Processed product and processed product producing method

Abstract

A processed product (1) formed from a plated steel sheet including a plating layer (13f) on a surface of the plated steel sheet which includes a cut end (13) along a sheet thickness direction of the processed product (1), the cut end (13) includes a shear droop and a shear surface in this order, or a shear droop, a shear surface, and a rupture surface in a sheet thickness direction of the cut end (13), a ratio L / t1 between a plating component remaining length L by which the shear surface is covered with the plating layer (13f) on the surface and a sheet thickness t1 of the cut end (13) of the processed product (1) is 0.70 or more, and a length Z of the shear droop in the sheet thickness direction of the cut end (13) is 0 times to less than 0.10 times the sheet thickness t1 of the cut end (13) of the processed product (1).

Description

Processed products and manufacturing methods for processed products

[0001] The present invention relates to a method for manufacturing a processed product having a cut edge using a plated steel sheet having a plated layer on the surface as a raw material, and to the processed product.

[0002] In recent years, processed products made of plated steel sheets having a plating layer on the surface have increasingly been used as parts for devices such as automobiles and home appliances. By using plated steel sheets as the material, it is possible to omit surface treatment after forming the processed product, thereby reducing manufacturing costs. Furthermore, by omitting surface treatment after forming, it is possible to avoid deterioration of the dimensional accuracy of the part due to the surface treatment after forming. Omitting surface treatment after forming is particularly considered for parts that require high dimensional accuracy, such as motor cases.

[0003] If surface treatment after forming is omitted, areas of exposed steel sheet base material will appear at the cut edges of the processed product. Depending on the environment in which the processed product is placed, red rust may form in the areas where the steel sheet base material is exposed. Red rust deteriorates the appearance of the processed product. In addition, as the area where red rust occurs spreads over time, there is concern that the red rust may reduce the strength of the processed product. In particular, in the case of home appliances, there is concern that missing rust may cause electrical short circuits.

[0004] Furthermore, the flange of a drawn product such as a motor case may have screw holes for fixing the product to other equipment. Poor flatness around the screw holes can lead to a decrease in fastening force. When cutting the flange to ensure flatness around the screw holes, the flange dimensions are set large, taking into account the sagging of the cut end. Increasing the flange dimensions results in an increase in the material weight.

[0005] As a method for improving the rust prevention ability of the cut end portion of a processed product, for example, Patent Document 1 proposes a method in which a Zn-based plated steel sheet having a thickness of 2 mm or less is punched using a die having a shoulder portion of a punch or die with a radius of curvature that is 0.1 to 0.5 times the thickness of the Zn-based plated steel sheet, thereby increasing the shear surface ratio of the punched end face after punching to 90% or more and the zinc coverage rate of the shear surface to 50% or more.

[0006] Furthermore, Patent Document 2 proposes a method in which a punching clearance is set to 1 to 20% of the sheet thickness regardless of the thickness of the zinc-based plated steel sheet, and the zinc-based plated steel sheet is cut using a die having a shoulder portion of a punch or die with a radius of curvature that is 0.12 times or more the thickness of the zinc-based plated steel sheet, thereby obtaining a processed product in which sag Z at the cut end surface is 0.10 × the sheet thickness or more and sag X is 0.45 × the sheet thickness or more.

[0007] Furthermore, Patent Document 3 proposes a method for obtaining a product with corrosion resistance at the end face by half-punching a plated steel sheet to 60 to 95% of the sheet thickness with a negative clearance and then shearing the sheet from the opposite side of the half-punching by flat pressing.

[0008] Furthermore, Patent Document 4 discloses a method for press working metal sheet material, which includes a first step of using a first punch and a first die to half-punch the metal sheet material and leaving a shaving allowance on the final processed surface of the punched portion of the metal sheet material, and a second step of using a second punch and a second die to further shaving the half-punched portion, mainly by shearing, thereby ensuring a sheared surface of 70% or more on the final processed surface of the punched portion.

[0009] Furthermore, Patent Document 5 describes a shear drilling method in which a first step is performed with a negative clearance, and then a second step is performed with a positive clearance using a punch and a die that do not have a rounded (R) cutting edge.

[0010] Japanese Patent No. 5272518 Japanese Patent No. 6073025 Japanese Patent Application Laid-Open No. 2002-321021 Japanese Patent Application Laid-Open No. 2004-174542 Japanese Patent Application Laid-Open No. 11-254055

[0011] However, the method described in Patent Document 1 is intended for steel plates with a thickness of 2 mm or less, and when steel plates with a thickness of more than 2 mm are used as the raw material, the zinc coverage rate on the sheared surface may be insufficient, making it difficult to prevent the occurrence of red rust. It is also difficult to apply this method to drawn products, such as motor cases, in which increased thickness occurs at the flange ends.

[0012] The method described in Patent Document 2 produces a processed product with a sag Z at the cut end of 0.10 times or more of the plate thickness and a sag X of 0.45 times or more of the plate thickness, resulting in significant sag. This reduces the effective contact area around the screw hole, resulting in a decrease in the fastening force of the fixing screw. On the other hand, increasing the dimensions of the flange to ensure flatness around the screw hole results in an increase in the material weight. For this reason, this method may not be applicable to drawn products such as motor cases that require a fixed flange.

[0013] In the method described in Patent Document 3, the plated steel sheet is half-punched with a negative clearance and then sheared by flat pressing from the opposite side of the half-punched. This can result in fracture surfaces at the midpoint of the cut end of the plated steel sheet in the thickness direction, and can also result in whisker-like burrs being generated during flat pressing, deteriorating the shape quality.

[0014] The method described in Patent Document 4 is a technology related to shaving, and improves the final processed surface of the metal sheet by forming a large sheared surface. Even if a metal sheet having a plating layer on its surface is shaved by the method described in Patent Document 4, almost no plating layer remains on the surface of the final processed surface, resulting in low corrosion resistance of the final processed surface.

[0015] In the method described in Patent Document 5, the cutting edges of the punch and die used in the second step are not rounded (R), and therefore, even if a plated steel sheet is used as the raw material, the effect of leaving a plating layer on the cut end surface cannot be expected.

[0016] Therefore, the present invention has been made in consideration of the above problems, and an object of the present invention is to provide a processed product that has good corrosion resistance and shape quality even when a plated steel sheet having a thickness of more than 2.0 mm is used as a raw material, and a method for manufacturing the processed product.

[0017] In order to solve the above-mentioned problems, according to one aspect of the present invention, there is provided a processed product that is made from a plated steel sheet having a plating layer on its surface, and that has a cut edge along the sheet thickness direction of the processed product, wherein the cut edge has a sag, a shear surface, and a fracture surface, in that order, or a sag and a shear surface, in that order, in the sheet thickness direction of the cut edge, and wherein the ratio L / t1 of the remaining plating component length L where the shear surface is covered by the surface plating layer to the sheet thickness t1 of the cut edge of the processed product is 0.70 or more, and the length Z of the sag in the sheet thickness direction of the cut edge is 0 times and less than 0.10 times the sheet thickness t1 of the cut edge of the processed product.

[0018] The length W1 of the fracture surface of the cut end in the thickness direction may be greater than 0 mm and less than or equal to 1.0 mm.

[0019] The length W1 of the fracture surface of the cut end in the thickness direction may be 0.5 mm or less.

[0020] The length X of the sag in a planar direction perpendicular to the thickness direction of the cut end portion may be 0 times and less than 0.30 times the thickness t1 of the cut end portion of the processed product.

[0021] The length of the burr on the cut edge may be less than 0.2 mm.

[0022] The cut end has a sag, a shear surface, a fracture surface, and a coining surface in that order, or a sag, a shear surface, and a coining surface in that order, in the thickness direction of the cut end, and the length W2 of the fracture surface between the shear surface and the coining surface in the thickness direction of the cut end may be more than 0 mm and not more than 0.5 mm.

[0023] In order to solve the above-mentioned problems, according to another aspect of the present invention, there is provided a method for manufacturing a processed product having a cut edge, using a plated steel sheet having a plating layer on a surface thereof as a raw material, the method comprising: a half-cutting step of half-cutting a cut portion of a first element formed from the raw material in a thickness direction of the sheet using a first die and a first punch, the clearance between the first die and the first punch being set to a negative clearance; and a finish-cutting step of finish-cutting the half-cut first element in the same direction as the half-cutting, using a second die and a second punch, to obtain a processed product having a cut edge along the thickness direction of the sheet; ３２ is the inner diameter D of the first die ３１ When the cut end is formed on the inner side of the processed product, the outer diameter d ３２ is the outer diameter d of the first die ３１ The thickness of the cut portion of the first body is t1, the remaining thickness of the cut portion after the half-cutting step is t2, and in the half-cutting step, the clearance C between the first die and the first punch is ３１－４１ satisfies the following formula (a1), the radius of curvature R1 of the cutting edge of the first die satisfies the following formula (a2), the amount of thrust D of the first die or the first punch against the cutting portion of the first blank satisfies the following formula (a3), and the distance C between the first die and the first punch at the bottom dead center Ｐ－Ｄ satisfies the following formula (a4), and in the finish cutting process, the clearance C between the second die and the second punch ３２－４２ satisfies the following formula (a5), and the radius of curvature R2 of the cutting edge of the second die satisfies the following formula (a6): −0.25×t1≦C ３１－４１ ≦-0.01 ... (a1) 0.10 x t1 ≦ R1 ≦ 0.50 x t1 ... (a2) D≧0.70 x t1 ... (a3) ​​C Ｐ－Ｄ ≧0.20 ... (a4) 0.01≦C ３２－４２ ≦0.2×t2 (a5) 0.25≦R2≦1.50×t2 (a6) where, C ３１－４１ , C Ｐ－Ｄ , C ３２－４２ and R2 is in mm.

[0024] Furthermore, in order to solve the above-mentioned problems, according to another aspect of the present invention, there is provided a method for manufacturing a processed product having a cut edge, using a plated steel sheet having a plating layer on a surface thereof as a raw material, the method comprising: a half-cutting step of half-cutting a cut portion of a first element formed from the raw material in a thickness direction of the sheet using a first die and a first punch, the clearance between the first die and the first punch being set to a negative clearance; and a finish-cutting step of finish-cutting the half-cut first element in the same direction as the half-cutting, using a second die and a second punch, to obtain a processed product having a cut edge whose cut surface is along the thickness direction of the sheet. ３２ is the inner diameter D of the first die ３１ When the cut end is formed on the inner side of the processed product, the outer diameter d ３２ is the outer diameter d of the first die ３１ The thickness of the cut portion of the first body is t1, the remaining thickness of the cut portion after the half-cutting step is t2, and in the half-cutting step, the clearance C between the first die and the first punch is ３１－４１ satisfies the following formula (b1), the radius of curvature R11 of the cutting edge of the first die satisfies the following formula (b2-1), the radius of curvature R12 of the cutting edge of the first punch satisfies the following formula (b2-2), the amount of pressing D of the first die or the first punch into the cutting portion of the first blank satisfies the following formula (b3), and the distance C between the first die and the first punch at the bottom dead center Ｐ－Ｄ satisfies the following formula (b4), and in the finish cutting process, the clearance C between the second die and the second punch ３２－４２ satisfies the following formula (b5), and the radius of curvature R2 of the cutting edge of the second die satisfies the following formula (b6): −0.35×t1≦C ３１－４１ ≦-0.10×t1 ...(b1) 0.10×t1≦R11≦0.65×t1 ...(b2-1) 0.10×t1≦R12≦0.65×t1 ...(b2-2) D≧0.70×t1 ...(b3) C Ｐ－Ｄ ≧0.20 ... (b4) 0.01≦C ３２－４２≦0.2×t2 (b5) 0.25≦R2≦1.50×t2 (b6) where, C ３１－４１ , C Ｐ－Ｄ , C ３２－４２ and R2 is in mm.

[0025] The above-described method for manufacturing a processed product may further include a coining step in which the processed product obtained in the finish cutting step is used as a second element, and corners of the cut end portion of the second element are pressed against a pad to obtain a processed product having coining surfaces formed on the corners.

[0026] When the cut end is formed on the outer periphery of the workpiece, the inner diameter D of the first die ３１ and the inner diameter D of the second die ３２ Absolute value of the difference |D ３２ -D ３１ | is 1.00 mm or less, and when the cut end is formed on the inner side of the processed product, the outer diameter d ３１ and the outer diameter d of the second die ３２ Absolute value of the difference |d ３２ -d ３１ may be set to 1.00 mm or less.

