Processed product and method for manufacturing the processed product

Abstract

To provide a finished article which can suppress a red rust generating region and can suppress remaining burrs even if a plated steel plate with a plate thickness exceeding 2.0 mm is used as a raw material.SOLUTION: A finished article with a plated steel plate having a plating layer on a surface thereof as a raw material has a cut end part 13 along a plate thickness direction of the finished article. The cut end part 13 has an undercut 13c, a sheared surface 13d, a fracture surface 13e and a coining surface 13f in this order in a plate thickness direction T of the cut end part 13 toward an undersurface 13b side from a top face 13a side. A length W3 of the fracture surface 13e between the sheared surface 13d and the coining surface 13f in the plate thickness direction T of the cut end part 13 is more than 0 mm and 0.5 mm or less, and a ratio L1 / W2 of a length L1 of the coining surface 13f in the plate thickness direction T and a distance W2 between the undersurface 13b of the cut end part 13 and an upper end of the fracture surface 13e is 0.95 or less.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a processed product having a cut end along the plate thickness direction of a plated steel sheet having a plating layer on the surface, and a method for manufacturing the same, using the plated steel sheet as a raw material.

Background Art

[0002] In recent years, as components of devices such as automobiles and home appliances, the use of processed products using a plated steel sheet having a plating layer on the surface as a raw material has been increasing. By using a plated steel sheet as a raw material, the plating process after forming the processed product can be omitted, and the manufacturing cost can be reduced. In addition, by omitting the plating process after forming, deterioration of the dimensional accuracy of the component due to the plating process after forming can be avoided. Omitting the plating process after forming is particularly considered for components that require high dimensional accuracy, such as motor cases.

[0003] When the plating process after forming is omitted, a region where the steel sheet base material is exposed appears at the cut end of the processed product. Depending on the environment where the processed product is placed, red rust may occur in the region where the steel sheet base material is exposed. Red rust deteriorates the appearance of the processed product.

[0004] As a method for improving the rust prevention ability of the end of the processed product, for example, the methods proposed in Patent Documents 1, 2, etc. below can be cited. In Patent Document 1, in a Zn-based plated steel sheet with a thickness of 2 mm or less, punching is performed using a die having a curvature radius of 0.1 to 0.5 times the thickness of the Zn-based plated steel sheet at the shoulder of the punch or die, so that the shear cross-sectional ratio of the punched end face after punching is 90% or more, and a method for making the zinc coating rate of the shear cross-section 50% or more has been proposed.

[0005] In Patent Document 2, a method for obtaining a product having corrosion resistance on the end face by performing semi-punching with a negative clearance of 60 to 95% of the thickness and shearing from the opposite side of the semi-punching by flat pressing has been proposed.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0007] In the method proposed in Patent Document 1, the target is a steel plate with a thickness of 2 mm or less. When a steel plate with a thickness exceeding 2 mm is used as a material, the zinc coating rate of the cross-sectional area becomes insufficient, and there is a possibility that it becomes difficult to suppress the occurrence of red rust. Also, it is difficult to apply to a drawn product in which thickening occurs at the flange end such as a motor case.

[0008] Also, in the method proposed in Patent Document 2, semi-punching is performed with a negative clearance, and shearing is performed by flat pressing from the opposite side of the semi-punching. Therefore, a fracture surface occurs at the intermediate position of the end portion in the plate thickness direction, and bearded burrs are likely to occur during flat pressing.

[0009] The present invention has been made to solve the above problems, and one of its purposes is to provide a processed product and a manufacturing method thereof that can suppress the red rust generation area and suppress the remaining burrs even when a plated steel plate with a thickness exceeding 2.0 mm is used as a material.

Means for Solving the Problems

[0010] In one embodiment, the processed product according to the present invention is a processed product made of a plated steel sheet having a plating layer on the surface and having a cut end along the thickness direction of the processed product. The cut end has, in the thickness direction of the cut end from the upper surface side to the lower surface side, a sag, a shear surface, a fracture surface, and a coining surface in this order. The length W3 of the fracture surface between the shear surface and the coining surface in the thickness direction of the cut end is more than 0 mm and 0.5 mm or less. The ratio L1 / W2 of the length L1 of the coining surface in the thickness direction to the distance W2 between the lower surface of the cut end and the upper end of the fracture surface is 0.95 or less.

[0011] In another embodiment, the processed product according to the present invention is a processed product made of a plated steel sheet having a plating layer on the surface and having a cut end along the thickness direction of the processed product. The cut end has, in the thickness direction of the cut end from the upper surface side to the lower surface side, a sag, a shear surface, a fracture surface, and a coining surface in this order. The length W3 of the fracture surface between the shear surface and the coining surface in the thickness direction of the cut end is more than 0 mm and 0.5 mm or less. The ratio L1 / t1 of the length L1 of the coining surface in the thickness direction to the thickness t1 of the cut end is 0.38 or less.

[0012] In one embodiment, the method for manufacturing a processed product according to the present invention is a method for manufacturing a processed product having a cut end along the thickness direction of the processed product, using a plated steel sheet having a plating layer on the surface as a material. The method includes a cutting step of obtaining a second element by performing a single cutting process on a cut portion of a first element formed from the material using a die and a punch. The cut portion is a flat portion including a portion that becomes a cut end. The cut end of the second element has a sag, a shear surface, and a fracture surface in order in the thickness direction of the cut end of the second element. The method also includes a coining step of performing a coining process by pressing a corner portion on the fracture surface side of the cut end of the second element against a pad to obtain a processed product having a coining surface formed at the corner portion. In the coining step, the processing amount is adjusted so that the ratio L1 / W1 of the length L1 of the coining surface in the thickness direction to the length W1 of the fracture surface of the second element in the thickness direction is 1.0 or less. The cut end of the processed product has a sag, a shear surface, a fracture surface, and a coining surface in order in the thickness direction of the cut end of the processed product from the upper surface side to the lower surface side. The length W3 of the fracture surface between the shear surface and the coining surface in the thickness direction of the cut end of the processed product is greater than 0 mm and less than or equal to 0.5 mm.

[0013] In another embodiment, the method for manufacturing a processed product according to the present invention is a method for manufacturing a processed product having a cut end along the plate thickness direction of the processed product, using a plated steel sheet having a plating layer on the surface as a raw material. The method includes a cutting step of performing a single cutting process on a cut portion of a first element formed from the raw material using a die and a punch to obtain a second element. The cut portion is a flat plate portion including a portion that becomes the cut end. The cut end of the second element has a sag, a shear cross-section, and a fracture cross-section in order in the plate thickness direction of the cut end of the second element. The method also includes a coining step of pressing a corner portion on the fracture cross-section side of the cut end of the second element against a pad to obtain a processed product having a coining surface formed at the corner portion. In the coining step, the coining process is performed by adjusting the processing amount so that the ratio L1 / t1 of the length L1 of the coining surface in the plate thickness direction to the plate thickness t1 of the cut end of the processed product is 0.38 or less. The cut end of the processed product has a sag, a shear cross-section, a fracture cross-section, and a coining surface in order in the plate thickness direction of the cut end of the processed product from the upper surface side to the lower surface side. The length W3 of the fracture cross-section between the shear cross-section and the coining surface in the plate thickness direction of the cut end of the processed product is greater than 0 mm and 0.5 mm or less.

Effects of the Invention

[0014] According to an embodiment of the processed product and its manufacturing method of the present invention, even when a plated steel sheet with a thickness exceeding 2.0 mm is used as a raw material, the rust generation area can be suppressed, and the remaining burrs can be suppressed.

