WO2023112390A1 - 金属板の曲げ加工部の疲労き裂進展抑制方法及び自動車部品 - Google Patents
金属板の曲げ加工部の疲労き裂進展抑制方法及び自動車部品 Download PDFInfo
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- WO2023112390A1 WO2023112390A1 PCT/JP2022/031204 JP2022031204W WO2023112390A1 WO 2023112390 A1 WO2023112390 A1 WO 2023112390A1 JP 2022031204 W JP2022031204 W JP 2022031204W WO 2023112390 A1 WO2023112390 A1 WO 2023112390A1
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- bent portion
- metal plate
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- 239000002184 metal Substances 0.000 title claims abstract description 63
- 238000000034 method Methods 0.000 title claims abstract description 42
- 238000005452 bending Methods 0.000 claims abstract description 80
- 238000007373 indentation Methods 0.000 claims description 25
- 206010053759 Growth retardation Diseases 0.000 claims 1
- 238000009661 fatigue test Methods 0.000 description 20
- 238000011282 treatment Methods 0.000 description 16
- 238000005480 shot peening Methods 0.000 description 8
- 238000010586 diagram Methods 0.000 description 6
- 230000000694 effects Effects 0.000 description 6
- 239000000463 material Substances 0.000 description 6
- 238000004519 manufacturing process Methods 0.000 description 5
- 229910000831 Steel Inorganic materials 0.000 description 3
- 230000000052 comparative effect Effects 0.000 description 3
- 238000005336 cracking Methods 0.000 description 3
- 230000007423 decrease Effects 0.000 description 3
- 230000000977 initiatory effect Effects 0.000 description 3
- 239000010959 steel Substances 0.000 description 3
- 238000010276 construction Methods 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 238000007689 inspection Methods 0.000 description 2
- 230000007935 neutral effect Effects 0.000 description 2
- 230000035939 shock Effects 0.000 description 2
- 239000007921 spray Substances 0.000 description 2
- 238000004458 analytical method Methods 0.000 description 1
- 238000005422 blasting Methods 0.000 description 1
- 238000010288 cold spraying Methods 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 125000004122 cyclic group Chemical group 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 230000000873 masking effect Effects 0.000 description 1
- 230000000737 periodic effect Effects 0.000 description 1
- 230000002265 prevention Effects 0.000 description 1
- 230000002250 progressing effect Effects 0.000 description 1
- 230000000644 propagated effect Effects 0.000 description 1
- 238000005482 strain hardening Methods 0.000 description 1
- 230000037303 wrinkles Effects 0.000 description 1
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Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D22/00—Shaping without cutting, by stamping, spinning, or deep-drawing
- B21D22/20—Deep-drawing
- B21D22/26—Deep-drawing for making peculiarly, e.g. irregularly, shaped articles
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D5/00—Bending sheet metal along straight lines, e.g. to form simple curves
- B21D5/01—Bending sheet metal along straight lines, e.g. to form simple curves between rams and anvils or abutments
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23P—METAL-WORKING NOT OTHERWISE PROVIDED FOR; COMBINED OPERATIONS; UNIVERSAL MACHINE TOOLS
- B23P9/00—Treating or finishing surfaces mechanically, with or without calibrating, primarily to resist wear or impact, e.g. smoothing or roughening turbine blades or bearings; Features of such surfaces not otherwise provided for, their treatment being unspecified
- B23P9/04—Treating or finishing by hammering or applying repeated pressure
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D7/00—Modifying the physical properties of iron or steel by deformation
- C21D7/02—Modifying the physical properties of iron or steel by deformation by cold working
- C21D7/04—Modifying the physical properties of iron or steel by deformation by cold working of the surface
- C21D7/06—Modifying the physical properties of iron or steel by deformation by cold working of the surface by shot-peening or the like
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
Definitions
- the present invention provides a method for suppressing fatigue crack growth in a bent portion of a metal sheet, which suppresses the growth of fatigue cracks in the bent portion of the metal sheet. suppressing method), and an automotive part that has a bent portion formed by bending a metal plate and suppresses the propagation of fatigue cracks in the bent portion.
