WO2013118862A1 - Article embouti et procédé de fabrication de cet article - Google Patents

Article embouti et procédé de fabrication de cet article Download PDF

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Publication number
WO2013118862A1
WO2013118862A1 PCT/JP2013/053039 JP2013053039W WO2013118862A1 WO 2013118862 A1 WO2013118862 A1 WO 2013118862A1 JP 2013053039 W JP2013053039 W JP 2013053039W WO 2013118862 A1 WO2013118862 A1 WO 2013118862A1
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WO
WIPO (PCT)
Prior art keywords
press
temperature
steel plate
molding
mold
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PCT/JP2013/053039
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English (en)
Japanese (ja)
Inventor
圭介 沖田
池田　周之
純也 内藤
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株式会社神戸製鋼所
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Application filed by 株式会社神戸製鋼所 filed Critical 株式会社神戸製鋼所
Publication of WO2013118862A1 publication Critical patent/WO2013118862A1/fr

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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
    • B21D22/208—Deep-drawing by heating the blank or deep-drawing associated with heat treatment
    • 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
    • B21D37/00—Tools as parts of machines covered by this subclass
    • B21D37/16—Heating or cooling

Definitions

  • the present invention heats a steel sheet (blank) as a raw material to the Ac 1 transformation point or higher, and then press-forms it into a predetermined shape.
  • the present invention relates to a method for producing a press-molded product that can be quenched at the same time as shape imparting to obtain a predetermined strength, and a press-molded product obtained by such a production method.
  • the present invention relates to a method for manufacturing a molded product capable of realizing good molding without generating odor, a press-molded product, and the like.
  • a hot pressing method that simultaneously improves the strength of the component by press molding and quenching has been proposed (for example, Patent Document 1).
  • the steel sheet is heated to an austenite ( ⁇ ) region above the Ac 3 transformation point and hot pressed, and the steel sheet is simultaneously quenched by bringing it into contact with a normal temperature mold during press forming. This is a method for realizing high strength.
  • Such a hot pressing method since it is molded in a low strength state, the spring back is reduced (the shape freezing property is good), and a strength of a tensile strength of 1500 MPa class is obtained by rapid cooling.
  • a hot pressing method is called by various names such as a hot forming method, a hot stamping method, a hot stamp method, and a die quench method in addition to the hot pressing method.
  • FIG. 1 is a schematic explanatory view showing a mold configuration for carrying out hot press molding as described above (hereinafter sometimes referred to as “hot press”).
  • 3 is a blank holder
  • 4 is a steel plate (blank)
  • BHF is a crease pressing force
  • rp is a punch shoulder radius
  • rd is a die shoulder radius
  • CL is a punch / die clearance.
  • the punch 1 and the die 2 have passages 1a and 2a through which a cooling medium (for example, water) can pass, and the cooling medium is allowed to pass through the passages.
  • a cooling medium for example, water
  • the blank When hot pressing (for example, hot deep drawing) using such a mold, the blank (steel plate 4) should be at or above the two-phase region temperature (Ac 1 transformation point to Ac 3 transformation point) or the Ac 3 transformation point. Molding is started in a state of being softened by heating to a single phase temperature. That is, in a state where the steel plate 4 in a high temperature state is sandwiched between the die 2 and the blank holder 3, the steel plate 4 is pushed into the hole of the die 2 (between 2 and 2 in FIG. 1) by the punch 1, and the outer diameter of the steel plate 4 is reduced. While shrinking, it is formed into a shape corresponding to the outer shape of the punch 1.
  • the steel sheet is press-cooled at a high temperature of, for example, around 900 ° C., so that there is a temperature difference between the contact portion with the mold (punch 1 and die 2) and the portion that does not contact. It becomes easy to stick and distortion concentrates on a relatively high temperature part. For example, in deep drawing molding, the shrink flange is cooled and cannot be shrunk.
