Fluid reaction surfaces (i.e. – impellers) – Specific blade structure – Irregular – flanged or channel forming blade surface
Reexamination Certificate
1999-11-08
2001-08-28
Look, Edward K. (Department: 3745)
Fluid reaction surfaces (i.e., impellers)
Specific blade structure
Irregular, flanged or channel forming blade surface
C416S228000
Reexamination Certificate
active
06280144
ABSTRACT:
BACKGROUND OF THE INVENTION
FIELD OF THE INVENTION
This invention relates to propellers and impellers and more particularly, to marine propellers and impellers of all designs having multiple grooves, recesses or striations which are cast in the low pressure or trailing face of each blade of the propeller and impeller, each of which striations tapers from the junction of the blade with the hub, toward the extending or distal end of the blade. The parallel or fan-like striations define a waffle-like pattern and act as stress relief pockets to effect more uniform cooling of the relatively thin blade and thick hub portions of the poured propellers and impellers as the propellers and impellers set during the casting process. The striations have been found to eliminate, or at least reduce, formation of voids in the propeller blades, as well as shrinkage and warpage along that segment of each blade where the blades join the hub.
One of the problems encountered in casting marine propellers as well as impellers of all designs, is that of void formation in the blades, as well as shrinkage and warpage of the blades along that portion of each blade which joins the hub, as the poured propellers and impellers cool in the casting mold. Such void formations and warpages are caused by a disparity in the relative cooling rates of the hub and blade portions of the cast propellers and impellers, the thinner blade portions cooling and contracting at a more rapid rate than the thicker hub portion. It has surprisingly been found that casting a series of grooves, striations, recesses or stress relief pockets of selected depth in the trailing or low-pressure face of each blade of the propeller and impeller, each of which striations extends from the junction of the blade with the hub and tapers toward the extending or distal end of the blade, effects uniform or substantially uniform cooling and contracting rates of the blade and hub portions of the propeller and impeller. As a result, formation of voids in the blades, as well as shrinkage and warpage of the blades as the propellers and impellers set in the casting mold, is eliminated or substantially reduced.
Accordingly, an object of this invention is to provide propellers and impellers having grooves, recesses, striations or relief pockets cast in each blade thereof, to effect optimum uniform cooling rates of the hub and blade portions as the poured propellers and impellers set during the casting process.
Another object of this invention is to provide a propeller or impeller having multiple striations which are cast in the low-pressure or trailing face of each blade to effect uniform or nearly uniform cooling rates of the relatively thick hub and thin blade portions of the poured propeller or impeller, and thus define relief pockets that prevent or reduce formation of voids throughout the thickness of the blade as the propellers or impellers set during the casting process.
Still another object of this invention is to provide a marine propeller having multiple, parallel or fan-like striations or stress relief pockets which are cast in the trailing face of each blade of the propeller and extend from the junction of the blade with the propeller toward the extending or distal end of the blade, to effect uniform or nearly uniform cooling and contracting rates of the thick hub and thin blade portions of the propeller and thereby prevent, or at least reduce, shrinkage and warpage of the propeller blades along that portion of each blade which joins the hub, as the poured propeller sets and cools in the casting mold during the propeller casting process.
Yet another object of this invention is to provide a new and improved method of casting a marine propeller and impellers of all designs, including the step of casting a series of elongated, essentially parallel and/or fan-like striations, relief pockets or recesses of selected varying depth in the trailing face of each blade thereof, each of which striations, relief pockets or recesses tapers from a maximum depth at the junction of the blade with the hub toward the extending end of the blade to a minimum depth to achieve uniform or substantially uniform rates of cooling of the blades and hub of the poured propeller or impeller and prevent or reduce formation of voids in the respective blades, as well as shrinkage and warpage along that portion of each blade which joins the hub, as the propeller or impeller sets and cools in the casting mold.
SUMMARY OF THE INVENTION
These and other objects of the invention are provided in marine propellers as well as impellers and a method of casting propellers and impellers with multiple, parallel and/or fan-like striations or recesses in each blade thereof, each of which striations is cast in the low-pressure or trailing face of the propeller or impeller blade to define a discrete relief pocket and tapers from a maximum depth the junction of the blade with the hub, toward the extending end of the blade to a minimum depth. The striations facilitate uniform or nearly uniform cooling rates of the hub and blade portions of the propeller or impeller as the poured wheel cools in the casting mold, thus preventing or minimizing formation of voids in the respective blades and shrinkage and warpage of each blade along that portion of the blade which joins the hub.
REFERENCES:
patent: D. 110871 (1938-08-01), Preston
patent: 120849 (1871-11-01), Broyhill et al.
patent: 1864803 (1932-06-01), Clark
patent: 3100628 (1963-08-01), Norris, Jr.
patent: 3746467 (1973-07-01), Buse
Harrison John M
Look Edward K.
McAleenan James M.
LandOfFree
Propellers and impellers with stress-relieving recesses does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Propellers and impellers with stress-relieving recesses, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Propellers and impellers with stress-relieving recesses will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2481050