JPH11319971A - Method for predicting occurrence of wrinkle in pressing - Google Patents
Method for predicting occurrence of wrinkle in pressingInfo
- Publication number
- JPH11319971A JPH11319971A JP10127500A JP12750098A JPH11319971A JP H11319971 A JPH11319971 A JP H11319971A JP 10127500 A JP10127500 A JP 10127500A JP 12750098 A JP12750098 A JP 12750098A JP H11319971 A JPH11319971 A JP H11319971A
- Authority
- JP
- Japan
- Prior art keywords
- wrinkle
- wrinkles
- press
- occurrence
- stress
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
Landscapes
- Shaping Metal By Deep-Drawing, Or The Like (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】この発明は、プレス成形にお
ける皺の発生の予測方法に関するものである。The present invention relates to a method for predicting the occurrence of wrinkles in press molding.
【０００２】[0002]
【従来の技術】プレス成形における皺の発生を予測する
方法としては、弾塑性有限要素法に基づくプレス成形シ
ミュレーションによる方法が従来から知られており、従
来のこの方法では、コンピュータを用いて弾塑性有限要
素法に基づく演算処理を実行することで板状素材のプレ
ス成形シミュレーションを行って、そのコンピュータの
画面上に表示された成形途中や成形終了時の素材形状を
目視で観察することにより、皺発生の有無を判断してい
る。2. Description of the Related Art As a method for predicting the occurrence of wrinkles in press forming, a method based on a press forming simulation based on an elasto-plastic finite element method has been conventionally known. By performing an arithmetic process based on the finite element method, a press forming simulation of a plate-shaped material is performed, and by visually observing the material shape during the forming or at the end of the forming displayed on the screen of the computer, wrinkles are obtained. The presence or absence of occurrence has been determined.
【０００３】[0003]
【発明が解決しようとする課題】しかしながら、かかる
従来の方法では、皺発生の有無を定量的にでなく、画面
上に表示された素材の立体形状を目視して定性的に判断
しているため、コンピュータ上の陰影処理の相違や判断
する人の熟練度等によって皺発生の判断結果が異なる場
合があり、それゆえ、設計段階では皺の発生がないと判
断されたプレス金型について製作段階で修正作業が必要
となってその金型で加工するプレス製品の開発期間が延
びてしまう場合があるという不都合があった。However, in such a conventional method, the presence or absence of wrinkles is determined not only quantitatively but also qualitatively by visually checking the three-dimensional shape of the material displayed on the screen. However, the judgment result of wrinkle generation may be different depending on a difference in shading processing on a computer or the skill of a person who judges, and therefore, in a design stage, a press die determined to have no wrinkle in a production stage. There is a disadvantage that a repair work is required and the development period of a press product processed by the mold may be extended.
【０００４】ところで、本願発明者は、プレス成形にお
ける皺発生について研究を進めた結果、以下の知見を得
た。すなわち、プレス成形における皺は、基本的には引
っ張り成形である絞り成形において圧縮応力が発生する
領域で発生し、かかる圧縮応力発生領域で応力の増大に
対して素材の伸び歪量に変化がなくなると、そこに座屈
ひいては皺が発生していると考えられる。従って、弾塑
性有限要素法に基づくプレス成形シミュレーションでの
解析結果から求まる素材の各要素の伸び歪量に対してそ
の素材の加工硬化曲線から得られる各要素の相当応力
と、これも上記解析結果から求まる各要素とその周囲の
要素との力の釣合いから得られる各要素の相当応力との
差が大きい場合には、その要素の位置に座屈が発生して
いると考えられる。By the way, the inventor of the present application has conducted research on the occurrence of wrinkles in press molding, and has obtained the following knowledge. In other words, wrinkles in press forming are basically generated in a region where compressive stress is generated in draw forming which is tensile forming, and in the compressive stress generating region, there is no change in the amount of elongation strain of the material with respect to an increase in stress. It is considered that buckling and wrinkles are occurring there. Therefore, the equivalent stress of each element obtained from the work hardening curve of the material with respect to the elongation strain of each element of the material obtained from the analysis result of the press forming simulation based on the elasto-plastic finite element method, and this is also the above analysis result If there is a large difference between the equivalent stress of each element obtained from the balance between the force of each element obtained from and the surrounding elements, it is considered that buckling has occurred at the position of the element.
