JPH08315789A - Manufacture of square battery - Google Patents

Abstract

PURPOSE: To provide a welding method of a sealed vessel of a square battery by which a fitting part having a straight line-shaped side part and a corner part having a prescribed radius of curvature can be excellently welded by a laser over its whole circumference. CONSTITUTION: A cover plate 2 composed of a metallic plate is fitted in an opening of a square case 1 composed of a straight line-shaped side part 31 and a corner part 32 having a prescribed radius of curvature, and a fitting part 3 is welded by a laser, and a sealed vessel of a square battery is formed. In first constitution, a radius of curvature of a locus (either a continuous locus or a sporadic locus) of the spot center of a laser beam is made smaller than a radius of curvature of the corner part 32 of the fitting part 3. In second constitution, laser output at welding time of the corner part 32 of the fitting part 3 is reduced more than laser output at welding time of the side part 31 of the fitting part 3. In third constitution, laser beam scanning speed at welding time of the corner part 32 of the fitting part 3 is increased more than laser beam scanning speed at welding time of the corner part 31 of the fitting part 3.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for manufacturing a prismatic battery.

[0002]

2. Description of the Related Art In a closed prismatic battery disclosed in Japanese Patent Publication No. 6-54660, a lid plate made of a metal plate is fitted into an opening formed at one end of a prismatic case made of metal, and is fitted to a fitting portion. Laser welding is used to form a prismatic battery container,
In particular, the movement of the table on which the rectangular case is placed is started from a predetermined time before the start of laser irradiation, and the movement of the table is continued for a predetermined time even after the laser irradiation end portion is passed, so that each part of the welding area is evenly distributed. It proposes to weld at a welding speed.

Such prismatic batteries are more efficient in space use than cylindrical batteries, and laser welding has a greater thermal effect on the electrolytic solution and electrically insulating parts than other welding methods. It has the advantage that the work efficiency is low and it is excellent. Usually, the above-mentioned rectangular case is formed by molding a metal flat plate, so that a corner portion (also referred to as a corner portion) has a certain radius of curvature, and accordingly, a corner portion of the lid plate also has a corresponding radius of curvature. The fitting portion includes a straight side portion and a corner portion having a predetermined radius of curvature.

[0004]

However, in the inspection of the prismatic sealed battery formed by the above-mentioned conventional laser welding, an internal short circuit, leakage of electrolyte from the welded portion, or insufficient pressure resistance of the welded portion may be found. there were. The present inventors have found that the cause of the defect is due to the welding of the corners by disassembling the defective welding product and observing the cross section.

That is, the welding path is sequentially performed at a constant speed and a constant output (constant pulse density) along the fitting portion as shown in FIG. 3, and for this reason, the straight sides of the fitting portion are connected. The vertical cross section of the melting region (also referred to as the melting region) has a valley shape (single peak shape) shown by a dotted line in FIG. In FIGS. 3 and 4, 1 is a case, 2 is a cover plate, 3 is a fitting portion, 31 is a linear side portion thereof, 32 is a quarter circular corner portion thereof, and W is a welding path. is there.

However, at the corner portion 32 of the fitting portion 3, the bead (melting area = melting area) is particularly beaded due to an increase in irradiation energy per unit length of the fitting portion 3 and a dimensional difference between the inner circumference and the outer circumference of the bead (melting area = melting area). The irradiation energy is increased in the inner peripheral part of the melt, and for this reason the melted region (also called the melted region)
The vertical section has a valley shape shown by the solid line in FIG. That is, in the corner portion 32 of the fitting portion 3, the portion having the maximum depth of the penetration area is biased toward the inner circumference of the bead, and in the corner portion 32 of the fitting portion 3, the maximum depth of the penetration area is equal to that of the fitting portion 3. Side 3
It was found to increase from 1.

