Thin sheet punching device

Details Thin sheet punching device Thin sheet punching device

2002-02-14

2004-02-10

Shoap, Allan N. (Department: 3724)

Cutting

Tool engages work during dwell of intermittent workfeed

With work-moving clamp jaw

C083S219000, C083S435150, C083S687000, C083S691000

Reexamination Certificate

active

06688201

ABSTRACT:

TECHNICAL FIELD
The present invention relates to a thin sheet punching device for obtaining a plurality of small pieces of similar shape corresponding to the punching hole of a press punching die, by processing a thin sheet of raw material of relatively large size by means of punching tools of a punch press machine.
BACKGROUND ART
Conventionally, the metal outer jacket of a battery is fabricated by the steps illustrated in
FIGS. 20A-20F
. Firstly, as shown in
FIG. 20A
, a hoop material made from tinplate steel sheet and having a thickness of approximately 0.2 mm is cut to prescribed dimensions to obtain a square-shaped raw material sheet
1
having a relatively large size, for example, 785 mm×850 mm. Thereupon, as shown in
FIG. 20B
, slits parallel to the edges are formed in the side edge regions, each approximately 2 mm from two mutually opposing side edges of the raw material sheet
1
. These two side regions
2
are removed, whereupon slits are formed at prescribed intervals between the two end edges of the sheet, as illustrated by the double-dotted lines. Thereupon, as illustrated in
FIG. 20C
, the raw material sheet
1
is divided into a prescribed number of strip-shaped intermediate sheets
3
. These intermediate sheets
3
are then respectively punch processed using prescribed press punching tools, as shown in
FIG. 20D
, thereby yielding a plurality of jacket blank sheets
4
like that shown in FIG.
20
E.
The aforementioned jacket blank
4
is then bent into a cylindrical shape, as shown in
FIG. 20F
, the opposing side edges
4
a
,
4
b
thereof are butted against each other, and a base section
5
is formed by curl caulking the edge region of the lower side
4
c
towards the inside, thereby forming an outer jacket for a battery
7
approximately having a bottomed cylinder shape. The reason that the aforementioned raw material sheet
1
is divided into a plurality of intermediate sheets
3
by means of a slitter is because, in order to achieve mass production jacket blanks
4
having small cutaways
6
a
,
6
b
respectively at the four corners thereof, in such a manner that there is no variation in the shape of the aforementioned cutaways
6
a
,
6
b
, it is difficult to adopt any means other than punch pressing wherein a plurality of jacket blanks
4
are punched out simultaneously from an intermediate sheet
3
.
However, in the method for manufacturing the aforementioned outer jacket
7
for a battery, as
FIG. 20D
clearly demonstrates, a very large amount of raw material waste is left after the strip-shaped intermediate sheets
3
have been punch pressed, and hence material loss is high. Accordingly, the number of jacket blank sheets
4
obtained from a single intermediate sheet
3
is reduced, and therefore productivity is low. Production numbers for small-scale batteries have been extremely high in recent years, and therefore the material loss described above leads to enormous economic losses, and is also undesirable from the viewpoint of preserving resources.
In order to resolve problems such as the foregoing, the applicants of the present invention have proposed a method for manufacturing metal outer jackets for batteries by means of the processes described below (see International Laid-Open Patent No. WO99/12218).
FIGS. 21A-21F
illustrate the sequence of manufacturing steps. Firstly, a hoop material made from tinplate steel sheet of approximately 0.2 mm thickness is cut to prescribed dimensions, to obtain a square-shaped raw material sheet
1
similar to that illustrated in FIG.
20
A. Slits are then formed in this raw material sheet
1
running along the cutting lines indicated by the parallel double-dotted lines in the diagram, thereby dividing the raw material sheet
1
into two edge sections
8
of approximately 2 mm width from opposing ends of the sheet
1
, and a prescribed number of strip-shaped first intermediate sheets
9
cut in parallel with these edge sections
8
.
Thereupon, as shown in
FIG. 21C
, the two edge regions of each first intermediate sheet
9
in the longitudinal direction thereof are removed by forming further slits, and a plurality of rectangular second intermediate sheets
10
are obtained by forming slits along a plurality of parallel cutting lines running perpendicularly to the longitudinal direction of the first intermediate sheet
9
. The longitudinal dimension of these second intermediate sheets
10
is set approximately 1 mm longer than the length of two jacket blanks
11
, which are the objects to be fabricated, laid end to end. Moreover, as shown in
FIG. 21D
, the central portion of each of the aforementioned second intermediate sheets
10
in the longitudinal direction thereof is then cut perpendicularly to said longitudinal direction by a press cutting tool
12
having an approximately I-shaped cross-section, thereby dividing it into two jacket blank sheets
11
, as illustrated in FIG.
21
E. These jacket blanks
11
are formed with two cutaways
13
a
,
13
b
on the upper and lower ends of one side edge
11
a
only, these cutaways
13
a
,
13
b
having a width respectively twice the size of the two cutaways
6
a
,
6
b
formed at the four corners of the jacket blanks
4
in FIG.
20
E. The jacket blank
11
is then bent into a cylindrical shape, as shown in
FIG. 21F
, the two side edges
11
a
,
11
b
thereof being butted against each other, and the edge region of the lower side
11
c
thereof is then curl caulked towards the inside, thereby yielding an outer jacket for a battery approximately having a bottomed cylinder shape.
In the manufacturing method for an outer jacket
14
described above, instead of means for obtaining jacket blanks
4
by press punching a strip-shaped intermediate sheet
3
as illustrated in
FIGS. 20A-20F
, jacket blanks
11
are obtained by respectively press cutting second intermediate sheets
10
formed by dividing a strip-shaped first intermediate strip
9
into a plurality of sheets. Compared to the method for manufacturing the outer jacket
7
in
FIGS. 20A-20F
, the raw material remainder created after forming the jacket blanks
11
is significantly reduced to approximately ¼. Since the number of jacket blanks
11
that can be obtained from the same raw material sheet
1
increases in accordance with the decrease in raw material remainder, it is possible to obtain an excellent merit in that the material yield rate increases dramatically.
However, whilst the method for manufacturing an outer jacket
14
described above brings the aforementioned excellent merit, it stills leaves scope for further improvement. Specifically, the method for manufacturing an outer jacket
14
described above comprises a cutting step performed by a slitter device on a raw material sheet
1
, a cutting step performed by a slitter on respective first intermediate sheets
9
, and a press cutting step performed by a press tool
12
on respective second intermediate sheets
10
, and therefore, since the number of manufacturing steps is relatively large in this way, a problem exists in that further improvements in productivity cannot be achieved.
Furthermore, although the material waste created after forming the jacket blanks
11
is reduced significantly in comparison with the method for manufacturing an outer jacket
7
illustrated in
FIGS. 20A-20F
, it cannot be regarded as being sufficiently reduced. In other words, the press tool
12
for dividing the second intermediate sheets
10
into two jacket blanks
11
by press cutting comprises a slit-forming cutting section
12
a
for forming the cutting line portion, as illustrated in
FIG. 21D
, and approximately triangular cutaway-forming cutting sections
12
b
,
12
c
provided at either end portion of this slit-forming cutting section
12
a
, but in order that the second intermediate sheets
10
are press cut smoothly to obtain jacket blanks
11
of the correct shape, it is necessary to set the width of the slit-forming cutting section
12
a
to approximately 1 mm at the minimum. Moreover, it is also necessary to set the cutaway-forming cutt

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