Friction damper

Abstract

To provide a friction damper in which a decrease in frictional force due to frictional heat is less likely to occur.SOLUTION: A friction damper comprises: a pressure-welding plate laminate in which a plurality of pressure-welding plates are laminated and slide against each other to generate a frictional force between the plurality of pressure-welding plates; a bolt that passes through the pressure-welding plate laminate; a nut that screws into the bolt on the opposite side of a head of the bolt; a first disc spring set arranged between the pressure-welding plate laminate and one of the head or the nut; and a second disc spring set arranged between the pressure-welding plate laminate and the other of the head or the nut. The friction damper adjusts the frictional force by a spring load bearing force of the first disc spring set. A contact area of the second disc spring set with the pressure-welding plate laminate is larger than the contact area of the first disc spring set with the pressure-welding laminate.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a friction damper.

Background Art

[0002] Conventionally, for example, as in Patent Document 1, there is known a friction damper that consumes vibration energy due to an earthquake or wind by the frictional force (frictional resistance) between pressure plates that move relative to each other in a predetermined direction and slide with the relative movement, and suppresses the relative movement. In this friction damper, bolts are passed through the pressure plates that move relative to each other, a disc spring is provided on the bolt head side, and a nut is screwed onto the bolt to press the pressure plates against each other by the spring load bearing force of the disc spring. At this time, a flat washer is interposed on the nut side so that the spring load bearing force of the disc spring acts on a wider area of the pressure plate.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a friction damper such as that of Patent Document 1, since the force applied from the nut side to press the pressure plates against each other easily acts on a narrow area near the nut, high frictional heat is likely to be generated due to the concentrated load. Further, even if a flat washer is interposed on the nut side, although the inner peripheral side of the flat washer pressed by the nut transmits the spring load bearing force, the outer peripheral side of the flat washer pressed by the nut warps in a direction away from the pressure plate, making it difficult to transmit the spring load bearing force. For this reason, the area where the spring load bearing force is transmitted becomes a narrow area where the nut is in contact with the pressure plate, and since the load acts on the narrow area, the surface pressure increases, resulting in a problem that it is difficult to obtain a desired frictional force due to the generation of high frictional heat. An object of the present invention is to provide a friction damper in which a decrease in frictional force due to frictional heat is less likely to occur.

Means for Solving the Problems

[0005] To achieve such an object, the present invention provides a pressure contact plate laminate in which a plurality of pressure contact plates are stacked and slid relative to each other to generate a frictional force between the plurality of pressure contact plates, a bolt passing through the pressure contact plate laminate, a nut screwed with the bolt on the side opposite to the head of the bolt, a first disc spring set disposed between the pressure contact plate laminate and one of the head or the nut, a second disc spring set disposed between the pressure contact plate laminate and the other of the head or the nut, and a friction damper that adjusts the frictional force by the spring load bearing capacity of the first disc spring set, wherein the contact area of the second disc spring set with the pressure contact plate laminate is larger than the contact area of the first disc spring set with the pressure contact plate laminate. Other features of the present invention will be clarified by the description in this specification.

Advantages of the Invention

[0006] According to the present invention, it is possible to provide a friction damper in which a decrease in frictional force due to frictional heat is less likely to occur.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

DETAILED DESCRIPTION OF THE INVENTION

[0008] At least the following matters become clear from the description of this specification and the accompanying drawings. (Aspect 1) A pressure contact plate laminate in which a plurality of pressure contact plates are overlapped and slid with each other to generate a frictional force between the plurality of pressure contact plates, A bolt passing through the pressure contact plate laminate, A nut screwed with the bolt on the opposite side of the head of the bolt, A first disc spring set disposed between the pressure contact plate laminate and one of the head or the nut, A second disc spring set disposed between the pressure contact plate laminate and the other of the head or the nut, Comprising A friction damper that adjusts the frictional force by the spring load bearing capacity of the first disc spring set, A friction damper characterized in that the contact area of the second disc spring set with the pressure contact plate laminate is larger than the contact area of the first disc spring set with the pressure contact plate laminate.

