JPS6349086B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to submersible bearings used in liquids and gases, and in particular, submersible bearings that are operated under non-lubricated conditions in gas during startup and shutdown, and in water or slurry during steady operation. This invention relates to submersible bearings used in vertical shaft pumps or oblique shaft pumps. Conventionally, rubber bearings, lead bronze bearings, and the like have been used as submersible bearings for vertical shaft pumps and oblique shaft pumps.
However, when starting these pumps,
Submersible bearings are often placed in gas, making it difficult to start them up as they are. The reason is that both rubber bearings and metal bearings such as lead bronze,
When used in water or when lubricated with water or oil, it exhibits extremely stable sliding characteristics, but when used in gas, that is, under unlubricated conditions, the sliding parts generate intense heat, causing damage to the bearing. This is because they are quickly damaged. Therefore, in conventional vertical shaft pumps and oblique shaft pumps, in order to protect the submersible bearings from operation under unlubricated conditions at startup, it is necessary to supply lubricating oil to the sliding parts of the bearings or inject water into the bearing parts, etc. He had been hired. This water injection device for the bearing will be explained with reference to FIGS. 1 and 2. FIG. 1 is a vertical cross-sectional view of a conventional vertical shaft pump equipped with a device for injecting water into the bearing part. 1 is the outside water level, and the vertical shaft is positioned so that the impeller 2 is submerged in the outside water level 1. Pumps are installed. The drive motor 3 is installed on the ground for easy maintenance and inspection, and the rotation of the drive motor 3 is transmitted to the shafts 5, 5' via a shaft coupling 4, and is connected to the tip of the shaft 5'. The impeller 2 rotates. Note that 6 is an intermediate shaft joint that connects the shaft 5 and the shaft 5'. As the impeller 2 rotates, water is sucked through the suction bell 7, passes through the discharge bowl 8, the hanging pipes 9 and 10, and is discharged from the discharge elbow 11. 12 and 13 are protection tubes for protecting the shafts 5 and 5' and guiding lubricating water to the upper underwater bearing 14 and the lower underwater bearing 15. In addition, the upper underwater bearing 14 is connected to the underwater bearing support 16.
The lower underwater bearing 15 is supported by ribs 17, 17'. FIG. 2 is an enlarged sectional view of the upper submersible bearing 14 in section A of FIG. A rubber bearing 19 is fixed to the underwater bearing support 16 with a slight gap between it and the outer peripheral surface of the sleeve 18. The inner periphery of the rubber bearing 19 in horizontal cross section is circular, and usually has several vertical grooves for lubricating water. Above rubber bearing 1
9 represents the rotation of the shafts 5, 5';
The radial deflection of the sleeve 18 is limited by sliding the outer circumferential surface of the sleeve 18 against the inner circumferential surface of the rubber bearing 19. When the vertical shaft pump shown in FIG. 1 and FIG.
3, and the two underwater bearings, the upper underwater bearing 14 and the lower underwater bearing 15, are lubricated and protected with water. However, in a vertical shaft pump, shafts 5 and 5'
The length of the bearing can reach several tens of meters, in which case many underwater bearings are used, and the shaft between them is protected by a protective tube. Therefore, there is a drawback that a large amount of equipment costs are required to protect the underwater bearing when the pump is started. Note that although the above explanation of FIGS. 1 and 2 relates to a vertical shaft pump,
Exactly the same problem occurred with diagonal shaft pumps. It is an object of the present invention to eliminate the drawbacks of the prior art described above, to provide a submersible bearing used in both liquid and gas, with stable sliding characteristics under both usage conditions, and to be easy to manufacture. In particular, as a submersible bearing for a vertical shaft pump and a diagonal shaft pump, the submersible bearing part is placed in gas when the pump is started, so that the submersible bearing can be started under non-lubricated conditions. To provide an underwater bearing that exhibits good sliding characteristics even during steady operation after startup, and also exhibits stable sliding characteristics not only in fresh water but also in liquids with good conductivity such as seawater and slurry liquid. It is in. In order to achieve this object, the present invention uses cemented carbide containing tungsten carbide (WC) for the stationary side member and silicon nitride (Si ₃ N ₄ ) for the rotating side member.