For example, FIG. 7 shows a state in which the fitting portion is welded by the pulse type laser welding machine schematically shown in FIG. Figure 7
In FIG. 1, 1 is a rectangular case, 2 is a cover plate, 10 is the top surface of the case, 200 is a welded part, 201 is a circular welded part, and 202 is a penetration increasing part of the welded part 200 where the melting depth is particularly increased. . In such a pulse type laser welding machine, the welded portion 200 to be melted is a circular welded portion 201.
Have overlapping shapes, and the degree of overlap of the circular welded portions 201 is biased toward the inner circumference at the corners of the fitting portion, so the maximum melting depth of the molten weld portion 200 at the corners of the fitting portion is:
It is larger than that at the side of the fitting part.

As a result, if the amount of melting (melting amount) at the side portion 31 of the fitting portion 3 is optimally set, the amount of melting, that is, the irradiation energy density, at the corner portion 32 of the fitting portion 3 becomes excessive, and the spatter of the molten liquid occurs. May be scattered inside the rectangular case 1 or small cracks may remain in the traces of spatter, resulting in defective welding at the corner 32 of the fitting part 3 and causing electrolyte leakage or internal short circuit. Further, since the irradiation is biased toward the inner peripheral side of the corner portion 32, the thermal influence on the inside of the battery becomes large. On the other hand, if the irradiation energy is optimally set at the corner portion 32 of the fitting portion 3, the irradiation energy will be too small at the side portion 31 of the fitting portion 3 and welding failure will occur due to insufficient penetration.

The present invention has been made in view of the above problems, and manufactures a prismatic battery in which a fitting portion having a straight side portion and a corner portion having a predetermined radius of curvature can be favorably laser-welded over the entire circumference thereof. Its purpose is to provide a method.

[0010]

According to another aspect of the present invention, there is provided a metal plate having a rectangular opening formed at one end of a metal case, the metal plate having straight side portions and corner portions having a predetermined radius of curvature. A lid plate made of is fitted and the fitting portion is laser-welded to form a prismatic battery container. In this configuration, the radius of curvature of the spot center of the laser beam (which may be continuous or discrete) may be smaller than the radius of curvature of the corners of the fitting portion. That is, the locus of the center of the spot is set at the corner of the fitting portion and outside the corner of the fitting portion. By doing this, for example, as shown in FIG.
It is possible to compensate for the deepest point of the penetration area at the corner of the fitting part shown in Figure 4 to be displaced to the inner circumference side, and this deepest point can be displaced to the square case side from the fitting part. It is possible to prevent spatter from scattering during welding and to prevent internal short circuit.

According to the welding method of the second aspect, a lid plate made of a metal plate is fitted into a square opening formed at one end of the metal case, the straight plate side portion and the corner portion having a predetermined radius of curvature. Then, the fitting portion is laser-welded to form a prismatic battery container. In this configuration, the laser output at the time of welding the corner portion of the fitting portion is further reduced than the laser output at the time of welding the side portion of the fitting portion. With this configuration, for example, the deepest point of the melted region at the corner of the fitting portion shown in FIG. 4 is deeper than the deepest point at the side portion and does not penetrate through the fitting portion due to the reasons described above. In other words, the amount of melting at the corners of the mating part becomes excessive, the spatter of the molten liquid scatters inside the rectangular case, and minute cracks remain on the traces of the spatter, resulting in poor welding at the corners of the mating part. It is possible to prevent electrolyte leakage and internal short circuit.

According to the welding method of the third aspect, a lid plate made of a metal plate is fitted into a square opening formed at one end of the metal case, the lid plate having straight side portions and corner portions having a predetermined radius of curvature. Then, the fitting portion is laser-welded to form a prismatic battery container. In this configuration, the laser beam scanning speed at the time of welding the corner portion of the fitting portion is further increased than the laser beam scanning speed at the time of welding the side portion of the fitting portion. If it does in this way, the same operation effect as the welding method according to claim 2 can be produced.

