WO2010035883A1 - Method for forming deformed cross-section and formed article of quadrilateral cross-section exhibiting excellent spot weldability - Google Patents

Method for forming deformed cross-section and formed article of quadrilateral cross-section exhibiting excellent spot weldability Download PDF

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Publication number
WO2010035883A1
WO2010035883A1 PCT/JP2009/067123 JP2009067123W WO2010035883A1 WO 2010035883 A1 WO2010035883 A1 WO 2010035883A1 JP 2009067123 W JP2009067123 W JP 2009067123W WO 2010035883 A1 WO2010035883 A1 WO 2010035883A1
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Prior art keywords
cross
mpa
section
internal pressure
pipe
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PCT/JP2009/067123
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French (fr)
Japanese (ja)
Inventor
新宮豊久
鈴木孝司
園部治
橋本裕二
池田倫正
佐藤昭夫
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Ｊｆｅスチール株式会社
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Priority to CN2009801377816A priority Critical patent/CN102164690A/en
Priority to EP09816295.1A priority patent/EP2351623B1/en
Priority to KR1020137017515A priority patent/KR20130083492A/en
Priority to KR1020117006739A priority patent/KR101322229B1/en
Publication of WO2010035883A1 publication Critical patent/WO2010035883A1/en

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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
    • B21D26/00—Shaping without cutting otherwise than using rigid devices or tools or yieldable or resilient pads, i.e. applying fluid pressure or magnetic forces
    • B21D26/02—Shaping without cutting otherwise than using rigid devices or tools or yieldable or resilient pads, i.e. applying fluid pressure or magnetic forces by applying fluid pressure
    • 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
    • B21D26/00—Shaping without cutting otherwise than using rigid devices or tools or yieldable or resilient pads, i.e. applying fluid pressure or magnetic forces
    • B21D26/02—Shaping without cutting otherwise than using rigid devices or tools or yieldable or resilient pads, i.e. applying fluid pressure or magnetic forces by applying fluid pressure
    • B21D26/033—Deforming tubular bodies
    • B21D26/041—Means for controlling fluid parameters, e.g. pressure or temperature
    • 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
    • B21D26/00—Shaping without cutting otherwise than using rigid devices or tools or yieldable or resilient pads, i.e. applying fluid pressure or magnetic forces
    • B21D26/02—Shaping without cutting otherwise than using rigid devices or tools or yieldable or resilient pads, i.e. applying fluid pressure or magnetic forces by applying fluid pressure
    • B21D26/033—Deforming tubular bodies
    • 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
    • B21D51/00—Making hollow objects
    • B21D51/02—Making hollow objects characterised by the structure of the objects
    • B21D51/06—Making hollow objects characterised by the structure of the objects folded objects
    • 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
    • B21D51/00—Making hollow objects
    • B21D51/16—Making hollow objects characterised by the use of the objects

Definitions

  • the conventional profile forming technology using hydroforming has a problem that it is difficult to obtain a molded product having a profile with a high dimensional accuracy and excellent spot weldability.
  • the irregular cross section refers to a cross section such as a quadrangular cross section other than a circular form.
  • a method for forming an irregular cross-section characterized in that: (4) In any one of the above (1) to (3), a modified cross-section forming method characterized by using a steel pipe having a thickness / outer diameter ratio t / D of 0.05 or less as the pipe material. (5) A quadrilateral cross-section molded product having one or two parallel two sides formed by molding a tubular material by the modified cross-section molding method according to any one of (1) to (4) above, One or two parallel 2 excellent in spot weldability, characterized in that (hollow depth on flat surface or depth of hollow on flat surface) is 0.5 mm or less, and further, the corner radius of curvature R is 10 mm or less. A quadrilateral cross-section molded product with sides.
  • the tube material is a tube material having a tensile strength of 690 MPa or more, and after crushing with the deformed section mold, the tube material is deformed by continuously applying an internal pressure with the liquid.
  • the maximum internal pressure is an internal pressure that satisfies both Pmin and more and more than 50 MPa, and the peripheral length increase rate after molding is A% or more and 11.0% or less below.
  • A 4.167 ⁇ 10 ⁇ 3 ⁇ (TS-590)
  • TS Tensile strength of pipe (MPa)
  • TS Tensile strength of pipe (MPa)
  • a steel pipe having a tensile strength of 780 MPa or more is used as the pipe material, and molding is performed such that the peripheral length increase rate after molding is A% or more and 10.0% or less below.
  • a modified cross-section molding method characterized.
  • A 4.167 ⁇ 10 ⁇ 3 ⁇ (TS-590)
  • TS Tensile strength of pipe (MPa)
  • (12) In combination with the internal pressure load after the crushing process, the tube end is loaded with a compressive force in the tube axis direction, and the tube end is pushed toward the center in the tube axis direction. Section forming method. (13) In the above (11) or (12), a steel pipe having a tensile strength of 780 MPa or more is used as the pipe, and the peripheral length increase rate after forming is formed to be A% or more and 10.0% or less below.
  • a modified cross-section molding method characterized by the above.
  • FIG. 1 is an explanatory diagram showing an outline of the method of the present invention.
  • a metal tube having a tensile strength (abbreviated as TS (tensile strength)) of 590 MPa or more, for example, a steel tube is used.
  • TS tensile strength
  • the tube material 10 is loaded into a mold having at least one flat portion, for example, a mold 1A having a pair of upper and lower flat portions.
  • the mold cross-sectional shape of the molds 1 and 1 ⁇ / b> A is a cross-sectional shape different from that of the tube material 10.
  • the tube material 10 may be either preformed or not.
  • the method without an internal pressure load on the pipe material includes two cases where the liquid is not contained in the pipe and the case where no internal pressure is generated by the liquid even if the liquid is contained in the pipe. .
  • preparation by injecting liquid is performed while crushing.
  • a recess (referred to as a flat portion recess) is formed in the tube wall portion facing the flat portion of the mold, and the tube wall portion facing the corner portion of the mold is loosely formed. Corner R is formed.
  • the pipe is continuously loaded with an internal pressure that causes the maximum internal pressure to be equal to or higher than the following P min [MPa] while being clamped of upper of die and lower die, so that the pipe has a deformed cross-sectional shape. Molding is performed (FIG. 1C).
  • P min 0.045 ⁇ TS (1)
  • P min lower limit of maximum internal pressure [MPa]
  • TS tensile strength of pipe material [MPa]
  • the coefficient on the right side is 0.09 instead of 0.045, more preferably 0.12, because the shape of the molded product is further improved.
  • the maximum internal pressure is usually about 100 to 200 MPa for the following reason.
  • the performance of a pressure intensifier that applies internal pressure is 200 MPa at maximum.
  • the projected area (or mold cavity projected area) in the horizontal plane of the molded product is excessive, it may be set to less than 200 MPa, for example, 150 MPa due to the limitation of the press force of the pressure intensifier. If there is no restriction as described above and the raw tube is thin and low in strength, sufficient straightening may be possible at 100 MPa.
  • the peripheral length increase rate after molding is 2.0% or more and 10.0% or less.
  • the flat portion dent amount tends to increase as the t / D increases, so that the t / D of the pipe material is 0. It is preferable to use a steel pipe of .05 or less.
  • the radius of curvature R (see FIG. The definition is shown in Fig. 2.
  • the specific measurement method is to cut a cross-section molded product with a plane perpendicular to the longitudinal direction, capture cross-sectional photographs of all corners in the image, and draw circles with various radii of curvature.
  • the curvature radius R of all corners was obtained by overlapping the corners, and the maximum radius R was set as the corner curvature radius R.) was 10 mm or less.
  • the reason why the lower limit P min [MPa] of the internal pressure (maximum internal pressure) when the internal pressure applied after crushing is maximized in the present invention is defined as the value of the above equation (1) will be described.
  • the flat portion dent amount of the molded product is 0.
  • the molding conditions were examined so that the corner radius of curvature R would be 10 mm or less.
  • both the flat portion dent amount and the corner radius of curvature R decrease. It was found that this should be the lower limit of the maximum internal pressure.
  • the relationship between this lower limit and the TS of the pipe material is as shown in FIG. 4. From FIG. 4, when TS is 590 MPa or more, the lower limit P min of the maximum internal pressure is expressed by the above formula (1).
  • the flat part dent amount and the peripheral length increase rate dependency of the corner R were obtained, and the following knowledge was obtained. That is, when the maximum internal pressure after crushing is set to P min or more and the tube TS is 780 MPa or more, the flat portion dent amount is further reduced when the product peripheral length increase rate is 2.0% or more. Further, it is a finding that when the product peripheral length increase rate is 10.0% or less, the corner radius of curvature R is further reduced.
  • the peripheral length increase rate after molding is 2.0 to 10.0%. It is better to mold it.
  • the internal pressure used for molding after crushing is determined by finding the correspondence between the maximum internal pressure and the peripheral length increase rate by FEM (finite element method) analysis and experiment, and this correspondence corresponds to the target peripheral length increase rate. It is better to set the maximum internal pressure.
  • tensile If strength is used tubing 10 above 690 MPa, as described above, maximum pressure is the by the liquid to continue tube while clamping (1) a defined P min [MPa ]
  • An internal pressure satisfying both the above-described internal pressure and over 50 MPa is loaded, and molding is performed so that the peripheral length increase rate after hydroforming is not less than A% and not more than 11.0%.
  • the circumference increase rate is given by the following equation.
  • a flat part dent further reduces, and a corner (R material) overhangs a corner R part, and becomes a sharper (small curvature radius) R shape.
  • the coefficient on the right side is 4.8 ⁇ 10 ⁇ 3 instead of 4.167 ⁇ 10 ⁇ 3 , the shape of the molded product (flat recess or corner R portion) is further improved. This is preferable.
  • the material when the internal pressure is applied after crushing, the material may overhang, resulting in an excessive reduction in the thickness near the corner R.
  • a compressive force in the tube axis direction is applied to the tube end and the tube end is pushed toward the center in the tube axis direction (this is referred to as “shaft pushing”). Therefore, it is possible to reduce the thickness reduction.
  • the preferable condition for “shaft pushing” is to adjust the cylinder stroke (cylinder stroke) of the press machine for shaft pushing so that the push-in amount (stroke) is 0 to the length of the molded part of the final product after hydrofume processing. About 10% is preferable.
  • the flat portion dent amount tends to increase as the t / D increases, so that the t / D of the pipe material is 0. It is preferable to use a steel pipe of .05 or less.
  • the corner radius of curvature R decreases as the circumference increase rate increases, and the circumference increase rate when the corner radius of curvature R becomes 10 mm is the upper limit.
  • the peripheral length increase rate is preferably 11.0% or less.
  • the peripheral length increase rate is preferably 10.0% or less.
