JP2019166527A - Manufacturing method of square battery case - Google Patents

Abstract

To provide a manufacturing method of a square battery case capable of enhancing productivity by reducing the process number of press working.SOLUTION: A manufacturing method of a square battery case includes a blank material preparation process of preparing a blank material of an aluminum alloy formed in a long size shape by setting a plate thickness to 2.7 times-3.5 times to a side surface wall thickness in a bottomed cylindrical square case of forming a processing end product 5 in a cross-sectional lengthy rectangular shape, a first press process of forming a bottomed cylindrical first intermediate product by executing restriction processing to the blank material, a second press process of forming a bottomed cylindrical second intermediate product 20 by executing squeezing restriction processing to the first intermediate product and a third press process of forming a third intermediate product 30 by executing squeezing processing to the second intermediate product 20.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a method for manufacturing a rectangular battery case.

  Conventionally, as a battery case of a lithium ion secondary battery, a manufacturing method for a bottomed cylindrical prismatic battery case formed by pressing is provided. For example, in Patent Document 1, a first step of forming a first intermediate cup body having an elliptical cross-sectional shape by drawing using a punch, a punch (second punch), and the punch A second step of forming a second intermediate cup body having a rectangular cross-sectional shape by drawing using the fitted sleeve, and the second intermediate cup body arranged in a plurality of stages with the third punch And a third step of forming a final rectangular battery case by ironing with a die (third ironing die).

Japanese Patent No. 5975573

  The prismatic battery case is required to have high rigidity while being formed with a thin side wall for weight reduction. Therefore, in the case of pressing a rectangular battery case, initially, the plate material is subjected to a drawing process having an elliptical cross section, and after the drawing process in a subsequent process, the cross section is formed into a long rectangular shape. The side wall was extended by ironing to obtain a highly rigid side wall. Such a conventional manufacturing method requires a further reduction in the number of steps because the number of steps of pressing (particularly the number of steps of ironing) increases.

  An object of this invention is to provide the manufacturing method of the rectangular battery case which can reduce the number of processes of press work and can improve productivity.

  The manufacturing method of the prismatic battery case is a long shape with a plate thickness of 2.7 times to 3.5 times the side wall thickness of a bottomed cylindrical prismatic case whose finished product has a rectangular shape in cross section. A blank material preparation step of preparing a blank material of an aluminum alloy formed on the base material, and a drawing using a punch whose front end surface is formed in a long rectangular shape corresponding to the inner surface of the bottom plate of the finished product. A first press step for forming a bottomed cylindrical first intermediate product by processing, and a punch whose end surface is formed in a long rectangular shape corresponding to the inner surface of the bottom plate of the processed product with respect to the first intermediate product A second press step of forming a bottomed cylindrical second intermediate product by performing ironing and drawing, and an elongated rectangle whose end surface corresponds to the inner surface of the bottom plate of the finished product with respect to the second intermediate product Shaped bread Including a third pressing step of forming a third intermediate product subjected to ironing using.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the square battery case which can reduce the number of processes of press work and can improve productivity can be provided.

It is a figure which shows the formation process of the square battery case which concerns on embodiment of this invention, (a) is a perspective view of the blank material prepared at a blank material preparation process, (b) is a perspective view of a 1st intermediate product. It is. It is a figure which shows the formation process of the square battery case which concerns on embodiment of this invention, (c) is a perspective view of the 2nd intermediate product shape | molded by a 2nd press process, (d) is a 3rd press process. It is a perspective view of the 3rd intermediate product formed, (e) is a perspective view of the 4th intermediate product formed at the 4th press process, (f) is a perspective view of the final product formed at a cutting process. FIG. It is the cross-sectional schematic diagram which looked at the metal mold | die used at the 1st press process which concerns on embodiment of this invention from the front, (a) shows the state which the upper mold | type and the lower mold | type opened, (b) The lower mold is closed. It is the cross-sectional schematic diagram which looked at the metal mold | die used by the 2nd press process which concerns on embodiment of this invention from the front, (a) shows the state which the upper mold | type and the lower mold | type opened, (b) The lower mold is closed.