Alternatively, they are each made of silicon carbide (SiC) ceramics, and are characterized in that the ceramics are divided into segments and attached to the circumferential surface of the rotating side member in an annular arrangement. Hereinafter, the present invention will be explained in detail with reference to Examples. First, we will explain the materials used for the rotating and stationary sides of underwater bearings, which is one of the features of the present invention. , for example, "Rubber bearings - stainless steel shaft sleeves" or "Carbon-containing Teflon (trade name)"
In the case of "bearings - stainless steel shaft sleeves", the sliding properties in fresh water are excellent, but they cannot be used at all under non-lubricated conditions, and "carbon bearings or carbon-containing copper alloy bearings - stainless steel" In the combination of "steel shaft sleeve", when the underwater bearing part is immersed in a slurry liquid containing silica sand or alumina particles, the sliding surface is quickly damaged, and the result is not necessarily satisfactory. Therefore, the present inventors used a testing device to examine the sliding characteristics of radial bearings and a vertical pump as shown in Fig. 4 without a protection tube, and tested various parts under fresh water conditions, gas conditions, slurry conditions, and seawater conditions. Alternatively, we investigated the sliding characteristics in various usage environments such as seawater conditions containing slurry, and found that the material used in the underwater bearing of the present invention as described above is the most excellent. Table 1 shows the data obtained as a result of the sliding test.

[Table] Stainless steel...SuS304 Stainless steel cemented carbide...JIS containing 90% or more WC
5501 G class No. 3 hardfacing material...Slurry water containing 35% WC...average particle size 80μ, maximum particle size 100μ
Water slurry containing 0.3% by weight of SiO ₂ - River water... Water containing 0.3% by weight of river sand + 0.3% by weight Al ₂ O ₃ (max 100μ av80μ) Seawater + slurry...SiO ₂ with av80μ, max 100μ
03% by weight of seawater In Table 1, Nos. 1 and 2 are the constituent materials of the underwater bearing of the present invention, and Nos. 3 to 9 are the combinations of conventional underwater bearing materials and underwater bearing materials for comparative tests. It's a combination. The symbols in the evaluation column are as follows: ◎...Sufficient durability (16,000 hours or more) 〇...Can be used for practical purposes (8,000 hours or more) △...Can be used depending on conditions ×...Cannot be used It shows the results of a comprehensive evaluation of various factors such as friction coefficient, wear resistance, and seizure resistance. FIG. 3 is a diagram showing the sliding characteristics of the bearing, with the horizontal axis representing the operating time and the vertical axis representing the friction coefficient.
Sliding speed 2.5 m/s, surface pressure rubber bearing - 6.3 Kgf/cm ² (represented by the symbol x) for stainless steel SUS304, 67 Kgf/cm for silicon nitride ceramic bearing - cemented carbide (90% WC) ² (Invention 1 represented by the symbol 〇), silicon carbide ceramic bearings - 67Kgf/ for cemented carbide (90% WC)
cm ² (invention 2) and 42Kgf/cm ² (invention 2'), respectively. As is clear from Table 1 and Figure 3 above,
In the underwater bearing of the present invention, the stationary side member and the rotating side member are respectively made of cemented carbide (containing tungsten carbide) and silicon nitride ceramics or silicon carbide ceramics, and the sliding surfaces can be in air, fresh water, silica sand, It can be seen that it exhibits extremely stable sliding characteristics even in slurry liquid containing alumina particles. In addition, in the present invention, the nitride or silicon carbide ceramics constituting the rotation side member should be as easy to install as possible and should be used for the fixed side sliding surface due to its mechanical properties such as tensile strength, fragility, and coefficient of linear expansion. Therefore, it is desirable to use it as a sliding member on the bearing side, which is a fixed side member, and it is desirable to use the other cemented carbide as a sliding member on the shaft side, which is a rotating side member. In addition, the cemented carbide used in the tests shown in Table 1 and Figure 3 was
It is equivalent to JIS H5501G type No. 3, but 90
A cemented carbide containing tungsten carbide (WC) in a weight percent or more has good and stable sliding properties as shown in Table 1 and FIG. 3. Next, an embodiment of the underwater bearing of the present invention using the above-mentioned bearing material will be described with reference to FIGS. 4 to 6c. FIG. 4 is a longitudinal cross-sectional view of the conventional vertical shaft pump shown in FIG. 1 to which the submersible bearing of the present invention is applied. Since the water injection device and the rib 17 supporting the lower underwater bearing 15 are no longer necessary, they are not provided, resulting in an extremely simple structure.
