Self-adjusting centering device for a pyrotechnic block, tool and method for implementing such a device

Abstract

A self-adjusting centering device for a pyrotechnic block, comprising a hollow tubular piece (12; 12') elongated along a longitudinal axis (X) and comprising: - two axially open opposite ends (12a, 12b; 12a', 12b'), - two elastically deformable zones (Z1, Z2) axially spaced apart and each positioned at a distance from the two opposite ends of the hollow tubular piece, each elastically deformable zone (Z1, Z2) being configured to contract or expand radially relative to the longitudinal axis (X) under the effect of a stress applied axially to the hollow tubular piece (12; 12'). Figure for the abbreviation: Fig. 1.

Description

Title of the invention: Self-adjusting centering device for a pyrotechnic block, tool and method for implementing such a device. Technical field

[0001] The present exposition relates to a self-adjusting centering device for a pyrotechnic block and a tool for implementing such a device, as well as a method for implementing such a device using such a tool. Previous technique

[0002] Pyrotechnic blocks are used in various applications such as gas generation (for example, for airbags), and are generally hollow cylindrical blocks containing a fuel such as propellant. Each hollow block is generally shaped to have a central, longitudinally oriented internal cavity extending from one open axial end of the block to the opposite, also open, axial end.

[0003] During their use, pyrotechnic blocks are mounted on various tools and, to do so, they must be centered on these tools. More specifically, the blocks are generally centered using plastic parts that are inserted more or less partially into the blocks through one or both of the two open axial ends of these blocks. The plastic parts must have an external diameter adapted to match the internal diameter of the central longitudinal cavity of the blocks.

[0004] However, depending on the batches of manufacture of the blocks, the dimensions of these blocks are likely to vary and in particular their internal diameter.

[0005] It follows that the plastic parts of the tooling must be modified, sometimes even replaced, in order to adapt to the variations in the internal diameters of the pyrotechnic blocks depending on their production batches. Description of the invention

[0006] The prior art solution described above proves to be complicated, lengthy and costly to implement.

[0007] In view of the above, it would therefore be useful to be able to achieve centering of pyrotechnic blocks, particularly when using them on different tools, by avoiding at least some of the problems identified above and in particular by avoiding having to modify tooling parts to adapt to variations in internal diameter of the blocks within a given range of internal diameters.

[0008] In this regard, one embodiment relates to a self-adjusting centering device for a pyrotechnic block, comprising a hollow tubular part elongated along a longitudinal axis X and which includes: -two opposite ends open axially, -two elastically deformable zones spaced axially apart from each other and each positioned at a distance from the two opposite ends of the hollow tubular part, each elastically deformable zone being configured to contract or expand radially relative to the longitudinal axis X under the effect of a stress applied axially to the hollow tubular part.

[0009] The aforementioned device eliminates the need for plastic parts to center pyrotechnic blocks. The device is configured to adapt to variations in the internal diameter of the blocks thanks to locally deformable zones in the tubular part. Depending on the applied stress, these zones can deform radially and come into contact, via their external surface, with the internal surface of the surrounding pyrotechnic block. The deformation capacity of these zones is adapted to a given range of internal diameter variations of the pyrotechnic blocks. This device reduces the tooling volume by decreasing the number of centering parts required at each manufacturing stage (inhibiting, shimming). Consequently, manufacturing costs are reduced.It should be noted that this self-adjusting mechanism also prevents degradation of the surface condition of the internal surface of the block with which the deformable zones will come into contact through elastic deformation.

[0010] According to other possible characteristics: -the hollow tubular part comprises a tubular wall, each deformable zone being formed in a distinct part of the tubular wall and extending both along an axial extension and along a circumference of the tubular wall part, each deformable zone comprising several elongated portions separated angularly from each other by axially elongated openings; -each elongated portion presents, along its axial extension, an undulating shape comprising a succession of hollows and bumps which each extend radially relative to the tubular wall of the hollow tubular piece. -the succession of hollows and bumps mainly comprises a bump which extends radially outwards relative to the tubular wall of the hollow tubular part and which is framed axially by two hollows extending radially inwards relative to the tubular wall of the hollow tubular part; -each deformable zone comprises at least three elongated portions; -the two deformable zones are axially spaced from each other along an axial distance which is greater than or equal to half the length of the hollow tubular part; -the hollow tubular part has, on its internal surface, between one of its two axially open opposite ends and the deformable zone which is closest to this end, one or more support elements projecting radially from the internal surface and away from it, this or these support elements being shaped inside the hollow tubular part so as to leave free an axial passage centered relative to the hollow tubular part; -Each opposite end of the hollow tubular part is provided with elastically deformable slats in a radial direction (the slats are arranged axially) so that each end can be fitted around a part whose external diameter is likely to vary; it should be noted that radial pins may be present on the internal faces of the slats in order to come into contact with a part such as the one mentioned above; -one of the two opposite ends of the hollow tubular piece is thicker than the other in order to exert a higher clamping force on one centering piece than on the other end with another centering piece; in this configuration, the aforementioned slats are made by removing material from the thickness of the thickened end in order to give them sufficient elasticity.

