JPH0749296B2 - Method for manufacturing thinned nickel-plated metal can for battery - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the production of metal cans (hereinafter referred to as battery cans) used as terminals and containers for filling electromotive force generating elements in alkaline manganese batteries, nickel-cadmium batteries, lithium batteries and the like. The present invention relates to a method, and more particularly to a method for manufacturing a thinned nickel-plated metal can for batteries.

[0002]

2. Description of the Related Art Conventionally, battery cans for batteries such as alkaline manganese batteries, nickel cadmium batteries and lithium batteries are
An iron plate was manufactured by drawing, and then an iron can was nickel-plated by a barrel plating method. Also,
It is also proposed that an iron plate, which has been nickel-plated in advance, is manufactured by a multistage drawing method so that the thickness of the cylindrical side portion is thinner than the thickness of the can bottom portion (Japanese Patent Laid-Open No. 60-18005).
No. 8). Japanese Unexamined Patent Publication No. 60-180058 proposes a battery in which the inner diameter and the inner volume of the iron can are increased, and a larger amount of power generating elements can be internally filled than in the conventional case, and which is excellent in battery capacity and weight efficiency. Since the conventional iron plate or nickel-plated steel plate usually has a thickness of about 0.25 mm,
It could also be manufactured by a conventional deep drawing method such as a multi-stage deep drawing method. However, recently, a plate material having a thinner plate thickness and higher tensile strength than the conventional one has been developed, and an attempt has been made to apply the plate material to a can for a battery. However, if such a plate material is directly applied to the conventional forming method, since it is a high tensile strength and high hardness steel plate, it becomes difficult for the plate material in the circumferential direction to flow into the tool during forming, and wrinkles occur on the side wall of the can during forming. However, there is a problem that the plate material is broken. Furthermore, as the can diameter becomes smaller, the effective wrinkle holding area of the die decreases, so the wrinkle holding force must be increased, which in turn increases the punching force, which in turn leads to a vicious cycle of breaking the plate material. There was also a problem. Further, the nickel-plated steel sheet has a large friction with the tool, and there is a problem in forming difficulty.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and when forming a metal can for a battery using a recently developed ultrathin high tensile strength metal plate, The purpose is to facilitate the inflow of blanks in the circumferential direction. Also, when molding a metal can with a small diameter,
An object of the present invention is to provide a method for manufacturing a thin-walled nickel-plated metal can for a battery, which solves the problems of wrinkling of the cup side wall portion and breakage of the base plate and can increase the internal volume of the battery.

[0004]

In order to achieve the above-mentioned object, the present invention is to form a nickel-plated metal plate into a front draw cup, and to arrange the front draw cup and a ring-shaped pressing member thereunder. A holding die and a re-drawing punch and re-drawing die that are provided so as to reciprocate in the holding member so as to be coaxial with the holding member and the re-drawing die. In a method for forming a deep drawing cup having a small diameter in multiple steps, the wrinkle holding surface angle of at least one set of the pressing member and the wrinkle holding taper surface angle of the redrawing die are respectively 20 degrees to 45 degrees with respect to the horizontal plane. A method for manufacturing a thin-walled nickel-plated metal can for a battery, characterized in that the side wall of the front-drawing cup is subjected to tensile bending using a pressing member and a redrawing die, and A nickel-plated metal plate is formed into a front drawing cup, and the front drawing cup is held by a ring-shaped holding member and a redrawing die arranged below it so that it is coaxial with these holding members and redrawing dies. And in the redrawing punch and the redrawing die provided to reciprocate in the pressing member, in a method of multi-step forming a deep drawing cup having a smaller diameter than the front drawing cup,
Using a pressing member and a redrawing die in which the wrinkle holding surface angle of at least one set of the pressing member and the wrinkle holding taper surface angle of the redrawing die are respectively 20 degrees to 45 degrees with respect to the horizontal plane, the front drawing cup side wall portion is used. Is subjected to a tensile bending process, and in at least one redrawing step, the reduction rate of the thickness of the cup side wall portion is 1 with respect to the thickness of the side wall portion of the pre-drawn cup
A method for producing a thin-walled nickel-plated metal can for a battery, which is characterized by performing ironing processing so as to be 10%.

