JP2009204034A - Sliding bearing unit and pre-standby pump using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bearing sliding member for a pre-standby pump which is free from breakage under long-time dry/wet repetitive and high-load sliding motion. <P>SOLUTION: A sliding bearing unit 2 comprises: a shaft sleeve 4 cylindrically formed of a fiber reinforced ceramics material in which ceramics fibers are bunched into bunched ceramics fibers, the bunched ceramics fibers are braided and laminated in a plurality of layers, and cavities are impregnated with ceramics base materials; and a bearing 3 formed of an oil impregnated porous ceramics material and combined therewith. It is suitably used in a bearing device for the pre-standby pump, which is free from cracking and breakage under long-time dry sliding motion or dry/wet repetitive sliding motion, and which has an operation system for keeping the pump in standby operation. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a sliding bearing unit constituted by a combination of a shaft sleeve for high surface pressure applied to a dry atmosphere and a bearing, and a preceding standby type pump using the sliding bearing unit.

  Conventionally, cemented carbides and ceramics have been widely used as materials used for sliding members such as pump bearings that perform a preliminary standby operation with no water injection.

A sliding member made of a combination of a ceramic fixing member and a cemented carbide rotating member is described in Patent Document 1, for example. Moreover, the sliding member which consists of a carbon fiber composite ceramic sintered compact obtained by sintering ceramics and carbon fiber is described in patent document 2, for example.
JP 2001-173661 A JP-A-5-155665

A cemented carbide combined with a ceramic fixing member as a sliding member shows a stable low dynamic friction coefficient up to a certain surface pressure, but has low toughness as a brittle characteristic. It is known that a rotating device generates a high load surface pressure exceeding an allowable surface pressure due to an increase in vibration due to deterioration over time, an increase in unbalance, and the like. In dry sliding under high surface pressure, an abnormal temperature rise occurs due to an increase in the coefficient of friction due to adhesion wear, and thermal stress and thermal shock may occur due to rapid cooling by the pumped water, which may cause damage. . And a carbon fiber composite ceramic sintered compact can reduce a friction coefficient by combining the carbon fiber which has self-lubricating property, However, Abrasion amount increases. There is a problem that the friction coefficient increases due to the adhesion of minute wear powder accumulated on the sliding surface, and the sliding characteristics deteriorate.

  The present invention relates to a fiber-reinforced ceramic material shaft sleeve in which ceramic fibers are bundled to form a ceramic fiber bundle, and the ceramic fiber bundle is knitted and laminated into a plurality of layers to form a cylindrical shape. It is a combination of a porous ceramic material bearing so as to be able to rotate and slide, and the tensile strength is improved and the toughness is high while maintaining the characteristics such as slidability and wear resistance inherent in ceramics. In addition, because we knit the ceramic fiber bundle that bundles the ceramic fibers, a mesh-like recess is formed in the sliding part, where minute wear powder due to sliding under high surface pressure in a dry atmosphere accumulates, There is no adhesion to the sliding surface and there is no abnormal increase in the coefficient of friction. Furthermore, as the oil content retained inside the oil-impregnated porous ceramic material gradually oozes out to the surface over time and contributes to the lubrication of the sliding portion, the sliding characteristics are improved.

  Oil-impregnated porous ceramics in which a vertical shaft pump using a sliding bearing unit is disposed in a pump casing, and a sliding bearing unit supporting a main shaft having an impeller fixed to the tip is fixed to the pump casing side And a shaft sleeve formed by a fiber-reinforced ceramic material rotating member inserted into the bearing so as to be rotationally slidable. There is no risk of cracking or breakage even when used for long periods of dry sliding or sliding where dry and wet are repeated. Further, when the dry operation is continued for a certain time, the oil content of the fixing member made of the oil-impregnated porous ceramic material contributes to the lubrication of the sliding portion, so that the friction coefficient becomes small and stable. Furthermore, since the friction coefficient does not increase abnormally even when sliding under high surface pressure, it can be applied to a large-diameter pump.

