Copper plate member and close-contact bending method

Abstract

To provide a close-contact bending method to be performed on a copper plate member capable of providing a good appearance on an outer surface side of a bent part.SOLUTION: A method for close-contact bending a copper plate member having a thickness of 0.3 mm or less comprises a 180-degree bending step of folding back a folding-back piece of the copper plate member at 180 degrees with respect to a body part of the copper plate member at a bending part so as to bring the folding-back piece into tight-contact with the body part. Therein, when a thickness is t, and an outer bending radius being a radius on an outer surface side of the bending part after a 180-degree bending step is R180, a ratio R180 / t of the outer bending radius to a plate thickness is equal to or greater than a threshold value that is determined, on the basis of a work hardening factor of a copper plate member, for each material of the copper plate. When the work hardening coefficient of the copper plate member is defined to be n, the threshold value is determined according to a linear expression related to the work hardening coefficient n: A×n+B.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a copper plate member and a method for tightly contact bending of a copper plate member. [Background technology]

[0002] Patent Document 1 discloses an aluminum alloy sheet having a hem. The tip of the hem is provided with a contact part formed by tight bending. When a steel sheet and an aluminum alloy sheet are used for the same purpose, the thickness of the aluminum alloy sheet is larger, but the adoption of tight bending makes it possible to maintain the sharpness of the appearance of the aluminum alloy sheet at the same level as that of the steel sheet. In addition, as a measure against surface roughness and cracks in the contact part, the 6000 series, which has excellent bending workability, is selected as an example of a suitable aluminum alloy. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2004-042061 A Summary of the Invention [Problem to be solved by the invention]

[0004] Conventionally, there has been no knowledge available on how to maintain a good appearance when performing close contact bending on a copper plate member.

[0005] An object of the present invention is to obtain a good appearance on the outer surface side of a bent portion when performing close contact bending on a copper plate member. [Means for solving the problem]

[0006] A first aspect of the present invention is a method for performing close contact bending of a copper plate member having a plate thickness of 0.3 mm or less, comprising a 180-degree bending step of folding back a folded piece of the copper plate member 180 degrees at a bending portion with respect to a main body portion of the copper plate member, and bringing the folded piece into close contact with the main body portion, the plate thickness being t, and an outer bending radius, which is the radius of the outer surface side of the bent portion after the 180-degree bending step, being R. 180 When the above is set, the radius-thickness ratio R of the outer bending radius to the plate thickness is 180 The present invention provides a method for closely bending a copper plate member, in which / t is equal to or greater than a threshold value determined for each material of the copper plate member based on a work-hardening coefficient, and when the work-hardening coefficient of the copper plate member is n, the threshold value is determined according to a linear equation relating to the work-hardening coefficient n: A×n+B.

[0007] Here, the work hardening coefficient is also called the strain hardening exponent or n value, and is defined as an index obtained when approximating the relationship between true stress and plastic strain in the plastic region (uniform plastic deformation region) above the yield point. According to the above configuration, the threshold value is determined based on the work hardening coefficient. The work hardening coefficient varies depending on the composition of the alloy, and also varies depending on the temper (tempering method) even for alloys of the same composition.

[0008] According to the above configuration, once the composition and quality of the copper plate member to be subjected to the close bending process are determined, the threshold value can be determined based on the work hardening coefficient corresponding to the material. The copper plate member is subjected to close bending process so that the radius-thickness ratio of the outer bending radius to the plate thickness is equal to or greater than this threshold value. In this way, by setting the plate thickness-radius ratio to a specified value or greater according to the material, it is possible to effectively prevent strain from concentrating in one area at the bent portion. In response to differences in composition and quality, cracks and wrinkles at the bent portion can be suppressed, and a good appearance can be obtained on the outer surface side of the bent portion. Since the threshold value can be easily determined according to a linear equation, it contributes to simplifying the design of the copper plate member.

[0009] The larger the work hardening coefficient, the smaller the threshold value may be.

[0010] According to the above configuration, the higher the work hardening coefficient of the material, the less likely strain will concentrate locally at the bent portion. When using such a material, the threshold value is appropriately set to a small value, and the design region for obtaining a good appearance is appropriately expanded. According to the above configuration,

[0011] The radius-thickness ratio and the work hardening coefficient are expressed by the following formula: R 180 / t≧−0.77n+1.15 may be satisfied.

