Method for manufacturing metal processed article, and metal processed article

Abstract

Provided is a method for manufacturing a metal processed article, whereby it is possible to reduce the height of a protrusion originating from a protruding part remaining after a coining step. A method for manufacturing a metal processed article according to the present invention comprises a half-cutting step, a finish cutting step, and a coining step. With respect to the half-cutting step, a clearance C31-41 (mm) between a first die and a first punch is set to a negative clearance, a cutting edge of the first die and a cutting edge of the first punch are formed in rounded shapes having predetermined radii of curvature RD1 and RP1 (mm), a protruding part having a height h (mm) is formed on a half-cutting part, and the height h (mm) corresponds to the separation distance along the pressing direction of the first die between the position on the cutting edge of the first punch on an extension line of the side surface of the first die and an extension line of the upper surface of the first punch in contact with the lower surface of a first element body. With respect to the coining step, the pad has a vertical wall surface, a bottom wall surface, and a pressing surface, and when the area of the area of the region surrounded by the extension surface of the vertical wall surface, the extension surface of the bottom wall surface, and the pressing surface is defined as the coining area Ar, the coining area Ar is set so as to satisfy the following expression: h ≤ -1.09Ar + 1.04.

Description

Manufacturing method of metal processed product and metal processed product

[0001] The present invention relates to a method for manufacturing a metal processed product using a plated metal sheet having a plating layer on its surface as a raw material, having a cut edge along the thickness direction of the raw material, and having a coining surface formed on the corner of the cut edge, and to the metal processed product.

[0002] In recent years, metal processed products made from plated metal 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 metal sheets as the material, it is possible to omit the plating process after forming the metal processed product, thereby reducing manufacturing costs. Furthermore, by omitting the plating process after forming, it is possible to avoid deterioration of the dimensional accuracy of the part due to the plating process after forming. Omitting the plating process after forming is particularly considered for parts that require high dimensional accuracy, such as motor cases.

[0003] If plating after forming is omitted, areas of the metal sheet base material will be exposed at the cut edges of the metal processed product. Depending on the environment in which the processed product is placed, red rust may form in the exposed areas of the metal sheet base material. This red rust will deteriorate the appearance of the processed product.

[0004] Patent Document 1 below proposes a rust-prevention method for cut edges, in which a first step involves half-cutting (half-blanking) with a negative clearance using a punch and die with rounded cutting edges, and a second step involves only rounding the die (or punch) and performing a finish cut with a positive clearance, thereby causing the surface plating layer to wrap around the end face of the cut edge. Patent Document 1 also discloses coining following the finish cutting step. In coining, a smoothed surface is formed on the corners of the cut edge on the fractured surface side of the finished cut product. The smoothed surface is less susceptible to red rust than the newly formed, rough fracture surface. Furthermore, coining can eliminate burrs generated during finish cutting. Coining is performed by sandwiching the cut edge between a pad with a pressing surface and a coining block, and compressing the corners on the fractured surface side with the pressing surface.

[0005] International Publication No. 2022 / 039168

[0006] The inventors have been studying ways to increase the corrosion prevention effect by increasing the amount of plating layer that wraps around the end surface of the cut end. In order to increase the amount of plating layer that wraps around, the radius of curvature of the cutting edges of the punch and die used for semi-cutting was increased, and the amount of depression of the die was also increased. However, a new problem arose: protrusions called horns were generated on the lower part of the cut end during the finish cutting process, and large protrusions resulting from the horns were formed on the underside of the cut end after the coining process. The protrusions are formed when the horns are crushed during the coining process. The above-mentioned Patent Document 1 does not take these issues into consideration.

[0007] For example, a drawn product such as a motor case may be provided with a flange for fixing the product to another device. The end of the flange is formed by cutting. If a large protrusion is formed on the underside of the flange, a space will be created between the flange and the other device when fixing the flange to the other device, causing rattle and possibly deteriorating product performance.

[0008] The present invention has been made to solve the above-mentioned problems, and one of its objects is to provide a method for manufacturing a metal processed product that can reduce the height of protrusions resulting from horns remaining after the coining process. Another object of the present invention is to provide a metal processed product that can reduce rattling caused by the protrusions.

[0009] In one embodiment, a method for manufacturing a metal processed product according to the present invention is a method for manufacturing a metal processed product using a plated metal sheet having a plating layer on its surface as a raw material, having a cut edge along the thickness direction of the raw material and having a coining surface formed at a corner of the cut edge, the method comprising: a half-cutting step using a first die and a first punch to half-cut a first element formed from the raw material in the thickness direction to form a half-cut portion; a finish-cutting step using a second die and a second punch to finish-cut the half-cut portion in the same direction as the half-cutting to obtain a second element having a cut edge; and a coining step to press a corner of the cut edge of the second element against a pad to obtain a metal processed product having a coining surface formed at the corner, wherein with respect to the half-cutting step: 31-41 (mm) is set to a negative clearance, and the cutting edge of the first die and the cutting edge of the first punch have a predetermined radius of curvature R D1 , R P1 (mm), and the half-cut portion has a horn portion having a height h (mm), and the height h (mm) corresponds to the distance along the pushing direction of the first die between the position on the cutting edge of the first punch on an extension line of the side surface of the first die and an extension line of the top surface of the first punch that contacts the bottom surface of the first base body, and is expressed by the following formula: Regarding the coining process, the pad has a vertical wall surface, a bottom wall surface, and a flat or curved pressing surface that connects the vertical wall surface and the bottom wall surface at the corner where the vertical wall surface and the bottom wall surface meet, and against which the corner portion of the cut end is pressed, and when the pad is viewed in a cross section along the pressing direction of the corner portion, the area of ​​the region surrounded by the extended surface of the vertical wall surface, the extended surface of the bottom wall surface, and the pressing surface is defined as the coining area Ar (mm 2 ), the coining area Ar (mm 2 ) is set to satisfy the following equation: h≦−1.09Ar+1.04.

[0010] In one embodiment, a metal processed product according to the present invention is a metal processed product made from a plated metal sheet having a plating layer on its surface, and having a cut edge along the sheet thickness direction of the material, wherein the cut edge has a sag, a shear surface, and a coining surface in that order in the sheet thickness direction of the cut edge from the upper surface side to the lower surface side, the shear surface has, in the sheet thickness direction, a first shear surface that is continuous with the sag and a second shear surface that is continuous with the first shear surface, the inclination angle θd1 of the first shear surface with respect to the sheet thickness direction and the inclination angle θd2 of the second shear surface with respect to the sheet thickness direction satisfy θd1 > θd2, the shear surface is covered with a plating layer on the surface and the remaining length L1 (mm) of the plating component and the cut surface are different from each other. The ratio L1 / t1 of the length Z (mm) of the sag in the thickness direction from the top surface of the cut end toward the bottom surface of the cut end to the thickness t1 (mm) of the cut end is 0.80 or more, the ratio Z / t1 of the length Z (mm) of the sag in the thickness direction from the top surface of the cut end toward the bottom surface of the cut end to the thickness t1 (mm) of the cut end is -0.10 or more and less than 0.10, a protrusion having a height h0 of more than 0 mm and 0.20 mm or less is provided at the bottom of the coining surface, the surface plating layer wraps around from the bottom surface to the end surface of the cut end, and the height Lc (mm) of the upper end of the plating layer wraps around from the bottom surface in the thickness direction from the bottom surface is 0.10 or more times the radius of curvature R0 (mm) of the coining surface or the tapered surface height C0 (mm).

[0011] According to one embodiment of the method for manufacturing a metal processed product of the present invention, the height of the protrusions resulting from the horns remaining after the coining process can be reduced. Also, according to one embodiment of the metal processed product of the present invention, rattle caused by the protrusions can be reduced.

[0012] 10 is a perspective view showing an example of a metal processed product manufactured by a method for manufacturing a metal processed product according to an embodiment of the present invention. FIG. 1 is an explanatory view showing a first aspect of a cut end portion in region A of FIG. 1. FIG. 1 is an explanatory view showing a second aspect of a cut end portion in region A of FIG. 1. FIG. 1 is an explanatory view showing a third aspect of a cut end portion in region A of FIG. 1. FIG. 10 is an explanatory view showing a fourth aspect of a cut end portion in region A of FIG. 1. FIG. 2 is a detailed view of a cross section of the cut end portion of FIG. 2. FIG. 6 is a detailed view of region B of FIG. 6. FIG. 7 is a graph showing an example of a relationship between sag Z and sag X. FIG. 11 is an explanatory view showing a method for manufacturing a metal processed product according to an embodiment of the present invention. FIG. 12 is an explanatory view showing a first die and a first punch used in the half-cutting step of FIG. 9. FIG. 13 is an explanatory view showing an enlarged half-cut portion of FIG. 10. FIG. 14 is an explanatory view showing a change in the horn portion due to a change in the radius of curvature of the cutting edge of the first punch and a change in clearance of the cutting edge. FIG. 14 is an explanatory view showing a second die and a second punch used in the finish-cutting step of FIG. 9. FIG. 15 is an explanatory view showing a pad and a coining block used in the coining step of FIG. 9. FIG. 16 is a photograph showing a cut end portion of a metal processed product after the coining step. FIG. 17 is a perspective view showing an example of a processed product. 20 is a schematic diagram showing a state in which an element body has been punched using the cutting die of FIG. 20; FIG. 21 is a schematic diagram showing an example of a coining die for producing the processed product of FIG. 16; FIG. 22 is a schematic diagram showing another example of a processed product; FIG. 23 is a graph showing the relationship between the height of the horn portion after half-cutting (before finish cutting) and the coining area of ​​the pad used in the coining process in the examples;

[0013] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present invention is not limited to each embodiment, and the components can be modified and embodied without departing from the spirit of the present invention. Furthermore, various inventions can be formed by appropriately combining multiple components disclosed in each embodiment. For example, some components may be omitted from all the components shown in the embodiments. Furthermore, components of different embodiments may be appropriately combined.