[0027] The above-described method for manufacturing a processed product may further include, before the semi-cutting step, a preparation step of forming a first body having a hollow side wall and a flange portion from a flat plated steel sheet.

[0028] As described above, according to the present invention, even when a plated steel sheet having a thickness of more than 2.0 mm is used as a raw material, it is possible to obtain a processed product having good corrosion resistance and shape quality.

[0029] 1 is a perspective view showing an example of a processed product manufactured by a processed product manufacturing method according to a first embodiment of the present invention. It shows a cut end 13 in region A of the processed product 1 in FIG. 1, with the left side being a cross-sectional view in the ZX plane including the central axis of the processed product, and the right side being a side view from the X direction. It is a detailed view of the cross-sectional view on the left side of FIG. 2. It is a graph showing the relationship between sagging X and sagging Z in FIG. 3. It is an explanatory diagram showing a processed product manufacturing method according to the same embodiment. It is an explanatory diagram showing a half-cutting process in which the cutting edge of the die used in the half-cutting process is R-shaped. It is an explanatory diagram showing a finish-cutting process performed subsequent to the half-cutting process shown in FIG. 6. It is an explanatory diagram showing a half-cutting process in which the cutting edges of the die and punch used in the half-cutting process are R-shaped. It is an explanatory diagram showing a finish-cutting process performed subsequent to the half-cutting process shown in FIG. 8. It is an explanatory diagram showing the formation position of a screw hole depending on the size of sagging X in the planar direction. It is an explanatory diagram showing a processed product manufacturing method according to a second embodiment of the present invention. It is an explanatory diagram showing a coining process. It shows the cut end of the processed product after the coining process, with the left side being a cross-sectional view in the ZX plane including the central axis of the processed product, and the right side being a side view from the X direction. FIG. 21 is a photograph showing an example of a cut end portion of a processed product after a coining process. FIG. 22 is an explanatory diagram showing the volume of a corner portion crushed by a pad in a coining process. FIG. 23 is a perspective view showing an example of a processed product. FIG. 24 is a perspective view showing another example of a processed product. FIG. 25 is a perspective view showing another example of a processed product. FIG. 26 is a schematic view showing an example of a cutting die for processing a flat washer. FIG. 27 is a schematic view showing a state in which a material has been punched using the cutting die of FIG. 20. FIG. 28 is a perspective view showing another example of a processed product.

[0030] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In this specification and drawings, components having substantially the same functional configurations are designated by the same reference numerals, and redundant explanations will be omitted.

[0031] [1. First Embodiment] [1-1. Worked Product] First, a worked product 1 manufactured by a worked product manufacturing method according to a first embodiment of the present invention will be described with reference to FIG. 1. FIG. 1 is a perspective view showing an example of the worked product 1 manufactured by the worked product manufacturing method according to the first embodiment of the present invention. The worked product 1 shown in FIG. 1 is a motor case made of a plated steel sheet having a plated layer on its surface. The motor case shown in FIG. 1 can be formed by subjecting a flat plated steel sheet to a forming process such as drawing.

[0032] As shown in FIG. 1 , the processed product 1 according to this embodiment has a body portion 10 , a protrusion portion 11 and a flange portion 12 .

[0033] The body 10 has a hollow cylindrical side wall 101 and a top wall 103 formed to cover one end of the side wall 101. The top wall 103 may be called a bottom wall or other name depending on the orientation of the processed product 1. The cross-sectional shape of the body 10 of the processed product 1 shown in FIG. 1 taken along the XY plane is a perfect circle, but the present invention is not limited to this example. The cross-sectional shape of the body 10 taken along the XY plane may be other shapes, such as an ellipse or a polygon.

[0034] The protrusion 11 is a protruding body that protrudes outward from the top wall 103 in the central axis direction (Z direction) of the body 10. Note that the protrusion 11 does not necessarily have to be formed, and the top wall 103 may be flat.

[0035] The flange portion 12 is a plate portion extending from an end portion of the body portion 10 (i.e., the other end of the side wall 101) toward the radially outer side of the body portion 10. The shape of the flange portion 12 is arbitrary. The flange portion 12 according to this embodiment extends in the radial direction of the body portion 10 over the entire circumferential area of ​​the body portion 10. The flange portion 12 has a plurality of screw holes 121 spaced apart from one another in the circumferential direction of the body portion 10. Screws 123 are inserted into the screw holes 121. The processed product 1 can be fixed to an attachment object, such as a vehicle body, by fastening it to the attachment object using the screws 123.

[0036] The flange portion 12 according to this embodiment is formed by cutting a flange portion blank (flange portion blank 20 in FIG. 5 ) having an outer diameter larger than the outer diameter of the flange portion 12 that will ultimately be formed in the processed product 1. That is, the processed product 1 according to this embodiment has a cut end portion 13 on the outer periphery of the flange portion 12.

[0037] Cutting processes include cutting, punching, and drilling. Cutting is a process of cutting an object along a predetermined straight line or curve. Punching is a process of punching a product out of an object. Drilling is a process of punching out a non-product part from an object to obtain a product with an opening. The flange portion 12 shown in FIG. 1 can be obtained by punching out a flange portion base body.

[0038] As the plated steel sheet, it is preferable to use a plated steel sheet having various plating layers. As the plated steel sheet, various steel sheets can be used, but it is preferable to use a Zn-based plated steel sheet. Zn-based plating includes Zn plating, Zn-Al-based alloy plating, Zn-Al-Mg-based alloy plating, and Zn-Al-Mg-Si-based alloy plating. As the plated steel sheet, it is particularly preferable to use a steel sheet that has been subjected to Zn-Al-Mg-based alloy plating. Here, the alloy plating preferably contains 80 mass% or more of Zn, and more preferably contains 90 mass% or more of Zn, based on the total number of moles of the plating.

[0039] The base steel sheet of the plated steel sheet may be any steel sheet, but may be, for example, ultra-low carbon steel.

[0040] The coating weight of the plated steel sheet is preferably 30 g / m ２ is the lower limit, and more preferably 45 g / m ２ The lower limit of the coating weight of the plated steel sheet is preferably 450 g / m ２ The upper limit is more preferably 190 g / m ２ The upper limit may be set to 45 g / m. ２ By doing so, the plating metal can easily get around the sheared surface of the cut end portion 13 (sheared surface 13c in FIG. 2), thereby improving the corrosion resistance after cutting.

[0041] The thickness of the plated steel sheet (the thickness of the base steel sheet plus the thickness of the plating layer) is arbitrary, but may be 2.0 mm or less or may exceed 2.0 mm. The thickness of the plated steel sheet may be, for example, 0.8 mm or more and 6.0 mm or less, more preferably 2.0 mm or more and 4.5 mm or less.

[0042] [1-2. Cut End of Workpiece] Next, the cut end 13 of the workpiece 1 according to this embodiment will be described with reference to FIGS. 2 to 4. FIG. 2 shows the cut end 13 in region A of the workpiece 1 in FIG. 1, with the left side being a cross-sectional view in the ZX plane including the central axis of the workpiece 1, and the right side being a side view from the X direction. FIG. 3 is a detailed view of the cross-sectional view on the left side of FIG. 2. FIG. 4 is a graph showing the relationship between sag X and sag Z in FIG. 3. Note that in FIGS. 2 and 3, the plate thickness direction T of the flange portion 12 is the same as the Z direction, which is the central axis direction of the workpiece 1 shown in FIG. 1. Also, the plating layer 13f is omitted from FIG. 2.

[0043] 2 and 3, the cut end 13 of the flange portion 12 of the processed product 1 has, in order from the upper surface 13a, a sag 13b, a shear surface 13c, a fracture surface 13d, and a burr 13e in the thickness direction T of the flange portion 12. It is preferable that the processed product 1 does not have the burr 13e, and the processed product 1 according to this embodiment may be a processed product 1 that does not have the burr 13e.

[0044] The upper surface 13a is the surface (pressed surface) against which the cutting die is pressed when cutting the flange portion body.

[0045] The sag 13b is a portion where a tensile force acts on the surface of the flange portion element (plated steel sheet) when a cutting die is pressed into the flange portion element, causing the surface of the flange portion element to deform. In this specification, the dimension of the sag 13b in the plate thickness direction T of the flange portion 12 is referred to as "sag Z," and the dimension of the sag 13b in a planar direction perpendicular to the plate thickness direction T is referred to as "sag X."

[0046] The sheared surface 13c is a surface where the flange portion body is sheared by the cutting edge of the cutting die. The sheared surface 13c is adjacent to the sag 13b in the plate thickness direction T of the flange portion 12.

[0047] The fracture surface 13d is a surface where cracks that have occurred in the flange portion blank from the cutting edge of the cutting die meet and fracture. The fracture surface 13d is adjacent to the shear surface 13c in the plate thickness direction T of the flange portion 12.

[0048] The burrs 13e are portions where the flange element body is stretched or torn off when the fractured surface 13d is formed. The burrs 13e are adjacent to the fractured surface 13d in the plate thickness direction T of the flange 12.

[0049] As will be described later, by cutting the flange portion element 20 by the method for manufacturing a processed product according to this embodiment, it is possible to reduce the sagging 13b, the fracture surface 13d, and the burrs 13e.

[0050] As shown in FIG. 3 , in the method for manufacturing a processed product according to this embodiment, the cut end 13 is formed so that a plating layer 13f wraps around the sheared surface 13c from the upper surface 13a of the cut end 13. As the cutting edge of the cutting die bites into the flange body, the plating layer 13f is stretched by the cutting die and wraps around the sheared surface 13c. This wrapping of the plating layer 13f results in at least a portion of the sheared surface 13c being covered with the plating layer 13f. The generation of red rust can be suppressed in the portion of the sheared surface 13c covered with the plating layer 13f. Furthermore, when the plating layer 13f is a Zn-based plating layer, the sacrificial corrosion protection effect of the Zn-based plating layer can also suppress the generation of red rust in the vicinity of the portion covered with the plating layer 13f.

[0051] In this case, the length L of the plating layer 13f, which extends from the upper surface 13a of the cut end 13 to the sag 13b and covers at least a portion of the sheared surface 13c of the workpiece 1, is 0.7 times or more the thickness t1 of the cut end 13 of the workpiece 1. That is, the ratio L / t1 of the remaining length L of the plating component where the sheared surface 13c is covered by the plating layer 13f to the thickness t1 of the cut end 13 of the workpiece 1 is 0.70 or more. The length L of the plating layer 13f can also be considered the distance between the upper surface 13a of the cut end 13 and the lower end of the plating layer 13f in the thickness direction T of the flange portion 12. Furthermore, the thickness t1 of the cut end 13 of the workpiece 1 is equal to the thickness of the flange portion 12 of the workpiece 1, as shown in FIG. 2 . Therefore, hereinafter, the thickness of the flange portion 12 may be referred to as "thickness t1."

[0052] The fracture surface 13d is a newly formed rough surface that is formed when cracks that have occurred in the flange portion element coalesce. Metallic components of the steel substrate are exposed at the fracture surface 13d. The plating layer 13f that covers the shear surface 13c does not easily extend to the fracture surface 13d. Therefore, red rust is more likely to develop on the fracture surface 13d than on other surfaces of the cut end portion 13.

[0053] The inventors conducted experiments in which the thickness t1 of the flange portion 12 on which the cut end 13 is formed, the cutting conditions, the surface treatment conditions, etc., were varied over various ranges to investigate the occurrence of red rust. As a result, they came up with the idea of ​​cutting a plated steel sheet by extending the plating layer 13f from the upper surface 13a to the shear surface 13c, setting the ratio L / t1 to 0.70 or more, and obtaining a processed product 1 in which the length of the sag 13b in the thickness direction T of the flange portion 12 (sag Z) is more than 0 times but less than 0.10 times the thickness of the flange portion 12 (i.e., the thickness t1 of the cut end 13 of the processed product 1). It was found that such cutting can suppress the occurrence of red rust at the cut end 13 over time after cutting, without excessively increasing the blank dimensions to ensure a flat area around the screws 123 required to secure the processed product 1.