[0012] According to the above configuration, a good appearance can be obtained on the outer surface side of the bent portion based on knowledge obtained through experiments and simulations.

[0013] The method may further include a 90 degree bending step of bending the folded piece 90 degrees relative to the main body portion at the bending portion before the 180 degree bending step, and one or more bending steps of bending the folded piece at the bending portion to a required angle relative to the main body portion before the 90 degree bending step and / or between the 90 degree bending step and the 180 degree bending step.

[0014] The copper plate member may be made of a nickel-silicon based copper alloy.

[0015] According to the above-mentioned configuration, since the nickel-silicon copper alloy has excellent bending workability, a good appearance can be easily obtained on the outer surface side of the bent portion.

[0016] A second aspect of the present invention is a copper plate member having a thickness of 0.3 mm or less, and a folded piece folded back 180 degrees at a bent portion relative to the main body and in close contact with the main body, the plate thickness being t and an outer bending radius, which is the radius of the outer surface of the bent portion, being R. 180 When the above is set, the radius-thickness ratio R of the outer bending radius to the plate thickness is 180The present invention provides a copper plate member in which / t is in the range of 0.90 to 1.20 and is equal to or greater than a threshold value determined for each material of the copper plate member based on a work-hardening coefficient, and when the work-hardening coefficient of the copper plate member is n, the threshold value is determined according to a linear equation related to the work-hardening coefficient n: A×n+B. Effect of the Invention

[0017] According to the present invention, when a copper plate member is subjected to close contact bending to form a bent portion, a good appearance can be obtained. [Brief description of the drawings]

[0018] [Figure 1] FIG. 2 is a cross-sectional view of a copper plate member according to an embodiment, showing a 180-degree bending step in a tight bending process. [Figure 2A] 4 is a cross-sectional view showing a preliminary bending step of the contact bending process of the copper plate member according to the embodiment. FIG. [Figure 2B] A cross-sectional view showing the 90-degree bending process of the close contact bending process. [Figure 2C] FIG. [Diagram 3] Graph showing bending gauge point versus bending strain. [Figure 4A] A scatter plot of the outer bending radius after a 90-degree bending process and the outer bending radius after a 180-degree bending process for material 1. [Figure 4B] A scatter plot of the outer bending radius after a 90-degree bending process and the outer bending radius after a 180-degree bending process for material 2. [Figure 4C] A scatter plot of the outer bending radius after a 90-degree bending process and the outer bending radius after a 180-degree bending process for material 3. [Figure 4D] A scatter plot of the outer bending radius after a 90-degree bending process and the outer bending radius after a 180-degree bending process for material 4. [Figure 4E] A scatter plot of the outer bending radius after a 90-degree bending process and the outer bending radius after a 180-degree bending process for material 5. [Diagram 5]Graph showing threshold values ​​for the work hardening exponent of each material used in Materials 1 to 5. [Figure 6] A scatter plot of the outer bending radius after a 90-degree bending process and the outer bending radius after a 180-degree bending process when the plate thickness is different. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] Hereinafter, an embodiment 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 description thereof will be omitted.

[0020] 1, the copper plate member 1 includes a main body portion 2, a bent portion 3, and a folded piece 4. The copper plate member 1 is a flat plate material having a uniform plate thickness t, and the plate thicknesses t of the main body portion 2, the bent portion 3, and the folded piece 4 are equal to each other. The plate thickness t is 0.3 mm or less.

[0021] The folded piece 4 is formed on the outer edge of the copper plate member 1. The folded piece 4 is folded 180 degrees with respect to the main body 2. As a result, one surface of the folded piece 4 is in intimate contact with one surface of the main body 2. The surfaces of the folded piece 4 and the surface of the main body 2 that are in intimate contact with each other are referred to as the "inner surface", and the opposite surface is referred to as the "outer surface". The outer surface 4a of the folded piece 4 is continuous with the outer surface 2a of the main body 2 via the outer surface 3a of the bent portion 3. The outer surfaces 2a, 3a, 4a of these parts constitute the outer surface 1a of the copper plate member 1 as a whole.

