JP3036170B2 - Mount for skid system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mount for a skid system having excellent vibration damping properties.

[0002]

2. Description of the Related Art SQUID (Superconducting quantum i
The skid element is a magnetic sensor having an extremely high resolution and responsiveness using the Josephson effect in a superconductor, and a magnetometer using the skid element is a skid system. A superconductor coil is used when measuring a magnetic field with a skid system. However, a differential connection of a differential coil that senses a magnetic field gradient does not detect a spatially uniform magnetic field or primary gradient magnetic field. It is possible to measure a weak biomagnetic field such as a heart or a brain even in a noise magnetic field.

However, in order to measure an extremely weak magnetic field (10 ⁻¹¹ to 10 ⁻¹⁴ T) typified by magnetoencephalography, the skid system must be made more sensitive and highly accurate measurement can be performed. In addition, there is a need to improve the environment around the system, particularly to improve the level of the skid system mount.

[0004] A frame for a skid system can be roughly divided into a movable portion in which the skid system is provided and a support portion for supporting the movable portion. The performance required of these skid system mounts is that they have the strength of a mount (both movable parts and supports). Isolation of vibration from the outside world (a support base, if anything). Vibration that occurs when the skid sensor unit in the system is moved according to the measurement location is rapidly attenuated (movable unit). Able to withstand 4.2 K (liquid helium temperature, hereinafter referred to as liquid He temperature) which is the main operating temperature of the skid element (movable part). And the like.

Wooden products have been used in conventional skid system mounts because they satisfy the above performance to some extent and have a high vibration damping ability as described later. However, wood products are inexpensive but are of a natural material, so their quality is not stable, and their strength and rigidity are insufficient, making them unsuitable for application to high-performance racks. Metal materials such as stainless steel are excellent in strength and rigidity, but are low in vibration damping capacity, high in magnetic susceptibility, and large in conductivity, so they are easy to generate noise and Joule heat due to eddy current. There was a problem. On the other hand, a fiber-reinforced resin in which inorganic fibers such as glass fibers or carbon fibers are compounded,
The magnetic susceptibility and conductivity were lower than those of metals, and the strength and rigidity were sufficient, but the vibration damping performance and low-temperature characteristics (especially crack resistance) were still insufficient.

[0006]

SUMMARY OF THE INVENTION The present invention provides a mount for a skid system which has excellent vibration damping properties and has sufficient strength even at extremely low temperatures, and is provided with an environment for enabling ultra-precision measurement with the skid system. The purpose is to do.

[0007]

The frame for a skid system of the present invention is a frame using a fiber-reinforced resin having organic fibers as reinforcing fibers as a main part or all of a constituent material, and has a vibration pressure of 20 MPa. The point is that the loss factor measured by the free vibration method is 18 × 10 ⁻³ or more.

[0008]

The organic fibers which are the reinforcing fibers in the fiber reinforced resin (hereinafter referred to as FRP) are preferably those having high strength and high elastic modulus, and high strength polyethylene, aramid, polyarylate; polybenzobisoxazole, polybenz PBZ polymers such as bisthiazole; fibers such as polyethylene terephthalate, polyphenylene sulfide, polyethylene naphthalate, polyimide, phenol, polyamide imide, polyether ether ketone, polyether ketone ketone, polyacrylate, polyacrylonitrile, polyfluorocarbon, and polyvinyl alcohol. Can be Among the above fibers, high-strength polyethylene fibers exhibiting the best performance in terms of magnetic susceptibility, specific gravity, and strength are preferable. Such a high-strength polyethylene fiber has a weight-average molecular weight of 100,000 or more, preferably ultra-high-molecular-weight polyethylene having a flexible polymer chain of 1,000,000 or more dissolved in decalin to obtain a stock solution for spinning. It can be obtained by extruding into water, cooling to form a gel-like fiber, and drawing by a single-stage or multi-stage stretching process to a total magnification of 30 to 40 times.