Brief Description of the Drawings

[0015]

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Embodiments for Carrying Out the Invention

[0016] Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. The present invention is not limited to each embodiment, and components can be modified and embodied without departing from the gist thereof. Further, various inventions can be formed by appropriately combining a plurality of components disclosed in each embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, components of different embodiments may be appropriately combined.

[0017] <Regarding the processed product> FIG. 1 is a perspective view showing an example of a processed product 1 manufactured by the processed product manufacturing method according to an embodiment of the present invention. The processed product 1 shown in FIG. 1 is a motor case made of a plated steel sheet having a plating layer on its surface. The motor case shown in FIG. 1 can be formed by subjecting a flat plated steel sheet to a forming process such as drawing.

[0018] As shown in FIG. 1, the processed product 1 according to the present embodiment has a body portion 10, a protrusion portion 11, and a flange portion 12.

[0019] The body portion 10 has a hollow cylindrical side wall 101 and a top wall 103 formed so as to cover one end of the side wall 101. The top wall 103 may be called by other names such as a bottom wall depending on the orientation in which the processed product 1 is used. In the body portion 10 of the processed product 1 shown in FIG. 1, the cross-sectional shape in the XY plane (the cross-sectional shape of the body portion 10) is a perfect circle, but the present invention is not limited to such an example. The cross-sectional shape of the body portion 10 in the XY plane may be other shapes such as an elliptical shape or a polygonal shape.

[0020] The protrusion portion 11 is a protrusion projecting outward in the central axis direction (Z direction) of the body portion 10 from the top wall 103. Note that the protrusion portion 11 does not necessarily have to be formed, and the top wall 103 may be flat.

[0021] The flange portion 12 is a plate portion that extends radially outward (in the X and Y directions) from the end of the barrel portion 10 (i.e., the other end of the side wall 101) of the barrel portion 10. The shape of the flange portion 12 is arbitrary. The flange portion 12 according to the present embodiment extends radially of the barrel portion 10 over the entire circumferential direction of the barrel portion 10. A plurality of screw holes 121 are provided in the flange portion 12 at intervals in the circumferential direction of the barrel portion 10. Screws 123 are inserted into the screw holes 121. The processed product 1 can be fixed to an attachment target, such as a vehicle body, by being fastened to the attachment target using the screws 123.

[0022] The flange portion 12 according to the present embodiment is formed by cutting a flange portion element (the flange portion element 20 in FIG. 7) having an outer diameter larger than the outer diameter of the flange portion 12 finally formed on the processed product 1. That is, the processed product 1 according to the present embodiment has a cut end portion 13 on the outer periphery of the flange portion 12.

[0023] The cutting process includes processes such as cutting, punching, and drilling. Cutting is a process of cutting a cutting target along a predetermined straight line or curve. Punching is a process of punching a product from a cutting target. Drilling is a process of punching out a non-product portion from a cutting target to obtain a product having an opening. The flange portion 12 shown in FIG. 1 can be obtained by punching from a flange portion element.

[0024] As the plated steel sheet, a plated steel sheet having various plating layers can be used. Although various steel sheets can be used as the plated steel sheet, it is preferable to use a Zn-based plated steel sheet. Zn-based plating includes Zn plating, Zn-Al-based alloy plating, Zn-Al-Mg-based alloy plating, and Zn-Al-Mg-Si-based alloy plating. Here, it is preferable that the alloy plating contains 80% by mass or more of Zn, and more preferably 90% by mass or more of Zn, based on the total number of moles of the plating.

[0025] The base steel sheet of the plated steel sheet is arbitrary, and can be, for example, extra low carbon steel or the like.

[0026] The plating adhesion amount on the plated steel sheet is preferably 30 g / m 2 as the lower limit, and more preferably 45 g / m 2 as the lower limit may also be used. Further, the plating adhesion amount on the plated steel sheet is preferably 450 g / m 2 as the upper limit, and more preferably 190 g / m 2 as the upper limit may also be used. In particular, by setting the plating adhesion amount to 45 g / m 2 or more, the plating metal is likely to wrap around the shear cross-section (shear cross-section 13d in FIG. 2) of the cut end 13, so that the corrosion resistance after cutting can be improved.

[0027] The plate thickness of the plated steel sheet (the plate thickness of the base steel sheet + the thickness of the plating layer) is arbitrary, and it may be 2.0 mm or less, or may be more than 2.0 mm. The plate thickness of the plated steel sheet can 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, etc.

[0028] <Regarding the cut end of the processed product> Next, the cut end 13 of the processed product 1 will be described with reference to FIGS. 2 to 6. FIGS. 2 to 4 are explanatory views showing the first to third modes of the cut end 13 in the region A of FIG. 1. The left side of FIGS. 2 to 4 is a cross-sectional view of the cut end 13 in the ZX plane of FIG. 1, and the right side of FIGS. 2 to 4 is a front view of the cut end 13 when viewed along the Y direction of FIG. 1. FIG. 5 is a detailed view of the cross-section of the cut end 13 in FIG. 2. FIG. 6 is a graph showing an example of the relationship between sag Z and sag X. In FIGS. 2 to 5, it is assumed that the plate thickness direction T of the cut end 13 is the same as the central axis direction (Z direction) of the processed product 1 shown in FIG. 1. Further, in FIGS. 2 to 4, the description of the plating layer 13h shown in FIG. 5 is omitted.

[0029] As particularly shown in FIG. 2, the cut end 13 has a sag 13c, a shear cross-section 13d, a fracture cross-section 13e, and a coining surface 13f in order in the plate thickness direction T of the cut end 13 from the upper surface 13a side to the lower surface 13b side.

[0030] The upper surface 13a is the surface (the surface to be pressed) on the side where the cutting edge of the cutting die (die 4 in FIG. 8) is pressed during the cutting process of the flange part element. The lower surface 13b is the surface on the side where the cutting edge of the cutting die exits during the cutting process of the flange part element.

[0031] The sag 13c is the portion where the surface of the flange part element 20 (plated steel sheet) is deformed due to the tensile force acting on the surface when the cutting edge of the cutting die is pressed against the flange part element. The sag 13c typically appears as a smooth surface with curvature at the cutting end 13.

[0032] In this specification, the dimension of the sag 13c in the plate thickness direction T of the cutting end 13 is referred to as "sag Z", and the dimension of the sag 13c in the plane direction orthogonal to the plate thickness direction T is referred to as "sag X". In particular, the "sag Z" at the cutting end 13 of the processed product 1 may be referred to as "sag Z2", and the "sag X" at the cutting end 13 of the processed product 1 may be referred to as "sag X2". On the other hand, the "sag Z" at the cutting end 13 of the second element 3 described later may be referred to as "sag Z1", and the "sag X" at the cutting end 13 of the second element 3 may be referred to as "sag X1".

[0033] The shear surface 13d is the surface where the flange part element is sheared by the cutting edge of the cutting die. The shear surface 13d is adjacent to the sag 13c in the plate thickness direction T of the cutting end 13. The shear surface 13d typically appears as a smooth surface at the cutting end 13. Since the shear surface 13d is generated by rubbing against the side surface of the cutting die when the compression (pressing) force is applied after the cutting die contacts the workpiece and bites into the workpiece, the shear surface 13d may exhibit a metallic luster. Fine streak-like sliding scratches may be observed on the shear surface 13d in the plate thickness direction T.

[0034] The fracture surface 13e is the surface where the cracks generated in the flange part element from the cutting edge of the cutting die meet and break. The fracture surface 13e is adjacent to the shear surface 13d in the plate thickness direction T of the flange part 12. The fracture surface 13e typically appears as a rough surface without luster at the cutting end 13. The fracture surface may have an inclination corresponding to the clearance of the cutting die.

