile parts and the like. However, it is very difficult to carry out welding, and the strength per unit area of the strength member deteriorates. In addition, the polymer resin cannot be used for structures that are harsh in the environment of use, such as ship decks or boiler flues, because they change over time.

(Problems to be Solved by the Invention) An object of the present invention is to obtain a vibration-damping steel sheet that is inexpensive and can withstand transportation, processing, and welding as a general industrial member without aging.

(Means for Solving Problems) The present invention solves the drawbacks of the above damping materials.
Although it is a composite type, it does not use a viscoelastic resin like the composite plate, but can exhibit a vibration damping effect by the contact friction between the steel plate surfaces, thus eliminating the drawbacks of the conventional composite type vibration damping steel plate.

The present invention is a composite vibration-damping steel plate in which two steel plates of the same kind are superposed, and the two superposed steel plates of the same kind are dispersedly arranged in a plane parallel to the plate surface, and each penetrates each plate. A composite vibration-damping steel plate is characterized in that it is integrally joined by spot welding at a plurality of points by a plurality of fine metal bodies having both ends fused to each plate.

As a result of an experiment, the present invention was divided into two steel plates, and the two steel plates were not completely restrained, but were dispersed and arranged in a plane parallel to the plate surface, each penetrating each plate and both ends thereof. We have found that it is possible to impart vibration damping property by mutual contact between steel plate surfaces by rejoining by spot welding fixation at multiple points by multiple micro metal bodies fused to each plate. .

That is, in order to join two superposed steel plates as described above, both ends of a bar or a pipe passed through each plate may be welded to each plate or embedded in a hole formed in each plate for welding. Alternatively, spot welding of the plates is performed, but it was found that such dot-like welding and fixing at multiple points is important for increasing the vibration damping effect without increasing the contact surface pressure of the two plates. It was If the contact surface pressure is large, the surfaces will not shift from each other, so the damping effect due to the sliding friction cannot be expected. On the other hand, if there is a gap between the plates without making contact with each other, there will be no sliding friction and, as a result, the damping effect will be lost.

The reason why the damping effect occurs when the contact surface pressure is not increased is as follows. That is, since the contact surface pressure on the surface of the plate is small, no constraint is exerted on the tangential direction of the surface, and a deviation occurs. At this time, the energy of the sliding friction, which is the product of the displacement of the sliding and the frictional force, is absorbed, so that the damping effect is obtained. The greatest damping effect due to shear friction of transverse waves. Further, the longitudinal wave is also superimposed and added on the transverse wave. At the plate interface, in the case of transverse waves, one side is in tensile stress, while in the other side, it is in compressive stress, whereas in the case of longitudinal waves, a phase difference occurs on both sides of the interface during propagation, and a sparse part There is a portion where the dense portion and the dense portion contact the interface, in which the stress of the tensile component is generated in the sparse portion and the compressive component is generated in the dense portion, and they cancel each other out through the friction of the interface. This phenomenon produces a longitudinal wave damping effect.

The shape of the welded part of the plate and the density of the welded part with respect to the plate area may be the following shapes and ratios as long as the contact surface pressure between the two plates is small and the contact surface is displaced.

An example of the structure of welding fixation is shown in FIG. 1 (a), (b) and (c). In either case, between the plates (1) and (1 '), the plates are in contact with each other at the periphery of the welded joint. (A) is one in which both ends of the bar (2) are connected to the plates (1) and (1 ') by the welded parts (3), and (b) is the hole formed in the plates (1) and (1'). The welding was carried out by the embedded welding (4), and (c) shows the plate (1) (1 ') joined by spot welding (5). And in (a), bar (2) becomes (b).
In (c), the weld metal becomes a fine metal body that penetrates the plates (1) and (1 ') and is bonded thereto.

In the case of such a welded fixed part structure, the contact surface pressure is high near the welded fixed part, but the contact surface pressure decreases as it goes to the middle of the welded fixed part and the adjacent welded fixed part. ing. Therefore, it has a vibration damping property.