  • Patent Document 2 discloses that the medium carbon steel sheet is heated, cooled, press-formed, and further controlled by controlling the press-forming start temperature, stop temperature and press-forming time when further cooling, and forming at a lower temperature. It is disclosed that excellent press formability can be ensured by performing press molding without undergoing martensitic transformation until is completed. In particular, it has been proposed to start press forming after heating the steel sheet and then cooling the steel sheet.
  • the present invention has been made in view of the above circumstances, and the object thereof is obtained by a useful method for producing a press-formed product having good formability to such an extent that deep drawing can be performed, and such a production method. It is to provide a pressed product.
  • the method of press-molded article produced the present invention which could achieve the above object, impinges on the production of moldings steel by press molding using a mold having a punch and a die, the steel plate Ac 1 transformation point After heating to the above temperature, it is cooled to a temperature of 650 ° C. or less, and then forming is started, and the gist is that the coefficient of friction between the mold and the steel plate during forming is 0.3 or less. It is what you have.
  • a lubricant is applied to at least one of the mold and the steel sheet, (b) on the surface of the steel sheet. Either metal plating is formed or paint is applied, (c) the surface of the mold is coated, or the like can be used together.
  • the forming start temperature is preferably not less than the martensitic transformation start temperature Ms of the steel sheet.
  • the forming end temperature is preferably lower than the martensite transformation start temperature Ms of the steel sheet and higher than the martensite transformation end temperature Mf.
  • the present invention also includes a press-molded product obtained by the above method.
  • the steel sheet is heated to a temperature equal to or higher than the Ac 1 transformation point, then cooled to a temperature of 650 ° C. or lower, and then forming is started, and the coefficient of friction between the mold and the steel sheet during forming is determined. Since it was 0.3 or less, it became possible to produce a press-molded product without causing breakage or cracking during molding.
  • the present inventors have studied from various angles in order to produce a press-formed product having good formability when the steel sheet is heated to a temperature equal to or higher than the Ac 1 transformation point and then press-formed.
  • the forming is not started as it is, but the press forming is started after cooling to a temperature of 650 ° C. or less, and the mold and the steel sheet during forming
  • the coefficient of friction between and is 0.3 or less, good moldability can be secured without causing breakage or cracking during molding, and the present invention has been completed.
  • the present invention will be described in detail along the background of the completion of the present invention.
  • the present inventors first conducted experiments and analyzes to confirm the usefulness of the method of cooling the steel sheet before press forming in the direct method.
  • a cylindrical drawing was performed by an indirect method using a steel plate (thickness: 1.4 mm, circular blank having a diameter of 85 to 100 mm) having the chemical composition shown in Table 1 below.
  • a circular mold (cylindrical die and cylindrical punch) having a diameter of 50 mm was used as the mold.
  • Detailed press molding conditions are shown below.
  • the coefficient of friction between the mold and the steel plate was 0.13.
  • the limit drawing ratio at the time of molding was 1.8.
  • the limit drawing ratio was obtained by analysis.
  • the friction coefficient between the mold and the steel plate was 0.5 (measurement method will be described later).
  • five patterns of 400 ° C., 500 ° C., 600 ° C., 700 ° C., and 800 ° C. were analyzed as the molding start temperature.
  • the heating temperature of the steel plate at this time is 900 degreeC.
  • FIG. 2 This analysis result is shown in FIG. 2 (analysis points are indicated by ⁇ ).
  • the limit drawing ratio is high, It can be confirmed that the moldability is improved. However, it is inferior to the limit drawing ratio in the case of forming by the indirect method, and it can be seen that improvement of formability is insufficient only by cooling the steel plate before pressing in the direct method.