[0035] The coining surface 13f is a surface where the corner 13i (see FIG. 7) on the lower surface 13b side of the cut end 13 is pressed or compressed by the coining process described later. The coining surface 13f of the present embodiment is a C surface (a surface subjected to chamfering). However, the coining surface 13f may be other pressed or compressed surfaces such as an R surface (a surface subjected to rounding). Typically, the coining surface 13f appears on the cut end 13 as a smooth surface where the unevenness of the fracture surface is flattened.

[0036] In the cut end 13, as a method for specifying the sag 13c, the shear surface 13d, the fracture surface 13e, and the coining surface 13f (a method for measuring their respective lengths), for example, there is a method of observing and measuring the shape profile of the cut end 13 from the appearance using a microscope or a tracer based on the above characteristics.

[0037] As described above, the fracture surface 13e is generated as a result of the cracks generated in the flange part element meeting and is a rough new surface. In the fracture surface 13e, the metal components of the steel base are exposed. Therefore, the fracture surface 13e is more likely to rust than the other surfaces of the cut end 13. On the other hand, the coining surface 13f is a pressed or compressed smooth surface and is less likely to rust compared to the rough fracture surface 13e. It is considered that this is because moisture is less likely to stay on the coining surface 13f due to the smooth surface roughness. Similarly, since the shear surface 13d is also a smooth surface, it is less likely to rust compared to the fracture surface 13e.

[0038] The inventors conducted experiments by varying the conditions of cutting and coining processes within various ranges, and investigated the occurrence status of rust on various cut ends 13. As a result, (1) when the length W3 of the fracture surface 13e between the shear surface 13d and the coining surface 13f in the plate thickness direction T of the cut end 13 (hereinafter also referred to as "fracture surface length W3") is more than 0 mm and 0.5 mm or less, even when using a plated steel sheet with a plate thickness of more than 2.0 mm as a material, the rust generation area can be suppressed. Even if rust occurs on the fracture surface 13e, it is not noticeable and can be judged not to be a practical problem. The fracture surface length W3 is preferably 0.3 mm or less, and more preferably 0.2 mm or less. Further, after the cutting process, burrs are formed following the fracture surface 13e. By forming the coining surface 13f, the burrs can be crushed and the remaining burrs can be suppressed.

[0039] Here, in the coining process when forming the coining surface 13f, a pressing or compressive force acts on the cut end 13 from the lower surface 13b side to the upper surface 13a side of the cut end 13, and the sag 13c, shear surface 13d, and fracture surface 13e may be pushed up within the cut end 13. Depending on the processing amount of the coining process, the sag 13c of the cut end 13 may take the form shown in FIG. 3 or FIG. 4 instead of the form shown in FIG. 2.

[0040] FIG. 3 shows a mode in which the boundary position 13g between the sag 13c and the shear surface 13d is pushed up to the same height position as the upper surface 13a by the coining process. FIG. 4 shows a mode in which 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 by the coining process. In either mode of FIG. 3 and FIG. 4, following the smooth upper surface 13a of the cut end 13, a deformed surface corresponding to the sag 13c remains. The deformed surface may bulge upward from the smooth upper surface 13a. In this specification, such a deformed surface is also treated as the sag 13c. In particular, the sag 13c as shown in FIG. 4 may also be referred to as a convex sag 13c upward.

[0041] In the case of the downward convex sag 13c shown in FIG. 4, that is, when the boundary position 13g between the sag 13c and the shear cross section 13d is pushed up to a position higher than the upper surface 13a, if the amount of pushing up of the boundary position 13g is too large, problems such as the stability of the screw 123 (see FIG. 1) being impaired due to excessive deformation of the cut end 13 may occur.

[0042] As a result of experiments in which the conditions of the cutting process and the coining process were varied within various ranges as described above, the inventors found that (2) by having the ratio L1 / W2 of the length L1 of the coining surface 13f in the plate thickness direction T to the distance W2 between the lower surface 13b of the cut end 13 and the upper end of the fracture surface 13e be 0.95 or less, it is possible to suppress the occurrence of problems due to excessive deformation of the cut end 13. The ratio L1 / W2 is preferably 0.85 or less. Thereby, excessive deformation of the cut end 13 can be more reliably suppressed.

[0043] Further, as a result of examining the experiments from another perspective, the inventors found that (3) by having the ratio L1 / t1 of the length L1 of the coining surface 13f in the plate thickness direction T to the plate thickness t1 of the cut end be 0.38 or less, it is also possible to suppress the occurrence of problems due to excessive deformation of the cut end 13. The ratio L1 / t1 is preferably 0.32 or less. Thereby, excessive deformation of the cut end 13 can be more reliably suppressed.

[0044] The numerical ranges of the ratio L1 / W2 and the ratio L1 / t1 may satisfy only one of them or both. Both the ratio L1 / W2 and the ratio L1 / t1 can be understood as indices corresponding to the amount of coining during the manufacture of the processed product 1.

[0045] Incidentally, the value obtained by adding "the length W3 of the fracture surface 13e between the shear cross-section 13d and the coining surface 13f in the plate thickness direction T of the cutting end 13" to "the length L1 of the coining surface 13f" can be "the distance W2 between the lower surface 13b of the cutting end 13 and the upper end of the fracture surface 13e" (W2 = L1 + W3). The plate thickness t1 of the cutting end 13 of the processed product 1 is equal to the plate thickness of the flange portion 12 of the processed product 1. The plate thickness t1 of the cutting end 13 may be the distance between the upper surface 13a and the lower surface 13b of the cutting end 13 at a position not affected by the sag 13c and the coining surface 13f.

[0046] Also, it is preferable that the ratio Z2 / t1 of the length Z2 of the sag 13c in the plate thickness direction T from the upper surface 13a of the cutting end 13 toward the lower surface 13b of the cutting end 13 to the plate thickness t1 of the cutting end 13 is -0.1 or more and 0.25 or less. By the ratio Z2 / t1 being -0.1 or more, it is possible to avoid the upwardly convex sag 13c from protruding excessively from the upper surface 13a, and it is possible to suppress the occurrence of problems due to excessive deformation of the cutting end 13. By the ratio Z2 / t1 being 0.25 or less, it is possible to avoid the sag X (the dimension of the sag 13c in the plane direction orthogonal to the plate thickness direction T) from becoming too large. The ratio Z2 / t1 is more preferably 0 or more and 0.1 or less. Thereby, the shape of the cutting end 13 can be made into a more preferable state. The ratio Z2 / t1 may be -0.10 or more and less than 0, or 0.1 or more and 0.25 or less.

[0047] Incidentally, it is known that the sag Z and the sag X have a correlation with each other. FIG. 6 shows an example of the relationship between the sag Z and the sag X of the cutting end when punching is performed in one step. FIG. 6 shows the relationship between the sag Z and the sag X of the cutting end of the product when a radius of curvature of 0.01 to 0.30 in terms of the plate thickness ratio of the flange portion element is given to the cutting die blade edge pushed into the flange portion element, and the clearance of the cutting die is set to 0.01 to 0.20 times the plate thickness for punching. As shown in FIG. 6, when punching is performed in one step, the sag X appearing in the plane direction becomes about 3 to 4 times as large as the sag Z in the plate thickness direction. This correlation is before the coining process, but it also affects after the coining process.

[0048] When measuring the length Z2 of the drip 13c, with the height position of the upper surface 13a of the cut end 13 as the reference position (zero point), the length to a position below the upper surface 13a is defined as a positive length, and the length to a position above the upper surface 13a is defined as a negative length. The reference position shall be the height position of the upper surface 13a of the cut end 13 at a position not affected by the drip 13c and the coining surface 13f (a position sufficiently far from the outer edge of the cut end 13).

