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 is provided on at least either of a center side of an inner side surface 11a at a longer side extending in a longitudinal direction of the recessed part 1a and a center side of an outside surface 2a extending in the longitudinal direction of the punch 2.SELECTED DRAWING: Figure 1

Description

Technical Field

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

Background Art

[0002] Conventionally, a method for manufacturing a metal housing 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 an extrusion molding die 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 surface of the male die from the gap between the outer surface of the male die and the inner surface of the recess of the female die, and a housing having a bottom surface and a side surface is formed.

Prior Art Document

Patent Document

[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, 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. When a male die having a rectangular shape corresponding to the recess enters the recess and a hollow rectangular parallelepiped-shaped molded body with an open upper part is formed, the material plastically deforms and moves from the center of the recess toward the short side and the long side of the outer surface 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 both the side surface on the long side and the side surface on the short side. Therefore, the amount of material moving along the short side of the male die becomes less than the amount of material moving along the long side, and the speed at which the side wall on the short side is formed becomes slower 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] In order 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 so as to be recessed at least in one of the outer direction on the central side of the inner surface extending in the longitudinal direction of the recess or the inner direction on the central side of the outer surface extending in the longitudinal direction of the punch. The method comprises a step of extruding the object to be a shape along the recess by pressing the object to be extruded using an extrusion mold including these components.

[0008] In the method for manufacturing a metal housing according to the first aspect of the present invention, as described above, using an extrusion die including a recessed portion provided so as to be recessed at least in one of the outer direction on the central side of the inner surface extending in the longitudinal direction of the recess or the inner direction on the central side of the outer surface extending in the longitudinal direction of the punch, the object to be processed is pressed. As a result, on the central side of the inner surface extending in the longitudinal direction of the recess where the speed at which the object to be processed moves increases, or on the central side of the outer surface extending in the longitudinal direction of the punch, since the recessed portion is provided, the thickness of the object to be processed after extrusion molding can be made larger than the case where the recessed portion is not provided. Therefore, for the amount by which the thickness increases, the amount of movement of the object to be processed moving between the inner surface of the recess and the outer surface of the punch during extrusion molding is larger than the case where the recessed portion is not provided, so that the speed at which the object to be processed moves along the inner surface in the longitudinal direction of the recess can be reduced accordingly. As a result, the difference from the speed at which the object to be processed moves along the inner surface in the short side direction of the recess can be reduced, and the generation of tensile stress due to the speed difference can be suppressed, and 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. Further, unlike the case where the configuration for reducing the speed difference is provided on the bottom surface side, since the bottom surface is a flat surface, the pressing force can be uniformly applied to the object to be processed. In this specification, the “rectangular shape” is a concept that includes not only “exact rectangles” but also those that can be said to be “rectangular shapes” when viewed as a whole and does not include squares.

[0009] In the method for manufacturing a metal housing according to the first aspect, preferably, the recessed portion is formed such that the amount of recess increases toward the opposite side to the side where the punch and the die face each other from the short side toward the center side when viewed from the extrusion direction.

[0010] With such a configuration, the amount of the depression can be increased as it goes toward the central side in the longitudinal direction where the moving speed of the object to be processed tends to increase. Therefore, it is possible to adjust the speed on the central side in the longitudinal direction where the moving speed of the object to be processed increases during the extrusion molding process to be decreased. As a result, the difference between the speed at which the object to be processed moves along the inner surface in the longitudinal direction of the concave portion and the speed at which it moves along the inner surface in the short transverse direction of the concave portion can be effectively reduced, so that the generation of tensile stress due to the speed difference can be effectively suppressed.

[0011] In the method for manufacturing a metal housing according to the first aspect, preferably, the recessed portion is formed in an arc shape when viewed from the extrusion direction.

[0012] With such a configuration, unlike the case where the recessed portion is provided linearly and the object to be processed is supplied to the entire recessed portion, the object to be processed can be supplied to the recessed portion from a part of the recessed portion closer to the center in the short transverse direction. Thereby, since the speed at which the object to be processed moves along the inner surface in the longitudinal direction of the concave portion during the extrusion molding process can be decreased, the difference between the speed at which it moves along the inner surface in the longitudinal direction of the concave portion and the speed at which it moves along the inner surface in the short transverse direction of the concave portion can be further reduced.

[0013] In the method for manufacturing a metal housing according to the first aspect, preferably, the end side of the inner surface extending in the longitudinal direction of the concave portion and the end side of the outer surface extending in the longitudinal direction of the punch are formed in a flat surface shape, and the distance between the die and the punch in the recessed portion when viewed from the extrusion direction is formed to be larger than the distance between the inner surface extending in the short transverse direction of the concave portion and the outer surface extending in the short transverse direction of the punch, and the distance between the flat inner surface extending in the longitudinal direction of the concave portion and the flat outer surface extending in the longitudinal direction of the punch at the end side.