[0009] Even if the disc spring is pressed and deformed to be substantially flat, the outer peripheral portion does not deform so as to float and warp like a flat washer. For this reason, by arranging the first disc spring set and the second disc spring set as in the friction damper of Aspect 1, it is possible to press the pressure contact plate laminate at a position away from the axis of the bolt.

[0010] Further, since the contact area of the pressing plate laminate with the second disc spring set is larger than the contact area of the pressing plate laminate with the first disc spring set, it is possible to disperse and act the spring load bearing force over a larger area. For this reason, since the concentration of the spring load bearing force locally is suppressed, it is possible to provide a friction damper in which the generation of frictional heat is suppressed and the decrease in frictional force due to frictional heat is less likely to occur.

[0011] (Aspect 2) The friction damper according to Aspect 1, further comprising a first washer disposed between the pressing plate laminate and one of the head or the nut, wherein the first disc spring set is disposed between the pressing plate laminate and the first washer.

[0012] According to the friction damper of Aspect 2, the first washer can press the first disc spring set, and the inner diameter and outer diameter of the disc spring can be increased, so that the spring load bearing force of the first disc spring can act on a wider area of the pressing plate laminate.

[0013] (Aspect 3) The friction damper according to Aspect 2, wherein the first washer has a flange that contacts one of the head or the nut, and a guide ring disposed inside the first disc spring set.

[0014] According to the friction damper of Aspect 3, the position of the first disc spring set can be easily fixed by the guide ring of the first washer. Further, the first disc spring set can be pressed against the pressing plate laminate by the flange of the first washer.

[0015] (Aspect 4) The friction damper according to Aspect 1, further comprising a second washer disposed between the pressing plate laminate and the other of the head or the nut, wherein the second disc spring set is disposed between the pressing plate laminate and the second washer.

[0016] According to the friction damper of Mode 4, the second washer can press the second disc spring set, and the inner diameter and outer diameter of the disc spring can be increased. Therefore, the spring load bearing capacity of the second disc spring can act on a wider area of the pressure contact plate laminate.

[0017] (Mode 5) The friction damper according to Mode 4, wherein the second washer has a flange that abuts against the other of the head or the nut, and a guide ring disposed inside the second disc spring set.

[0018] According to the friction damper of Mode 5, the position of the second disc spring set can be easily fixed by the guide ring of the second washer. Further, the second disc spring set can be pressed against the pressure contact plate laminate by the flange of the second washer.

[0019] (Mode 6) The friction damper according to Mode 1, wherein the contact region of the first disc spring set with the pressure contact plate laminate is the outer peripheral edge of the first disc spring set.

[0020] According to the friction damper of Mode 6, the contact region of the first disc spring set with the pressure contact plate laminate is the outer peripheral edge of the first disc spring set, that is, the outer peripheral edge of the disc spring is where the first disc spring set is in contact with the pressure contact plate laminate. Therefore, the first disc spring set is not deformed so that the entire surface is in contact with the pressure contact plate laminate. For this reason, the spring load bearing capacity of the first disc spring set can act on the outer peripheral edge of the first disc spring set, that is, at a position farther from the axis of the bolt, so that the spring load bearing capacity can act on a wider range.

[0021] (Mode 7) The friction damper according to Mode 1, wherein the contact region of the second disc spring set with the pressure contact plate laminate extends from the outer peripheral edge to the inner peripheral edge of the second disc spring set.

[0022] According to the friction damper of aspect 7, since the contact area of the second disc spring set with the pressure contact plate laminate extends from the outer peripheral edge to the inner peripheral edge of the second disc spring set, it is possible to surely increase the contact area with the pressure contact plate laminate of the second disc spring set compared to the case where only the outer peripheral edge is in contact. Therefore, it is possible to disperse and act the spring load bearing force.

