RU2487272C1 - Rotary pump with gap-free attachment of impeller and end seals to rotor shaft and method of improving pump performances - Google Patents

Abstract

FIELD: engines and pumps.

SUBSTANCE: pump comprises casing and casing cover. Rotor composed of shaft and impeller is arranged between casing and cover. Impeller is fitted on said shaft by means of two-sided collet lock with taper bushes with screws. Rotor end seals are fitted on said shaft with the help of one-sided collet locks with taper bushes and screws. Said locks are composed of two aligned rings with taper working surfaces to be displaced by clamping screws along shaft axis relative to each other to clamp the shaft.

EFFECT: improved performances, reduced noise and vibrations, higher reliability and efficiency.

5 cl, 9 dwg

Description

Technical field

A centrifugal pump belongs to the field of radial flow pumps and can be used in various industries for pumping a wide range of liquids, primarily oil.

State of the art

Known centrifugal pump of a two-way inlet for pumping oil OJSC Sumy plant "Nasosenergomash" (Ukrainian patent No. 22403, IPC F04D 1/00, publ. 04.24.2007). The pump contains a housing, inside of which a rotor is mounted, on the shaft of which bearings, mechanical seals and a blade impeller are fixed, which together with the supply volume and the extended spiral housing outlet form a flow part. The housing is additionally equipped with a circulation system for lubricating and cooling the internal cavity of the mechanical seals, and the impeller, which is mounted on the shaft, is made of two halves. The presence of two halves of the impeller allows you to halve the vibrational characteristics of the pump by fixing the halves of the impeller on the rotor shaft with the rotation of one half relative to the other around the axis of the rotor by half the angle between the blades. The rotation of the halves is ensured by the corresponding arrangement of the grooves for the keys.

The disadvantage of this pump is the presence of dowels and grooves for them, which weaken the rotor shaft and are stress concentrators, taking into account the fundamental presence of lateral clearances in the keyed joints, the presence of grooves on the shaft for the dowels, which contribute to the excitation of vibration of the pump rotor and reduce the shaft resource.

The closest analogue of the pump device is the Livgidromash double-entry centrifugal pump (RF patent No. 95760, IPC F04D 1/00, published July 10, 2010), comprising a pump housing with a cover and brackets, a shaft mounted in bearings located on housing brackets, a double-entry centrifugal impeller, fixed to the shaft by means of protective bushes and locking elements. The following elements are used as locking elements for fixing the protective bushes to the shaft in different versions: figured keys with threaded nuts and lock washers, or cylindrical elements located on the shaft flat, threaded nuts and lock washers, or lock rings and lock bushes mounted on the keys between the protective bushes and the locking rings, while the ends of the protective bushes and the locking bushes contacting each other are made at an angle relative to their axis of rotation.

The disadvantage of this pump is the presence of dowels and grooves under them, weakening the rotor shaft, which are stress concentrators and taking into account the principal presence of lateral gaps in the keyed joints and the presence of keyways, which enhance the vibrations (vibration activity) and noise of the pump rotating shaft.

The disadvantage of such a device for connecting the impeller to the shaft is the increased vibration activity of the pump due to large gaps, the presence of stress concentrators at the locations of the keys and the inevitable large values of gap seals.

As for the method of improving the characteristics of the pump through its assembly, the published PCT application WO 2010030802 (IPC F04D 17/02, published March 18, 2010) on a method for assembling a highly efficient multistage centrifugal pump is known. However, this method is still not intended for the assembly of a horizontal oil centrifugal pump and therefore does not take into account many design features of such a pump.

Also known is a method of manufacturing a pump described in UK patent No. 1255169 (IPC F04C 19/00, publ. 12/01/1971), in which the machining operation of the ends of the tongue-and-groove vertical surfaces of the housing and the pump cover is carried out in 1 installation.

And this specified method is also not intended for the assembly of a single-stage horizontal centrifugal pump and therefore does not take into account many design features of such a pump.

Disclosure of invention

The main general objective of the invention is the creation of a centrifugal pump with improved technical and economic characteristics, specifically with reduced noise and vibration, increased reliability, resource and efficiency through a number of structural and technological improvements combined in a single inventive concept in individual basic components of the pump.

