JP4160501B2 - Wrinkle suppression force distribution control device for plate press forming - Google Patents

Description

  The present invention relates to control of wrinkle restraining force distribution in plate press forming, and also relates to a module that generates a distribution load of wrinkle restraining force that is optimal for use in the control.

In the plate forming process, variable control of the wrinkle restraining force and optimization of the distribution state are technical issues that are highly important from the viewpoint of in-process optimization. However, the process control principle and basic algorithm of the wrinkle restraining power have not been clearly established so far. In particular, recent trends in wrinkle restraining force control technology include the application to more general non-axisymmetric shape forming problems, based on research results on wrinkle restraining force control technology for simple forming objects such as cylindrical deep drawing. There is a lot of attention in the development. That is, development of a wrinkle restraining force control technique for optimizing the process by suppressing defective phenomena such as wrinkles and fractures in the non-uniform deformation behavior based on the complex shape of the workpiece has been promoted. However, in many cases, setting of conditions such as wrinkle restraining power is performed depending on a trial and error method based on empirical skills and knowledge of skilled engineers at the time of process design. Therefore, this is a problem to be solved in improving the efficiency of the production process, and a wrinkle restraining force control technology that can obtain a clear effect should be established, but it has not been realized yet. Especially in complex molded products with high molding difficulty and molding that requires a high degree of processing, not only the wrinkle suppression force itself but also the optimization of the distribution state is an extremely important factor, but this is a trial and error method. It is more difficult to determine, and even a skilled engineer requires a lot of time and labor for process design.
However, the technical problem in the wrinkle restraining force control technology field is the wrinkle restraining force control technology that can flexibly deal with arbitrary complex shapes without trial and error, specifically the distribution state of rational wrinkle restraining force. The development of an algorithm for determining the load is cited as an urgent issue.

FIG. 1 schematically shows a state in which a blank holder 112, which is an integral rigid body, suppresses the blank 120 against the die 130. A conventional blank holder is treated as an integral rigid body, and when suppressing wrinkles that occur in the workpiece, paying particular attention to the deformation behavior in the inflow direction, as shown in FIG. The restraining force BHF is intensively loaded. Therefore, the applied wrinkle restraining force acts locally on the wrinkles, and the effect is merely local deformation at the site of action, and the restraining effect on the entire wrinkles is small. That is, since most of the portion is not loaded with the wrinkle restraining force, it cannot cope with the suppression of wrinkle generation at that portion, and the wrinkle restraining effect of the wrinkle restraining force cannot be expected sufficiently. Therefore, in order to realize effective wrinkle suppression in the entire region to be molded, it is necessary to take into account the distribution of wrinkle restraining force in the flange inflow direction and to control the distribution during molding.
With regard to the distribution of wrinkle restraining force, the thin blank and thickness distribution of the blank holder surface is used to study the equalization of the wrinkle restraining pressure in each part and the split blank that divides the rigid blank holder. -Although the holder has been developed, a technique for controlling the distributed pressure that can cope with the local wrinkle suppression as described above has not yet been established. In particular, the determination of the distribution state of the wrinkle restraining force is difficult with the process design based on the conventional trial and error means, and it is essential to improve the efficiency of the systemized process design that can be designed in a short period of time. For this purpose, an algorithm capable of efficiently determining an effective wrinkle restraining force distribution including the distribution in the flange inflow direction is required.

An object of the present invention is to provide a system for optimally controlling the wrinkle restraining force in the inflow direction of the work material and the circumferential direction orthogonal thereto during molding.
It is also an object of the present invention to provide a blank holder module that generates a distributed load of wrinkle restraining force.