[0011] Another embodiment relates to a tool for implementing a self-adjusting centering device for a pyrotechnic block as briefly described above.The tool comprises a first and a second elongated part along a longitudinal axis, the first part forming an external sleeve around the second part which it surrounds coaxially and which is able to slide axially relative to the second part, the first part being provided on an external surface of the external sleeve with one or more elements projecting radially from said external surface and away from it, the first and second part each having, at the same longitudinal end of the tool, a actuating head, the two actuating heads being configured to cause the first part to slide relative to the second part by displacement of the actuating head of the first part relative to the actuating head of the second part.

[0012] This tool is configured to exert suitable axial stresses on the aforementioned self-adjusting centering device and, thus, induce the appropriate radial elastic deformation (expansion or contraction by elastic return) of the locally deformable zones of the tubular part. When the tubular part is to be inserted into the internal cavity of a block, the aim is to locally reduce (at its deformable zones) the diameter of this tubular part. Once the tubular part has been inserted into a block, the aim is to locally increase the diameter of this tubular part (at its deformable zones) to achieve contact with the internal surface of the block, thus centering it relative to the tubular part. In practice, it is possible, for example, to apply axial tension to the part to force the radial elastic retraction of its deformable zones, and the radial expansion of these zones can be simply achieved by removing the stress, through a simple elastic return of the deformable zones to their initial shape.

[0013] According to other possible characteristics of the tool: -the operating head of the first part is arranged axially between the external sleeve of the first part and the operating head of the second part, the sliding of the first part relative to the second part being achieved by a pull exerted on the operating head of the first part towards the operating head of the second part.

[0014] Another embodiment relates to a method of implementing a self-adaptive centering device as briefly described above using a tool for implementing the self-adjusting centering device of a pyrotechnic block, this tool being as briefly described above.

[0015] According to other possible characteristics of the process: -the process includes: the axial insertion of the tool inside the hollow tubular part of the self-adaptive centering device, the displacement of the operating head of the first part relative to the operating head of the second part in order to cause the axial sliding of the first part relative to the second part and to apply an axial end stress on the hollow tubular part and thus cause a radial retraction of the two deformable zones of the hollow tubular part; -the process includes a relative displacement between, on the one hand, a hollow pyrotechnic block having a central longitudinal internal cavity and, on the other hand, the assembly formed by the hollow tubular part of the self-adaptive centering device in a radially retracted position with the tool inserted inside so that the aforementioned assembly is disposed in the central longitudinal internal cavity of the pyrotechnic block; -the process includes a displacement of the operating head of the first part relative to the operating head of the second part in order to cause an axial sliding in the opposite direction, of the first part relative to the second part, and thus to release the axial extension stress applied to the hollow tubular part, thereby causing the radial expansion of the two deformable zones of the hollow tubular part and their pressing against the internal peripheral surface of the central longitudinal internal cavity of the pyrotechnic block; -more specifically, the movement of the operating head of the first piece relative to the operating head of the second piece is achieved by releasing the axial extension stress applied to the hollow tubular part, thus causing radial expansion, by elastic return, of the two deformable zones of the hollow tubular part and their pressing against the internal peripheral surface of the central longitudinal internal cavity of the pyrotechnic block. Brief description of the drawings

[0016] The purpose of this presentation and its advantages will be better understood upon reading the detailed description below of various embodiments given by way of non-limiting examples. This description refers to the attached figure pages, on which:

[0017] [Fig-1] Fig. 1 represents a schematic perspective view of a device self-adjusting centering of a pyrotechnic block (not shown) according to an embodiment.

[0018] [Fig.2] Fig.2 represents a schematic perspective view of an assembly consisting of the self-adjusting centering device of [Fig.1] and a tool for implementing this device.

[0019] [Fig. 3] Fig. 3 represents a schematic axial cross-sectional view of the entire assembly [Fig.2],

[0020] [Fig.4] Fig.4 is a schematic cross-sectional view (along IV-IV) of the whole of [Fig.3].

[0021] [Fig. 5] Fig. 5 represents a schematic axial cross-sectional view of an assembly formed from the self-adjusting centering device of [Fig.1] mounted inside a pyrotechnic block.

[0022] [Fig. 6] Fig. 6 represents a schematic axial cross-sectional view of the entire assembly the [Fig.5] mounted on an inhibition tool.

