U.S. patent application number 11/839299 was filed with the patent office on 2008-02-28 for method for manufacturing a metal container.
This patent application is currently assigned to Corus Staal BV. Invention is credited to Henri KWAKKEL, Hendrik Michel.
Application Number | 20080050206 11/839299 |
Document ID | / |
Family ID | 37654934 |
Filed Date | 2008-02-28 |
United States Patent
Application |
20080050206 |
Kind Code |
A1 |
KWAKKEL; Henri ; et
al. |
February 28, 2008 |
METHOD FOR MANUFACTURING A METAL CONTAINER
Abstract
Method for manufacturing a metal container including a metal
body part, a metal bottom part and optionally a top part. The
method includes steps of: providing a metal body part with a closed
circumferential wall; providing a metal bottom part with a flanged
edge, the outside of the flanged edge corresponding to the inner
side of the body part at the location where the bottom part is to
be connected to the body part; placing the bottom part within the
body part at the location; and folding the outer end of the body
part that extends beyond the flanged edge of the bottom part inward
against the inside of the flanged edge of the bottom part.
Furthermore, sealer is provided to ensure a liquid- and airtight
seal between body part and bottom part, which sealer is included in
a coating applied on the bottom part and typically activated by
heating.
Inventors: |
KWAKKEL; Henri; (Beverwijk,
NL) ; Michel; Hendrik; (Bergen, NL) |
Correspondence
Address: |
STEVENS DAVIS MILLER & MOSHER, LLP
1615 L STREET, NW
SUITE 850
WASHINGTON
DC
20036
US
|
Assignee: |
Corus Staal BV
Ijmuiden
NL
|
Family ID: |
37654934 |
Appl. No.: |
11/839299 |
Filed: |
August 15, 2007 |
Current U.S.
Class: |
413/1 |
Current CPC
Class: |
B21D 51/30 20130101;
B65D 7/36 20130101; B21D 51/2653 20130101 |
Class at
Publication: |
413/001 |
International
Class: |
B21D 51/26 20060101
B21D051/26 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 17, 2006 |
EP |
06017135.2 |
Claims
1. A method for manufacturing a metal container, the metal
container comprising a metal body part with a closed
circumferential wall, a metal bottom part and optionally a top
part, wherein the method at least comprises the following steps:
providing a metal body part with a closed circumferential wall,
providing a metal bottom part with a flanged edge, the outside of
the flanged edge corresponding to the inner side of the body part
at the location where the bottom part is to be connected to the
body part, placing the bottom part within the body part at said
location, and - folding the outer end of the body part that extends
beyond the flanged edge of the bottom part inward against the
inside of the flanged edge of the bottom part.
2. The method according to claim 1, wherein the outer end of the
body part that extends beyond the flanged edge of the bottom part
is folded such that the largest part of the inner side of said
outer end of the body part butts against the inner surface of the
flanged edge of the bottom part.
3. The method according to claim 1, wherein the outer end of the
body part that extends beyond the flanged edge of the bottom part
is folded inward such that the edge between outer and inner side of
said outer end of the body part butts against the inner side of the
flanged edge of the bottom part.
4. The method according to claim 1, wherein at least the outer side
of the flanged edge of the bottom part is provided with sealing
means.
5. The method according to claim 1, wherein the bottom part is made
out of a sheet provided at least at one side with a coating, the
coating consisting of or comprising sealing means or provided with
a coating that is suitable to be used as sealing means.
6. The method according to claim 5, wherein the bottom part is made
out of a steel sheet with at least at one side a coating comprising
polyethylene terephthalate, polypropylene or a mixture of
polypropylene and nylon.
7. The method according to claim 4, wherein the sealing means are
activated by means of a heating treatment.
8. The method according to claim 7, wherein the heating treatment
consist of induction heating.
9. The method according to claim 1, wherein the bottom part is
formed into a dome shape, the dome pointing in a direction opposite
to the direction in which the flanged edge of the bottom part
points.
10. The method according to claim 1, wherein the container is
provided with a top part such as a top part provided with a valve
as used for aerosols.
11. The method according to claim 1, wherein the body part of the
container is provided with a top opening suitable to receive a
valve cap.
12. The method according to claim 5, wherein the sealing means are
activated by means of a heating treatment.
13. The method according to claim 6, wherein the sealing means are
activated by means of a heating treatment.
14. A metal container manufactured according to claim 1 and
provided with a top part, wherein the container is manufactured to
hold a pressurized medium.
15. The metal container according to claim 14, wherein the top part
consists of a valve cap.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This claims priority from European patent application number
06017135.2 filed 17 Aug. 2006 incorporated herein by reference in
its entirety.
FIELD OF THE INVENTION
[0002] The invention relates to a method for manufacturing a metal
container, the metal container comprising a metal body part with a
closed circumferential wall, a metal bottom part and optionally a
top part.
BACKGROUND OF THE INVENTION
[0003] Such metal containers are known in different embodiments,
that is with an open top, with a closed bottom and top, such as for
example cans for the food industry, or closed at both ends with the
top part provided with or consisting of a valve cap, such as a
container for a pressurized medium, an aerosol.
