JPS59222050A - Cylindrical rotor - Google Patents

Abstract

PURPOSE:To prevent fretting corrosion of a rotor shaft due to the relative slip between a wedge and a wedge slot shoulder by forming a reces at the position near the contacting surface of the shoulder of with the axial end of the wedge. CONSTITUTION:In the cylindrical rotor of a turbine generator, a rotor winding 3 is wound in a plurality of axial slots 2 formed on a cylindrical core 1, and wedges 4 which are axially divided are mounted in the wedge slots 5 of a slot outlet to retain the winding 3. A slotlike recess 8 parallel to the contacting surface 7 is formed at the position near the contacting surface 7 of the wedge slot shoulder 6 of the axial end on the wedges 4 arranged in an axially divided manner. In this manner, the flexibility of the portion which is contacted with the shoulder 6 at the end of the wedge 4 increases. Accordingly, the fretting corrosion of the rotor caused by the relative slip between the wedge slot shoulder of the core and the wedge and fatigue strength decrase due to the fretting can be prevented.

Description

TECHNICAL FIELD OF THE INVENTION This invention relates to improvements in long-axis cylindrical rotors, such as turbine generator rotors.

[Technical background of the invention and its problems]

A cylindrical rotor of a turbine generator has rotor windings (3) wound around a plurality of axial slots (2) (only one is shown in the figure) provided in a cylindrical core (1). To prevent the rotor from escaping in the radial direction due to centrifugal force during operation, a wedge (4) divided into multiple pieces in the axial direction is inserted into the wedge groove (5) at the slot outlet.
) and holds down the rotor winding (3). In rotating heavy machinery that operates at high speeds, such as turbine generators, the centrifugal force of the rotor windings is large, and the wedges (4
) has a large contact pressure on the contact surface (7) with the wedge groove shoulder (6).

On the other hand, as the capacity of turbine generators has increased in recent years, rotors have tended to become longer and larger, and bending stress and bending deformation that are repeatedly applied due to deflection and vibration due to their own weight are increasing.

As a result, the wedge (4) and the wedge groove shoulder (6) repeatedly slide with relatively small amplitude while being pressed against each other. In general, abrasion powder is often generated at parts of mechanical structures that come into contact with repeated sliding, and this phenomenon is called fretting corrosion. That is, fretting corrosion is a phenomenon of wear that occurs on the contact surfaces when two contacting objects pressed against each other perform repeated relative sliding motions with minute amplitudes. Furthermore, there are many cases where the fretting corrosion spots become the starting point of fatigue fractures and microcracks occur, and the occurrence of fretting corrosion has a large effect on the fatigue strength of the member and is generally Significantly reduces the fatigue strength of machine-drawn objects.

The contact area between the wedge (4) and the wedge groove shoulder (6) is the cause of fretting corrosion, and has the potential to reduce the fatigue strength of the cylindrical rotor.

Therefore, the present inventor conducted an experiment to determine the effect of fretting fatigue strength on changes in contact surface pressure as the number of rupture cycles, and obtained results as shown in the curve shown in FIG. 2. In other words, it is clear that the higher the contact surface pressure, the lower the number of repeated fractures.

Further, the present inventor investigated the distribution of the contact surface pressure between the wedge (4) and the wedge groove shoulder (6) of a conventional cylindrical rotor, and found that the distribution was as shown by curve a in Fig. 3. discovered. Looking at this curve a, it can be seen that the concentration of pressure is remarkable at the end of the wedge (4).

Based on the results shown in Figures 2 and 3, we believe that reducing the concentration of surface pressure at the end of the rotor (4) is a means of obtaining a highly reliable cylindrical rotor. The inventor discovered.

[Purpose of the invention]

The present invention prevents the occurrence of 7-renting corrosion on the rotor shaft due to the relative slip between the wedge and the wedge groove shoulder, and the accompanying decrease in fatigue strength, thereby improving the reliability of the cylindrical rotation of rotating electric machines. The purpose is to provide children.