If necessary, two or more kinds of organic fibers or a mixture of organic fibers and inorganic fibers can be used. Examples of the inorganic fibers include glass fibers, carbon fibers, ceramic fibers such as alumina, silica, zirconia, titania, silicon nitride, and silicon carbide.

In this case, as a mixing method, two or more kinds of organic fibers or filaments of organic / inorganic fibers are combined, or one of the fibers is used as a core and its periphery is covered with the other filament. A method of manufacturing a yarn having a core-sheath structure, a method of manufacturing a mixed fiber using the generated filaments, a method of manufacturing a mixed fiber using the generated filaments, and a method of manufacturing the mixed fiber by using the generated filament bundles. There is a method of laminating prepregs using prepregs or prepregs using organic fibers and prepregs using inorganic fibers.However, inorganic fibers are significantly inferior to organic fibers in terms of magnetic susceptibility, weight, and expansion coefficient. The amount needs to be considered.

The matrix resin used in the present invention is not particularly limited as long as it is a resin that can be molded by heating. For example, epoxy resin, unsaturated polyester resin,
Vinyl ester resin, phenol resin, urethane resin,
Thermosetting resins such as urethane acrylate resins, polyolefin-based resins such as polyethylene, vinyl-based, fluorine-based, thermoplastic polyester-based, PBZ-based, and amide-based resins can be used. From the viewpoint of vibration damping characteristics, an epoxy resin is preferable among thermosetting resins, and a polyethylene is preferable among thermoplastic resins. The epoxy resin is not particularly limited, but a general-purpose bisphenol A type or the like is used.

The method of molding the FRP into a frame for a skid system according to the present invention includes a filament winding method or a tape winding method in which a thread or tape of the organic fiber is wound around a mandrel while impregnating a matrix resin with the matrix resin, and a prepreg is laminated. Press molding method, in which the fiber and matrix resin are integrated and extruded under pressure from the die, vacuum impregnation method in which the fiber and matrix resin are integrally impregnated in vacuum, and then molded, autoclave method And known methods such as a hand lay-up method and a sheet molding compound method.

The mixing ratio of the fibers and the matrix resin in the composite material is expressed by the volume fraction of the fibers (may be abbreviated as Vf).
Is preferably 25 to 85%, more preferably 45 to 85%.
~ 70%. If the Vf of the fiber is less than 25%, the reinforcing effect of the fiber will not be exhibited, and if it exceeds 85%, the impregnation of the matrix resin will be insufficient, and the mechanical properties of the composite material will deteriorate, which is not preferable.

It is preferable that the entire frame for the skid system of the present invention is formed by using the above FRP.
Other materials may be used. Since the movable part is required to have a capability of rapidly attenuating the vibration generated when the skid sensor part in the system is moved in accordance with the measurement location and being capable of withstanding the liquid He temperature, at least the skid of the present invention is required. It is preferable that the movable part of the system mount is formed of FRP.

The FRP used in the present invention is made of an organic fiber that is lightweight, has excellent specific strength, and has a low magnetic susceptibility.
In addition, since a plastic material with good vibration damping and low magnetic susceptibility is used for the matrix resin, it is necessary to provide a skid system mount that is very easy to handle and has high performance compared to FRP and metal materials using glass fiber. Can be. Furthermore, since the expansion coefficient of the organic fiber used in the present invention is negative or close to zero, the expansion coefficient as a material can be suppressed even if it is combined with a matrix resin having a positive expansion coefficient. As a result, even if the skid system maintained at the liquid He temperature is used as a material for the movable part inscribed therein, cracks and the like due to low temperatures do not occur, and good dimensional stability is exhibited even during long-term use.

[0016]

EXAMPLES The present invention will be described below in more detail with reference to examples, but the present invention is not limited to these examples.

