JP2020185591A - Press molding method - Google Patents
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- JP2020185591A JP2020185591A JP2019091808A JP2019091808A JP2020185591A JP 2020185591 A JP2020185591 A JP 2020185591A JP 2019091808 A JP2019091808 A JP 2019091808A JP 2019091808 A JP2019091808 A JP 2019091808A JP 2020185591 A JP2020185591 A JP 2020185591A
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本発明は、プレス成形方法に関し、特に、天板部、縦壁部及びフランジ部を有する断面ハット形状であり、側面視で長手方向に沿って高さ方向に凸状に湾曲する部位を有するプレス成形品のプレス成形方法に関する。 The present invention relates to a press molding method, in particular, a press having a cross-sectional hat shape having a top plate portion, a vertical wall portion, and a flange portion, and having a portion curved in a height direction along the longitudinal direction in a side view. The present invention relates to a press molding method for a molded product.
プレス成形は、鋼板等の金属板（ブランク材）を一対の金型の間に挟んで挟圧して該金属板を金型の形状に倣うよう成形することで、該金属板を様々な形状の部品（プレス成形品）に加工する方法である。しかしながら、天板部と縦壁部とフランジ部とを有する断面ハット形状であって長手方向に沿って高さ方向に湾曲するプレス成形品（以下、「湾曲部品」という場合がある。）のプレス成形においては、フランジ部や天板部にしわが発生する場合がある。特に、近年では高張力鋼板を用いたプレス成形品が増えており、鋼板の強度が増加するに伴ってプレス成形品にしわが発生しやすくなるという問題がある。そのため、高張力鋼板を用いた場合にあっては、しわの発生をいかに抑制しながらプレス成形を行うかが課題となっている。 In press forming, a metal plate (blank material) such as a steel plate is sandwiched between a pair of dies and pressed to form the metal plate so as to follow the shape of the dies. This is a method of processing into parts (press molded products). However, a press of a press-molded product (hereinafter, may be referred to as a "curved part") having a cross-sectional hat shape having a top plate portion, a vertical wall portion, and a flange portion and curved in the height direction along the longitudinal direction. In molding, wrinkles may occur on the flange portion and the top plate portion. In particular, in recent years, the number of press-molded products using high-strength steel sheets has increased, and there is a problem that wrinkles are likely to occur in the press-molded products as the strength of the steel sheet increases. Therefore, when a high-strength steel plate is used, how to perform press forming while suppressing the occurrence of wrinkles is an issue.
これまでに、しわを抑制して湾曲部品をプレス成形する技術がいくつか提案されている。
例えば、特許文献１には、長手方向の平面外で屈曲部を有する金属製断面ハット型形状部材を成形するに際し、天板部と縦壁部が形成する稜線部に、又は、該稜線部及び縦壁部とフランジ部が形成する角部の両方にフィレット部を形成することで、しわを抑制する技術が開示されている。
また、特許文献２には、天面部の幅方向端縁が長手方向に沿って湾曲する断面ハット状の湾曲プレス部品をプレス成形するに際し、平板状のブランク材の幅方向の端部にビードや折曲部などの高剛性部を設ける予備成形工程と、該高剛性部を残した状態で天面部と側壁部とを成形する本成形工程により、フランジ部におけるシワを抑制する技術が開示されている。
さらに、特許文献３には、上下方向に湾曲した湾曲部品に対し、パッドでブランクのパンチ底を板厚方向に加圧しながら該ブランクの端部をダイとホルダとで挟持してドロー成形を行うことで、しわを抑制する技術が開示されている。
So far, some techniques for suppressing wrinkles and press-molding curved parts have been proposed.
For example, in Patent Document 1, when forming a metal cross-section hat-shaped member having a bent portion outside a plane in the longitudinal direction, the ridge portion formed by the top plate portion and the vertical wall portion, or the ridge portion and the ridge portion A technique for suppressing wrinkles by forming fillets on both the vertical wall portion and the corner portion formed by the flange portion is disclosed.
Further, in Patent Document 2, when a curved press part having a hat-shaped cross section in which the widthwise edge of the top surface portion is curved along the longitudinal direction is press-molded, a bead or a bead or a bead is provided on the widthwise end portion of the flat plate-shaped blank material. A technique for suppressing wrinkles in a flange portion is disclosed by a pre-molding step of providing a high-rigidity portion such as a bent portion and a main molding step of molding a top surface portion and a side wall portion while leaving the high-rigidity portion. There is.
Further, in Patent Document 3, for a curved part curved in the vertical direction, the punch bottom of the blank is pressed in the plate thickness direction by a pad, and the end portion of the blank is sandwiched between a die and a holder to perform draw molding. As a result, a technique for suppressing wrinkles is disclosed.
しかしながら、特許文献１に開示されている技術は、１工程で金属製断面ハット型形状部材を成形するものであり、フィレット部を充分に押し潰すことができずに残ってしまい、目標形状の部品の剛性を低下させる要因になりやすいという問題がある。 However, the technique disclosed in Patent Document 1 is for molding a metal cross-section hat-shaped member in one step, and the fillet portion cannot be sufficiently crushed and remains, so that a component having a target shape is formed. There is a problem that it tends to be a factor that lowers the rigidity of the.
また、特許文献２に開示されている技術は、本成形工程に続くフランジ部平坦化工程において、ブランク材の幅方向の端部に形成されたビードや折曲部を平坦に押し潰すものであるが、該ビードや折曲部が十分に平坦に押し潰されない場合があった。 Further, the technique disclosed in Patent Document 2 flatly crushes a bead or a bent portion formed at an end portion in the width direction of a blank material in a flange portion flattening step following the main molding step. However, the bead or the bent portion may not be crushed sufficiently flatly.
さらに、特許文献３に開示されている技術は、凹状湾曲部の天板や凸状湾曲部のフランジにおけるしわを抑制するため、パッドでブランクのパンチ底を板厚方向に加圧しながら該ブランクの端部をダイとホルダとで挟持して縦壁部を絞り加工で成形するため、該縦壁部においてはスプリングバックによる壁の反りが生じて問題となる場合があった。 Further, in the technique disclosed in Patent Document 3, in order to suppress wrinkles on the top plate of the concave curved portion and the flange of the convex curved portion, the punch bottom of the blank is pressed with a pad in the plate thickness direction of the blank. Since the end portion is sandwiched between the die and the holder and the vertical wall portion is formed by drawing, the vertical wall portion may be warped due to springback, which may cause a problem.
本発明は、上記のような課題を解決するためになされたものであり、天板部、縦壁部及びフランジ部を有する断面ハット形状であり、長手方向に沿って高さ方向に凸状に湾曲するプレス成形品を、しわを抑制してプレス成形することができるプレス成形方法を提供することを目的とする。 The present invention has been made to solve the above problems, and has a cross-sectional hat shape having a top plate portion, a vertical wall portion, and a flange portion, and is convex in the height direction along the longitudinal direction. It is an object of the present invention to provide a press forming method capable of press-forming a curved press-molded product while suppressing wrinkles.
