JP2018105340A - Shaft sleeve and pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a shaft sleeve that can prevent crevice corrosion.SOLUTION: A shaft sleeve 35 includes: a cylindrical substrate 41; a coating 43 constituting an outer peripheral surface of the shaft sleeve 35; and a barrier layer 46 formed between the substrate 41 and the coating 43. The barrier layer 46 covers the entire inner surface of the coating 43. As the barrier layer 46 constituted of nickel and the like is formed between the substrate 41 and the coating 43, the barrier layer 46 prevents liquid permeating the coating 43 from reaching the substrate 41. Accordingly, crevice corrosion is prevented and the coating 43 is less likely to be detached.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a shaft sleeve attached to a rotating shaft, and more particularly to a shaft sleeve incorporated in a pump for transferring a liquid such as seawater. The invention also relates to a pump incorporating such a shaft sleeve.

  Submersible bearings used in drainage pumps are advantageous in terms of simplifying equipment and facilitating maintenance because they do not require lubricating oil, but the sliding parts of submersible bearings are materials with excellent wear resistance. Must be used. Therefore, ceramic bearings in which a cemented carbide shaft sleeve and a SiC bearing are combined have been developed.

FIG. 9 is a cross-sectional view schematically showing a conventional structure of a shaft sleeve. As shown in FIG. 9, the shaft sleeve 100 includes a cylindrical base material 101 fixed to a rotating shaft (not shown), and a coating 102 formed on the outer peripheral surface of the base material 101 by thermal spraying. For the base material 101, stainless steel having excellent corrosion resistance against liquid is used. The film 102 is formed in a recess formed on the outer peripheral surface of the base material 101. As a thermal spray material for forming the coating 102, at least one of WC (tungsten carbide) and Cr ₃ C ₂ (trichrome dicarbide) is a main component, and the remainder is Ni, Cr, Mo, Co, Fe. What contains the binder which consists of at least 1 and an unavoidable impurity is mentioned.

  When the shaft sleeve 100 rotates, the coating 102 comes into sliding contact with a bearing made of a hard member such as ceramic, and the rotating shaft and the shaft sleeve 100 are rotatably supported by the bearing. The coating 102 made of cemented carbide has excellent wear resistance and corrosion resistance, and can protect the base material 101 made of stainless steel.

JP 2001-82479 A

  However, liquids such as seawater may gradually penetrate the coating 102 and reach the substrate 101. There are fine structural voids between the substrate 101 and the coating 102. When liquid enters the voids, so-called crevice corrosion may occur. In particular, when seawater comes into contact with the interface 103 between the base material 101 and the coating 102 made of stainless steel, crevice corrosion tends to occur.

  Then, an object of this invention is to provide the axial sleeve which can prevent crevice corrosion. Moreover, an object of this invention is to provide the pump provided with such a shaft sleeve.

  In order to achieve the above-described object, according to one aspect of the present invention, there is provided a shaft sleeve fixed to the outer peripheral surface of the rotating shaft, the cylindrical base material, and the coating film constituting the outer peripheral surface of the shaft sleeve And a barrier layer formed between the substrate and the coating, wherein the barrier layer covers the entire inner surface of the coating.

In one embodiment, the base material is made of stainless steel, and the barrier layer is made of a metal that is less susceptible to crevice corrosion than stainless steel.
In one embodiment, the barrier layer is composed of nickel.
In one embodiment, the barrier layer has a uniform thickness.
In one Embodiment, the said base material has the cyclic | annular hollow formed in the outer peripheral surface, and the said barrier layer has covered the whole surface which comprises the said cyclic | annular depression.

  According to one aspect of the present invention, a rotating shaft, an impeller fixed to the rotating shaft, a submerged bearing that rotatably supports the rotating shaft, an outer peripheral surface of the rotating shaft fixed to the underwater bearing, There is provided a pump characterized by comprising the shaft sleeve in sliding contact with the shaft.

  According to the present invention, since the barrier layer made of nickel or the like is formed between the substrate and the coating, the liquid that has permeated the coating cannot be blocked by the barrier layer and reach the substrate. Therefore, crevice corrosion is prevented and the film is difficult to peel off. As a result, the shaft sleeve can exhibit its original performance until the design life is reached, and the reliability of the shaft sleeve is improved.

