FR2795799A1 - Fluid tight hollow cylindrical plug for cast metal or plastic article has body containing chuck plastically deforming body radially outwards when chuck pulled out of body - Google Patents

Abstract

A hollow cylindrical plug has a body containing a chuck that plastically deforms the body radially outwards when the chuck is pulled out of the body. The internal diameter of the body narrows at its open end and the chuck has a bulge whose diameter is larger than the internal diameter of the open end. An Independent claim is included for the following: (a) Manufacturing the above plug from the chuck and a preform of the body. The preform has a solid base fitted with a skirt. The skirt is shaped to capture the bulging end of the chuck.

Description

The present invention relates to a device for permanently sealing a hole, in particular a hole in a piece coming from a foundry or plastic molding, said device comprising - a plug having a longitudinal axis and delimiting a blind longitudinal cavity, - a mandrel laying longitudinal engaged in the cavity and capable of causing a plastic transverse expansion of the cap parltranslation longitudinally with respect thereto.

Such a device is used, for example, to close off a fluid passage from a foundry or plastic molding, which makes it possible to avoid making a thread for receiving a screwed plug as well as the use of sealants. .

In a known embodiment, distributed under the name BETAPLUG SERIE 6000 by the French company LEE COMPANY SA, the plug externally has a frustoconical envelope surface of revolution about said longitudinal axis and converging in a longitudinal direction from the opening zone of the cavity towards the bottom zone thereof and it is necessary to give a corresponding shape to the inner peripheral face of the hole so that the cap comes to immobilize therein by a conical fitting shape. The cap has, moreover, to delimit the cavity, an inner peripheral face which also has a frustoconical shape of revolution about said longitudinal axis and converges in the same direction as the envelope surface of the outer peripheral face and, after engaging the plug in the hole is pressed and then left permanently in the cavity of the plug a frustoconical mandrel pin which causes the plastic expansion of the plug, thereby reinforcing the force of application of the outer peripheral face of the latter against the peripheral face inside the hole.

This known embodiment is not entirely satisfactory in that it requires suitably to conform the hole for receiving the cap, on the one hand, and to the extent that the conical fitting causes a certain inaccuracy in the relative longitudinal positioning of the stopper and the hole once assembly is made, on the other hand.

In addition, for a given force of application of the outer peripheral face of the plug against the inner peripheral face of the hole, the plug is less resistant to longitudinal thrusts applied in the direction of the increase of the respective cross sections than in the direction the decay of these respective cross sections.

In addition, insofar as the mandrel engaged in the plug cavity is left, the respective constituent materials of the plug, that is to say generally aluminum or an aluminum alloy, and the mandrel, ie, generally steel, are exposed on the side towards which the plug cavity opens, which provides corrosion and battery effects.

The object of the present invention is to remedy these drawbacks, and, to this end, the present invention proposes a device of the type indicated in the preamble, characterized in that - the cap has externally a longitudinal, cylindrical envelope surface, - the cavity the plug has a narrowed cross-section in an opening area of the cavity, the laying mandrel has an enlarged cross-sectional enlargement, larger than said narrowed cross-section of the cavity, in a bottom zone thereof; ci so as to cause said expansion of the plug by longitudinal extraction out of the cavity thereof and passage, forcibly, said bulge in the opening area of the cavity.

Preferably, as in the prior art, the plug and the mandrel have a respective symmetry of revolution about said longitudinal axis.

The cylindrical shape, in particular of revolution, that presents the envelope surface of the plug of this device according to the invention is accompanied by a cylindrical shape, in particular of revolution, with regard to the inner peripheral face of the hole to be butchered, which simplifies the development of the latter, on the one hand, and allows to choose at will the longitudinal position in which the stopper will be immobilized relative to the hole, during the introduction of the device according to the invention, other share.

In addition, once installed, the cap resists in the same way to the longitudinal thrusts applied in one direction that longitudinal thrusts applied in the other direction.

Finally, it is observed that the cap is immobilized by progressive extraction of the laying mandrel, so that only the cap is in place after its immobilization in the hole and that, therefore, only the material constituting the cap is exposed. fluids, whether on one side or the other of the cap. The risk of corrosion is greatly reduced, and any risk of battery effect disappears.

