JPH0153737B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement of a turbine disk rotation test device, and relates to a turbine disk rotation test device that automatically adjusts the alignment between the disk and the shaft to increase the rotation speed.

Turbine blades are attached to the tip of the turbine disk and are used at high speeds.

Therefore, in actual use, the disk weighs more than a single disk, and the rotating diameter (tip of the blade) also becomes larger, so a large centrifugal stress is generated on the disk, and the disk has a large centrifugal stress during operation. To confirm reliability, a rotation test is conducted in which the disk itself is rotated at a high speed of, for example, 5000 rpm.

In addition to the above reliability check, the disk is heated and rotated at a high speed of, for example, 6000 rpm, and the centrifugal force generated by this causes plastic deformation in the vicinity of the inner hole of the disk, so that residual stress remains after the rotation stops. Residual stress and during actual operation e.g.
A method of strengthening the disk is being implemented to offset the centrifugal force generated at 3000 rpm and reduce the internal stress on the disk.

This principle will be explained in more detail.

As shown in FIG.
When the disk is rotated at high speed, the inner hole diameter d increases due to centrifugal force.

This phenomenon occurs because tensile centrifugal stress is generated inside the disk due to the centrifugal force caused by the rotation of the disk, and the inner hole diameter d also increases due to this centrifugal force.

If this stress distribution is shown at a point O on the disk, it will be like a curve A, with the stress distribution being maximum at the part closest to the inner hole and decreasing closer to the outer periphery of the disk.

When this tensile stress exceeds the descending point of the disk material, plastic deformation occurs near the disk, and even after the rotation is stopped, compressive residual stress remains near the inner hole. becomes.

When a disk made of such a disk is used in an actual turbine, the tensile centrifugal stress generated by rotation is offset by the compressive residual stress near the inner hole, so the strength of the disk against centrifugal force is reduced. Can be strengthened.

This relationship is shown in FIG. In the figure, the 0 point is the point where the inner hole is located, as shown in Figure 1, and the y
The axis indicates the radial position of the disk with the 0 point as the origin, and the x-axis is the tensile stress axis with the 0 point being 0 stress. Curve A is the tensile stress generated by the rotation of the disk during turbine operation, and curve B is the compressive residual stress given to the disk in advance. During rotation of the disk, they act in opposite directions, and a resultant stress as shown by curve C acts on the disk during actual operation.

In this way, by subjecting the disk to high-speed rotation in advance and plastically deforming the vicinity of the inner hole, the centrifugal tension generated in the disk during turbine operation due to the effect of compressive residual stress (curve B) generated thereby is reduced. The stress can be reduced from curve A to curve C.

The above-mentioned residual stress cannot be applied to the material within its elastic limit, but is applied at the yield point of the material.

Therefore, in order to apply residual stress to the disc, it is necessary to rotate the disc at an extremely high speed and apply centrifugal stress to the yield point of the disc material.

A conventional turbine disk rotation testing device had a structure shown in FIGS. 3 and 4.

That is, in the conventional rotation testing apparatus shown in FIG.
and tighten the turbine disc 1 to the shaft 2.
It was fixed at

In this rotation test device, when the turbine disk 1 is rotated at high speed, the inner hole of the turbine disk 1 becomes larger due to centrifugal force, and the fixed state with the shaft 2 loosens, causing the turbine disk 1 to
Concentricity with the shaft 2 is no longer maintained, resulting in imbalance and vibration.

Furthermore, it is difficult to shrink-fit the shaft 2 to the turbine disk 1 concentrically, and it is difficult to achieve concentricity with high precision. As a result, when the turbine disk was rotated at high speed, it became unbalanced and caused vibrations.

For these reasons, this device has the drawback of not being able to increase the rotation above 3000 RPM and applying residual stress to the turbine disk, for example when the outer diameter of the disk is 1500 mm. .

Next, in the conventional rotation testing apparatus shown in FIG. 4, a thin cone-shaped portion 2a is provided on the shaft 2, and the turbine disk 1 is fixed to this cone-shaped portion 2a with bolts 7 and nuts 8.

With this configuration, the cone-shaped portion 2a deforms to follow the deformation caused by the centrifugal force of the turbine disk 1, and the concentricity of the turbine disk 1 and the shaft 2 is maintained. Ta.

However, the weight of the shaft becomes large, and especially in the case of a large turbine disk, an increase in the total weight of the rotating body becomes a problem.