＜発明に至った経緯＞
図１（ａ）に一例として示すような、天板部３と、天板部３から連続する縦壁部５と、縦壁部５から連続するフランジ部７とを有する断面ハット形状であり、側面視で天板部３とフランジ部７とが長手方向に沿って高さ方向に凸状に湾曲する凸状湾曲部位９を有するプレス成形品１を、従来技術のように１工程でプレス成形すると、しわがフランジ部７に生じやすく、特に、湾曲の大きい凸状湾曲部位９に生じやすい。
<Background to the invention>
As shown as an example in FIG. 1A, it has a cross-sectional hat shape having a top plate portion 3, a vertical wall portion 5 continuous from the top plate portion 3, and a flange portion 7 continuous from the vertical wall portion 5. A press-molded product 1 having a convex curved portion 9 in which the top plate portion 3 and the flange portion 7 are curved in the height direction along the longitudinal direction in a side view is press-molded in one step as in the prior art. Then, wrinkles are likely to occur on the flange portion 7, and particularly on the convex curved portion 9 having a large curvature.
これは、金属板である平板状のブランク材をその垂直方向に向かって凸状に湾曲させるため、縦壁部５からフランジ部７に向かう材料流れが凸状湾曲部位９に集中する結果、しわが発生するためである。したがって、しわを抑制するためには、プレス成形過程において縦壁部５からフランジ部７への材料流れを生じさせないようにすることが必要となる。 This is because the flat plate-shaped blank material, which is a metal plate, is curved convexly in the vertical direction, and as a result, the material flow from the vertical wall portion 5 to the flange portion 7 is concentrated on the convex curved portion 9. This is because I will occur. Therefore, in order to suppress wrinkles, it is necessary to prevent the material from flowing from the vertical wall portion 5 to the flange portion 7 in the press molding process.
そこで、本発明者は、長手方向に沿って凸状に湾曲するプレス成形品１をプレス成形するに際し、その縦壁部５からフランジ部７への材料流れを生じさせないようにする方法を鋭意検討した。その結果、まずは目標形状よりも長手方向中央から端部に至るほど平坦に押し潰された中間形状にプレス成形し、続いて該中間形状のプレス成形品をフォーム成形することにより曲げ成形のみで目標形状にプレス成形することにより、縦壁部５からフランジ部７への材料流れを抑制することを想到した。 Therefore, the present inventor has diligently studied a method for preventing a material flow from the vertical wall portion 5 to the flange portion 7 when the press-molded product 1 which is curved in a convex shape along the longitudinal direction is press-molded. did. As a result, first, press molding is performed into an intermediate shape that is crushed flat from the center to the end in the longitudinal direction from the target shape, and then the press-molded product of the intermediate shape is form-formed to achieve the target only by bending. The idea was to suppress the material flow from the vertical wall portion 5 to the flange portion 7 by press-molding into a shape.
次に、目標形状よりも平坦な中間形状をどのように決定するかについて検討した。検討においては、金属板の端部側は中央に比べて変形が容易であることに着目した。そこで、目標形状のプレス成形品をその長手方向の両端から中央に向かって圧縮させることで、断面線長を維持したまま天板部と縦壁部の開き角度が大きくなって縦壁部の縦壁高さが小さくなること、さらには、長手方向の中央に比べて端部側の方が開き角度は大きく縦壁高さは低くなることを見出した。そして、このような中間形状をフォーム成形することで、しわを抑制して目標形状にプレス成形できるという知見が得られた。 Next, we examined how to determine an intermediate shape that is flatter than the target shape. In the study, we focused on the fact that the edge side of the metal plate is easier to deform than the center. Therefore, by compressing the press-molded product of the target shape from both ends in the longitudinal direction toward the center, the opening angle between the top plate and the vertical wall is increased while maintaining the cross-sectional line length, and the vertical wall is vertical. It was found that the wall height becomes smaller, and that the opening angle is larger and the vertical wall height is lower on the end side than in the center in the longitudinal direction. Then, it was found that by forming such an intermediate shape into a foam, wrinkles can be suppressed and press molding can be performed to a target shape.
本発明は係る知見に基づいてなされたものであり、具体的には、以下の構成を備えてなるものである。 The present invention has been made based on the above findings, and specifically, it has the following configurations.
（１）本発明に係るプレス成形方法は、天板部と、該天板部から連続する縦壁部と、該縦壁部から連続するフランジ部とを有する断面ハット形状であり、前記天板部及び／又は前記フランジ部が側面視で長手方向に沿って高さ方向に凸状に湾曲する凸状湾曲部位を有するプレス成形品をプレス成形するものであって、前記プレス成形品の目標形状に比べて、長手方向長さが短くて前記凸状湾曲部位が前記目標形状よりも大きく湾曲し、かつ該凸状湾曲部位における前記天板部と前記縦壁部との開き角度が大きくて前記縦壁部の縦壁高さが低い中間形状のプレス成形品をプレス成形する中間形状成形工程と、該中間形状のプレス成形品をフォーム成形により目標形状にプレス成形する目標形状成形工程と、を備えたことを特徴とするものである。 (1) The press molding method according to the present invention has a cross-sectional hat shape having a top plate portion, a vertical wall portion continuous from the top plate portion, and a flange portion continuous from the vertical wall portion, and the top plate A press-molded product having a convex curved portion in which the portion and / or the flange portion is convexly curved in the height direction along the longitudinal direction in a side view is press-molded, and the target shape of the press-molded product. Compared to the above, the length in the longitudinal direction is short, the convex curved portion is curved larger than the target shape, and the opening angle between the top plate portion and the vertical wall portion at the convex curved portion is large. An intermediate shape forming step of press-molding an intermediate-shaped press-molded product having a low vertical wall height of a vertical wall portion and a target shape forming step of press-molding the intermediate-shaped press-molded product to a target shape by foam molding. It is characterized by being prepared.
（２）上記（１）に記載のものにおいて、前記中間形状成形工程における前記中間形状は、前記目標形状と同一形状の成形品モデルを設定し、該成形品モデルの長手方向の両端面に中央に向かう荷重又は変位を与えて成形解析を行うことにより決定することを特徴とするものである。 (2) In the one described in (1) above, the intermediate shape in the intermediate shape molding step sets a molded product model having the same shape as the target shape, and is centered on both end faces in the longitudinal direction of the molded product model. It is characterized in that it is determined by applying a load or displacement toward the shape and performing a molding analysis.
（３）上記（２）に記載のものにおいて、前記中間形状成形工程における前記中間形状は、前記成形解析後の中間形状モデルについて、その長手方向の端部側をさらに平坦にする逆解析を行うことにより決定することを特徴とするものである。 (3) In the above-described item (2), the intermediate shape in the intermediate shape forming step is subjected to an inverse analysis of the intermediate shape model after the molding analysis to further flatten the end side in the longitudinal direction. It is characterized by being determined by.
（４）上記（１）に記載のものにおいて、前記中間形状成形工程における前記中間形状は、前記目標形状と同一形状の成形品モデルを設定し、該成形品モデルについてその長手方向の端部側を平坦にする逆解析を行い、該逆解析した後の中間形状モデルの長手方向の両端面に中央に向かう荷重又は変位を与えて成形解析を行うことにより決定することを特徴とするものである。 (4) In the one described in (1) above, the intermediate shape in the intermediate shape molding step sets a molded product model having the same shape as the target shape, and the end side of the molded product model in the longitudinal direction thereof. It is characterized in that it is determined by performing an inverse analysis to flatten the surface, applying a load or displacement toward the center to both end faces in the longitudinal direction of the intermediate shape model after the inverse analysis, and performing a molding analysis. ..
