FR2510249A1 - PROJECTILE, IN PARTICULAR OBUSED WITH FUMIGENE MORTAR, COMPRISING A FRONT PART AND A REAR PART, INTENDED TO SEPARATE - Google Patents

Abstract

TO INCREASE THE STRENGTH AND TIGHTNESS OF THE CONNECTION BETWEEN THE BODY 1 AND THE BASE 2 OF A SMOKE MORTAR SHELL, SO THAT THE SHELL RESISTS ON THE ONE HAND FOR YEARS TO THE SURROUNDING CONDITIONS AND ON THE OTHER HAND TO L '' TEST OF DROP IN INCLINED POSITION, THE NECK 15 OF THE BOTTOM 2, FITTED IN THE BOTTOM 16 OF THE BODY 1, CARRIES A THREAD 17 AND THROATS FILLED WITH GLUE AND ADJUSTMENT DOORS, CONSTITUTING WITH THE INSIDE SURFACE OF THE BOTTOM 16 ADJUSTED AND GLUE ASSEMBLY. THE EJECTION CHARGE 4, INTENDED TO SEPARATE THE BODY 2 FROM THE BODY 1 TO RELEASE THE SMOKE CARTRIDGE 5, IS INCREASED AND IS COMBINED WITH A PRESSURE CHAMBER 10 IN THE BODY.

Description

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  The invention relates to a projectile, in particular a mortar shell, comprising a front part and a rear part

  which are joined by collared joining surfaces serving as sur-

  adjustment faces provided on the adjacent ends of the front and rear parts and overlapping in the assembled state, and which are traversed in the region of the joining surfaces by pins

radial shearing.

  Such a projectile is represented and described by

  for example, in German Patent Application DE-AS 28 478.

  Such a mortar shell is composed of two parts a front part or body carrying a payload and an ejection charge for the payload, and a rear part or base carrying a propellant charge For technical reasons of manufacture and for price reasons, the ring slot

  between the assembly surface provided on a neck of the cap and the

  assembly face provided in the open rear end o bottom of the body of the projectile can not be reduced as much as one could desire It has a maximum width of 0.075 mm It is possible to fill this slot with a glue but this glue acts in this case only as a sealing means and does not contribute to the strength of the assembly The junction between the front part and the rear part of such a projectile is therefore a critical point. The strength of the assembly is normally ensured only by the shear pins through which the neck of the base is pinned at the bottom of the front part, when, when the projectile is dropped in an inclined position, the rear part and the front part tilt. relative to each other, so that the pins break This rocking naturally depends on

  the width of the slit It is even smaller than this width.

  or this game is weak and it would be virtually eliminated if, in the extreme case, there was no play at all, so in the case of a precise adjustment of the two parts This result could however be obtained only by a very expensive manufacture, which would therefore make the projectile all the more expensive It would be necessary in this case to adjust each time a front part and a rear part and number them so that the pairing is preserved.

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  However, even such a sharp reduction of the annular slot could only ensure the strength of the connection and not the perfect seal. An adhesive could never fill

  totally the annular slot and a glued joint would not otherwise be

  their not elastic enough to resist without

to be sure to have a fall test.

  In addition, there is an optimum layer thickness for each glue, so that a given glue only possesses

  its maximum strength and elasticity at a determined thickness.

  The more viscous a glue, the stronger is usually its thick

  Optimal layer thickness Of course, narrow slots can only be filled with low viscosity adhesives.

  it is therefore not possible to introduce a glue of high viscosity.

  having a high shear strength and a high elasticity

after curing, -

  On conventional projectiles, such as mortar shells and especially on smoke mortar shells, the bonding gap between the base and the body may vary between 0 and 0.15 mm (= 2 x 0.075 mm) for the reasons indicated. above This

  variation can not only exist in a number of

  jets but also on individual projectiles, because the

  base and body never let themselves be assembled with such a pre-

  In contrast, there is always some eccentricity, so that the strength and elasticity characteristics of the glue always vary in the direction of the circumference of the slit. Slit is in addition relatively narrow, it can only be used, as indicated above, low viscosity adhesives It is therefore inevitably obtained a bonded assembly whose final strength and elasticity are relatively reduced This explains why such a bonded assembly begins to let go and crack already during a simple vibration test, so that the

  connection between the base and the body loses its seal -

  The problem of sealing could also be solved by a seal, as described in French Patent No. 1,502,826. The incorporation of seals implies

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  however, a minimum thickness of the neck bearing the joint and a

  groove of the annular slot, so that the seal is not damaged.

