JPS63254242A - Multilayered coil spring - Google Patents

Abstract

PURPOSE:To obtain the load supporting performance over a certain value per unit installation area without increasing the close adhesion stress by winding at least two wire materials in concentric and multilayered form in the same winding direction and setting the coil diameter of the wire material so that each wire material is superposed in the axial direction. CONSTITUTION:Coil springs 1 and 2 in double winding form are formed by winding two wire materials having an equal wire diameter in concentric form in the same winding direction into an equal coil diameter, together with an upper flange 3 and a lower flange 4. Therefore, the load supporting performance over a certain value per unit installation area can be obtained without increasing the wire diameter and increasing the close adhesion stress, even if the rigidity ratio between the shaft and the direction perpendicular to the shaft is reduced, and a suitable coil spring for a vibrationproof device can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present device relates to a seismic isolation device, and is suitable for vertical seismic isolation or three-dimensional seismic isolation of a heavy object such as a nuclear reactor.

[Conventional technology]

The needs for seismic isolation devices suitable for vertical seismic isolation or three-dimensional seismic isolation are wide-ranging, including nuclear reactors, computers, semiconductor manufacturing equipment, and nuclear fuel enrichment equipment. In particular, nuclear reactors (fast breeder reactors)
This is a nuclear reactor that has the potential for significant rationalization through seismic isolation. However, a nuclear reactor is a heavy object weighing as much as 8,000 tons, and the seismic isolation device must support at least about 100 tons of load per unit installation area, as will be described later.

Laminated rubber of about 200 h/m2 is considered as a horizontal seismic isolation device, but there is currently no available vertical or three-dimensional seismic isolation device. The use of coil springs in this seismic isolation device is being considered.

Conventionally, coil springs have been discussed, for example, in "Mechanical Design Handbook, Complete Edition of Mechanical Design Handbook Editorial Committee," Maruzen Co., Ltd., 12, Springs and Vibration Isolation Rubber, pp. 1235-1264. teeth,
It is determined by the wire diameter and the coil diameter, and the supported load is proportional to the cube of the wire diameter and inversely proportional to the coil diameter. Therefore, it is effective to increase the supporting load by increasing the wire diameter and decreasing the coil diameter. However, from the viewpoint of manufacturability, there is a limit to increasing the wire diameter and reducing the coil diameter, and the maximum wire diameter that can be manufactured is about 100 mm. In addition, the minimum coil diameter limit is 3.3 of the wire diameter.
In other words, in the case of a wire diameter of 100 mm, the average diameter of the coil needs to be about 330 mm.

Next, the rigidity of the coil spring will be described. Generally, the axial stiffness KV of a coil spring is given by: ((B, L, α: constant, d: wire diameter, D:
(coil diameter, N: effective number of turns) Therefore, the axial stiffness KV of a coil spring is determined by the wire diameter d, the coil diameter D, and the effective number of turns N, and is proportional to the fourth power of the wire diameter d, and is proportional to the cube of the coil diameter. is inversely proportional to the effective winding N. The stiffness KH of the coil spring in the direction perpendicular to the axis is given by: KH=Rc-KV Rc=f (D, Lo). (However, Lo: Natural length of coil spring)
In this way, KH is the axial stiffness KV and the natural length L of the coil.
It is known that the higher the axial stiffness KV is, the higher the stiffness is, and the longer the natural length LO of the coil is, the lower the stiffness is.

On the other hand, as a three-dimensional seismic isolation device, the rigidity in the axis perpendicular direction K H
The smaller the ratio K)I/KV of the axial stiffness KV and the axial stiffness KV, the more convenient the rotational vibration of the seismically isolated structure is suppressed. However, it could not be made too small, so the inventor decided to reduce the axial natural frequency fv to 2H when the rated load is applied.
z, aiming for the axis-perpendicular direction natural frequency fH to be 1Hz or less,
When designing a coil spring, if the maximum wire diameter is 100 mm and the minimum average coil diameter is 330 mm, the effective number of turns N must be 7, the coil free length Lo must be approximately 1100 mm, the supporting load is 24 tons, and the minimum coil diameter per unit installation area is approximately 1,100 mm. The supporting load is approximately 86 tons, which is 100 tons of the target supporting load.
Not enough for a ton.