[0054] Here, the thickness of the flange portion 12 is equal to the thickness t1 of the cut end portion 13 of the processed product 1, and is the outermost thickness of the flange portion 12 (however, this is the thickness of the portion where the sagging 13b does not occur). The length W1 of the fracture surface 13d in the thickness direction T of the flange portion 12 (hereinafter also referred to as the "fracture surface length") is preferably greater than 0 mm and less than 1.0 mm. If the fracture surface length W1 is 1.0 mm or less, even if red rust occurs on the fracture surface 13d, it will not be noticeable, and it can be determined that this will not pose a practical problem. The fracture surface length W1 of the processed product 1 is preferably small, and may be 0.8 mm or less or 0.6 mm or less. It is more preferable that the fracture surface length W1 of the processed product 1 be 0.5 mm or less, 0.3 mm or less, or 0.2 mm or less. Furthermore, the ratio W1 / t1 of the fracture surface length W1 to the thickness t1 of the cut end 13 of the workpiece 1 may be less than 0.15, less than 0.10, less than 0.08, less than 0.06, or less than 0.04. The fracture surface length W1 of the workpiece 1 may be 0 mm. In other words, the cut end 13 of the workpiece 1 may not have a fracture surface 13d. In this case, the cut end 13 has, in the thickness direction T of the flange portion 12, a sag 13b and a shear surface 13c (and, if a burr 13e is generated, a burr 13e) in this order from the upper surface 13a.

[0055] In order to ensure a flat portion around the screw 123, it is desirable to minimize the sag X. There is a correlation between the sag Z and the sag X. Therefore, in terms of the sag Z, which is easy to measure, it is preferable that the sag Z is less than 0.10 times the thickness of the flange portion 12, i.e., the thickness t1 of the cut end portion 13 of the processed product 1. The thickness t1 of the flange portion 12 is also equal to the thickness of the flange portion body 20. A smaller sag Z is preferable, and it may be less than 0.08 times, less than 0.06 times, or less than 0.04 times the thickness of the flange portion 12, i.e., the thickness t1 of the cut end portion 13 of the processed product 1.

[0056] FIG. 4 shows an example of the relationship between sag Z and sag X at the cut end of a product manufactured by punching in a single process. FIG. 4 shows the relationship between sag Z and sag X at the cut end of a product when punching is performed by imparting a radius of curvature of 0.01 to 0.30 times the plate thickness of the flange portion blank to the cutting edge of the cutting die that is pressed into the flange portion blank, and setting the clearance of the cutting die to 0.01 to 0.20 times the plate thickness. As shown in FIG. 4 , when punching is performed in a single process, the sag X that appears in the planar direction is approximately 3 to 4 times larger than the sag Z in the plate thickness direction. In other words, when punching is performed in a single process, the sag X in the planar direction becomes large, and in order to ensure a flat area around the screw 123 required to secure the processed product 1 to the mounting target, the trim dimension must be increased by the amount of sag X. Therefore, it is preferable that the sag X is 0 times and less than 0.30 times the thickness of the flange portion 12 of the processed product 1, i.e., the thickness t1 of the cut end portion 13 of the processed product 1. It is preferable that the sag X is small, and it may be less than 0.25 times, less than 0.26 times, less than 0.15 times, less than 0.12 times, or less than 0.10 times the thickness of the flange portion 12, i.e., the thickness t1 of the cut end portion 13 of the processed product 1.

[0057] Furthermore, the length of the burrs 13e generated on the lower side of the fracture surface 13d of the cut end portion 13 of the workpiece 1 may be less than 0.2 mm. The burrs 13e can cause dents, electrical short circuits, etc. By making the length of the burrs 13e less than 0.2 mm and minimizing the amount of burrs remaining on the workpiece 1, the occurrence of dents, electrical short circuits, etc. can be suppressed. It is more preferable that the length of the burrs 13e is less than 0.1 mm. It is most preferable that the length of the burrs 13e is 0 mm, i.e., no burrs 13e are present on the workpiece 1.

[0058] Therefore, in the method for manufacturing a processed product according to this embodiment, the plated steel sheet is cut not in a single step but in two steps, a semi-cutting step and a finish-cutting step. This allows a larger amount of the plating layer 13f to bend around the shear surface 13c while suppressing the sagging 13b of the cut edge 13 from becoming large. The method for manufacturing a processed product according to this embodiment will be described below.

[0059] [1-3. Processed Product Manufacturing Method] First, the processed product manufacturing method according to this embodiment will be described with reference to Fig. 5. Fig. 5 is an explanatory diagram showing the processed product manufacturing method according to this embodiment. As shown in Fig. 5, the processed product manufacturing method according to this embodiment includes a preparation step, a semi-cutting step, and a finish cutting step.

[0060] The preparation step is a step of preparing a first element body 2. The first element body 2 can be obtained by performing a forming process such as drawing on a flat plated steel sheet. That is, the first element body 2 is made of plated steel sheet, just like the processed product 1. The first element body 2 includes a flange portion element body 20 having an outer diameter larger than that of the flange portion 12 shown in FIG. 1. The flange portion element body 20 may have a circular or non-circular outer shape in a plan view. The first element body 2 may have a shape similar to that of the processed product 1 except for the flange portion element body 20. Note that the preparation step is not essential to the implementation of the present invention. If an element body that has been processed by a third party using some method is available, the preparation step can be omitted.

[0061] The half-cutting process is a process of half-cutting the first element body 2. In the half-cutting process, the flange portion element body 20 is half-cut. Half-cutting is a process of cutting the flange portion element body 20 to a position halfway in the plate thickness direction of the flange portion element body 20. When the flange portion element body 20 of the first element body 2 is half-cut, a removed portion 20a that will ultimately be outside the product is cut partway from the flange portion element body 20.

[0062] The finish cutting step is a step of finish-cutting the first element body 2. In the finish cutting step, the removed portion 20a of the flange portion element body 20 is cut and separated from the flange portion element body 20. The flange portion 12 is formed by cutting the removed portion 20a. That is, in the processed product manufacturing method according to this embodiment, the processed product 1 is obtained from the first element body 2 prepared in the preparation step through the half-cutting step and the finish cutting step. The screw holes 121 of the processed product 1 shown in FIG. 1 may be formed in the flange portion element body 20 at the stage of the first element body 2, or may be formed in the flange portion 12 after the finish cutting step.

[0063] In the half-cutting step and finish-cutting step of the processed product manufacturing method according to this embodiment, the flange portion blank 20 is machined using a die and a punch. Details of the half-cutting step and the finish-cutting step will be described below, with two embodiments depending on the shapes of the cutting edges of the die and punch used in the half-cutting step. The cutting edges of the die and punch are sometimes referred to as "shoulders."

[0064] In the following description, for convenience, the molds used to obtain the processed product 1 will be referred to as the die, and the punch, respectively. The pushing-side mold may be positioned above or below the blank. Even when moving horizontally, the pushing-side mold is referred to as the die, and the punch, respectively. For example, the processed product 1 shown in FIG. 2 was cut using the upper mold as the pushing-side mold. If the lower mold were the pushing-side mold, i.e., the lower mold were the die, the cut end 13 of the processed product 1 would have the sag 13b located at the bottom of the cut end 13, and above that, the shear surface 13c, the fracture surface 13d, and the burr 13e, in that order, as opposed to FIG. 2. Therefore, the burr 13e would be located at the top. In other words, of the two surfaces of the flange portion body 20 facing each other in the thickness direction, the mold that presses the surface on which the sag 13b of the workpiece 1 is located after processing is called the die, and the mold that presses the surface on which the burr 13e is located is called the punch.

[0065] If it is unclear which of the upper and lower (or left and right) molds will be the die and which will be the punch, the cut end 13 can be observed after the actual cutting, and the mold that presses the surface on the side where the sag 13b is located can be called the die, and the mold that presses the surface on the side where the burr 13e is located can be called the punch.

[0066] As shown in FIG. 2 , when the cut edge 13 is formed on the outer periphery of the workpiece 1, the die is positioned on the outer periphery of the punch. During processing, the inner surface of the die faces the cut edge 13, and the outer surface of the punch is flush with the cut edge 13. On the other hand, when the cut edge 13 is formed on the inner periphery of the workpiece 1, such as when cutting the inner periphery of a flat washer 900 shown in FIG. 16 (described later), the die is positioned on the inner periphery of the punch. During processing, the outer surface of the die faces the cut edge 13, and the inner surface of the punch is flush with the cut edge 13. Furthermore, when the outer and inner peripheries of the workpiece 1 are cut simultaneously, as shown in FIGS. 20 and 21 (described later), in this embodiment, both the push-in dies 61 and 63 are referred to as dies, and the pushed-in dies 65 are referred to as punches.

[0067] (a. When the cutting edge of the die used in the semi-cutting step is rounded) First, the semi-cutting step and the finish-cutting step when the cutting edge of the die used in the semi-cutting step is rounded will be described with reference to Fig. 6 and Fig. 7. Fig. 6 is an explanatory diagram showing the semi-cutting step when the cutting edge of the die used in the semi-cutting step is rounded. Fig. 7 is an explanatory diagram showing the finish-cutting step that is performed subsequent to the semi-cutting step in Fig. 6.

[0068] (Half-Cutting Process) In the half-cutting process, as shown in Fig. 6 , the flange portion element 20 of the first element 2 is half-cut using a first die 31 and a first punch 41. Fig. 6 shows, as one mode of half-cutting, a mode in which the flange portion 12 is half-punched from the flange portion element 20 held between the first punch 41 and a first plate holder 51. The first die 31 constitutes a cutting mold that is pressed into the flange portion element 20 during half-cutting. In this embodiment, the first punch 41 is the mold that presses the portion of the flange portion element 20 that will become the flange portion 12, and the first die 31 is the mold that presses the removed portion 20a.

[0069] Clearance C between the first die 31 and the first punch 41 ３１－４１ is a negative clearance. Here, the clearance C ３１－４１represents the gap between the first die 31 and the first punch 41, and specifically, as shown in FIG. 6, is represented by the distance between the side surface 31a of the first die 31 and the side surface 41a of the first punch 41. In the state where there is no clearance (i.e., C ３１－４１ When viewed from the pushing direction of the first die 31 (i.e., the plate thickness direction of the flange portion 12, the Z direction), the clearance when the first die 31 and the first punch 41 are separated from each other is referred to as a positive clearance, and the clearance when the first die 31 and the first punch 41 are partially overlapping is referred to as a negative clearance. In this specification, regarding the clearance between the die and the punch, a positive clearance is represented by a positive value, and a negative clearance is represented by a negative value.

[0070] As shown in Figure 6, the first die 31 and the first punch 41 that cut the first element body 2 in half are arranged so that the first die 31 and the first punch 41 partially overlap when viewed from the pushing direction of the first die 31. ３１－４１ If the clearance C is set to a positive value, cracks generated from the cutting edges of the first die 31 and the first punch 41 may meet, as in a single punching operation, and the removed portion 20a may be completely cut off from the flange portion body 20. In addition, the sagging 13b of the cut end 13 will increase. ３１－４１ By making the clearance a negative clearance, it is possible to prevent the removed portion 20a from being completely cut off from the flange portion body 20 in the half-cutting step, and to reduce the sagging 13b.

[0071] Also, clearance C ３１－４１By making the clearance between the first die 31 and the first punch 41 negative, large hydrostatic stress is generated in the region sandwiched between the first die 31 and the first punch 41. Therefore, the proportion of tensile stress generated between the material that will become scrap (i.e., the removed portion 20a) after cutting and the flange material that will become the flange 12 is reduced in the stress generated when the first die 31 is pressed into the flange element 20. As a result, the material that will become scrap after cutting and that contacts the tip of the cutting edge of the first die 31 is more likely to flow from the tip of the cutting edge of the first die 31 toward the side surface 31a of the first die 31, thereby increasing the spread of the plating layer 13f around the sheared surface 13c. Furthermore, the reduction in the proportion of tensile stress increases compressive stress, and the material that would normally flow toward the scrap side is pushed back toward the flange 12. As a result, the material that will become sagging 13b after cutting is filled with material, thereby reducing the size of the sagging 13b.

[0072] In the direction in which the first die 31 and the first punch 41 are adjacent to each other (the X direction in FIG. 6 ), the shorter the length of the material that will become scrap after cutting is, the more likely the material will flow from the tip of the cutting edge of the first die 31 toward the side surface 31 a of the first die 31. For this reason, it is preferable to perform half-cutting by positioning the first die 31 so that the side surface 31 a of the first die 31 is located within a range from the end of the flange portion element 20 that is not more than twice the plate thickness of the flange portion element 20 (i.e., the flange portion 12).

[0073] Clearance C between the first die 31 and the first punch 41 ３１－４１ [mm] is set to be −0.01 mm or less and −0.25 times or more the thickness t1 [mm] of the flange portion element 20 (i.e., the flange portion 12) of the first element 2, as shown in the following formula (a1).