  The sliding member of the fiber-reinforced ceramic material of the present invention is a material in which ceramic fibers are reinforced with a ceramic base material, so that the tensile strength is improved while maintaining the inherent characteristics of ceramics such as slidability and wear resistance. High toughness. In addition, since the ceramic fiber bundle in which the ceramic fibers are bundled is knitted, a mesh-like concave portion is formed in the sliding portion. The minute wear powder caused by sliding under a high surface pressure in a dry atmosphere accumulates in the concave portion, and does not adhere to the sliding surface and does not increase the abnormal friction coefficient. As time passes, the oil retained in the oil-impregnated porous ceramic material gradually oozes out to the surface and contributes to lubrication of the sliding portion, so that the sliding characteristics are improved. Sliding that can be used as a bearing device for large-diameter advanced stand-by pumps with no risk of cracking or breakage even when used for long-time dry sliding under high surface pressure or sliding with dry and wet repeated. It is a member.

  A sliding bearing unit according to the present invention will be described in detail with reference to the drawings. FIG. 1 shows a rotating member of a fiber reinforced ceramic material. A SiC fiber bundle 14 is formed by bundling a plurality of SiC fibers made of SiC ceramics. 14 is knitted and laminated in a cylindrical shape to form a thickness of 3 to 5 mm, and an air gap is impregnated with a SiC ceramic substrate to form a shaft sleeve 4.

  In the examples, the CVI method (Chemical Vapor Infiltration method) is used as a method for impregnating the SiC ceramic substrate, but the RS method (reactive sintering method) is used depending on the type of ceramic fiber and ceramic substrate. / Reaction Sintering, Infiltration Direct Metal Oxidation (Direct Oxidation (Lanxide) Process), PIP (Polymer Impregnation and Pyrolysis), MI (Melt Infiltration / Melt Infiltration), Sol Gel Various ceramic filling methods such as Sol-Gel Technologies) and HIP method (Pressurized Sintering / Hot Isostatic Processing). It can have. As the ceramic material, silicon carbide (SiC), silicon nitride (SiN), alumina (Al2O3), zirconia (ZrO2), titanium carbide, or the like is used.

  The SiC fiber bundle 14 is plain woven as shown in FIG. 2, and is formed so that every other orthogonal SiC fiber bundle 14 is alternately raised and lowered. In the embodiment, it is plain weave, but it may be knitted by knitting, blade knitting or the like. The minute wear powder 17 generated at the time of high surface pressure dry sliding accumulates in the mesh-shaped recess 15 existing on the surface, and therefore does not adhere to the sliding surface 16.

  3 and 4 show the vertical shaft pump 1 in which the sliding bearing unit 2 is constituted by a sliding member according to the present invention. FIG. 3 is a conceptual diagram showing the entirety of the vertical shaft pump 1, and FIG.

  The vertical shaft pump 1 is roughly configured by a main shaft 5 having an impeller 6 fixed to a tip end thereof rotatably supported by a sliding bearing unit 2 disposed at several locations (upper and lower locations in FIG. 3) in a pump casing 8. It is configured. At this time, the main shaft 5 is freely rotatable by the slide bearing unit 2 whose lower part is fitted to the base part of the guide blade 7 and whose upper part is fitted by the rib 9 provided in the pump casing 8. It is supported.

  Further, as shown in FIG. 4, the sliding bearing unit 2 is inserted outside the bearing 3 fixed to the pump casing 8 side and the spindle 5 while restricting the rotation, and is inserted into the bearing 3 so as to be slidable. The shaft sleeve 4 is formed. FIG. 4 shows the plain bearing unit 2 located in the upper part of FIG.

  At this time, the bearing 3 is formed of a ceramic fixing member made of oil-impregnated porous SiC, and the shaft sleeve 4 bundles a plurality of SiC fibers made of SiC-based ceramics to form a SiC fiber bundle 14. It is formed of a fiber reinforced SiC rotating member formed by knitting and laminating a plurality of layers in a cylindrical shape and impregnating a SiC-based ceramic base material in the gap.

  More specifically, in the sliding bearing unit 2, the shaft sleeve 4 is attached to the main shaft 5 with the relative rotation being restrained by the anti-rotation member 13, and the bearing 3 is provided with a cushioning material 10 interposed therebetween. 11, and is fitted and attached to the bearing support portion 12 fixed to the pump casing 8 via the rib 9 in this fitted state. The cushioning material 10 is for preventing the ceramic from being damaged when a sudden load is applied to the bearing 3, and is formed using an elastic body such as rubber.

  In this vertical shaft pump 1, if the main shaft 5 rotates, it slides between the bearing 3 and the shaft sleeve 4. The vertical shaft pump 1 of this embodiment is a full-speed, full-water-type advanced standby pump that performs standby operation in advance regardless of the water level of the water absorption tank. Time standby operation can be performed.

