JPS624926A - Shaft joint of rotary machine - Google Patents

Abstract

PURPOSE:To prevent a slip of a joint area, by a method wherein a sleeve, longer than the length in the direction of the axis of a pair of shaft joint flanges and having plural circumferential grooves formed in an inner and an outer peripheral surface and alternately in a longitudinal direction, is situated in a gap between the bolt holes of the shaft joint flanges and the outer periphery of a fastening bolt. CONSTITUTION:A sleeve 10 is disposed in a gap 9 between bolt holes 4 and 5 of a pair of shaft joint flanges 1 and 2 and the outer periphery of a fastening bolt 6. Since the sleeve 10 is longer given amount than a total of lengths of the bolt holes 4 and 5, the sleeve is resiliently deformed by fastening of fastening nuts 7 and 8 and is forced into pressure contact with the fastening bolt 6 and the bolt holes 4 and 5. In which case, circumferential grooves 12 and 13 may be formed in the outer and the inner peripheral surface of the sleeve 11 alternately in an axial direction. Thus, a clearance 9, increased by fastening of the fastening nuts 7 and 8, is absorbed through deformation of the sleeve 10 or 11, and this enables prevention of a slip of a joint area.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a shaft coupling for a rotating machine, and particularly to a shaft coupling suitable for coupling a high-speed, large-capacity, multi-span steam turbine generator rotor.

(Technical background of the invention and its problems) In recent years, thermal power plants and nuclear power plants have tended to have larger capacities, generator rotors have become larger, and ultra-high pressure steam sources are also used. For this reason, the shaft coupling that transmits the rotational force of the turbine blades to the end of the generator rotor has
Significantly large loads are applied. Therefore, shaft couplings have become larger, the number of tightening bolts has increased, and the bolts have also become larger in diameter.

FIG. 5 shows a conventional shaft joint of a rotating machine, in which a pair of shaft joint flanges 1.2 face each other at a joint surface 3, and a tightening bolt 6 passes through each bolt hole 4, 5. A tightening nut 7.8 is tightened to provide a predetermined pressure on the joint surface 3.

However, when the turbine generator rotor overspeeds due to load shedding of the turbine generator, and when it returns to the rated speed again, there is a difference in shaft vibration values before and after overspeed, which may make it impossible to continue operation. . This is thought to be due to the fact that as the rotor of the turbine generator becomes larger and has a larger capacity, fluctuations in shaft torque become larger, which causes slippage (slip failure or surface opening) on the shaft coupling surface.

In order to prevent such slippage on the shaft coupling surface, it is necessary to increase the blood pressure on the shaft coupling surface 3 and to make the clearance 9 between the port hole 4.5 and the tightening bolt 6 as small as possible. .

In order to reduce this clearance 9, the tightening bolt 6
A reamed bolt is usually used as a bolt, and the clearance 9 is adjusted to a diameter of about 0.025 m to minimize play between the bolt 6 and the bolt holes 1 and 5. On the other hand, the blood pressure of the shaft joint is determined by the tightening torque of each tightening hole 1 to 6, and this tightening torque T is defined by the following formula (according to the mechanical elements of ``Mechanical T Science Handbook''). (disclosed).

+d janβ 10μH'dN) Here, T is the tightening torque of 1-lux, σ8 is the tensile stress of the bolt, and A
Ha Pol!・The minimum cross-sectional area of The falling lead angle, dN, is the average diameter of the bolt or nut at the seating surface.

As can be seen from the above equation, when the tightening torque T is increased, the tensile stress σ8 of Pol] also increases, and the bolt 6 is pulled in the direction of the arrow as shown in Figure 5, so the diameter is reduced. ,
Clearance 9 will increase. That is, even if a reamer bolt is used as the tightening bolt 6 and the tightening torque is increased in an attempt to reduce the slip on the shaft coupling surface, the increase in the tightening torque will conversely lead to an increase in the clearance 9. It was not possible to prevent the occurrence of slippage.

[Purpose of the invention]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a shaft coupling for a rotating machine that provides sufficient tightening torque and substantially reduces the clearance between the bolt hole and the tightening bolt to prevent slipping of the coupling surface. .

[Summary of the invention]

In order to achieve this object, the present invention includes a pair of shaft joint flanges that are joined to each other and have bolt holes passing through them, a tightening bolt that passes through the bolt holes, and an outer periphery of the tightening bolt and the J located in the gap between the hole and the hole:
a thin-walled cylindrical sleeve that is fitted onto the bolts and whose overall length is longer than the axial length of the pair of shaft joint flanges; The present invention is characterized by comprising a tightening nut that is elastically deformed within the gap.

[Embodiments of the invention]

Hereinafter, an embodiment of a shaft joint for a rotating machine according to the present invention will be described with reference to FIGS. 1 to 4, with the same parts as in FIG. 5 being denoted by the same reference numerals.

