A MINE PROVIDED WITH A PRIMING DEVICE HAVING A SAFETY AND ARMING MECHANISM

Abstract: The mine (1) includes a priming device (19) movable between a safety position and an active position in which it is located facing an activator element (18); the priming device (19) includes first means (28, 34, 35) for triggering a cover-removal charge (4), and second means (45, 48, 50) for triggering a detonation charge (3) by means of respective interface means (57; 59, 61) which the said priming means (35; 50) face in the said active position.

Description: The present invention relates to a mine and in particular to a mine of the type including a cover-removal charge and a detonation charge; such charges are made to explode in rapid sucession in such a way that the first exposes the mine and frees it from overlying soil or camouflage material, and the second explodes immediately afterwards. It is known that this effect can be advantageously obtained by utilising a single priming device for the two charges, provided with a first explosive mixture and a second explosive mixture disposed in a single container and separated by a fire delay; this device is usually disposed within the body of the mine in a conveniently formed seat, in such a way that the first explosive mixture is close to the cover-removal charge and the second explosive mixture is located close to the detonation charge. Known mines of the type previously described have various disadvantages. In particular, when the priming device is introduced into the body of the mine it can be activated accidentally, for example because of a knock, and cause explosion of the mine. Consequently, for safety reasons, mines can be neither stored nor transported in a primed state, but must be primed upon placing. This involves an increase in the time taken for placement and makes it impossible to effect automatic placement of the mines. It is also known from the US-A-4030418 a double-ended mine, adapted to be carried by a projectile, deployed by gravity, and come to rest on either end. This mine comprises a priming device having an arming slider slidable in an axial channel between safe and armed position. However, to effect this sliding movement the slider is spring-biased and is normally locked in the safe position by bolts, which can only be disabled by centrifugal force due to the spin of the mine when the projectile is launched. The object of the present invention is that of providing a mine which will be free from the disadvantages associated with the known mines and described above. The said object is achieved by a mine according to the present invention, of the type comprising: a body closed by an upper cover and defining a lower chamber and an upper chamber; a cover-removal charge housed in said upper chamber; a detonation charge housed in said lower chamber; a priming device comprising first priming means for priming said cover-removal charge and second priming means for priming said detonation charge, said first and second priming means being separated from one another by a fire delay; and an activator device for said priming device; said priming device being movable with respect to said body between a first position in which said activator device cannot cooperate with said priming device and said first and second priming means are inoperative, and a second position in which said activator device can cooperate with said priming device and in which said first and second priming means face respective first and second interface means for interfacing with the said cover-removal charge and with the said detonation charge, characterised in that said first interface means include a flame guide tube extending from a through hole of a bottom wall of said body to said upper chamber, and said second interface means include a relay coupled to an auxiliary charge placed at the bottom of said upper chamber; said priming device comprising an elongated external casing movable below said body, containing said first and second priming means and provided with first and second through holes open into the same side of said casing, said through holes respectively communicating with said first priming means and second priming means, and facing said flame guide tube and said relay in said second position of said priming device. For a better understanding of the present invention a preferred embodiment is described hereinafter by way of non-limitative example and with reference to the attached drawings, in which: Figure 1 is a section through a mine formed according to the present invention; and Figure 2 is a sectional view on an enlarged scale of a detail of Figure 1. In Figure 1 is illustrated a mine, generally indicated with the reference numeral 1 . The mine 1 comprises an outer body 2, a main or detonation charge 3, and a cover-removal charge 4. The body 2 is constituted by a lower, substantially cup-shaped element 5, an intermediate element 6 of concave form fixed onto the lower element 5, respectively containing the said detonation charge 3 and cover removal charge 4, and by an upper cover 7 screwed onto a periphery of the said intermediate element 6. The cover removal charge 4, in particular, is contained in a chamber 8 lying between the bottom of the intermediate element 6 and a peripherally sealed circular cover 9 provided with a central plug 10 removable for filling the chamber 8. The upper cover 7 includes a side wall 13 which surrounds the lower element 5, and an upper, circular and substantially flat portion 14. This portion 14 has a pair of concentric reinforcing ribs 15, and is provided on its inner surface with a circumferential notch 16 which defines a weakened section 17. Beneath the lower element 2 are disposed an activator element 18 and a priming device 19. The activator device 18, known per se, is mounted on a support structure 20 fixed to the outer body 2, and is provided with an electronically activatable striker element 23. With reference to Figure 2, the priming device 19 includes an outer casing 24 of elongate form provided with two cylindrical, longitudinal cavities 25, 26 which communicate with one another by means of a duct 27 of reduced section. At the mouth of the cavity 25 is disposed an explosive capsule 28, fixed by means of a threaded ring nut 29 which clamps a peripheral border 30 thereof against a shoulder 33 of the outer casing 24. The cavity 25 and the duct 27 contain a first explosive mixture 34. The cavity 25 can communicate with the exterior through a radial hole 35, sealed by means of a paper disc 36 and a suitable varnish (not illustrated). A portion of the cavity 26 facing the duct 27 is occupied by a fire delay 37 formed by means of a first cup-shape element 38 provided with a central hole 39 and a second, tubular, element 40; this element 40 includes a portion 43 having a smaller outer diameter, housed within the element 38, and a portion 44 having an outer diameter substantially equal to the outer diameter of the element 38, which houses a second explosive capsule 45. An inner cavity 46 of the element 40 lying axially between a paper disc 47 disposed between the elements 38 and 40 and the said capsule 45, contains a further explosive mixture 48. The cavity 26 further includes a radial hole 49 the axis of which is parallel to the axis of the hole 35, in which is housed a detonator 50 of known type. The cavity 26 is axially closed by a threaded plug 51. The priming device 19 is mounted on a movable element 53, for example a slidable or pivoted rod, the purpose of which will be described hereinbelow. As is clearly visible in Figure 1, on the bottom wall 54 of the lower element are disposed, in respective apertures 55, 56, a tube 57 which extends upwardly to penetrate into the chamber 8, and a flange 58; this flange 58 supports an auxiliary, or booster, charge 59 for activation of the detonation charge 3, and is provided with a through hole 60 in which is disposed a relay 61. The tube 57 and the relay 61 face corresponding holes 63, 64 formed on the support structure 20. The operation of the mine 1 is as follows. The element 53 can carry the priming device 19 from a safety position (not illustrated) to the position illustrated in Figure 1, in which the hole 35 and the detonator 50 of the device 19 itself are located respectively facing the tube 57 and the relay 61. In this configuration the striker 23 of the activator device 18 faces the capsule 28 of the priming device 19. When a suitable signal is sent to the activator device 18 the striker strikes the capsule 28, which explodes and ignites the mixture 34; the paper disc 36 and its layer of varnish are easily blown out and the combustion extends through the tube 57 which behaves as a flame guide, to the cover-removal charge 4. The explosion of this charge 4 causes rupture of the cover 7 of the mine 1 along the weakened section 17, with consequent upward projection of the upper portion 14 of the cover 7. Simultaneously, within the priming device 19 the combustion propagates through the fire delay 37 in a predetermined time differential, and is transmitted from the explosive mixture 48 to the capsule 45 which triggers the detonator 50. The detonator 50 activates the relay 61, which causes the auxiliary charge 59 to explode; the explosion extends to the entire detonation charge 3. From the description of the mine formed according to the present invention the advantages which it allows to be obtained are evident. First of all, the accidental detonation of the mine 1 is only possible in the described configuration in which the hole 35, the detonator 50 and the capsule 28 are located facing, respectively, the tube 57, the relay 61 and the striker 23; therefore, as long as the movable element 53 maintains the priming device 19 in a position different from this, transport and/or storage of the mine 1 can take place in conditions of absolute safety even with the priming device 19 already inserted. This makes it possible significantly to shorten the mine placing times, which in this case do not include the asssembly of the priming device 19, but only the displacement of the movable element from the safety position to the active position; moreover, it is possible to effect placing of the mines with automatic means, without requiring the direct presence of an operator. Finally, it is clear that the mine 1 described can have modifications and variations introduced thereto without by this departing from the protective ambit of the present invention. In particular, the movable element 53 can be translational or rotational, automatically or manually actuable, and its displacement can conveniently be timed.