In other words, in high-speed rotation, when supporting a large rotating weight and rotating at high speed, there are problems with the strength of the support part against vibrations due to unbalance, and problems with driving power, and there is a limit to the speed of high-speed rotation. be. Moreover, the cone-shaped portion 2a and the turbine disk 1
Since a large centrifugal force is generated near the connection with the cone-shaped portion 2a, there is a problem with the strength of the cone-shaped portion 2a.
The maximum possible rotation speed is determined.

For example, if the outer diameter of the turbine disk is 1500 mm and the pitch diameter of the bolt 7 is 1000 mm, the maximum rotational speed will be 5000 RPM.

For this reason, the turbine disk had the disadvantage that sufficient residual stress could not be applied to it.

In addition, the turbine disk may be heated or cooled for testing, and in such cases, the cone-shaped portion covers the upper half of the turbine disk, making it difficult to heat or cool efficiently and uniformly. The drawback was that it was not possible to do so.

The present invention aims to provide a turbine disk rotation testing device capable of ultra high speed rotation, which solves the above-mentioned conventional drawbacks.

That is, in the present invention, a mortar-shaped tapered hole is formed on both sides of the inner hole of the turbine disk, and a conical protrusion is provided at one end of the shaft to fit into the tapered hole formed on both sides of the inner hole. is inserted into the inner hole of the turbine disk, and a conically shaped bushing is fitted into the other side of the shaft, and between this bushing and the conical protrusion provided on the shaft, pressure is generated by the surface pressure of the tapered hole. The turbine disk is sandwiched between the turbine disks, and even when the turbine disk rotates at high speed and the inner hole becomes large, the turbine disk is held between the surfaces of the tapered holes, and the concentricity with the shaft is maintained. do.

Examples of the present invention will be described below. In the following description, the outline of this embodiment will first be explained using FIG. 6.

In the figure, a mortar-shaped taper hole 13 is formed on both sides of an inner hole 14 of the turbine disk 1 . At one end of one shaft 2, the inner hole 14 is provided.
A conical protrusion 12 that fits into a tapered hole 13 formed on both sides of the shaft 2 is provided, and the shaft 2 is inserted into the inner hole 14.
The conical protrusion 12 and the tapered hole 13 are fitted into each other, and a conical bushing 3 is fitted into the other end of the shaft 2, and a conical bush 3 is inserted between the bush 3 and the protrusion 2. , the turbine disk 1 is clamped by the surface pressure of the tapered hole 13, and the surface pressure is applied to the nut 5 via the disc spring 4 and the spherical washer 6.
This is achieved by tightening the .

With this configuration, even if the turbine disk 1 rotates and the inner hole 14 becomes larger,
Due to the elastic force of the disc spring 14, the taper hole 13 is
The conical protrusion 12 and the bush 3 are pushed in,
The turbine disk 1 is clamped and fixed to the shaft 2, and the concentricity between the two is maintained to eliminate vibrations due to unbalance, allowing the turbine disk 1 to rotate at high speed and applying residual stress. be.

The details will be explained in more detail below. FIG. 5 shows an outline of the rotation test apparatus.

In the figure, turbine disk 1 is connected to shaft 2.
This shaft 2 is fixed to a drive turbine 9
It is connected to the. This drive turbine 9 is fixed on a frame 10 which wraps around the outside of the turbine disk 1 and is fixed on a foundation 11.

FIG. 6 shows the fixing of the turbine disk 1 and shaft 2 in more detail.

In the figure, an inner hole 14 is bored in the center of the turbine disk 1 . A mortar-shaped taper hole 13 is formed on both sides of the inner hole 14 . A conical protrusion 12 that fits into the tapered hole 13 is provided at one end of the shaft 2 . 3 is a bush, which is formed into a conical shape so as to fit into the tapered hole 13. 4 is a disc spring, and 6 is a spherical washer. The tightening force of the nut 5 is evenly transmitted to the disc spring via the spherical washer 6, and the elastic force of the disc spring 4 causes the bush 3 to be evenly compressed. Pressed down by force.

In other words, the turbine blade 1 has a tapered hole 13
It is held by the elastic force of a disk spring 4 by the protruding portion 12 and the bush 3 that fit into each other, and is fixed to the shaft 2 inserted into the inner hole 14. In addition, in the inner hole 14 part,
The diameter of the shaft 2 is smaller than that of the inner hole, and an annular gap is provided.

