JPH0613889B2 - Bolt fastening structure for disc-shaped body of high-speed rotating body of 10,000 rpm or more and shaft - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a bolt fastening structure for a disc-shaped body of a high-speed rotating body of 10,000 rpm or more and a shaft, which is suitable for coupling a rotor of a turbo molecular pump and a shaft. Regarding

[Conventional technology]

Conventionally, in a high-speed rotating body of 10,000 rpm or more such as a turbo molecular pump, the coupling structure of the disc with a central hole and the shaft is generally as shown in FIG. 5 partial vertical sectional view and FIG. 6 partial vertical sectional view. In the structure shown in FIG. 5, the inner peripheral portion of the disc-shaped body 1 with a central hole is a straight splint portion 1a with the shaft 2, and a flange portion 2c is formed on the shaft 2 to abut. Surface 2f
And the shaft end is the anchor part 2a, the flange contact surface 2f and the disk part contact surface 1f of the disk-shaped body 1 are provided.
Are brought into contact with each other and fastened with the bolt 4. Further, in the structure shown in FIG. 6, the inner peripheral portion of the disc-shaped body 1 is a straight splint portion 1a with the shaft 2, and a protrusion 2'is formed on a part of the shaft 2 to form the disc-shaped body 1. Is provided with a contact surface 2f for contacting with the disk-shaped body 1 and a threaded portion 2b for fastening the straight soldering part 2a with the disk-shaped body 1 is further formed on the free end 2 ″ side of the disk-shaped body 1 and the shaft 2. It is fitted and abutted and fastened by the nut 3.

Therefore, in a rotating body in which the disc-shaped body 1 and the shaft 2 are fastened, it is important to prevent vibration during rotation.
It is necessary to prevent the center of gravity from moving during rotation, and as shown in the explanatory diagram in FIG. 7, the bending rigidity M / of the bolt fastening part that is based on the relationship between the bending moment M (kgf · mm) and the rotation angle θ (rad). It is necessary to increase θ.

Therefore, in order to prevent the movement of the center of gravity, it is most important to prevent the occurrence of the clearance between the fitting portions, that is, the anchor portions 1a and 2a. However, the conventional structure shown in FIGS. The deformation of the portion is much larger in the disc-shaped body 1 than in the shaft 2, and in order to keep the contact state or keep the clearance extremely small, fitting with a tightening margin is necessary, which is practically impossible. Nearly possible.

Further, in order to increase the bending rigidity, the radial position of the bolt should be as large as possible on the outer peripheral side, sufficient tightening surface pressure should be maintained, and the contact surfaces 1f and 2f and the fitting surface 1a of the anchor part should be It is necessary that 2a is sufficiently tightened. However, in the conventional structure shown in FIGS. 5 and 6, since a clearance is generated in the fitting surfaces 1a and 2a of the anchor part, the bending rigidity is reduced. Therefore, it is necessary to increase the bolt size and tighten the bolts strongly. As described above, if the bolt is moved closer to the outer periphery of the radial position or the size of the bolt is increased, the centrifugal force of the bolt increases with high speed rotation, which is a problem.

Further, with respect to the structure shown in FIG. 6, high-speed rotation is impossible because of its rigidity, and it is small in size, and can be applied only to low-speed rotation.

[Problems to be solved by the invention]

The present invention has been proposed in view of such circumstances,
It is possible to obtain a high-speed rotating body of 10,000 rpm or more, which can prevent the occurrence of a clearance at the fitting part during rotation and can obtain a large bending rigidity, can prevent vibration, and can rotate at high speed and has excellent rotation performance. An object of the present invention is to provide a bolt fastening structure between a disc-shaped body of a rotating body and a shaft capable of performing the above.