[Summary of the invention]

In the present invention, the flexibility of the portion of the wedge end that contacts the wedge groove shoulder is increased by providing the four portions at positions close to the contact surface with the wedge groove shoulder on the axial end surface of the wedge. This prevents the wedge ends from bending freely against the repeated bending deformation caused by the flexure and vibration of the cylindrical rotor due to its own weight, thereby preventing large contact pressure from occurring. This prevents the occurrence of corrosion corrosion and reduces fatigue strength.

[Embodiment of the Invention] An embodiment of the present invention will be described below with reference to FIG. 4. Incidentally, in FIG. 4, the same parts as in FIG. 1 are given the same reference numerals, and their explanation will be omitted.

In this embodiment, a wedge (
4) is provided with four groove-shaped portions (8) parallel to the contact portion (7) at positions close to the contact surface (7) with the lateral groove/F1 portion (6) on its axial end surface. The rest is the same as the conventional example shown in FIG.

Next, the effect will be explained.

The contact surface (7) of the axial end face of the wedge (4) with the wedge groove shoulder (6)
) is a groove-shaped recess parallel to the contact surface (7) (
8), the wedge groove shoulder (
6), so the end of the wedge (4) flexes freely against bending deformation caused by the cylindrical rotor's own weight and repeated vibrations, reducing the contact surface pressure. The distribution becomes as shown by curve a in FIG. 5, and the concentration of surface pressure at the end of the wedge (4), which was shown in the conventional curve a in FIG. 3, is eliminated. Since the depth of the four-way portion (8) is only slightly smaller than the total length of the wedge (4), the increase in the average curved surface 1-E is extremely small. Therefore, it is possible to significantly reduce the contact pressure at the end of the wedge (4), where fretting corrosion is most likely to occur in the past, thereby preventing the occurrence of fretting corrosion and fretting fatigue. , a highly reliable cylindrical rotor is obtained.

It should be noted that the present invention is not limited to the embodiments described above and shown in the drawings, but may include the following without changing the gist thereof:
Of course, it can be implemented with various modifications.

〔Effect of the invention〕

As explained above, according to one aspect of the present invention, the recessed portion is provided at a position close to the contact surface with the wedge groove shoulder portion of the axial end surface of the wedge, thereby reducing the contact between the wedge end portion and the wedge groove/Iq portion. Since the flexible part of the iron core is more flexible, it is possible to prevent fretting corrosion of the rotor caused by relative slippage between the wedge groove shoulder of the core and a decrease in fatigue strength due to fretting, thereby increasing reliability. It is possible to provide a cylindrical rotor for a rotating electrical machine with high performance.

[Brief explanation of the drawing]

Figure 1 is a cutaway perspective view of the main parts showing the cylindrical rotor from J.
Figure IY12 is a graph of experimental values showing the relationship between the contact pressure and the number of repeated fractures when fretting corrosion occurs, and Figure 3 shows the contact pressure distribution between the wedge and wedge groove n1 in Figure 1. FIG. 4 is a cutaway perspective view of essential parts showing an embodiment of the cylindrical rotor of the present invention, and FIG. 5 shows the wedges and wedge grooves h' of FIG. 4.
lγ? It is an explanatory diagram showing the contact surface pressure distribution with l(. 1... Yuto Shin 2- Slot 3...
... Rotor winding 4 ... Wedge 5 ... Wedge
Groove 6... Wedge groove shoulder 7... Contact surface
8...Kobe's agent, patent attorney, Mr. I, Figure 1, Figure 3, Figure 4, and Figure 5, 3 books.

Claims (2)

[Claims] (1) A plurality of axial slots are provided on the outer periphery of the cylindrical core, rotor windings are wound around the slots, and wedges divided into a plurality of pieces in the axial direction are fitted into the wedge grooves at the exits of the slots. A cylindrical rotor holding rotor windings, characterized in that four parts are provided at positions close to contact surfaces with wedge groove shoulders of end faces in the axial direction. (2) The cylindrical rotor according to claim 1, wherein the four parts are groove-shaped parts provided parallel to the contact surface.