According to the welding method of the fourth aspect, a lid plate made of a metal plate is fitted into an opening formed at one end of the metal case, the lid plate being formed of straight side portions and curved corner portions,
The fitting portion is laser-welded to form a prismatic battery container.
In this configuration, the center of the laser spot is further offset to the outside of the corner when welding the corner, and the center of the laser spot is aligned with the side when welding the side to perform laser welding. If it does in this way, the same operation effect as the welding method according to claim 2 can be produced.

According to the welding method of the fifth aspect, a lid plate made of a metal plate is fitted into a square opening formed at one end of the metal case and having straight side portions and curved corner portions. , The fitting portion is laser-welded to form a prismatic battery container. Further, in this configuration, while maintaining the scanning speed of the laser beam at a predetermined value, the laser beam emission interval at the time of welding the corner portion is made longer than that at the time of welding the side portion. If it does in this way, the same operation effect as the welding method according to claim 1 can be produced.

According to the welding method according to claims 6 to 9, the XY table is further used in the welding method according to claims 2 to 5, and the mounting surface thereof is a flat surface including the fitting portion to be welded. Since the plane scanning control of the laser spot is performed by making them parallel to each other, it is possible to simplify the structure of the apparatus and to reliably carry out the welding method according to claims 2 to 5.

According to the welding method of claim 6, claim 1
Further, in the welding method according to any one of items 1 to 5, the lid plate is fitted into the opening of the case by press fitting, so that the lid plate can be prevented from being displaced before welding or temporary fixing.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention will be described with reference to examples. (Embodiment 1) An embodiment of a method for manufacturing a prismatic battery of the present invention will be described with reference to FIGS. FIG. 2 shows a prismatic battery to which the welding method of this embodiment is applied. The container of this battery comprises a rectangular case (metal case in the present invention) 1 and a lid plate 2 which is fitted into an opening at the upper end of the rectangular case 1 and is laser-welded to seal the opening. In FIG. 3, reference numeral 5 is a positive electrode terminal fixed to the central portion of the lid plate 2 so as to be electrically insulated from the lid plate 2 and fixed.

The rectangular case 1 has a rectangular box shape and is formed by molding a nickel-plated steel plate. A battery element 9 (see FIG. 4) made of a positive electrode active material made of lithium cobalt oxide, a separator, a negative electrode active material made of carbon, and a non-aqueous electrolyte is housed in the rectangular case 1. Lid plate 2
Is made of a nickel-plated steel plate (the periphery of which is not plated) that is press-fitted into the opening. After being fitted into the opening of the rectangular case 1, the outer peripheral edge of the lid plate 2 is attached to the inner circumference of the opening of the rectangular case 1 ( While keeping the state of abutting against the opening edge), the fitting portion 3 is welded over the entire circumference by a pulse type YAG laser welding machine (see FIG. 6) to form the rectangular case 1 as a container.

As shown in FIG. 6, in this welding machine, a battery assembly 100 to be welded is fixed and displaced in horizontal X and Y directions, respectively, and an X and Y table 6. 6, a laser oscillator 7 which is immovably positioned above and vertically emits a laser pulse, and a controller 8 which is composed of a personal computer and controls the X and Y tables 6 and the laser oscillator 7. Reference numeral 70 is a lens for focusing (focusing) the laser beam emitted from the laser oscillator 7.

Therefore, the fitting portion 3 is composed of the opening edge of the rectangular case 1 (the inner peripheral edge of the opening) and the outer peripheral edge of the cover plate 2. The fitting part 3 has a square ring shape composed of four side parts 31 made of straight lines and corner parts 32 having a predetermined radius of curvature (see FIG. 1). Hereinafter, the welding process will be described in detail. While the laser irradiation position is moved along the fitting portion 3 from the predetermined welding start portion on the fitting portion 3, the pulse laser light is sequentially output to perform welding, and the sealing is completed.