- Patent Literature 1 and Patent Literature 2 describe a technique for suppressing the occurrence of cracks on the inner side of a local bend that constitutes the root of a burring portion during coining of a metal plate. ing. Specifically, in this technique, bending is performed with a radius of curvature different from the final shape (including an infinite curvature radius, that is, a straight line) in the first step, and the curvature radius of the final shape is performed in the second step. Cracking on the inside surface of the bend is suppressed by bending to introduce tensile stress on the inside surface of the bend.
- Patent Document 3 a surface hardening treatment by shot peening is applied to the surface of a metal plate to which a bending stress is applied, thereby increasing the yield stress and increasing the yield stress after shot peening.
- Patent Literature 4 describes a technique for repairing fatigue cracks occurring in curved plate portions of steel materials. Specifically, this technology closes the opening of the fatigue crack by peening at least one of the two sides of the fatigue crack on the steel surface parallel to the fatigue crack. Peening directly above.
- Patent Document 1 With the technology described in Patent Document 1, there are two processes for bending, so two types of molds need to be prepared, which raises the problem of high manufacturing costs.
- the technique described in Patent Literature 2 has a problem that the applicable portion is limited to the burring portion.
- the technique described in Patent Document 3 since shot peening is used, it was necessary to perform processing in a sealed container in order to prevent scattering of the projection material.
- the technique described in Patent Document 4 is a method of peening a flat plate or weld toe using an air hammer peening device.
- problems (a) to (c) occur when applying to a part having a bent portion formed by bending a metal plate.
- the present invention has been made to solve the above problems, and its object is to be applicable to a bent portion after bending without increasing the manufacturing cost of bending a metal plate.
- a method for suppressing the growth of fatigue cracks in a bent portion of a metal plate, capable of suppressing the propagation of fatigue cracks in the bent portion without reducing productivity and without changing the bending angle of the entire part or the bent portion is to provide
- Another object of the present invention is to provide an automobile part that has a bent portion formed by bending a metal plate and suppresses the propagation of fatigue cracks in the bent portion.
- a method for suppressing fatigue crack propagation in a bent portion of a metal plate according to the present invention suppresses propagation of a fatigue crack in a bent portion obtained by bending a metal plate, and comprises: (valley line direction) with a space less than the plate thickness of the metal plate, in a direction orthogonal to the valley line direction, at least from the bending start point on the inner side of the bending portion to the bending end point A plastic strain is applied within the range up to the bending end point to generate compressive residual stress.
- the compressive residual stress is generated by forming an indentation band, which is a series of indentations, on the inner side of the bent portion by needle peening treatment using an impact pin.
- the striking pin has a radius of curvature in a cross section perpendicular to the direction of the valley line at the tip of the striking pin that is equal to or less than the radius of curvature of the bent portion.
- An automobile part according to the present invention has a bent portion obtained by bending a metal plate, suppresses the propagation of fatigue cracks in the bent portion, and Needle peening treatment using an impact pin at least within the range from the bending start point to the bending end point on the inner side of the bend of the bent portion in the direction perpendicular to the valley line direction with a space less than the plate thickness of the metal plate. It has an indentation band, which is a series of impact marks caused by
- the present invention it is possible to suppress the propagation of cracks that occur in the bent portion obtained by bending a metal plate, and to effectively improve the fatigue life of automobile parts having the bent portion.
- FIG. 1 is a diagram for explaining a method for suppressing fatigue crack propagation in a bent portion of a metal plate according to Embodiment 1 of the present invention and an automobile component according to Embodiment 2 of the present invention ((a) bending (b) a cross-sectional view, (c) an enlarged view of the bent portion).
- FIG. 2 is a diagram illustrating the progress of fatigue cracks in a bent portion and the concept of suppressing the growth of the fatigue cracks as the background to the present invention ((a) normal (general) Crack growth in metal plate, (b) Crack growth in bent portion).
- 3A and 3B are diagrams for explaining the stress distribution in the bent portion in the background to the present invention ((a) immediately after bending, (b) after springback).
