EP2143957B2 - Flow guiding component of a pump - Google Patents

Abstract

A multi-stage centrifugal pump has a two-part wheel whose first section (2) is fabricated by injection moulded metal powder, and the second part (4) is made of sheet metal. Further claimed is a commensurate centrifugal pump in which the two parts are welded together. The first part is a cover plate formed jointly with the pump blades and has a hub. The second part is fabricated from sheet metal.

Description

The invention relates to a flow-guiding component of a pump, which is composed of at least two parts.

Such flow-leading components of pumps are known for example in the form of impellers or nozzles of centrifugal pumps. These wheels or nozzles often consist of two spaced cover plates with intermediate blades. It is known to assemble such wheels or diffusers of several parts, for example, sheet metal parts. So it is known to manufacture the cover plates and the blades as individual parts of sheet metal and then to weld together.

This production is quite expensive, since a large number of individual parts must be connected to each other.

It is therefore an object of the invention to improve a multi-part flow-guiding component of a pump to the effect that it is easier and less expensive to manufacture.

This object is achieved by a flow-guiding component of a pump having the features specified in claim 1 or in claim 7 and by a pump unit having the features specified in claim 13. Preferred embodiments result from the subclaims, the following description and the accompanying figures.

The flow-guiding component according to the invention is an element of a pump and serves there to guide the flow of the fluid to be delivered by the pump, for example for the guidance of water. In particular, the component serves to conduct or deflect the flow. The flow-guiding component according to the invention is composed of at least two parts, but may also be composed of more than two parts.

According to the invention, a first part of the component is produced by metal injection molding (metal injection molding). In this method, a metal powder together with plastic is first formed in an injection molding process, which corresponds to the injection molding of plastic, and then heated similar to a sintering process, wherein the plastic volatilizes from the component and the metal powder melts into a homogeneous metal component. As a result of the volatilization of the plastic, the component shrinks, which, however, can be taken into account during molding in injection molding. Thus, this method makes it possible to produce high-precision metal components very cost-effectively, since in particular the molding process is very simple and inexpensive. The shape is much less expensive than, for example, in conventional metal casting, since no lost molds are used and the tool wear is significantly lower.

According to the invention, according to the invention, a further part of the component is preferably made of sheet metal. The first and the second component are then assembled and then together, possibly with additional parts, form the flow-guiding component.

The combination of a part which is manufactured in metal injection molding and a part which is made of sheet metal, ie metal sheet, makes it very easy to finish very complex flow-leading components. So it is possible to form complex geometries in the metal powder injection molding. However, it is possible to limit oneself to such geometries, which can be formed by injection molding without lost cores. Ie undercuts and cavities can be avoided. If such are required in the flow-guiding member, they are then formed by the assembly of the first and the second part. The second part is preferably a part which has no complex geometries, so that the second part can be inexpensively stamped and / or formed from sheet metal.

In particular, the combination of a metal powder injection molded part and a sheet metal part makes it possible to produce a complex flow-guiding component overall at very low cost. Here, the production is much easier and cheaper than if the entire component would be made of metal powder injection molding or sheet metal parts.

Alternatively, it is provided according to the invention to produce the second part, which has no complex geometries, as a plastic molded part, for example as a plastic injection molded part. The connection with the metal powder injection molded part can then take place, for example, such that pin-like projections are provided in the metal powder injection molded part, which engage in recesses arranged correspondingly in the second part and are deformed or bent or folded on the other side of the second part in the manner of a rivet this way to join the parts to a component.

If the flow-guiding component is composed of more than two parts, then it is also possible to produce more than one part from sheet metal and / or more than one part in metal powder injection molding. However, it is essential to the invention that at least one part made of sheet metal or as a plastic molded part and at least one part made of metal powder injection molding are assembled to form the flow-guiding component.

