US2625884A - Impeller - Google Patents

Description

Jan. 20, 1953 w. H. WELSH 2,625,884

IMPELLER Filed Feb. 23, 1949 3 Sheets-Sheet 1 IN V EN TOR.

2 MLL/ M H. WELSH fir TOR/VEY W. H. WELSH Jan. 20, 1953 IMPELLER 3 Sheets-Shee 2 Filed Feb. 23, 1949 FIG.3

INVEN TOR. WILL/AM H- WE FIG. 4

Irromvey W. H. WELSH Jan. 20, 1953 IMPELLER 3Sheets-Shee 3 Filed Feb. 25, 1949 FIG. 5

R. OH T5 my W M m L H W FIG. 6

fiTTORNE r Patented Jan. 20, 1953 UNITED STATES PATENT OFFICE (Granted under Title 35, U. S. Code (1952),

sec. 266) Claims.

This invention relates to improvements in impellers and more particularly pertains to improvements in impellers adapted for use on centrifugal pumps.

In pumping corrosive fluids or slurries of either corrosive or non-corrosive abrasive material, conventional cast-iron impellers are worn speedily and require replacement in a relatively short time, as the Wear on the working surfaces disturbs the balance of the device, which in turn causes torsional vibration and consequent damage to the impeller drive shaft. Slurries of sand or of ore and ashes, for example, are handled commonly by volute centrifugal pumps. The impellers of such pumps wear, erode and corrode rapidly and such conditions result in the reduction of exit velocity from the pump to a level at which suspended solids settle out of the slurry and clog the system. Shutdowns of pumping operations then necessary are long and costly since pump runners and conveyor-line piping must be separated and cleaned and the worn impeller replaced.

The industrial life of a pump impeller can be lengthened appreciably by fabricating the entire impeller of a material more resistant to wear and corrosion than cast iron. Such a practice, however, involves the use of a large quantity of relatively expensive material that is difficult and expensive to machine and must be replaced by reason of only localized wear. In addition, since the impeller must operate at relatively high speeds at which balance against torsional vibration must be provided, it is virtually impossible to cast and then machine such an impeller so as to attain such balance.

Alternatively, in order to attain more efiicient performance for longer periods of time, only portions of the impeller that are subjected to great wear, erosion and corrosion, can be fabricated of a material more resistant to wear and corrosion than cast iron. While such a practice requires use of a smaller quantity of relatively expensive material, it has, in the past, required construction of a multiplicity of members, thereby increasing tooling costs.

The problems above set forth hav been met in some measure by providing structure such as that shown in U. S. Letters Patent No. 2,463,581, issued March 8, 1949, to applicant for an Improvement in Impellers. Such a pump impeller comprises an impeller body provided with an inlet opening and a plurality of vanes and a unitary replaceable insert constructed of a material having relatively high resistance to wear and erosion, said insert having vane portions disposed conterminously with said vanes. Such structure is subject to several objections of substance. First, in a device so constructed the entire face of the wear-resisting insert member that is opposite the inlet end must be machined. Second, accurate casting and machining of a great number of component elements is required in order to obtain proper balance against torsional vibration. Third, the number and complexity of component elements increases materially the length of time and amount of labor required to dismantle and reassemble such a device.

The primary object of this invention is to provide a pump impeller of simple and durable construction in which the portions thereof that are subjected to maximum wear, erosion and corrosion are constructed of a unitary replaceable member.

Another object is to provide a pump impeller in which the member thereof most liable to wear and corrosion is made of material having a high resistance to abrasion and corrosion, the remainder of the impeller being made of common and inexpensive material that can be machined easily and accurately at comparatively low cost.

A further object is to provide a pump impeller in which but a single member is subjected to appreciable Wear, said member being adapted to be constructed with a minimum of tooling and to be capable of being dismantled and replaced from the impeller assembly facilely.

Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:

Fig. 1 is a plan view of an assembled pump impeller, showing a preferred embodiment of the invention;

Fig. 2 is an elevation thereof, taken partly in full elevation and partly in section on the line 2-2 of Fig. 1;

Fig. 3 is a section taken on the line 3-3 of Fig. 2;

Fig. 4 is a section taken on the line 4 4 of Fig. 2;

Fig. 5 is an elevation of a modified form of the invention, taken partly in elevation and partly in sections; and

Fig. 6 is a section taken on the line 6-6 of Fig. 5. v

Similar numerals j'refer to similar parts throughout the several views.