【０００５】[0005]
【課題を解決するための手段およびその作用・効果】こ
の発明は、上述の点に鑑みて前記課題を有利に解決した
皺発生予測方法を提供することを目的とするものであ
り、この発明のプレス成形における皺発生予測方法は、
コンピュータを用いて弾塑性有限要素法に基づく板状素
材のプレス成形シミュレーションを行い、その結果に基
づいて皺の発生を予測するに際し、前記プレス成形シミ
ュレーションでの前記素材のプレス成形過程における単
位時間毎の各要素の相当応力および相当歪を出力し、前
記出力した相当歪に対し前記素材の加工硬化曲線から得
られる相当応力と、前記出力した相当応力との差を皺評
価パラメータとして求め、前記皺評価パラメータの値に
基づいて皺発生の有無を判断することを特徴としてい
る。SUMMARY OF THE INVENTION An object of the present invention is to provide a method for predicting wrinkle occurrence which advantageously solves the above-mentioned problems in view of the above points. The method for predicting wrinkles in press molding is as follows.
A press-forming simulation of a plate-shaped material based on an elasto-plastic finite element method is performed by using a computer, and when predicting the occurrence of wrinkles based on the result, each unit time in the press-forming process of the material in the press-forming simulation is performed. The equivalent stress and the equivalent strain of each element are output, and the difference between the equivalent stress obtained from the work hardening curve of the material with respect to the outputted equivalent strain and the outputted equivalent stress is obtained as a wrinkle evaluation parameter, It is characterized in that the presence or absence of wrinkles is determined based on the value of the evaluation parameter.
【０００６】弾塑性有限要素法によるプレス成形シミュ
レーションでの素材のプレス成形過程における単位時間
毎の各要素の相当歪に対しその素材の加工硬化曲線から
得られる相当応力と、そのプレス成形シミュレーション
での素材のプレス成形過程における単位時間毎の各要素
の相当応力との差が大きい場合には、その要素の位置に
座屈が発生していると考えられることから、この発明の
方法では、その差を皺評価パラメータとして求めて、そ
の皺評価パラメータの値に基づいて皺発生の有無を判断
するので、この発明の方法によれば、皺発生の有無を定
量的に判断することができるとともに、その発生場所を
明確に特定することができ、従って、設計段階では皺の
発生がないと判断されたプレス金型について製作段階で
修正作業が必要となってその金型で加工するプレス製品
の開発期間が延びてしまうという不都合を確実に防止す
ることができる。The equivalent stress obtained from the work hardening curve of the material for the equivalent strain of each element per unit time in the press forming process of the material in the press forming simulation by the elasto-plastic finite element method, and If the difference from the equivalent stress of each element per unit time in the press forming process of the material is large, it is considered that buckling has occurred at the position of the element. Is determined as a wrinkle evaluation parameter, and the presence or absence of wrinkle occurrence is determined based on the value of the wrinkle evaluation parameter. Therefore, according to the method of the present invention, the presence or absence of wrinkle occurrence can be quantitatively determined, and The location of the occurrence can be clearly specified, and therefore, it is necessary to correct the press mold that has been determined to have no wrinkles at the design stage at the manufacturing stage. The disadvantage that the development period of the press products will extend to processing in the mold I can be reliably prevented.
【０００７】なお、この発明においては、前記プレス成
形シミュレーションでの成形途中および成形終了時の前
記素材の各部の皺発生パラメータ値の大きさの相違を表
示色の相違として前記コンピュータで画面表示すること
としても良く、このようにすれば、成形中の素材や成形
後のプレス製品における皺発生位置を容易に目視確認す
ることができる。In the present invention, the difference in the magnitude of the wrinkle generation parameter value of each part of the material during the molding in the press molding simulation and at the end of the molding is displayed on the screen as a difference in display color by the computer. In this way, the position where wrinkles occur in the material being molded or the pressed product after molding can be easily confirmed visually.