[0014] <Regarding the Metal Worked Product> Figure 1 is a perspective view showing an example of a metal worked product 1 manufactured by a method for manufacturing a metal worked product 1 according to an embodiment of the present invention. The metal worked product 1 shown in Figure 1 is a motor case made of a plated metal sheet having a plating layer on its surface. The motor case shown in Figure 1 can be formed by applying a forming process such as drawing to a flat plated metal sheet.

[0015] As shown in FIG. 1 , the metal processed product 1 according to this embodiment has a body portion 10 , a protrusion portion 11 and a flange portion 12 .

[0016] 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 metal processed product 1. The cross-sectional shape of the body 10 of the metal processed product 1 shown in FIG. 1 in the XY plane (the transverse cross-sectional shape of the body 10) is a perfect circle, but the present invention is not limited to this example. The cross-sectional shape of the body 10 in the XY plane may also be other shapes, such as an ellipse or a polygon.

[0017] 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.

[0018] The flange portion 12 is a plate portion that extends from an end portion of the body portion 10 (i.e., the other end of the side wall 101) toward the outside in the radial direction (X and Y directions) of the body portion 10. The shape of the flange portion 12 is arbitrary. The flange portion 12 in 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 that are spaced apart from one another in the circumferential direction of the body portion 10. Screws 123 are inserted into the screw holes 121. The metal 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.

[0019] The flange portion 12 according to this embodiment is formed by cutting a flange portion blank (first flange portion blank 20 in FIG. 9 ) having an outer diameter larger than the outer diameter of the flange portion 12 that will ultimately be formed on the metal processed product 1. That is, the metal processed product 1 according to this embodiment has a cut end 13 on the outer periphery of the flange portion 12. The cut end 13 extends along the thickness direction of the plated metal sheet that is the raw material.

[0020] 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.

[0021] The base material of the plated metal sheet may be any metal, such as steel, copper, a copper alloy, aluminum, or an aluminum alloy. Typically, the plated metal sheet is a plated steel sheet. The manufacturing method of the metal processed product 1 according to the embodiment of the present invention, which will be described later, is particularly suitable for the case where the base material is steel. This is because steel is prone to rust, and imparting corrosion resistance is a significant advantage.

[0022] The plated steel sheet is, for example, a Zn-based plated steel sheet, an Al-based plated steel sheet, or the like. The plated steel sheet is more preferably a Zn-based plated steel sheet. The Zn-based plating has a sacrificial corrosion protection effect on the base steel sheet. Therefore, corrosion from the exposed portion of the base material on the end surface of the cut end portion 13 can be suppressed, and the corrosion resistance of the manufactured metal member can be further improved. Examples of the Zn-based plating include hot-dip Zn galvannealing, alloyed hot-dip galvannealing, Zn-Ni-based plating, Zn-Al-based plating, Zn-Mg-based plating, and Zn-Al-Mg-based plating.

[0023] The thickness of the plated metal sheet (the thickness of the base metal sheet plus the thickness of the plating layer) is not particularly limited and 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.

[0024] When the plating weight of the plated metal sheet is above a certain level, the plating metal is likely to wrap around the end surface of the cut end 13. By allowing the plating metal to wrap around, the corrosion resistance of the end surface of the cut end 13 can be improved. The preferable lower limit of the plating weight is 30 g / m 2 A more preferable lower limit of the plating coating weight is 45 g / m 2 The preferred upper limit of the plating coating weight is 450 g / m 2 A more preferable upper limit of the plating coating weight is 190 g / m 2 is.

[0025] <Regarding the Cut End of the Workpiece> Next, the cut end 13 of the metal workpiece 1 will be described using Figures 2 to 8. Figures 2 to 5 are explanatory diagrams showing first to fourth aspects of the cut end 13 in region A of Figure 1. The left side of Figures 2 to 5 is a cross-sectional view of the cut end 13 in the ZX plane of Figure 1, and the right side of Figures 2 to 5 is a front view of the cut end 13 as viewed along the X direction of Figure 1. Figure 6 is a detailed cross-sectional view of the cut end 13 in Figure 2, and Figure 7 is a detailed view of region B in Figure 6. Figure 8 is a graph showing an example of the relationship between sag Z and sag X. Note that in Figures 2 to 6, the plate thickness direction T of the cut end 13 is assumed to be the same as the central axis direction (Z direction) of the metal workpiece 1 shown in Figure 1. Also, in Figures 2 to 5, the plating layers 13f and 13k shown in Figure 6 are omitted.

[0026] As particularly shown in FIG. 2, the cut end portion 13 has a sag 13c, a shear surface 13d, and a coining surface 13e in this order in the thickness direction T of the cut end portion 13 from the upper surface 13a side to the lower surface 13b side.

[0027] The upper surface 13a is the surface (pressed surface) onto which the cutting edges of the cutting dies (the first die 31 and the second die 32 in FIGS. 10 and 13) are pressed when cutting the flange portion blank, and the lower surface 13b is the surface from which the cutting edges of the cutting dies emerge when cutting the flange portion blank.

[0028] The sag 13c is a portion of the flange portion element surface that is deformed due to a tensile force acting on the surface of the flange portion element (the plated metal sheet as the raw material) when the cutting edge of the cutting die is pressed into the flange portion element. The sag 13c typically appears as a smooth surface with a curvature at the cut end 13. In this specification, the dimension of the sag 13c in the thickness direction T of the cut end 13 is referred to as "sag Z," and the dimension of the sag 13c in a planar direction perpendicular to the thickness direction T is referred to as "sag X."

[0029] The sheared surface 13d is a surface where the flange portion element is sheared by the cutting edge of the cutting die. The sheared surface 13d is adjacent to the sag 13c in the thickness direction T of the cut end 13. The sheared surface 13d typically appears as a smooth surface at the cut end 13. The sheared surface 13d may have a metallic luster because it is created by rubbing against the side surface of the cutting die when a compressive (pressure) force is applied after the cutting die comes into contact with the workpiece and bites into the workpiece. Fine streak-like sliding scratches may be seen on the sheared surface 13d in the thickness direction T.

[0030] The coining surface 13e is a surface formed by pressing or compressing a corner portion 13m (see FIG. 9 ) on the lower surface 13b side of the cut end portion 13 by a coining process described below. In this embodiment, the coining surface 13e is a tapered surface (a flat chamfered surface). The inclination angle θ of the extending direction of the coining surface 13e relative to the extending direction of the lower surface 13b may be, for example, 45° or 60°. However, as shown in FIG. 5 , the coining surface 13e may be another pressed or compressed surface, such as an R-surface (a curved chamfered surface). The coining surface 13e typically appears on the cut end portion 13 as a smooth surface in which the irregularities of the fracture surface have been smoothed. The cut end portion 13 does not need to have a burr. This is because even if burrs are generated during the cutting process, the burrs are smoothed by the coining process.

[0031] As a method for identifying the sagging 13c, shear surface 13d, and coining surface 13e in the cut end portion 13 (a method for measuring the length of each), for example, there is a method for observing and measuring the shape profile of the cut end portion 13 from the appearance using a microscope or a contrast tracer based on the above characteristics.

[0032] In this embodiment, the shear surface 13d has a first shear surface 13d1 that is continuous with the sag 13c and a second shear surface 13d2 that is continuous with the first shear surface 13d1 in the thickness direction T. The lower end of the second shear surface 13d2 may be continuous with the coining surface 13e. The first shear surface 13d1 and the second shear surface 13d2 have different inclination angles θd1 and θd2 relative to the thickness direction T. The inclination angle θd1 of the first shear surface 13d1 relative to the thickness direction T and the inclination angle θd2 of the second shear surface 13d2 relative to the thickness direction T satisfy the relationship θd1 > θd2. In other words, the first shear surface 13d1 is inclined more than the second shear surface 13d2 relative to the thickness direction T. When the cut end portion 13 is viewed from the front, as shown on the right side of FIG. 2 , a boundary line may be visible between the first shear surface 13d1 and the second shear surface 13d2. In the direction perpendicular to the plate thickness direction T (X-axis direction in the drawing), the second shear surface 13d2 may protrude outward more than the first shear surface 13d1.

[0033] In the metal processed product 1 of this embodiment, as particularly shown in Figure 6, a plating layer 13f extends from the upper surface 13a of the cut end portion 13 to the sheared surface 13d. When the cutting die's cutting edge bites into the flange body, the plating layer 13f is stretched by the cutting die and extends to the sheared surface 13d. This extension of the plating layer 13f coats at least a portion of the sheared surface 13d with the plating layer 13f, thereby suppressing the occurrence of red rust in the portion coated with the plating layer 13f. Furthermore, when the plating layer 13f is a Zn-based plating layer, the sacrificial anticorrosion effect of the Zn-based plating layer also suppresses the occurrence of red rust near the portion coated with the plating layer 13f.

[0034] In the metal processed product 1 of this embodiment, the length L1 of the plating layer 13f, which extends from the upper surface 13a of the cut end 13 to the sag 13c and covers at least a portion of the sheared surface 13d, is 0.80 times or more the thickness t1 of the cut end 13 of the metal processed product 1. That is, the ratio L1 / t1 of the remaining plating component length L1 where the sheared surface 13d is covered by the plating layer 13f on the surface of the plated metal sheet to the thickness t1 of the cut end 13 is 0.80 or more. The length L1 of the plating layer 13f or the remaining plating component length L1 can also be considered as 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 cut end 13. The thickness t1 of the cut end 13 can also be considered as the distance between the upper surface 13a and the lower surface 13b of the cut end 13 in the thickness direction T of the cut end 13. More specifically, the thickness t1 of the cut end 13 may be the distance between the upper surface 13a and the lower surface 13b at a position not affected by the sag 13c and the coining surface 13e (a position sufficiently distant from the outer edge of the cut end 13). The thickness t1 of the cut end 13 is equal to the thickness of the flange portion 12 shown in FIG.

