JP2006236949A - Safety valve plate of sealed battery case, its molding method and its molding device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a safety valve plate (compression-molded article) of a sealed battery instantly ruptured by predetermined rupture working pressure (gas pressure); and to provide its molding method; and to provide its molding device. <P>SOLUTION: This safety valve plate of a sealed battery is provided with: a thin recessed part bottom 12a compression-molded around a predetermined area on a surface of a metal plate 1'; and a dimension stabilization part 22 molded by restraining the bulge of the predetermined area in the compression molding of the recessed part 12; and a corner part of the recessed part bottom 12a on the dimension stabilization part 22 is formed into a sharp corner 12' having a radius of 5-50 μm. After forming a recessed part 32 in a predetermined area set on a surface of the metal plate 1', when compression-molding the recessed part 12 around the predetermined area set on the bottom of the recessed part 32, the bulge in the predetermined area is molded by restraining it by an area molded article 6 moving independently of a recessed part molded article 5. The tip angle of the recessed part molded article 5 on the predetermined area side is formed into a sharp edge having a radius of 5-50 μm. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a safety valve plate for a sealed battery and a method for forming the same, more specifically, a safety valve plate for a sealed battery container that discharges gas in the battery to the atmosphere when the internal pressure of the sealed organic electrolyte battery is increased, and a method for forming the same. The present invention relates to a molding apparatus.

  Conventionally, in a sealed battery safety valve plate, a flexible membrane that closes the valve hole is sandwiched between a plate plate having a valve hole at the opening of the battery container and a terminal plate having a gas vent hole, and the terminal plate is flexible. There has been proposed a safety valve structure (see Patent Document 1) in which a cutting blade is provided so as to protrude from a membrane and a thin portion by a wedge-shaped annular recess is provided in the terminal plate as the center of a valve hole.

In a sealed organic electrolyte battery, the internal pressure (operating pressure) may increase due to an abnormal reaction in the battery due to a short circuit or contact with a heat source, and the battery container may be destroyed.
Therefore, a safety valve that releases gas when the internal pressure reaches a predetermined pressure and prevents destruction of the battery container is provided on the safety valve plate that closes the opening of the battery container.
In Patent Document 1, when the internal pressure of the battery container exceeds a predetermined pressure, the flexible membrane is elastically deformed by the internal pressure and cut with a cutting blade, or the thin part formed on the terminal plate is damaged and gas is discharged. Are to be released.
The thin part, which is the weak part, is formed at the bottom of the annular groove by providing concentric annular grooves with concentric diameters opposite to each other, and the area surrounded by the annular groove is subjected to gas pressure. The thin portion (fragile portion) is broken by the gas pressure acting on the pressure receiving surface, and gas is released.

However, in Patent Document 1, the structure is not only complicated because of the structure in which the flexible film is sandwiched between the plate with the cutting blade and the terminal plate, and is assembled and fixed to the opening of the battery container. If used, the battery may be accidentally injured when the sealed battery is assembled, and safety is poor.
Moreover, in the flexible membrane, the spreading degree changes due to the change in composition of the membrane components over time, and there is no reliability with respect to breaking at a predetermined breaking operating pressure.
Since the annular groove is formed by cutting, it is cumbersome to form, requires a lot of work time, and the complexity of the structure of using three members (a plate with a cutting blade, a flexible film, a terminal plate) is synergistic. This makes it difficult to provide a low-priced service.
Japanese Utility Model Publication No. 63-167669

The present invention has been made in view of the above-mentioned conventional circumstances, and its intended process is to have a pressure-receiving surface having a stable area with a wide area around which a fragile portion is provided, and to break at a predetermined breaking operating pressure. It is an object of the present invention to provide a suitable sealed battery safety valve plate (compression molded product), a molding method thereof, and a molding apparatus thereof.
Another object is to set the sharpness of the rupture point at the fragile part continuous to the pressure-receiving surface of the stable area, and the sealed battery optimal for timely rupture at a predetermined rupture operating pressure (gas pressure) The present invention provides a safety valve plate (compression molded product), a molding method thereof, and a molding apparatus thereof.