Examples 1 to 5 and Comparative Examples 1 to 2 Each of the organic fibers shown in Table 1 was made into a plain fabric of 170 g / m ² , and epoxy resin [Epicoat 828 (manufactured by Yuka Shell Co., Ltd.) 100
Parts by weight, methylhexahydrophthalic anhydride (manufactured by Showa Polymer Co., Ltd.) 90 parts by weight, BMI-12 (benzyl imidazole,
(2 parts by weight of Nippon Yushi Co., Ltd.) was used as a matrix resin to prepare a cured molded product having a Vf of 60% and a wall thickness of 30 mm. The curing condition at this time is 130 ° C. × 3 hours.
After the molded product was processed into a predetermined shape, each member was combined to produce a gantry.

Comparative Examples 3 to 5 In Comparative Example 3, a gantry was produced by molding in the same manner as in the example without using organic fibers. In Comparative Example 4, wood was used, and in Comparative Example 5, stainless steel (SUS304) was used to produce a gantry having the same shape as the example.

Each stand was evaluated by the following method, and the results are shown in Table 1. (1) Specific gravity The specific gravity was measured (25 ° C.). (2) Loss factor Using a damping characteristic evaluation device manufactured by Lyon Co., Ltd., a loss factor indicating the degree of vibration damping by the free vibration method was measured. However, the excitation pressure was 20 MPa. (3) Flexural strength and flexural modulus A sample with a thickness of 5 mm, a width of 10 mm and a length of 50 mm was cut out from each sample, and the flexural strength and flexural modulus at room temperature were measured at a distance between fulcrums of 25 mm and a crosshead speed of 1 mm / min. It was measured. (4) Bending strength standard deviation 10 cut out from 10 different places for each sample
Each of the samples was subjected to a bending test in the same manner as in the above (3), and the standard deviation indicating the variation was calculated. (5) Specific bending strength and specific bending elastic modulus

The specific bending strength and the specific bending elastic modulus were calculated from the results of measuring the bending strength and the bending elastic modulus under the condition (3) and the specific gravity (specific bending strength = bending strength / specific gravity, the same applies to the specific bending elastic modulus). ). (6) Crack resistance A sample having a shape of 50 mm x 20 mm x 100 mm was prepared from each sample, immersed in liquid He for 30 minutes, pulled up, and visually inspected for cracks. The evaluation was based on the following criteria. ；: No crack is observed at all. Δ: Cracks are slightly observed. X: There are large cracks on the entire surface.

[0021]

[Table 1]

It can be seen that the organic fiber reinforced resins of Examples 1 to 5 have extremely excellent vibration damping performance and good crack resistance as compared with the inorganic fiber reinforced resins of Comparative Examples 1 and 2. The epoxy resin alone system of Comparative Example 3 is inferior in mechanical properties and cold resistance, and the wood of Comparative Example 4 has excellent vibration damping properties but has large variations, and it is difficult to obtain stable quality. . The metal material of Comparative Example 5 has extremely poor vibration damping performance.

[0023]

The skid system mount of the present invention is made of an organic fiber reinforced resin having a low magnetic susceptibility, which is lightweight and has excellent low-temperature characteristics, specific strength, and vibration damping properties. , FRP using glass fiber
Compared to a gantry mainly made of metal or a metal material, a gantry for a skid system having very high performance and easy handling can be provided. By using the frame for the skid system of the present invention, it is possible to shut off external vibrations and quickly attenuate vibrations when the sensor unit is moved, so that even very weak magnetic fields such as brain magnets can be detected. The environment that can perform ultra-precision measurement that can be done was set.

[Brief description of the drawings]

FIG. 1 is a graph showing vibration damping.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-62-175681 (JP, A) JP-A-51-130895 (JP, A) JP-A-63-213906 (JP, A) JP-A-4- 67843 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) A61B 5/05-5/053

Claims (1)

(57) [Claims] 1. A gantry using a fiber-reinforced resin having organic fibers as reinforcing fibers as a main part or all of a constituent material.
The free vibration method when the excitation pressure is 20 MPa.
Gantry skids system characterized Oh <br/> Rukoto in loss factor is 18 × 10 ^-3 or more to be measured I.