  However, such a widening of the slot increases again the risk and the amplitude of the tilting of part of the projectile relative to the other, in particular during an impact of such projectiles in an oblique position. , driving the

shear pins.

  Finally, it would still be possible to fill the

  annular groove required for the incorporation of a seal of

  However, this solution does not provide a perfect seal because it is very difficult to fill such a groove completely with glue. Moreover, the strength of the assembly is not affected by

This measure.

  The known mortar shells thus pose the problem that the junction between the neck of the base and the bottom of the body can not

  be made, from the point of view of mechanical resistance and

  in such a way that it withstands for years every conceivable stress on the environment and, above all, so that it withstands the drop test prescribed for such devices, in particular the drop test This problem can not be further solved by the conceivable variants mentioned above of the connection between the body and

the nerve.

  The invention therefore aims to provide a bonded assembly

  for the front and rear part of a projectile, in parti-

  a mortar shell, which, together with the preservation of the basic construction of such guns, improves the strength and tightness of the junction in such a way that the projectile successfully passes the drop test, even with impact oblique, and also withstands

  years, to all the imaginable demands of the environ-

  ment. According to the invention, a projectile as indicated in

  The beginning is essentially characterized by the fact that

  The collar of the rear portion is formed by a multi-turn thread disposed on the neck and having a small pitch and / or a flattened threaded vertex, the bottom of which serves to receive a

251,024.9

  glue and whose top-of net serves as an adjustment surface, and-in this

  that the open bottom of the front part, intended to become the neck, pre-

  feels a fill hole leading to the threads for introduction

glue -

  The embodiment according to the invention of the junction between the front part and the rear part of a mortar ohus

  satisfies all the requirements - that can be asked about it.

  The threading provided on the joining surface of the neck of the rear part is preferably a thread with a small pitch and / or whose threaded top is flattened. The thread has a reference width of about 2 mm and a height of about 0.25 mm The top of the net preferably has a width of about 1 mm and the clearance between the assembly surface formed by the top of the thread on the neck of the rear part and the inner assembly surface of the the bottom of the front part is preferably at most 0> 075 mm approximately This ensures the proper adjustment of the neck of the rear part in the bottom of the front part and allows at the same time the filling of the bottom of the net provided on the neck of the rear part with a high viscosity glue, for example with a polyurethane glue, which gives, after adequate hardening, a

  bonded assembly of great mechanical strength and great elasticity

  ticity. The thread preferably opens into a rear annular groove of the neck by its thread end, located near a shoulder of the neck and / or in an annular groove before the neck by its thread start, the neck preferably having these two. throats at a time Each of the throats communicates with the bottom of the

  provided on the neck, so that the two throats can also

  The grooves will generally be deeper than the bottom of the net, their depth preferably being between about 0.5 and 1 mm. The two grooves may have the same width or different tumblers. It is advantageous that the back groove has a width of about 6 mm, especially when the filling hole for the glue opens into this groove,

  in which case it is used to fill the turns of the file.

  and the front groove The latter has the advantage

  Gently a width of about 2 mm The layout of a throat

  before the beginning of the thread and a rear groove at the end of the

  the neck ensures, in combination with this threading, the

  a particularly good glued joint between the neck of the

  rear part and the bottom of the front part of the projectile.

  To properly close the area where the glue is located and to prevent glue from simply

  after it has been put in place, it is advantageous that a range of adjustments

  a smooth rear end follows the end of the thread or the rear groove and / or that a smooth front adjustment seat precedes the beginning of the thread or the front groove It is preferable that the neck has these two spans In a form of Particularly preferred embodiment, the beginning and the end of the threading are each combined with an annular groove and with an annular bearing surface. In such an embodiment of the neck of the rear part of the projectile, we thus find on this neck, from its end. before, in order, a front adjustment seat, a front groove, the thread, a rear groove and a rear seat. The glued assembly obtained in such an embodiment resists even the most severe conditions. The maximum clearance between the front or rear reach and the

  assembly surface in the bottom of the front part is preferably

  also 0.075 mm in this case, which corresponds to the maximum clearance between the top of the net and the same inner surface

  In this embodiment, the width and the

  both grooves correspond preferably to the values

indicated in the foregoing.

  It suffices that the front reach has a width of a few millimeters; it could therefore correspond to the preferred width of the net and the front groove, that is to say about 2 mm. The rear span is preferably wider than the front span since it is preferably used at the same time for fixing the rear part of the projectile in the bottom of the front part by the pins. For this reason, the rear door preferably has a width of about 15 mm, which therefore gives a guide length of about 15 mm from the neck in the bottom of the front portion, guiding length which extends to the shoulder formed by the transition between the collar and the rest of the

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  rear part of the projectile The rear seat can be attached to the bottom of the front part by six to eight pins for example, which are preferably made of brass and for which the bottom of the front part has through holes and the rear seat has corresponding blind holes The pins will usually have

a thickness of about 2 mm.

