EP0133826A1 - Method of strengthening crimpings and crimped sealings, in particular for packages - Google Patents

Abstract

1. Process for assembling a first and a second piece with thin walls, particularly a body (10) and a base (28) of a metallic package of the barrel type by a crimped fastening having, in a crimped zone of given height, a plurality of layers belonging alternately to two neighbouring margins of the pieces to be assembled, a fold previously made in one of the neighbouring margins increasing, over a predetermined fraction of the said height, the number of layers, the said procedure involving after the pieces to be crimped are put in position the successive use of a roll moulder (31) for rolling the margin (30) of the second piece around and with the margin of the first piece, then a crimping moulder (33) for pressing and laminating which presents a working surface profile essentially parallel to that of the mandrel (32) for supporting the assembly, the said procedure being characterized by the fact that the squeezing phase of the crimping in ended when the working surface of the crimping moulder (33) reaches a distance from the facing surface of the mandrel (32) equal to the sum of six thicknesses of the metal forming the alternating layers of the two pieces to be assembled, and in that the phase of lamination which follows the squeezing phase reduces this distance to almost five thicknesses of the metal.

Description

The present invention relates to crimped seals, in particular for packaging with bottoms assembled to the body by crimping, in particular metal drums or the like, seals of the kind where the bordering edges of the body and of the bottom constitute generally alternating layers of an interlaced structure. extending over a certain height in an axial direction. We know the so-called single, double and triple crimps comprising respectively three, five and seven layers capable of coming alternately from the bordering edges of the two parts to be assembled, the double and the triple crimping corresponding to the techniques practiced most commonly in the case of metal drums or composites.

The crimping constituting the zone most exposed to the risks of dislocation of the packaging, in particular in the event of accidental fall, we have long sought means capable of improving the mechanical resistance of this type of seals.

We have thus described from 1919 (cf. patent GB 142,967) a process tending to reinforce a crimped joint, according to which, in the assembly by crimping a bottom of a metal barrel, the edge of the bottom of the so as to put it in overthickness, then the crimping was carried out so that the parts of the bottom and of the barrel body arranged opposite the overthickness are pushed back by determining an inflection of the structure of the setting along its height.

Patent BE 793,875 describes the application of such a process to double crimping by indicating the possibility of operating the prior folding either on the bottom edge, or on the body edge of a metal barrel or the like.

This kind of process leads to joint structures confined between two boundary surfaces, at least one of which has an inflection or undulation of amplitude corresponding substantially to the excess thickness formed by the prior folding of the bordering edge of at least one of the parts. assemblies. By keeping for example practically straight the pro wire of the external limit surface of the joint, it is the profile of the internal limit surface of the joint which is affected by the inflection or undulation by imposing in the structure of the joint a sinuous course essentially affecting the layer or layers located on the side interior compared to the original fold of the extra thickness.

A crimp structure thus determined is obviously capable of providing an improvement in the mechanical strength of the joint with regard to certain types of stress. Experience shows, however, that this improvement remains limited, in particular due to the limitation of the amplitude of the inflection to the thickness of a wall.

With still another object of strengthening the mechanical strength of joints of the type considered, the present invention provides a technique capable of surprisingly increasing the efficiency of the reinforcement obtained.

Also starting from the fold back on itself of one of the bordering edges of the parts to be assembled by a crimping comprising in a crimp zone of given height a plurality of layers belonging alternately to the two bordering edges, said fold increasing over a predetermined fraction of said height the number of layers of said plurality, the method according to the invention is essentially characterized by a rolling operation of the structure thus formed until its thickness is equalized over said given height.

The fold is thus imprinted in the metal of the adjacent layers with a more or less pronounced thinning of all the layers; the fold thus becomes a sort of strongly anchored core between adjacent layers which are themselves hardened by a work hardening effect. Sealing is itself greatly improved due to the multiplicity of baffles created at the interfaces.

The increase in efficiency of the reinforcement thus obtained can indeed be attributed, on the one hand, to the fact that the rolling operation according to the invention causes an inflection affecting all the interfaces in the excess thickness zone, while according to l above-mentioned prior art alone was affected approximately half of the interfaces. The improvement is attributable, on the other hand, to the fact that the elastic limit can be greatly exceeded in all the zone of overthickness affected by rolling, while in the prior art the elasticity of the layers affected by the deformation could remain practically intact, leaving a tendency for a bending recovery. Following rolling according to the invention this tendency to straightening can be practically eliminated; the "nerve of the sheets" can be "broken" according to the imaginary expression of those skilled in the art.

The characteristics and advantages of the invention will become apparent from the following description of an application by way of example to the assembly by double crimping of a bottom and of the body of a metal barrel in the shape of a cylinder. circular, with reference to the accompanying drawings in which:

• en figure 1, une phase préparatoire du bord du corps ;
• en figure 2, formage du bord à sertir du corps ;
• en figure 3, emboîtement du fond après dépose d'un joint d'étanchéité ;
• en figure 4, opération de roulage du serti ;
• en figure 5, fin de l'opération de roulage ;
• en figures 6 et 7, l'opération finale de serrage du serti ;
• la figure 8, vue semblable à la figure 7, montre une variante avec repli du bord de fond ;
• les figures 9 à 12 montrent des phases successives d'un mode d'élaboration de la variante de la figure 8.