[0023] (Aspect 8) The friction damper according to aspect 1, wherein the first disc spring set is a laminate of a predetermined number of disc springs, and the second disc spring set has a number of the disc springs less than the predetermined number.

[0024] According to the friction damper of aspect 8, since the second disc spring set has a number of disc springs less than that of the first disc spring set, when the nut is tightened, the second disc spring set starts to deform significantly earlier than the first disc spring set. Therefore, since the second disc spring set deforms and the contact area with the pressure contact plate laminate expands more than that of the first disc spring set, it is possible to make the contact area between the second disc spring set and the pressure contact plate laminate wider than the contact area between the first disc spring set and the pressure contact plate laminate.

[0025] (Aspect 9) The friction damper according to aspect 8, wherein the second disc spring set is a laminate of a plurality of the disc springs.

[0026] According to the friction damper of aspect 9, since the second disc spring set is a laminate of a plurality of disc springs, it is possible to improve the transmission efficiency of the spring load bearing force compared to the case where there is only one disc spring.

[0027] <<<This Embodiment>>> Hereinafter, a friction damper according to an embodiment of the present invention will be described with reference to the drawings. In the following description, the same or equivalent components, members, etc. shown in each drawing are denoted by the same reference numerals, and redundant descriptions may be omitted as appropriate. The friction damper 10 is incorporated, for example, in the brace 1a of the H-shaped steel of the column-beam frame 1 as shown in FIG. 1. The brace 1a has brace segments 2 and 3 that are divided at appropriate positions in the spanning direction with a predetermined interval therebetween, and the friction damper 10 is incorporated in the divided portion. The friction damper 10 suppresses the relative movement of the brace segments 2 and 3 in the spanning direction when an external force such as an earthquake occurs.

[0028] As shown in FIGS. 2 and 3, the friction damper 10 includes a first pressure plate 11 bolted to the web 2a of one brace segment 2, a second pressure plate 12 in which the web 3a of the other brace segment 3 is directly used, a high-strength bolt 20 passing through the first pressure plate 11 and the second pressure plate 12, a nut 21 screwed onto the high-strength bolt 20, a first washer 22 and a first disc spring set 23 disposed on the nut 21 side, and a second washer 24 and a second disc spring set 25 disposed on the head 20a side of the high-strength bolt 20.

[0029] A first through hole 11a is formed through the first pressure plate 11 in the plate thickness direction, and a second through hole 12a is formed through the second pressure plate 12 in the plate thickness direction. The first through hole 11a is a circular shape slightly larger than the diameter of the shaft portion 20b of the high-strength bolt 20, and the second through hole 12a is a long hole having a width wider than the inner diameter of the first through hole 11a and extending in the spanning direction. The first pressure plate 11 and the second pressure plate 12 are overlapped in the plate thickness direction, and the high-strength bolt 20 is inserted through the through holes 11a and 12a in a skewered manner, and the nut 21 is screwed onto the tip of the high-strength bolt 20.

[0030] Between the first pressure contact plate 11 and the nut 21, a first washer 22 through which the high-strength bolt 20 is inserted and a first disc spring set 23 are provided. The first washer 22 is positioned on the nut 21 side, and the first disc spring set 23 is positioned between the first washer 22 and the first pressure contact plate 11. The first disc spring set 23 is composed of six disc springs 26 stacked in parallel. The inner peripheral edge portion 26a side is arranged on the first washer 22 side, the outer peripheral edge portion 26b side is arranged on the first pressure contact plate 11 side, and the outer peripheral edge portion 26b is in contact with the first pressure contact plate 11.

[0031] Also, between the second pressure contact plate 12 and the head (hereinafter simply referred to as the head) 20a of the high-strength bolt 20, a second washer 24 through which the high-strength bolt 20 is inserted and a second disc spring set 25 are provided. The second washer 24 is positioned on the head 20a side, and the second disc spring set 25 is positioned between the second washer 24 and the second pressure contact plate 12. The second disc spring set 25 is composed of two disc springs 26 stacked in parallel, and is arranged such that the inner peripheral edge portion 26a side faces the second washer 24 side and the outer peripheral edge portion 26b side faces the second pressure contact plate 12 side.