[0022] In this specification, the radius of the outer surface 3a of the bent portion 3 is referred to as the "outside bending radius." The ratio of the outside bending radius to the plate thickness t is referred to as the "radius-to-plate thickness ratio."

[0023] The copper plate member 1 is made of pure copper or a copper alloy. Nickel-silicon copper alloys are suitable as metal materials to be processed using the contact bending method according to the present embodiment, because of their excellent corrosion resistance and bending workability. The nickel-silicon copper alloy may contain zinc or tin in addition to nickel and silicon. The tempering method is not particularly limited. Copper alloys of various qualities can be used even if they have the same composition.

[0024] Such a copper plate member 1 is formed using the contact bending method according to this embodiment. The contact bending method includes a multi-stage bending process having three or more stages. The contact bending method includes a 90-degree bending process (see FIG. 2B) and a 180-degree bending process (see FIG. 1). In the 90-degree bending process, the folded piece 4 is bent 90 degrees relative to the main body portion 2 at the bending portion 3. In the 180-degree bending process, the folded piece 4 is bent 180 degrees relative to the main body portion 2 at the bending portion 3.

[0025] The close contact bending method includes one or more bending steps before the 90-degree bending step and / or between the 90-degree bending step and the 180-degree bending step. In this intermediate bending step, the folded-back piece 4 is bent at the bending portion 3 to a required angle (an angle between 0 degrees and 90 degrees, or an angle between 90 degrees and 180 degrees) with respect to the main body portion 2.

[0026] In this embodiment, the close contact bending method includes one bending step before the 90-degree bending step, and one bending step between the 90-degree bending step and the 180-degree bending step, and is configured with a total of four bending steps. The bending step before the 90-degree bending step is a pre-bending step (see FIG. 2A). The bending step between the 90-degree bending step and the 180-degree bending step is an inner bending step (see FIG. 2C).

[0027] 2A, in the preliminary bending process, first, the outer surface 2a of the main body 2 is supported by a horizontal support stand 51, and a die 52 is placed on the inner surface of the main body 2. The tip of the die 52 is curved in a semicircular arc. In a state in which the main body 2 is clamped between the support stand 51 and the die 52 before the close contact bending process, the folded-back piece 4 that has not yet been folded continues seamlessly and integrally from the main body 2, and protrudes horizontally relative to the support stand 51 and the die 52.

[0028] From this state, the outer surface 4a of the folded piece 4 is pressed by the bender 53, and the folded piece 4 is bent so as to rise upward. This transfers the shape of the tip of the die 52 to the inner surface of the copper plate material, thereby forming the bent portion 3. The folded piece 4 becomes continuous with the main body portion 2 via the bent portion 3, and extends from the bent portion 3 so as to be inclined obliquely upward with respect to the main body portion 2. The outer surface 3a of the bent portion 3 is curved and has an arc-shaped cross section.

[0029] In the preliminary bending process, the extension direction of the folded piece 4 from the bent portion 3 is inclined by an initial bending angle θ1 with respect to the extension direction of the main body portion 2. The initial bending angle θ1 is equal to or greater than 45 degrees and equal to or less than 60 degrees. The outer bending radius R1 after completion of the preliminary bending process is 0.05 to 0.7 mm.

[0030] 2B, in the 90-degree bending process, instead of the above-mentioned die 52 (see FIG. 2A), a die 54 having an L-shaped cross section is installed on the inner surface of the main body 2. The die 54 has a horizontal plate portion 54a that holds the main body 2 together with the support base 51, and a vertical plate portion 54b that extends upward from the horizontal plate portion 54a. A punch 55 is moved upward from below to press an outer surface 4a of the folded piece 4 from below, folding the folded piece 4 upward at the bending portion 3 relative to the main body 2, and the folded piece 4 is sandwiched between the punch 55 and the vertical plate portion 54b.

[0031] In the 90-degree bending process, the folded-back piece 4 is folded 90 degrees with respect to the main body 2 at the bending portion 3. That is, the angle between the extending direction of the folded-back piece 4 from the bending portion 3 and the extending direction of the main body 2 is 90 degrees. The outer bending radius R after the 90-degree bending process is completed 90 is 0.05 to 0.3 mm, and even if the outer bending radius R1 after the preliminary bending process is relatively large, the outer bending radius R 90 decreases.

