Manufacturing method for metallic enclosure and die for extrusion

Abstract

To provide a manufacturing method for a metallic enclosure that can suppress cracks from occurring in the vicinity of a center of a side wall on a longer side of an extrusion target object.SOLUTION: A manufacturing method for a metallic enclosure according to the present invention presses a target object by using a die for extrusion including: a die 1 on which a metallic target object 50 to be extruded is arranged, and which has a recessed part 1a in a rectangular shape when viewed from an extruding direction; a punch 2 having a rectangular shape along the recessed part 1a, which extrudes the target object 50 into a shape along the recessed part 1a, by pressing the target object 50 arranged on the recessed part 1a; and a dent part 3 that extends along an extending direction of a longer side, and that is provided in a central part in a longitudinal direction of at least either of a bottom surface 2b which is a surface pressing the target object 50, of the punch 2, or an inner bottom surface 11b on which the target object 50 on the recessed part 1a is arranged.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a metal casing and a die for extrusion molding, and particularly to a method for manufacturing a metal casing provided with a die and a punch and a die for extrusion molding.

Background Art

[0002] Conventionally, a method for manufacturing a metal casing provided with a die and a punch and a die for extrusion molding have been known (see, for example, Patent Document 1).

[0003] Patent Document 1 discloses a die for extrusion molding including a female die having a recess for placing a material and a male die having an outer diameter smaller than the inner diameter of the recess of the female die. In Patent Document 1, the material is placed in the recess of the female die and pressed by the male die, so that the material is plastically deformed and moves along the outer peripheral surface of the male die from the gap between the outer peripheral surface of the male die and the inner side surface of the recess of the female die, and a casing having a bottom surface and a side surface is formed.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Although not disclosed in the above Patent Document 1, when the recess of the female die (die) of the extrusion mold has a rectangular shape with a long side and a short side in plan view, and a male die having a rectangular shape corresponding to the recess enters the recess to form a hollow rectangular parallelepiped-shaped molded body with an open upper part, the material plastically deforms and moves from the center of the recess toward both the short-side and long-side outer surfaces of the male die (punch). At this time, on the bottom surface of the male die that first contacts the material, near the center of the long side, the pressed material moves toward the outer surface on the near long-side. On the other hand, on the bottom surface of the male die, at both ends of the long side near the short side, the pressed material moves so as to disperse toward the side surface on the long-side and the side surface on the short-side. Therefore, the amount of material moving along the long side of the male die becomes larger than the amount of material moving along the short side, and the speed at which the side wall on the long side is formed becomes larger than the speed at which the side wall on the long side is formed. Due to the occurrence of such a speed difference, there is a problem that the material moving from the center of the recess toward the long side and the material moving from the center of the recess toward the short side pull against each other, and a crack occurs near the center of the side wall on the long side of the extruded material.

[0006] This invention has been made to solve the above problems, and one object of this invention is to provide a method for manufacturing a metal casing and an extrusion mold capable of suppressing the occurrence of cracks near the center of the side wall on the long side of the extruded object.

Means for Solving the Problems

[0007] To achieve the above object, a method for manufacturing a metal casing according to a first aspect of this invention includes a die having a rectangular recess when viewed from the extrusion direction, in which a metal object to be extruded is disposed, a punch having a rectangular shape along the recess and pressing the object disposed in the recess, and a recess provided at at least one longitudinal center portion of either the bottom surface that is the surface of the punch pressing the object or the inner bottom surface where the object of the recess is disposed, and extending along the direction in which the long side extends. The method includes a step of extruding the object to be pressed into a shape along the recess using an extrusion mold including the recess.

[0008] In the method for manufacturing a metal casing according to the first aspect of the present invention, as described above, at least one of the bottom surface, which is the surface of the punch that presses the object to be processed, or the inner bottom surface where the object to be processed in the concave portion is disposed, is provided at the central portion in the longitudinal direction, and the object to be processed is pressed using an extrusion mold including a recessed portion extending along the direction in which the long side extends, thereby performing an extrusion molding process to form a shape along the concave portion. As a result, compared with the case of moving to the short side of the concave portion, on the central side of the inner surface extending in the longitudinal direction of the concave portion where the moving speed of the object to be processed increases, or on the central side of the outer surface extending in the longitudinal direction of the punch where the moving speed of the object to be processed increases, the object to be processed disperses and flows toward the long side and the inside of the recessed portion. Therefore, the amount of movement of the object to be processed moving between the inner surface of the concave portion and the outer surface of the punch is reduced, and the speed at which the object to be processed moves along the inner surface in the longitudinal direction of the concave portion during extrusion molding can be reduced, so that the difference from the speed at which the object to be processed moves along the inner surface in the short direction of the concave portion can be reduced. As a result, since the generation of tensile stress due to the speed difference during extrusion molding can be suppressed, the occurrence of cracks near the center of the side wall on the long side of the extruded object to be processed can be suppressed. In this specification, the "rectangular shape" is a concept that includes not only an "exact rectangle" but also those that can be said to be "rectangular" when viewed as a whole and does not include a square.

[0009] In the extrusion mold according to the first aspect, preferably, the recessed portion includes at least one of a curved portion formed in an arc shape when viewed from the extrusion direction or a straight portion extending along the longitudinal direction.