- FIG. 1 is a diagram for explaining a method for suppressing fatigue crack propagation in a bent portion of a metal plate according to Embodiment 1 of the present invention and an automobile component according to Embodiment 2 of the present invention ((a) bending
- FIG. 4 is a graph showing the results of examining the stress intensity factor at the crack tip of the crack generated in the bending part in the process leading to the present invention ((a) crack fracture surface (crack surface), (b) stress intensity factors in the depth direction and lateral direction at the crack fracture surface).
- FIG. 5 is a diagram showing a fatigue test piece used in a fatigue test in an example of the present invention ((a) front view, (b) cross-sectional view).
- FIG. 6 is a diagram explaining a fatigue test method in an embodiment of the present invention.
- Fatigue cracks occurring on the surface of the metal plate generally extend laterally (along the surface of the metal plate 1) and in the depth direction from the location where the crack 5 occurs, as shown in FIG.
- a semi-elliptic crack fracture surface expands in both directions (thickness direction of the metal plate 1) and propagates. Then, the crack fracture surface reaches the back surface side of the metal plate 1, resulting in fatigue fracture.
- the inventor observed in detail the propagation process of fatigue cracks generated on the inner side of bending of the bent portion 3 obtained by bending the metal plate 1.
- the crack 5 generated on the inner side of the bend of the bent portion 3 immediately after the crack 5 occurs in the depth direction (thickness direction of the metal plate 1) and the lateral direction (the valley line direction of the inner side of the bend) in the bent portion 3. It turns out that both sides are progressing.
- the propagation of the crack 5 in the plate thickness direction stops when it reaches a depth of about 1/4 of the plate thickness t. It turns out that it only progresses in one direction.
- the inventor focused on the stress distribution in the bent portion 3 as shown in FIG.
- the bent portion 3 Immediately after bending the metal plate 1, the bent portion 3 has a compressive stress in the area inside the bending from the neutral axis, and a compressive stress in the area outside the neutral axis in the bending, as shown in FIG. is a tensile stress.
- the compressive stress remains at a position about 1/4 of the plate thickness t from the inner surface of the bent portion 3 when bent.
- the crack progresses in the depth direction again.
- the crack propagates in both the lateral direction and the depth direction while the semi-elliptical crack fracture surface expands.
- the crack growth rate increases remarkably, making fatigue fracture more likely, and brittle fracture more likely to occur. Therefore, from the viewpoint of component reliability, it is desirable to take measures against such cracks.
- the inventor diligently studied a method for suppressing the propagation of cracks in the depth direction even when the compressive residual stress inside the bent portion of the metal plate is released. As a result, by applying plastic strain at predetermined intervals along the valley line direction (horizontal direction) of the bent portion 3 to generate compressive residual stress, the compressive residual stress remaining inside the bent portion 3 is reduced. The present inventors have found that even if the crack is released, it is possible to suppress the propagation of cracks in the depth direction to prevent fatigue fracture or suppress brittle fracture.
- the present invention has been made based on the above findings, and specifically has the following configurations.
- Embodiment 1 ⁇ Method for Suppressing Fatigue Crack Propagation at Bent Part of Metal Plate>
- a method for suppressing fatigue crack propagation in a bent portion of a metal plate according to Embodiment 1 of the present invention suppresses propagation of fatigue cracks occurring in the bent portion 3 formed by bending the metal plate 1 .
- the metal plate 1 is bent at least in a direction orthogonal to the valley line direction at intervals of less than the thickness t of the metal plate 1 along the valley line direction inside the bend in the bending part 3.
- a compressive residual stress is generated by applying plastic strain within the range from the bending start point 3a to the bending end point 3b on the bending inner side of the processed portion 3.
- the compressive residual stress is generated in a series within the range from the bending start point 3a to the bending end point 3b on the inner side of bending of the bent portion 3 by needle peening treatment using an impact pin 11. It is generated by forming an indentation band 9 (see FIG. 1(a)) which is an impact mark 7. As shown in FIG. At this time, the interval d in the valley line direction of the indentation bands 9 is less than the plate thickness t of the metal plate 1 .
- the curvature radius r of the tip portion 13 of the striking pin 11 in a cross section orthogonal to the valley line direction is less than the curvature radius R of the bent portion 3 on the inner side of the bend.