According to a preferred embodiment of the invention, and in a manner known per se, the cap externally comprises a longitudinal alternation of transverse annular grooves, in particular of revolution about said longitudinal axis, recessed towards it relative to said envelope surface, and transverse annular ribs, in particular of revolution about said longitudinal axis, defining said envelope surface, which facilitates the plastic deformation of the plug and its firm application against the inner peripheral face of the hole.

In order to facilitate the progression of the bulge of the mandrel in the plug cavity during installation, it is preferably provided that the bulge of the mandrel has a cross section which decreases progressively in a longitudinal direction of directional extraction from the bottom zone to the opening area of the cavity.

In addition, it is also advantageously provided that the cross section of the cavity decreases progressively in said longitudinal direction, in a manner complementary to the bulge of the mandrel.

Naturally, the plug and the mandrel must be made of the most appropriate respective material, namely a ductile material with respect to the plug and a material as little compressible as possible with respect to the mandrel; in this respect, for example, the plug is advantageously made of a material chosen from a group comprising aluminum and its alloys, in a manner known per se, whereas the mandrel may be made of steel; in any case, these materials can be chosen without fear of any stack effect between them after the installation of the cap, insofar as the mandrel does not remain engaged in the latter after installation.

in addition to the device characterized in the manner indicated above, the present invention provides a particularly advantageous method for the manufacture of such a device.

this method is characterized in that the mandrel, comprising said bulge, is produced on the one hand, and on the other hand a plug blank comprising a transverse bottom and a longitudinal skirt integral with the bottom and having a longitudinal inner peripheral face, cylindrical, of cross section at least equal to that of the bulge of the mandrel, intended to define the opening area of the cavity and, with the bottom, the bottom zone thereof, and then introduced longitudinally the mandrel by its bulge in the blank, until the bulge of the mandrel reaches the immediate vicinity of the bottom, then the blank of the plug is crimped on the mandrel causing a plastic shrinkage of the skirt in an area lying longitudinally opposite the bottom relative to the bulge of the mandrel to form the opening area of the cavity and trap the bulge in the cavity of the plug thus formed.

Particularly advantageously, when the stopper must comprise externally a longitudinal alternation of transverse annular grooves and ribs, in particular of revolution, according to the preferred embodiment indicated above, said grooves are formed by performing the crimping of the blank of the stopper on the stem by rolling. Thus, a single rolling operation allows both to develop the grooves and perform crimping.

Other features and advantages of these two aspects of the invention will emerge from the description below, relating to a nonlimiting example of implementation, and the accompanying drawings which form an integral part of this description.

Figure 1 shows a view of a device according to the invention in section through a plane including its longitudinal axis, before laying in a hole to be closed.

FIG. 2 shows a view of the plug of this device after its installation in such a hole, in section through a plane passing through the then common axis of the plug and the hole.

Figures 3 and 4 respectively show a plug blank and the mandrel before their mutual assembly to produce the device according to the invention, in views similar to those of Figures 1 and 2.

Reference will firstly be made to FIG. 1, which shows the device according to the invention 1 as it is delivered to its users.

This device 1 has a symmetry of revolution about a longitudinal axis 2 which will later serve as a reference to the notions of longitudinality and transversality as well as the concepts of axial and radial direction and derived concepts; more specifically, it consists of a hollow plug 3, for example aluminum or aluminum alloy, and a mandrel 4, for example steel, both having such a symmetry of revolution around the axis 2 and arranged coaxially.

The plug 3 comprises, in one piece, a longitudinal tubular skirt 5 and a transverse bottom 6, both sealed and sealed to each other when the plug 3 is intended to seal a hole 7 of a part 8, in particular came from foundry or plastic molding, as will be described later with reference to Figure 2. It will be observed however that the fact that we can place the cap 3 in any desired longitudinal position to the inside a hole 7 allows to consider other applications, including an application in which the plug 3 would be intended to make a constricted passage of fluid inside the hole 7, in which case its bottom 6, otherwise sealed in the same way as the skirt 5, could be pierced with one or more longitudinal passages, including calibrated; the realization of such a variant, not illustrated, is within the normal abilities of a person skilled in the art.