  Next, an embodiment of the present invention will be described based on the drawings. 1 and 2 are views showing products and the like in the manufacturing process of a rectangular battery case made of aluminum alloy. Fig.1 (a) shows the blank material 1 prepared in the blank material preparation process which prepares the blank material made from an aluminum alloy, and FIG.1 (b) shows the 1st intermediate product 10 formed at a 1st press process. FIGS. 2C to 2E show the second intermediate product to the fourth intermediate product in the second press process to the fourth press process in order, and FIG. 2F is formed by a cutting process for cutting unnecessary portions. Indicates the final product.

(Blank material preparation process)
In the blank material preparation step, a blank material 1 shown in FIG. The blank material 1 is made into a substantially long flat plate shape. The blank material 1 includes two linear portions 2 that extend in the longitudinal direction and are opposed in the lateral direction in plan view. At both ends of the blank material 1, tapered connection portions 3 are formed on the outer side in the longitudinal direction so as to connect the ends of the two linear portions 2. More specifically, each connecting portion 3 includes a large arc 3a connected to the straight portion 2 and a small arc 3b connecting the large arcs 3a. The large arc 3a is formed as an arc having a larger radius than the small arc 3b.

  Each straight line portion 2 of the blank 1 corresponds to the longitudinal direction of the finished product (fourth intermediate product 40, see FIG. 2E) that has been subjected to press working having a rectangular cross section. And the plate | board thickness of the blank material 1 is set to 2.7 times or more and 3.5 times or less with respect to the side plate thickness (same as the side plate thickness of the product 5) of a processing completion product (4th intermediate product 40). The

(First press process)
In the first pressing step, the blank material 1 is drawn by the mold 100 shown in FIGS. 3A and 3B to form the first intermediate product 10 shown in FIG. Here, the mold 100 shown in FIGS. 3A and 3B includes an upper mold 110, a lower mold 120, and a die cushion 130. In the upper mold 110, the first die component 112 is erected downward from the lower surface of the upper die plate 111. A holder 113 that is formed in an annular shape and holds the first die part 112 on the upper die plate 111 is provided on the outer periphery of the first die part 112. A second die part 114 that is formed in an annular shape and has an inclined surface 114 a on the inner periphery is provided on the lower surface of the holder 113 and on the outer periphery of the tip end of the first die part 112. An annular third die part 115 is provided on the lower surface of the second die part 114. A concave space formed by the first die part 112, the second die part 114, and the third die part 115 is used as a die for the punch 122.

  In the lower mold 120, a punch 122 is erected from the upper surface of the lower die plate 121. A punch holder 123 that is formed in an annular shape and holds the punch 122 on the lower die plate 121 is provided on the outer periphery of the punch 122. A plurality of cushion pins 135 are inserted through the lower die plate 121 and the punch holder 123. An annular blank holder 132 is provided at the upper end of the cushion pin 135 so as to be disposed on the outer periphery of the punch 122. An annular plate 136 is arranged on the outer periphery of the upper surface of the blank holder 132. The plate 136 is positioned by positioning pins 137 standing on the blank holder 132. The plate 136 has substantially the same thickness as that of the blank material 1. The blank 1 is arranged and positioned inside the plate 136.

  3A and 3B, the press machine is not shown, but the upper die plate 111 is fixed to the slide lower surface of the press machine, and the lower die plate 121 is the upper surface of the bolster on the bed of the press machine. The upper die 110 and the lower die 120 are relatively approached and separated from each other, and press working is performed.

  In the first pressing step, first, as shown in FIG. 3A, the blank material 1 is arranged on the upper surface of the blank holder 132 and inside the plate 136. And as shown in FIG.3 (b), the upper mold | type 110 and the lower mold | type 120 are made to approach, and press work (drawing process) is performed. At this time, at the initial stage of the drawing process, the outer periphery of the blank material 1 is sandwiched by the third die part 115 and the blank holder 132 together with the plate 136. Then, the outer periphery of the blank 1 moves between the third die part 115 and the blank holder 132 to be sandwiched as the drawing process proceeds. At this time, since the lower inner peripheral edge 115a of the third die part 115 is formed in an R chamfered shape, the outer periphery of the blank 1 is smoothly moved. In this way, the blank material 1 is formed with the first intermediate product 10 shown in FIG. 1B having side walls on which no flanges are formed while suppressing generation of wrinkles on the outer periphery.

