JP4568539B2 - Pump bearing structure - Google Patents

Description

  The present invention relates to a bearing structure for a pump, and in particular, when a load on the bearing is large, when a dry operation such as a pumping-off operation of a preceding standby operation pump is performed, or even when operating conditions are exposed to slurry water. The present invention relates to a pump bearing structure that exhibits excellent sliding characteristics.

  FIG. 5 shows a conventional bearing structure for a pump suitable for a dry operation such as a preceding standby operation of a preceding standby operation pump. The pump bearing structure B includes a metal bearing case 1, a rubber cushioning material 2 fitted to the bearing case 1 via a metal back shell 3, and the cushioning material 2. The bearing 6 is made of ceramic such as silicon nitride, and the inner peripheral surface of the bearing 6 is configured to slide on a shaft sleeve 5 made of cemented carbide that rotates simultaneously with the main shaft 4. In the figure, 8 is a key connection, 9 is a bearing cover, 10 is a bearing stop plate, and 11 is an intermediate bearing base (Patent Document 1).

  The pump bearing structure B configured as described above is applied to, for example, a vertical shaft pump P shown in FIG. That is, the main shaft 4 to which the impeller 13 accommodated in the discharge bowl 12 is fixed is formed by a plurality of pump bearing structures B in the interior of the discharge bowl 12 and the pumping pipe 14 provided above the discharge bowl 12. It is supported rotatably inside.

JP 2002-317814 A (P7, FIG. 7)

  In the pump bearing structure described in Patent Document 1 in which the sliding surface of the bearing is made of ceramic such as silicon nitride and the sliding surface of the sleeve is made of cemented carbide, the wear rate is low because both are hard. . However, the self-lubricating property in the atmosphere between the bearing sliding surface and the sleeve sliding surface is low. For this reason, like the dry operation during the pre-standby operation of the pre-standby operation pump, if they slide in the atmosphere, the friction coefficient between the two increases, and the temperature of the sliding surface rises significantly, The durability of the bearing structure is reduced. It is also possible to use an amorphous carbon film called DLC (Diamond Like Carbon) on the sliding surface, but when exposed to slurry water containing silica sand or alumina particles, the sliding surface can be obtained in a short time. There is a problem that the DLC film that constitutes the material is worn out.

  The present invention solves such a problem, and the object of the present invention is to provide excellent sliding during dry operation such as when the load on the bearing is large or during prior standby operation of the prior standby operation pump. An object of the present invention is to provide a pump bearing structure that exhibits characteristics, exhibits excellent sliding characteristics even under operating conditions exposed to slurry water, and can improve durability.

To achieve the above object, a pump bearing structure according to the present invention is a pump in which a sliding surface is constituted by a rotating shaft or a sleeve fixed to the rotating shaft and a bearing facing the rotating shaft or the sleeve. In the bearing for a bearing, at least one sliding surface of the rotary shaft or the sleeve and the bearing is composed of a sintered body layer containing diamond, and a diamond content of the diamond sintered body layer is in a range of 80 Vol% to 97 Vol%. an inner, and the particle size of the diamond is in the range of 0.5Myuemu～70myuemu, hardness of the diamond sintered body layers Ri der least 30 GPa, the layer thickness of the diamond sintered body layer is 30μm~7000μm It is within the range, and the surface roughness Rmax is 16 μm or less .

  As described above, since the rotating surface or the sliding surface constituting at least one of the sleeve fixed to the rotating shaft and the bearing is a diamond sintered body layer having high hardness and high self-lubricity in the atmosphere, Even if a dry operation is performed in which the rotating shaft or both the sleeve fixed to the rotating shaft and the bearing slide in the atmosphere, the friction coefficient between them does not increase. For this reason, durability of the bearing structure for pumps can be improved. In addition, since the surface of the diamond sintered body layer having high hardness is used as a sliding surface, wear of the sliding surface under operating conditions exposed to slurry water is prevented, and durability of the pump bearing structure is improved. be able to.

  In the present invention, the diamond content of the sintered diamond layer is in the range of 80 Vol% to 97 Vol%, and the diamond particle size is in the range of 0.5 μm to 70 μm. According to this, since the high self-lubricating property of the diamond sintered body layer is maintained, an increase in the friction coefficient can be avoided, the wear resistance can be improved, and the durability of the pump bearing structure can be improved. Thus, it is possible to avoid the adverse effects such as cracking, chipping or peeling, and to reliably form the diamond sintered body layer on the substrate, and to make the Vickers hardness 30 GPa or more.