[0035] Here, during the coining process to form the coining surface 13e, a pressing or compressive force acts on the cut end 13 from the lower surface 13b side toward the upper surface 13a side of the cut end 13, which may push up the sagging 13c, shear surface 13d, and fracture surface within the cut end 13. Depending on the amount of coining, the sagging 13c of the cut end 13 may take the form shown in Figure 3 or Figure 4 rather than the form shown in Figure 2.

[0036] FIG. 3 shows an embodiment in which the boundary position 13g between the sag 13c and the sheared surface 13d is raised to the same height as the upper surface 13a by the coining process. FIG. 4 shows an embodiment in which the boundary position 13g between the sag 13c and the sheared surface 13d is raised to a position higher than the upper surface 13a by the coining process. In both of the embodiments shown in FIGS. 3 and 4, a deformed surface corresponding to the sag 13c remains following the smooth upper surface 13a of the cut end 13. The deformed surface may bulge upward from the smooth upper surface 13a. In this specification, such a deformed surface is also referred to as the sag 13c. In particular, the sag 13c shown in FIG. 4 may also be referred to as an upwardly convex sag 13c.

[0037] In the case of an upwardly convex sag 13c as shown in Figure 4, i.e., in the case where the boundary position 13g between the sag 13c and the shear surface 13d is pushed up to a position higher than the upper surface 13a, if the boundary position 13g is pushed up too much, excessive deformation of the cut end 13 may cause problems such as loss of stability of the screw 123 (see Figure 1).

[0038] In the metal processed product 1 of this embodiment, the ratio Z / t1 of the length Z of the sagging 13c in the thickness direction T, which extends from the upper surface 13a of the cut end 13 toward the lower surface 13b of the cut end 13, to the thickness t1 of the cut end 13 is set to be greater than or equal to -0.10 and less than 0.10. Having the ratio Z / t1 of -0.10 or greater prevents the upwardly convex sagging 13c from excessively protruding from the upper surface 13a, thereby reducing the risk of defects due to excessive deformation of the cut end 13. Having the ratio Z / t1 of less than 0.10 prevents the sagging X (the dimension of the sagging 13c in a planar direction perpendicular to the thickness direction T) from becoming too large. It is more preferable that the ratio Z / t1 be greater than or equal to 0 and less than 0.10. This allows for a more desirable shape for the cut end 13. The ratio Z / t1 may be greater than or equal to -0.10 and less than 0.

[0039] It is known that sag Z and sag X are correlated with each other. FIG. 8 shows an example of the relationship between sag Z and sag X of the cut end 13 when punching is performed in a single process. FIG. 8 shows the relationship between sag Z and sag X of the cut end 13 of a product when punching is performed by imparting a radius of curvature of 0.01 to 0.30 in relation to 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. 8, 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. This correlation is before the coining process, but it also has an effect after the coining process.

[0040] When measuring the sag Z, the height position of the upper surface 13a of the cut end portion 13 is set as the reference position (0 point), and the length from the upper surface 13a to a position below the upper surface 13a is defined as a positive length, and the length from the upper surface 13a to a position above the upper surface 13a is defined as a negative length. The reference position is the height position of the upper surface 13a of the cut end portion 13 at a position not affected by the sag 13c and coining surface 13e (a position sufficiently distant from the outer edge of the cut end portion 13).

[0041] For example, height measurement points on the surface of the cut end 13 can be scanned from a position not affected by the sag 13c and the coining surface 13e toward the outer edge of the cut end 13. When the boundary position 13g is lower than the upper surface 13a as in the first embodiment shown in Figure 2, the height position of the surface of the cut end 13 gradually decreases toward the boundary position 13g, and the height position of the surface of the cut end 13 takes a discontinuous value when the boundary position 13g is exceeded. When the boundary position 13g is at the same height as the upper surface 13a as in the second embodiment shown in Figure 3, the height position of the surface of the cut end 13 slightly fluctuates toward the boundary position 13g, and the height position of the surface of the cut end 13 takes a discontinuous value when the boundary position 13g is exceeded. When the boundary position 13g is higher than the upper surface 13a as in the third embodiment shown in Figure 4, the height position of the surface of the cut end 13 gradually increases toward the boundary position 13g, and the height position of the surface of the cut end 13 takes a discontinuous value when the boundary position 13g is exceeded. The length Z of the sag 13c can be the length in the thickness direction T between the height position immediately before the height position of the surface of the cut end 13 becomes discontinuous and the reference position. The height position immediately before the height position of the surface of the cut end 13 becomes discontinuous can be the height position of the boundary position 13g. One method for measuring the length Z of the sag 13c is to observe and measure the shape profile of the cut end 13 using, for example, a contrast tracer.

[0042] In the metal processed product 1 of this embodiment, a protrusion 13h is provided on the lower part of the coining surface 13e. The protrusion 13h is formed by the material of the corner portion 13m (see FIG. 9) on the lower surface 13b of the cut end portion 13 escaping inward in a direction perpendicular to the plate thickness direction T (the X-axis direction in the drawing) during the coining process that forms the coining surface 13e.

[0043] The protrusion 13h has a height h0 greater than 0 mm and equal to or less than 0.20 mm. The metal processed product 1 may be used such that the lower surface 13b of the cut end 13 comes into contact with another structure. If the height h0 of the protrusion 13h is large, a space will be created between the lower surface 13b of the cut end 13 and the other structure, causing rattle. By setting the height h0 of the protrusion 13h to 0.20 mm or less, rattle caused by the protrusion 13h can be reduced. The height h0 may be the distance between the lower surface 13b of the cut end 13 and the lower end of the protrusion 13h in the plate thickness direction T of the cut end 13.

[0044] 7, protrusion 13h may be formed by crushing horns 21a (horn-shaped protrusions) created during cutting by coining, and plating layer 13k on the lower surface 13b of cut end 13 may become caught up in protrusion 13h. By reducing both the height h of horns 21a and the coining area Ar crushed by coining, the amount of plating layer 13k caught up in protrusion 13h can be kept small, and the occurrence of whisker burrs caused by the falling off of this plating layer 13k can be suppressed.

[0045] In the metal processed product 1 of this embodiment, as particularly shown in Fig. 6, a plating layer 13k on the surface of the plated metal sheet wraps around from the lower surface 13b of the cut end portion 13 to the end surface of the cut end portion 13. When the coining process is performed, the plating layer 13k on the lower surface 13b is pressed or compressed together with the portion that constitutes the coining surface 13e, and the plating layer 13k wraps around to the end surface of the cut end portion 13. This wrapping of the plating layer 13k causes at least a portion of the coining surface 13e to be covered with the plating layer 13k. The generation of red rust can be further suppressed in the portion of the coining surface 13e that is covered with the plating layer 13k.

[0046] In the metal processed product 1 of this embodiment, the height Lc of the upper end of the plating layer 13k extending from the lower surface 13b of the cut end 13 in the thickness direction T relative to the lower surface 13b of the cut end 13 is at least 0.10 times the radius of curvature R0 or the tapered surface height C0 of the coining surface 13e. Having the height Lc at least 0.10 times the radius of curvature R0 or the tapered surface height C0 more reliably suppresses the occurrence of red rust. The radius of curvature R0 is the radius of curvature of the outer surface of the coining surface 13e when the coining surface 13e is an R-surface (a curved chamfered surface) as shown in FIG. 5. The tapered surface height C0 is the length between the lower surface 13b and the upper end of the coining surface 13e in the thickness direction T when the coining surface 13e is a tapered surface (a flat chamfered surface) as shown in FIG. 2, etc. The radius of curvature R0 or the tapered surface height C0 can be measured on the cross section of the cut end 13.

[0047] <Regarding the manufacturing method of the metal processed product 1> Next, Fig. 9 is an explanatory diagram showing a manufacturing method of the metal processed product 1 according to an embodiment of the present invention. As shown in Fig. 9, the manufacturing method of the metal processed product 1 according to this embodiment includes a preparation step, a semi-cutting step, a finish cutting step, and a coining step.

[0048] 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 metal sheet. That is, the first element body 2 is made of a plated metal sheet, similar to the metal processed product 1. The first element body 2 includes a first flange portion element body 20 having an outer diameter larger than the flange portion 12 shown in FIG. 1. The first 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 metal processed product 1, except for the first flange portion element body 20. The preparation step does not necessarily involve forming a plated metal strip. An element body processed by a third party by some method may be obtained. The first flange portion element body 20 of this embodiment constitutes the flat portion to be cut, including the portion that will become the cut end portion 13.

[0049] The half-cutting process is a process of half-cutting the first element 2. In the half-cutting process, the first flange element 20 (portion to be cut) is half-cut. Half-cutting is a process of cutting the first flange element 20 to a position partway along the thickness direction of the first flange element 20. Here, the smooth surface smoothed by the die used for half-cutting (side surface 31a of first die 31 in FIG. 10 ) becomes the first shear surface 13d1. When the first flange element 20 of the first element 2 is half-cut, the removed portion 20a, which will ultimately be outside the product, is cut partway from the first flange element 20.

[0050] The finish cutting process is a process in which the first flange portion element 20 (the portion to be cut) of the first element 2 is cut to obtain the second element 3. The second element 3 is an intermediate member for manufacturing the metal processed product 1, and the metal processed product 1 can be obtained by further processing the second element 3. In the finish cutting process, the removed portion 20a of the first flange portion element 20 is cut and separated from the first flange portion element 20. The removed portion 20a is cut to form the second flange portion element 30. Here, the smooth surface smoothed by the side surface of the die used for finish cutting (side surface 32a of the second die 32 in FIG. 13 ) becomes the second shear surface 13d2. The second flange portion element 30 has a cut end 13. The cut end 13 of the second element 3 has a corner portion 13m on the lower surface 13b side. The corner portion 13m may have burrs and / or horns 21a (see FIG. 13 , etc.), which will be described later.

