JP2022031258A - Shearing device and shearing method - Google Patents

Abstract

To prevent a large tensile residual stress from being generated on the end face of the steel sheet remaining on the die, and to suppress deterioration of fatigue characteristics and hydrogen embrittlement resistance.SOLUTION: A shearing device 10 comprises a die 20, a punch 30, a moving device 40, and a holder 50, where a first ridge line portion 26 being a cutting edge, includes a first tilted surface 26B1 and a first curved surface 26B2, a second ridge line portion 36 being a cutting edge forming a shear angle α between the first ridge line portion 26 and itself, includes a second tilted surface 36B1 and a second curved surface 36B2, and a total tilt angle difference ΔCT satisfies (0.15×α2+0.05×α+1)<ΔCT≤40 where the total tilt angle difference ΔCT is a sum of a first tilt angle difference ΔCA [degree] obtained by subtracting a tilt angle C2 of the second tilt surface 36B1 from a tilt angle C1 of the first tilted surface 26B1, and a second tilt angle difference ΔCB calculated from a curvature radius difference ΔR obtained by subtracting a curvature radius R2 of the second curved surface 36B2 from a curvature radius R1 of the first curved surface 26B2.SELECTED DRAWING: Figure 10

Description

The present disclosure relates to a shearing machine and a shearing method.

Conventionally, it is known that the characteristics of a steel sheet are impaired due to work hardening, surface roughness, large tensile residual stress, and the like on the end face of the steel sheet as a work material cut by shearing. As a technique for reducing the influence on the characteristics of the steel sheet, for example, Patent Document 1 describes the above according to the deformation in the thickness direction of the work material during the shearing process until the steel plate of the work material has a fracture surface. Shearing devices that increase the clearance between the blade and the lower blade are disclosed. According to Patent Document 1, it is possible to reduce the influence of work hardening on the end face of a member after fracture.

International Publication No. 2018/180820

In general shearing, a large amount of strain is generated inside the steel sheet in contact with the cutting edge of the die, and as a result, cracks are likely to develop from the surface of the steel sheet on the die side. In addition, due to the growth of cracks from the surface of the steel sheet on the die side, a large tensile residual stress is generated on the end face of the steel sheet remaining on the die after shearing, and the fatigue characteristics and hydrogen embrittlement resistance deteriorate. .. In particular, deterioration of hydrogen embrittlement resistance tends to occur in high-strength steel plates of 980 MPa or more.

By the way, for the purpose of reducing the maximum value of the load required for machining in shearing, a method of cutting a workpiece with a shear angle between the cutting edge of a die and the cutting edge of a punch is known. However, it was found that the larger the shear angle applied, the higher the probability that cracks will grow from the surface of the steel sheet on the die side.

In both the state where the shear angle is not given and the state where the shear angle is given, the fatigue characteristics and hydrogen embrittlement resistance of the steel sheet cut into the product and scrap by shearing are deteriorated. If it occurs on the scrap side, the problem is small. On the other hand, if the fatigue characteristics and the hydrogen embrittlement resistance are deteriorated on the product side, there is a concern that the product may be defective. Therefore, when the steel sheet is sheared and the steel sheet remaining on the die is obtained as a product, the present inventors suppress the growth of cracks from the surface of the steel sheet on the die side and suppress the growth of cracks on the die side. It was found that shortening or reducing the growth distance of cracks from the steel sheet to zero is effective for preventing deterioration of fatigue characteristics and hydrogen embrittlement resistance characteristics.

In view of the above problems, the present disclosure is a shearing apparatus capable of preventing a large tensile residual stress from being generated on the end face of the steel plate remaining on the die, and suppressing deterioration of fatigue characteristics and hydrogen embrittlement resistance. It is an object of the present invention to provide a shearing method using this shearing apparatus.

The shearing apparatus according to the first aspect of the present disclosure has a first surface in contact with one surface of a steel plate and a second surface continuous with the first surface via a first ridge line portion as a cutting edge. A third surface that is continuous with the third surface via a second ridge line portion that is a cutting edge that forms a shear angle α between the die and the third surface that contacts the other surface of the steel plate and the first ridge line portion. The holder that sandwiches the steel plate between the punch having four sides and the first side of the die, and the die or punch, the position where the fourth side of the punch faces the holder and the fourth side faces the second side of the die. A moving device that moves relative to and from the position to be formed along the thickness direction of the steel plate is provided, and the first ridge portion is at least one of the first inclined surface and the first curved surface inclined with respect to the first surface. One is included, and the second ridge portion includes at least one of a second inclined surface and a second curved surface inclined with respect to the third surface, and the direction of relative movement and the fourth surface and the holder face each other. From the tilt angle [degrees], which is the smaller angle formed by the first inclined surface with the first surface when viewed from a direction orthogonal to both directions, the smaller angle formed by the second inclined surface with the third surface. The first inclination angle difference ΔCA [degree] obtained by subtracting a certain inclination angle [degree] and the radius of curvature difference ΔR [mm] obtained by subtracting the radius of curvature [mm] of the second curved surface from the radius of curvature [mm] of the first curved surface. ]of,
ΔCB [degree] = 80 × ΔR
When the second tilt angle difference ΔCB is calculated and the sum of the first tilt angle difference ΔCA and the second tilt angle difference ΔCB is the total tilt angle difference ΔCT, the total tilt angle difference ΔCT is
(0.15 × α ² +0.05 × α + 1) <ΔCT ≦ 40
Meet.

In the first aspect, the total tilt angle difference ΔCT, which is the sum of the first tilt angle difference ΔCA and the second tilt angle difference ΔCB, is
(0.15 × α ² +0.05 × α + 1) <ΔCT ≦ 40
The shapes of the first ridge line portion and the second ridge line portion are configured so as to satisfy the above conditions. When the steel plate is cut with a tool (shearing device) whose shape of the first ridge line portion and the second ridge line portion is as in the first aspect, it is possible to suppress the biting of the blade on the die side into the steel plate during shearing. .. Then, while promoting the growth of cracks from the surface of the steel plate on the punch side, the growth of cracks from the surface of the steel plate on the die side is suppressed, and the growth distance of the cracks from the die side is shortened or set to zero. be able to.

The shearing apparatus according to the second aspect of the present disclosure includes a step of preparing the shearing apparatus of the first aspect and a step of placing a steel plate on the first surface of the die of the prepared shearing apparatus. And the step of supporting the placed steel plate by the holder, and the die or punch using the moving device, relative to each other along the thickness direction of the steel plate so that the first ridge portion and the second ridge portion are close to each other. Includes steps to move and cut the steel sheet.

In the second aspect, since the steel sheet is sheared using the shearing apparatus of the first aspect, cracks are promoted from the surface of the steel sheet on the punch side and the die side is sheared. Suppresses the growth of cracks from the surface of the steel sheet. Then, the crack growth distance from the die side can be shortened or set to zero.

According to the present disclosure, it is possible to provide a shearing apparatus capable of preventing a large tensile residual stress from being generated on the end face of a steel sheet remaining on a die and suppressing deterioration of fatigue characteristics and hydrogen embrittlement resistance. Further, according to the shearing method using this shearing apparatus, it is possible to prevent a large tensile residual stress from being generated on the end face of the steel sheet remaining on the die, and to suppress deterioration of fatigue characteristics and hydrogen embrittlement resistance. ..

It is a perspective view explaining the structure of the shearing processing apparatus which concerns on 1st Embodiment of this disclosure. It is a front view explaining the structure of the shearing processing apparatus which concerns on 1st Embodiment. 3 is a sectional view taken along line 3-3 in FIG. It is a figure explaining the calculation method of the radius of curvature difference in the case where the radius of curvature difference of a cutting edge is non-uniform along the extending direction of a cutting edge. It is a graph which explains the relationship between the inclination angle difference and the shear angle in the shearing apparatus which concerns on 1st Embodiment. It is sectional drawing explaining the shearing processing method which concerns on 1st Embodiment. It is a graph which explains the magnitude of the tensile residual stress of each of the product and scrap obtained by the shearing process which concerns on 1st Embodiment. It is sectional drawing of the position corresponding to line 3-3 in FIG. 2, which explains the structure of the shearing processing apparatus which concerns on 2nd Embodiment of this disclosure. It is a graph which explains the relationship between the radius of curvature difference and the shear angle in the shearing apparatus which concerns on 2nd Embodiment. It is sectional drawing of the position corresponding to line 3-3 in FIG. 2, which explains the structure of the shearing processing apparatus which concerns on 3rd Embodiment of this disclosure. It is a perspective view explaining the structure of the shearing processing apparatus which concerns on the modification. It is a top view explaining the method of confirming a shear angle in a shearing machine.