Preferably, the first and the second part are firmly connected to each other, in particular welded together. Thus, after the assembly of the parts by the connection of the parts, a one-piece flow-guiding component is provided, which is easy to handle in the further processing, in particular during the assembly of a pump unit. It is preferable to weld the sheet metal part and the metal powder injection molded part together, for example by induction welding. This makes it easy to connect the two parts together. For the connection projections may be formed on one of the parts, which later form welds. It is particularly appropriate to form these projections in the metal powder injection molded part, for welding these projections then come into contact with the part made of sheet metal. If a current is applied to both, the parts can then be easily welded together.

Preferably, the first part, which is manufactured by metal injection molding, has one or more blades for guiding the flow. These blades serve in particular to divert the fluid to be delivered in a pump or to guide it in a desired direction. Especially such blades have a complex geometry, which formed in a simple manner cost in the metal powder injection molding can be. Such blades may for example be present on an impeller or a distributor of a pump unit. Thus, according to a first alternative embodiment of the invention, the flow-guiding component is designed as a pump impeller.

More preferably, the first part is a first cover plate of a pump impeller, which is made in one piece with the blades of the pump impeller in the metal powder injection molding, and the second part is a second cover plate made of sheet metal. Such a pump impeller can be manufactured conveniently according to the above-described method or method according to the invention. The first cover disk with the complex blade geometry is formed as a metal powder injection molded part. The second less complex formed cover, however, can be cost-effectively punched from sheet metal and / or reshape. Thus, a particularly suitable manufacturing method can be used for each of the two parts. Subsequently, both parts are connected together, preferably welded together. For this purpose, projections may be formed on the free longitudinal edges, which are remote from the associated cover disk, on the blades produced in the metal powder injection molding, which projections serve for welding to the cover disk. The cover plate made of sheet metal is pressed onto these projections and the assembly is then subjected to a current which leads to a welding of first and second parts to said projections.

More preferably, the first part on a hub, which is made in one piece with the cover plate and the blades in the metal powder injection molding. This hub serves to attach the impeller to a drive shaft. Since this hub is used for torque transmission from the shaft to the impeller, it is preferable to form it integrally with the cover plate and the blades, because in this way a large Strength can be achieved. Furthermore, the hub may also have a complex geometry in order to achieve a positive connection for transmitting power to the drive shaft. Such a geometry can likewise be produced favorably in metal powder injection molding. The fact that hub, first shroud and blades can be made in one operation, also reduces the number of required manufacturing and assembly steps.

According to a further preferred embodiment, the hub may have a thread which is formed directly in the metal powder injection molding on the hub. This thread can serve to receive a fastener, such as a clamping screw for fixing the hub to the drive shaft. The metal powder injection molding makes it possible to form the thread in the required precision directly during the formation of the hub, so that further processing steps, in particular a machining operation for introducing the thread can be omitted.

Thus, preferably all complex in their geometry or complex components of the impeller, in particular blades, hub and existing on the hub fasteners, such as a thread formed in a single pass in the metal injection molding, so that the number of further manufacturing and assembly steps to form the impeller can be reduced.

According to an alternative embodiment of the invention, the flow-guiding component is designed as a pump distributor, in particular for a multi-stage centrifugal pump. Such nozzles serve to continue out of an impeller of the centrifugal pump on the outer circumference exiting fluid, such as water, in the desired manner. In particular, the diffuser serves to guide the fluid radially inwards again, then it umes an outlet nozzle of the pump or a next pump stage, ie to supply the suction mouth of a next impeller. Like the impellers of the pump, such diffusers also have a complex one Geometry, which can be formed inexpensively in the manner described above by the present invention at least two-part design of the component. Also in this diffuser, the complex shaped structures can be made by metal injection molding, while parts which are simpler in geometry, can be stamped or formed from sheet metal. Subsequently, both parts can be assembled or connected to each other.

