Metal working – Means to assemble or disassemble – Overedge assembling means
Reexamination Certificate
2000-01-31
2001-07-10
Crane, Daniel C. (Department: 3725)
Metal working
Means to assemble or disassemble
Overedge assembling means
C029S283500, C029S623100, C072S357000
Reexamination Certificate
active
06256853
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to crimping dies and the like, and in particular to a crimping die that utilizes a powered chuck and segmented die to release a formed part.
Various types of metal forming dies have been used in the fabrication of a wide array of parts. One example is an electrochemical battery cell having a two piece cladding that is crimped together to form the finished battery cell. Known crimping methods utilize a one piece female die. A punch drives the two pieces of the cell into the female die segment, thereby deforming the outer edge of one of the cell pieces, and crimping the two sections together to form the electrochemical cell.
One problem encountered in such an arrangement is that the formed steel part will have some residual stress, causing the part to “spring” outwardly against the inner sidewalls of the female die segment. The friction generated between the part and the sidewalls of the female die segment can make removal of the formed cell difficult, leading to damage of the cell. Although lubricants may aid removal of the cell to some degree, such lubricants may lead to contamination of the cell. Even with lubrication it may not be possible to crimp the cell as tightly as desired and still permit removal of the cell without damage thereto, particularly for cells with thin sidewalls, such as miniature air cells.
A prior art segmented crimping die is shown in FIGS.
8
and
9
A-
9
C. As shown in
FIGS. 9A-9C
, the prior art die includes a one-piece base support
101
having a bore
102
through which a lower punch
103
may be moved. Base plate
101
is generally fixed relative to the other parts. Base plate
101
further includes a recess
104
in which a one-piece crimp die
105
is disposed. Crimp die
105
also includes a central aperture through which lower punch
103
extends. The die further includes a tapered guide housing
106
disposed in fixed relation on base plate
101
and a top plate
107
mounted atop tapered guide housing
106
. Tapered guide housing
106
includes a centrally disposed tapered opening
109
for receiving four segmented dies
108
a
-
108
d
. As shown in
FIG. 8
, which is a top view of the four segmented dies, the four segmented dies together form annular side walls of the die and define a central opening through which an upper punch
111
and a battery
110
to be crimped may be moved. Top plate
107
also includes a centrally disposed hole of the same diameter for similarly allowing upper punch
111
and cell
110
to be moved therethrough. As shown, the four segmented dies are tapered and allowed to slide vertically along the tapered surface
109
of guide
106
. In this matter, as the four segmented dies
108
a
-
108
d
move vertically between the upper surface of the one-piece crimp die
105
and the lower surface of top plate
107
, the four segmented dies move radially inward and outward to thereby increase/decrease the diameter of the centrally disposed aperture defined by the four segmented dies
108
a
-
108
d.
In operation, the die press is positioned with the four segmented dies
108
a
-
108
d
in their lowermost position resting upon the upper surface of one-piece crimp die
105
. A battery
110
is placed within aperture
112
, and upper punch
111
is moved vertically downward to push the cell down against the curved portion of crimp die
105
. Once the cell has been crimped, upper punch
111
is raised and lower punch
103
is moved vertically upward as shown in
FIG. 9B
to push the crimped battery upward through aperture
112
. Because of the close tolerances with aperture
112
relative to the outer dimensions of the battery, the four segmented dies
108
a
-
108
d
tend to move upward as the battery is lifted by lower punch
103
. As the four segmented dies
108
a
-
108
d
are lifted, they will move radially outward at the same time until their upper surfaces abut the stops on top plate
107
. With the four segmented dies in their uppermost position, the diameter of aperture
112
is sufficient to freely remove battery
110
from the die apparatus.
A problem exists, however, in that some of the segmented dies
108
a
-
108
d
may at times become hung up, as shown in FIG.
9
C. Thus, when the next battery is inserted for crimping, the battery may become misaligned and a uniform crimping of the battery may not be obtained. A similar problem can occur during crimping, with one segment rising up independent of the other segments, due to the axial component of the radial stress on the angled surface, and thereby limiting the amount of radial stress that can be applied during crimping.
Accordingly, an apparatus and method for alleviating the above-identified problems would be desirable.
SUMMARY OF THE INVENTION
One aspect of the present invention is to provide a forming die including a base and at least two die segments. At least a first one of the die segments is moveably mounted to the base for shifting between closed and opened positions. The die segments together define a cavity having an opening when the first die segment is in the closed position. A punch is moveably mounted to the base for shifting between a retracted position and an extended position wherein the punch crimps a part positioned within the cavity. A powered actuator is connected to at least the first one of the die segments, and shifts the first die segment between the closed and opened positions such that a part positioned within the cavity can be removed after crimping by shifting of the first die segment to the open position.
Another aspect of the present invention is a forming die including a base and a pneumatic chuck. The pneumatic chuck has at least two powered jaws mounted to the base. The powered jaws are shiftable between extended and retracted positions. A die piece is mounted to each of the powered jaws, and the die pieces together define a die forming surface when the powered jaws are in the extended (closed) position. A punch is movably mounted to the base, and shifts to an extended position to form a part positioned against the die forming surface. The powered jaws shift to the retracted position to permit removal of a part from the forming die.
Yet another aspect of the present invention is a forming die including a base and a fluid actuated clamp. The clamp includes a chamber connectable to a source of pressurized fluid. The clamp also includes a flexible diaphragm in fluid communication with the chamber. A die assembly includes at least two die pieces, each of which is operably connected to the flexible diaphragm and shifts from an engaged position to a disengaged position upon pressurization of fluid within the chamber. Together, the die pieces define a die forming surface when in the engaged position. A punch is movably mounted to the base and shifts between a disengaged position away from the die forming surfaces, and an engaged position wherein the punch forms a part positioned in the die assembly. The die pieces shift to the disengaged position upon pressurization of fluid within the chamber to release a formed part for removal from the forming die.
Yet another aspect of the present invention is a method of crimping a deformable part. The method includes mounting die pieces on the jaws of a pneumatic chuck. The chuck is actuated to move the jaws into a clamped position such that the die pieces form a die cavity having sidewalls. A part positioned in the die cavity is punched to crimp the outer edge of the part along the sidewalls of the die cavity, and the chuck is actuated to move the jaws into a released position.
These and other advantages of the present invention will be further understood and appreciated by those skilled in the art by reference to the following written specification, claims, and appended drawings.
REFERENCES:
patent: 1844616 (1932-02-01), Whiton
patent: 1895401 (1933-01-01), Simonsen et al.
patent: 2473673 (1949-06-01), Bell
patent: 2663205 (1953-12-01), Allen
patent: 2755839 (1956-07-01), Garrock
patent: 3604240 (1971-09-01), Weyhmüller et al.
patent:
Piantoni Raymond W.
Ray, Jr. Robert E.
Crane Daniel C.
Eveready Battery Company Inc.
Toye, Jr. Russell H.
Welsh Robert W.
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