The first to third embodiments will be described below. In the description of the drawings below, the same parts and similar parts are designated by the same reference numerals or similar reference numerals. However, the relationship between the thickness and the plane dimension in the drawing, the ratio of the thickness of each device and each member, etc. are different from the actual ones. Therefore, the specific thickness and dimensions should be determined in consideration of the following explanation. In addition, there are parts where the relationships and ratios of the dimensions of the drawings are different from each other.

-First Embodiment-
<Structure of shearing equipment>
First, the shearing apparatus 10 according to the first embodiment will be described with reference to FIGS. 1 to 7. As shown in FIG. 1, the shearing apparatus 10 is, for example, a crop shear that is arranged in a hot rolling line of a steel mill or the like and cuts an end portion of a steel plate 12 as a work material. The shearing device 10 includes a die 20, a punch 30, a moving device 40, and a holder 50 (see FIG. 3).

The die 20 is the lower blade of the shearing apparatus 10, and is the first surface 22, the second surface 24, and the first surface 22 and the second surface that come into contact with one surface (lower surface in FIG. 3) of the steel plate 12. It has a first ridgeline portion 26 located between 24 and 24. The first surface 22 is almost horizontal. The second surface 24 is substantially vertical and is continuous with the first surface 22 via the first ridge line portion 26. The first ridge line portion 26 extends linearly along the shear direction X (left-right direction in FIG. 1) of the steel plate 12. The entire region of the first ridge 26 from end to end functions as a cutting edge.

The punch 30 is the upper blade of the shearing apparatus 10, and the third surface 32, the fourth surface 34, and the third surface 32 and the fourth surface are in contact with the other surface (upper surface in FIG. 3) of the steel plate 12. It has a second ridgeline portion 36 located between the 34 and the 34th. The third surface 32 is almost horizontal. The fourth surface 34 is substantially vertical and is continuous with the third surface 32 via the second ridge line portion 36. The second ridge line portion 36 extends linearly along the shear direction X of the steel plate 12, similarly to the first ridge line portion 26. The entire region from end to end of the second ridge 36 serves as a cutting edge.

The moving device 40 is provided on the upper side of the punch 30, and can be realized by, for example, an electric motor, a hydraulic pressure mechanism, or the like. Although not shown in each case, the mobile device 40 is provided with a drive device, a speed control device, and the like. In the moving device 40, the second ridge line portion 36 of the punch 30 is placed between a position where the fourth surface 34 of the punch 30 faces the holder 50 and a position where the fourth surface 34 faces the second surface 24 of the die 20. Then, it moves toward the first ridge line portion 26 side of the die 20 along the thickness direction of the steel plate 12. That is, the die 20 and the punch 30 move relative to each other by the moving device 40. The first ridge line portion 26 and the second ridge line portion 36 are close to each other and can be separated from each other. In the first embodiment, the thickness direction of the steel plate 12 is defined as the "relative movement direction Y".

In the present disclosure, the first ridge line portion 26 and the second ridge line portion 36 may move relative to each other so that they are close to each other, and the direction Y of the relative movement is when the punch 30 is pushed toward the die 20. Not limited. The moving device 40 may be provided on the die 20 side and the die 20 may be pushed toward the punch 30, or the moving device 40 may be provided on both sides of the die 20 side and the punch 30 side.

As shown in FIG. 2, the die 20 and the punch 30 each other so that a constant shear angle α is formed between the first ridge portion 26 of the die 20 and the second ridge portion 36 of the punch 30. Have been placed. By performing the shearing process in a state where the shear angle α is applied, the maximum value of the load required for the processing is reduced, and the load on the shearing process device 10 is reduced. Further, as the second ridge line portion 36 descends along the relative movement direction Y, the contact position (shear position) between the second ridge line portion 36 and the steel plate 12 changes along the shear direction X in FIGS. 1 and 1. Move to the right in 2.

The method of the present disclosure is effective regardless of the shear angle α, but in the present disclosure, the shear angle α is 0.5 degrees or more and 10 degrees or less (0.5 degrees ≤ α ≤ 10 degrees). Is preferable. When the shear angle α is less than 0.5 degrees, the shear angle is too small and cutting may be difficult due to the load constraint of the press machine (shearing apparatus). Further, when the shear angle α exceeds 10 degrees, the characteristics of the end face such as post-workability deteriorate.

Further, when the range of the shear angle α is 1 degree or more and 5 degrees or less, the load can be effectively reduced and the characteristics of the end face are maintained, which is more preferable (1 degree ≤ α ≤ 5). Every time). In the first embodiment, the shear angle α is set to about 3 degrees.

The holder 50 is provided on the upper side of the die 20 and supports the steel plate 12 by sandwiching it with the first surface 22 of the die 20 (see FIG. 3). The holder 50 is not essential in the present disclosure. As shown in FIG. 3, the die 20 and the punch 30 are arranged with a constant clearance along the direction Z (left-right direction in FIG. 3) in which the fourth surface 34 and the holder 50 face each other.

In the present disclosure, the clearance is preferably 5% or more and 25% or less of the thickness of the steel sheet 12. If the clearance is less than 5%, the clearance becomes too narrow and a secondary sheared surface is generated on the end face of the steel sheet 12 after shearing, so that there is a concern that ductility may decrease. Further, when the clearance exceeds 25%, the clearance becomes too wide, burrs adhering to the end face are formed relatively large by shearing, and the burden of removing burrs in a later step becomes large. Further, in order to stably secure high ductility of the end face and reduce the probability of occurrence of burrs, it is preferable that the clearance is controlled within the range of 10% or more and 20% or less of the thickness of the steel sheet 12. ..

(1st ridgeline part and 2nd ridgeline part)
Next, the first ridge line portion 26 of the die 20 and the second ridge line portion 36 of the punch 30 will be specifically described. As shown in FIG. 3, the first ridge line portion 26 is composed of a first inclined surface inclined with respect to the first surface 22, and the second ridge line portion 36 is inclined with respect to the third surface 32. It consists of a second inclined surface.

FIG. 3 is a cross-sectional view seen from a direction orthogonal to both the direction Y of the relative movement and the direction Z in which the fourth surface 34 and the holder 50 face each other, that is, a cross-sectional view taken along the shear direction X. .. In the first embodiment, the entire first ridge line portion 26 forms the first inclined surface, and the entire second ridge line portion 36 forms the second inclined surface. The width W of the region of the first inclined surface and the width W of the region of the second inclined surface are equal. Further, the first surface 22 and the third surface 32 are parallel to the direction Z in which the fourth surface 34 and the holder 50 face each other.

Here, in the present disclosure, the first ridge line portion includes at least one of a first inclined surface and a first curved surface (see the first curved surface 26B2 in FIG. 10) inclined with respect to the first surface, and the second. The ridgeline portion of is included at least one of a second inclined surface and a second curved surface (see 36B2 in FIG. 10) inclined with respect to the third surface. Then, when viewed along the shearing direction X, the angle of inclination [degrees], which is the smaller angle formed by the first inclined surface with the first surface, is the smaller angle formed by the second inclined surface with the third surface. The first tilt angle difference ΔCA [degree] is calculated by subtracting the tilt angle [degree].

Then, the radius of curvature difference ΔR [mm] is calculated by subtracting the radius of curvature [mm] of the second curved surface from the radius of curvature [mm] of the first curved surface. Then, the radius of curvature difference ΔR is

ΔCB [degree] = 80 × ΔR ・ ・ ・ Equation (1)

The second inclination angle difference ΔCB is calculated by using it in the equation of.