[0010] With this configuration, by providing the curved portion, the width of the recessed portion can be increased. For example, by providing a recessed portion having a convex shape toward the center in the longitudinal direction in a top view, the amount of the object to be processed flowing into the recessed portion during extrusion molding becomes larger, and the moving speed of the object to be processed toward the center in the longitudinal direction can be made smaller. In addition, by providing the straight portion, the recessed portion can be easily provided.

[0011] In the die for extrusion molding according to the first aspect, preferably, the recessed portion is formed such that the distance in the short-side direction from the center in the short-side direction to the edge of the recessed portion increases as it goes from the end portion in the longitudinal direction toward the central portion.

[0012] With such a configuration, since it takes time to fill the recessed portion as it goes from the end portion in the longitudinal direction toward the central portion, the speed can be further reduced. As a result, the difference between the moving speed of the object to be processed moving in the short-side direction from the center of the concave portion during extrusion molding and the moving speed of the object to be processed moving in the longitudinal direction can be further reduced.

[0013] In the die for extrusion molding according to the first aspect, preferably, the recessed portion includes at least a curved portion, and the curved portion includes a first curved portion that curves from the central side in the short-side direction toward one long-side and is convex toward the one long-side when viewed from the extrusion direction, and a second curved portion that is opposed to the first curved portion in the short-side direction and curves from the side opposite to the first curved portion toward the other long-side and is convex toward the other long-side, and the interval between the first curved portion and the second curved portion in the short-side direction is formed to increase from the end portion side in the longitudinal direction toward the central portion.

[0014] With such a configuration, since the curved portion protrudes in the longitudinal direction from the central side in the short-side direction, the distance from the protruding end portion of the curved portion to the center in the short-side direction increases, and the amount of the object to be processed flowing into the recessed portion during extrusion molding increases. As a result, the moving speed of the object to be processed moving along the inner surface on the long-side of the concave portion can be made smaller, so that the difference between the moving speed of the object to be processed moving along the inner surface on the long-side of the concave portion and the moving speed of the object to be processed moving along the inner surface on the short-side of the concave portion can be made smaller. Further, since the interval between the first curved portion and the second curved portion in the short-side direction increases from the end portion side in the longitudinal direction toward the central portion, the amount of the object to be processed flowing into the recessed portion during extrusion molding can be increased, so that the moving speed of the object to be processed on the central side in the longitudinal direction where the moving speed of the object to be processed is large can be further reduced.

[0015] The die for extrusion molding in the second aspect of the present invention includes a die having a rectangular recess in which a metal object to be extrusion-molded is disposed, a punch having a rectangular shape along the recess and pressing the object disposed in the recess to extrude the object into a shape along the recess, a bottom surface which is a surface of the punch for pressing the object, or a recess provided at a central portion in the longitudinal direction of at least one of the inner bottom surfaces where the object is disposed in the recess and extending along the direction in which the long side extends.

[0016] In the die for extrusion molding in the second aspect of the present invention, as described above, a recess is provided at a central portion in the longitudinal direction of at least one of the bottom surface which is a surface of the punch for pressing the object, or the inner bottom surface where the object is disposed in the recess and extending along the direction in which the long side extends. As a result, on the central side of the inner surface extending in the longitudinal direction of the recess where the moving speed of the object becomes larger compared to the case of moving to the short side of the recess, or on the central side of the outer surface extending in the longitudinal direction of the punch where the moving speed of the object becomes larger, the object flows dispersedly toward the long side and the inside of the recess. Therefore, the amount of movement of the object moving between the inner surface of the recess and the outer surface of the punch is reduced, and the speed at which the object moves along the inner surface in the longitudinal direction of the recess is reduced, so that the difference from the speed at which the object moves along the inner surface in the short direction of the recess can be reduced. As a result, it is possible to suppress the generation of tensile stress due to the speed difference, and it is possible to suppress the occurrence of cracks near the center of the side wall on the long side of the extruded object. In this specification, the “rectangular shape” includes not only an “exact rectangle” but also those that can be said to be “rectangular” when viewed as a whole and does not include a square.

[0017] In addition, in the manufacturing method of the metal housing in the first aspect and the die for extrusion molding in the second aspect, the following configurations are also conceivable.

[0018] (Additional item 1) In the die for extrusion molding according to the above aspect, the recess is provided at a position spaced from the short side toward the central side in the longitudinal direction.

[0019] With such a configuration, it is possible to suppress the object to be processed located on the short side from flowing into the recessed portion. Therefore, it is possible to suppress the movement speed of the object to be processed from becoming even smaller on the short side where the movement speed of the object to be processed is small.

[0020] (Appended Claim 2) In the die for extrusion molding according to the above-mentioned one aspect, the recessed portion includes an inclined surface provided so that the width, which is the length in the short side direction, becomes smaller from the opening side toward the bottom surface side in the extrusion direction.

[0021] With such a configuration, by providing an inclined surface in the recessed portion, it becomes easy to remove the object to be processed extruded from the punch or the die.

Advantages of the Invention

[0022] According to the present invention, as described above, it is possible to provide a die for extrusion molding of a metal casing capable of suppressing cracks from occurring near the center of the side wall on the long side of the extruded object to be processed.

Brief Description of the Drawings

[0023]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Embodiments for Carrying Out the Invention

[0024] Hereinafter, embodiments embodying the present invention will be described with reference to the drawings.

[0025] [First Embodiment] With reference to FIGS. 1 to 6, a manufacturing method of the metal housing 1000 and the configuration of the die 100 for extrusion molding according to the first embodiment will be described.