本発明においては、天板部と、該天板部から連続する縦壁部と、該縦壁部から連続するフランジ部とを有する断面ハット形状であり、前記天板部及び／又は前記フランジ部が側面視で長手方向に沿って高さ方向に凸状に湾曲する凸状湾曲部位を有するプレス成形品をプレス成形するものであって、前記プレス成形品の目標形状に比べて、長手方向長さが短くて前記凸状湾曲部位が前記目標形状よりも大きく湾曲し、かつ該凸状湾曲部位における前記天板部と前記縦壁部との開き角度が大きくて前記縦壁部の縦壁高さが低い中間形状のプレス成形品をプレス成形する中間形状成形工程と、該中間形状のプレス成形品をフォーム成形により目標形状にプレス成形する目標形状成形工程と、を備えたことにより、プレス成形過程における縦壁部からフランジ部への材料流れを抑制し、フランジ部におけるしわを抑制することができる。 In the present invention, the cross-sectional hat shape has a top plate portion, a vertical wall portion continuous from the top plate portion, and a flange portion continuous from the vertical wall portion, and the top plate portion and / or the flange portion. Is a press-molded product having a convex curved portion that is convexly curved in the height direction along the longitudinal direction in a side view, and is longer in the longitudinal direction than the target shape of the press-molded product. The convex curved portion is curved more than the target shape due to a short flange, and the opening angle between the top plate portion and the vertical wall portion at the convex curved portion is large, and the vertical wall height of the vertical wall portion is large. By providing an intermediate shape forming step of press-molding an intermediate-shaped press-molded product having a low flange and a target shape forming step of press-molding the intermediate-shaped press-molded product into a target shape by foam molding, press molding is provided. It is possible to suppress the material flow from the vertical wall portion to the flange portion in the process and suppress wrinkles in the flange portion.
本発明の実施の形態に係るプレス成形方法は、図１（ａ）に示すように、長手方向に沿って高さ方向に湾曲するプレス成形品１をプレス成形するものであって、図１（ｂ）に示すような中間形状のプレス成形品１１に成形する中間形状成形工程と、中間形状のプレス成形品１１をフォーム成形により目標形状のプレス成形品１にプレス成形する目標形状成形工程と、を備えたものである。以下、各工程について説明する。
なお、本発明において、長手方向に沿って高さ方向に凸状に湾曲するとは、側面視において凸状に湾曲した円弧の中心がフランジ部７側に位置することをいう。
As shown in FIG. 1A, the press molding method according to the embodiment of the present invention press-molds a press-molded product 1 that is curved in the height direction along the longitudinal direction, and is shown in FIG. An intermediate shape molding step of molding into an intermediate shape press-molded product 11 as shown in b), and a target shape molding step of press-molding the intermediate shape press-molded product 11 into a target-shaped press-molded product 1 by foam molding. It is equipped with. Hereinafter, each step will be described.
In the present invention, "curving convexly in the height direction along the longitudinal direction" means that the center of the convexally curved arc is located on the flange portion 7 side in the side view.
＜中間形状成形工程＞
中間形状成形工程は、図１（ｂ）に示すように、プレス成形品１の目標形状に比べて、長手方向長さLが短くて凸状湾曲部位１９が前記目標形状よりも大きく湾曲し、かつ凸状湾曲部位１９における天板部１３と縦壁部１５との開き角度が大きくて縦壁部１５の縦壁高さが低い中間形状のプレス成形品１１をプレス成形する工程である。
<Intermediate shape molding process>
In the intermediate shape forming step, as shown in FIG. 1 (b), the length L in the longitudinal direction is shorter than the target shape of the press-molded product 1, and the convex curved portion 19 is curved more than the target shape. In addition, this is a step of press-molding an intermediate-shaped press-molded product 11 in which the opening angle between the top plate portion 13 and the vertical wall portion 15 in the convex curved portion 19 is large and the vertical wall height of the vertical wall portion 15 is low.
ここで、凸状湾曲部位１９が前記目標形状よりも大きく湾曲する形状とは、図１（ａ）に示すように目標形状の凸状湾曲部位９の長手方向の両端面に中央に向かう荷重を与えることにより、長手方向長さLが目標形状の長手方向長さL0よりも短くなって目標形状の凸状湾曲部位９の曲率よりも大きくなった形状のことをいう。 Here, the shape in which the convex curved portion 19 is curved more than the target shape means that, as shown in FIG. 1A, a load toward the center is applied to both end faces of the convex curved portion 9 of the target shape in the longitudinal direction. By giving, the length L in the longitudinal direction becomes shorter than the length L 0 in the longitudinal direction of the target shape and becomes larger than the curvature of the convex curved portion 9 of the target shape.
また、天板部１３と縦壁部１５との開き角度は、天板部１３と縦壁部１５のなす角度のうち断面ハット形状の内側における角度であり、縦壁部１５の縦壁高さは、高さ方向における縦壁部１５の高さである（後述する図３中の縦壁高さHに該当）。 The opening angle between the top plate portion 13 and the vertical wall portion 15 is the angle formed by the top plate portion 13 and the vertical wall portion 15 inside the cross-sectional hat shape, and is the vertical wall height of the vertical wall portion 15. Is the height of the vertical wall portion 15 in the height direction (corresponding to the vertical wall height H in FIG. 3 described later).
そして、中間形状のプレス成形品１１における凸状湾曲部位１９の長手方向長さL（図１（ｂ））は、目標形状のプレス成形品１における凸状湾曲部位９の長手方向長さL0（図１（ａ））に対する変化割合(＝(L0−L)／L0)が10%以上であることが好ましい。 The longitudinal length L (FIG. 1 (b)) of the convex curved portion 19 in the intermediate-shaped press-molded product 11 is the longitudinal length L 0 of the convex curved portion 9 in the target-shaped press-molded product 1. The rate of change (= (L 0 −L) / L 0 ) with respect to (FIG. 1 (a)) is preferably 10% or more.
なお、中間形状成形工程における中間形状の具体的な決定方法については後述する。
また、中間形状成形工程は、ドロー成形又はフォーム成形のいずれであってもよい。
The specific method for determining the intermediate shape in the intermediate shape forming step will be described later.
Further, the intermediate shape molding step may be either draw molding or foam molding.
＜目標形状成形工程＞
目標形状成形工程は、中間形状のプレス成形品１１をフォーム成形により目標形状のプレス成形品１にプレス成形する工程である。
<Target shape forming process>
The target shape forming step is a step of press-molding the intermediate-shaped press-molded product 11 into the target-shaped press-molded product 1 by foam molding.
＜中間形状の決定方法＞
中間形状成形工程における中間形状は、以下の（ａ）〜（ｃ）に示す方法により決定することができる。
<Method of determining intermediate shape>
The intermediate shape in the intermediate shape forming step can be determined by the methods shown in (a) to (c) below.
（ａ）目標形状のプレス成形品と同一形状の成形品モデルを設定し、該成形品モデルの長手方向の両端面に中央に向かう荷重又は変位を与えて成形解析を行うことにより決定する。 (A) It is determined by setting a molded product model having the same shape as the press-molded product having the target shape, applying a load or displacement toward the center to both end faces in the longitudinal direction of the molded product model, and performing molding analysis.