  The bottom of the front part of the projectile furthermore has a filling orifice for the glue, which opens into the

  the region of the thread or the annular groove behind or before.

  It is preferable that this orifice opens into the rear groove which, according to the particularly preferred embodiment described above, is wider than the front groove and has

  preferably a width of about 6 minutes.

  glue can be filled easily and

  especially the back groove, the bottom of the front part of the projectile further has a control orifice which is located diametrically opposite the filling orifice on the same

  axis that it and which also leads into the back groove.

  The essential function of this control orifice is to allow the complete filling of the back groove with glue.

  then, by adding an additional quantity of adhesive exactly

  metering, proper filling-of the thread and the front groove.

  Other features and advantages of the invention

  will become more clearly apparent from the following description

  of a nonlimiting exemplary embodiment, and the accompanying drawings, in which Figure 1 is an axial section of a smoke mortar shell whose front part or body and the rear part or base are joined by a bonded assembly according to the invention; and

  FIG. 2 is a detail of FIG.

  the scale 2: 1 showing the bonded assembly according to the invention, only the relevant portion of the body of the projectile being shown in axial section, the portion concerned by the assembly of the base of the

  projectile being represented in elevation.

  FIG. 1 represents a shell of a smoke mortar composed of a body 1 and a base 2. The body 1 carries at the front a conventional igniter head 3, which is connected to an ejection charge. l contains inside a smoke cartridge 5 which is filled with a conventional fumigant composition 6. In the composition 6 is incorporated an ignition charge 7 which is connected with the ejection charge 4 by an ignition piece The smoke cartridge 5 is traversed longitudinally by a central channel 9 which establishes a communication between the ejection charge 4 (and also by the delay piece 8).

  7 for the smoke composition 6) and a chamber of

  The rear end of the cap 2 externally carries a conventional propellant charge which communicates through the ignition apertures 31 with a charge.

  ignition 32, itself connected to a capsule-primer-percussion 12.

  The end of the base 2 also carries a conventional empennage 13.

  At its front end, the base 2 has a shoulder 14 where begins the neck 15 carrying the assembly surface with the body of the projectile The neck 15 of the base 2 s -ememanche in the open bottom 16 of the body 1 and is connected to him, for the most part,

  by the glued assembly according to the invention The collar 15 outer door-

  The bottom 18 of this threading is flat and the same goes for the top 19. At the end of the threading, located on the side of the shoulder 14, there is a groove. rear ring 21, into which a port of

  filling 22 formed in the bottom 16 of the body 1 and used for the in-

  troduction of the glue 23 On the same axis as the fill hole

  22, the bottom 16 has a control orifice 24 which also communicates with the rear groove 21 The latter is followed directly, at the rear, by an annular adjustment surface 25, also located on the neck 15 and connected by pins 26

  at the bottom 16 of the body 1 of the projectile.

  The beginning 27 of the thread 17 is preceded by a front annular groove 28, itself preceded by a ring-span

adjustment 29.

  The voids between the neck 15 of the base 2 and the inner assembly surface of the bottom 16, formed by the rear groove 21, the bottom 18 of the net and the front groove 28, are filled with adhesive 23, the front groove 28 serving normally overflow groove and in this case being filled in part only with excess glue. The smoke cartridge 5 is supported on the bearing-front 28 of the neck 15 by a projection 30 from the latter, the rear portion of the cartridge is narrowed and adapted to the cylindrical interior of the neck 15 so as to replace the This entire cylindrical space-filled by the smoke cartridge 5 is followed at the rear by the frustoconical pressure chamber 10 inside the base 2, which, as already mentioned, is in communication and interaction by the central channel. 9 of the

  cartridge with ejection charge 4 and igniter head 3 & -

  the front of the projectile The references on the more detailed view of figure 2 corresponding totally to those mentioned and indicated

  in Figure 1, it is not necessary to describe them again.

  By the representation on a larger scale (and in elevation) of the neck 15 of the base 2, FIG. 2 thus only shows even more clearly the essential conformation for the bonded assembly according to the invention of this neck in combination with the bottom. open 16

of the body 1 of the projectile.

