Barrel Casing Pump and Method for Manufacturing a Barrel Casing Pump

Abstract

A centrifugal pump having a barrel casing and at least one stage casing therein includes a transition from the last stage casing to the pressure connector of the barrel casing in the form of a spiral flow space. The contour of the spiral flow space is formed by a contour of the last stage casing, a contour of a cover which closes the barrel casing on an end face, and an inner contour of the barrel casing.

Claims

1-9. (canceled)

10. A centrifugal pump, comprising: a barrel casing; a barrel casing cover configured to close an axial end of the barrel casing; and at least one stage casing configured to be inserted in the barrel casing, wherein in a transition region from a last stage casing of the at least one stage casing into a pressure nozzle of the barrel casing, a helical flow space is formed by a contour of the last stage casing, a contour of the barrel casing cover, and an inner contour of the barrel casing.

11. The centrifugal pump as claimed in claim 10, wherein at least one redirection device is provided on the barrel casing in the region of a nose of the pressure nozzle.

12. The centrifugal pump as claimed in claim 11, wherein the helical flow space, starting from the nose, increases radially along a flow direction from the last stage casing toward the pressure nozzle, with a constant axial width.

13. The centrifugal pump as claimed in claim 12, wherein the helical flow space, from a predetermined peripheral angle from the nose, axially expands in the flow direction, and a radial depth of the helical flow space is constant from the predetermined peripheral angle.

14. The centrifugal pump as claimed in claim 13, wherein the predetermine peripheral angle is 90°.

15. The centrifugal pump as claimed in claim 10, wherein the contour of the barrel casing cover and the contour of the last stage casing are configured to be lateral guiding walls of the helical flow space.

16. The centrifugal pump as claimed in claim 10, further comprising: at least one guide wheel, wherein an inner diameter of the helical flow space substantially corresponds to an outer diameter of a last stage one of the at least one guide wheels adjacent to the transition region.

17. A method for manufacturing a centrifugal pump having a barrel casing, a barrel casing cover configured to close an axial end of the barrel casing, and at least one stage casing configured to be inserted in the barrel casing, wherein in a transition region from a last stage casing of the at least one stage casing into a pressure nozzle of the barrel casing, a helical flow space is formed by a contour of the last stage casing, a contour of the barrel casing cover, and an inner contour of the barrel casing, comprising the steps of: producing a 3D template for a helical flow space; and mechanically processing the barrel casing, barrel casing cover and from a last stage casing of the at least one stage casing using the 3D template, wherein the 3D template takes into account a maximum flow space diameter of the barrel casing and the available flow space width at the last stage casing.

18. The method as claimed in claim 17, wherein in the mechanical processing step, the contour of the barrel casing in the region of the pressure nozzle is traversed by a processing machine having a milling tool and having an angular head capable of following the 3D template.

19. The method as claimed in claim 18, further comprising the step of: after the mechanical processing of the helical contour in the barrel casing, welding a redirection device at a nose of the pressure nozzle.

20. The method as claimed in claim 19, wherein the redirection component is configured as defined by the 3D template.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0024] FIG. 1 is a sectioned illustration through the pump according to an embodiment of the invention along the pump shaft,

[0025] FIGS. 2a/2b are two sectioned views through the barrel casing of the pump in FIG. 1 in the transition region into the pressure nozzles,

[0026] FIGS. 3a/3b are two sectioned illustrations through the assembled pump in accordance with embodiments of the present invention in the transition region into the pressure nozzles,

[0027] FIGS. 4a/4b are two illustrations of the processed helical flow space in in accordance with further embodiments of the present invention,

[0028] FIGS. 5a/5b are a side view and a plan view of the relevant contour of the last stage casing of the pump of FIG. 1, and

[0029] FIGS. 6a/6b are a plan view and a side view of the relevant contour of the end-side cover of the pump in FIG. 1.

DETAILED DESCRIPTION

[0030] FIG. 1 shows a centrifugal pump with a barrel casing 1, which has both a suction nozzle 2 and a pressure nozzle 3. The barrel casing 1 is closed at the pressure-side end thereof by means of a cover 4 which is secured to the barrel casing 1, in particular screwed, via connection means 5.

[0031] In the barrel casing 1, there is arranged an insertion module which has a shaft 6 which is arranged so as to be able to be rotated about a rotation axis A. On the shaft 6 a plurality of impellers 7, 7′ are arranged one behind the other, whereby the individual, in this instance five, pump stages are formed. Each pump stage further has in addition a stationary guide wheel 8, wherein the last guide wheel when viewed in the flow direction is identified with the reference numeral 8′. The impeller next to the pressure nozzle 3 or last when viewed in the flow direction is designated 7′. In the embodiment, the impellers 7, 7′ are radial wheels. Alternatively, for example, semi-axial wheels may also be used. Each impeller 7 is surrounded by a stage casing 9. Adjacent stage casings 9 adjoin each other. The stage casing next to the pressure nozzle 3 or last when viewed in the flow direction is designated 9′ and surrounds the impeller 7 which when viewed in the flow direction is arranged in front of the last impeller 7′.