The inventors of the present invention have made extensive research to combine ease of processing, simplification of configuration, and safety, and as a result, a compression molding configuration including a predetermined area set on a metal plate and a concave portion around the predetermined area. In the present invention, it has been found that a pressure-receiving surface having a stable area can be formed in the predetermined area by controlling the bulge generated at the time of the concave compression of the predetermined area.
In addition to stabilizing the area of the pressure receiving surface, the time for the internal pressure to reach the predetermined breaking operating pressure (gas pressure) by setting the sharpness of the corner on the pressure receiving surface side at the recess bottom (fragile portion) to a predetermined value. The present invention has led to the fact that the fragile portion is ruptured by Lee.
That is, the present invention provides a thin concave bottom that is compression-molded around a predetermined area on the surface of a metal plate for a safety valve that closes an opening of a battery container of a sealed organic electrolyte battery, and the predetermined in the concave compression molding. A safety valve plate for a sealed battery comprising a dimensionally stable portion formed by pressing a bulge of an area (Claim 1).
Further, a recess is formed in the first predetermined area on the surface of the metal plate for safety valve configuration that closes the opening of the battery container of the sealed organic electrolyte battery, and the second predetermined area set at the bottom of the recess is formed around the second predetermined area. It is preferable to provide a safety valve plate for a sealed battery in which a compression-molded thin recess bottom is provided and the second predetermined area is formed by a dimensionally stable portion formed by suppressing the swelling in the recess compression molding. (Claim 2).

In the present invention, the weakened portion and the pressure-receiving surface having the surrounding portion are simultaneously formed by compression formation.
In compression molding, particularly press molding, when a certain part is formed, stress is generated that deforms the adjacent part.
If this is, for example, an annular or substantially annular groove, the area enclosed by it will swell.
The bulge amount tends to fluctuate as it is thinner, affected by changes in the metal plate thickness, presence or absence of surface undulations, processing chamber temperature, humidity, and the like.
If this is accepted, the area of the pressure-receiving surface is widened and the breaking force acting on the fragile portion becomes unstable, and the timely release of gas at a predetermined breaking working pressure is hindered.

In the case of a safety valve structure in which the pressure receiving surface has an area around which there is a concave portion that becomes a fragile portion, stabilization of the area of the pressure receiving surface is complemented by the sharpness of the location where the fragile portion is connected to the pressure receiving surface. It is possible to break from the concave portion in a more timely manner at the breaking operating pressure (gas pressure).
Claims 1 and 2 suppress the bulge that is the cause of destabilization of the area of the pressure receiving surface. This presser includes complete suppression that does not cause swelling and semi-suppression (regulation) that prevents free swelling.
By this bulge presser, the free bulge of the area having the concave portion around is restricted, and a dimensionally stable portion with little variation in the pressure receiving area can be formed in the area.

  In order to perform a more timely break from the recess at a predetermined breaking operating pressure (gas pressure), the corner on the dimensionally stable portion side at the bottom of the recess is a sharp corner with a radius of 5 μm to 50 μm. (Claim 3).

The molding method is to set a recess in the first predetermined area set on the surface of the metal plate for the safety valve structure that closes the opening of the battery container of the sealed organic electrolyte battery, and then set the bottom of the recess When the concave portion is compression-molded around the second predetermined area, the bulge of the second predetermined area is pressed by the area molded body integrated with the concave molded body to be molded (Claim 4).
The molding apparatus includes a concave molded body in which a recess is formed in a first predetermined area set on a surface of a metal plate for a safety valve that closes an opening of a battery container of a sealed organic electrolyte battery, and a bottom of the recess And a recessed portion molded body that compresses the recessed portion around the second predetermined area, and an area molded body that is integrated with the recessed portion molded body and suppresses the swelling of the second predetermined area during the recessed portion compression molding. (Claim 7).
By comprising in this way, the dimension stable part where a pressure receiving area is stabilized can be shape | molded simultaneously with the compression molding of a recessed part.

In addition, as a molding method, after forming a recess in the first predetermined area set on the surface of the metal plate for the safety valve structure for closing the opening of the battery container of the sealed organic electrolyte battery, A configuration is adopted in which when the concave portion is compression-molded around the set second predetermined area, the bulge of the second predetermined area is pressed by an area molded body that can move independently of the concave molded body, and molded. This is preferable (claim 5).
The molding apparatus includes a concave molded body in which a recess is formed in a first predetermined area set on a surface of a metal plate for a safety valve that closes an opening of a battery container of a sealed organic electrolyte battery, and a bottom of the recess A recess molded body that compresses and forms a recess around a second predetermined area, and an area molded body that is independently movable with respect to the recess molded body and suppresses the swelling of the second predetermined area during the recess compression molding. (Claim 8).