  The assembly of the smoke mortar shell of Figures 1 and 2 is carried out in the usual manner, with pinning of the bottom 16 of the body to the neck 15 of the base as shown by means of the pins 26 It is generally eight pins brass uniformly distributed around the perimeter of the body 1 of the

  After the assembly, the shell is lying with the opening

  At the bottom 22, glue 23 is introduced into the rear groove 21 through the orifice 22, until glue appears at the control orifice 24 which is diametrically opposite. then the control orifice 24 and place the shell standing on its base 2 to inject the remaining amount of glue, in the form of an exactly predetermined dose After filling of the rear groove 21, this dose completely fills the hollow 18 of the threading with glue-23; the amount of excess glue, which is the consequence of dimensional tolerances, arrives in the front or upper groove 28 which acts as an overflow groove for the glue and acts at the same time as a

  additional sealing groove.

  The filling orifice 22 is then closed and the shell is then left in the upright position until the

glue 23.

  By the particular conformation of the collar 15 as an element

  5, the invention provides an increase in both the strength and the tightness of the connection between the base 2 and the grooves 21, 28 and fitting surfaces 25, 29. the body 1 The necessary solidity is provided both by the flattened threaded top 19 in combination with the bearing surfaces 25, 29 as by the glue 23 filling the bottom thread 18 and the grooves 21, 28, while the seal is provided only through the link

  glued The depth of the grooves and the bottom of the net is adapteded -

  the viscosity of the glue to be used and is usually about 0.25 mm for a high viscosity glue, a polyurethane glue

for example.

  The diameter at the top of the net normally has a tolerance

  rance of not more than 0.075 mm, which is still acceptable

to the manufacturing technique.

  Generally, the bonded assembly according to the invention increases the strength of the connection between the neck 15 and the bottom 16 so that, to eject the payload in this case the smoke cartridge 5 by separating the base 2 and the , body 1, ejection charge 4 of about 15 g usually-expected

  in smoke mortar shells is not enough In case of assem-

  According to the invention, it will normally be necessary to increase this charge, up to a maximum of 50 g. Thanks to the conformation according to the invention of the interior of the projectile and the cartridge, even

  a load of this magnitude will not damage the -

  smoke cartridge 5 and this for two reasons: a) The bottom of the cartridge is followed by the pressure chamber 10, located in the base 2 and communicating through the central channel 9 of the cartridge with the ejection charge 4 Il s' then that the base is separated from the body mainly by the gas pressure established through this channel in the chamber 10 and for a small part only by a thrust exerted on the base by

through the cartridge.

  b) Since the smoke cartridge 5 is supported by projection 30

  on the neck 15 of the base, forces developed by the ejection charge

  4 can at most be transmitted through the wall of the cartridge. The deformation or damage of the cartridge is thus practically excluded. The particular conformation of the smoke cartridge 5 has the additional advantage that it makes it possible to operate optimal the internal volume of the shell by the composition

smoke 6.

  The application of the bonded assembly according to the invention is not limited, of course, to fumigant mortar shells or

  other or ammunition in general; such an assembly is applied

  cable everywhere o the connection of two different tubular parts poses a similar problem, namely an insufficient strength and tightness for certain loads, for example in the event of a fall

or impact.

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Claims (5)

REVEND I C AT I ON S   1 -Projectile, in particular mortar shell, comprising a front portion and a rear portion which are joined by collar assembly surfaces serving as adjustment surfaces provided on the adjacent ends of the front and rear portions and opening to the assembled state, and which are traversed in the region of the joining surfaces by radial shear goupiiles, characterized in that the assembly surface of the neck L 5) of the part   rear (2) is formed by a thread (17) with several turns   placed on the neck (15) and having a small pitch and / or a flattened thread apex (19), whose bottom thread (18) serves to receive a   glue (23) and whose thread tip (19) serves as an adjus-   in that the open bottom (16) of the front part (1) for receiving the neck (15) has a filling opening (22) leading   to the thread (17) for the introduction of the glue -   2 projectile according to claim 1, characterized in that the thread (17) opens into a rear annular groove (21) of the neck by its thread end (20), located near the shoulder (14) of the neck forming the transition between the neck (15) and the remainder of the rear part (2) and / or in a front annular groove (28) of the   neck by its start threading (27).   3 Projectile according to claim 1 or 2, characterized in that the end of the thread (20) or the rear groove (21) is followed by a rear annular adjustment seat (25) without thread and / or the start of threading ( 27) or the front groove (28) is preceded by a   front ring adjustment seat (29) without thread.   4 projectile according to claim 1, characterized in that the filling orifice (22) for the glue (23) opens in the rear groove (21).   5 Projectile according to claim 1 or 2, characterized in that the open bottom (16) of the front part (1) has on the   same axis as the filling orifice (22) for the glue (23)   singing in the back groove (21), a control orifice (Z for the   glue (23), which also opens into the rear groove (21).