【０００８】[0008]
【発明の実施の形態】以下に、この発明の実施の形態を
実施例によって、図面に基づき詳細に説明する。先ず、
この発明のプレス成形における皺発生予測方法で用いる
皺評価パラメータの基本的な考え方を説明するために降
伏曲面について簡単に説明すると、降伏曲面は、３次元
主応力空間での降伏条件である以下の式を満たす曲面
として定義される。ここに、J2, J3は各々、偏差応力の
２次、３次の不変量である。Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. First,
In order to explain the basic concept of wrinkle evaluation parameters used in the method for predicting wrinkles in press forming according to the present invention, the yield surface will be briefly described. The yield surface is the following yield condition in a three-dimensional principal stress space. It is defined as a surface that satisfies the equation. Here, J2 and J3 are second and third order invariants of the deviation stress, respectively.
【０００９】[0009]
【数１】ｆ(J2, J3)＝０ ・・・[Equation 1] f (J2, J3) = 0 ...
【００１０】現在、降伏条件としては主にフォン・ミー
ゼス（von Mises)の降伏条件が採用されることが多く、
これは以下の式のように表される。ここに、式の左
辺はフォン・ミーゼスの降伏条件での相当応力と呼ば
れ、Ypは、一軸引っ張りでの降伏応力、σ1,σ2,σ3
は、主応力である。At present, the von Mises yield condition is often adopted as the yield condition.
This is represented by the following equation. Here, the left side of the equation is called equivalent stress under the von Mises yield condition, and Yp is the yield stress under uniaxial tension, σ1, σ2, σ3
Is the main stress.
【００１１】[0011]
【数２】 ｛ (σ1-σ2)2 ＋ (σ2-σ3)2 ＋ (σ3-σ1)2 ｝1/2 ／２1/2 ＝Yp ・・[Equation 2] ｛(σ1-σ2) 2 + (σ2-σ3) 2 + (σ3-σ1) 2 ｝ 1/2 / 1/2 = Yp ···
【００１２】平面応力状態では、von Mises の降伏条件
を満たす降伏曲面は図４に示すように楕円となり、歪硬
化材料では、等方硬化を仮定すると塑性変形による加工
硬化は加工硬化前降伏曲面Ａから加工硬化後降伏曲面Ｂ
への楕円の径の拡大Ｃとして表現される。In the plane stress state, the yield surface satisfying the von Mises yield condition becomes an ellipse as shown in FIG. 4, and in the case of the strain hardening material, assuming isotropic hardening, the work hardening due to plastic deformation becomes the yield surface A before work hardening. Yield surface B after work hardening
Is expressed as an enlargement C of the diameter of the ellipse.
【００１３】図５は、皺発生前後の応力状態の概念を示
しており、図示の平面応力状態で、最も基本的な皺発生
領域である第２象限（引っ張り応力σ2 ＋圧縮応力σ1
）での皺発生前後の降伏曲面の変化について考えてみ
ると、圧縮応力により座屈すなわち皺が発生すると圧縮
応力が解放され、その結果、降伏応力は図中実線で示す
降伏曲面Ｄから破線で示す降伏曲面Ｅに、矢印Ｆで示す
ように径が縮小し、上記式で示される相当応力が小さ
くなる。この一方、かかる変化を歪の面から考えると、
素材の形状は本来あるべき形状から外れることになる
が、各部の歪自体は大きくは変化しないと考えられる。FIG. 5 shows the concept of the stress state before and after the generation of wrinkles. In the illustrated plane stress state, the second quadrant (tensile stress σ 2 + compression stress σ 1), which is the most basic wrinkle generation area, is shown.
Considering the change of the yield surface before and after the occurrence of wrinkles in (1), when buckling, that is, wrinkles are generated by compressive stress, the compressive stress is released. The diameter of the yield surface E shown decreases as shown by the arrow F, and the equivalent stress shown by the above equation becomes smaller. On the other hand, considering these changes in terms of distortion,
Although the shape of the material will deviate from the original shape, it is considered that the distortion itself of each part does not significantly change.