[0026] As shown in FIG. 1, the metal housing 1000 has a rectangular parallelepiped shape with an opening. In FIG. 1, the upper surface is open. In the first embodiment, the metal housing 1000 is used as a battery housing. Parts for a battery including a positive electrode foil and a negative electrode foil are accommodated inside the metal housing 1000.

[0027] As shown in FIG. 2, the manufacturing method of the metal housing 1000 includes a step of extruding and molding the object 50 (see FIG. 3) into a shape along the recess 1a (see FIG. 3) by pressing, and a finishing step.

[0028] The step of extruding and molding the object 50 into a shape along the recess 1a by pressing is a step of extruding and molding the object into a shape along the recess using the die 100 for extrusion molding. In the step of extruding and molding the object into a shape along the recess by pressing, a molding machine (not shown) is used.

[0029] As shown in FIGS. 3 and 4, the extrusion mold 100 includes a die 1, a punch 2, and a recessed portion 3. The extrusion mold 100 is used to extrude the object 50 into a shape along the concave portion 1a by pressing the object 50 with the punch 2 in a state where the metal object 50 is disposed on the die 1. Specifically, the pressed object 50 moves (extends) in a direction opposite to the direction in which the gap between the concave portion 1a and the punch 2 is pressed, so that the object 50 is configured to be formed into a shape along the concave portion 1a. In this specification, the extrusion direction is defined as the Z direction, the Z1 direction in the Z direction is the direction in which the object 50 moves, and the Z2 direction, which is the direction opposite to the Z1 direction, is the direction in which the punch 2 presses the object 50. Among the X direction and the Y direction orthogonal to the Z direction, the X direction is the longitudinal direction of the concave portion 1a and the die 1, and the Y direction is the short-side direction of the concave portion 1a and the die 1. The X direction and the Y direction are orthogonal to each other.

[0030] The metal object 50 includes, for example, slag which is a metal plate. The metal constituting the object 50 is, for example, aluminum. Note that the relative size of the object 50 with respect to the concave portion 1a may be larger or smaller than the size shown in FIG. 3.

[0031] The die 1 has a rectangular parallelepiped shape with an open top. The die 1 has a rectangular concave portion 1a when viewed from the extrusion direction (Z direction). The die 1 is configured such that the object 50 is disposed in the concave portion 1a. The inner surface 11a of the concave portion 1a is located on the outer surface side of the die 1 rather than the center of the die 1 when viewed from the extrusion direction. Note that the rectangular parallelepiped shape is a concept including not only an "exact rectangular parallelepiped" but also those that can be said to be "rectangular parallelepiped" when viewed as a whole. Also, the "rectangular shape" is a concept including not only an "exact rectangle" but also those that can be said to be "rectangular shape" when viewed as a whole, but does not include a square.

[0032] The punch 2 is formed in a rectangular parallelepiped shape having an outer surface 2a and a bottom surface 2b. The punch 2 has a shape along the concave portion 1a of the die 1. The punch 2 has a rectangular shape with an area smaller than that of the concave portion 1a when viewed from the extrusion direction. In a state where the punch 2 is inserted into the concave portion 1a, a gap is formed between the inner surface 11a of the concave portion 1a and the outer surface 2a of the punch 2. Through this gap, the object 50 is configured to extend in a direction opposite to the pressing direction. Note that the length of the punch 2 along the extrusion direction is configured to be larger than the length (depth) of the concave portion 1a in the extrusion direction.

[0033] As shown in FIG. 5, in the first embodiment, the recessed portion 3 is provided at the central portion in the longitudinal direction of the bottom surface 2b (the surface on the Z2 side), which is the surface of the punch 2 that presses the object 50. The recessed portion 3 is configured to extend along the direction in which the long side of the punch 2 extends.

[0034] The recessed portion 3 includes a curved portion formed in an arc shape when viewed from the extrusion direction and a straight portion extending along the short side direction. The recessed portion 3 is surrounded by the curved portion and the straight portion, and the curved portion and the straight portion form the edge of the recessed portion 3.

[0035] The curved portion includes a first curved portion 31a and a second curved portion 32a. The first curved portion 31a is convex toward one long side when viewed from the extrusion direction and is configured to curve from the central side (C2 side) in the short side direction toward the long side. The second curved portion 32a faces the first curved portion 31a in the short side direction, is convex toward the other long side, and is configured to curve in a direction opposite to the first curved portion 31a. The curved portion is formed in a gentle curve.

[0036] The distance between the first curved portion 31a and the second curved portion 32a in the short side direction is formed so as to increase from the end side in the longitudinal direction toward the center side. Therefore, the distance t1 at the end side in the longitudinal direction, which is the same as the lengths of the first straight portion 31b and the second straight portion 32b, is the smallest, and the distance t2 at the center C1 in the longitudinal direction is the largest. In other words, in the first straight portion 31b and the second straight portion 32b, the distance from the side extending in the longitudinal direction of the outer surface 2a of the punch 2 to the recessed portion 3 is the largest, and at the center C1 in the longitudinal direction, the distance from the side extending in the longitudinal direction of the outer surface 2a of the punch 2 to the recessed portion 3 is the smallest. As a result, the recessed portion 3 is formed such that the distance t3 from the center C2 in the short side direction to the edge (curved portion) of the recessed portion increases as it goes from the end portion in the longitudinal direction toward the central portion.