  • a tube material having the TS and size shown in Table 1 was formed into a deformed cross section in the following steps.
  • the pipe materials used were all ERW steel pipes.
  • Table 2 shows the composition of the steel sheets of materials 1-33 and the manufacturing method of the steel sheets.
  • the length of the steel pipe used for the Example was 300 mm.
  • the steel plate 12 is placed on the upper flat portion of the product 11, and the electrode 3 is pressed against it with a constant pressure (50 to 200 Kgf) to perform one-side spot welding for each three pieces.
  • a constant pressure 50 to 200 Kgf
  • welding conditions energization time: 10 to 20 cycles (50 Hz), welding current: 5 to 10 KA
  • Whether or not spot weldability is determined is determined by the presence or absence of nugget formation and a tensile shear test (JIS).
  • JIS tensile shear test
  • Z 3136 is performed with a tensile shear load, and the following two-stage evaluation of ⁇ and ⁇ is made.
  • the pipe after crushing using the upper and lower molding dies, the pipe is continuously loaded with an internal pressure by a liquid, and the maximum internal pressure is in an appropriate range, more preferably, the rate of increase in peripheral length after molding is in the appropriate range.
  • the tubular material can be formed into a deformed cross-sectional shape having a curvature radius R of a corner with a small flat portion dent amount and a sharp outline (small curvature radius). Since the obtained deformed cross-section molded product has a small flat portion dent amount, it is excellent in one-side spot weldability with a metal plate. Further, the deformation of the springback after unloading is suppressed, and a deformed cross-section molded product with high dimensional accuracy is obtained.

Abstract

It is difficult to obtain a formed article of deformed cross-section which exhibits excellent spot-weldability and high dimensional precision by using a conventional technology for forming a deformed cross-section. In a state where no internal pressure is loaded to a tubular material (10) having a tensile strength (TS) of 590 MPa or above, or an internal pressure of 50 MPa or less is loaded to the tubular material (10) by liquid, the tublar material is subjected to tube-flattening by using dies (1, 1A) of deformed cross-section where at least one surface has a flat part, and then an internal pressure is loaded by the liquid so that the highest internal pressure is at least the following Pmin [MPa], whereby the tubular material is formed to have a deformed cross-section. Pmin=0.045×TS.

Description

異形断面への成形方法およびスポット溶接性に優れた四辺形断面成形品Quadrilateral cross-section molded product with excellent molding method and spot weldability to irregular cross-section
　本発明は、異形断面への成形方法（ｆｏｒｍｉｎｇ　ｍｅｔｈｏｄ　ｏｆ　ｃｏｍｐｌｅｘ　ｃｒｏｓｓ−ｓｅｃｔｉｏｎ　ｓｈａｐｅ）およびスポット溶接性（ｓｐｏｔ　ｗｅｌｄａｂｉｌｉｔｙ）に優れた四辺形断面の成形品（ｑｕａｄｒａｔｅ　ｃｒｏｓｓ−ｓｅｃｔｉｏｎ　ｆｏｒｍｉｎｇ　ａｒｔｉｃｌｅ）に関し、詳しくは、管材（ｔｕｂｉｎｇ　ｍａｔｅｒｉａｌ）を素材とし、これをハイドロフォーミング加工（ｈｙｄｒｏｆｏｒｍ　ｐｒｏｃｅｓｓ）により異形断面形状に成形する異形断面成形方法、および該成形方法で管材を成形してなるスポット溶接性に優れた一又は二の平行２辺を有する四辺形断面の成形品に関する。 The present invention relates to a method for forming a cross section with a deformed cross section (formation method of complex cross-section shape) and a quadrilateral cross section with excellent spot weldability (quadrate cross-section forming art, and details). A tubular material (tubing material) is used as a raw material, and a modified cross-section forming method for forming this into a deformed cross-sectional shape by hydroforming, and one or two excellent spot weldability formed by forming the tubular material by the forming method. The present invention relates to a molded article having a quadrilateral cross section having two parallel sides.
　従来、管材を素材として用い、これをハイドロフォーミング加工により、異形断面形状に成形する方法が知られている（例えば特許文献１の従来技術の［０００３］~［０００５］および図１、図２参照）。これは、特許文献１の図１の（ａ）に示すように、断面が円形のパイプを所要平面形状たとえば特許文献１の図３の（ｂ）に示すようなＵ字状に曲げ加工（本発明では、予成形（ｐｒｅｆｏｒｍｉｎｇ）と称す）し、その曲げ加工品のパイプ径よりも狭い幅の製品部分については、プレスあるいは専用機により特許文献１の図１の（ｂ）のように素材径よりも幅寸法が減縮した断面形状に潰し加工（ｐｒｅ−ｐｒｅｓｓｉｎｇ　ｏｒ　ｃｒｕｓｈｉｎｇ）し、この潰し加工品を特許文献１の図１の（ｃ）のように上下型のキャビテイに装填し、特許文献１の図１の（ｄ）のように上下型の型締めを行った後、特許文献１の図１の（ｅ）のように潰し加工品内に液体を注入して、例えば２２０００ｐｓｉ（１５１ＭＰａ）の内圧を負荷させることにより、型面に馴染むように塑性変形させ、特許文献１の図１の（ｆ）のような断面形状に成形する第１のタイプの方法が開示されている。また、特許文献１の図２の（ａ）に示すように、断面が円形のパイプを所要平面形状たとえば特許文献１の図３の（ｂ）に示すようなＵ字状に曲げ加工し、その曲げ加工品をやはりプレスあるいは専用機により特許文献１の図２の（ｂ）に示すように幅寸法が減縮した断面形状に潰し加工し、この潰し加工品を特許文献１の図２の（ｃ）のように上下型のキャビテイに装着し、特許文献１の図２の（ｄ）のように型締め前に潰し加工品内に例えば１０００ｐｓｉ（７ＭＰａ）程度の低圧を負荷させて予備加圧成形し、ついで、特許文献１の図２の（ｅ）のように型締めを行い、予備加圧成形品を特許文献１の図２の（ｆ）のような断面形状になるように６０００~７０００ｐｓｉ（４２−４９ＭＰａ）の高い内圧にして、型面に馴染むように塑性変形させる第２のタイプが開示されている。 Conventionally, there has been known a method of using a pipe material as a raw material and forming it into a deformed cross-sectional shape by hydroforming (for example, refer to [0003] to [0005] of the prior art of Patent Document 1 and FIGS. 1 and 2). ). As shown in FIG. 1A of Patent Document 1, a pipe having a circular cross section is bent into a required planar shape, for example, a U-shape as shown in FIG. In the present invention, it is referred to as preforming), and a product portion having a width smaller than the pipe diameter of the bent product is subjected to a material diameter as shown in FIG. Further, the cross-sectional shape with a reduced width dimension is crushed (pre-pressing or crushing), and this crushed product is loaded into an upper and lower mold cavity as shown in FIG. After the upper and lower molds are clamped as shown in FIG. 1 (d), a liquid is injected into the crushed product as shown in FIG. 1 (e) of Patent Document 1, for example, 22000 psi (151 MPa). Applying internal pressure By, is plastically deformed to adapt to the mold surface, the first type of method of molding is disclosed in the cross-sectional shape as in FIG. 1 of Patent Document 1 (f). Further, as shown in FIG. 2 (a) of Patent Document 1, a pipe having a circular cross section is bent into a required plane shape, for example, a U-shape as shown in FIG. 3 (b) of Patent Document 1, The bent product is also crushed into a cross-sectional shape with a reduced width as shown in FIG. 2 (b) of Patent Document 1 by a press or a dedicated machine. ) And pre-press molding by applying a low pressure of about 1000 psi (7 MPa), for example, to the crushed product before clamping as shown in FIG. Then, clamping is performed as shown in FIG. 2E of Patent Document 1, and the pre-pressed product is 6000 to 7000 psi so as to have a cross-sectional shape as shown in FIG. 2F of Patent Document 1. (42-49MPa) with high internal pressure, plastic so as to fit the mold surface A second type of sexual deformation is disclosed.
特開２０００−２４６３６１号公報JP 2000-246361 A
　しかし、上記従来の成形方法では、前記第１のタイプでは１０％以上の大きな周長増加率を採用することが一般的であり、延性の低い管材、例えば高強度の鋼管では高内圧負荷時に破断が発生する傾向が増加し、前記第２のタイプでは、潰し加工を行うことにより異形断面成形品の平坦であるべき部位（例えば四辺形断面の辺になる部位）にかなりの凹みを生じる部分があり、スポット溶接、特に片側スポット溶接（ｏｎｅ−ｓｉｄｅ　ｓｐｏｔ　ｗｅｌｄｉｎｇ）が非常に困難となる。また、コーナー（ｃｏｒｎｅｒ）Ｒ部（例えば四辺形断面のコーナーになる部位）の曲率半径（ｃｕｒｖａｔｕｒｅ　ｒａｄｉｕｓ）Ｒが、金型の対応隅部（ｃｏｒｎｅｒ）のそれよりかなり大きくなり、シャープな断面形状を得難く、製品の形状精度が不十分である。 However, in the above-described conventional forming method, it is common to employ a large peripheral length increase rate of 10% or more in the first type, and in the case of a pipe material with low ductility, for example, a high-strength steel pipe, it breaks when a high internal pressure load is applied. In the second type, there is a portion in which a considerable dent is generated in a portion that should be flat (for example, a portion that becomes a side of a quadrilateral cross section) of the deformed cross-section molded product by performing the crushing process. In addition, spot welding, particularly one-side spot welding, becomes very difficult. In addition, the curvature radius R of the corner R portion (for example, the portion that becomes the corner of the quadrilateral cross section) is considerably larger than that of the corresponding corner of the mold, resulting in a sharp cross-sectional shape. It is difficult to obtain and the shape accuracy of the product is insufficient.
　つまり、従来のハイドロフォーミング加工による異形断面成形技術では、スポット溶接性に優れた高寸法精度（ｈｉｇｈ　ｄｉｍｅｎｓｉｏｎａｌ　ａｃｃｕｒａｃｙ）の異形断面の成形品を得るのが困難であるという課題があった。
　ここで、異形断面とは円形（ｃｉｒｃｕｌａｒ　ｆｏｒｍ）以外の、例えば、四辺形断面のような断面をいう。 In other words, the conventional profile forming technology using hydroforming has a problem that it is difficult to obtain a molded product having a profile with a high dimensional accuracy and excellent spot weldability.
Here, the irregular cross section refers to a cross section such as a quadrangular cross section other than a circular form.