  Moreover, in this invention, it is preferable that the layer thickness of a diamond sintered compact layer exists in the range of 30 micrometers-7000 micrometers, and surface roughness Rmax shall be 16 micrometers or less. According to this, the wear resistance of the diamond sintered body layer is enhanced, the durability of the pump bearing structure can be improved, and the workability of the diamond sintered body layer can be improved. The durability of the pump bearing structure can be improved by suppressing wear of the mating member that slides on the shaft.

  Furthermore, in the present invention, the diamond sintered body layer has a diamond content of 80 Vol% to 95 Vol%, a diamond sintered body layer has a layer thickness of 70 μm to 5500 μm, and a surface roughness Rmax. Is more preferably 10 μm or less, and the diamond particle size is more preferably in the range of 0.8 μm to 50 μm.

  According to this, the high self-lubricating property of the diamond sintered body layer is more reliably maintained, the friction coefficient is surely avoided, the wear resistance is increased, and the durability of the pump bearing structure is further improved. In addition, it is possible to further improve the workability of the diamond sintered body layer, and avoid the adverse effects such as cracking, chipping or peeling, and more reliably form the diamond sintered body layer on the substrate. it can.

  Furthermore, in the present invention, a structure in which the base material forming the diamond sintered body layer is made of cemented carbide or cermet and the diamond sintered body layer contains the same components as the base material is preferable.

  In the present invention, at least one of the sleeve or the bearing is constituted by a plurality of segments, and the segments are constituted by the base material and the diamond sintered body layer. A structure in which the surface is a sliding surface may be used.

  Further, in the present invention, the sliding surface of the sleeve is a cemented carbide, the bearing is composed of a plurality of segments, the segments are composed of the base material and the diamond sintered body layer, It is preferable to use a structure in which the surface of the bonded layer is a sliding surface of the bearing.

According to the present invention, since the surface of the diamond sintered body layer having high hardness and high self-lubricity in the atmosphere is used as a sliding surface, the load between the sleeve and the bearing is increased in the atmosphere or when the load on the bearing is large. Even if a dry operation is performed in which both slide, the coefficient of friction between the two does not increase, so the wear resistance is improved and the durability of the pump bearing structure can be improved. Furthermore, excellent sliding characteristics such as preventing wear of the sliding surface and improving durability even under operating conditions exposed to slurry water can be exhibited.
In addition, when at least one of the sleeve or the bearing is constituted by a plurality of segments, and this segment is constituted by the base material and the diamond sintered body layer, in addition to the above effects, one member constituting the sliding surface Since the surface area is reduced, processability such as surface finishing of the hard diamond sintered body layer is improved, and a high-quality sliding surface with less unevenness can be economically formed.

  FIG. 1 is a longitudinal sectional view showing an embodiment of the present invention, and FIG. 2 is a sectional view taken along line AA of FIG. In these drawings, a pump bearing structure B includes a bearing 21 constituted by a plurality of segments 20 and an NBR (nitrile rubber) integrally coupled to the outer periphery of the bearing 21 via, for example, an adhesive (not shown). And a cylindrical housing 23 made of stainless steel (SUS304) and fitted on the outer periphery of the pump main shaft 24. The sleeve 25 is fixed to the outer periphery of the pump main shaft 24. The annular housing 23 is fixed to the pump side via a bearing base (not shown).

  As shown in FIG. 3, each segment 20 constituting the bearing 21 includes a base material 20A made of a cemented carbide such as a cobalt base alloy containing tungsten carbide, and a diamond firing formed on the base material 20A. The sleeve 25 is made of cemented carbide such as a cobalt base alloy containing tungsten carbide similar to the base material 20A. The surface of the diamond sintered body layer 20 </ b> B, which is the sliding surface of the bearing 21, is formed in an inward arc shape having a radius of curvature that allows sliding contact with the outer peripheral sliding surface of the sleeve 25. In the figure, reference numeral 27 denotes a cemented carbide layer formed on the sleeve 25 by HIP, and its surface is a sliding surface.

  The diamond sintered body layer 20B in the embodiment contains, for example, 92 Vol% of diamond particles having a particle diameter of 7 μm, the diamond sintered body layer 20B has a thickness of 500 μm, and the surface roughness of the diamond sintered body layer 20B. Rmax is 0.4 μm or less.

  When the pump bearing structure B having the above configuration is applied to the vertical shaft pump P shown in FIG. 6, the diamond sintered body layer 20B having high hardness [Vickers hardness (GPa)] and high self-lubricity in the atmosphere. Therefore, even if a dry operation is performed in which both the outer peripheral sliding surface 27 of the sleeve 25 and the diamond sintered body layer 20B slide in the atmosphere, the friction coefficient between the both 27 and 20B is maintained. Does not rise. For this reason, abrasion resistance is improved and durability of the bearing structure B for pumps can be improved. Further, by using the surface of the diamond sintered body layer 20B having high hardness as a sliding surface, it is possible to prevent wear of the sliding surface (the surface of the diamond sintered body layer 20B) under operating conditions exposed to slurry water. The durability of the pump bearing structure B can be improved.