  Here, the shape of the first intermediate product 10 corresponds to the shape of the space formed by combining the first die part 112, the second die part 114, the third die part 115, the punch 122 and the blank holder 132. It is formed. More specifically, as shown in FIG. 1B, the first intermediate product 10 is formed in a bottomed cylindrical shape formed in a substantially rectangular shape in cross section. In the first intermediate product 10, the side wall 11 in the longitudinal direction has a substantially mountain shape in side view, and the height is higher than the side wall 12 in the short side direction. A flat surface 15 formed in a long rectangular shape is formed on the inner surface of the bottom plate 13 of the first intermediate product 10. Corresponding to the flat surface 15, a long rectangular flat portion is formed on the tip surface of the punch 122. Similarly, a long rectangular flat portion is formed on the lower surface of the bottom plate 13, and a long rectangular flat portion is formed corresponding to the front end surface of the first die component 112.

  As shown in the AA end view of the first intermediate product 10 surrounded by a broken line in FIG. 1B, the bottom plate 13 and the side wall 11 in the longitudinal direction in the longitudinal sectional view are connected at both ends of the bottom plate 13 with a radius. A small arc portion 13a having a small R is formed, and a large arc portion 11a having a radius R larger than that of the small arc portion 13a is connected. And the large circular arc part 11a is connected with the linear part 11b extended linearly in the longitudinal cross sectional view. The side wall 11 in the longitudinal direction of the first intermediate product 10 is formed by a large arc portion 11a and a straight portion 11b. Similarly, the side wall 12 in the short direction is formed of a large arc portion and a straight portion, and the large arc portion of the side wall 12 and the small arc portions at both ends of the bottom plate 13 are connected. Further, the side wall 11 in the longitudinal direction and the side wall 12 in the short direction are connected with a relatively large radius R in plan view. The first intermediate product 10 formed by drawing the blank material 1 is formed to have a thickness substantially the same as the thickness of the blank material 1.

(Second press process)
In the second pressing step, iron drawing is performed on the first intermediate product 10 formed in the first pressing step to form the second intermediate product 20 shown in FIG. In the ironing drawing process according to the present embodiment, a part of the first intermediate product 10 is drawn and the other part is ironed.

  Specifically, the large arc portion and the small arc portion around the bottom plate 13 of the first intermediate product 10 (the large arc portion 11a and the small arc portion 13a in the longitudinal direction are shown in FIG. 1B) are drawn. Then, the side plates 21 and 22 of the second intermediate product 20 have substantially the same thickness as the side walls 11 and 12 of the first intermediate product 10. On the other hand, the four corners where the side walls 11 and 12 of the first intermediate product 10 and the bottom plate 13 are connected and the periphery thereof are subjected to ironing. That is, when drawing is performed on the large arc portion and the small arc portion around the bottom plate 13 of the first intermediate product 10, the material flows in the corners of the four corners of the bottom plate 13 and the periphery thereof. As a result of the ironing process, the four corners where the side walls 21 and 22 of the second intermediate product 20 and the bottom plate 23 are connected and the thickness of the periphery thereof are substantially equal to the thickness of the side walls 21 and 22. Is done.

  In addition, by ironing the four corners where the side walls 11 and 12 and the bottom plate 13 of the first intermediate product 10 are connected and the periphery thereof, the height of the side wall 12 on the short side is set in a side view. It becomes substantially the same height as the upper part of the mountain shape of the side plate 11 of the first intermediate product 10 having a substantially mountain shape. Therefore, the height of the side walls 21 and 22 of the second intermediate component 20 is approximately the same. In this way, the second intermediate product 20 is formed in a rectangular shape with a long cross section.

  The second pressing step is performed by a mold 200 shown in FIGS. 4 (a) and 4 (b). The mold 200 includes an upper mold 210 and a lower mold 220. The upper die 210 has a backing plate 213 attached to the lower surface of the upper die plate 211 and supports the rear end of the punch 212. The punch 212 is fixed to the backing plate 213 by a punch holder 214 formed in an annular shape on the outer periphery of the punch 212.