[0032] The second washer 24 has a small annular portion 24a and a large annular portion 24b with different outer diameters connected in the thickness direction to form an integral body, and has a through-hole 24c in the center with an inner diameter slightly larger than the diameter of the shaft portion 20b of the high-strength bolt 20. The outer diameter of the small annular portion 24a is slightly smaller than the inner diameter of the disc spring 26, and the outer diameter of the large annular portion 24b is formed larger than the inner diameter of the disc spring 26. The second washer 24 is arranged such that the small annular portion 24a is arranged inside the inner peripheral edge portion 26a of the second disc spring set 25, and the large annular portion 24b is positioned between the head 20a and the second disc spring set 25 (in other words, in contact with the head 20a). Note that the small annular portion 24a of the second washer 24 corresponds to a guide ring, and the large annular portion 24b corresponds to a flange.

[0033] When the nut 21 is tightened, a pressing force acts between the first pressing plate 11 and the second pressing plate 12 due to the spring load-bearing capacity of the first disc spring set 23. And, in a state where a pressing force acts between the first pressing plate 11 and the second pressing plate 12, the first pressing plate 11 and the second pressing plate 12 are relatively movable while sliding on each other, and a frictional force corresponding to the pressing force is generated during sliding. This frictional force becomes the damping force of the vibration of the column-beam structure 1. Here, the overlapped first pressing plate 11 and second pressing plate 12 correspond to the pressing plate laminate 4 that overlaps a plurality of pressing plates, slides on each other, and generates a frictional force between the plurality of pressing plates.

[0034] When disc springs are stacked in the same direction, the load strength becomes higher compared to the characteristics of a single disc spring. Therefore, the friction damper 10 can adjust the frictional force by changing the number of the disc springs 26 that constitute the first disc spring set 23 and changing the amount of change with respect to the free height of the first disc spring set 23 when the nut 21 is tightened, thereby changing the spring load-bearing capacity of the first disc spring set 23.

[0035] Also, the first disc spring set 23 and the second disc spring set 25, whose spring load-bearing capacities change by tightening the nut 21 screwed onto the single high-strength bolt 20, each use the same disc spring 26 and have different numbers of overlaps. For this reason, when the nut 21 is tightened, the second disc spring set 25 with a smaller number of overlaps than the first disc spring set 23 changes in height more greatly than the first disc spring set 23.

[0036] At this time, as shown in FIGS. 4(a) and 4(b), the disc springs 26 of the second disc spring set 25 are elastically deformed so as to bend and approach the second pressing plate 12 from the outer peripheral edge portion 26b side in the overlapped state. When the nut 21 is continuously tightened to increase the spring load-bearing capacity of the first disc spring set 23, the contact region R where the disc springs 26 of the second disc spring set 25 contact the second pressing plate 12 expands from the outer peripheral edge portion 26b side toward the inner peripheral edge portion 26a side.

[0037] Therefore, when the nut 21 is tightened so that the spring load-bearing capacity of the first dish spring set 23 becomes a desired magnitude, the contact area S1 between the first dish spring set 23 of the first dish spring set 23 and the first pressure contact plate 11 is, as shown in Fig. 5(a), the outer peripheral edge 26b of the dish spring 26, whereas the contact area S2 between the second dish spring set 25 and the second pressure contact plate 12 has a wider width on the inner peripheral edge 26a side than the outer peripheral edge 26b of the dish spring 26, as shown in Fig. 5(b). That is, the contact area S2 between the second dish spring set 25 and the second pressure contact plate 12 becomes larger than the contact area S1 between the first dish spring set 23 and the first pressure contact plate 11, and the dish spring 26 of the second dish spring set 25 is deformed so as to become flat, and the entire region facing the second pressure contact plate 12 comes into contact with the second pressure contact plate 12.