  • the coefficient of friction between the mold and the steel plate is set to 0.2, and the limit drawing ratio when the cylindrical deep drawing is performed by the method of cooling the steel plate before press forming in the direct method as described above is analyzed. Sought by. In this case, as shown by the solid line in FIG. 2 (analysis points are indicated by ⁇ ), when the forming temperature is lowered by cooling the steel plate before press forming, compared to the case of forming by the indirect method. In addition, a large limit drawing ratio was obtained, and it was confirmed that the moldability was excellent.
  • the molding start temperature exceeds 700 ° C., and the temperature is too high to obtain good moldability, and should be lower than 700 ° C. Specifically, 650 Must be below °C More preferably, if the temperature is 600 ° C. or lower, further improvement in moldability can be expected. Moreover, it is preferable that the lower limit value of the molding start temperature is equal to or higher than the martensite transformation start temperature Ms.
  • the temperature was set to 900 ° C. as described above.
  • the upper limit of the heating temperature is preferably up to about 1000 ° C. If the temperature is higher than 1000 ° C., the particle size of austenite becomes large during heating, and good moldability cannot be achieved. Further, when the temperature is higher than 1000 ° C., generation of oxide scale becomes remarkable (for example, 100 ⁇ m or more), and the plate thickness (thickness after descaling) of the molded product may be thinner than a predetermined one.
  • this temperature is less than the martensite transformation start temperature Ms, and the martensite transformation. It is preferable to set the temperature higher than the end temperature Mf.
  • the “molding end temperature” refers to the bottom dead center of molding (when the punch tip is located at the deepest part: the state shown in FIG. 1), and the mold is cooled and held to a predetermined temperature. It means the temperature when the mold is released.
  • the Ac 1 transformation point, Ac 3 transformation point, martensite transformation start temperature Ms, and martensite transformation end temperature Mf are obtained based on the following formulas (1) to (4) (for example, “ Heat treatment ”41 (3), 164 to 169, 2001 See Tetsuro Kunitake,“ Predicting Ac 1 , Ac 3 and Ms transformation points of steel by empirical formulas ”).
  • the Ac 1 transformation point, Ac 3 transformation point, martensite transformation start temperature Ms, and martensite transformation end temperature Mf of the steel sheets having the chemical composition shown in Table 1 are Ac 1 transformation point: 718 ° C. and Ac 3, respectively. Transformation point: 830 ° C., Ms: 411 ° C., Mf: 261 ° C.
  • the friction coefficient between the mold and the thin steel plate may be 0.3 or less. More preferably, it is 0.2 or less.
  • the means for setting the coefficient of friction between the mold and the thin steel sheet to 0.3 or less is not particularly limited.
  • the following means (1) to (3) are applicable, Any one of these may be used together.
  • the lubricant used at this time is not particularly limited, and any known lubricant can be used as long as the coefficient of friction between the mold and the thin steel plate can be 0.3 or less.
  • Illustrative examples include solid lubricants that use graphite, molybdenum disulfide, boron nitride, and the like, liquid lubricants, greases, and the like.
  • Plating may be formed or paint may be applied to the surface of the thin steel sheet. It does not specifically limit as plating and a coating material to be used, A well-known thing is employable as long as the friction coefficient between a metal mold
  • the surface of the mold may be coated.
  • the coating is not particularly limited, and any known coating can be used as long as the coefficient of friction between the mold and the thin steel plate is 0.3 or less.
  • Specific examples include an ICF film (intrinsic carbon film) including a DLC (diamond-like carbon) film, a CrSiN film by PVD, a TiBON film, a TiCN film, a TiC-Al 2 O 3 film by CVD, and the like. It is done.
  • a conventional hot press line generally has a configuration (equipment configuration) as shown in FIG. That is, as shown in FIG. 4, the coiled steel sheet 10 is cut out by a cutting machine 11 (Blanking), heated in a heating furnace 12, and then moved to a press molding machine 13 to be a press-formed product 14.