[0032] 2C, in the inward bending process, the die is omitted, and the outer surface 4a of the folded-up piece 4 is pressed by a bender 56, so that the folded-up piece 4 is bent so as to fall down and bend back. Note that the main body 2 is placed and supported on the support base 51, as in the previous processes.

[0033] In the inward bending process, the extending direction of the folded piece 4 from the bent portion 3 is inclined by an inward bending angle θ3 with respect to the extending direction of the main body portion 2. The inward bending angle θ3 is equal to or greater than 120 degrees and equal to or less than 135 degrees.

[0034] 1, in the 180-degree bending process, the outer surface 4a of the folded piece 4 is pressed directly downward by the bender 56, and the inner surface of the folded piece 4 is brought into close contact with the inner surface of the main body 2. The main body 2 is placed and supported on the support base 51, as in the previous processes.

[0035] In the 180-degree bending process, the folded piece 4 is folded 180 degrees at the bent portion 3 relative to the main body portion 2. That is, the angle formed between the extending direction of the folded piece 4 from the bent portion 3 and the extending direction of the main body portion 2 is 180 degrees.

[0036] When using such a close bending method, the radius-thickness ratio R after the 180-degree bending process is completed 180 Three or more stages (for example, four stages) of bending steps are sequentially performed so that / t is equal to or greater than a threshold value determined for each material of the copper plate member 1 based on the work hardening coefficient n.

[0037] Even among copper alloys, the work hardening coefficient n (also called the strain hardening exponent or n value) is different from one another. The work hardening coefficient n is defined as an index obtained when the relationship between true stress and plastic strain in the plastic region (uniform plastic deformation region) above the yield point is approximated by an exponential function. In order to obtain the work hardening coefficient n of the material used in the copper plate member 1, the Swift's equation, the Voce's equation, etc. can be used as an approximate equation (i.e., the work hardening law). In this document, unless otherwise specified, the work hardening coefficient n is obtained using the Swift's equation shown below.

[0038]

number

[0039] Once the composition and quality of the material used in the copper plate member 1 are determined, the threshold value can be determined based on the work hardening coefficient n corresponding to the material. 180 By making / t equal to or greater than the specified value according to the material, it is possible to effectively prevent strain from concentrating in one area in the bent portion 3. Depending on the difference in composition and quality, it is possible to suppress cracks and wrinkles in the bent portion 3, and it is possible to obtain a good appearance on the outer surface 3a side of the bent portion 3.

[0040] The larger the work hardening coefficient n, the smaller the threshold value is set. The larger the work hardening coefficient n of a material, the less likely it is that distortion will occur in the bent portion 3. The threshold value is set in consideration of this property. When using a material with a large work hardening coefficient n, the threshold value becomes appropriately small, and the design region (radius-to-plate thickness ratio R 180 / t tolerance, i.e., outer bending radius R 180 The allowable range of radius and thickness t is appropriately expanded. 180 When / t is set in the range of 0.90 to 1.20, a good appearance can be obtained on the outer surface 3a side of the bent portion 3 when the copper plate member is made of a copper alloy, particularly a nickel-silicon based copper alloy.

[0041] The threshold value is determined according to a linear equation related to the work hardening coefficient n: A×n+B, where the slope A and intercept B are constants. Since the threshold value can be determined using such a simple equation, it contributes to simplifying the design of steel plate members that are subjected to close bending. In light of the relationship between the increase and decrease of the work hardening coefficient and the threshold value described above, A is a negative value.

[0042] As a more specific example, the radius-thickness ratio R 180 / t and work hardening coefficient n are expressed by the following formula: 180If the radius-thickness ratio R / t≧−0.77n+1.15 is satisfied, a good appearance can be obtained on the outer surface 3a side of the bent portion 3. 180 The formula expressing the relationship between / t and the work hardening coefficient n was obtained from the findings obtained through experiments and numerical analysis by the inventors.

[0043] An example of a method for calculating the threshold value discovered by the present inventors will be described below.