As shown in FIG. 1, the welding method of this embodiment is characterized in that the locus of the spot center of the laser beam formed by the control of the X and Y tables 6 (in this case, the spot center positions of the spots are connected). This means that the radius of curvature of the corner portion of the welding path W, which means a line), is set smaller than the radius of curvature of the corner portion 32 of the fitting portion 3. That is,
The welding path W is set outside the corner 32 of the fitting portion 3. By doing so, even if the deepest point of the melted region is displaced to the inner peripheral side from the welding path W at the corner of the fitting portion due to the above-mentioned reason, and the deepest point becomes deep, the solid line in FIG. As shown in the drawing, the deepest point is shifted to the side of the rectangular case 1, so that it is possible to prevent the spatter due to welding from scattering inside.

(Embodiment 2) Another embodiment of the method for manufacturing a prismatic battery of the present invention will be described with reference to FIG. The welding method of this embodiment differs from the welding method of Embodiment 1 only in the following points. That is, as shown in FIG. 3, the characteristic of the welding method of the present embodiment is that the corner of the welding path W means the locus of the spot center of the laser beam (in this case, it becomes a line connecting the spot center positions of the spots). The radius of curvature of the part is the corner 32 of the fitting part 3.
Is set in accordance with the radius of curvature of the fitting portion 3, and the laser output per pulse when welding the corner portion 32 of the fitting portion 3 is controlled by the laser oscillator 7 to be 1 pulse when welding the side portion 31 of the fitting portion 3. It is about 5% less than the laser output per hit. By doing so, the deepest point of the melted region is indicated by the solid line in FIG.
It becomes shallower than ax. Therefore, the penetration amount becomes excessive at the corner portion 32 of the fitting portion 3 which is a defect in the conventional constant energy irradiation method, and the spatter of the molten liquid is scattered inside the rectangular case 1 or a minute crack remains in the trace of the spatter. However, this can solve the problem that electrolyte leakage and internal short circuit may occur. In addition,
In this embodiment, the laser beam scanning speed and the laser pulse emission rate per unit time are made equal at the corner portion 32 and the side portion 31 of the fitting portion 3.

(Embodiment 3) Another embodiment of the method for manufacturing a prismatic battery of the present invention will be described with reference to FIG. The welding method of this example is different from Example 2 only in the following points. That is, as shown in FIG. 3, the characteristic of the welding method of the present embodiment is that the corner of the welding path W means the locus of the spot center of the laser beam (in this case, it becomes a line connecting the spot center positions of the spots). The radius of curvature of the part is the corner 32 of the fitting part 3.
It is set in accordance with the radius of curvature of the same as in the second embodiment, but the laser beam scanning speed when welding the corner 32 of the fitting part 3 by the control of the X and Y table 6 is set to the fitting part. Three
It is about 10% higher than the laser beam scanning speed when welding the side portion 31 of the. By doing so, the deepest point of the melted region becomes shallower than the deepest point dmax shown by the solid line in FIG. 4 at the corner portion 32 of the fitting portion 3, especially on the inner peripheral side of the melted region, for the reason described above. Therefore, the melting amount becomes excessive at the corner 32 of the fitting portion 3, which is a drawback of the conventional constant energy irradiation method, and the spatter of the molten liquid scatters inside the rectangular case 1 or minute cracks remain in the trace of the spatter. However, this can solve the problem that electrolyte leakage and internal short circuit may occur. In this embodiment, the output per pulse of the laser beam and the laser pulse emission rate per unit time are made equal in the corner portion 32 and the side portion 31 of the fitting portion 3.