【００１４】従って、座屈後の相当歪に対してその素材
の加工硬化曲線から得られる相当応力は、座屈前の状態
の式の相当応力すなわち図中の降伏曲面Ｄの応力とほ
ぼ等しいと考えられ、座屈後の状態の式の相当応力す
なわち図中の降伏曲面Ｅの応力との差は、皺の大きさに
対応すると考えられる。この考え方に従い、本願発明者
は、以下の式で表される皺評価パラメータを設定し
た。ここに、Pwは、皺評価パラメータ、σesは、弾塑性
有限要素法での解析結果からの伸び歪量に対して加工硬
化曲線から得られる相当応力、σe は、その解析結果か
ら得られる相当応力である。Accordingly, the equivalent stress obtained from the work hardening curve of the material with respect to the equivalent strain after buckling is substantially equal to the equivalent stress in the equation before buckling, that is, the stress on the yield surface D in the figure. It is considered that the difference between the equivalent stress in the equation after buckling, that is, the stress of the yielded curved surface E in the figure, corresponds to the size of the wrinkle. In accordance with this concept, the inventor of the present application has set a wrinkle evaluation parameter represented by the following equation. Here, Pw is the wrinkle evaluation parameter, σes is the equivalent stress obtained from the work hardening curve with respect to the amount of elongation strain from the analysis result by the elasto-plastic finite element method, and σe is the equivalent stress obtained from the analysis result. It is.
【００１５】[0015]
【数３】Pw＝σes−σe ・・・[Equation 3] Pw = σes−σe
【００１６】次に、後述するこの発明の実施例に用い
る、コンピュータを用いての弾塑性有限要素法に基づく
板状素材のプレス成形シミュレーションの皺形状計算精
度確認試験について説明すると、本願発明者は、上記プ
レス成形シミュレーションのために、幾つかの自動車メ
ーカーや大学等で使用されている通常の弾塑性有限要素
法に基づく弾塑性変形シミュレーションソフトウェアを
用いることとし、そのシミュレーションソフトウェア
で、最も基本的な皺発生モードである平板の一軸圧縮の
計算を行い、その計算結果を実験結果と比較した。Next, a description will be given of a wrinkle shape calculation accuracy confirmation test of a press forming simulation of a plate-like material based on an elastic-plastic finite element method using a computer, which is used in an embodiment of the present invention described later. For the press forming simulation, elasto-plastic deformation simulation software based on the normal elasto-plastic finite element method used by some automobile manufacturers and universities is used, and the most basic simulation software is used. The uniaxial compression of the flat plate, which is the wrinkle generation mode, was calculated, and the calculation result was compared with the experimental result.
【００１７】上記シミュレーションソフトウェアに設定
した条件は、図６に示す如き形状および寸法の平板一軸
圧縮計算用素材メッシュで、節点数３２４個、要素数３
８５個、材料定数ＮＰ１１４相当、板厚０．８mmとし、
ＮＰ１１４の材料特性値を、σ＝６６０．８３６×（ε
ｐ＋０．０１０６７)0.30345 (MPa)、Yp＝１６６．６(M
Pa) 、ｒ値（ランクフォード値）＝１．８８とした。The conditions set in the simulation software are a material mesh for a plate uniaxial compression calculation having a shape and dimensions as shown in FIG. 6, with 324 nodes and 3 elements.
85 pieces, material constant NP114 equivalent, plate thickness 0.8 mm,
The material characteristic value of NP114 is given by σ = 660.636 × (ε
p + 0.01067) 0.30345 (MPa), Yp = 166.6 (M
Pa) and r value (Rankford value) = 1.88.
【００１８】図７は、上記計算結果での平板の変形形状
を示し、また図８は、皺高さｈと材料移動量dxとの関係
の実験値（×印で示す）と計算値（○印で示す）との比
較結果を示す。図８の比較結果から、計算で求めた皺高
さが実験値と良く一致することが確認でき、上記シミュ
レーションソフトウェアの一軸平板圧縮での皺形状計算
精度は充分高いと判断した。FIG. 7 shows the deformed shape of the flat plate as a result of the above calculation, and FIG. 8 shows the experimental value (indicated by x) and the calculated value (（) of the relationship between the wrinkle height h and the material movement amount dx. (Indicated by a mark). From the comparison result of FIG. 8, it was confirmed that the calculated wrinkle height was in good agreement with the experimental value, and it was determined that the calculation accuracy of the wrinkle shape in the uniaxial flat plate compression of the simulation software was sufficiently high.