[0049] For example, it is possible to scan the measurement points of the height position on the surface of the cut end 13 from a position not affected by the drip 13c and the coining surface 13f toward the outer edge of the cut end 13. When the boundary position 13g is at a position lower than the upper surface 13a as in the first aspect shown in FIG. 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 crossing the boundary position 13g. When the boundary position 13g is at the same height position as the upper surface 13a as in the second aspect shown in FIG. 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 crossing the boundary position 13g. When the boundary position 13g is at a position higher than the upper surface 13a as in the third aspect shown in FIG. 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 crossing the boundary position 13g. The length Z2 of the drip 13c can be the length in the plate thickness direction T between the height position immediately before the height position of the surface of the cut end 13 takes a discontinuous value and the reference position. The height position immediately before the height position of the surface of the cut end 13 takes a discontinuous value can be the height position of the boundary position 13g. As a method for measuring the length Z2 of the drip 13c, for example, there is a method of observing and measuring the shape profile of the cut end 13 with a tracer or the like.

[0050] As shown in Fig. 5, in the processed product according to this embodiment, the cut end 13 is formed such that the plating layer 13h wraps around from the upper surface 13a of the cut end 13 to the chamfered surface 13d. When the cutting die blade bites into the flange part body, the plating layer 13h is stretched by the cutting die and wraps around to the chamfered surface 13d. Due to the wrapping of this plating layer 13h, at least a part of the chamfered surface 13d is covered by the plating layer 13h. In the part of the chamfered surface 13d covered by the plating layer 13h, the generation of red rust can be further suppressed.

[0051] Also, in the processed product according to this embodiment, the cut end 13 is formed such that the plating layer 13h wraps around from the lower surface 13b of the cut end 13 to the coining surface 13f. When the coining process is performed, the plating layer 13h on the lower surface 13b is pressed or compressed together with the part constituting the coining surface 13f and wraps around to the coining surface 13f. Due to the wrapping of this plating layer 13h, at least a part of the coining surface 13f is covered by the plating layer 13h. In the part of the coining surface 13f covered by the plating layer 13h, the generation of red rust can be further suppressed.

[0052] At this time, the difference W2 - L2 between the distance W2 between the lower surface 13b of the cut end 13 and the upper end of the fracture surface 13e in the plate thickness direction T and the distance L2 between the upper end of the plating layer 13h from the lower surface 13b in the plate thickness direction is preferably 1.4 mm or less. The difference W2 - L2 corresponds to the length in the plate thickness direction T of the region not covered by the plating layer 13h. By the difference W2 - L2 being 1.4 mm or less, the generation of red rust can be more reliably suppressed. However, since the chamfered surface 13d and the coining surface 13f are smooth surfaces, even in the part not covered by the plating layer 13h, the generation of red rust can be suppressed compared to the rough fracture surface 13e.

[0053] Also, the distance W2 between the lower surface 13b of the cut end 13 and the upper end of the fracture surface 13e is preferably 1.6 mm or less. By the distance W2 being 1.6 mm or less, the generation of red rust can be more reliably suppressed.

[0054] <Method for manufacturing a processed product> Next, FIG. 7 is an explanatory diagram showing a method for manufacturing a processed product according to an embodiment of the present invention. As shown in FIG. 7, the method for manufacturing a processed product according to the present embodiment includes a preparation step, a cutting step, and a coining step.

[0055] The preparation step is a step of preparing the first blank 2. The first blank 2 can be obtained by subjecting a flat-plate-shaped plated steel sheet to a forming process such as drawing. That is, the first blank 2 uses a plated steel sheet as a material, similar to the processed product 1. The first blank 2 has a flange portion element 20 that is wider than the flange portion 12 shown in FIG. 1. The outer shape of the flange portion element 20 when viewed in a plane may be circular or non-circular. Regarding the portion other than the flange portion element 20, the first blank 2 may have the same shape as the processed product 1. Note that the preparation step may not involve a forming process on the plated steel sheet. A blank processed by a third party by some method may be obtained. The flange portion element 20 of the present embodiment constitutes a flat-plate-shaped portion to be cut including a portion that becomes the cut end portion 13.

[0056] The cutting step is a step of performing a single cutting process on the flange portion element 20 (the portion to be cut) of the first blank 2 to obtain a second blank 3. The second blank 3 is an intermediate member for manufacturing the processed product 1, and the processed product 1 can be obtained by further processing the second blank 3. The single cutting process is a process of cutting off a removed portion 20a from the flange portion element 20 by a single process using a die 4 and a punch 5 described later, rather than cutting the flange portion element 20 through a plurality of processes such as half-cutting and finish-cutting. The flange portion element 20 of the second blank 3 has a cut end portion 13. The cut end portion 13 of the second blank 3 has a corner portion 13i on the lower surface 13b side. The corner portion 13i may have burrs.

[0057] The coining process is a process of subjecting the cut end 13 of the second blank 3 obtained in the cutting process to coining to obtain a processed product. As will be described later with reference to the drawings, the coining process in this embodiment is a process of pressing the corner 13i of the cut end 13 of the second blank 3 against the pad 7 to form a coining surface 13f on the corner 13i. The coining surface 13f is a surface where the corner 13i is crushed. In the method for manufacturing a processed product according to the embodiment, by forming the coining surface 13f on the corner 13i of the flange portion blank 20 of the second blank 3, the processed product 1 having the flange portion 12 is obtained. The screw hole 121 of the processed product 1 shown in FIG. 1 may be formed in the flange portion blank 20 at the stage of the first blank 2 or the second blank 3, or may be formed in the flange portion 12 after the coining process.

[0058] <Die used in the cutting process> Next, FIG. 8 is an explanatory view showing the die 4 and the punch 5 used in the cutting process of FIG. 7. The upper side of FIG. 8 shows the state immediately before the cutting process, and the lower side of FIG. 8 shows the state immediately after the cutting process.

[0059] Regarding the mold used to obtain the processed product 1, for the sake of convenience, the mold on the pushing side is referred to as die 4, and the mold on the side to be pushed is referred to as punch 5. The mold on the pushing side may be located above or below the base body. Even when it moves in the horizontal direction, the mold on the pushing side is referred to as die 4, and the mold on the side to be pushed is referred to as punch 5. For example, the processed product 1 shown in Fig. 2 is cut with the upper mold as the mold on the pushing side. When the lower mold is the mold on the pushing side, that is, when the lower mold is die 4, the cut end 13 of the processed product 1, contrary to Fig. 2, has a sag 13c located at the lowermost part of the cut end 13, and a sheared surface 13d, a fractured surface 13e, and a coining surface 13f are formed above it. When it is unclear whether the upper or lower (or left or right) mold is die 4 or punch 5, after actually performing the cutting, observe the cut end 13, and the mold that presses the surface on the side where the sag 13c is located is referred to as die 4, and the mold that presses the surface on the opposite side is referred to as punch 5. In any case, as described above, the upper surface 13a of the cut end 13 is defined as the surface on the side where the cutting edge of die 4 is pushed in during the cutting process of the flange part base body 20, that is, the surface on the side where the sag 13c is located. Also, the lower surface 13b of the cut end 13 is defined as the surface on the side where the cutting edge of die 4 exits during the cutting process of the flange part base body 20.

[0060] As shown in Fig. 8, in the cutting process of the processed product manufacturing method according to this embodiment, the flange part base body 20 of the first base body 2 is cut using die 4 and punch 5. Fig. 8 shows, as an aspect of the cutting process, an aspect in which a removed portion 20a is punched out by die 4 from the flange part base body 20 of the first base body 2 held by punch 5 and a plate presser 6.