  Here, when the diamond content of the diamond sintered body layer 20B is less than 50 Vol%, the number of diamond particles decreases, the self-lubricity decreases, the friction coefficient increases, and the durability of the pump bearing structure B increases. Decreases. On the other hand, if the diamond content exceeds 97% by volume, the diamond particles become too much and it becomes difficult to sinter, cracking, chipping or peeling occurs, and the form of the diamond sintered body layer 20B is impaired. Therefore, the diamond content is preferably set within the range of 50 Vol% to 97 Vol%, desirably 55 Vol% to 95 Vol%, and more desirably 60 Vol% to 92 Vol%.

  If the particle size of the diamond particles is less than 0.5 μm, the diamond particles become too fine and wear resistance is lowered, and the durability of the pump bearing structure B is lowered. And when a particle size exceeds 70 micrometers, it will become large too much and it will become difficult to perform a wire-cut process, and workability will worsen. Therefore, the particle size of the diamond particles should be set in the range of 0.5 μm to 70 μm, desirably 0.8 μm to 50 μm, and more desirably 1 μm to 36 μm. By combining the particle diameter range of these diamond particles and the range of the diamond content, the Vickers hardness of the diamond sintered body layer 20B becomes 30 GPa or more.

  Further, if the thickness of the diamond sintered body layer 20B is less than 30 μm, the diamond sintered body layer 20B becomes too thin and wear resistance is lowered, and the durability of the pump bearing structure B is lowered. And when layer thickness exceeds 7000 micrometers, it will become thick too much, processing time will increase remarkably, and workability will worsen. Therefore, the layer thickness of the diamond sintered body layer 20B is set within the range of 30 μm to 7000 μm, desirably 70 μm to 5500 μm, and more desirably 100 μm to 4000 μm.

  When the surface roughness Rmax of the diamond sintered body layer 20B exceeds 16 μm, it becomes too rough and the sleeve 25 made of cemented carbide wears in a short time, so that the durability of the pump bearing structure B is lowered. . Therefore, the surface roughness Rmax of the diamond sintered body layer 20B is set to 16 μm or less, desirably 10 μm or less, and more desirably 6.3 μm or less.

  Examples 1 to 8 of the pump bearing structure B according to the present invention and "processability" of the diamond sintered body layer 20B (hard layer) in Comparative Examples 1 to 7, "cracking, chipping, peeling of the hard layer", Table 1 shows the test results of “durability time” and “state of hard layer after slurry test”. In Table 1, the durability time (h) * indicates that the friction coefficient of the pump bearing structure B is 0.8 when the pump bearing structure B is applied to the vertical shaft pump P shown in FIG. Shown in overtime. Although it mentions for reference, the thing of Examples 3 and 8 has a diamond content of less than 80 Vol%, which is outside the scope of the present invention.

  In Table 1 above, Examples 1 to 8 of the pump bearing structure B according to the present invention have good “workability” of the hard layer, and “cracking, chipping and peeling of the hard layer” do not occur at all. All of the durability times exceeded 50 hours, and the “state of the hard layer after the slurry test” exhibited excellent characteristics such as not being worn out. However, in Comparative Examples 1 to 7, in Comparative Example 1, the hard layer has a diamond content of less than 50 Vol% (40 Vol%), and therefore contains more components than diamond, so the diamond-specific self-lubricity is low. Thus, the friction coefficient is increased, and the durability of the pump bearing structure B is decreased (Note 1). In Comparative Example 2, the diamond layer content of the hard layer exceeds 97 Vol% (98 Vol%). It becomes difficult to tie and cracks, chips or peeling occurs (Note 2). Further, in Comparative Example 3, since the particle diameter of the diamond particles is less than 0.5 μm (0.1 μm), it becomes too fine and wear resistance is lowered, and the hard layer after the slurry test is worn (Note 3). In Comparative Example 4, since the particle diameter of the diamond particles exceeds 70 μm (100 μm), the particles become too large to make wire cutting difficult, and the workability of the hard layer deteriorates (Note 4). In Comparative Example 5, since the surface roughness Rmax of the hard layer exceeds 16 μm (25 μm), the surface of the hard layer becomes too rough and the sliding surface of the sleeve 25 made of cemented carbide is short. Since it wears out over time, the durability of the pump bearing structure B is reduced (Note 5). Furthermore, in Comparative Example 6, since the thickness of the hard layer is less than 30 μm (20 μm), it becomes too thin and wear resistance becomes low, and wear occurs in the hard layer after the slurry test (Note 6). In No. 7, since the hard layer thickness exceeds 7000 μm (10000 μm), it becomes too thick, the processing time increases significantly, the workability of the hard layer deteriorates (Note 7), the stress strain of the hard layer It becomes clear that cracking, chipping or peeling occurs (Note 8).