  In the lower mold 220, the die plate 222 is fixed to the upper surface of the lower die plate 221. A die 223 is provided on the top of the die plate 222. The dice 223 includes an upper die 223a and a lower die 223b, both of which are annular. By combining the upper die 223a and the lower die 223b, a portion to be drawn with the clearance between the punch 212 and the die (here, the die 223) equivalent to the thickness of the first intermediate product 10 (that is, equivalent to the plate thickness of the blank material 1); Thus, a portion to which ironing is performed so that the clearance between the punch 212 and the die (die 223) is equal to or less than the thickness of the first intermediate product 10 is formed.

  An annular stripper 215 is provided on the outer periphery of the punch 212 above the upper die 223a. The stripper 215 is supported by a spring 217 wound around the outer periphery of a stripper bolt 216 whose tip is screwed with the lower surface of the stripper 215 and extends downward, so as to be elastically upwardly projected. Further, a knockout 225 and a cushion pin 226 connected to the knockout 225 from below are provided on the die 223.

  When the second pressing step is performed on the first intermediate product 10 by the mold 200, ironing drawing is performed to form the second intermediate product. In the second intermediate product 20, a flat portion 25 having a long rectangular shape is formed on the inner surface of the bottom plate 23, and a front end surface of the punch 212 is also formed in a long rectangular shape corresponding to the flat portion 25. The cross-sectional shape of the second intermediate product 20 is a long rectangular shape close to the product 5 after processing is completed.

(3rd press process and 4th press process)
In the third press process and the fourth press process, the punch 212 and the die 223 of the mold 200 in FIG. 4 are changed, and the second intermediate product 20 and the third intermediate product 30 are ironed. Ironing in the third press process and the fourth press process is performed on the side walls 21, 22, 31, 32 including the corners of the four corners of the bottom plates 23, 33 of the second intermediate product 20 and the third intermediate product 30, respectively. The ironing process is performed to make it thinner. Further, the front end surface of the punch in the third pressing step is formed in a long rectangular shape corresponding to the long rectangular flat portion 35 on the inner surface of the bottom plate 33 of the third intermediate product 30. Similarly, the front end surface of the punch in the fourth pressing step is formed in a long rectangular shape corresponding to the flat portion 45 on the inner surface of the bottom plate 43 of the fourth intermediate product 40.

(Cutting process)
In the fourth intermediate product 40 that has been pressed, unnecessary portions of the upper opening are cut off in the cutting process. In this way, the product 5 is formed which is a case body having a rectangular shape with a bottomed cylindrical cross section of a rectangular battery case.

  Thus, the plate thickness is 2.7 times or more and 3.5 times or less with respect to the side wall thickness in the bottomed cylindrical rectangular case in which the finished product (and the fourth intermediate product 40) has a rectangular shape in cross section. By using the long aluminum alloy blank 1 as described above and successively pressing with a punch whose front end surface is formed in a long rectangular shape corresponding to the inner surface of the bottom plate of the finished product, the number of processes can be increased. We were able to reduce significantly. Specifically, when the thickness of the side wall of the finished product is 0.7 mm, the thickness of the blank material is conventionally 1.2 mm. Then, since the pressing process is initially performed by two or more drawing processes and multi-stage ironing is performed, a total of 11 to 13 pressing processes are required until a finished product is obtained from the blank material. However, the number of steps of pressing is conventionally increased by performing the pressing process using a punch (punch 122, 212, etc.) in which the thickness of the blank 1 is 2.0 mm and a long rectangular flat surface is formed on the tip surface. It was able to be about half of.

  Further, the first intermediate product 10 is partially ironed and the other portions are subjected to ironing drawing, whereby the thickness of the side walls 21 and 22 is increased in the second pressing step. Obtaining a second intermediate product 20 having a substantially rectangular cross section substantially the same as the inner surface of the bottom plate 23 while being substantially equal to the thickness of the side walls 11 and 12 of the intermediate product 10 (that is, the thickness of the blank 1). Therefore, it is possible to reduce the number of processing steps before the plurality of ironing processes.

