FR2548565A1 - METHOD FOR REINFORCING CRIMP AND CRIMPED JOINTS, ESPECIALLY FOR PACKAGING - Google Patents

Abstract

THE BOTTOM 28 OF A METAL WASTE BEING ASSEMBLED TO BODY 10 THEREOF BY A DOUBLE CRIMPING IN WHICH A OVERCURRENT IS CREATED BY A BEND 20 OF THE EDGE OF THE BODY, IT IS PROVIDED FOLLOWING THE INVENTION A LAMINATION OPERATION DURING WHICH THE THICKNESS OF THE SERTI IS PRACTICALLY EQUALIZED OVER THE WHOLE HEIGHT BETWEEN A CHUCK 32 AND A ROLLING ROLLER 33 WITH SUBSTANTIALLY PARALLEL WORKING SURFACES.

Description

The present invention relates to crimped joints, in particular for

  bottom packings assembled to the body by crimping, in particular Metallic or similar drums, seals of the kind where the bordering edges of the body and the bottom constitute generally alternating layers of an interlaced structure extending over a certain height in an axial direction We know the so-called simple, double and triple crimps comprising respectively three, five and seven layers capable of coming alternately from the edges bordering the two parts 10 to be assembled, the double and the triple crimping corresponding to the techniques practiced most commonly in terms of

metal or composite drums.

  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 joints.

  There has thus been described from 1919 (see patent GB 142 967) a process tending to reinforce a crimped joint, according to which, in the assembly by crimping of a metal drum bottom, the edge of the bottom was folded back on itself so as to put it in excess thickness, then the crimping was carried out so that the parts of the bottom and of the barrel body were arranged opposite

  of the extra thickness are repelled by determining an inflection of the structure of the seam 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 edge of the body of a metal or similar barrel.

  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 assembled parts. 35 For example, keeping the profile 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

  ches located on the inner side relative to the original fold

of the extra thickness.

  A seam 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 resistance of joints of the type considered, the present invention proposes a technique capable of increasing to a greater extent.

  surprisingly the effectiveness 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 up to

  equalization of its thickness 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 The tightness is itself greatly improved due to the multiplicity of baffles

created at interfaces.

  The increase in efficiency of the reinforcement thus obtained can in fact 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 the aforementioned state of the art alone was affected substantially half of the interfaces. The improvement is attributable, on the other hand, to the fact that the elastic limit can be greatly exceeded throughout the entire excess thickness area affected by rolling, whereas in the prior art the elasticity of the layers affected by the deformation could remain practically intact, leaving a tendency to straighten the folds. Following the rolling according to the invention, this tendency to straighten 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 more apparent from the following description of an application by way of example to assembly by double crimping

  of a bottom and of the body of a metal barrel in the shape of a circular cylin10 dre, with reference to the appended drawings in which: FIGS. 1 to 7 are partial schematic sectional representations of successive phases of the process according to the invention, namely : in Figure 1, a preparatory phase of the edge of the body; 15 in Figure 2, forming the crimped edge of the body; in Figure 3, bottom fitting 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 7.1 'final operation of tightening the seam; FIG. 8, a view similar to FIG. 7, shows a variant with the bottom edge folded back; Figures 9 to 12 show successive phases of a

  method of developing the variant of FIG. 8.

  Depending on 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 of a mandrel 13 having a groove 14 facing a knurled wheel 15 of suitable profile is introduced into the adjacent end portion 30 at the end 11, by attacking the external face 16 of the wall. of the body, to push back this wall towards the bottom of the groove 14 The result of this preparatory operation of the part terminina35 the of the body is the formation in the profile of the latter of a ring with a hook profile 19 generally embracing the profile of the groove 14 of the mandrel and ending with a flat edge or beak having an inclination relative to the axis of the body

between O and 45.

  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 seal 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 knobs in a first phase, a rolling wheel 31 (FIG. 4) with progressive advance of the latter towards a mandrel 32 Le. bottom edge 30 is wound progressively 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 has arrived after a rotation of about 270 along the wall of the body 10, while the beak 20 of the body edge has been driven in an additional rotation 35 of more than 90 relative to the position before rolling of the

figure 3.

  During this joint material operation is widely spread and compressed between the bottom edges 30 and the body edge, while the imprint 26 may have undergone a certain straightening by deformation during rolling. crimping according to the invention ends

  by the final phase illustrated in FIGS. 6 and 7 o the rolling wheel 31 has been taken up by means of a so-called tightening wheel 33 having a working surface 34 with a substantially straight profile between two rounded corners 35, 36 for confining the crimp in look of the active part 37 of the mandrel 32.

  Starting from the stage illustrated in Figure 5 o the work of the rolling wheel 31 is finished, the intervention of the

  clamping 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 span 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 progressive reduction of its connection radius 21 A on one side and progressive closing of the hook 19 until the spout 20 straightens against the

  terminal part 30 ′ of 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 thick metal cores 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 30 A of the bottom edge now folded and, on the other hand, on the outside, the facing part 30 B of said bottom edge covering 30 the adjacent part of the body edge designated by the reference 26 'and corresponding to the area previously marked by the

depression 26.

  The clamping phase thus completed is followed according to the invention by a terminal phase known as rolling during which the stroke of the clamping wheel is continued (FIG. 7) up 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 of the spout 20.

  Under these conditions the six layers of material are found

  before 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 reinforcement of the together by a work hardening effect, an improvement in sealing 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 previously carried out on the zone bordering the bottom edge 30 ′. The thinning affecting will be noted mainly in this case the two folds 20 A and 20 B

of the body 10 '.

  The preparation of the edge bordering the bottom can take place 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 installation on the body 20 (as above in FIG. 3), by prior rolling, a rounded hook profile.

  Figures 9 to 12 show an embodiment of such preparation of the bottom edge and the operation

subsequent crimping.

  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 of the bottom in the body 10 '

  at the edge to be crimped simply folded down 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 35 preceding the rolling operation according to the invention.

  A terminal 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

  Illustrative Thus, as regards for example the installation 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 con5 techniques naked during the rolling operation of FIGS. 3 and 4 or also of FIGS. 9 and 10.

Claims (8)

  1 Method of assembling two thin-walled parts, in particular of metal packaging bodies and bottoms by 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 previously carried out on one of the bordering edges increasing over a predetermined fraction of said height the number of layers of said plurality, charac10 terized by a rolling operation of the structure thus   formed until its thickness is equalized over said given height.   2 Method according to claim 1, characterized in that   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 hook profile in   the terminal part of the body edge.   4 Method according to claim 3, characterized in that the printing of a hook profile takes place by setting   work of a wheel and a mandrel of complementary profiles.   Method according to claim 3 or 4, characterized in that the hook profile comprises a root branch directed inwards and a terminal branch or directing beak outward from the body.   6 Method according to any one of claims 3 to   , characterized in that the body edge is folded down with 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 profile of the   hook 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 realistically at the setting in place of the bottom to be crimped.   9 Method according to any one of the pre- claims   cédentes, characterized in that it comprises, after setting   place of the bottom to be crimped, the successive intervention of a knurling wheel (31) for rolling the bottom edge around and with the body edge, then of a nolette (33) for clamping rolling presenting a surface of profile work substantially parallel to that of a mandrel for supporting the assembly.   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 10 alternately belonging to the edges bordering the bottom e L of the body of the packaging with at least one hook resulting from '' a fold 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 on said fraction of its height so that the setting is confined   between two substantially parallel boundary surfaces, causing 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 metal packaging body, an operation for preparing the bordering edge of the body characterized by the printing of a hook profile (19) in an end portion of the edge body, followed by an edge falling 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).