Conversely, if a spring with a supporting load of 100 tons/m2 or more is designed with the goal of having a natural frequency of 2 Hz in the axial direction and a natural frequency of I Hz in the direction perpendicular to the axis when loaded with the rated load,
A wire diameter of 125 mm, an average coil diameter of 410 mm, an effective winding N of 5.7, and a coil free length Lo of about 1400 mm are required, but as mentioned above, it is extremely difficult to manufacture a wire diameter of 125 mm, and the manufacturing results are limited. Of course not. Furthermore, even if a spring with a wire diameter of 125 mm were manufactured, the adhesion stress (the stress generated when the coil is compressed until it is tightly attached) is extremely high, reaching 140 kg/mm2 (the tension of the spring material For example, the strength is 5UPIIA and 12
(approximately 5 kg/mm2) Not desirable (it is customary to design so that the adhesion stress is smaller than the tensile strength)
. Therefore, it is difficult to achieve the above goal with a coil spring made of a single wire.

Next, as a plan to increase load bearing capacity.

A multi-turn coil shown in FIG. 5 can be considered. This is a system in which two coil springs 1 and 2 with different coil diameters are arranged concentrically, and the outer diameter of the inner coil 2 is smaller than the inner diameter of the outer coil 1. A coil 2 is arranged. In this case, if the outer coil 1 is, for example, a coil spring with the maximum wire diameter of 100+nrrl and the minimum coil average diameter of 330 mm,
The empty space inside is a cylindrical space with a diameter of 230 mm. When designing a coil spring 2 that can be installed in this space, it is impossible to design it under the conditions that the natural frequency in the axial direction is 2 Hz or less and the natural frequency in the axis perpendicular direction is I Hz or less when the rated load is applied. Examples of double coils that can be designed include:
The outer coil has a maximum wire diameter of 100 mm, the average coil diameter is slightly thicker L400 mm, the inner coil wire diameter is 50 mm, and the average coil diameter is about 200 mm. In this case, the supported load is 20 tons for the outer coil and 5 tons for the inner coil, for a total of 251 tons, which is slightly more than the above-mentioned coil spring with a wire diameter of 100 m+++ and a coil diameter of 330 mm. However, the supported load per unit installation area remains at around 70 tons/m2, falling short of the target of 100 tons/m2.

Therefore, if we loosen the conditions regarding the rigidity a little and allow the rigidity to increase somewhat in both the axial direction and the axis-perpendicular direction, and the natural frequency to increase, then the above-mentioned wire diameter of 100 mm and coil diameter of 3.
It is possible to arrange a coil with a wire diameter of 40 mm and a coil diameter of about 130 mm inside a 30 mm coil spring. In this case, the total supported load will be 28 tons, and the supported load per unit installation area will be 100 tons/m2, achieving the target.

However, there is no improvement in adhesion stress either when the outer coil diameter is 400 mm or 330 mm, and when the outer coil diameter is 330 mm, <140 kg/mm2 occurs as described above. Further, when the outer coil diameter is 400 mm, the adhesion stress is as high as 250 kg/mm''.

Problems to be solved by the invention] The conventional technology requires that the supported load per unit installation area be 100 tons/m2 or more, and that both the axial rigidity and the axis-perpendicular rigidity are appropriately set. In other words, for example, the ratio of the axial stiffness KV to the perpendicular stiffness KO is K
No consideration was given to the point that H/KV = -, and when designing a spring, it became necessary to use a wire with a thickness that was extremely difficult to manufacture, and the adhesion stress was too high for the tensile strength of the spring material. The problem was that it exceeded the limit.

The purpose of the present invention is to (1) avoid making the wire diameter d so thick that it is difficult to manufacture (
(e.g. 8510 mm), (i) and without increasing the adhesion stress extremely (e.g. 125 kg/mm2 or less), (i)
To provide a coil spring that has a load bearing capacity of a certain value (e.g., 100 tons/m2) or more per unit installation area, and in which KH/KV is a predetermined small value (e.g., about 1 (/KV = -)) be.

[Means for solving problems]

The multi-wound coil spring of the present invention is a coil spring used in a seismic isolation device, in which two or more wire rods are wound multiple times in the same (q) core shape and in the same winding direction, and each wire rod is wound with respect to each other in the axial direction. The diameters of each coil are set so that they can overlap.

We believe that it is most likely to be implemented when the number of wire rods is two. The present invention can be implemented not only when the coil diameter and the wire diameter of the two wires are the same, but also when the coil diameter and the wire diameter are different. That is, if the coil diameters are set such that the difference in coil diameter between the two wire rods is greater than or equal to the sum of the wire diameters, the wire rods can overlap each other in the axial direction.