FIGS. 1 to 7 are partial schematic sectional representations of successive phases of the method according to the invention, namely:

• in Figure 1, a preparatory phase of the edge of the body;
• in Figure 2, forming the crimped edge of the body;
• in Figure 3, nesting of the bottom after removal of a seal;
• in FIG. 4, operation of rolling the seam;
• in FIG. 5, end of the rolling operation;
• in Figures 6 and 7, the final operation of tightening the seam;
• Figure 8, a view similar to Figure 7, shows a variant with folding of the bottom edge;
• FIGS. 9 to 12 show successive phases of an embodiment of the variant of FIG. 8.

According to the embodiment chosen and shown, the body 10 of generally cylindrical shape of a metal barrel, is subjected, according to Figure 1 to a preparatory operation of its end 11 intended to be closed by a bottom to be crimped. For this purpose, the axially projecting part 12 is introduced into the terminal part adjacent to the end 11. a mandrel 13 having a groove 14 opposite a wheel 15 of suitable profile, by attacking the external face 16 of the wall of the body, to push this wall towards the bottom of the groove 14. The result of this preparatory operation of the terminal part of the body is the formation in the profile of the latter of a rod profile hook 19 conforming generally to the profile of the groove 14 of the mandrel and ending in a flat edge. or beak 20 having an inclination between 0 ° and 45 ° relative to the axis of the body.

The following operation, illustrated in FIG. 2, is the forming of a crimping edge 21 obtained by the conventional intervention of a press and a tool 22 for dropping the edges of the usual type comprising a punch part 23 and a flared discharge zone 24 limited by an abutment flange 25. The crimping edge 21 is generally folded in this way in a plane substantially perpendicular to the axis of the body while having, radially inside the ring with hook profile 19 previously formed, a depression marked at 26, while the flat edge formed by the spout 20, having undergone a rotation of about 90 ° is slightly inclined towards the inside of the body.

After release of the press tool 22, the third step, not detailed, is the installation in the annular impression 26, of a plastic material called a seal; this operation can advantageously be carried out with a roller, the joint material being at this stage in a fluid state.

The joint thus deposited is visible at 27 in FIG. 3, which shows the result of the following stage of the establishment of a bottom 28 with a fitting part 29 and a bottom edge 30 extending in direction radial over a predetermined distance beyond the spout 20 of the crimping edge 21 of the body 10. It can be seen that the cavity 26 for receiving the seal 27 extends over most of the body edge 21 upstream of the hook 19 on which bears on the bottom edge 30.

Next, the actual crimping operation is carried out, which is carried out in a conventional manner with the successive action of two rollers in a first phase, a rolling wheel 31 (FIG. 4) with progressive advance thereof. towards a mandrel 32. The bottom edge 30 is gradually wound around the hook 19 until the final phase of the rolling operation illustrated in FIG. 5; the end portion 30 'of the bottom edge 30 arrived after a rotation of about 270 ° along the wall of the body 10, while the beak 20 of the body edge was found in an additional rotation of more than 90 ° to the position before driving in Figure 3.

During this operation, the seal material is widely spread and compressed between the bottom edges 30 and the body edge, while the impression 26 may have undergone a certain straightening by deformation during rolling.

The development of the crimping according to the invention ends with the final phase illustrated in Figures 6 and 7 where the rolling wheel 31 has been taken up by a so-called clamping wheel 33 having a working surface 34 of substantially straight profile between two rounded corners 35, 36 for confining the crimp opposite the active part 37 of the mandrel 32.

Starting from the stage illustrated in FIG. 5 where the work of the rolling wheel 31 is finished, the intervention of the tightening wheel 33 can be analyzed in two phases.

In a first part of the stroke of the tightening wheel 33 towards the mandrel 32, there occurs (FIG. 6) a flattening of the whole of the seam during which the curved tracing of the bottom edge 30 straightens gradually in contact with the active surface 34 of the tightening wheel, causes the body edge 21 to be pushed back with a gradual reduction in its connection radius 21A on one side and progressive closure of the hook 19 until the spout 20 straightens against the end portion 30 ' from the bottom edge, which is on its side practically straightened and driven against the adjacent part of the body 10.

This setting phase of the setting can be considered complete when the working surface 34 of the wheel 33 has arrived with respect to the facing surface 37 of the mandrel 32 at a distance corresponding to the sum of the six metal thicknesses corresponding to the insertion of the spout 20 against, on the one hand, on the inside, the body 10 caught between the fitting part 29 and the adjacent internal part 30A of the bottom edge now folded and, on the other hand on the outside, the facing part 30B of said bottom edge covering the adjacent part of the body edge designated by the reference 26 ′ and corresponding to the zone previously marked by the depression 26.