The technical effect of reducing vibrations and increasing the shaft resource is achieved by replacing the key connections of the impeller with the rotor shaft of the installation, as well as in the places of mechanical seals (isolating the internal cavity of the pump from the surrounding space) with new modified collet-free gapless clamping devices, which are a combination of two coaxial rings with conical work surfaces. The rings are displaced along the axis of the shaft relative to each other.

The technical effect of the improved pump design is achieved by the fact that a rotor consisting of a shaft and a blade impeller is installed between the pump casing and the cover, while the impeller is seated on the shaft by means of a double-sided collet clamping device with tapered bushings and screws, and the rotor mechanical seals are mounted on the shaft using single-sided collet chucks with tapered bushings and screws.

The pump rotor is also installed in the cantilever bearings of two types of cantilever bearings external to the pump body: a spherical double-row roller bearing that receives the axial load of the pump shaft, and a “floating” toroidal roller bearing, both bearings are mounted on the shaft on tapered shrink sleeve with axial section.

All connections of the housings are fastened, including pairs of removable conical pins with threaded ends.

The technical effect of the method for improving the characteristics of the unit is achieved by the fact that the manufacturing process of a high-precision and practically clearance-free pump assembly consists of a sequence of the following methods: before assembling the pump in the molded pump housing and in the molded cover of the pump housing, baseline grinding of the landing surfaces of the "paws" of the pump housing and the connector planes is performed - the total horizontal plane of the housing and the cover and vertical mating planes around the holes for the rotor shaft for mounting the bearing housing. For boring from one installation on the boring machine, holes for rings for adjusting axial clearance of the rotor in the housing, holes for slotted seals of the impeller and holes for bearings in the housings of the bearing assemblies, pre-installation of the boring bar with boring through the empty housings of the bearing assemblies cutters adjustable flights and then make the connection of the pump housing and cover with studs and two removable conical pins with threaded ends horizontally Flax plane of the connector and its connection empty shells bearing assemblies of screws and removable pairs of conical pins with threaded ends along vertical planes connectors with the housing and the cover of the pump housing. After boring the holes from one installation, all the housings and the cover are disconnected with all removable conical pins removed. Regardless of the boring operation, from one installation, the pump rotor is assembled from the shaft, the impeller and two shaped sleeves on the shaft participating in the formation of the pump flow path, using a double-sided collet clamping connection with tapered bushings and screws and using a precision measuring device in the form of a pipe lengths for accurate location of the impeller on the shaft, then install and fasten the shaped bushings on both sides of the collet chuck. Then, the rotor is installed with the axial clearance adjustment rings previously mounted on its shaft in the pump housing without a cover and the clearances are aligned between the impeller and the rings with axial shaft fixing relative to the pump housing, for example, using technological gaskets. Regardless of the installation of the rotor in the pump casing, two bearing units are assembled separately with a spherical double-row roller bearing that accepts axial load, and with a toroidal roller bearing that "floats" and therefore does not accept axial load. This is followed by adjustment mounting and after this dismantling of the bearing assembly with a spherical double-row roller bearing on the rotor shaft and on the pump housing to ensure that the clearance between the mating planes of the bearing housing and the pump housing is practically zero due to a corresponding reduction in the thickness of the expansion ring. Before final fastening of the pump cover to the pump casing, using studs and conical pins, fixing technological pads are removed from the axial clearances of the shaft relative to the casing. After attaching the pump cover to the pump casing, mechanical seals are installed between the rotor shaft and the assembled pump casing, the mechanical seals are mounted on the casing, for example, with studs, and on the shaft with a one-sided collet, clearance-free clamp connection with a conical sleeve and screws. At the end of the pump assembly, the final assembly of the bearing assemblies is carried out on the assembled pump housing using tapered shrink sleeves between the bearings and the shaft and the installation of radial clearances between the rotor and the pump housing, including slotted seals, due to the reuse of removable conical pins between the bearing housing and pump.

The connection of the cover and the pump casing is preferably reliably and gaplessly sealed or sealed with a liquid gasket (anaerobic sealant) with the expectation of the complete polymerization of the sealant. The sealant is polymerized in the absence of air between the gapless metal surfaces, compressed by the forces of tightening the studs. The initial liquid monomer is transformed into a sealant polymer by compression force, but without air for 1 ... 2 days and then reliably holds the joint seal under operating conditions of high pressure drops.