In the direction of a radial distance relative to the axis 2, the skirt 5 is delimited by an outer peripheral face 9 which has a cylindrical envelope surface 10 of revolution about the axis 2 with a diameter d1 approximately equal, although only slightly smaller, for example a few tenths of a millimeter, to a diameter d2 that has an inner peripheral face 11, cylindrical of revolution about an axis 12, of the hole 7.

From a first longitudinally extreme zone 13, in which it connects to the bottom 6, the skirt 5 has on a longitudinal dimension of the order of one-third to one-half of its total longitudinal dimension a cylindrical zone 14 of revolution around the axis 2 with a diameter d3 less than the diameter dl.

From this zone 14 to a second longitudinally extreme zone 15, it has an alternation of grooves 16 and annular ribs 17 of revolution about the axis 2 and giving to the corresponding zone 18 of the face 9, when seen in cut by any longitudinal half-plane defined by the axis 2, a sinuous configuration formed of an alternation of arcs of concave circles in the direction of a distance from the axis 2 and corresponding to the grooves 16 and d convex circles in the direction of a distance from the axis 2 and corresponding to the ribs 17. The grooves 16, mutually identical, and the ribs 17, mutually identical, have for example a respective section of the order from a quarter circle to a semicircle; in the illustrated example, their respective number is three but one could choose different numbers and different shapes of their respective section without departing from the scope of the present invention.

As will be readily understood by a person skilled in the art, it is the ribs 17 which, in their crest zones, that is to say in their zones farthest from the axis 2, have the diameter d1 and define the envelope surface 10 whereas, in their zones closest to the axis 2 or bottom, the grooves 16 define an envelope surface 19 also cylindrical of revolution about the axis 2, with a diameter d4 smaller than the diameter d3.

In a longitudinal direction 20 extending from the longitudinally extreme zone 15 towards the longitudinally extreme zone 13, the zone 14 of the face 9 is connected by means of a frustoconical bevel 21 of revolution about the axis 2 converging into the direction 20 and forming for example an unreferenced angle of 45 with respect to the axis 2, to a plane, transverse front face 22 of the bottom 6; turned in the direction 20, this face has the shape of a disk perpendicular to the axis 2.

In the longitudinal direction opposite to the direction 20, in the longitudinally extreme zone 15, the zone 18 of the face 9 is connected to a front face 23 which is also flat and transverse, whereas it is annular in revolution about the axis 2 and turned in longitudinal direction opposite to the direction 20.

This face 23 borders a blind cavity 24 delimited, inside the cap 3, by the skirt 5 and the bottom 6 thereof and open in the longitudinal direction opposite to the direction 20, in the longitudinally extreme zone 15 of the skirt. 5.

The end face 23 thus connects, in the direction of approach towards the axis 2, the outer peripheral face 9 of the skirt 5 to an inner peripheral face 26 thereof, defining the cavity 24 with a front face, transverse 27 of the base 6, which is offset in the direction 20 relative to the face 23 and may have the shape of a flat disc perpendicular to the axis 2, not shown, where, as it is illustrated, the shape of a concave spherical cap in longitudinal direction opposite to the direction 20 and centered on the axis 2 at a point 28 located outside the cavity 24, that is to say shifted in the longitudinal direction opposite to the direction 20 with respect to the end face 23.

In the direction 20, from the front face 23 to the end face 27, the inner peripheral face 26 of the skirt 5 has three successive zones 28, 29, 30.

The first 28 of these zones, which extends from the face 23, thus constituting an opening zone of the cavity 24, over a longitudinal distance which substantially corresponds to the longitudinal distance separating from this face 23 the junction between the last rib in the direction 17 and the last groove in the direction 16, is cylindrical of revolution about the axis 2 with a diameter d5 less than the diameter d4. In the direction 20, it is extended by the zone 29 in turn frustoconical about the axis 2 so as to gradually disappear in the direction 20, to a longitudinal level which corresponds substantially to that of the connection between the last groove 16, in the direction 20, to the zone 14 of the outer peripheral face 9 of the skirt 5. The zone 29 is thus connected in the direction 20 to the zone 30, again cylindrical of revolution about the axis 2 but with a diameter d6 greater than the diameter d5 although still less than the diameter d4. The zone 30 connects itself in the direction 20 to the front face 27 of the bottom 6 and thus defines a bottom zone of the cavity 24. The zone 30 thus defines with the faces 29 and 27, in the immediate vicinity of the zone longitudinally extreme 13 in which is situated the face 27, an annular groove 31 of revolution about the axis 2 and constituting in the immediate vicinity of the longitudinally extreme zone 13 an enlargement of the cavity 24.