[0004] The usual method to connect a separate bottom part or top
part to a body part is by forming the edges of bottom part and body
part or top part and body part into a double seam. The double seam
method sets a number of demands to the properties, such as
thickness and hardness, of the metal to be used with this method.
For instance, seaming with one or both of the container parts being
made out of very thin sheet metal of considerable hardness will be
difficult or even impossible. Therefore, the material used for the
double seam method will in most cases be a standard tin or chromium
plated steel with properties which are most favourable for the
method. These sheets may further be provided with a coating that
serves as a barrier between the container and the content of the
container and if also applied on the outside between the container
and the environment.
[0005] Furthermore, prior to the seaming operation a sealing
compound is applied to the bottom part and top part, if present, to
ensure that the double seam will form a good closure of the
container. The use of such a sealing compound brings extra costs,
not only for the sealing compound itself, which are relatively
costly, but also for the application thereof on the bottom part and
top part, if present, which asks for an extra handling step.
SUMMARY OF THE INVENTION
[0006] It is an object of the invention to provide a method to
manufacture a metal container in which in a simple and economic
manner a bottom part and a top part, if present, are connected to a
body part of a metal container.
[0007] It is another object of the invention to provide a method to
manufacture a metal container which enables the use of different
sheet metals for the bottom part and/or top part than the sheet
metal used for the body part.
[0008] It is another object of the invention to provide a method to
manufacture a metal container wherein a coating on bottom part or
top part is used as sealing means.
[0009] It is still another object of the invention to provide a
metal container manufactured according to the method and capable of
holding a pressurized medium.
[0010] According to a first aspect of the invention one or more of
the objects are achieved by means of a method comprising at least
the following steps: [0011] providing a metal body part with a
closed circumferential wall, [0012] providing a metal bottom part
with a flanged edge, the outside of the flanged edge corresponding
to the inner side of the body part at the location where the bottom
part is to be connected to the body part, [0013] placing the bottom
part within the body part at said location, and [0014] folding the
outer end of the body part that extends beyond the flanged edge of
the bottom part inward against the inside of the flanged edge of
the bottom part.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] FIG. 1 shows schematically part of a cross-section of an
embodiment of a container with the outer end of the body part
folded flat against the flanged edge of the bottom part,
[0016] FIG. 2 shows schematically part of a cross-section of an
embodiment with the outer end of the body part curled against the
inner side of the flanged edge of the bottom part, and
[0017] FIG. 3 shows in cross-section as well as in perspective a
part of an embodiment of a container with the outer end of the body
part folded flat against the flanged edge of the bottom part.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0018] As mentioned above, according to a first aspect of the
invention one or more of the objects are achieved by means of a
method comprising at least the following steps: [0019] providing a
metal body part with a closed circumferential wall, [0020]
providing a metal bottom part with a flanged edge, the outside of
the flanged edge corresponding to the inner side of the body part
at the location where the bottom part is to be connected to the
body part, [0021] placing the bottom part within the body part at
said location, and [0022] folding the outer end of the body part
that extends beyond the flanged edge of the bottom part inward
against the inside of the flanged edge of the bottom part.
[0023] With this method the bottom part is bent to a final shape
with a flanged edge in only one step, which is done prior to
inserting the bottom part into the body part at the final position.
Thereafter, the body part is folded in a simple operation without
having to bend the bottom part at the same time as is done in the
double seam method. With these simple bending and folding
operations it is possible to use other sheet metals than is
necessary with the double seam method, without the risk of flange
cracks. Furthermore, it is possible to use different sheet metals
for body and bottom and/or top part. For instance, a thinner sheet
metal of greater hardness may be used for the bottom part.
[0024] By folding the outer end of the body part against the inside
of the flanged edge the bottom part is clamped securely against the
body part. However, in order to also have a liquid and air tight
connection between bottom part and body part it is further provided
that at least the outer side of the flanged edge of the bottom part
is provided with sealing means. According to the invention the
bottom part is made out of a sheet metal provided at least at one
side with a coating, the coating consisting of or comprising
sealing means or provided with a coating that is suitable to be
used as sealing means. Very good experimental results have been
achieved by using a steel sheet that is commercially available from
CORUS under the trademark "Protact". This steel sheet is provided
at one or at both sides with a single or multi-layered polymer
coating preferably comprising polyethylene terephthalate,
polypropylene or a mixture of polypropylene and nylon. A coating
from other material than that of said polymer coatings can also be
used, such as for instance a lacquer, however, such coatings do not
have the advantages of thickness and flexibility of said polymer
coatings.
[0025] In order to form a liquid and air tight connection a heating
treatment is required to have the coating act as a sealing means.
There are a number of possibilities to perform such a heating
treatment, but preferably this is done by induction heating because
this is an easy and fast manner to do so.
[0026] By using such a sheet metal with a coating suitable to be
used as a sealing means, it is no longer necessary to use said
special sealing compound. This not only means saving out the costs
for such a relatively expensive compound but also the steps of
applying the sealing compound and the following curing of the
compound before the bottom part can be applied to the body
part.
