Copper plate member and method for tightly bending the same

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 bending a copper plate member. [Background technology]

[0002] Patent Document 1 discloses an aluminum alloy sheet having a hem portion. The tip of the hem portion is provided with a tightly bent joint. When steel sheets and aluminum alloy sheets are used for the same purpose, the aluminum alloy sheet will have a greater thickness, but the adoption of tight bending allows the sharpness of the appearance to be maintained at the same level as that of steel sheets. As a countermeasure against surface roughness and cracking of the joint, the 6000 series, which has excellent bendability, is selected as an example of a suitable aluminum alloy. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2004-042061 [Overview of the project] [Problems that the invention aims to solve]

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

[0005] The present invention aims to achieve a good appearance on the outer surface of a bent portion when performing a close-fitting bending process on a copper plate member. [Means for solving the problem]

[0006] A first aspect of the present invention is a method for tightly bending a copper plate member having a thickness of 0.3 mm or less, comprising a 180-degree bending step in which a folded portion of the copper plate member is folded 180 degrees relative to the main body of the copper plate member at the bending portion, and the folded portion is tightly bound to the main body, wherein the thickness of the plate is t, and the outer bending radius, which is the radius of the outer surface of the bent portion after the 180-degree bending step, is R. 180 In this case, the radius-to-plate thickness ratio R of the outer bending radius to the plate thickness 180 The present invention provides a method for tightly bending a copper plate member, wherein / t is greater than or equal to a threshold determined for each material of the copper plate member based on the work hardening coefficient, and when the work hardening coefficient of the copper plate member is n, the threshold is determined according to a linear equation: A × n + B relating to the work hardening coefficient n.

[0007] Here, the work hardening coefficient, also called the strain hardening index or n-value, is defined as an index obtained by 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, a threshold is determined based on the work hardening coefficient. The work hardening coefficient varies depending on the composition of the alloy, and also differs even for alloys of the same composition depending on the tempering method.

[0008] According to the above configuration, by determining the composition and temper of the copper plate member to be subjected to close bending, a threshold can be set based on the work hardening coefficient corresponding to the material. Close bending is performed on the copper plate member so that the radius-to-plate thickness ratio of the outer bending radius is equal to or greater than this threshold. In this way, by making the plate thickness-to-radius ratio equal to or greater than a specified value according to the material, the concentration of strain at one point in the bend can be effectively prevented. Cracks and wrinkles in the bend can be suppressed in response to differences in composition and temper, and a good appearance can be obtained on the outer surface of the bend. Since the threshold can be easily determined according to a linear equation, it contributes to simplifying the design of copper plate members.

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

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

[0011] the radius-to-thickness ratio and the work hardening coefficient may satisfy the following formula: R 180 / t ≥ -0.77n + 1.15.

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

[0013] Before the 180-degree bending step, a 90-degree bending step of bending the folded piece at 90 degrees with respect to the main body portion at the bent portion, and one or more bending steps of bending the folded piece at a required angle with respect to the main body portion at the bent portion before the 90-degree bending step and / or between the 90-degree bending step and the 180-degree bending step may be further provided.

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

[0015] According to the above configuration, since the nickel-silicon-based copper alloy has excellent bendability, it is easy to obtain a good appearance on the outer surface side of the bent portion.

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

[0017] According to the present invention, when forming a bent portion by applying a close bending process to a copper plate member, a good appearance can be obtained. [Brief explanation of the drawing]

[0018] [Figure 1] This is a cross-sectional view of a copper plate member according to an embodiment, showing a 180-degree bending process of a close-fitting bending process. [Figure 2A] A cross-sectional view showing the preliminary bending process for the close-fitting bending of a copper plate member according to the embodiment. [Figure 2B] A cross-sectional view showing the 90-degree bending process in a tight-fitting bending process. [Figure 2C] A cross-sectional view showing the internal bending process in a tight-fitting bending process. [Figure 3] A graph showing the bending point against bending strain. [Figure 4A] 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] 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] 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] 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] 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. [Figure 5]A graph showing the threshold values ​​for the work hardening index of each material used in materials 1-5. [Figure 6] 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 different plate thicknesses. [Modes for carrying out the invention]

[0019] Embodiments will be described below with reference to the drawings. The same reference numerals are used throughout the drawings for identical or corresponding elements to avoid redundant detailed descriptions.