  And the blank material 1 in this embodiment can make an area smaller than the conventional blank material whose plate | board thickness is 1.2 mm. That is, conventionally, since the first few steps of all pressing steps perform drawing processing in which the plate thickness does not substantially change, a blank material having a predetermined area has been required. However, since the blank material 1 in this embodiment is an ironing drawing process in which the second pressing process can reduce a part of the thickness, and the third pressing process and the subsequent ironing processes, the area of the blank material 1 is conventionally reduced. Can be significantly reduced. Therefore, the yield at the time of blanking the blank 1 from the aluminum plate was improved. Moreover, although the plate thickness increased from 1.2 mm to 2.0 mm, the blank material area could be greatly reduced, so the required blank material weight relative to the weight of the product 5 was reduced by about 7%. I was able to.

  In addition, although the applicant of this application tried processing even if the board | plate thickness of the blank material 1 was set to 2.5 mm or 3.0 mm, when board thickness is made too thick in this way, board thickness (0 It has been found that the number of ironing processes to obtain (.7 mm) is increased, and the number of processes is increased as compared with the prior art. Further, when the plate thickness is less than 2.0 mm, the required area of the blank material 1 is increased, and the occurrence of processing defects such as tearing of the side wall surface in the ironing process increases. In this way, the applicant of the present invention has a thickness of the blank material 1 that is at least 2.7 times the side wall thickness of the bottomed cylindrical rectangular case in which the finished product has a long rectangular cross section. We found that 5 times or less is optimal.

  As mentioned above, although embodiment of this invention was described, this invention is not limited by this embodiment, It can implement by changing suitably. For example, the first press step for obtaining the first intermediate product 10 and the second press step for obtaining the second intermediate product 20 can each be composed of a plurality of steps. Further, the ironing process of a plurality of times can be performed so that one punch is inserted through dies formed in multiple stages.

DESCRIPTION OF SYMBOLS 1 Blank material 2 Straight part 3 Connection part 3a Large circular arc 3b Small circular arc 5 Product 10 1st intermediate product 11 Side wall 11a Large circular arc part 11b Straight line part 12 Side wall 13 Bottom plate 13a Small circular arc part 15 Flat surface 20 2nd intermediate product 21 Side wall 22 Side wall 23 Bottom plate 25 Flat part 30 Third intermediate product 31 Side wall 32 Side wall 35 Flat part 40 Fourth intermediate product 41 Side wall 42 Side wall 45 Flat part 100 Mold 110 Upper mold 111 Upper die plate 112 First die part 113 Holder 114 Second Die part 114a Inclined surface 115 Third die part 120 Lower die 121 Lower die plate 122 Punch 123 Punch holder 130 Die cushion 131a Lower inner peripheral edge 132 Blank holder 135 Cushion pin 136 Plate 137 Positioning pin 200 Mold 210 Upper die 211 Upper die Plate 212 Chi 213 backing plate 214 punch holder 215 punch holder 216 stripper bolt 217 spring 220 the lower die 221 lower die plate 222 die plate 223 die 223a on die 223b under die 225 knockout 226 cushion pins

Claims (2)

Aluminum alloy blank formed into a long shape with a plate thickness of 2.7 times to 3.5 times the side wall thickness in a bottomed cylindrical rectangular case whose finished product has a long rectangular cross section Blank material preparation process to prepare the material,
A first intermediate product having a bottomed cylindrical shape is formed by drawing the blank material using a punch having a long rectangular shape corresponding to the inner surface of the bottom plate of the finished product. Pressing process;
A second intermediate product having a bottomed cylindrical shape is formed on the first intermediate product by ironing using a punch whose end surface is formed in a long rectangular shape corresponding to the inner surface of the bottom plate of the finished product. 2 press processes;
A third press step of forming a third intermediate product by performing ironing on the second intermediate product using a punch having an end surface corresponding to the inner surface of the bottom plate of the processed product;
The manufacturing method of the square battery case characterized by including.   The blank material is formed in a tapered shape on the outside in the longitudinal direction so as to connect two linear portions formed corresponding to the longitudinal direction of the processed product and the ends of the two linear portions. The method of manufacturing a rectangular battery case according to claim 1, further comprising: a connecting portion.

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