  According to the above means, the bulge can be completely suppressed or the presser amount can be adjusted with the movable area molded body.

  Preferably, the molding method is preferably such that the tip angle on the predetermined area side of the concave molded body is formed with a sharp edge having a radius of 5 μm to 50 μm, and the bulging deformation that occurs in the second predetermined area at the time of concave compression molding is performed on the area molded body. It is optimal to convert into a deformation in the outer peripheral direction so that the corner of the recess on the second predetermined area side is along the sharp edge of the recess molding (claim 6).

  In each claim, the thin concave bottom is provided over the entire circumference around a predetermined area on the surface of the metal plate, or is provided except for a part thereof.

Since the present invention is configured as described above, it has the following advantages.
(Claims 1 and 2) Since the dimensionally stable portion composed of a predetermined area having a recess around it is a safety valve plate formed by pressing the bulge of the predetermined area when the recess is compression-molded, the inner surface of the dimensionally stable portion The safety pressure plate that is suitable for releasing gas at a predetermined breaking operating pressure can be provided as a compression molded product without the area of the gas pressure receiving surface being wide and narrow, the breaking force acting on the bottom of the recess being stabilized.
Moreover, since it is a safety valve plate comprising a thin recess bottom and a dimension stabilizing portion having the recess around it, the flexible membrane is sandwiched between the plate and the terminal plate and assembled and fixed to the opening of the battery container. It does not have a complicated configuration as in the prior art, can contribute to the inexpensive provision of the battery case, and there is no risk of injury from the cutting blade when assembling the battery case.

(Claims 4 and 7) Since it is a method and an apparatus for suppressing the swelling of the area having the recessed part at the same time when the recessed part is compression-molded, the forming tact time can be shortened and the productivity can be improved. The equipment cost is low with a simple configuration.

(Claims 5 and 8) Further, since the area molded body that suppresses the bulge of the area at the time of the concave compression molding is a method and apparatus that moves independently of the concave molded body, the bulge is completely suppressed by the adjustment function. it can.

(Claim 3) Since the corner portion on the dimensionally stable portion side of the concave portion is a sharp corner having a radius of 5 μm to 50 μm, the optimum safety valve breaks in a timely manner when the predetermined breaking operating pressure is reached. Can provide a board.
(Claim 6) Further, since the sharp corner is formed by the concave formed body and the area molded body, a separate means and process for forming the sharp corner are completely unnecessary.

  Next, an embodiment of the safety valve plate of the sealed battery container of the present invention, a molding method thereof, and a molding apparatus will be described. FIGS. 1 to 6 show the first embodiment, and FIG. 7 shows the second embodiment. An embodiment is shown.

The first embodiment shown in FIGS. 1 to 6 will be described. Reference numeral 1 denotes a safety valve plate of a battery container.
The battery container is made of an aluminum alloy, is processed into a rectangular parallelepiped shape, and accommodates, for example, an organic electrolyte battery member therein, and the safety valve plate 1 has an appropriate means such as laser welding at the opening of the battery container. It is joined in an airtight manner.

  As shown in FIG. 1 and the like, the safety valve plate 1 is a safety valve comprising a recess bottom 12a and a dimension stabilizing portion 22 near one short edge of a metal plate 1 ′ having an area that matches the opening area of the opening of the battery container. 2 is provided.

As shown in FIG. 1, the concave portion 12 is formed in a track shape in plan view in which both ends of both longitudinal edges parallel to each other with a predetermined interval are continuous with arc edges.
In addition, the planar view shape of the recessed part 2 may be formed in another planar view shape.

  The concave portion 12 is continuously formed by compression molding around the second predetermined area c2 set at the bottom thereof after the recess 32 is provided in the first predetermined area c1 set at the metal plate 1 ′. The bottom is thin.