[0032] FIG. 1 shows an end helix 10 which is produced in the transition region from the last stage casing 9′ in the pressure nozzle 3 by the cooperation of the inner contour 11 of the barrel casing 1 and the contours of the cover 4 and the last stage casing 9′.

[0033] As shown in FIGS. 2a, 2b, to this end according to the invention the inner contour 11 of the barrel casing 1 in the transition region to the pressure nozzle 3 is brought mechanically to a desired helical contour 12 by means of a milling processing operation. The helical contour 12 begins in the region close to a nose 13 on the pressure nozzle 3 as shown in FIG. 2a and provides at the beginning a region 14 which has a radial expansion of an available flow space 15 which increases over the periphery, that is to say, the inner contour 11 of the barrel casing 1 provides an increasing deepening of the inner contour 11 with a constant width. In the embodiment shown, the radial expansion increases at a peripheral angle α of approximately 25° up to a peripheral angle α′ of 90°. In alternative embodiments, the increasing radial expansion may extend up to a peripheral angle α′=135°.

[0034] The region 14 is adjoined by a region 16 of the helical contour 12 in which, in the embodiment shown, the radial expansion remains constant from the angle α′˜90° and the helical contour 12 instead still expands only in an axial direction until the helical contour 12 then opens in the pressure nozzle 3. In the region of the nose 13, the original flow space 15 is narrowed in a radial direction by a redirection device 17.

[0035] FIGS. 3a and 3b are sectional illustrations through the assembled pump according to the invention in the transition region in the pressure nozzle 3. As a variant, the redirection device 17 is constructed as a separate component and forms the nose 13. The redirection device 17 is welded in the region of the pressure nozzle 3 to the barrel casing 1.

[0036] Exemplary developments of the helical contour 12 can be seen in the illustrations of FIGS. 4a and 4b.

[0037] FIG. 4a shows as continuous lines that the region 14 and the region 16 of the helical contour 12 are orientated centrally or symmetrically with the pressure nozzle 3. A helical contour 12′ which is illustrated with dashed lines or a helical contour 12″ which is illustrated with a dot-dash line show further variants, in which the region 14′ or 14″ are orientated eccentrically or asymmetrically with the pressure nozzle 3. Accordingly, the regions 16′ and 16″ are orientated eccentrically or asymmetrically with the pressure nozzle 3.

[0038] FIG. 4b shows that the length of the region 14 of the helical contour 12 can vary. A helical contour 12′ which is illustrated with a dot-dash line has an extended region 14′, wherein the region 16′″ is constructed in a shortened state. It is self-evident that the length variation shown in FIG. 4b can also be applied to the embodiments of FIG. 4a.

[0039] FIGS. 5a, 5b show a partial illustration of the last stage casing 9′ in the region of a processed contour 18 which in the assembled pump state forms a guiding wall of the end helix 10 formed.

[0040] The cover 4 with a significant contour 19 for forming the opposing guiding wall can be seen in the illustrations of FIGS. 6a, 6b.

[0041] The multi-component end helix 10, which is constructed in this instance in three pieces, uses a large portion (approximately 80%) of the possible loss level gain of an end helical contour without producing the ideal helical contour. The pump thereby does not have to be constructed in a larger manner. Particularly with multi-stage feed pumps of the barrel casing construction type, a high gain can be achieved in terms of efficiency. The smaller the number of stages, the greater the gain in terms of efficiency. The new structural form, even with feed pumps with radially smaller guide wheels 8′, enables an end helix 10 to be integrated without having to construct the pump in a larger manner.

[0042] For the production of the pump shown, a 3D helical contour in accordance with the provided guide wheel outer diameter and the maximum possible flow space diameter and the flow space width is first produced in the barrel casing 1 using CAD. The dimensions for the flow space correspond to the specifications for the construction of the pump without a helical contour. The resultant pump with a helical contour therefore does not have larger dimensions.

[0043] The axial position between the guide wheel outlet and the pressure nozzle center can be freely selected in the production of the 3D template. The three-dimensional helical contour generated acts as a template for the construction of the three components, that is to say, the barrel casing 1, the stage casing 9′ and the pressure-side cover 4 which in the assembled state form the helical flow space 15. The components or the respective contours 11, 18 and 19 can be produced by means of a shell end mill. In order to process the inner contour 11 of the barrel casing 1, there is used a programmable processing machine by means of which via an angular head, in which the milling cutter is received, the three-dimensional helical contour 12 is travelled from the inner side in accordance with the provisions of the template.

[0044] For the production of the lateral guiding walls, that is to say, the processing of the contour 19 of the pressure-side cover 4 and the contour 18 of the last stage casing 9′, the three-dimensional template of the helical contour 12 is also used. After the processing of the barrel casing 1, that is to say, the production of the helical contour 12, the redirection device 17 additionally has to be welded. This redirection device 17 is also constructed beforehand using the three-dimensional template.