JPS6133966B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rotor blade connecting device, and more particularly to a rotor blade connecting device suitable for suppressing vibrations of the rotor blade that occur during rotation of a turbomachine.

The rotor blades of turbomachines are generally long and thin members in the radial direction, so due to the high-speed rotation of the rotor shaft and the collision of high-speed fluid with the rotor blades,
Alternatively, the rotor blades enter the fluid at high speed and receive a reaction force. This reaction force is caused by thermal stress, centrifugal stress,
It is a combination of bending stress and torsional stress, which act simultaneously or individually to cause intense rotor blade vibration,
This may cause blade bending or misalignment. This can result in reduced efficiency, turbine failure, and damage to associated turbine components.

One of the known methods for reducing vibrations of turbine rotor blades will be explained with reference to FIG. That is, in the figure, a turbine wheel 1 is composed of a large number of rotor blades 2, and the rotor blades 2 are installed on a rotor 13 via a dovetail joint 3. Bosses 5A and 5B are integrally formed on the rear surface portion 4A and the ventral surface portion 4B of the rotor blade 2, respectively, along the rotational direction, and small protrusions 6 are provided protruding from the tips of the bosses 5A and 5B, respectively. ing. As shown in FIGS. 2 and 3, sleeves 7 are loosely attached to the opposing small protrusions 6 of adjacent rotor blades to connect the rotor blades 2 to each other. The end surface edge of the small protrusion 6 is formed with a corner R to facilitate the articulation of the sleeve 7.
As shown in FIG. 4, the cross-sectional shapes of the small protrusion 6 and the sleeve 7 are in the form of a large diameter semicircle, an opposing small diameter semicircle, and a straight line connecting these semicircles. The cross-sectional shapes are complementary to each other and have a gap 11 in the direction of the rotation axis and a gap 12 in the radial direction. Fig. 2 shows a state in which the sleeve 7 is inserted at an angle when the rotor blade is stationary, and Fig. 3 shows a state in which the sleeve 7 is aligned in the direction of rotation as the rotor blade tries to untwist when rotating. It shows. When the rotor blade is stationary, the sleeve may be positioned as shown in FIG. 3, and when rotating, it may take an inclined position as shown in FIG. 2 (although the direction is reversed). For this purpose, both ends of the sleeve 7 form roof-like tapered parts.

With the above configuration, the free movement of adjacent rotor blades is restrained by the sleeve 7, and vibrations during rotation are restricted. However, the above-mentioned connecting structure is a structure that utilizes the prying moment of the sleeve 7, and cannot restrict movement in the rotational direction, so it cannot be said to be a sufficiently effective structure in terms of vibration isolation. Furthermore, the above-described structure has point or line contact portions, and cannot be said to be a reliable structure in terms of strength.

It is an object of the present invention to eliminate the above-mentioned drawbacks of the prior art, and to provide a turbine rotor blade with very little deformation, wear, fretting, etc. at the connecting part, very reliable strength, and excellent vibration-proofing effect. The purpose of the present invention is to provide a wing articulation device.

In order to achieve this object, the present invention provides protrusions that protrude from the back and abdomen of the rotor blades along the rotational direction, and attaches a separate body to the tips of the mutually opposing protrusions of adjacent rotor blades. The connector is slidably inserted, and the rotor blade twists back during rotation.
The rotor blades are characterized in that the opposing connectors press against each other on their tapered surfaces to transmit forces in the direction of the rotational axis and in the direction of rotation between the rotor blades, thereby firmly connecting the rotor blades.

The invention will now be explained in detail with reference to the illustrated embodiments.