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

[0021] The folded portion 4 is formed on the outer edge of the copper plate member 1. The folded portion 4 is folded back 180 degrees relative to the main body 2. As a result, one surface of the folded portion 4 is in close contact with one surface of the main body 2. The surfaces of the folded portion 4 and the main body 2 that are in close contact with each other are called the "inner surface," and the opposite surface is called the "outer surface." The outer surface 4a of the folded portion 4 is continuous with the outer surface 2a of the main body 2 via the outer surface 3a of the bent portion 3. These outer surfaces 2a, 3a, and 4a of each part constitute the overall outer surface 1a of the copper plate member 1.

[0022] In this book, the radius of the outer surface 3a of the bent portion 3 is referred to as the "outer bending radius." The ratio of the outer 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 close-fit bending method according to this embodiment because they have excellent corrosion resistance and bendability. Nickel-silicon copper alloys may contain zinc or tin in addition to nickel and silicon. The tempering method is not particularly limited. Even copper alloys with the same composition can be used in various tempers.

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

[0025] The close 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 piece 4 is bent at the bending section 3 relative to the main body 2 at a required angle (an angle between 0 degrees and 90 degrees, or an angle between 90 degrees and 180 degrees).

[0026] In this embodiment, the close bending method consists of a total of four bending steps, including 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. The bending step before the 90-degree bending step is the preliminary bending step (see Figure 2A). The bending step between the 90-degree bending step and the 180-degree bending step is the internal bending step (see Figure 2C).

[0027] Referring to Figure 2A, in the preliminary bending process, first, the outer surface 2a of the main body 2 is supported by a horizontal support base 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 semi-circular arc. In the state where the main body 2 is held between the support base 51 and the die 52 before the close bending process, the unbent folded-back piece 4 is continuous and seamlessly integrated from the main body 2, protruding horizontally from the support base 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 that it rises upward. As a result, the tip shape of the die 52 is transferred 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 2 via the bent portion 3 and extends from the bent portion 3 so as to be inclined diagonally upward relative to the main body 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 portion 4 from the bent portion 3 is inclined by an initial bending angle θ1 relative to the extension direction of the main body portion 2. The initial bending angle θ1 is between 45 and 60 degrees. The outer bending radius R1 after the completion of the preliminary bending process is 0.05 to 0.7 mm.

[0030] Referring to Figure 2B, in the 90-degree bending process, instead of the die 52 (see Figure 2A) described above, a die 54 with an L-shaped cross-section is placed on the inner surface of the main body 2. The die 54 has a horizontal plate portion 54a that clamps 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. The punch 55 is moved from bottom to top, pressing the outer surface 4a of the folded piece 4 from below, bending the folded piece 4 upward at the bending portion 3 relative to the main body 2, and clamping the folded piece 4 between the punch 55 and the vertical plate portion 54b.

[0031] In the 90-degree bending process, the folded-back piece 4 is bent at a 90-degree angle relative to the main body 2 at the bending section 3. That is, the angle between the direction of extension of the folded-back piece 4 from the bending section 3 and the direction of extension of the main body 2 is 90 degrees. Outer bending radius R after completion of the 90-degree bending process. 90 The outer bending radius R1 is 0.05 to 0.3 mm, and even when the outer bending radius R1 after the preliminary bending process is relatively large, the outer bending radius R1 can be reduced by going through the 90-degree bending process. 90 It decreases.

[0032] Referring to Figure 2C, in the internal bending process, the die is omitted, and the outer surface 4a of the folded piece 4 is pressed by the bender 56, bending the folded piece 4 so that it folds and collapses. The main body 2 is supported on the support base 51, as in the previous processes.

[0033] In the inward bending process, the extension direction of the folded portion 4 from the bent portion 3 is inclined by an inward bending angle θ3 with respect to the extension direction of the main body portion 2. The inward bending angle θ3 is between 120 degrees and 135 degrees.

[0034] Returning to Figure 1, in the 180-degree bending process, the outer surface 4a of the folded piece 4 is pressed directly downward by the bender 56, causing the inner surface of the folded piece 4 to adhere closely to the inner surface of the main body 2. The main body 2 is supported on the support base 51, as in the previous processes.

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

[0036] When using this type of close bending process, the radius-to-thickness ratio R after the completion of the 180-degree bending process is important. 180 Three or more bending processes (for example, four) are performed sequentially so that / t is greater than or equal to a threshold 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 index or n-value) differs from one another. The work hardening coefficient n is defined as the 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. To obtain the work hardening coefficient n of the material used in copper plate member 1, approximation formulas (i.e., work hardening rules) such as Swift's formula and Voce's formula can be used. In this book, unless otherwise specified, the work hardening coefficient n is obtained using Swift's formula shown below.

