Shearing machine

Abstract

To provide a shearing machine capable of suppressing the occurrence of edge nicking caused by a concentrated load applied on the tip of a cutter.SOLUTION: First and second cutters 41 and 42 are configured so that at a position where biting of a material to be cut is started by a first blade tip 412 of the first cutter 41 and a second blade tip of the second cutter 42, an angle θ1 between a first top surface 411 of the first cutter 41 and a surface of the material can be smaller than an angle θ2 between a second top surface 421 of the second cutter 42 and the backside of the material. The first blade tip 412 is provided at the rear end of the first top surface 411 in the rotation direction of a first rotary drum 40A. The first cutter 41 has a first slope 413 inclined from the first blade tip 412 to the first top surface 411 to extend in the height direction H1 of the first cutter 41. An angle between an extension surface of the first top surface 411 and the first slope 413 is over 0° and 45° or less, and the height of the first slope 413 in the height direction H1 of the first cutter 41 is 0.3 mm or more.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a shearing machine that applies a shearing force to a material to be cut by the relative movement of a first blade and a second blade attached to a first rotating drum and a second rotating drum, respectively, which are arranged opposite each other across the material to be cut. [Background technology]

[0002] Examples of this type of shearing machine that has been used conventionally include the shearing machines shown in Patent Documents 1 and 2 below.

[0003] Patent Document 1 describes "a shearing machine that moves a first blade and a second blade relatively to apply a shearing force to a material to be cut that is located between cutting edge A of the first blade and cutting edge B of the second blade, characterized in that cutting edges A and B have opposing obtuse angled portions with cutting edge angles greater than 90 degrees and less than 135 degrees formed by irregularly chamfering the regular corners of the first blade and the second blade, respectively." Patent Document 1 explains that by using such obtuse angled portions on cutting edges A and B, the distance between cutting edges A and B can maintain the initial clearance c even if cutting edges A and B wear.

[0004] Patent Document 2 describes a shearing machine that includes "a pair of rotating drums rotatably arranged to face each other with a conveyed material sandwiched therebetween, grooves arranged on the outer circumferential surfaces of the rotating drums and extending in the axial direction of the rotating drums, one cutting blade detachably arranged in the groove of one of the rotating drums, and the other cutting blade detachably arranged in the groove of the other rotating drum." Patent Document 2 also shows an embodiment in which, at a position where the cutting blades (first and second blades) start to bite into the material, the angle between the top surface of the first blade and the surface of the material is smaller than the angle between the top surface of the second blade and the back surface of the material. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-79096 [Patent Document 2] Patent No. 4979841 Summary of the Invention [Problem to be solved by the invention]

[0006] When a configuration is adopted in which the angle between the top surface of the first blade and the surface of the workpiece to be cut is smaller than the angle between the top surface of the second blade and the back surface of the workpiece, as in Patent Document 2, chips (missing blades) can occur in the cutting edge of the first blade before the cutting edge of the first blade wears down to the point where the first blade becomes unusable.

[0007] An investigation into the cause of chipping revealed that, in the early stages of cutting, a concentrated load acts on the cutting edge of the first blade, which has a smaller angle with the workpiece, generating a moment inside the first blade with the point of contact between the top face of the first blade and the surface of the workpiece as a fulcrum, causing tensile stress to act on the top face behind the contact point, which then leads to cracking.Even if an obtuse angle portion as in Patent Document 1 is used on the cutting edge, poor cutting due to wear of the cutting edge can be avoided, but it is difficult to prevent chipping.