【００１９】しかして上記シミュレーションを行ったコ
ンピュータを用いて上記平板一軸圧縮の計算結果に式
の皺評価パラメータPwを適用したところ、図９〜図11に
示す結果が得られた。図９は、上記計算結果での平板の
一軸圧縮における皺評価パラメータPwの分布状態を４種
類皺高さｈについて示し、また図10は、上記計算結果で
の平板の一軸圧縮における皺高さｈに対する皺評価パラ
メータPwの最大値の関係を示し、そして図11は、上記計
算結果での平板の一軸圧縮における皺高さｈに対する塑
性状態の積分点数ｎの関係を示す。ここで、その塑性状
態の積分点数ｎについて説明すると、上記シミュレーシ
ョンソフトウェアでは、要素１個当たり８個（上記計算
では総計３０８０個）の積分点（歪の評価点）があり、
上記塑性状態の積分点数ｎは、変形の進行に伴って弾性
変形状態から塑性変形状態に移行した積分点の総数を示
している。When the wrinkle evaluation parameter Pw of the equation was applied to the calculation result of the above-described uniaxial compression of the flat plate using the computer that performed the above simulation, the results shown in FIGS. 9 to 11 were obtained. FIG. 9 shows the distribution state of the wrinkle evaluation parameter Pw in the uniaxial compression of the flat plate based on the above calculation results for four types of wrinkle heights h. FIG. 10 shows the wrinkle height h in the uniaxial compression of the flat plate obtained in the above calculation results. 11 shows the relationship between the wrinkle height h and the integral number n of the plastic state in the uniaxial compression of the flat plate based on the above calculation results. Here, the integration point n of the plastic state will be described. In the simulation software, there are eight integration points (total of 3,080 in the above calculation) per element (evaluation point of strain).
The number n of integration points in the plastic state indicates the total number of integration points that have shifted from the elastic deformation state to the plastic deformation state as the deformation progresses.
【００２０】図11から、一軸平板圧縮では大きく別けて
３つの変形過程が存在することがわかる。ここに、領域
ａは、弾性座屈の変形過程であり、領域ｂは、皺頂点部
およびチャック部の近傍が降伏を始め、塑性変形領域が
急激に拡大する変形領域であり、領域ｃは、皺頂点部お
よびチャック部の近傍が降伏を完了し、皺中央部両サイ
ドの斜面部が一定の割合で降伏してゆく変形過程である
と考えられる。FIG. 11 shows that there are three major deformation processes in uniaxial flat plate compression. Here, the region a is a deformation process of elastic buckling, the region b is a deformation region where the vicinity of the wrinkle apex and the chuck portion starts yielding, and the plastic deformation region rapidly expands, and the region c is It is considered that the deformation process is such that the yielding is completed in the vicinity of the wrinkle apex and the chuck portion, and the slopes on both sides of the wrinkle central portion yield at a constant rate.
【００２１】図10および図11から、領域ａ，ｃでは弾性
変形と塑性変形との相違はあるが、これら領域ａ，ｃの
ように変形が一定の割合で安定して進行する場合には、
対応する領域での皺評価パラメータPwは皺高さｈに比例
して増加することがわかる。これは、皺高さｈが大きく
なる程、言い換えると座屈が大きくなる程、皺中央部両
サイドでの応力解放が大きくなるため、式の右辺第２
項の解析結果から得られる相当応力σe が小さくなるか
らであると考えられる。From FIGS. 10 and 11, although there is a difference between elastic deformation and plastic deformation in the regions a and c, when the deformation progresses stably at a constant rate as in these regions a and c,
It can be seen that the wrinkle evaluation parameter Pw in the corresponding area increases in proportion to the wrinkle height h. This is because the greater the wrinkle height h, in other words, the greater the buckling, the greater the stress release on both sides of the wrinkle center.
It is considered that the equivalent stress σe obtained from the analysis result of the term becomes smaller.
【００２２】また領域ｂでは、降伏する領域が急激に拡
大するため、全体としての応力が一気に解放される結
果、式の右辺第１項のσesと第２項のσe とが共に小
さくなるので、その差である皺評価パラメータPwも減少
すると考えられる。Further, in the region b, since the yielding region expands rapidly, the stress as a whole is released at a stretch, and both σes of the first term and σe of the second term on the right side of the equation become smaller. It is considered that the wrinkle evaluation parameter Pw, which is the difference, also decreases.
【００２３】以上の結果から、本願発明者が設定した皺
評価パラメータPwは、降伏が急激に進行する過渡的な状
態を除けば皺高さｈにほぼ比例して増加しており、皺の
発生量を充分評価できるものと考えられる。From the above results, the wrinkle evaluation parameter Pw set by the inventor of the present invention increases almost in proportion to the wrinkle height h except for a transient state in which yielding rapidly progresses. It is considered that the amount can be sufficiently evaluated.