成形解析後の中間形状モデルは、目標形状よりも長手方向長さが短くなって凸状湾曲部位（プレス成形品１１の凸状湾曲部位１９に相当）の高さ方向に大きく湾曲する。さらに、成形解析後の中間形状モデルは、目標形状における断面線長を維持したまま、天板部（プレス成形品１１の天板部１３に相当）と縦壁部（プレス成形品１１の縦壁部１５に相当）との開き角度が目標形状に比べて大きくなって縦壁部の縦壁高さが低くなる。さらに、成形解析後の中間形状モデルにおいては、長手方向の中央に比べて端部側の方が、天板部と縦壁部との開き角度が大きくて縦壁高さが低い。
このような成形解析後の中間形状モデルの形状を、中間形状成形工程における中間形状として決定する。
The intermediate shape model after the molding analysis has a length shorter in the longitudinal direction than the target shape and is largely curved in the height direction of the convex curved portion (corresponding to the convex curved portion 19 of the press-molded product 11). Further, in the intermediate shape model after the molding analysis, the top plate portion (corresponding to the top plate portion 13 of the press molded product 11) and the vertical wall portion (vertical wall of the press molded product 11) while maintaining the cross-sectional line length in the target shape. The opening angle with (corresponding to the portion 15) becomes larger than the target shape, and the vertical wall height of the vertical wall portion becomes lower. Further, in the intermediate shape model after the molding analysis, the opening angle between the top plate portion and the vertical wall portion is larger and the vertical wall height is lower on the end side than in the center in the longitudinal direction.
The shape of the intermediate shape model after such molding analysis is determined as the intermediate shape in the intermediate shape forming step.
（ｂ）上記（ａ）と同様に、目標形状のプレス成形品と同一形状に設定した成形品モデルの成形解析を行い、該成形解析を行った成形品モデルについてその長手方向の端部側をさらに平坦にする逆解析を行うことにより決定する。 (B) In the same manner as in (a) above, the molding analysis of the molded product model set to have the same shape as the press-molded product of the target shape is performed, and the end side in the longitudinal direction of the molded product model for which the molding analysis is performed is performed. It is determined by performing an inverse analysis to further flatten.
逆解析とは、成形対象とする目標形状にプレス成形されたプレス成形品を、プレス成形前の平板状のブランク材またはその途中の形状に戻す解析である。具体的には、例えば、成形対象とする目標形状のプレス成形品を要素分割した成形品モデルを設定し、これをひずみエネルギーが最小または所定値まで低減するように（要素同士が重なることなく、また各要素の変形が最小または所定値まで低減するように）することで、プレス成形前の平板状のブランク材または中間形状に展開する。 The inverse analysis is an analysis in which a press-molded product press-molded to a target shape to be molded is returned to a flat plate-shaped blank material before press molding or a shape in the middle thereof. Specifically, for example, a molded product model in which a press-molded product having a target shape to be molded is divided into elements is set, and the strain energy is reduced to the minimum or a predetermined value (without overlapping the elements). Further, by reducing the deformation of each element to the minimum or a predetermined value), it is developed into a flat plate-shaped blank material or an intermediate shape before press molding.
まず、目標形状の成形品モデルについて成形解析を行うことにより、前述のとおり、目標形状に比べて長手方向の両端から中央に向かって圧縮されて長手方向長さが短くなり、該成形品モデルにおける凸状湾曲部位（プレス成形品１１の凸状湾曲部位１９に相当）は、目標形状よりも大きく湾曲した形状の成形解析後の成形品モデルが得られる。
そして、該成形解析後の成形品モデルについてその長手方向の端部側を平坦にする逆解析を行うことにより、天板部（プレス成形品１１の天板部１３に相当）と縦壁部（プレス成形品１１の縦壁部１５に相当）との開き角度はさらに大きくなって縦壁部の縦壁高さは低くなった形状の逆解析後の中間形状モデルが得られる。そして、このような逆解析後の中間形状モデルの形状を、中間形状成形工程における中間形状として決定する。
First, by performing a molding analysis on a molded product model of the target shape, as described above, the molded product model is compressed from both ends in the longitudinal direction toward the center and the length in the longitudinal direction is shortened as compared with the target shape. As the convex curved portion (corresponding to the convex curved portion 19 of the press-molded product 11), a molded product model after molding analysis of a shape curved larger than the target shape can be obtained.
Then, by performing an inverse analysis of flattening the end side in the longitudinal direction of the molded product model after the molding analysis, the top plate portion (corresponding to the top plate portion 13 of the press molded product 11) and the vertical wall portion (corresponding to the top plate portion 13 of the press molded product 11) An intermediate shape model after inverse analysis of the shape in which the opening angle with the vertical wall portion 15 of the press-molded product 11 (corresponding to the vertical wall portion 15) is further increased and the vertical wall height of the vertical wall portion is lowered can be obtained. Then, the shape of the intermediate shape model after such inverse analysis is determined as the intermediate shape in the intermediate shape forming step.
当該（ｂ）の方法により決定される中間形状は、上記（ａ）の方法により決定された中間形状と同様に、目標形状に比べて長手方向長さが小さく、高さ方向にさらに凸状に湾曲した形状であることに加え、長手方向の中央に比べて端部側が平坦な形状をより適切に決定することができる。 The intermediate shape determined by the method (b) has a shorter longitudinal length than the target shape and is more convex in the height direction, similarly to the intermediate shape determined by the method (a). In addition to having a curved shape, it is possible to more appropriately determine a shape whose end side is flat as compared with the center in the longitudinal direction.
なお、一般的に逆解析は、プレス成形品の全領域を解析対象として平板状のブランク材に展開する。しかしながら、本発明における逆解析は、プレス成形品をモデル化した成形品モデルのうち少なくとも長手方向の端部側の所定の範囲が平坦化またはその途中の形状となるように展開するものである。そのため、本発明での逆解析においては、平坦化またはその途中形状とする長手方向の端部側における所定の範囲は、適宜設定すればよい。 In general, the inverse analysis is performed on a flat blank material with the entire region of the press-molded product as the analysis target. However, the inverse analysis in the present invention is developed so that at least a predetermined range on the end side in the longitudinal direction of the molded product model of the press-molded product is flattened or has a shape in the middle thereof. Therefore, in the inverse analysis in the present invention, a predetermined range on the end side in the longitudinal direction to be flattened or its intermediate shape may be appropriately set.
（ｃ）目標形状と同一形状に設定した成形品モデルについて、その長手方向の端部側を平坦にする逆解析を行う。続いて、逆解析を行った中間形状モデルの長手方向の両端面に中央に向かう荷重又は変位を与えて成形解析を行う。そして、成形解析した中間形状モデルの形状を、中間形状成形工程における中間形状として決定する。 (C) For a molded product model set to have the same shape as the target shape, an inverse analysis is performed to flatten the end side in the longitudinal direction. Subsequently, the molding analysis is performed by applying a load or displacement toward the center to both end faces in the longitudinal direction of the intermediate shape model for which the inverse analysis has been performed. Then, the shape of the intermediate shape model analyzed by molding is determined as the intermediate shape in the intermediate shape molding step.
当該（ｃ）の方法により決定される中間形状は、前述の（ｂ）の方法と同様に、目標形状に比べて、長手方向長さが短くて高さ方向に大きく湾曲した形状であることに加え、長手方向の中央に比べて端部側がさらに平坦な形状である。 The intermediate shape determined by the method (c) is a shape having a shorter length in the longitudinal direction and a large curvature in the height direction as compared with the target shape, as in the method (b) described above. In addition, the end side is flatter than the center in the longitudinal direction.