[0008] The present invention has been made to solve the above-mentioned problems, and one of its purposes is to provide a shears that can suppress the occurrence of chipped blades caused by concentrated loads acting on the cutting edge of the blade. [Means for solving the problem]

[0009] In one embodiment, the shears according to the present invention are shears that apply a shearing force to the material to be cut by the relative movement of a first blade and a second blade attached to a first rotating drum and a second rotating drum, respectively, which are arranged to face each other across the material to be cut. The first blade and the second blade are configured so that, at the position where the first cutting edge of the first blade and the second cutting edge of the second blade begin to bite into the material, the angle between the first top surface of the first blade and the surface of the material to be cut is smaller than the angle between the second top surface of the second blade and the back surface of the material to be cut. The first cutting edge is provided at the rear end of the first top surface in the rotational direction of the first rotating drum. The first blade has a first inclined surface that extends from the first cutting edge to the first top surface in the height direction of the first blade, and is inclined from the first cutting edge to the first top surface. The angle between the extended surface of the first top surface and the first inclined surface is greater than 0° and less than 45°. The height of the first inclined surface in the height direction of the first blade is 0.3 mm or more. [Effects of the Invention]

[0010] According to one embodiment of the shears of the present invention, the angle between the extension of the first top surface and the first inclined surface is greater than 0° and less than 45°, and the height of the first inclined surface in the height direction of the first cutting tool is 0.3 mm or greater, which ensures a wide contact area between the workpiece and the first cutting tool during the cutting process and distributes the load on the first cutting edge to create a distributed load, thereby suppressing the occurrence of chipped edges due to a concentrated load acting on the first cutting edge of the first cutting tool. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a side view of a strip trimming system including a shear according to an embodiment of the present invention; [Figure 2] FIG. 2 is an enlarged side view of the shears of FIG. 1. [Figure 3] 10 is a side view showing the first blade and the second blade when the cutting edges of the first blade and the second blade start to bite into the trim chips. FIG. [Figure 4] 3 is a side view showing the first blade and the second blade in the middle of cutting the trimmings of FIG. 2.

[0023] FIG. [Figure 5]3 is a side view showing the first blade and the second blade when cutting of the trimmings in FIG. 2 is completed. FIG. [Figure 6] FIG. 4 is an explanatory diagram showing the cause of chipping (missing edge) on the first cutting edge of the first cutting tool. [Figure 7] 6 is an enlarged side view showing the first cutting edge and its periphery of the first cutting edge of the first cutting tool in FIG. 5. FIG. [Figure 8] 6 is an enlarged side view showing a corner portion and its periphery of the second cutting tool of FIG. 5. FIG. [Figure 9] FIG. 1 is an explanatory diagram showing internal stress of a blade obtained by FEM analysis. [Figure 10] 10 is a graph showing the relationship between the chamfer angle of the first cutting tool and the tensile stress. [Figure 11] 10 is a graph showing the relationship between the chamfer height of the first cutting tool and the tensile stress. [Figure 12] 10 is a graph showing the relationship between the number of chipped edges and the chamfering angle. DETAILED DESCRIPTION OF THE INVENTION

[0012] 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.

[0013] FIG. 1 is a side view showing a steel strip trimming equipment including a shearing machine 4 according to an embodiment of the present invention. The steel strip trimming equipment shown in FIG. 1 is equipment for cutting both sides of a steel strip 1 according to the product width. Although only one side is shown in FIG. 1, a pair of trimmers 2 are arranged spaced apart in the width direction of the steel strip 1 (a direction perpendicular to the plane of the paper in FIG. 1), and both sides of the steel strip 1 are cut by the trimmers 2. The cut both sides are called trim scraps 10. The steel strip 1 is continuously introduced into the trimmer 2, and the trim scraps 10 have a continuous strip-like form.

[0014] The trim scraps 10 are introduced through a chute 3 into a shearing machine 4 disposed diagonally below the trimmer 2. The shearing machine 4 of this embodiment cuts the trim scraps 10 as materials to be cut. The trim scraps 10 cut by the shearing machine 4 are made into shorter scraps 11. The scraps 11 can be transported to subsequent equipment via a conveyor 5.

[0015] Next, Fig. 2 is an enlarged side view of the shears 4 of Fig. 1. As shown in Fig. 2, the shears 4 has a first rotating drum 40A and a second rotating drum 40B arranged to face each other with the conveyed trim scraps 10 (material to be cut) therebetween, and a plurality of first blades 41 and a plurality of second blades 42 attached to the first rotating drum 40A and the second rotating drum 40B, respectively. The shears 4 applies a shearing force to the trim scraps 10 to cut them by relative movement between the first blades 41 and the second blades 42.