In the embodiment of the flow-guiding component as a guide apparatus, the first part of the component is preferably a first cover disk, which is integral is made with the blades of the nozzle in metal powder injection molding, and the second part of the component is a second cover plate made of sheet metal. As described above with reference to the impeller, the blades, which may have a complicated geometry, in this way can easily be formed together with a cover disk, so that they are firmly connected to this cover disk. The second cover plate, which is substantially planar, can be inexpensively made of sheet metal. Subsequently, both parts can be connected to each other. This connection can be made in the manner described above with reference to the impeller.

More preferably, the first part of the diffuser is a first cover plate with which integrally formed in the metal powder injection molding an axially extending abutment ring, which is designed to bear with a sealing insert. As described above, in a multi-stage centrifugal pump, the distributor serves to guide the fluid radially inwards again to the suction mouth of a following impeller. It is necessary that the suction port of the following impeller comes to the plant sealed against the outlet of the diffuser. For this purpose, a sealing insert is provided which can simultaneously produce a seal to the surrounding housing. In order to fix this sealing insert on the diffuser, a seat in the form of the abutment ring described is preferably formed on this. By using the metal powder injection molding method, it is also possible to inexpensively form such an abutment ring or other shaped seat for sealing elements in one step on the diffuser.

Further, a bearing seat is preferably also integrally formed in the nozzle with the first cover plate, in which a bearing for supporting the drive shaft for the impellers of the pump can be used.

Preferably, the pump nozzle has at least one radially, with respect to the pump longitudinal axis, outwardly directed projection, by means of which the diffuser is fixable between two parts of a pump housing. The projection protrudes radially outwardly beyond the outer circumference of the distributor, so that it can come to rest between the end faces of two housing parts. These housing parts are each associated with a pump stage and are fixed from the outside via straps. The protrusion of the diffuser is thus clamped between the two adjacent housing parts, whereby the diffuser is fixed in the axial direction in the pump housing. The projections are integrally formed with the other parts of the distributor, which are made in metal powder injection molded. The metallic formation of the projections allows a good power transmission, in particular a high surface pressure, when the projections are clamped between the adjacent housing parts. This in turn makes it possible that no enlarged contact surfaces to reduce the surface pressure must be formed at the axial ends of the housing parts. Instead, the housing parts can be easily rohrfömig, wherein the end faces of the tube form contact surfaces for the projection. That the end faces have the same cross-sectional area as the pipe wall at any other point in the pipe. In particular, they have no extended inside or outside diameter. This simplifies the production, since the housing parts can be formed as simple pipe sections, which can either be cut to length from a longer pipe or can be bent out of a metal sheet, in which case only the end faces may need to be machined flat. The projection can be inexpensively formed integrally with the remaining parts of the nozzle in the metal powder injection molding. It can be formed several, preferably uniformly distributed over the circumference projections, more preferably a projection in the form of an annular projection. That the projection is formed as a radially directed ring or collar, which extends over the entire circumference of the distributor.

The invention further relates to a pump unit, in particular a single-stage or multi-stage centrifugal pump unit, which has at least one flow-guiding component according to the preceding description. Preferably, this pump unit has one or more impellers and / or one or more nozzles as described above. These wheels and / or diffusers can be made according to the invention described above system or method of at least two parts, of which a part is made in metal injection molding and a part of sheet metal.

Fig. 1

eine Explosionsansicht eines Pumpenlaufrades, welches ein strömungsführendes Bauteil gemäß der Erfindung bil- det,

Fig. 2

eine Schnittansicht des Pumpenlaufrades gemäß Fig. 1 in montiertem Zustand,

Fig. 3

eine perspektivische Ansicht eines ersten Teils eines Pum- pen-Leitapparates, welcher ein strömungsführendes Bau- teil gemäß der Erfindung bildet,

Fig. 4

eine Ansicht des ersten Teils des Pumpen-Leitapparates gemäß Fig. 3 von der Rückseite her gesehen und

Fig. 5

eine Schnittansicht des Pumpen-Leitapparates gemäß Figuren 3 und 4 in eingebautem Zustand.

