Manufacturing method of bottomed cylindrical part

Abstract

To provide a method for manufacturing a cylindrical component with a bottom, capable of achieving both a sharp and deep shape and a wrinkle-free flange part.SOLUTION: An intermediate formed body 6 is obtained from a plate material 2 by drawing with a first die 3. A cylindrical component 6 with a bottom is obtained from the intermediate formed body 6 by drawing with a second die 8. The first die 3 has a first die shoulder part radius DSR1 larger than a product shoulder part radius PSR, and has a first die depth DD1 deeper than a product depth PD. The second die 8 has a second die shoulder part radius DSR2 equal to the product shoulder part radius PSR, and has a second die depth DD2 equal to the product depth PD.SELECTED DRAWING: Figure 4B

Description

[Technical field]

[0001] The present invention relates to a method for manufacturing a bottomed tubular part. [Background technology]

[0002] Patent Documents 1 and 2 disclose that a battery pack case for an automobile, which is an example of a bottomed tubular part, is produced by press molding a plate material such as an aluminum alloy. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication 2014-60165 [Patent Document 2] Patent Publication 2019-18732 Summary of the Invention [Problem to be solved by the invention]

[0004] Automotive battery pack cases manufactured by press molding have, for example, a rectangular cylindrical shape with a flange and a bottom. This type of battery pack case requires a sharp and deep shape to ensure the amount of batteries that can be mounted. It also requires sealing properties to prevent electric leakage.

[0005] For a sharp, deep shape, it is important to reduce the radius (shoulder radius) of the connection between the main body in which the battery is housed and the flange extending from the opening of the main body. The maximum size of the battery pack case is restricted by the size of the automobile's framework (e.g., side sills, A-pillars, B-pillars). To increase the battery capacity under these conditions, it is important to reduce the radius of the shoulders and the gap between the battery pack case and the mating member that supports it (e.g., battery pack frame and side sills).

[0006] To ensure a good seal, it is important that the flange portion is free of wrinkles.

[0007] However, Patent Documents 1 and 2 are silent about achieving both a sharp and deep shape and the absence of wrinkles in the flange portion when manufacturing a bottomed tubular part by press molding a metal plate.

[0008] An object of the present invention is to provide a method for manufacturing a bottomed tubular part that can achieve both a sharp, deep shape and a flange portion without wrinkles. [Means for solving the problem]

[0009] One aspect of the present invention is a manufacturing method for a bottomed tubular part including a bottomed tubular main body and a flange portion extending from an opening of the main body, the method including a first step of obtaining an intermediate formed body from a sheet material by drawing using a first die having a first die shoulder radius larger than a product shoulder radius, which is a radius of a connection portion between the main body and the flange portion, and a first die depth deeper than a product depth, which is a depth of the main body, and a second step of obtaining the bottomed tubular part from the intermediate formed body by drawing using a second die having a second die shoulder radius the same as the product shoulder radius and having a second die depth the same as the product depth. The corner radius of the bottomed rectangular cylinder shape is 20 mm or more, the initial thickness of the blank is 1.0 mm or more, and the first die depth satisfies the following formula: A method for manufacturing a bottomed tubular part is provided.

[0010]

number

[0011] In the first step, a first die having a first die shoulder radius larger than the product shoulder radius is used, which promotes the flow of material into the body of the intermediate compact, and ensures the molding depth of the body of the intermediate compact. As a result, the product depth of the bottomed tubular part, which is the final product, can be set deep. In addition, by using a first die having a first die shoulder radius larger than the product shoulder radius in the first step and then using a second die having a second die shoulder radius the same as the product shoulder radius in the subsequent second step, the product shoulder radius of the bottomed tubular part, which is the final product, can be set small. In this way, according to the present invention, a bottomed tubular part with a sharp and deep shape can be manufactured.