[0016] The first rotating drum 40A and the second rotating drum 40B may be cylindrical bodies extending with their axial direction intersecting the conveying direction 10a of the trim scraps 10, more specifically, perpendicular to the conveying direction 10a (the direction perpendicular to the plane of the paper in FIG. 1). The first blade 41 and the second blade 42 may be rectangular bodies extending in the axial direction of the first rotating drum 40A and the second rotating drum 40B. The outer circumferential surfaces of the first rotating drum 40A and the second rotating drum 40B may be provided with a plurality of grooves equally spaced circumferentially, and the first blade 41 and the second blade 42 may be attached to the grooves. In the illustrated embodiment, the grooves are arranged at 45° intervals, and the number of first blades 41 and the number of second blades 42 attached to the first rotating drum 40A and the second rotating drum 40B is eight. However, the number of first blades 41 and the number of second blades 42 attached to the first rotating drum 40A and the second rotating drum 40B may be changed as desired.

[0017] In the illustrated embodiment, the first rotating drum 40A is disposed above the trim scraps 10, and the second rotating drum 40B is disposed below the trim scraps 10. Depending on the cutting mode of the trim scraps 10, the orientations of the first rotating drum 40A and the second rotating drum 40B and the first blade 41 and the second blade 42 may be changed, for example, by disposing the first rotating drum 40A and the second rotating drum 40B on the left and right of the trim scraps 10.

[0018] The first rotating drum 40A and the second rotating drum 40B may be rotated in a direction along the conveying direction 10a of the trim scraps 10 at a position between the first rotating drum 40A and the second rotating drum 40B through which the trim scraps 10 pass. In Fig. 2, the first rotating drum 40A is shown rotated counterclockwise, and the second rotating drum 40B is shown rotated clockwise.

[0019] The first blade 41 and the second blade 42 are arranged so that their tips protrude from the outer circumferential surfaces of the first rotating drum 40A and the second rotating drum 40B. The first blade 41 and the second blade 42 move relative to each other as the first rotating drum 40A and the second rotating drum 40B rotate, respectively, causing the trim scraps 10 to be cut by the first blade 41 and the second blade 42 at a position between the first rotating drum 40A and the second rotating drum 40B. The position between the first rotating drum 40A and the second rotating drum 40B can be referred to as the cutting position of the trim scraps 10.

[0020] The straight line passing through the central axes or rotation axes of the first rotating drum 40A and the second rotating drum 40B is called the center line CLi. The center line CLi may be disposed so as to be perpendicular to the conveying direction 10a of the trim scraps 10 and the central axes of the first rotating drum 40A and the second rotating drum 40B. When the trim scraps 10 are conveyed diagonally downward as in the illustrated embodiment, the center line CLi may be inclined with respect to the vertical direction.

[0021] The first blade 41 is disposed so as to be located forward of the center line CLi in the rotation direction of the first rotating drum 40A when the first blade 41 moves to the cutting position for the trim scraps 10 due to the rotation of the first rotating drum 40A. Conversely, the second blade 42 is disposed so as to be located rearward of the center line CLi in the rotation direction of the second rotating drum 40B when the second blade 42 moves to the cutting position for the trim scraps 10 due to the rotation of the second rotating drum 40B. A rear side surface 410 of the first blade 41 in the rotation direction of the first rotating drum 40A and a front side surface 420 of the second blade 42 in the rotation direction of the second rotating drum 40B may extend along the center line CLi at the cutting position for the trim scraps 10.

[0022] Next, the behavior of the first blade 41 and the second blade 42 will be described in more detail with reference to Figures 3 to 5. Figure 3 is a side view showing the first blade 41 and the second blade 42 when the cutting edges of the first blade 41 and the second blade 42 start to bite into the trim 10, Figure 4 is a side view showing the first blade 41 and the second blade 42 in the middle of cutting the trim 10 of Figure 2, and Figure 5 is a side view showing the first blade 41 and the second blade 42 when cutting the trim 10 of Figure 2 is completed. Note that Figures 3 to 5 illustrate the case where the angle θ3 (see Figure 7) between the extension surface ES1 of the first top surface 411 and the first inclined surface 413 is 15°.