[0061] The cutting edge of the die 4 is preferably an R shape having a predetermined radius of curvature R shown in Fig. 8. Generally, increasing the radius of curvature R of the cutting edge of the die 4 can reduce the ratio of the fracture surface to the entire cutting surface. The cutting edge of the punch 5 is preferably a non-rounded rectangular shape as shown in Fig. 8. At this time, the cutting edge of the punch 5 may have a radius of curvature of less than 0.25 mm, less than 0.15 mm, less than 0.10 mm, or less than 0.05 mm. Alternatively, the radius of curvature of the cutting edge of the punch 5 may be less than 0.1 times the plate thickness t1 of the flange part 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 required.

[0062] A predetermined clearance C 4-5 [mm] is provided between the die 4 and the punch 5. The clearance C 4-5 in the cutting step of the processed product manufacturing method according to the present embodiment 4-5 is a positive clearance. C

[0063] <Cutting end of the second element> Next, the cutting end 13 of the second element 3 will be described with reference to Figs. 9 and 10. Fig. 9 is an explanatory diagram showing the cutting end 13 of the second element 3 obtained in the cutting step of Fig. 8. The left side of Fig. 9 is a cross-sectional view of the cutting end 13 of the second element 3 in the ZX plane of Fig. 1, and the right side of Fig. 9 is a front view of the cutting end 13 of the second element 3 when viewed along the Y direction of Fig. 1. Fig. 10 is a detailed view of the cross-sectional view of the cutting end 13 of the second element 3 in Fig. 9.

[0064] As shown in FIGS. 9 and 10, the cut end 13 of the second element 3 cut by the die 4 and the punch 5 has a sag 13c, a shear surface 13d, a fracture surface 13e, and a burr 13k in the plate thickness direction T of the cut end 13 from the upper surface 13a side toward the lower surface 13b side.

[0065] Regarding the sag 13c, the shear surface 13d, and the fracture surface 13e of the second element 3, they are the same as those of the cut end 13 of the processed product 1 described with reference to FIG. 2.

[0066] However, the cut end 13 of the second element 3 has not been subjected to coining, and compared with the sag 13c, the shear surface 13d, and the fracture surface 13e of the processed product 1, the sag 13c, the shear surface 13d, and the fracture surface 13e of the second element 3 are in a state of being lowered overall toward the lower surface 13b side. The boundary position 13g between the sag 13c and the shear surface 13d of the second element 3 is located below the upper surface 13a and does not reach the same height as the upper surface 13a as shown in FIG. 3 or a position higher than the upper surface 13a as shown in FIG. 4. The length W1 of the fracture surface 13e of the second element 3 in the plate thickness direction T is longer than the length W3 of the fracture surface 13e between the shear surface 13d and the coining surface 13f of the processed product 1 (see FIG. 2 etc.). This is because the fracture surface 13e of the second element 3 is crushed by subsequent coining to form the coining surface 13f. Also, the length W1 of the fracture surface 13e of the second element 3 in the plate thickness direction T may be shorter than the distance W2 between the lower surface 13b of the cut end 13 of the processed product 1 and the upper end of the fracture surface 13e (see FIG. 2 etc.). This is because the upper end of the fracture surface 13e of the second element 3 is pushed up by subsequent coining.

[0067] The burr 13k is a part where the flange part element 20 is stretched or torn when the fracture surface 13e is formed. The burr 13k is provided adjacent to the fracture surface 13e in the plate thickness direction T of the cut end 13.

[0068] The shapes or sizes of these sag 13c, shear surface 13d, fracture surface 13e, and burr 13k are related to the clearance C between the die 4 and the punch 5 4-5It is determined according to the cutting edge shapes of the die 4 and the punch 5 and the contour shape of the second base body 3. Depending on the cutting process, burr 13k may not be generated. That is, the cut end 13 of the second base body 3 may not have burr 13k. The corner 13i on the lower surface 13b side at the cut end 13 of the second base body 3 can be constituted by burr 13k or the lower end of the fracture surface 13e.

[0069] In the cutting process, it is preferable to perform the cutting process on the flange part body 20 (the part to be cut) of the first base body 2 so that the length W1 of the fracture surface 13e of the second base body 3 in the plate thickness direction T is 1.5 mm or less. By setting the length W1 of the fracture surface 13e of the second base body 3 to 1.5 mm or less, it is possible to avoid an excessive machining amount for the coining process for making the length W3 of the fracture surface 13e after the coining process exceed 0 mm and be 0.5 mm or less.

[0070] As described above, the larger the radius of curvature R of the die 4, the smaller the ratio of the fracture surface 13e in the entire cutting surface can be. Also, the clearance C 4-5 between the die 4 and the punch 5 can be made smaller within the range of the positive clearance to reduce the ratio of the fracture surface 13e in the entire cutting surface. Therefore, by adjusting the radius of curvature of the die 4 and the clearance between the die 4 and the punch 5 according to the plate thickness t, the length W1 of the fracture surface 13e of the second base body 3 can be made 1.5 mm or less.

[0071] Also, as particularly shown in FIG. 10, in the cutting process of the present embodiment, the cut end 13 is formed so that the plating layer 13h wraps around from the upper surface 13a to the shear surface 13d. The plating layer 13h wraps around to the shear surface 13d by being stretched by the die 4 when the cutting edge of the die 4 bites into the plated steel sheet. Due to the wrapping of this plating layer 13h, at least a part of the shear surface 13d is covered by the plating layer 13h, and the generation of red rust at the portion covered by the plating layer 13h can be suppressed. Also, when the plating layer 13h is a Zn-based plating layer, the sacrificial anticorrosion action of the Zn-based plating layer can also suppress the generation of red rust in the vicinity of the portion covered by the plating layer 13h.

[0072] Regarding the intrusion of the plating layer 13h, the larger the radius of curvature R given to the cutting edge tip of the die 4 that is pressed into the flange part element 20, the more prominent it becomes. This is because when the radius of curvature R given to the cutting edge tip is small, the material directly below the die 4 is inhibited from flowing from the cutting edge tip of the die 4 to the side surface. For this reason, the element of shear force becomes dominant, cracks are generated in the material from the cutting edge of the die 4 at an early stage, and a wider fracture surface 13e is generated. On the other hand, when the radius of curvature R given to the cutting edge tip is large, the material directly below the die 4 is promoted to flow from the cutting edge tip of the die 4 to the side surface. As a result, the element of shear force weakens, the generation of cracks from the cutting edge of the die 4 is delayed, and the shear surface 13d becomes longer. As the material directly below the die 4 flows from the cutting edge tip of the die 4 to the side surface, the plating layer 13h is thinly stretched and intrudes into the shear surface 13d.

[0073] As described above, the radius of curvature R given to the cutting edge tip of the die 4 should be adjusted according to the plate thickness t and the clearance C between the die 4 and the punch 5 so that the length W1 of the fracture surface 13e of the second element 3 is 1.5 mm or less. However, from the viewpoint of ensuring that the plating layer 13h surely intrudes into the shear surface 13d, it is preferably 0.08 times or more and 0.45 times or less of the plate thickness of the flange part element 20 before the cutting process. 4-5

[0074] <Die used in the coining process> Next, FIG. 11 is an explanatory view showing the pad 7 and the coining block 8 used in the coining process of FIG. 7. As shown in FIG. 11, in the coining process of the present embodiment, the cutting 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.

[0075] The vertical wall surface 70 is arranged to face and be substantially parallel to the shear surface 13d of the second element 3 when the cutting end 13 of the second element 3 is sandwiched between the pad 7 and the coining block 8. The vertical wall surface 70 is arranged to be parallel to the advancing and retreating direction of the coining block 8 (the Z direction in FIG. 11).

[0076] The bottom wall surface 71 is arranged to face the coining block 8 in the plate thickness direction T of the cutting end portion 13 with the second element body 3 interposed therebetween. The bottom wall surface 71 extends in a direction orthogonal to the vertical wall surface 70 below the vertical wall surface 70 (that is, on the side opposite to the coining block 8).