Claims: A mine of the type comprising: a body (2) closed by an upper cover (7) and defining a lower chamber (5, 6) and an upper chamber (8); a cover-removal charge (4) housed in said upper chamber (8); a detonation charge (3) housed in said lower chamber (5, 6); a priming device (19) comprising first priming means (28, 34) for priming said cover-removal charge (4) and second priming means (45, 48, 50) for priming said detonation charge (3), said first (28, 34) and second priming means (45, 48, 50) being separated from one another by a fire delay (37); and an activator device (18) for said priming device (19); said priming device (19) being movable with respect to said body (2) between a first position in which said activator device (18) cannot cooperate with said priming device (19) and said first (28, 34) and second priming means (45, 48, 51)) are inoperative, and a second position in which said activator device (18) can cooperate with said priming device (19) and in which said first (28, 34) and second priming means (45, 48, 50) face respective first (57) and second interface means (59, 61) for interfacing with the said cover-removal charge (4) and with the said detonation charge (3), characterised in that said first interface means (57) include a flame guide tube (57) extending from a through hole (55) of a bottom wall (54) of said body (2) to said upper chamber (8), and said second interface means (59, 61) include a relay (61) coupled to an auxiliary charge (59) placed at the bottom of said upper chamber (5, 6); said priming device (19) comprising an elongated eternal casing (24) movable below said body (2), containing said first (20, 34) and second priming means (45, 48, 50) and provided with first and second through holes (35, 49) open into the same side of said casing (24), said through holes (35, 49) respectively communicating with said first priming means (28, 34) and second priming means (45, 48, 50), and facing said flame guide tube (57) and said relay (61) in said second position of said priming device (19). A mine according to Claim 1, characterised in that the said first priming means (28, 34) comprise an explosive capsule (28) and an explosive mixture (34) contained in an axial cavity (25) of said casing (24); the said axial cavity (25) communicating with said flame guide tube (57) by means of said first through hole (35). A mine according to Claim 2, characterised in that the said second priming means (45, 48, 50) comprise a second explosive mixture (48) and a second explosive capsule (45) both contained in a second axial cavity (26) of said casing (24), and a detonator (50) housed in said second through hole (49), second axial cavity (26) communicating with said second through hole (49). A mine according to Claim 3, characterised in that the said auxiliary charge (59) is placed on a support flange (58) housed in aperture (56) of said bottom wall (54), said flange (58) being in contact with said casing (24) and having a hole (64) housing said relay (61) and being aligned with said second through hole (49). A mine according to Claim 3 or 4, characterised in that each one of the said through holes (35, 49) is radial with respect to the associated axial cavity (25, 26), said through holes (35, 49) having axes parallel to one another and open into the same side of said casing (24). A mine according to any Claim from 3 to 5, characterised in that said fire delay (37) includes a cup-shaped element (38) and a tubular element (40) having a portion (43) housed into said cup-shaped element (38), both said elements (38, 40) being housed into said second axial cavity (26) and being each one in contact with an associated one of said explosive mixtures (34, 48).

Inventors: TOPA, FERDINANDO
Applicants: VALSELLA MECCANOTECNICA S.P.A.
Application year: 1987
Main classification: F42B23
IPC codes: F42B23, F42C14, F42C15