[0005]

EXAMPLES Examples will be described based on one embodiment of the present invention. Base plate In the present invention, the base plate is a so-called ultra-thin steel plate with a plate thickness of 0.2 to 0.165 mm and a tensile strength of 65 to 73 kg.
A nickel-plated steel sheet with a f / mm ^{2 level} is used. This is because, in order to increase the internal volume of the battery, an attempt is made to apply to the battery can a plate that is thinner than before. However, it is also possible to use a raw plate of about 0.25 mm which has been conventionally used as a material for cans. The nickel-plated steel sheet has been widely applied as a material for battery cans, and the present invention is not a conventional method of forming an iron plate or a method of forming a tin-plated steel sheet that is widely used as a beverage can. The present invention provides a method for molding a base plate, which has been subjected to the above, into a battery can. The present invention can be applied even if nickel plating is partially or wholly diffused with the iron plate as the original plate.

Description of Can Manufacturing Method FIG. 4 is a schematic view showing a manufacturing process of the thin-walled nickel-plated metal can of the present invention. First, a blank is stamped and subsequently a shallow drawn cup is formed. Then, this shallow drawing cup is mounted on a tool, and multi-step redrawing is repeated to sequentially form deep cups. In this case, separate die punch tool tools are used. Although FIG. 4 illustrates the case where all the steps are 5, the number of steps can be reduced or increased depending on the tool shape. Next, the manufacturing method of the present invention will be described in detail with reference to FIGS. (1) First Step Punching and Drawing Step First, in the punching step, a disc is punched. Next, a shallow squeezing cup having a bottom portion and a side wall portion having a low height is formed. Usually, the drawing ratio in this step is preferably 1.2 to 1.9. The drawing ratio is (base plate diameter) /
(Shallow squeeze can diameter) value.

(2) Second to Fourth Steps Redrawing Step In the present invention, the shallow drawing cup obtained in the above step is redrawn, and the redrawing cup has a smaller diameter and a higher height than the shallow drawing cup. To mold. The side wall portion of the redrawing cup is stretched and bent during the redrawing process, and the thickness of the side wall portion is smaller than the thickness of the front drawing cup. The front drawing cup 20 formed from a raw plate includes a ring-shaped pressing member 11 inserted in the cup and a re-drawing die 12 located below the pressing member 11.
And held in. A redrawing punch 13 is provided coaxially with the holding member 11 and the redrawing die 12 so as to be able to reciprocate in the holding member 11. The redrawing punch 13 and the redrawing die 12 move relative to each other. Here, the pre-drawing cup means a cup before forming before re-drawing. When redrawing is performed in multiple stages, all cups before processing are called predrawing cups. Next, referring to FIG. 2, details of redrawing will be described. Due to the redrawing process, the side wall portion of the front drawing cup 20 is pressed by the pressing member 1.
1 is bent from the outer peripheral surface through the corner portion 17 in the radial inward direction, passes through a narrow gap set in advance by the wrinkle holding surface 14 of the holding member 11 and the wrinkle holding tapered surface 15, and the working corner portion of the redrawing die 12 16 is bent in the axial direction of the redrawing punch to form a deep drawing cup having a diameter smaller than that of the redrawing cup, and the side wall portion 21 is thinned by tensile bending.

The principle of thinning the cup side wall portion 21 by the tensile bending process will be described in more detail with reference to FIG. In FIG. 3, the front drawing cup 20 reaches a working corner portion 16 of the redrawing die 15 having a radius of curvature of the redrawing die (hereinafter referred to as Rd) and is forcibly bent while being loaded with strong back tension and punch force. . The material reaching the entrance of the die undergoes the following plastic deformation due to the change of Rd and the influence of strong back tension and punch force. That is, the plastic deformation neutral axis position in the blank plate is deviated between the redrawing die inlet portion and the redrawing die outlet portion.
Therefore, at the entrance of the redrawing die, elongation strain occurs on the side opposite to the redrawing die surface, and compressive strain occurs on the redrawing die surface side. On the other hand, at the outlet of the redraw die, elongation strain occurs on the redraw die surface side, and compressive strain occurs on the side opposite to the redraw die surface. However, the final redrawing die 1
After passing through all the action corners 16 of 5,
The amount of elongation of the cup side wall is almost equal in the plate thickness direction, and no strain remains on the cup side wall. Moreover, the material is thin. That is, the thickness before redrawing is t
If o and the plate thickness after forming is t, then to> t.