- FIG. 4(a) is a diagram schematically showing the shape of the crack fracture surface. As shown in FIG. 4(a), the crack generated on the inner surface of the bent portion 3 of the metal plate 1 expands in a semielliptical shape in both the depth direction and the lateral direction. Assuming that
- Fig. 4(b) shows the horizontal direction (trough direction on the inner side of the bend) and the depth direction (plate thickness direction) using the Newman-Raju equation (see Non-Patent Document 1) shown in the following equation (1). This is the result of calculating the stress intensity factor K at the crack tip that propagates to each of
- ⁇ t is the tensile stress
- ⁇ b is the bending stress
- a is the length of the crack fracture surface in the depth direction (thickness direction)
- c is the lateral length of the crack fracture surface. (distance from the crack initiation location to the crack tip in the lateral direction)
- b is the plate width of the metal plate 1
- t is the plate thickness of the bending part 3 (metal plate 1)
- ⁇ is the crack initiation location and the crack tip. and the surface of the bent portion 3.
- H(a,c,t, ⁇ ), Q(a,c) and F(a,c,b,t, ⁇ ) are functions given by each variable (see Non-Patent Document 1).
- width 50mm is the bending load 100MPa
- FIG. 4(b) shows the relationship between the crack fracture surface ratio c/a, which is an index representing the shape of the semi-elliptic crack fracture surface, and K(0) and K(90).
- the effect of compressive residual stress at a depth of about 1/4 of the plate thickness t from the inner surface of the bend is not considered.
- the magnitude of the stress intensity factor which does not consider the effect of compressive residual stress, represents the magnitude of the crack growth rate.
- region P the region where the crack fracture surface ratio c/a is c/a ⁇ 2 (hereinafter referred to as “region P”), that is, the shape of the crack fracture surface is semicircular
- the stress intensity factor K(0) in the lateral direction is almost constant and high, indicating that the driving force for crack propagation (growth) in the lateral direction is large.
- the stress intensity factor K(90) in the depth direction is smaller than the stress intensity factor K(0) in the lateral direction (K(90) ⁇ K(0)), indicating that cracks in the depth direction It can be seen that the driving force of the crack extension (progress) is small.
- region Q the shape of the crack fracture surface spreads in the lateral direction (the value of c/a increases
- the stress intensity factor K(0) decreases as the shape becomes semi-elliptical, and the driving force for crack propagation in the lateral direction also decreases.
- the stress intensity factor K(90) in the depth direction is larger than the stress intensity factor K(0) in the lateral direction (K(90)>K(0)), indicating that cracks in the depth direction It can be seen that the driving force for propagation (advancement) increases.
- the shape of the crack fracture surface is a semi-elliptical shape extending in the horizontal direction (crack fracture surface ratio c/a>2, region Q in FIG. 4(b)).
- the stress intensity factor K(0) in the lateral direction decreases. speed slows down.
- the stress intensity factor K(90) in the depth direction when ignoring the residual stress is The state is greater than the coefficient K(0) (K(90)>K(0)). In such a state, if the compressive residual stress inside the bent portion 3 is released for some reason as described above, the crack progresses in the depth direction again.
- the stress intensity factor K(90) in the depth direction governs fracture phenomena such as fracture toughness, and the crack growth rate in the depth direction increases remarkably, making brittle fracture more likely to occur. turn into.
- the crack propagation in the lateral direction is c/a ⁇ 2, i.e., the crack width 2c is less than the plate thickness t (2c ⁇ t) in the region P.
- compressive residual stress is introduced by forming indentation bands 9 in the valley direction of the bent portion 3 at intervals of less than the plate thickness t.
- the compressive residual stress of the bent portion 3 forms an indentation band 9, which is a series of impact marks 7, on the inside of the bend of the bent portion 3 by needle peening using an impact pin. It is generated by applying plastic strain.
- the striking pin 11 it is preferable that the radius of curvature r of the tip portion 13 of the cross section orthogonal to the direction of the valley line is less than or equal to the radius of curvature R of the bent portion 3 .
- buckling deformation may occur during bending and the curvature radius may become extremely small locally.