【００２４】図１〜図３は、上記コンピュータで上記シ
ミュレーションソフトウェアを用いて上記一軸平板圧縮
の場合と同様にして行った、この発明の皺発生予測方法
を自動車のドアインナーパネルのプレス成形に適用した
一実施例の解析結果を、実際にそのプレス型を製作して
行った実験結果と対比して示すものであり、ここで、図
１（ａ）は、プレス型の下死点前２０mmでの成形途中の
板状素材の変形状態、同図（ｂ）は、その変形状態にお
ける板状素材上での皺評価パラメータPwの分布状態、図
２（ａ）は、プレス型の下死点前１０mmでの成形途中の
板状素材の変形状態、同図（ｂ）は、その変形状態にお
ける板状素材上での皺評価パラメータPwの分布状態、そ
して図３（ａ）は、プレス型の下死点での成形終了時の
板状素材の変形状態、同図（ｂ）は、その変形状態にお
ける板状素材上での皺評価パラメータPwの分布状態をそ
れぞれ示す。FIGS. 1 to 3 show the wrinkle occurrence prediction method of the present invention applied to the press molding of a door inner panel of an automobile, which is performed in the same manner as in the case of the uniaxial flat plate compression using the simulation software by the computer. FIG. 1A shows an analysis result of one embodiment in comparison with an experimental result obtained by actually fabricating the press die. Here, FIG. (B) is a distribution state of the wrinkle evaluation parameter Pw on the plate material in the deformed state, and FIG. 2 (a) is a state before the bottom dead center of the press die. The deformed state of the plate material in the process of molding at 10 mm, FIG. 3B shows the distribution state of the wrinkle evaluation parameter Pw on the plate material in the deformed state, and FIG. Deformation state of plate material at end of molding at dead center FIG (b) shows the distribution of wrinkles evaluation parameters Pw on plate material in its deformed state, respectively.
【００２５】これら図１〜図３の各々の（ａ）に示す素
材の皺発生場所Waに対応する（ｂ）の場所Wsにて、皺評
価パラメータPwが他の場所より大きくなっており、これ
ら図１〜図３から明らかなように、実際に、複雑な形状
のプレス成形に上記方法を適用した場合にも、素材の変
形が進んで皺が大きくなるにつれて、その皺発生位置に
おける皺評価パラメータPwの最大値も大きくなり、皺評
価パラメータPwの値が大きい範囲も拡大することが確認
された。In each of FIGS. 1 to 3, the wrinkle evaluation parameter Pw is larger at the location Ws of (b) corresponding to the location Wa of the material shown in (a) of FIG. As apparent from FIGS. 1 to 3, even when the above method is actually applied to press molding of a complicated shape, as the material deforms and the wrinkles increase, the wrinkle evaluation parameter at the position where the wrinkles occur is increased. It was confirmed that the maximum value of Pw also increased, and the range in which the value of the wrinkle evaluation parameter Pw was large also expanded.
【００２６】かくしてこの実施例の皺発生予測方法によ
れば、素材への皺発生の有無を、上記式で求めた皺評
価パラメータPwによって定量的に判断することができる
とともに、その発生場所を明確に特定することができる
ので、設計段階では皺の発生がないと判断されたプレス
金型について製作段階で修正作業が必要となってその金
型で加工するプレス製品の開発期間が延びてしまうとい
う不都合を確実に防止することができる。Thus, according to the wrinkle occurrence prediction method of this embodiment, the presence or absence of wrinkle occurrence in the material can be quantitatively determined by the wrinkle evaluation parameter Pw obtained by the above equation, and the location of the occurrence can be clearly defined. Therefore, it is necessary to correct the press mold that is determined to have no wrinkles at the design stage at the manufacturing stage, and the development period of the press product processed by the mold will be extended. Inconvenience can be reliably prevented.
【００２７】なお、上記図１〜図３や図９では色彩を付
すことができないので、皺発生パラメータ値の大きさの
相違をハッチングで描き分けたが、上記実施例において
は実際上は、上記シミュレーションを行うコンピュータ
により成形途中および成形終了時の上記素材の形状を３
次元で画面表示するとともに、その素材の各部の皺発生
パラメータ値の大きさの相違をその素材の各部の表示色
の相違として画面表示しており、それゆえ上記実施例に
よれば、成形中の素材や成形後のプレス製品における皺
発生位置を容易に目視確認することができる。In FIGS. 1 to 3 and FIG. 9, since colors cannot be added, differences in wrinkle generation parameter values are indicated by hatching. The shape of the above-mentioned material during molding and at the end of molding is determined by a computer that performs simulation.