Further, in the present invention, in the redrawing process, by providing an angle to the wrinkle holding surface 14 and the wrinkle holding tapered surface 15, the inflow resistance of the blank for redraw drawing is reduced and the pressure of the holding member 11 is increased. We are trying to make it possible. That is, in the present invention, the wrinkle holding surface 14
And the wrinkle pressing taper surface 15 opposed thereto is at an angle of 20 to 45 degrees with respect to the horizontal plane. The reason for this is that the nickel-plated steel plate has a poor slip between the redrawing die 12 and the pressing member 11, and it is necessary to reduce the inflow resistance. This point is different from tin-plated steel sheets and the like having self-lubricating properties. If the can diameter is made smaller, the punching force at the time of molding increases the risk of the front draw cup 20 breaking at the punch shoulder, and the present invention eliminates these problems. The wrinkle holding tapered surface 15 is provided with an angle to reduce the inflow resistance of the material. The proper use of the angles of 20 to 45 degrees described above is generally determined from the following viewpoints. That is, when using a base plate having a low tensile strength, which is conventionally used, the base plate is likely to break during molding, and therefore it is necessary to further reduce the inflow resistance, and therefore the angle is set relatively large.
On the other hand, since the base plate having high tensile strength has strength, the back tension can be increased and the angle can be decreased.
In addition, when the angle is 0 degree, that is, I tried tensile bending of the ultra-thin nickel-plated steel sheet using a flat tool with no angle, but it was caused by the slip resistance of the nickel-plated steel sheet and the anisotropy of the base plate. The cup breaks frequently. 2 mentioned above
If a value of 0 to 45 degrees is adopted, not only can the wall thickness be reduced by tensile bending of the side wall, but also wrinkles do not occur in the can, and uniform thickness reduction can be achieved throughout. Table 1
In the case where there are four redrawing steps, the examples of the thickness of the nickel-plated steel sheet and the above angles are shown together with the comparative example. From this result, when the angle is 20 to 45 degrees, a good can is molded, whereas when the angle is less than 20 degrees, wrinkles are generated or the plate is broken (Comparative Example 1).
~ 4). Further, in the case of 50 degrees, sufficient back tension required for tensile bending cannot be obtained, and thinning does not proceed (see Comparative Examples 11 and 12). Generally, a plurality of redrawing steps are provided to reduce the load per one step. However, if the plate thickness reduction rate is increased, the number of redrawing steps can be reduced. However, on the other hand, cup breakage is likely to occur. Rd in the redrawing process is
Generally, a thickness of 0.5 to 2 times the thickness of the material plate is adopted, and the thickness of the cup side wall is successively thinned in each redrawing process by tensile bending and bending back action, and finally the target wall thickness is obtained. Rd of each redrawing process is set so as to be performed. This is different from the case where Rd in the conventional multi-step draw forming method is used with a size of about 2 to 10 times the thickness of the blank.
This difference in Rd is due to the fact that the present invention actively applies a tensile force to the cup during molding to actively reduce the plate thickness, that is, reduce the wall thickness. When Rd is large, the action corner part 1
The tensile bending effect of No. 6 is reduced, and it is not possible to actively reduce the plate thickness. In the present invention, when the cup end is drawn into the re-drawing die, the cup end is sandwiched between the pressing member 11 and the die 12, and a part of the cup end generally called pinching becomes extremely large. Since the problem of thinning is likely to occur, a method of completing the drawing while leaving the residual flange portion in each redrawing process is adopted. A smaller residual flange is more suitable for redrawing in the next process, but the flange width is not uniform in the circumferential direction due to the anisotropy of the material, but the average flange width for each redrawing process is It is necessary to adjust the tool conditions, the drawing depth in each process, etc. so that the thickness is 2.5 to 3 mm.

In the present invention, a nickel-plated steel sheet is used as a raw material, but when a deep-drawn cup is formed using the nickel-plated steel sheet, the presence of the nickel-plated layer is a major factor that hinders redrawing. That is, the nickel plating layer has a large friction resistance with a die or a punch, and the method used for a tin-plated steel sheet or an organic coating steel sheet cannot be applied as it is. Therefore, in the present invention, the wrinkle holding surface 14 and the wrinkle holding tapered surface 12 are 20 degrees to the horizontal plane so that the nickel-plated steel sheet having a large friction resistance can easily flow into the narrow gap of the tool under high surface pressure.
The pressing member 11 and the redrawing die 12 having an angle of 45 degrees are used. By using these tools, it is possible to facilitate the plastic deformation of the steel sheet having the nickel plating layer and to crush the cracks in the nickel plating layer portion which are likely to occur during cup forming. Then, it has a relatively smooth surface morphology macroscopically and has excellent corrosion resistance. The results are shown in the corrosion resistance test result column of Table 1. The corrosion resistance test was conducted under the following conditions. The result of immersing the molded metal can in a (5% sodium chloride + 5% hydrogen peroxide solution) solution for 16 hours was visually determined.

