JP2004019409A - Base isolation supporting device for building - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a base isolation supporting device having a sufficient base isolating action independently of the direction of earthquake and allowing the setting to start base isolating action when the seismic intensity reaches a certain seismic intensity. <P>SOLUTION: Shock absorbing members 4, 5 having elasticity are provided in a bottomed cylindrical body 3 having an upper part open. On the shock absorbing member, there are provided a foundation side fixing member having a ball supporting plate 6 on the upper face for supporting a plurality of steel balls 7 in a rolling manner and a supporting plate 8 as a building side fixing member provided on the steel balls so as to be horizontally displaceable with the rolling operation of the steel balls 7. A plurality of adjusters 9 are provided between the foundation side fixing member and the building member for restricting the horizontal displacement between the foundation side fixing member and a building with the resilience of a spring 12. The magnitude of the shaking by an earthquake can be set to start the base isolating operation by adjusting the free lengths of the adjusters. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a device for supporting a building such as a building or a house on a foundation, and more particularly to a seismic isolation support device for reducing the influence of a seismic force on a building.
[0002]
[Conventional technology and its problems]
There is a seismic isolation structure that prevents or damages the building by suppressing or controlling the effect of the earthquake on the building, so that seismic force is not transmitted to the building. There is a member or mechanism called an isolator that insulates the energy of the earthquake between the structure and the main structure of the building.
[0003]
As an isolator that has been widely used in the past, there is a laminated rubber isolator in which thin rubber sheets and steel plates are alternately laminated and adhered. In this laminated rubber isolator, a vertical load (a load of a building) is applied. The steel plate regulates the horizontal spread of the rubber due to the same load, and the vertical deformation is suppressed.However, it can be greatly deformed by the elasticity of the rubber against the horizontal force, and therefore the load on the building Can be sufficiently supported, and the transmission of horizontal energy due to the earthquake to the building can be reliably shut off.
[0004]
However, in the conventional seismic isolation structure described above, specifications such as the supporting strength of the laminated rubber isolator against vertical load and the elastic deformation rate against horizontal stress must be designed according to the individual building and the anticipated magnitude of the earthquake. Therefore, there is a problem that building design and construction costs increase.
[0005]
The conventional seismic isolation structure described above also has a problem that vertical seismic energy due to so-called pitching in a direct earthquake cannot be cut off.
[0006]
Furthermore, in the conventional seismic isolation structure described above, since the seismic isolation effect is determined by the dimensions and elasticity of the laminated rubber and steel plates, the seismic isolation effect cannot be adjusted according to the magnitude of the earthquake tremor, In other words, it is not possible to prevent seismic isolation from acting on a small shaking earthquake, and if a building shakes due to a small shaking earthquake or wind, a gentle shaking of the building will continue for a long time due to seismic isolation. There is.
[0007]
In addition, earthquakes often cause ground changes after the occurrence, and this ground change often causes buildings to unequally settle and tilt, but conventional seismic isolation structures There is no one that can correct the settlement of a building in case of uneven settlement.
[0008]
In addition, as a seismic isolation structure for ordinary houses, the upper plate and the lower plate are relatively horizontal between the lower plate with the concave upper surface and the upper plate with the lower concave surface. A seismic isolation device with a plurality of steel balls interposed between it and the concrete foundation and the base of the house is installed between the upper and lower plates in response to the shaking of the earthquake. There is something that suppresses the energy of earthquakes on houses by rolling, but if the shaking is large, steel balls fall off and vertical shaking in the case of a direct type earthquake is suppressed. It is not possible to expect sufficient seismic isolation.
[0009]
【Purpose】
An object of the present invention is to provide a sufficient seismic isolation effect regardless of the direction of the earthquake sway, and to set the seismic isolation effect to work when the required seismic intensity is reached, It is an object of the present invention to provide a seismic isolation support device capable of easily and accurately correcting settlement of a building when uneven settlement occurs in the building.