- a macroscopic radius of curvature may be used.
- the impact pin 11 having a radius of curvature r smaller than the radius of curvature of the bent inner side of the bent portion 3 is used for impact.
- deformation of the metal plate 1 and change in bending angle of the bent portion 3 can be suppressed, and at the same time, compressive residual stress can be appropriately introduced into the bent portion 3 .
- the range in which the indentation band 9 is formed in the direction orthogonal to the valley line direction on the inner side of the bending portion 3 may be all or part of the range from the bending start point to the bending end point on the inner side of the bend.
- the bending start point and the bending end point refer to the bending end of curvature on the inner side of bending of the bent portion 3 .
- the lower limit of the interval d between the indentation bands 9 in the valley line direction on the inner side of the bend of the bent portion 3 is not particularly defined, it is better from the viewpoint of productivity that it is larger.
- the lower limit may be the crack length or plate thickness, whichever is smaller.
- the present invention may perform needle peening treatment simultaneously with a plurality of striking pins, and if combined with an automatic construction method using a robot arm or the like, a further improvement in productivity can be expected. Furthermore, in the case of parts having many bent portions such as automobile parts, applying this treatment to the entire bent portion reduces productivity. For this reason, it is advisable to limit the bending work only to locations where the radius of curvature of the bent portion is small, or to locations where there is concern about fatigue fracture on the inner side of the bend by fatigue tests, stress analysis, etc. in advance.
- the present invention only needs to generate compressive residual stress in the bent portion that can suppress the propagation of cracks in the valley line direction of the bent portion. Therefore, the method of generating compressive residual stress is not limited to needle peening, and similar treatments such as laser peening, shot peening, and cold spray may be used. In the case of shot peening, the same effect can be obtained by masking the position other than the position where the indentation is to be introduced so as not to cause unnecessary plastic deformation. These methods are methods of giving plastic strain and generating compressive residual stress by applying an impact to the material. Laser peening uses a shock wave during laser irradiation, and shot peening and cold spray apply a shock wave to the bent part by projecting a blasting material to give plastic strain.
- the present invention it is possible to effectively improve the fatigue life of a part having a bent portion formed by bending a metal plate. Furthermore, according to the present invention, since it is not necessary to perform a peening treatment on the entire inner surface of the bend in the bent portion, an improvement in productivity can be expected. The effect of improving fatigue life due to stress and work hardening can also be expected.
- an automobile component according to Embodiment 2 of the present invention has a bent portion 3 obtained by bending a metal plate 1, and suppresses the propagation of fatigue cracks in the bent portion 3. be.
- the automobile part is bent at least from the bending start point 3a on the inner side of the bent portion 3 in a direction orthogonal to the valley line direction with a space less than the plate thickness of the metal plate 1 along the valley line direction of the bent portion 3.
- An indentation band 9 is formed by needle peening treatment with a gap less than the plate thickness, and compressive residual stress is applied, and the crack 5 is propagated in the valley line direction before the crack width reaches the plate thickness. Suppress.
- the compressive residual stress remaining inside the bent portion 3 is released, it is possible to suppress the fatigue fracture due to rapid growth of the crack in the plate thickness direction. Also, brittle fracture caused by the crack 5 generated in the bent portion 3 can be suppressed.
- the crack 5 is prevented from growing in the direction of the valley line. Since it can be suppressed, fatigue fracture can be prevented and the fatigue life can be improved.
- the plastic strain imparted to the bent portion 3 in the automobile component according to Embodiment 2 is due to the needle peening treatment.
- the plastic strain imparted to the bent portion is not limited to needle peening treatment, but may be laser peening, shot peening, cold spraying, or other treatment.
- a fatigue test was performed using the fatigue test piece 21 shown in FIG. 5 as a test object, and the fatigue strength was evaluated.
- a hot rolled steel sheet with a thickness of 2.9 mm and a yield strength of 850 MPa was cut into 200 mm x 50 mm pieces as test material.
- the fatigue test piece 21 has a bent portion 23 having a curvature radius R of 2 mm on the inner side of the bend, and pieces 25a and 25b extending from both sides of the bent portion 23.