[0014] With such a configuration, by reducing the distance between the inner surface extending in the short side direction of the concave portion and the outer surface extending in the short side direction of the punch, and the distance between the flat inner surface extending in the long side direction of the concave portion at the end portion side and the flat outer surface extending in the long side direction of the punch, it is possible to increase the speed at the end portion side where the speed of the object to be processed moving during extrusion molding becomes slow, and by increasing the distance between the die and the punch in the recessed portion when viewed from the extrusion direction, it is possible to decrease the speed at the central side where the speed of the object to be processed moving during extrusion molding becomes fast. As a result, it is possible to easily reduce the difference between the speed at which the object to be processed moves along the inner surface in the short side direction of the concave portion and the speed at which it moves along the long side.

[0015] The extrusion die according to the second aspect of the present invention includes a die having a rectangular concave portion in which a metal object to be extrusion-molded is disposed, a punch having a rectangular shape along the concave portion and pressing the object to be processed disposed in the concave portion to extrude the object to be processed into a shape along the concave portion, and a recessed portion provided so as to be recessed at least in one of the outer direction on the central side of the inner surface extending in the longitudinal direction of the concave portion or the inner direction on the central side of the outer surface extending in the longitudinal direction of the punch.

[0016] In the mold for extrusion molding according to the second aspect of the present invention, as described above, a recessed portion is provided so as to be recessed at least in one of the outer direction on the central side of the inner surface extending in the longitudinal direction of the recess or the inner direction on the central side of the outer surface extending in the longitudinal direction of the punch. As a result, on the central side of the inner surface extending in the longitudinal direction of the recess where the speed at which the object to be processed moves increases, or on the central side of the outer surface extending in the longitudinal direction of the punch, since the recessed portion is provided, the thickness of the object to be processed after extrusion molding becomes larger than when the recessed portion is not provided. Therefore, the amount of movement of the object to be processed moving between the inner surface of the recess and the outer surface of the punch increases by the amount of the increase in thickness, so that the speed at which the object to be processed moves along the inner surface in the longitudinal direction of the recess can be reduced accordingly. As a result, the difference from the speed at which the object to be processed moves along the inner surface in the short-side direction of the recess can be reduced, and the generation of tensile stress due to the speed difference can be suppressed, and 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. Further, unlike the case where the bottom surface side has a configuration for reducing the speed difference, since the bottom surface is a flat surface, the pressing force can be uniformly applied to the object to be processed.

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

[0018] (Additional item 1) In the method for manufacturing a metal housing according to the first aspect and the mold for extrusion molding according to the second aspect, the recessed portions are respectively provided on a pair of outer surfaces extending in the longitudinal direction of a rectangular punch.

[0019] With this configuration, since the recessed portions are provided on a pair of outer surfaces extending in the longitudinal direction of the rectangular punch, the speed of the object to be processed moving between the pair of outer surfaces and the inner surface of the recess during extrusion molding can be reduced. Therefore, the difference between the speed at which the object to be processed moves along the inner surface in the short-side direction of the recess and the speed at which it moves along the inner surface in the longitudinal direction of the recess can be more effectively reduced.

Advantages of the Invention

[0020] According to the present invention, as described above, it is possible to provide a method for manufacturing a metal housing and an extrusion mold that can suppress the occurrence of cracks near the center of the side wall on the long side of the extruded object to be processed.

Brief Description of the Drawings

[0021]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Modes for Carrying Out the Invention

[0022] Hereinafter, embodiments embodying the present invention will be described with reference to the drawings.

[0023] [First Embodiment] With reference to FIGS. 1 to 7, a manufacturing method of the metal housing 1000 and the configuration of the extrusion mold 100 according to the first embodiment will be described.

[0024] 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. The metal housing 1000 houses battery components including a positive electrode foil and a negative electrode foil inside.

[0025] As shown in FIG. 2, the manufacturing method of the metal housing 1000 includes a step of extruding the object to be processed 50 (see FIG. 3) into a shape along the recess 1a (see FIG. 3) by pressing, and a finishing process.

[0026] The step of extruding the object to be processed 50 into a shape along the recess 1a by pressing is a step of extruding the object to be processed into a shape along the recess using the extrusion mold 100. In the step of extruding the object to be processed into a shape along the recess by pressing, a molding machine (not shown) is used.

[0027] As shown in FIGS. 3 and 4, the extrusion mold 100 includes a die 1, a punch 2, and a recessed portion 3. The die 1 and the punch 2 are attached to a molding machine (not shown). 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 placed 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. Also, the extrusion direction in the drawing is indicated by a black arrow.

