Metal working – Expanded metal making – By use of reciprocating perforator
Reexamination Certificate
1999-03-02
2001-03-20
Bryant, David P. (Department: 3726)
Metal working
Expanded metal making
By use of reciprocating perforator
C029S006100, C029S002000
Reexamination Certificate
active
06202271
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an expanded mesh sheet that is preferable for use as a battery collector, and more particularly to a method and apparatus for manufacturing an expanded mesh sheet with which a fine reticulated configuration can be formed in a thin metal sheet for realizing smaller, thinner, and higher capacity batteries, and to a battery using this expanded mesh sheet.
2. Description of the Related Art
As portable instruments such as portable telephones have become smaller, thinner, and lighter in weight, the batteries used as a source of power by such instruments have been required to have higher capacities, as well as to be smaller and lighter.
FIGS. 13 and 14
show the constitution of a polymer electrolyte secondary cell, a type of battery developed in response to these requirements. This battery comprises a laminated electrode
4
, of positive electrode plates
1
and a negative electrode plate
2
laminated together with separators
3
therebetween, held within an outer case
7
comprising a laminated sheet. As shown in
FIG. 14
, which shows a cross sectional view of
FIG. 13
at line XIV—XIV, the above-mentioned positive electrode plate
1
is formed of positive electrode active material
1
b
coated on a positive electrode collector
1
a
; the above-mentioned negative electrode plate
2
is formed of negative electrode active material
2
b
coated on a negative electrode collector
2
a
. The positive electrode plate
1
and negative electrode plate
2
are layered together with separators
3
, consisting of solid electrolyte material therebetween, and sealed along with liquid electrolyte within an outer case
7
, comprising a pair of laminated sheets heat fused along their perimeters at seal portions P
1
, P
2
, P
3
. The positive electrode lead
8
is connected to the lead connecting portions
1
c
,
1
c
each formed on the two positive electrode collectors
1
a
,
1
a
and the negative electrode lead
9
is connected to the lead connecting portion
2
c
formed on the negative electrode collector
2
a
. The positive electrode lead
8
and negative electrode lead
9
are insulated from each other with an insulating sheet
6
and drawn out to the outside of the outer case
7
so as to be used as battery connection terminals for the positive and negative electrodes of the battery.
The above-mentioned positive electrode plate
1
and negative electrode plate
2
are manufactured as follows. The positive electrode active material, prepared as a paste, is applied on an expanded mesh sheet of aluminum that will constitute the positive electrode collector
1
a
, which is then dried and rolled to form a positive electrode sheet. The positive electrode place is cut to a prescribed form and size from this positive electrode sheet thus obtained wherein the positive electrode active material
1
b
is adhered to a prescribed thickness on the positive electrode collector
1
a
. Also, the negative electrode active material, prepared as a paste, is applied on both surfaces of an expanded mesh sheet of copper that will constitute the negative electrode collector
2
a
, which is then dried and rolled to form a negative electrode sheet. The negative electrode plate is cut to a prescribed form and size from this negative electrode sheet thus obtained wherein the negative electrode active material
2
b
is adhered to a prescribed thickness on both surfaces of the negative electrode collector
2
a
. As shown in
FIG. 13
, the positive electrode plate
1
and negative electrode plate
2
are cut from the positive electrode sheet and negative electrode sheet respectively, such that the lead connecting portion
1
c
protrudes from the positive electrode collector
1
a
at a position offset from the center line, and such that the lead connecting portion
2
c
protrudes from the negative electrode collector
2
a
at a position offset from the center line opposite from the lead connecting portion
1
c
of the positive electrode collector
1
a
. The aluminum positive electrode lead
8
is joined to the lead connecting portion
1
c
of the positive electrode collector
1
a
, and the copper negative electrode lead
9
is joined to the lead connecting portion
2
c
of the negative electrode collector
2
a
, respectively, at welding points S using resistance welding or ultrasonic welding.
In order to satisfy the requirement that a battery be small, light, and have higher capacity, the expanded mesh sheet used as a collector must be thin, with a fine mesh grid, and yet have the strength to withstand the tensile force applied during manufacture. Moreover, the mesh sheet must be superior in binding properties to the active material and collecting properties.
In the collector, the electrodes of same polarity are connected to each other at the lead connecting portions, and the lead is further connected thereto. Therefore, the lead connecting portions are required to have better welding properties as the number of laminated positive and negative electrodes increases. However, in collectors wherein an expanded mesh sheet with a high rate of openings is used, the lead connecting portions tend to have poor welding properties, and low bonding strength and conductivity between collectors and leads.
The above-mentioned expanded mesh sheet is manufactured by pulling a metal sheet, wherein slits have been formed in a zigzag pattern, in a direction perpendicular to the orientation of the slits, thereby opening the slits to form a lozenge-shaped reticulated configuration.
In other words, as shown in
FIG. 15A
, a multiplicity of slits a are formed intermittently and parallel to each other in the direction in which the metal sheet A extends. The slits a are arranged in a zigzag pattern, with the parallel and adjacent positions being offset in the direction in which the metal sheet A extends; nodes b are formed between intermittent slits a, a. Furthermore, as shown in
FIG. 15B
, bulges c are formed by plastic deformation at positions sandwiched between slits a, a juxtaposed in a widthwise direction, protruding from both surfaces of the metal sheet alternately in opposite directions. Such a metal sheet, wherein slits a, nodes b, and bulges c have been formed, is pulled widthwise as shown in
FIG. 16
to attain an expanded mesh sheet having a mesh grid structure, wherein the slits a, a are opened thus forming lozenge-shaped openings surrounded by linear lattice bars d connected by nodes b.
Current methods for manufacturing this type of mesh sheet include those using a rotary system and those using a reciprocating system.
FIG. 17
shows an example of a rotary-type apparatus for manufacturing expanded mesh sheets. This apparatus includes a pair of rollers
100
,
100
which is constructed such that a plurality of disk-shaped cutters
31
, that are provided with raised portions
32
for forming the above-mentioned bulges c on the periphery, are superposed coaxially at intervals approximately equal to the thickness of the disk-shaped cutters
31
. The rollers
100
,
100
are disposed opposite to each other with their axes being parallel and their positions in the axial direction being offset by the thickness of the disk-shaped cutters
31
. Blades for forming the slits a in the direction in which the metal sheet A is supplied and in an area between the disk-shaped cutters
31
of one roller
100
and the disk-shaped cutters
31
of the other roller
100
, are formed on both edges of each disk shaped cutter
31
. Recessed portions
33
for interrupting the formation of the slits a and for forming the nodes b are formed at a prescribed pitch on the blades in the direction of the circumference of the disk-shaped cutters
31
. By supplying the metal sheet A between the rollers
100
,
100
and rotating the rollers
100
,
100
around their respective axes, the slits a connected with the nodes b are formed in the metal sheet A, as well as the bulges c protruding in mutually opposite directions are formed at positions where slits a, a, are juxtaposed with ea
Goda Yoshio
Kobayashi Hiroyuki
Nakatsuka Saburo
Ogawa Masahiko
Bryant David P.
Jordan and Hamburg LLP
Matsushita Electric - Industrial Co., Ltd.
Omgba Essama
LandOfFree
Method and apparatus for manufacturing expanded mesh sheet... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and apparatus for manufacturing expanded mesh sheet..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and apparatus for manufacturing expanded mesh sheet... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2467770