JPS6254961B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a retaining device for a rotor blade mounted on a wheel in an axial flow fluid machine such as an axial flow compressor or an axial flow turbine.

A conventional rotor blade retaining device will be explained with reference to FIGS. 1 to 4, taking the case of an axial flow compressor as an example.

Fig. 1 shows an example of the rotor structure of an axial flow compressor. In the figure, 1 is a wheel having a plurality of dovetail grooves 1a provided at equal intervals in the circumferential direction and extending in the axial direction. are fastened by stacking bolts 2 in number corresponding to the number of compression stages determined by compressor performance. Reference numeral 3 designates a plurality of rotor blades attached to the outer periphery of the wheel 1, and the rotor blades 3 are composed of a dovetail portion 3a attached to the dovetail groove 1a of the wheel 1 and an airfoil portion 3b.

FIGS. 2 and 3 show an example of a conventional rotor blade retaining device. In the figure, 3c is a pawl formed at one end of the dovetail portion 3a of the rotor blade 3 so as to extend in the inner circumferential direction.
Movement to the right in the figure is prevented. 4 is a blade lock inserted between the bottom of the dovetail groove 1a of the wheel 1 and the dovetail portion 3a of the rotor blade 3; the claw side 4a of the blade lock 4 is bent and attached to the side surface of the dovetail portion 3a of the rotor blade 3; Also, the opposite pawl side 4b of this blade lock 4
is also bent and is in contact with the side surface of the wheel 1. Therefore, the blade lock 4 causes the rotor blade 3 to
Since the moving blade 3 is also prevented from moving to the left in FIG. 3, the pawl 3c and the blade lock 4 completely prevent the rotor blade 3 from moving in the axial direction.

In this conventional device, since the plate-shaped blade lock 4 is bent, the bent portion is likely to be damaged, and the device cannot be used safely for a long period of time, which is a drawback in terms of reliability. In addition, moving blade 3
Since the claw 3c must be formed at the blade lock 4, the structure of the rotor blade 3 becomes complicated.
Since the blade lock 4 is used in a plastically deformed state, it also has the disadvantage that the blade lock 4 cannot be reused when the rotor blade 3 is replaced.

FIG. 4 shows another example of the conventional device, in which the moving blade 3 is connected to the dovetail groove of the wheel 1.
After mounting on the rotor blade 3, a set screw 5 is screwed into the mating surface between the bottom surface of the dovetail portion 3a of the rotor blade 3 and the dovetail groove 1a of the wheel 1, thereby preventing the rotor blade 1 from moving in the axial direction. It is something.

In this conventional device, since centrifugal force acts on the rotor blade 3 during operation, a gap is created between the dovetail portion 3a of the rotor blade 3 and the dovetail groove 1a of the wheel 1. Easy to loosen,
Therefore, it has the disadvantage that it cannot be used with confidence. In addition, in this conventional example, if the set screw 5 is screwed in tightly to prevent it from loosening, the damping effect of the rotor blade 3 against vibration is lost, and extremely large vibration stress is generated in the rotor blade 3. It has the disadvantage of being stored away.

The present invention improves the above-mentioned drawbacks of the conventional device, and provides a rotor that is highly reliable, does not impair the damping effect of the rotor blade against vibrations, has a simple structure, and can easily replace each rotor blade. The purpose of this device is to provide a blade slip-off prevention device, in which a pin hole is formed that passes through the wheel rib portion from the dovetail groove of the wheel, and a ring-shaped groove is formed in the wheel rib portion on the inner circumferential side of the pin hole. , and a recess is formed in the bottom surface of the dovetail portion of the rotor blade that faces the pin hole when the rotor blade is installed in the dovetail groove, and a pin is inserted into the pin hole and one end of this pin is inserted into the rotor blade. The pin is fitted into a recess formed on the bottom surface of the dovetail portion of the pin, and a ring spring is attached to the ring-shaped groove to prevent the pin from falling off.

Hereinafter, one embodiment of the rotor blade retaining device of the present invention will be described with reference to FIGS. 5 to 12. Portions with the same reference numerals in each figure are the same parts, and parts with the same reference numerals as in FIGS. 1 to 4 are the same or corresponding parts.