[Means for solving problems]

To this end, the present invention is directed to a cylindrical fitting surface formed on the center hole surface of a disc-shaped body having a center hole and an axial contact surface formed on the inner surface of the disc-shaped body, and an end portion of the shaft. A fitting surface that is formed on the outer periphery and faces the fitting surface of the disc-shaped body, and a flange portion that projects from the inner end of the fitting surface and that faces the abutment surface of the disc-shaped body. A plurality of bolt holes bored from the disk-shaped body along the entire circumference of the contact surface and the both contact surfaces, bolts attached to the holes, and a bolt mounting seat on the disk-shaped portion of the bolt hole. A counterbore provided so that the effective surface length is equal to or less than the bolt head height, and a wide shallow groove type annular notch provided closer to the shaft center than the bolt hole of the abutment surface at a right angle to the shaft. It is characterized by

[Work]

The device of the present invention has the above-described configuration, by notching a portion closer to the shaft center than the bolt hole in the contact surface of the flange portion of the shaft, and limiting the radial effective length of the contact surface to the outer peripheral side by a bolt, Since the surface pressure during tightening can be increased and the contact rate of the surface can be increased, and sufficient surface pressure can be generated at a position distant from the axis of the shaft, bending rigidity can be increased.

In addition, a counterbore is formed in the plurality of bolt holes drilled in the disk-shaped body so that the effective length of the bolt mounting seat surface is at the height of the bolt head or slightly smaller than that, and The rigidity and the centrifugal strength of the bolt can be improved, and it can be used up to 10,000 rpm or higher.

〔Example〕

An embodiment in which the present invention is applied to an ultrahigh-speed rotating molecular pump of 20,000 to 60,000 rpm will be described with reference to the drawings.
2, 3, and 4 are partial vertical cross-sectional views of different embodiments.

First, in FIG. 1, a disc-shaped body 1 with a clear center hole is provided with a fitting surface 1a on the center hole surface and a contact surface 1f on the inner side surface. A flange portion 2c is formed on the shaft 2 slightly inside the end portion, and a fitting surface 2 facing the free end and facing the disc-shaped body fitting surface 1a is formed on the outer peripheral surface thereof.
A is formed, and the flange portion 2c is formed with a contact surface 2f that faces the disk-shaped body contact surface 1f.
A plurality of bolt holes 4a are bored from the disk-shaped body 1 side over the entire abutment surfaces 1f and 2f, and fastening bolts 4 are screwed into them.

Further, a notch 2d that is a wide shallow groove type annular groove is formed in the contact surface 2f of the shaft 2 closer to the shaft center than the bolt hole 4a to limit the effective length of the contact surface 2f to a small value.

The base end portion of the flange portion 2c does not have a surface that is perpendicular to the axis when viewed microscopically, so this portion is removed as a wide shallow groove-shaped groove (notch 2d). As a result, the notch 2d limits the effective length of the contact surface 2f to a small value, increases the surface pressure when tightening with bolts and increases the contact rate of the surface, and provides sufficient surface pressure at a position away from the axial center. To increase bending rigidity.

Further, a counterbore 1c is provided on the disc-shaped body 1 of the bolt hole 4a so that the effective length 1 of the bolt tightening seat surface is about the head height h of the bolt 4 or slightly smaller than that.

This helps to reduce the weight of the bolt 4 and to reduce the centrifugal force acting on the bolt head with high rotational speed. This is because the shear axial force of the bolt head is regarded as the tension of the bolt and l≤
This is because the weight of the bolt head can be reduced by setting h.

Next, referring to FIG. 2, in addition to the structure shown in FIG. 1, a part of the contact surface 1f of the disk-shaped body 1 is cut out and a cylindrical portion (narrow deep groove type annular groove) is formed near the center hole. ) 1b is formed. Due to the circulation groove 1b, an annular lip L is formed at the inner end corner portion of the inward flange portion of the disc-shaped body 1, and the lip L
Is a residual strain due to micro plastic deformation at the tip that escapes in the inward radial direction due to cutting resistance during processing. Therefore, when the disk-shaped body 1 is displaced microscopically in the outward radial direction by the centrifugal force at the time of high-speed rotation in the assembled state, the annular lip L is spring-backed so that it is coaxial with the center line without being eccentric. Allows displacement while maintaining.

Further, in FIG. 3, a screw portion 2b is formed on the outer periphery of the free end protruding portion of the shaft 2 in addition to the structure shown in FIG. 1, and the nut 3 is screwed into this, and in FIG. In addition to the structure shown in FIG. 3, a cutout portion similar to that shown in FIG. 2 is provided.