If a light ironing step of about 3 to 5% is added in the redraw forming, the corrosion resistance of the completed metal can will be further improved. By adding the ironing process, it is possible to close coarse cracks existing on the surface of the cup side wall portion 21 that could not be crushed in the processes up to the previous process, and further improve the surface corrosion resistance of the battery can. You can That is, since the forming method of the present invention is an extremely severe forming method in which tensile bending is positively performed, the nickel layer plated on the original plate may not be able to follow its plastic deformation and cracks may occur in the surface layer. is there. These cracks deteriorate the corrosion resistance of the battery can and are not preferable in terms of battery performance. Therefore, a light ironing process is added to the normal process to close the surface of coarse cracks. The ironing rate is 1 to
A range of 10% is suitable. This is because if it is less than 1%, the cracks cannot be closed, and if it exceeds 10%, cup rupture or peeling of the nickel plating layer is caused. Here, the ironing rate refers to the rate of reduction in plate thickness on the side wall of the cup. Table 1 shows the corrosion resistance improvement effect of the ironing process in the final process of the redrawing process.
Example 9 of It can be seen that the corrosion resistance is greatly improved. The ironing process may be performed in the middle of the redrawing process. Example 10 shows the results of the corrosion resistance test when ironing was performed in the second step of the redrawing step. Even when ironing was performed, the number of redrawing steps was set to four.

(3) Trimming process After the redrawing is completed, the unnecessary portion of the cup end is trimmed (see FIG. 4). The can bottom thickness of the battery can after molding is substantially equal to the base plate thickness, and the battery can side wall thickness is 70 to 80% of the base plate thickness, that is, the plate thickness reduction rate of 20 to 3
It is preferable to process it so as to be 0%. On the other hand, the plate thickness reduction rate of the battery can side wall thickness with respect to the base plate thickness can be processed in the range of 0% to 35%, but from the economical point of view, the plate thickness reduction rate is at least about 15 to 25%. It is preferable to avoid the trouble of breaking the inside blank.

[Table 1]

[0013]

The present invention has the following effects because it is configured as described above. Since the wrinkle holding surface and the wrinkle holding tapered surface are provided, it becomes easy to form a small-diameter can such as an AA battery using a thin nickel-plated steel plate as a base plate. Next, even when forming a thin plate having anisotropy,
Circumferential inflow became easier, and wrinkles and blank breakage during molding were eliminated. In addition, it is possible to improve the corrosion resistance by closing the cracks generated in the nickel plating layer during molding.

[0014]

[Brief description of drawings]

FIG. 1 is a half sectional view showing an outline of a method for manufacturing a battery can of the present invention.

FIG. 2 is a schematic diagram showing a main part of FIG.

FIG. 3 is a schematic view showing the principle of tensile bending.

FIG. 4 is a schematic view showing a manufacturing process of a battery can.

[Explanation of reference numerals] 11 ... Holding member 12 ... Redrawing die 14 ... Wrinkle holding surface 15 ... Wrinkle holding tapered surface 16 ... Working corner portion 20 ... Front throttle cup 21 ... Side wall portion

Claims (2)

[Claims] 1. A nickel-plated metal plate is formed into a front drawing cup, and the front drawing cup is held by a ring-shaped holding member and a re-drawing die arranged below the holding member, and these holding member and re-drawing die are held. With a re-drawing punch and the re-drawing die that are provided so as to be coaxial with and reciprocate in the pressing member, in a method for multi-step molding a deep-drawing cup having a diameter smaller than that of the front drawing cup, A pair of the pressing member and the re-drawing die have a wrinkle holding surface angle of 20 ° to 45 ° with respect to the horizontal plane, respectively. A method for manufacturing a thin-walled nickel-plated metal can for a battery, which is characterized by tensile bending. 2. A nickel-plated metal plate is formed into a front drawing cup, and the front drawing cup is held by a ring-shaped holding member and a redrawing die arranged below the holding member, and these holding member and redrawing die are held. With a re-drawing punch and the re-drawing die that are provided so as to be coaxial with and reciprocate in the pressing member, in a method for multi-step molding a deep-drawing cup having a diameter smaller than that of the front drawing cup, A pair of the pressing member and the re-drawing die have a wrinkle holding surface angle of 20 ° to 45 ° with respect to the horizontal plane, respectively. Tensile bending, and in at least one redrawing step, the cup sidewall thickness reduction rate is 1 to 1 with respect to the pre-drawn cup sidewall thickness.
A method for producing a thin-walled nickel-plated metal can for batteries, characterized by performing ironing processing so that the content of the metal can becomes 0%.