(Embodiment 4) Another embodiment of the method for manufacturing a prismatic battery of the present invention will be described with reference to FIG. The welding method of this embodiment is different from the welding method of Embodiment 3 only in the following points. That is, as shown in FIG. 3, the characteristic of the welding method of the present embodiment is that the corner of the welding path W means the locus of the spot center of the laser beam (in this case, it becomes a line connecting the spot center positions of the spots). The radius of curvature of the part is the corner 32 of the fitting part 3.
Although it is set in accordance with the radius of curvature of the same as in the second and third embodiments, the laser pulse firing rate per unit time when welding the corner portion 32 of the fitting portion 3 is set to the fitting portion 3. Side 3
It is about 10% less than the laser pulse firing rate per unit time when welding No. 1. By doing so, the same effects as those of the second and third embodiments can be obtained. In this embodiment, the output per pulse of the laser beam and the laser beam scanning speed are made equal at the corner portion 32 and the side portion 31 of the fitting portion 3.

(Fifth Embodiment) Incidentally, the above-mentioned second to fourth embodiments.
Then, the output per pulse of the laser beam or the laser beam scanning speed or the laser pulse emission rate per unit time is stepped from the moment when the side portion 31 of the fitting portion 3 moves to the corner portion 32 of the fitting portion 3. However, after the transition from the side portion 31 of the fitting portion 3 to the corner portion 32 of the fitting portion 3, the value of the corner portion 32 of the fitting portion 3 is gradually changed, and the fitting portion 3 The value of the corner 32 is gradually changed also when returning from the corner 32 to the side 31.

By doing so, the effects of the above-described embodiment can be realized more smoothly. (Embodiment 6) In this embodiment, the reduction of the radius of curvature of the welding path W of Embodiment 1 and any one of Embodiments 2 to 4 described above are carried out at the same time. In this way, in the corner portion 32 of the fitting portion 3, the deepest point of the melted region can be matched with the fitting portion 3, and the depth of this deepest point can be the side portion 31.
The depth of the deepest point of can be matched.

The test results will be described below. Square case 1
Is height 34mm, width 8.5mm, height 48mm, corner 32
Has a radius of curvature of 0.5 mm, the rectangular case 1 and the cover plate 2 have a wall thickness of 0.4 mm, the side has a pulse density of 10 pieces / mm, the side has a pulse energy of 2.4 J, and the side has a laser beam. The scanning speed was 10 mm / sec, the diameter of the melting area by one pulse was about 0.7 mm, welding was performed, and a polypropylene resin plate was joined to one surface inside the lid plate 2, and the spatter appeared on this polypropylene resin plate. Was investigated for the traces and thermal effects. In addition, the sealed battery was left for 90 days with the welded part facing downward, and the leakage of the electrolytic solution was examined.

(Test 1) As a test of Example 1, the radius of curvature of the welding path W at the corner 32 of the fitting portion 3 is 0.35.
mm, and the laser irradiation condition of the side portion 31 is set to the fitting portion 3
Welding was also performed by applying it to the corner portion 32. (Test 2) As the test of Example 2, the corner 32 of the fitting part 3
The radius of curvature of the welding path W at 0.5 is set to 0.5 mm so that the welding path W and the fitting portion 3 are aligned, and the energy per pulse at the corner 32 of the fitting portion 3 is set to the side portion 31 of the fitting portion 3.
The energy per pulse was reduced by 5%, and other than that, the laser irradiation condition of the side portion 31 was applied to the corner portion 32 of the fitting portion 3 to perform welding.

(Test 3) As a test of Example 3, the radius of curvature of the welding path W was 0.35 mm, the laser beam scanning speed at the corner 32 was 11 mm / sec, and the side 31 was.
Laser beam scanning speed at 10 mm / sec,
Other than that, the laser irradiation condition of the side portion 31 is set to the fitting portion 3
Welding was also performed by applying it to the corner portion 32.

(Comparative Example) As a comparative example, the radius of curvature of the welding path W at the corner portion 32 of the fitting portion 3 is set to 0.5 mm so that the welding path W and the fitting portion 3 are aligned with each other and the laser of the side portion 31 is used. Welding was performed by applying all the irradiation conditions to the corner portions 32 of the fitting portion 3. The results of these tests are shown in Table 1. The test was carried out for 50 samples each.