Each part of the embodiment is shown in FIGS. 5 to 9, and in FIG.
A first protrusion 15 and a second protrusion 14 are integrally provided on the abdomen 4B, respectively. These protrusions are located at the center in the radial direction of each rotor blade, and impenetrable holes 17 having the same cross-sectional shape are bored at their tips. And the first protrusion 1
A first connector 23 and a second connector 16 are slidably fitted into the impervious hole 17 of the second projection 14 and the second connector 16, respectively. Bottom part 3 of opaque tag 17
0 and the bottom portion 27 of each connector 23, 16 are each formed into a planar shape so that they can come into surface contact with each other. The center of the tip of the first connector 23 has a tapered surface 28 facing upstream, and the center of the tip of the second connector 16 has a tapered surface 29 facing downstream and gently protruding into a convex shape. are doing. When the moving blade is stationary, the fifth
As shown in the figure, there is a slight gap between the tapered surfaces of the adjacent connectors, but since the rotor blades during rotation twist back in the direction of arrow 18, the tapered surfaces come into pressure contact with each other. It's summery.

FIG. 6 clearly shows the shapes of the impermeable hole 17 and the second connector 16. In Figure a, the second protrusion 14 protruding from the rotor blade abdomen 4B is a cylindrical body, and the opaque hole 17 of the second protrusion 14 has a small diameter radius on the upstream side (left side in the figure). A cross-sectional shape is formed by the circular portion 19 and a large-diameter semicircular portion 20 facing each other on the downstream side (right side in the figure) and a jaw portion 21 connecting these semicircles with a curved line.

The impermeable hole of the first protrusion 15 (not shown) has the same cross-sectional shape as the impermeable hole of the second protrusion 14, but has a large-diameter semicircular portion located on the upstream side, and its orientation is It's backwards. The figure shows the fitted state between the impermeable hole 17 and the connector (the figure shows the second connector 16), and as is clear from the figure, the connector has a complementary cross-sectional shape to the impermeable hole. It has a small diameter semicircular part 24, a large diameter semicircular part 25, and a jaw part 26, and there is a small gap between them to enable sliding.

Details of the connectors 16 and 23 are shown in FIGS. 7 and 8. As is clear from FIG. 7, the tapered surfaces 28 and 29 of the connectors protrude from the large diameter semicircular portion 25 toward the small diameter semicircular portion 24, and the first and second connectors 23 , 16 may be in a pressed state, as shown in FIG. 8, even if the tapered surface 29 having a gently protruding convex crown is located on the upstream side or on the downstream side.

In FIG. 9, when the rotor blade 2 rotates, a force couple 18 in the direction of the arrow acts to untwist it. As a result, a pair of connectors 16, 23 between adjacent blades contact each other at their tapered surfaces 28, 29. The torsional return force of the rotor blades is generated by restraining the torsional return at the tapered surfaces 28 and 29, which are inclined contact surfaces of a pair of connectors with respect to the rotational direction. Second connector 1 fitted into second protrusion 14 of abdomen 4B
The force acting on 6 is divided into a component force 31 in the rotation direction (longitudinal direction of the protrusion) and a component force 32 in the direction of the rotation axis perpendicular to the rotation direction. The rotational direction component force 31 is supported by the contact portion between the opaque hole bottom 30 of the second protrusion 14 and the bottom 27 of the second connector 16, and the rotational axis direction component 32 is supported by the jaw 21 of the opaque hole 17. The second connector 16 is supported at its contact portion with the jaw portion 26 of the second connector 16. At this time, as shown in Figure 8,
A crown is formed on the tapered surface 29 of the second connector 16, and the opposing tapered surface 28 of the first connector 23 is a flat surface, so the contact portion is approximately at the center of the tapered surface, and uneven contact etc. There's no fear.
Moreover, since the part with a small contact area is the center point of the block, there is no problem in terms of strength, and the component forces 31 and 32 acting on the connector are transmitted through the impermeable hole 17 to each protrusion of the abdomen 4B and the back 4A. 14 and 15. On the other hand, since the impermeable holes 17 of the first protrusion 15 protruding from the back portion 4A of the adjacent rotor blades have a cross-sectional shape that is staggered with the impermeable holes of the second protrusion 14, the first protrusion The rotational direction component and rotational axis direction component of the rotor blade twist return restraining force acting on the first connector 23 fitted into the portion 15 are in the same direction as the respective component forces 31 and 32 acting on the second connector 16. They are opposite and have the same size, and are supported by a mechanism similar to that acting on the first connector 23.

