Microstructure and method for manufacturing microstructure

Abstract

To achieve both miniaturization and breakage avoidance of a structure that is integrally provided on a metal plate.SOLUTION: A method for manufacturing a microstructure 2 includes: installing a metal plate 1 on a lower die 51 of a shearing device 50; and shearing a processing position of the metal plate 1 by an upper die 52 of the shearing device 50 without completely punching out the metal plate 1.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a microstructure and a method for manufacturing the same. [Background technology]

[0002] For example, in the case of a connector, a metal plate may have a minute structure. Patent Document 1 discloses a locking projection and a lance that are provided on the terminal fitting and the connector housing, respectively, and are engageable with each other to prevent the terminal fitting from coming off the connector housing. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-014304 Summary of the Invention [Problem to be solved by the invention]

[0004] The above-mentioned locking protrusion is thought to be integrally formed with the terminal fitting by bulging. When bulging is used to form a microstructure on a metal plate, it is necessary to set a punch draft angle on the structure. In addition, a biaxial stress state occurs in the width direction and the perpendicular direction within the surface of the structure, making the metal plate prone to cracking. In order to set the draft angle and avoid cracking, the width of the structure must be large relative to the amount of protrusion of the structure. As such, conventional methods for manufacturing microstructures have room for improvement in terms of miniaturizing the structures.

[0005] An object of the present invention is to simultaneously achieve miniaturization of a structure integrally provided on a metal plate and avoidance of fracture. [Means for solving the problem]

[0006] One aspect of the present invention provides a method for manufacturing a microstructure, which includes placing a metal plate on a lower mold of a shearing processing device, and shearing the metal plate at a processing position using an upper mold of the shearing processing device without completely punching out the metal plate, thereby forming a protrusion.

[0007] According to the above configuration, a protrusion having approximately the same width as the upper die of the shearing device can be integrally formed on the metal plate by a single shearing process. There is no need to set a draft angle on the upper die, as is the case with bulging processes. Furthermore, because the shearing process is performed below the fracture limit, no fractures, including cracks, occur in the metal plate. When integrating a structure with the metal plate, the width of the structure can be made smaller than the protrusion amount of the structure without causing fractures in the metal plate.

[0008] The processing positions may include a plurality of processing positions repeatedly shifted outward in the width direction of the metal plate, and the method may further comprise repeatedly shifting the processing positions outward in the width direction of the metal plate and performing the shearing processing.

[0009] According to the above configuration, by repeating the shearing process while shifting the processing position in the width direction, it is possible to gradually increase the protrusion amount of the microstructure.

[0010] The manufacturing method may further comprise smoothing out any uneven protrusions caused by the shearing process.

[0011] According to the above-mentioned configuration, the surface of the structure is uneven as a result of the multi-stage shearing process. These unevennesses are smoothed, making the surface of the structure smooth. This reduces stress concentration in the structure, thereby improving the durability of the structure.

[0012] The shearing may be performed at the processing position of the metal plate by a shearing amount of 50% or less of the thickness of the metal plate.

[0013] According to the above configuration, it is possible to achieve shear processing below the breaking limit.

[0014] The metal plate may be a plate made of pure copper or a copper alloy.

[0015] According to the above-mentioned configuration, minute structures can be provided on a plate material made of pure copper or a copper alloy, which can contribute to, for example, increasing the number of poles and reducing the size of connectors.

[0016] One aspect of the present invention provides a microstructure having a shear deformation band formed within a protrusion by shearing a metal plate without completely punching it out, and the protrusion may be smoothed. [Effects of the Invention]

[0017] According to the present invention, it is possible to achieve both miniaturization of the structure integrally provided on the metal plate and prevention of breakage. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 10 is a perspective view of a connector shown as an application example of a microstructure manufactured using the manufacturing method according to the present embodiment. [Figure 2] Enlarged view of a portion of Figure 1. [Figure 3] 1 is a flowchart showing a method for manufacturing a microstructure according to the present embodiment. [Figure 4] An outline of the process from placing the metal plate on the lower die to performing a single shearing process. [Figure 5] Schematic cross-section of a metal plate that has been sheared once. [Figure 6] An overview of the process from the first shearing process to smoothing out the unevenness. [Figure 7] Cross section of a metal plate that has been sheared twice. [Figure 8] FIG. 10 is a cross-sectional view of a metal plate after bulging according to a comparative example. [Figure 9] Graph showing shear rate versus clearance. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, embodiments will be described with reference to the drawings. Note that the same or corresponding elements are designated by the same reference numerals throughout the drawings, and detailed descriptions thereof will be omitted.