FIG. 5 is a diagram showing the main parts of an axial flow compressor rotor equipped with the device of the present invention. The wheels 1 are fastened with stacking bolts 2 for the required number of wheels corresponding to the number of compression stages determined by the compressor performance.
Dovetail grooves 1a are formed on the outer peripheral surface of each wheel 1 at equal intervals in the circumferential direction and extend in the axial direction, the number of which is equal to the number of rotor blades 3. A dovetail portion 3a is attached. The moving blade 3 is a dovetail part 3
a and an airfoil portion 3b, and when installing the rotor blade 3, the dovetail portion 3a is inserted into the dovetail groove 1a.
Insert from the axial direction. Reference numeral 6 denotes a pin hole formed from the dovetail groove 1a of the wheel 1 through the wheel rib portion 1b, and a ring-shaped groove 7 is formed in the wheel rib portion 1b on the inner peripheral side of the pin hole 6 as shown in FIG. is formed. Although the wheel rib portions 1b are located on both sides of the wheel 1, the pin holes 6 and the ring-shaped grooves 7 may be formed on any one side thereof, and the pin holes 6 are provided on all dovetail grooves 1a. As shown in FIGS. 5 and 6, a recess 8 is formed on the bottom surface of the dovetail portion 3a of the rotor blade 3 at a portion facing the pin hole 6 when the rotor blade 3 is installed in the dovetail groove 1a. In this embodiment, the recess 8 is formed by forming a groove perpendicular to the longitudinal direction of the dovetail portion 3a, but a hole may be formed instead of the groove. After the rotor blade 3 is installed in the dovetail groove 1a, a pin 9 is inserted into the pin hole 6, and one end of this pin 9 is inserted into the recess 8 formed on the bottom surface of the dovetail portion 3a of the rotor blade 3, as shown in FIG. By fitting the ring spring 10 into the ring groove 7, the pin 9 inserted into the pin hole 6 is prevented from falling out. This ring spring 1
0 can have a structure cut at one point as shown in Fig. 8, or a structure cut at two places as shown in Fig. 9 (in this case, the ring spring 1
0 may be composed of two semicircular springs), in short, it is attached to the ring-shaped groove 7 and the pin 9
Any material that can prevent the material from falling off is sufficient. Furthermore, it is clear that the cross-sectional shape of the ring spring 10 is not limited to a circular shape, but may also be rectangular.

Next, the assembling procedure of the device of the present invention described above will be explained in the 10th step.
This will be explained with reference to the drawings and FIG.

As shown in FIG. 10, first, before fastening the wheel 1 with stacking bolts, a ring spring 10 is installed in advance in the ring-shaped groove 7 formed in the wheel rib portion 1b of the wheel 1. Next, after assembling the compressor rotor by fastening the wheel 1 with the stacking bolts 2 as shown in FIG. Insert pin 9 into dovetail groove 1a.
After inserting from the side, push the push rod 11 into the adjacent pin hole 6 to push the ring spring 10 inward, and move the pin 9 inserted into the upper pin hole 6 from the bottom of the dovetail groove 1a. The blade 3 is inserted into the dovetail groove 1a from the axial direction of the rotor to a predetermined position. Next, when the push rod 11 is released, the ring spring 10 returns to the ring-shaped groove 7, so the pin 9
fits into the recess 8 of the rotor blade 3. By repeating this procedure, each part of the rotor blade 3 and the rotor blade retaining device can be attached. When using a ring spring 10 divided into two or more parts as shown in FIG. 9, after assembling the compressor rotor by fastening the wheel 1 with stacking bolts 2, After inserting the rotor into the dovetail groove 1a to a predetermined position and setting the rotor in a horizontal state, as shown in FIG.
Insert the pin 9 into the pin hole 6 of b, attach the semicircular ring spring 10 to the ring groove 7, hold this state and turn the rotor half a turn, and then insert the new lower part in the same way as above. Assembly can be completed by attaching the pin 9 and the semicircular ring spring 10. As described above, using the ring spring 10 divided into two parts makes assembly easier.