Moreover, both the upper and lower underwater bearings 14, 15
However, it can be seen that it is much smaller than the conventional one. As mentioned above, the reason why underwater bearings can be made smaller by applying the present invention is that, as is clear from FIG. This is because it can withstand the above), making it possible to reduce the sliding area. FIG. 5 is an enlarged cross-sectional view of the underwater bearing part in part B of FIG. It is designed to rotate as a unit. In addition, the underwater bearing support 16 includes
A ceramic bearing 23 divided into segments is attached through the metal case 22, and each of the ceramic pieces divided into segments is fitted into a fitting hole formed inside the metal case 22. The ceramic pieces are arranged in an annular shape so that the inner circumferential surface of each ceramic piece is in close to line contact with the outer circumferential surface of the shaft sleeve 21. Note that this attachment is performed by shrink fitting or adhesive, and each ceramic piece is firmly fixed to the metal case 22. 6a to 6c are cross-sectional views taken along the line -- in FIG. 5, and clearly show how the segments are arranged and attached to the inside of the metal case 22 of the underwater bearing support 16 in an annular manner. has been done. That is, FIG. 6a shows an embodiment in which each segment piece is constituted by a rod-shaped body 23a having a circular cross section, and these segment pieces 23a having a circular cross section are as follows.
A through hole 24a having an arc-shaped cross section is drilled in the axial direction at predetermined intervals inside the metal case 22, and a portion that slides on the outer peripheral surface of the shaft sleeve 21 is left slightly, and the remaining portion is shrink-fitted or glued. It is fixed by. Further, FIG. 6b shows an embodiment in which each segment piece is constituted by a rod-shaped body 23b having a trapezoidal cross section,
Each of these segment pieces 23b is attached to the metal case 2.
It is fixed by shrink-fitting or adhesive into a through-hole 24b having a trapezoidal cross section (dovetail groove shape) which is bored in the axial direction at intervals inside the holder 2. Similarly, FIG. 6c shows an embodiment in which each segment piece is composed of a rod-shaped body 23c having a rectangular cross section,
Each of these segment pieces 23c is attached to the metal case 2.
It is fixed by shrink-fitting or adhesive into through-holes 24c having a rectangular cross section that are bored in the axial direction at intervals inside the shaft sleeve 21, and the sliding surface with the outer peripheral surface of the shaft sleeve 21 has a rectangular cross section. It is formed in an arc shape. According to each of the embodiments shown in FIGS. 6a to 6c, the ceramic bearing 23 attached to the underwater bearing support 16 via the metal case 22 is divided into segments and the metal case 22 is divided into segments.
Since they are arranged and attached in an annular manner around the circumferential surface, the following functions and effects are achieved. () Since the contact between each ceramic piece and the shaft can be made to be close to line contact, heat generation during air operation can be reduced. This was not possible with conventional bearing materials because the contact area was extremely small and the local surface pressure was extremely high.