List of drawings

Figure 1 - General side section of the pump;

FIG. 2 is a sectional view of a double-sided modified (smoothed edge edges) clearance-free clamping device for mounting the pump impeller on the shaft;

Figure 3 - cross section of the clamping device for clamping screws;

Figure 4 - cross section of the clamping device on the screws on the reverse side solely for mounting the corresponding shaped sleeve;

5 is a view of the clamping device from the clamping screws;

6 is a one-sided modified (smooth edges of the edges) clearance-free clamping device of one of the two mechanical shaft seals;

Fig. 7 - dismantling of one conical sleeve of a double-sided clamping device;

Fig. 8 - dismantling of a second conical sleeve of a double-sided clamping device;

Fig.9 - the dismantling of the conical sleeve of a single-sided clamping device.

The implementation of the invention

In the figures, in the general numbering of positions, the following significant units and details are enlarged. The most significant components and parts of the pump are enlarged: a molded case 1 with two half-spiral inlets and a double-spiral outlet and a molded cover 2 of the pump body (with a common horizontal plane of the connector along the common central plane of symmetry of the holes for the pump rotor), the pump rotor from balanced and machined shaft 3 and impeller 4, double-sided collet clamping device 5 of the impeller on the shaft, two shaped sleeves 6 on the shaft for forming the flow part of the pump, mechanical seals 7, one-way collet clamping devices 8 mechanical seals on the shaft, two different rolling bearings: spherical double-row roller bearing 9 and toroidal roller bearing 10, tapered shrink sleeve 11, 12 for bearings, tubular housings 13, 14 bearing assemblies (cantilever bearings).

A collet-free gap-free connection of the shaft with the hub is used to securely fit machine parts without the use of dowels or splines. The torque transmitted by the friction joint is significantly higher than the torque transmitted by the key. The advantages of such a connection: Easy installation. For installation, only standard keys are used; heating and pressing are not necessary. Material saving. Due to the absence of a weakening of the shaft with a keyway, a reduction in the diameter of the shaft is possible. Suitable for high speed drives. It has precise alignment and balancing. It is insensitive to pollution. There are no voltage concentrators. Corrosion and chemical resistance.

For a gapless strong connection of the impeller with the shaft, a clamping element is used, consisting of three main parts: a central ring into which identical side rings are pulled by the tightening force of the screws, while the conical surfaces of the rings are pressed against the conical surfaces of the ring. The central ring and side rings contact on conical surfaces. The connection is self-centering relative to the axis of rotation and is an easily mounted interference fit. The joint transmits significant torques and axial forces. Reducing the bending vibrations of the rotor shaft is achieved by replacing the keyed joints of the pump impeller with the rotor shaft with an adjustable interference fit. The device consists of two identical parts with an inner cylindrical surface and an outer conical surface. When tightening the screws, the parts come together along the axis of the shaft and interact with the internal conical surfaces. As a result, the outer diameter of the cylindrical surface of the part increases, and the inner cylindrical surfaces of the parts decrease. A tightness is created. The friction forces on the working surfaces in the hole "a" of the impeller and rotor shaft are provided by normal pressure, which is created by interference (diameter difference) on the working surfaces as a result of axial convergence of the parts. The result is an interference fit and the possibility of transmission of a large torque and axial force by friction between the shaft and the impeller, the impeller is firmly connected to the shaft. To reduce the concentration of shear stresses, the generatrix of the inner cylindrical surface of the inner ring in sections near the ends is made curvilinear of the second order.

Radial grooves are made at the ends of the shaped bushings, into which the screw heads of the clamping device enter, thereby providing a connection of the shaped bushings with the clamping device in the circumferential direction. To fasten the shaped bushings to the clamping element, several more (at least two) are inserted into its through threaded holes on the opposite side ) screws in a symmetrical pattern.

The impeller hub is connected to the rotor shaft with a rather simple mounted conical backlashless interference fit. Tightening the screws, bring together two conical bushings having conical surfaces on the outer diameter and cylindrical surfaces on the inner diameter.

For the possibility of dismantling this connection, squeezing threaded holes are provided. To increase the radial compliance of the parts, a radial section is made.

Shaped bushings are dressed on the rotor shaft for transition landing. The surface of these bushings on the outer diameter forms the geometry of the flow part of the pump. One end of the sleeve is pressed against the end of the clamping device with screw heads that enter the grooves on the end of the sleeve.