An example of a seismic isolation device that uses a coil spring having gaps such that wire rods can overlap each other in the axial direction as in the present invention is, for example, a seismic isolation device that supports a nuclear reactor. In order to suppress rotational vibration, the rigidity KH in the direction perpendicular to the axis must be smaller than the rigidity KV in the axial direction, and therefore, there may be large gaps between each winding of the coil spring.

[Effect]

In the multi-wound coil spring of the present invention, the coil diameters are set so that the wire rods can overlap each other in the axial direction. In other words, by having a shape in which another wire is wound in the gap between the windings of one wire, it is possible to make the load bearing capacity of each coil constituted by each wire similar. Therefore, the load supporting capacity per unit installation area can be increased. Conventional multi-wound coil spring (Figure 12゜10 on page 1242 of the mechanical design handbook listed above)
This is because it can support a larger load compared to the case where the coil diameter of the inner coil becomes thinner, resulting in a smaller wire diameter. Further, since the coils overlap each other in the axial direction when compressed, the gap between the coils is small, and the adhesion stress can be reduced.

Therefore, unlike conventional products, it is possible to satisfy the conditions of wire diameter and rigidity ratio, and there is no need to meet the conditions of adhesion stress or load bearing capacity per unit installation area.
It is possible to provide a coil spring that satisfies all of the conditions of ■■■.

〔Example〕

FIG. 1 shows a first embodiment of the invention. In this embodiment, two wire rods of the same diameter are wound concentrically and in the same winding direction as a coil spring with the same coil diameter. It is composed of a coil spring 2. Coil spring 1 and coil spring 2 are exactly the same, and their specifications are such that the wire diameter d is 100++
++n (for the above purpose), the average diameter of the coil is 400 mm,
The coil inner diameter is 300 mm, the coil outer diameter is 500 mm, the effective number of turns N is 5, and the coil free length Lo is 1360 mm.

The design formula for the coil spring of this example is as follows.

ND3 Ko=Rc-KV KV; Axial rigidity KH; Axis-perpendicular rigidity τ; Stress due to axial load τH; Stress G due to axis-perpendicular load; Shear susceptibility coefficient d; Wire diameter N; Effective winding D; Coil average diameter Rc; Coefficient Fv determined by coil shape; Axial load FH; Axis-perpendicular load Rτ; Coefficient determined by coil shape Based on these formulas, the specifications of the coil spring in this example are set, and the rated The load is 20 tons with one coil spring.
The supported load per unit installation area is 55 tons/m2, the natural frequency in the axial direction when this rated load is applied is 2 Hz, and the natural frequency in the direction perpendicular to the axis is less than IHz (for the above purpose
). Since this coil spring is double-wound concentrically, the coil spring of this example has a supporting load of 40 tons, a supporting load per unit installation area of 110 tons/m2 (objective (■) above), and a Loot of 27 m2. We have achieved the above goals. Furthermore, the coil spring of this example has a stroke of 260 mm before coming into close contact when no load is applied, but this is because if it were not wound twice, there would have been an additional stroke of about 500 mm before coming into close contact. However, by using double winding, it was significantly reduced. The adhesion stress in the case of a single-wound coil is <250 as described above.
kg/mm”, but in the case of a double-wound coil it reaches 85
It is approximately 0 kg/mm2 (objective (above)), which is a significant reduction.

Note that the coil spring of this example contracts by about 60 mm due to its weight when the rated load is applied. Therefore, the stroke of 260 mm is the amount that will only reach close contact when an earthquake load of 3 G in the vertical direction is applied, and can be said to be a sufficient capacity for a seismic isolation device.

FIG. 2 is a detailed view of the flange portion of the embodiment of FIG. 1. The lower flange 4 (the same applies to the upper flange 3) is composed of a flat plate part 5 and a cylindrical part 6, and the flat plate part 5 and the cylindrical part 6 are joined together by welding or the like (14) to form an integral body. What is coil spring 1 and coil spring 2?
It is inserted and stored inside the cylindrical portion 6 in a heavily rolled state. The outer diameter of the coil spring 1 and the coil spring 2 is the cylindrical portion 6.
The inner diameter of the tube is slightly smaller (for example, 5 mm) than the inner diameter of the tube, so that no special considerations are required during insertion. In the case of this embodiment, the axial load is borne by the flat plate portion 5, and the axially perpendicular load is borne by the cylindrical portion 6. In addition, in the case of this example, if the vertical farmland load exceeds 3G, the coil spring will lose its load-bearing capacity, but this is not a problem because the seismic response of a seismically isolated structure is usually not designed to exceed IG. .

