JP2785902B2 - Material for forming battery can and battery can using the material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to DI (Drawing and I
The present invention relates to a material for forming a drawn battery can, and a battery can formed from the formed material.

[0002]

2. Description of the Related Art Recently, as a method for manufacturing a cylindrical battery can having one end closed surface and the other end opening, a DI drawing method as shown in FIG. 5 has recently been developed. In the DI drawing method, when the base material M is punched from the sheet steel sheet S, the punching is performed while drawing as a shallow cylindrical cup having a bottom wall M-1 and a peripheral wall M-2. This is a process of forming into a cylindrical shape having a required depth and diameter by deep drawing.

When the above-mentioned DI drawing is used, only the peripheral wall is stretched in the step of deep drawing the cup. For example, when the thickness of the bottom wall is 0.4 mm and the thickness of the peripheral wall is 0.4 mm.
It can be squeezed down to 15mm, and the ironing ratio to the plate thickness
The (decrease rate) can be slightly more than twice the conventional value. As described above, when the peripheral wall is made thin, the volume of the hollow portion becomes large, and the amount of the filler is increased, so that the battery characteristics can be improved. In addition, a processing step includes a cupping step of punching a cup from a sheet steel sheet as a can forming material, and a D step of drawing.
Since only two steps, one step of the I step, are required, the number of processing steps can be significantly reduced and the manufacturing cost can be reduced accordingly.

[0004]

However, the above D
When using the I drawing method, the cupping process and DI
In the process, when the elongation percentage of the can forming material in the vertical, horizontal and oblique directions is not constant, and when the plate thickness is not uniform, as shown in FIG. A so-called earring (ear height difference) that causes a difference easily occurs. This earring occurs during the cupping process and is further promoted during the DI process.

Specifically, in the steel sheet shown in FIG. 7, when a strain equal to or less than the elongation limit is applied uniformly in the rolling direction (longitudinal direction X), the sheet width is set to W _x0 , W _x , and the sheet thickness is set to t _x0. , t _x , the anisotropy of deformation (rankhorse value r _x ) with respect to the force in the rolling direction X is represented by the following equation (1).

R _x = ln (W _x / W _x0 ) / ln (t _x / t _xo ) (1)

Rankhorde values r _y , r _{z for} a force in the horizontal direction Y and a force in the oblique direction Z forming an angle of 45 degrees with the vertical direction X.
Is also expressed in the same manner as the above formula (1), and the anisotropy (in-plane anisotropy Δr) between the vertical direction X, the horizontal direction Y and the oblique direction Z is expressed by the following formula (2). . _{△ r = (r x + r} y) / 2-r z ... (2)

From the experiments conducted by the present applicant, it has been found that the earring occurrence rate differs depending on the above-mentioned rank horde value r and the in-plane anisotropy Δr. That is, if the above-mentioned rank horde value r is not more than the required value, earring is likely to occur. Also, if the absolute value of △ r is (+) or (−), the earring occurrence rate increases as the absolute value increases, 90 at the open end
Crests protruding at an interval are generated, so-called four ears are formed. When the absolute value is on the (+) side, 0 degree and 9 with respect to the X direction
Four ears are generated at 0 degrees, and when the absolute value is on the (-) side, four ears are generated at 45 degrees with respect to the X direction. As the absolute value approaches 0, six ears are generated and earrings are generated. Being held down.

When the above-mentioned earring occurs, as shown in FIG. 6, the highest position of the earring is point A, the lowest position is point B, and the position for obtaining the necessary battery can is point C. In this case, it is necessary to cut at the lowest point B, but the point B is below the point C and the length of the battery can is insufficient. In order to prevent a portion shorter than the required length from being generated, the cylindrical portion is squeezed so as to have a longer length, and the lowest point B is raised above the point C.
This time, there is a disadvantage that the difference between the point C and the point A at the highest position becomes large, and the material is wasted.

[0010] The above problem can be solved by preventing the occurrence of earrings.
The longitudinal direction (rolling direction) of the can forming material, the longitudinal direction, the lateral direction in the width direction, and the oblique direction are each equal to or greater than a certain rank hod value r.
Is required to approach 0, but it was extremely difficult.

In addition, when the battery can is formed by DI drawing, if the material is not sufficiently ductile, cracks are likely to occur in the bent portion between the bottom wall and the peripheral wall, and if cracks occur, the corrosion resistance deteriorates. was there.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and aims to improve the ductility of a plated steel sheet used as a material for a battery can, thereby preventing cracks and improving the corrosion resistance. Rankhord values r in the longitudinal, lateral, and diagonal directions of the steel sheet are set to be greater than required, and the difference Δr between the rankhord values is made close to 0 to prevent the occurrence of earring at the opening end face during DI drawing. It is intended to be.