[0028] 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.

[0029] The die 1 has a rectangular parallelepiped shape with an open upper portion. 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 placed on the bottom surface (the surface on the Z1 side) of the concave portion 1a. The inner surface 11a extending in the longitudinal direction of the concave portion 1a and the inner surface 11b extending in the short-side direction are 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 that includes not only an "exact rectangular parallelepiped" but also those that can be said to have a "rectangular parallelepiped shape" when viewed as a whole. Also, the "rectangular shape" is a concept that includes not only an "exact rectangle" but also those that can be said to have a "rectangular shape" when viewed as a whole and does not include a square.

[0030] The punch 2 is formed in a rectangular parallelepiped shape. 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.

[0031] As shown in FIG. 4, in a state where the punch 2 is inserted into the concave portion 1a, a gap is formed between the inner surface 11a extending in the longitudinal direction 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.

[0032] The recessed portion 3 is provided on the outer surface 2a extending in the longitudinal direction of the punch 2. The position where the recessed portion 3 is provided is on the central side of the outer surface 2a in the longitudinal direction of the punch 2. The recessed portion 3 has an arc shape when viewed from the extrusion direction. The recessed portion 3 is configured to be recessed in the outer direction of the inner surface 11a extending in the longitudinal direction of the concave portion 1a. The recessed portion 3 is provided on each of a pair of outer surfaces 2a extending in the longitudinal direction of the rectangular punch 2. The recessed portion 3 is provided along the extrusion direction from the upper surface to the bottom surface.

[0033] The recessed portion 3 is formed such that the amount of recess increases in the direction opposite to the side where the punch 2 and the die 1 face each other as it goes from the short side to the central side when viewed from the extrusion direction. For example, it is configured such that the amount of recess is maximum at the center in the longitudinal direction. The amount of recess may be appropriately selected and may be smaller than half the length of the punch 2 in the short direction. Also, at the center C in the longitudinal direction, the recessed portion 3 is configured such that the amount of recess is maximum.

[0034] The end side of the inner surface 11a extending in the longitudinal direction of the recess 1a and the end side of the outer surface 2a extending in the longitudinal direction of the punch 2 are formed in a flat surface shape. When viewed from the extrusion direction, the distance t1 between the die 1 and the punch 2 in the recess 3 is larger than the distance t2 between the inner surface 11b extending in the short-side direction of the recess 1a and the outer surface 2a extending in the short-side direction of the punch 2, and the distance t2 between the flat inner surface 11a extending in the longitudinal direction of the recess 1a and the flat outer surface 2a extending in the longitudinal direction of the punch 2 at the end side. For example, the distance t1 between the die 1 and the punch 2 in the recess 3 when viewed from the extrusion direction is 1 mm, and the distance t2 between the inner surface 11b extending in the short-side direction of the recess 1a and the outer surface 2a extending in the short-side direction of the punch 2, and the distance t2 between the flat inner surface 11a extending in the longitudinal direction of the recess 1a and the flat outer surface 2a extending in the longitudinal direction of the punch 2 at the end side are set to be 0.5 mm. Note that the end side in the longitudinal direction refers to the side close to the short side in the longitudinal direction and does not refer to a specific range. For example, the range from the corner of the rectangle to one-fourth of the long side in the longitudinal direction may be defined as the end side, or the range from the corner of the rectangle to one-third of the long side in the longitudinal direction may be defined as the end side.

[0035] The length t5 of the central portion of the outer surface 2a extending in the longitudinal direction where the recess 3 of the punch 2 is provided is larger than the length t3 of the outer surface 2a extending in the short-side direction and the length t4 of the end side of the outer surface 2a extending in the longitudinal direction. Also, a corner portion is formed at the boundary between the flat surface of the punch 2 and the recess 3.

[0036] In the step of extrusion molding the object 50 into a shape along the recess 1a by pressing the object 50, the object 50 is placed in the recess 1a of the die 1, and the punch 2 is inserted into the recess 1a of the die 1 so that the bottom surface of the punch 2 presses the object 50. The speed of pressing by the punch 2 is not particularly limited. As an example, the speed of pressing by the punch is 20 spm (shots per minute) or more and 40 spm or less. The extruded object 50 is taken out of the recess 1a of the die 1 together with the punch 2. Then, by removing the object 50 from the punch 2, a metal housing 1000 having a thick portion formed along the recessed portion 3 is manufactured. Also, 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.