It is a mimetic diagram showing a vertical shaft pump in which a shaft sleeve concerning one embodiment of the present invention was built. FIG. 2 is an enlarged view showing a shaft sleeve and an underwater bearing shown in FIG. 1. FIG. 3 is an enlarged view of the shaft sleeve shown in FIG. 2. It is a figure explaining 1 process of the manufacturing method of a shaft sleeve. It is a figure explaining 1 process of the manufacturing method of a shaft sleeve. It is a figure explaining 1 process of the manufacturing method of a shaft sleeve. It is a figure explaining 1 process of the manufacturing method of a shaft sleeve. It is a figure explaining 1 process of the manufacturing method of a shaft sleeve. It is sectional drawing which shows the conventional structure of a shaft sleeve typically.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a schematic view showing a vertical shaft pump incorporating a shaft sleeve according to an embodiment of the present invention. The vertical shaft pump is a pump for pumping liquids such as seawater and river water from the suction water tank 5 to the discharge water tank 21. The vertical shaft pump shown in FIG. 1 is an example of a pump in which a shaft sleeve according to an embodiment of the present invention is incorporated, and the shaft sleeve can also be applied to pumps of other configurations.

  As shown in FIG. 1, the vertical shaft pump is connected to an impeller casing 1 having a suction bell mouth 1 a and a discharge bowl 1 b, a pumping pipe 3 for suspending the impeller casing 1 in a suction water tank 5, and an upper end of the pumping pipe 3. The discharge elbow pipe 4, the impeller 10 accommodated in the impeller casing 1, and the rotating shaft 6 to which the impeller 10 is fixed are provided.

  The pump installation floor 22 is connected to the upper part of the suction water tank 5. The pumping pipe 3 extends downward through an insertion port 24 formed in the pump installation floor 22 and is fixed to the pump installation floor 22 via an installation base 23 provided at the upper end of the pumping pipe 3. The rotary shaft 6 extends in the vertical direction through the discharge elbow pipe 4, the pumping pipe 3, and the impeller casing 1. The pump casing 2 includes an impeller casing 1, a pumping pipe 3, and a discharge elbow pipe 4.

  The suction bell mouth 1a opens downward, and the upper end of the suction bell mouth 1a is connected to the lower end of the discharge bowl 1b. The impeller 10 is fixed to the lower end of the rotating shaft 6, and the impeller 10 and the rotating shaft 6 rotate integrally. A plurality of guide vanes 14 are arranged above the impeller 10 (discharge side). These guide vanes 14 are fixed to the inner peripheral surface of the discharge bowl 1b.

  The rotary shaft 6 extends upward through the discharge elbow pipe 4 and is connected to a drive source 18. The drive source 18 is fixed on a gantry 19 fixed to the pump installation floor 22. During operation of the vertical pump, the impeller 10 is located below the liquid level in the suction water tank 5.

  The rotating shaft 6 is rotatably supported by the outer bearing 11 and the underwater bearings 12 and 15. The outer bearing 11 is a rolling bearing such as a ball bearing or a sliding bearing, and the underwater bearings 12 and 15 are sliding bearings. The outer bearing 11 is disposed in the pump casing 2. More specifically, the outer bearing 11 is disposed above the discharge elbow pipe 4.

  The underwater bearing 12 is accommodated in the discharge bowl 1 b and is disposed above the impeller 10. The support member 7 that supports the underwater bearing 12 is fixed to the inner surface of the bowl bush 13, and the bowl bush 13 is supported by the impeller casing 1 via a guide vane 14. The underwater bearing 15 is disposed in the pumping pipe 3. The underwater bearing 15 is supported by a plurality of support members 32, and these support members 32 are fixed to the inner surface of the water pump pipe 3. A shaft sleeve 35 according to an embodiment of the present invention is fixed to the rotating shaft 6. The shaft sleeve 35 and the rotating shaft 6 rotate integrally.

  The vertical pump transfers the liquid in the suction water tank 5 to the discharge water tank 21. That is, when the impeller 10 is rotated through the rotating shaft 6 by operating the drive source 18, the liquid in the suction water tank 5 is sucked from the suction bell mouth 1a, and the discharge bowl 1b, the pumping pipe 3, and the discharge elbow pipe. 4, and the discharge water tank 21 through the discharge pipe 20.

  The discharge pipe 20 extends from the discharge elbow pipe 4 to the discharge water tank 21. The liquid level of the discharge water tank 21 is located above the discharge elbow pipe 4. A gate valve 25 is arranged in the middle of the discharge pipe 20, and the gate valve 25 is opened during normal operation of the vertical shaft pump. When the vertical shaft is stopped, the gate valve 25 is closed to prevent the liquid from flowing back from the discharge water tank 21 to the suction water tank 5 through the discharge pipe 20. Instead of the gate valve 25, a check valve may be provided. Further, a flap valve may be arranged at the discharge end of the discharge pipe 20.