[0074] −0.25×t1≦C ３１－４１ ≦-0.01...(a1)

[0075] Clearance C ３１－４１If the clearance C is -0.01 mm or less, a partial positive clearance will not occur due to the sliding accuracy of the press machine or misalignment of the die, and a negative clearance can be maintained. As a result, a crack will not occur during partial cutting, causing a complete cut and resulting in a large fracture surface. On the other hand, if the clearance C is ３１－４１ is equal to or greater than -0.25 times the plate thickness t1 of the flange portion element 20, the forming load required for half-cutting will not increase and will not exceed the press capacity. Therefore, the burden on the die is small, and it is possible to suppress a decrease in the die life. ３１－４１ The upper limit of the clearance C may be set to −0.05 or −0.10 times the plate thickness t1 of the flange portion element 20. ３１－４１ The upper limit of the thickness t1 of the flange portion element 20 may be set to −0.20 or −0.15 times the thickness t1 of the flange portion element 20.

[0076] The cutting edge of the first die 31 is rounded with a radius of curvature R1 as shown in Fig. 6. As shown in Fig. 6, the first die 31 is pressed into the flange portion body 20, so the cutting edge of the first die 31 is rounded with a radius of curvature R1.

[0077] The radius of curvature R1 [mm] is set to be 0.10 to 0.50 times the plate thickness t1 [mm] of the flange portion element 20 (i.e., the flange portion 12) of the first element 2, as shown in the following formula (a2).

[0078] 0.1×t1≦R1≦0.5×t1 (a2)

[0079] If the radius of curvature R1 is 0.10 times the sheet thickness t1 or more, a large hydrostatic force is generated under a negative clearance without scraping away the plating layer 13f, causing the material in contact with the cutting edge of the first die 31, which will become scrap directly below the first die 31, to flow from the cutting edge toward the side surface 31a of the first die 31. This flow reduces the proportion of tensile stress generated between the material that will become scrap (i.e., the removed portion 20a) after cutting and the flange material that will become the flange portion 12, among the stresses generated when the first die 31 is pressed into the flange portion element 20. As a result, the sheared surface 13c can be caused to flow around the plating layer 13f. On the other hand, if the radius of curvature R1 is 0.50 times the sheet thickness t1 or less, less material is present at the cutting edge of the first die 31 during half-cutting, thereby reducing the generation of fractured surfaces 13d during the subsequent finish cut.

[0080] The cutting edge of the first punch 41 is rectangular and not rounded, as shown in Fig. 6. In this case, the cutting edge of the first punch 41 may have a radius of curvature that is less than 0.1 times the thickness t1 of the flange portion element 20 of the first element 2. The radius of curvature of the cutting edge of the first punch 41 may also be less than 0.06 times, less than 0.04 times, or less than 0.02 times the thickness t1 of the flange portion element 20 of the first element 2, as necessary.

[0081] The pushing amount D [mm] of the first die 31 into the flange portion element 20 of the first element 2 is set to be 0.70 times or more the plate thickness t1 [mm] of the flange portion element 20 (i.e., the flange portion 12) of the first element 2, as shown in the following formula (a3). The pushing amount D is the amount of movement of the first die 31 from the position where the first die 31 contacts the upper surface of the flange portion element 20 of the first element 2 to the position where the pushing of the first die 31 stops (hereinafter, this position will also be referred to as the "bottom dead center"). In addition, the distance C between the first die 31 and the first punch 41 at the bottom dead center is Ｐ－Ｄ [mm] is set to 0.20 mm or more as shown in the following formula (a4).

[0082] D≧0.70×t1...(a3) C Ｐ－Ｄ ≧0.20...(a4)

[0083] The remaining thickness t2 of the flange portion blank 20 (i.e., the removed portion 20a) remaining on the first blank 2 after half-cutting may be 0.30 times or less the thickness t1 [mm] of the flange portion blank 20. Here, the remaining thickness t2 is the remaining thickness on the surface of the cut end portion 13 of the workpiece 1 (this surface faces the inner peripheral surface of the first die 31). If the push-in amount D is 0.70 times or more the thickness t1, it becomes difficult to generate a fracture surface 13d in the subsequent finish cutting. On the other hand, the distance C between the first die 31 and the first punch 41 at the bottom dead center Ｐ－Ｄ By ensuring that the gap C is 0.20 mm or more, it is possible to prevent cracks from occurring during partial cutting, which can result in partial complete cutting. In addition, the burden on the mold is small, and the reduction in the mold life can be suppressed. Ｐ－Ｄ is the minimum value of the distance between the first die 31 and the first punch 41 at the bottom dead center.

[0084] The pushing amount D [mm] of the first die 31 into the flange portion element 20 (i.e., the flange portion 12) of the first element 2 may be at least 0.70 times the plate thickness t1 of the flange portion element 20 (i.e., the flange portion 12) of the first element 2, as shown in the above formula (a3), but may also be at most 0.95 times (0.70 × t1 ≦ D ≦ 0.95 × t1).

[0085] The remaining thickness t2 is the thickness t1 of the flange portion blank 20 (i.e., the flange portion 12) minus the amount of pressing D of the first die 31 into the flange portion blank 20 plus the radius of curvature R1 (t2=t1-D+R1). Therefore, the remaining thickness t2 is the distance C between the first die 31 and the first punch 41 at the bottom dead center. Ｐ－Ｄ If the pushing amount D is 0.70 times the plate thickness t1 or more, it is difficult for the fracture surface 13d to be generated in the subsequent finish cutting. On the other hand, if the pushing amount D is 0.95 times the plate thickness t1 or less, cracks may occur during partial cutting due to the slide accuracy of the press machine or misalignment of the die, resulting in complete cutting, and large fracture surfaces will not be generated.

[0086] (Finish Cutting Process) In the finish cutting process, as shown in Fig. 7 , the half-cut flange portion element 20 is finish-cut using a second die 32 and a second punch 42. Fig. 7 shows, as one mode of finish cutting, a mode in which the flange portion 12 is finish-punched out from the flange portion element 20 held between the second punch 42 and the second plate holder 52. The second die 32 constitutes a cutting mold that is pressed into the flange portion element 20 in the finish cutting. In this embodiment, the second punch 42 is the mold that presses the portion of the flange portion element 20 that will become the flange portion 12, and the second die 32 is the mold that presses the removed portion 20a. The second die 32 may be the same as the first die 31. In other words, the first die 31 used in the half-cutting process may be used as the second die 32 in the finish cutting process.

[0087] The positional relationship between the second die 32 and the first element body 2 is preferably the same as the positional relationship between the first die 31 and the first element body 2. If these positional relationships are not the same, for example, if the diameter of the second die 32 is larger than the diameter of the first die 31, a step will occur at the cut edge 13. Conversely, for example, if the diameter of the second die 32 is smaller than the diameter of the first die 31, the second die 32 will come into contact with the half-cut cut edge produced in the half-cutting step, and the second die 32 may scrape off the plating layer 13f that has wrapped around the sheared surface 13c.

[0088] The finish cutting according to this embodiment is performed from the same direction as the half cutting. That is, when the first die 31 is forced into the flange portion element 20 from the upper surface side of the flange portion element 20 in the half cutting as shown in Fig. 6, the second die 32 is also forced into the flange portion element 20 from the upper surface side of the flange portion element 20 in the finish cutting as shown in Fig. 7. This separates the removed portion 20a from the flange portion element 20. This separates the removed portion 20a from the flange portion element 20.

[0089] Clearance C between the second die 32 and the second punch 42 ３２－４２ [mm] is the positive clearance. Clearance C ３２－４２is expressed as the distance between the side surface 32 a of the second die 32 and the side surface 42 a of the second punch 42. Here, as in the half-cutting process, the clearance when the second die 32 and the second punch 42 are separated from each other is called a positive clearance, and the clearance when the second die 32 and the second punch 42 are partially overlapping each other is called a negative clearance.

[0090] Clearance C between the second die 32 and the second punch 42 ３２－４２ is set to be 0.01 mm or more and 0.2 times or less the remaining plate thickness t2 of the removed portion 20a remaining in the flange portion body 20 of the first body 2 after half-cutting, as shown in the following formula (5).

[0091] 0.01≦C ３２－４２ ≦0.2×t2 (5)

[0092] Clearance C ３２－４２ If the clearance C is 0.01 mm or more, there is no risk of damage due to contact between the second die 32 and the second punch 42 even if the slide accuracy of the press machine or the center misalignment of the die occurs during the finish cutting. ３２－４２ If is 0.2 times or less the remaining plate thickness t2, burrs 13e are less likely to be generated.

[0093] The cutting edge of the second die 32 is rounded with a radius of curvature R2. As shown in FIG. 7 , the second die 32 is pressed into the portion of the flange portion blank 20 where the finish cutting is performed, so the cutting edge of the second die 32 is rounded with a radius of curvature R2. The cutting edge of the second punch 42 is squared without any rounding, as shown in FIG. 7 . In this case, the cutting edge of the second punch 42 may have a radius of curvature of less than 0.25 mm, less than 0.15 mm, less than 0.10 mm, or less than 0.05 mm. Alternatively, the radius of curvature of the cutting edge of the second punch 42 may be less than 0.1 times the thickness t1 of the flange portion blank 20 of the first blank 2, and may be less than 0.06 times, less than 0.04 times, or less than 0.02 times, as necessary.

[0094] The radius of curvature R2 [mm] is set to 0.25 mm or more and 1.50 times or less the remaining plate thickness t2 of the half-cut portion, as shown in the following formula (6).

[0095] 0.25≦R2≦1.50×t2 (6)

[0096] If the radius of curvature R2 is 0.25 mm or more, the plating layer 13f that has reached the sheared surface 13c is not scraped off by the second die 32. On the other hand, if the radius of curvature R2 is 1.50 times the remaining sheet thickness t2 or less, burrs 13e are less likely to be generated.

[0097] In addition, when the cut end portion is formed on the outer periphery of the workpiece 1, the inner diameter D ３２ is the inner diameter D of the first die 31 ３１ In the case where the cut end is formed on the inner periphery of the workpiece 1, the outer diameter d ３２ is the outer diameter d of the first die 31 ３１ Specifically, when the cut end portion is formed on the outer periphery of the workpiece 1, the inner diameter D of the first die 31 is ３１ and the inner diameter D of the second die 32 ３２ Absolute value of the difference |D ３２ -D ３１ In the case where the cut end portion is formed on the inner periphery of the workpiece 1, the outer diameter d ３１ and the outer diameter d of the second die 32 ３２ Absolute value of the difference |d ３２ -d ３１ It is desirable that | is 1.00 mm or less. In this way, the diameter difference D between the dies 31 and 32 is set to 1.00 mm or less in order to perform two steps, namely, the half-cutting step and the finish-cutting step. ３２ -D ３１ or d ３２ -d ３１ This makes it possible to reduce the step that occurs at the cut end 13 of the processed product 1, and to obtain a good cut cross section.

[0098] In addition, when a step at the cut end 13 is acceptable as the quality of the processed product 1, the absolute value of the inner diameter difference |D ３２ -D ３１ |, the absolute value of the outer diameter difference when the cut end is formed on the inner periphery of the workpiece 1 |d ３２ -d ３１ | may be greater than 1.00 mm. In addition, the absolute value of the diameter difference |D ３２ -D ３１| and |d ３２ -d ３１ The upper limit of | is preferably small, and may be set to 0.75 mm, 0.50 mm, 0.35 mm, or 0.20 mm. ３２ -D ３１ | and |d ３２ -d ３１ The lower limit of | is 0 mm. The step generated at the cut end 13 of the processed product 1 is preferably small, and may be 0.5 mm or less. The upper limit of the step generated at the cut end 13 of the processed product 1 may be 0.4 mm, 0.3 mm, 0.2 mm, or 0.1 mm, as necessary.

[0099] (b. When the cutting edges of the die and punch used in the semi-cutting process are rounded) Next, the semi-cutting process and the finish-cutting process when the cutting edges of the die and punch used in the semi-cutting process are rounded will be described with reference to Fig. 8 and Fig. 9. Fig. 8 is an explanatory diagram showing the semi-cutting process when the cutting edges of the die and punch used in the semi-cutting process are rounded. Fig. 9 is an explanatory diagram showing the finish-cutting process that is performed following the semi-cutting process in Fig. 8.