[0051] The coining step is a step of coining the cut end portion 13 of the second element 3 obtained in the finish cutting step to obtain the metal processed product 1. As will be described later with reference to the drawings, the coining step in this embodiment involves pressing the corner portion 13m of the cut end portion 13 of the second element 3 against a pad 7 to form a coining surface 13e on the corner portion 13m. The coining surface 13e is a crushed surface of the corner portion 13m. In the manufacturing method of the metal processed product 1 according to this embodiment, the coining surface 13e is formed on the corner portion 13m of the second flange portion element 30 of the second element 3, thereby obtaining the metal processed product 1 having the flange portion 12. The screw holes 121 of the metal processed product 1 shown in FIG. 1 may be formed in the first flange portion element 20 or the second flange portion element 30 at the stage of the first element 2 or the second element 3, or may be formed in the flange portion 12 after the coining step.

[0052] In the semi-cutting step and the finish-cutting step of the method for manufacturing the metal processed product 1 according to this embodiment, the first flange portion element 20 and the second flange portion element 30 are machined using a die and a punch. The semi-cutting step and the finish-cutting step will be described in detail below. The cutting edges of the die and the punch are sometimes referred to as "shoulders."

[0053] In the following description, for convenience, the dies used to obtain the metal product 1 will be referred to as the die on the pushing side and the punch on the receiving side. The pushing die may be positioned above or below the blanks 2 and 3. Even when moving horizontally, the pushing die is referred to as the die and the receiving die as the punch. For example, the metal product 1 shown in FIG. 2 was cut using the upper die as the pushing die. If the lower die were used as the pushing die, i.e., the lower die were used as the die, the cut end 13 of the metal product 1 would be the opposite of that shown in FIG. 2 , with the sag 13c located at the bottom of the cut end 13 and the shear surface 13d and coining surface 13e formed above it. If it is unclear which of the upper and lower (or left and right) dies will serve as the die and the punch, it is sufficient to actually perform cutting and observe the cut end 13, and refer to the die that presses the surface on the side where the sag 13c is located as the die, and the die that presses the opposite surface as the punch. In any case, as described above, the upper surface 13a of the cut end portion 13 is defined as the surface on the side where the cutting edge of the die is pressed in during cutting of the first flange portion element 20 and the second flange portion element 30, i.e., the surface on the side where the sag 13c is located. Also, the lower surface 13b of the cut end portion 13 is defined as the surface on the side where the cutting edge of the die comes out during cutting of the second flange portion element 30.

[0054] <a. Half-cutting step> Fig. 10 is an explanatory view showing the first die 31 and the first punch 41 used in the half-cutting step of Fig. 9. Fig. 11 is an explanatory view showing an enlarged view of the half-cutting portion 21 of Fig. 10. Fig. 12 is an explanatory view showing the radius of curvature R of the cutting edge of the first punch 41 of Fig. 10. P1 and Clearance C 31-41 10 is an explanatory diagram showing the change in the horn portion 21a due to the change in the temperature.

[0055] The upper side of Fig. 10 shows the state immediately before the half-cutting process, and the lower side of Fig. 10 shows the state immediately after the half-cutting process. As shown in Fig. 10 , in the half-cutting step of the manufacturing method for the metal processed product 1 according to this embodiment, the first blank 2 is half-cut in the plate thickness direction using a first die 31 and a first punch 41 to form the half-cut portion 21. Fig. 10 shows, as one mode of the half-cutting process, a mode in which the first flange portion blank 20 of the first blank 2 held between the first punch 41 and the first plate holder 51 is half-cut (half-punched). The first die 31 constitutes a cutting mold that is pressed into the first flange portion blank 20 during half-cutting. In this embodiment, the mold that presses the portion of the first flange portion blank 20 that will become the flange portion 12 is the first punch 41, and the mold that presses the removed portion 20a is the first die 31.

[0056] Clearance C between the first die 31 and the first punch 41 31-41 (mm) is the negative clearance. Here, the clearance C 31-41 represents the gap between the first die 31 and the first punch 41, and specifically, as shown in FIG. 10, 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.

[0057] 10, 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. 31-41If 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 first flange portion body 20. In addition, the sagging 13c of the cut end portion 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 first flange portion body 20 in the half-cutting step, and reduce the sagging 13c.

[0058] Also, clearance C 31-41 By setting the clearance to a negative value, large hydrostatic stress occurs in the region sandwiched between the first die 31 and the first punch 41. Therefore, the proportion of tensile stress 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 is reduced in the stress generated when the first die 31 is pressed into the first flange portion 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 13d. 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 portion 12. As a result, the material also fills the portion that will become sagging 13c after cutting, thereby reducing the sagging 13c.

[0059] In the direction in which the first die 31 and the first punch 41 are adjacent to each other (the X direction in FIG. 10 ), 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 first flange portion element 20 that is not more than twice the plate thickness t1 of the first flange portion element 20 (i.e., the flange portion 12).

[0060] Clearance C between the first die 31 and the first punch 41 31-41It is preferable that [mm] satisfy the following formula (a1): −0.35×t1≦C 31-41 ≦−0.0125×t1 (a1) Here, t1 is the plate thickness (mm) of the portion to be partially cut of the first element body 2. In this embodiment, the portion to be partially cut of the first element body 2 is the first flange element body 20.

[0061] Clearance C 31-41 is less than or equal to -0.0125 times the plate thickness t1 of the first 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, resulting in complete cutting and the generation of large fracture surfaces, and it is possible to prevent the removed portion 20a from being completely cut off from the first flange portion element 20 in the half-cutting step. On the other hand, when the clearance C 31-41 is equal to or greater than -0.35 times the plate thickness t1 of the first flange portion element 20, the forming load required for half-cutting does not increase and does not exceed the press capacity. Therefore, the burden on the die is small, and the reduction in die life can be suppressed. 31-41 is more preferably set to be equal to or less than −0.10 times or equal to or less than −0.15 times the plate thickness t1 of the first 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 first flange portion element 20.

[0062] The cutting edge of the first die 31 and the cutting edge of the first punch 41 have a predetermined radius of curvature R as shown in FIG. D1 , R P1 The radius of curvature is R (mm).

[0063] The radius of curvature R of the cutting edge of the first die 31 D1 It is preferable that the thickness (mm) satisfies the following formula (a2): 0.10×t1≦R D1 ≦1.50 (a2) The radius of curvature R of the cutting edge of the first punch 41 P1 It is preferable that the thickness (mm) satisfies the following formula (a3): 0.10×t1≦R P1 ≦3.00...(a3)

[0064] radius of curvature R D1If R is 0.10 times or more the plate thickness t1, a large hydrostatic stress is generated under a negative clearance without scraping off the plating layer 13f, and the material to become scrap (i.e., the removed portion 20a) directly below the first die 31 can flow from the cutting edge of the first die 31 to the side surface 31a of the first die 31. p1 is 0.10 times the plate thickness t1 or more, the first die 31 can be pressed deeper into the first flange portion element 20, allowing the material that will become scrap (i.e., the removed portion 20a) 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 that occurs between the material that will become scrap after cutting and the flange material that will become the flange portion 12, among the stresses that occur when the first die 31 is pressed into the first flange portion element 20. As a result, the plating layer 13f can be made to wrap around the sheared surface 13d.

[0065] On the other hand, the radius of curvature R D1 If the radius of curvature R is set to 1.50 mm or less, the amount of material present at the cutting edge of the first die 31 during half-cutting is reduced, and the generation of fracture surfaces in the subsequent finish cutting can be reduced. P1 If the distance is set to 3.00 mm or less, it is possible to prevent the occurrence of burrs due to the falling off of the plating layer after the subsequent coining process and to prevent an increase in the height h0 of the protrusion 13h resulting from the horn portion at the bottom of the coining surface 13e.

[0066] Furthermore, by making the cutting edges of the first die 31 and the first punch 41 rounded, it is possible to increase the amount of cutting of the first flange portion blank 20 in the half-cutting step, compared to when only one of the cutting edges of the first die 31 or the first punch 41 is rounded. In other words, by making the cutting edges of the first die 31 and the first punch 41 rounded, it is possible to reduce the plate thickness t2 (mm) of the half-cut portion 21 of the first blank 2, compared to when only one of the cutting edges of the first die 31 or the first punch 41 is rounded. The thickness t2 of the half-cut portion 21 of the first base body 2 (first flange portion base body 20) corresponds to the distance along the pushing direction of the first die 31 between the connection position between the cutting edge of the first die 31 and the side surface 31a and the upper surface 41b of the cutting edge of the first punch 41 that contacts the lower surface 2b of the first base body 2 when the first die 31 is pushed down to the bottom dead center as shown in the lower side of Figure 10, and can also be said to be the remaining thickness of the removed portion 20a in the half-cut portion 21.

[0067] If only the cutting edge of the first die 31 is rounded, the cutting edge of the first die 31 will come into contact with the cutting edge of the first punch 41 if the push-in amount D of the first die 31 is set to be equal to or greater than the thickness t1 of the flange portion 12. In this case, the push-in 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. Note that, as shown in FIG. 10 , the push-in amount D is the amount of movement of the first die 31 from the position where the first die 31 comes into contact with the top surface of the first flange portion element 20 of the first element 2 to the position where the push-in of the first die 31 stops (hereinafter, this position will also be referred to as the "bottom dead center").

