JP5239058B2 - High speed rotating body - Google Patents

Description

  The present invention relates to a high-speed rotating body used for a flyhole for a power storage system, a rotor of a centrifuge, and the like.

  Being able to rotate the rotating body at a higher speed relates to technological innovation in various fields. For example, a flyhole that can store electrical energy in rotational kinetic energy, a centrifuge that can perform analysis more efficiently by rotating at high speed, and the like can be considered.

  The speed at the outer edge of the disk (referred to as peripheral speed) is given by the product of the angular speed around the axis and the radius of the disk. The rotating body used so far for industrial use has a peripheral speed of 1000 m / s or less. This is because the rotating body has been restricted by the limitations of material strength and structure. Here, when a disk made of a certain material breaks at a certain peripheral speed, this is defined as a fracture peripheral speed.

In general, it is known that the fracture peripheral speed of a disk having a uniform thickness is determined by the specific strength of an isotropic material such as a metal. For example, A70705T6 of ultra-duralumin is required to have a fracture peripheral speed of 631 m / s from its yield stress (460 MPa) and density (2800 kg / m ³ ).

  The fiber reinforced plastic is calculated to have a breaking peripheral speed of 1000 m / s or more from its high specific strength. In particular, since carbon fiber has high strength, it has been widely used as a conventional fiber-reinforced plastic disk (referred to as a CFRP disk). So far, CFRP discs have mainly been researched with perforated discs of uniform thickness (referred to as “circular winding discs”) in which fibers are wound in the circumferential direction of a rotating body.

  In an orthotropic or isotropic perforated disk, the stress along the circumferential direction is overwhelmingly high as the rotational stress, so the circumferentially wound disk wrapped with carbon fibers in the circumferential direction has a high fracture rotation speed. Was expected to show. However, since it is not reinforced with fibers in the radial direction, the strength in the radial direction is almost equal to that of the resin, and breakage along the fibers limits the maximum rotation speed.

  Generally, in a rotating disk, the radial stress increases as the inner / outer diameter ratio decreases. Here, the inner / outer diameter ratio is the ratio of the inner diameter to the outer diameter, and the disk having a smaller inner / outer diameter ratio means a disk having a hole having a relatively smaller inner diameter than the outer diameter. In the circumferentially wound disk, when the inner / outer diameter ratio becomes relatively small, the radial stress exceeds the strength of the resin, and separation (breakage) occurs between the circumferential fiber bundles.

  As a technique for suppressing separation between fibers, a technique for concentrically assembling several circular disks by press fitting has been studied. This method preliminarily applies a compressive radial stress by press-fitting, and has an effect of suppressing peeling between fibers to some extent. However, in press fitting, stress concentration occurs at the ends of both rings, so there is a limit in the molding process. For this reason, the inner / outer diameter ratio of the disk by this method is limited to 0.6 or more.

  In order to actually use a CFRP disk as a rotating body, as shown in FIG. 6, in order to hold the disk 30 on the rotating shaft, a hub is joined 32 to the inner peripheral side of the CFRP disk, and the rotating shaft is connected to the hub. 34 had to be assembled. For example, consider attaching an aluminum (A7075) hub. As described above, the fracture peripheral speed of aluminum is 631 m /, and it is assumed here that an aluminum hub is joined to the inside of a CFRP disk having an inner / outer diameter ratio of 0.6. At this time, the limit of the outermost peripheral speed at which the aluminum hub does not break is approximately 1051 m / s obtained by dividing 631 by 0.6. In other words, when the outer periphery of the CFRP disk is 1051 m / s, the aluminum hub has reached the breaking peripheral speed of 631 m / s and cannot withstand an outer peripheral speed higher than this. Although it is sufficiently possible for the CFRP disk to exceed 1051 m / s, the peripheral speed of the CFRP disk having an inner / outer diameter ratio of 0.6 is 1000 m / s due to the limitation of the material strength inherent to aluminum as described above. The limit is about s. When the inner / outer diameter ratio is higher than this, the destruction of the aluminum hub always occurs first, and the destruction peripheral speed of the entire disk does not exceed 1000 m / s.

  The specific strength of steel (SCM435) is almost equal to that of aluminum and the situation is similar. For this reason, Japanese Patent Application Laid-Open No. 9-42380 has proposed a composite flywheel in which a hub made of glass fiber reinforced plastic is attached to a flywheel disk. Since this hub is a fiber reinforced plastic, the peripheral breaking speed can be increased. However, the structure is such that the disk is held via a hub on the rotating shaft, and it cannot be said that the features of the CFRP disk having a high breaking peripheral speed can be fully utilized.