[0038]

number

[0039] Once the composition and quality classification of the material used for the copper plate member 1 are determined, a threshold value can be determined based on the work hardening coefficient n corresponding to the material. By setting the radius-to-thickness ratio R 180 / t to a specified value or more according to the material, it is possible to effectively prevent the extreme concentration of strain in the bending portion 3. Corresponding to differences in composition and quality classification, cracking and wrinkling of the bending portion 3 can be suppressed, and a good appearance can be obtained on the outer surface 3a side of the bending portion 3.

[0040] The larger the work hardening coefficient n, the smaller the threshold value is set. For materials with a larger work hardening coefficient n, strain is less likely to occur in the bending portion 3. The threshold value is set in light of such properties. When using a material with a large work hardening coefficient n, the threshold value becomes appropriately small, and the design region (the allowable range of the radius-to-thickness ratio R 180 / t, that is, the allowable range of the outer bending radius R 180 and the allowable range of the plate thickness t) for obtaining a good appearance is appropriately expanded. When the radius-to-thickness ratio R 180 / t is set within the range of 0.90 to 1.20, a good appearance can be obtained on the outer surface 3a side of the bending 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 regarding the work hardening coefficient n: A×n + B. Here, the slope A and the intercept B are constants. Since the threshold value can be determined using such a simple equation, it contributes to the simplification of the design of the steel plate member subjected to the hemming process. In light of the above-described relationship of the increase and decrease of the work hardening coefficient and the threshold value, A is a negative value.

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

[0043] The following is an example of a method for calculating the threshold value discovered by the inventor of this case.

[0044] (Definition of pass / fail judgment) The relationship between bending strain and bending gauge was investigated for CAC60 (registered trademark), an example of a copper alloy. The copper alloy used was a nickel-silicon copper alloy. To determine the bending gauge, CAC60 sheets were bent using a roughly W-shaped die with five levels of curvature radius R at each vertex, and tight bending was performed by pressing from above. Nine test pieces were taken from each. The central bend of the tightly bent test pieces was observed, and the radius-to-thickness ratio was measured. Additionally, points were assigned to each level of curvature radius: 5 points for large cracks, 4 points for small cracks, 3 points for large wrinkles, and 2 points for small wrinkles. The average value of the scores from the nine test pieces at each level of curvature radius was evaluated as the bending gauge for that level. Furthermore, equivalent analytical calculations were performed to obtain bending strain values ​​used for crack / wrinkle determination on the outer surface of the sheet. Note that these values ​​are representative examples, as they vary depending on the material used, die shape, and other conditions.

[0045] Figure 3 is a scatter plot of bending strain and bending point for each of the five levels of radius of curvature, with the horizontal axis representing bending strain and the vertical axis representing bending point. The smaller the bending point value, the better the appearance of the bent section; the higher the bending point value, the worse the appearance of the bent section. Specifically, as the bending point value increases, wrinkles become larger, and eventually cracks occur.

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

[0047] The dashed line in Figure 3 shows the results of linear regression performed on the five plots. The least squares method was used for regression. The coefficient of determination (R) 2 The value was 0.92. It was found that the bending gauge has a high linear correlation with bending strain. From the above, it was found that the bending gauge can be estimated with high accuracy based on the analysis results of bending strain, and consequently, 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 bending gauge exceeds approximately 2.0, small wrinkles begin to appear on the outer surface of the bent section, and when the bending gauge exceeds approximately 3.0, cracks begin to appear on the outer surface of the bent section. Therefore, a bending gauge of 2.0 and a bending gauge of 3.0 were set as thresholds for appearance evaluation, making it possible to evaluate the quality of the appearance in three stages.

[0049] If the bending gauge is less than 2.0, there is a high probability that no cracks or wrinkles will occur in the bent area, and the appearance of the bent area can be judged as good. If the bending gauge is 3.0 or higher, there is a high probability that cracks will occur in the bent area, and the appearance of the bent area can be judged as poor. If the bending gauge is between 2.0 and 3.0, there is a high probability that wrinkles will occur in the bent area, although no cracks will occur, and the appearance of the bent area can be judged as average (moderate). Note that, instead of the bending gauge of 2.0, the bending strain value corresponding to the bending gauge of 2.0 according to the regression line described above may be used as the threshold for appearance evaluation. The same applies to the bending gauge of 3.0.