　発明者らは、前記課題を解決すべく鋭意検討し、その結果、スポット溶接を容易ならしめる高寸法精度の異形断面成形品をハイドロフォーミング加工により実現する手段に想到し、本発明をなした。すなわち本発明は以下のとおりである。
（１）引張強さ５９０ＭＰａ以上の管材に、内圧を負荷しない状態もしくは液体により５０ＭＰａ以下の内圧を負荷した状態で、少なくとも１つの面が平坦部を有する異形断面金型にて潰し加工を行い、引続き前記液体により最高内圧が下記Ｐｍｉｎ［ＭＰａ］以上になる内圧を負荷して、前記管材を異形断面形状に成形することを特徴とする異形断面成形方法。 The inventors have intensively studied to solve the above-mentioned problems. As a result, the inventors have conceived a means for realizing a high-dimensional precision deformed cross-section molded article that facilitates spot welding by hydroforming, and have made the present invention. That is, the present invention is as follows.
(1) In a state where no internal pressure is applied to a pipe material having a tensile strength of 590 MPa or more or an internal pressure of 50 MPa or less is applied with a liquid, crushing is performed with a deformed cross-section mold having at least one flat surface, A deformed cross-section forming method, wherein the tube is formed into a deformed cross-sectional shape by continuously applying an internal pressure at which the maximum internal pressure is equal to or higher than the following P min [MPa] by the liquid.
　記
　Ｐｍｉｎ＝０．０４５×ＴＳ
　Ｐｍｉｎ：最高内圧の下限［ＭＰａ］、ＴＳ：管材の引張強さ［ＭＰａ］
（２）前記潰し加工後の内圧負荷と併せて、管端（ｔｕｂｅ　ｅｎｄ）に管軸方向（ｔｕｂｅ　ａｘｉｓ　ｄｉｒｅｃｔｉｏｎ）の圧縮力（ｃｏｍｐｒｅｓｓｉｏｎ　ｆｏｒｃｅ）を負荷して管端を管軸方向中央側に押し込むことを特徴とする上記（１）に記載の異形断面成形方法。
（３）上記（１）または（２）において、前記管材として引張強さ７８０ＭＰａ以上の鋼管を用い、成形後の周長増加率（ｉｎｃｒｅａｓｉｎｇ　ｒａｔｅ　ｏｆ　ｇｉｒｔｈ）が２．０％以上１０．０％以下となるように成形することを特徴とする異形断面成形方法。
（４）上記（１）~（３）のいずれかにおいて、前記管材として肉厚／外径比ｔ／Ｄが０．０５以下である鋼管を用いることを特徴とする異形断面成形方法。
（５）管材を上記（１）~（４）のいずれかに記載の異形断面成形方法で成形してなる一又は二の平行２辺を有する四辺形断面成形品であって、平坦部凹み量（ｈｏｌｌｏｗ　ｄｅｐｔｈ　ｏｎ　ｆｌａｔ　ｓｕｒｆａｃｅ　ｏｒ　ｄｅｐｔｈ　ｏｆ　ｈｏｌｌｏｗ　ｏｎ　ｆｌａｔ　ｓｕｒｆａｃｅ）が０．５ｍｍ以下であり、さらにコーナーの曲率半径Ｒが１０ｍｍ以下であることを特徴とするスポット溶接性に優れた一又は二の平行２辺を有する四辺形断面成形品。
（６）上記（１）において、前記管材が引張強さ６９０ＭＰａ以上の管材であり、前記異形断面金型にて潰し加工を行った後、引続き前記液体により内圧を負荷して、前記管材を異形断面形状に成形するにあたり、前記最高内圧が、Ｐｍｉｎ以上および、５０ＭＰａ超えの両方を満足する内圧を加え、さらに、成形後の周長増加率が下記Ａ％以上１１．０％以下となるように成形することを特徴とする異形断面成形方法。 P min = 0.045 × TS
P min : lower limit of maximum internal pressure [MPa], TS: tensile strength of pipe material [MPa]
(2) Along with the internal pressure load after the crushing process, a tube axis direction compression force is applied to the tube end and the tube end is pushed toward the center in the tube axis direction. The method for forming an irregular cross-section as described in (1) above, wherein
(3) In the above (1) or (2), a steel pipe having a tensile strength of 780 MPa or more is used as the pipe material, and an increasing rate of circumference after molding is 2.0% or more and 10.0% or less. A method for forming an irregular cross-section, characterized in that:
(4) In any one of the above (1) to (3), a modified cross-section forming method characterized by using a steel pipe having a thickness / outer diameter ratio t / D of 0.05 or less as the pipe material.
(5) A quadrilateral cross-section molded product having one or two parallel two sides formed by molding a tubular material by the modified cross-section molding method according to any one of (1) to (4) above, One or two parallel 2 excellent in spot weldability, characterized in that (hollow depth on flat surface or depth of hollow on flat surface) is 0.5 mm or less, and further, the corner radius of curvature R is 10 mm or less. A quadrilateral cross-section molded product with sides.
(6) In the above (1), the tube material is a tube material having a tensile strength of 690 MPa or more, and after crushing with the deformed section mold, the tube material is deformed by continuously applying an internal pressure with the liquid. When forming into a cross-sectional shape, the maximum internal pressure is an internal pressure that satisfies both Pmin and more and more than 50 MPa, and the peripheral length increase rate after molding is A% or more and 11.0% or less below. A method for forming an irregular cross section, characterized by forming.
　記
　Ａ＝４．１６７×１０−３×（ＴＳ−５９０）
　Ａ：周長増加率の下限（％）、ＴＳ：管材の引張強さ（ＭＰａ）
（７）前記潰し加工後の内圧負荷と併せて、管端に管軸方向の圧縮力を負荷して管端を管軸方向中央側に押し込むことを特徴とする（６）に記載の異形断面成形方法。
（８）（６）または（７）において、前記管材として引張強さ７８０ＭＰａ以上の鋼管を用い、成形後の周長増加率が下記Ａ％以上１０．０％以下となるように成形することを特徴とする異形断面成形方法。 A = 4.167 × 10 −3 × (TS-590)
A: Lower limit of perimeter increase rate (%), TS: Tensile strength of pipe (MPa)
(7) The deformed cross section according to (6), wherein a compressive force in the tube axis direction is applied to the tube end together with the internal pressure load after the crushing process, and the tube end is pushed toward the center in the tube axis direction. Molding method.
(8) In (6) or (7), a steel pipe having a tensile strength of 780 MPa or more is used as the pipe material, and molding is performed such that the peripheral length increase rate after molding is A% or more and 10.0% or less below. A modified cross-section molding method characterized.
　記
　Ａ＝４．１６７×１０−３×（ＴＳ−５９０）
　Ａ：周長増加率の下限（％）、ＴＳ：管材の引張強さ（ＭＰａ）
（９）（６）~（８）のいずれかにおいて、前記管材として肉厚／外径比ｔ／Ｄが０．０５以下である鋼管を用いることを特徴とする異形断面成形方法。
（１０）管材を（６）~（９）のいずれかに記載の異形断面成形方法で成形してなる一又は二の平行２辺を有する四辺形断面成形品であって、平坦部凹み量が０．５ｍｍ以下であり、さらにコーナーの曲率半径Ｒが１０ｍｍ以下であることを特徴とするスポット溶接性に優れた一又は二の平行２辺を有する四辺形断面成形品。
（１１）引張強さ６９０ＭＰａ以上の管材に、内圧を負荷しない状態もしくは液体により５０ＭＰａ以下の内圧を負荷した状態で、少なくとも１つの面が平坦部を有する異形断面金型にて潰し加工を行い、引続き前記液体により最高内圧が、５０ＭＰａ超である内圧を負荷して、前記管材を異形断面形状に成形するにあたり、成形後の周長増加率が下記Ａ％以上１１．０％以下となるように成形することを特徴とする異形断面成形方法。
　記
　Ａ＝４．１６７×１０−３×（ＴＳ−５９０）
　Ａ：周長増加率の下限（％）、ＴＳ：管材の引張強さ（ＭＰａ）
（１２）前記潰し加工後の内圧負荷と併せて、管端に管軸方向の圧縮力を負荷して管端を管軸方向中央側に押し込むことを特徴とする前記（１１）に記載の異形断面成形方法。
（１３）前記（１１）または（１２）において、前記管材として引張強さ７８０ＭＰａ以上の鋼管を用い、成形後の周長増加率が下記Ａ％以上１０．０％以下となるように成形することを特徴とする異形断面成形方法。
　記
　Ａ＝４．１６７×１０−３×（ＴＳ−５９０）
　Ａ：周長増加率の下限（％）、ＴＳ：管材の引張強さ（ＭＰａ）
（１４）前記（１１）~（１３）のいずれかにおいて、前記管材として肉厚／外径比ｔ／Ｄが０．０５以下である鋼管を用いることを特徴とする異形断面成形方法。
（１５）管材を前記（１１）~（１４）のいずれかに記載の異形断面成形方法で成形してなる一又は二の平行２辺を有する四辺形断面成形品であって、平坦部凹み量が０．５ｍｍ以下であり、さらにコーナーの曲率半径Ｒが１０ｍｍ以下であることを特徴とするスポット溶接性に優れた一又は二の平行２辺を有する四辺形断面成形品。 A = 4.167 × 10 −3 × (TS-590)
A: Lower limit of perimeter increase rate (%), TS: Tensile strength of pipe (MPa)
(9) The modified cross-section forming method according to any one of (6) to (8), wherein a steel pipe having a thickness / outer diameter ratio t / D of 0.05 or less is used as the pipe material.
(10) A quadrilateral cross-sectional molded product having one or two parallel two sides formed by molding a tubular material by the modified cross-section molding method according to any one of (6) to (9), wherein the flat portion dent amount is A quadrilateral cross-sectional molded article having one or two parallel two sides excellent in spot weldability, characterized by being 0.5 mm or less and having a corner radius of curvature R of 10 mm or less.
(11) In a state where no internal pressure is applied to a pipe material having a tensile strength of 690 MPa or more or an internal pressure of 50 MPa or less is applied with a liquid, crushing is performed with a deformed cross-section die having at least one flat surface, When the tube is formed into a deformed cross-sectional shape by continuously applying an internal pressure with a maximum internal pressure of more than 50 MPa with the liquid, the peripheral length increase rate after molding is from A% to 11.0% below. A method for forming an irregular cross section, characterized by forming.
A = 4.167 × 10 −3 × (TS-590)
A: Lower limit of perimeter increase rate (%), TS: Tensile strength of pipe (MPa)
(12) In combination with the internal pressure load after the crushing process, the tube end is loaded with a compressive force in the tube axis direction, and the tube end is pushed toward the center in the tube axis direction. Section forming method.
(13) In the above (11) or (12), a steel pipe having a tensile strength of 780 MPa or more is used as the pipe, and the peripheral length increase rate after forming is formed to be A% or more and 10.0% or less below. A modified cross-section molding method characterized by the above.