[0100] (Half-Cutting Process) In the half-cutting process, as shown in Fig. 8, the flange portion element 20 of the first element 2 is half-cut using a first die 31 and a first punch 41. As with Fig. 6, Fig. 8 shows, as one mode of half-cutting, a mode in which the flange portion 12 is half-punched from the flange portion element 20 held between the first punch 41 and the first plate holder 51. The first die 31 constitutes a cutting mold that is pressed into the flange portion element 20 during half-cutting. In this embodiment, the first punch 41 is the mold that presses the portion of the flange portion element 20 that will become the flange portion 12, and the first die 31 is the mold that presses the removed portion 20a.

[0101] Clearance C between the first die 31 and the first punch 41 ３１－４１ is a negative clearance. Therefore, as shown in Figure 8, the first die 31 and the first punch 41 that cut the first body 2 in half are arranged so that the first die 31 and the first punch 41 partially overlap when viewed from the pushing direction of the first die 31. ３１－４１By making the clearance C a negative, it is possible to prevent the removal portion 20a from being completely cut off from the flange portion body 20 in the half-cutting step, and to reduce the sagging 13b. ３１－４１ The meanings of the negative clearance and positive clearance are the same as those in the above embodiment a.

[0102] Also, clearance C ３１－４１ By making the clearance between the first die 31 and the first punch 41 negative, large hydrostatic stress is generated in the region sandwiched between the first die 31 and the first punch 41. Therefore, the proportion of tensile stress generated between the material that will become scrap (i.e., the removed portion 20a) after cutting and the flange material that will become the flange 12 is reduced in the stress generated when the first die 31 is pressed into the flange element 20. As a result, the material that will become scrap after cutting and that contacts the tip of the cutting edge of the first die 31 is more likely to flow from the tip of the cutting edge of the first die 31 toward the side surface 31a of the first die 31, thereby increasing the spread of the plating layer 13f around the sheared surface 13c. Furthermore, the reduction in the proportion of tensile stress increases compressive stress, and the material that would normally flow toward the scrap side is pushed back toward the flange 12. As a result, the material that will become sagging 13b after cutting is filled with material, thereby reducing the size of the sagging 13b.

[0103] In the direction in which the first die 31 and the first punch 41 are adjacent to each other (the X direction in FIG. 8 ), the shorter the length of the material that will become scrap after cutting is, the more likely the material is to flow from the tip of the cutting edge of the first die 31 toward the side surface 31 a of the first die 31. For this reason, the first die 31 is positioned so that the side surface 31 a of the first die 31 is located within a range from the end of the flange portion element 20 that is not more than twice the plate thickness of the flange portion element 20 (i.e., the flange portion 12), and half-cutting is performed.

[0104] Clearance C between the first die 31 and the first punch 41 ３１－４１ [mm] is set to be not more than −0.10 and not less than −0.35 times the plate thickness t1 [mm] of the flange portion element 20 (i.e., the flange portion 12) of the first element 2, as shown in the following formula (b1).

[0105] −0.35×t1≦C ３１－４１ ≦-0.10×t1...(b1)

[0106] Clearance C ３１－４１ is less than or equal to -0.10 times the plate thickness t1 of the flange portion element 20, large hydrostatic stress occurs in the region sandwiched between the first die 31 and the first punch 41, and the proportion of tensile stress decreases. As a result, cracks do not occur during half-cutting, causing complete cutting, and large fracture surfaces do not occur, so it is possible to prevent the removed portion 20a from being completely cut from the flange portion element 20 in the half-cutting step. On the other hand, if the clearance C ３１－４１ is equal to or greater than -0.35 times the plate thickness t1 of the flange portion element 20, the forming load required for half-cutting will not increase and will not exceed the press capacity. Therefore, the burden on the die is small, and it is possible to suppress a decrease in the die life. ３１－４１ It is more preferable that the clearance C is not more than −0.15 times or not more than −0.20 times the plate thickness t1 of the flange portion element 20. ３１－４１ may be set to be −0.30 times or more or −0.25 times or more the plate thickness t1 of the flange portion element 20.

[0107] 8, the cutting edges of the first die 31 and the first punch 41 are rounded. The radius of curvature R11 [mm] of the cutting edge of the first die 31 and the radius of curvature R12 [mm] of the cutting edge of the first punch 41 are set to be 0.10 to 0.65 times the thickness t1 [mm] of the flange portion element 20 (i.e., the flange portion 12) of the first element 2, as shown in the following formulas (b2-1) and (b2-2). Note that the radius of curvature R11 of the cutting edge of the first die 31 and the radius of curvature R12 of the cutting edge of the first punch 41 may be the same or different.

[0108] 0.10×t1≦R11≦0.65×t1 (b2-1) 0.10×t1≦R12≦0.65×t1 (b2-2)

[0109] If the radii of curvature R11 and R12 are 0.10 times the sheet thickness t1 or more, a large hydrostatic force is generated under a negative clearance without scraping away the plating layer 13f, allowing the material to become scrap directly below the first die 31 to flow from the cutting edge of the first die 31 toward the side surface 31a of the first die 31. This flow reduces the proportion of tensile stress generated between the material to become scrap (i.e., the removed portion 20a) after cutting and the flange material to become the flange portion 12, among the stresses generated when the first die 31 is pressed into the flange portion element 20. As a result, the sheared surface 13c can be caused to flow around the plating layer 13f. On the other hand, if the radii of curvature R11 and R12 are 0.65 times the sheet thickness t1 or less, less material is present at the cutting edge of the first die 31 during half-cutting, thereby reducing the generation of fractured surfaces 13d in the subsequent finish-cutting.

[0110] The pushing amount D [mm] of the first die 31 into the flange portion element 20 (i.e., the flange portion 12) of the first element 2 is set to be 0.70 times or more the plate thickness t1 [mm] of the flange portion element 20 (i.e., the flange portion 12) of the first element 2, as shown in the following formula (b3). The pushing amount D is the amount of movement of the first die 31 from the position where the first die 31 contacts the upper surface of the flange portion element 20 of the first element 2 to the position (bottom dead center) where the pushing of the first die 31 stops. The distance C between the first die 31 and the first punch 41 at the bottom dead center is Ｐ－Ｄ [mm] is set to 0.20 mm or more as shown in the following formula (b4).

[0111] D≧0.70×t1...(b3) C Ｐ－Ｄ ≧0.20...(b4)

[0112] The remaining thickness t2 of the removed portion 20a remaining in the flange portion element 20 of the first element 2 after half-cutting may be 0.30 times or less the thickness t1 [mm] of the flange portion element 20. If the push-in amount D is 0.70 times or more the thickness t1, it becomes difficult for a fracture surface 13d to be generated in the subsequent finish cutting. On the other hand, the distance C between the first die 31 and the first punch 41 at the bottom dead center Ｐ－ＤBy ensuring that the gap C is 0.20 mm or more, it is possible to prevent cracks from occurring during partial cutting, which may result in partial complete cutting. Ｐ－Ｄ is the minimum value of the distance between the first die 31 and the first punch 41 at the bottom dead center.

[0113] By forming the cutting edges of the first die 31 and the first punch 41 into an R shape, it is possible to increase the amount of flange portion blank 20 cut out in the half-cutting step, compared to when the cutting edges of only one of the first die 31 or the first punch 41 are R-shaped, as shown in Fig. 6. In other words, by forming the cutting edges of the first die 31 and the first punch 41 into an R shape, it is possible to reduce the remaining plate thickness t2 of the removed portion 20a remaining in the flange portion blank 20 after half-cutting, compared to when the cutting edges of only one of the first die 31 or the first punch 41 are R-shaped, as shown in Fig. 6.

[0114] If only the cutting edge of the first die 31 is rounded as in the above-described embodiment a, the cutting edge of the first die 31 will come into contact with the cutting edge of the first punch 41 if the indentation amount D of the first die 31 is set to be equal to or greater than the thickness t1 of the flange portion 12. Therefore, in the above-described embodiment a, the indentation amount D of the first die 31 cannot be set to be equal to or greater than the thickness t1 of the flange portion 12. However, if the cutting edges of the first die 31 and the first punch 41 are rounded, the indentation amount of the first die 31 before it comes into contact with the cutting edge of the first punch 41 increases, as shown in FIG. 8 . Therefore, it is possible to cut a larger amount of the flange portion element 20 than in embodiment a, and the proportion of the sheared surface 13c in the cut end portion 13 can be increased. This allows the plating layer 13f to wrap around the sheared surface 13c more, thereby increasing the proportion of the cut end portion 13 covered by the plating layer 13f. Furthermore, by reducing the remaining plate thickness t2, the amount of cutting in the finish cutting step is reduced, and it is possible to avoid a situation in which no plating layer remains in part of the finish-cut portion.

[0115] (Finish Cutting Process) In the finish cutting process, as shown in Fig. 9, the half-cut flange portion blank 20 is finish-cut using the second die 32 and the second punch 42. The finish cutting process may be performed in the same manner as the finish cutting process shown in Fig. 7, which is performed after half-cutting is performed by forming the cutting edge of only one of the first die 31 or the first punch 41 into an R shape.

[0116] 9 shows, as one mode of finish cutting, a mode in which the flange portion 12 is finish-punched out from the flange portion element 20 held between the second punch 42 and the second plate holder 52. The second die 32 constitutes a cutting mold that is pressed into the flange portion element 20 during finish cutting. In this embodiment, the second punch 42 is the mold that presses the portion of the flange portion element 20 that will become the flange portion 12, and the second die 32 is the mold that presses the removed portion 20a. The second die 32 may be the same as the first die 31. In other words, the first die 31 used in the half-cutting step may be used as the second die 32 in the finish-cutting step.

[0117] The positional relationship between the second die 32 and the first element body 2 is preferably the same as the positional relationship between the first die 31 and the first element body 2. If these positional relationships are not the same, for example, if the diameter of the second die 32 is larger than the diameter of the first die 31, a step will occur at the cut edge 13. Conversely, for example, if the diameter of the second die 32 is smaller than the diameter of the first die 31, the second die 32 will come into contact with the half-cut cut edge produced in the half-cutting step, and the second die 32 may scrape off the plating layer 13f that has wrapped around the sheared surface 13c.

[0118] The finish cutting according to this embodiment is performed in the same direction as the half cutting. That is, when the first die 31 is pressed into the flange portion element 20 from the upper surface side of the flange portion element 20 in the half cutting as shown in Fig. 8, the second die 32 is also pressed into the flange portion element 20 from the upper surface side of the flange portion element 20 in the finish cutting as shown in Fig. 9. This separates the removed portion 20a from the flange portion element 20.

[0119] Clearance C between the second die 32 and the second punch 42 ３２－４２[mm] is a plus clearance. Clearance C between the second die 32 and the second punch 42 ３２－４２ As shown in the above formula (5), the clearance C is set to be 0.01 mm or more and 0.2 times or less the remaining plate thickness t2 of the removed portion 20a remaining in the flange portion body 20 of the first body 2 after half-cutting. ３２－４２ If the clearance C is 0.01 mm or more, the second die 32 and the second punch 42 will not come into contact with each other and be damaged even if there is a problem with the slide accuracy of the press machine or misalignment of the die during the finish cutting. ３２－４２ If is 0.2 times or less the remaining plate thickness t2, burrs 13e are less likely to be generated.

[0120] The cutting edge of the second die 32 is rounded with a radius of curvature R2. As shown in FIG. 9 , the second die 32 is pressed into the portion of the flange portion body 20 where the finish cutting is performed, so the cutting edge of the second die 32 is rounded with a radius of curvature R2. The cutting edge of the second punch 42 may be rectangular with no rounding as shown in FIG. 9 , or may have a radius of curvature. If the cutting edge of the second punch 42 is rectangular with no rounding, burrs generated at the tip of the fracture surface 13d can be reduced. The radius of curvature of the cutting edge of the second punch 42 may be less than 1.00 mm, less than 0.50 mm, less than 0.20 mm, less than 0.10 mm, or less than 0.05 mm. Alternatively, the radius of curvature of the cutting edge of the second punch 42 may be less than 0.3 times the plate thickness t1 of the flange portion body 20 of the first body 2, or, if necessary, less than 0.1 times, less than 0.06 times, less than 0.04 times or less than 0.02 times.

[0121] As shown in the above formula (6), the radius of curvature R2 [mm] is set to be 0.25 mm or more and 1.50 times or less the remaining sheet thickness t2 of the half-cut portion. If the radius of curvature R2 is 0.25 mm or more, the second die 32 does not scrape off the plating layer 13f that has reached the sheared surface 13c. On the other hand, if the radius of curvature R2 is 1.50 times or less the remaining sheet thickness t2, burrs 13e are less likely to be generated.