[0068] On the other hand, if the cutting edges of the first die 31 and the first punch 41 are rounded, as shown in FIG. 10 , the amount by which the first die 31 can be pushed in until the cutting edge of the first die 31 contacts the cutting edge of the first punch 41 increases. Therefore, by rounding both the cutting edges of the first die 31 and the first punch 41, the pushing amount D of the first die 31 can be made equal to or greater than the thickness t1 of the flange portion 12, thereby increasing the amount of cutting of the first flange portion element 20 during half-cutting and increasing the proportion of the sheared surface 13d at the cut end 13. This allows the plating layer 13f to extend more around the sheared surface 13d, thereby increasing the proportion of the cut end 13 covered by the plating layer 13f. Furthermore, a smaller remaining thickness t2 reduces the amount of cutting in the finish-cutting process, preventing a situation in which no plating layer remains in part of the finish-cut portion. The remaining thickness t2 may be 0.30 times or less the thickness t1 [mm] of the first flange portion element 20.

[0069] It is preferable that the amount of pressing D (mm) of the first die 31 into the half-cut portion 21 (first flange portion blank 20) ​​satisfies the following formula (a4): 1.00×t1<D≦t1+1.00 (a4) The distance C between the first die 31 and the first punch 41 at the bottom dead center is D1-P1 It is preferable that the thickness (mm) satisfies the following formula (a5): 0.20≦C D1-P1 ...(a5)

[0070] If the indentation amount D is greater than 1.00 times the plate thickness t1, fracture surfaces are less likely to be generated in the subsequent finish cutting. On the other hand, if the indentation amount D is equal to or less than the plate thickness t1 plus 1.00 mm, the height h of the horn portion 21a can be reduced. This makes it easier to suppress the occurrence of whisker burrs, which are the loss of the plating layer after the coining process, and also makes it easier to set the height h0 of the protrusion 13h below the coining surface 13e to 0.20 mm or less.

[0071] On the other hand, the distance C between the first die 31 and the first punch 41 at the bottom dead center D1-P1 By ensuring that the gap C is 0.20 mm or more, it is possible to prevent cracks from occurring during partial cutting, resulting in partial complete cutting. D1-P1is the minimum value of the distance between the first die 31 and the first punch 41 at the bottom dead center.

[0072] 11 , a horn portion 21a having a height h (mm) is formed in the half-cut portion 21. The height h (mm) corresponds to the distance along the pushing direction of the first die 31 between the position on the cutting edge of the first punch 41 on the extension line of the side surface 31a of the first die 31 and the extension line of the upper surface 41b of the first punch 41 that contacts the lower surface 2b of the first element body 2, and is expressed by the following formula: That is, the height h (mm) of the horn portion 21a is determined by the radius of curvature R of the cutting edge of the first punch 41 used in the half-cutting step. P1 (mm), and the clearance C between the first die 31 and the first punch 41 31-41 (mm) is determined by the

[0073]

[0074] The height h can be derived as follows. That is, when a line segment "X" is placed as shown in FIG. 11, the following formula (1) is obtained from Pythagoras' theorem. P1 2 = (R P1 - | C 31-41 |) 2 +X 2 ...(1) When equation (1) is solved for X, the following equation (2) is obtained. Here, h = R P1 Since the height h is −X, by substituting X in equation (2) into this, the above-mentioned equation for the height h is obtained.

[0075] The height h of the horn portion 21a is the radius of curvature R of the cutting edge of the first punch 41. P1 The larger the clearance C 31-41 The radius of curvature R of the cutting edge of the first punch 41 in FIG. P1 12(c) shows the horn portion 21a when the radius of curvature R of the cutting edge of the first punch 41 is larger than that of ... cutting edge of the first punch 41 when the radius of curvature R of the cutting edge of the P1 As the clearance C increases, 31-4112(a) to 12(c), the greater the height h of the horns 21a, the more the lower surface 2b of the first body 2 rises above the upper surface 42b of the second punch 42 when the first body 2 is placed in the mold (second die 32 and second punch 42) used for finish cutting.

[0076] <b. Finish Cutting Process> Next, Fig. 13 is an explanatory diagram showing the second die 32 and the second punch 42 used in the finish cutting process of Fig. 9. The upper side of Fig. 13 shows the state immediately before the finish cutting process, and the lower side of Fig. 13 shows the state immediately after the finish cutting process.

[0077] In the finish-cutting step, as shown in FIG. 13 , the first flange portion element 20 having the half-cut portion 21 is finish-cut using a second die 32 and a second punch 42. FIG. 13 shows, as one mode of finish-cutting, a mode in which the second flange portion element 30 is punched out from the first 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 first flange portion element 20 during finish-cutting. In this embodiment, the second punch 42 is the mold that presses the portion of the first flange portion element 20 that will become the flange portion 12, and the second die 32 is the mold that presses the removed portion 20 a. 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.

[0078] 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 in 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 may come into contact with the half-cut cut edge 13 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 13d. Regarding the positional relationship between the second punch 42 and the first element body 2, it is preferable that the diameter of the second punch 42 is smaller than the diameter of the first die 31. However, as long as the diameter of the second punch 42 is smaller than the diameter of the second die 32, there is no problem even if the diameter of the second punch 42 is the same as the diameter of the first die 31. Conversely, if the diameter of the second punch 42 is larger than the diameter of the first die 31, a step will occur in the cut edge 13.

[0079] The finish cutting in this embodiment is performed from the same direction as the half cutting. That is, when the first die 31 is forced into the first flange portion element 20 from the upper surface side of the first flange portion element 20 in the half cutting as shown in Fig. 10, the second die 32 is also forced into the first flange portion element 20 from the upper surface side of the first flange portion element 20 in the finish cutting as shown in Fig. 13. This separates the removed portion 20a from the first flange portion element 20, and obtains the second element 3 having the cut end portion 13.

[0080] Clearance C between the second die 32 and the second punch 42 32-42 [mm] is the positive clearance. Clearance C 32-42 is 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.

[0081] 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 It is preferable that the following formula (b1) is satisfied: 0.01≦C 32-42≦0.20×t2 ... (b1) Here, t2 is the plate thickness of the half-cut portion 21 of the first base body 2 (first flange portion base body 20) as described above, and corresponds to the distance along the pushing direction of the first die 31 between the connection position between the cutting edge of the first die 31 and the side surface 31a and the upper surface 41b of the cutting edge of the first punch 41 that contacts the lower surface 2b of the first base body 2 when the first die 31 is pushed in to the bottom dead center as shown in the lower side of Figure 10, and can also be said to be the remaining plate thickness of the removed portion 20a in the half-cut portion 21.

[0082] 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 the shearing distance t2 is equal to or less than 0.20 times the plate thickness t2, burrs are unlikely to be generated. Here, the smooth surface of the end surface smoothed by the side surface 32a of the second die 32 becomes the second shear surface 13d2.

[0083] The cutting edge of the second die 32 has a predetermined radius of curvature R D2 As shown in FIG. 13, the second die 32 is pressed into the portion of the first flange portion body 20 where the finish cutting is to be performed, and therefore the cutting edge of the second die 32 is formed into an R shape having a radius of curvature R D2 The cutting edge of the second punch 42 is formed into an R-shape having 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 0.10 times the thickness t1 of the first flange portion element 20 of the first element 2, and may be less than 0.06 times, less than 0.04 times, or less than 0.02 times, as necessary.

[0084] The radius of curvature R of the cutting edge of the second die 32 D2 It is preferable that R (mm) satisfies the following formula (b2): 0.25≦R D2 ≦1.50×t2...(b2) Radius of curvature R D2 If the radius of curvature R is 0.25 mm or more, the plating layer 13f that has reached the sheared surface 13d will not be scraped off by the second die 32.D2 If is 1.50 times or less the plate thickness t2, burrs are less likely to be generated.

[0085] When the cut end 13 is formed on the outer periphery of the metal workpiece 1, the inner diameter D32 of the second die 32 is set to be equal to or larger than the inner diameter D31 of the first die 31, and when the cut end 13 is formed on the inner periphery of the metal workpiece 1, the outer diameter d32 of the second die 32 is set to be equal to or smaller than the outer diameter d31 of the first die 31. Specifically, when the cut end 13 is formed on the outer periphery of the metal workpiece 1, the absolute value |D32-D31| of the difference between the inner diameter D31 of the first die 31 and the inner diameter D32 of the second die 32 is preferably 1.00 mm or less. When the cut end 13 is formed on the inner periphery of the metal workpiece 1, the absolute value |d32-d31| of the difference between the outer diameter d31 of the first die 31 and the outer diameter d32 of the second die 32 is preferably 1.00 mm or less. This allows the step that occurs at the cut end 13 of the metal workpiece 1 due to the diameter difference D32-D31 or d32-d31 between the dies 31 and 32 to be reduced by performing two processes, the semi-cutting process and the finish cutting process, and a good cut cross section can be obtained.

[0086] In addition, when a step at the cut end 13 is acceptable as part of the quality of the metal workpiece 1, the absolute value of the inner diameter difference |D32 - D31| when the cut end 13 is formed on the outer periphery of the metal workpiece 1 and the absolute value of the outer diameter difference |d32 - d31| when the cut end 13 is formed on the inner periphery of the metal workpiece 1 may be greater than 1.00 mm. Furthermore, the upper limits of the absolute values ​​of these diameter differences |D32 - D31| and |d32 - d31| are preferably smaller, and may be 0.75 mm, 0.50 mm, 0.35 mm, or 0.20 mm. The lower limits of the absolute values ​​of the diameter differences |D32 - D31| and |d32 - d31| are 0 mm. Furthermore, the step at the cut end 13 of the metal workpiece 1 is preferably smaller, and may be 0.5 mm or less. The upper limit of the step that occurs at the cut end 13 of the metal processed product 1 may be 0.4 mm, 0.3 mm, 0.2 mm, or 0.1 mm, as necessary. When cutting the material in the finish cutting process, local elongation occurs in the material at the tip, causing it to stretch into a thorn-like shape, resulting in so-called burrs. These burrs have little volume and are crushed in the subsequent coining process, so they do not cause a step that occurs at the end. However, the horns 21 a that remain at the bottom of the second flange portion element 30 after finish cutting have more volume than the burrs and can cause a step that occurs at the end after coining.