In FIG. 1, a pair of shaft joint flanges 1 and 2 face each other at a joint surface 3, and each flange 1.2 is provided with holes Jζ unipoles 1 to 7L4.5 that pass through both flanges. Of course, pol I to hole 4.5 are attached to flanges 1 and 2, respectively.
A plurality of them are provided at approximately equal angular intervals in the circumferential direction. A tightening bolt 6 is inserted into the holes 1 to 4 and 5, and a thin cylindrical metal sleeve 1 is attached to the outer periphery of the tightening bolt 6.
0 is inserted. That is, the sleeve 1 is positioned in the gap 9 between the outer periphery of the tightening bolt 6 and the bolt hole 4.5.
0 is placed. The length of this sleeve 10 is set to be larger than the axial length of the pair of shaft joint flanges 1.2, that is, the total length J of the bolt holes 4.5, by a predetermined amount. A tightening nut 7.8 is threaded onto both ends of the tightening bolt 6.

Since the shaft joint of the present invention has such a configuration, when the tightening nut h7.8 is tightened to the predetermined torque of 1 to torque from the state shown in Fig. 1, it will become as shown in Fig. 2. The sleeve 10 is elastically deformed in the direction of the arrow. In detail, the sleeve 10 is
The small diameter portion 6a near both ends of the tightening bolt l-6 is pressed against the small diameter portion 6a, and the center portion 6 of the tightening bolt 6 is
At b, it is elastically deformed so as to come into pressure contact with the bolt hole 4.5.

In this way, when tightening the tightening nut 7.8, use the tightening port 1.
Even if the diameter of -6 becomes smaller and the clearance 9 becomes larger, the elastically deformed sleeve 10 comes into pressure contact with the tightening bolt 6 and the holes 1 to 4, 5, and this enlarged clearance 9 is substantially reduced. Due to the filling, displacement of the joint due to the clearance 9 is prevented.

Incidentally, since the deformation of the sleeve 10 is an elastic deformation, the sleeve 10 will be restored to its original shape by loosening the tightening nut 7.8.

Figure 3 shows a modification of the thin-walled cylindrical sleeve.
The sleeve 11 has a plurality of circumferential grooves 12 formed on its outer circumference, and a plurality of circumferential grooves 13 formed on its inner circumferential surface.

These outer circumferential grooves 12 and inner circumferential grooves 13 are arranged alternately in the axial direction of the sleeve. The other configurations are the same as those in FIG. Insert this grooved sleeve 11 into the tightening bolt as shown in Fig. 1, and tighten the nut.
As shown in FIG. 4, the grooved sleeve 11 has an outer circumferential groove 1.
2 and the circumferential groove 13, are elastically deformed into a wave shape, and are pressed into contact with the bolt hole 4.5 and the bolt 6. Since the grooved sleeve 11 is thus elastically deformed into a wave shape, the pressure contact area increases and the slip prevention effect of the joint surface is enhanced.

Note that the outer circumferential grooves 12 and the inner circumferential grooves 13 are not necessarily arranged alternately, and the shape of the grooves is not limited to rectangular shapes, but various shapes such as semicircular, triangular, and polygonal shapes can be used.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, a thin cylindrical sleeve longer than the axial length of the shaft coupling flange is inserted into the tightening port 1-, and the sleeve is tightened at the same time as the shaft coupling flange is tightened with the tightening nut. Since it is elastically deformed and brought into pressure contact with the tightening bolt and the hole I, it is possible to reliably prevent displacement of the joint surface and ensure stable operation of the rotating machine.In particular, the shaft joint of the rotating machine according to the present invention is characterized by the stable operation of the rotating machine. Compared to the previous version, the sleeve is simply added, so there is no substantial cost increase, and it also has the advantage of being applicable to shaft joints of existing rotating machines.

[Brief Description of the Drawings] Figures 1 and 2 are sectional views showing an embodiment of a shaft coupling for a rotating machine according to the present invention, and Figure 1 shows the state before tightening with a tightening nut. , Figure 2 shows the state after tightening, Figure 3 is a partially cutaway front view showing a modified example of the sleeve, and Figure 4 shows a shaft coupling using the sleeve in Figure 3. 5 is a sectional view showing a shaft coupling of a conventional rotating machine. 1.2... Pair of shaft joint flanges, 4.5... Bolt hole, 6... Tightening bolt, 7.8... Tightening nut,
9...Clearance, 10.1.1...Sleeve,
12゜13...Circumferential groove. Applicant's agent Kiyoo Inomata/Koqin 2 Koqin 34 acts 4 Xi

Claims (1)

[Scope of Claims] 1. A pair of shaft joint flanges that are joined to each other and have bolt holes passing through them, a tightening bolt passing through the bolt holes, and an outer periphery of the tightening bolt and the bolt hole. a thin-walled cylindrical sleeve that is fitted into the bolt so as to be positioned in the gap between the two and has an overall length longer than the axial length of the pair of shaft joint flanges; A shaft joint for a rotating machine, comprising a tightening nut that tightens the flange and elastically deforms the sleeve within the gap. 2. The shaft joint for a rotating machine according to claim 1, wherein the sleeve is provided with a plurality of circumferential grooves. 3. The plurality of circumferential grooves are carved on the outer and inner circumferential surfaces of the sleeve, and the circumferential grooves on the outer circumferential side and the circumferential grooves on the inner circumferential side are formed in the longitudinal direction of the sleeve. The shaft joint for a rotating machine according to claim 2, wherein the shaft joints are arranged alternately.