  FIG. 2 is an enlarged view showing the shaft sleeve 35 and the underwater bearing 15 shown in FIG. The shaft sleeve 35 has a cylindrical shape and is fixed to the outer peripheral surface of the rotating shaft 6. The underwater bearing 15 is disposed at the same height as the shaft sleeve 35 and supports the rotary shaft 6 via the shaft sleeve 35. More specifically, when the rotary shaft 6 and the shaft sleeve 35 rotate, the outer peripheral surface of the shaft sleeve 35 comes into sliding contact with the inner peripheral surface of the underwater bearing 15. A minute gap is formed between the outer peripheral surface of the shaft sleeve 35 and the inner peripheral surface of the underwater bearing 15. The liquid existing in the pumping pipe 3 (see FIG. 1) passes through this gap to lubricate the shaft sleeve 35 and the underwater bearing 15.

  The shaft sleeve 35 includes a cylindrical base material 41, a coating 43 constituting the outer peripheral surface of the shaft sleeve 35, and a barrier layer 46 formed between the base material 41 and the coating 43. Both edges of the barrier layer 46 are exposed to the outside of the shaft sleeve 35, and the exposed edges are in contact with the coating 43. In this embodiment, the shaft sleeve 35 is arranged vertically, and the coating 43 is located at the same height as the underwater bearing 15. The exposed edge of the barrier layer 46 is located above and below the underwater bearing 15. During operation of the vertical shaft pump, only the coating 43 contacts the underwater bearing 15, and the barrier layer 46 and the base material 41 do not contact the underwater bearing 15.

  In order to allow the liquid to pass through the gap between the shaft sleeve 35 and the underwater bearing 15 without stagnation, the exposed edge of the barrier layer 46 and the outer peripheral surface of the coating 43 are preferably in the same plane. . The exposed edge of the barrier layer 46 and the outer peripheral surface of the coating 43 constitute the outer peripheral surface of the shaft sleeve 35.

  FIG. 3 is an enlarged view of the shaft sleeve 35 shown in FIG. The base material 41 is made of a metal such as stainless steel. In the present embodiment, stainless steel having corrosion resistance against liquid is used. The film 43 and the barrier layer 46 are formed over the entire circumference of the substrate 41. On the outer peripheral surface of the base material 41, an annular recess 51 extending over the entire circumference is formed. The barrier layer 46 covers the entire surface constituting the recess 51 and covers the entire inner surface of the coating 43.

The coating 43 is formed on the outer surface of the barrier layer 46 by thermal spraying. As the thermal spray material for forming the coating 43, WC (tungsten carbide), W ₂ C, Cr ₃ C ₂ (trichrome dicarbide), Cr ₇ C ₃ , Cr ₂₃ C ₆ , NbC (niobium carbide) which are carbide ceramics. , And TiC (titanium carbide) containing at least one binder as a main component, and the remainder containing at least one of Ni, Cr, Mo, Co, and Fe and inevitable impurities. WC and / or Cr ₃ C ₂ are preferably used from the viewpoint of having high wear resistance. Examples of the thermal spraying method include high-speed flame spraying, but other types of thermal spraying such as low-pressure plasma spraying and explosive spraying that can spray a cermet material may be used.

  Since the barrier layer 46 exists between the base material 41 and the film 43, the base material 41 and the film 43 do not come into contact with each other. The barrier layer 46 is made of a metal that is less susceptible to crevice corrosion than stainless steel, which is the material of the base material 41. In the present embodiment, the barrier layer 46 is made of nickel. Nickel is a metal that is less susceptible to crevice corrosion than stainless steel. Therefore, even when the liquid penetrates the film 43 and reaches the barrier layer 46, crevice corrosion hardly occurs at the interface between the film 43 and the barrier layer 46. The liquid is blocked by the barrier layer 46 and cannot reach the substrate 41. Therefore, crevice corrosion is prevented and the film is difficult to peel off. As a result, the shaft sleeve can exhibit its original performance until the design life is reached, and the reliability of the shaft sleeve is improved. As a material for the barrier layer 46, in addition to nickel, Cr (chromium), Mo (molybdenum), zirconia, Ni-based alloy, Cu (copper), Cu alloy, Ti (titanium), Ti alloy, or the like may be used. .

  The barrier layer 46 preferably has a uniform thickness throughout. This is because when force is applied to the film 43 from the underwater bearing 15, the force is evenly dispersed in the barrier layer 46, and local stress can be prevented from being generated. The thickness of the barrier layer 46 is not particularly limited, but the barrier layer 46 has such a thickness that the sprayed material does not penetrate the barrier layer 46 when the sprayed material is sprayed onto the barrier layer 46.

  The barrier layer 46 made of nickel can be formed by plating. More specifically, the base material 41 made of stainless steel is plated with nickel, and the barrier layer 46 made of nickel is formed on the entire surface of the recess 51. Since the barrier layer 46 formed by plating has a uniform thickness, it is preferable to form the barrier layer 46 using plating.