In addition to displaying the screen in two dimensions, the difference in the value of the wrinkle generation parameter value of each part of the material is displayed as the difference in the display color of each part of the material, and therefore, according to the above embodiment, It is possible to easily visually check the position of wrinkles in the raw material and the pressed product after molding.
【００２８】以上、図示例に基づき説明したが、この発
明は上述の例に限定されるものでなく、例えば、プレス
成形シミュレーションを行うコンピュータと、その結果
を用いて皺評価パラメータを算出するコンピュータとを
別にしても良い。そしてこの発明の方法は、上記実施例
の自動車のドアインナーパネルのプレス成形以外にも適
用し得て、その場合にも上述した作用効果をもたらすこ
とができる。Although the present invention has been described with reference to the illustrated examples, the present invention is not limited to the above-described examples. For example, a computer for performing a press forming simulation and a computer for calculating wrinkle evaluation parameters using the results are provided. May be separated. The method of the present invention can be applied to other than the press forming of the door inner panel of the automobile of the above embodiment, and in such a case, the above-described effects can be obtained.
【図１】（ａ）は、この発明の皺発生予測方法を自動車
のドアインナーパネルのプレス成形に適用した一実施例
と対比するための実際のプレス型の下死点前２０mmでの
成形途中の板状素材の変形状態を示す説明図であり、
（ｂ）は、その変形状態における板状素材上での上記実
施例の方法で求めた皺評価パラメータPwの分布状態を示
す説明図である。FIG. 1 (a) is a process of forming a wrinkle occurrence prediction method of the present invention in comparison with an embodiment in which the method is applied to press forming of a door inner panel of an automobile in the middle of forming an actual press die 20 mm before a bottom dead center. It is an explanatory view showing a deformed state of the plate-shaped material of
(B) is an explanatory diagram showing a distribution state of wrinkle evaluation parameters Pw obtained by the method of the above embodiment on the plate-like material in the deformed state.
【図２】（ａ）は、上記実際のプレス型の下死点前１０
mmでの成形途中の板状素材の変形状態を示す説明図であ
り、（ｂ）は、その変形状態における板状素材上での上
記実施例の方法で求めた皺評価パラメータPwの分布状態
を示す説明図である。FIG. 2 (a) is a diagram showing a state before the bottom dead center of the actual press die.
FIG. 7B is an explanatory diagram showing a deformed state of a plate-like material in the process of molding in mm, and (b) shows a distribution state of wrinkle evaluation parameters Pw obtained on the plate-like material in the deformed state by the method of the above embodiment. FIG.
【図３】（ａ）は、上記実際のプレス型の下死点での成
形終了時の板状素材の変形状態を示す説明図であり、
（ｂ）は、その変形状態における板状素材上での上記実
施例の方法で求めた皺評価パラメータPwの分布状態を示
す説明図である。FIG. 3 (a) is an explanatory diagram showing a deformed state of a plate-shaped material at the end of molding at the bottom dead center of the actual press die,
(B) is an explanatory diagram showing a distribution state of wrinkle evaluation parameters Pw obtained by the method of the above embodiment on the plate-like material in the deformed state.
【図４】一般的な、加工硬化に伴う降伏曲面の拡大状況
を示す説明図である。FIG. 4 is an explanatory diagram showing a general state of enlargement of a yield surface due to work hardening.
【図５】一般的な、皺発生（座屈）時の応力状態を示す
概念図である。FIG. 5 is a conceptual diagram showing a general stress state when wrinkles occur (buckling).
【図６】この発明の皺発生予測方法の一実施例に用いた
弾塑性変形シミュレーションソフトウェアの皺形状計算
精度確認のための平板一軸圧縮計算用材料メッシュを示
す平面図である。FIG. 6 is a plan view showing a material mesh for flat plate uniaxial compression calculation for checking wrinkle shape calculation accuracy of elasto-plastic deformation simulation software used in one embodiment of the wrinkle occurrence prediction method of the present invention.