  Previous CFRP discs were almost uniform in thickness. This is presumably because the thickness direction is not reinforced with fibers in the same way as the radial direction, so that the generation of stress in the thickness direction is suppressed by setting the thickness to a uniform thickness. However, it cannot be said that the design flexibility of changing the thickness for speeding up is given.

JP-A-9-42380

  The present invention has been made under such circumstances, and an object of the present invention is to provide a high-speed rotating body capable of making the rotational speed higher than ever.

  In order to achieve the above object, the high-speed rotating body of the present invention has the following characteristics. First, it has a disk shape having an inner diameter and an outer diameter, and the disk is made of fiber reinforced plastic, and the reinforcing fibers are in the R direction (radial direction), θ direction (circumferential direction), Z direction (thickness) of the cylindrical coordinate system. It is characterized by being oriented in each direction.

  The reinforcing fiber of the high-speed rotating body has a thinner disk from the center toward the outer periphery so that the fiber volume ratio in the R direction is constant.

  The ratio of the inner diameter to the outer diameter of the disk is preferably 0.5 or less.

  A cylindrical portion having a large thickness is provided on the inner diameter portion of the disk, and a metal rotating shaft or hub is joined to the outer peripheral surface of the cylindrical portion.

  A metal part connected to the inner diameter part is a bearing part that directly transmits power.

  The reinforcing fibers can be carbon fibers, glass fibers, ceramic fibers, or composite fibers thereof.

  The high-speed rotating body of the present invention can reduce the inner / outer diameter ratio of the fiber-reinforced plastic disk by using a reinforced base material reinforced in three axial directions (R direction, θ direction, Z direction) of the cylindrical coordinate system. it can. In particular, the effect of reducing the inner / outer diameter ratio is by strengthening the radial direction. In addition, since the inner / outer diameter ratio is reduced, it is possible to prevent the fracture peripheral speed inherent to the material of the metal rotating shaft to be joined from being exceeded. In addition, by strengthening the Z direction of the cylindrical coordinate system, it is possible to give a reinforcing effect against the Z direction stress generated when the inner diameter side boss part joins the metal rotation shaft and the shear stress in the RZ plane. Become.

  Embodiments of the present invention will be described below with reference to the drawings. The conventional rotator breakage is caused by peeling (breaking) between fiber bundles in the circumferential direction due to the absence of reinforcing fibers in the radial direction of the CFRP disk. For this reason, strengthening in the radial direction was necessary.

  In addition, the fact that the metal hub is smaller than the fracture peripheral speed of the CFRP disk makes high-speed rotation difficult. For this reason, it is necessary to assemble a metal hub on a CFRP disk having a small inner / outer diameter ratio. For example, when an aluminum hub is joined to a CFRP disk having an inner / outer diameter ratio of 0.2, the fracture peripheral speed is 3155 m / s, which is obtained by dividing the fracture peripheral speed of aluminum by 631 m / s by 0.2. . This can be said to be effectively utilizing the high fracture peripheral speed of the CFRP disk.

  Assembling a structure as an assembly from three or more parts, such as a fiber reinforced plastic disk, a metal hub, and a rotating shaft, complicates the manufacturing process. For this reason, it is necessary to reduce the number of parts from three to two. By reinforcing the thickness direction with fibers in order to rotate at higher speeds, the thickness of the disk can also be optimally designed, giving freedom in disk design.

  Therefore, in this embodiment, such a problem is overcome by arranging the reinforcing fibers in the radial direction. By reinforcing in the radial direction, cracks in the fiber bundle can be suppressed and the inner / outer diameter ratio of the disk can be reduced. Further, since the inner / outer diameter ratio of the disk is small, the disk is directly joined to the rotating shaft without interposing a hub (referred to as hubless joining). Furthermore, the Z direction is reinforced with fibers to reinforce the stress associated with the thickness change.

  As described above, in the present embodiment, the reinforcing fiber is a disk oriented in R, θ, and Z in the three-dimensional reinforced cylindrical coordinate system, and the inner / outer diameter ratio is small. A shape having a cylindrical boss portion is formed on the inner diameter side of the disk, and a rotating shaft is joined to the outer peripheral side of the boss portion.

  FIG. 1 is a perspective view showing an orientation state of reinforcing fibers used in the present embodiment. As shown in the figure, the reinforcing fibers are oriented in all of the radial direction (R direction), the circumferential direction (θ direction), and the thickness direction (Z direction). FIG. 1 shows the orientation state at a certain point of the CFRP disk of the present embodiment, but all the points of the CFRP disk are oriented in the same direction as in FIG.