  The shaft sleeve 35 of the present embodiment is manufactured as follows. In step 1, as shown in FIG. 4, a cylindrical base material 41 is prepared. In step 2, as shown in FIG. 5, a cutting tool (not shown) is pressed against the outer peripheral surface of the base material 41 while rotating the base material 41 around its axis, An annular recess 51 is formed over the entire circumference. More specifically, the outer peripheral surface of the base material 41 is cut so that a bottom surface 51a of the recess 51 and two inclined surfaces 51b extending from the bottom surface 51a to the outer peripheral surface of the base material 41 are formed. The angle of the inclined surface 51b with respect to the bottom surface 51a parallel to the axis of the substrate 41 is 45 degrees. The inclined surface 51b is formed to ensure that the thermal spray material is in close contact with the end portion of the barrier layer 46 in the thermal spraying described later.

  In step 3, as shown in FIG. 6, the barrier layer 46 is formed on the entire surface of the recess 51 including the bottom surface 51a and the inclined surface 51b. In this embodiment, the base material 41 is plated with nickel, and the barrier layer 46 made of nickel is formed on the entire bottom surface 51 a and the inclined surface 51 b of the recess 51. The barrier layer 46 has a bottom surface 46 a formed on the bottom surface 51 a of the recess 51 and an inclined surface 46 b formed on the inclined surface 51 b of the recess 51. The angle of the inclined surface 46b with respect to the bottom surface 46a parallel to the axis of the base material 41 is also 45 degrees.

  In step 4, as shown in FIG. 7, a spray material is sprayed onto the barrier layer 46 to form a coating 43 on the entire bottom surface 46 a and the inclined surface 46 b of the barrier layer 46. In this step 4, the thermal spray material is sprayed until the thermal spray material rises from the edge of the barrier layer 46. The thermal spray material is sprayed from a direction perpendicular to the entire barrier layer 46. Since the bottom surface 46a and the inclined surface 46b of the barrier layer 46 can receive a jet of the thermal spray material, the thermal spray material once sprayed on the barrier layer 46 receives the pressure of the subsequent thermal spray material to the bottom surface 46a and the inclined surface 46b. Strong adhesion is possible. That is, the anchor effect is obtained by the entire bottom surface 46a and the inclined surface 46b.

  In step 5, as shown in FIG. 8, surface processing such as grinding is performed on the barrier layer 46 and the coating 43 to smooth the exposed edge of the barrier layer 46 and the outer peripheral surface of the coating 43. The shaft sleeve 35 according to this embodiment is manufactured through the above manufacturing steps.

  The embodiment described above is described for the purpose of enabling the person having ordinary knowledge in the technical field to which the present invention belongs to implement the present invention. Various modifications of the above embodiment can be naturally made by those skilled in the art, and the technical idea of the present invention can be applied to other embodiments. Accordingly, the present invention is not limited to the described embodiments, but is to be construed in the widest scope according to the technical idea defined by the claims.

DESCRIPTION OF SYMBOLS 1a Suction bell mouth 1b Discharge bowl 1 Impeller casing 3 Pumping pipe 4 Discharge elbow pipe 5 Suction water tank 6 Rotating shaft 10 Impeller 11 Outer bearing 12, 15 Underwater bearing 13 Bowl bush 14 Guide vane 18 Drive source 19 Mounting base 20 Discharge piping 21 Discharge Water tank 22 Pump installation floor 23 Installation base 24 Insertion port 25 Gate valve 32 Support member 35 Shaft sleeve 41 Base material 43 Film 46 Barrier layer 51 Annular depression

Claims (6)

A shaft sleeve fixed to the outer peripheral surface of the rotating shaft,
A cylindrical substrate;
A film constituting the outer peripheral surface of the shaft sleeve;
A barrier layer formed between the substrate and the coating;
The shaft sleeve, wherein the barrier layer covers the entire inner surface of the coating.   2. The shaft sleeve according to claim 1, wherein the base material is made of stainless steel, and the barrier layer is made of a metal that is less susceptible to crevice corrosion than stainless steel.   The shaft sleeve according to claim 2, wherein the barrier layer is made of nickel.   The shaft sleeve according to any one of claims 1 to 3, wherein the barrier layer has a uniform thickness. The base material has an annular depression formed on the outer peripheral surface thereof,
The shaft sleeve according to any one of claims 1 to 4, wherein the barrier layer covers the entire surface constituting the annular depression. A rotation axis;
An impeller fixed to the rotating shaft;
An underwater bearing that rotatably supports the rotating shaft;
A shaft sleeve fixed to the outer peripheral surface of the rotating shaft and in sliding contact with the underwater bearing;
6. The pump according to claim 1, wherein the shaft sleeve is the shaft sleeve according to any one of claims 1 to 5.

Images