The mandrel 4, better visible in FIG. 4, to which reference will also be made, has a shape such that it is retained by interlocking inside the cavity 24 and can be extracted only by applied traction. in a longitudinal direction opposite to the direction 20, with respect to the plug 3, which traction results in a plastic expansion of the skirt 5 in the direction of a distance relative to the axis 2.

For this purpose, the mandrel 4, considered in the position it occupies when it is engaged and retained in the cavity 24 as illustrated in FIG. 1, has the current shape of a rectilinear, longitudinal rod 32 delimited, in the direction of a distance relative to the axis 2, by an outer circumferential face 33 cylindrical of revolution about this axis 2 with a diameter d7 substantially identical to the diameter d5, so that in the relative position of the mandrel 4 of the plug 3 illustrated in Figure 1, there is established between the face 33 and the region 28 of the inner peripheral face 26 of the skirt 5 a guide contact relative longitudinal sliding. Indeed, in the relative position of the mandrel 4 and the plug 3 shown in Figure 1, the mandrel 4 has a first end 34 rotated in the direction 20, in the immediate vicinity of the longitudinally end zone 13, and more precisely the face 27 of the bottom 6, while it has a second end 35 projecting from the cavity 24 in longitudinal direction opposite to the direction 20, and the face 33 extends longitudinally from a level corresponding approximately to that of the connection between the zones. 28 and 29 of the inner peripheral face 26 of the skirt 5 to the end 35 of the mandrel 4 located outside the cavity 24.

In the direction 20, this outer peripheral face 33, cylindrical of revolution about the axis 2, is connected to an outer circumferential peripheral face 36 of revolution about the axis 2 and flaring in the direction 20 identically to the zone 29 of the inner peripheral face 26 of the skirt 5, to be connected to an outer circumferential face 37 cylindrical of revolution about the axis 2 with a diameter d8 greater than diameters d5 and d7 and substantially equal to, or slightly lower, at the diameter d6 of the zone 30 of the inner peripheral face 26 of the skirt 5. In the direction 20, the outer peripheral face 37 is connected to a front face 38 embodying the first end 34 of the mandrel 4 and having, for example, the shape d a spherical cap convex in the direction 20 and complementary to the face 27 of the bottom 6, as illustrated, or a flat shape and perpendicular to the axis 2, f not illustrated but easily understandable by a person skilled in the art. The faces 37 and 38 can thus be placed in contact with the zone 30 of the face 26 and in contact with the face 27, respectively, in a manner not illustrated, or be placed in close proximity thereto, respectively, but without contact, as illustrated; it is the same of the face 36 vis-à-vis the area 29 of the face 26. In both cases, the faces 36, 37 and 38 define in the immediate vicinity of the first end 34 of the mandrel 4 a bulge 39 annular revolution around the axis 2 and sufficiently complementary to the groove 31 to ensure retention of the mandrel 4 in the position shown in Figure 1, relative to the plug 3.

The bulge 39 has the same rigidity as the rod 32 and is rigidly connected thereto, in particular by being produced in one piece with the latter, and this rigidity is expressed in particular in terms of incomprehensibility in the sense of a comparison with respect to the axis 2, in comparison with a ability of the skirt 5 to expand by plastic deformation in the direction of a distance relative to this axis 2, under operating conditions of installation of the 3 which will be described now, with reference to Figures 1 and 2. To ensure this pose, using a not shown tool, known in itself, of the type used to ensure the installation of rivets blind. Such a tool is able to bear in the direction 20 on the face 23 of the skirt 5 of the plug 3, to grasp the rod 32 by the end 35 of the mandrel 4, and to apply to the latter a traction in longitudinal direction opposite to the direction 20 relative to the plug 3.

In an initial phase of laying, without applying such traction, is introduced coaxially into the hole 7 the device according to the invention 1, further consisting of the plug 3 and the mandrel 4 retained in the cavity 24 of the latter, until bring the plug 3 into the position it will definitely occupy inside the hole 7. It will be observed that this position can be freely chosen in the then common longitudinal direction of the axes 2 and 12.