  The vertical shaft pump 1 configured as described above employs the sliding bearing unit 2 configured by the sliding member according to the present invention, so that the shaft sleeve 4 has an extremely excellent coefficient of friction, temperature rise, strength, and corrosion resistance. Due to this, it is possible to perform a preliminary standby operation in a dry sliding state for a long time.

  FIG. 5 is a conceptual diagram of an experimental apparatus used for the bearing sliding test of the present invention. The experimental apparatus 100 is an apparatus for performing an experiment on the test slide bearing unit 101. The test slide bearing unit 101 is a test bearing that supports the shaft 104, and the test shaft sleeve 102 that is fixed to the shaft 104. The test bearing 103 is fixed to the apparatus casing 105 and is inserted into the test shaft sleeve 102 so as to be able to rotate and slide. An unbalanced weight 106 is provided on the shaft 104 so that a swinging load is applied to the test sliding bearing unit 101, and the bearing surface pressure can be adjusted by increasing or decreasing the weight. Reference numeral 107 denotes an inverter motor, which can adjust the peripheral speed of the bearing portion to a peripheral speed close to that of the actual machine. Torque can be measured with the torque meter 108, and the temperature is measured by attaching a temperature sensor (not shown) to the fixed test bearing 103. The place for temperature measurement is about 3 mm away from the sliding surface.

  FIG. 6 and FIG. 7 show that the test shaft sleeve 102 in the experimental apparatus 100 is made of a fiber-reinforced SiC of the present invention and a conventional cemented carbide, respectively, and is impregnated with oil. The friction coefficient and the rising temperature (dry rise) of the sliding portion combined with the test bearing 103 made of high quality SiC are shown in comparison.

FIG.
<Sliding test conditions>
・ Shaft sleeve: Fiber-reinforced SiC / Cemented carbide (BN5C)
・ Bearings: Oil-impregnated porous SiC
・ Peripheral speed: 4.70 m / sec
・ Surface pressure: 0.13 MPa
・ Sliding time: A graph showing the relationship between the friction coefficient and time of the product of the present invention and the comparative product under a sliding test condition of 70 minutes, with the horizontal axis representing time (minutes) and the vertical axis representing the friction coefficient (μ ). As can be seen from FIG. 1, the test shaft sleeve 102a formed of the fiber-reinforced SiC material of the present invention has a slightly large value (friction coefficient 0.25) at the initial stage of the sliding test, and the friction coefficient over time. Becomes small and becomes a stable low numerical value (friction coefficient of 0.15 to 0.13) in about 10 minutes. On the other hand, in the cemented carbide test shaft sleeve 102b, which is a comparative product, the friction coefficient rises to around 0.4 at the initial stage of the sliding test, and the friction coefficient decreases with time (about 30 minutes). . This phenomenon is because immediately after the sliding test is started, the oil retained in the oil-impregnated porous SiC test bearing 103 is solidified and does not contribute to the lubrication of the sliding portion. At the same time, the temperature of the oil-impregnated porous SiC starts to rise, and the oil component held inside gradually oozes out to the surface and starts to contribute to the lubrication of the sliding portion. The time until the coefficient of friction stably shows a small value is faster for the fiber-reinforced SiC test shaft sleeve 102a than for the cemented carbide test shaft sleeve 102b. From this, the fiber-reinforced SiC test shaft sleeve It can be seen that 102a has a small amount of heat generated by friction and is less likely to cause problems such as cracking.

FIG.
<Sliding test conditions>
・ Shaft sleeve: Fiber-reinforced SiC / Cemented carbide (BN5C)
・ Bearings: Oil-impregnated porous SiC
・ Peripheral speed: 1.57 m / sec
・ Surface pressure: 0.19 MPa
・ Sliding time: A graph showing the relationship between the friction coefficient and time of the product of the present invention and the comparative product under a sliding test condition of 70 minutes, with the horizontal axis representing time (minutes) and the vertical axis representing the friction coefficient (μ ). Even when the surface pressure is high, the fiber-reinforced SiC test shaft sleeve 102a according to the present invention has a slightly large value (friction coefficient 0.25) at the initial stage of the sliding test. It becomes small and becomes a stable low numerical value (friction coefficient 0.14) in about 15 to 20 minutes. On the other hand, in the comparative cemented carbide test shaft sleeve 102b, the coefficient of friction rises to near 0.4 at the beginning of the sliding test, and the coefficient of friction decreases with time, but after 70 minutes. Indicates a value of the friction coefficient that is twice or more compared to the case where the friction coefficient is around 0.3 and the surface pressure is 0.13 MPa. From this, it can be seen that the fiber-reinforced SiC test shaft sleeve 102a always has good slidability without being affected by the surface pressure.