[0037] The finishing process includes ironing to equalize the thickness of the pressed object 50. At this time, the size (thickness) of the thick portion formed along the recessed portion 3 of the extrusion mold 100 is reduced to equalize the thickness. Also, the height variation caused by the difference in the moving speed of the object 50 is equalized. Ironing is a process of further pressing (squeezing) the object. Also, in the finishing process, polishing may be performed.

[0038] As shown in FIG. 5, the object 50 moves in the short-side direction and the longitudinal direction from the center as indicated by the arrow. When moving in the short-side direction, the object 50 has 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.

[0039] By providing the recessed portion 3, the speed at which the object 50 to be processed moves toward the inner surface 11a in the longitudinal direction of the concave portion 1a can be reduced. Specifically, the object 50 to be processed that moves to the long side of the inner surface 11a in the longitudinal direction of the concave portion 1a has a greater thickness according to the amount of recess of the recessed portion 3, so it takes more time compared to the case where the object 50 to be processed moves along a flat surface. As a result, the speed of the object 50 to be processed moving to the long side is reduced, and the difference between the speed of the object 50 to be processed moving to the long side and the speed of the object to be processed moving to the short side can be reduced.

[0040] Based on FIGS. 6 and 7, the speed of the object 50 to be processed moving between the inner surface 11a extending in the longitudinal direction of the concave portion 1a and the outer surface 2a of the punch 2 will be described. In FIGS. 4 and 5, the moving speed of the object 50 to be processed moving between the inner surface 11a extending in the longitudinal direction of the concave portion 1a and the outer surface 2a of the punch 2 is divided into six levels. Note that the first level with fine hatching has the highest speed, and the speed decreases as the width of the hatching and the numbers increase, and the sixth level has the lowest speed.

[0041] FIG. 6 shows the moving speed of the object 50 to be processed when the object 50 to be processed is extrusion-molded using an extrusion mold of a comparative example without a recessed portion. In the case of the comparative example, the speed at the end side in the longitudinal direction is the third level out of six levels, and the first or second level at the center side in the longitudinal direction. That is, the speed is higher at the center side than at the end side in the longitudinal direction. Also, at the center side in the longitudinal direction, since the speed is high, the height of the object 50 to be processed in the Z direction is larger than the height in the Z direction of other parts, and it has a mountain shape.

[0042] In the case of the example using the extrusion die 100 of the first embodiment shown in FIG. 7, the speed was at the third or fourth stage on the central side in the longitudinal direction, and the speed was at the fourth stage on the end side in the longitudinal direction. Therefore, it was found that the speed on the central side in the longitudinal direction was lower than that in the comparative example. Further, unlike the comparative example, since the speed on the central side in the longitudinal direction was lower, the height in the Z direction on the central side in the longitudinal direction was reduced. As a result, it is considered that the speed difference between the longitudinal direction and the lateral direction is reduced, and the occurrence of cracks can be suppressed.

[0043] (Effect of the First Embodiment) In the first embodiment, the following effects can be obtained.

[0044] In the first embodiment, as described above, the object 50 is pressed using the extrusion die 100 including the recessed portion 3 provided so as to be recessed at least in one of the outer direction on the central side of the inner surface 11a extending in the longitudinal direction of the recess 1a or the inner direction on the central side of the outer surface 2a extending in the longitudinal direction of the punch 2. Thereby, on the central side of the inner surface 11a extending in the longitudinal direction of the recess 1a where the speed at which the object 50 moves increases, or on the central side of the outer surface 2a extending in the longitudinal direction of the punch 2, since the recessed portion 3 is provided, the thickness of the object 50 after extrusion molding can be made larger than the case where the recessed portion 3 is not provided. Therefore, as the thickness increases, the amount of movement of the object 50 moving between the inner surface 11a of the recess 1a and the outer surface 2a of the punch 2 during extrusion molding increases, and accordingly, the speed at which the object 50 moves along the inner surface in the longitudinal direction of the recess 1a can be reduced. As a result, the difference from the speed at which the object 50 moves along the inner surface 11b in the lateral direction of the recess 1a can be reduced, the generation of tensile stress due to the speed difference can be suppressed, and the occurrence of cracks near the center of the side wall on the long side of the extruded object 50 can be suppressed. Further, compared with the case where the bottom surface side is provided with a configuration for reducing the speed difference, since the bottom surface is a flat surface, the pressing force can be uniformly applied to the object.

[0045] Also, in the first embodiment, as described above, the recessed portion 3 is formed such that the amount of recess increases toward the side opposite to the side where the punch 2 and the die 1 face each other from the short side toward the center side when viewed in the extrusion direction. Thereby, since the amount of recess can be increased toward the center side in the longitudinal direction where the moving speed of the object 50 tends to increase, the speed on the center side in the longitudinal direction where the moving speed of the object 50 tends to increase during extrusion molding can be adjusted to be small. As a result, the difference between the speed at which the object 50 moves along the inner surface 11a extending in the longitudinal direction of the concave portion 1a and the speed at which the object 50 moves along the inner surface 11b in the short side direction of the concave portion 1a can be effectively reduced, so that the generation of tensile stress due to the speed difference can be effectively suppressed.