[0122] The above has described the method for manufacturing a processed product according to the first embodiment of the present invention. According to this embodiment, the method includes a half-cutting step in which a first element body 2 formed from a plated steel sheet and having a flange portion element 20 that will become the flange portion 12 is cut into half using a first die 31 and a first punch 41, the clearance between which is set to a negative clearance, and a finish-cutting step in which the half-cut flange portion element 20 is cut into half using a second die 32 and a second punch 42 in the same direction as the half-cutting, to obtain a processed product 1 having a cut edge 13 on the flange portion 12.

[0123] The cut end 13 of the flange portion 12 of the workpiece 1 cut through these two processes has a sag 13b, a shear surface 13c, and a fracture surface 13d, in that order, in the thickness direction T of the cut end 13. The shear surface 13c is at least partially covered by the plating layer 13f on the upper surface 13a. The ratio L / t1 of the remaining plating component length L, where the shear surface 13c is covered by the plating layer 13f1, to the thickness t1 of the cut end 13 of the workpiece 1 is 0.70 or more, and the length of the sag 13b in the thickness direction T of the cut end 13 is more than 0 times and less than 0.10 times the thickness t1 of the cut end 13 of the workpiece 1. In this way, the sag 13b of the cut end 13 of the workpiece 1 is prevented from becoming large, and more of the plating layer 13f wraps around the shear surface 13c. Even when a plated steel sheet having a thickness of more than 2.0 mm is used as the material, the corrosion resistance and shape quality can be improved.

[0124] If the length (sag X) of the sag 13b in the planar direction (XY plane direction) can be reduced, the amount of material used for the processed product 1 can be reduced. For example, as shown in FIG. 1 , screw holes 121 into which screws 123 for securing the processed product 1 are inserted are formed in the flange portion 12, avoiding the sag 13b, so that the screws 123 are secured to the flat portion. As shown in the upper part of FIG. 10 , if the sag X is large, the distance from the end of the flange portion 12 to the screw hole 121 becomes long, requiring extra material. On the other hand, as shown in the lower part of FIG. 10 , if the sag X is small, the distance from the end of the flange portion 12 to the screw hole 121 becomes short, allowing the amount of material used to form the flange portion 12 to be reduced. As such, the processed product manufacturing method according to this embodiment eliminates the need to oversize the blank to ensure a flat portion around the screw 123 required to secure the processed product 1.

[0125] Furthermore, the processed product manufacturing method according to this embodiment allows more plating layer 13f to be formed around shear surface 13c, thereby suppressing red rust that occurs on cut end 13 over time after cutting.

[0126] Furthermore, the clearance C between the second die 32 and the second punch 42 ３２－４２ is set to 0.01 mm or more and 0.2 times or less the remaining plate thickness t2 of the first element 2 (flange element 20) in the part that has been partially cut. This makes it possible to prevent damage due to contact with the cutting die during finish cutting, while suppressing the generation of burrs 13e.

[0127] The tip of the cutting edge of the second die 32, which is pressed into the portion of the first body 2 that is to be finish-cut, is curved with a radius of curvature R2 that is 0.25 mm or more and 1.50 times or less the remaining thickness t2 of the half-cut portion. This prevents the cutting die from scraping off the plating layer 13f that has reached the sheared surface 13c, while suppressing the generation of burrs 13e.

[0128] 2. Second Embodiment Next, a processed product manufacturing method according to a second embodiment of the present invention will be described with reference to Fig. 11. Fig. 11 is an explanatory view showing the processed product manufacturing method according to the second embodiment of the present invention. As shown in Fig. 11, the processed product manufacturing method according to this embodiment includes a preparation step, a semi-cutting step, a finish-cutting step, and a coining step.

[0129] The processed product manufacturing method according to this embodiment is a method in which a coining step is added to the processed product manufacturing method according to the first embodiment shown in Fig. 5. As shown in Fig. 11, in this embodiment, as in the first embodiment, the first element body 2 prepared in the preparation step is subjected to the half-cutting step and the finish-cutting step. Therefore, detailed description of the preparation step, half-cutting step, and finish-cutting step will be omitted.

[0130] In the coining step, the workpiece obtained in the finish cutting step is used as the second element 6 and is subjected to a coining process. In the coining step, after the finish cutting step, the corner 13g of the cut end 13 on the fracture surface 13d side is pressed against a pad (pad 7 in FIG. 12 ) to obtain a workpiece 1 having a coining surface 13h formed on the corner. The coining process can narrow the area of ​​the fracture surface 13d, which is a newly formed rough surface, and can suppress the area where red rust occurs. In addition, the coining process can crush burrs 13e, more reliably suppressing the burrs 13e from remaining in the workpiece 1.

[0131] The coining process will be described in more detail with reference to Figures 12 to 14. Figure 12 is an explanatory diagram illustrating the coining process. Figure 13 shows the cut end of the processed product 1 after the coining process, with the left side being a cross-sectional view in the ZX plane including the central axis of the processed product 1, and the right side being a side view from the X direction. Figure 14 is a photograph showing an example of the cut end of the processed product 1 after the coining process. Note that, as with Figure 2, the plating layer 13f is not shown in Figure 13.

[0132] 12 , in the coining step according to this embodiment, the cut end portion 13 of the second element body 6 is sandwiched between a pad 7 and a coining block 8. The pad 7 has a vertical wall surface 70, a bottom wall surface 71, and a pressing surface 72.

[0133] The vertical wall surface 70 is disposed so as to face and be substantially parallel to the shear surface 13c of the second element 6 when the cut end portion 13 of the second element 6 is sandwiched between the pad 7 and the coining block 8. The vertical wall surface 70 is disposed so as to be parallel to the direction in which the coining block 8 advances and retreats (the Z direction in FIG. 12 ).

[0134] The bottom wall surface 71 is disposed so as to face the coining block 8 in the plate thickness direction of the flange portion 12, with the second element body 6 interposed therebetween. The bottom wall surface 71 extends in a direction perpendicular to the vertical wall surface 70 below the vertical wall surface 70 (i.e., on the opposite side from the coining block 8).

[0135] The pressing surface 72 is a surface that connects the bottom wall surfaces 71 to each other. The pressing surface 72 is provided to form a coining surface (coining surface 13h in FIG. 13) on the second element body 6, and is formed in a shape corresponding to the shape of the coining surface. For example, as shown in FIG. 13, if the coining surface 13h is a flat chamfered surface (hereinafter referred to as a "C surface"), the pressing surface 72 may be a flat surface that is inclined relative to the vertical wall surface 70 and the bottom wall surface 71. Furthermore, if the coining surface 13h is a curved surface (which may be either a pressing surface or a compression surface; hereinafter referred to as an "R surface"), the pressing surface 72 may be a curved surface.

[0136] 12 , with the cut end 13 of the second element 6 facing the vertical wall surface 70 of the pad 7, the second element 6 is sandwiched in the plate thickness direction T between the coining block 8 and the bottom wall surface 71 of the pad 7. The coining block 8 is then pressed toward the bottom wall surface 71, pressing the second element 6 down until the bottom surface 13k of the second element 6 contacts the bottom wall surface 71. Here, before the bottom surface 13k of the second element 6 contacts the bottom wall surface 71, the corner 13g is pressed against the pressing surface 72. After the corner 13g is pressed against the pressing surface 72, the coining block 8 is pressed further, and the bottom surface 13k of the second element 6 contacts the bottom wall surface 71. The corner 13g is crushed by the pressing surface 72 to form a coining surface 13h. After the coining process, the cut end 13 of the workpiece 1 is in a state such as that shown in the photograph of FIG.

[0137] The coining surface 13h is a smooth surface onto which the pressing surface 72 is transferred, and is therefore less susceptible to red rust than the rough fracture surface 13d. This is thought to be because the smooth surface roughness makes it difficult for moisture to remain on the coining surface 13h. Another factor that contributes to the resistance to red rust is that the plating layer 13f on the bottom surface 13k of the cut end 13 is thinly spread on the coining surface 13h. By forming the coining surface 13h on the corner 13g on the fracture surface 13d side, the fracture surface length W2 (see FIG. 13 ) in the thickness direction T of the flange portion 12 after coining is shorter than the fracture surface length W1 (see FIGS. 2 and 3 ) in the thickness direction T of the flange portion 12 before coining. In other words, the coining process narrows the area of ​​the fracture surface 13d, which is a newly roughened surface, thereby suppressing the area where red rust occurs. Furthermore, the coining process can crush the burrs 13e, and the burrs 13e remaining on the processed product 1 can be more reliably prevented.

[0138] In the coining process, the pressing surface 72 is pressed against the corner 13g so that the length W2 (fracture surface length) of the fracture surface 13d between the shear surface 13c and the coining surface 13h in the thickness direction T of the flange portion 12 of the processed product 1 is greater than 0 mm and not greater than 0.5 mm. By setting the fracture surface length W2 to greater than 0 mm and not greater than 0.5 mm, even if red rust occurs on the fracture surface 13d, it is inconspicuous and can be determined that this does not pose a practical problem.

[0139] In the finish cutting process, it is preferable to obtain a second element body 6 having a fracture surface length W1 in the thickness direction T of less than 1.0 mm. By obtaining a second element body 6 having a fracture surface length W1 of less than 1.0 mm, it is possible to more reliably achieve a fracture surface length W2 of 0.5 mm or less in the coining process. The fracture surface length W2 of the workpiece 1 is preferably small, and may be 0.4 mm or less or 0.3 mm or less. It is more preferable to set the fracture surface length W2 of the workpiece 1 to 0.2 mm or less or 0.1 mm or less. Furthermore, the ratio W2 / t1 of the fracture surface length W2 to the thickness t1 of the cut end portion 13 of the workpiece 1 may be less than 0.15, less than 0.10, less than 0.08, less than 0.06, or less than 0.04. The fracture surface length W2 of the workpiece 1 may be 0 mm. In other words, the cut end portion 13 of the workpiece 1 may not have a fracture surface 13d. 13 , the cut end 13 may have, in the thickness direction of the cut end 13, a sag 13b, a shear surface 13c, a fracture surface 13d, and a coining surface 13h, in that order. Alternatively, the cut end 13 may have, in the thickness direction of the cut end 13, a sag 13b, a shear surface 13c, and a coining surface 13h, in that order.

[0140] 15 is an explanatory diagram showing the volume of the corner 13g crushed by the pressing surface 72 of the pad 7 in FIG. 12. As the coining block 8 in FIG. 12 is pressed down toward the bottom wall surface 71 of the pad 7, the corner 13g comes into contact with the pressing surface 72 and is crushed. The material (base steel) of the crushed corner 13g moves along the pressing surface 72 toward the shear surface 13c. When the cut end 13 is pressed down to a position where the bottom surface 13k of the cut end 13 contacts the bottom wall surface 71, the volume V1 of the corner 13g of the flange 12 crushed by the pressing surface 72 changes depending on the position and angle of the pressing surface 72, etc.

[0141] In the coining process, as shown in the upper part of Figure 15, it is preferable that the volume V1 of the corner 13g crushed by the pressing surface 72 be equal to or smaller than the volume V2 of the coining space surrounded by the extension surface 13j of the shear surface 13c, the fracture surface 13d, and the pressing surface 72. As shown in Figure 12, the fracture surface 13d of the cut end 13 of the flange portion 12 is inclined relative to the vertical wall surface 70, leaving a gap therebetween. The volume V2 of the coining space created by this gap becomes a space into which the material of the corner 13g crushed by the pressing surface 72 flows. If the volume V2 of the coining space is smaller than the volume V1 of the corner 13g crushed by the pressing surface 72, the material of the corner 13g crushed by the pressing surface 72 cannot be contained within the volume V2 and will move toward the top of the pad 7.

[0142] Therefore, by setting the volume V1 to be equal to or less than the volume V2, it is possible to prevent the material of the corner 13g crushed by the pressing surface 72 from protruding beyond the extension 13j of the sheared surface 13c. As shown in the lower part of Figure 15, if the volume V1 exceeds the volume V2, the material of the corner 13g crushed by the pressing surface 72 will protrude beyond the extension 13j of the sheared surface 13c and move toward the top of the pad 7. If this occurs, the dimensional accuracy of the cut end 13 will deteriorate. Therefore, it is preferable to process the corner 13g by crushing it with the pressing surface 72 so that the volume V1 is equal to or less than the volume V2.