[0038] When the dish spring 26 of the second dish spring set 25 is deformed into a flat state and comes into contact with the second pressure contact plate 12, the second pressure contact plate 12 is pressed in the contact region. That is, the second pressure contact plate 12 is pressed in the contact region extending from the outer peripheral edge 26b to the inner peripheral edge 26a of the dish spring 26 that comes into contact with the second pressure contact plate 12 in the second dish spring set 25.

[0039] Therefore, for example, as in the case where only a flat washer is provided between the second pressure contact plate and the head, the outer peripheral edge of the flat washer does not warp in a direction away from the second pressure contact plate, and the second pressure contact plate is not pressed only on the inner peripheral edge side of the flat washer with which the nut is in contact. Therefore, by pressing the second pressure contact plate 12 with the second dish spring set 25, the second pressure contact plate 12 can be pressed at a position farther from the high-strength bolt 20 than in the case of using a flat washer.

[0040] Further, by deforming the dish spring 26 of the second dish spring set 25 so as to become flat and increasing the contact area S2 between the second dish spring set 25 and the second pressure contact plate 12, it becomes possible to disperse and act the spring load-bearing capacity over a wider region to press the second pressure contact plate 12. Therefore, since the pressing force is difficult to concentrate and act in a narrow range, it is possible to suppress the frictional heat generated between the first pressure contact plate 11 and the second pressure contact plate 12 and prevent a decrease in the frictional force due to the generation of high frictional heat.

[0041] In addition, in the present embodiment, the first washer 22 is a flat washer, and the second washer 24 is a washer having a small annular portion 24a and a large annular portion 24b, but it is not limited thereto. For example, the first washer 22 may be a washer having a small annular portion and a large annular portion, and the second washer 24 may be a flat washer. Further, both the first washer 22 and the second washer 24 may be flat washers, or both may be washers having a small annular portion and a large annular portion.

[0042] <First Modification Example> FIG. 6 is a view showing a first modification example of the friction damper. The friction damper shown in FIG. 6 includes a first washer 22A and a second disc spring set 25A.

[0043] Note that the first washer 22 of the above-described embodiment has substantially the same size (outer diameter) as the nut 21 (see FIGS. 2 and 3). In this case, when measuring the height of the first disc spring set 23, it is measured at the end face on the nut 21 side of the first disc spring set 23. However, since the end face of the first disc spring set 23 is inclined as shown in FIG. 3 and the like, it is difficult to accurately measure the height.

[0044] Therefore, in the first modification example, a first washer 22A is provided between the nut 21 and the first disc spring set 23. As shown in FIG. 6, the first washer 22A has a larger size (outer diameter) than the nut 21. Thereby, the height can be measured at the portion of the first washer 22A protruding outward from the nut 21. Therefore, by subtracting the thickness of the first washer 22A from the measured value, the height of the first disc spring set 23A can be known. Therefore, it becomes easier to accurately measure the height of the first disc spring set 23.

[0045] Further, in this first modification example, only the second disc spring set 25A is disposed on the head 20a side of the high-strength bolt 20 (between the pressure contact plate laminate 4 and the head 20a).

[0046] The inner diameter of the disc spring of the second disc spring set 25A is slightly larger than the diameter of the shaft portion 20b of the high-strength bolt 20 and smaller than the diameter of the head portion 20a of the high-strength bolt 20. Thereby, the second disc spring set 25A can be pressed by the head portion 20a of the high-strength bolt 20. Therefore, since the second washer 24 used in the above-described embodiment can be omitted, the configuration of the friction damper can be simplified. In FIG. 6, the disc spring of the second disc spring set 25A and the disc spring of the first disc spring set 23 are substantially the same size, but they do not have to be the same size. Further, the configuration on the head portion 20a side may be the same as that in FIGS. 2 and 3, and the washer on the nut 21 side (here, the first washer 22A) may be omitted.

