[0001]The present invention relates to a cutting method for cutting a workpiece, and a cut article which was cut and formed by the cutting method. 10 BACKGROUND ART [0002] Various kinds of surface-treated materials are produced according to the applications, such as a plated metal sheet for which the surface of a metallic material has been subjected to a plating treatment, or a painted metal sheet for which the surface 15 of a metallic material has been painted. For example, plated steel sheets which are excellent in corrosion resistance are utilized for building materials, automobiles, and household electrical appliances. [0003] Components which use a surface-treated material that was produced by 20 subjecting a workpiece to a surface treatment are manufactured, for example, by cutting the workpiece that was subjected to the surface treatment, and thereafter processing the cut workpiece. Cutting of a workpiece 5 can be performed, for example, by cutting the workpiece 5 using a shearing tool 10 as illustrated in Figure 35. The shearing tool 10 is composed of a die 11, a punch 12 and a blank holder 13. For example, in a state in 25 which one end of the workpiece 5 is restrained by the die 11 and the blank holder 13, the punch 12 which has been placed to have a clearance d with respect to the die 11 is moved relatively to the die 11 side to apply a shearing force to the workpiece 5. By this means, the workpiece 5 is cut. [0004] 30 The workpiece 5 which was subjected to a surface treatment that was cut using 2 the shearing tool 10 illustrated in Figure 35 has a cut end face as illustrated in Figure 36. The cut end face of the workpiece 5 is composed of a shear drop, a shear surface, and a fracture surface. The shear drop is a deformation caused by a tensile force acting on the top surface of the workpiece 5 when, with respect to the workpiece 5 in which the 5 surface of a metallic material 5a as the base material has been covered with a coating layer 5b, the punch 12 illustrated in Figure 35 is pushed down from the top surface side toward the bottom surface side of the workpiece 5. The shear surface is a smooth surface formed by movement of the punch 12 which sunk into the workpiece 5, and the fracture surface is a surface at which cracks that arose in the workpiece 5 served as 10 rupture starting points and the workpiece 5 ruptured. As illustrated in Figure 36, at the cut end face of the workpiece 5, although the coating layer 5b remains at the shear drop portion, almost none of the coating layer 5b remains at the shear surface, and the metallic material 5a is exposed at the fracture surface. [0005] 15 In this regard, at the cut end face of the workpiece 5, the corrosion resistance of the shear surface and the fracture surface at which the metallic material 5a is almost fully exposed is low, and there is a concern that red rust may occur. For example, sacrificial protection by a plated metal layer or chemical treatment are commonly employed as measures for preventing rust at the cut end face of a plated metal sheet in 20 which a plated metal layer is formed on the surface of a metallic material. For example, Patent Document 1 discloses that a cutting process is performed so that, within a range of 0.10 times or more of the sheet thickness in the sheet thickness direction, the size of a shear drop of a cut end face falls within a range of 0.45 times or more of the sheet thickness in the flat surface direction. A tensile force and a shearing force 25 applied to the metallic material are increased by such a cutting process, a plated metal layer coated on the surface of the base metal material is caused to go around to the cut end face, and at least one part of the shear surface of the cut end face is covered with the plated metal layer. The occurrence of red rust at the cut end face is suppressed by a sacrificial protection action of the plated metal layer that went around to the cut end 30 face. 3 [0006] Further, Patent Document 2 discloses a method in which a surface-treated steel sheet is cut with a rotary blade that is shifted upward and downward, and thereafter the end face is subjected to a processing using a forming roll. 5 [0007] In addition, Patent Document 3 discloses a laminated substrate cutting method in which a laminated substrate is transferred to and placed in a press tooling composed of an upper blade mold having an upper blade with a V-shaped front end cross-section, and a lower blade mold having a lower blade that has the same shape structure as the 10 upper blade and that faces the upper blade mold, and is cut by the upper blade and the lower blade when a moving operation is performed