[0046] Also, in the first embodiment, as described above, the recessed portion 3 is formed in an arc shape when viewed in the extrusion direction. Thereby, unlike the case where the recessed portion 3 is provided linearly and the object 50 is supplied to the entire recessed portion 3, the object 50 can be supplied to the recessed portion 3 from a part of the recessed portion 3 close to the center in the short side direction. As a result, the speed at which the object 50 moves along the inner surface 11a extending in the longitudinal direction of the concave portion 1a during extrusion molding can be reduced, so that the difference between the speed at which the object 50 moves along the inner surface 11a in the longitudinal direction of the concave portion 1a and the speed at which the object 50 moves along the inner surface 11a on the long side side in the short side direction of the concave portion 1a can be further reduced.

[0047] Also, in the first embodiment, as described above, the end portion side of the inner surface 11a on the long side extending in the longitudinal direction of the recess 1a and the end portion side of the outer surface 2a extending in the longitudinal direction of the punch 2 are formed in a flat surface shape. When viewed from the extrusion direction, the distance between the die 1 and the punch 2 in the recessed portion 3 is larger than the distance between the inner surface 11a on the long side extending in the short direction of the recess 1a and the outer surface 2a extending in the short direction of the punch 2, and the distance between the flat inner surface 11a on the long side extending in the longitudinal direction of the recess 1a and the flat outer surface 2a extending in the longitudinal direction of the punch 2 at the end portion side. Thereby, by reducing the distance between the inner surface 11b extending in the short direction of the recess 1a and the outer surface 2a extending in the short direction of the punch 2, and the distance between the flat inner surface 11a on the long side extending in the longitudinal direction of the recess 1a and the flat outer surface 2a extending in the longitudinal direction of the punch 2 at the end portion side, it is possible to increase the speed of the end portion side where the speed of movement of the object 50 during extrusion molding becomes slow, and by increasing the distance between the die 1 and the punch 2 in the recessed portion 3 when viewed from the extrusion direction, it is possible to reduce the speed of the central side where the speed of movement of the object 50 during extrusion molding becomes large. As a result, it is possible to easily reduce the difference between the speed at which the object 50 moves along the inner surface 11a on the long side in the short direction of the recess 1a and the speed at which it moves along the long side.

[0048] In the first embodiment, as described above, the recessed portion 3 is provided so as to be recessed in at least one of the outer direction on the central side of the inner surface 11a extending in the longitudinal direction of the recess 1a or the inner direction on the central side of the outer surface 2a extending in the longitudinal direction of the punch 2. As a result, on the central side of the inner surface 11a extending in the longitudinal direction of the recess 1a where the speed at which the object 50 to be processed moves increases, or on the central side of the outer surface 2a extending in the longitudinal direction of the punch 2, since the recessed portion 3 is provided, the thickness of the object 50 after extrusion molding becomes larger than when the recessed portion 3 is not provided. Therefore, by the amount of the increased thickness, the amount of movement of the object 50 moving between the inner surface 11a of the recess 1a and the outer surface 2a of the punch 2 is increased, so that the speed at which the object 50 moves along the inner surface in the longitudinal direction of the recess 1a can be reduced accordingly. As a result, the difference from the speed at which the object 50 moves along the inner surface 11b in the short side direction of the recess 1a can be reduced, and the generation of tensile stress due to the speed difference can be suppressed, and the occurrence of cracks near the center of the side wall on the long side of the extruded object 50 can be suppressed. Further, compared with the case of having a configuration for reducing the speed difference on the bottom surface side, since the bottom surface is a flat surface, the pressing force can be uniformly applied to the object to be processed.

[0049] Also, in the first embodiment, as described above, the recessed portions 3 are respectively provided on a pair of outer surfaces 2a extending in the longitudinal direction of the rectangular punch 2. As a result, since the recessed portions 3 are provided on a pair of outer surfaces 2a extending in the longitudinal direction of the rectangular punch 2, the speed of the object 50 to be processed moving between the pair of outer surfaces 2a and the inner surface 11a on the long side of the recess 1a during extrusion molding can be reduced. Therefore, the difference between the speed at which the object 50 moves along the inner surface 11a on the long side in the short side direction of the recess 1a and the speed at which it moves along the inner surface 11a extending in the longitudinal direction of the recess 1a can be more effectively reduced.