なお、上記（ａ）乃至（ｃ）のいずれかの方法で決定された中間形状のプレス成形品１１は、前述のとおり目標形状のプレス成形品１の長手方向の両端から中央に向かって圧縮され、凸状湾曲部位１９が目標形状よりも湾曲したものである。そのため、中間形状のプレス成形品１１において、天板部１３と縦壁部１５との間の曲げ稜線部１４の稜線長さ、及び、縦壁部１５とフランジ部１７との間の曲げ稜線部１６の稜線長さはそれぞれ、目標形状のプレス成形品１の天板部３と縦壁部５との間の曲げ稜線部４の稜線長さ、及び、縦壁部５とフランジ部７との間の曲げ稜線部６の稜線長さに等しいものと考えられる。 The intermediate-shaped press-molded product 11 determined by any of the above methods (a) to (c) is compressed from both ends in the longitudinal direction of the target-shaped press-molded product 1 toward the center as described above. , The convex curved portion 19 is curved more than the target shape. Therefore, in the intermediate-shaped press-formed product 11, the ridgeline length of the bent ridgeline portion 14 between the top plate portion 13 and the vertical wall portion 15 and the bent ridgeline portion between the vertical wall portion 15 and the flange portion 17 The ridge line lengths of 16 are the ridge line length of the bent ridge line portion 4 between the top plate portion 3 and the vertical wall portion 5 of the press-formed product 1 having the target shape, and the vertical wall portion 5 and the flange portion 7, respectively. It is considered to be equal to the ridge line length of the bent ridge line portion 6 between them.
すなわち、中間形状のプレス成形品１１は、目標形状の曲げ稜線部４及び曲げ稜線部６それぞれの稜線長さを維持したまま、長手方向の両端から中央に向かって圧縮させて凸状湾曲部位１９を目標形状よりも大きく湾曲させた形状である。 That is, the intermediate-shaped press-molded product 11 is compressed from both ends in the longitudinal direction toward the center while maintaining the ridge line lengths of the bent ridge line portion 4 and the bent ridge line portion 6 of the target shape, and the convex curved portion 19 Is a shape that is curved larger than the target shape.
＜しわを抑制することができる理由＞
本実施の形態に係るプレス成形方法により、側面視で長手方向に沿って高さ方向に凸状に湾曲するプレス成形品を、しわを抑制してプレス成形することができる理由について説明する（図１参照）。
<Reason why wrinkles can be suppressed>
The reason why a press-molded product that is convexly curved in the height direction along the longitudinal direction in a side view can be press-molded while suppressing wrinkles by the press molding method according to the present embodiment will be described (FIG. 1).
前述のとおり、中間形状成形工程においてプレス成形する中間形状のプレス成形品１１は、目標形状のプレス成形品１に比べて、天板部１３と縦壁部１５との開き角度が大きくて縦壁部１５の縦壁高さが低いものである。１工程で目標形状のプレス成形品１をプレス成形する場合に比べて、中間形状成形工程においては縦壁部１５からフランジ部１７への縦壁高さの変化が緩やかになるため、材料の変形は広く分散し、かつ、金型で材料流れを抑えることが容易となる。 As described above, the intermediate shape press-molded product 11 press-molded in the intermediate shape molding step has a larger opening angle between the top plate portion 13 and the vertical wall portion 15 than the target shape press-molded product 1, and has a vertical wall. The height of the vertical wall of the portion 15 is low. Compared to the case where the press-molded product 1 having the target shape is press-molded in one step, the change in the vertical wall height from the vertical wall portion 15 to the flange portion 17 becomes slower in the intermediate shape forming process, so that the material is deformed. Is widely dispersed, and it is easy to suppress the material flow with a mold.
そして、続く目標形状成形工程は、中間形状のプレス成形品１１における天板部１３と縦壁部１５との間の曲げ稜線部１４と、縦壁部１５とフランジ部１７との間の曲げ稜線部１６を曲げ成形するものである。そのため、目標形状成形工程においては、縦壁部５からフランジ部７への材料流れを抑制して目標形状のプレス成形品１が成形される。その結果、フランジ部７におけるしわを抑制することができる。 Then, in the subsequent target shape forming step, the bending ridge line portion 14 between the top plate portion 13 and the vertical wall portion 15 and the bending ridge line portion between the vertical wall portion 15 and the flange portion 17 in the intermediate shape press-molded product 11 are performed. The portion 16 is bent and molded. Therefore, in the target shape forming step, the press-molded product 1 having the target shape is formed by suppressing the material flow from the vertical wall portion 5 to the flange portion 7. As a result, wrinkles in the flange portion 7 can be suppressed.
さらに、本実施の形態に係るプレス成形方法は、前述の特許文献２に開示されている技術のように、ブランク材の幅方向の端部にビードや折曲部を形成するものではない、そのため、本実施の形態に係るプレス成形方法によれば、このようなビードや折曲部が十分に押し潰されずに平坦にならないおそれがなく、フランジ部を平坦な形状に成形することができる。 Further, the press molding method according to the present embodiment does not form a bead or a bent portion at the end portion in the width direction of the blank material as in the technique disclosed in Patent Document 2 described above. Therefore, According to the press molding method according to the present embodiment, there is no possibility that such beads and bent portions are not sufficiently crushed and become flat, and the flange portion can be molded into a flat shape.
また、本実施の形態に係るプレス成形方法は、中間形状のプレス成形品１１をフォーム成形により曲げ成形のみで目標形状に成形するものである。そのため、前述の特許文献３に開示されている絞り成形による技術で問題とされていたスプリングバックによる縦壁部５の壁反りは、本実施の形態に係るプレス成形方法では防ぐことができる。 Further, in the press molding method according to the present embodiment, the press-molded product 11 having an intermediate shape is formed into a target shape only by bending molding by foam molding. Therefore, the wall warpage of the vertical wall portion 5 due to the springback, which has been a problem in the drawing molding technique disclosed in Patent Document 3 described above, can be prevented by the press molding method according to the present embodiment.
なお、公知文献（ＷＯ２０１７／０１０４７０号公報）には、前工程においてプレス成形部品形状（本発明の中間形状に相当）にプレス成形し、該前工程のプレス成形部品形状を最終部品形状（本発明の目標形状に相当）にプレス成形する技術が開示されている。当該技術における前工程のプレス成形部品形状は、プレス成形部品の最終部品形状を展開する途中で得られる展開途中形状から設定した形状であるとされている。しかしながら、目標形状のフランジ部を部品外側方向に開く途中で得られる展開途中形状から前工程のプレス成形品形状を設定するものであり、長手方向長さについては何ら規定されていない。 In addition, in the publicly known document (WO2017 / 01470), the press-molded part shape (corresponding to the intermediate shape of the present invention) is press-molded in the pre-process, and the press-molded part shape in the pre-process is the final part shape (the present invention). A technique for press molding (corresponding to the target shape of) is disclosed. The shape of the press-molded part in the previous process in the technique is said to be a shape set from the shape in the middle of development obtained during the development of the final part shape of the press-molded part. However, the shape of the press-molded product in the previous process is set from the shape in the middle of unfolding obtained while the flange portion of the target shape is opened in the outward direction of the part, and the length in the longitudinal direction is not specified at all.