Mechanical seals are mounted on the shaft with bushings and sleeves bearing movable mechanical seal rings. The sleeves are connected to the bushings by friction due to the conical surfaces of the single-sided collet clamping devices tightened with screws. Fixed rings of the mechanical seal are pressed against the movable rings by springs (initially the springs are compressed and fixed with clips) and connected to the pump casing by means of a sleeve, a pin and a cylindrical casing connected to the pump casing by half rings and studs.

Detailed installation of the pump

Before mounting the pump, boring with a boring bar on the boring machine of the holes in the housings from one installation (when boring the indicated holes, empty bearing housings should be fixed to the pump housing with screws and bolted in pairs of removable conical pins).

Next, connect the rotor shaft to the impeller using a double-sided clamp collet connection with tapered bushings and screws. The position of the impeller relative to the shaft is ensured by means of a device in the form of a pipe of an exact measured length with a disk and with screw holes at the end. When mounting the impeller, put the pipe on the shaft until the disk stops against the shaft end and fasten it to the shaft end with a screw through the hole in the disk. Tighten the collet connection screws in three bypasses with moments of 0.3 Tzat., 0.7 Tzat. and tzat.

From the side opposite to the main screws of the collet connection, install the false screws for connecting the impeller to the shaped sleeve.

Install the shaped bushings on both sides of the impeller, fix them with nuts and lock the nuts.

Lower the shaft with the rings (centering gaskets) previously mounted on it into the pump housing and install the rings in the grooves of the housing.

By shifting the shaft along the axis, to achieve equality of the gaps between the impeller and the rings, insert technological pads (gauges) into these gaps for axial fixing of the shaft relative to the pump casing.

Separately, assemble two bearing units on the mounting table. When assembling the bearing assembly with a spherical double-row roller bearing, insert the bearing into the bearing housing and fasten it with a false cover. Similarly, assemble another bearing assembly with a toroidal roller bearing.

On both sides of the rotor shaft, put on oil disks, brass sealing sleeves (can be with screw seals) and expansion rings (not shown in the figures).

Slide the bearing assembly onto the shaft, insert the tapered sleeve (from the bearing kit) into the bearing and fasten it with a nut. Install the screws to connect the bearing housing to the pump housing. Turning these screws “by hand” and using mounting gaskets, achieve parallelism of the mating planes of the bearing and pump housings. Measure with a feeler gauge the clearance between the mating planes of the bearing and pump housings. After dismantling the bearing assembly, remove the ring and reduce its thickness by the amount of clearance, which will allow for the final assembly to provide an adjusted clearance between the bearing planes of the bearing and pump housings close to zero.

Remove process gaskets from axial (side) clearances.

Install the pump cover on the pump housing. To do this, after lubricating the contact surfaces of the joint with a liquid gasket (anaerobic sealant-monomer), gently lower the pump cover onto the pump casing, install the pins and fix it on the casing, tightening the nuts in several rounds. Make sure that when lowering the cover, the protrusions of the rings are in the mating grooves of the pump cover. Leave the structure alone for a time sufficient to cure the sealant.

Mount the mechanical seals by installing them so that one of the holes for flushing the mechanical seal faces the upper hole in the pump cover. Secure the mechanical seal on the pump housing with studs and on the shaft axially with a one-way clamp collet. Remove the clips from the mechanical seal springs.

Install the bearing assembly on the shaft, having previously put on the ring, sleeve and expansion ring (not shown). Install a conical shrink sleeve between the bearing and the shaft, tighten the nut with the rated torque and lock it. Tighten the screws “by hand” and, using the mounting screw, align the holes for the pins in the bearing housing with the counter holes in the pump housing. Install the taper pins, tighten and lock the screws.

Remove the cover and place the cover in its place. By choosing the thickness of the gasket, to ensure the absence of axial play of the bearing relative to its housing.

When installing a support with a toroidal roller bearing, the fit of the flanges of the bearing housing and pump will be ensured by the axial mobility of the rings of the roller bearing. But to optimize the conditions of its operation, it is necessary to combine the planes of the ends of the outer and inner rings, which should be ensured by the selection of the thickness of the expansion ring (not shown). To do this, install and fix the bearing assembly on the pump housing by tightening the bolts “by hand”, install the tapered shrink sleeve in the bearing and tighten the nut. Measure the mutual displacement of the outer and inner rings of the bearing and correct the thickness of the expansion ring by the value of this displacement. After that, finally install and secure the bearing assembly.

Check freedom of rotation of the shaft in the assembled pump.