  • the cooling unit 15 is disposed in the second half region after heating (in FIG. 5, the same reference numerals are assigned to the portions corresponding to FIG. 4), and the steel plate 10 is moved from the heating furnace 12 to the press molding machine 13. What is necessary is just to make it cool in the cooling part 15 when moving.
  • the cooling can be performed by the following methods (1) to (4), for example.
  • a gas cooling means is provided to cool the gas jet.
  • a means for example, a cooling means using a water-cooling roll) for bringing into contact with a metal as a refrigerant is provided to remove heat.
  • a mist cooling means for cooling is provided.
  • a dry ice shot means (cooled by causing the granule dry ice to collide with the blank material) is cooled.
  • the molding unit 13 After cooling to a predetermined temperature by the cooling unit 15 as described above, the molding unit 13 is moved to the press molding machine 13 to perform molding while continuing cooling with the molding die even after the molding is started. It ’s fine.
  • a steel plate having the chemical composition shown in Table 1 (accordingly, Ac 1 transformation point of this steel plate: 718 ° C., Ac 3 transformation point: 830 ° C., martensite transformation start temperature Ms: 411 ° C., martensite transformation end temperature Mf) : 261 ° C.), and cylindrical drawing was performed by the direct method.
  • the steel plate used the non-plating material.
  • the press molding conditions at this time are the same mold (FIG. 1) as in the indirect method, wrinkle pressing force: 3 tons, molding speed: 100 mm / sec.
  • Five types of lubricants including solid lubrication and liquid lubrication (Table 2 below) were used as the lubricant, and DLC was used as the mold coating.
  • the molding start temperature in the examples was set to four patterns of 761 ° C., 633 ° C., 526 ° C., and 446 ° C.
  • the heating temperature was 900 ° C. and the heating temperature was 6 minutes.
  • the cooling of the steel sheet in the process of transporting the steel sheet from the heating furnace to the press machine, cold air was blown onto the blank, the cooling was rapidly performed at an average cooling rate of 25 ° C./second or more, and forming was started at each of the above temperatures. .
  • the forming start temperature was calculated by cooling the thin steel plate to which the thermocouple had been attached in advance, obtaining a cooling curve, and based on this, the quenching time from taking out the steel plate from the heating furnace until press forming was calculated.
  • the molding end temperature was 280 ° C. for all.
  • the press formability and Vickers hardness of the molded product in each test were evaluated. Note that the press formability is higher than the limit drawing ratio of 1.8 in the indirect method when it can be formed without cracking under the condition of blank diameter: 95 mm (drawing ratio: 1.9). Formability was evaluated as ⁇ (“X” when there was a break or crack, “ ⁇ ” when there was no break).
  • the Vickers hardness of the molded product was evaluated by measuring the Vickers hardness at the center of the thickness of the bottom portion, the R portion, and the vertical wall portion, and evaluating the average value. The results are shown in the following Table 3 (Test Nos. 1 to 14) and Table 4 (Test Nos. 15 to 28) together with the type of frictional resistance reduction treatment, heating conditions, cooling method, and molding conditions.
  • Each lubricant was sprayed or applied to the lower surface of the die 2 in FIG. 1 (the surface in contact with the steel plate) and the upper surface of the blank holder 3 so as to be as uniform as possible about 20 g / m 2 .
  • the ion nitriding process was performed before the process and it formed into a film by physical vapor deposition (PVD). The film thickness at this time is about 1 ⁇ m.
  • the steel plate in manufacturing a molded product by press-molding a steel plate using a die having a punch and a die, the steel plate is heated to a temperature not lower than the Ac 1 transformation point and then cooled to a temperature not higher than 650 ° C.
  • Useful methods for manufacturing can be realized.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Shaping Metal By Deep-Drawing, Or The Like (AREA)
  • Mounting, Exchange, And Manufacturing Of Dies (AREA)