A = 4.167 × 10 −3 × (TS-590)
A: Lower limit of perimeter increase rate (%), TS: Tensile strength of pipe (MPa)
(14) In any one of the above (11) to (13), a modified cross-section forming method using a steel pipe having a thickness / outer diameter ratio t / D of 0.05 or less as the pipe material.
(15) A quadrilateral cross-sectional molded product having one or two parallel two sides formed by molding a tubular material by the modified cross-section molding method according to any one of (11) to (14) above, Is a quadrilateral cross-sectional molded article having one or two parallel two sides excellent in spot weldability, characterized in that the corner radius of curvature R is 10 mm or less.
　本発明によれば、上下成形金型（ｕｐｐｅｒ　ａｎｄ　ｌｏｗｅｒ　ｆｏｒｍｉｎｇ　ｄｉｅ）を用いた潰し加工後、引続き管材に液体により内圧を負荷し、最高内圧が、適正範囲、さらに好ましくは、成形後の周長増加率が適正範囲に収まるように成形することにより、管材を平坦部凹み量が小さくかつ輪郭がシャープな（曲率半径が小さい）コーナーの曲率半径Ｒを有する異形断面形状に成形することができる。得られた異形断面成形品は、平坦部凹み量が小さいことから、金属板との片側スポット溶接性に優れる。また、除荷後のスプリングバック変形（ｓｐｒｉｎｇｂａｃｋ　ｄｅｆｏｒｍａｔｉｏｎ）が抑制され、高寸法精度の異形断面成形品となる。 According to the present invention, after crushing using an upper and lower forming die, an internal pressure is continuously applied to the pipe material with a liquid, and the maximum internal pressure is within an appropriate range, more preferably a circumferential length after molding. By forming so that the increase rate falls within an appropriate range, the tube material can be formed into a deformed cross-sectional shape having a curvature radius R of a corner having a small flat portion dent amount and a sharp outline (small curvature radius). Since the obtained deformed cross-section molded product has a small flat portion dent amount, it is excellent in one-side spot weldability with a metal plate. In addition, springback deformation after unloading is suppressed, and a deformed cross-section molded product with high dimensional accuracy is obtained.
本発明方法の概要を示す説明図である。It is explanatory drawing which shows the outline | summary of this invention method. 一又は二の平行２辺を有する四辺形断面成形品の平坦部凹み量およびコーナーの曲率半径Ｒの定義を示す説明図である。It is explanatory drawing which shows the definition of the flat part dent amount and the curvature radius R of a corner of a quadrilateral cross-section molded product having one or two parallel two sides. 片側スポット溶接が不具合になる状態を示す説明図である。It is explanatory drawing which shows the state from which one side spot welding becomes a malfunction. 最高内圧の下限と引張強さの関係を示すグラフである。It is a graph which shows the relationship between the minimum of the maximum internal pressure, and tensile strength. スポット溶接実験の実験方法を示す説明図である。It is explanatory drawing which shows the experimental method of a spot welding experiment. 周長増加率の下限と引張強さの関係を示すグラフである。It is a graph which shows the relationship between the minimum of perimeter increase rate, and tensile strength.
　図１は、本発明方法の概要を示す説明図である。管材１０には引張強さ（略してＴＳ（ｔｅｎｓｉｌｅ　ｓｔｒｅｎｇｔｈ））が５９０ＭＰａ以上の金属管（ｍｅｔａｌｌｉｃ　ｔｕｂｅ）例えば鋼管（ｓｔｅｅｌ　ｔｕｂｅ）を用いる。まず、図１（ａ）のように管材１０を少なくとも１つの面が平坦部を有する金型、例えば上下一対の平坦部を有する金型１，１Ａに装入する。金型１，１Ａの型断面形状は管材１０とは異形の断面形状である。管材１０は予成形されたものとされていないものとのいずれであってもよい。なお、本発明で言う予成形とは、前述したように、管材を特許文献１の図３の（ｂ）に示すように長手方向にＵ字状に曲げ加工する場合やＳ字形状、９０°曲げ加工したり、管材の長手方向の一部を潰し加工したり、局部的に拡管加工あるいは、縮径加工することを言う。そして、管材への内圧負荷なしの状態、あるいは液体による低内圧（５０ＭＰａ以下）負荷ありの状態で、管材を上下金型１，１Ａで潰し加工する。 FIG. 1 is an explanatory diagram showing an outline of the method of the present invention. For the pipe member 10, a metal tube having a tensile strength (abbreviated as TS (tensile strength)) of 590 MPa or more, for example, a steel tube is used. First, as shown in FIG. 1A, the tube material 10 is loaded into a mold having at least one flat portion, for example, a mold 1A having a pair of upper and lower flat portions. The mold cross-sectional shape of the molds 1 and 1 </ b> A is a cross-sectional shape different from that of the tube material 10. The tube material 10 may be either preformed or not. In addition, as described above, the pre-molding referred to in the present invention is a case where the pipe material is bent into a U shape in the longitudinal direction as shown in FIG. It refers to bending, crushing part of the longitudinal direction of the pipe, or locally expanding or reducing the diameter. Then, the tube material is crushed by the upper and lower molds 1, 1 </ b> A in a state in which there is no internal pressure load on the tube material or a state in which a low internal pressure (50 MPa or less) is applied due to the liquid.
　なお、本発明方法では、管材への内圧負荷なしの方法の場合、パイプ内に液体が入っていない場合とパイプ内に液体が入っていても液体による内圧が発生しない場合の２つの場合を含む。一般には、ハイドロフォーミングのサイクルタイムを短縮するため、潰し加工を行いながら、液体の注入による準備（液体で満たしつつ気泡を抜く）を行う。 In the method of the present invention, the method without an internal pressure load on the pipe material includes two cases where the liquid is not contained in the pipe and the case where no internal pressure is generated by the liquid even if the liquid is contained in the pipe. . In general, in order to reduce the cycle time of hydroforming, preparation by injecting liquid (removing bubbles while filling with liquid) is performed while crushing.
　すると、図１（ｂ）に示すように、金型の平坦部に対面する管壁部分には凹み（平坦部凹みという）が形成され、金型のコーナー部に対面する管壁部分には緩やかなコーナーＲが形成される。 Then, as shown in FIG. 1B, a recess (referred to as a flat portion recess) is formed in the tube wall portion facing the flat portion of the mold, and the tube wall portion facing the corner portion of the mold is loosely formed. Corner R is formed.
　そこで、型締め（ｃｌｏｓｉｎｇ　ｏｆ　ｄｉｅｓ　ｏｒ　ｃｌｏｓｉｎｇ　ｏｆ　ｕｐｐｅｒ　ｄｉｅ　ａｎｄ　ｌｏｗｅｒ　ｄｉｅ）したまま引続き管材に前記液体により最高内圧が下記Ｐｍｉｎ［ＭＰａ］以上になる内圧を負荷して、前記管材を異形断面形状に成形する（図１（ｃ））。
　記
　Ｐｍｉｎ＝０．０４５×ＴＳ　　・・・・（１）
　Ｐｍｉｎ：最高内圧の下限［ＭＰａ］、ＴＳ：管材の引張強さ［ＭＰａ］
　これにより、図１（ｃ）に示すように、平坦部凹みは低減し、コーナーＲ部は材料（管材の材料）が張り出し、シャープなＲ形状となる。また、最高内圧を高くするほど残留応力が低減し、除荷後のスプリングバックによる形状変化が小さくなる。 Therefore, the pipe is continuously loaded with an internal pressure that causes the maximum internal pressure to be equal to or higher than the following P min [MPa] while being clamped of upper of die and lower die, so that the pipe has a deformed cross-sectional shape. Molding is performed (FIG. 1C).
P min = 0.045 × TS (1)
P min : lower limit of maximum internal pressure [MPa], TS: tensile strength of pipe material [MPa]
Thereby, as shown in FIG.1 (c), a flat part dent is reduced and material (material of a pipe material) overhangs a corner R part, and becomes a sharp R shape. Further, as the maximum internal pressure is increased, the residual stress is reduced, and the shape change due to the springback after unloading is reduced.
　なお、（１）式において、右辺の係数を０．０４５に代えて、０．０９、より好ましくは０．１２とすると、成形品の形状がさらに良好となるので好ましい。 In the formula (1), it is preferable that the coefficient on the right side is 0.09 instead of 0.045, more preferably 0.12, because the shape of the molded product is further improved.
　なお、ここで、最高内圧は下記の理由から、通常１００~２００ＭＰａ程度である。通常、内圧を掛ける増圧機の性能は、最大２００ＭＰａである。また、成形品の水平面内の投影面積（あるいは、金型キャビティ投影面積）が過大の場合は、増圧機のプレス力量の制限から２００ＭＰａ未満、例えば１５０ＭＰａに設定される場合もある。上記のような制約がない場合で、素管が薄肉で低強度であれば、１００ＭＰａで、十分な矯正成形が可能となる場合もある。 Here, the maximum internal pressure is usually about 100 to 200 MPa for the following reason. Usually, the performance of a pressure intensifier that applies internal pressure is 200 MPa at maximum. In addition, when the projected area (or mold cavity projected area) in the horizontal plane of the molded product is excessive, it may be set to less than 200 MPa, for example, 150 MPa due to the limitation of the press force of the pressure intensifier. If there is no restriction as described above and the raw tube is thin and low in strength, sufficient straightening may be possible at 100 MPa.