[0037] The straight portions include a first straight portion 31b and a second straight portion 32b. The first straight portion 31b is configured to connect one end of the first curved portion 31a extending along the short side direction (Y direction) and one end of the second curved portion 32a. The second straight portion 32b is configured to connect the other end of the first curved portion 31a and the other end of the second curved portion 32a. The first straight portion 31b and the second straight portion 32b are preferably provided away from the short side of the inner surface 11a of the concave portion 1a in order to prevent the object 50 moving along the inner surface 11a on the short side of the concave portion 1a from flowing into the recessed portion 3. Also, the lengths of the first straight portion 31b and the second straight portion 32b provided near the inner surface 11a on the short side of the concave portion 1a are preferably short in order to suppress a decrease in the moving speed of the object 50 moving to the short side.

[0038] The recessed portion 3 is provided at a position spaced apart from the short side toward the central side in the longitudinal direction. The recessed portion 3 is preferably at a greater distance from the short side. Therefore, the first straight portion 31b and the second straight portion 32b are provided away from the short side of the outer surface 2a of the punch 2.

[0039] As shown in FIG. 6, the recessed portion 3 includes an inclined surface 33 provided such that the width, which is the length in the short side direction (Y direction), decreases from the opening side (Z1 side) toward the bottom surface side (Z2 side) in the extrusion direction. The inclination angle of the inclined surface 33 is not particularly limited. In FIG. 6, the inclined surface 33 is formed with a large and gentle inclination angle, but the inclination angle may be less than 90 degrees and may be formed as a steep inclined surface 33.

[0040] As shown in FIG. 2, in the step of extrusion-molding the object 50 to be processed into a shape along the concave portion 1a by pressing the object 50 to be processed, the object 50 to be processed is placed in the concave portion 1a, and the punch 2 is inserted into the concave portion 1a of the die 1 so that the bottom surface of the punch 2 presses the object 50 to be processed. The pressing speed by the punch 2 is not particularly limited. As an example, the pressing speed by the punch is 20 spm (shots per minute) or more and 40 spm or less. The extrusion-molded object 50 to be processed is taken out from the concave portion 1a of the die 1 together with the punch 2. Then, by removing the object 50 to be processed from the punch 2, a metal housing 1000 having a thick portion formed along the recessed portion 3 is manufactured. Further, in the metal housing 1000, the vicinity of the central portion in the longitudinal direction may have a greater height (length in the Z direction) than other portions.

[0041] The finishing process includes ironing to equalize the thickness of the pressed object 50 to be processed. At this time, the size (thickness) of the thick portion formed along the recessed portion 3 of the extrusion die 100 is reduced to equalize the thickness. Also, the height variation caused by the difference in the moving speed of the object 50 to be processed is equalized. The ironing process is a process of further pressing (squeezing) the object to be processed. Further, in the finishing process, polishing may be performed.

[0042] In the first embodiment, the inner bottom surface 11b of the die 1 is a flat surface. Therefore, in the first embodiment, when the object 50 to be processed is extrusion-molded, a protruding portion along the shape of the recessed portion 3 is formed on the inner bottom surface 11b of the extrusion-molded object 50 to be processed.

[0043] The object 50 is placed in the recess 1a of the die 1 and pressed by the punch 2. In the extrusion die 100 of the first embodiment, the object 50 flows (plastically deforms and extends) toward the short side, the long side, and the recess 3. In this case, when flowing toward the short side, there are a portion that moves along the longitudinal direction and a portion that moves in a direction inclined with respect to the longitudinal direction after flowing along the longitudinal direction. In particular, at the end side in the longitudinal direction, it moves in a direction inclined with respect to the longitudinal direction. Therefore, when there is no recess 3, the amount of the object 50 flowing toward the short side becomes smaller than the amount of the object 50 flowing toward the long side. However, in the first embodiment, due to the presence of the recess 3, the object 50 flowing toward the long side can have a portion that flows toward the recess 3 and a portion that flows along the short direction. Thereby, the speed difference between the object 50 flowing toward the short side and the object 50 flowing toward the long side can be suppressed.

[0044] (Effect of the First Embodiment) In the first embodiment, the following effects can be obtained.

[0045] In the first embodiment, as described above, at least one of the bottom surface 2b, which is the surface of the punch 2 that presses the object 50, or the inner bottom surface 11b where the object 50 of the concave portion 1a is disposed, is provided at the central portion in the longitudinal direction, and an extrusion mold 100 including a recessed portion 3 extending along the direction in which the long side extends is used. The object 50 is pressed to perform an extrusion molding process into a shape along the concave portion 1a. As a result, compared with the case of moving to the short side of the concave portion 1a, on the central side of the inner surface 11a extending in the longitudinal direction of the concave portion 1a where the moving speed of the object 50 becomes large, or on the central side of the outer surface 2a extending in the longitudinal direction of the punch 2 where the moving speed of the object 50 becomes large, the object 50 disperses and flows toward the long side and the inside of the recessed portion 3. Therefore, the amount of movement of the object 50 moving between the inner surface 11a of the concave portion 1a and the outer surface 2a of the punch 2 is reduced, and the speed at which the object 50 moves along the inner surface 11a in the longitudinal direction of the concave portion 1a during extrusion molding can be reduced. Thus, the difference from the speed at which the object 50 moves along the inner surface 11a in the short side direction of the concave portion 1a can be reduced. As a result, since the generation of tensile stress due to the speed difference during extrusion molding can be suppressed, the occurrence of cracks near the center of the side wall on the long side of the extruded object 50 can be suppressed. Further, by providing the recessed portion 3 on at least one of the bottom surface 2b, which is the surface of the punch 2 that presses the object 50, or the inner bottom surface 11b where the object 50 of the concave portion 1a is disposed, it is possible to suppress an increase in thickness compared with the case of changing the size of the gap between the inner surface 11a of the concave portion 1a and the outer surface 2a of the punch 2.

