FR2667845A1 - CONTAINER BODY AND CORRESPONDING CLOSED BOX WITH IMPROVED CRIMPING. - Google Patents

Abstract

The invention relates to a can body (20) whose side wall comprises, from the bottom to its upper end, a lower portion (5) then at least one shoulder (7) for supporting said body. (20) overhanging it, then an upper portion (8) extending the outside of said shoulder (7) and a crimping edge surrounding the opening (10) of said upper end, characterized in that said side wall comprises, on the right of each of said small radius portions, such a shoulder (7), and, at least in line with each said rectilinear or large radius portion of length greater than 20 mm, an oblique surface (18) inclined at less than 40 degrees relative to vertically (6) and connecting said lower portion (5) to said upper portion (8), so as to have a regular crimping with a cover (3) while retaining the possibilities of supporting said body (20). A subject of the invention is also the corresponding closed boxes. It applies to the manufacture of metal cans.

Description

i

  BODY OF CANS AND CORRESPONDING CLOSED BOX

IMPROVED CRIMPING

  The invention relates to the field of metal or plastic-based cans closed by crimping, and more precisely those which have a support shoulder serving for example for adjusting the stacking with casing of identical box bodies, or when the closed box is pressed on the periphery of a positioning orifice. In particular, there is known a body of a can of aluminum alloy of the rectangular type with rounded angles, that is to say of which the open upper end, by horizontal convention, has a contour which has four radiated portions separated by short sides and large rectilinear sides This box body has a side wall above its bottom which comprises, from this bottom to said upper end, a lower portion or skirt surmounted by a peripheral shoulder overhanging this skirt and used to adjust the stacking with nesting of successive box bodies so that there is no jamming during unstacking, then a vertical upper portion extending the outside of the shoulder, this upper portion ending at the end upper open and with a peripheral horizontal crimping edge surrounding the opening of this end For closing the box after filling of its body, there is placed on said open upper end a cover having an end edge to be crimped slightly projecting from the crimping edge of the body and slightly folded down to facilitate the establishment and crimping This cover has a central portion fitting into the opening of the body of

box.

  The crimping produces an overlap with contact of the crimping edges of the cover and the box, this overlapping is called "crimping overlap" and ensures sealing. It has been observed that with such bodies one often obtains "crimping overlaps" insufficient, and therefore risk of leakage, along the long rectilinear sides and more particularly towards the middle of these long sides, while the overlaps were satisfactory in law

radiated portions.

  The plaintiff sought to remove these defects and the corresponding risks of leakage.

STATEMENT OF THE INVENTION

  The subject of the invention is a typically metallic can body comprising a bottom, a side wall and a horizontal open upper end, the opening of said end having a contour which has at least two portions of small radius, said portions being separated by rectilinear or large radius portions, said side wall comprising, from the bottom to said upper end, a lower portion then at least one bearing shoulder of said body overhanging said lower portion, then an upper portion extending the exterior of said shoulder and a crimping edge surrounding said opening of said upper end, as is already known from the prior art presented in which the bearing shoulder is peripheral and unique According to the invention, said side wall comprises, at right of each of said portions of small radius, a support shoulder, and, at least at the right of each said rectilinear or large-radius portion of length greater than 20 mm, an oblique surface inclined at less than 400 relative to the vertical and connecting said lower portion to said upper portion, so as to ensure the regularity of its crimping with a cover while

  retaining possibilities of support of said body.

  The following interpretation is proposed for the solution given by the invention to the problem of insufficient crimping overlaps of the prior art: when there is a shoulder on the side wall of the body, a vertical component of the crimping force of the cover deforms the shoulder in the less stiff portions, that is to say in line with straight or large radius portions (typically more than 50 mm) typically having more than 20 mm in individual length This deformation of the shoulder causes a shortening of the portion of the crimping edge of the body which is applied against the end edge of the

  cover by crimping operation.

  such a defect does not appear plumb with the portions of small radius, typically between 10 and 25 mm, probably because of the stiffening of the wall associated with this radius; the replacement of the shoulder, in line with said straight or large radius portions, by an oblique surface or wall has the effect of avoiding or greatly limiting a deformation such as that associated with the shoulder and therefore avoiding the shortening of the crimping edge

of the box body.

  The effect obtained is surprising According to the following comparative tests: with a body of the prior art, the crimping overlap is 1, 2 mm in the spokes and only 0.6 to 0.7 mm near the middle of the straight portions; with a body according to the invention, the overlap is 1.2 mm in the

  radii and 1.1 to 1.2 mm in the straight portions.

  Each oblique surface is inclined less than 400 relative to the

  vertical, so as to minimize the risk of deformation during crimping.

  Given the offset between upper and lower portions, the angle

  of optimal inclination varies in practice between 10 and 300.

  Each said oblique surface preferably extends to the right of the ends of the portions of small radius framing the rectilinear or large radius portion dominating said oblique surface or even less than 10 mm from each of said ends, which means that '' it then stops either at the beginning of the rounded portions which surround it or a

shortly before.