This was made possible for the first time by the present invention. () Since the pumped water flows through the relatively wide gaps between the ceramic pieces divided into segments, foreign matter in the handled liquid flows in the axial direction, reducing the amount of foreign matter caught in the sliding surface, and reducing the amount of the bearing constituent material. Combined with this, wear resistance is further improved. () When ceramic bearings for large shaft diameters are manufactured in one piece, the material tends to be non-uniform, resulting in poor strength and reliability, and as a result, it becomes expensive. However, by dividing the ceramic into segments as in the present invention, the ceramic itself can be small and can be applied to large bearings, improving reliability and reducing costs. In addition to the above effects, in the embodiment shown in FIG. 6a, since each ceramic piece 23a is formed into a rod-shaped body with a circular cross section, it is easy to process and manufacture. There is no fear of it loosening inward in the radial direction. Similarly, in the embodiment shown in FIG. 6b, each ceramic piece is fitted into a dovetail hole, so there is no risk of it loosening inwardly, and the method (means) for fixing the ceramic piece is made using a high technology. , high reliability is not required, and since each ceramic piece has a wide bottom surface, it has the effect of providing stable support. However, it is difficult to process the grooves and ceramic pieces and achieve the required dimensional accuracy due to their shape. The embodiment shown in FIG. 6c has a shape in which the ceramic pieces are easily separated in the radial direction compared to the above two examples, so the method (means) for fixing the ceramic pieces needs to be highly reliable. It is easier to assemble and process the grooves and ceramic pieces than in FIG. 6b when fixing with adhesive, and it is also easier to achieve accuracy. The above describes an example in which the present invention is applied to a submersible bearing of a vertical shaft pump, but the same effect can be achieved when applied to a diagonal shaft pump, and the invention can also be used as a submersible bearing of other hydraulic machines. Of course it can be done. In addition, it is a bearing device in which the rotating shaft is supported on the fixed side, and it can also be used as an underwater bearing used in liquid or gas. It is installed on the fixed shaft side due to its properties. It goes without saying that the cemented carbide constituting the stationary side member may be one containing tungsten carbide as a main component. As explained above, the present invention provides an underwater bearing used in liquid and gas, in which the rotating side member is made of a cemented carbide made of tungsten carbide.
Furthermore, the fixed side member is made of ceramics such as silicon nitride or silicon carbide, and the ceramics are divided into segments and arranged and attached in an annular manner on the circumferential surface of the fixed side member.
It has extremely stable sliding characteristics even when starting under non-lubricated conditions, that is, sliding in gas, which was impossible with conventional underwater bearings, and it has extremely stable sliding characteristics even under water-lubricated conditions. It maintains good sliding characteristics even when sliding in slurry water made of aluminum and fine alumina particles, so it can be operated under conditions where unlubricated and lubricated conditions repeatedly occur or in abrasive handling fluids. Furthermore, since both ceramics have good insulating properties, if used as a sliding member that operates in a liquid with good conductivity, they can cut off corrosion current and protect surrounding metal members. It will also happen. Furthermore, since it can withstand high surface pressure loads, it is possible to divide the ceramic into segments and make the contact with the shaft close to a line contact.
Heat generation during air operation can be reduced, and the gaps between the divided ceramic pieces can be used as passages for foreign matter in the liquid being handled, which not only protects the sliding surfaces and improves wear resistance, but also Since the ceramic is divided, it can be easily applied to large-sized bearings, and there is no need to manufacture the ceramic by integral molding, resulting in lower costs.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional view of a conventional vertical shaft pump, Fig. 2 is an enlarged sectional view of section A in Fig. 1, Fig. 3 is a diagram showing the sliding characteristics of a bearing, and Fig. 4 is an embodiment of the present invention. A vertical cross-sectional view of a vertical shaft pump to which the submersible bearing of the example is applied, FIG. 5 is an enlarged cross-sectional view of part B in FIG.
Figure c is a sectional view taken along the line -- in Figure 5 and shows a different embodiment. 5'...Rotating shaft, 16...Bearing support, 21...Shaft sleeve, 23...Ceramics, 23a, 23b, 2
3c...Ceramics piece.

Claims (1)

[Claims] 1. In an underwater bearing used in liquid and gas, the rotating side member is made of cemented carbide containing tungsten carbide (WC), and the stationary side member is made of silicon nitride (Si ₃ N ₄ ) or What is claimed is: 1. An underwater bearing comprising a silicon carbide (SiC) ceramic, the ceramic being divided into segments and arranged in an annular manner on the circumferential surface of a stationary member. 2. The underwater bearing according to claim 1, wherein each ceramic piece divided into segments is fixed to a fitting hole provided in a metal case, and the outer circumference of the metal case is supported by a bearing support. 3. The underwater bearing according to claim 1, wherein each ceramic piece divided into segments has a circular cross section. 4. The underwater bearing according to claim 1, wherein each of the ceramic pieces divided into segments has a trapezoidal cross section. 5. The underwater bearing according to claim 1, wherein each ceramic piece divided into segments has a rectangular cross section.