During a second phase, by means of the tool, the aforementioned traction, in the direction opposite to the direction 20, is applied to the positioning mandrel 4 relative to the plug 3 then retained in place by the tool at inside the hole 7. Given that the diameter d8 is greater than the diameter d5, the passage of the bulge 39 inside the zone 28 of the inner peripheral face 26 of the skirt 5 under the effect of this traction is possible but is necessarily accompanied by a radial plastic expansion of the latter, accompanied by a progressive plastic crushing of the ribs 17 on the inner peripheral face 11 of the hole 7. More precisely, while the diameters d3 of the zone 14 of the outer peripheral face of the skirt 5 and d6 of the zone 30 of the inner peripheral face 26 of this skirt 5 remain unchanged, the minimum diameter of the frustoconical zone 29 of this inner peripheral face 26 and the diameter of its zone 28 take the value d8 of the diameter of the outer peripheral face 37 of the bulge 39 of the rod 32 and the diameter of the envelope surface 10 of the outer peripheral face 9 of the skirt 5, that is to say the maximum diameter ribs 17, passes from the value di to the value d2 of the diameter of the inner peripheral face 15 of the hole 7. This increase in diameter of the zones 29 and 28 of the inner peripheral face 26 of the skirt 5 and the envelope surface 10 of the zone 18 of its outer peripheral face 9 is progressively made for areas of the skirt 5 increasingly close to the longitudinally extreme zone 15 thereof, progressing in a longitudinal direction opposite to the direction 20 as as the bulge 39 progresses in the direction opposite to the direction 20, inside the cavity 24. When the bulge 39 reaches the longitudinally end zone 15 of the skirt 5, the mandrel 4 escapes from the cavity 24 in the longitudinal direction opposite to the direction 20, and the plug 3 remains immobilized inside the hole 7 by application, under a strong pressure resulting from the plastic expansion of the skirt 5, against the inner peripheral face il of the hole 7 by the ribs 17 which thus ensure both a fastening of the cap 3 by friction with the part 8 and a seal between the plug 3 and the part 8.

Various embodiments of the device 1 according to the invention can be envisaged, but an embodiment is preferred that implements a plug blank 40 3 illustrated in FIG.

It emerges from this FIG. 3, to which reference will now be made, that the blank 40 already has in its definitive forms the bottom 6, that is to say its end faces 22 and 27, as well as the bevel 21, the zone 14 of the outer peripheral face 9 of the skirt 5 and the zone 30 of its inner peripheral face 26. However, the latter uniformly presents the diameter d6 of the zone 30, from one to the other of the extreme longitudinal zones 13 and 15 of the skirt 5.

The zone 18 of the outer peripheral face 9 of the latter has a cylindrical shape of revolution about the axis 12, with a diameter d9 greater than the diameter d3, the two zones 14 and 18 being mutually connected by a facet 41 frustoconical of revolution about the axis 12 with a convergence in the direction 20 and an angle for example of the order of 45 relative to the axis 12.

The difference between the diameters d9 and d6 is approximately equal to the difference between the diameters di and d5 so as to allow the assembly of the blank 40 and the mandrel 4 and the deformation of the blank 40 to make the plug 3 under conditions that will be described now.

The laying mandrel 4 having been made in its definitive form, previously described, is engaged in the direction 20, by its first end 34, in the cavity 24 of the blank 40 until the front face 38 of the mandrel 4 adjoins the front face 27 of the bottom 6. The relationship between the diameter d8 of the outer peripheral face 37 delimiting the bulge 39 of the mandrel 4 and the diameter d6 that the inner peripheral face 26 of the skirt 5 of the blank 40 presents on the whole of its longitudinal dimension allows this introduction and promotes a coaxiality of the mandrel 4 and the blank 40.

When the front walls 38 and 7 are directly adjacent, that is to say when the outer peripheral faces 37 and 36 and a portion of the outer peripheral face 33 of the rod 32 are placed facing the zones 30, 29, 28 of the inner peripheral face 26 of the skirt 5 of the blank 40, respectively, in radial directions with reference to the axis 2, it causes the crimping of the skirt 5 of the blank 40 on the rod 32 of the mandrel 4 .