[0087] After the finish cutting, horns 21a remain at the bottom of the second flange portion element 30. The higher the height h of the horns 21a after partial cutting, the larger the horns 21a remaining after the finish cutting.

[0088] <c. Coining step> Next, Fig. 14 is an explanatory diagram showing the pad 7 and coining block 8 used in the coining step of Fig. 9, and Fig. 15 is a photograph showing the cut end 13 of the metal workpiece 1 after the coining step. As shown in Fig. 14, in the coining step of this embodiment, the cut end 13 of the second element 3 is sandwiched between the pad 7 and the coining block 8. The pad 7 has a vertical wall surface 70, a bottom wall surface 71, and a pressing surface 72.

[0089] The vertical wall surface 70 is disposed so as to face and be substantially parallel to the shear surface 13d of the second element body 3 when the cut end portion 13 of the second element body 3 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. 11 ).

[0090] The bottom wall surface 71 is disposed so as to face the coining block 8 in the plate thickness direction T of the cut end portion 13, with the second element body 3 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).

[0091] The pressing surface 72 is a surface that connects the vertical wall surface 70 and the bottom wall surface 71 at the corner where the vertical wall surface 70 and the bottom wall surface 71 meet. The pressing surface 72 is provided to form a coining surface (coining surface 13e in FIGS. 2 to 6) on the second element body 3, and has a flat or curved shape corresponding to the shape of the coining surface. For example, as shown in FIGS. 2 to 4, when the coining surface 13e is a flat chamfered surface (hereinafter referred to as a "tapered surface"), the pressing surface 72 is flat and inclined relative to the vertical wall surface 70 and the bottom wall surface 71, as shown in FIG. 14. On the other hand, as shown in FIG. 5, when the coining surface 13e of the second element body 3 is a curved chamfered surface (hereinafter referred to as an "R surface"), the pressing surface 72 is a concave curved surface.

[0092] 14 , with the cut end 13 of the second element 3 facing the vertical wall surface 70 of the pad 7, the second element 3 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, and the second element 3 is pressed down to a position where the lower surface 13b of the second element 3 contacts the bottom wall surface 71. Here, before the lower surface 13b of the second element 3 contacts the bottom wall surface 71, the corner portion 13m or the horn portion 21a is pressed against the pressing surface 72. After the corner portion 13m or the horn portion 21a is pressed against the pressing surface 72, the coining block 8 is pressed further, and the lower surface 13b of the second element 3 contacts the bottom wall surface 71. In this process, the corner portion 13m or the horn portion 21a is crushed by the pressing surface 72, and the coining surface 13e shown in Figures 2 to 5 is formed. After the coining process, the cut end portion 13 of the metal workpiece 1 is in a state such as that shown in the photograph in Figure 15.

[0093] The coining surface 13e is a smooth surface onto which the surface of the pressing surface 72 is transferred, and is less susceptible to red rust than a rough fracture surface. This is thought to be because the smooth surface roughness makes it difficult for moisture to remain on the coining surface 13e. In addition, the plating layer 13k on the underside 13b of the cut end portion 13 is thinly spread on the coining surface 13e, which is also thought to be a factor in making red rust less likely to occur.

[0094] Meanwhile, during the coining process that forms the coining surface 13e, the material at the corner 13m of the cut end 13 escapes inward in a direction perpendicular to the thickness direction T (the X-axis direction in the figures), forming a protrusion 13h (see FIGS. 2 to 6). As described above, if the height h0 of the protrusion 13h is large, a space is created between the underside 13b of the cut end 13 and other structures, causing rattling. Furthermore, as shown in FIG. 7, the plating layer 13k on the horn 21a of the cut end 13 may become caught in the protrusion 13h, and the plating layer 13k caught in the protrusion 13h may fall off, resulting in whisker burrs.

[0095] The inventors conducted experiments in which the conditions for cutting and coining were varied over various ranges to investigate the height h0 of the protrusions 13h and the occurrence of burrs. As a result, it was found that the height h0 of the protrusions 13h and the occurrence of burrs are correlated with the height h of the horns 21a after half-cutting (before finish cutting) and the coining area Ar of the pad 7 used in the coining process. Note that burrs may occur depending on the finish cutting conditions, but the burrs are small in volume and do not cause burrs to occur in the subsequent coining process.

[0096] In the manufacturing method of the metal processed product 1 according to the embodiment of the present invention, the coining area Ar is set to satisfy the following formula: h≦−1.09Ar+1.04, where h is the height (mm) of the horn portion 21a after half-cutting, and Ar is the coining area (mm 2 ) By setting the coining area Ar to satisfy this formula, the height h0 of the protrusion 13h can be set to 0.20 mm or less. The manufacturing method of the metal processed product 1 according to the embodiment of the present invention may be understood to include a step of setting the height h and coining area Ar of the horn portion 21a after half-cutting so as to satisfy the above formula.

[0097] In the method for manufacturing the metal processed product 1 according to the embodiment of the present invention, the coining area Ar is preferably set to satisfy the following formula: h≦1.20Ar 2 -2.07Ar+0.90 As described above, h is the height (mm) of the horn portion 21a after half-cutting, and Ar is the coining area (mm 2 ) By setting the coining area Ar to satisfy this formula, the occurrence of whisker burrs can be avoided. The manufacturing method of the metal processed product 1 according to the embodiment of the present invention may be understood to include a step of setting the height h of the horn portion 21a after half-cutting and the coining area Ar to satisfy the above formula.

[0098] <Examples of Processed Product> In the above embodiment, the metal processed product 1 is described as a motor case as shown in Fig. 1, but the metal processed product 1 manufactured by the processed product manufacturing method according to this embodiment may be any article made from a plated metal sheet and having a cut end portion 13. Examples of the metal processed product 1 include plate materials, drawn products having flange portions 12, burred products having flange portions 12, bulged products having flange portions 12, bent products, and punched products such as various washers, plates, gears, and springs.

[0099] The metal workpiece 1 may be, for example, a circular flat washer 900 as shown in FIG. 16 . The metal workpiece 1 may also be, for example, a flat washer 910A, 910B, or 910C having teeth 911 as shown in FIG. 17 . Alternatively, the metal workpiece 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 metal workpiece 1 may be, for example, a disc spring 930 having teeth 931 as shown in FIG. 19 .

[0100] When the metal processed product 1 is an annular plate member such as those shown in FIGS. 16 to 19, the outer and inner peripheries thereof become the cut end portions 13.

[0101] 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.

[0102] The cutting die shown in FIG. 20 is a die for manufacturing an annular metal workpiece 90 such as a flat washer 900, and includes a hollow cylindrical die (hereinafter referred to as the "outer die") 61, a columnar die (hereinafter referred to as the "inner die") 63, and a hollow cylindrical punch 65 that supports a disk-shaped blank 9 (see FIG. 23). 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 metal workpiece 90, and the outer diameter of the inner die 63 corresponds to the inner diameter of the metal 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.

[0103] When the base body 9 is finish-cut using such a cutting die, as shown in Figure 21, the portion 9a that is on the outer side of the outer surface 91 of the metal workpiece 90 is cut by the outer die 61, and the portion 9b that is on the inner side of the inner surface 92 of the metal workpiece 90 is cut by the inner die 63.

[0104] The coining die shown in Figure 22 is a die for coining the cut end 9c of the element 9 after cutting using the die shown in Figure 20, and includes a pad 7 and a coining block 8. The pad 7 has a bottom 75, a central protrusion 76 protruding from the bottom 75, and a side periphery 77. The outer peripheral surface of the central protrusion 76 and the inner peripheral surface of the side periphery 77 form the vertical wall surface 70, and the upper surface of the bottom 75 forms the above-mentioned bottom wall surface 71. A pressing surface 72 is formed between the bottom wall surface 71 and the vertical wall surface 70. The coining block 8 may be annular. The central protrusion 76 is passed through a hole 9d in the element 9, which has been formed into an annular shape by cutting, and the element 9 is pressed down by the coining block 8, thereby coining the cut end 9c of the element 9. By these cutting and coining processes, a metal processed product 90 (flat washer 900) as shown in Fig. 16 can be formed. However, this figure explains the coining process, and does not show the mechanism for ejecting the product from the die after processing.

[0105] Furthermore, the metal processed product 1 may be, for example, a disk-shaped plate 940 as shown in FIG.

[0106] 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.

[0107] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0108] The inventors created multiple processed product samples by varying the conditions for semi-cutting, finish-cutting, and coining over a variety of ranges, as shown in Tables 1 to 3 below. A flat Zn-6%Al-3%Mg (by mass) alloy-plated steel sheet with a thickness of 3.2 mm was used as the first element body 2. The coating weight of the steel sheet was 90 g / m 2 (One-sided).

[0109]

[0110]

[0111]

[0112] (Half-cutting step) The half-cutting step was carried out on the first element body 2 by the method shown in Fig. 10. The half-cutting process was carried out by pressing the first die 31 into the first element body 2 held by the first punch 41 and the first plate holder 51. The first die 31 was an annular body with a circular hole having an inner diameter of 85.00 mm. The first punch 41 was cylindrical so that it could be inserted into the circular hole of the first die 31. The outer diameter of the first punch 41 was set to 1 / 4 the clearance C shown in Table 1. 31-41 The cutting edges of the first die 31 and the first punch 41 have a radius of curvature R shown in Table 1. D1 , R P1 The pushing amount D of the first die 31 and the distance C between the first die 31 and the first punch 41 at the bottom dead center were D1-P1was as shown in Table 1.

[0113] After the half-cutting process, the thickness t2 of the half-cut portion 21 (see FIG. 10) formed on the first element body 2 was measured. The measurement results are shown in Table 2. In addition, the height h (see FIG. 11) of the horn portion 21a of the half-cut portion 21 formed on the first element body 2 was calculated using the above-mentioned formula. The calculation results are also shown in Table 1.