The vane section H is an integrally formed 7 body constructed of a material characterized by great resistance to erosion, corrosion and wear, the choice of material therefor depending on the type of fluid or slurry the impeller is designed to pump. For example, in pumping a slurry of power-plant ashes in salt water, ordinary castiron impellers wear to the point of uselessness in a relatively short time, while it has been found that sand-cast white iron or chilled cast iron carrying i.0% to 6.0% nickel and 1.25% to 2.25% chromium will withstand the destructive action of such a slurry for a relatively long period. of time. Such material as vulcanized rubber, cast iron provided with a rubber casing or jacket, or' similar material is also adapted for use in constructing the insert.

Said vane section II comprises a disc or platev portion l3 defining the diameter of the impeller assembly, a protuberant mound-shaped boss i5 disposed centrally onthesuction-side face it of saidplate portion, a plurality oi spaced, arcuate vane-portions 1.1, each extendin normallyto said suction-side face and each defining an are ex tending approximately from the mid-point of the radiusof said plate portion to a point proximate the periphery of said plate portion, and, a pinrality of fin portions 19.. Each of said fin per-- tionsfiares into said boss, into the suction-side face of said plate portion and into one of said- Said fin portions [9 each defines.

vane portions. an arc confluent with one. of said. vanes to present a conterminous end therewith. The foot of each of said vane portions. [7 flares into said suctionside face IS.

A core. 2'! extends through each vane portion l1. Eachof' said-cores is elongate in cross-section, as shown in Figs. 1, 3 and e. A raised seating surface 23 is machined on the engine-side face 25 of said vane section, said surface ZS circumscribingsaid' vane section and extending over and beyond the areas defined by said cores, as shown in Figs. '2 and 4.

It is thusapparentthat the vane section H can be fabricated facilely by producing a single casting, andthat the only tooling ofsaid vane sectionrequired is the machining ofseating surface Etandithe machining of the faces 27 vofvane portions i'ithat register with the suction-side shroud plate hereinafter. described.

Engine-side shroud plate 29 is constructed preferably of cast iron. Said plate 2&- comprises a disc portion 3'! and an. integral hub 33-, said hub having a threaded axial bore 35 for mounting said member on an engine drive shaft... A plurality of stud holes 3! drilled through disc portion 3.! are positioned to be alignedwith cores 2| upon .assembly of the impeller, as hereinafter described. Each of said stud holes has a counterbore 35iextending into the engine-side face 2 I of saidshroud stud holes 47 has a counterbore 49 extendingintc.

the suction-side face 5| of said shroud plate 53 to permit full recessing of the stud nuts of the studs hereinafter described. The suction-side face 5| of said shroud plate 63 is also drilledand tapped to provide threaded bores 53 for the cap screws of a feed-line coupling,

Figs. 5 and 6 'showa modified form of the invention, wherein the vane section II is provided with a rubber casin or jacket 61 extending over the wear surfaces of said vane section.

In assembling the impeller, studs 55 having stud nuts 5? are positioned in the stud holes 37, said stud nuts 57 each being seated in a counterbore 39 and are then sealed. in position by pouring type metal 59, or an equivalent eutectic alloy, into the cavity defined and permitting such alloy to harden. The vane section is then seated upon engine-side shroud plate 29 with the studs i5 extending through their respective cores 2! and sealed in position by pouring type metal ti, or an equivalent eutectic alloy, into said cores and permitting such alloy to harden. Suction-side shroud plate 43 is then seated upon the faces 2? of vane portions H with the studs 55 extending through their respective stud holes 2? and stud nuts 63 threaded on said studs, said stud nuts tfl being recessed'in their respective counterbores as. The said suction-side shroud, plate is then sealed in position by pouring type metal 55, or anequivalent eutectic alloy, into the chambers defined in said counterbores as and permitting such alloy to harden.

Dismantling of the assembly can be accomplished facilely by reversing the procedure hereinabove described.

While, for thepurposes cf illustration, the number of vanes is ShOWZl' as 3, it. is. apparent that a vane sectionhavingagreateror lesser number of vanes, arranged symmetrically, can be utilized.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. it is therefore to be understood that within the'scope .of the appended claims the invention may be practiced otherwise than as specifically described.