【図７】上記皺形状計算精度確認のための平板一軸圧縮
計算の結果の変形形状を４段階の皺高さについて示す斜
視図である。FIG. 7 is a perspective view showing a deformed shape obtained as a result of the flat plate uniaxial compression calculation for checking the wrinkle shape calculation accuracy with respect to four wrinkle heights.
【図８】上記皺形状計算精度確認のための平板一軸圧縮
計算の結果と実験結果とを比較して示す関係線図であ
る。FIG. 8 is a relation diagram showing a comparison between a result of a flat plate uniaxial compression calculation for checking the wrinkle shape calculation accuracy and an experimental result.
【図９】上記皺形状計算精度確認のための平板一軸圧縮
計算の結果から求めた皺評価パラメータの分布状態を４
段階の皺高さについて示す斜視図である。FIG. 9 shows the distribution state of wrinkle evaluation parameters obtained from the result of the flat plate uniaxial compression calculation for checking the wrinkle shape calculation accuracy as 4
It is a perspective view which shows about the wrinkle height of a step.
【図１０】上記皺形状計算精度確認のための平板一軸圧
縮計算の結果から求めた皺評価パラメータの最大値と皺
高さとの関係を示す関係線図である。FIG. 10 is a relationship diagram showing a relationship between a maximum value of a wrinkle evaluation parameter and a wrinkle height obtained from a result of a flat plate uniaxial compression calculation for checking the wrinkle shape calculation accuracy.
【図１１】上記皺形状計算精度確認のための平板一軸圧
縮計算の結果から求めた塑性状態の積分点数と皺高さと
の関係を示す関係線図である。FIG. 11 is a relationship diagram showing a relationship between the number of integrated points in the plastic state and the height of wrinkles obtained from the result of the flat plate uniaxial compression calculation for checking the accuracy of wrinkle shape calculation.
Ａ，Ｂ，Ｄ，Ｅ 降伏曲面 ｈ 皺高さ dx 材料移動量 Pw 皺評価パラメータ Wa 皺発生場所 Ws 皺評価パラメータの値の大きい場所 A, B, D, E Yield surface h Wrinkle height dx Material movement amount Pw Wrinkle evaluation parameter Wa Wrinkle occurrence location Ws Wrinkle evaluation parameter large value
Claims (2)
に基づく板状素材のプレス成形シミュレーションを行
い、その結果に基づいて皺の発生を予測するに際し、 前記プレス成形シミュレーションでの前記素材のプレス
成形過程における単位時間毎の各要素の相当応力および
相当歪を出力し、 前記出力した相当歪に対し前記素材の加工硬化曲線から
得られる相当応力と、前記出力した相当応力との差を皺
評価パラメータとして求め、 前記皺評価パラメータの値に基づいて皺発生の有無を判
断することを特徴とする、プレス成形における皺発生予
測方法。1. A press-forming simulation of a plate-like material based on an elasto-plastic finite element method using a computer, and when predicting the occurrence of wrinkles based on the result, press-forming the material by the press-forming simulation. Output the equivalent stress and equivalent strain of each element per unit time in the process, and calculate the difference between the equivalent stress obtained from the work hardening curve of the material and the outputted equivalent stress for the output equivalent strain, wrinkle evaluation parameter And determining whether or not wrinkles have occurred based on the value of the wrinkle evaluation parameter.
形途中および成形終了時の前記素材の各部の皺発生パラ
メータ値の大きさの相違を表示色の相違として前記コン
ピュータで画面表示することを特徴とする、請求項１記
載のプレス成形における皺発生予測方法。2. The computer according to claim 1, wherein the difference in the value of the wrinkle generation parameter value of each part of the material during the molding in the press molding simulation and at the end of the molding is displayed on the computer as a difference in display color. The method for predicting wrinkles in press molding according to claim 1.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10127500A JPH11319971A (en) | 1998-05-11 | 1998-05-11 | Method for predicting occurrence of wrinkle in pressing |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10127500A JPH11319971A (en) | 1998-05-11 | 1998-05-11 | Method for predicting occurrence of wrinkle in pressing |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH11319971A true JPH11319971A (en) | 1999-11-24 |
Family
ID=14961516
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP10127500A Withdrawn JPH11319971A (en) | 1998-05-11 | 1998-05-11 | Method for predicting occurrence of wrinkle in pressing |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH11319971A (en) |
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