- Each of the pieces 25a and 25b has a diameter Holes 27a and 27b with a diameter of 8.5 mm are provided.
- the bent portion 23 of the fatigue test piece 21 is subjected to needle peening treatment, and indentations are made at predetermined intervals d along the valley line direction on the inner side of the bend.
- a band 29 was formed.
- the fatigue test piece 21 with a different interval d between the indentation bands 29 is subjected to the fatigue test.
- the piece 21 was designated as invention example 1 and invention example 2.
- Comparative Example 3 was obtained by not performing the treatment and not forming the indentation band 29 .
- Table 1 shows the distance d between the indentation bands 29 formed on the fatigue test piece 21 and the results of the fatigue test.
- Both invention examples 1 and 2 reached the fatigue limit without cracks of 2.8m or more even after 2 million cycles, and were judged to pass.
- Comparative Examples 1 and 2 in which the distance d between the indentation bands 29 is outside the scope of the present invention, the number of cycles was 1,500,000 and 500,000. Cracks of 2.8 mm or more occurred at several 200,000 cycles, and all were judged to be unacceptable.
- the present invention there is no increase in the manufacturing cost of bending a metal plate, it can be applied to the bent portion after bending, and the productivity is not lowered, and the entire part or the bent portion can be manufactured. It is possible to provide a method for suppressing the growth of fatigue cracks in a bent portion of a metal plate, which can suppress the propagation of fatigue cracks in the bent portion without changing the bending angle. Further, according to the present invention, it is possible to provide an automobile part that has a bent portion obtained by bending a metal plate and suppresses the progress of fatigue cracks in the bent portion.
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Abstract
Description
(b)ピーニングに用いる打撃ピン(impact pin)の打撃荷重(impact load)によって部品全体(曲げ加工部やその周辺)が変形してしまう。
(c)打撃ピンの先端半径が曲げ加工部の曲率半径より大きいと曲げ加工部の曲げ角度が拡大してしまう。
金属板の表面に発生する疲労き裂は、一般的には図2(a)に示すように、き裂5の発生箇所から横方向(金属板1の表面に沿った方向)と深さ方向(金属板1の板厚方向)の双方に半だ円状のき裂破面が拡大しながら進展する。そして、き裂破面が金属板1の裏面側にまで到達して疲労破壊(fatigue fracture)に至る。
<金属板の曲げ加工部の疲労き裂進展抑制方法>
本発明の実施の形態1に係る金属板の曲げ加工部の疲労き裂進展抑制方法は、金属板1を曲げ加工した曲げ加工部3に発生する疲労き裂の進展を抑制するものである。図1に示すように、本方法は、曲げ加工部3における曲げ内側の谷線方向に沿って金属板1の板厚t未満の間隔を空けて、谷線方向に直交する方向に、少なくとも曲げ加工部3の曲げ内側における曲げ始点3aから曲げ終点3bまでの範囲内に塑性ひずみを付与して圧縮残留応力を発生させる。
<自動車部品>
本発明の実施の形態2に係る自動車部品は、図1に示すように、金属板1を曲げ加工した曲げ加工部3を有し、曲げ加工部3における疲労き裂の進展を抑制したものである。自動車部品は、曲げ加工部3の谷線方向に沿って金属板1の板厚未満の間隔を空けて、谷線方向に直交する方向に、少なくとも曲げ加工部3の曲げ内側における曲げ始点3aから曲げ終点3bまでの範囲内にニードルピーニング処理による一連の打撃痕7である圧痕帯9を有する。