[0023] [Fig.7] The [Fig.7] is a schematic view showing the whole of the [Fig.5] in a packing chamber for the formation of a packing varnish around a pyrotechnic block coated with an inhibiting varnish in order to create a load containing several pyrotechnic blocks.

[0024] [Fig.8] Fig.8 is a schematic perspective view of a centering device self-adjusting according to a variant of the embodiment.

[0025] [Fig.9] Fig.9 is a schematic perspective view showing the interior of the self-adjusting centering device of the [Fig.8]. Description of the implementation methods

[0026] Fig. 1 schematically represents a self-adjusting centering device 10 of a pyrotechnic block (not shown) according to an embodiment of the invention.

[0027] Generally, the self-adjusting centering device 10 comprises a hollow tubular part or body 12 elongated along a longitudinal axis X. The part 12 comprises: -two opposite ends 12a, 12b which are each axially open to allow access to the interior of the room from each end, from the outside of the room, -two elastically deformable zones Z1, Z2 of the hollow tubular part 12 which are axially spaced from each other and arranged on either side of a central part 12c of part.

[0028] Each elastically deformable zone Z1, Z2 is positioned at a distance from the two opposite ends 12a, 12b of the hollow tubular part, but is closer to one end than the other. Thus, the deformable zone Z1 (resp. Z2) is closer to end 12a (resp. 12b) than to end 12b (resp. 12a), while still being positioned at a certain distance from the end in question, as illustrated in [Fig. 1]. Maintaining a certain distance between each deformable zone and the nearest end of the part allows for suitable and sufficient centering of the pyrotechnic block into which the tubular part 12 will be inserted. This distance can thus be approximately equal to twice the diameter of the internal channel or cavity of the block. In general, each zone Zl, Z2 is deformable along a radial direction relative to the longitudinal axis X (as indicated by the double arrows on [Fig.l]).More specifically, each zone Zl, Z2 is configured to contract or expand radially under the effect of a respective tensile or compressive stress applied axially to the hollow tubular part, as schematically indicated by the double arrow Fl, F2 at the end 12a of the part 12. The presence of two deformable zones allows for good distribution of the mechanical contact between the tubular part 12, via these two zones, and a contact surface of an external part surrounding the part 12, as will be seen later.

[0029] More specifically, the hollow tubular part 12 comprises a tubular wall, and each deformable zone Zl, Z2 is formed in a distinct portion (depending on its longitudinal extent or length) of the tubular wall. The central portion 12c of the part 12, which axially separates the two zones Zl, Z2 from each other, is generally rectilinear in shape (both externally and internally). Two end portions 12d, 12e, respectively including the two opposite ends 12a, 12b, are arranged respectively on either side of the two deformable zones Zl, Z2, along the longitudinal extent of the part. Each deformable zone Zl, Z2 is thus situated between the central portion 12c and the corresponding end portion 12d, 12e.

[0030] Each deformable zone Z1, Z2 extends locally both along an axial extension (along the longitudinal axis X of the tubular wall) and along a circumference of the relevant section of the tubular wall. Each local deformable zone thus extends angularly through an angle of 360°, that is, around the entire circumference of the tubular wall. Furthermore, each deformable zone comprises several elongated portions of material (following the axial extension of the zone in question) which are separated angularly from one another by openings or ports that are also axially elongated. The elongated portions of material thus form branches or segments of material which, in pairs, form an opening / port between them along a circumferential direction, allowing these portions to move freely radially relative to one another under the action of external stresses on the tubular part 12.

[0031] The number of elongated portions is at least three, as this number defines a minimum number of external supports for the deformable area under consideration. These supports can thus be inscribed on a contact circle external to the area when the part is surrounded by another part (pyrotechnic block), as will be seen later. Two elongated portions would not be sufficient to obtain adequate external support / contact, as it is necessary to constrain both degrees of freedom of the block (along the two axes of movement) in the cutting plane. The number of elongated portions may, however, exceed three if the hardness of the pyrotechnic block is too low to withstand the pressure exerted by the elongated portions (risk of local deformation of the block). However, the number of elongated portions may also depend on the dimensions of the block's internal channel.It should be noted that in the described embodiment, the elongated portions / branches (regardless of their number and shape) are aligned with each other from one zone to the next; that is, they are each located on the same cylindrical generatrix from one zone to the next, for example, for the sake of simplified manufacturing. However, in other configurations not shown here, the elongated portions / branches of one zone may be angularly offset relative to the elongated portions / branches of the other zone.

[0032] In the embodiment example of [Fig.1], the zone ZI (resp. Z2) comprises three elongated portions of material ZI 1, Z12 and Z13 (resp. Z21, Z22 and Z23) between which three cuts have been made in the tubular wall of the hollow part in order to create three elongated openings 011, 012 and 013 (resp. 021, 022 and 023), each opening angularly separating two portions of material arranged consecutively in a circumferential arrangement.