[0077] The pressing surface 72 is a surface that connects the vertical wall surface 70 and the bottom wall surface 71. The pressing surface 72 is provided to form a coining surface (the coining surface 13f in FIGS. 2 to 4) on the second element body 3, and is formed in a shape corresponding to the shape of the coining surface. For example, as shown in FIGS. 2 to 4, when the coining surface 13f is a flat chamfered surface (hereinafter referred to as a "C surface"), the pressing surface 72 may be a plane inclined with respect to the vertical wall surface 70 and the bottom wall surface 71. Further, for example, when the coining surface 13f is a curved chamfered surface (hereinafter referred to as an "R surface"), the pressing surface 72 may be a curved surface.

[0078] In the coining process, as shown in FIG. 11, with the cutting end portion 13 of the second element body 3 facing the vertical wall surface 70 of the pad 7, the second element body 3 is sandwiched in the plate thickness direction T by the coining block 8 and the bottom wall surface 71 of the pad 7. Then, the coining block 8 is pushed toward the bottom wall surface 71, and the second element body 3 is pushed down until the lower surface 13b of the second element body 3 contacts the bottom wall surface 71. Here, before the lower surface 13b of the second element body 3 contacts the bottom wall surface 71, the corner portion 13i or the burr 13k is pressed against the pressing surface 72. After the corner portion 13i or the burr 13k is pressed against the pressing surface 72, the coining block 8 is further pushed in, and the lower surface 13b of the second element body 3 contacts the bottom wall surface 71. In this process, the corner portion 13i or the burr 13k and the fracture surface 13e are crushed by the pressing surface 72, and the coining surface 13f in FIGS. 2 to 4 is formed. The cutting end portion 13 of the processed product 1 after the coining process is in a state as shown in the photograph of FIG. 12, for example.

[0079] The coining surface 13f is a smooth surface onto which the surface of the pressing surface 72 is transferred, and is less likely to generate red rust compared to the rough fracture surface 13e. It is considered that this is because moisture is less likely to stay on the coining surface 13f due to the smooth surface roughness. Also, it is considered that the fact that the plating layer 13h on the lower surface 13b side of the cut end 13 is thinly extended to the coining surface 13f is also a factor that makes it less likely for red rust to occur. By forming the coining surface 13f at the corner 13i on the lower surface 13b side, the fracture surface length W3 (see FIGS. 2 to 4) in the plate thickness direction T at the cut end 13 after coining is shorter than the fracture surface length W1 (see FIG. 9) in the plate thickness direction T at the cut end 13 of the second base body 3 before coining. That is, by the coining process, the area of the fracture surface 13e, which is a rough new surface, can be narrowed, and the red rust generation area can be suppressed. Also, by the coining process, the burr 13k can be crushed, and the remaining burr 13k in the processed product 1 can be more reliably suppressed.

[0080] The inventors conducted experiments in which the conditions of the cutting process and the coining process were changed within various ranges, and investigated the occurrence status of red rust at various cut ends 13. As a result, (1’) in the coining process, by adjusting the processing amount so that the length W3 (fracture surface length W3) of the fracture surface 13e between the shear surface 13d and the coining surface 13f in the plate thickness direction T of the cut end 13 of the processed product 1 is more than 0 mm and 0.5 mm or less, and performing the coining process, it was found that even when using a plated steel sheet with a plate thickness of more than 2.0 mm as a material, the red rust generation area can be suppressed. More specifically, it was found that if the length W3 of the fracture surface 13e is 0.5 mm or less, even if red rust occurs on the fracture surface 13e, it is not noticeable and can be judged not to be a problem in practice. The processing amount is the pressing amount of the corner 13i against the pressing surface 72. Also, the processing amount can be adjusted by adjusting conditions such as the position and angle of the pressing surface 72.

[0081] In addition, as a result of experiments in which the conditions of cutting and coining were varied within various ranges as described above, the inventors found that in the coining process, by adjusting the processing amount so that the ratio L1 / W1 of the length L1 of the coining surface 13f in the plate thickness direction T of the processed product 1 (see FIGS. 2 to 4) to the length W1 of the fracture surface 13e of the second element 3 in the plate thickness direction T (see FIG. 9) is 1.0 or less, it is possible to suppress the occurrence of defects due to excessive deformation of the cut end 13. The ratio L1 / W1 is preferably 0.9 or less. By these means, excessive deformation of the cut end 13 can be more reliably suppressed. The length L1 of the coining surface 13f can be estimated based on the processing amount of the coining process. The length W1 of the fracture surface 13e of the second element 3 is known during the coining process.

[0082] In addition, as a result of examining experiments from another perspective, the inventors found that in the coining process, by adjusting the processing amount so that the ratio L1 / t1 of the length L1 of the coining surface 13f in the plate thickness direction T of the processed product 1 to the plate thickness t1 of the cut end 13 of the processed product 1 (see FIGS. 2 to 4) is 0.38 or less, it is possible to suppress the occurrence of defects due to excessive deformation of the cut end 13. The ratio L1 / t1 is preferably 0.32 or less. By these means, excessive deformation of the cut end 13 can be more reliably suppressed. The length L1 of the coining surface 13f can be estimated based on the processing amount of the coining process. The plate thickness t1 of the cut end 13 of the processed product 1 may be the plate thickness t1 of the cut end 13 of the second element 3.

[0083] The numerical ranges of the ratio L1 / W1 and the ratio L1 / t1 may satisfy only one of them or both of them.

[0084] Also, in the coining process, it is preferable to perform coining by adjusting the processing amount so that the ratio Z2 / t1 of the length Z2 of the sag 13c in the plate thickness direction T from the upper surface 13a to the lower surface 13b of the cut end 13 of the workpiece 1 to the plate thickness t1 of the cut end 13 of the workpiece 1 is -0.1 or more and 0.25 or less. The length Z2 of the sag 13c can be estimated based on the processing amount of the coining process. The plate thickness t1 of the cut end 13 may be the plate thickness t1 of the cut end 13 of the second base body 3. When the ratio Z2 / t1 is -0.1 or more, it is possible to avoid the upwardly convex sag 13c from protruding excessively from the upper surface 13a, and it is possible to suppress the occurrence of problems due to excessive deformation of the cut end 13. When the ratio Z2 / t1 is 0.25 or less, it is possible to avoid the sag X (the dimension of the sag 13c in the plane direction orthogonal to the plate thickness direction T) from becoming too large. More preferably, the ratio Z2 / t1 is 0 or more and 0.1 or less. Thereby, the shape of the cut end 13 can be made into a more preferable state. The ratio Z2 / t1 may be -0.10 or more and less than 0, or 0.1 or more and 0.25 or less.

[0085] Also, as described above, in the coining process, the plating layer 13h wraps around from the lower surface 13b of the cutting end 13 to the coining surface 13f. In the coining process, it is preferable to adjust the processing amount so that the difference W1 - L2 between the length W1 of the fracture surface 13e of the second element 3 in the plate thickness direction T and the wrapping length L2 of the plating layer 13h from the lower surface 13b of the cutting end 13 in the plate thickness direction T (see FIG. 5) is 1.25 mm or less, and it is more preferable to adjust the processing amount so that it is 1.0 mm or less and perform the coining process. The length W1 of the fracture surface 13e of the second element 3 is known during the coining process. The wrapping length L2 of the plating layer 13h from the lower surface 13b of the cutting end 13 can be estimated based on the processing amount of the coining process. The difference W1 - L2 predicts the extent of the area not covered by the plating layer 13h. By the difference W1 - L2 being 1.25 mm or less, the occurrence of red rust can be more reliably suppressed, and by the difference W1 - L2 being 1.0 mm or less, the occurrence of red rust can be even more reliably suppressed.