[0023] The first blade 41 of this embodiment has a first top surface 411, a first cutting edge 412, and a first inclined surface 413. The first top surface 411 is disposed at a position that protrudes most from the outer circumferential surface of the first rotating drum 40A. The first cutting edge 412 is provided at the rear end of the first top surface 411 in the rotation direction of the first rotating drum 40A. The first inclined surface 413 extends from the first cutting edge 412 in a height direction H1 of the first blade 41, inclined relative to the first top surface 411. A first intermediate corner between the first inclined surface 413 and the first top surface 411 may be understood as the first cutting edge 412. The height direction H1 of the first blade 41 is the direction in which the first blade 41 protrudes from the outer circumferential surface of the first rotating drum 40A, and may be the radial direction of the first rotating drum 40A. The first beveled surface 413 may extend between the first cutting edge 412 and the rear side surface 410 of the first blade 41. The first beveled surface 413 may be formed by chamfering the corner where the first top surface 411 and the rear side surface 410 meet.

[0024] The second blade 42 of this embodiment has a second top surface 421, a corner portion 422, and a second inclined surface 423. The second top surface 421 is disposed at a position that protrudes most from the outer peripheral surface of the second rotating drum 40B. The corner portion 422 is provided at the front end of the second top surface 421 in the rotation direction of the second rotating drum 40B. The second inclined surface 423 extends from the corner portion 422 in the height direction H2 of the second blade 42, inclined relative to the second top surface 421. The corner portion 422 may be understood as a second intermediate corner portion between the second inclined surface 423 and the second top surface 421. The height direction H2 of the second blade 42 is the direction in which the second blade 42 protrudes from the outer peripheral surface of the second rotating drum 40B and may be the radial direction of the second rotating drum 40B. The second inclined surface 423 may extend between the corner portion 422 and the front side surface 420 of the second blade 42. The second inclined surface 423 can be formed by chamfering a corner 422 where the second top surface 421 and the front side surface 420 meet.

[0025] As described above, the first blade 41 and the second blade 42 cut the trim scraps 10 by moving in accordance with the rotation of the first rotating drum 40A and the second rotating drum 40B, respectively. In Figures 3 to 5, the first blade 41 moves counterclockwise along a circular orbit, and the second blade 42 moves clockwise along a circular orbit.

[0026] The first blade 41 and the second blade 42 contact the trim scraps 10 from the front side in the rotation direction of the first rotating drum 40A and the second rotating drum 40B. In the first blade 41, the first top surface 411 contacts the trim scraps 10 before the first cutting edge 412, and in the second blade 42, the corner 422 and / or the second inclined surface 423 contact the trim scraps 10 before the second top surface 421. Which portion of the second blade 42 first contacts the trim scraps 10 varies depending on the chamfer angle used to form the second inclined surface 423 and the thickness of the trim scraps 10. The portion of the second blade 42 that first contacts the trim scraps 10 may be understood as the second cutting edge. FIG. 3 shows an aspect in which the front end of the second inclined surface 423 in the rotation direction of the second rotating drum 40B first contacts the trim scraps 10. Although not limited thereto, the thickness of the trim scrap 10 can be greater than or equal to 0.3 mm and up to 6.0 mm.

[0027] As shown in FIG. 3 , cutting of the trim scraps 10 begins when the first cutting edge 412 of the first blade 41 and the second cutting edge of the second blade 42 begin to bite into the trim scraps 10. As shown in FIG. 4 , the cutting of the trim scraps 10 progresses as the first blade 41 and the second blade 42 move further from the state shown in FIG. 3 . As shown in FIG. 5 , cutting of the trim scraps 10 is completed when the first blade 41 and the second blade 42 overlap most closely in the direction of the center line CLi. This may be interpreted as the first blade 41 reaching its bottom dead center and the second blade 42 reaching its top dead center. The trim scraps 10 are sequentially introduced between the first rotating drum 40A and the second rotating drum 40B. After cutting of the trim scraps 10 is completed, the subsequent first blade 41 and second blade 42 in the direction of rotation of the first rotating drum 40A and the second rotating drum 40B cut the trim scraps 10.