[0031]

[Table 1] Next, a specific example of laser spot control will be described below with reference to a flowchart.

As a pulse type laser welding machine,
Using what is schematically shown in FIG. 6, the controller 8 follows the built-in program so that the center of the laser spot (focal point of the objective lens 70) moves sequentially along the fitting part of the battery assembly 100, X, It is assumed that the Y table 6 is controlled. Since such control itself is not the gist of the present invention, its detailed description is omitted.

(Control Example 1) A first control example embodying the control of the second embodiment will be described with reference to the flowchart of FIG. First, the built-in program determines whether the laser spot (focal position of the objective lens 70) is currently traveling on the linear side portion 31 (whether the corner portion 32 is traveling) by controlling the X and Y tables 6. Based on (10
0), set the set value of the laser pulse output to a predetermined high value PH if the side part 31 is running (103), otherwise set it to a predetermined low value if the corner part 32 is running. The value PL is set (102), and it is judged whether or not the welding is completed (110). If not completed, the process returns to step 100, and when completed, the routine is completed.

(Control Example 2) A second control example embodying the control of the third embodiment will be described with reference to the flowchart of FIG. First, the control of the X and Y tables 6 determines whether the laser spot is currently traveling on the side portion 31 (whether or not it is traveling on the corner portion 32) based on a built-in program (100). If the vehicle is traveling, the set value of the scanning speed of the laser beam, that is, the moving speed along the fitting portion of the X and Y table 6 is set to a predetermined low value VL (1
05), if it is traveling on the corner 32, set it to a predetermined high value V
It is set to H (104), and it is judged whether or not welding is completed (110). If not completed, step 10
The routine returns to 0 and ends the routine when completed.

(Control Example 3) A third control example embodying the control of the fifth embodiment will be described with reference to the flowchart of FIG. First, the control of the X and Y tables 6 determines whether the laser spot is currently traveling on the side portion 31 (whether or not it is traveling on the corner portion 32) based on a built-in program (100). When the vehicle is traveling, the set value of the scanning locus of the laser beam, that is, the moving path of the X, Y table 6 is set along the side portion 31 of the fitting portion 3 (10
7) If the vehicle is traveling on the corner 32, the offset amount from the corner 32 of the fitting part 3 is read from the ROM built-in table based on the current traveling position (101), and only the read offset amount is fitted. It is set so as to be offset by a predetermined distance from the corner 32 of the part 3 (106), and it is determined whether or not the welding is completed (110). If not completed, the process returns to step 100, and when completed, Exit the routine.

In the table, the traveling position when traveling in a curved manner while approaching the corner 32 of the fitting portion 3 and the offset amount which is the shortest distance between the traveling position and the corner 32. It remembers the relationship with. In this example,
In order to prevent the travel route (travel locus) from jumping sharply, the offset amount gradually increases from 0 when it is separated from the side portion 31, and the offset amount is 0 when it gradually approaches the next side portion 31. It is set to gradually decrease toward. As a result, it becomes possible to smoothly offset the traveling locus.

(Control Example 4) A fourth control example embodying the control of the fourth embodiment will be described with reference to the flowchart of FIG. First, by controlling the X and Y tables 6, the X and Y tables 6 are controlled so that the center of the laser spot (the focal position of the objective lens 70) sequentially moves at a constant speed along the fitting portion of the battery assembly 100. Keep it. Since such control itself is not the gist of the present invention, its detailed description is omitted.

First, the laser spot is currently on the side 31.
Whether you are traveling (whether you are not traveling the corner 32)
Is determined based on a built-in program (100), the laser pulse emission interval is set to a predetermined short interval if the side portion 31 is traveling (109), and if the corner portion 32 is traveling, Is set to a predetermined long interval (108), and it is determined whether or not the welding is completed (110). If not completed, the process returns to step 100, and when completed, the routine is completed.