[0044] (Definition of pass / fail judgement) The relationship between bending strain and bending gauge of CAC60 (registered trademark) as an example of a copper alloy was investigated. The copper alloy used was a nickel-silicon copper alloy, and the bending gauge was a CAC60 plate strip bent using a substantially W-shaped die with 5 levels of curvature radius R at each vertex for evaluating the appearance quality, pressed from above to perform close bending, and 9 test pieces were taken for each. The central bent part of the close bending test piece was observed, and the radius-thickness ratio was measured, and the average value of the scores of the 9 test pieces at each level of curvature radius was evaluated as the bending gauge at that level, with 5 points for cracks (large), 4 points for cracks (small), 3 points for wrinkles (large), and 2 points for wrinkles (small). In addition, an analytical calculation equivalent to this was performed to obtain the bending strain value used to judge cracks / wrinkles on the outside of the plate. Note that this value is a representative example, as it changes depending on conditions such as the material used and the shape of the die.

[0045] Figure 3 is a scatter diagram of bending strain and bending gauge for five levels of curvature radius, with the horizontal axis showing bending strain and the vertical axis showing bending gauge. The smaller the bending gauge value, the better the appearance of the bent part, and the higher the bending gauge value, the worse the appearance of the bent part. Specifically, as the bending gauge value increases, wrinkles become larger and even cracks occur.

[0046] From the five plots, it is found reasonable to assume that the bend gauge, i.e., poor appearance, is positively correlated with the bending strain.

[0047] The dashed lines in Figure 3 show the results of linear regression performed on the five plots. The least squares method was used for the regression. The coefficient of determination (R 2 ) was 0.92. It was found that the bending gauge has a high linear correlation with the bending strain. From the above, it was found that the bending gauge can be estimated with high accuracy based on the analysis results of the bending strain, and therefore the quality of the appearance can be estimated with high accuracy. If the bending gauge is y and the bending strain is x, the regression line can be expressed by the following equation: y = 0.0365x - 0.7491.

[0048] Specifically, when the bend gauge exceeds approximately 2.0, small wrinkles begin to appear on the outer surface of the bent portion, and when the bend gauge exceeds approximately 3.0, cracks begin to appear on the outer surface of the bent portion. Therefore, the bend gauge of 2.0 and the bend gauge of 3.0 were set as thresholds for appearance evaluation, and the appearance could be evaluated on a three-level scale.

[0049] If the bend gauge is less than 2.0, it is highly likely that no cracks or wrinkles will occur in the bent portion, and the appearance of the bent portion can be judged as good. If the bend gauge is 3.0 or more, it is highly likely that cracks will occur in the bent portion, and the appearance of the bent portion can be judged as bad. If the bend gauge is 2.0 or more and less than 3.0, it is highly likely that no cracks will occur in the bent portion, but wrinkles will occur, and the appearance of the bent portion can be judged as medium (medium). Note that, instead of the bend gauge of 2.0, the threshold value for appearance evaluation may be the bending strain value corresponding to the bend gauge of 2.0 according to the regression line described above. The same applies to the bend gauge of 3.0.

[0050] (stress-strain curve, work hardening coefficient) Next, for each of the five types of materials selected or set from the category of copper alloys, the stress-strain curve was investigated or set, and the work hardening coefficient was investigated or set.

[0051] Materials 1 to 3 are real materials. All of Materials 1 to 3 are CAC60 (registered trademark), but have different tempers. The temper of Material 1 is SH, the temper of Material 2 is H, and the temper of Material 3 is ESH. The tensile strength of Material 3 is the highest among the three, and that of Material 2 is the lowest among the three. The stress-strain curves of Materials 1 to 3 were obtained by fitting the tensile test results to the Swift equation, and the work-hardening coefficient n was obtained according to the equation. The work-hardening coefficient n of Material 1 was calculated to be 0.15, the work-hardening coefficient n of Material 2 was calculated to be 0.26, and the work-hardening coefficient n of Material 3 was calculated to be 0.027.