[0010]
Configuration of the Invention
In order to achieve the above object, a device according to the present invention is a seismic isolation support device that supports a building on a foundation, and has an elastically expandable and contractable vertically in a bottomed cylindrical body having an open top. A base-side fixing member having a ball receiving plate that supports a plurality of steel balls on the upper surface of the buffer member so that the steel balls can roll, and a steel member that can be displaced in the horizontal direction by the rolling of the steel balls. A support plate serving as a building-side fixing member provided on a sphere, and between the foundation-side fixing member and the building member, the horizontal displacement between the foundation-side fixing member and the building A plurality of adjusters are provided that are regulated by the spring force of the spring.The adjusters have a free length that can be adjusted, and by adjusting the free length, the magnitude of the earthquake sway that starts seismic isolation action can be set. It has a configuration that allows .
[0011]
Further, the apparatus according to the present invention is characterized in that an upper and lower female screw cylinder in which female threads having winding directions different from each other are formed on the inner peripheral surface between the base-side fixing member and the foundation, And a male screw body having upper and lower male screws having different winding directions formed on the outer peripheral surface thereof, and a rotation operating part for rotating the male screw body between the upper and lower male screws on the outer peripheral surface of the male screw body in the normal and reverse directions. An upper and lower adjustment mechanism is provided in which the upper and lower female screw cylinders are separated or approached by extending and retracting the upper and lower female screw cylinders by rotating the rotation operation unit in the forward and reverse directions.
[0012]
【Example】
Hereinafter, embodiments of the seismic isolation support device according to the present invention will be described based on specific examples shown in the accompanying drawings.
The apparatus of this embodiment includes a seismic isolation mechanism 1 for suppressing shaking caused by an earthquake, and a vertical adjustment mechanism 2 for adjusting the vertical position of a building during construction and settlement correction.
[0013]
The seismic isolation mechanism 1 includes a compression coil spring 4 as a buffer member and a buffer rubber 5 in a cylindrical body 3 having a bottom and an opening at the top, and a ball receiving plate 6 on the buffer member.
The cushioning rubber 5 is provided with a concave portion 5a at the center of the upper surface of, for example, a synthetic rubber formed in a columnar shape. The compression rubber is formed in a gap between the outer periphery of the cushioning rubber 5 and the inner periphery of the cylindrical body 3. A coil spring 4 is provided, and the free height of the compression coil spring is substantially the same as the height of the cushion rubber.
[0014]
The ball receiving plate 6 has a plurality of (four in FIG. 2) recesses 6b on the upper surface of a ring-shaped steel plate having a central hole 6a as shown in FIG. The steel ball 7 is supported so as to be able to roll, and the outer peripheral portion is provided with a rising edge 6c for preventing the steel ball from falling off. The outer diameter of the ball receiving plate 6 is a cylindrical body. 3, which is slightly smaller than the inner diameter, and is capable of sliding up and down along the inner peripheral surface of the cylindrical body.
[0015]
A cylindrical portion 8a vertically extending from the lower surface of the central portion of the support plate 8 is fitted into the central hole 6a of the ball receiving plate 6 and the concave portion 5a of the cushioning rubber 5, and the support plate is formed of the steel balls 7,7. Supported above.
The inner diameter of the concave portion 5a of the cushion rubber is substantially the same as the outer diameter of the cylindrical portion 8a, but the inner diameter of the central hole 6a of the ball receiving plate is sufficiently larger than the outer diameter of the cylindrical portion 8a.
[0016]
Accordingly, the support plate 8 is provided so that the cylindrical portion 8a is fitted in the cushion rubber 5, but can be moved in the horizontal direction by rolling of the steel ball 7 against the elastic force of the cushion rubber.
[0017]
In addition, a sufficient gap is provided between the lower surface of the support plate 8 and the upper edge of the cylindrical body 3 when a load from a building is applied on the support plate. Is larger than a vertical contraction amount of the cushioning member which is assumed when a vertical force is applied.
[0018]
A plurality of adjusters 9, 9 extending radially in the horizontal direction from the tubular body are provided on the outer periphery of the upper portion of the tubular body 3, and these adjusters are used to connect the tubular body 3 to the building during an earthquake. The relative movement amount in the horizontal direction between them is regulated.
[0019]
As shown in FIG. 3, the adjuster 9 includes a cylindrical outer cylinder 10 and an inner cylinder 11 which are open at one end and closed at the other end, and accommodates a coil spring 12 in the outer cylinder. A spring receiving plate 13 is provided to some extent inside from the opening end of the coil spring, and the ends of the coil springs are fixed to the inner surface of the closed end of the spring receiving plate and the outer cylinder, respectively.