[0046] Also, in the first embodiment, as described above, the recessed portion 3 includes at least one of a curved portion formed in an arc shape when viewed from the extrusion direction or a straight portion extending along the longitudinal direction. As a result, by providing the curved portion, the width of the recessed portion 3 can be increased. For example, by providing the recessed portion 3 convex toward the center in the longitudinal direction, the amount of the object 50 flowing into the recessed portion 3 during extrusion molding becomes larger, and the moving speed of the object 50 toward the center in the longitudinal direction can be made smaller. Further, by providing the straight portion, the recessed portion 3 can be easily provided.

[0047] Also, in the first embodiment, as described above, the recessed portion 3 is formed such that the distance in the short-side direction from the center in the short-side direction to the edge of the recessed portion 3 increases as it goes from the end portion in the longitudinal direction toward the central portion. As a result, as it goes from the end portion in the longitudinal direction toward the central portion, it takes time to reach the recessed portion 3 and it takes time to fill the recessed portion 3, so that the speed can be further reduced. Thereby, the difference between the moving speed of the object 50 moving in the short-side direction from the center of the concave portion 1a during extrusion molding and the moving speed of the object 50 moving in the longitudinal direction can be further reduced.

[0048] Also, in the first embodiment, as described above, the recessed portion 3 includes at least a curved portion. The curved portion includes a first curved portion 31a that curves from the central side in the short-side direction toward one long-side and is convex toward the one long-side when viewed from the extrusion direction, and a second curved portion 32a that faces the first curved portion 31a in the short-side direction and curves toward the opposite side of the first curved portion 31a and is convex toward the other long-side. The interval between the first curved portion 31a and the second curved portion 32a in the short-side direction is formed to increase from the end portion side in the longitudinal direction toward the central side. As a result, since the curved portion protrudes in the longitudinal direction from the central side in the short-side direction, the distance from the protruding end portion of the curved portion to the center in the short-side direction increases, and the amount of the object 50 flowing into the recessed portion 3 during extrusion molding increases. Thereby, the moving speed of the object 50 moving along the inner surface 11a on the long-side of the concave portion 1a can be made smaller, so that the difference between the moving speed of the object 50 moving along the inner surface 11a on the long-side of the concave portion 1a and the moving speed of the object 50 moving along the inner surface 11a on the short-side of the concave portion 1a can be made smaller. Also, since the interval between the first curved portion 31a and the second curved portion 32a in the short-side direction increases from the end portion side in the longitudinal direction toward the central side, the amount of the object 50 flowing into the recessed portion 3 during extrusion molding can be increased, so that the moving speed of the object 50 on the central side in the longitudinal direction where the moving speed of the object 50 increases can be further reduced.

[0049] Further, in the first embodiment, as described above, the recessed portion 3 is provided at at least one of the central portions in the longitudinal direction of the bottom surface 2b which is the surface for pressing the object 50 of the punch 2 or the inner bottom surface 11b where the object 50 of the recessed portion 1a is disposed, and extends along the direction in which the long side extends. Thereby, compared with the case of moving to the short side of the recessed portion 1a, on the central side of the inner side surface 11a extending in the longitudinal direction of the recessed portion 1a where the moving speed of the object 50 increases, or on the central side of the outer side surface 2a extending in the longitudinal direction of the punch 2 where the moving speed of the object 50 increases, the object 50 disperses and flows toward the long side and the inside of the recessed portion 3. Therefore, the amount of movement of the object 50 moving between the inner side surface 11a of the recessed portion 1a and the outer side surface 2a of the punch 2 is reduced, and the speed at which the object 50 moves along the inner side surface 11a in the longitudinal direction of the recessed portion 1a is reduced, so that the difference from the speed at which the object 50 moves along the inner side surface 11a in the short direction of the recessed portion 1a can be reduced. As a result, since the generation of tensile stress due to the speed difference can be suppressed, it is possible to suppress the occurrence of cracks near the center of the side wall on the long side of the extruded object 50. Further, by providing the recessed portion 3 on at least one of the bottom surface 2b which is the surface for pressing the object 50 of the punch 2 or the inner bottom surface 11b where the object 50 of the recessed portion 1a is disposed, it is possible to suppress an increase in thickness compared with the case of changing the size of the gap between the inner side surface 11a of the recessed portion 1a and the outer side surface 2a of the punch 2.

[0050] Further, in the first embodiment, as described above, the recessed portion 3 is provided at a position spaced apart from the short side toward the central side in the longitudinal direction. Thereby, since it is possible to suppress the object 50 located on the short side from flowing into the recessed portion 3, it is possible to suppress a further decrease in the moving speed of the object 50 on the short side where the moving speed of the object 50 is small.