[0052] Materials 4 and 5 were assumed for numerical analysis based on material 1 (CAC60-SH). The stress-strain curves of materials 4 and 5 were obtained by changing only the values ​​of the work hardening coefficient n and material constant C in the Swift equation (the value of the material constant ε0 is the same as that of material 1). The work hardening coefficient n of material 4 was set to 0.05, and the work hardening coefficient n of material 5 was set to 0.3.

[0053] (Numerical analysis of pass / fail) For each of materials 1 to 5, the outer bending radius R1 after the initial bending process, the initial bending angle θ1, and the outer bending radius R after the 90-degree bending process are 90 A total of 18 patterns of close contact bending were simulated by numerical simulation, with the inner bending angle θ3 as variables. The specifications of patterns No. 1 to 18 are shown in Table 1. In addition, in all patterns for all materials, the plate thickness t was set to 0.2 mm.

[0054] [Table 1]

[0055] Next, for each material, the radius-thickness ratio R after the 90-degree bending process 90 / t and radius-thickness ratio R after 180-degree bending process 180 The relationship between the radius-thickness ratio R and the thickness-to-radius ratio R was investigated and evaluated. 90 / t and radius plate thickness ratio R 1804A corresponds to material 1, FIG. 4B corresponds to material 2, FIG. 4C corresponds to material 3, FIG. 4D corresponds to material 4, and FIG. 5E corresponds to material 5. In each scatter plot, a circle plot indicates a pattern whose appearance was judged to be good based on the calculation results of the bend gauge and / or bending strain. A triangle plot indicates a pattern whose appearance was judged to be fair based on the calculation results of the bend gauge and / or bending strain. A bar plot indicates a pattern whose appearance was judged to be poor based on the calculation results of the bend gauge and / or bending strain.

[0056] From each scatter diagram (i.e., for any material), the radius-thickness ratio R 180 If / t is large, the variables of the forming process (R1, θ1, R 90 , θ3), it was found that the appearance tends to improve overall. Therefore, the radius-thickness ratio R 180 It was found that when / t exceeds a certain boundary value, the probability of obtaining a bent part with a good appearance (no wrinkles or cracks) becomes extremely high. The straight line extending parallel to the horizontal axis in the graph area of ​​each scatter plot indicates the boundary value. On the other hand, when comparing scatter plots with each other, it was found that the boundary value differs depending on the material.

[0057] Next, the work hardening coefficient n and the radius-thickness ratio R are used as examples of parameters specific to the material. 180 The relationship between the work hardening coefficient n and the radius-thickness ratio R obtained from Figs. 4A to 4E for each material 1 to 5 was investigated. 180 / t, the horizontal axis shows the work hardening coefficient n, and the vertical axis shows the radius-thickness ratio R 180 Indicates the boundary value of / t.

[0058] It was found that the boundary value decreases as the work hardening coefficient n decreases. The dashed lines in Figure 5 show the results of linear regression of the five plots. The least squares method was used for the regression. The coefficient of determination (R 2 ) was 0.97, and it was found that the boundary value has a high linear correlation with the work-hardening coefficient n. When the boundary value is y, the regression line is expressed by the following equation: y = -0.7734 × n + 1.1261.

[0059] According to this regression line, when the material and the work hardening coefficient n are determined, the value of the right side of the above equation and the boundary value y corresponding to the material are determined. 180 When the close bending is performed so that / t is equal to or greater than the boundary value y, there is a high probability that no wrinkles or cracks will occur on the outer surface of the bent part and the appearance of the bent part will be good. In other words, the right-hand side value of the above formula based on the work hardening coefficient n corresponding to the material is set as a threshold value, and the radius-thickness ratio R 180 When the close contact bending is performed so that / t is equal to or greater than the threshold value, the probability of obtaining a bent portion with a good appearance increases.

[0060] (Correction of the threshold calculation formula) The above equation, which represents the regression line, is expressed as the radius-thickness ratio R 180 A threshold value for / t may be used, but among materials 1 to 5, there are some whose boundary value y is off to the high side of the regression line. Therefore, the regression line is translated upward along the vertical axis. That is, the intercept of the above equation is increased. As a result, the corrected line moves above the boundary value y of any of materials 1 to 5. As an example, the corrected line can be expressed by the following equation: y=-0.77n+1.15.