Abstract

L'invention porte sur des articles emboutis. Lors de la fabrication d'un article embouti au moyen d'un moule métallique qui comprend un poinçon et une matrice pour emboutir une tôle d'acier, après le chauffage de la tôle d'acier à une température qui est au moins égale à un point de transformation Ac1, en déclenchant l'emboutissage après que la tôle soit refroidie à 650°C ou moins, et en maintenant le coefficient de frottement entre le moule métallique et la tôle d'acier pendant l'emboutissage à 0,3 ou moins, ce procédé peut être utilisé pour fabriquer un article embouti ayant une excellente aptitude à l'emboutissage qui autorise un emboutissage profond.
PCT/JP2013/053039 2012-02-10 2013-02-08 Article embouti et procédé de fabrication de cet article WO2013118862A1 (fr)

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JP2012-027649 2012-02-10
JP2012027649 2012-02-10

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
TWI623361B (zh) * 2016-10-04 2018-05-11 Nippon Steel & Sumitomo Metal Corp Hot pressing method and hot pressing system
JP2020510757A (ja) * 2017-03-01 2020-04-09 エーケー スティール プロパティ−ズ、インク． 極めて高い強度を有するプレス硬化鋼および製造方法

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP6192521B2 (ja) * 2013-12-06 2017-09-06 三菱重工業株式会社 スウェージツール
JP6211987B2 (ja) * 2014-04-22 2017-10-11 株式会社神戸製鋼所 Ｚｎめっき鋼板の熱間成形用金型
MX2021012218A (es) 2019-04-29 2021-12-10 Autotech Eng Sl Aparato de conformacion por prensado en caliente y metodo para la conformacion por prensado en caliente de una pieza en bruto.
JP2021122839A (ja) * 2020-02-04 2021-08-30 日本製鉄株式会社 プレス成形品の製造方法

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JP2001353548A (ja) * 2000-04-07 2001-12-25 Usinor 極めて高い機械的特性値をもつ成形部品を被覆圧延鋼板、特に被覆熱間圧延鋼板の帯材から型打ちによって製造する方法
JP2005060619A (ja) * 2003-08-19 2005-03-10 Toyota Central Res & Dev Lab Inc 金属塑性加工用潤滑剤
JP2005329449A (ja) * 2004-05-21 2005-12-02 Kobe Steel Ltd 温熱間成形品の製造方法および成形品
JP2010099735A (ja) * 2008-09-24 2010-05-06 Hitachi Metals Ltd 塑性加工用被覆金型
JP2011183451A (ja) * 2010-03-11 2011-09-22 Jfe Steel Corp 高温摺動試験装置

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JP4673558B2 (ja) * 2004-01-26 2011-04-20 新日本製鐵株式会社 生産性に優れた熱間プレス成形方法及び自動車用部材
JP3816937B1 (ja) * 2005-03-31 2006-08-30 株式会社神戸製鋼所 熱間成形品用鋼板およびその製造方法並びに熱間成形品

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Publication number Priority date Publication date Assignee Title
JP2001353548A (ja) * 2000-04-07 2001-12-25 Usinor 極めて高い機械的特性値をもつ成形部品を被覆圧延鋼板、特に被覆熱間圧延鋼板の帯材から型打ちによって製造する方法
JP2005060619A (ja) * 2003-08-19 2005-03-10 Toyota Central Res & Dev Lab Inc 金属塑性加工用潤滑剤
JP2005329449A (ja) * 2004-05-21 2005-12-02 Kobe Steel Ltd 温熱間成形品の製造方法および成形品
JP2010099735A (ja) * 2008-09-24 2010-05-06 Hitachi Metals Ltd 塑性加工用被覆金型
JP2011183451A (ja) * 2010-03-11 2011-09-22 Jfe Steel Corp 高温摺動試験装置

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
TWI623361B (zh) * 2016-10-04 2018-05-11 Nippon Steel & Sumitomo Metal Corp Hot pressing method and hot pressing system
JP2020510757A (ja) * 2017-03-01 2020-04-09 エーケー スティール プロパティ−ズ、インク． 極めて高い強度を有するプレス硬化鋼および製造方法
US11913099B2 (en) 2017-03-01 2024-02-27 Cleveland-Cliffs Steel Properties Inc. Press hardened steel with extremely high strength and method for production

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