The invention will now be described by way of example with reference to the accompanying drawings. In these shows:

Fig. 1

an exploded view of a pump impeller, which forms a flow-guiding member according to the invention,

Fig. 2

a sectional view of the pump impeller according to Fig. 1 in assembled condition,

Fig. 3

3 is a perspective view of a first part of a pump nozzle, which forms a flow-guiding component according to the invention,

Fig. 4

a view of the first part of the pump nozzle according to Fig. 3 seen from the back and

Fig. 5

a sectional view of the pump nozzle according to FIGS. 3 and 4 in installed condition.

Based on FIGS. 1 and 2 is a efindungsgemöß flow-guiding component, which is designed as a pump impeller of a centrifugal pump assembly described in more detail.

The impeller consists essentially of two parts, namely a first cover plate 2 and a second cover plate 4. The first cover plate 2 carries the blades 6 and has a hub 8 in its center, which serves for attachment to a drive shaft. The first cover plate 2 forms together with the blades 6 and the hub 8, a first part of the impeller. This first part is made of metal, z. As stainless steel, manufactured in metal powder injection molding. Cover disk 2, blades 6 and hub 8 are manufactured in one piece in one operation. The metal powder injection molding makes it very easy to integrally form the plurality of blades together with the cover plate 2 and the hub 8 in one operation. Due to the metal powder injection molding even complex blade geometries of the blades 6 can be formed very easily. At their free longitudinal edges facing away from the cover disk 2, the blades 6 have projections 10 which serve to weld the cover disk 2 with the blades 6 to the second cover disk 4.

This second cover 4 is made of a metal sheet, preferably stainless steel. This is done by punching and forming. The cover plate 4 is slightly funnel-shaped and has in its center an axially projecting collar 12, which forms the suction mouth of the impeller. The cover plate 4 with the integrally formed collar 12 is inexpensive to manufacture as a sheet metal part.

After both parts are made separately, they are assembled to the impeller, as in Fig. 2 is shown. For this purpose, the cover plate 4 is pressed onto the projections 10 on the blades 6 and inductively welded to the free longitudinal edges of the blades 6. This creates a one-piece impeller, as it is in Fig. 2 is shown. The two-part production of the impeller has the advantage that the flow channels in the interior of the impeller forming cavities can be formed very easily and inexpensively. So can be dispensed with casting on cores. The manufactured in the metal powder injection molding first part, consisting of cover plate 2, blades 6 and hub 8 preferably has no undercuts, so that it can be easily poured into a two-part injection molding tool. However, this does not exclude that the blades can be formed in more complex forms, which can be realized by a multi-part injection molding tool or inserted cores.

For attachment to a shaft, a clamping cone 14 and a screwed onto this clamping nut 16 are also provided. The slotted clamping cone 14 is inserted into the hub 8 and receives in its interior the drive shaft. By the clamping nut 16, which is screwed onto the thin end of the clamping cone 14, the clamping cone 14 is drawn into the hub 8 and pressed simultaneously radially inwardly due to its conical outer contour, so that the shaft receiving through opening is reduced and the clamping cone 14 together with the surrounding hub 8 and thus the entire impeller can be clamped onto the drive shaft.

A second example of a fluid-conducting component according to the invention will be described with reference to FIGS. 3 to 5, which show a distributor 17.

Also, this nozzle 17 is formed in two parts. The FIGS. 3 and 4 show the first part 18 from two sides. The first part 18 of the distributor 17 is essentially formed by a cover plate 20 with guide vanes or blades 22 formed thereon. The blades 22 end at their radial end on a bearing holder 24, which is also integrally connected or manufactured with the cover plate 20. The bearing holder 24 is a cylindrical sleeve adapted to receive a bearing 26 (see FIG Fig. 5 ) is trained. This bearing 26 serves to support the drive shaft for the wheels.