さらに、本実施の形態に係るプレス成形方法は、上述のとおり、長手方向に荷重又は変位を与えて成形解析を行うことにより中間形状を決定するものである。そして、このように決定された中間形状のプレス成形品は、長手方向の中央に比べて端部側の方がより開いた形状である。これにより、しわをさらに抑制できると考えられる。しかしながら、上記の参考文献に記載されている発明においては、長手方向における開きの度合いの違いについては何ら開示も示唆もされていない。 Further, in the press molding method according to the present embodiment, as described above, the intermediate shape is determined by applying a load or displacement in the longitudinal direction and performing molding analysis. The intermediate-shaped press-molded product thus determined has a shape that is more open on the end side than in the center in the longitudinal direction. It is considered that this makes it possible to further suppress wrinkles. However, in the inventions described in the above references, no disclosure or suggestion is made regarding the difference in the degree of opening in the longitudinal direction.
＜対象とするプレス成形品の目標形状＞
なお、本発明において成形対象とするプレス成形品の目標形状は、凸状湾曲部位の曲率半径Rが30mm以上5000mm以下であり、縦壁部の縦壁高さHが10mm以上300mm以下のものであることが好ましい。
<Target shape of the target press-molded product>
The target shape of the press-molded product to be molded in the present invention is that the radius of curvature R of the convex curved portion is 30 mm or more and 5000 mm or less, and the vertical wall height H of the vertical wall portion is 10 mm or more and 300 mm or less. It is preferable to have.
曲率半径Rが30mm未満、又は、縦壁高さHが300mmより大きいと、高強度鋼板を用いてプレス成形したときにフランジ部におけるしわや天板部における割れが顕著になり、プレス成形が困難になる場合がある。
また、曲率半径Rが5000mmより大きい、又は、縦壁高さHが10mm未満であると、本発明を用いなくても、しわを抑制して目標形状にプレス成形することできる。
If the radius of curvature R is less than 30 mm or the vertical wall height H is larger than 300 mm, wrinkles at the flange and cracks at the top plate become noticeable when press-molding using a high-strength steel plate, making press-forming difficult. May become.
Further, when the radius of curvature R is larger than 5000 mm or the vertical wall height H is less than 10 mm, wrinkles can be suppressed and press molding can be performed to a target shape without using the present invention.
したがって、本発明に係るプレス成形方法は、湾曲の曲率半径Rと縦壁高さHとの比R／Hが0.1以上500以下である目標形状のプレス成形品に対して好適に適用することができる。湾曲の曲率半径Rと縦壁高さHとの比R／Hの好適範囲については、後述する実施例において実証する。 Therefore, the press molding method according to the present invention can be suitably applied to a press molding product having a target shape in which the ratio R / H of the radius of curvature R of the curve to the height H of the vertical wall is 0.1 or more and 500 or less. it can. The preferable range of the ratio R / H of the radius of curvature R of the curve to the height H of the vertical wall will be demonstrated in Examples described later.
なお、上記の説明においては、側面視で高さ方向に凸状に湾曲した凸状湾曲部位９のみを有するプレス成形品１について説明した。もっとも、本発明はこのようなプレス成形品１のみを対象とするものではなく、図２に示すように、天板部２３と縦壁部２５とフランジ部２７とを有する断面ハット形状であり、長手方向に沿って高さ方向に凸状に湾曲する凸状湾曲部位２９と、長手方向に沿って高さ方向に凹状に湾曲する凹状湾曲部位３１とを有するプレス成形品２１や、凸状湾曲部位の長手方向の端部から外方に直線状に延出する直線部位を有するプレス成形品（図示なし）であってもよい。
なお、長手方向に沿って高さ方向に凹状に湾曲するとは、側面視において凹状に湾曲した円弧の中心が天板部３側に位置することをいう。
In the above description, the press-molded product 1 having only the convex curved portion 9 curved in the height direction in the side view has been described. However, the present invention is not intended only for such a press-molded product 1, but has a cross-sectional hat shape having a top plate portion 23, a vertical wall portion 25, and a flange portion 27, as shown in FIG. A press-molded product 21 having a convex curved portion 29 that curves convexly in the height direction along the longitudinal direction and a concave curved portion 31 that curves concavely in the height direction along the longitudinal direction, and convex curvature. It may be a press-molded product (not shown) having a straight portion extending linearly outward from the end portion in the longitudinal direction of the portion.
The fact that the arc is concavely curved in the height direction along the longitudinal direction means that the center of the concavely curved arc is located on the top plate portion 3 side in the side view.
そして、図２に示すような凸状湾曲部位２９と凹状湾曲部位３１を有するプレス成形品や、凸状湾曲部位と直線部位を有するプレス成形品の場合、長手方向の端面から中央に向かって圧縮されて長手方向長さを短くする場合、中間形状成形工程における中間形状は、中間形状の凸状湾曲部位の長手方向長さと目標形状の凸状湾曲部位の長手方向長さとの差が10%以上であることが好ましい。 Then, in the case of a press-molded product having a convex curved portion 29 and a concave curved portion 31 as shown in FIG. 2 or a press-molded product having a convex curved portion and a straight portion, compression is performed from the end face in the longitudinal direction toward the center. When the longitudinal length is shortened, the difference between the longitudinal length of the convex curved portion of the intermediate shape and the longitudinal length of the convex curved portion of the target shape is 10% or more in the intermediate shape in the intermediate shape forming process. Is preferable.
なお、凸状湾曲部位の長手方向長さは、該凸状湾曲部位の長手方向における両端間の距離とすればよい。そして、凸状湾曲部位の長手方向の端部に凹状湾曲部位や直線部位が接続している場合、凸状湾曲部位の長手方向の端は、該凸状湾曲部位と凹状湾曲部位又は直線部位との湾曲の変曲点の位置とすればよい。 The length of the convex curved portion in the longitudinal direction may be the distance between both ends of the convex curved portion in the longitudinal direction. When a concave curved portion or a straight portion is connected to the longitudinal end of the convex curved portion, the longitudinal end of the convex curved portion is the convex curved portion and the concave curved portion or the straight portion. It may be the position of the inflection point of the curve of.
また、図１に示すプレス成形品１における凸状湾曲部位９は天板部３とフランジ部７の双方が側面視で高さ方向に凸状に湾曲するものであり、また、図２に示すプレス成形品２１における凸状湾曲部位２９も同様に天板部２３とフランジ部２７の双方が側面視で高さ方向に凸状に湾曲するものであった。
もっとも、本発明は、天板部又はフランジ部のいずれか一方が、長手方向に沿って高さ方向に凸状に湾曲するプレス成形品を成形対象とするものであっても、しわを抑制してプレス成形することができる。
Further, in the convex curved portion 9 of the press-molded product 1 shown in FIG. 1, both the top plate portion 3 and the flange portion 7 are curved in a height direction in a side view, and are also shown in FIG. Similarly, in the convex curved portion 29 of the press-molded product 21, both the top plate portion 23 and the flange portion 27 are curved convexly in the height direction in the side view.
However, the present invention suppresses wrinkles even if one of the top plate portion and the flange portion is a press-molded product that is curved in a height direction along the longitudinal direction. Can be press molded.
本発明に係るプレス成形方法の作用効果について検証するため、具体的な実験を行ったので、以下に説明する。 In order to verify the action and effect of the press molding method according to the present invention, a specific experiment was conducted, which will be described below.