[0020] Fig. 1 is a perspective view of a connector 90 as a type of electronic component, and Fig. 2 is a partially enlarged view of the connector 90 of Fig. 1. The connector 90 is formed by primarily bending a metal plate 1 made of, for example, pure copper, a copper alloy, stainless steel, pure aluminum, or an aluminum alloy. As a mere example, the connector 90 includes a rectangular tube portion 91 having a rectangular cross section, and a flexible piece 92 that is integral with the rectangular tube portion 91 and is capable of flexibly deforming within the rectangular tube portion 91.

[0021] The connector 90 is provided with a first protrusion 93 and a second protrusion 94 as an example of a microstructure 2 manufactured using the manufacturing method according to this embodiment. The first protrusion 93 protrudes from the outer upper surface of the rectangular tube portion 91. The second protrusion 94 protrudes from the surface of the flexible piece 92 in the direction opposite to the deformation direction of the flexible piece 92. Such a microstructure 2 contributes to improving the engagement reliability between the connector 90 and a terminal (not shown) or the like that can be connected thereto.

[0022] In the illustrated example, the first protrusions 93 are thin plate-shaped with triangular sides, and the second protrusions 94 are hemispherical. This is merely an example, and the shape of the microstructure 2 is not particularly limited.

[0023] The following describes a method (hereinafter sometimes simply referred to as "this method") for manufacturing the above-described microstructure 2. In this method, a shearing process is used instead of the conventional bulging process in order to integrally form the microstructure 2 on the metal plate 1.

[0024] 3, this method includes a step of placing the metal sheet 1 on the lower die 51 of the shearing device 50 (step S1), and a step of shearing the metal sheet 1 at a processing position P with the upper die 52 of the shearing device 50 without completely punching out the metal sheet 1 (step S3). Then, a series of processes including a step of changing the processing position P so that the processing position P is shifted outward in the width direction of the metal sheet 1 from the previous processing position (step S5), and a step of shearing at the changed processing position P (step S3) are repeated a specified number of times (step S4: NO).

[0025] This method further includes a step of smoothing unevenness caused by shearing (step S6) after the series of processes has been performed a specified number of times (step S4: YES).This method further includes a step of bending the metal sheet 1 (step S2) after the metal sheet 1 is placed on the lower mold 51 and before the metal sheet 1 is subjected to the first shearing process.

[0026] Referring to FIG. 4, the shearing device 50 includes a lower die 51 and an upper die 52. The lower die 51 and the upper die 52 are spaced apart in the vertical direction. The upper die 52 is movable in the vertical direction within a movable range between an upper limit position and a lower limit position. Within the movable range, the upper die 52 can be positioned at a bending start position, a shear start position, and a shear stop position. These three positions are arranged in this order from top to bottom. The bending start position is lower than the upper limit position, and the shear stop position is the same as the lower limit position.

[0027] The upper die 52 includes a punching die 53 and a bending die 54 supported by the punching die 53. The shearing device 50 sequentially performs bending using the bending die 54 and shearing (punching) using the punching die 53 while the upper die 52 moves downward from the upper limit position to the lower limit position.

[0028] The punching die 53 protrudes downward from the underside of the base 52a of the upper die 52. The bending die 54 is disposed around the punching die 53 and is elastically supported on the underside of the base 52a via an elastic member 55. The elastic member 55 has an upper end supported on the underside of the base 52a and a lower end supported on the upper surface of the bending die 54. The elastic member 55 is, for example, a coil spring, and is expandable in the vertical direction. When the upper die 52 is at its uppermost position, neither the punching die 53 nor the bending die 54 is supported from below, and the elastic member 55 extends until it exerts an elastic force that balances the gravity of the bending die 54. In this state, the underside of the bending die 54 is located lower than the underside of the punching die 53.

[0029] The upper surface of the lower die 51 serves as a support surface 51a that supports the metal sheet 1. The lower die 51 is provided with a receiving portion 51b formed by partially recessing the support surface 51a downward. In a plan view, the ridgeline of the receiving portion 51b has the same shape as the ridgeline of the lower surface of the punching die 53, and surrounds the ridgeline of the punching die 53 slightly to the outside. The distance between the ridgeline of the receiving portion 51b and the ridgeline of the punching die 53 is defined as the "clearance amount c." The smaller the clearance amount c (see FIG. 6), the less likely breakage occurs during shearing.