[0013]

That is, according to the present invention, a cylindrical battery can having an opening at one end is provided by DI (Drawing and Ironin).
g) a forming material used for forming by drawing,
An object of the present invention is to provide a material for forming a battery can, comprising a nickel plating layer having a granular structure on both front and back surfaces of an Fe steel plate. The lower the carbon content of the Fe steel sheet, the lower the carbon content, the more preferable in terms of drawability.

In the Fe steel sheet provided with the nickel plating layer, a difference Δr between rank-horizontal values r _x , r _y , and r _{z in} the longitudinal, lateral, and oblique directions is ± 0.15 or less. Also the longitudinal direction, transverse and diagonal Rankuhodo values _{(r x, r y, r} z) the average value of a least 1.2. Further, it is preferable that an Fe-Ni diffusion layer is provided between the Fe steel sheet and the nickel plating layer.

The present invention also provides a battery can formed by using the above-mentioned forming material.

Further, the material for forming a battery can is obtained by applying nickel plating to both sides of an unannealed cold-rolled steel sheet and then annealing to change the needle-like (metal) structure of the nickel-plated layer to a granular (metal) structure. At the same time as being transformed into a structure, a Fe-Ni diffusion layer is formed between the plating layers of the cold-rolled steel sheet, and
The metallic structure of Fe is a granular structure.

In the above method, the nickel plating layer is
After applying a thickness of 2 μm to 5 μm, annealing is performed at 600 ° C. to 9
It is preferable to carry out at 00 ° C. for 0.5 to 2 minutes. further,
After the above-mentioned annealing, it is preferable to perform a temper rolling of 0.5 to 2.0%, and to refine the granular structure produced by recrystallization by continuous annealing to increase the toughness.

[0018]

When the nickel-plated unannealed cold-rolled steel sheet is nickel-plated, the soft nickel-plated metal structure that is electrodeposited on the front and back surfaces of the Fe steel sheet has a needle-like structure. Cracks sometimes occur in the bent portion, resulting in poor corrosion resistance. On the other hand, since the needle-like structure is transformed into a granular structure by performing continuous annealing after plating, ductility is improved, cracks are not formed in a bent portion during processing, and corrosion resistance can be improved.

Further, by the continuous annealing after the plating, an Fe—Ni diffusion layer is formed between the steel sheet and the plating layer, and the Fe metal structure is recrystallized to form a granular structure. As described above, when the metal structure becomes a granular structure by recrystallization, the above-mentioned rank horde value r is 1.2 or more on average, and the in-plane anisotropy Δr, which is the difference between the rank horse values r, is set to ± 0.15 or less, and Generation can be greatly reduced, and the height of the opening end of the cylindrical portion can be made substantially uniform.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings. 1 and 2 show a battery can 1 formed from a nickel-plated steel sheet as a forming material according to the present invention,
It is a deep-bottom cylindrical shape having an upper end opening provided with a bottom wall 2 and a peripheral wall 3. A positive contact 2a is formed on the bottom wall 2 of the can 1, and after filling the hollow portion surrounded by the bottom wall 2 and the peripheral wall 3 with a filler (not shown), a negative contact is inserted into the upper end opening. The battery is assembled by covering and fixing the lid (not shown) formed. The positive contact and the negative contact may be provided on any side of the lid attached to the bottom wall and the opening.

The nickel-plated steel sheet for forming the battery can 1 is manufactured in the order shown in FIG. That is, as a first step, 2 μm
A nickel plating layer having a thickness of about 5 μm is provided by electroplating. In the second step, in a gas atmosphere,
Continuous annealing is performed at 900 ° C. for 0.5 to 2.0 minutes. still,
The temperature and time are set such that the thinner the nickel plating layer applied in the first step, the lower the temperature and the shorter the time, while the thicker the thickness, the higher the temperature and the longer the time. I have. By this annealing, the entire metallographic structure of the nickel plating layer electrodeposited and deposited on the surface of the unannealed cold-rolled steel sheet 5 in the first step was changed from the needle-like structure shown in FIG.
Transform to the granular structure shown in (B). At the same time, an Fe—Ni diffusion layer is formed between the steel sheet 5 and the plating layer, and the steel sheet 5 is recrystallized to make the metal structure granular. In the third step, temper rolling is performed at a rolling rate of 0.5 to 2.0%.

In the first to third steps, a material 10 for forming a battery can is manufactured. As shown in the cross-sectional view of FIG.
1 has Fe-Ni diffusion layers 12A, 12B and nickel plating layers 13A, 13B having a granular structure on both sides.
Next, the can-forming material 10 made of the nickel-plated steel sheet is formed into a battery can 1 having the shape shown in FIGS. 1 and 2 by the DI drawing method shown in FIG.