Equation (1) is a conversion equation introduced to treat the difference in radius of curvature of the curved surface as a quantity equivalent to the difference in inclination angle. For example, when the radius of curvature difference ΔR is 0.1 mm, the second inclination angle difference ΔCB is 8 degrees from the equation (1). Equation (1) is set in consideration of the result of measuring the tensile residual stress of the end face of the product 12A obtained by the shearing method using the shearing apparatus with X-rays. Further, the shearing method is carried out by changing the shear angle α of the shearing apparatus, the first inclination angle difference ΔCA and the second inclination angle difference ΔCB in a plurality of patterns.

Here, it is desirable that the radius of curvature difference ΔR is uniform along the extending direction of the cutting edge (shearing direction X in FIG. 1). When the radius of curvature difference ΔR is non-uniform along the shear direction X in FIG. 1, for example, a partial dent is formed on the cutting edge, the roughness of the fracture surface becomes large, and fatigue characteristics and hydrogen embrittlement resistance become brittle. The embrittlement characteristics are reduced. In the present disclosure, it is a fracture surface that the change width of the radius of curvature difference ΔR in the range of 1 mm along the shear direction X in FIG. 1 is 20% or less of the average value of the radius of curvature difference ΔR in the entire shear direction X. It is preferable in that it can effectively suppress the deterioration of the roughness and the deterioration of the fatigue property and the hydrogen embrittlement resistance property. However, the present disclosure holds even when the radius of curvature difference ΔR is non-uniform along the shear direction X in FIG.

Further, in the present disclosure, when the radius of curvature difference ΔR of the cutting edge is non-uniform in the cross section, the radius of curvature difference ΔR for use in the calculation formula of the present disclosure can be calculated by defining an approximate circle. Specifically, for example, in the cross section of FIG. 4, a recess D is formed between the bottom surface BS and the side surface SS, and curved surfaces are formed on the upper side of the recess D and the lower side of the recess D, respectively. Is illustrated. The bottom surface BS corresponds to the first surface and the third surface of the present embodiment. Further, the side surface SS corresponds to the second surface and the fourth surface of the present embodiment.

The intersection of the contour of the curved surface SC1 on the upper side of the recess D in FIG. 4 and the contour of the side surface SS on the upper side of the curved surface SC1 is defined as “a”. Further, the intersection of the contour of the curved surface SC2 on the lower side of the recess D in FIG. 4 and the contour of the bottom surface BS on the left side of the curved surface SC2 is defined as “b”.

Next, an approximate ellipse P that passes through the intersection a and the intersection b and has the smallest deviation from the cross-sectional profile of the cutting edge composed of the curved surface SC1 and the curved surface SC2 is defined. Specifically, in a plurality of approximate ellipses passing through the intersection a and the intersection b, the separation distance from the cross-sectional profile of the cutting edge along the normal direction at each point on the approximate ellipse is measured. Then, an approximate ellipse is defined in which the total sum of the separation distances in the section sandwiched between the intersection a and the intersection b is minimized. In FIG. 4, the defined approximate ellipse P is illustrated by a broken line.

Next, on the defined approximate ellipse P, the two-division point c where the distances from the intersection a and the intersection b are equal is set on the cross-sectional profile side of the curved surface SC1 and the curved surface SC2 (lower right side in FIG. 4). ). Then, the approximate circle Q that passes through the dichotomous point c and is closest to the bottom surface BS and the side surface SS in the cross section is defined. In FIG. 4, the defined approximate circle Q is illustrated by a chain line. The radius of the defined approximate circle Q can be used as the radius of curvature difference ΔR for use in the formulas of the present disclosure.

Then, the sum of the first inclination angle difference ΔCA and the second inclination angle difference ΔCB is defined as the total inclination angle difference ΔCT. The total tilt angle difference ΔCT is

(0.15 × α ² +0.05 × α + 1) <ΔCT ≦ 40 ・ ・ ・ Equation (2)

Meet. In the present disclosure, the total tilt angle difference ΔCT may be composed of only the first tilt angle difference ΔCA or only the second tilt angle difference ΔCB. In the first embodiment, the first ridge line portion 26 includes only the first inclined surface, and the second ridge line portion 36 includes only the second inclined surface. When the total inclination angle difference ΔCT exceeds 40, the burr formed on the cutting edge becomes too large. Therefore, in the present disclosure, the upper limit of the total tilt angle difference ΔCT is set to 40.

In the first embodiment, the smaller angle formed by the first inclined surface and the first surface 22 is set as the inclined angle C1 [degree]. Further, the smaller angle formed by the second inclined surface and the third surface 32 is set as the inclined angle C2 [degree]. Then, the tilt angle C2 is subtracted from the tilt angle C1 to calculate the first tilt angle difference ΔCA [degree] (ΔCA = C1-C2). In the first embodiment, the first tilt angle difference ΔCA [degree] is

(0.15 × α ² +0.05 × α + 1) <ΔCA ≦ 40 ・ ・ ・ Equation (3)

The shape of the first ridge line portion 26 and the shape of the second ridge line portion 36 are configured so as to satisfy the above conditions. That is, in the first embodiment, the total tilt angle difference ΔCT is composed of only the first tilt angle difference ΔCA, and ΔCT = ΔCA. The above formula (3) of the first embodiment is the formula (2) of the present disclosure.

The above equation (2) means the condition represented by the shaded area in FIG. That is, in the shearing method using the shearing apparatus 10 according to the first embodiment, the conditions of the shear angle α and the first inclination angle difference ΔCA included in the shaded area are used.

The solid locus L1 in FIG. 5 is a part of the curve: ΔCA = 0.15 × α ² + 0.05 × α + 1. Curve: For ΔCA, after shearing is performed by changing the conditions of the shear angle α and the first inclination angle difference ΔCA into a plurality of patterns, the tensile residual stress of the end face of each steel plate 12 product is measured by X-ray. It is obtained by that. At the time of X-ray measurement, the spot diameter was set to 500 μm, and the tensile residual stress in the plate thickness direction was measured at the center position in the plate thickness direction.

Specifically, for example, as shown in Table 1 below, nine shear angles α of 0 degree, 1 degree, 2 degree, 3 degree, 4 degree, 5 degree, 6 degree, 8 degree and 10 degree. In addition to setting the values, in the case of each shear angle α value, five values of 0 degree, 10 degree, 20 degree, 30 degree and 40 degree are set as the first inclination angle difference ΔCA. Then, in each of the patterns in which the shear angle α and the first inclination angle difference ΔCA are combined, the tensile residual stress of the end face of the product of the steel sheet 12 after the shearing process is measured. Further, the tensile residual stress when the first inclination angle difference ΔCA = 0 degree is set as a reference value for each of the nine shear angles α. Then, by comparing the respective tensile residual stresses measured when the first inclination angle difference ΔCA is 10 degrees, 20 degrees, 30 degrees, and 40 degrees with the respective reference values at the corresponding shear angle α, the product is produced. The end face of the above may be evaluated, and the equation (3) may be derived according to the evaluation result.

Table 1 shows the evaluation results of the tensile residual stress of the obtained steel sheet when the shearing process is performed by changing the inclination angle difference of the cutting edge and the shear angle in the shearing processing apparatus. Both Table 2 and Table 3 are tables illustrating specific parameters of each of the 36 examples in Table 1. Specifically, Table 2 is an example in which the first tilt angle difference ΔCA is formed only by the value of the tilt angle C1. Further, Table 3 shows an example in which the first inclination angle difference ΔCA is formed by the difference between the inclination angle C1 and the inclination angle C2.

Further, in Tables 2 and 3, the notation in which "-" is added as the value of the radius of curvature R1 and the radius of curvature R2 means that the cutting edge is not intentionally provided with the radius of curvature, that is, the cutting edge is It means that it is a right-angled blade. Further, in Tables 2 and 3, the notation in which "-" is added as the values of the inclination angle C1 and the inclination angle C2 means that the chamfer is not intentionally provided, that is, the cutting edge is a right-angled blade. Means that.

Further, the third "lower limit equation" from the right side in the uppermost row in Tables 2 and 3 is the left-hand side (0.15 × α2 + 0.05 × α + 1) in the above equations (2) and (3). It is an equation. Therefore, when the value of the second “ΔCT / lower limit equation” from the right in the uppermost row in Tables 2 and 3 exceeds 1, the total inclination angle difference ΔCT is the left side in the above equation (2). It means that the lower limit defined by is satisfied.

