Metal working – Method of mechanical manufacture – Electrical device making
Reexamination Certificate
2001-07-03
2004-02-17
Ryan, Patrick (Department: 1745)
Metal working
Method of mechanical manufacture
Electrical device making
C029S623300, C029S729000, C029S730000, C029S743000, C029S007000
Reexamination Certificate
active
06692542
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an apparatus for manufacturing spiral electrode groups for example for a lithium battery, having a construction in which a positive electrode plate and a negative electrode plate are superimposed with a separator therebetween and wound in spiral fashion.
BACKGROUND ART
Cylindrical lithium primary batteries or various types of rechargeable batteries of small size and high capacity have long been used as the drive power sources of portable electrical equipment. As improvements in performance and function have been achieved in portable electrical equipment, such batteries are being required to have higher voltage and higher capacity; in order to satisfy such demands, batteries adopting a spiral electrode construction are now widely used, in which a positive electrode plate and a negative electrode plate are superimposed with a separator interposed between these, and wound in spiral form. With such spiral electrode groups for cylindrical batteries of various types, there are important problems to be solved in order to improve productivity and ensure high performance and uniformity of quality. Firstly, the electrode plates must be precisely aligned with each other when wound together in spiral form. Secondly, any excessive tensile force must not be applied to the electrode plates and the separator during the winding of these, or they may be expanded or deformed. On the other hand, the electrode plates and the separator must be wound tightly without any slack portion.
The present inventors have previously proposed an apparatus for manufacturing spiral electrode groups having improved performance and uniformity of quality as described above (see Laid-open Japanese Patent Application No. H9-147878). This apparatus for manufacturing spiral electrode groups will be described with reference to
FIG. 10
to FIG.
12
.
FIG. 10
is a perspective view showing the main structural elements used for manufacturing a spiral electrode group for lithium batteries in the above apparatus. First of all, the concept of forming a strip-shaped electrode group will be described with reference to this Figure. A strip of negative electrode plate
1
is fixed on one surface (the upper surface in the drawing) of a strip of separator
2
by means of non-woven cloth
3
in a predetermined relative position with respect to the separator
2
, and a positive electrode plate
8
is overlaid on the other surface (bottom surface in the drawing) of the separator
2
. This strip-shaped electrode group is wound up in spiral condition, and its circumference is fixed by means of a circumferential tape
10
. Prior to winding up the strip-shaped electrode group, a negative electrode lead portion
4
is mounted on the negative electrode plate
1
and a positive electrode lead portion
9
is mounted on the positive electrode plate
8
, respectively.
FIGS. 11A
to
11
D are diagrammatic perspective views illustrating the sequence of steps of the manufacturing steps in the conventional spiral electrode group manufacturing apparatus. From its central portion S, the separator
2
is divided into a first region Q from one end thereof and a second region P from the other end thereof. The strip-shaped electrode group is formed with the negative electrode plate
1
arranged on the upper surface of one or other of the regions (in this example, the first region Q) in this separator
2
and the positive electrode plate
8
overlaid on the bottom surface thereof, respectively. In the other region P, only the separator
2
is provided.
A winding shaft
11
for winding the aforementioned strip-shaped electrode group is constituted of a winding core
12
and an auxiliary pin
13
; winding core
12
is provided in its axial direction with a plurality of grooves (not shown) at its circumference, in the manner of a reamer. First of all, as shown in
FIG. 11A
, the winding shaft
11
comprising the winding core
12
and the auxiliary pin
13
is made to project towards the central portion S of the strip-shaped electrode group, and is rotated to start winding the strip-shaped electrode group with this central portion S being gripped by the winding core
12
and the auxiliary pin
13
. At the time point where this strip-shaped electrode group has been wound a few times, as shown by the arrow in
FIG. 11B
, the auxiliary pin
13
is withdrawn and removed from the strip-shaped electrode group. After this, as shown in
FIG. 11C
, the strip-shaped electrode group is wound to completion using only the winding core
12
. In this process, winding of the strip-shaped electrode group is performed whilst applying a suitable tension by suction means, to be described. Then, when winding has been completed, as shown in
FIG. 11D
, a circumferential tape
10
is wound around the electrode group in order to prevent it from coming loose, whereby a spiral electrode group
14
is completed.
FIG. 12
is a vertical cross-sectional view illustrating the major structural portions of the above apparatus for manufacturing spiral electrode groups. A first suction means
17
that holds the first region Q of the strip-shaped electrode group by suction and a second suction means
18
that holds the second region P of the strip-shaped electrode group by suction are arranged on both sides of the winding shaft
11
. The winding shaft
11
is, as described in the foregoing, in engagement with the central portion S of the strip-shaped electrode group, and winds the separator from the central portion S thereof as being folded in two. The two suction means
17
and
18
are of identical construction. Specifically, the two suction means
17
,
18
are provided with endless belts
19
that respectively attract by vacuum the corresponding regions Q, P of the strip-shaped electrode group by means of a plurality of suction holes (not shown). The endless belts
19
are fed with a desired speed by feed means, in a manner which is responsive to the increased diameter produced by the winding of the strip-shaped electrode group by the winding shaft
11
. The first region Q and second region P are thereby displaced towards winding shaft
11
such that a suitable tension acts on the first region Q and the second region P of the strip-shaped electrode group that are respectively held by suction.
The feed means of the endless belt
19
comprises a cam groove
20
, a rod
22
having a cam follower
21
provided at its bottom end to engage with the cam groove
20
, a pinion
27
that meshes with a rack
24
at the top end of the rod
22
as the rod
22
is moved vertically along a guide
23
in accordance with the shape of the cam groove
20
, a drive gear wheel
28
integral with the pinion
27
, a transmission gearwheel
29
that meshes with the drive gear wheel
28
, and drive rollers
30
that are rotated by the transmission gearwheel
29
, causing drive rollers
30
to abut on the endless belts
19
, thereby feeding and driving the endless belts
19
.
With this spiral electrode group manufacturing apparatus, the first region Q and the second region P of the strip-shaped electrode group, which are respectively held by the respective endless belts
19
of the first suction means
17
and second suction means
18
, are displaced towards the winding shaft
11
from both sides by the feed means. Thereby, application of excessive tension to the separator
2
and other elements constituting the strip-shaped electrode group can be prevented. The feed speed of the endless belts
19
is controlled such that this tension is the optimum, so that elongation of the separator
2
and others does not occur and occurrence of winding misalignment of the electrode plates
1
,
8
is prevented.
However, it has been ascertained that there is still room for improvement in the manufacturing apparatus for a spiral electrode group as described above. With manufacturing equipment as described above, in the case of manufacturing spiral electrode groups for nickel/cadmium batteries or nickel metal hydride batteries, comparatively good spiral electrode
Aoi Takayuki
Kaneda Masaaki
Kashiyama Akihiro
Koda Minoru
Cantelmo Gregg
Ryan Patrick
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