[0143] The above has described the method for manufacturing a machined product according to the second embodiment. According to this embodiment, as in the first embodiment, it is not necessary to make the blank dimensions excessively large in order to ensure a flat portion around the screw 123 required for fastening the machined product 1. Furthermore, since a larger amount of the plating layer 13f can be made to extend around the sheared surface 13c, it is possible to suppress red rust that occurs on the cut end 13 over time after cutting.

[0144] Furthermore, by performing a coining process after the finish cutting process, the area of ​​the fracture surface 13d, which is a newly formed rough surface, can be narrowed, and the area where red rust occurs can be suppressed. Furthermore, since the coining process can crush the burrs 13e, the remaining burrs 13e on the processed product 1 are less than 0.2 mm, which more reliably suppresses the remaining burrs 13e. The length of the burrs 13e is preferably less than 0.1 mm, and more preferably less than 0.05 mm or less than 0.01 mm. It is most preferable that the length of the burrs 13e is 0 mm, i.e., no burrs 13e are present on the processed product 1.

[0145] [3. Example of Workpiece] In the above embodiment, the case where the workpiece 1 is a motor case as shown in FIG. 1 has been described. However, the workpiece 1 manufactured by the workpiece manufacturing method according to this embodiment may be any article made of a plated steel sheet and having a cut end portion 13.

[0146] The processed product 1 may be, for example, a circular flat washer 900 as shown in Fig. 16 . The processed product 1 may also be, for example, a flat washer 910A, 910B, or 910C having teeth 911 as shown in Fig. 17 . Alternatively, the processed product 1 may be, for example, a corrugated circular disc spring 920 as shown in Fig. 18 . The disc spring 920 in Fig. 18 may be manufactured by corrugating the flat washer 900 shown in Fig. 16 . Furthermore, the processed product may be, for example, a disc spring 930 having teeth 931 as shown in Fig. 19 .

[0147] 16 to 19 , the outer periphery and inner periphery of the workpiece 1 become the cut end 13. By applying the workpiece manufacturing method according to the above embodiment, at least one of the outer periphery and inner periphery can be made such that the ratio L / t1 of the remaining plating component length L where the sheared surface 13c is covered with the plating layer 13f1 in the thickness direction T of the workpiece 1 to the thickness t1 of the cut end 13 of the workpiece 1 is 0.70 or more, and the length of the sag 13b is less than 0.10 times the thickness t1 of the cut end 13 of the workpiece 1.

[0148] For example, in order to cover the sheared surfaces of the inner and outer peripheral surfaces of the flat washer 900 shown in Fig. 16 with a plating layer, it is sufficient to process it using a cutting die as shown in Fig. 20 and Fig. 21. Fig. 20 is a schematic diagram showing an example of a cutting die for processing the flat washer 900. Fig. 21 is a schematic diagram showing the state after blanking the element 9 using the cutting die of Fig. 20.

[0149] The cutting die shown in FIG. 20 is a die for manufacturing an annular workpiece 90 such as a flat washer 900, and includes a hollow cylindrical die (hereinafter referred to as the "outer die") 61, a cylindrical die (hereinafter referred to as the "inner die") 63, and a hollow cylindrical punch 65 that supports a disk-shaped blank 9 (see FIG. 21). The outer die 61, the inner die 63, and the punch 65 are arranged opposite each other, and the blank 9 is cut by pressing the outer die 61 and the inner die 63 into the blank 9 supported by the punch 65. The inner diameter of the outer die 61 corresponds to the outer diameter of the workpiece 90, and the outer diameter of the inner die 63 corresponds to the inner diameter of the workpiece 90. The cutting edges on the inner peripheral surface of the outer die 61 and the outer peripheral surface of the inner die 63 have an R-shape with a radius of curvature. On the other hand, the edges of the inner and outer peripheral surfaces of the punch 65 do not have an R-shape.

[0150] When the blank 9 is finish-cut using such a cutting die, as shown in Fig. 21 , a portion 9a that is outer than an outer peripheral surface 91 of the processed product 90 is cut by the outer die 61, and a portion 9b that is inner than an inner peripheral surface 92 of the processed product 90 is cut by the inner die 63. This results in the formation of the processed product 90 (flat washer 900) as shown in Fig. 20 . At this time, the shear surfaces of the outer peripheral surface 91 and the inner peripheral surface 92 of the processed product 90 have a ratio L / t1 of the remaining length L of the plating component covered by the plating layer to the thickness t1 of the cut end of the processed product 90 of 0.70 or more, and the length of the sagging in the thickness direction of the cut end can be less than 0.10 times the thickness t1 of the cut end of the processed product 90.

[0151] Furthermore, the processed product 1 may be, for example, a disk-shaped plate 940 as shown in FIG.

[0152] (Example a: Case where only the cutting edge of the die used in the semi-cutting process is rounded) The shoulder of the die (i.e., the cutting edge) in the semi-cutting process is rounded with a predetermined radius of curvature, and processed product samples were prepared by the methods shown in Figures 5 and 11. The plated steel sheets had a thickness of 1.4 to 3.8 mm and a coating weight of 90 g / m ２ (one side) or 190 g / m ２ A Zn-6%Al-3%Mg (by mass) alloy plated steel sheet (one side) was used. ３１ The plated steel sheet was held by a sheet presser using a round die with a diameter of 85.00 mm and a punch whose diameter was changed depending on the clearance between the die and the punch. The finish cutting was performed using a die whose shoulder (i.e., cutting edge) was R-shaped with a predetermined radius of curvature and a clearance between the die and the punch C ３２－４２ Depending on the diameter D ３２ The test was carried out using a punch with a different shape and holding the plated steel sheet with a sheet presser.

[0153] For each sample, the sag Z, sag X, and fracture surface length after finish cutting (W1), as well as the fracture surface length after coining (W2) if coining was performed, were measured. These were measured using a microscope at 30° intervals around the circumference of the end face of the processed product, and a total of 12 measurements were averaged. Furthermore, for each sample, the wraparound of the plating layer around the cut end was measured by measuring the length L of the plating layer wraparound in the thickness direction of the plated steel sheet from the cross section of the center of the straight side of the processed product. An electron probe microanalyzer (EPMA-WDS) was used to measure the length L of the plating layer at the cut end. The presence of a plating layer was determined in areas where the detection level of Zn components was three times or more the background level. The objects of measurement were the processed product after finish cutting or the second element and the processed product after coining.

[0154] At the cut end of each sample, the sagging, shear surface, fracture surface and coining surface are as shown in FIG. 14, and more specifically, they appear as follows.

[0155] The sag appears as a smooth surface created by the compression (pressure) force applied after the die contacts the workpiece, stretching the surface of the workpiece. As shown in Figure 3, when the cut edge is viewed from the side, it has a curved shape.

[0156] The shear surface appears as a smooth surface at the cut edge. The shear surface is created when the die comes into contact with the workpiece and then a compressive (pressure) force is applied, causing the workpiece to bite into the die and rub against the side of the die. Because it is created by rubbing against the die, the shear surface has a metallic luster. Fine, streaky scratches can be seen on the shear surface in the thickness direction of the plate.

[0157] The fracture surface is the surface where cracks that have formed in the workpiece from the sheared surface meet and break, and appears as a dull, rough surface. After the sheared surface has formed in the workpiece, when the die further penetrates into the workpiece, cracks are formed in the workpiece by the cutting edge of the punch, and also by the cutting edge of the die. The cracks that have formed from the punch and die meet and penetrate each other. The surface formed by these cracks is the fracture surface. Because the fracture surface is formed without contact between the punch and die, it is a dull, rough surface. The fracture surface has a slope that corresponds to the gap (clearance) between the punch and die.

[0158] A coining surface appears as a smooth surface where the irregularities on the fracture surface have been flattened. A coining surface is obtained by pressing a sloped or curved coining die against the corner of the fracture surface from the underside of the edge of the fracture surface. The coining surface is a smooth surface where the irregularities on the fracture surface have been flattened by transferring the surface roughness of the coining die.

[0159] Methods for identifying sagging, shear surfaces, fracture surfaces, and coining surfaces at the cut end include, for example, observing and measuring the shape profile of the cut end from the appearance using a microscope or a contrast tracer based on the above characteristics.

[0160] From the viewpoint of ensuring flatness around the fixing screws, cut end 13 with a sag Z of less than 0.10 was evaluated as "A (Acceptable)," and cut end 13 with a sag Z of 0.10 or more was evaluated as "B (Not Acceptable)." Regarding burrs that can cause dents or electrical shorts, cut end 13 with a size of less than 0.2 mm was evaluated as "A (Acceptable)," and cut end 13 with a size of 0.2 mm or more or with whisker-like burrs was evaluated as "B (Not Acceptable)." Furthermore, it is desirable to minimize the occurrence of stepping on the end surface in terms of appearance and product dimensional accuracy. Therefore, cut end 13 with a step of 0.5 mm or less was evaluated as "A (Acceptable)," and cut end 13 with a step of more than 0.5 mm was evaluated as "B (Not Acceptable)."

[0161] The samples were also subjected to an outdoor atmospheric exposure test, and the number of days until noticeable red rust appeared on the cut edges was observed every 15 days.

[0162] The results are shown in Table 1. Table 1 also shows the plated steel sheets used for each sample, the conditions for the semi-cutting and finish-cutting processes, and whether or not coining was performed on the corners of the cut end. Here, the ratio of the die radius of curvature to the sheet thickness (R1 / t1, R2 / t2) is the ratio of the roundness imparted to the die shoulder by the sheet thickness. Die shoulders (cutting edges) that were not intentionally rounded are marked "<0.01" in this column.

[0163]

[0164] As shown in Table 1, in Examples a1 to a19, the remaining length L of the plating component relative to the thickness t1 of the cut end was 0.70 or more, and the size of the sagging Z appearing in the thickness direction was less than 0.10 times the thickness t1 of the cut end of the processed product. The fracture surface length W1 of the cut end was 1.0 mm or less in all cases, and Examples a1 to a19 exhibited good corrosion resistance of 60 days until red rust appeared. In Examples a1 to a13, the size of the sagging X appearing in the planar direction was less than 0.30 times the thickness t1 of the cut end of the processed product. Examples a1 to a16, in which the fracture surface length W1 of the cut end was 0.5 mm or less, exhibited good corrosion resistance of 90 days or more until red rust appeared.

[0165] In Examples a1 to a14, the remaining length L of the plating component relative to the plate thickness t1 of the cut end of the processed product was 0.80 times or more, and the fracture surface length (W1) was 0.5 mm or less. In Example a15, after finish punching, a coining process was performed to form an R-shaped coining surface with a crushed edge length (coining surface width) of 0.6 mm. In Example a16, after finish punching, a coining process was performed to form a C-shaped coining surface with a crushed edge length (coining surface width) of 1.0 mm and a chamfered angle of 45°. The fracture surface length (W2) after coining was smaller than the fracture surface length W1 of the other Examples. The diameter D of the cutting die ３１ and the diameter of the die for finishing cutting D ３２ Absolute value of the difference |D ３２ -D ３１ In Examples a1 to a17, the diameter | was set to 0.05 mm, and in Example a18, the diameter | was set to zero (D ３１ and diameter D ３２ In Example a19, the step height was 1.00 mm, and in Example a20, the step height was 0.5 mm or less.

[0166] Based on the above characteristics, it was confirmed from the appearance that the cut end portions of Examples a1 to a14, a18, and a19 have sagging, a shear surface, and a fracture surface in the thickness direction, and that the cut end portions of Examples a15 and a16 have sagging, a shear surface, a fracture surface, and a coining surface in the thickness direction, in that order.

[0167] In contrast, in Comparative Examples a1 to a5, a8, a10 to a13, and a16, the remaining length L of the plating layer component relative to the sheet thickness t1 of the cut end of the processed product was less than 0.70 times, so the number of days until red rust appeared at the cut end was less than 60 days, and the corrosion resistance was inferior to that of the Examples. Comparative Example a9 employed a large negative clearance in the half-cutting process, but the load exceeded the limit during the half-blanking process using a 750 kN mechanical press, causing the press to stop. Comparative Examples a14 and a15 both showed good corrosion resistance until red rust appeared at the cut end for more than 90 days, but large burrs of 0.2 mm or more appeared at the cut end.