By configuring the rotor blade retaining device as described above, the rotor blade 3 is prevented from moving in the axial direction by the engagement between the recess 8 and the pin 9, and thus the rotor blade 3 is prevented from moving in the axial direction during rotation. You can prevent it from slipping out. Also,
Since centrifugal force acts on the pin 9 itself while the rotor is rotating, the pin 9 does not come off the recess 8, and there is no need to apply plastic deformation to the parts that make up the rotor blade retainer, unlike conventional devices. Therefore, it is sufficiently safe in terms of strength, and the present invention is a highly reliable rotor blade retaining device that can withstand long-term use. Further, as shown in the above-described embodiment, since the ring spring 10 is configured to press the bottom surface of the dovetail portion 3a of the rotor blade 3 via the pin 9, the rotor blade 3 is tightly fixed to the wheel 1. In addition, since the sliding of the dovetail contact area between the wheel and the rotor blade is not restricted, the damping effect on the vibration of the rotor blade 3 is not impaired, and therefore the rotor blade 3 is free from large vibrations. This can prevent stress from occurring. By the way, about several dozen rotor blades 3 are attached to each stage, and if the number of rotor blades 3 is multi-stage, there will be a very large number of rotor blades 3, so the production, assembly, maintenance, etc. costs of a complicated rotor blade retaining device will be extremely high. . As shown in this embodiment, the device of the present invention has an extremely simple structure, and the rotor blades 3 can be replaced one by one very easily, so manufacturing, assembly, maintenance, etc. costs are extremely low. be able to. In addition, in order to make it easier to replace each moving blade 3, a hole for inserting the push rod 11 may be specially provided, or a plurality of tension members or the like may be attached to the inner circumference of the ring spring 10. It is also effective to embed the pin 8 from the bottom of the dovetail groove 1a by pulling inward a tension member near the rotor blade to be replaced when replacing the rotor blade.

As described in detail above, the rotor blade slip-off prevention device of the present invention has a pin hole that passes through the wheel rib portion from the dovetail groove, a recessed portion on the bottom surface of the dovetail portion of the rotor blade, and a pin hole that is inserted into the pin hole. The pin is inserted and one end thereof is fitted into the recess, and a ring spring that prevents the pin from falling off is attached to the ring groove, so reliability is high and the rotor blade has a damping effect against vibration. It has the advantage that it is not damaged, has a simple structure, and allows individual rotor blades to be replaced extremely easily.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of essential parts showing an example of an axial flow compressor rotor structure, Fig. 2 is a side view showing an example of a conventional rotor blade retaining device, and Fig. 3 is a view taken along the - line in Fig. 2. , FIG. 4 is a side view showing another example of the conventional device,
5 to 12 are diagrams illustrating an embodiment of the rotor blade retaining device of the present invention, and FIG. 5 is a longitudinal cross-sectional view showing the main parts of an axial flow compressor rotor equipped with the device of the present invention.
Figure 6 is a perspective view showing the structure of the moving blade in detail, Figure 7 is a perspective view of the main parts showing the structure of the wheel in detail, Figure 8 is a perspective view showing an example of a ring spring, and Figure 9 is a ring spring. FIGS. 10 and 11 are perspective views showing other examples of springs, and FIGS. 10 and 11 are views for explaining an example of the assembly procedure. FIG. FIG. 12 is a side sectional view of the main part of the wheel showing the mounted state, and FIG. 12 is a side sectional view of the main part of the wheel showing another example of the assembly procedure. 1... Wheel, 1a... Dovetail groove, 1b
...Wheel rib portion, 3...Rotating blade, 3a...Dovetail portion, 3b...Airfoil portion, 6...Pin hole, 7...
...Ring-shaped groove, 8...Recess, 9...Pin, 10...
...Ring spring.

Claims (1)

[Claims] 1 Axial flow comprising a wheel having a plurality of dovetail grooves provided at equal intervals in the circumferential direction and extending in the axial direction, and a plurality of moving blades having a dovetail part and an airfoil part attached to the dovetail grooves of this wheel. In the type fluid machine, a pin hole is formed that passes through the wheel rib part from the dovetail groove of the wheel, a ring-shaped groove is formed in the wheel rib part on the inner peripheral side of the pin hole, and a rotor blade is attached to the dovetail groove. Sometimes, a recess is formed on the bottom surface of the dovetail portion of the rotor blade opposite to the pin hole, a pin is inserted into the pin hole, and one end of this pin is fitted into the recess formed on the bottom surface of the dovetail portion of the rotor blade. and a ring spring is attached to the ring-shaped groove to prevent the pin from falling off.