Weapon tube

Details Weapon tube Weapon tube

1998-07-02

2001-01-09

Johnson, Stephen M. (Department: 3641)

Firearms

Barrels

Rifling or lining

C089S014050, C102S524000

Reexamination Certificate

active

06170187

ABSTRACT:

REFERENCE TO RELATED APPLICATIONS
This application claims the priority of German application Serial No. 197 29 294.1, filed Jul. 9, 1997, which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
The invention relates to a weapon tube for firing spin-stabilized projectiles with driving bands, wherein the weapon tube has rifling in the form of grooves helically cut over the total periphery into a tube inside wall, so that a rifling groove flank forms on both sides toward a rifling groove bottom and thus encloses a respective rifling groove flank angle, and that lands exist between the rifling grooves so as to together determine a rifling profile for the tube. The projectiles for weapon tubes rifled in this way have one or sometimes even several driving bands (rotating bands), arranged one after another, for transmitting the spin, which driving bands are subjected to high stress during the firing acceleration inside the tube and are subjected to more or less high wear .
In order to raise the muzzle velocity and increase the range of an artillery weapon, the weapon tube is frequently lengthened, e.g. from 39 caliber lengths to 52 caliber lengths. As a result, the driving bands of the projectiles are stressed to their limits and wear out faster. The driving band wear can be reduced by reducing the surface pressure at the rifling groove flanks, whereby either the rifling angle (spin angle) is reduced or the number/depth of the rifling grooves or the driving band width are increased, or through a combination of these options. The surface pressure is caused by a rifling force R during the spin acceleration. Accordingly, the highest occurring rifling force must be used as a starting point for dimensioning the rifling grooves and driving bands.
The German published Patent Application No. DE-40 01 130 A
1
describes a weapon tube with optimized rifling to improve the internal and external ballistics of the projectiles fired from this tube and to reduce driving band wear. The spin is optimized by taking into account a rifling force R(x), wherein the rifling angle is dissected into a Fourier series.
The German published Patent Application No. DE-42 00 171 A
1
furthermore discloses a standardizing of the rifling force R(x) and teaches to use this to determine the rifling angle and also reduce the driving band wear. With the aid of this standardized rifling force and a predetermined final rifling angle, all relevant weapon tube parameters can already be specified during the production.
The rifling angle can be changed only slightly or not at all. Such a change jeopardizes the compatibility of some inserted projectiles. A change in the rifling depth, meaning the depth of a helical groove cut into the tube inside wall, jeopardizes the compatibility of all inserted projectiles. Changing the driving band width is not possible for inserted projectiles. To be sure, the use of more resistant materials for driving bands (e.g., soft iron instead of brass) leads to a reduction in the wear, but is highly problematic and rather involved, especially with inserted live projectiles (combat ammunition). In addition, it is to be expected that the service life of the weapon tube is negatively influenced.
It is the object of the invention to provide a weapon tube where the driving band wear at the projectile is reduced, without negatively influencing the projectile velocity in the muzzle region.
SUMMARY OF THE INVENTION
The above object is achieved according to the invention by a weapon tube for firing spin-stabilized projectiles with driving bands, which comprises: a weapon tube having rifling in the form of a plurality of helical grooves cut over the entire periphery into a tube inside wall, with the grooves being such that a respective rifling groove flank forms on both sides toward a rifling groove bottom and encloses a respective rifling groove flank angle &agr;, and such that lands exist between the respective rifling grooves, which grooves and lands together determine a rifling profile; and wherein the rifling grooves and lands are configured such that with an increased number of grooves, a total volume of the rifling grooves is equal to that for a smaller number of rifling grooves, and the rifling groove depth and spin angle (&dgr;) are the same for the increased number of rifling grooves as for the lower number of rifling grooves.
This solution is based on the realization that an increase in the number of rifling grooves will reduce the frictional stress (frictional work) per rifling flank on a projectile driving band inside the weapon tube. In order to avoid impressions on the projectile shell, caused by the increase in the number of rifling grooves, and thus the reduction of the land surfaces between the rifling grooves, the rifling profile according to the invention is designed such that the total rifling groove volume or the compressed driving band volume is equal to that resulting from a smaller number of rifling grooves. The rifling depth and the rifling angle are not changed as compared to the profile for a smaller number of rifling grooves. The internal and external ballistics for a higher number of rifling grooves is equal to that of a smaller number of rifling grooves. A large total lands area results if steep rifling flanks are created, which prevents the surface pressure between projectile shell and lands areas, and thus also the frictional work, from getting worse as compared to the rifling profile for a smaller number of rifling grooves.
Further advantageous features of the invention are disclosed.
The invention is explained in further detail and described in the following with the aid of a preferred embodiment of a 155 mm caliber artillery tube having a 52 caliber tube length.


REFERENCES:
patent: 1355422 (1920-10-01), Pedersen
patent: 2498052 (1950-02-01), Smith
patent: 3100358 (1963-08-01), Robinson, Jr.
patent: 4924614 (1990-05-01), Hoffman
patent: 5077926 (1992-01-01), Krumm
patent: 5435089 (1995-07-01), Rodney, Jr.
patent: 3300175 A1 (1984-07-01), None
patent: 40 01 130 A1 (1991-07-01), None
patent: 42 00 171 A1 (1993-07-01), None
“Waffentechnisches Taschenbuch”, 1977, Rheinmetall, D{umlaut over (u)}sseldorf, Germany, XP002139998, pp. 523-536.
“Handbook on Weaponry”, 1982, Rheinmetall GmbH, D{umlaut over (e)}sseldorf, Germany, pp. 571-586.

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