The clamping phase thus completed is followed according to the invention by a terminal phase called rolling during which the stroke of the clamping wheel is continued (Figure 7) to a distance from the surface 37 of the mandrel roughly reduced to the sum of the five thicknesses of metal in the setting outside the spout 20.

Under these conditions the six layers of material located at the hook 19 undergo a rolling or forging work determining a plastic deformation of the assembly leading to a particularly effective anchoring or locking of the hook 19 in the surrounding layers in the manner of 'a harpoon, a strengthening of the assembly by a work hardening effect, an improvement in the seal by the effect of baffles impregnated in the structure obtained.

FIG. 8, a view similar to FIG. 7, shows a variant which differs from the previous one in that the hook 19 ′ results from a fold made beforehand on the area bordering the bottom edge 30 ′. Note the thinning mainly affecting in this case the two folds 20A and 20B of the body 10 '.

The preparation of the edge bordering the bottom can be carried out by forming on the edge bordering the bottom of a profiling similar to that which has been described above for the body edge with reference to FIG. 1. However, it is also possible, and it may be preferred, to practice on the edge bordering the bottom, before or after placement on the body (as above in FIG. 3), by prior rolling, a rounded hook profile.

Figures 9 to 12 show an exemplary embodiment of such preparation of the bottom edge and of the subsequent crimping operation.

According to FIG. 9, the zone bordering the edge 30 ′ of a bottom 28 ′ has a profile 41 in rounded hook following shaping by rolling which may have been carried out, either generally before or after setting place from the bottom in the body 10 'to the edge to be crimped simply folded 20'.

The assembly thus prepared is subjected to the successive action of two crimping wheels: a first rolling wheel 40, which Figures 9 to 11 show in three successive positions facing a mandrel 42, and a wheel 40 'of tightening which brings the crimping, according to FIG. 12, to the stage preceding the rolling operation according to the invention.

A final rolling phase can take place in accordance with the preceding description.

The invention is of course not limited to the details of the embodiments which have just been described by way of illustration. Thus, as regards for example the positioning of the seal, as a variant with respect to the description given above with reference to FIG. 3, the seal can be deposited or injected according to techniques known during the rolling operation of FIGS. 3 and 4 or also of FIGS. 9 and 10.

Claims (11)

1. Assembly process of two thin-walled parts, in particular of metal packaging bodies and bottoms by a crimping comprising, in a crimped area of height given in an axial direction, a plurality of layers alternately belonging to two bordering edges of the parts to be assembled, a fold made beforehand on one of the bordering edges increasing over a predetermined fraction of said height the number of layers of said plurality, characterized by a rolling operation of the structure thus formed until its thickness is equalized on said given height 2. Method according to claim 1, characterized in that the fold is made on the edge bordering the bottom. 3. Method according to claim 1 applied to the assembly of a barrel body with a bottom, the fold being operated on the edge bordering the body, characterized in that this fold is prepared by printing a profile of hook in the end part of the body edge. 4. Method according to claim 3, characterized in that the printing of a hook profile is effected by the use of a wheel and a mandrel of complementary profiles. 5. Method according to claim 3 or 4, characterized in that the hook profile comprises a root branch directed towards the inside and a terminal branch or beak directed towards the outside of the body. 6. Method according to any one of claims 3 to 5, characterized in that the body edge is folded to the press after forming the hook. 7. Method according to claim 6, characterized in that an outwardly concave annular impression is formed in the fallen edge of the body between the bottom of the hook profile and the radius of connection of said fallen edge to the undeformed part of the wall of the body. 8. Method according to claim 7, characterized by the installation of a seal in said cavity before the establishment of the bottom to be crimped. 9. Method according to any one of the preceding claims, characterized in that it comprises, after the setting of the bottom to be crimped, the successive intervention of a wheel (31) for rolling the bottom edge around the edge body and with the latter, then a rolling clamping wheel (33) having a profile working surface substantially parallel to that of a mandrel for supporting the assembly. 10. Crimped seal, in particular for packaging with bottoms assembled by crimping, of the type comprising on a crimped area of predetermined height a plurality of layers belonging alternately to the bordering edges of the bottom and of the body of the packaging with at least one hook resulting from '' a fold back of one of said edges and determining over a fraction of said predetermined height the increase of one unit in the number of layers of said plurality, characterized by a modification affecting the structure of the seam at least over said fraction of its height , so that the setting is confined between two substantially parallel boundary surfaces, resulting in a rolling and a reduction in thickness of the layers adjacent to the hook. 11. In a method of assembling by crimping a bottom in a metallic packaging body, an operation for preparing the bordering edge of the body characterized by the printing of a hook profile (19) in an end part of the body edge, followed by a falling edge operation leading to the formation of a crimping edge (20,21) provided with a hook (19) having an end portion (20) of substantially axial orientation radially outside an annular cavity (26).

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