実験は、図３に示すように、長手方向に沿って高さ方向に凸状に湾曲する凸状湾曲部位９を有するプレス成形品１を目標形状とする場合（実施例１）と、図５に示すように、長手方向に沿って高さ方向に凸状に湾曲する凸状湾曲部位２９と高さ方向に凹状に湾曲する凹状湾曲部位３１とが連続するプレス成形品２１を目標形状とする場合（実施例２）のそれぞれについて行った。
なお、実施例１及び実施例２において、プレス成形に供した材料として、以下の表１に示す材料Ａ又はＤの鋼板を用いた。
In the experiment, as shown in FIG. 3, when the press-molded product 1 having the convex curved portion 9 curved in the height direction along the longitudinal direction is set as the target shape (Example 1), FIG. 5 As shown in the above, the target shape is a press-molded product 21 in which a convex curved portion 29 that curves convexly in the height direction along the longitudinal direction and a concave curved portion 31 that curves concavely in the height direction are continuous. This was done for each of the cases (Example 2).
In Examples 1 and 2, the steel sheets of the materials A or D shown in Table 1 below were used as the materials used for press molding.
＜実施例１＞
図３に示すように、天板部３と縦壁部５とフランジ部７とを有する断面ハット形状であり、側面視で天板部３とフランジ部７の双方が長手方向に沿って高さ方向に凸状に湾曲する凸状湾曲部位９を有するプレス成形品１を成形対象とした。
<Example 1>
As shown in FIG. 3, it has a cross-sectional hat shape having a top plate portion 3, a vertical wall portion 5, and a flange portion 7, and both the top plate portion 3 and the flange portion 7 have heights along the longitudinal direction in a side view. The press-molded product 1 having the convex curved portion 9 that curves convexly in the direction was set as the molding target.
プレス成形品１の寸法は、図４に断面形状を示すように、長手方向長さを500mm、天板部３と縦壁部５の開き角度を長手方向の全長にわたって110°一定とした。さらに、凸状湾曲部位９のフランジ部７側における湾曲の曲率半径Rを30〜5000mm、縦壁部５の縦壁高さHを10〜300mmの範囲で変更した。 As shown in the cross-sectional shape of the press-molded product 1, the length in the longitudinal direction was set to 500 mm, and the opening angle between the top plate portion 3 and the vertical wall portion 5 was set to be constant at 110 ° over the entire length in the longitudinal direction. Further, the radius of curvature R of the curvature of the convex curved portion 9 on the flange portion 7 side was changed in the range of 30 to 5000 mm, and the vertical wall height H of the vertical wall portion 5 was changed in the range of 10 to 300 mm.
実施例１においては、目標形状のプレス成形品１に比べて、凸状湾曲部位１９における天板部１３と縦壁部１５との開き角度が大きくて縦壁部１５の縦壁高さが低い中間形状のプレス成形品１１（図１（ｂ）参照）をプレス成形し、次いで中間形状のプレス成形品１１を目標形状にフォーム成形したものを発明例とした。そして、目標形状のプレス成形品１の長手方向長さL0に対する中間形状のプレス成形品１１の長手方向長さLの変化割合（＝(L0−L)／L0）を5%〜20%とした。実施例１では、目標形状のプレス成形品１の長手方向の両端面に中央に向かう荷重を与える成形解析により中間形状を定めた。 In the first embodiment, the opening angle between the top plate portion 13 and the vertical wall portion 15 at the convex curved portion 19 is larger and the vertical wall height of the vertical wall portion 15 is lower than that of the press-molded product 1 having the target shape. An example of the invention was a press-molded product 11 having an intermediate shape (see FIG. 1B), which was press-molded, and then a press-molded product 11 having an intermediate shape was form-molded into a target shape. Then, the rate of change (= (L 0 − L) / L 0 ) of the length L in the longitudinal direction of the press-molded product 11 having the intermediate shape with respect to the length L 0 in the longitudinal direction of the press-molded product 1 having the target shape is 5% to 20. %. In Example 1, the intermediate shape was determined by molding analysis in which a load toward the center was applied to both end faces in the longitudinal direction of the press-molded product 1 having the target shape.
なお、実施例１において、中間形状成形工程でのプレス工法はドロー成形とし、目標形状成形工程でのプレス工法はフォーム成形とした。 In Example 1, the press method in the intermediate shape forming step was draw molding, and the press method in the target shape forming step was foam molding.
そして、目標形状にプレス成形したプレス成形品におけるしわの有無を評価した。
ここで、しわが無い場合は「○」、微小なしわがある場合は「△」、明らかなしわがある場合は「×」と評価した。
Then, the presence or absence of wrinkles in the press-molded product press-molded to the target shape was evaluated.
Here, when there was no wrinkle, it was evaluated as "○", when there was a minute wrinkle, it was evaluated as "Δ", and when there was an obvious wrinkle, it was evaluated as "×".
さらに、比較対象として、１工程で目標形状のプレス成形品にプレス成形したものを従来例とし、発明例と同様にしわを評価した。
表２に、中間形状のプレス成形品の押し込み割合（長手方向長さの変化割合）、目標形状の凸状湾曲部位９の湾曲の曲率半径Rと縦壁部の縦壁高さHの比R／H、及びしわの評価結果を示す。
Further, as a comparison target, a press-molded product having a target shape in one step was used as a conventional example, and wrinkles were evaluated in the same manner as in the invention example.
Table 2 shows the pushing ratio (change rate of length in the longitudinal direction) of the press-formed product of the intermediate shape, the ratio R of the radius of curvature R of the curvature of the convex curved portion 9 of the target shape to the vertical wall height H of the vertical wall portion. The evaluation results of / H and wrinkles are shown.
表２より、従来例１においては明らかなしわが見られたのに対し、発明例１〜４においてはしわを抑制してプレス成形できることが示された。
さらに、目標形状の凸状湾曲部位９の湾曲の曲率半径Rと縦壁部５の縦壁高さHの比R／Hが好適範囲である0.1以上500以下の場合においては、しわの発生が一切見られず、良好な結果であった。なお、発明例４では、発明例３の中間形状のプレス成形品に対して長手方向の端部を逆解析によりさらに平坦とした中間形状を用いた。
From Table 2, it was shown that wrinkles were clearly observed in Conventional Example 1, whereas in Invention Examples 1 to 4, wrinkles could be suppressed and press molding was possible.
Further, when the ratio R / H of the radius of curvature R of the curvature of the convex curved portion 9 of the target shape and the vertical wall height H of the vertical wall portion 5 is 0.1 or more and 500 or less, which is a preferable range, wrinkles occur. Nothing was seen, and the result was good. In Invention Example 4, an intermediate shape was used in which the end portion in the longitudinal direction was further flattened by reverse analysis with respect to the press-molded product having the intermediate shape of Invention Example 3.
＜実施例２＞
図５に示すように、天板部２３と縦壁部２５とフランジ部２７とを有する断面ハット形状であり、側面視で天板部２３とフランジ部２７の双方が長手方向に沿って高さ方向に凸状に湾曲する凸状湾曲部位２９と、長手方向に沿って高さ方向に凹状に湾曲する凹状湾曲部位３１を有するプレス成形品２１を成形対象とした。
<Example 2>
As shown in FIG. 5, it has a cross-sectional hat shape having a top plate portion 23, a vertical wall portion 25, and a flange portion 27, and both the top plate portion 23 and the flange portion 27 have heights along the longitudinal direction in a side view. A press-molded product 21 having a convex curved portion 29 that curves convexly in the direction and a concave curved portion 31 that curves concavely in the height direction along the longitudinal direction was targeted for molding.