Thus, the torsional return force is supported by the contact portions of the above-mentioned protrusions and connectors, and is caused by the component forces 31, 3 in the rotation direction and rotation axis direction acting on the contact portions.
2 restricts twisting and return, and adjacent rotor blades become connected to each other. When vibration occurs in the turbine rotor blade, the tapered surfaces 28 and 29 of the adjacent connectors 23, the jaws 26 of the connectors, the jaws 21 of the impermeable hole 17 of the projection, and the bottom of the impermeable hole 30 and connector bottom 2
A small amount of sliding accompanied by friction occurs at each contact portion of 7, producing a large damping effect. Also,
Since the contact portion is spread over a wider area and the acting force is greater than in the past, the vibration damping effect of the rotor blade is more greatly exerted.

By applying the above-described connecting structure to adjacent rotor blades one after another, it is possible to realize a connecting structure of rotor blades that is seamlessly connected all around the circumference.

FIG. 10 shows another embodiment of the invention. That is, the spacer 33 is fitted into the bottom part 30 of the impermeable hole 17, and the dimensions can be adjusted by appropriately adjusting the thickness of the spacer 33 without increasing the processing accuracy of the impermeable hole. The advantage in this case is that there is no need to increase processing accuracy, so a reduction in man-hours and, ultimately, a reduction in costs can be expected. There is no difference in the vibration isolation effect of the rotor blade from the previous embodiment.

As explained above, the rotor blade connecting device of the present invention has extremely low deformation, wear, fretting, etc. of the joint portion of the turbine rotor blade, is extremely reliable in terms of strength, and has the effect of improving the vibration isolation effect. .

[Brief explanation of the drawing]

Figure 1 is a partial front view showing the turbine wheel;
3 and 3 are cross-sectional views showing an example of a conventional rotor blade coupling device, FIG. 4 is a cross-sectional view showing the fitted state of the small protrusion and the sleeve shown in the above example, and FIGS. 5 and 6 a are A sectional view and a perspective view showing the embodiment, FIG. 6b is the sixth
The BB arrow view shown in Figure a, Figures 7 and 8 are diagrams for explaining the connector, Figure 9 is a sectional view for explaining the vibration isolation effect of the rotor blade, and Figure 10 is FIG. 3 is a partially sectional view showing another embodiment of the present invention. 2... Moving blade, 4A... Back, 4B... Abdomen, 14... Second protrusion, 15... First protrusion, 16... Second connector, 17... Impermeable hole, 19, 24... Small diameter semicircular part, 2
0, 25... Large diameter semicircular part, 21, 26... Jaw part, 2
3...First connector, 27...Connector bottom, 28, 29
... Tapered surface, 30 ... Impermeable hole bottom.

Claims (1)

[Claims] 1. A first protrusion and a second protrusion are provided on the back and abdomen of a rotor blade implanted on the outer periphery of the rotor, respectively, along the rotor rotation direction, and a large diameter semicircle and a small diameter semicircle are opposed to each other. An impermeable hole having a cross-sectional shape consisting of a part and a jaw part connecting these two semicircles with a curved line is arranged and bored at the tip of the first protrusion with a small diameter semicircular part on the upstream side, and A small-diameter semicircular portion is disposed and bored on the downstream side at the tip of the second protrusion, and a cross section complementary to the impermeable hole is slidably inserted into each impermeable hole of the first and second protrusion. first and second connectors having a shape are fitted, each of the first and second connectors has a tapered surface that can contact each other at each tip, and a tapered surface of one of these connectors has a gently The torsion return couple of the rotor blades that forms the bulge and occurs during turbine rotation causes the first and second opposing blades of adjacent rotor blades to
By pressing the tapered surfaces of the first and second connectors attached to the tip of the protrusion into pressure contact with each other at the center, the load in the rotational direction is retained at the contact area between the bottom of the connector and the bottom of the impermeable hole of the protrusion. A rotor blade connecting device, characterized in that a load in the rotational axis direction is held at a contact portion between the connector and the protrusion impermeable hole, which is constituted by a small-diameter semicircular portion and a jaw portion.