[0050] [Second Embodiment] Referring to FIGS. 8 and 9, the configuration of the die 200 for extrusion molding according to the second embodiment will be described. In the second embodiment, instead of the punch 202, the die 201 is provided with a recess 203. In addition, in the second embodiment, detailed descriptions of the same configurations as those in the first embodiment are omitted.

[0051] As shown in FIG. 8, in the second embodiment, the punch 202 is not provided with a recess 203, and all outer surfaces 202a are flat surfaces. The punch 202 has a rectangular parallelepiped shape.

[0052] The recess 203 is provided on the inner surface 211a on the long side extending in the longitudinal direction of the concave portion 201a of the die 201. The recess 203 is provided so as to recess inward on the central side of the inner surface 211a on the long side extending in the longitudinal direction of the concave portion 201a of the die 201.

[0053] As shown in FIG. 9, the recesses 203 are respectively provided on a pair of inner surfaces 211a extending in the longitudinal direction that form the concave portion 201a. The amount of depression of the recess 203 is formed so as to increase from the short side toward the central side when viewed from the extrusion direction. Also, at the longitudinal center C, the amount of depression of the recess 203 is configured to be maximum.

[0054] When viewed from the extrusion direction, the distance t1a between the inner surface 211a on the long side in the central portion in the longitudinal direction of the concave portion 201a and the outer surface 202a of the punch 202 is larger than the distance t2 between the inner surface 211b extending in the short direction of the concave portion 201a and the outer surface 202a extending in the short direction of the punch 2, and the distance between the flat inner surface 211a extending in the longitudinal direction of the concave portion 201a and the flat outer surface 202a extending in the longitudinal direction of the punch 2 at the end portion side. In the second embodiment, the object 50 is formed in a shape in which the central side in the longitudinal direction of the outer surface 202a protrudes along the recess 203. In addition, other configurations of the second embodiment are the same as those of the first embodiment.

[0055] (Effects of the Second Embodiment) In the second embodiment, similarly to the first embodiment, using an extrusion mold 200 including a recessed portion 203 provided so as to be recessed at least in one of the outer direction on the central side of the inner surface 211a on the long side extending in the longitudinal direction of the recess 201a or the inner direction on the central side of the outer surface 202a extending in the longitudinal direction of the punch 202, the object 50 to be processed is pressed. As a result, on the central side of the inner surface 211a on the long side extending in the longitudinal direction of the recess 201a where the speed at which the object 50 to be processed moves increases, or on the central side of the outer surface 202a extending in the longitudinal direction of the punch 202, since the recessed portion 203 is provided, the thickness of the object 50 to be processed after extrusion molding can be made larger than when the recessed portion 203 is not provided. Therefore, for the increased thickness, compared with the case where the recessed portion 203 is not provided, the amount of movement of the object 50 to be processed moving between the inner surface 211a of the recess 201a and the outer surface 202a of the punch 2 during extrusion molding increases, and thus the speed at which the object 50 to be processed moves along the inner surface in the longitudinal direction of the recess 201a can be reduced. As a result, the difference from the speed at which the object 50 to be processed moves along the inner surface 211b in the short side direction of the recess 201a can be reduced, and generation of tensile stress due to the speed difference can be suppressed, and occurrence of cracks near the center of the side wall on the long side of the extruded object 50 to be processed can be suppressed. Further, compared with the case where the bottom surface side is provided with a configuration for reducing the speed difference, since the bottom surface is a flat surface, the pressing force can be uniformly applied to the object to be processed. Note that other effects of the second embodiment are the same as those of the first embodiment.

[0056] [Third Embodiment] With reference to FIGS. 10 and 11, the configuration of an 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 is formed in a tapered shape when viewed from the extrusion direction. Note that in the third embodiment, detailed description of the same configuration as that of the first embodiment will be omitted.

[0057] As shown in Fig. 10, in the third embodiment, a recessed portion 303 is provided in the punch 302. The recessed portion 303 is provided on the central side of the outer side surfaces 302a on the pair of long sides of the punch 302. The end sides of the outer side surfaces 302a on the long sides of the punch 302 are flat surfaces. The recessed portion 303 is provided with an inclined surface such that the distance between the inner side surface 311a on the long side of the recessed portion 301a and the outer side surface 302a of the punch 302 gradually increases from the end side in the longitudinal direction of the punch 302 toward the central portion. Also, on the central side, a region where the distance between the inner side surface 311a extending in the long side direction of the recessed portion 301a and the outer side surface 302a extending in the long side direction of the punch 2 is maximized is formed linearly. The inclination angle of the inclined surface is not particularly limited. Also, at the center C in the longitudinal direction, the recess amount of the recessed portion 303 is configured to be maximized.