In the DI drawing, it is important that the metal structure of the nickel plating layer is changed from the needle-like structure shown in FIG. 4A to the granular metal structure shown in FIG. It is an organization. As described above, when the needle-shaped structure of the nickel plating layer is a granular structure, the ductility of the nickel plating layer becomes good, cracks are less likely to occur in a bent portion during processing into a battery can, and corrosion resistance can be improved. it can. Further, by making the metal structure of the substrate 11 and the granular structure, the vertical direction (rolling direction) X of the rolled steel sheet shown in FIG. 7, the horizontal direction Y, each Rankuhodo value r _x in an oblique direction Z, r _y, r _z Is 1.2 or more on average, and the in-plane anisotropy Δr, which is the difference between these rank-hord values r, is ± 0.15.
You can do the following:

In the continuous annealing in the second step, when annealing is performed at a high temperature for a long time, the metal structure grows rapidly, and the metal structure in the surface layer becomes coarse grains (mixed grains). May differ from the part.
Therefore, in the above continuous annealing, the needle-shaped metal structure is transformed into a granular metal structure in the nickel plating layer, but the F
In e, the heating temperature and the heating time are set at 600 ° C. to 900 ° C. as described above so that the metal structure does not grow and become coarse grains.
The heating temperature and the heating time are set within the above range according to the nickel plating layer thickness of 2 μm to 5 μm, limited to a very short time range of 0.5 to 2.0 minutes in the range of 0 ° C. ing. When continuous annealing is performed with such settings, the needle-shaped metal structure of the nickel plating layer can be transformed into a granular structure having a diameter of approximately 1 μm to 5 μm.

Further, after the continuous annealing in the second step, a temper rolling of 0.5 to 2.0% is performed in the third step, so that the crystal grains of the granular metal structure can be either on the surface side or the inside side. In this case, a crystal grain having a particle size of about 0.9 specified in JIS-G-0552 is formed.

As described above, in the nickel-plated steel sheet 10 manufactured in the above process, the nickel-plated layer 13A,
The metal structure of 13B is a granular structure, and furthermore, since the surface layer portion and the inside of the substrate 11 have a substantially uniform particle size and are small particles, the elongation in the vertical direction X, the horizontal direction Y, and the oblique direction Z,
That is, the width deformation degree in the X direction / the thickness deformation degree in the X direction, the width deformation degree in the Y direction / the thickness deformation degree in the Y direction, the width deformation degree in the Z direction /
Each is a Z direction thickness deformation degree Rankuhodo values r _x, r _y,
r _z can be as high as 1.2 or more on average, and the in-plane anisotropy Δr, which is the difference between these rank-hord values r, can be made close to 0, ± 0.15 or less. Thus, the in-plane anisotropy △
By making r smaller, it is possible to prevent the occurrence of earring at the opening end of the cylindrical can at the time of drawing, and to improve drawability.

The following experimental data demonstrate that the nickel plating layers 13A and 13B transformed into a granular structure by annealing have excellent ductility, so that cracks are less likely to be formed in a bent portion during processing and have excellent corrosion resistance. Was done.

[0028]

[Experimental Example 1] It was measured how the metallographic structure and the elongation of the deposited nickel plating layer were changed by annealing. Incidentally, even if the unannealed cold-rolled steel sheet is annealed after being subjected to nickel plating, it is difficult to observe and measure the metallographic structure and mechanical properties of only the nickel plated layer. Annealing was performed using the foil, the metal structure thereof was observed, and mechanical properties were measured. That is, nickel foil (electrical deposition) 49 μm to 54 μm
(Vertical 250mm, horizontal 250mm, thickness 50μ
m) is 300 mm in the vertical direction, 300 mm in the horizontal direction, and height 2
The sample was placed in a 50 mm experimental furnace and annealed in a gas atmosphere of 75% hydrogen and 25% nitrogen at a heating temperature of 650 ° C. for a heating time of 1 minute.

As shown in Table 1 below, the results of the above experiments show that the annealing reduced the tensile force (TS), increased the elongation (EL) and increased the metal structure to a granular structure.

[0030]

[Table 1] TS (kgf / mm) EL. (%) Before structure annealing 55.6 7 After needle-shaped metal structure annealing 30.9 14 Granular metal structure (1-5 μm)

[0031]

[Experimental example 2] The nickel-plated steel sheet of the above embodiment was manufactured, and its tensile force, elongation, metal structure of nickel-plated layer,
And the corrosion resistance test of the bending surface according to JIS standard (JIS-Z-
2371). A nickel-plated steel sheet was manufactured by applying nickel plating to both sides of the unannealed cold-rolled steel sheet at a thickness of 3.5 μm and continuously annealing at 650 ° C. for 1 minute. The tensile strength, elongation, surface hardness (HV), and metal structure of the nickel plating layer of the nickel-plated steel sheet were as shown in Table 2 below. Further, the nickel-plated steel sheet was bent at 90 degrees (R1), salt water was sprayed on the bent surface of the bent portion, and the limit time was measured based on the JIS standard.