[0033] We will now describe the shape of an elongated portion, for example that of portion Z13, which is clearly visible in [Fig. 1], knowing that all other portions are identical for the same zone. Here, the elongated portions of the two zones are all identical. However, depending on certain block configurations, the Elongated portions of one zone may differ from those of the other zone. This characteristic can be found, for example, in the case of a pyrotechnic block with a conical internal channel / cavity.

[0034] As shown in [Fig. 1], the elongated portion Z13, along its axial extension (along the X-axis), has a wavy shape comprising a succession of troughs and bulges, each extending radially relative to the tubular wall of the hollow tubular part. This alternation of radial troughs and bulges, giving the deformable portion a sort of accordion-like bellows shape, provides the necessary elasticity to the area, ensuring its elastic return after deformation. Generally speaking, the elastic deformation of each area is understood to be its ability to deform repeatedly over time without being damaged.

[0035] In this case, the succession of hollows and bulges mainly comprises a central bulge B1 that extends radially outward relative to the tubular wall of the hollow tubular part (i.e., the bulge forms a convexity outward from the part) and is axially framed by two hollows Cl, C2 extending radially inward relative to the tubular wall of the hollow tubular part. Each hollow thus forms a concavity with respect to the outside of the part, or, in other words, a re-entrant convexity, which extends inward from the part. This conformation of the deformable portion Z13, and therefore of the deformable zone ZI as a whole, provides the elastic deformability necessary for the zone to allow repeated elastic contraction and expansion movements under the effect of an external axial stress, and this for both deformable zones of the part.

[0036] In this embodiment, the two deformable zones Z1, Z2 are axially spaced from each other by an axial distance that is greater than or equal to half the length of the hollow tubular part 12. In practice, the length of the central part 12c which ensures the axial spacing between the two zones is greater than or equal to half the length of the hollow tubular part 12. In practice, the axial distance between the two zones is taken at the center of each zone along the X axis.

[0037] Figures 2 and 3 represent an assembly consisting of the self-adjusting centering device 10 of [Fig. 1] and a tool 20 for implementing this device. The operation of this assembly will be described later.

[0038] Note the presence, on the axial section of the entire [Fig. 3], of one or more support elements projecting radially from the internal surface SI of the hollow tubular part 12 and away from this internal surface. In this embodiment, several support elements 12f, 12g, and 12h are formed on this internal surface, as shown in the cross-section of [Fig. 4] (plane of section IV-IV of [Fig.3]). Each support element 12f, 12g, 12h takes, for example, the form of a radial protrusion which extends over a relatively small radial distance, so as to leave a sufficient central axial passage (the axial passage is centered relative to the hollow tubular part) to allow the axial sliding passage of the implementation tool of the self-adjusting centering device 10. The protrusions 12f, 12g, 12h are here angularly arranged at 120° to each other.

[0039] Each projection 12f, 12g, 12h extends along a relatively small angular sector in order to leave a sufficient free angular space E1, E2, E3 between two consecutive projections (along a circumferential direction). These free spaces or angular sectors allow external radial elements of the tool to pass axially through them and, subsequently, by a simple rotation of the tool 20 around its axis, to pivot the external radial elements so that they are arranged in an angular position corresponding to that of the projections 12f, 12g, 12h forming axial supports (stops) for the external radial elements of the tool.

[0040] The protrusions 12f, 12g, 12h are formed in a portion of the hollow tubular part 12 which is located between one of its two axially open opposite ends 12a, 12b and the deformable zone closest to that end. In this case, it is the ZI zone and the end 12a.

[0041] The number of protrusions can of course vary and therefore their angular spacing, as well as their shape (here trapezoidal in cross-section).

[0042] Figures 2 to 4 illustrate the temporary assembly formed by the self-adjusting centering device 10 of [Fig. 1] and the aforementioned tool 20 for implementing this device. In these figures, the tool 20 has been inserted axially inside the device 10 through the axially open end 12a of the hollow tubular part 12.

[0043] Generally, the tool 20 is in two parts and comprises a first part 22 and a second part 24, both elongated along a longitudinal axis which is coincident here with the longitudinal axis X of the tubular part 12.

[0044] The two parts 22, 24 are assembled together such that the first part 22 forms an external sleeve 22a around the second part 24, which it surrounds coaxially. As shown in [Fig. 3], the sleeve 22a of the first part 22 surrounds the second part 24 only along a portion of the latter's length. The second part 24 is thus engaged inside the first part 22 along a first portion 24a of its length, while the second part 24b extends axially freely inside the part 12 until it reaches a perforated bottom 12 of the latter, into which the distal end 24bl of the second part 24b is inserted axially to be fixed and, thus, to immobilize the second part relative to the hollow tubular part 12.