[0114] The formulas (a1) to (a5) in the table relating to the half-cutting process are as follows: -0.35 × t1≦C 31-41 ≦−0.0125×t1 (a1) where t1 is the plate thickness (mm) of the part to be cut off of the first element body 2, and C 31-41 is the clearance (mm) between the first die 31 and the first punch 41. 0.10×t1≦R D1 ≦1.50 (a2) where R D1 is the radius of curvature (mm) of the cutting edge of the first die 31. 0.10×t1≦R P1 ≦3.00 (a3) ​​where R P1 is the radius of curvature (mm) of the cutting edge of the first punch 41. 1.00×t1<D≦t1+1.00 (a4) Here, t1 is the plate thickness (mm) of the part to be half-cut of the first body 2, and D is the amount of depression (mm) of the first die 31 into the half-cut part 21. 0.20≦C D1-P1 ...(a5) where C D1-P1 is the distance (mm) between the first die 31 and the first punch 41 at the bottom dead center.

[0115] In the columns in Tables 1 and 2 indicating whether or not various conditions are met, "Yes" indicates that the conditions are met, and "N" indicates that the conditions are not met.

[0116] (Finish Cutting Process) The first element body 2 after the half-cutting process was subjected to the finish cutting process by the method shown in Fig. 13 to obtain a second element body 3. The finish cutting process was performed by forcing the second die 32 into the first element body 2 held by the second punch 42 and the second plate holder 52. The second die 32 was an annular body with a circular hole with an inner diameter of 85.00 mm. The second punch 42 was cylindrical so that it could be inserted into the circular hole of the second die 32. The outer diameter of the second punch 42 was determined by the clearance C shown in Table 2. 32-42 The cutting edge of the second die 32 has a radius of curvature R shown in Table 2. D2 The cutting edge of the second punch 42 was an unrounded square shape.

[0117] The formulas (b1) and (b2) for the finish cutting process in the table are as follows: 0.01≦C 32-42 ≦0.20×t2 (b1) where C 32-42 is the clearance (mm) between the second die 32 and the second punch 42, and t2 is the plate thickness of the half-cut portion 21 of the first body 2. 0.25≦R D2 ≦1.50×t2 (b2) where R D2 is the radius of curvature (mm) of the cutting edge of the second die 32.

[0118] (Coining step) The second element body 3 obtained in the finish cutting step was subjected to the coining step using the method shown in Fig. 14 to obtain a processed product sample. The coining process was performed by pressing the corner portion 13m of the cut end portion 13 of the second element body 3 against the pressing surface 72 of the pad 7. The pressing surface 72 of the pad 7 was flat or curved, as shown in Table 2. The coining area Ar was changed as shown in Table 2.

[0119] (Investigation of Processed Product Samples) The cut end surfaces of the processed product samples obtained through the above-described processes were examined for the inclination angle θd1 [°] of the first sheared surface 13d1, the inclination angle θd2 [°] of the second sheared surface 13d2, the remaining length L1 [mm] of the plating component, the sag length Z [mm], the radius of curvature R0 [mm] or the tapered surface height C0 [mm] of the coining surface 13e, the height Lc [mm] of the upper end of the plating layer 13k, the height h0 [mm] of the protrusion 13h, and the presence or absence of whisker burrs. The results are shown in Table 3.

[0120] Regarding the presence or absence of burrs, whisker-shaped burrs that fell off during coining were evaluated as "present." Regarding the presence or absence of burrs, burrs that were crushed by coining were evaluated as "absent," and burrs that were not crushed completely by coining and remained floating, or burrs that fell off after coining, were evaluated as "present." Here, burrs are those from which plating components have fallen off, and burrs whose main component is the steel substrate of the steel sheet are referred to as "burrs."

[0121] In the table, Examples 1 to 18 of the present invention are examples in which the height h0 of the protrusion 13h on the cut end surface of the processed sample is 0.20 mm or less. Comparative Examples 1 to 5 are examples in which the height h0 of the protrusion 13h on the cut end surface of the processed sample exceeds 0.20 mm, or the processing was stopped during the semi-cutting or finish cutting. In all of Examples 1 to 18 of the present invention and Comparative Examples 1 to 5, the clearance C between the first die 31 and the first punch 41 in the semi-cutting step was 31-41 (mm) is set as a negative clearance, and the cutting edge of the first die 31 and the cutting edge of the first punch 41 are set to a predetermined radius of curvature R D1 , R P1 The radius of curvature is R (mm).

[0122] Here, Figure 24 is a graph showing the relationship between the height h of the horn portion 21a after half-cutting (before finish-cutting) in the example and the coining area Ar of the pad 7 used in the coining process. The vertical axis of the graph shown in Figure 24 is the height h (mm) of the horn portion 21a after half-cutting. The height h of the horn portion 21a after half-cutting is as explained using Figure 11. The horizontal axis of the graph shown in Figure 24 is the coining area Ar (mm2 The coining area Ar refers to the area of ​​the region surrounded by the extended surface 70a of the vertical wall surface 70, the extended surface 71a of the bottom wall surface 71, and the pressing surface 72 when the pad 7 is viewed in a cross section along the pressing direction of the corner portion 13m as shown in FIG.

[0123] In the graph, the triangular or circular plots labeled "a1" to "a18" indicate the height h and coining area Ar of the horn portion 21a in invention examples 1 to 18. The cross plots labeled "b1" to "b3" indicate the height h and coining area Ar of the horn portion 21a in comparative examples 1 to 3. That is, "a" indicates the plot of an invention example, and "b" indicates the plot of a comparative example. The plot numbers correspond to the numbers of each example.

[0124] Among the plots for the present invention examples, the triangular plots (a3, a6, a10, a11, a13, and a18) show the height h and coining area Ar of the horn portion 21a after partial cutting when the height h0 of the protrusion 13h is 0.20 mm or less but burrs have occurred. The circular plots (a1, a2, a4, a5, a7 to a9, a12, and a14 to a17) show the height h and coining area Ar of the horn portion 21a after partial cutting when the height h0 of the protrusion 13h is 0.20 mm or less and no burrs have occurred. The cross plots representing comparative examples 1 to 3 show the height h and coining area Ar of the horn portion 21a after partial cutting when the height h0 of the protrusion 13h exceeds 0.20 mm and burrs have occurred.

[0125] From the graph in Figure 24, it can be seen that the height h0 of the protrusion 13h and the occurrence of burrs are correlated with the height h of the horn portion 21a after partial cutting (before finish cutting) and the coining area Ar of the pad 7 used in the coining process.

[0126] The straight line shown in the graph is an approximate line (h = -1.09Ar + 1.04) obtained from test examples in which the height h0 of the protrusion 13h was 0.20 mm or less. It can be seen that the height h0 of the protrusion 13h can be set to 0.20 mm or less if the height h of the horn 21a after partial cutting and the coining area Ar are included in the region below this approximate line.

[0127] The curve shown in the graph is an approximation curve (h=1.20Ar) obtained from a test example in which the occurrence of whisker burrs was avoided. 2 It can be seen that if the height h of the horn portion 21a after partial cutting and the coining area Ar are included in the region below this approximate curve, the height h0 of the protrusion 13h can be set to 0.20 mm or less, and the occurrence of whisker burrs can be avoided.

[0128] Inventive Examples 1 to 14 are examples that satisfy the above-mentioned formulas (a1) to (a5) regarding the semi-cutting step and formulas (b1) and (b2) regarding the finish-cutting step.

[0129] In contrast, Invention Examples 15 to 17 are examples that do not satisfy at least one of the formulas (a1) to (a5) related to the half-cutting step. More specifically, Invention Examples 15 and 16 do not satisfy formula (a2), and Invention Example 17 does not satisfy formulas (a3) ​​and (a4).

[0130] The processed product samples of Inventive Examples 1 to 14 achieved the target ratio L1 / t1 of 0.80 or more, where L1 is the remaining length of the plating component at which the sheared surface 13d is covered by the plating layer 13f on the surface of the plated metal sheet, and t1 is the sheet thickness at the cut end 13. In contrast, the processed product samples of Inventive Examples 15 to 17 had ratios L1 / t1 below 0.80. These results demonstrate that it is preferable to satisfy the above-described formulas (a1) to (a5) regarding the semi-cutting step.

[0131] Moreover, Inventive Example 18 is an example that does not satisfy at least one of the formulas (b1) and (b2) regarding the finish cutting process. More specifically, Inventive Example 18 does not satisfy the formula (b1).

[0132] In the processed product samples of Inventive Examples 1 to 14, the target height Lc of the upper end of the plating layer 13k extending around from the lower surface 13b of the cut end portion 13 in the thickness direction T, based on the lower surface 13b of the cut end portion 13, was set to be at least 0.10 times the radius of curvature R0 of the coining surface 13e or the height C0 of the tapered surface. In contrast, in the processed product sample of Inventive Example 18, the height Lc was less than 0.10 times the radius of curvature R0 or the height C0 of the tapered surface. This result demonstrates that it is preferable to satisfy the above-mentioned formulas (b1) and (b2) related to the finish cutting process.