The "A" in the "evaluation result" on the far right side of Table 1 means that the tensile residual stress has decreased by 20% or more with respect to the reference value. Further, "B" means that the tensile residual stress is reduced by 10% or more and less than 20% with respect to the reference value. Further, "C" means that the tensile residual stress is reduced by 5% or more and less than 10% with respect to the reference value. Further, "D" means that the tensile residual stress is reduced by less than 5% with respect to the reference value.

For example, when the shear angle α is 0 degrees, the tensile residual stress is reduced by 10% or more in all the measured steel sheets 12 regardless of the magnitude of the first inclination angle difference ΔCA. On the other hand, when the shear angle α is 10 degrees, it can be seen that the magnitude of the reduced tensile residual stress differs depending on the magnitude of the first inclination angle difference ΔCA. When the shear angle α was 10 degrees, the reduced tensile residual stress was larger when the first inclination angle difference ΔCA was 20 degrees than when the first inclination angle difference ΔCA was 10 degrees. Further, the reduced tensile residual stress was larger when the first inclination angle difference ΔCA was 40 degrees than when the first inclination angle difference ΔCA was 20 degrees.

Further, when the shear angle α is 3 to 5 degrees and the first inclination angle difference ΔCA is 10 degrees, 20 degrees, 30 degrees and 40 degrees, the respective tensile residual stress is with respect to the reference value. It was found that an excellent effect of reducing by 20% or more can be obtained. Further, even when the shear angle α is 6 degrees, when the first inclination angle difference ΔCA is 40 degrees, the tensile residual stress is similarly reduced by 20% or more with respect to the reference value, which is an excellent effect. It turned out. Further, as shown in Tables 2 and 3, the same effect can be obtained if the first tilt angle difference ΔCA between the tilt angle C1 and the tilt angle C2 is the same regardless of the presence or absence of the tilt angle C2. I found that I could do it.

The broken line locus L2 in FIG. 5 is a part of the curve: ΔCA = (0.3 × α ² + 0.1 × α + 2). The curve of the locus L2 is also derived according to the measurement result of the tensile residual stress of the end face of the product of the steel plate 12, as in the case of the locus L1. By executing the shearing method so that the first inclination angle difference ΔCA satisfies (0.3 × α ² + 0.1 × α + 2) <ΔCA ≦ 40, the tensile residue of each end face of the product of the steel sheet 12 is obtained. The magnitude of stress can be further reduced.

Since the shape of the first ridge line portion 26 and the shape of the second ridge line portion 36 are configured so that the first inclination angle difference ΔCA satisfies the equation (3) according to the shear angle α at the time of shearing. During shearing, it becomes possible to promote the growth of cracks from the surface of the steel plate 12 on the punch 30 side. By promoting the growth of cracks from the surface of the steel plate 12 on the punch 30 side, it is possible to suppress the tensile residual stress of the end face of the steel plate 12 as a product remaining on the die 20 after shearing.

<Shearing method>
Next, the shearing method according to the first embodiment will be described. First, the shearing apparatus 10 described with reference to FIGS. 1 to 4 is prepared. Next, as shown in FIG. 3, the steel plate 12 is placed on the first surface 22 of the prepared die 20 of the shearing machine 10. As the steel sheet 12, for example, a high-strength steel sheet having a tensile strength of about 980 MPa or more can be adopted. In the first embodiment, a steel plate 12 having a plate thickness of 1.6 mm and a tensile strength of 1180 MPa was used as the material to be processed. The definition of the tensile strength of the steel plate 12 follows, for example, "ISO 6892-1: 2009".

Next, the placed steel plate 12 is supported by the holder 50. Next, the punch 30 is lowered along the thickness direction of the steel plate 12 by the moving device 40 so that the first ridge line portion 26 and the second ridge line portion 36 are close to each other. In the first embodiment, the punching clearance between the die 20 and the punch 30 is set to a value of 10% of the plate thickness (clearance / plate thickness = 0.1). The shear angle α was set to 5 degrees, and the first inclination angle difference ΔCA was set to 20 degrees. In the case of the first embodiment, as a result of observing the cross section of the end portion of the steel plate 12 in the middle of cutting, it was confirmed that cracks were generated from the punch 30 side and cracks were propagated.

Then, as shown in FIG. 6, when the punch 30 is further lowered along the thickness direction of the steel plate 12 by the moving device 40, the growth of cracks from the surface of the steel plate 12 on the punch 30 side is promoted. Then, the steel plate 12 is sheared by the developed crack and cut into the product 12A and the scrap 12B. Each of the above steps realizes the shearing method according to the first embodiment.

FIG. 7 illustrates the results of X-ray measurement (experimental) of tensile residual stress measured along the relative movement direction Y (plate thickness direction) at the end faces of the product 12A and the scrap 12B after shearing. ing. The conditions for the X-ray measurement are the same as the conditions used for the evaluation results of the end faces described in Table 1.

As shown in FIG. 7, in the direction Y of the relative movement, the tensile residual stress of the scrap 12B was about 1200 MPa, while the tensile residual stress of the product 12A was suppressed to a low value of about 200 MPa.

<Comparison example>
On the other hand, as a comparative example, a shearing apparatus is used in which the shape of the first ridge line portion 26 and the shape of the second ridge line portion 36 are configured so that the first inclination angle difference ΔCA does not satisfy the equation (3). Sheared. Specifically, for example, the shearing apparatus according to the comparative example is configured so that the inclination angle C1 = the inclination angle C2 and the first inclination angle difference ΔCA = 0. In the shearing apparatus according to the comparative example, the conditions other than the first inclination angle difference ΔCA were set in the same manner as in the case of the first embodiment, including the size of the shear angle α.

In the case of the comparative example, as a result of observing the cross section of the end portion of the steel plate 12 in the middle of cutting, it was confirmed that cracks were generated from both sides of the punch and the die and that the cracks were grown. Further, in the direction Y of the relative movement, the tensile residual stress of the product 12A was about 700 MPa, which was about 3.5 times larger than the corresponding value of about 200 MPa in the case of the first embodiment.

(Action effect)
In the shearing apparatus 10 according to the first embodiment, the inclination angle C1 of the first inclined surface in the first ridge line portion 26 of the die 20 is changed to the inclination angle C2 of the second inclined surface in the second ridge line portion 36 of the punch 30. The first tilt angle difference ΔCA is calculated by subtracting. The calculated first inclination angle difference ΔCA is the shape of the first ridge line portion 26 and the shape of the second ridge line portion 36 so as to satisfy (0.15 × α ² + 0.05 × α + 1) <ΔCA ≦ 40. And are configured.

Therefore, it is possible to suppress the biting of the blade on the die 20 side into the steel plate 12 during shearing. Further, it promotes the growth of cracks from the surface of the steel plate 12 on the punch 30 side, suppresses the growth of cracks from the surface of the steel plate 12 on the die 20 side, and shortens the growth distance of cracks from the die 20 side. Alternatively, it can be zero. Therefore, even if the steel sheet 12 is sheared with a shear angle, it is possible to prevent a large tensile residual stress from being generated on the end face of the steel sheet 12 remaining on the die 20, and it is possible to prevent fatigue characteristics and hydrogen embrittlement resistance. It is possible to provide a shearing apparatus 10 capable of suppressing deterioration of characteristics.

Further, according to the shearing method using the shearing apparatus 10 according to the first embodiment, even in a state where the shear angle α is applied, a large tensile residue remains on the end face of the steel plate 12 remaining on the die 20. It is possible to prevent the generation of stress and suppress the deterioration of fatigue characteristics and hydrogen embrittlement resistance. In particular, the decrease in hydrogen embrittlement resistance tends to occur in a high-strength steel sheet having a tensile strength of about 980 MPa or more, so that this embodiment is advantageous in shearing a high-strength steel sheet.

Further, there is a method of eliminating work hardening of the end face and preventing the occurrence of tensile residual stress by applying additional shearing such as so-called shaving to the end face after the original shearing. However, according to the first embodiment, when the original shearing process is completed, a large tensile residual stress is prevented from being generated on the end face of the steel sheet 12, so that no additional shearing operation is required. Therefore, the burden on the entire processing work can be reduced.