[0045] The first part 22 and the second part 24 each have an operating or actuating head 22c, 24c located at the same longitudinal end of the tool. The two operating heads 22c, 24c are thus arranged on the same side of the tool, outside of the part 12, so that they can be actuated from the outside by a user. The first part 22 also includes a thinner portion 22b that extends between the actuating head 22c and the outer sleeve 22a.

[0046] The first part 22 and the second part 24 are configured and assembled with each other so that they can slide axially relative to each other. Since the second part 24 is fixed relative to the tubular part 12, it is the first part 22 that is able to slide axially relative to the second part 24, by actuating the operating head 22c of the first part 22 relative to the operating head 24c of the second part 24, which remains fixed.

[0047] The operating head 22c of the first part 22 is arranged axially between the outer sleeve 22a of this first part and the operating head 24c of the second part 24. More specifically, the operating head 22c is arranged axially between the axial end 12a of the part 12 and the operating head 24c. The initial (rest) position of the tool (after being inserted into the hollow tubular part and before deformation of the tubular part 12) is that illustrated in Figures 2 and 3. The operating head 22c of the first part 22 is at a distance from the operating head 24c of the first part 24: an axial clearance J is present between the two operating heads 22c and 24c.

[0048] The relative axial sliding of the first part 22 with respect to the second part 24 is achieved by an axial pull (arrow Fl in Figures 2 and 3) exerted on the operating head 22c of the first part 22 towards the fixed operating head 24c of the second part 24. Thus, the user can, with one hand, hold the operating head 24c against their palm and, using their fingers, exert a pull on the operating head 22c to bring it against the operating head 24c and thus eliminate, or at least greatly reduce, the axial play J. This movement is similar to that performed by the user of a syringe when they want to empty the syringe plunger with liquid.

[0049] More particularly, the first part 22 comprises, on the outer surface of the outer sleeve 22a, one or more external radial elements that project radially from and away from this outer surface, as shown in [Fig. 4]. Here, three external radial elements 22a1, 22a2, 22a3 extend radially away from the outer surface of the outer sleeve 22a. The number three is adapted to the number of internal radial projections 12f, 12g, and 12h so that, by a simple rotational movement of the first part 22 relative to the second part 24, the elements 22a1, 22a2, 22a3, which are offset in [Fig. 4], angularly relative to the protrusions 12f, 12g and 12h, are in geometric (angular) correspondence with these protrusions. Thus, by exerting an axial tension (along the arrow Fl of [Fig.3]) on the first part 22, via its operating head 22c, the members 22al, 22a2, 22a3 come into axial contact against the protrusions 12f, 12g and 12h opposite, which makes it possible to axially stretch the tubular part 12 and therefore to radially shrink the deformable zones Zl, Z2.

[0050] The preceding operations are performed when it is desired to insert part 22 into a pyrotechnic block, particularly to center the latter with respect to the various user tools. The tool configuration allows control of the expansion of the centering device and its radial retraction.

[0051] In practice, the tool 22, which is engaged in the tubular or centering piece 12 (Figures 2 and 3), is manually operated by an operator, via its control heads, to extend it axially and thus retract the deformable areas Z1, Z2 (elongated portions or retracted branches). The assembly [Fig. 2], consisting of the tool 22 and the tubular piece 12, can then be slid or inserted into the internal channel / cavity of the pyrotechnic block to be centered, without the deformable areas Z1, Z2 rubbing against the internal walls of the channel / cavity of the pyrotechnic block. When the assembly is in the correct axial position inside the channel, the tool 22 is released by the operator, and the deformable areas Z1, Z2 return to their initial geometry and press against the internal walls of the channel of the block. Then, the tool is 22 pivoted so that the organs 22al, 22a2 and 22a3 are opposite the open spaces El, E2 and E3 ([Fig.4]).The tool 22 can then be removed axially by translation through the tubular part 12 which, for its part, is held in axial position due to the clamping force of the deformable zones Z1, Z2 against the internal walls of the channel.

[0052] Fig. 5 is an axial section representing the position of the tubular part 12 inside the internal channel C of a pyrotechnic block B, after removal of the placement tool 22.

[0053] Figure 6 shows an axial cross-section of the assembly consisting of block B and its self-adjusting centering piece 12 mounted on an inhibition tool 30 with its own centering device. The tool 30 comprises an upper centering device 32 and a lower centering device 34, and a central rod 36. The central rod 36 passes axially through the piece 12 and is mounted and fixed, by a first axial end 36a, in a lower centering sleeve 34a. The axial end 12b of the piece 12 is, in turn, mounted on the upper part 34a of the lower centering sleeve 34a and coaxially surrounds a portion of the axial end 36a. At the level of the upper centering device 32, the opposite axial end 12a of the part 12 is mounted around a shim 40 which is mounted on the lower part 32al of an upper centering sleeve 32a of the upper centering device 32. The central rod 36 passes axially through the upper centering sleeve 32a of the upper centering device 32 and its end 36b emerges axially above the latter and is held screwed by a clamping nut 42.