　また、潰し加工後の内圧負荷時には、材料が張り出すことにより、コーナーＲ部近傍の肉厚減少が過大となる場合が考えられる。そのような場合には、潰し加工後の内圧負荷に併せて、管端に管軸方向の圧縮力を負荷して管端を管軸方向中央側に押し込むこと（これを「軸押し」（ａｘｉａｌ　ｆｅｅｄｉｎｇ）という）により、肉厚減少を軽減させることが可能である。実際に軸押しをかけるタイミングは、内圧負荷後少し経過してから、軸押しをするのが好ましく、内圧負荷と同時に軸押しすることは無い。なお、「軸押し」の好ましい条件は、軸押し用のプレス機のシリンダーストローク（ｃｙｌｉｎｄｅｒ　ｓｔｒｏｋｅ）を調整することで、押し込み量（ａｘｉａｌ　ｆｅｅｄｉｎｇ　ｌｅｎｇｔｈ）（ストローク（ｓｔｒｏｋｅ））をハイドロフィーム加工後の最終製品の成形部長さＬと素管外径Ｄの比Ｌ／Ｄにおいて、Ｌ／Ｄ≧１０程度ならば押し込み量は最終製品の成形部長さＬの０~２％程度、Ｌ／Ｄ＝７超え~１０未満では、Ｌの０~３．５％程度、Ｌ／Ｄ≦７ならばＬの０~５％程度にするのが好ましい。なお、内圧が負荷されていれば、軸押し用のプレス機に反力がかかり、押し戻される傾向があるため、０％の押し込み量でも軸押し力が存在する。 In addition, when the internal pressure is applied after crushing, the material may overhang, resulting in an excessive reduction in the thickness near the corner R. In such a case, along with the internal pressure load after crushing, a compressive force in the tube axis direction is applied to the tube end and the tube end is pushed toward the center in the tube axis direction (this is called “axial push” (axial). It is possible to reduce the thickness reduction. The timing for actually pushing the shaft is preferably a little after the internal pressure is applied, and then the shaft is pushed, and the shaft is not pushed simultaneously with the internal pressure load. The preferable condition for “shaft pushing” is to adjust the cylinder stroke of the pressing machine for shaft pushing so that the pushing amount (stroke) is the final after the hydrofume processing. If the ratio L / D between the molded part length L of the product and the outer diameter D of the tube is about L / D ≧ 10, the pushing amount is about 0 to 2% of the molded part length L of the final product, and L / D = 7 or more If it is less than ˜10, it is preferably about 0 to 3.5% of L, and if L / D ≦ 7, about 0 to 5% of L is preferable. If an internal pressure is applied, a reaction force is applied to the press machine for pushing the shaft, and there is a tendency to push it back. Therefore, even if the pushing amount is 0%, the pushing force is present.
　また、本発明では、管材として引張強さ７８０ＭＰａ以上の鋼管を用いるときには、成形後の周長増加率が２．０％以上１０．０％以下となるように成形することが好ましい。
　なお、周長増加率は次式の（２）式で与えられる。
　周長増加率＝（成形品の外周長／成形前の管材の外周長−１）×１００（％）‥‥・・・（２） Further, in the present invention, when a steel pipe having a tensile strength of 780 MPa or more is used as the pipe material, it is preferable that the peripheral length increase rate after molding is 2.0% or more and 10.0% or less.
The circumference increase rate is given by the following equation (2).
Perimeter increase rate = (periphery length of molded product / perimeter length of tube material before molding-1) × 100 (%) (2)
　また、管材に用いる鋼管の肉厚／外径比ｔ／Ｄが０．０５を超えると、ｔ／Ｄの増加につれて平坦部凹み量が増加する傾向があるため、管材にはｔ／Ｄが０．０５以下の鋼管を用いることが好ましい。 In addition, when the thickness / outer diameter ratio t / D of the steel pipe used for the pipe material exceeds 0.05, the flat portion dent amount tends to increase as the t / D increases, so that the t / D of the pipe material is 0. It is preferable to use a steel pipe of .05 or less.
　上述の本発明方法により、スポット溶接性に優れた、高寸法精度の異形断面成形品が得られる。この成形品（製品）が、優れた片側スポット溶接性を有するには、製品の平坦部凹み量（図２に定義を示す。具体的な測定方法として、レーザー距離計を用いて、異形断面成形品の平坦部の凹み量を測定し、その最大凹み量を平坦部凹み量とした。）が０．５ｍｍ以下である必要がある。製品の平坦部凹み量が０．５ｍｍを超えると、例えば図３に示すように、スポット溶接用電極（ｓｐｏｔ　ｗｅｌｄｉｎｇ　ｅｌｅｃｔｒｏｄｅ）３で鋼板１２を製品１１に押し付けた際に、電極３の直下の範囲内の鋼板１２と製品１１との間に比較的大きな隙間δが生じやすくなり、安定した通電状態が得られず、スポット溶接が不具合となりやすいからである。 By the above-described method of the present invention, a deformed cross-section molded article having excellent spot weldability and high dimensional accuracy can be obtained. In order for this molded article (product) to have excellent one-side spot weldability, the flat part dent amount of the product (definition is shown in Fig. 2. As a specific measuring method, an irregular cross-section molding using a laser distance meter. The dent amount of the flat part of the product was measured, and the maximum dent amount was defined as the flat part dent amount.) Must be 0.5 mm or less. When the flat part dent amount of the product exceeds 0.5 mm, for example, as shown in FIG. 3, when the steel plate 12 is pressed against the product 11 with a spot welding electrode 3, a range immediately below the electrode 3. This is because a relatively large gap δ is likely to be generated between the inner steel plate 12 and the product 11, a stable energization state cannot be obtained, and spot welding is liable to be defective.
　また、一又は二の平行２辺を有する四辺形断面成形品について高寸法精度を有するには、シャープなＲ形状が必要であり、その目安として本発明では、製品のコーナーの曲率半径Ｒ（図２に定義を示す。具体的な測定方法は、異形断面成形品を長手方向に垂直な面で切断し、全てのコーナーの断面写真を画像に取り込み、種々の大きさの曲率半径の円を各コーナーに重ね合わせることで、全てのコーナーの曲率半径Ｒを求め、その最大Ｒをコーナーの曲率半径Ｒとした。）が１０ｍｍ以下であることとした。 In addition, a sharp R shape is necessary to obtain high dimensional accuracy for a quadrilateral cross-section molded product having one or two parallel two sides. As a guideline, in the present invention, the radius of curvature R (see FIG. The definition is shown in Fig. 2. The specific measurement method is to cut a cross-section molded product with a plane perpendicular to the longitudinal direction, capture cross-sectional photographs of all corners in the image, and draw circles with various radii of curvature. The curvature radius R of all corners was obtained by overlapping the corners, and the maximum radius R was set as the corner curvature radius R.) was 10 mm or less.
　ここで、本発明において潰し加工後に負荷する内圧が最高になるときの内圧（最高内圧）の下限Ｐｍｉｎ［ＭＰａ］を前記（１）式の値に規定した理由を述べる。種々のＴＳを有する管材を金型にて潰し加工後、液体で内圧を負荷して一又は二の平行２辺を有する四辺形断面形状に成形する場合に、成形品の平坦部凹み量が０．５ｍｍ以下となり、かつコーナーの曲率半径Ｒが１０ｍｍ以下となるための成形条件を検討した。その結果、最高内圧の上昇につれて平坦部凹み量、コーナーの曲率半径Ｒとも減少し、平坦部凹み量が０．５ｍｍになる最高内圧とコーナーの曲率半径Ｒが１０ｍｍになる最高内圧とのうち大きい方を最高内圧の下限とすればよいことがわかった。この下限と管材のＴＳとの関係は図４のようになり、同図より、ＴＳが５９０ＭＰａ以上において、最高内圧の下限Ｐｍｉｎは前記式（１）で表される。 Here, the reason why the lower limit P min [MPa] of the internal pressure (maximum internal pressure) when the internal pressure applied after crushing is maximized in the present invention is defined as the value of the above equation (1) will be described. When a tube material having various TS is crushed with a mold, and the inner pressure is applied with a liquid to form a quadrilateral cross-sectional shape having one or two parallel two sides, the flat portion dent amount of the molded product is 0. The molding conditions were examined so that the corner radius of curvature R would be 10 mm or less. As a result, as the maximum internal pressure increases, both the flat portion dent amount and the corner radius of curvature R decrease. It was found that this should be the lower limit of the maximum internal pressure. The relationship between this lower limit and the TS of the pipe material is as shown in FIG. 4. From FIG. 4, when TS is 590 MPa or more, the lower limit P min of the maximum internal pressure is expressed by the above formula (1).
　さらに、周長増加率に着目して、平坦部凹み量およびコーナーＲの周長増加率依存性を求め、次の知見が得られた。すなわち、潰し加工後の最高内圧を前記Ｐｍｉｎ以上とした条件下で、管材のＴＳが７８０ＭＰａ以上のとき、製品の周長増加率が２．０％以上であると平坦部凹み量が一段と小さくなり、また、製品の周長増加率が１０．０％以下であるとコーナーの曲率半径Ｒが一段と小さくなるという知見である。 Furthermore, paying attention to the peripheral length increase rate, the flat part dent amount and the peripheral length increase rate dependency of the corner R were obtained, and the following knowledge was obtained. That is, when the maximum internal pressure after crushing is set to P min or more and the tube TS is 780 MPa or more, the flat portion dent amount is further reduced when the product peripheral length increase rate is 2.0% or more. Further, it is a finding that when the product peripheral length increase rate is 10.0% or less, the corner radius of curvature R is further reduced.
　したがって、管材のＴＳが７８０ＭＰａ以上の場合は、潰し加工後の最高内圧をＰｍｉｎ［ＭＰａ］以上とする条件下で、成形後の周長増加率が２．０~１０．０％になるように成形するのがよい。 Therefore, when the TS of the pipe material is 780 MPa or more, under the condition that the maximum internal pressure after crushing is P min [MPa] or more, the peripheral length increase rate after molding is 2.0 to 10.0%. It is better to mold it.
　周長増加率を所定の範囲（Ａ％以上Ｂ％以下）に収めるには、型締め時の金型断面の内周長ＬＫとハイドロフォーム成形前の管材の外周長ＬＰとが、次式の関係を満足するような、金型と管材の組み合わせを用いて成形を行うとよい。 To fit the circumference increasing rate in a predetermined range (A% inclusive B%) is the outer peripheral length L P of the inner peripheral length of the mold cross section when the mold clamping L K and hydroformed front of the tube material, the following It is preferable to perform molding using a combination of a mold and a tube material that satisfies the formula relationship.
　Ａ≦（ＬＫ／ＬＰ−１）×１００≦Ｂ　…（３）
　また、潰し加工後の成形に用いる内圧は、ＦＥＭ（ｆｉｎｉｔｅ　ｅｌｅｍｅｎｔ　ｍｅｔｈｏｄ）解析や実験により、最高内圧と周長増加率の対応関係を求めておき、この対応関係において目標の周長増加率に対応する最高内圧に設定するとよい。 A ≦ (L K / L P −1) × 100 ≦ B (3)
In addition, the internal pressure used for molding after crushing is determined by finding the correspondence between the maximum internal pressure and the peripheral length increase rate by FEM (finite element method) analysis and experiment, and this correspondence corresponds to the target peripheral length increase rate. It is better to set the maximum internal pressure.
　さらに、本発明では、引張強さが６９０ＭＰａ以上の管材１０を用いる場合、上述したように、型締めしたまま引続き管材に前記液体により最高内圧が前記（１）式に規定されたＰｍｉｎ［ＭＰａ］以上になる内圧および５０ＭＰａ超の両方を満足する内圧を負荷し、ハイドロフォーム成形後の周長増加率が下記Ａ％以上１１．０％以下となるように成形する。なお、周長増加率は次式で与えられる。 Furthermore, in the present invention, tensile If strength is used tubing 10 above 690 MPa, as described above, maximum pressure is the by the liquid to continue tube while clamping (1) a defined P min [MPa ] An internal pressure satisfying both the above-described internal pressure and over 50 MPa is loaded, and molding is performed so that the peripheral length increase rate after hydroforming is not less than A% and not more than 11.0%. The circumference increase rate is given by the following equation.