Further, as a result of research by the present inventors, it was found that the larger the tensile strength of the steel sheet 12, the more easily cracks develop from the surface on the die 20 side when cutting with the shear angle α applied. Therefore, the shearing apparatus 10 according to the first embodiment is effective for a high-strength steel plate having a large tensile strength. In particular, as a result of studies by the present inventors, the tensile residual stress was remarkably reduced for a high-strength steel plate having a tensile strength of about 980 MPa or more.

Further, when cutting a high-strength steel plate having a tensile strength of 980 MPa or more, the hardness of the material of the cutting edge as a tool is 58 Rockwell hardness (HRC) or more in order to suppress the damage of the cutting edge that progresses with the number of cuttings. Is desirable. Further, from the viewpoint of suppressing damage to the cutting edge, it is desirable to apply a coating to the cutting edge separately from the setting of the hardness of the material or together with the setting of the hardness of the material. When the coating is applied, it is more preferable to apply a PVD (Physical Vapor Deposition) coating in that it is easy to prevent deformation and modification of the metal material of the base material. In the present disclosure, the steel plate 12 is not limited to the high-strength steel plate, and the present disclosure can be applied to the shearing of a steel plate having a wide range of strength.

-Second Embodiment-
<Structure of shearing equipment>
Next, the shearing apparatus 10A according to the second embodiment will be described with reference to FIGS. 8 and 9 and Table 4. As shown in FIG. 8, the shearing apparatus 10A includes a die 20A, a punch 30A, a moving apparatus 40, and a holder 50.

FIG. 8 is a cross-sectional view seen from a direction orthogonal to both the direction Y of the relative movement and the direction Z in which the fourth surface 34 and the holder 50 face each other, that is, along the shearing direction X (see FIG. 1). It is a cross-sectional view. Here, in the first embodiment, the first ridge line portion 26 of the die 20 and the second ridge line portion 36 of the punch 30 each have an inclined surface. However, the second embodiment is different from the first embodiment in that the first ridge line portion 26A of the die 20A and the second ridge line portion 36A of the punch 30A each have a curved surface.

Therefore, in the following description of the second embodiment, the first ridge line portion 26A and the second ridge line portion 36A will be mainly described. Further, the configurations other than the first ridge line portion 26A and the second ridge line portion 36A in the shearing machine 10A according to the second embodiment are the same as the members having the same name in the shearing machine 10 according to the first embodiment. Since they are equivalent, duplicate explanations are omitted.

In the second embodiment, as shown in FIG. 8, the first ridge line portion 26A is composed of the first curved surface, and the second ridge line portion 36A is composed of the second curved surface. That is, in the second embodiment, the total tilt angle difference ΔCT of the formula (2) of the present disclosure is composed of only the second tilt angle difference ΔCB, and ΔCT = ΔCB. Here, the radius of curvature of the first curved surface is set to R1 [mm]. Further, the radius of curvature of the second curved surface is set to R2 [mm]. Then, the radius of curvature R2 is subtracted from the radius of curvature R1 to calculate the radius of curvature difference ΔR [mm] (ΔR = R1-R2). In the second embodiment, the calculated radius of curvature difference ΔR [mm] is

(0.001875 × α ² + 0.000625 × α + 0.0125) <ΔR ≦ 0.5
... Equation (4)

The shape of the first ridge line portion 26A and the shape of the second ridge line portion 36A are configured so as to satisfy the above conditions.

Here, when equation (4) is multiplied by 80,

(0.15 × α ² +0.05 × α + 1) <80 × ΔR ≦ 40 ・ ・ ・ Equation (5)

Is obtained. Then, the following equation (6) is obtained from the equations (1) and (5).

(0.15 × α ² +0.05 × α + 1) <ΔCB ≦ 40 ・ ・ ・ Equation (6)

That is, the above formula (6) of the second embodiment is the formula (2) of the present disclosure.

Equation (4) means the condition represented by the shaded area in FIG. That is, in the shearing method using the shearing apparatus 10A according to the second embodiment, the conditions of the shear angle α and the radius of curvature difference ΔR included in the shaded area are used.

The solid locus M1 in FIG. 9 is a part of the curve: ΔR = 0.001875 × α ² + 0.000625 × α + 0.0125. Curve: ΔR is obtained by measuring the tensile residual stress of the end face of each steel plate 12 product with X-ray after performing shearing by changing the conditions of shear angle α and radius of curvature difference ΔR to multiple patterns. Has been obtained.

Specifically, for example, as shown in Table 4 below, nine shear angles α of 0 degree, 1 degree, 2 degree, 3 degree, 4 degree, 5 degree, 6 degree, 8 degree and 10 degree. Set the value. Further, in the case of each value of the shear angle α, six values of 0 mm, 0.1 mm, 0.125 mm, 0.25 mm, 0.375 mm and 0.5 mm are set as the radius of curvature difference ΔR. Then, in each of the patterns in which the shear angle α and the radius of curvature difference ΔR are combined, the tensile residual stress of the end face of the product of the steel sheet 12 after the shearing process is measured.

Further, the tensile residual stress when the radius of curvature difference ΔR = 0 mm is set as a reference value for each of the nine shear angles α. Then, the respective tensile residual stresses measured when the radius of curvature difference ΔR is 0.1 mm, 0.125 mm, 0.25 mm, 0.375 mm and 0.5 mm are set with the respective reference values at the corresponding shear angle α. By comparing, the end faces of the products may be evaluated, and the equation (2) may be derived according to the evaluation result.

Table 4 shows the evaluation results of the tensile residual stress of the obtained steel sheet when the shearing process is performed by changing the difference in the radius of curvature of the cutting edge and the shear angle in the shearing processing apparatus. Tables 5 and 6 are tables illustrating specific parameters of each of the 45 examples in Table 4. Specifically, Table 5 is an example in which the radius of curvature difference ΔR is formed only by the value of the radius of curvature R1. Further, Table 6 is an example in which the radius of curvature difference ΔR is formed by the difference between the radius of curvature R1 and the radius of curvature R2.

Further, in Tables 5 and 6, "-" is added as the value of the radius of curvature R1 and the radius of curvature R2, and "-" is added as the value of the inclination angle C1 and the inclination angle C2. The meanings of the notations are the same as in Tables 2 and 3. Further, the meanings of "lower limit formula" and "ΔCT / lower limit formula" in Tables 5 and 6 are the same as those in Tables 2 and 3.

The “evaluation result” and “A” on the far right in Table 4 mean that the tensile residual stress is reduced by 20% or more with respect to the reference value, as in the case described in Table 1. Further, "B" means that the tensile residual stress is reduced by 10% or more and less than 20% with respect to the reference value. Further, "C" means that the tensile residual stress is reduced by 5% or more and less than 10% with respect to the reference value. Further, "D" means that the tensile residual stress is reduced by less than 5% with respect to the reference value.

For example, when the shear angle α is 0 degrees, the tensile residual stress is reduced by 10% or more in all the measured steel plates 12 regardless of the magnitude of the radius of curvature difference ΔR. On the other hand, when the shear angle α is 10 degrees, it can be seen that the magnitude of the reduced tensile residual stress differs depending on the magnitude of the radius of curvature difference ΔR. When the shear angle α was 10 degrees, the reduced tensile residual response was larger when the radius of curvature difference ΔR was 0.25 mm than when the radius of curvature difference ΔR was 0.1 mm and 0.125 mm. Further, when the radius of curvature difference ΔR was 0.5 mm, the reduced tensile residual stress was larger than when the radius of curvature difference ΔR was 0.375 mm.

Further, when the shear angle α is 3 to 5 degrees, the respective tensile residual stresses are in all cases where the radius of curvature difference ΔR is 0.1 mm, 0.125 mm, 0.25 mm, 0.375 mm and 0.5 mm. It was found that an excellent effect of 20% or more reduction with respect to the standard value can be obtained. Further, even when the shear angle α is 6 degrees, when the radius of curvature difference ΔR is 0.5 mm, it is possible to obtain an excellent effect that the tensile residual stress is similarly reduced by 20% or more with respect to the reference value. Do you get it. Further, as shown in Tables 5 and 6, the same effect can be obtained if the radius of curvature difference ΔR between the radius of curvature R1 and the radius of curvature R2 is the same regardless of the presence or absence of the radius of curvature R2. Do you get it.