[0054] In its lower part, the lower centering sleeve 34a is slidably mounted in the central part of a hollow support or base 44 and is immobilized, by its thinned lower part 34a2, by means of a clamping device 45, of the washer and nut type, disposed in the lower hollowed part of the base 44 and cooperating with the distal end of the thinned lower part 34a2. The body 46 of the tooling (ferrule) bears vertically on a periphery of the base 44. This tooling makes it possible to coat the external surface of the block B with an inhibiting varnish identified by the reference Vi in [Fig. 6] and which is externally delimited by the ferrule 46 of the tooling.

[0055] Generally, the injection of varnish Vi is carried out through a fitting 47, called a cannula, which is screwed onto the base 44, specifically into a peripheral wall 44a of the latter that surrounds the intermediate part 34a3 (body) of the lower centering sleeve 34a, located between the upper part 34a1 and the lower part 34a2. The injected varnish Vi fills the calibrated gap between the base 44 and the sleeve 34a, then spreads peripherally around the sleeve 34a and fills the gap left between the inside of the ferrule 46 and the outer surface of the pyrotechnic block B. The varnish Vi is finished being injected when it overflows at the top of the assembly, at the level of the reservoir 48. This is achieved, for example, by a visual check by the manufacturing operators who observe the arrival of the varnish in the reservoir and then stop the injection.

[0056] Figure 7 schematically represents the assembly consisting of block B coated with the inhibiting varnish Vi and its self-adjusting centering piece 12 mounted inside an enclosure 50. It should be noted that to move from the position of Figure 6 to that of Figure 7, the centering device 12 was removed from block B (for example, using the tool shown in Figures 2 and 3), block B was inverted (the upper face of the block in Figure 6 becomes the lower face of the block in Figure 7), the centering device 12 was replaced inside the block, and the assembly was placed in the enclosure 50. The tooling of Figure 6 has been removed. The closed enclosure includes a base 2 in which a centering pin 54 is fixed, extending axially upwards. The self-adjusting centering piece 12 is mounted, by its axial end 12b around the centering pin 54. The body of the enclosure forms a ferrule 56 which extends axially from the base 52 and surrounds coaxially the block B.The enclosure is closed at its upper part by a cover 58 bearing against the upper edge of the ferrule 56. An upper closing and tightening piece 60 is axially mounted bearing against the upper face of the pyrotechnic block B and the axial end 12a of the self-adjusting centering piece 12. The cover 58 bears against the piece 60 to ensure the assembly is properly closed. The... Part 60 is a high centering device which is centered in the upper part of the pyrotechnic block B. It is a cylindrical part, placed on the upper face of the pyrotechnic block inhibited with varnish Vi and centered via an adjustment between the outer diameter of this part and the inner diameter Di of the varnish Vi which overhangs the upper face of the pyrotechnic block, as illustrated in [Fig.7].

[0057] This upper centering device 60 can be equipped with a ball pusher 60a which transmits a clamping force between the support cover 58 and the pyrotechnic block B. This allows control of both the holding of the pyrotechnic block in static position during the shimming operation and also the level of sealing between the inhibited pyrotechnic block and the bottom 52 of the structure to prevent any leakage of the shimming varnish Vc outside of the assembly.

[0058] As shown in [Fig.7], a sizing varnish Vc fills the peripheral space between the inner face of the ferrule 56 and the varnish Vi of block B so as to coaxially surround the block coated with its inhibiting varnish.

[0059] Generally, the Vc sealing varnish is applied by gravity pouring. Its application is managed by an external device, such as an injection device, and it is poured at atmospheric pressure from the top of the assembly. The varnish is fluid enough that it spreads perfectly around the pyrotechnic block and fills all the gaps encountered.

[0060] It should be noted that once the setting varnish has been applied and has solidified, the tooling can be removed. To do this, the cover 58 is removed, as well as the upper centering device 60, and the housing 50 is rotated 90° to bring it to a horizontal position. For example, a rod (for example, of the type shown in [Fig. 6]) is inserted through the open end of the block-centering device assembly 12 (this end is the upper end in [Fig. 7]) and slid inside the centering device 12 to its opposite end to axially push the centering pin 54 and expel it from the bottom 52 outwards. The centering device 12 can, for its part, be removed from the block using the tool described above with reference to figures 2 and 3. The block wrapped in its shimming varnish Vc can then be removed from the enclosure 50 under the effect of its weight, by tilting the enclosure downwards.