　周長増加率＝（成形品の外周長／成形前の管材の外周長−１）×１００（％）・・・（２）
　記
　Ａ＝４．１６７×１０−３×（ＴＳ−５９０）…（４）
　Ａ：周長増加率の下限（％）、ＴＳ：管材の引張強さ（ＭＰａ） Perimeter increase rate = (periphery length of molded product / perimeter length of tube material before molding-1) × 100 (%) (2)
A = 4.167 × 10 −3 × (TS-590) (4)
A: Lower limit of perimeter increase rate (%), TS: Tensile strength of pipe (MPa)
　これにより、図１（ｃ）に示すように、平坦部凹みはさらに低減し、コーナーＲ部は材料（管材の材料）が張り出し、さらにシャープな（曲率半径が小さい）Ｒ形状となる。また、最高内圧を高くするほど、残留応力が低減し、除荷後のスプリングバックによる形状変化が小さくなる。なお、（４）式において、右辺の係数を４．１６７×１０−３に代えて、４．８×１０−３とすると、成形品の形状（平坦部凹みやコーナーＲ部）がさらに良好となるので好ましい。 Thereby, as shown in FIG.1 (c), a flat part dent further reduces, and a corner (R material) overhangs a corner R part, and becomes a sharper (small curvature radius) R shape. Further, the higher the maximum internal pressure, the lower the residual stress, and the smaller the shape change due to the springback after unloading. In addition, in the formula (4), when the coefficient on the right side is 4.8 × 10 −3 instead of 4.167 × 10 −3 , the shape of the molded product (flat recess or corner R portion) is further improved. This is preferable.
　なお、本発明では、管材の引張強さが、ＴＳ：６９０−１１００ＭＰａの範囲では、最高内圧は、前述のＰｍｉｎよりも５０ＭＰａの方が高くなるので、型締め時の最高内圧は、Ｐｍｉｎおよび５０ＭＰａ超えの両方を満足する５０ＭＰａ超えが好ましい。また、ＴＳ：１１００ＭＰａ超えの場合は、５０ＭＰａ超えよりもＰｍｉｎの方が最高内圧が高くなるので、型締め時の最高内圧は、Ｐｍｉｎ以上が好ましい。 In the present invention, when the tensile strength of the pipe material is in the range of TS: 690-1100 MPa, the maximum internal pressure is higher at 50 MPa than the above-described Pmin. Therefore, the maximum internal pressure at the time of clamping is Pmin and 50 MPa. Exceeding 50 MPa, which satisfies both of the above, is preferable. In addition, when TS exceeds 1100 MPa, Pmin has a higher maximum internal pressure than when it exceeds 50 MPa. Therefore, the maximum internal pressure during mold clamping is preferably Pmin or higher.
　また、潰し加工後の内圧負荷時には、材料が張り出すことにより、コーナーＲ部近傍の肉厚減少が過大となる場合が考えられる。そのような場合には、潰し加工後の内圧負荷に併せて、管端に管軸方向の圧縮力を負荷して管端を管軸方向中央側に押し込むこと（これを「軸押し」という）により、肉厚減少を軽減させることが可能である。なお、「軸押し」の好ましい条件は、軸押し用のプレス機のシリンダーストローク（ｃｙｌｉｎｄｅｒ　ｓｔｒｏｋｅ）を調整することで、押し込み量（ストローク）をハイドロフィーム加工後の最終製品の成形部長さの０~１０％程度にするのが好ましい。 In addition, when the internal pressure is applied after crushing, the material may overhang, resulting in an excessive reduction in the thickness near the corner R. In such a case, in accordance with the internal pressure load after crushing, a compressive force in the tube axis direction is applied to the tube end and the tube end is pushed toward the center in the tube axis direction (this is referred to as “shaft pushing”). Therefore, it is possible to reduce the thickness reduction. The preferable condition for “shaft pushing” is to adjust the cylinder stroke (cylinder stroke) of the press machine for shaft pushing so that the push-in amount (stroke) is 0 to the length of the molded part of the final product after hydrofume processing. About 10% is preferable.
　また、管材に用いる鋼管の肉厚／外径比ｔ／Ｄが０．０５を超えると、ｔ／Ｄの増加につれて平坦部凹み量が増加する傾向があるため、管材にはｔ／Ｄが０．０５以下の鋼管を用いることが好ましい。 In addition, when the thickness / outer diameter ratio t / D of the steel pipe used for the pipe material exceeds 0.05, the flat portion dent amount tends to increase as the t / D increases, so that the t / D of the pipe material is 0. It is preferable to use a steel pipe of .05 or less.
　ここで、本発明において成形後の周長増加率がＡ％以上１１．０％以下となるように成形することと規定した理由を述べる。種々のＴＳを有する管材を金型にて潰し加工後、液体で内圧を負荷して一又は二の平行２辺を有する四辺形断面形状に成形する場合に、成形品の平坦部凹み量が０．５ｍｍ以下となり、かつコーナーの曲率半径Ｒが１０ｍｍ以下となるための成形条件を検討した。その結果、平坦部凹み量は周長増加率の増加につれて減少し、平坦部凹み量が０．５ｍｍになるときの周長増加率が下限となることがわかった。この下限と管材のＴＳとの関係は図６のようになり、図６より、ＴＳが６９０ＭＰａ以上において、周長増加率の下限Ａは前記式（４）で表される。 Here, the reason why it is specified that the peripheral length increase rate after molding is A% or more and 11.0% or less in the present invention will be described. When a tube material having various TS is crushed with a mold, and the inner pressure is applied with a liquid to form a quadrilateral cross-sectional shape having one or two parallel two sides, the flat portion dent amount of the molded product is 0. The molding conditions were examined so that the corner radius of curvature R would be 10 mm or less. As a result, it was found that the flat portion dent amount decreased as the peripheral length increase rate increased, and the peripheral length increase rate when the flat portion dent amount became 0.5 mm was the lower limit. The relationship between this lower limit and the TS of the pipe material is as shown in FIG. 6, and from FIG. 6, when TS is 690 MPa or more, the lower limit A of the circumferential length increase rate is expressed by the above formula (4).
　一方、コーナーの曲率半径Ｒは、周長増加率の増加につれて減少し、コーナーの曲率半径Ｒが１０ｍｍになるときの周長増加率が上限となることがわかった。この上限と管材のＴＳとの関係（図示省略）を求めた結果によると、ＴＳが６９０ＭＰａ以上では周長増加率は１１．０％以下とするのがよい。また、ＴＳが７８０ＭＰａ以上では周長増加率は１０．０％以下とするのがよい。 On the other hand, it was found that the corner radius of curvature R decreases as the circumference increase rate increases, and the circumference increase rate when the corner radius of curvature R becomes 10 mm is the upper limit. According to the result of obtaining the relationship between the upper limit and the TS of the pipe material (not shown), when the TS is 690 MPa or more, the peripheral length increase rate is preferably 11.0% or less. Further, when TS is 780 MPa or more, the peripheral length increase rate is preferably 10.0% or less.
　したがって、管材のＴＳが６９０ＭＰａ以上の場合は、成形後の周長増加率がＡ~１１．０％となるように成形するのがよい。また、管材のＴＳが７８０ＭＰａ以上の場合は、成形後の周長増加率がＡ~１０．０％となるように成形するのがよい。 Therefore, when the TS of the pipe material is 690 MPa or more, it is preferable to form the tube so that the peripheral length increase rate after forming is A to 11.0%. Further, when the TS of the pipe material is 780 MPa or more, it is preferable to form the tube so that the rate of increase in the peripheral length after forming is A to 10.0%.
　なお、本願成形方法が適用可能な管材は、ＴＳが５９０ＭＰａ以上の熱延鋼板や冷延鋼板から製造された電縫鋼管であり、焼入れ、焼戻し等の熱処理された熱延鋼板や冷延鋼板から製造された電縫鋼管も含む。また、上記の熱延鋼板および冷延鋼板の鋼種は、普通鋼、低合金鋼、フェライト系ステンレス、オーステナイト系ステンレスあるいは、マルテンサイト系ステンレスであっても良い。これらに限るものではない。 The pipe material to which the present forming method can be applied is an ERW steel pipe manufactured from a hot-rolled steel sheet or a cold-rolled steel sheet having a TS of 590 MPa or more, and from a hot-rolled steel sheet or a cold-rolled steel sheet subjected to heat treatment such as quenching or tempering Includes manufactured ERW steel pipes. The steel types of the hot-rolled steel sheet and the cold-rolled steel sheet may be ordinary steel, low alloy steel, ferritic stainless steel, austenitic stainless steel, or martensitic stainless steel. It is not limited to these.
　図１に示した矩形断面形状の金型１、１Ａを用い、表１に示すＴＳ、サイズを有する管材を下記の工程で異形断面形状に成形した。なお、用いられた管材は、全て電縫鋼管で、Ｎｏ．１~３２の電縫鋼管の素材の鋼板の組成と、鋼板の製造方法を表２に示す。なお、実施例に用いた鋼管の長さは、３００ｍｍであった。
［工程］　金型に装入→内圧無しの状態または液体により５０ＭＰａ以下の内圧（Ｎｏ．１０と１１は、それぞれ　１０ＭＰａ、１３ＭＰａ）を負荷した状態で型締めによる潰し加工→表１に示す種々の周長増加率となるように液体により最高内圧が表１に示す値となる内圧を負荷（一部の管材には軸押しを併用（Ｎｏ．１２と１３は、それぞれ、押し込み量　２．５％、３．０％））。 Using the molds 1 and 1A having a rectangular cross section shown in FIG. 1, a tube material having the TS and size shown in Table 1 was formed into a deformed cross section in the following steps. The pipe materials used were all ERW steel pipes. Table 2 shows the composition of the steel sheets of materials 1-33 and the manufacturing method of the steel sheets. In addition, the length of the steel pipe used for the Example was 300 mm.
[Process] Inserting into mold → No internal pressure or crushing by mold clamping under liquid pressure of 50 MPa or less (No. 10 and 11 are 10 MPa and 13 MPa, respectively) → Various types shown in Table 1 Load the internal pressure so that the maximum internal pressure becomes the value shown in Table 1 by the liquid so that the perimeter increase rate is obtained (Axial push is used in combination with some pipes (No. 12 and 13 are 2.5% push-in amount respectively) 3.0%)).