The broken line locus M2 in FIG. 9 is a part of the curve: ΔR = 0.00375 × α ² + 0.00125 × α + 0.025. The curve of the locus M2 is also derived according to the measurement result of the tensile residual stress of the end face of the product of the steel plate 12, as in the case of the locus M1. By executing the shearing method so that the radius of curvature difference ΔR satisfies (0.00375 × α ² + 0.00125 × α + 0.025) <ΔR ≦ 0.5, each of the end faces of the product of the steel plate 12 is obtained. The magnitude of the residual stress can be further reduced.

Since the shapes of the first ridge line portion 26A and the second ridge line portion 36A are configured so that the radius of curvature difference ΔR satisfies the equation (4) according to the shear angle α during shearing, the punch 30A is formed during shearing. It becomes possible to promote the growth of cracks from the surface of the steel plate 12 on the side. By promoting the growth of cracks from the surface of the steel plate 12 on the punch 30A side, it is possible to suppress the residual stress of the end face of the steel plate 12 as a product remaining on the die 20A after shearing. Since the shearing method using the shearing apparatus 10A according to the second embodiment is the same as the shearing method using the shearing apparatus 10 according to the first embodiment, duplicate description will be omitted. ..

(Action effect)
In the shearing apparatus 10A according to the second embodiment, the radius of curvature R1 of the first curved surface in the first ridge line portion 26A is subtracted from the radius of curvature R2 of the second curved surface in the second ridge line portion 36A, and the radius of curvature difference ΔR Is calculated. When the calculated radius of curvature difference ΔR satisfies (0.001875 × α ² + 0.000625 × α + 0.0125) <ΔR ≦ 0.5, the first equation (2) of the present disclosure holds. The shapes of the ridge line portion 26A and the second ridge line portion 36A are configured. Therefore, also in the second embodiment, it is possible to suppress the biting of the blade on the die 20A side into the steel plate 12 during shearing. Further, it promotes the growth of cracks from the surface of the steel plate 12 on the punch 30A side, suppresses the growth of cracks from the surface of the steel plate 12 on the die 20A side, and shortens the growth distance of cracks from the die 20A side. Alternatively, it can be zero.

Therefore, as in the case of the first embodiment, even if the steel sheet 12 is sheared with the shear angle α applied, a large residual stress is generated on the end face of the steel sheet 12 remaining on the die 20A. It can be prevented, and deterioration of fatigue characteristics and hydrogen embrittlement resistance can be suppressed. Other effects of the shearing apparatus 10A according to the second embodiment are the same as those of the first embodiment.

-Third Embodiment-
<Structure of shearing equipment>
Next, the shearing apparatus 10B according to the third embodiment will be described with reference to FIG. As shown in FIG. 10, the shearing apparatus 10B includes a die 20B, a punch 30B, a moving apparatus 40, and a holder 50. FIG. 10 is a cross-sectional view seen from a direction orthogonal to both the direction Y of the relative movement and the direction Z in which the fourth surface 34 and the holder 50 face each other, that is, along the shearing direction X (see FIG. 1). It is a cross-sectional view.

Here, in the first embodiment, the entire first ridge line portion 26 of the die 20 and the entire second ridge line portion 36 of the punch 30 are inclined surfaces. Further, in the second embodiment, the entire first ridge line portion 26A of the die 20A and the entire second ridge line portion 36A of the punch 30A are both curved surfaces. However, the third embodiment is different from the first and second embodiments in that the first ridge line portion 26B of the die 20B has a partially combined inclined surface and curved surface. Further, the second ridge line portion 36B of the punch 30B also has a partial combination of the inclined surface and the curved surface corresponding to the inclined surface and the curved surface of the first ridge line portion 26B, respectively, in the first and second embodiments. Different from the morphology. That is, in the third embodiment, the total tilt angle difference ΔCT of the formula (2) of the present disclosure is composed of the sum of the first tilt angle difference ΔCA and the second tilt angle difference ΔCB, and ΔCT = ΔCA + ΔCB.

In the following description of the third embodiment, the first ridge line portion 26B and the second ridge line portion 36B will be mainly described. Further, regarding the configurations other than the first ridge line portion 26B and the second ridge line portion 36B in the shearing machine 10B according to the third embodiment, the shearing machines 10 and 10A according to the first and second embodiments have. Since they are equivalent to the members with the same name, duplicate explanations will be omitted.

In the third embodiment, as shown in FIG. 10, the first ridge line portion 26B includes a first inclined surface 26B1 inclined with respect to the first surface 22 and a first curved surface 26B2. Further, the second ridge line portion 36B is composed of a second inclined surface 36B1 inclined with respect to the third surface 32 and a second curved surface 36B2. The first surface 22 and the third surface 32 are parallel to the direction Z in which the fourth surface 34 and the holder 50 face each other.

Here, the smaller angle formed by the first inclined surface 26B1 and the first surface 22 is set as the inclined angle C1A [degree]. Further, the smaller angle formed by the second inclined surface 36B1 and the third surface 32 is set as the inclined angle C2A [degree]. Then, the tilt angle C2A is subtracted from the tilt angle C1A to calculate the first tilt angle difference ΔCA [degree] (ΔCA = C1A—C2A).

On the other hand, the radius of curvature of the first curved surface 26B2 is set to R1 [mm]. Further, the radius of curvature of the second curved surface 36B2 is set to R2 [mm]. Then, the radius of curvature R2 is subtracted from the radius of curvature R1 to calculate the radius of curvature difference ΔR [mm] (ΔR = R1-R2). Further, the second inclination angle difference ΔCB [degree] is calculated from the above equation (1) using the radius of curvature difference ΔR.

Then, the sum of the calculated first inclination angle difference ΔCA [degree] and the calculated second inclination angle difference ΔCB [degree] is set as the total inclination angle difference ΔCT [degree]. In the third embodiment, the shape of the first ridge line portion 26B and the shape of the second ridge line portion 36B are configured so that the total inclination angle difference ΔCT [degree] satisfies the formula (2) of the present disclosure. ..

Therefore, during shearing, it becomes possible to promote the growth of cracks from the surface of the steel plate 12 on the punch 30B side. By promoting the growth of cracks from the surface of the steel plate 12 on the punch 30B side, it is possible to suppress the tensile residual stress of the end face of the steel plate 12 as a product remaining on the die 20B after shearing.

Since each step included in the shearing method using the shearing apparatus 10B according to the third embodiment is the same as that of the first and second embodiments, duplicate description will be omitted.

Also in the third embodiment, similarly to the first embodiment and the second embodiment, the shearing process was performed by changing the shear angle α in the shearing processing apparatus, and the evaluation result of the tensile residual stress of the steel sheet was obtained. In the third embodiment, nine values of 0 degree, 1 degree, 2 degree, 3 degree, 4 degree, 5 degree, 6 degree, 8 degree and 10 degree are set as the shear angle α. Further, the radius of curvature difference ΔR was set to 0.1 mm, and the first inclination angle difference ΔCA was set to 18 degrees. Then, in each pattern of the nine shear angles α, the tensile residual stress of the end face of the product of the steel sheet 12 after the shearing process was measured.

Further, in the shearing process of the third embodiment, three types of steel sheets, a high-strength steel sheet having a tensile strength of 1180 MPa, a high-strength steel sheet having a tensile strength of 980 MPa, and a steel sheet having a tensile strength of 590 MPa, were used as the steel sheet 12. .. Table 7 shows the evaluation results using 1180 MPa high-strength steel sheets, Table 8 shows the evaluation results using 980 MPa high-strength steel sheets, and Table 9 shows the evaluation results using 590 MPa high-strength steel sheets. It is shown together with the specific parameters of the examples of. The other measurement methods and evaluation methods in the third embodiment are the same as those in the first embodiment and the second embodiment.

“A” in the “evaluation result” on the far right in Tables 7 to 9 means that the tensile residual stress is reduced by 20% or more with respect to the reference value, as in the case described in Table 1. Further, "B" means that the tensile residual stress is reduced by 10% or more and less than 20% with respect to the reference value. Further, "C" means that the tensile residual stress is reduced by 5% or more and less than 10% with respect to the reference value. Further, "D" means that the tensile residual stress is reduced by less than 5% with respect to the reference value.