On the outer circumference of the cover plate 20 further includes an axially extending ring 26, which forms the circumferential housing of the distributor and for connection to a pump housing 28, which in Fig. 5 is shown is provided.

In its central region, the cover plate 20 has an opening 30, which forms the outlet opening of the distributor 17. The opening 30 has a diameter which is larger than the diameter of the bearing support 24, so that the blades 22 extend in the radial direction beyond the outer periphery of the opening 30 inwardly. Spaced radially outward, the opening 30 surrounds an abutment ring, which serves to receive a sealing element 34. The abutment ring 32 extends as a cylindrical ring in the axial direction, starting from the cover plate 20 in the opposite direction to the blades 22.

At the cover disc 20 axially opposite end of the blades 22, a collar 36 is formed in the central region, which extends from the bearing holder 24 substantially radially outward. In this case, the collar 36 extends over the longitudinal edges of the blades 22 and thus forms part of a second cover plate of the nozzle 17. The collar 36 has an outer diameter which corresponds to the inner diameter of the opening 30. However, the outer diameter could also be smaller than the inner diameter of the opening 30. Both causes the cover plate 20 and the collar 36 do not overlap in the radial direction. Thus, the first part 18 of the distributor on no undercuts, so that a shaping in a two-part tool is possible. The first part 18 of the distributor 17 is made entirely in metal powder injection molding as a one-piece component. That is, the first cover plate 20 with the Blades 22, the bearing holder 24, the ring 26, the abutment ring 32 and the collar 36 is made in one piece in one operation as a metal powder injection molded part.

The second part 38 of the distributor 17, which in the assembled state in Fig. 5 is shown, a sheet metal part, which is made by punching and forming. This sheet metal part forms the essential part of the second cover plate of the distributor 17 and extends in the assembled state in the radial extension of the collar 36 to the outside. Thus, the collar 36 and the second part 38 together form the second cover plate. The second part 38 is welded onto the free longitudinal edges of the blades 22. For this purpose, on the blades 22 projections 40 (see Fig. 3 ), which serve for inductive welding to the second part 38.

Also in this second embodiment, i. it can be seen that the method according to the invention or the construction according to the invention makes it possible to form the complex or complicated geometries of the diffuser 17 in the metal powder injection molding, and the combinations with a second part, a sheet metal part, but allows this first part 18, which is manufactured in the metal powder injection molding, without major undercuts or cavities can be formed. This makes a simple injection molding possible. The second part 38, which is then welded to the first part 18, is very simple in its geometry, so that it can be easily made of sheet metal.

In Fig. 5 is also seen how the nozzle 17 is fixed in the pump housing 28. The pump housing 28 is formed from a plurality of housing parts 28a and 28b. Each pump stage is associated with a housing part 28a, 28b. In Fig. 5 two housing parts 28a and 28b are shown. It is to be understood that in a pump having more than two stages correspondingly more housing parts are provided. In each case between two housing parts 28a and 28b, a distributor 17 is fixed. For this purpose, the distributor 17 has on its outer circumference, which, moreover, essentially corresponds to the inner circumference of the housing parts 28a and 28b, has a projection 42 projecting radially outward with respect to the longitudinal axis X. The projection 42 projects annularly in a radially outward direction and is manufactured in one piece with the first part 18 of the distributor 17 by metal injection molding. The Geheäusteile 28a, 28b and possibly other housing parts are compressed from the outside by clamping elements such as straps or clamping bolts. Between the end faces of the housing parts 28a and 28b while the projection 42 of the nozzle is clamped. The fact that the projection of the diffuser 42 is also formed of metal, it can easily absorb the pressure forces occurring without deforming. This makes it possible to avoid in this area on special extended contact surfaces to reduce the surface pressure. Instead, the housing parts 28a and 28b abut the projection 42 with the normal wall cross-sectional area. The projection 42 extends in the radial direction to the outer periphery of the housing parts 28a and 28b, so that a gapless smooth outer surface of the pump housing 28 is provided. The projection 42 fixes the distributor in the axial direction. In the radial direction of the diffuser is fixed by the fact that it comes with its outer periphery on the inner circumference of the pump housing 28 to the plant.