[0030] 4, first, the metal plate 1 is placed on the lower mold 51 with the upper mold 52 positioned at the upper limit position (step S1). The metal plate 1 is supported on the support surface 51a so as to cover the receiving portion 51b from above at the location where the microstructure 2 is to be provided.

[0031] Next, the upper die 52 moves downward from the upper limit position. As a result, the lower surface of the bending die 54 comes into contact with the upper surface of the metal sheet 1. The position of the upper die 52 at this time is the bending start position. The upper die 52 moves further downward from the bending start position. During this process, the vertical distance between the bending die 54 and the support surface 51a is maintained at the same value as the thickness of the metal sheet 1, while the base 52a moves downward. This behavior is achieved by the contraction of the elastic member 55.

[0032] When the upper die 52 is positioned at the bending start position, a clearance is formed between the lower surface of the punching die 53 and the upper surface of the metal sheet 1. As the upper die 52 moves downward, the clearance gradually closes and the lower surface of the punching die 53 comes into contact with the upper surface of the metal sheet 1. The position of the upper die 52 at this time is the shear start position.

[0033] While the upper die 52 moves downward from the bending start position to the shear start position, the metal sheet 1 is bent (step S2). As the upper die 52 moves further downward, the metal sheet 1 is sheared (step S3).

[0034] When the upper die 52 moves downward from the shearing start position, the portion of the metal sheet 1 that is in contact with the punching die 53 is punched downward and enters the receiving portion 51b. Hereinafter, this portion will be referred to as the "shearing processing portion 10."

[0035] When the shearing section 10 hits the bottom surface of the receiving section 51b, the downward movement of the upper die 52 stops. The position of the upper die 52 at this time is the lower limit position or shear stop position. While the upper die 52 moves downward from the shear start position to the shear stop position, shearing is performed on the metal sheet 1. The distance between the shear start position and the shear stop position corresponds to the depth of the receiving section 51b, and can be defined as the amount of shearing d performed on the metal sheet 1.

[0036] During the shearing process, the bending die 54 continues to contact the upper surface of the metal sheet 1 around the sheared portion 10. The metal sheet 1 is tightly sandwiched between the lower die 51 and the bending die 54 in the vertical direction. Therefore, the sheared portion 10 can be punched downward substantially perpendicular to the original shape of the metal sheet 1.

[0037] Referring to FIG. 5, the shearing amount d is smaller than the thickness t of the metal plate 1. Therefore, the sheared portion 10 is not completely punched out of the metal plate 1, and is maintained in a state of being seamlessly continuous with the metal plate 1. Specifically, it is preferable that the shearing amount d is set to 50% or less of the thickness of the metal plate 1. By setting the shearing amount d in this manner, the sheared portion 10 is not torn off from the metal plate 1, and the microstructure 2 can be provided integrally with the metal plate 1. This point will be explained further below.

[0038] If the shearing amount d reaches the protrusion amount required for the microstructure 2 to be manufactured, the shearing process may end here. This is the case when the "specified number of times" in step S4 is 1. If the protrusion amount required for the microstructure 2 exceeds the shearing amount d, the "specified number of times" in step S4 is set to 2 or more so that the required protrusion amount is obtained. The shearing process is repeated while changing the processing position P (step S5).

[0039] FIG. 6 illustrates an example in which the specified number of times is set to three, and shearing is repeated. The processing positions P2a and P2b of the second shearing are shifted outward in the width direction of the metal plate 1, particularly to both sides, relative to the previous processing position (first processing position P1). The "width direction" here includes the radial direction when forming a hemispherical structure. The processing positions P3a and P3b of the third shearing are shifted further outward in the width direction of the metal plate 1, particularly to both sides, relative to the previous processing positions (second processing positions P2a and P2b). In this way, the current processing position is sequentially shifted outward relative to the previous processing position.