In Tables 7 to 9, the meaning of the notation in which "-" is added as the value of the inclination angle C2 is the same as in the cases of Tables 2 and 3. Further, the meanings of "lower limit formula" and "ΔCT / lower limit formula" in Tables 7 to 9 are the same as those in Tables 2 and 3.

As shown in Tables 7 to 9, when the shear angle α is 5 degrees and when the shear angle α is 6 degrees, the evaluation result of the 590 MPa steel sheet is “B”, whereas the evaluation result is 980 MPa. The evaluation results of the high-strength steel sheet and the high-strength steel sheet of 1180 MPa were both "A". In this embodiment, particularly when the shear angle α is 5 degrees and when the shear angle α is 6 degrees, the high-strength steel sheet of 980 MPa or more has lower fatigue characteristics and hydrogen embrittlement resistance than the steel sheet of 590 MPa. It was found that the effect of suppressing the problem was great.

(Action effect)
According to the shearing apparatus 10B according to the third embodiment, from the inclination angle C1A of the first inclined surface 26B1 in the first ridge portion 26B of the die 20B to the second inclined surface 36B1 in the second ridge portion 36B of the punch 30B. The first tilt angle difference ΔCA is calculated by subtracting the tilt angle C2A. Further, the radius of curvature difference ΔR is calculated by subtracting the radius of curvature R2 of the second curved surface 36B2 in the second ridge portion 36B of the punch 30B from the radius of curvature R1 of the first curved surface 26B2 in the first ridge portion 26B of the die 20B. Will be done. Further, according to the equation (1) of ΔCB = 80 × ΔR, the radius of curvature difference ΔR is converted as the second inclination angle difference ΔCB. Further, the total tilt angle difference ΔCT is calculated as the sum of the first tilt angle difference ΔCA and the second tilt angle difference ΔCB.

Then, the shape of the first ridge line portion 26B and the shape of the second ridge line portion 36B are configured so that the total inclination angle difference ΔCT satisfies (0.15 × α ² + 0.05 × α + 1) <ΔCT ≦ 40. Has been done. Therefore, even when the ridgeline portion includes both the inclined surface and the curved surface, it is possible to suppress the biting of the blade on the die 20B side into the steel plate 12 during shearing. Further, it promotes the growth of cracks from the surface of the steel plate 12 on the punch 30B side, suppresses the growth of cracks from the surface of the steel plate 12 on the die 20B side, and shortens the growth distance of cracks from the die 20B side. Alternatively, it can be zero.

Therefore, as in the case of the first and second embodiments, even if the steel sheet 12 is sheared with the shear angle α applied, a large tensile residual stress is applied to the end face of the steel sheet 12 remaining on the die 20B. Can be prevented from occurring, and deterioration of fatigue characteristics and hydrogen embrittlement resistance can be suppressed. Other effects of the shearing apparatus 10B according to the third embodiment are the same as those of the first and second embodiments.

<Modification example>
In the first to third embodiments, a shearing apparatus and a shearing method for cutting the end portion of the steel sheet 12 have been exemplified, but the present disclosure is not limited thereto. For example, as shown in FIGS. 11 and 12, the present disclosure is also applicable to shearing equipment and shearing methods used for press working such as punching or punching.

The shearing device 10C illustrated in FIG. 11 includes a die 20C, a punch 30C, a moving device 40, and a holder (not shown). The die 20C is a lower blade of the shearing apparatus 10C and has a first surface 22C in contact with one surface (upper surface in FIG. 11) of the steel plate 12. Further, the shearing apparatus 10C has a second surface 24C continuous with the first surface 22C and a first ridge line portion 26C located between the first surface 22C and the second surface 24C.

A recess is provided in the center of the first surface 22C, and the second surface 24C forms an inner wall surface of the recess. That is, the first ridge line portion 26C appears as the outer edge of the recess. The lower portion of the punch 30C is inserted into the recess, and the steel plate 12 is punched out according to the shape of the outer edge of the recess. On the upper surface of the steel plate 12 in FIG. 11, the outer edge of the punched portion of the steel plate 12 is exemplified by the region V surrounded by the alternate long and short dash line. Although not shown in FIG. 11, a holder can be provided with a gap around the region V on the upper surface of the steel plate 12. The outer edge and region V of the recess of the die 20C illustrated in FIG. 11 have a rectangular shape with four curved corners in a plan view, but the present disclosure is not limited to this, and other geometric shapes such as a circle can be formed. Can be changed as appropriate.

The punch 30C is the upper blade of the shearing apparatus 10C and has a third surface 32C (lower surface in FIG. 11) in contact with the other surface of the steel plate 12. Further, the shearing apparatus 10C has a fourth surface 34C (side surface) continuous with the third surface 32C, and a second ridge line portion 36C located between the third surface 32C and the fourth surface 34C.

In the modified example, the die 20C and the punch 30C are arranged so as to face each other in the vertical direction so that the third surface 32C of the punch 30C is inclined with respect to the first surface 22C of the die 20C. Therefore, a constant shear angle α is formed between the first ridge line portion 26C of the die 20C and the second ridge line portion 36C of the punch 30C.

In the case of punching using the shearing apparatus 10C according to the modified example, when the punch 30C descends along the direction Y of relative movement, the second punch 30C located at the lower end of the leftmost punch 30C in FIG. 11 first. The ridge line portion 36C comes into contact with the steel plate 12. Then, the contact position (shear position) between the second ridge line portion 36C and the steel plate 12 moves to the right side in FIG. 11 along the shear direction X.

In the case of the modified example, the shape of the outer edge of the first ridge line portion 26C and the second ridge line portion 36C, which are the cutting edges, in a plan view is circular so as to form a closed space inside. is not it. Therefore, the direction Z in which the fourth surface 34C and the holder face each other is not specified in one direction as in the case of the first to third embodiments. With respect to an arbitrary position on the outer edge of the region V on the upper surface of the steel plate 12, the direction Z in which the fourth surface 34C and the holder face each other is the direction of the normal at this arbitrary position.

For example, in FIG. 11, the four sides of the rectangle of the outer edge of the region V include a set of long sides parallel to the top and bottom and a set of short sides parallel to the left and right. When the first ridge line portion 26C and the second ridge line portion 36C are located on the long side of the four sides of the rectangle of the region V, the direction Z in which the fourth surface 34C and the holder face each other is on the upper surface of the steel plate 12. Can be set in a direction orthogonal to the shear direction X.

Further, when the first ridge line portion 26C and the second ridge line portion 36C are located on the short side of the four sides of the rectangle of the region V, the direction Z in which the fourth surface 34C and the holder face each other is the shear direction X. Can be set in the same direction as. That is, the direction Z in which the fourth surface 34C and the holder face each other changes depending on an arbitrary position on the upper surface of the steel plate 12 in which the direction Z is set.

Also in the modified example, the first ridge line portion 26C is relative to the first surface 22C when viewed from a direction orthogonal to both the relative movement direction Y and the direction Z in which the fourth surface 34 and the holder 50 face each other. It has a first inclined surface that is inclined. Further, the second ridge line portion 36C has a second inclined surface inclined with respect to the third surface 32C.

Further, also in the modified example, as in the case of the first embodiment, the smaller angle formed by the first inclined surface in the direction Z in which the fourth surface 34C and the holder 50 face each other is set as the inclined angle C1. Further, the smaller angle formed by the second inclined surface in the direction Z in which the fourth surface 34C and the holder 50 face each other is set as the inclination angle C2. Then, the tilt angle C2 is subtracted from the tilt angle C1 to calculate the first tilt angle difference ΔCA (ΔCA = C1-C2). Further, the shape of the first ridge line portion 26C and the shape of the second ridge line portion 36C are configured so that the first inclination angle difference ΔCA satisfies the formula (2) of the present disclosure.

Since the other configurations of the shearing apparatus 10C according to the modified example are equivalent to the members having the same name in the shearing apparatus 10, 10A, 10B according to the first to third embodiments, duplicate description will be omitted. Further, each step included in the shearing method using the shearing apparatus 10C according to the modified example is the same as in the case of the first to third embodiments.