Bezugszelchenliste

2 -

First cover disc

4 -

Second cover disk

6 -

shovel

8th -

hub

10 -

projections

12 -

collar

14 -

clamping cone

16 -

locknut

17 -

diffuser

18 -

First part

20 -

cover disc

22 -

shovel

24 -

storekeeper

26 -

ring

28 -

pump housing

28a -

housing part

28b -

housing part

30 -

opening

32 -

Anlagenring

34 -

sealing element

36 -

collar

38 -

Second part

40 -

projections

42 -

head Start

X -

pumps longitudinal axis

Claims (13)

1. A flow-leading component of a pump which is designed as a pump impeller of a centrifugal pump assembly and is composed of at least two parts, characterised in that a first part (2; 18) of the component is manufactured with metal powder injection moulding, and a second part (4; 38) of the component is manufactured of sheet metal or as a plastic moulded part, wherein the first and the second part are assembled in a manner such that required cavities or undercuts in the flow-leading component are formed between them.
2. A flow-leading component according to claim 1, characterised in that the first (2; 18) and the second part (4; 38) are connected to one another in a fixed manner, in particular are welded to one another.
3. A flow-leading component according to claim 1 or 2, characterised in that the first part (2; 18) which is manufactured with metal powder injection moulding comprises one or more blades (6; 22) for leading the flow.
4. A flow-leading component according to one of the preceding claims, characterised in that the first part (2) is a first cover plate which is manufactured as one piece with the blades (6) of the pump impeller by metal powder injection moulding, and the second part (4) is a second cover plate which is manufactured from sheet metal.
5. A flow-leading component according to one of the preceding claims, characterised in that the first part (2) comprises a hub (8) which is manufactured as one piece with the cover plate and the blades (6) by metal powder injection moulding.
6. A flow-leading component according to claim 5, characterised in that the hub (8) comprises a thread which is formed directly on the hub (8) by the metal powder injection moulding.
7. A flow-leading component of a pump which is designed as a pump guide vane for a multi-stage centrifugal pump and is composed of at least two parts, characterised in that a first part (2;18) of the component is manufactured with metal powder injection moulding, and a second part (4; 38) of the component is manufactured of sheet metal or as a plastic moulded part, wherein the first and the second part are assembled in a manner such that required cavities or undercuts in the flow-leading component are formed between them.
8. A flow-leading component according to claim 7, characterised in that the first part (18) is a first cover plate which is manufactured as one piece with the blades (22) of the guide vane by metal powder injection moulding, and the second part (28) is a second cover plate which is manufactured of sheet metal.
9. A flow-leading component according to claim 7 or 8, characterised in that the first part (18) is a first cover plate with which an axially extending bearing-contact ring (32) which is designed for bearing-contact with a sealing insert (34), is formed as one piece by metal powder injection moulding.
10. A flow-leading components according to one of the claims 7 to 9, characterised in that the pump guide vane comprises at least one radially outwardly directed projection, by way of which the guide vane may be fixed between two parts (28a, 28b) of a pump housing (28).
11. A flow-leading component according to one of the claims 7 to 10, characterised in that the first (2; 18) and the second part (4; 38) are connected to one another in a fixed manner, in particular are welded to one another.
12. A flow-leading component according to one of the claims 7 to 11, characterised in that the first part (2; 18) which is manufactured with metal powder injection moulding comprises one or more blades (6; 22) for leading the flow.
13. A pump assembly, in particular a single-stage or multi-stage centrifugal pump assembly, characterised in that it comprises at least one flow-leading component according to one of the preceding claims.

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