Metal working – Method of mechanical manufacture – Prime mover or fluid pump making
Patent
1989-05-31
1991-01-15
Look, Edward K.
Metal working
Method of mechanical manufacture
Prime mover or fluid pump making
415197, 4151701, F04D 704, F04D 2942
Patent
active
049849662
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to an improved centrifugal pump and in particular to an improved liner construction for centrifugal slurry pumps and method of construction thereof and particularly to centrifugal slurry pumps wherein because of their method of construction a sharp discontinuity occurs on the inner surface because of the mating of the liner components.
As these pumps are used in slurry applications, hard metal or elastomeric liners are necessary to minimise wear. As the metal and elastomeric liners are required to be interchangeable, it is necessary to make the liners of different materials with the same internal "hydraulic" shape, so that performance does not change when liners are changed.
With hard metal liners, the only available method to conform the liner to the required dimensions until recently was by means of grinding. Grinding is slow and costly and is confined to flat surfaces, readily accessible to large grinding wheels. Therefore the grinding of excess materials from hard metal liners was restricted to the minimum.
Hard metal parts made from a casting process are difficult to control dimensionally, particularly when cores are used, as cores can shift and cause variations in casting thickness. As it is necessary that the liner and its parts must fit exactly within required tolerances in the casing as shown in FIG. 3, the outer surfaces 16 of the volute liner 1 and the outer surface 15 and 17 respectively of the throat bush 2 and frame plate liner insert 3 (as shown in FIG. 1 and 2) are machined to the required width.
In FIG. 2 is shown a close-up of the fitting of the throat bush 2 and the volute liner 1 in the prior art pump shown in section view in FIG. 3. Because the parts are produced as cast metal liners or as moulded elastomeric liners as is required by the medium to be pumped, it is necessary that the mating surfaces 6 and 7 of both the volute liner 1 and the throat bush 2 are produced to smooth finish to ensure accurate fitting of the mating parts. Further to fit the liners into the pumps the outer surfaces 15 and 16 are machined. The inner surfaces of the liner are not machined.
Because of the above considerations, it is extremely difficult to cast two separate hard metal parts such as a volute and throat bush which, when ground and fitted together, have the inside surfaces matching exactly.
As it was not practical to make the liner parts'inner surfaces flush, the side liners (i.e. throat bush 2 and frame plate liner insert 3) were allowed to protrude further inwards than the inside surface 8 of the volute liner 1 as shown in FIG. 1 to 4. This configuration is preferable from a wear point of view than having the inside liners thinner than the volute liner as shown in FIG. 5.
In order that elastomeric lined pumps have the same performance as metal lined pumps, the elastomeric liners are produced with the same internal shape as the metal liners, although the rubber liners can be moulded to very much closer tolerances than metal liners.
It is known that, when slurries or liquids having entrained solids are pumped, the solids can cause wear on the parts of the pumps. Eddying and unwanted turbulence are formed near areas of the pump casing or liner which have abrupt discontinuity, such as steps, of the surface profile. This problem is particularly associated with the mating of the throat bush and the volute liner, and the mating of frame plate liner insert and the volute liner in pumps where components are metal (e.g., cast metal) and the respective mating surfaces require machining or the like. As shown in FIGS. 1 to 4 there is a discontinuity 4 in the form of a step 5 on the inner surface of the liner between the volute liner 1 and the throat bush 2 and between the volute liner 1 and the frame plate liner insert 3 in prior art centrifugal slurry pumps.
This discontinuity causes eddying and turbulence around the step 5 with consequential abrasion by the entrained solids of the volute liner and side liners, producing a high wear area, as shown in FIG. 6. The flow leaving the pu
REFERENCES:
patent: 914283 (1909-03-01), Jackson
patent: 1727703 (1929-09-01), Hause et al.
patent: 2414931 (1947-01-01), Colwell et al.
patent: 2690131 (1954-09-01), Butler
patent: 2800084 (1957-02-01), Butler
patent: 3018736 (1962-01-01), Clay
patent: 3149574 (1964-09-01), Mill
patent: 3381617 (1986-05-01), Wright
patent: 3938908 (1976-02-01), DeBree
Look Edward K.
Nguyen Hoang
Warman International Limited
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