US 2996012 A
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Description (OCR text may contain errors)
Aug. 15, 1961 R. B. BUTLER ROTATING BAND AND SEAT THEREFOR Filed NOV. 17, 1955 n GE INVENTOR REX B. BUTLER Patented Aug. 15, 1961 2,996,012 ROTATING BAND SEAT THEREFOR Rex B. Butler, Dahlgren, Va., assignor to the United States of America as represented by the Secretary of the Navy Filed Nov. 17, 1955, Ser. No. 547,587 1 Claim. (Cl. 102-93) (Granted under Title '35, U.S. Code (1952), see. 266) The invention described herein may be manufactured and used by or for the Government of the United States of American for governmental purposes without the payment of any royalties thereon or therefor.
This invention relates to projectiles and more particularly to an improved rotating band with complementary seating means for high velocity projectiles.
In the past it has been the practice to utilize metallic rotating bands such as copper etc. which are positioned in annular grooves on the periphery of the projectile. The function of such a band is to impart the necessary rotation to the projectile through a biting cooperation with the barrel rifling and also to provide a sealing action between the projectile and the interior of the barrel to -prevent bypass or escape of the gun gases.
While the conventional metallic bands have proved adequate when used with projectiles fired from the older relatively low velocity type of gun, it has been found however, that they do not perform satisfactorily with projectiles of the latest type of guns wherein such projectiles are design to travel at extremely high velocities. Investigation has disclosed that when the conventional metallic bands are used on a high velocity projectile the band material has a tendency to melt during its travel along the bore due to the existing high gas pressures. This, of course, resulted in undesirable metallic deposits along the rifiing. Moreover, an attendant chemical reaction was also noted which damaged the bore to such an extent that it severely limited the number of rounds which could be fired without extensive overhaul of the interior of the gun barrel.
It is also generally recognized that the use of metallic rotating bands particularly copper bands, has always posed one basic problem even when such bands were utilized with the older relatively low velocity gun. That is, the degree of yieldability of a copper band under high radial pressure within the bore was less than that desired and consequently it was always necessary to thicken that portion of the projectile shell adjacent the band to assure against projectile failure. This resulted in added projectile weight and also limited the amount of material which could be carried therein.
It has been found that a rotating band composed of relatively freely yieldable plastic material which is seated on the projectile by a novel retaining arrangement eliminates these prior objections and disadvantages. The plastic rotating band of the present invention is considerably more elastic and yieldable than the conventional metal band, particularly the copper band, and as such deforms or flows laterally quite readily when used on high velocity projectiles, thus providing an excellent sealing and rotating action. Further, due to the increase in yieldability of the plastic band over those of the prior art the projectile shell can be made of lighter construction.
While the present invention solves problems inherent in rotating bands on projectiles designed to travel at exceedingly high velocities, it is to be understood that the invention is equally well suited for service on the older or conventional type of relatively low velocity projectiles.
Accordingly, an object of the present invention is to provide an improved projectile presenting a rotating band assembly which is capable of eflicient performance when utilized with high velocity projectiles.
It is a further object of the invention to provide a rotat ing band with a cooperating retaining seat which is especially adapted for use on projectiles for high velocity guns wherein extremely large gas pressures and radial loads are inherently present. I
Another aim is to present a projectile rotating band which is of suflicient hardness to eifectuate proper rotation and sealing action without flaking or melting and yet which will yield to such an extent as to eliminate the necessity for adjacent projectile shell supporting portions.
A further purpose of the present invention is that of obtaining an improved rotating band assembly for high velocity projectiles, which assembly is readily and inexpensively produced and is securely seatable on the projectile in such a manner that it will be retained thereon throughout projectile travel.
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 longitudinal view of a projectile with parts shown broken away and shown in section for purposes of clarity, the projectile having a rotating band receiving portion at the rear thereof;
FIG. 2 is an enlarged fragmentary sectional view of FIG. 1 showing details of the band receiving portion;
FIG. 3 is an enlarged fragmentary sectional view of the rotating band secured within the band receiving portion fabricated in accordance with the present invention;
FIG. 4 is an enlarged perspective view of a segment of one of the rib members of FIG. 3 illustrating the various successive steps of the knurling operation;
FIG. 5 is a plan view of portions of the rib members; and
FIG. 6 is a side sectional view taken substantially along line 66 of FIG. 5.
In FIG. 1 there is illustrated a projectile 8 having an annular rotating band receiving portion or recess 9 in the rear part of the projectile shell 12. The band receiving portion 9 when initially machined or formed comprises a plurality of longitudinally spaced annular rib or ridge members 14 which in turn establish grooves 11 therebetween. By means of a knurling operation or other suitable process the ribs 14 are then knurled to produce V-shaped recesses or troughs 15 along their outer peripheral surfaces, the depth of said recesses being substantially equal to the height of the rib members. During the knurling operation the metal is disposed in directions normal or transverse to the rib members; thereby creating the V-shaped recesses 15 and crests or points 16 with forward and aft protrusions 17 which protrusions overhang the passages or grooves 11 between the rib members.
The rotating band 10 may then be molded into place within the band receiving portion as shown in FIG. 3. As presently contemplated the band is composed of a relatively freely yieldable plastic material, either a thermoplastic or polyamide of which nylon has up to the present time proved to be quite satisfactory.
It will thus be seen that following the knurling operation each rib comprises alternate V-shaped recesses or troughs with wedge-shaped key structures therebetween. These wedge-shaped key structures not only serve to retain the rotating band in place within the band receiving portion, but through means of a cam action they also tend to force .the band back into its seat when the band is subjected to an outward pressure moment during high rate of spin of the projectile. When the projectile is in flight and rotating at a high rate the inclined surfaces 18' of the band tend to ride out and over the adjacent inclined surfaces 19 of the rib members 14. However, since the opposed surfaces 19 are inclined in'a converging pattern the band material within: each of the grooves is wedged together at the top portion of the groove and forced or canmmed downward towards the bottom thereof.
In addition to camming and locking action abovementioned the knurling of the rib members also presents added rib surface by virtue of the resulting crest and trough contour. This additional surface will of course materially increase the adhesive area and accordingly the holding power of the seating arrangement when the band is molded into place. 7 Y
Example While the following dimensions are in nowis'e to be considered as limiting they present an example of one successfully tested embodiment of the invention used Obviously many modifications and variations of the present invention are possible in the light of the above 4 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.
What is claimed is:
A projectile having an annular recessed portion disposed circumferentially thereof, an" annular ring of polyamicle material superimposed on said recessed portion, the recessed portion comprising a pluralityof spaced ribs, said ribs having knurled outer bearing surfaces, said surfaces being formed of alternate crests and troughs in a thread-like arrangement, said crests being normal to the ribs and the depth of the troughs being substantially equal to but not more than the height of said ribs, each of said knurled ribs having a base portion and sides diverging from the outer limits of said base portion to thereby form locking grooves between successive ribs.
References Cited in the tile of this patent UNITED STATES PATENTS 293,337 Mann Feb. 12, 1884 469,631 Driggs Feb. 23, 1892 681,448 Gathrntann Augq27, 1901 707,135 Maxim Aug. 19, 1902 789,359 Cowdrey May 9, 1905 805,556 Johnson Nov. 28, 1905 815,992 Wheeler Mar. 27, 1906 2,442,369 McBride June 1, 1948 2,663,259 Catlin Dec. 22, 1953 2,809,587 Musser Oct. 15, 1957 FOREIGN PATENTS 586,674 Great Britain Mar. 27, 1947