  When the cover has a central part which fits into the upper portion of the body for closing, the height of fitting is known in advance and it is ensured that each oblique surface joins this upper portion at the bottom or end. lower of this casing or less than 1 mm lower so as to minimize the possibilities of deformation during crimping, these being influenced by the inclination of the oblique surface and by the height of the upper wall

  not held by the fitting of the cover.

  When it is a box body and more precisely a lower portion of this body nestable in an identical body, the overhanging shoulders situated in line with the portions of small radius in the case of the invention are sufficient to limit and adjust this nesting of

  so as to avoid unstacking difficulties.

  The invention also relates to a closed metal can, obtainable from the previous can body, said can comprising such a body and a cover crimped on an upper portion of said body, said upper portion having a crimped horizontal outline having at at least two portions of small radius, said portions being separated by rectilinear or large radius portions and dominant

  at least one shoulder which overhangs a lower portion of said body.

  According to the invention, this box body has such a shoulder to the right of each of said portions of small radius and, or less to the right of each said straight portion or of large radius of length greater than 20 mm, an oblique surface inclined at least of 400 with respect to the vertical and connecting said lower portion to said upper portion, and probes crimped contour has a crimping overlap

constant at better than 0.2 mm.

  Each said oblique surface is preferably inclined from 10 to 30 relative to the vertical When the cover of the box is fitted into said upper portion of the body, each said oblique surface joins this upper portion at the lower end of the

  nested portion of said cover or less than 1 mm lower.

  The box body and the cover are typically made of aluminum or alloy or tinplate and between 0.15 and 0.30 mm thick, and even more typically between 0.17 and 0.26 mm. The metallic designation s The invention also applies to rigid plastic bodies having a bearing shoulder and a crimped metal cover. closed is also typically a box of the rectangular type with rounded angles, the large rectilinear portions of its outline having

  to 100 mm long It can also be for example an oblong box.

ADVANTAGES OF THE INVENTION

  It thus makes it possible to obtain crimped cans whose crimping overlap is very regular and therefore has no

risk of leaks.

  The manufacturing modification corresponding to the invention is

particularly simple.

TESTS

  Figure 1 shows the side walls of two bodies of boxes outside

  invention in stacked position, in an axial half-section.

  FIG. 2 represents a box outside the invention in the position of

crimping.

  Figures 3 and 4 show the profile of this box after the first crimping pass, respectively in the middle of a long side and in a

radiated part.

  FIG. 5 represents the side walls of two bodies of boxes according to the invention in the middle of a large side, the side walls of a neighboring radiated part being shown in broken lines, in two

axial half-sections.

  Figure 6 shows a tin can according to the invention, in half-elevation. Figure 1 shows the profile of the side wall 1 of two identical box bodies 2, the fitting of these two bodies 2 and the adaptation of a cover 3 on one of these bodies 2 before crimping Each body 2 comprises, at above its bottom 4, a skirt or lower portion 5 here slightly inclined towards the vertical direction or direction of the axis 6 of the box body 2, then a shoulder 7 overhanging the skirt 5, then an upper portion 8 here vertical, then an outer rim or crimping edge 9 surrounding the opening 10 located at the upper end of the portion 8 As can be seen, the shoulders 7 serve to limit and adjust the nesting of the box bodies, so that their unstacking sure

machine be easy.

  The cover 3 comprises a central portion II which fits into the upper portion 8 to a depth H 1 = 3 mm and a crimping edge 12 having an end portion 13 folded down slightly beyond the edge 9 to serve Here, the width or overflow of the shoulder 7 is 1 mm, this shoulder 7 is at H = 6 mm below the upper end of the portion 8 and its opening 10 and therefore at H 2 = 3 mm below the bottom 14 of the cover 3 in the nested position The bodies 2 and the cover 3 are made of aluminum alloy AISI 5052, that is to say about 2.5% Mg + 0.25% Cr, d 'thickness

0.25 mm and in the semi-hard state.

  Figure 2 shows a rectangular body 2 with rounded angles and a cover 3 in position for crimping, the first pass being made with two rotating rollers 15 rotating around the body 2 and the cover 3 approaching the axis 6 of the body 2 This first pass produces a pinching and tilting of the crimping edges 9 and 12 + 13 The result after tightening pass differs in the middle of a large side and in the radiated parts: the differences in "crimping overlap" are already present before tightening and they are shown diagrammatically in FIGS. 3 (less than 10 mm from the middle of a large side) and 4 (in a radiated part) The overlap of the crimping therein is respectively R 1 = 0.6 to 0.7 mm and R 2 = 1.2 mm Body 2 has an opening 10 of

  104 x 59.8 mm with radiated corner parts of radius 20 mm.

  The interpretation of the poor result R 1 is that the shoulder 7 is pushed down and deforms under the effect of a vertical component of the support of the upper surface 16 of the groove 17 of the roller (s) 15, as shown in FIG. 3, the portion of the edge 9 available for clamping against the edges 12 and 13 of the cover being thereby shortened. The bending of the radiated parts makes them more difficult to deform, it is observed in particular that the shoulder 7 retains its initial shape there (FIG. 4), the satisfactory covering R 2

thus being maintained.