[0051] Further, in the first embodiment, as described above, the recessed portion 3 includes an inclined surface 33 provided so that the width, which is the length in the short side direction, decreases from the opening side toward the bottom surface side in the extrusion direction. By providing the inclined surface 33 in the recessed portion 3, it becomes easier to remove the object 50 extruded from the punch 2 or the die 1.

[0052] [Second Embodiment] With reference to FIGS. 7 and 8, the configuration of the extrusion die 200 according to the second embodiment will be described. In the second embodiment, the recessed portion 203 is provided in the die 201 instead of the punch 202. In the second embodiment, detailed description of the same configuration as that in the first embodiment will be omitted.

[0053] As shown in FIGS. 7 and 8, the recessed portion 203 is provided at the central portion in the longitudinal direction of the inner bottom surface 211b where the object 50 of the concave portion 201a is disposed and extends in the longitudinal direction. The recessed portion 3 includes a curved portion formed in an arc shape when viewed from the extrusion direction and a straight portion extending along the longitudinal direction.

[0054] The curved portion includes a first curved portion 231a and a second curved portion 232a. The first curved portion 231a is convex toward one long side when viewed from the extrusion direction and is configured to curve from the central side in the short side direction toward the long side. The second curved portion 232a faces the first curved portion 231a in the short side direction, is convex toward the other long side, and is configured to curve in the direction opposite to the first curved portion 231a.

[0055] The straight portions include a first straight portion 231b that connects one end of the first curved portion 231a extending along the short side direction (Y direction) and one end of the second curved portion 232a, and a second straight portion 232b that connects the other end of the first curved portion 231a and the other end of the second curved portion 232a. The first straight portion 231b and the second straight portion 232b are preferably provided away from the short side of the inner surface 211a of the concave portion 201a in order to prevent the object 50 to be processed moving along the inner surface 211a on the short side of the concave portion 201a from flowing into the recessed portion 203. Further, the lengths of the first straight portion 231b and the second straight portion 232b provided near the inner surface 211a on the short side of the concave portion 201a are preferably short in order to suppress a decrease in the moving speed of the object 50 to be processed moving to the short side. Note that other configurations of the second embodiment are the same as those of the first embodiment.

[0056] (Effect of the Second Embodiment) In the second embodiment, similar to the first embodiment, a recessed portion 203 is provided at the central portion in the longitudinal direction of at least one of the bottom surface 202b which is the surface of the punch 202 that presses the object 50, or the inner bottom surface 211b where the object 50 of the recess 201a is disposed, and the recessed portion 203 extends along the direction in which the long side extends. The object 50 is pressed using an extrusion mold 200 including the recessed portion 203, thereby performing an extrusion molding process to form a shape along the recess 201a. As a result, compared with the case where the object 50 moves to the short side of the recess 201a, at the central side of the inner surface 211a extending in the longitudinal direction of the recess 201a where the moving speed of the object 50 increases, or at the central side of the outer surface 202a extending in the longitudinal direction of the punch 202 where the moving speed of the object 50 increases, the object 50 disperses and flows toward the long side and the inside of the recessed portion 203. Therefore, the amount of movement of the object 50 moving between the inner surface 211a of the recess 201a and the outer surface 202a of the punch 202 is reduced, and the speed at which the object 50 moves along the inner surface 211a in the longitudinal direction of the recess 201a during extrusion molding can be reduced. Thus, the difference from the speed at which the object 50 moves along the inner surface 211a in the short side direction of the recess 1a can be reduced. As a result, since the generation of tensile stress due to the speed difference during extrusion molding can be suppressed, the occurrence of cracks near the center of the side wall on the long side of the extruded object 50 can be suppressed. Further, by providing the recessed portion 203 on at least one of the bottom surface 202b which is the surface of the punch 202 that presses the object 50, or the inner bottom surface 211b where the object 50 of the recess 201a is disposed, an increase in thickness can be suppressed compared with the case where the size of the gap between the inner surface 211a of the recess 201a and the outer surface 202a of the punch 202 is changed. Note that other effects of the second embodiment are the same as those of the first embodiment.

[0057] [Third Embodiment] With reference to FIGS. 9 and 10, the configuration of the extrusion mold 300 according to the third embodiment will be described. In the third embodiment, the recessed portion 303 is provided in the punch 302 and does not include a curved portion. Note that in the third embodiment, detailed descriptions of the same configurations as those in the first embodiment are omitted.

[0058] As shown in FIGS. 9 and 10, in the third embodiment, the recessed portion 303 is provided on the bottom surface 302b of the punch 302 and is configured to extend in the longitudinal direction. The recessed portion 303 does not include a curved portion and is composed only of straight portions. Specifically, the recessed portion 303 is composed of straight portions including a first straight portion 303a extending in the longitudinal direction, a second straight portion 303b facing the first straight portion 303a, a third straight portion 303c extending in the short-side direction, and a fourth straight portion 303d facing the third straight portion 303c, and has a rectangular shape along the bottom surface 302b of the punch 302.

[0059] The first straight portion 303a and the second straight portion 303b of the recessed portion 303 extend parallel to the long side of the bottom surface 302b of the punch 302. In FIGS. 9 and 10, the first straight portion 303a and the second straight portion 303b of the recessed portion 303 are separated from the longitudinal side of the outer surface 302a of the punch 2, but the first straight portion 303a and the second straight portion 303b of the recessed portion 303 may be provided in the vicinity of the longitudinal side of the punch 2.