[0061] The right-hand side value of the above equation based on the work hardening coefficient n corresponding to the material is set as the corrected threshold value, and the radius-thickness ratio R 180 When the close contact bending process is performed so that / t is equal to or greater than the corrected threshold value, the probability of obtaining a bent portion with a good appearance increases.

[0062] (Change in plate thickness t) Fig. 6 is a diagram equivalent to Fig. 4A when the plate thickness t is 0.3 mm for Material 1. Even when the plate thickness t was changed from 0.2 mm to 0.3 mm, the same results as when the plate thickness was 0.2 mm were obtained.

[0063] As described above, when bending copper plate components, the radius-thickness ratio R 180It was found that the appearance of the bend is good if / t is equal to or greater than a threshold value determined for each material based on the work-hardening coefficient n. It was found that the larger the work-hardening coefficient n, the smaller the threshold value should be set. It was found that the threshold value has a negative linear correlation with the work-hardening coefficient, and therefore the threshold value is determined according to a linear equation for the work-hardening coefficient: A×n+B. It was found that setting A=-0.77 and B=1.15 increases the probability of obtaining a rating of good appearance for bends in a variety of materials.

[0064] Although the embodiment has been described above, the above configuration can be appropriately modified, added, or deleted within the scope of the spirit of the present invention. [Explanation of symbols]

[0065] 1 Copper plate material 1a External surface 2 Main unit 2a Exterior 3 Bending section 3a Exterior 4 Folding piece 4a Exterior 51 Support stand 52 Dice 53 Vendor 54 Dice 55 Punch 56 Vendor A Tilt B-intercept n Work hardening coefficient t Plate thickness R 90 Outside bend radius after 90 degree bending process R 90 / t Radius to thickness ratio after 90 degree bending process R 180 Outer bend radius after 180 degree bending process R 180 / t Radius to thickness ratio after 180 degree bending process θ1 preliminary bending angle θ3 inner bending angle

Claims

1. A method for closely bending a copper plate member having a thickness of 0.3 mm or less, comprising the steps of: a 180-degree bending process for folding the folded piece of the copper plate member 180 degrees at a bending portion with respect to a main body portion of the copper plate member, and bringing the folded piece into close contact with the main body portion, The plate thickness is t, and the outer bending radius, which is the radius on the outer surface side of the bent portion after the 180-degree bending process, is R 180 When The radius-to-plate thickness ratio R of the outer bending radius to the plate thickness 180 / t is equal to or greater than a threshold value determined for each material of the copper plate member based on the work hardening coefficient, When the work hardening coefficient of the copper plate member is n, The threshold value is determined according to a linear equation relating to the work hardening coefficient n: A×n+B. A method for tightly bending copper plate components.

2. The larger the work hardening coefficient, the smaller the threshold value. The method for tightly bending a copper plate member according to claim 1 .

3. The radius-thickness ratio and the work hardening coefficient are expressed by the following formula: R 180 / t≧−0.77n+1.15 is satisfied. The method for tightly bending a copper plate member according to claim 1 .

4. a 90-degree bending step of bending the folded piece at the bending portion by 90 degrees with respect to the main body portion, prior to the 180-degree bending step; one or more bending steps of bending the folded piece at the bending portion at a required angle relative to the main body portion before the 90-degree bending step and / or between the 90-degree bending step and the 180-degree bending step; The method for tightly bending a copper plate member according to claim 1 , further comprising:

5. The copper plate member is made of a nickel-silicon copper alloy. The method for tightly bending a copper plate member according to any one of claims 1 to 3.

6. A main body portion made of a copper plate member having a thickness of 0.3 mm or less; A folded piece that is folded back 180 degrees at a bent portion with respect to the main body portion and is in close contact with the main body portion; Equipped with The plate thickness is t, and the outer bending radius, which is the radius on the outer surface side of the bent portion, is R 180 When The radius-to-plate thickness ratio R of the outer bending radius to the plate thickness 180 / t is in the range of 0.90 to 1.20 and is equal to or greater than a threshold value determined for each material of the copper plate member based on the work hardening coefficient; When the work hardening coefficient of the copper plate member is n, The threshold value is determined according to a linear equation relating to the work hardening coefficient n: A×n+B. Copper plate material.

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