[0027] With the method according to the invention the outer end of
the body part that extends beyond the flanged edge of the bottom
part may be folded such that the largest part of the inner side of
said outer end of the body part butts against the inner surface of
the flanged edge of the bottom part. With a bottom part that is
provided at only the side that is facing the inside of the
container and the inside wall of the body part a very good seal can
be formed by induction heating as described. By providing a coating
at both sides the seal is further improved, but this is not really
necessary, if the length of the flanged edge of the bottom part is
long enough.
[0028] However, a bottom part provided on both sides with a coating
suitable to be used as sealing means gives the possibility for
another advantageous way to fold the outer end of the body part.
Accordingly, the outer end of the body part that extends beyond the
flanged edge of the bottom part is curled inward such that the edge
between outer and inner side of said outer end of the body part
butt against the inner side of the flanged edge of the bottom part.
Herewith, the edge of the body part, along which the sheet is cut
and for that reason is not provided with a protective layer of for
instance tin, chromium and/or organic coating, butts against the
coating of the bottom part. With the heating treatment to form a
seal between the bottom part and body part, also a seal between the
inside of the flanged edge of the bottom plate and said edge of the
body part is formed, protecting the edge and therewith preventing
it from corrosion.
[0029] The method according to the invention can be applied to
manufacture a container that is open at the top and in principle
also to manufacture a container closed at both sides with the same
bottom and top part, although the last embodiment will be a bit
more complicated to manufacture. However, the method seems best to
be used to manufacture a container with different bottom and top
parts, such as for example a container with a bottom part as
described and a top part consisting of a top part provided with a
valve cap or only a valve cap, as used for aerosols.
[0030] If the method is used to manufacture aerosols, the bottom
part is preferably formed into a dome shape, the dome pointing in a
direction opposite to the direction in which the flanged edge of
the bottom part points. With such a shape the transition from dome
into the flanged edge can also be formed more easily than from a
for instance flat bottom.
[0031] Furthermore, if the container is manufactured to be used as
an aerosol the method provides in either a top part with a valve
cap or that the body part of the container is provided with a top
opening suitable to directly receive a valve cap. The latter will
mean in most cases that the top opening has to be made smaller than
the bottom opening.
[0032] The invention will be further described on hand of the
examples given in the drawing, wherein:
[0033] FIG. 1 shows schematically part of a cross-section of an
embodiment of a container with the outer end of the body part
folded flat against the flanged edge of the bottom part,
[0034] FIG. 2 shows schematically part of a cross-section of an
embodiment with the outer end of the body part curled against the
inner side of the flanged edge of the bottom part, and
[0035] FIG. 3 shows in cross-section as well as in perspective a
part of an embodiment of a container with the outer end of the body
part folded flat against the flanged edge of the bottom part.
[0036] The embodiment of the container 1 as shown in FIG. 1 and
also in FIG. 3 comprises a body part 2 and a bottom part 3. The
body part 2 has a closed circumferential wall 6. In the most simple
shape such a wall 6 is of circular cross-section and with a
constant diameter along the length of the body. However, other
shapes, such as tapered shapes and/or shapes of non-circular
cross-section are also possible. The bottom part 3 is formed with a
dome shape 4 pointing in upward direction and is further provided
with a flanged edge 5. The outer size and shape of flanged edge 5
of bottom part 3 corresponds to the size and shape of body part 2
at the inside at the location where the bottom part 3 is to be
connected to the body part 2.
[0037] After placing the bottom part 3 at the right location in the
body part 2, that is at a certain distance above the lower edge of
body part 2, the outer end 7 of body part 2 that extends below the
flanged edge 5 of bottom part 3 is folded such that the largest
part of the inner side of said outer end 7 of body part 2 butts
against the inner side of the flanged edge 5 of bottom part 3. By
folding the outer end 7 in this way bottom part 3 is clamped
securely against body part 2.
[0038] The bottom part 3 is provided at one or both sides with a
coating that comprises a sealing means or that may be used as a
sealing means. The bottom part that was experimented with is made
from a steel sheet commercially available under the trade name
"PROTACT", which is provided at one or both sides with a coating of
polyethylene terephthalate, polypropylene or a mixture of
polypropylene and nylon. To activate the sealing means a heating
treatment is necessary, which heating treatment is preferably an
induction heating treatment. After this heating treatment the
sealing means not only provide a liquid tight and air tight seal
but it also improves the mechanical connection between the bottom
and body parts 2, 3.
[0039] In the embodiment shown in FIG. 2 the outer end of the body
part 2 is curled inward in such a way that the edge 8 of body part
2 butts against the inner side of the flanged edge 5 of bottom part
3 and therewith against the coating comprising a sealing means.
After induction heating the edge 8 will be securely embedded in the
sealing means therewith preventing any corrosion of edge 8 of body
part 2.
[0040] With this embodiment sealing of the container 1 is mainly
achieved by the sealing means acting on the outer side of the
flanged edge 5 of bottom part 3 and the inner side of the
circumferential wall 6 of body part 2, which however is sufficient.
For this embodiment it is essential that bottom part 3 is provided
on both sides with the coating containing sealing means.
* * * * *