The two plates can be structurally strong by providing a plurality of welding points. If these welding points are made too dense, they become the same as one plate, and the vibration damping property is lost. However, if they become too sparse, they will not differ from the two plates in practice and at least two welding points must be included.

From the standpoint of vibration control, it is appropriate that the welded area has a density of 20 or less per 1 m ² . At this time, although it depends on the mutual friction coefficient between the plate surfaces, the contact surface pressure required to cause the sliding friction for improving the vibration damping property is appropriately 15 kgf / cm ² or less. It was also desirable to remove the weld beads on the plate surface with a grinder finish.

(Embodiment, Action) Next, an embodiment of the present invention and its vibration damping action will be described.

Table 1 shows Nos. 1 and 2 of the present invention and No. 3 of Comparative Example, and shows their materials, plate dimensions, welding fixation, and vibration damping action. The steel plates used are all SM41.

Figure 2 (a) (b) shows the arrangement of welding points for Nos. 1 and 2.
Shown in. As shown in the figure, the welding points (a), (b), (c) ... were arranged on a plate with a width of 500 mm and a length of 1500 mm. As for the converted number of welding points, a, b, c, and d (4 points) are located at the center of the side edge of the plate, so it is 1/2, and f, g, t, c and r (4 points) are the corners of the plate. It is calculated as 1/4 because it is in the part, and e (1 place) because it is in the center. (B) When the figures are summed up, it becomes 1/2 × 4 + 1/4 × 4 + 1 = 4,
It is thought that it is distributed in the area of the plate 1.5 m × 0.5 m = 0.75 m ² , and the weld spot density is 4 / 0.75 m ² . For (b) figure, the same calculation gives 3 lines / 0.75 m ² . The location of any welded part satisfies the requirement of vibration damping of 20 or less per 1 m ² .

Nos. 1 to 3 were hit with a hammer to cause vibration, and the vibration damping effect was confirmed by the vibration peak sound pressure level.

FIG. 3 (a) (front view) (b) (side view) shows a method for measuring the peak sound pressure level of the plate. (B) The figure shows the situation where the plastic hammer (7) is vibrated by hitting the plastic hammer (7) to the center of the plate with an arm length of 200 mm and a lift angle of 30 °. It shows that it causes the vibration. FIG. 4 is a diagram showing how the sound pressure level of the vibration generated in the center of the plate changes with time. A peak of the sound pressure occurs immediately after striking, and the highest point (9) is the peak sound pressure level (end). From the whole to the edge).

As shown in Table 1, the peak sound pressure level is 95 to 96 dB in the invention examples No. 1 and 2, which is significantly lower than the 108 dB of the comparative example No. 3,
The damping effect was remarkable.

(Effects of the Invention) As described above, the composite vibration-damping steel plate of the present invention has a structure in which two steel plates are directly stacked and organic substances are excluded.
It is cheaper than anything else, moreover, it can be welded, and even if it is used for a structure under severe operating conditions such as a ship deck or a boiler flue, the vibration damping performance does not deteriorate. Furthermore, even if it is incorporated into a structure as a strength member and a static load or residual stress due to welding is applied, the deterioration of the vibration damping performance is small.

[Brief description of drawings]

FIG. 1 (a) is a cross-sectional structural view showing the state of welding at both ends of a bar, (b) is embedded welding, (c) is a spot welding, and FIG. 2 (a) (b) is the invention example No. 1, Fig. 3 (a) (front view) (b) (side view) is an explanatory view showing the peak sound pressure level measuring method of the plate, and Fig. 4 is a sound pressure level generation situation. FIG. 1: Steel plate, 2: Bar, 3: Weld, 4: Embedded weld, 5: Spot weld, 7: Hammer, 8: Node point, 9: Peak sound pressure level.

Claims (1)

[Claims] 1. A composite vibration-damping steel plate obtained by laminating two steel plates of the same kind, wherein two superposed steel plates of the same kind are dispersed and arranged in a plane parallel to the plate surface. A composite vibration-damping steel sheet, characterized in that it is joined and integrated by dot-like welding and fixing at a plurality of points by a plurality of fine metal bodies that penetrate and are fused at both ends to each plate.