[0028] 5, when cutting of the trim scraps 10 is completed, the rear side 410 of the first cutting tool 41 and the front side 420 of the second cutting tool 42 may extend parallel to each other along the center line CLi. Furthermore, when cutting of the trim scraps 10 is completed, the first top surface 411 and the second top surface 421 may extend perpendicular to the center line CLi. The distance between the first top surface 411 and the second top surface 421 in the direction in which the center line CLi extends when cutting of the trim scraps 10 is completed is referred to as the maximum overlap width MLM (see FIG. 5).

[0029] As shown in Figure 3, the first blade 41 and the second blade 42 of this embodiment are configured so that at the position where the first cutting edge 412 of the first blade 41 and the second cutting edge of the second blade 42 start to bite into the trim scraps 10, the angle θ1 between the first top surface 411 of the first blade 41 and the surface of the trim scraps 10 is smaller than the angle θ2 between the second top surface 421 of the second blade 42 and the back surface of the trim scraps 10.

[0030] Next, FIG. 6 is an explanatory diagram illustrating a cause of chipping (edge ​​chipping) in the first cutting edge 412 of the first cutting tool 41. When the shears 4 described above are used to cut the trim scraps 10, the first cutting edge 412 of the first cutting tool 41 may be chipped (edge ​​chipped) before the first cutting edge 412 of the first cutting tool 41 wears down and becomes unusable. Investigation into the cause of edge chipping revealed that, in the early stages of cutting, a concentrated load CLo acts on the first cutting edge 412 of the first cutting tool 41 that has a smaller angle θ1 (see FIG. 3 ) with the trim scraps 10. This generates a moment IM inside the first cutting tool 41, with the contact point between the first top surface 411 of the first cutting tool 41 and the surface of the trim scraps 10 as a fulcrum. This causes a tensile stress TS to act on the first top surface 411 behind the contact point in the rotational direction of the first rotating drum 40A, which then leads to a crack starting from the point SP. This is believed to be the cause of edge chipping. This situation can be thought of as a situation in which a concentrated load CLo is applied to the tip of the cantilever beam.

[0031] On the other hand, with regard to the second cutting tool 42, the angle θ2 (see FIG. 3) between the trim scraps 10 and the second top surface 421 is relatively large at the beginning of cutting, and only compressive stress is applied to the contact point with the trim scraps 10. Since chipping occurs due to tensile stress TS, it is considered to be a phenomenon specific to the first cutting tool 41.

[0032] 7 is an enlarged side view of the first cutting edge 412 and its periphery of the first cutting tool 41 of FIG. 5. As a result of various studies into directions that can prevent chipping of the first cutting tool 41 as described above, it was found that chipping of the first cutting tool 41 can be prevented when the angle θ3 between the extension surface ES1 of the first top surface 411 and the first slant surface 413 is greater than 0° and less than 45°, and when the height TH1 of the first slant surface 413 in the height direction H1 of the first cutting tool 41 is 0.3 mm or greater. The angle θ3 is the chamfer angle when forming the first slant surface 413, and the height TH1 may be the chamfer height.

[0033] By setting the angle θ3 to 45° or less, a wide contact area between the first cutting tool 41 and the trims 10 during the cutting process can be ensured, and the load on the first cutting edge 412 can be dispersed to form a distributed load. This reduces the moment IM generated on the rear surface of the first cutting edge 412, reduces the tensile stress TS at the first top surface 411, and suppresses the occurrence of chipped edges due to the concentrated load CLo acting on the first cutting edge 412 of the first cutting tool 41. It is preferable that the angle θ3 be as small as possible. However, when the angle θ3 is 0°, the first cutting edge 412 becomes 90°, causing chipped edges. When the angle θ3 is greater than 0°, the contact area between the first cutting tool 41 and the trims 10 during the cutting process can be widened compared to when the angle θ3 is 0°.