[0058] As shown in Fig. 11, when viewed from the extrusion direction, the distance t1b between the inner side surface 311a on the long side of the recessed portion 301a and the outer side surface 302a of the punch 302 at the central portion in the longitudinal direction is formed larger than the distance t2 between the inner side surface 311b extending in the short side direction of the recessed portion 301a and the outer side surface 302a extending in the short side direction of the punch 302, and also larger than the distance t2 between the inner side surface 311a extending in the long side direction of the recessed portion 301a and the flat outer side surface 302a extending in the longitudinal direction of the punch 302 at the end side. In the third embodiment, the object 50 is formed in a shape in which the central side in the longitudinal direction of the outer side surface 302a protrudes inward along the recessed portion 303. Other configurations of the third embodiment are the same as those of the first embodiment.

[0059] (Effects of the Third Embodiment) In the third embodiment, similar to the first embodiment, the object 50 is pressed using an extrusion mold 300 including a recessed portion 303 provided so as to be recessed in at least one of the outer direction on the central side of the inner surface 311a on the long side extending in the longitudinal direction of the recess 301a or the inner direction on the central side of the outer surface 302a extending in the longitudinal direction of the punch 302. As a result, on the central side of the inner surface 311a on the long side extending in the longitudinal direction of the recess 301a where the speed at which the object 50 moves increases, or on the central side of the outer surface 302a extending in the longitudinal direction of the punch 302, since the recessed portion 303 is provided, the thickness of the object 50 after extrusion molding can be made larger than when the recessed portion 303 is not provided. Therefore, for the amount by which the thickness increases, compared with the case where the recessed portion 303 is not provided, 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 during extrusion molding increases, so that the speed at which the object 50 moves along the inner surface in the longitudinal direction of the recess 301a can be reduced accordingly. As a result, the difference from the speed at which the object 50 moves along the inner surface 311b in the short side direction of the recess 301a can be reduced, and 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 50. Further, compared with the case where the bottom surface side is provided with a configuration for reducing the speed difference, since the bottom surface is a flat surface, the pressing force can be applied to the object uniformly. Note that other effects of the third embodiment are the same as those of the first embodiment.

[0060] [Fourth Embodiment] With reference to FIGS. 12 and 13, the configuration of an extrusion mold 400 according to the fourth embodiment will be described. In the fourth embodiment, the recessed portion 403 is provided in the die 401 and is formed in a tapered shape when viewed from the extrusion direction. Note that in the fourth embodiment, detailed description of the same configuration as that of the first embodiment will be omitted.

[0061] As shown in FIG. 12, in the fourth embodiment, a recessed portion 403 is provided in the die 401. The recessed portion 403 is provided on each of a pair of long sides that form the concave portion 401a of the die 401. An inclined surface is provided such that the distance between the inner surface 411a extending in the long side direction of the concave portion 401a from the end side in the longitudinal direction of the die 401 toward the central portion and the outer surface 402a extending in the long side direction of the punch 402 gradually increases. Also, on the central side, a region where the distance between the inner surface 411a extending in the long side direction of the concave portion 401a and the outer surface 402a extending in the long side direction of the punch 402 is maximized is formed linearly. The inclination angle of the inclined surface is not particularly limited. Also, at the longitudinal center C, the recessed portion 403 is configured such that the amount of recess is maximized.

[0062] As shown in FIG. 13, when viewed from the extrusion direction, the distance t1c between the inner surface 411a extending in the long side direction of the concave portion 401a at the central portion in the longitudinal direction and the outer surface 402a extending in the long side direction of the punch 402 is formed to be larger than the distance t2 between the inner surface 411b extending in the short side direction of the concave portion 401a and the outer surface 402a extending in the short side direction of the punch 402, and also larger than the distance t2 between the flat inner surface 411a extending in the longitudinal direction of the concave portion 401a and the flat outer surface 402a extending in the longitudinal direction of the punch 402 at the end side. In the fourth embodiment, the object 50 is formed in a shape in which the central side in the longitudinal direction of the outer surface 402a protrudes outward along the recessed portion 403. Other configurations of the fourth embodiment are the same as those of the first embodiment.