[0050] (Stress-strain curve, work hardening coefficient) Next, for each of the five materials selected or defined from the category of copper alloys, stress-strain curves were investigated or defined, and work hardening coefficients were investigated or defined.

[0051] Materials 1-3 are real materials. All three materials are CAC60 (registered trademark), but they differ in temper. Material 1 is temper SH, Material 2 is temper H, and Material 3 is temper ESH. The tensile strength of Material 3 is the highest of the three, and Material 2 is the lowest. The stress-strain curves for Materials 1-3 were obtained by fitting the tensile test results to Swift's formula, and the work hardening coefficient n was obtained according to the same formula. The work hardening coefficient n for Material 1 was calculated to be 0.15, for Material 2 it was calculated to be 0.26, and for Material 3 it was calculated to be 0.027.

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

[0053] (Numerical analysis of quality) For each of materials 1-5, the outer bending radius R1 after the initial bending process is complete, the initial bending angle θ1, and the outer bending radius R after the 90-degree bending process is complete. 90 Numerical simulation was performed to simulate a total of 18 patterns of tight bending processes, using the material and internal bending angle θ3 as variables. The specifications for patterns No. 1 to 18 are shown in Table 1. In all patterns and for all materials, the plate thickness t was set to 0.2 mm.

[0054] [Table 1]

[0055] Next, for each material, the radius-to-thickness ratio R after the 90-degree bending process. 90 / t and radius plate thickness ratio R after 180-degree bending process 180 The relationship between / t was investigated and evaluated. Figures 4A to 4E show the radius-to-plate thickness ratio R 90 / t and radius plate thickness ratio R 180These are scatter plots of / t, with Figure 4A corresponding to Material 1, Figure 4B to Material 2, Figure 4C to Material 3, Figure 4D to Material 4, and Figure 5E to Material 5. In each scatter plot, the circular plots indicate patterns judged to have a good appearance based on the calculation results of the bending gauge and / or bending strain. The triangular plots indicate patterns judged to have a moderate appearance based on the calculation results of the bending gauge and / or bending strain. The bar plots indicate patterns judged to have a poor appearance based on the calculation results of the bending gauge and / or bending strain.

[0056] From each scatter plot (i.e., for all materials), the radius-to-thickness ratio R 180 If / t is large, the variables of the molding process (R1, θ1, R 90 It was found that the overall appearance tends to improve without strongly depending on θ3). Therefore, the radius-to-thickness ratio R 180 It was found that when / t exceeds a certain boundary value, the probability of obtaining a bent section with a good appearance (no wrinkles or cracks) becomes extremely high. The straight line extending parallel to the horizontal axis within the graph area of ​​each scatter plot indicates that boundary value. On the other hand, when comparing the scatter plots, it was found that the boundary value differs depending on the material.

[0057] Next, as an example of material-specific parameters, we have the work hardening coefficient n and the radius-to-thickness ratio R. 180 The relationship with the boundary value of / t was investigated. Figure 5 shows the work hardening coefficient n and the radius-to-thickness ratio R obtained from Figures 4A to 4E for each material 1 to 5. 180 This is a scatter plot of the boundary values ​​for / t, with the horizontal axis representing the work hardening coefficient n and the vertical axis representing the radius-to-thickness ratio R. 180 The boundary values ​​for / t are shown.

[0058] The work hardening coefficient n is big It was found that the boundary value decreases as the value decreases. The dashed line in Figure 5 shows the results of linear regression performed on the five plots. The least squares method was used for regression. Coefficient of determination (R 2 The value of n is 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 denoted as y, the regression line is expressed by the following equation: y = -0.7734 × n + 1.1261.

[0059] Following this regression line, once the material and the work hardening coefficient n are determined, the value of the right-hand side of the above equation and the boundary value y corresponding to that material, which is equal to it, are determined. At this time, the radius-to-thickness ratio R 180 When the close bending process is performed such that / t is greater than or equal to the boundary value y, there is a high probability that no wrinkles or cracks will occur on the outer surface of the bent part, resulting in a good appearance. In other words, using the value on the right side of the above equation, which is based on the work hardening coefficient n corresponding to the material, as a threshold, the radius-to-thickness ratio R 180 When the close bending process is performed so that / t is equal to or greater than the threshold, the probability of obtaining a bent section with a good appearance increases.