The dimension stabilizing portion 22 is formed by pressing the swelling of the second predetermined area c2 in the concave portion 12 compression molding.
More specifically, the dimension stabilizing portion 22 has a concave portion 12 around the battery container with a semi-suppression (regulation) that suppresses free swelling of the second predetermined area c2 that occurs at the time of compression molding of the concave portion 12 and complete suppression that does not cause swelling. The area of the pressure receiving surface 22a facing the inside is stabilized.
And in the connecting part of the dimension stabilizing part 22 and the recessed part 12, the corner part by the side of the dimension stabilizing part 22 of the recessed part bottom 12a is made into the sharp corner which makes a radius 5 micrometers-50 micrometers, and the recessed part bottom 12a is the sharp corner. 12 'serves as an actual breakage point at the time of breakage.

  Next, the molding method of the safety valve plate of the sealed battery container and the molding apparatus will be described with reference to FIGS. 4 to 6. In each figure, reference numeral 3 is a die, 4 is a recess molding, and 5 is a recess molding. , 6 is an area molded body. Both are incorporated into a compression molding apparatus, that is, a press apparatus, as a mold so as to be exchangeable and detachable.

  This forming method and forming apparatus show a semi-suppressing (regulating) method and apparatus for suppressing the above-mentioned free bulge, and the recess formed body 4 has a flat area that matches the area of the first predetermined area c1. The punch, the concave formed body 5 is a processing punch for concave portions applied around the second predetermined area c2 set on the bottom of the concave formed by compression molding in the one predetermined area c1, and the area molded body 6 is the concave portion. It is a processing punch integrated with the molded body 5, and this area molded body 6 has a molding surface provided integrally by changing the height of the entire region surrounded by the recessed molded body 5 toward the tip of the recessed molded body 5. This is a machining punch that is flat (horizontal).

  In this embodiment, the tip angle on the second predetermined area c2 side of the concave formed body 5 is formed with a sharp edge having a radius of 5 μm to 50 μm.

  The procedure for forming the safety valve 2 on the metal plate 1 ′ using this forming apparatus will be described. First, a recess is formed in the first predetermined area c 1 set on the metal plate 1 ′ set on the die 3. Compression molding (coining) is performed on the molded body 4 to form a recess 32 having a track shape in plan view.

Next, compression molding is performed around the second predetermined area c <b> 2 set on the bottom surface of the recess 32 in an annular shape by the recess molding body 4.
The compression molding (coining process) may be performed by removing an intermediate portion of the one-side arc edge of the second predetermined area c2.
At this time, the upward bulging deformation that occurs as the concave portion 12 is compressed into the thin concave bottom 12a by compression molding is suppressed by the area molded body 6 and converted into deformation in the direction of the concave molded body 5.
Specifically, the area molded body 6 suppresses the upward bulging deformation and converts the bulging deformation into deformation in the outer peripheral direction. Then, the corner of the recess 12 on the second predetermined area c2 side is aligned with the sharp edge of the recess molding 5.

  As a result, the second predetermined area c2 is, for example, an area surrounded by a thin concave bottom 12a, which is a fragile portion, as compared with the safety valve plate 1 that allows free bulge deformation that does not hold the bulge in the area molded body 6. In addition, it is possible to reproducibly form the dimension stabilizing portion 22 in which the area of the pressure receiving surface 22a facing the battery container is stable.

Next, a second embodiment shown in FIG. 7 will be described. This embodiment shows a molding apparatus configured to move the area molded body 6 independently with respect to the recessed molded body 5.
Thus, by making the protrusion amount of the area molded body 6 variable, the bulge can be completely suppressed by the area molded body 6. Further, the presser amount can be adjusted as necessary.

  Further, although the compression molding of the metal plate itself is performed twice, the first compression molding may be omitted and only the second compression molding may be performed. In this case, in the area corresponding to the first predetermined area of the metal plate (which may be subjected to drawing if necessary), the concave molded body integrated with the area molded body of the first embodiment or the second The bulge is pressed and molded so as to be converted into deformation in the outer peripheral direction by the combined use of the concave molded body and the movable area molded body of the embodiment.