Also in the modified example, as in the case of the first to third embodiments, even if the steel plate 12 is sheared with the shear angle α applied, the end face of the steel plate 12 remaining on the die 20C is large. It is possible to prevent the occurrence of tensile residual stress and suppress the deterioration of fatigue characteristics and hydrogen embrittlement resistance. Other effects of the shearing apparatus 10C according to the modified example are the same as in the case of the first embodiment.

The shear angle α is not constant and may be partially different within the range in which the first ridge line portion and the second ridge line portion exist. For example, FIG. 12 illustrates a first ridge line portion 26C1 that orbits so as to form a closed space inside as in the modified example.

The overall shape of the outer edge of the first ridge line portion 26C1 is elliptical in a plan view, and the upper central portion in FIG. 12 is recessed toward the lower side. Here, in FIG. 12, in the first ridge line portion 26C1, the section between the division point 60 on the left side of the depression and the division point 62 on the right side of the depression is set as A1. Further, in the first ridge line portion 26C1, the section on the left side in FIG. 12 is set as A2 between the division point 60 and the division point 64 located on the opposite side of the section A1. Further, in the first ridge line portion 26C1, the section on the right side in FIG. 12 is set as A3 between the division point 62 and the division point 64.

In the case of the die 20C illustrated in FIG. 12, for example, the shear angle α in the section A1 is about 3 degrees, the shear angle α in the section A2 is 0 degrees, and the shear angle α in the section A1 is about 10 degrees. Can be set. By partially different shear angles α in the first ridge line portion and the second ridge line portion, the magnitude of the tensile residual stress allowed in the end face of the steel sheet product after punching is determined according to the position. It becomes possible to make them different.

The method of forming the respective shapes of the first ridge line portion and the second ridge line portion so that the shear angle α is partially different is not limited to the case of punching, and is not limited to the case of punching, and is described in the first to third embodiments. As described above, even when the first ridge line portion and the second ridge line portion extend linearly, it can be adopted.

(How to check the shear angle)
Further, as a method of objectively confirming the size of the shear angle α on the first ridgeline portion or the second ridgeline portion, for example, a region having a certain width in a plan view is set on the ridgeline portion. , It is also possible to use a plurality of measured values extracted in the set area. Specifically, for example, as shown in FIG. 12, in a plan view, on the outer edge of the first ridge line portion 26C1, with a specific center point B as the center, along the extending direction of the tangent line at the center point B. A region having a constant width D on the left and right is set. The width D can be set to, for example, about 3 mm.

Then, in the portion included in the set region, the shear angle α between the first ridge line portion 26C1 and the second ridge line portion is measured at several points. Then, for example, when the shear angle α is defined as 3 degrees, the average value of a plurality of measured shear angles α is calculated in the portion included in the set area, and the calculated average value is regarded as 3 degrees. The shear angle α can be determined to be 3 degrees as long as it is within the range that can be considered. The specified range can be set, for example, 3 degrees ± 0.5 degrees.

<Other embodiments>
Although the present disclosure has been described by the embodiments disclosed above, this description is not limiting the present disclosure. It should be considered from this disclosure to those skilled in the art that various alternative embodiments, examples and operational techniques will be revealed.

For example, in the first to third embodiments, the case where the holder 50 is provided has been exemplified as a basic configuration, but in the present disclosure, even if the holder 50 is not provided, the die side of the steel plate 12 is provided. It can promote the growth of cracks from the surface. Further, for example, it is not essential that the actual pressing force applied to the steel plate 12 by the holder 50 always achieves the specification value set in the holder 50. Even if the actual pressing force of the holder 50 is lower than the specified value, the same effect as in the case of the first to third embodiments can be obtained.

Further, the shearing apparatus according to the present disclosure can realize a pattern in which not only the portion of the steel plate 12 remaining on the die but also the portion of the steel plate extruded by a punch is a product. Specifically, by exchanging the dies and punches described in the first to third embodiments with each other, the surface of the steel sheet 12 whose crack growth is desired can be inverted.

That is, the definitions of the die and the punch and the direction of gravity in the shearing apparatus described with reference to FIGS. 1 to 12 are merely examples, and may be read in reverse with each other. In the present disclosure, the respective definitions of the die and the punch and the direction of gravity are merely examples, and even when they are reversed from each other, the technical idea is equivalent to that of the first to third embodiments. Can be included.

The present disclosure can also be configured by partially combining the structures of the shearing apparatus shown in FIGS. 1 to 12. The present disclosure includes various embodiments not described above, and the technical scope of the present disclosure is defined only by the matters specifying the invention within the scope of claims reasonable from the above description.

10,10A,10B, 10C Shearing device 20,20A, 20B, 20C Die 22,22C First surface 24,24C Second surface 26, 26A, 26B, 26C, 26C1 First ridge line portion 26B1 First inclined surface 26B2 First curved surface 30, 30A, 30B, 30C Punch 32, 32C Third surface 34, 34C Fourth surface 36, 36A, 36B, 36C Second ridge line portion 36B1 Second inclined surface 36B2 Second curved surface 40 Moving device 50 Holders C1, C1A, C2, C2A Tilt angle R1, R2 Radiation of curvature X Shear direction Y Relative movement direction Z Direction in which the fourth surface and the holder face each other α Shear angle ΔCA First tilt angle difference ΔCB Second tilt angle difference ΔCT Total Inclination angle difference ΔR radius of curvature difference

Claims (8)

A die having a first surface in contact with one surface of a steel sheet and a second surface continuous with the first surface via a first ridge line portion as a cutting edge.
A third surface continuous with the third surface via a third surface in contact with the other surface of the steel sheet and a second ridge line portion which is a cutting edge forming a shear angle α with the first ridge line portion. A punch with four sides and
A holder that sandwiches the steel sheet between the die and the first surface of the die,
Along the thickness direction of the steel plate, the die or the punch is placed between a position where the fourth surface of the punch faces the holder and a position where the fourth surface faces the second surface of the die. Equipped with a moving device that moves relative to each other
The first ridge line portion includes at least one of a first inclined surface and a first curved surface inclined with respect to the first surface, and the second ridge line portion is a second inclined surface with respect to the third surface. 2 includes at least one of an inclined surface and a second curved surface, including
Seen from the direction orthogonal to both the direction of the relative movement and the direction in which the fourth surface and the holder face each other.
From the tilt angle [degrees], which is the smaller angle formed by the first inclined surface with the first surface, the tilt angle [degrees], which is the smaller angle formed by the second inclined surface with the third surface, is subtracted. First tilt angle difference ΔCA [degrees] and
The radius of curvature difference ΔR [mm] obtained by subtracting the radius of curvature [mm] of the second curved surface from the radius of curvature [mm] of the first curved surface.
ΔCB [degree] = 80 × ΔR
The second tilt angle difference ΔCB is calculated by using it in the equation of.
When the sum of the first tilt angle difference ΔCA and the second tilt angle difference ΔCB is the total tilt angle difference ΔCT, the total tilt angle difference ΔCT is
(0.15 × α ² +0.05 × α + 1) <ΔCT ≦ 40
Meet, meet
Shearing equipment. The first ridge line portion is composed of the first inclined surface, and the second ridge line portion is formed of the second inclined surface.
The shearing apparatus according to claim 1. The first ridge line portion is made of the first curved surface, and the second ridge line portion is made of the second curved surface.
The shearing apparatus according to claim 1. The first ridge line portion is composed of the first inclined surface and the first curved surface, and the second ridge line portion is composed of the second inclined surface and the second curved surface.
The shearing apparatus according to claim 1. The shear angle α is 0.5 degrees or more and 10 degrees or less.
The shearing apparatus according to any one of claims 1 to 4. The clearance between the die and the punch is 5% or more and 25% or less of the thickness of the steel sheet.
The shearing apparatus according to any one of claims 1 to 5. The step of preparing the shearing apparatus according to any one of claims 1 to 6 and
A step of placing a steel plate on the first surface of the die of the prepared shearing device, and
A step of supporting the mounted steel plate by the holder, and
A step of cutting the steel sheet by relatively moving the die or the punch using the moving device along the thickness direction of the steel sheet so that the first ridge line portion and the second ridge line portion are close to each other. When,
Shearing methods, including. The tensile strength of the steel sheet is 980 MPa or more.
The shearing method according to claim 7.

Images