[0012] In the first step, a first die having a first die shoulder radius larger than the product shoulder radius is used to ensure the forming depth, whereas in the second step, a second die having a second die shoulder radius equal to the product shoulder radius is used. In other words, in the second step, the product shoulder radius of the intermediate formed body (corresponding to the first die shoulder radius) is reduced to the product shoulder radius of the final product (corresponding to the second die shoulder radius). This means that material needs to be supplied to the shoulder of the intermediate formed body in the second step. However, the first die depth of the first die used in the first step is deeper than the product depth of the bottomed tubular part, which is the final product. In other words, the product depth of the intermediate formed body provided in the second step is deeper than the product depth of the bottomed tubular part, which is the final product, and the depth of the main body is reduced in the second step. Therefore, in the second step, the material to be supplied to the connection part between the main body and the flange part in order to reduce the product shoulder radius from the size corresponding to the first die shoulder radius to the size corresponding to the second die shoulder radius can be ensured by the outflow of material from the main body. In other words, the material to be supplied to the connection between the main body and the flange in order to reduce the die shoulder radius from the first die shoulder radius to the second die shoulder radius in the second step is not secured by the inflow of material from the flange. By reducing or eliminating the inflow of material from the flange, the occurrence of wrinkles in the flange can be prevented.

[0013] As described above, according to the present invention, it is possible to achieve both a sharp and deep shape and a flange portion without wrinkles.

[0014] The plate may be made of aluminum. Effect of the Invention

[0016] According to the method for manufacturing a bottomed tubular part of the present invention, it is possible to achieve both a sharp and deep shape and a flange portion without wrinkles. [Brief description of the drawings]

[0017] [Figure 1A] FIG. 2 is a perspective view of a bottomed rectangular tubular part manufactured by a manufacturing method according to an embodiment of the present invention. [Figure 1B] FIG. 1B is a cross-sectional view taken along line II in FIG. 1A. [Figure 2A] FIG. 3 is a perspective view of a die used in a first drawing step of the manufacturing method according to the embodiment of the present invention. [Figure 2B] FIG. 2B is a cross-sectional view taken along line II-II in FIG. 2A. [Diagram 3] FIG. 4 is an exploded perspective view illustrating a first drawing step in the manufacturing method according to the embodiment of the present invention. [Figure 4A] FIG. 4 is a perspective view of a die used in a second drawing step in the manufacturing method according to the embodiment of the present invention. [Figure 4B] FIG. 4B is a cross-sectional view taken along line IV-IV in FIG. 4A. [Diagram 5] FIG. 4 is an exploded perspective view illustrating a second drawing step in the manufacturing method according to the embodiment of the present invention. [Figure 6A] 2 is a schematic cross-sectional view taken along line II in FIG. 1 for explaining a change in line length after a second drawing process. FIG. [Figure 6B] 1 is a graph showing the results of a forming analysis regarding the relationship between the deviation of the forming height from the reference value in the first process and the occurrence of breakage and wrinkles. [Figure 7A] FIG. 4 is a perspective view of a die used in the manufacturing method according to the first comparative example. [Figure 7B] FIG. 7B is a cross-sectional view taken along line VII-VII in FIG. 7A. [Figure 8A] FIG. 11 is a perspective view of a die used in a first drawing step of the manufacturing method according to the second comparative example. [Figure 8B] FIG. 8B is a cross-sectional view taken along line VIII-VIII in FIG. 8A. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Hereinafter, a manufacturing method according to an embodiment of the present invention will be described with reference to the accompanying drawings.

[0019] 1A and 1B, in the manufacturing method of this embodiment, an aluminum plate is press-formed to manufacture a bottomed rectangular tubular part 1. The bottomed rectangular tubular part 1 can be used as a case for a battery pack, which is an example of a component for an automobile.

[0020] The bottomed rectangular tubular part 1 includes a main body 1a which is a bottomed rectangular tubular body of a certain depth, and a flange portion 1b which extends outward from the entire circumference of the opening of the main body 1a.

[0021] In this embodiment, the main shape and dimensions of the bottomed rectangular tubular part 1 are as follows.