　得られた成形品（製品）の平坦部凹み量およびコーナーの曲率半径Ｒ（図２参照）を測定し（平坦部凹み量の測定は、異形断面成形品を長手方向の中央部で、各々４つの平坦部について、長手方向に垂直な方向にレーザー距離計を用いて、各々４つの平坦部の凹み量を測定し、その最大凹み量を平坦部凹み量とした。また、コーナーの曲率半径Ｒの測定は、異形断面成形品を長手方向の中央部で、長手方向に垂直な面で切断し、各々４つのコーナーの断面写真を画像に取り込み、種々の大きさの半径の円を各コーナーに重ね合わせることで、４つのコーナーの曲率半径Ｒを求め、その最大Ｒをコーナーの曲率半径Ｒとした。）、また、以下の方法でスポット溶接性を試験した。
［スポット溶接性の試験方法］ The flat part dent amount and the corner radius of curvature R (see FIG. 2) of the obtained molded product (product) were measured (measurement of the flat part dent amount was performed by measuring each of the deformed cross-section molded products at the center part in the longitudinal direction. For each of the two flat portions, a dent amount of each of the four flat portions was measured using a laser distance meter in a direction perpendicular to the longitudinal direction, and the maximum dent amount was defined as the flat portion dent amount. In the measurement, the cross-section molded product was cut at the center in the longitudinal direction at a plane perpendicular to the longitudinal direction, and cross-sectional photographs of each of the four corners were taken into the image, and circles of various radii were placed at each corner. The radius of curvature R of the four corners was obtained by superimposing them, and the maximum radius R was defined as the radius of curvature R of the corner.) Also, the spot weldability was tested by the following method.
[Spot weldability test method]
　図５に示すように、製品１１の上平坦部に鋼板１２を置き、その上から電極３を一定の加圧力（５０~２００Ｋｇｆ）で押し当てて、各３個づつ片側スポット溶接を行う。（溶接条件：通電時間１０~２０サイクル（ｃｙｃｌｅｓ）（５０Ｈｚ）、溶接電流５~１０ＫＡ）スポット溶接性の良否判定は、ナゲット形成（ｎｕｇｇｅｔ　ｆｏｒｍａｔｉｏｎ）の有無および引張せん断試験（ｔｅｎｓｉｌｅ　ｓｈｅａｒ　ｔｅｓｔ）（ＪＩＳ　Ｚ　３１３６）における引張せん断荷重（ｔｅｎｓｉｌｅ　ｓｈｅａｒ　ｌｏａｄ）で行い、次の○、×の２段階評価とする。継手の引張せん断荷重の基準値ＴＳＳは下式に基づき、基準値を満足する継手を十分（合格）と判定する。
　ＴＳＳ（Ｎ）＝１．８５×ｔ×ＴＳ×（１＋０．００５９ＥＬ）×（ＮＤ＋２．０９）
　ただし、ｔは鋼板１２の板厚（ｍｍ）
　ＴＳは鋼板１２の引張強さ（ＭＰａ）
　ＥＬは鋼板１２の伸び（％）
　ＮＤは製品１１と鋼板１２の間のナゲット径（ｎｕｇｇｅｔ　ｄｉａｍｅｔｅｒ）（ｍｍ）
　鋼板１２は、板厚が１．０ｍｍ以下の４４０ＭＰａ級以下の鋼板である。
○：スポット溶接部１３にナゲット形成有（ナゲット形成の有無は断面写真から判定）、引張せん断荷重は十分（合格）
×：スポット溶接部１３にナゲット形成無、もしくは、引張せん断荷重が不十分 As shown in FIG. 5, the steel plate 12 is placed on the upper flat portion of the product 11, and the electrode 3 is pressed against it with a constant pressure (50 to 200 Kgf) to perform one-side spot welding for each three pieces. (Welding conditions: energization time: 10 to 20 cycles (50 Hz), welding current: 5 to 10 KA) Whether or not spot weldability is determined is determined by the presence or absence of nugget formation and a tensile shear test (JIS). Z 3136) is performed with a tensile shear load, and the following two-stage evaluation of ○ and × is made. Based on the following formula, the reference value TSS of the tensile shear load of the joint is determined to be sufficient (pass) for a joint that satisfies the reference value.
TSS (N) = 1.85 × t × TS × (1 + 0.0059EL) × (ND + 2.09)
Where t is the thickness of the steel plate 12 (mm)
TS is the tensile strength of steel plate 12 (MPa)
EL is the elongation of steel sheet 12 (%)
ND is the nugget diameter (mm) between the product 11 and the steel plate 12
The steel plate 12 is a 440 MPa grade or less steel plate having a thickness of 1.0 mm or less.
○: Nugget formed on spot weld 13 (presence of nugget formation is determined from cross-sectional photograph), and sufficient tensile shear load (passed)
X: No nugget is formed on the spot weld 13 or the tensile shear load is insufficient.
　上記測定および試験の結果を表１に示す。表１より、本発明例では、ＴＳ５９０ＭＰａ以上の管材からスポット溶接性に優れた高寸法精度の異形断面成形品が得られたことがわかる。なお、本発明例において、ｔ／Ｄ≦０．０５のものは、ｔ／Ｄ＞０．０５のものに比べ、平坦部凹み量が小さくなっている。 Table 1 shows the results of the above measurements and tests. From Table 1, it can be seen that in the example of the present invention, a deformed cross-sectional molded article having high dimensional accuracy and excellent spot weldability was obtained from a tube material of TS590 MPa or more. In the example of the present invention, the flat portion dent amount is smaller when t / D ≦ 0.05 than when t / D> 0.05.
　実施例１と同様に、図１に示した矩形断面形状の金型１、１Ａを用い、表３に示すＴＳ、サイズを有する管材を下記の工程で異形断面形状に成形した。なお、用いられた管材は、全て電縫鋼管で、Ｎｏ．１~３０の電縫鋼管の素材の鋼板の組成と、鋼板の製造方法を表４に示す。なお、実施例に用いた鋼管の長さは、３００ｍｍであった。
［工程］　金型に装入→内圧無しの状態または液体により５０ＭＰａ以下の内圧（Ｎｏ．８と９は、それぞれ１０ＭＰａ、１３ＭＰａ）を負荷した状態で型締めによる潰し加工→表３に示す種々の周長増加率となるように液体により５０ＭＰａ超の内圧を負荷（一部の管材には軸押しを併用（Ｎｏ．１０と１１は、それぞれ、押し込み量４％、５％））。 In the same manner as in Example 1, using the molds 1 and 1A having the rectangular cross-sectional shape shown in FIG. 1, a tube material having the TS and size shown in Table 3 was formed into an irregular cross-sectional shape in the following steps. The pipe materials used were all ERW steel pipes. Table 4 shows the composition of the steel sheets of 1 to 30 ERW steel pipe materials and the method of manufacturing the steel sheets. In addition, the length of the steel pipe used for the Example was 300 mm.
[Process] Inserting into mold → No internal pressure or crushing by mold clamping with internal pressure of 50 MPa or less (No. 8 and 9 are 10 MPa and 13 MPa, respectively) with liquid → Various types shown in Table 3 An internal pressure of more than 50 MPa is applied with a liquid so as to increase the peripheral length (shaft pressing is used in combination with some pipe materials (No. 10 and 11 are 4% and 5%, respectively)).
　得られた成形品（製品）の平坦部凹み量およびコーナーの曲率半径Ｒ（図２参照）を測定し、また、実施例１と同様の方法でスポット溶接性を試験した。
　上記測定および試験の結果を表３に示す。表３より、本発明例では、ＴＳ６９０ＭＰａ以上の管材からスポット溶接性に優れた高寸法精度の異形断面成形品が得られたことがわかる。なお、本発明例において、ｔ／Ｄ≦０．０５のものは、ｔ／Ｄ＞０．０５のものに比べ、平坦部凹み量が小さくなっている。 The flat part dent amount and the corner radius of curvature R (see FIG. 2) of the obtained molded product (product) were measured, and spot weldability was tested in the same manner as in Example 1.
The results of the above measurements and tests are shown in Table 3. From Table 3, it can be seen that in the example of the present invention, an irregular cross-section molded article with high dimensional accuracy having excellent spot weldability was obtained from a tube material of TS690 MPa or more. In the example of the present invention, the flat portion dent amount is smaller when t / D ≦ 0.05 than when t / D> 0.05.
　本発明によれば、上下成形金型を用いた潰し加工後、引続き管材に液体により内圧を負荷し、最高内圧が、適正範囲、さらに好ましくは、成形後の周長増加率が適正範囲に収まるように成形することにより、管材を平坦部凹み量が小さくかつ輪郭がシャープな（曲率半径が小さい）コーナーの曲率半径Ｒを有する異形断面形状に成形することができる。得られた異形断面成形品は、平坦部凹み量が小さいことから、金属板との片側スポット溶接性に優れる。また、除荷後のスプリングバック変形が抑制され、高寸法精度の異形断面成形品となる。 According to the present invention, after crushing using the upper and lower molding dies, the pipe is continuously loaded with an internal pressure by a liquid, and the maximum internal pressure is in an appropriate range, more preferably, the rate of increase in peripheral length after molding is in the appropriate range. By molding in this manner, the tubular material can be formed into a deformed cross-sectional shape having a curvature radius R of a corner with a small flat portion dent amount and a sharp outline (small curvature radius). Since the obtained deformed cross-section molded product has a small flat portion dent amount, it is excellent in one-side spot weldability with a metal plate. Further, the deformation of the springback after unloading is suppressed, and a deformed cross-section molded product with high dimensional accuracy is obtained.
１　　金型（上金型）
１Ａ　金型（下金型）
３　　電極
１０　管材
１１　製品（異形断面成形品、一又は二の平行２辺を有する四辺形断面成形品）
１２　鋼板
１３　スポット溶接部 1 Mold (Upper mold)
1A mold (lower mold)
3 Electrode 10 Tubing 11 Product (Deformed cross-section product, quadrilateral cross-section product with one or two parallel two sides)
12 Steel plate 13 Spot weld
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000004
Figure JPOXMLDOC01-appb-T000004
Figure JPOXMLDOC01-appb-T000005
Figure JPOXMLDOC01-appb-T000005
Figure JPOXMLDOC01-appb-T000006
Figure JPOXMLDOC01-appb-T000006

Claims (15)

  1. 　引張強さ５９０ＭＰａ以上の管材に、内圧を負荷しない状態もしくは液体により５０ＭＰａ以下の内圧を負荷した状態で、少なくとも１つの面が平坦部を有する異形断面金型にて潰し加工を行い、引続き前記液体により最高内圧が下記Ｐｍｉｎ［ＭＰａ］以上になる内圧を負荷して、前記管材を異形断面形状に成形することを特徴とする異形断面成形方法。
    　記
    　Ｐｍｉｎ＝０．０４５×ＴＳ
    　Ｐｍｉｎ：最高内圧の下限［ＭＰａ］、ＴＳ：管材の引張強さ［ＭＰａ］     In a state in which an internal pressure is not applied to a pipe material having a tensile strength of 590 MPa or more or an internal pressure of 50 MPa or less is applied by a liquid, crushing processing is performed with a deformed cross-section mold having at least one flat surface, and the liquid is continuously applied. The deformed cross-section forming method is characterized in that an internal pressure at which the maximum internal pressure is equal to or higher than the following P min [MPa] is applied to form the tube material into a deformed cross-sectional shape.