  2 is a cross-sectional view of the high-speed rotating body 10 according to the first embodiment of the present invention, and FIG. 3 is a vertical cross-sectional view showing only the portion of the CFRP disk 1 in the high-speed rotating body 1 shown in FIG. . The CFRP disk 1 of this embodiment has an outer diameter φ300, an inner diameter φ20, and a cylindrical portion 2 having an outer diameter φ40 and a height of 10 mm on the inner diameter side. Further, the thickness at the outer diameter is 10 mm, and the thickness is reduced almost linearly from the thickness of the inner diameter side disk of 30 mm. The fiber volume contents in each direction in the cylindrical coordinate system of the three-dimensional fabric were 0.183, 0.252, and 0.024, respectively.

  FIG. 4 is a view showing the metal rotating shaft 4 of the high-speed rotating body 10 shown in FIG. The rotation shaft made of SNCM435 has an outer diameter of φ60. The CFRP disc 1 and the rotating shaft 4 were joined to the inner peripheral surface 5 of the rotating shaft 4 by press-fitting with an inner margin of 0.03 mm on the outer peripheral surface 3 of the cylindrical portion 2 of the CFRP disc.

In Example 1, the design breaking peripheral speed of the fiber reinforced plastic was set to 1500 m / s in consideration of the safety factor. The outer circumference rule of the rotating shaft is calculated as 300 m / s by multiplying the ratio (φ60 / φ300) between the rotating shaft and the outer diameter of the disk by the design breaking peripheral speed. Since the material strength of SNCM435 is 1373 MPa and the density is 7850 kg / m ³ , the fracture peripheral speed is 652 m / s. Since the value of 300 m / s is within the fracture peripheral speed range of SNCM435, the design is acceptable.

  FIG. 5 is a longitudinal sectional view of the high-speed rotating body 20 according to the second embodiment of the present invention. The CFRP disc 22 has an outer diameter of φ300, and is a disc having no hole in the center, unlike the case of the first embodiment. A cylindrical portion 24 having an outer diameter φ20 and a height of 10 mm is provided on the inner diameter side. Further, the thickness at the outer diameter is 10 mm, and the thickness is reduced almost linearly from the thickness of the inner diameter side disk of 30 mm. The fiber volume contents in each direction in the cylindrical coordinate system of the three-dimensional fabric were 0.153, 0.272, and 0.035, respectively.

In Example 2, the design breaking peripheral speed of the fiber reinforced plastic was set to 1700 m / s in consideration of the safety factor. The outer peripheral speed of the rotating shaft is obtained as 226 m / s by multiplying the ratio of the rotating shaft and the outer diameter of the disk (φ40 / φ300) to the white system breaking peripheral speed. Since the material strength of SNCM435 is 1373 MPa and the density is 7850 kg / m ³ , the fracture peripheral speed is 652 m / s. Since the value of 226 m / s is within the fracture peripheral speed range of SNCM435, the design is acceptable.

  According to the high-speed rotating body of the present invention, since the speed is increased, it is used in the fields of a power storage flywheel, a gas turbine, a compressor, a centrifuge, and the like.

It is the perspective view which showed the orientation state of the reinforced fiber used by this embodiment. It is a longitudinal cross-sectional view of the high-speed rotary body which concerns on Example 1 of this invention, and shows the state which joined the rotating shaft to the CFRP disk. It is a longitudinal cross-sectional view of the CFRP disk of the high-speed rotary body which concerns on Example 2 of this invention. It is a figure which shows the rotating shaft of the high-speed rotary body which concerns on Example 1 of this invention. It is a longitudinal cross-sectional view of the high-speed rotary body which concerns on Example 2 of this invention, and shows the state which joined the rotating shaft to the CFRP disk. It is a perspective view of the conventional rotary body.

10, 20 High-speed rotating body 1, 22 CFRP disk 2, 24 Cylindrical portion 4, 26 Rotating shaft

Claims (5)

A disk shape having an inner diameter and an outer diameter, wherein the disk is made of fiber reinforced plastic, and the reinforcing fibers are in the R direction (radial direction), θ direction (circumferential direction), Z direction (thickness direction) of the cylindrical coordinate system. ) And the reinforcing fibers are thinned from the center toward the outer periphery so that the fiber volume fraction in the R direction is constant .   The high-speed rotating body according to claim 1, wherein a ratio of an inner diameter to an outer diameter of the disk is 0.5 or less.   The high-speed rotating body according to claim 1 or 2, wherein a cylindrical portion having a large thickness is provided on an inner diameter portion of the disk, and a metal rotating shaft or hub is joined to the outer peripheral surface of the cylindrical portion.   The high-speed rotating body according to any one of claims 1 to 3, wherein the metal part connected to the inner diameter part is a bearing part that directly transmits power.   The high-speed rotating body according to any one of claims 1 to 4, wherein the reinforcing fiber is carbon fiber, glass fiber, ceramic fiber, or a composite fiber thereof.

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