[0020]
Each end of the coil spring 12 is firmly fixed to the spring receiving plate 13 and the outer cylinder 10 so that the coil spring 12 can receive a load in either the compression direction or the tension direction. On the other hand, a spring with a similar spring constant is used.
[0021]
At both ends of the adjuster 9, bases of rods 16, 17 having ball joints 14, 15 at their ends are attached, respectively, and the rod 16 on the outer cylinder side is directly fixed to the outer surface of the closed end of the outer cylinder. The rod 17 on the inner cylinder side has a male screw 17a formed on the outer peripheral surface. The male screw is screwed into a nut 18 fixed to the outside of a hole formed in the closed end of the inner cylinder, and the base is formed inside. It faces the inside of the cylinder.
[0022]
One of the ball joints, for example, the ball joint 15 at the tip of the rod 17 on the inner cylinder side is fixed to the outer peripheral surface of the cylindrical body 3 as a base side fixing member by welding or the like, and the other ball joint, For example, the ball joint 14 at the tip of the rod 16 on the outer cylinder side is fixed to the foundation 26 side of a building described later.
[0023]
The vertical adjusting mechanism 2 is a male screw body composed of a cylindrical body having upper and lower female screw cylinders 19 and 20 having female screw parts 19a and 20a formed on the inner peripheral surface thereof and a rotary operation part 22 between upper and lower male screw parts 21a and 21b. The lock nuts 23a and 23b are provided between the rotary operation part 22 and the upper and lower female screw cylinders 19 and 20.
[0024]
The female screw portions 19a and 20a of the upper and lower female screw cylinders 19 and 20 have oppositely wound screw directions, and the upper and lower male screw portions 21a and 21b of the male screw body also have opposite screw winding directions. The upper and lower female screw cylinders are separated or approached by rotating the rotation operation unit in the normal and reverse directions, so that the entire vertical adjustment mechanism 2 can expand and contract.
[0025]
The rotation operating part 22 has a shape in which the cross section of the outer peripheral surface has a hexagonal shape, and can be turned with the same tool as the lock nuts 23a and 23b.
It is preferable that each of the female threads, the male threads, and the lock nuts is a square thread or trapezoidal thread having high load resistance.
A cross-shaped reinforcing rib 24 is provided inside the upper female screw cylinder 19 near the upper end.
[0026]
The vertical adjustment mechanism 2 having the above-described configuration has a configuration in which the upper end of the upper female screw cylinder 19 is connected to the lower surface of the cylindrical body 3 of the seismic isolation mechanism 1 by welding, and the load from the building is large. Is provided with a bracket between the outer surface of the upper female screw cylinder 19 and the lower surface of the cylindrical body 3 as necessary.
[0027]
Thus, the device according to the present embodiment is attached to the upper end of a foundation pile 25 such as a steel pipe pile which is cast on the ground by welding the lower end of the lower female screw cylinder 20 of the vertical adjustment mechanism 2 by welding. The base 26 of the building is fixed on the upper surface of the support plate 8 which is a building-side fixing member with fasteners 27 such as bolts and nuts, and the ball joint 14 on the free end side of the adjuster 9 is connected to the building via a bracket 28. It is fixed and attached to the base 26 as a member on the side.
In addition, all components other than the support plate 8 and the vertical adjustment mechanism 2 in the seismic isolation mechanism 1 are foundation-side fixing members.
[0028]
In FIG. 1, reference numeral 29 denotes a pillar of a building mounted on a base 28, and reference numeral 30 denotes a reinforcement for the base below the pillar.
[0029]
The apparatus of the present invention configured as described above supports the base 26 on the foundation pile 25. More specifically, the load of the building from the base 26 to the support plate 8 is reduced by the steel balls 7, 7 and the ball receiving plate. 6 and a cushion member provided with a compression coil spring 4 and a cushioning rubber 5 via a cylindrical portion 8 a, and further a foundation pile 25 via a cylindrical body 3 and a vertical adjustment mechanism 2.
[0030]
The support plate 8 is supported so as to be displaceable in the horizontal direction with respect to the cylindrical body 3 by the rolling of the steel balls 7 and 7 and the elastic deformation of the cushioning rubber 5. It is regulated by adjusters 9, 9 provided between 3 and the base 26.