FIG. 3 shows the flange portion of another embodiment of the invention. The flange is composed of a flat plate portion 5 and a cylindrical portion 7, and the flat plate portion 5 and the cylindrical portion 7 are joined by welding or the like. The difference from the embodiment shown in FIG. 2 is that the cylindrical portion 7 is threaded, and this threading is made to match the wire diameter and pitch of the coil springs 1 and 2. The coil spring 1 and the coil spring 2 are screwed into the threaded portion of the cylindrical portion 7. In the case of the coil spring of this embodiment, the axial load is borne by the flat plate portion 5 and the threaded portion, and the axis-perpendicular load is borne by the threaded portion. In the case of this embodiment, even if the vertical seismic force exceeds IG, the coil spring will not lose its load supporting capacity.
It has the advantage of maintaining a seismic isolation effect.

When such a multi-wound coil spring as described above is employed, for example, as a seismic isolation device for a fast breeder reactor, it becomes possible to reduce the weight of the nuclear reactor. Furthermore, when adopted as a seismic isolation device for semiconductor manufacturing equipment, it has the effect of improving product yield by further protecting against damage caused by earthquakes.

FIG. 4 shows yet another embodiment of the present invention. The difference from the embodiment shown in FIG. 1 is that the two coil springs 1,
The second point is that both the wire diameter and the coil diameter are different. The embodiment shown in Fig. 1 is an embodiment in which the pitch of the coil springs is wide enough to allow coil springs of the same wire diameter to be placed between them, but in the embodiment shown in Fig. 4, the pitch of the outer coil springs 1 is the same This is an example in which the diameter is not wide enough to allow a coil spring to be placed between the coil springs. In such a case, as long as the wire diameter is greater than or equal to the sum of the wire diameters of the two coil springs, there is no difference in diameter from the conventional technology in which the outer diameter of the inner coil is smaller than the inner diameter of the outer coil, but in the case of this example, the coil diameter The difference is set to an appropriate value (by design) that is greater than the sum of the wire diameters of the two coil springs, so that the two coil springs overlap (contact) in the axial direction against axial compression. Adhesion stress is reduced. Although the load supporting capacity is slightly inferior to the embodiment shown in FIG. 1, it is promising as the next best option when such a design is unavoidable.

Above, as embodiments of the present invention, two coil springs with the same wire diameter and the same coil diameter are wound twice, and a coil spring with different wire diameters and coil diameters is double wound. It is not limited to these.

For example, coil springs with different wire diameters can be wound twice with the same coil diameter, and the number of coil springs is not limited to two turns, but may be three or more turns.

Furthermore, the cross section of the coil spring is not limited to a circular shape either. The connection between the coil spring and the flange portion is not limited to these embodiments, and it is of course also effective to use something such as a tie rod, for example.

〔Effect of the invention〕

According to the multi-wound coil spring of the present invention, (1) the wire diameter d is not made so thick that it is difficult to manufacture (2) and (2) the ratio Kl (/KV) of the axial stiffness KV and the axially perpendicular stiffness KH takes a predetermined small value. Even when designed, it is possible to provide a coil spring that has a load-bearing capacity of more than a certain level per unit installation area;

[BRIEF DESCRIPTION OF THE DRAWINGS] Fig. 1 is a side view showing one embodiment of the present invention, and Fig. 2 is a side view showing an embodiment of the present invention.
3 is a partial detailed sectional view of another embodiment of the present invention, FIG. 4 is a side view of still another embodiment of the present invention, and FIG. 5 is a side view of the prior art. It is a diagram. 1... Coil spring, 2... Coil spring, 3... Upper flange, 4... Lower flange, 5... Flat plate part of flange, 6... Cylindrical part of flange, 7... Cylindrical column of flange. part.

Claims (1)

[Claims] 1. A coil spring used in a seismic isolation device, in which two or more wire rods are wound multiple times concentrically and in the same winding direction, and each coil is wound so that the wire rods can overlap each other in the axial direction. A multi-wound coil spring characterized by a set diameter. 2. The multi-wound coil spring according to claim 1, wherein the coil diameters of the two wire rods are set such that the difference in coil diameter is less than or equal to the sum of the wire diameters. 3. A multi-wound coil spring according to claim 2, in which the coil diameter and the wire diameter are the same. 4. In claim 3, the multi-wound coil is used in a seismic isolation device that supports a nuclear reactor, and the axial stiffness K_V and the axis-perpendicular direction K_H are 1/5<K_H/K_V<1. A multi-turn coil spring with a value of /2.