(Fifth Control Example) A fifth control example embodying the control of the first embodiment will be described with reference to the flowchart of FIG. First, by controlling the X and Y tables 6, it is checked whether or not the vicinity of the corner portion 32 of the fitting portion 3 is currently traveling (scanning) (200). If not, that is, if the vicinity of the side portion 31 is traveling. For example, the laser beam spot center is side 3
The X, Y table 6 is controlled so that the scanning is performed on the upper part of (1)
2) If it is traveling (scanning) in the vicinity of the corner 32 of the fitting part 3, it is checked whether or not the period of traveling in the vicinity of the corner 32 is the initial stage (202). After continuing the last straight running, if it is not the initial stage, the process directly proceeds to step 206.

In step 206, it is checked whether or not it is the end of the period in which the vehicle is currently traveling near the corner 32 (206). If it is the end, the vehicle travels in a straight line on the extension of the side 31 to be traveled thereafter (210). ), Otherwise (neither in the beginning nor in the end) run on an arc of a given radius. Of course, the radius of this arc is set smaller than the radius of the corner 32.

Next, it is judged whether or not all the welding is completed (110). If not completed, the process returns to step 100, and when completed, the routine is completed.

[Brief description of drawings]

FIG. 1 is an explanatory view showing a welding route W as an example of a method for manufacturing a prismatic battery of the present invention.

FIG. 2 is a perspective view showing an example of a rectangular battery container to which the welding method of the present invention is applied.

FIG. 3 is an explanatory view showing a welding route W as another embodiment of the method for manufacturing a prismatic battery of the present invention.

FIG. 4 is a diagram illustrating a vertical cross-section of a welded region at the time of laser melting at the side portion 31 and the corner portion 32 when the corner portion 32 of the fitting portion 3 and the welding path W coincide with each other.

FIG. 5 is a diagram illustrating a vertical cross section of a welded region at a side portion 31 and a corner portion 32 at the time of laser melting when the welding path W is offset from the corner portion 32 of the fitting portion 3 to the outside.

FIG. 6 is a schematic perspective view of a pulse type laser welding machine.

7 is a partial plan view showing the shape of a penetration region (welded part) when the corners of the pulse type laser welding machine shown in FIG. 6 are welded along the fitting part 3. FIG.

FIG. 8 is a flowchart showing an example of irradiation control.

FIG. 9 is a flowchart showing an example of irradiation control.

FIG. 10 is a flowchart showing an example of irradiation control.

FIG. 11 is a flowchart showing an example of irradiation control.

FIG. 12 is a flowchart showing an example of irradiation control.

[Explanation of symbols]

Reference numeral 1 is a rectangular case (metal case in the present invention), and 2 is a cover plate.

Claims (10)