by the upper blade mold or the upper blade mold and the lower blade mold. [0008] Further, Patent Document 4 discloses a method for manufacturing an electric 15 contact in which an outer covering composed of a material having favorable weldability is adhered to a wire rod to form a linear contact material, and by shearing the contact material through the outer covering with a cutter that has a cutting edge having a wedge-shaped cross section whose top surface is inclined, the outer covering is plastically deformed and a coating of the material having favorable weldability is 20 formed on the shear surface of the wire rod, and the wire rod is joined to the contact base metal through the shear surface. A recess is provided partway along the slope of the top surface of the cutting edge. LIST OF PRIOR ART DOCUMENTS 25 PATENT DOCUMENT [0009] Patent Document 1: JP2017-87294A Patent Document 2: JP2018-075600A Patent Document 3: JP2006-315123A 30 Patent Document 4: JPH1-255117A 4 Patent Document 5: WO 2016/027288 Patent Document 6: JP2012-101258A Patent Document 7: JP2008-155219A NON PATENT DOCUMENT 5 [0010] Non-Patent Document 1: Osamu KADA, and two others, "Advanced Forming Analysis for Bar and Wire Rod with Finite Element Method", Nippon Steel Technical Report, Nippon Steel Corporation, March 2007, No. 386, p. 59-63 10 SUMMARY OF INVENTION TECHNICAL PROBLEM [0011] However, in the aforementioned Patent Document 1, the plated metal layer on the surface of the base metal material only covers at least one part of the shear surface 15 of the cut end face, and the base metal material remains exposed at the fracture surface. Consequently, the corrosion resistance of the cut end face of the plated metal sheet is not sufficient. Further, in general, when it is attempted to impart an excessive sacrificial protection property to the cut end face for the purpose of rust prevention, the plating on the surface of the plated metal sheet decreases, and the surface corrosion 20 resistance at the surface of the plated metal sheet (that is, the flat surface corrosion resistance) decreases. [0012] Further, in the aforementioned Patent Document 2, the plating coverage is increased by performing two processes, namely, a process for cutting a surface-treated 25 steel sheet, and a process for forming an end face portion of the surface-treated steel sheet that was cut. However, because it is necessary to perform a plurality of processes, the equipment cost increases. Further, in the technique described in Patent Document 2, after cutting the surface-treated steel sheet with a rotary blade that is shifted upward and downward, the shape of the end face portion is adjusted, and 30 consequently, because stress is imparted in different directions in the respective 5 processes, cracking or peeling is liable to occur in the plating layer. In addition, in the technique described in Patent Document 2, it is necessary to cause a greater amount of the plating layer to flow from the surface side in order to cover the end face of the steel sheet which is the base material. Consequently, there is a possibility that a defect such 5 as cracking of the plating at the outer layer or localized thinning of the plating may occur, or the plating may flow onto the surface of the steel sheet to which an oxide coating or contamination has adhered, resulting in poor adhesion of the plating. [0013] In addition, in the aforementioned Patent Document 3, the front end of the 10 cutting edge has a flat portion as illustrated in Figure 2(a). Therefore, when a laminated substrate is cut using such a tool, the plating is split when the blade bites into the laminated substrate, and the cut end face is not covered with the plating. Further, because the state at the end of cutting is one in which the material is crushed, it is difficult to cut the laminated substrate in a single process, or to impart sufficient damage 15 to the laminated substrate in a first process and perform cutting to make the cut end face into a desired shape in the next process. [0014] Furthermore, in the aforementioned Patent Document 4, the objective is to cause the plating of the wire rod to cover the end face thereof during cutting. As 20 illustrated in Figure 1 and Figure 2 of Patent Document 4, although one side of the blade of the cutter in question is an inclined face, the other side is a substantially vertical face, and thus the shape has remarkably high asymmetry. When the blade bites into the wire rod, the blade and the wire rod come in contact at a point, and consequently almost no force is generated in the direction perpendicular to the direction 25 in which the blade