[0047] <Second Modified Example> FIG. 7 is a diagram showing a second modified example of the friction damper. In the second modified example, as shown in FIG. 7, only the second disc spring set 25A is disposed on the head portion 20a side (between the pressure contact plate laminate 4 and the head portion 20a) of the high-strength bolt 20, and only the first disc spring set 23 is disposed on the nut 21 side (between the pressure contact plate laminate 4 and the nut 21). That is, in the second modified example, the washers on both the head portion 20a side and the nut 21 side of the high-strength bolt 20 are omitted.

[0048] Also in the case of this second modified example, by providing disc spring sets (the first disc spring set 23 and the second disc spring set 25A) on both sides of the pressure contact plate laminate 4, it is possible to press the pressure contact plate laminate 4 at a position away from the shaft (shaft portion 20b) of the high-strength bolt 20. Further, in the second modified example, the configuration of the friction damper can be further simplified.

[0049] In the above embodiment, the example in which the pressure contact plate laminate 4 is composed of the first pressure contact plate 11 and the second pressure contact plate 12 has been described, but the present invention is not limited to this, and the pressure contact plate laminate 4 may be configured by overlapping three or more pressure contact plates. For example, as shown in FIG. 8, the pressure contact plate laminate may be composed of three pressure contact plates.

[0050] In this case, the friction damper 10 includes a first pressure plate 11 and a third pressure plate 13 bolted to the web 2a of one brace fragment 2, a second pressure plate 12 in which the web 3a of the other brace fragment 3 is directly reused, a high-strength bolt 20 passing through a pressure plate laminate 5 formed by overlapping the first pressure plate 11, the second pressure plate 12, and the third pressure plate 13, a nut 21 screwed onto the high-strength bolt 20, a first washer 22 and a first disc spring set 23 arranged on the nut 21 side, and a second washer 24 and a second disc spring set 25 arranged on the head 20a side. The nut 21 is tightened so that the disc spring 26 of the second disc spring set 25 is deformed to be flat, and the entire area of the portion facing the third pressure plate 13 abuts against the third pressure plate 13.

[0051] Also, as shown in FIG. 9, the pressure plate laminate may be composed of five pressure plates. In this case, the friction damper 10 includes a first pressure plate 11 and a third pressure plate 13 bolted to the web 2a of one brace fragment 2, a second pressure plate 12 in which the web 3a of the other brace fragment 3 is directly reused, a fourth pressure plate 14 and a fifth pressure plate 15 bolted to both surfaces of the web 3a via filler plates 6, a high-strength bolt 20 passing through a pressure plate laminate 7 formed by overlapping the first to fifth pressure plates 11, 12, 13, 14, and 15, a nut 21 screwed onto the high-strength bolt 20, a first washer 22 and a first disc spring set 23 arranged on the nut 21 side, and a second washer 24 and a second disc spring set 25 arranged on the head 20a side. The nut 21 is tightened so that the disc spring 26 of the second disc spring set 25 is deformed to be flat, and the entire area of the portion facing the fifth pressure plate 15 abuts against the fifth pressure plate 15. In the configurations of FIGS. 8 and 9, the above-described first modification example and second modification example can be similarly applied.

[0052] In the above embodiment, an example was described in which the first disc spring set 23 is composed of six disc springs 26, and the second disc spring set 25 is composed of two of the same disc springs 26 as the first disc spring set 23. However, the present invention is not limited to this. The number of disc springs 26 constituting each of the disc spring sets 23 and 25 may be such that the number of disc springs 26 constituting the first disc spring set 23 is more than the number of disc springs 26 constituting the second disc spring set 25. Also, the number of disc springs 26 constituting the second disc spring set 25 may be one.

[0053] Further, in the above embodiment, an example was described in which the first disc spring set 23 and the second disc spring set 25 are configured using the same disc springs 26. However, the present invention is not limited to this. Even a configuration in which the disc springs of the first disc spring set 23 and the disc springs of the second disc spring set 25 are different may be acceptable. In this case, the amount of deflection deformation with respect to the load in the second disc spring set 25 is set to be larger than the amount of deflection deformation with respect to the load in the first disc spring set 23.