[Claims] 1. A lid plate made of a metal plate is fitted into a rectangular opening formed at one end of a metal case, which is composed of straight sides and corners having a predetermined radius of curvature, and the fitting portion is laser-welded. In a method of manufacturing a prismatic battery for forming a container of a prismatic battery, the corner of the fitting part is welded with a radius of curvature smaller than that of the corner of the fitting part. Production method. 2. A lid plate made of a metal plate is fitted into a rectangular opening formed at one end of a metal case, which is composed of a straight side portion and a corner portion having a predetermined radius of curvature, and the fitting portion is laser-welded. In the method of manufacturing a prismatic battery for forming a prismatic battery container, the laser output at the time of welding the corner of the fitting portion is lower than the laser output at the time of welding the side portion of the fitting portion. Method for manufacturing prismatic battery. 3. A lid plate made of a metal plate is fitted into a rectangular opening formed at one end of a metal case, which is composed of straight sides and corners having a predetermined radius of curvature, and the fitting portion is laser-welded. In the method of manufacturing a prismatic battery for forming a prismatic battery container, the laser beam scanning speed during corner welding of the fitting portion is higher than the laser beam scanning speed during side welding of the fitting portion. And a method for manufacturing a prismatic battery. 4. A method of manufacturing a prismatic battery, wherein a metal case having a rectangular cross section having a battery element inside and a metal cover plate fitted in an opening of the case to close the case are joined by laser welding. In the method, a planar form of the fitting portion is formed into a linear shape including a linear side portion and a curved corner portion that joins a pair of adjacent side portions, and a laser beam is used when welding the corner portion. The method of manufacturing a prismatic battery, wherein the spot center of the laser beam is offset to the outside of the corner portion by a predetermined dimension, and laser welding is performed by aligning the spot center of the laser beam with the side portion when welding the side portion. . 5. A manufacturing method of a prismatic battery, wherein a metal case having a prismatic cross section having a battery element inside and a metal cover plate fitted into an opening of the case to close the case are joined by laser welding. In the method, the planar shape of the fitting portion is formed in a linear shape including a linear side portion and a curved corner portion connecting a pair of adjacent side portions, and a scanning speed of the laser beam is set to a predetermined value. A method for manufacturing a prismatic battery, wherein the speed is maintained, and the laser pulse firing time interval during welding of the corner portion is longer than the laser pulse firing time interval during welding of the side portion. 6. A battery assembly including the case and the cover plate fitted in the opening of the case is mounted on a mounting surface of an XY table, and the irradiation position of the laser beam is in front. A laser oscillator is arranged above the table so as to be fixed at a predetermined position on the placing surface, and the laser is driven by driving the table in the X coordinate direction and the Y coordinate direction which are parallel to the placing surface and orthogonal to each other. By controlling the output of the laser oscillator while moving the beam spot, the laser output of the laser oscillator when irradiating the corner of the laser beam spot, the laser when irradiating the side The method for welding a rectangular battery container according to claim 2, wherein the output is reduced compared to the output. 7. A battery assembly including the case and the cover plate fitted in the opening of the case is mounted on a mounting surface of an XY table, and the irradiation position of the laser beam is in front. A laser oscillator is arranged above the table so as to be fixed at a predetermined position on the placing surface, and the laser is driven by driving the table in the X coordinate direction and the Y coordinate direction which are parallel to the placing surface and orthogonal to each other. The scanning speed of the spot of the beam is controlled so that the scanning speed of irradiating the corner of the laser beam spot is higher than the scanning speed of irradiating the side. Welding method for rectangular battery container. 8. A battery assembly including the case and the cover plate fitted in the opening of the case is mounted on a mounting surface of an XY table, and the irradiation position of the laser beam is in front. A laser oscillator is arranged above the table so as to be fixed at a predetermined position on the placing surface, and the laser is driven by driving the table in the X coordinate direction and the Y coordinate direction which are parallel to the placing surface and orthogonal to each other. By moving the spot of the beam, the center of the spot of the laser beam is offset to the outside of the corner by a predetermined dimension when welding the corner, and the center of the laser spot is welded to the side when welding the side. The method for manufacturing a prismatic battery according to claim 4, wherein laser welding is performed in accordance with the above. 9. A battery assembly including the case and the cover plate fitted in the opening of the case is mounted on a mounting surface of an XY table, and the irradiation position of the laser beam is in front. A laser oscillator is arranged above the table so as to be fixed at a predetermined position on the placing surface, and the laser is driven by driving the table in the X coordinate direction and the Y coordinate direction which are parallel to the placing surface and orthogonal to each other. By controlling the firing interval of the laser pulse while moving the beam spot, the firing interval when irradiating the corner portion with the laser beam spot is more than the firing interval when irradiating the side portion. The method for welding a container of a prismatic battery according to claim 5, which is also extended. 10. The method for manufacturing a prismatic battery according to claim 1, wherein the lid plate is fitted into the opening of the case by press fitting.