[0060] The third straight portion 303c and the fourth straight portion 303d of the recessed portion 303 extend parallel to the short side of the bottom surface 302b of the punch 302. The third straight portion 303c and the fourth straight portion 303d are provided away from the short side of the bottom surface 302b of the punch 302 so that the distance from the short side of the bottom surface 302b of the punch 302 becomes longer. Note that other configurations of the third embodiment are the same as those of the first embodiment.

[0061] (Effect of the Third Embodiment) In the third embodiment, similar to the first embodiment, at least one of the bottom surface 302b, which is the surface of the punch 302 that presses the object 50, or the inner bottom surface 311b where the object 50 of the recess 301a is disposed, is provided at the central portion in the longitudinal direction, and an extrusion mold 300 including a recessed portion 303 extending along the direction in which the long side extends is used. The object 50 is pressed to perform an extrusion molding process into a shape along the recess 301a. As a result, compared with the case of moving to the short side of the recess 301a, on the central side of the inner surface 311a extending in the longitudinal direction of the recess 301a where the moving speed of the object 50 increases, or on the central side of the outer surface 302a extending in the longitudinal direction of the punch 302 where the moving speed of the object 50 increases, the object 50 disperses and flows toward the long side and the inside of the recessed portion 303. Therefore, the amount of movement of the object 50 moving between the inner surface 311a of the recess 301a and the outer surface 302a of the punch 302 is reduced, and the speed at which the object 50 moves along the inner surface 311a in the longitudinal direction of the recess 301a during extrusion molding can be reduced. Thus, the difference from the speed at which the object 50 moves along the inner surface 311a in the short direction of the recess 1a can be reduced. As a result, it is possible to suppress the generation of tensile stress due to the speed difference during extrusion molding, and thus it is possible to suppress the occurrence of cracks near the center of the side wall on the long side of the extruded object 50. Further, by providing the recessed portion 303 on at least one of the bottom surface 302b, which is the surface of the punch 302 that presses the object 50, or the inner bottom surface 311b where the object 50 of the recess 301a is disposed, it is possible to suppress an increase in thickness compared with the case of changing the size of the gap between the inner surface 311a of the recess 301a and the outer surface 302a of the punch 302. Note that other effects of the third embodiment are the same as those of the first embodiment.

[0062] [Fourth Embodiment] Referring to FIGS. 11 and 12, the configuration of the die 400 for extrusion molding according to the fourth embodiment will be described. In the fourth embodiment, the recessed portion 403 is provided in the die 401 instead of the punch 402. Further, the recessed portion 403 does not have a curved portion. In the fourth embodiment, detailed description of the same configuration as that of the first embodiment will be omitted.

[0063] As shown in FIGS. 11 and 12, in the fourth embodiment, a recessed portion 403 is provided in the die 401. The recessed portion 403 is provided on the inner bottom surface 411b of the concave portion 401a of the die 401. The recessed portion 403 is configured to extend along the extending direction of the punch 402. The recessed portion 403 does not include a curved portion and is composed of only a straight portion. Specifically, the recessed portion 403 is composed of a first straight portion 403a extending in the longitudinal direction, a second straight portion 403b facing the first straight portion 403a, a third straight portion 403c extending in the short-side direction, and a fourth straight portion 403d facing the third straight portion 403c, and has a rectangular shape along the inner bottom surface 411b of the concave portion 401a of the die 401.

[0064] The first straight portion 403a and the second straight portion 403b of the recessed portion 403 extend parallel to the long side of the inner bottom surface 411b of the concave portion 401a of the die 401. In FIGS. 11 and 12, the first straight portion 403a and the second straight portion 403b of the recessed portion 403 are away from the longitudinal side of the inner bottom surface 411b of the concave portion 401a, but the first straight portion 403a and the second straight portion 403b of the recessed portion 403 may be provided near the longitudinal side of the inner bottom surface 411b of the concave portion 401a.

[0065] The third straight portion 403c and the fourth straight portion 403d of the recessed portion 403 extend parallel to the short side of the bottom surface 402b of the punch 402. The third straight portion 403c and the fourth straight portion 403d are provided away from the short side of the bottom surface 402b of the punch 402 so that the distance from the short side of the inner bottom surface 411b of the concave portion 401a of the die 401 becomes longer. Note that other configurations of the fourth embodiment are the same as those of the first embodiment.

[0066] (Effects of the Fourth Embodiment) In the fourth embodiment, similar to the first embodiment, at least one of the bottom surface 402b, which is the surface of the punch 402 that presses the object 50, or the inner bottom surface 411b where the object 50 of the concave portion 401a is disposed, is provided at the central portion in the longitudinal direction, and an extrusion die 400 including a recessed portion 403 extending along the direction in which the long side extends is used to press the object 50 to perform an extrusion molding process into a shape along the concave portion 401a. As a result, compared with the case of moving to the short side of the concave portion 401a, on the central side of the inner surface 411a extending in the longitudinal direction of the concave portion 401a where the moving speed of the object 50 increases, or on the central side of the outer surface 402a extending in the longitudinal direction of the punch 402 where the moving speed of the object 50 increases, the object 50 disperses and flows toward the long side and the inside of the recessed portion 403. Therefore, the amount of movement of the object 50 moving between the inner surface 411a of the concave portion 401a and the outer surface 402a of the punch 402 is reduced, and the speed at which the object 50 moves along the inner surface 411a in the longitudinal direction of the concave portion 401a during extrusion molding can be reduced, so that the difference from the speed at which the object 50 moves along the inner surface 411a in the short direction of the concave portion 401a can be reduced. As a result, since the generation of tensile stress due to the speed difference during extrusion molding can be suppressed, the occurrence of cracks near the center of the side wall on the long side of the extruded object 50 can be suppressed. Further, by providing the recessed portion 403 on at least one of the bottom surface 402b, which is the surface of the punch 402 that presses the object 50, or the inner bottom surface 411b where the object 50 of the concave portion 401a is disposed, it is possible to suppress an increase in thickness compared with the case of changing the size of the gap between the inner surface 411a of the concave portion 401a and the outer surface 402a of the punch 402. Note that other effects of the fourth embodiment are the same as those of the first embodiment.