[0061] Figures 8 and 9 are schematic views showing a variant of a self-adjusting centering device 12' for a pyrotechnic block. The only differences between the device in Figures 8 and 1 lie in the configuration of the two opposing axial ends 12a' and 12b' of the device 12'. Apart from this aspect, everything described above applies here and will not be repeated.

[0062] Each end 12a', 12b' is provided with elastic strips arranged axially along the longitudinal axis X of the device and distributed regularly around the circumference of the end concerned. In this example, three strips are provided but a different number can alternatively be considered depending on the device configurations, particularly its diameter.

[0063] The three lamellae 12bl', 12b2', 12b3' of the end 12b' and the three lamellae 12al', 12a2', 12a3' of the end 12a' are visible in Figures 8 and 9 (Fig. 9 is an axial cross-sectional view showing the interior of the device of Fig. 8), and in particular the presence on an inner face of a lamella 12b3' of a radially internal pin Pb' (e.g., hemispherical protrusion) and the presence on an inner face of a lamella 12a3' of a radially internal pin Pa' (e.g., hemispherical protrusion). Although not shown in the figures, all the lamellae are provided with such a pin. In the configuration described and illustrated, the lamellae are arranged respectively along the same generatrices as the elongated portions / branches of the deformable zones Z1, Z2. However, the lamellae can be angularly offset relative to these generatrices.Furthermore, the elongated portions / branches of the two zones Z1, Z2 can also be angularly offset from each other.

[0064] In general, the function provided by this embodiment is to eliminate the play between the centering elements of the self-adjusting centering device 12 on the inhibiting or shimming tools, where zones Z1 and Z2 are there to eliminate the play between the pyrotechnic block and the tooling. The pins carried by the inner faces of the slats allow adjustment of the contact pressure between each slat that carries it (and therefore the self-adjusting centering device) and the centering piece (centering sleeve, centering pin, etc.) on which each end is mounted. This configuration thus makes it possible to compensate for the existing functional play between the self-adjusting centering device and the centering piece (support tooling) by absorbing the radial dimensional difference between them.

[0065] The representation in [Fig. 9] shows that the end 12b' of the tubular part 12' is thicker than the opposite end 12a' (as in [Fig. 3] with the ends 12a and 12b of part 12). This is because the thickened end 12b' is the one mounted on the lower centering piece 34a of [Fig. 6] and on part 54 of [Fig. 7] in order to exert a higher clamping force at the bottom (due to significant friction) than the clamping force exerted at the top, between the thinner opposite end 12a' and the upper centering piece. Thus, this differential clamping force allows the upper centering piece to be removed without causing the centering device 12' to be removed, as it is more securely held at the bottom thanks to the higher clamping force. The tooling assembly and disassembly operations are therefore facilitated.The thickened end 12b' of the centering device is the one opposite the end 12a' through which the centering device placement tool (Figures 2 and 3) is introduced into the latter.

[0066] Furthermore, due to this thickened end 12b', in order to maintain a certain flexibility / elasticity, the lamellae of this end are made by removing material from the thickness of the end and thus have a recessed conformation or in the form of an axial recess relative to the external surface of the tube, as illustrated in figures 8 and 9 for the lamella 12b 1'. All the lamellae of this end are formed in the same way.

[0067] In addition, for both ends 12a' and 12b', keeping the material between the slats rather than removing it helps to protect the slats during handling of part 12' or during its storage.

[0068] Although the present invention has been described with reference to specific embodiments, it is evident that modifications and changes can be made to these examples without departing from the general scope of the invention as defined by the claims. In particular, individual features of the various embodiments illustrated / mentioned can be combined in additional embodiments. Therefore, the description and drawings should be considered in an illustrative rather than a restrictive sense.

[0069] It is also evident that all the characteristics described with reference to a process are transposable, alone or in combination, to a system, and conversely, all the characteristics described with reference to a system are transposable, alone or in combination, to a process.

Claims

Demands

1. A self-adjusting centering device for a pyrotechnic block, comprising a hollow tubular piece (12; 12') elongated along a longitudinal axis (X) and comprising: -two opposite ends (12a, 12b; 12a', 12b') open axially, -two elastically deformable zones (Zl, Z2) spaced axially apart from each other and each disposed at a distance from the two opposite ends of the hollow tubular piece, each elastically deformable zone (Zl, Z2) being configured to retract or expand radially relative to the longitudinal axis (X) under the effect of a stress applied axially to the hollow tubular piece (12; 12').

2. Self-adjusting centering device for a pyrotechnic block according to claim 1, in which the hollow tubular part (12; 12') comprises a tubular wall, each deformable zone (Z1, Z2) being formed in a separate part of the tubular wall and extending both along an axial extension and along a circumference of the tubular wall part, each deformable zone comprising several elongated portions (Z11-Z13, Z21-Z23) separated angularly from each other by axially elongated openings (011-013, 021-023).