[0031]
That is, when the ground shakes in the horizontal direction due to the earthquake, the vertical adjustment mechanism 2 fixed to the foundation pile 25, the cylindrical body 3, the buffer members 4, 5, the ball receiving plate 6, and the steel balls 7, 7 shake with the ground. However, the cushioning members 4, 5, the steel balls 7, 7 and the adjusters 9, 9 act as an isolator for isolating the swing, and the building is displaced in the horizontal direction relative to the ground together with the support plate 8 by its inertia force. However, the absolute position does not change much, so that the ground shaking is hardly transmitted to the building.
[0032]
When the adjuster 9 is disposed to face left and right in FIG. 1, when one adjuster extends, the other adjuster contracts to release vibration, and the adjuster 9 moves between the cylindrical body 3 and the bracket 28. Since they are connected via the ball joints 14 and 15, respectively, it is possible to cope with the swing in the twisting direction with respect to the foundation pile.
[0033]
In addition, the vertical vibration of the ground due to the earthquake is absorbed by the buffer members 4 and 5, and the impact on the building is sufficiently reduced.
[0034]
Thus, the apparatus of the present invention is configured such that the seismic isolation action can be adjusted with respect to the magnitude of horizontal shaking caused by an earthquake.
That is, when the adjuster 9 rotates the rod 17 on the inner cylinder side with respect to the inner cylinder 11, the free length of the entire adjuster can be adjusted, and the seismic isolation is performed by setting the free length of the adjuster. The effect can be adjusted.
[0035]
More specifically, when the free length of the adjuster 9 is set to be the same as the distance between the cylindrical body 3 and the bracket 28 on the base 26 side, the seismic isolation effect becomes the largest, and therefore, the horizontal shaking due to the earthquake. Although the building is very small, the building is displaced with respect to the ground, and the horizontal impact due to the earthquake is not transmitted to the building, but the building continues to be weak for a long time even if the shaking of the earthquake stops.
[0036]
On the other hand, when the free length of the adjuster is set to be larger or smaller than the distance between the cylindrical body 3 and the bracket 28 on the base 26 side, the adjuster 9 pulls or presses the cylindrical body and the base. If the force is large, the seismic isolation function does not work unless the shaking caused by the earthquake exceeds a predetermined size, and if the shaking in the horizontal direction due to the earthquake is small (for example, when the seismic intensity is less than 3), the building is The horizontal energy due to the earthquake is transmitted to the building due to displacement, but if the shaking of the earthquake stops, the building stops immediately and the horizontal shaking due to the earthquake has a predetermined value (for example, seismic intensity 3). If it exceeds, the building will be displaced against the ground against the spring force of the adjuster 9, and the horizontal shock due to the earthquake will not be transmitted to the building. It is locked.
[0037]
The above-mentioned adjustment of the free length of the adjuster 9 is appropriately performed at the time of building construction in accordance with the scale and purpose of use of the building or the state of the ground. A few years later, the free length can be set again.
[0038]
In the adjuster 9 having the above-described configuration, even if the shaking of the earthquake subsides, a slight shaking of the building due to seismic isolation remains, and this small shaking continues until it is completely attenuated by friction. When it is required to quickly attenuate the fluctuation, an adjuster having a damper function is used, and a specific example thereof is shown in FIG.
[0039]
The adjuster 31 having a damper function has a partition plate 32 in the outer cylinder 10, a damper chamber 33 is formed in the outer cylinder by the partition plate 32, and the partition plate, the spring receiving plate 13 of the inner cylinder 11, A piston plate 35 is attached to the other end of the rod 34 having one end fixed to the spring receiving plate 13 and facing the damper chamber, and a plurality of orifices 35a are opened in the piston plate 35. There is.
[0040]
In the damper chamber 33, an appropriate fluid such as oil, nitrogen gas or a mixed fluid of oil and gas is sealed, and even if a sudden stress is applied to expand and contract the adjuster in the axial direction of the adjuster 31, the piston plate The movement of 35 is restricted by the amount of fluid passing through the orifice, so that the adjuster is prevented from suddenly expanding and contracting, and the minute shaking remaining in the building after the shaking of the earthquake stops is attenuated by the damper.