[0040] In the second shearing process, the receiving portion 51b of the lower die 51 has a stepped cross section. The upper die 52 covers the first shearing process portion 11 formed by the first shearing process and the adjacent portion from above, and abuts against the adjacent portion. As the upper die 52 moves downward, the adjacent portion is punched downward into the metal plate 1 to form the second shearing process portion 12. The second shearing process portion 12 abuts against the bottom surface of the receiving portion 51b, and the second shearing process ends. The center of the receiving portion 51b has a deep bottom or a hole. At the end of the second shearing process, the first shearing process portion 11 does not interfere with the receiving portion 51b, and its shape is maintained.

[0041] The second shearing section 12 is sandwiched between the first shearing section 11 and the original shape of the metal plate 1. The upper surface of the second shearing section 12 is lower than the upper surface of the metal plate 1 and higher than the upper surface of the first shearing section 11. The lower surface of the second shearing section 12 is similar to this. In this way, the shearing section 10 (the first shearing section 11 and the second shearing section 12) has a mortar-shaped cross section with irregularities.

[0042] FIG. 7 is a partial cross-sectional view of the metal plate 1 after the second shearing process according to this embodiment, and FIG. 8 is a cross-sectional view of a metal plate 101 according to a comparative example. As shown in FIG. 8, when bulging is used, a biaxial stress state occurs in the metal plate 1, making fracture (see dashed line) more likely to occur. To avoid fracture, the protrusions must be inclined or gently curved, which increases the width of the protrusions while reducing the protrusion length. On the other hand, as shown in FIG. 7, this embodiment employs shearing. As shown by the diagonal lines in FIG. 7, the region where shear deformation actually occurs in the shearing section 10, i.e., the shear deformation band, is narrow. In this narrow shear deformation band, the shearing amount d is adjusted so that it is below the fracture limit. This makes it possible to narrow the shearing section 10 and avoid fracture.

[0043] Returning to FIG. 6 , the third shearing process is similar to the above. The upper die 52 covers the first shearing section 11, the second shearing section 12, and the area adjacent to the second shearing section 12 on the opposite side of the first shearing section 11 from above and abuts against the adjacent area. As the upper die 52 moves downward, the adjacent area is punched downward into the metal sheet 1, forming the third shearing section 13. The third shearing section 13 abuts against the bottom surface of the receiving section 51b, completing the third shearing process. The receiving section 51b has a deep bottom or a hole in the center, so that the first shearing section 11 and the second shearing section 12 do not interfere with the receiving section 51b at the end of the third shearing process, maintaining their shapes. The third shearing section 13 is sandwiched between the second shearing section 12 and the original shape of the metal sheet 1. The upper surface of the third shearing section 13 is lower than the upper surface of the metal plate 1 and higher than the upper surface of the second shearing section 12. The lower surface of the third shearing section 13 is similar to this.

[0044] When the shearing process is performed one or more times as described above, unevenness is imparted to the surfaces of the metal plate 1 and the sheared portion 10. To smooth out these unevenness (step S6), a mold 60 separate from the shearing device 50 is used. The mold 60 comprises a lower mold 61 and an upper mold 62. Both the lower mold 61 and the upper mold 62 have linear tapered surfaces 61a, 62a. When the sheared portion 10 is sandwiched between the lower mold 61 and the upper mold 62, the shapes of the tapered surfaces 61a, 62a are transferred to the surface of the sheared portion 10. This eliminates the unevenness, and a microstructure 2 having a smooth surface is integrally formed on the metal plate 1.

[0045] As described above, this method comprises placing the metal sheet 1 on the lower die 51 of the shearing device 50, and shearing the metal sheet 1 at the processing position with the upper die 52 of the shearing device 50 without completely punching out the metal sheet 1. As a result, a protrusion having approximately the same width as the upper die 52 of the shearing device 50 can be integrally formed on the metal sheet 1 by a single shearing operation. Unlike bulging, there is no need to set a draft angle for the upper die 52. Furthermore, since the shearing is performed so as to be below the fracture limit, no fractures, including cracks, occur in the metal sheet 1. When integrally providing the microstructure 2 on the metal sheet 1, the width of the microstructure 2 can be made smaller than the protrusion amount of the microstructure 2 without causing fractures in the metal sheet 1.

[0046] This method further comprises repeatedly performing shearing by shifting the processing position P outward in the width direction of the metal plate 1. By repeating the shearing while shifting the processing position P in the width direction, the protrusion amount of the microstructure 2 can be gradually increased.