[0067] [Modification Example] The above-described embodiments disclosed this time should be considered as illustrative in all respects and not restrictive. The scope of the present invention is shown not by the description of the above embodiments but by the scope of claims, and further includes all changes (modification examples) within the meaning and scope equivalent to the scope of claims.

[0068] For example, in the first to fourth embodiments described above, an example in which the metal housing is used for the battery housing was shown, but the present invention is not limited to this. In the present invention, the metal housing may be used for a box-shaped product including a toolbox or the like.

[0069] Also, in the first to fourth embodiments described above, an example in which the recessed portion is provided in the recess of the die or the punch was shown, but the present invention is not limited to this. In the present invention, the recessed portion may be provided in both the recess of the die and the punch.

[0070] Also, in the first to fourth embodiments described above, an example in which the recessed portion is formed in a tapered shape having an inclined surface when viewed from the extrusion direction was shown, but the present invention is not limited to this. In the present invention, the recessed portion may be a linear recessed portion along the pressing direction without having an inclined surface.

[0071] Also, in the first and second embodiments described above, an example in which the curved portion is a gentle curve was shown, but the present invention is not limited to this. In the present invention, the curved portion may be a sharp mountain-shaped curve.

[0072] Also, in the first and second embodiments described above, an example in which the curved portion includes a first curved portion and a second curved portion was shown, but the present invention is not limited to this. In the present invention, the curved portion may be only the first curved portion.

[0073] Also, in the first and third embodiments described above, an example in which the recessed portion includes a straight portion was shown, but the present invention is not limited to this. In the present invention, the recessed portion may not include a straight portion. In this case, a third curved portion and a fourth curved portion may be provided, and the recessed portion may be formed in an elliptical shape.

[0074] Also, in the above-described second and fourth embodiments, an example in which the recessed portion includes a third straight portion and a fourth straight portion extending in the short side direction has been shown, but the present invention is not limited thereto. In the present invention, the recessed portion may have only a straight portion extending in the long side direction without including a straight portion extending in the short side direction. In this case, the first straight portion and the second straight portion may be connected by a curved portion that extends in the short side direction and is convex toward the center side.

Explanation of Signs

[0075] 1, 201, 301, 401 ··· Dies, 1a, 201a, 301a, 401a ··· Recessed portions, 2, 202, 302, 402 ··· Punches, 2b, 202b, 302b, 402b ··· Bottom surfaces, 3, 203, 303, 403 ··· Recessed portions, 11a, 211a, 311a, 411a ··· Inner bottom surfaces, 31a, 231a ··· First curved portion (curved portion), 32a, 232a ··· Second curved portion (curved portion), 31b, 231b, 331b, 431b ··· First straight portion (straight portion), 32b, 232b, 332b, 432b ··· Second straight portion (straight portion), 50 ··· Object to be processed, 100, 200, 300, 400 ··· Extrusion molds

Claims

1. A die having a rectangular recess in which a metal object to be extruded is disposed, a punch having a rectangular shape along the recess and pressing the object disposed in the recess, a bottom surface which is a surface of the punch for pressing the object, or at least one of the inner bottom surfaces of the recess where the object is disposed, and a recess provided at a central portion in the longitudinal direction and extending along the direction in which the long side extends. A method for manufacturing a metal housing, comprising a step of extruding the object into a shape along the recess by pressing the object using an extrusion mold including the recess.

2. The method for manufacturing a metal housing according to claim 1, wherein the recess includes at least one of a curved portion formed in an arc shape when viewed from the extrusion direction or a straight portion extending along the longitudinal direction.

3. The method for manufacturing a metal housing according to claim 1, wherein the recess is formed such that the distance in the short direction from the center in the short direction to the edge of the recess increases as it goes from the end portion in the longitudinal direction toward the central portion.

4. The recess includes at least the curved portion, The curved portion includes a first curved portion that curves from the center side in the short direction toward the long side and is convex toward one long side when viewed from the extrusion direction, and a second curved portion that is opposed to the first curved portion in the short direction and curves from the side opposite to the first curved portion toward the other long side and is convex toward the other long side. The method for manufacturing a metal housing according to claim 2, wherein the distance between the first curved portion and the second curved portion in the short direction is formed to increase from the end portion side in the longitudinal direction toward the central portion.

5. A die having a rectangular recess in which a metal object to be extruded is disposed, A punch having a rectangular shape along the recess and pressing the object disposed in the recess to extrude the object into a shape along the recess, A bottom surface which is a surface of the punch for pressing the object, or at least one of the inner bottom surfaces of the recess where the object is disposed, and a recess provided at a central portion in the longitudinal direction and extending along the direction in which the long side extends. An extrusion mold.

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