[0022] In this embodiment, a 5000 series aluminum plate having a plate thickness of 1 mm is used, but the plate thickness and alloy type are not limited to this.

[0023] In this embodiment, the bottom of the main body 1a is a square with a side length of 600 mm. The side length is not limited to 600 mm. The bottom of the main body 1a may be a rectangle.

[0024] In this embodiment, the depth of the main body 1a (product depth PD) is 70 mm. The product depth PD is not limited to 70 mm.

[0025] In this embodiment, the radius of the connection portion between the main body 1a and the flange portion 1b, that is, the radius of the product shoulder portion 1c (product shoulder radius PSR) is 2 mm. The product shoulder radius PSR is not limited to 2 mm.

[0026] In this embodiment, the radius of the connecting portion between the bottom and side of the main body 1a (product bottom radius PBR) is 10 mm. The product bottom radius PBR is not limited to 10 mm.

[0027] In this embodiment, the radius (product corner radius PCR1) of the bottom corner of the main body 1a is about 52 mm. The product corner radius PCR1 is not limited to about 52 mm.

[0028] In this embodiment, the radius of the corner formed by the two side parts of the main body 1a (product corner radius PCR2) is 20 mm. The product corner radius PCR2 is not limited to 20 mm.

[0029] The radius of the corner formed by the connection between the side and bottom of the main body 1a 2 (product corner radius PCR3) is 25 mm at the center and gradually tapers to 10 mm at the radius end. The dimensions of the product corner radius PCR3 are not limited to those in this embodiment.

[0030] In the manufacturing method of this embodiment, the bottomed rectangular tubular part 1 is manufactured from a blank 2 (see FIG. 3), which is an aluminum plate material, by two drawing steps (a first step and a second step).

[0031] (1st step) The first step will be described with reference to FIGS. 2A to 3.

[0032] The first die 3 used in the first step has a die body 3a for forming the main body 1a of the bottomed rectangular tubular part 1, which is the final product, and a die flange portion 3b for forming the flange portion 1b of the bottomed rectangular tubular part 1.

[0033] The radius (first die shoulder radius DSR1) of the die shoulder 3c, which is the connection portion between the die body 3a and the die flange portion 3b, is set to be larger than the product shoulder radius PSR. Specifically, in this embodiment, the product shoulder radius PSR is 2 mm as described above, while the first die shoulder radius DSR1 is set to 15 mm. The first die shoulder radius DSR1 is set to satisfy the condition that it is larger than the product shoulder radius PSR.

[0034] The depth of the die body 3a (first die depth DD1) is set deeper than the product depth PD. Specifically, in this embodiment, the product depth PD is 70 mm as described above, whereas the first die depth DD1 is set to 75 mm. The first die depth DD1 is set to satisfy the condition that it is deeper than the product depth PD.

[0035] Other shapes and dimensions of the first die 3 are set corresponding to the shape and dimensions of the bottomed rectangular tubular part 1 described with reference to Figs. 1A and 1B, that is, the shape and dimensions of the final product.

[0036] 3, in the first step, the peripheral portion of the blank 2 is sandwiched and held between the die flange portion 3b of the first die 3 and a rectangular frame-shaped holder 4. In this state, pressure is applied to the blank 2 by the first punch 5, as conceptually shown by the arrow F in FIG.

[0037] The shape and dimensions of the first punch 5 are set in accordance with the first die 3 .

[0038] The pressure applied by the first punch 5 causes the blank 1 to deform into the shape of the first die 3, and an intermediate formed body 6 (see FIG. 5) is obtained. The intermediate formed body 6 has a main body 6a which will become the main body 1a in the bottomed rectangular tubular part 1, which is the final product, and a flange portion 6b which will become the flange portion 1b in the bottomed rectangular tubular part 1. The radius (intermediate formed body shoulder radius MSR) of the shoulder portion 6c, which is the connection portion between the main body 6a and the flange portion 6b in the intermediate formed body 6, is the same as the first die shoulder radius DSR1 (15 mm in this embodiment). In addition, the depth (intermediate formed body depth MD) of the main body 6a of the intermediate formed body 6 is the same as the first die depth DD1.