advances. Therefore, when the workpiece is a wire rod, it is possible to cut the workpiece even in the case of the cutting edge shape illustrated in Patent Document 4. On the other hand, in the case of cutting a workpiece that is a tabular material, the blade and the workpiece contact each other in the form of a line. Therefore, in the case of the cutting edge shape shown in Patent Document 4, a large 30 force arises in the direction perpendicular to the direction in which the blade advances, 6 and the load on the blade increases. Although in a case where the workpiece is extremely soft relative to the blade, such as in the case of a resin workpiece, the load that arises at the blade in question does not constitute a problem, in the case of cutting a material that has a certain strength or more, such as a metal material, the durability of 5 the blade is caused to markedly deteriorate. [0015] Therefore, the present invention has been made in view of the problems described above, and an objective of the present invention is to provide a novel and improved cutting method and cutting tool which, with respect to cutting of a workpiece, 10 are capable of suppressing the occurrence of a situation in which the performance which the workpiece has is reduced after the cutting. SOLUTION TO PROBLEM [0016] 15 According to an embodiment of the present invention, there is provided a cutting method for cutting a workpiece using a cutting tool comprising a die and a punch, which includes arranging the workpiece between the die and the punch, and in a state in which a wedge-shaped first cutting part of the die and a wedge-shaped second cutting part of the punch are opposed, pushing the punch relatively to the die side to cut 20 the workpiece; wherein: a front end angle θ1 of the first cutting part and a front end angle θ2 of the second cutting part are each 10° or more and 120° or less, and a front end radius R1 of the first cutting part and a front end radius R2 of the second cutting part are each 0.5% or more and 35.0% or less of a sheet thickness. [0017] 25 The workpiece may be a multi-layer material formed by coating a surface of a base material with a coating material. [0018] The front end angle θ1 of the first cutting part and the front end angle θ2 of the second cutting part may be each 30° or more and 90° or less. 30 [0019] 7 The front end radius R1 of the first cutting part and the front end radius R2 of the second cutting part may be each 1.5% or more and 10.0% or less of a sheet thickness. [0020] 5 The cutting of the workpiece may be performed by a plurality of cutting processes. [0021] The plurality of cutting processes may include a first cutting process, and a second cutting process that is performed after the first cutting process; and in the second 10 cutting process, at least one of the following may be performed: a front end angle θ1 of the first cutting part in the second cutting process is made smaller than a front end angle θ1 of the first cutting part in the first cutting process, and a front end angle θ2 of the second cutting part in the second cutting process is made smaller than a front end angle θ2 of the second cutting part in the first cutting process, and thereafter the workpiece 15 may be cut. [0022] Moreover, the plurality of cutting processes may include a first cutting process, and a second cutting process that is performed after the first cutting process; and in the second cutting process, at least one of the following may be performed: a front end 20 radius R1 of the first cutting part in the second cutting process is made smaller than a front end radius R1 of the first cutting part in the first cutting process, and a front end radius R2 of the second cutting part in the second cutting process is made smaller than a front end radius R2 of the second cutting part in the first cutting process; and thereafter the workpiece may be cut. 25 [0023] Moreover, among the plurality of cutting processes, when a front end radius of the first cutting part is defined as R1, a front end radius of the second cutting part is defined as R2, and a sheet thickness of the workpiece is defined as t, a stroke S of the punch in a first cutting process may satisfy expression (A) below: 30 (R1+R2)≤S≤{t-(R1+R2)} ...(A). 8 [0024] A trimming width of the workpiece is a distance between one end portion of the workpiece and a cutting position of the workpiece, and when a front end radius of the first cutting part is defined as R1, a front end radius of the second cutting part is 5 defined as R2, and a sheet thickness of the workpiece is defined as t, a trimming width D of the workpiece may satisfy expression (B) below: R