プレス成形品２１の寸法は、長手方向長さを800mm、凸状湾曲部位２９の長手方向長さを400mm、天板部２３と縦壁部２５の開き角度を長手方向の全長にわたって110°一定とした。さらに、凸状湾曲部位２９のフランジ部２７側における湾曲の曲率半径R1を30〜5000mm、縦壁部２５の縦壁高さHを10〜300mmの範囲で変更した。また、凹状湾曲部位３１の湾曲の曲率半径R2は、凸状湾曲部位２９の湾曲の曲率半径R1と等しいものとした。 The dimensions of the press-molded product 21 are such that the length in the longitudinal direction is 800 mm, the length in the longitudinal direction of the convex curved portion 29 is 400 mm, and the opening angle between the top plate portion 23 and the vertical wall portion 25 is constant at 110 ° over the entire length in the longitudinal direction. did. Furthermore, changing the radius of curvature R 1 of curvature in the flange portion 27 side of the convexly curved portions 29 30～5000Mm, the vertical wall height H of the vertical wall portion 25 in the range of 10 to 300 mm. Further, the radius of curvature R 2 of the curvature of the concave curved portion 31 is assumed to be equal to the radius of curvature R 1 of the curvature of the convex curved portion 29.
実施例２においては、目標形状のプレス成形品２１に比べて、凸状湾曲部位２９における天板部２３と縦壁部２５との開き角度が大きくて縦壁部２５の縦壁高さが低い中間形状のプレス成形品４１（図２（ｂ）参照）をプレス成形し、次いで中間形状のプレス成形品４１を目標形状にフォーム成形したものを発明例とした。そして、目標形状のプレス成形品２１の凸状湾曲部位における長手方向長さL0に対する中間形状のプレス成形品４１の凸状湾曲部位における長手方向長さLの変化割合（＝(L0−L)／L0）を5%又は10%とした。実施例２では、目標形状のプレス成形品２１の長手方向両端面に中央に向かう変位を与える成形解析により中間形状を定めた。 In the second embodiment, the opening angle between the top plate portion 23 and the vertical wall portion 25 at the convex curved portion 29 is larger and the vertical wall height of the vertical wall portion 25 is lower than that of the press-molded product 21 having the target shape. An example of the invention was a press-molded product 41 having an intermediate shape (see FIG. 2B), which was press-molded, and then a press-molded product 41 having an intermediate shape was foam-molded to a target shape. Then, the rate of change of the longitudinal length L of the intermediate-shaped press-molded product 41 at the convex curved portion of the target-shaped press-molded product 21 with respect to the longitudinal length L 0 of the convex curved portion (= (L 0 −L). ) / L 0 ) was set to 5% or 10%. In Example 2, the intermediate shape was determined by molding analysis in which the end faces of the press-molded product 21 having the target shape were displaced toward the center in the longitudinal direction.
なお、本実施例において、中間形状成形工程でのプレス工法はドロー成形とし、目標形状成形工程でのプレス工法はフォーム成形とした。 In this embodiment, the press method in the intermediate shape forming step was draw molding, and the press method in the target shape forming step was foam molding.
そして、目標形状にプレス成形したプレス成形品におけるしわの有無を評価した。
ここで、しわが無い場合は「○」、微小なしわがある場合は「△」、明らかなしわがある場合は「×」と評価した。
Then, the presence or absence of wrinkles in the press-molded product press-molded to the target shape was evaluated.
Here, when there was no wrinkle, it was evaluated as "○", when there was a minute wrinkle, it was evaluated as "Δ", and when there was an obvious wrinkle, it was evaluated as "×".
さらに、比較対象として、１工程で目標形状のプレス成形品にプレス成形したものを従来例とし、発明例と同様にしわを評価した。
表３に、中間形状のプレス成形品４１の凸状湾曲部位における長手方向長さの変化割合、目標形状の凸状湾曲部位２９の湾曲の曲率半径R1と縦壁部２５の縦壁高さHの比R1／H、及びしわの評価結果を示す。
Further, as a comparison target, a press-molded product having a target shape in one step was used as a conventional example, and wrinkles were evaluated in the same manner as in the invention example.
Table 3, vertical wall height of the longitudinal length change ratio of the curvature of the curvature of the convex curvature portion 29 of target shape radius R 1 and the vertical wall portion 25 in the convex curved portion of the press-molded product 41 of the intermediate shape The evaluation results of H ratio R 1 / H and wrinkles are shown.
表３より、従来例２、３においては明らかなしわが見られたのに対し、発明例５〜９においてはしわを抑制してプレス成形できることが示された。
さらに、目標形状の凸状湾曲部位２９の湾曲の曲率半径R1と縦壁部５の縦壁高さHの比R1／Hが好適範囲である0.1以上500以下の場合、しわの発生が一切見られず、良好な結果であった。
From Table 3, it was shown that wrinkles were clearly observed in Conventional Examples 2 and 3, whereas wrinkles could be suppressed and press molding could be performed in Invention Examples 5-9.
Further, when the ratio R 1 / H of the radius of curvature R 1 of the curvature of the convex curved portion 29 of the target shape and the vertical wall height H of the vertical wall portion 5 is 0.1 or more and 500 or less, which is a preferable range, wrinkles occur. Nothing was seen, and the result was good.
１ 目標形状のプレス成形品
３ 天板部
５ 縦壁部
７ フランジ部
９ 凸状湾曲部位
１１ 中間形状のプレス成形品
１３ 天板部
１５ 縦壁部
１７ フランジ部
１９ 凸状湾曲部位
２１ 目標形状のプレス成形品
２３ 天板部
２５ 縦壁部
２７ フランジ部
２９ 凸状湾曲部位
３１ 凹状湾曲部位
４１ 目標形状のプレス成形品
４３ 天板部
４５ 縦壁部
４７ フランジ部
４９ 凸状湾曲部位
５１ 凹状湾曲部位
1 Target-shaped press-molded product 3 Top plate part 5 Vertical wall part 7 Flange part 9 Convex curved part 11 Intermediate-shaped press-molded product 13 Top plate part 15 Vertical wall part 17 Flange part 19 Convex curved part 21 Target shape Press-molded product 23 Top plate part 25 Vertical wall part 27 Flange part 29 Convex curved part 31 Concave curved part 41 Press-molded product of target shape 43 Top plate part 45 Vertical wall part 47 Flange part 49 Convex curved part 51 Concave curved part
Claims (4)
前記プレス成形品の目標形状に比べて、長手方向長さが短くて前記凸状湾曲部位が前記目標形状よりも大きく湾曲し、かつ該凸状湾曲部位における前記天板部と前記縦壁部との開き角度が大きくて前記縦壁部の縦壁高さが低い中間形状のプレス成形品をプレス成形する中間形状成形工程と、
該中間形状のプレス成形品をフォーム成形により目標形状にプレス成形する目標形状成形工程と、を備えたことを特徴とするプレス成形方法。 It has a cross-sectional hat shape having a top plate portion, a vertical wall portion continuous from the top plate portion, and a flange portion continuous from the vertical wall portion, and the top plate portion and / or the flange portion is longitudinal in a side view. A press-molding method for press-molding a press-molded product having a convexly curved portion that is convexly curved in the height direction along a direction.
The length in the longitudinal direction is shorter than the target shape of the press-molded product, the convex curved portion is curved more than the target shape, and the top plate portion and the vertical wall portion in the convex curved portion An intermediate shape forming step of press molding an intermediate shape press-molded product having a large opening angle and a low vertical wall height of the vertical wall portion.
A press molding method comprising a target shape molding step of press molding the intermediate shape press-molded product into a target shape by foam molding.
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