  In the embodiment described with reference to FIGS. 1 and 2, as shown in FIG. 3, the base material 20A of each segment 20 of the bearing 21 is made of a cemented carbide such as a cobalt base alloy containing tungsten carbide. However, the base material 20A may be formed of a sintered cermet mainly composed of titanium carbide. Moreover, it is preferable that the diamond sintered body layer 20B has a structure in which the same component as the used base material such as a cobalt-based alloy or cermet which is a metal component of the base material 20A is included.

  Further, as shown in FIG. 4, the plurality of segments 20 may be divided in the axial direction. With such a divided structure, the yield when cutting and processing a segment from a single plate is improved, and even if the axis of the pump main shaft 24 is slightly inclined with respect to the axis of the bearing 21, the axial direction The inclination of the pump main shaft 24 can be absorbed by the cooperation of the plurality of segments 20 divided into two and the cylindrical buffer member 22 disposed on the outer peripheral side of the segments 20.

Further, in the embodiment described with reference to FIGS. 1 and 2, the cemented carbide layer 27 is formed on the sleeve 25 fixed to the pump main shaft 24, and the sliding surface of the bearing 21 facing the cemented carbide layer 27 is formed. The sleeve 20 is composed of a plurality of segments 20 having a diamond sintered body layer 20B. The sliding surface of the bearing 21 is made of a cylindrical cemented carbide, ceramic such as silicon nitride, and the sleeve facing the bearing 21. The 25 outer peripheral sliding surfaces 25A may be composed of a plurality of segments 20 having a diamond sintered body layer 20B. In addition, the surface of the rotating shaft 24 may be a sliding surface without using the configuration in which the sleeve 25 is fixed to the rotating shaft 24. Further, it may be formed directly on the surface of the rotating shaft 24, the sleeve 25, or the bearing 21 without being formed on the diamond sintered body layer 20B segment.

It is a longitudinal cross-sectional view which shows embodiment of this invention. It is the sectional view on the AA line of FIG. It is a perspective view which shows an example of a segment. It is a longitudinal cross-sectional view which shows the modification use example of a segment. It is a longitudinal section of a conventional example. It is a longitudinal cross-sectional view which shows the example of application of the bearing structure for pumps.

20 segment 20A base material 20B diamond sintered body layer 21 bearing 24 pump main shaft (rotating shaft)
25 sleeve

Claims (5)

In a bearing for a pump in which a sliding surface is constituted by a rotating shaft or a sleeve fixed to the rotating shaft and a bearing facing the rotating shaft or the sleeve,
At least one sliding surface of the rotating shaft or the sleeve and the bearing is composed of a sintered body layer containing diamond, and the diamond content of the diamond sintered body layer is in a range of 80 Vol% to 97 Vol%, and the particle size of the diamond is in the range of 0.5Myuemu～70myuemu, hardness of the diamond sintered body layers Ri der least 30 GPa,
A bearing structure for a pump, wherein the diamond sintered body layer has a layer thickness of 30 μm to 7000 μm and a surface roughness Rmax of 16 μm or less . In the pump bearing structure according to claim 1,
The diamond content of the diamond sintered body layer is in the range of 80 Vol% to 95 Vol%, the layer thickness of the diamond sintered body layer is in the range of 70 μm to 5500 μm, and the surface roughness Rmax is 10 μm or less. There is also a pump bearing structure in which the diamond particle size is in the range of 0.8 μm to 50 μm . The pump bearing structure according to claim 1 or 2,
The bearing structure for pumps in which the base material which forms the said diamond sintered compact layer consists of a cemented carbide or a cermet, and contains the same component as the said base material in the said diamond sintered compact layer . The pump bearing structure according to claim 3 ,
At least one of the sleeve or the bearing is composed of a plurality of segments, the segments are composed of the base material and the diamond sintered body layer, and the surface of the diamond sintered body layer is a sliding surface. bearing structure for the pump. The pump bearing structure according to claim 3 or 4 ,
The sliding surface of the sleeve is a cemented carbide, the bearing is composed of a plurality of segments, the segments are composed of the base material and the diamond sintered body layer, and the surface of the diamond sintered body layer is A bearing structure for a pump that is a sliding surface of the bearing.

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