[0034] The angle θ3 is preferably 10° or more and 30° or less. By setting the angle θ3 to 30° or less, a wider contact area between the first cutting tool 41 and the trim chips 10 during the cutting process can be more reliably ensured, and the load applied to the first cutting edge 412 can be more reliably distributed. By setting the angle θ3 to 10° or more, the load can be more reliably distributed by the first inclined surface 413. Furthermore, by setting the angle θ3 to 10° or more, the processing for forming the first inclined surface 413 can be facilitated. For this reason, the angle θ3 is preferably 10° or more. The angle θ3 is more preferably 12° or more and 28° or less, and even more preferably 15° or more and 25° or less. For example, the angle θ3 may be optimally set to 15°.

[0035] By setting the height TH1 of the first inclined surface 413 to 0.3 mm or more, a wide contact area between the first cutting tool 41 and the trim chips 10 during the cutting process can be ensured, and the load applied to the first cutting edge 412 can be dispersed to form a distributed load. This reduces the moment IM generated on the rear surface of the first cutting edge 412, reduces the tensile stress TS at the first top surface 411, and suppresses the occurrence of chipped edges due to the concentrated load CLo acting on the first cutting edge 412 of the first cutting tool 41.

[0036] From the viewpoint of preventing chipping of the first cutting edge 41, there is no particular upper limit for the height TH1 of the first inclined surface 413. However, if the height TH1 of the first inclined surface 413 is too large, the clearance between the rear side 410 of the first cutting edge 411 and the front side 420 of the second cutting edge 42 increases near the first top surface 411 and the second top surface 421, causing poor cutting of the trim scraps 10. The height TH1 of the first inclined surface 413 is preferably no more than two-thirds of the maximum overlap length MLM (see FIG. 5 ) between the first cutting edge 41 and the second cutting edge 42. This prevents poor cutting of the trim scraps 10. The height TH1 of the first inclined surface 413 is more preferably no more than 1.0 mm. This more reliably prevents poor cutting of the trim scraps 10. The height TH1 of the first inclined surface 413 is even more preferably no less than 0.4 mm and no more than 0.8 mm, and 0.5 mm may be optimal.

[0037] Next, Fig. 8 is an enlarged side view showing the corner 422 and its surroundings of the second cutting blade 42 in Fig. 5. As described above, chipping of the blade is relatively unlikely to occur in the second cutting blade 42. Therefore, from the viewpoint of suppressing the occurrence of chipping of the blade, the second cutting blade 42 may have any configuration.

[0038] However, as shown in Figure 8, it is preferable that the angle θ4 between the extension surface ES2 of the second top surface 421 and the second inclined surface 423 is greater than 0° and less than 45°, and that the height TH2 of the second inclined surface 423 in the height direction H2 of the second blade 42 is smaller than the height TH1 of the first inclined surface 413.

[0039] The angle θ4 is preferably 10° or more and 30° or less, more preferably 12° or more and 28° or less, and even more preferably 15° or more and 25° or less. The angle θ4 of the second cutting tool 42 is preferably equal to the angle θ3 of the first cutting tool 41. This is because the angle is not changed during processing, thereby reducing processing time.

[0040] As described above, chipping of the second cutting tool 42 is relatively unlikely, so the height TH2 of the second inclined surface 423 does not need to be high. By making the height TH2 of the second inclined surface 423 smaller than the height TH1 of the first inclined surface 413, the area facing the rear surface 410 of the first cutting tool 41 and the front surface 420 of the second cutting tool 42 can be made larger than when the height TH2 of the second inclined surface 423 is the same as the height TH1 of the first inclined surface 413, thereby reducing the occurrence of poor cutting of the trim scraps 10. It is more preferable that the height TH2 of the second inclined surface 423 be 0.1 mm or more and less than 0.3 mm. This more reliably reduces the occurrence of poor cutting of the trim scraps 10.