[0086] <Processed product example> In the above embodiment, the case where the processed product 1 is a motor case as shown in FIG. 1 has been described. However, the processed product 1 manufactured by the processed product manufacturing method according to the present embodiment may be any article made of a plated steel sheet and having a cutting end 13.

[0087] The processed product 1 may be, for example, an annular flat washer 900 as shown in FIG. 13. Also, the processed product 1 may be, for example, flat washers 910A, 910B, 910C having tooth portions 911 as shown in FIG. 14. Alternatively, the processed product 1 may be, for example, a corrugated annular disc spring 920 as shown in FIG. 15. The disc spring 920 in FIG. 15 can be manufactured by processing the flat washer 900 shown in FIG. 13 into a corrugated shape. Further, the processed product may be, for example, a disc spring 930 having a tooth portion 931 as shown in FIG. 16.

[0088] When the processed product 1 is various annular plate members as shown in FIGS. 13 to 16, the outer peripheral portion and the inner peripheral portion thereof become the cut end portions 13. By applying the processed product manufacturing method according to the above embodiment, at least one of the outer peripheral portion and the inner peripheral portion is set such that (1) the length W3 of the fracture surface 13e (hereinafter also referred to as "fracture surface length W3") between the shear cross section 13d and the coining surface 13f in the plate thickness direction T of the cut end portion 13 is more than 0 mm and 0.5 mm or less, and (2) the ratio L1 / W2 of the length L1 of the coining surface 13f in the plate thickness direction T to the distance W2 between the lower surface 13b of the cut end portion 13 and the upper end of the fracture surface 13e is 0.95 or less, and / or (3) the ratio L1 / t1 of the length L1 of the coining surface 13f in the plate thickness direction T to the plate thickness t1 of the cut end portion is 0.38 or less.

[0089] For example, in order to cover the shear cross sections of the inner peripheral surface and the outer peripheral surface of the flat washer 900 shown in FIG. 13 with a plating layer, processing may be performed using a cutting die as shown in FIGS. 17 and 18. FIG. 17 is a schematic diagram showing an example of a cutting die for processing the flat washer 900. FIG. 18 is a schematic diagram showing a state in which the blank 9 is punched by the cutting die of FIG. 17.

[0090] The cutting die shown in FIG. 17 is a die for manufacturing an annular processed product 90 such as the flat washer 900, and includes a hollow cylindrical die (hereinafter referred to as an "outer die") 61, a cylindrical die (hereinafter referred to as an "inner die") 63, and a hollow cylindrical punch 65 that supports a disk-shaped blank 9 (see FIG. 18). The outer die 61 and the inner die 63 and the punch 65 are provided to face each other, and the blank 9 is cut by pushing 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 processed product 90, and the outer diameter of the inner die 63 corresponds to the inner diameter of the processed product 90. The cutting edges of 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 curvature radius. On the other hand, the edges of the inner peripheral surface and the outer peripheral surface of the punch 65 do not have an R shape.

[0091] When the blank 9 is finish-cut by such a cutting die, as shown in Fig. 18, a portion 9a outside the outer peripheral surface 91 of the workpiece 90 is cut by the outer die 61, and a portion 9b inside the inner peripheral surface 92 of the workpiece 90 is cut by the inner die 63. Thereby, a workpiece 90 (flat washer 900) as shown in Fig. 13 is formed.

[0092] Furthermore, the workpiece 1 may be, for example, a disk-shaped plate 940 as shown in Fig. 19.

Example

[0093] Next, an example will be given. Samples of the second blank 3 and the workpiece 1 were created by the method shown in Fig. 7. As the plated steel sheet, a Zn-6%Al-3%Mg (mass ratio) alloy plated steel sheet with a plate thickness of 1.1 to 4 mm and a plating adhesion amount of 90 g / m 2 (one-sided) or 190 g / m 2 (one-sided) was used. The cutting process was performed using a round die (doughnut-shaped or annular die) with an inner diameter of φ85 mm and a round punch whose diameter was changed according to the clearance C 4-5 , and holding the flange portion blank 20 of the second blank 3 with a plate clamp. At this time, the shoulder portion of the die 4 was formed into an R shape having a predetermined radius of curvature.

[0094] For each sample, the length W1 of the fracture surface 13e after punching and the lengths W2 and W3 of the fracture surface 13e after coining were measured. These were measured at 30° intervals on the circumference of the end face of the processed product using a microscope, and the average of 12 measurement values was obtained. Also, for each sample, regarding the intrusion of the plating layer 13h around the coining surface 13f of the cut end 13, the length L2 by which the plating layer 13h intruded in the plate thickness direction T of the cut end 13 was measured from the cross section of the flange portion 12 of the processed product. For the measurement of the length L2 of the plating layer 13h at the cut end 13, an electron probe microanalyzer (EPMA-WDS) was used. It was determined that the plating layer 13h was present in a portion where the detection level of the Zn component was 3 times or more the background. The measurement targets were the second base body 3 obtained by the cutting process and the processed product 1 obtained by the coining process.

[0095] The burr 13k that causes scratches, electrical short circuits, etc. was evaluated. Samples with a burr 13k size less than 0.2 mm were evaluated as "〇", and samples with a size of 0.2 mm or more or samples with whisker-like burrs were evaluated as "×".

[0096] Also, the sag Z (Z2 for those with coining, Z1 for those without coining) after coining was evaluated. Those with Z2 / t1 (or Z1 / t1) of 0 or more and less than 0.1 were evaluated as "◎", those with Z2 / t1 (or Z1 / t1) of -0.1 or more and 0.25 or less (excluding those with the above-mentioned ◎ evaluation) were evaluated as "〇", and those with Z2 / t1 (or Z1 / t1) less than -0.1 or exceeding 0.25 were evaluated as "×".

[0097] Furthermore, the samples were subjected to an atmospheric exposure test outdoors, and the number of days until obvious red rust occurred on the cut end face was observed every 15 days.

[0098] The above results are shown in Table 1. Table 1 shows, for each sample, the plating steel sheet used, the punching conditions, the presence or absence of coining on the corner 13i of the cut end 13, and the dimensions of the coining surface 13f. Here, the radius of curvature (plate thickness ratio) of the die 4 is the value obtained by dividing the roundness provided on the shoulder of the die 4 by the plate thickness. Those without intentionally provided roundness are indicated as "<0.01" in this column. For those with the coining surface 13f as the R surface, the numerical value of dimension L1 is enclosed in "<>" for notation.

[0099] [Table 1]

[0100] As shown in Table 1, in Examples 1 to 21, the fracture surface length W3 after coining was 0.5 mm or less. The cut ends showed good corrosion resistance for 60 days or more until red rust occurred. Also, in Examples 1 to 21, there was no generation of burrs and the dimensions of the sag Z were also good.

[0101] In any of the examples, in the state of the processed product 1, the ratio L1 / W2 of the length L1 of the coining surface 13f in the plate thickness direction T to the distance W2 between the lower surface 13b of the cut end 13 and the upper end of the fracture surface 13e was 0.95 or less, and also (3) the ratio L1 / t1 of the length L1 of the coining surface 13f in the plate thickness direction T to the plate thickness t1 of the cut end was 0.38 or less. Also, in any of the examples, (2') the coining process was performed by adjusting the processing amount so that the ratio L1 / W1 of the length L1 of the coining surface 13f in the plate thickness direction T of the processed product 1 to the length W1 of the fracture surface 13e of the second element 3 in the plate thickness direction T (see FIG. 9) became 1.0 or less, and (3') the coining process was performed by adjusting the processing amount so that the ratio L1 / t1 of the length L1 of the coining surface 13f in the plate thickness direction T of the processed product 1 to the plate thickness t1 of the cut end 13 of the processed product 1 became 0.38 or less.