    P min = 0.045 × TS
    P min : lower limit of maximum internal pressure [MPa], TS: tensile strength of pipe material [MPa]
  2. 　前記潰し加工後の内圧負荷と併せて、管端に管軸方向の圧縮力を負荷して管端を管軸方向中央側に押し込むことを特徴とする請求項１に記載の異形断面成形方法。 The deformed cross-section forming method according to claim 1, wherein together with the internal pressure load after the crushing process, a compressive force in the tube axis direction is applied to the tube end and the tube end is pushed toward the center in the tube axis direction.
  3. 　請求項１または２において、前記管材として引張強さ７８０ＭＰａ以上の鋼管を用い、成形後の周長増加率が２．０％以上１０．０％以下となるように成形することを特徴とする異形断面成形方法。 3. The modified shape according to claim 1, wherein a steel pipe having a tensile strength of 780 MPa or more is used as the pipe material, and the peripheral length increase rate after forming is 2.0% or more and 10.0% or less. Section forming method.
  4. 　請求項１~３のいずれか１項において、前記管材として肉厚／外径比ｔ／Ｄが０．０５以下である鋼管を用いることを特徴とする異形断面成形方法。 4. The modified cross-section forming method according to claim 1, wherein a steel pipe having a wall thickness / outer diameter ratio t / D of 0.05 or less is used as the pipe material.
  5. 　管材を請求項１~４のいずれか１項に記載の異形断面成形方法で成形してなる一又は二の平行２辺を有する四辺形断面成形品であって、平坦部凹み量が０．５ｍｍ以下であり、さらにコーナーの曲率半径Ｒが１０ｍｍ以下であることを特徴とするスポット溶接性に優れた一又は二の平行２辺を有する四辺形断面成形品。 A quadrilateral cross-sectional molded product having one or two parallel two sides formed by molding a tubular material by the modified cross-section molding method according to any one of claims 1 to 4, wherein the flat portion dent amount is 0.5 mm. A quadrilateral cross-sectional molded article having one or two parallel two sides excellent in spot weldability, wherein the corner radius of curvature R is 10 mm or less.
  6. 　請求項１において、前記管材が引張強さ６９０ＭＰａ以上の管材であり、前記異形断面金型にて潰し加工を行った後、引続き前記液体により内圧を負荷して、前記管材を異形断面形状に成形するにあたり、前記最高内圧が、Ｐｍｉｎ以上および、５０ＭＰａ超えの両方を満足する内圧を加え、さらに、成形後の周長増加率が下記Ａ％以上１１．０％以下となるように成形することを特徴とする異形断面成形方法。
    　記
    　Ａ＝４．１６７×１０−３×（ＴＳ−５９０）
    　Ａ：周長増加率の下限（％）、ＴＳ：管材の引張強さ（ＭＰａ）     2. The tube material according to claim 1, wherein the tube material is a tube material having a tensile strength of 690 MPa or more, and after the crushing process is performed with the deformed cross-section mold, an internal pressure is continuously applied by the liquid to form the tube material into a deformed cross-section shape. In doing so, the internal pressure satisfying both the maximum internal pressure of Pmin or more and exceeding 50 MPa is applied, and further, the molding is performed such that the peripheral length increase rate after molding is A% or more and 11.0% or less as follows. A modified cross-section molding method characterized.
    A = 4.167 × 10 −3 × (TS-590)
    A: Lower limit of perimeter increase rate (%), TS: Tensile strength of pipe (MPa)
  7. 　前記潰し加工後の内圧負荷と併せて、管端に管軸方向の圧縮力を負荷して管端を管軸方向中央側に押し込むことを特徴とする請求項６に記載の異形断面成形方法。 The deformed cross-section forming method according to claim 6, wherein together with the internal pressure load after the crushing process, a compressive force in the tube axis direction is applied to the tube end and the tube end is pushed toward the center in the tube axis direction.
  8. 　請求項６または７において、前記管材として引張強さ７８０ＭＰａ以上の鋼管を用い、成形後の周長増加率が下記Ａ％以上１０．０％以下となるように成形することを特徴とする異形断面成形方法。
    　記
    　Ａ＝４．１６７×１０−３×（ＴＳ−５９０）
    　Ａ：周長増加率の下限（％）、ＴＳ：管材の引張強さ（ＭＰａ）     8. The modified cross section according to claim 6 or 7, wherein a steel pipe having a tensile strength of 780 MPa or more is used as the pipe material, and the peripheral length increase rate after the forming is A% or more and 10.0% or less below. Molding method.
    A = 4.167 × 10 −3 × (TS-590)
    A: Lower limit of perimeter increase rate (%), TS: Tensile strength of pipe (MPa)
  9. 　請求項６~８のいずれか１項において、前記管材として肉厚／外径比ｔ／Ｄが０．０５以下である鋼管を用いることを特徴とする異形断面成形方法。 9. The modified cross-section forming method according to claim 6, wherein a steel pipe having a thickness / outer diameter ratio t / D of 0.05 or less is used as the pipe material.
  10. 　管材を請求項６~９のいずれか１項に記載の異形断面成形方法で成形してなる一又は二の平行２辺を有する四辺形断面成形品であって、平坦部凹み量が０．５ｍｍ以下であり、さらにコーナーの曲率半径Ｒが１０ｍｍ以下であることを特徴とするスポット溶接性に優れた一又は二の平行２辺を有する四辺形断面成形品。 A quadrilateral cross-sectional molded product having one or two parallel two sides formed by molding a tubular material by the irregular cross-section molding method according to any one of claims 6 to 9, wherein a flat portion dent amount is 0.5 mm. A quadrilateral cross-sectional molded article having one or two parallel two sides excellent in spot weldability, wherein the corner radius of curvature R is 10 mm or less.
  11. 　引張強さ６９０ＭＰａ以上の管材に、内圧を負荷しない状態もしくは液体により５０ＭＰａ以下の内圧を負荷した状態で、少なくとも１つの面が平坦部を有する異形断面金型にて潰し加工を行い、引続き前記液体により最高内圧が、５０ＭＰａ超である内圧を負荷して、前記管材を異形断面形状に成形するにあたり、成形後の周長増加率が下記Ａ％以上１１．０％以下となるように成形することを特徴とする異形断面成形方法。
    　記
    　Ａ＝４．１６７×１０−３×（ＴＳ−５９０）
    　Ａ：周長増加率の下限（％）、ＴＳ：管材の引張強さ（ＭＰａ）     In a state in which an internal pressure is not applied to a pipe material having a tensile strength of 690 MPa or more or an internal pressure of 50 MPa or less is applied by a liquid, crushing processing is performed with a deformed cross-section mold having at least one flat portion, and the liquid is continuously applied. When forming the pipe material into an irregular cross-sectional shape by applying an internal pressure whose maximum internal pressure is more than 50 MPa, forming the peripheral length increase rate after molding to be A% or more and 11.0% or less below. A modified cross-section molding method characterized by the above.
    A = 4.167 × 10 −3 × (TS-590)
    A: Lower limit of perimeter increase rate (%), TS: Tensile strength of pipe (MPa)
  12. 　前記潰し加工後の内圧負荷と併せて、管端に管軸方向の圧縮力を負荷して管端を管軸方向中央側に押し込むことを特徴とする請求項１１に記載の異形断面成形方法。 The deformed cross-section forming method according to claim 11, wherein together with the internal pressure load after the crushing, a compressive force in the tube axis direction is applied to the tube end and the tube end is pushed toward the center in the tube axis direction.
  13. 　請求項１１または１２において、前記管材として引張強さ７８０ＭＰａ以上の鋼管を用い、成形後の周長増加率が下記Ａ％以上１０．０％以下となるように成形することを特徴とする異形断面成形方法。
    　記
    　Ａ＝４．１６７×１０−３×（ＴＳ−５９０）
    　Ａ：周長増加率の下限（％）、ＴＳ：管材の引張強さ（ＭＰａ）     13. The modified cross section according to claim 11 or 12, wherein a steel pipe having a tensile strength of 780 MPa or more is used as the pipe material, and the peripheral length increase rate after forming is A% or more and 10.0% or less below. Molding method.
    A = 4.167 × 10 −3 × (TS-590)
    A: Lower limit of perimeter increase rate (%), TS: Tensile strength of pipe (MPa)
  14. 　請求項１１~１３のいずれか１項において、前記管材として肉厚／外径比ｔ／Ｄが０．０５以下である鋼管を用いることを特徴とする異形断面成形方法。 14. The modified cross-section forming method according to claim 11, wherein a steel pipe having a thickness / outer diameter ratio t / D of 0.05 or less is used as the pipe material.
  15. 　管材を請求項１１~１４のいずれか１項に記載の異形断面成形方法で成形してなる一又は二の平行２辺を有する四辺形断面成形品であって、平坦部凹み量が０．５ｍｍ以下であり、さらにコーナーＲが１０ｍｍ以下であることを特徴とするスポット溶接性に優れた一又は二の平行２辺を有する四辺形断面成形品。 A quadrilateral cross-sectional molded product having one or two parallel two sides formed by molding a tubular material by the modified cross-section molding method according to any one of claims 11 to 14, wherein the flat portion dent amount is 0.5 mm. A quadrilateral cross-sectional molded article having one or two parallel two sides excellent in spot weldability, wherein the corner R is 10 mm or less.
PCT/JP2009/067123 2008-09-25 2009-09-24 Method for forming deformed cross-section and formed article of quadrilateral cross-section exhibiting excellent spot weldability WO2010035883A1 (en)

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EP09816295.1A EP2351623B1 (en) 2008-09-25 2009-09-24 Method for forming deformed cross-section and formed article of quadrilateral cross-section exhibiting excellent spot weldability
KR1020137017515A KR20130083492A (en) 2008-09-25 2009-09-24 Method for forming deformed cross-section and formed article of quadrilateral cross-section exhibiting excellent spot weldability
KR1020117006739A KR101322229B1 (en) 2008-09-25 2009-09-24 Method for forming deformed cross-section and formed article of quadrilateral cross-section exhibiting excellent spot weldability

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