Next, the experimental result (table) of the fracture | rupture operating pressure with respect to the recessed part bottom 12a thickness (fragile part) is demonstrated.
(Experimental example 1) Area molded body 6 which is a safety valve plate (semi-suppressed) molded by the molding method and apparatus described in the first embodiment and has a radius of 50 μm at the tip angle on the second predetermined area c2 side. An integral recessed body 5 was used.
(Experimental example 2) Recess molded body 5 which is a safety valve plate (completely restrained) molded by the molding method and apparatus described in the second embodiment, and the tip angle on the second predetermined area c2 side is formed with a radius of 50 μm. And a movable area molded body 6 were used in combination.
(Comparative Example 1) Recess molded body 5 which is a safety valve plate (complete suppression) molded by the molding method and apparatus described in the second embodiment, and has a radius of 100 μm at the tip angle on the second predetermined area c2 side. And a movable area molded body 6 were used in combination.
In the (Experimental example 1), the area molded body 6 is set at a position 380 μm above the tip of the recessed molded body 5.
The metal plate has a thickness of 800 μm and the depth of the recess is 500 μm.
Both are the results of experiments in use in the state where they are mounted in the opening of a battery container having a width of 4 mm.
Each black circle is a test sample.

In each example, the area of the pressure-receiving surface (surface facing the battery container of the dimension stabilizing portion) 22a which was compression-molded (coined) to a concave bottom thickness of 29 μm to 31 μm using the molding method and apparatus of the present invention was stabilized. It is a safety valve plate.
In (Experimental example 1), compression molding (coining) is performed from a concave bottom thickness of 300 μm to a concave bottom thickness of 29 μm to 31 μm, so that it occurs in a second predetermined area when the concave bottom changes to a thin bottom. Swelling deformation is suppressed by the area molded body, and the dimensionally stable portion is deformed outwardly so that the surface (outer surface) conforms to the processed punch shape of the recessed molded body.
The concave bottom thickness of 29 μm to 31 μm is a necessary secured thickness that also has a drop impact strength and is an in-house standard value.
In addition, in-house standards stipulate that the operating pressure at break is in the range of 1.4 to 2.0 MPa (light gray display), and that the in-house optimum specified operating thickness (in dark gray display) is strictly specified to be 1.6 to 2.0 MPa. The break operating pressure range is set to a predetermined value, and any other value is prohibited.

According to the experimental results, in (Experimental example 1) and (Experimental example 2), the safety valve broke from the sharp corner in the range of 1.7MPa to 1.95Mpa and 1.65Mpa to 1.8Mpa in-house standard (predetermined pressure). On the other hand, (Comparative Example 1) was not broken from the sharp corner (breakage point) unless the operating pressure was 2.15 Mpa to 2.4 Mpa.
Also, in the comparison of both (Method 2) and (Comparative Example 1) with the same molding method and apparatus, (Experiment 2) is stable at a low rupture operating pressure with little variation within the company's optimum specified operating thickness. Thus, it is proved that the sharpness of the bottom corner of the recess also affects the rupture operating pressure.
In addition, the same experiment was performed on the safety valve plate mounted on a 6 mm-wide battery container, but the same tendency was shown although there were differences in the bottom thickness of the recess and the operating pressure at break.

As a result of this experiment, the sharpness of the corner portion on the dimension stabilizing portion 22 side of the recess bottom 12a is complemented by the stabilization of the area of the pressure receiving surface 22a of the dimension stabilizing portion 22, and more timely at a predetermined breaking operating pressure. It is understood that a proper fracture is achieved.
Further, the experiment using the area molded body 6 having a tip angle of 5 μm in radius showed less variation in breaking operating pressure.

  The breaking operating pressure (predetermined pressure) is different for each battery container manufacturer, but is not as severely limited as its own standards. Therefore, in the first aspect of the present invention, the safety valve plate molded by the molding method and apparatus that does not limit the sharpness of the corner portion on the dimension stable portion side in the bottom of the recess is included.