[0133] The invention described in this specification can also be described as follows: [1] A method for manufacturing a metal processed product, using a plated metal sheet having a plating layer on its surface as a starting material, for manufacturing a metal processed product having a cut edge along the thickness direction of the starting material and having a coining surface formed at a corner of the cut edge, comprising: a half-cutting step using a first die and a first punch to half-cut a first element formed from the starting material in the thickness direction to form a half-cut portion; a finish-cutting step using a second die and a second punch to finish-cut the half-cut portion in the same direction as the half-cutting to obtain a second element having the cut edge; and a coining step to press a corner of the cut edge of the second element against a pad to obtain a metal processed product having a coining surface formed at the corner, wherein with respect to the half-cutting step: a clearance C between the first die and the first punch 31-41 (mm) is set to a negative clearance, and the cutting edge of the first die and the cutting edge of the first punch have a predetermined radius of curvature R D1 , R P1 (mm), a horn portion having a height h (mm) is formed in the half-cut portion, and the height h (mm) corresponds to the distance between a position on the cutting edge of the first punch on an extension line of the side surface of the first die and an extension line of the upper surface of the first punch that contacts the lower surface of the first base body, along the pushing direction of the first die, and is expressed by the following formula: Regarding the coining process, the pad has a vertical wall surface, a bottom wall surface, and a flat or curved pressing surface that connects the vertical wall surface and the bottom wall surface at the corner where the vertical wall surface and the bottom wall surface meet, and against which the corner portion of the cut end portion is pressed, and when the pad is viewed in a cross section along the pressing direction of the corner portion, the area of ​​the region surrounded by the extended surface of the vertical wall surface, the extended surface of the bottom wall surface, and the pressing surface is defined as a coining area Ar (mm 2 ), the coining area Ar (mm 2 ) is set to satisfy the following formula: h≦−1.09Ar+1.04. [2] The coining area Ar (mm 2 ) is set to further satisfy the following formula: h≦1.20Ar 2 -2.07Ar+0.90 The method for manufacturing the metal processed product according to item 1. [3] In the semi-cutting step, the clearance C between the first die and the first punch is 31-41 (mm) satisfies the following formula (a1), -0.35 × t1≦C 31-41 ≦−0.0125×t1 (a1) where t1 is the plate thickness (mm) of the part to be half-cut of the first element body, and the radius of curvature R of the cutting edge of the first die. D1 (mm) satisfies the following formula (a2): 0.10 × t1≦R D1 ≦1.50 (a2) The radius of curvature R of the cutting edge of the first punch P1 (mm) satisfies the following formula (a3): 0.10 × t1≦R P1 ≦3.00 (a3) ​​The amount of pressing D (mm) of the first die into the half-cut portion satisfies the following formula (a4): 1.00×t1<D≦t1+1.00 (a4) The distance C between the first die and the first punch at the bottom dead center D1-P1 (mm) satisfies the following formula (a5): 0.20≦C D1-P1 ...(a5) The method for manufacturing a metal processed product according to claim 1 or 2. [4] Regarding the finish cutting step, the clearance C between the second die and the second punch is 32-42(mm) satisfies the following formula (b1): 0.01≦C 32-42 ≦0.20×t2 (b1) where t2 is the plate thickness (mm) of the half-cut portion of the first blank, which corresponds to the distance along the pressing direction of the first die between the connecting position of the cutting edge of the first die and the side surface and the upper surface of the cutting edge of the first punch that contacts the lower surface of the first blank when the first die is pressed down to the bottom dead center, and D2 The cutting edge of the second die has a radius of curvature R (mm). D2 (mm) satisfies the following formula (b2): 0.25≦R D2 ≦1.50×t2 (b2) A method for manufacturing a metal processed product according to any one of Items 1 to 3. [5] A metal processed product using a plated metal sheet having a plating layer on its surface as a raw material, and having a cut edge along a thickness direction of the raw material, wherein the cut edge has a sag, a sheared surface, and a coining surface in this order in the thickness direction of the cut edge from the upper surface side to the lower surface side, the sheared surface has, in the thickness direction, a first sheared surface continuing with the sag and a second sheared surface continuing with the first sheared surface, an inclination angle θd1 of the first sheared surface with respect to the thickness direction and an inclination angle θd2 of the second sheared surface with respect to the thickness direction satisfy θd1 > θd2, a ratio L1 / t1 of a remaining length L1 (mm) of a plating component where the sheared surface is covered by the surface plating layer to a thickness t1 (mm) of the cut edge is 0.80 or more, a ratio Z / t1 of a length Z (mm) of the sag in the plate thickness direction from the top surface of the cut end toward the bottom surface of the cut end to a plate thickness t1 (mm) of the cut end is -0.10 or more and less than 0.10; a protrusion having a height h0 of more than 0 mm and not more than 0.20 mm is provided at a lower part of the coining surface; the surface plating layer wraps around from the bottom surface of the cut end to the end surface of the cut end, and a height Lc (mm) in the plate thickness direction from the bottom surface of the upper end of the plating layer wraps around from the bottom surface is 0.10 or more times a radius of curvature R0 (mm) of the coining surface or a tapered surface height C0 (mm).

[0134] DESCRIPTION OF SYMBOLS 1: Metal processed product 2: First element body 3: Second element body 7: Pad 13: Cut end 13a: Upper surface 13b: Lower surface 13c: Sagging 13d: Shear surface 13d1: First shear surface 13d2: Second shear surface 13e: Coining surface 13f: Plating layer from upper surface 13h: Protrusion 13k: Plating layer from lower surface 13m: Corner portion 21: Half-cut portion 21a: Horn portion 31: First die 32: Second die 41: First punch 42: Second punch 70: Vertical wall surface 71: Bottom wall surface 72: Pressing surface

Claims

1. A method for manufacturing a metal processed product using a plated metal sheet having a plating layer on a surface thereof as a starting material, the method comprising: a half-cutting step of cutting a first element formed from the element in the thickness direction to form a half-cut portion using a first die and a first punch; a finish-cutting step of using a second die and a second punch to finish-cut the half-cut portion in the same direction as the half-cutting to obtain a second element having the cut end; and a coining step of pressing a corner portion of the cut end of the second element against a pad to obtain a metal processed product having a coining surface formed on the corner portion, wherein with respect to the half-cutting step: - a clearance C between the first die and the first punch is 31-41 (mm) is set to a negative clearance, and the cutting edge of the first die and the cutting edge of the first punch have a predetermined radius of curvature R D1 , R P1 (mm), a horn portion having a height h (mm) is formed in the half-cut portion, and the height h (mm) corresponds to a distance between a position on the cutting edge of the first punch on an extension line of a side surface of the first die and an extension line of the upper surface of the first punch that contacts the lower surface of the first body, along the pressing direction of the first die, and is expressed by the following formula: Regarding the coining process, the pad has a vertical wall surface, a bottom wall surface, and a flat or curved pressing surface that connects the vertical wall surface and the bottom wall surface at the corner where the vertical wall surface and the bottom wall surface meet, and against which the corner portion of the cut end portion is pressed, and when the pad is viewed in a cross section along the pressing direction of the corner portion, the area of ​​the region surrounded by the extended surface of the vertical wall surface, the extended surface of the bottom wall surface, and the pressing surface is defined as a coining area Ar (mm 2 ), the coining area Ar (mm 2 ) is set to satisfy the following formula: h≦-1.09Ar+1.04 A method for manufacturing a metal processed product.

2. The coining area Ar (mm 2 ) is set to further satisfy the following formula: h≦1.20Ar 2 -2.07Ar+0.90 The method for manufacturing a metal processed product according to claim 1.

3. Regarding the semi-cutting step, the clearance C between the first die and the first punch 31-41 (mm) satisfies the following formula (a1), -0.35 × t1 ≦ C 31-41 ≦−0.0125×t1 (a1) where t1 is the plate thickness (mm) of the portion to be cut in half of the first body, and the radius of curvature R of the cutting edge of the first die. D1 (mm) satisfies the following formula (a2): 0.10 × t1 ≦ R D1 ≦1.50 (a2) The radius of curvature R of the cutting edge of the first punch P1 (mm) satisfies the following formula (a3): 0.10 × t1≦R P1 ≦3.00 (a3) ​​A pressing amount D (mm) of the first die against the half-cut portion satisfies the following formula (a4): 1.00×t1<D≦t1+1.00 (a4) A distance C between the first die and the first punch at the bottom dead center D1-P1 (mm) satisfies the following formula (a5): 0.20≦C D1-P1 ...(a5) A method for manufacturing a metal processed product according to claim 1 or 2.

4. Regarding the finish cutting process, the clearance C between the second die and the second punch 32-42 (mm) satisfies the following formula (b1), 0.01≦C 32-42 ≦0.20×t2 (b1) Here, t2 is a plate thickness (mm) of the half-cut portion of the first blank, which corresponds to a distance along the pressing direction of the first die between a connecting position of the cutting edge of the first die and a side surface, and the upper surface of the cutting edge of the first punch that contacts the lower surface of the first blank, when the first die is pressed down to the bottom dead center, and D2 The radius of curvature R of the cutting edge of the second die is 1 mm. D2 (mm) satisfies the following formula (b2): 0.25≦R D2 ≦1.50×t2 (b2) A method for manufacturing a metal processed product according to claim 3.

5. A metal processed product using a plated metal sheet having a plating layer on its surface as a raw material, and having a cut end along the sheet thickness direction of the raw material, wherein the cut end has a sag, a sheared surface, and a coining surface in that order in the sheet thickness direction of the cut end from the upper surface side to the lower surface side, the sheared surface has a first sheared surface continuing to the sag and a second sheared surface continuing to the first sheared surface in the sheet thickness direction, the inclination angle θd1 of the first sheared surface with respect to the sheet thickness direction and the inclination angle θd2 of the second sheared surface with respect to the sheet thickness direction satisfy θd1>θd2, the ratio L1 / t1 of the remaining plating component length L1 (mm) where the sheared surface is covered by the plating layer on the surface to the sheet thickness t1 (mm) of the cut end is 0.80 or more, a ratio Z / t1 of a length Z (mm) of the sagging in the sheet thickness direction from the top surface of the cut end toward the bottom surface of the cut end to a sheet thickness t1 (mm) of the cut end is -0.10 or more and less than 0.10, a protrusion having a height h0 of more than 0 mm and not more than 0.20 mm is provided on a lower part of the coining surface, the plating layer of the surface wraps around from the bottom surface of the cut end to the end surface of the cut end, and a height Lc (mm) of an upper end of the plating layer wraps around from the bottom surface in the sheet thickness direction from the bottom surface is 0.10 times or more the radius of curvature R0 (mm) of the coining surface or the tapered surface height C0 (mm).

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