[0054] Also, in the above embodiment, an example was described in which the first disc spring set 23 is arranged on the nut 21 side and the second disc spring set 25 is arranged on the head 20a side. However, the present invention is not limited to this. The first disc spring set 23 may be arranged on the head 20a side and the second disc spring set 25 may be arranged on the nut 21 side. ===Other Embodiments===

[0055] As described above, embodiments of the present invention have been explained. However, the above embodiments are for facilitating the understanding of the present invention and are not for limiting and interpreting the present invention. Also, the present invention can be changed and improved without departing from its gist, and it goes without saying that equivalents of the present invention are included.

Explanation of Reference Numerals

[0056] 1 Column-beam structure, 1a Brace, 2 Brace fragment, 2a Web, 3 Brace fragment, 3a Web, 4 Pressure welding plate laminate, 5 Pressure welding plate laminate, 6 Filler plate, 7 Welded plate laminate, 10 Friction damper, 11 First welded plate, 11a First through-hole, 12 Second welded plate, 12a Second through-hole, 13 Third welded plate, 14 Fourth welded plate, 15 Fifth welded plate, 20 High-strength bolt, 20a Head, 20b Shaft portion, 21 Nut, 22, 22A First washer, 23 First disc spring set, 24 Second washer, 24a Small annular portion, 24b Large annular portion, 24c Through-hole, 25, 25A Second disc spring set, 26a Inner peripheral edge portion, 26b Outer peripheral edge portion, R Contact region, S1 Contact area of the first disc spring set, S2 Contact area of the second disc spring set,

Claims

1. A friction damper comprising a laminated body of pressure contact plates that are overlapped and slid relative to each other to generate frictional force between the plurality of pressure contact plates, a bolt passing through the laminated body of pressure contact plates, a nut screwed with the bolt on the side opposite to the head of the bolt, a first disc spring set disposed between the laminated body of pressure contact plates and one of the head or the nut, a second disc spring set disposed between the laminated body of pressure contact plates and the other of the head or the nut, wherein the friction damper adjusts the frictional force by the spring load bearing capacity of the first disc spring set, and the contact area of the second disc spring set with the laminated body of pressure contact plates is larger than the contact area of the first disc spring set with the laminated body of pressure contact plates.

2. The friction damper according to claim 1, further comprising a first washer disposed between the laminated body of pressure contact plates and one of the head or the nut, wherein the first disc spring set is disposed between the laminated body of pressure contact plates and the first washer. This is the friction damper characterized by this.

3. The friction damper according to claim 2, wherein the first washer has a flange that contacts one of the head or the nut, and a guide ring disposed inside the first disc spring set. This is the friction damper characterized by this.

4. The friction damper according to claim 1, further comprising a second washer disposed between the laminated body of pressure contact plates and the other of the head or the nut, wherein the second disc spring set is disposed between the laminated body of pressure contact plates and the second washer. This is the friction damper characterized by this.

5. The friction damper according to claim 4, wherein the second washer has a flange that contacts the other of the head or the nut, and a guide ring disposed inside the second disc spring set. This is the friction damper characterized by this.

6. The friction damper according to claim 1, wherein the contact region of the first disc spring set with the laminated body of pressure contact plates is the outer peripheral edge of the first disc spring set.

7. The friction damper according to claim 1, wherein the contact region of the second disc spring set with the laminated body of pressure contact plates extends from the outer peripheral edge to the inner peripheral edge of the second disc spring set.

8. The friction damper according to claim 1, wherein the first disc spring set is a laminate of a predetermined number of disc springs. The friction damper is characterized in that the second disc spring set has a number of the disc springs less than the predetermined number.

9. The friction damper according to claim 8, wherein the second disc spring set is a laminate of a plurality of the disc springs.

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