[0168] Comparative Example a6 showed good corrosion resistance, with the number of days until red rust appeared on the cut end being 90 days or more, but the size of the sagging Z that appeared in the plate thickness direction was 0.10 times or more the plate thickness of the flange material, and the size of the sagging X that appeared in the planar direction was 0.30 times or more the plate thickness of the processed product, so that the flange dimensions had to be increased by that amount when fastened with screws. Comparative Example a7 was a case in which the clearance between the die and the punch in the half-cutting step was zero, and the plated steel sheet completely broke in the half-cutting step.

[0169] (Example b. When the cutting edges of the die and punch used in the semi-cutting step are rounded) Next, the shoulders (i.e., cutting edges) of the die and punch used in the semi-cutting step were rounded with a predetermined radius of curvature, and processed product samples were prepared by the methods shown in Figures 5 and 11. The plated steel sheets had a thickness of 1.4 to 4.5 mm and a coating weight of 90 g / m ２ (one side) or 190 g / m ２ A Zn-6%Al-3%Mg (by mass) alloy-plated steel sheet (one side) was used. Semi-cutting was performed using a round die with an inner diameter of 85.00 mm and a punch whose diameter was changed depending on the clearance between the die and the punch, with the plated steel sheet held by a sheet holder. Finish-cutting was performed using an R-shaped die with a shoulder (i.e., cutting edge) having a predetermined radius of curvature and a punch whose diameter was changed depending on the clearance between the die and the punch, with the plated steel sheet held by a sheet holder.

[0170] For each sample, flatness evaluation, burr evaluation, and step evaluation were carried out in the same manner as in Example a above, and the number of days until red rust occurred in an atmospheric exposure test was investigated. The results of Example b are shown in Table 2.

[0171]

[0172] As shown in Table 2, in Examples b1 to b19, the remaining length L of the plating component relative to the thickness t1 of the cut end of the processed product was 0.70 or more times, and the size of the sagging Z appearing in the thickness direction was less than 0.10 times the thickness t1 of the cut end of the processed product. The fracture surface length of each cut end was 1.0 mm or less, and Examples b1 to b19 exhibited good corrosion resistance of 60 days until red rust appeared. In Examples b1 to b13 and b15 to b19, the size of the sagging X appearing in the planar direction was less than 0.30 times the thickness t1 of the cut end of the processed product. In Examples b1 to b14, b16, and b17, the remaining length L of the plating component relative to the thickness t1 of the cut end of the processed product was 0.80 or more times, and the fracture surface length (W1) was 0.5 mm or less, exhibiting good corrosion resistance of 90 days or more until red rust appeared. In Example b16, after finish punching, a coining process was performed to form an R-shaped coining surface with a crushed edge length (coining surface width) of 0.6 mm. In Example b17, after finish punching, a coining process was performed to form a C-shaped coining surface with a crushed edge length (coining surface width) of 1.0 mm and a chamfered angle of 45°. The fracture surface length (W2) after coining was smaller than in the other Examples. The diameter D of the die for half-cutting ３１ and the diameter of the die for finishing cutting D ３２ Absolute value of the difference |D ３２ -D ３１ In Examples b1 to b17, the diameter | was set to 0.05 mm, and in Example b18, the diameter | was set to zero (D ３１ and diameter D ３２ In Example b19, the step height was 1.00 mm, and in both cases the step height on the end face was 0.5 mm or less.

[0173] Based on the above-mentioned characteristics, it was confirmed from the appearance that the cut end portions of Examples b1 to b15, b18, and b19 have sagging, a shear surface, and a fracture surface in the thickness direction, in that order, and that the cut end portions of Examples b16 and b17 have sagging, a shear surface, a fracture surface, and a coining surface in the thickness direction, in that order.

[0174] In contrast, in Comparative Examples b1, b2, b4, b6 to b8, b11, and b13, the remaining length L of the coating layer components relative to the plate thickness t1 of the cut end of the processed product was less than 0.70 times, so the number of days until red rust appeared at the cut end was less than 60 days, resulting in inferior corrosion resistance compared to the Examples. Furthermore, in Comparative Examples b1 and b4, the size of the sagging Z appearing in the plate thickness direction was 0.10 times the plate thickness t1 of the cut end of the processed product, so sufficient flatness was not achieved. Comparative Example b5 employed a large negative clearance in the half-cutting process, but the load exceeded the limit during the half-blanking process using a 750 kN mechanical press, causing the press to stop. Comparative Examples b9 and b10 both showed good corrosion resistance until red rust appeared at the cut end for more than 90 days, but large burrs of 0.2 mm or more appeared at the cut end. In Comparative Examples b3 and b12, the negative clearance between the die and the punch in the semi-cutting step was insufficient, and therefore the plated steel sheet was completely broken in the semi-cutting step.

[0175] From the above, it was confirmed that in a cutting process that involves a semi-cutting step followed by a finish-cutting step, by making the remaining length L of the plating component 0.70 times or more the thickness t1 of the cut end of the processed product, a cut end with good corrosion resistance can be obtained. Furthermore, it was confirmed that by making the sag Z appearing in the thickness direction of the cut end less than 0.10 times the thickness t1 of the cut end of the processed product, a product can be obtained without unnecessarily increasing the flange dimensions when fastened with screws.

[0176] Although the preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings, the present invention is not limited to these examples. It is clear that a person skilled in the art to which the present invention pertains can conceive of various modifications and alterations within the scope of the technical ideas set forth in the claims, and it is understood that these also naturally fall within the technical scope of the present invention.

[0177] DESCRIPTION OF SYMBOLS 1 Workpiece 2 First element 6 Second element 7 Pad 8 Coining block 9 Element 10 Body 11 Protrusion 12 Flange 13 Cut end 13a Top surface 13b Sagging 13c Shear surface 13d Fracture surface 13e Burr 13f Plating layer 13g Corner 13h Coining surface 13j Extension surface 13k Bottom surface 20 Flange element 20a Removed portion 31 First die 32 Second die 41 First punch 42 Second punch 61 Outer die 63 Inner die 65 Punch 70 Vertical wall surface 71 Bottom wall surface 72 Pressing surface 101 Side wall 103 Top wall 121 Screw hole 123 Screw 900, 910A, 910B, 910C: Flat washer 911, 931: Tooth portion 940: Plate

Claims

1. A processed product made of plated steel sheet having a plating layer on its surface, the cut end having a sagging, a sheared surface and a fractured surface, or a sagging and a sheared surface, in the thickness direction of the cut end, a ratio L / t1 of a remaining plating component length L where the sheared surface is covered by the plating layer on the surface to a thickness t1 of the cut end of the processed product is 0.70 or more, and a length Z of the sagging in the thickness direction of the cut end is 0 and less than 0.10 times the thickness t1 of the cut end of the processed product.

2. The processed product according to claim 1, wherein the length W1 of the fracture surface in the thickness direction of the cut end is greater than 0 mm and less than 1.0 mm.

3. The processed product according to claim 2, wherein the length W1 of the fracture surface in the thickness direction of the cut end is 0.5 mm or less.

4. A processed product according to any one of claims 1 to 3, wherein the length X of the sagging in a planar direction perpendicular to the thickness direction of the cut end portion is 0 times and less than 0.30 times the thickness t1 of the cut end portion of the processed product.

5. The processed product according to any one of claims 1 to 4, wherein the length of the burr on the cut end is less than 0.2 mm.

6. The processed product according to any one of claims 1 to 5, wherein the cut end portion has, in a thickness direction of the cut end portion, the sagging, the shear surface, the fracture surface, and a coining surface, or the sagging, the shear surface, and a coining surface, and a length W2 of the fracture surface between the shear surface and the coining surface in the thickness direction of the cut end portion is more than 0 mm and 0.5 mm or less.

7. A method for manufacturing a processed product having a cut end, using a plated steel sheet having a plating layer on its surface as a raw material, comprising: a half-cutting step of half-cutting a cut portion of a first body formed from the raw material in a thickness direction using a first die and a first punch with a clearance between the first die and the first punch set to a negative clearance; and a finish-cutting step of finish-cutting the half-cut first body in the same direction as the half-cutting using a second die and a second punch to obtain a processed product having a cut end along the thickness direction, wherein when the cut end is formed on the outer periphery of the processed product, the inner diameter D of the second die is set to a negative clearance. ３２ is the inner diameter D of the first die ３１ In the case where the cut end is formed on the inner side of the processed product, the outer diameter d ３２ is the outer diameter d of the first die ３１ The thickness of the cut portion of the first body is t1, the remaining thickness of the cut portion after the semi-cutting step is t2, and in the semi-cutting step, a clearance C between the first die and the first punch is ３１－４１ satisfies the following formula (a1), a radius of curvature R1 of the cutting edge of the first die satisfies the following formula (a2-1), a pressing amount D of the first die or the first punch against the cut portion of the first body satisfies the following formula (a3), and a distance C between the first die and the first punch at the bottom dead point satisfies the following formula (a4). Ｐ－Ｄ satisfies the following formula (a4), and in the finish cutting step, the clearance C between the second die and the second punch ３２－４２ satisfies the following formula (a5), and the radius of curvature R2 of the cutting edge of the second die satisfies the following formula (a6). ３１－４１ ≦-0.01 ... (a1) 0.10 x t1 ≦ R1 ≦ 0.50 x t1 ... (a2) D≧0.70 x t1 ... (a3) ​​C Ｐ－Ｄ ≧0.20 ... (a4) 0.01≦C ３２－４２ ≦0.2×t2 (a5) 0.25≦R2≦1.50×t2 (a6) Here, C ３１－４１ , C Ｐ－Ｄ , C ３２－４２ and R2 is in mm.

8. A method for manufacturing a processed product having a cut end using a plated steel sheet having a plating layer on its surface as a raw material, the method comprising: a half-cutting step of half-cutting a cut portion of a first body formed from the raw material in a sheet thickness direction using a first die and a first punch with a clearance between the first die and a first punch set to a negative clearance; and a finish-cutting step of finish-cutting the half-cut first body in the same direction as the half-cutting using a second die and a second punch to obtain a processed product having a cut end whose cut surface is along the sheet thickness direction, wherein when the cut end is formed on the outer periphery of the processed product, the inner diameter D of the second die is set to a value smaller than the inner diameter D of the second die. ３２ is the inner diameter D of the first die ３１ In the case where the cut end is formed on the inner side of the processed product, the outer diameter d ３２ is the outer diameter d of the first die ３１ The thickness of the cut portion of the first body is t1, the remaining thickness of the cut portion after the semi-cutting step is t2, and in the semi-cutting step, a clearance C between the first die and the first punch is ３１－４１ satisfies the following formula (b1), a radius of curvature R11 of the cutting edge of the first die satisfies the following formula (b2-1), a radius of curvature R12 of the cutting edge of the first punch satisfies the following formula (b2-2), a pressing amount D of the first die or the first punch against a cut portion of the first blank satisfies the following formula (b3), and a distance C between the first die and the first punch at the bottom dead center satisfies the following formula (b4). Ｐ－Ｄ satisfies the following formula (b4), and in the finish cutting step, the clearance C between the second die and the second punch ３２－４２ satisfies the following formula (b5), and the radius of curvature R2 of the cutting edge of the second die satisfies the following formula (b6). ３１－４１ ≦-0.10×t1 (b1) 0.10×t1≦R11≦0.65×t1 (b2-1) 0.10×t1≦R12≦0.65×t1 (b2-2) D≧0.70×t1 (b3) C Ｐ－Ｄ ≧0.20 ... (b4) 0.01≦C ３２－４２ ≦0.2×t2 (b5) 0.25≦R2≦1.50×t2 (b6) Here, C ３１－４１ , C Ｐ－Ｄ , C ３２－４２ and R2 is in mm.

9. A method for manufacturing a processed product according to claim 7 or 8, further comprising a coining step of using the processed product obtained in the finish cutting step as a second body, and pressing corners of the cut end portion of the second body against a pad to obtain a processed product having a coining surface formed on the corners.

10. When the cut end is formed on the outer periphery of the processed product, the inner diameter D of the first die ３１ and the inner diameter D of the second die ３２ Absolute value of the difference between |D ３２ -D ３１ | is 1.00 mm or less, and when a cut end portion is formed on the inner side of the processed product, the outer diameter d ３１ and the outer diameter d of the second die ３２ Absolute value of the difference between |d ３２ -d ３１ The method for manufacturing a processed product according to any one of claims 7 to 9, wherein | is 1.00 mm or less.

11. The method for manufacturing a processed product according to any one of claims 7 to 10, further comprising a preparation step of forming a first body from a flat plated steel sheet prior to the semi-cutting step.