[0039] (2nd process) The second step will be described with reference to FIGS. 4A to 5.

[0040] The second die 7 used in the second step has a die body 7a for forming the main body 1a of the bottomed rectangular tubular part 1, which is the final product, and a die flange portion 7b for forming the flange portion 7b of the bottomed rectangular tubular part 1.

[0041] The radius (second die shoulder radius DSR2) of the die shoulder 7c, which is the connection portion between the die body 7a and the die flange 7b, is set to be the same as the product shoulder radius PSR. Specifically, in this embodiment, since the product shoulder radius PSR is 2 mm as described above, the second die shoulder radius DSR2 is set to 2 mm. Also referring to Fig. 6, the second die shoulder radius DSR2 of the second die 7 used in the second step is smaller (2 mm in this embodiment) than the first die shoulder radius DSR1 of the first die 3 used in the first step (15 mm in this embodiment).

[0042] The depth of the die body 7a (second die depth DD2) is set to be the same as the product depth PD. Specifically, in this embodiment, since the product depth PD is 70 mm as described above, the second die depth DD2 is set to 70 mm. Referring to Fig. 5, the second die depth DD2 of the second die 7 used in the second step is shallower (70 mm in this embodiment) than the first die depth DD1 of the first die 3 used in the first step (75 mm in this embodiment).

[0043] The other shapes and dimensions of the second die 7 are set corresponding to the shape and dimensions of the bottomed rectangular tubular part 1 described with reference to Figs. 1A and 1B, that is, the shape and dimensions of the final product.

[0044] 5, the intermediate compact 6 is placed on the second punch 8. In this state, as conceptually shown by the arrow F in FIG. 5, the second die 7 moves toward the second punch 8, thereby applying pressure to the intermediate compact 6.

[0045] The second punch 8 has a punch body 8a and a punch flange portion 8b extending outward from the entire circumference of the punch body 8a. The radius (second punch shoulder radius PUSR2) of the punch shoulder portion 8c, which is the connection portion between the punch body 8a and the punch flange portion 8b, is set based on the second die shoulder radius DSR2 and taking into account the plate thickness. In addition, the depth (second punch depth PUD2) of the punch body 8a is set to be the same as the second die depth DD2.

[0046] The pressure applied by the second die 7 moving toward the second punch 8 deforms the intermediate formed body 6 into the shape of the second die 7, resulting in the final product, a bottomed rectangular tubular part 1 (see Figures 1A and 1B).

[0047] The features of the manufacturing method of this embodiment will be described below with reference to two comparative examples, that is, a first comparative example shown in FIGS. 7A and 7B and a second comparative example shown in FIGS. 8A and 8B.

[0048] In this embodiment, a first step is performed which is drawing using a first die 3 having a first die shoulder radius DSR1 larger than the product shoulder radius PSR of the bottomed rectangular tubular part 1, which is the final product, and a first die depth DD1 deeper than the product depth PD of the bottomed rectangular tubular part 1. Then, a second step is performed which is drawing using a second die 8 having a second die shoulder radius DSR2 the same as the product shoulder radius PSR and a second die depth DD2 the same as the product depth PD.

[0049] In contrast, in the first comparative example, only one drawing process corresponding to the first step in this embodiment, that is, only one drawing process is performed on a blank. Also, in the first comparative example, as shown in Figures 7A and 7B, a first die 3 having a first die shoulder radius DSR1 that is the same as the product shoulder radius PSR and a first die depth DD1 that is the same as the product depth PD is used.

[0050] Next, in the second comparative example, a drawing process is performed on a blank, which corresponds to the first step in this embodiment, and a drawing process is performed on an intermediate formed body, which corresponds to the second step. The difference between the second comparative example and this embodiment is that the first die depth DD1 of the first die 3 used in the first step is the same as the product depth PD of the bottomed rectangular tubular part 1, which is the final product, as shown in Figures 8A and 8B (the first die shoulder radius DSR1 is larger than the product shoulder radius PSR).