In such a device, the effective length of the contact surface 2f of the shaft 2 is limited to a small value, and the effective length 1 of the bolt mounting seat surface of the disk-shaped body 1 is equal to or higher than the head height h of the bolt 4. Since the counterbore 1c is slightly small, the bending rigidity can be increased, and a rotating body having excellent rotational performance can be obtained without increasing the occurrence of clearance on the fitting surface during rotation.
Further, in FIG. 2, since the cylindrical portion (narrow width deep groove type annular groove) 1b is formed near the center hole of the disc-shaped body 1,
It is possible to further prevent the occurrence of a clearance between the mating surfaces 1a and 2a. Furthermore, in FIGS. 3 and 4, the shaft 2 and the disk-shaped body 1 are firmly fastened to the nut 3 as well. The effect of further preventing the occurrence of clearance and the occurrence of vibration can be exerted.

〔The invention's effect〕

In short, according to the present invention, the cylindrical fitting surface formed on the central hole surface of the disc-shaped body having the central hole and the axial right-angled contact surface formed on the inner side surface of the circular disc, and the end of the shaft. A right angled axis formed on the outer circumference of the disc-shaped body and facing the disc-shaped body, and a flange projecting at the inner end of the mating surface. A plurality of bolt holes bored from the disk-shaped body along the entire circumference of the contact surface and the both contact surfaces, bolts attached to the holes, and bolts mounted on the disk-shaped body of the bolt holes. It is provided with a counterbore provided so that the effective seating surface length is equal to or less than the bolt head height, and a wide shallow groove type annular notch provided closer to the shaft center than the bolt hole of the contact surface orthogonal to the shaft. This prevents the occurrence of clearance at the mating part during rotation and provides a large bending rigidity, which can prevent vibration and increase the speed. INDUSTRIAL APPLICABILITY The present invention is extremely useful industrially because it provides a bolt fastening structure between a disk-shaped body of a rotating body and a shaft that can obtain a rotating body that can rotate and has excellent rotation performance.

[Brief description of drawings]

1, FIG. 2, FIG. 3, and FIG. 4 show different embodiments of the bolt fastening structure between the disk-shaped body and the shaft of the high speed rotating body of the embodiment in which the present invention is applied to the turbo molecular pump. It is a partial longitudinal cross-sectional view. FIG. 5 and FIG. 6 are partial vertical cross-sectional views showing a bolt fastening structure between a disk-shaped body and a shaft of a rotary body of a conventional turbo molecular pump, and FIG. 7 is an illustration of bending rigidity of the rotary body. is there. 1 ... Disc-shaped body, 1a ... Fitting surface, 1b ... Cylindrical part,
1c …… Spot facing of bolt seating surface 1f …… Abutting surface 2 ……
Shaft, 2a ... Mating surface, 2b ... Screw part, 2c ... Flange part, 2d ... Notch, 2f ... Abutting surface, 3 ... Nut, 4 ... Bolt, 4a ... Bolt hole.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shomin Kaneko 4-6-22 Kannon Shinmachi, Nishi-ku, Hiroshima City, Hiroshima Prefecture Mitsubishi Heavy Industries, Ltd. Hiroshima Works (56) References: 521-21098 (JP, U) ) Actual Development Sho 61-17528 (JP, U) Actual Public Sho 55-48819 (JP, Y2) Noboru Koma "Handbook for Machinery and Equipment Design" 3rd edition (published by Taikaku on November 30, 1964) 231

Claims (1)

[Claims] 1. A cylindrical fitting surface formed on a central hole surface of a disc-shaped body having a central hole, a shaft right-angled contact surface formed on an inner surface of the disc-shaped body, and an outer periphery of an end portion of the shaft. A mating surface that is formed on the disk-shaped body and faces the mating surface of the disc-shaped body, and a flange portion that projects from the inner surface of the mating surface Surface, a plurality of bolt holes bored from the disk-shaped body side along the entire circumference of the both contact surface parts, bolts fitted in the holes, and a bolt mounting seat on the disk-shaped body portion of the bolt hole. A counterbore provided so that the effective surface length is equal to or less than the bolt head height, and a wide shallow groove type annular notch provided closer to the shaft center than the bolt hole of the abutment surface at a right angle to the shaft. A bolt fastening structure between a disc-shaped body of a high-speed rotating body of 10,000 rpm or more and a shaft, which is characterized in that.