[0041] 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.

[0042] For example, although the shears 4 in the embodiments of the present invention have been described as cutting trim scrap 10 in a steel strip trimming facility, the shears 4 of the present invention may be used to cut any other material to be cut. [Example]

[0043] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0044] The inventors evaluated the internal stress of the blades using FEM analysis. The first cutting tool 41, the second cutting tool 42, and the trimmings 10 were modeled (using two-dimensional solid elements) and analyzed until the trimmings 10 reached their tensile strength. In the FEM analysis, the angle θ3 between the extension ES1 of the first top surface 411 and the first inclined surface 413 and the angle θ4 between the extension ES2 of the second top surface 421 and the second inclined surface 423 were set to 45°. The results of the FEM analysis are shown in FIG. 9. Note that the location of the second cutting tool 42 that first contacts the trimmings 10 (the second cutting edge) differs from the example shown in FIGS. 3 to 5, which show angles θ3 and θ4 of 15°. As can be seen from FIG. 9, when the first cutting tool 41 and the second cutting tool 42 were pressed into the trimmings 10, the maximum tensile stress occurred at the same position as the chipping point of the first cutting tool 41. Therefore, it was determined that the chipping occurred starting from the position where the maximum tensile stress occurred.

[0045] Next, the height TH1 of the first inclined surface 413 in the height direction H1 of the first cutting tool 41 (hereinafter referred to as the "chamfer height") was fixed at 0.5 mm, while the angle θ3 between the extension surface ES1 of the first top surface 411 and the first inclined surface 413 (hereinafter referred to as the "chamfer angle") was changed, and the change in the tensile stress TS acting on the first cutting tool 41 was investigated. The results are shown in FIG. 10. The horizontal axis of FIG. 10 is the chamfer angle, and the vertical axis is the ratio of the tensile stress TS to the tensile stress TS when the chamfer angle is 45°. It can be seen from the results shown in FIG. 10 that the tensile stress TS decreases as the chamfer angle decreases.

[0046] Furthermore, while the chamfer angle was fixed at 25°, the chamfer height was changed to examine the change in the tensile stress TS acting on the first cutting tool 41. The results are shown in Fig. 11. The horizontal axis of Fig. 11 is the chamfer height (mm), and the vertical axis is the ratio of the tensile stress TS to the tensile stress TS when the chamfer height is 0.5 mm. The results shown in Fig. 11 show that the tensile stress TS decreases as the chamfer height increases.

[0047] Next, several first cutting tools 41 were prototyped with a fixed chamfer height of 0.5 mm and chamfer angles of 15°, 25°, 45°, and 90°, and the occurrence of chipped edges of the first cutting tools 41 was confirmed in the shearing machine 4 of the steel strip trimming equipment shown in Figure 1. The results are shown in Table 1 and Figure 12. When the chamfer angle was 90°, that is, when the first top surface 411 and the rear side surface 410 were butted at a right angle without providing the first inclined surface 413 (no chamfering), many chipped edges occurred. When the chamfer angle was 15° or 25°, the occurrence of chipped edges was extremely low. When the chamfer angle was 45°, the occurrence of chipped edges was reduced compared to when the chamfer angle was 90°. From these results, it was confirmed that by setting the chamfer angle (angle θ3) to 45° or less, a wide contact area between the first cutting tool 41 and the trimmings 10 during the cutting process can be ensured, and the load acting on the first cutting edge 412 can be dispersed to form a distributed load.

[0048] [Table 1]

[0049] When the chamfer angle was 15° or 25°, chipping hardly occurred even when used for a period two to three times longer than the period when chipping occurred when the chamfer angle was 45°. This confirmed that by increasing the contact area between the workpiece and the first cutting tool 41 during the cutting process and dispersing the load on the first cutting edge 412 to form a distributed load, it was possible to suppress the occurrence of chipping caused by the concentrated load CLo acting on the first cutting edge 412 of the first cutting tool 41.