[0051] According to a simulation carried out by the present inventors, in the first comparative example, the blank breaks before reaching the first product depth PD, and the bottomed tubular part 1 as the final product is not obtained.

[0052] Furthermore, according to the above simulation, in the second comparative example, although a bottomed tubular part 1 is obtained, wrinkles occur in the flange portion 1b. This is because the second die shoulder radius DSR2 in the second step is smaller (2 mm) than the first die shoulder radius DSR1 (15 mm) in the first step, and therefore the material to be supplied to the shoulder portion 6c of the intermediate formed body 6 in the second step is secured by the material flowing in from the flange portion 6b.

[0053] On the other hand, according to the above simulation, in the manufacturing method of this embodiment, by using the first die 3 having the first die shoulder radius DSR1 larger than the product shoulder radius PSR in the first step, the material flow into the main body 6a of the intermediate compact 6 can be promoted, and the intermediate compact depth MD can be secured. As a result, the product depth PD of the bottomed tubular part 1 can be set deep without causing breakage of the blank as in the first comparative example. In addition, in the manufacturing method of this embodiment, by using the first die 3 having the first die shoulder radius DSR1 larger than the product shoulder radius PSR in the first step, and then using the second die 7 having the second die shoulder radius DSR2 the same as the product shoulder radius PSR in the second step, the product shoulder radius PSR of the bottomed tubular part 1, which is the final product, can be set small. In this way, according to the manufacturing method of this embodiment, a bottomed rectangular tubular part 1 having a sharp and deep shape can be manufactured.

[0054] Next, according to the above simulation, in the manufacturing method of this embodiment, in the first step, a first die 3 having a first die shoulder radius DSR1 larger than the product shoulder radius PSR is used to ensure the forming depth, but in the second step, a second die 7 having a second die shoulder radius DSR2 equal to the product shoulder radius PSR is used. In other words, in the second step, the intermediate compact shoulder radius MSR1 (corresponding to the first die shoulder radius DSR1) of the intermediate compact 6 is reduced to the product shoulder radius PSR (corresponding to the second die shoulder radius DSR2) of the final product. This means that in the second step, material needs to be supplied to the shoulder 6c of the intermediate compact 6. However, the first die depth DD1 of the first die 3 used in the first step is deeper than the product depth PD of the final product. In other words, the intermediate compact depth MD of the intermediate compact 6 provided in the second step is deeper than the product depth PD of the final product, and the depth of the main body is reduced by the second step. Therefore, in the second step, the material to be supplied to the shoulder 6c of the intermediate body 6 in order to reduce the intermediate body shoulder radius MSR1 of the intermediate body 6 to the product shoulder radius PSR of the final product can be secured by the outflow of material from the main body 6a. In other words, the material to be supplied to the shoulder 6c of the intermediate body 6 in order to reduce the die shoulder radius from the first die shoulder radius DSR1 to the second die shoulder radius DSR2 in the second step is not secured by the inflow of material from the flange 6b. By reducing or eliminating the inflow of material from the flange 6b, the occurrence of wrinkles in the flange 1b of the final product can be prevented.

[0055] As described above, according to the manufacturing method of this embodiment, it is possible to achieve both a sharp and deep shape and a wrinkle-free flange portion 1b.

[0056] Referring to Figure 6A, in the manufacturing method of this embodiment, the change in line length due to reducing the die shoulder radius from the first die shoulder radius DSR1 to the second die shoulder radius DSR2 in the second step, and therefore the difference ΔDD between the first die depth DD1 and the second die depth DD2 (corresponding to the difference in forming depth between the first step and the second step), is expressed by the following equation (1) based on geometric relationships.

[0057]

number

[0058] From this formula (1), when the first die shoulder radius DSR1 is 15 mm and the second die shoulder radius DSR2 is 2 mm, the difference ΔDD between the first die depth D1 and the second die depth DD2 is approximately 5.57 mm.