The operation of this embodiment configured as above will be explained next.

First, the turbine disk 1 is rotated by the drive turbine 9 via the shaft 2 . This rotation speed varies from 5000 to 5000 depending on the purpose of the rotation test.
This is done while controlling the rotation within a range of 20,000 RPM.

When the turbine disk 1 is rotated at high speed,
The inner diameter of the inner hole 14 increases due to the centrifugal force. In such a case, in the mortar-shaped taper hole 13 formed on both sides of the inner hole 14, the fitting surface between the protrusion 12 provided at one end of the shaft 2 and the bush 3 slides, and the elastic force of the disc spring 4 causes the fitting surface to slide. Therefore, the taper hole 13
pushed into.

In this way, the protrusion 12 and the bush 3 are pushed into the tapered hole 13 according to the width of the inner hole 14, and at the same time fix and hold the turbine disk 1 to the shaft 2, the turbine disk 1 and the shaft 2 are
Align the cores concentrically.

Conversely, even if the rotational speed becomes slow and the inner diameter of the inner hole 14 becomes smaller, the bush 3 and the protrusion 12 will continue to maintain their tapered shape while sliding on the fitting surfaces between the taper hole 13, the bush 3, and the protrusion 12. It is pushed out from the hole 13.

In this way, according to the change in the inner diameter of the inner hole 14, the turbine disk 1 is maintained in a fixed state while simultaneously being automatically aligned.

As detailed above, according to the rotating device of the present invention,
A rod-shaped tapered hole is formed on both sides of the inner hole of the turbine disk concentrically with the inner hole, and a conical protrusion that fits into the tapered hole formed in the turbine disk is provided at one end of the shaft. , the shaft is inserted into the inner hole of the turbine disk, a conically shaped bushing is fitted, and the conical protrusion provided on the bushing and the shaft are pressed inwardly toward each other to form a gap between the shaft and the tapered hole. Since the turbine disk is always held in a concentric position by the surface pressure of
The turbine disk can be fixedly held on the shaft and self-aligned at the same time, and vibrations due to unbalance will not occur even if the turbine disk is rotated at high speed.

Therefore, it is possible to apply a centrifugal load to the turbine disk up to its yield point, imparting residual stress, and it is possible to strengthen the strength of the turbine disk against the centrifugal force generated by high-speed rotation.

In this way, solving the problem of vibration in rotating equipment,
The reliability of the rotation test is improved by ensuring that the rotation test of the turbine disk is performed at a rotation speed that matches the purpose of the rotation test, and the reliability of the turbine disk itself is also improved by strengthening the strength of the turbine disk. It has great effects such as improving

Furthermore, compared to conventional means of fixing the turbine disk by shrink fitting or bolt tightening, assembly and disassembly is easier, and heating and cooling of the turbine disk is also easier.In addition to improving operability, the device itself can be made smaller. As a result, less driving power is required, which has a great effect in terms of economy.

[Brief explanation of drawings]

Figures 1 and 2 are diagrams shown to explain the relationship between residual stress and the state in which compressive stress is applied to the disc due to centrifugal force when the disc is rotated at high speed, and Figure 3 and Figure 4 shows a conventional example, Figure 3 is a partially assembled sectional view of the turbine disk fixed to the shaft by shrink fitting, Figure 4 is a partially assembled sectional view of the turbine disk fixed to the shaft by bolting, and Figures 5 and 6 are This is an embodiment of the present invention, and FIG. 5 is a schematic view of the entire device, and FIG. 6 is a vertical cross-sectional view of the fixed portion of the turbine disk and shaft. 1... Turbine disk, 2... Shaft, 4
... Disc spring, 5 ... Nut, 6 ... Spherical washer, 1
2...Protrusion part, 13...Tapered hole, 14...Inner hole.

Claims (1)

[Claims] 1. A rod-shaped tapered hole is formed on both sides of the inner hole of the turbine disk concentrically with the inner hole, and a conical protrusion that fits into the tapered hole formed in the turbine disk is formed at one end of the shaft. The shaft is inserted into the inner hole of the turbine disk to fit the conical protrusion and the tapered hole, and a conically shaped bushing is fitted to the other side of the shaft, and the conical part formed on the bushing and the shaft A self-aligning turbine characterized in that the turbine disk is always held in a concentric position by pressing the shaped protrusions inwardly toward each other and by the surface pressure between them and the tapered hole. Disk rotation test equipment.