1 is a partially cutaway enlarged view showing a state where a safety valve plate of a sealed battery of the present invention is attached to a battery container. The (a)-(a) sectional view taken on the line of FIG. 1 of the safety valve plate shape | molded with the shaping | molding method shown in 1st Embodiment, and an apparatus. The (b)-(b) sectional view taken on the line of the safety valve plate of FIG. Sectional drawing which follows the said (a)-(a) line | wire which shows the state which compression-molds (coin-printing) a recess with a recessed body molded object in the shaping | molding method and apparatus shown in 1st Embodiment. In the molding method and apparatus shown in the first embodiment, a state in which swelling is suppressed in parallel with compression molding (indentation processing) of a recess with a recess molding integrally provided with an area molding on a metal plate is shown. Sectional drawing which follows the said (a)-(a) line. In the molding method and apparatus shown in the first embodiment, a state in which swelling is suppressed in parallel with compression molding (indentation processing) of a recess with a recess molding integrally provided with an area molding on a metal plate is shown. Sectional drawing which follows the said (b)-(b) line. In the shaping | molding method and apparatus shown in 2nd Embodiment, the state which suppressed the swelling in parallel with carrying out the compression molding (coinling process) of a recessed part with a recessed part molded object and a movable area molded object to a metal plate is shown. Sectional drawing which follows the said (a)-(a) line.

Explanation of symbols

1: Safety valve plate 1 ': Metal plate 22: Dimensional stability portion 12: Recess 12a: Recess bottom c1: First predetermined area c2: Second predetermined area 32: Recess 4: Recess molded body 5: Recess molded body 6: Area molded body 2: Safety valve 22a: Pressure receiving surface 12 ': Sharp corner 3: Die

Claims (8)

  Hold the thin concave bottom that is compression-molded around a predetermined area on the surface of the metal plate for the safety valve structure that closes the opening of the battery container of the sealed organic electrolyte battery, and suppress the swelling of the predetermined area in the concave compression molding A safety valve plate for a sealed battery, comprising a molded dimension stabilizing portion.   A recess is formed in the first predetermined area on the surface of the metal plate for the safety valve that closes the opening of the battery container of the sealed organic electrolyte battery, and compression is performed around the second predetermined area set at the bottom of the recess. A safety valve plate for a sealed battery, characterized in that it is provided with a molded thin-walled recess bottom and the second predetermined area is formed by a dimensionally stable portion formed by pressing the bulge in the recess compression molding.   The safety valve plate for a sealed battery according to claim 1 or 2, wherein the corner on the dimension stabilizing portion side in the bottom of the recess is a sharp corner having a radius of 5 µm to 50 µm.   After forming a recess in the first predetermined area set on the surface of the metal plate for the safety valve structure for closing the opening of the battery container of the sealed organic electrolyte battery, the second predetermined area set on the bottom of the recess A method for forming a safety valve body for a sealed battery, comprising: pressing a bulge of the second predetermined area with an area molded body integral with a recessed molded body when the concave section is compression molded around.   After forming a recess in the first predetermined area set on the surface of the metal plate for the safety valve structure for closing the opening of the battery container of the sealed organic electrolyte battery, the second predetermined area set on the bottom of the recess Molding of a safety valve body for a sealed battery, characterized in that when a recess is compressed around, the bulge of the second predetermined area is pressed by an area molded body that can move independently of the molded molded body. Method.   The tip angle on the predetermined area side of the concave formed body is formed with a sharp edge having a radius of 5 μm to 50 μm, and the bulging deformation that occurs in the second predetermined area at the time of concave compression molding is transformed into the outer peripheral direction by the area molded body. 6. The method of molding a safety valve body for a sealed battery according to claim 4, wherein the corner portion of the recess on the second predetermined area side is converted to be along the sharp edge of the recess molded body.   A recess molded body in which a recess is formed in a first predetermined area set on the surface of the metal plate for the safety valve structure for closing the opening of the battery container of the sealed organic electrolyte battery, and a first set on the bottom of the recess (2) A hermetic seal comprising: a concave molded body that compresses a concave portion around a predetermined area; and an area molded body that is integrated with the concave molded body and suppresses swelling of the second predetermined area during the concave compression molding. Molded battery safety valve body molding device.   A recess molded body in which a recess is formed in a first predetermined area set on the surface of the metal plate for the safety valve structure for closing the opening of the battery container of the sealed organic electrolyte battery, and a first set on the bottom of the recess (2) A concave molded body that compresses a concave portion around a predetermined area, and an area molded body that is independently movable with respect to the concave molded body and suppresses the swelling of the second predetermined area during the concave compression molding. A device for forming a safety valve body for a sealed battery.

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