[0032]

[Table 2] T.S. HV structure Salt spraying time r △ r Before annealing 76 3 200 Needle-like 1 hour 1.0 + After 0.233 annealing 33 39 105 Granular 8 hours 1.3 +0.005 * HV (load 1 kg) * r Rankhord value * △ r In-plane anisotropy

As shown in Table 2 above, by forming the granular structure by annealing the nickel plating layer, the limit time can be increased eight times as compared with that before annealing, that is, as compared with the case without annealing. It was confirmed that it had high corrosion resistance.

Further, batch annealing may be used instead of continuous annealing in the second step. However, when the nickel-plated steel sheet has a coil shape, continuous annealing is preferable.
Further, it is preferable to form a battery can by DI drawing from the nickel-plated steel plate having the above structure, and then coat a conductive material on an inner peripheral surface thereof to improve battery characteristics.

The present invention is not limited to the above embodiment. After the temper rolling in the third step, the outer surface side is subjected to hard nickel plating or bright nickel plating by drawing to obtain corrosion resistance and appearance. The property may be further improved.

[0036]

As is apparent from the above description, in the present invention, the metallographic structure of the nickel plating layers on both the front and back surfaces of a nickel-plated steel sheet formed by DI drawing processing to form a cylindrical battery can having an upper end opening. Has a constant granular structure, so that the ductility can be increased and the occurrence of cracks in the bent portion during processing can be reduced. Thus, the corrosion resistance can be improved by reducing the occurrence of cracks.

Further, by continuous annealing after plating, the metallographic structure of the steel sheet becomes a granular structure, so that the elongation in the longitudinal, lateral and oblique directions can be made larger than required values and in each of these directions. Since the difference in elongation is less than or equal to a certain value, workability during DI drawing is improved and earrings can be prevented from occurring at the opening edge. Therefore, the yield of the material can be improved, and the cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a front view of a battery can according to the present invention.

FIG. 2 is a partially enlarged sectional view of FIG.

FIG. 3 is a flowchart showing a method for producing a material for forming a battery can according to the present invention.

FIG. 4A is a schematic sectional view showing a needle-like structure of a nickel plating layer before annealing, and FIG. 4B is a schematic sectional view showing a granular structure of a nickel plating layer after annealing.

FIG. 5 is a view showing a method for manufacturing a battery can by a DI drawing method.

FIG. 6 is a perspective view showing a problem when a can is manufactured by the DI drawing method.

FIG. 7 is a drawing showing an elongation direction in a material for a battery can.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Battery can 2 Bottom wall 3 Perimeter wall 11 Substrate 12A, 12B Fe-Ni diffusion layer 13A, 13B Nickel plating layer 10 Material for forming battery can

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-6-2104 (JP, A) JP-A-2-129395 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C25D 5/00-7/12 C23C 10/28 H01M 2/02

Claims (5)

(57) [Claims] 1. A cylindrical battery can having one end opening is DI
(Drawing and Iron-ing) A forming material used for forming by drawing, comprising a nickel plated layer having a granular structure on both front and back surfaces of the Fe steel sheet, and the Fe steel sheet provided with the nickel plated layer has a vertical length. , Lateral and oblique rankhord values r _x ,
A material for forming a battery can, wherein a difference Δr between r _y and r _z is ± 0.15 or less. 2. A cylindrical battery can having one end opening is DI
(Drawing and Iron-ing) A forming material used for forming by drawing, comprising a nickel plated layer having a granular structure on both front and back surfaces of the Fe steel sheet, and the Fe steel sheet provided with the nickel plated layer has a longitudinal direction. , The horizontal and diagonal rank-hord values (r _x ,
r _y, the material for forming the battery can, wherein the average value of r _z) is 1.2 or more. 3. A cylindrical battery can having one end opening is DI
(Drawing and Iron-ing) A forming material used for forming by drawing, comprising a nickel plated layer having a granular structure on both front and back surfaces of the Fe steel sheet, and the Fe steel sheet provided with the nickel plated layer has a vertical length. , Lateral and oblique rankhord values r _x ,
The difference Δr between r _y and r _z is ± 0.15 or less, and the average of the above-mentioned rank-horizontal values (r _x , r _y , r _z ) in the vertical, horizontal, and oblique directions is 1.2 or more. A material for forming a battery can, characterized in that: 4. The material for forming a battery can according to claim 1, further comprising an Fe—Ni diffusion layer between the Fe steel sheet and the nickel plating layer. 5. A battery can formed by DI drawing using the forming material according to any one of claims 1 to 4.