3 曲げ加工部
3a 曲げ始点
3b 曲げ終点
5 き裂
7 打撃痕
9 圧痕帯
11 打撃ピン
13 先端部
21 疲労試験片
23 曲げ加工部
25a、25b 片部
27a、27b 穴部
29 圧痕帯
Claims (3)
- 金属板を曲げ加工した曲げ加工部の疲労き裂の進展を抑制する金属板の曲げ加工部の疲労き裂進展抑制方法であって、
前記曲げ加工部の谷線方向に沿って前記金属板の板厚未満の間隔を空けて、前記谷線方向に直交する方向に、少なくとも前記曲げ加工部の曲げ内側における曲げ始点から曲げ終点までの範囲内に塑性ひずみを付与して圧縮残留応力を発生させる、金属板の曲げ加工部の疲労き裂進展抑制方法。 - 前記圧縮残留応力は、打撃ピンを用いたニードルピーニング処理により前記曲げ加工部の曲げ内側に一連の打撃痕である圧痕帯を形成することにより発生させ、
前記打撃ピンとして、その先端部の前記谷線方向に直交する断面における曲率半径が、前記曲げ加工部の曲率半径以下のものを用いる、請求項1に記載の金属板の曲げ加工部の疲労き裂進展抑制方法。 - 金属板を曲げ加工した曲げ加工部を有し、該曲げ加工部における疲労き裂の進展を抑制した自動車部品であって、
前記曲げ加工部の谷線方向に沿って前記金属板の板厚未満の間隔を空けて、前記谷線方向に直交する方向に、少なくとも前記曲げ加工部の曲げ内側における曲げ始点から曲げ終点までの範囲内に打撃ピンを用いたニードルピーニング処理による一連の打撃痕である圧痕帯を有する、自動車部品。
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Citations (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS52133864A (en) * | 1976-05-04 | 1977-11-09 | Nippon Electric Co | Mold for vvbend processing of metal plate material |
JPH08117879A (ja) * | 1994-08-29 | 1996-05-14 | Toyota Motor Corp | プレス加工方法 |
JP2000225567A (ja) | 1999-02-05 | 2000-08-15 | Toyota Motor Corp | 金属板のショットピーニング方法 |
JP4441641B1 (ja) | 2008-11-25 | 2010-03-31 | 国立大学法人名古屋大学 | 鋼構造物の疲労き裂補修方法 |
JP2016107310A (ja) * | 2014-12-08 | 2016-06-20 | トヨタ自動車株式会社 | ショットピーニング方法 |
JP2018051608A (ja) | 2016-09-29 | 2018-04-05 | 新日鐵住金株式会社 | コイニング加工方法、バーリング加工品のコイニング装置及び金属部品 |
JP2018051609A (ja) | 2016-09-29 | 2018-04-05 | 新日鐵住金株式会社 | バーリング加工装置、バーリング加工方法、金属部品の製造方法、バーリング加工品及び金属部品 |
JP2021045783A (ja) * | 2019-09-20 | 2021-03-25 | ジヤトコ株式会社 | プレス用金型およびワークの製造方法 |
-
2021
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2022
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- 2022-08-18 CN CN202280081513.2A patent/CN118302260A/zh active Pending
Patent Citations (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS52133864A (en) * | 1976-05-04 | 1977-11-09 | Nippon Electric Co | Mold for vvbend processing of metal plate material |
JPH08117879A (ja) * | 1994-08-29 | 1996-05-14 | Toyota Motor Corp | プレス加工方法 |
JP2000225567A (ja) | 1999-02-05 | 2000-08-15 | Toyota Motor Corp | 金属板のショットピーニング方法 |
JP4441641B1 (ja) | 2008-11-25 | 2010-03-31 | 国立大学法人名古屋大学 | 鋼構造物の疲労き裂補修方法 |
JP2016107310A (ja) * | 2014-12-08 | 2016-06-20 | トヨタ自動車株式会社 | ショットピーニング方法 |
JP2018051608A (ja) | 2016-09-29 | 2018-04-05 | 新日鐵住金株式会社 | コイニング加工方法、バーリング加工品のコイニング装置及び金属部品 |
JP2018051609A (ja) | 2016-09-29 | 2018-04-05 | 新日鐵住金株式会社 | バーリング加工装置、バーリング加工方法、金属部品の製造方法、バーリング加工品及び金属部品 |
JP2021045783A (ja) * | 2019-09-20 | 2021-03-25 | ジヤトコ株式会社 | プレス用金型およびワークの製造方法 |
Non-Patent Citations (1)
Title |
---|
J. C. NEWMAN JR.I. S. RAJU, ENG. FRACT. MECH., vol. 15, no. 1-2, 1981, pages 185 |
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