[0059] Furthermore, from formula (1), the first die depth DD1 is expressed by the following formula (2) using the second die depth DD2, the first die shoulder radius DSR1, and the second die shoulder radius DSR2.

[0060]

number

[0061] The first die depth DD1 is defined by formula (2), but some error occurs in the actual process. Therefore, we conducted a simulation to examine to what extent that error can be tolerated. The results are shown in Figure 6B. As shown in Figure 6B, when the deviation of the forming height in the first process (equal to the first die depth DD1) from the reference value (the value obtained from formula (2)) was in the range of -2.54 mm to +2.42 mm, no wrinkles were generated in the final product.

[0062] In this study, the initial sheet thickness is set to 1.0 mm as mentioned above, and the product corner radius RCR2 of the bottomed rectangular tubular shape (see Figure 1A) is set to 20 mm as mentioned above. In general, wrinkles in cylindrical shapes are affected by the sheet thickness and the size of the corner radius, and the thinner the sheet thickness and the smaller the corner radius, the more likely wrinkles are to occur. Therefore, when forming a bottomed rectangular tubular shape using the results obtained in this study, if the product corner radius RCR2 is 20 mm or more and the blank sheet thickness is 1.0 mm or more, wrinkles will not occur in the flange portion if the forming height in the first process, i.e., the first die depth DD1, satisfies the following formula (3).

[0063]

number

[0064] Here, DD1 is the first die depth, DD2 is the second die depth (forming height of the final product), DSR1 is the first die shoulder radius, and DSR2 is the second die shoulder radius (shoulder radius of the final product). The units in the above formula are "mm".

[0065] The bottomed rectangular tubular part manufactured by the manufacturing method of this embodiment can be used as a battery pack case for an automobile, but the application of the present invention is not limited thereto. The present invention is preferably applied to the manufacture of components that require a reduced maximum dimension and a maximized internal volume in consideration of the surrounding components. Examples of such components include battery pack lids, side door inner panels, converter cases, and other automobile components such as motor cases (bottomed cylindrical containers). [Explanation of symbols]

[0066] 1 Bottomed square cylindrical part (bottomed cylindrical part) 1a Main unit 1b Flange part 1c Product shoulder 2 Blank 3 First Die 3a Dice body 3b Die flange part 3c Die shoulder 4 Holder 5. First Punch 6 Intermediate molding 6a Main unit 6b Flange part 6c Shoulder 7 Second Die 7a Dice body 7b Die flange part 7c Die shoulder 8. Second Punch 8a Punch body 8b Punch flange part 8c Punch shoulder PD Product Depth PSR product shoulder radius PBR product bottom radius PCR1, PCR2, PCR3 Product Corner Radius DSR1 No.1 die shoulder radius DSR2 No. 2 die shoulder radius DD1 First Die Depth DD2 Second Die Depth PUSR1 First punch shoulder radius PUSR1 Second punch shoulder radius PUD1 2nd punch depth PUD2 Second punch depth MSR intermediate body shoulder radius MD Intermediate molding depth

Claims

1. A method for manufacturing a bottomed tubular part including a bottomed tubular main body and a flange portion extending from an opening of the main body, comprising: a first step of obtaining an intermediate formed body from a plate material by drawing using a first die having a first die shoulder radius larger than a product shoulder radius, which is a radius of a connection portion between the main body and the flange portion, and a first die depth deeper than a product depth, which is a depth of the main body; a second step of obtaining the bottomed tubular part from the intermediate formed body by drawing using a second die having a second die shoulder radius equal to the product shoulder radius and a second die depth equal to the product depth; Equipped with A method for manufacturing a bottomed tubular part, wherein a corner radius of the bottomed square tubular shape is 20 mm or more, an initial plate thickness of the blank is 1.0 mm or more, and the first die depth satisfies the following formula.

2. The method for manufacturing a bottomed tubular part according to claim 1 , wherein the plate material is made of aluminum.

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