The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

I claim:

1. A pump impeller comprising a vane section constructed of a material having relatively high resistance to wear and erosion, said vane section having a plurality of vane portions radiating arcuately from a central boss and having cores of elongated cross-section extending through selected vane portions, an engine-side shroudplate seated on a face of said-vane section, said engine-side shroud-plate having a threaded bore in a hub thereof whereby said shroud plate can be mounted on a drive shaft, a suction-side shroud-plate seated on the end faces .of said vane portions, said suction-side shroud-plate having an inlet opening, a plurality of studs extending through each of said cores and securing said shroud plates to said vane section, and a filler material'deposited and setin said cores.

2. A pump impeller comprising a vane section constructed of a material having relatively high resistance to wear and erosion, said vane section having a plurality of vane portions radiating arcuately from a central boss andhaving cores of elongated. cross-section extending through selected vane portions, an engine-side shroudplate seated on aface of said vane section, said englneeside shroud-plate-having. arthreaded bore in a hub thereof whereby saidrshroud plate can be mounted- .on a drive shaft,..a. suction-side shroud-plate seated on the-.endfacesfof said vane portions, said suction-side shroud-plate having an inlet opening, a plurality of studs extending through each of said cores and securing said shroud plates to said vane section and a metal alloy of medium hardness and low melting point deposited in and filling said cores.

3. A pump impeller comprising a vane section constructed of a material having relatively high resistance to wear and erosion, said vane section comprising a central boss, a plurality of fins flaring into said boss and into the suction-side face of said vane section, said fins radiating arcuately from said boss, a plurality of vane portions radiating arcuately from and conterminous with said fins, selected vane portions having cores extending therethrough, and a raised seating surface machined on the engine-side face of said vane section, said surface circumscribing said face, an engine-side shroud-plate seated on said surface, said engine-side shroud-plate having a threaded bore in a hub thereof whereby said shroud plate can be mounted on a drive shaft, a suction-side shroud-plate seated on the end faces of said vane portions, said suction-side shroud-plate having an inlet opening and means to secure a suction line thereto, a plurality of studs extending through said shroud plates and said cores and securing said shroud plates to said vane section, and a metal alloy of medium hardness and low melting point deposited in and filling said cores.

4. A pump impeller comprising a vane section constructed of a material having relatively high resistance to wear and erosion, said vane section comprising a central boss, a plurality of fins flaring into said boss and into the suction-side face of said vane section, said fins radiating arcuately from said boss, a plurality of vane portions radiating arcuately from and conterminous with said fins, selected vane portions having cores extending therethrough, and a raised seating surface machined on the engine-side face of said vane section, said surface circumscribing said face, an engine-side shroud-plate seated on said surface, said engine-side shroud-plate having a threaded bore in a hub thereof whereby said shroud plate can be mounted on a drive shaft, a suction-side shroud-plate seated on the end faces of said vane Number portions, said suction-side shroud-plate having an inlet opening and means to secure a suction line thereto, a plurality of studs extending through said shroud plates to said vane section, and a type metal carried in and filling said cores.

5. A pump impeller comprising a vane section constructed of a material having relatively high resistance to wear and erosion, said vane section comprising a central boss, a plurality of fins flaring into said boss and into the suction-side face of said vane section, said fins radiating arcuately from said boss, a plurality of vane portions radiating arcuately from and conterminous with said fins, selected vane portions having cores extending therethrough, and a raised seating surface machined on the engine-side face of said vane section, said surface circumscribing said face, an engine-side shroud-plate seated on said surface, said engine-side shroud-plate having a threaded bore in a hub thereof whereby said shroud plate can be mounted on a drive shaft, and having a plurality of countersunk stud bores, a suction-side shroud-plate seated on the end faces of said vane portions, said suction-side shroud-plate having an inlet opening, means to secure a suction line thereto and a plurality of countersunk stud bores, a plurality of studs extending through the stud bores of said shroud plates and said cores and carrying stud nuts securing said shroud plates to said vane section, and a type metal carried in and filling said cores and said countersunk bores.

WILLIAM H. WELSH.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Name Date Mauran Aug. 20, 1901 Jungren Aug. 4, 1903 Humphrey J an. 24, 1922 Allen July 17, 1934 Pekor Nov. 11, 1941

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