[0041]
By the way, an earthquake often accompanies ground deformation, and in many cases, an earthquake causes unequal settlement of a building and the building tilts.
When the settlement of the building is uneven, the settlement of the settlement can be easily performed by the vertical adjustment mechanism 2 in the apparatus of the present invention configured as described above.
[0042]
Specifically, the correction height in each device is determined by measuring the amount of settlement at the position of each foundation pile 25, the lock nuts 23a and 23b are loosened in each device, and the rotation operation unit 22 is rotated forward and backward. Adjusting the length of the vertical adjustment mechanism in accordance with the required correction height by separating or approaching the upper and lower female screw cylinders 19, 20 and correcting the settlement by a simple operation of tightening the lock nuts 23a, 23b. This eliminates the need for complicated work such as jacking up buildings.
[0043]
In the device of the present invention configured as described above, the adjusters 9 and 9 are provided in four directions around the cylindrical body 3 so that the adjusters 9 and 9 are parallel to the respective bases at the portions where the bases 26 of the building cross in a cross shape. However, adjusters cannot be provided on all sides in the outer periphery of the building. Therefore, in the outer peripheral portion of the building, adjusters may be provided around the cylindrical body 3 in three directions along the base as shown in FIG. 5, or a reinforcing material 36 between orthogonal bases called a fired base. In some cases, one end of the adjuster may be fixed.
[0044]
FIG. 6 shows another embodiment of the apparatus according to the present invention, which differs from the first embodiment in the configuration of the buffer member, the support plate and the ball receiving plate.
That is, in the first embodiment, the cushioning member is constituted by the compression coil spring 4 and the cushion rubber 5, but in this embodiment, the ball receiving plate 38 is supported only by the compression coil spring 37. The compression coil spring 37 has a circular cross section in FIG. 6, but may use a coil spring having a plate shape whose cross section is long on the left and right. The withstand load can be increased.
[0045]
Further, in the first embodiment, the ball receiving plate 6 is configured to be able to slide up and down along the inner peripheral surface of the cylindrical body 3, but in the present embodiment, the ball receiving plate 38 is attached to the outer peripheral edge downward. A portion 38a is provided so that the inner peripheral surface of the peripheral portion can slide up and down along the outer peripheral surface of the tubular body 3.
[0046]
Further, the support plate 39 has a concave portion 39a formed on the lower surface, and the curved surface of the concave portion is configured to be in contact with the upper portions of the steel balls 7, 7, so that even if the support plate 39 is displaced in the horizontal direction. There is always a restoring force for the support plate to return to its initial position, so there is no need to provide a column on the lower surface of the support plate and fit it into the cushion rubber as in the first embodiment.
[0047]
In the case of the first embodiment, one end of each of the adjusters 9 and 9 is attached to the outer periphery of the cylindrical body 3, but in the case of the present embodiment, the adjusters 9 are fixed to the outer periphery of the ball receiving plate 38. In some cases, one end of the adjuster 9 may be attached to the outer periphery of the cylindrical body as in the case of the first embodiment.
[0048]
The apparatus of the first and second embodiments is for supporting a building on a foundation pile 25. The apparatus of the present invention is, for example, a general detached house in which a building is supported on a concrete foundation. FIG. 7 shows a specific example.
[0049]
The device of the present embodiment does not include the vertical adjustment mechanism in the devices of the first and second embodiments, but includes only the seismic isolation mechanism.
A concave portion 40a is formed in the upper portion of the concrete foundation 40, and a cutout portion 26a is formed in the lower portion of the base 26 on the concave portion, and the present embodiment is provided between the concave portion and the cutout portion. Device is provided.
[0050]
Specifically, a ball receiving plate 42 is fixed to the center of the concave portion of the foundation 40 via a vibration isolating member 41 made of a vibration isolating rubber sheet or the like. A support plate 39 is provided, and the support plate 39 is attached to the base 26 via a reinforcing plate 43.
[0051]
One end of each of the adjusters 9, 9 is fixed to the outer peripheral surface of the ball receiving plate 42, and the other end of each of the adjusters is fixed to a bracket on the base side.
The structures of the steel ball 7 and the support plate are the same as those of the second embodiment.