[0047] This method further comprises smoothing out the irregularities caused by the shearing process. As a result of the multi-stage shearing process, irregularities are formed on the surface of the microstructure 2. By smoothing out these irregularities, the surface of the microstructure 2 becomes smooth. This alleviates stress concentration in the microstructure 2, thereby improving the durability of the microstructure 2.

[0048] FIG. 9 shows the shear rate versus clearance for each metal material. The "clearance" on the horizontal axis is the value (%) obtained by dividing the clearance amount by the plate thickness. The "shear rate" on the vertical axis is the value (%) obtained by dividing the shear processing amount d by the plate thickness t. The top two graphs, from left to right, show the shear rates of pure copper and brass. The bottom two graphs show the shear rates of the "first copper alloy" and the "second copper alloy," with the second copper alloy being, for example, H. The first copper alloy is "CAC (registered trademark) 5" manufactured by Kobe Steel, Ltd., and has a chemical composition of Cu-0.8Ni-1.2Sn-0.07P (wt%). The second copper alloy is "CAC (registered trademark) 60" manufactured by Kobe Steel, Ltd., and has a chemical composition of Cu-1.8Ni-0.4Si-1.1Zn-0.1Sn (wt%).

[0049] It can be seen that for any metal material, the larger the clearance and the higher the material strength, the earlier the metal material will separate. When the clearance is in the range of 2.5% to 10%, it is thought that the material can be processed without separation even if shear processing is performed until the shear processing amount d becomes approximately 50% of the plate thickness t (i.e., until the shear rate becomes approximately 50%).

[0050] Although the embodiments have been described above, the above configurations can be modified as appropriate within the scope of the present invention.

[0051] The present disclosure may include the following aspects. (Aspect 1) placing the metal plate on a lower die of a shearing device; shearing the metal plate at a processing position using an upper die of the shearing device without completely punching out the metal plate to form a protrusion; A method for manufacturing a microstructure, comprising: (Aspect 2) The processing positions include a plurality of processing positions repeatedly shifted outward in the width direction of the metal plate, The processing position is shifted outward in the width direction of the metal plate from the previous processing position, and the shearing processing is repeated. A method for manufacturing the microstructure according to claim 1. (Aspect 3) The method further comprises smoothing the protrusions having irregularities caused by the shearing process. 3. A method for producing a microstructure according to claim 1 or 2. (Aspect 4) The shearing is performed at the processing position of the metal plate by a shearing amount of 50% or less of the thickness of the metal plate. A method for producing a microstructure according to any one of embodiments 1 to 3. (Aspect 5) The metal plate is a plate made of pure copper or a copper alloy. A method for producing a microstructure according to any one of embodiments 1 to 4. (Aspect 6) A microstructure having a shear deformation band formed within a protrusion formed by shearing a metal plate without completely punching it out. (Aspect 7) 7. The microstructure of embodiment 6, wherein the protrusions are smoothed. [Explanation of symbols]

[0052] 1 metal plate 2 Microstructures 10 Shearing section 50 Shearing equipment 51 Lower mold 51a Support surface 51b Receiving part 52 Upper mold 52a bass 53 Cutter 54 Bending mold 55 Elastic member 90 Connector 91 Square tube part 92 Flexible piece 93 1st protrusion 94 Second protrusion P Machining position c Clearance amount d Shearing amount t Plate thickness

Claims

1. placing the metal plate on a lower die of a shearing device; shearing the metal plate at a processing position using an upper die of the shearing device without completely punching out the metal plate to form a protrusion; A method for manufacturing a microstructure, comprising:

2. The processing positions include a plurality of processing positions repeatedly shifted outward in the width direction of the metal plate, The processing position is shifted outward in the width direction of the metal plate from the previous processing position, and the shearing processing is repeated. The method for manufacturing the microstructure according to claim 1 .

3. The method further comprises smoothing the protrusions having irregularities caused by the shearing process. The method for manufacturing a microstructure according to claim 1 or 2.

4. The shearing is performed at the processing position of the metal plate by a shearing amount of 50% or less of the thickness of the metal plate. The method for manufacturing a microstructure according to claim 1 or 2.

5. The metal plate is a plate made of pure copper or a copper alloy. The method for manufacturing a microstructure according to claim 1 or 2.

6. A microstructure having a shear deformation band formed within a protrusion formed by shearing a metal plate without completely punching it out.

7. The microstructure of claim 6 , wherein the protrusions are smoothed.

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