[0060] (Correction of threshold calculation formula) The above equation, which represents the regression line, is defined as the radius-to-thickness ratio R. 180 While this could be used as a threshold for / t, some of the materials 1-5 have boundary values ​​y that are higher than the regression line. Therefore, the regression line is shifted upwards on the vertical axis. In other words, the intercept of the above equation is increased. As a result, the corrected line will move above any of the boundary values ​​y for materials 1-5. The corrected line can be expressed, as an example, 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 used as the corrected threshold for the radius-to-thickness ratio R. 180 When the close-fitting bending process is performed so that / t is equal to or greater than the corrected threshold, the probability of obtaining a bent section with a good appearance increases even further.

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

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

[0064] While embodiments have been described above, the above configuration can be modified, added to, or deleted as appropriate within the scope of the present invention. [Explanation of symbols]

[0065] 1 Copper plate member 1a External surface 2 Main body 2a Exterior 3. Bent section 3a Exterior 4 Folded piece 4a Exterior 51 Support stand 52 dice 53 Vendors 54 dice 55 punches 56 Vendors A. Slope B-intercept n work hardening coefficient t Plate thickness R 90 Outer bending radius after 90-degree bending process R 90 / t Radius-to-thickness ratio after 90-degree bending process R 180 Outer bending radius after 180-degree bending process R 180 / t Radius-to-thickness ratio after 180-degree bending process θ1 Preliminary bending angle θ3 internal bending angle

Claims

1. A method for tightly bending copper plate members with a thickness of 0.3 mm or less, The process includes a 180-degree bending step in which the folded portion of the copper plate member is folded 180 degrees relative to the main body of the copper plate member at the bending portion, and the folded portion is brought into close contact with the main body. Let t be the plate thickness, and R be the outer bending radius, which is the radius of the outer surface of the bent portion after the 180-degree bending process. 180 In that case, The radius-to-plate thickness ratio R of the outer bending radius relative to the plate thickness 180 / t is greater than or equal to a threshold 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 is determined according to a linear equation relating to the work hardening coefficient n: A × n + B, A is the slope of the regression line obtained by linearly regressing the relationship between the work hardening coefficient of each copper material and the boundary value, which is the lower limit of the radius-to-thickness ratio R 180 / t at which cracks and wrinkles do not occur on the outer surface of the bent portion of the copper material, for multiple types of copper materials. The aforementioned B is set based on the intercept of the regression line, A method for tightly bending copper plate components.

2. The B is the intercept of a correction line obtained by shifting the regression line upward on the vertical axis so that it is equal to or greater than the boundary values ​​of each of the multiple types of copper materials. A method for tightly bending a copper plate member as described in claim 1.

3. The larger the work hardening coefficient, the smaller the threshold. A method for tightly bending a copper plate member as described in claim 1.

4. The radius-to-thickness ratio and the work hardening coefficient are given by the following formula: R 180 / t ≥ -0.77n + 1.15 satisfies, A method for tightly bending a copper plate member as described in claim 1.

5. Prior to the 180-degree bending step, a 90-degree bending step is performed in which the folded-back piece is bent 90 degrees relative to the main body at the bending portion, Before the 90-degree bending step and / or between the 90-degree bending step and the 180-degree bending step, one or more bending steps are performed to bend the folded-back piece at the bend portion at a required angle relative to the main body, A method for tightly bending a copper plate member according to any one of claims 1 to 4, further comprising the above.

6. The copper plate member is made of a nickel-silicon copper alloy. A method for tightly bending a copper plate member according to any one of claims 1 to 4.

7. The main body of the copper plate component with a thickness of 0.3 mm or less, A folded portion is bent 180 degrees relative to the main body and adheres closely to the main body, Equipped with, Let t be the plate thickness, and R be the outer bending radius, which is the radius on the outer surface of the bent portion. 180 In that case, The radius-to-plate thickness ratio R of the outer bending radius relative to the plate thickness 180 / t is in the range of 0.90 to 1.20 and is above a threshold 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 is determined according to a linear equation relating to the work hardening coefficient n: A × n + B, A is the slope of the regression line obtained by linearly regressing the relationship between the work hardening coefficient of each copper material and the boundary value, which is the lower limit of the radius-to-thickness ratio R 180 / t at which cracks and wrinkles do not occur on the outer surface of the bent portion of the copper material, for multiple types of copper materials. The aforementioned B is set based on the intercept of the regression line, Copper plate component.

8. The B is the intercept of a correction line obtained by shifting the regression line upward on the vertical axis so that it is equal to or greater than the boundary values ​​of each of the multiple types of copper materials. The copper plate member according to claim 7.

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