[0052]
By the way, as shown in FIG. 7, the apparatus of the present embodiment is provided with the base 26 so that an appropriate gap 44 is provided between the lower surface of the base and the upper surface of the concrete foundation 40. It acts as a shrinkage allowance and a vent for the lower part of the building.
The apparatus of this embodiment may be provided with a vertical adjustment mechanism as in the first and second embodiments.
[0053]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, the impact by the shaking by an earthquake is hardly transmitted to a building by a seismic isolation mechanism, and the damage of the building by the shaking of an earthquake can be prevented.
In addition, by appropriately adjusting the free length of the adjuster, the seismic isolation effect can be set to start for a predetermined magnitude of seismic intensity (seismic intensity). On the other hand, the seismic isolation function does not work, so that after the earthquake has subsided, it is possible to prevent the building from continuing small shaking, and if the shaking is large enough to damage the building The energy of the earthquake can be sufficiently attenuated to prevent damage to the building.
[0054]
In addition, the vibration in the vertical direction can be absorbed by the shock absorbing member, and a sufficient seismic isolation effect can be obtained even in the case of a vertical vibration in the case of a direct earthquake.
[0055]
Furthermore, with the vertical adjustment mechanism, it is possible to accurately adjust the height of the device by rotating the rotary operation unit forward and backward with respect to unequal settlement of a building that often occurs due to an earthquake, Therefore, the settlement correction can be performed easily and accurately.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view showing an embodiment of an apparatus according to the present invention.
FIG. 2 is a perspective view of a ball receiving plate.
FIG. 3 is a longitudinal sectional view showing a specific example of an adjuster.
FIG. 4 is a longitudinal sectional view showing another example of the adjuster.
FIG. 5 is a view showing a construction example of the device according to the present invention from the bottom of a base of a building.
FIG. 6 is a longitudinal sectional view showing another embodiment of the device according to the present invention.
FIG. 7 is a longitudinal sectional view showing still another embodiment of the device according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Seismic isolation mechanism 2 Vertical adjustment mechanism 3 Cylindrical body 4 Compression coil spring 5 Buffer rubber 6 Ball receiving plate 7 Steel ball 8 Support plate 9 Adjuster 10 Outer cylinder 11 Inner cylinder 12 Coil spring 13 Spring receiving plate 14, 15 Ball joint 16 , 17 rod 18 nut 19, 20 female screw cylinder 21 male screw body 22 rotation operation part 23a, 23b lock nut 24 reinforcing rib 25 foundation pile 26 base 27 stopper 28 bracket 29 pillar 30 reinforcing material 31 adjuster 32 partition plate 33 damper chamber 34 rod 35 Piston plate 36 Reinforcement material 37 Compression coil spring 38 Ball receiving plate 39 Support plate 40 Concrete foundation 41 Anti-vibration member 42 Ball receiving plate 43 Reinforcement plate 44 Clearance

Claims (2)

A seismic isolation support device for supporting a building on a foundation, comprising a buffer member having elasticity capable of being vertically expanded and contracted in a bottomed cylindrical body having an open top, and on the top surface of the cushioning member, A base-side fixing member including a ball receiving plate that rotatably supports a plurality of steel balls, and a support plate as a building-side fixing member provided on the steel balls so that the steel balls can be displaced horizontally by rolling of the steel balls. Comprising, between the foundation-side fixing member and the building member, a plurality of adjusters that regulate horizontal displacement between these foundation-side fixing member and the building by the elastic force of a spring, The adjuster is a seismic isolation support device for a building whose free length is adjustable, and by adjusting this free length, the magnitude of the quake of an earthquake at which seismic isolation starts to work can be set. Between the foundation-side fixing member and the foundation, upper and lower female screw cylinders in which female threads having different winding directions are formed on the inner peripheral surface, and upper and lower female threads different from each other in which the female threads of these female screw cylinders are screwed with each other. A male screw body having an external thread formed on the outer peripheral surface thereof; and a rotary operation part for rotating the male screw body between the upper and lower external threads on the outer peripheral surface of the male screw body in the forward and reverse directions. 2. The seismic isolation support device for a building according to claim 1, wherein an up-down adjustment mechanism is provided so that the upper and lower female screw cylinders are separated or approached by being rotated to expand and contract in the vertical direction.

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