  FIG. 5 shows the side walls of two box bodies 20 according to the invention, identical to bodies 2 with the exception of the following changes: in the rectilinear portions 25 60 mm long (FIG. 6), and exceeding them by 3 mm each of their ends or connections 230 with the adjacent portions of small radius 23 (radius of 20 mm), an oblique wall portion 18 has been made This portion 18 (FIGS. 5 and 6) is inclined to the vertical 6 at an angle 19 of 200, its lower end 180 is located at the lower connection 21 of the shoulders 7 with the skirt or lower portion 5, and its end

  upper 22 at the bottom 14 of the fitted portion of the cover 3.

  Each flat portion 18 thus has a height H 3 = 4 mm, a width of 1 mm in horizontal projection, and is at a distance H, = 3 mm from

  the upper end 10 of the box body 20.

  And on each short side of the box bodies 20, there is a similar oblique wall 18 mm long between the radiated parts such as 23 des

angles of the box body.

  These oblique walls of limited length can be removed without notable inconvenience, and replaced by a continuous shoulder, the risk

  of prejudicial deformation being of little importance there.

  The shoulder 7 is kept in the radiated parts, the 4 small

  shoulders 7 sufficient to adjust the nesting of the box bodies 20.

  The crimping was carried out as described, it gave for the box

  closed 200 (fig 6) a crimped bead 24 of constant height 2.8 mm.

  Destructive examinations of two boots 200 showed that the crimp overlaps were equal to R 2 = 1.2 mm in the radiated parts 23 and on the short sides And that the crimp overlaps on the long sides were "R 2" or very similar: they vary

from 1.1 to 1.2 mm.

Claims (10)

  1 can body (20) comprising a bottom, a side wall and a horizontal open upper end (9), the opening (10) of said end (9) having a contour which has at least two portions of small radius (23), said portions (23) being separated by rectilinear or large radius portions (25), said side wall comprising, from the bottom to said upper end (9), a lower portion (5) then at least a shoulder (7) for supporting said body overhanging said lower portion (5), then an upper portion (8) extending the end of said shoulder (7) and a crimping edge (9) 1 LO surrounding said opening (10) of said upper end, characterized in that said side wall comprises, to the right of each of said portions of small radius (23), such a shoulder (7), and, at least to the right of each said portion of rectilinear or large radius ( 25) length su greater than 20 mm, an oblique surface (18) inclined less than 400 relative to the vertical (6) and connecting said lower portion (5) to said upper portion (8), so as to ensure the regularity of its crimping (R 2) with a cover   (3) while retaining support possibilities (7) of said body (20).   2 box body (20) according to claim 1, wherein each said oblique surface (18) is inclined from 10 to 300 relative to the vertical (6).   3 can body (20) according to any one of claims 1 or 2,   wherein each said oblique surface (18) extends to the right of the ends (230) of the portions of small radius (23) framing the rectilinear or large radius portion (25) dominating said oblique surface (18) or '' less than 10 mm from each of the said ends (230).   4 can body (20) according to any one of claims 1 or 2,   wherein each said oblique surface (18) joins said upper portion (8) at the lower end (14) of the casing   of said cover (3) or less than 1 mm lower.   Box body (20) according to claim 1, wherein said lower portion (5) is nestable in an identical box body, said overhanging shoulders (7) limiting and regulating this interlocking.   6 can body (20) according to any one of claims 1 to 5,   aluminum or alloy or tinplate and between 0.15 and 0.30 mm.   7 Closed tin can (200), obtainable from the body of the tin   (20) of any one of claims 1 to 6, said box   comprising such a body (20) and a cover (3) crimped on an upper portion (8) of said body, said upper portion having a crimped horizontal contour (24) having at least two portions of small radius (23), said portions ( 23) being separated by rectilinear or large radius portions (25) and dominating at least one shoulder (7) which overhangs a lower portion (5) of said body (20), characterized in that said box body (20) has such a shoulder (7) in line with each of said portions of small radius (23) and, at least in line with each said straight portion or of large radius (25) of length greater than 20 mm, an oblique surface (18) inclined less than 400 from the vertical (6) and connecting said lower portion (5) to said upper portion (8), and in that said crimped contour (24) has a crimping overlap (R 2) constant better than 0.2 mm.   8 can (200) according to claim 7, each said oblique surface (18) is inclined from 10 to 300 relative to the vertical (6).   9 Can (200) according to any one of claims 7   or 8, said cover (3) being fitted into said upper portion (8) of said body (20) and each said oblique surface (18) joining said upper portion (8) at the lower end (14) of the portion fitted with said cover (3) or less 1 mm lower.   Can (200) according to any one of claims 7   to 9, of the rectangular type with rounded angles, the large rectilinear portions (25) of its outline having 30 to 100 mm in length, its body (20) being of aluminum or alloy or of tin and thick between 0.15 and 0.30 mm.   11 Can of preserves according to any one of claims 7 to 9,   with a rigid plastic body and a cover set is metallic.