[0102] On the other hand, in Comparative Examples 1 to 12 where the corrosion resistance was evaluated only by punching, the fracture surface length W3 exceeded 0.5 mm, and the number of days until red rust occurred at the cut ends was less than 60 days, and the corrosion resistance was inferior compared to the examples of the present invention.

[0103] Comparative Examples 13 to 16 were subjected to coining from the fracture surface side with respect to the cut end after punching. However, since the C-plane dimension during coining was small, the fracture surface length (W3) after coining exceeded 0.5 mm. The number of days until red rust occurred on the cut end face was less than 60 days, and the corrosion resistance was inferior compared to the examples.

[0104] Comparative Examples 17 and 18 have a large fracture surface length W1 of 1.5 mm or more after punching, similar to Examples 10 and 21. In Examples 10 and 21, coining is performed by adjusting the processing amount as described above. However, in Comparative Examples 17 and 18, coining is performed such that the ratio L1 / W1 exceeds 1.0 and the ratio L1 / t1 exceeds 0.38. As a result, the ratio Z2 / t1 of the length Z2 of the sag 13c in the plate thickness direction T from the upper surface 13a to the lower surface 13b of the cut end 13 with respect to the plate thickness t1 of the cut end 13 is a large negative value of -0.11. In Comparative Examples 17 and 18, it was evaluated that there is a risk of problems due to excessive deformation of the cut end 13.

[0105] From the above results, in the cutting process where punching is continuously performed and then coining is performed from the opposite fracture surface side, it was confirmed that a cut end face with good corrosion resistance can be obtained by setting the fracture surface length W3 after coining to 0.5 mm or less. Also, the effectiveness of adjusting the processing amount of coining was confirmed.

[0106] As described above, the preferred embodiments of the present invention have been described in detail with reference to the accompanying drawings. However, the present invention is not limited to such examples. It is obvious that those having ordinary knowledge in the technical field to which the present invention pertains can conceive of various modification examples or correction examples within the scope of the technical idea described in the claims, and it is naturally understood that these also belong to the technical scope of the present invention.

Explanation of Reference Numerals

[0107] 1: Processed product 2: First element 3: Second body 4: Die 5: Punch 7: Pad 13: Cut end 13a: Upper surface 13b: Lower surface 13c: Sag 13d: Shear cross-section 13e: Fracture cross-section 13f: Coining surface 13h: Plating layer 13i: Corner

Claims

1. A processed product made of a plated steel sheet having a plating layer on its surface and having a cut end along the thickness direction of the processed product, wherein the cut end has a sag, a shear cross-section, a fracture cross-section, and a coining surface in order in the thickness direction of the cut end from the upper surface side to the lower surface side, the length W3 of the fracture cross-section between the shear cross-section and the coining surface in the thickness direction of the cut end is more than 0 mm and 0.5 mm or less, the ratio L1 / W2 of the length L1 of the coining surface in the thickness direction to the distance W2 between the lower surface of the cut end and the upper end of the fracture cross-section is 0.95 or less, Processed product.

2. The ratio L1 / t1 of the length L1 of the coining surface in the thickness direction to the thickness t1 of the cut end is 0.38 or less. The processed product according to claim 1.

3. A processed product made of a plated steel sheet having a plating layer on its surface and having a cut end along the thickness direction of the processed product, wherein the cut end has a sag, a shear cross-section, a fracture cross-section, and a coining surface in order in the thickness direction of the cut end from the upper surface side to the lower surface side, the length W3 of the fracture cross-section between the shear cross-section and the coining surface in the thickness direction of the cut end is more than 0 mm and 0.5 mm or less, the ratio L1 / t1 of the length L1 of the coining surface in the thickness direction to the thickness t1 of the cut end is 0.38 or less, Processed product.

4. The ratio Z2 / t1 of the length Z2 of the sag in the thickness direction from the upper surface of the cut end toward the lower surface of the cut end to the thickness t1 of the cut end is -0.1 or more and 0.25 or less. The processed product according to any one of claims 1 to 3.

5. The plating layer wraps around from the lower surface of the cut end to the coining surface, and the difference W2 - L2 between the distance W2 between the lower surface of the cut end and the upper end of the fracture cross-section in the thickness direction and the distance L2 between the upper end of the plating layer from the lower surface in the thickness direction is 1.4 mm or less. The processed product according to any one of claims 1 to 4.

6. The distance W2 between the lower surface of the cut end and the upper end of the fracture cross-section is 1.6 mm or less. The processed product according to any one of claims 1 to 5.

7. A processed product manufacturing method for manufacturing a processed product made of a plated steel sheet having a plating layer on its surface and having a cut end along the thickness direction of the processed product, A cutting step of obtaining a second element by performing a single cutting process on a cut portion of the first element formed from the material using a die and a punch, wherein the cut portion is a flat plate-like portion including a portion that becomes the cut end, and the cut end of the second element has a sag, a shear surface, and a fracture surface in order in the plate thickness direction of the cut end of the second element. A coining step of pressing a corner portion on the fracture surface side of the cut end of the second element against a pad to obtain a processed product having a coining surface formed at the corner portion, and adjusting the processing amount so that the ratio L1 / W1 of the length L1 of the coining surface in the plate thickness direction to the length W1 of the fracture surface of the second element in the plate thickness direction is 1.0 or less, and performing the coining process. including The cut end of the processed product has a sag, a shear surface, a fracture surface, and the coining surface in order in the plate thickness direction of the cut end of the processed product from the upper surface side to the lower surface side, and the length W3 of the fracture surface between the shear surface and the coining surface in the plate thickness direction of the cut end of the processed product is more than 0 mm and 0.5 mm or less. Processed product manufacturing method.

8. In the coining step, the coining process is performed by adjusting the processing amount so that the ratio L1 / t1 of the length L1 of the coining surface in the plate thickness direction to the plate thickness t1 of the cut end is 0.38 or less. The processed product manufacturing method according to claim 7.

9. A processed product manufacturing method for manufacturing a processed product having a cut end along the plate thickness direction of the processed product, using a plated steel sheet having a plating layer on the surface as a material. A cutting step of obtaining a second element by performing a single cutting process on a cut portion of the first element formed from the material using a die and a punch, wherein the cut portion is a flat plate-like portion including a portion that becomes the cut end, and the cut end of the second element has a sag, a shear surface, and a fracture surface in order in the plate thickness direction of the cut end of the second element. A coining step of pressing a corner portion on the fracture surface side of the cut end of the second element against a pad to obtain a processed product having a coining surface formed at the corner portion, and adjusting the processing amount so that the ratio L1 / t1 of the length L1 of the coining surface in the plate thickness direction to the plate thickness t1 of the cut end of the processed product is 0.38 or less, and performing the coining process. including The cut end of the processed product has a sag, a sheared cross-section, a fracture cross-section, and the coining surface in this order from the upper surface side toward the lower surface side in the plate thickness direction of the cut end of the processed product, and the length W3 of the fracture cross-section between the sheared cross-section and the coining surface in the plate thickness direction of the cut end of the processed product is more than 0 mm and 0.5 mm or less. Method for manufacturing a processed product.

10. In the coining step, the processing amount is adjusted so that the ratio Z2 / t1 of the length Z2 of the sag in the plate thickness direction from the upper surface of the cut end of the processed product toward the lower surface of the cut end to the plate thickness t1 of the cut end of the processed product is -0.1 or more and 0.25 or less, and coining is performed. The method for manufacturing a processed product according to any one of claims 7 to 9.

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