More specifically, for this purpose, is applied to the zone 18 of the outer peripheral face 9 of the skirt 5 of the blank 40, for example by rolling in the area of each of the grooves 16 to achieve, a thrust towards the axis 2 to bring the zones 28 and 29 of the inner peripheral face 26 of the blank 40 bearing against the outer peripheral faces 33 and 36 of the rod 32.

The deformation then undergone by the skirt 5 is an at least partially plastic deformation, which may be followed by a slight elastic expansion of the skirt 5, and the zone 28 of the inner peripheral face 26 takes the diameter d5 which may be slightly greater at d7 but is in any case less than the diameter d8, while the rolling formed the grooves 16 leaving between them the ribs 17 defining the envelope surface 10 of diameter di.

In other words, the device according to the invention 1 as described with reference to FIG. 1 is completed.

Naturally, this method of manufacturing the device according to the invention 1 as illustrated in FIG. 1, as well as this device itself, could have many variants without thereby going beyond the scope of the invention. present invention.

Claims (3)

1. Device for permanently sealing a hole (7), in particular a hole (7) in a piece of casting (8) or plastic molding, said device comprising. - a plug (3) having a longitudinal axis (2) and defining a blind longitudinal cavity (24), - a longitudinal laying mandrel (4) engaged in the cavity (24) and capable of causing a plastic transverse expansion of the plug ( 3) by longitudinal translation with respect thereto, characterized in that - the plug (3) externally has a longitudinal, cylindrical envelope surface (10), - the cavity (24) of the plug (3) has a narrowed cross-section in an opening region (28) of the cavity (24), the laying mandrel (4) has a bulge (39) of larger cross-section, larger than said narrowed cross-section of the cavity (24), in a bottom region (30) thereof, so as to cause said plug (3) to expand by longitudinal extraction out of the cavity (24) thereof and forcing said bulge (39) into the opening zone (15) of the cavity (24). 2. Device according to claim 1, characterized in that the plug (3) and the laying mandrel (4) have a respective symmetry of revolution about said longitudinal axis (2). 3. Device according to any one of claims 1 and 2, characterized in that the plug (3) externally comprises a longitudinal alternation of transverse annular grooves (16) recessed towards said longitudinal axis (2) relative to said surface. envelope (10), and transverse annular ribs (17) defining said envelope surface (10). <B> 4. </ B> Device according to any one of claims 1 to 3, characterized in that the bulge (39) of the mandrel (4) has a cross section which decreases gradually in a longitudinal direction of extraction ( 25) directed from the bottom zone (30) to the opening zone (28) of the cavity (24). 5. Device according to claim 4, characterized in that the internal cross section of the cavity (24) decreases progressively in a longitudinal direction of extraction (25) directed from the bottom zone (30) to the opening zone ( 28) from the cavity (24) to this opening region (28), complementary to the bulge (39) of the mandrel (4). 6. Device according to any one of claims 1 to 5, characterized in that the plug (3) is a material selected from a group comprising aluminum and its alloys. 7. Device according to any one of claims 1 to 6, characterized in that the mandrel (4) is made of steel. <B> 8. </ B> A method of manufacturing a device (1) according to any one of claims 1 to 7, characterized in that one carries out firstly the mandrel (4), comprising said bulge (39), and secondly a blank plug (40) having a transverse bottom (6) and a longitudinal skirt (5) integral with the bottom (6) and having a cylindrical longitudinal inner peripheral face (26), of cross section at least equal to that of the bulge (39) of the mandrel (4), intended to define the opening area (28) of the cavity (24) and, with the bottom (6), the bottom zone ( 30) thereof, and then the mandrel (4) is introduced longitudinally through its bulge (39) into the blank (40) until the bulge (39) of the mandrel (4) reaches the immediately from the bottom (6), then the blank of the plug (40) is crimped onto the mandrel (4) causing the skirt (5) to shrink plastically in a longitudinally located zone. ent opposite the bottom (6) with respect to the bulge (39) of the mandrel (4) to form the opening region (28) of the cavity (24) and to trap the bulge (39) of the mandrel (4) in the cavity (24) of the plug (3) thus formed. 9. The method of claim 8, for producing a device according to claim 3, characterized in that one forms said grooves (16) by performing crimping by rolling.