Pump assembly complete. If necessary, bearings and mechanical seals of the shaft rotor can be replaced without disconnecting the cover and pump housing.

An example of assessing the benefits of a method for improving pump performance.

Preliminary tests of prototypes of the pump and expert estimates showed the following relative values of the impact of the proposed technical solutions, primarily on the reduction of pump vibrations, presented in the table.

As a result, the characteristics of the pump will be significantly improved (its vibration activity is significantly reduced, the resource is increased), and therefore, the main objective of the invention is fulfilled.

Claims (5)

1. A centrifugal pump consisting of a housing and a housing cover; a rotor consisting of a shaft and a blade impeller is installed between the housing and the cover; the impeller is mounted on the shaft by means of a double-sided collet clamping device with tapered bushings and screws, and the rotor mechanical seals are fitted on the shaft using one-side collet clamping devices with tapered bushings and screws, these clamping devices are a combination of two coaxial rings with conical working surfaces with possible awn offset rings by means of clamping screws along the shaft axis relative to each other with shaft clamp. 2. The pump according to claim 1, in which the pump rotor is installed in the cantilever bearings of the rolling bearings external to the pump casing of two types: a spherical double-row roller bearing that receives the axial load of the pump shaft, and a "floating" toroidal roller bearing, both bearings are mounted on the shaft on tapered coupling sleeves with axial cut. 3. The pump according to claim 1 or 2, in which all the connections of the housings are fastened, including pairs of removable conical pins with threaded ends. 4. The method of improving the characteristics of the pump according to claim 1 by means of its high-precision and practically clearance-free assembly, namely: before assembling the pump in the molded pump housing and in the molded cover of the pump housing, baseline grinding of the landing surfaces of the "paws" of the pump housing and the connector planes is made - the general horizontal the plane of the housing and the cover and the vertical mating planes around the holes for the rotor shaft for mounting the housing of the bearing units; for boring from one installation on the boring machine, holes for rings for adjusting axial clearance of the rotor in the housing, holes for slotted seals of the impeller and holes for bearings in the housing of the bearing assemblies, pre-installation of the boring bar with boring through the empty housing of the bearing assemblies cutters adjustable flights and then make the connection of the pump housing and cover with studs and two removable conical pins with threaded ends horizontally Flax plane of the connector and its connection empty shells bearing assemblies of screws and removable pairs of conical pins with threaded ends along vertical planes connectors with the housing and the cover of the pump housing; after boring the holes from one installation, disconnect all cases and covers with the removal of all removable conical pins; regardless of the boring operation, from one installation, the pump rotor is assembled from the shaft, the impeller and two shaped sleeves on the shaft participating in the formation of the pump flow path, using a double-sided collet clamping connection with conical bushings and screws and using a precision measuring device in the form of a pipe lengths for pinpointing the location of the impeller on the shaft, then install and mount the shaped bushings on both sides of the collet chuck; then the rotor is installed with the axial clearance adjustment rings previously mounted on its shaft in the pump housing without a cover and the clearances are aligned between the impeller and the rings with axial shaft fixing relative to the pump housing, for example, using technological gaskets; regardless of the installation of the rotor in the pump housing, two bearing assemblies with a spherical double-row roller bearing and a "floating" toroidal roller bearing are separately assembled; followed by adjusting the installation and then dismantling the bearing assembly with a spherical double-row roller bearing on the rotor shaft and on the pump housing to ensure that the clearance between the mating planes of the bearing housing and the pump housing is practically zero due to a corresponding reduction in the thickness of the expansion ring; before final fastening of the pump cover to the pump casing, using studs and conical pins, fixing technological pads are removed from the axial clearances of the shaft relative to the casing; after attaching the pump cover to the pump casing, the mechanical seals are installed between the rotor shaft and the assembled pump casing, the mechanical seals are mounted on the casing, for example, with studs, and on the shaft with a one-sided collet, clearance-free clamp connection with a conical sleeve and screws; at the end of the pump assembly, the final assembly of the bearing assemblies is carried out on the assembled pump housing using tapered shrink sleeves between the bearings and the shaft and the installation of radial clearances between the rotor and the pump housing, including slotted seals, due to the reuse of removable conical pins between the bearing housing and pump. 5. The method according to claim 4, in which at the final connection of the cover and the pump casing, a liquid monomer gasket is used - an anaerobic sealant, with the expectation of the complete polymerization of the sealant under pressure and in the absence of air.

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