[0063] (Effect of the Fourth Embodiment) In the fourth embodiment, in the same manner as in the first embodiment, using the extrusion mold 400 including the recessed portion 403 provided so as to be recessed at least in one of the outer direction on the central side of the inner surface 411a extending in the longitudinal direction of the recess 401a or the inner direction on the central side of the outer surface 402a extending in the longitudinal direction of the punch 402, the object 50 is pressed. As a result, on the central side of the inner surface 411a on the long side extending in the longitudinal direction of the recess 401a where the speed at which the object 50 moves increases, or on the central side of the outer surface 402a extending in the longitudinal direction of the punch 2, since the recessed portion 403 is provided, the thickness of the object 50 after extrusion molding can be made larger than the case where the recessed portion 403 is not provided. Therefore, by the amount of increase in thickness, compared with the case where the recessed portion 403 is not provided, the moving amount of the object 50 moving between the inner surface 411a of the recess 401a and the outer surface 402a of the punch 402 during extrusion molding increases, so that the speed at which the object 50 moves along the inner surface in the longitudinal direction of the recess 401a can be reduced accordingly. As a result, the difference from the speed at which the object 50 moves along the inner surface 411b in the short side direction of the recess 401a can be reduced, and the generation of tensile stress due to the speed difference can be suppressed, and the occurrence of cracks near the center of the side wall on the long side of the extruded object 50 can be suppressed. Further, compared with the case of having a configuration for reducing the speed difference on the bottom surface side, since the bottom surface is a flat surface, the pressing force can be uniformly applied to the object. Note that other effects of the fourth embodiment are the same as those of the first embodiment.

[0064] [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 claims, and further includes all changes (modification examples) within the meaning and scope equivalent to the claims.

[0065] For example, in the above first to fourth embodiments, an example in which the metal housing is used for the battery housing is shown, but the present invention is not limited to this. In the present invention, the metal housing may be used for box-shaped products including tool boxes and the like.

[0066] In addition, 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 has been shown. However, 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.

[0067] In addition, in the first to fourth embodiments described above, an example in which a corner portion is formed at the boundary between the flat surface and the recessed portion has been shown. However, the present invention is not limited to this. In the present invention, the boundary between the flat surface and the recessed portion may be formed in an arc shape. Thereby, the object to be processed can be moved smoothly.

[0068] In addition, in the first to fourth embodiments described above, an example in which the flat surface and the recessed portion are formed on at least one long side of the die or the punch has been shown. However, the present invention is not limited to this. In the present invention, the recessed portion may be formed on the entire length of at least one long side of the die or the punch.

[0069] In addition, in the first to fourth embodiments described above, an example in which the recessed portion is formed on at least one pair of long sides of the die or the punch has been shown. However, the present invention is not limited to this. In the present invention, the recessed portion may be formed on one of at least one pair of long sides of the die or the punch.

[0070] In addition, in the third and 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 has been shown. However, the present invention is not limited to this. In the present invention, the recessed portion may be composed of a surface extending along the short side direction and a surface extending along the long side direction without having an inclined surface.

Explanation of Reference Numerals

[0071] 1,201,301,401 ··· dies, 1a,201a,301a,401a ··· recesses, 2,202,302,402 ··· punches, 2a,202a,302a,402a ··· outer surfaces, 3,202,303,403 ··· depressions, 11a,211a,311a,411a: inner surfaces, 50 ··· object to be processed, 100,200,300,400 ··· extrusion molds

Claims

1. A method for manufacturing a metal housing, comprising the step of pressing a metal object to be extruded, which is disposed in a die having a rectangular recess when viewed from the extrusion direction, with a punch having a rectangular shape along the recess and pressing the object disposed in the recess, using an extrusion mold including a recessed portion provided so as to be recessed at least in one of an outer direction on a central side of an inner surface extending in a longitudinal direction of the recess or an inner direction on a central side of an outer surface extending in a longitudinal direction of the punch, to extrude the object into a shape along the recess.

2. The method for manufacturing a metal housing according to claim 1, wherein the recessed portion is formed such that a recess amount of the recessed portion recesses toward a side opposite to a side where the punch and the die face each other as it goes from a short side toward a central side when viewed from the extrusion direction.

3. The method for manufacturing a metal housing according to claim 1, wherein the recessed portion is formed in an arc shape when viewed from the extrusion direction.

4. End portions of an inner surface extending in a longitudinal direction of the recess and end portions of an outer surface extending in a longitudinal direction of the punch are formed in a flat surface shape, and a distance between the die and the punch in the recessed portion when viewed from the extrusion direction is formed to be larger than a distance between an inner surface extending in a short direction of the recess and an outer surface extending in a short direction of the punch, and a distance between the flat inner surface extending in the longitudinal direction of the recess and the flat outer surface extending in the longitudinal direction of the punch at the end portion side. The method for manufacturing a metal housing according to claim 1.

5. An extrusion mold, comprising 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 to extrude the object into a shape along the recess, and a recessed portion provided so as to be recessed at least in one of an outer direction on a central side of an inner surface extending in a longitudinal direction of the recess or an inner direction on a central side of an outer surface extending in a longitudinal direction of the punch.

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