3. Self-adjusting centering device for a pyrotechnic block according to claim 2, wherein each elongated portion (Z11-Z13, Z21-Z23) has, along its axial extension, a wavy shape comprising a succession of hollows and bumps which each extend radially relative to the tubular wall of the hollow tubular piece.

4. Self-adjusting centering device for a pyrotechnic block according to the preceding claim, wherein the succession of hollows and bumps mainly comprises a bump (Bl) which extends radially outwards relative to the tubular wall of the hollow tubular part (12; 12') and which is framed axially by two hollows (Cl, C2) extending radially inwards relative to the tubular wall of the hollow tubular part.

5. Self-adjusting centering device for a pyrotechnic block according to any one of the preceding claims, wherein each deformable zone (Z1, Z2) comprises at least three elongated portions.

6. Self-adjusting centering device for a pyrotechnic block according to any one of the preceding claims, wherein the two deformable zones (Z1, Z2) are axially spaced from each other along an axial distance that is greater than or equal to half the length of the hollow tubular piece.

7. A self-adjusting centering device for a pyrotechnic block according to any one of the preceding claims, in which the hollow tubular part has, on its internal surface, between one (12a) of its two axially open opposite ends (12a, 12b) and the deformable zone (Zl) which is closest to this end, one or more support elements (12f-12h) projecting radially from and away from the internal surface, this or these support elements being shaped inside the hollow tubular part so as to leave clear an axial passage centered relative to the hollow tubular part.

8. Self-adjusting centering device for a pyrotechnic block according to any one of the preceding claims, wherein each opposite end (12a', 12b') of the hollow tubular part (12') is provided with elastically deformable slats (12al'-12a3', 12bl'-12b3') along a radial direction so that each end can be fitted tightly around a part whose external diameter is likely to vary.

9. A tool (20) for implementing a self-adjusting centering device for a pyrotechnic block (B) according to any one of the preceding claims, comprising a first (22) and a second (24) elongated parts along a longitudinal axis (X), the first part (22) forming an external sleeve (22a) around the second part (24), which it surrounds coaxially and which is adapted to slide axially relative to the second part, the first part being provided on an external surface of the external sleeve with one or more elements (22a1-22a3) projecting radially from said external surface and away from it, the first and second parts each having, at the same longitudinal end of the tool, an operating head (22c, 24c), the two operating heads being configured to cause the sliding of the first part (22) relative to the second part (24) by displacement of the operating head of the first part relative to the operating head of the second part.

10. Tool according to the preceding claim, wherein the operating head (22c) of the first part is arranged axially between the external sleeve (22a) of the first part and the operating head (24c) of the second part, the sliding of the first part relative to the second part being achieved by a pull exerted on the operating head (22c) of the first part in the direction of the operating head (24c) of the second part.

11. Method of implementing a self-adaptive centering device (12;12') according to any one of claims 1 to 8 using a tool (20) for implementing the self-adjusting centering device of a pyrotechnic block (B) according to claim 9 or 10.

12. A method according to the preceding claim, comprising: - axial insertion of the tool (20) inside the hollow tubular part (12; 12') of the self-adaptive centering device, - displacement of the operating head (22c) of the first part (22) relative to the operating head (24c) of the second part (24) in order to cause axial sliding of the first part relative to the second part (24) and to apply an axial end stress on the hollow tubular part (12; 12') and thus cause radial retraction of the two deformable zones (Z1, Z2) of the hollow tubular part.

13. Method according to the preceding claim, comprising a relative displacement between, on the one hand, a hollow pyrotechnic block (B) having a central longitudinal internal cavity (C) and, on the other hand, the assembly formed by the hollow tubular part (12; 12') of the self-adaptive centering device in a radially retracted position with the tool (20) inserted inside so that the aforementioned assembly is disposed in the central longitudinal internal cavity (C) of the pyrotechnic block.

14. A method according to the preceding claim, comprising a displacement of the operating head (22c) of the first part (22) relative to the operating head (24c) of the second part (24) in order to cause axial sliding in the opposite direction of the first part relative to the second part, and thus to release the axial tensile stress applied to the tubular part

15. hollow (12; 12'), thus causing the radial expansion of the two deformable zones (Z1, Z2) of the hollow tubular piece and their plating against the internal peripheral surface of the central longitudinal internal cavity (C) of the pyrotechnic block (B). Method according to the preceding claim, the movement of the operating head (22c) of the first part (22) relative to the operating head (24c) of the second part (24) being achieved by releasing the axial extension stress applied to the hollow tubular part (12; 12'), thus causing the radial expansion, by elastic return, of the two deformable zones (Z1, Z2) of the hollow tubular part and their pressing against the internal peripheral surface of the central longitudinal internal cavity (C) of the pyrotechnic block (B).

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