[0050] The invention described in this specification can also be described as follows. [1] A shearing machine that applies a shearing force to a material to be cut by the relative movement of a first blade and a second blade attached to a first rotating drum and a second rotating drum, respectively, that are arranged to face each other across the material to be cut, the first blade and the second blade are configured such that, at a position where the first cutting edge of the first blade and the second cutting edge of the second blade start to bite into the workpiece, an angle between a first top surface of the first blade and a surface of the workpiece is smaller than an angle between a second top surface of the second blade and a back surface of the workpiece, the first cutting edge is provided at a rear end of the first top surface in the rotation direction of the first rotating drum, and the first blade has a first inclined surface that is inclined from the first cutting edge to the first top surface and extends in a height direction of the first blade, The angle between the extension of the first top surface and the first inclined surface is greater than 0° and less than 45°, and the height of the first inclined surface in the height direction of the first blade is 0.3 mm or more. Shearing machine. [2] The angle between the extension of the first top surface and the first inclined surface is 10° or more and 30° or less. 10. The shears of claim 1. [3] The height of the first inclined surface in the height direction of the first blade is 2 / 3 or less of the maximum overlapping distance between the first blade and the second blade. 3. A shearing machine according to claim 1 or 2. [4] The height of the first inclined surface in the height direction of the first blade is 1.0 mm or less. 4. The shears of claim 3. [5] the second blade has a corner portion provided at a front end of the second top surface in the rotation direction of the second rotating drum, and a second inclined surface extending from the corner portion in a height direction of the second blade and inclined with respect to the second top surface, The angle between the extension of the second top surface and the second inclined surface is greater than 0° and less than 45°, and the height of the second inclined surface in the height direction of the second blade is smaller than the height of the first inclined surface. 5. A shearing machine according to any one of claims 1 to 4. [6] The height of the second inclined surface is 0.1 mm or more and less than 0.3 mm. 6. A shearing machine as described in paragraph 5. [Explanation of symbols]

[0051] 4: Shearing machine 40A: First rotating drum 40B: Second rotating drum 41: First blade 411: 1st top surface 412: First cutting edge 413: First slope 42: Second blade 421: 2nd top surface 422: Corner 423: Second slope

Claims

1. A shearing machine that applies a shearing force to a material to be cut by the relative movement of a first blade and a second blade attached to a first rotating drum and a second rotating drum, respectively, that are arranged to face each other across the material to be cut, the first blade and the second blade are configured such that, at a position where the first cutting edge of the first blade and the second cutting edge of the second blade start to bite into the workpiece, an angle between a first top surface of the first blade and a surface of the workpiece is smaller than an angle between a second top surface of the second blade and a back surface of the workpiece, the first cutting edge is provided at a rear end of the first top surface in the rotation direction of the first rotating drum, and the first blade has a first inclined surface that is inclined from the first cutting edge to the first top surface and extends in a height direction of the first blade, an angle between an extension of the first top surface and the first inclined surface is greater than 0° and less than 45°, and a height of the first inclined surface in the height direction of the first blade is 0.3 mm or more; Shearing machine.

2. an angle between an extension of the first top surface and the first inclined surface is 10° or more and 30° or less; The shears of claim 1 .

3. a height of the first inclined surface in a height direction of the first blade being equal to or less than two-thirds of a maximum overlapping distance between the first blade and the second blade; The shears of claim 1 .

4. The height of the first inclined surface in the height direction of the first blade is 1.0 mm or less.

4. The shears of claim 3.

5. the second blade has a corner portion provided at a front end of the second top surface in the rotation direction of the second rotating drum, and a second inclined surface extending from the corner portion in a height direction of the second blade and inclined with respect to the second top surface, The angle between the extension of the second top surface and the second inclined surface is greater than 0° and less than 45°, and the height of the second inclined surface in the height direction of the second blade is smaller than the height of the first inclined surface.

5. A shears machine according to any one of claims 1 to 4.

6. The height of the second inclined surface is 0.1 mm or more and less than 0.3 mm.

6. The shears of claim 5.

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