FIG. 8 is a schematic sectional view of a main part of the sliding bearing unit of the present invention and the conventional sliding bearing unit. When the SiC fiber bundle 14 is formed by bundling a plurality of SiC fibers made of SiC ceramics on the sliding surface 16 of the fiber-reinforced SiC shaft sleeve 4 of the present invention shown in FIG. There is a mesh-like recess 15 generated in For this reason, minute wear powder 17 generated when sliding at a high surface pressure enters the recess 15 and keeps the sliding clearance between the bearing 3 and the shaft sleeve 4 constant. On the other hand, as shown in FIG. 5B, in the sliding bearing unit in which the sliding surface 16 does not have the recess 15, there is no escape place for the large amount of wear powder 17 generated at the time of high surface pressure, and the bearing 3 and the shaft sleeve 4 ′. It accumulates on the sliding surface 16 in the meantime. Then, the accumulated wear powder 17 adheres to the surface of the fixing member by heat, and the sliding characteristics are deteriorated. The coefficient of friction increases, the amount of heat generated by friction increases rapidly, and a member with low fracture toughness cracks.
The fiber reinforced structure using the SiC fiber made of the SiC ceramic of the present invention has toughness and is not easily cracked. In particular, since the fracture toughness is high, even if foreign matter enters the sliding surface, it does not crack.

The sliding bearing unit according to the present invention and the preliminary standby pump using the sliding bearing unit are configured as described above, and the sliding member of the fiber reinforced ceramic material is a material in which ceramic fibers are reinforced with a ceramic base material. Therefore, the tensile strength is improved and the toughness is high while maintaining the characteristics such as slidability and wear resistance inherent in ceramics. In addition, because we knit the ceramic fiber bundle that bundles the ceramic fibers, a mesh-like recess is formed in the sliding part, where minute wear powder due to sliding under high surface pressure in a dry atmosphere accumulates, Since it does not adhere to the sliding surface and there is no abnormal increase in the friction coefficient, the sliding characteristics are improved.
There is no risk of cracking or breakage even when using dry sliding for a long time or sliding with dry and wet repeated, and it is suitable for the bearing device of the preceding standby type pump that operates the pump in standby mode. is there.

1 is a schematic perspective view of a fiber-reinforced ceramic sliding member according to the present invention. Similarly, it is the elements on larger scale of a fiber reinforced ceramic sliding member. It is a conceptual diagram of the vertical shaft pump using the sliding member which concerns on this invention. Similarly, it is a principal part enlarged view of the vertical shaft pump using a sliding member. It is a conceptual diagram of the experimental apparatus used for a bearing sliding test. It is a graph which shows the time change of the friction coefficient of the sliding part which combined the cemented carbide of this invention and the comparative product, and oil impregnation porous SiC. Similarly, it is a graph which shows the time change of the friction coefficient of the sliding part which combined the cemented carbide of the invention and the comparative product, and oil-impregnated porous SiC. It is the principal part schematic sectional drawing of the sliding bearing unit which concerns on this invention, and the conventional sliding bearing unit.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Vertical shaft pump 2 Sliding bearing unit 3 Bearing 4 Shaft sleeve 5 Main shaft 6 Impeller 8 Pump casing 14 Ceramic fiber bundle

Claims (2)

  A fiber-reinforced ceramic material shaft sleeve (4) in which ceramic fibers are bundled to form a ceramic fiber bundle (14), the ceramic fiber bundle (14) is knitted and laminated into a plurality of layers, and the gap is impregnated with a ceramic substrate. ) And a bearing (3) made of an oil-impregnated porous ceramic material so as to be rotatable and slidable.   A vertical shaft (1) using the plain bearing unit (2) according to claim 1, wherein several main shafts (5) are arranged in the pump casing (8) and the impeller (6) is fixed to the tip (5). ) Supports the bearing (3) formed of a fixed member of an oil-impregnated porous ceramic material fixed to the pump casing (8) side and the main shaft (5) to restrain the rotation. And a shaft sleeve (4) formed of a rotating member of a fiber reinforced ceramic material inserted into the bearing (3) so as to be rotatable and slidable. Type pump.