In order to achieve the above-mentioned object, the present invention provides a sensor for detecting a plate thickness T _i based on a detection distance between a segment in contact with a blank and a die in each region of the flange portion divided into regions. A data input means for inputting data from a sensor unit having a sensor for detecting displacement f in a plurality of directions of the flange end, a sensor for detecting punch stroke S, and a flange unit from the displacement f of the flange end in a plurality of directions a region displacement means for determining the area displacement f _i of each region, and a thickness T _i and the area displacement f _i of the respective regions, and wrinkling risk estimation means for evaluating creasing risk of each region, punch and a region displacement f _i of the stroke S and the regions, and the rupture risk estimation means for evaluating the fracture risk of each region, the output from the wrinkle occurs when the risk estimation means the breaking risk estimation means, each The wrinkle restraining force increment value ΔBHF for obtaining the wrinkle restraining force increment value ΔBHF for each region and the actuator driving means for controlling the actuator that generates the wrinkle restraining force provided for each region of the flange portion is output. And a wrinkle suppressing force distribution control device for press forming a sheet material.

The wrinkle occurrence risk evaluation means is related as a deviation between the plate thickness T _i and the region displacement f _i from the sensor unit and the reference plate thickness curve representing the relationship between the plate thickness T _i and the region displacement f _i . A wrinkle occurrence risk evaluation function can be used.
The fracture risk estimation means, said a region displacement f _i and punch stroke S from the region displacement means, the area displacement f _i and breaking occurs that is associated as a deviation between the reference machining curve representing the relationship between the punch stroke S A risk evaluation function can be used.
The fracture risk evaluation means may use a ductile fracture condition formula.
The wrinkle restraining force calculating means may use fuzzy reasoning.
A program for causing the above-described means to function in a computer system is also the present invention.
Further, as the actuator for generating the wrinkle suppressing force, a blank holder module having a plurality of actuators that divide the plane and apply pressure may be combined.
The blank holder module may comprise an actuator having a cylinder and a piston driven by fluid from ports of different heights.

  By using this control system, the wrinkle suppression force works optimally on each part of the workpiece material being molded. Therefore, by suppressing the occurrence of molding defects such as wrinkles and fractures, complex molded shapes and high processing It is possible to mold to a certain degree, and further increase the efficiency of production.

Embodiments of the present invention will be described with reference to the drawings.
FIG. 2 shows an outline of the wrinkle restraining force according to the present invention, and shows a state in which the distribution of the wrinkle restraining force BHF is loaded. In order to achieve effective wrinkle suppression in the entire region to be molded, as shown in FIG. 2, considering the distribution of wrinkle suppression force in the flange inflow direction, using a split blank holder, etc. It is necessary to control the distribution during molding.
In the present invention, in order to optimize not only the size of the wrinkle restraining force but also the complex shape press molding whose distribution state greatly affects the moldability, the material inflow direction and circumferential direction (with respect to the inflow direction) We propose an algorithm that appropriately determines the distribution of the wrinkle restraining force (perpendicular direction) during molding. For the distribution load of the wrinkle restraining force, a blank holder divided into a plurality of small regions or a plate pressing device having an equivalent function is used at least in the circumferential direction or the inflow direction. By distributing the wrinkle restraining force to the flange portion and controlling it optimally during molding, it is possible to effectively suppress the occurrence of molding defects such as wrinkles and fractures.

FIG. 3 shows an example of the embodiment of the present invention. One of the embodiments shown in FIG. 3A is a form that is directly incorporated into the actual molding apparatus. The sensor unit 140 is controlled by the control unit 150 and the control unit 150 and measures the actuator unit 110 that generates a distributed load of wrinkle restraining force and the blank material 120 that is acted on by the actuator unit 110 and feeds back to the control unit 150 It is comprised by.
In FIG. 3A, the data reading unit 152 reads fuzzy parameters and the like used in the control algorithm from the database 230. Based on this data and the data from the sensor unit 140, the real-time evaluation data calculation unit 154 controls the actuator driving unit 156 to drive the actuator unit 110.
As another form, as shown in FIG. 3B, there is a form of virtual forming in which the wrinkle restraining force is changed as a boundary condition by numerical analysis such as a finite element method and is controlled and shaped on a computer. In this embodiment, the control unit 150 ′ converted into a subroutine is used to analyze the analysis model 164 by giving a boundary condition 162, and the analysis data is fed back to the control unit 150 ′. In the control unit 150 ′, the boundary condition given to the analysis model 164 is changed by the boundary condition changing unit 157 instead of the actuator driving unit. This is a form implemented in process design prior to actual molding.
In these, the algorithm described in detail below is implemented in the control units 150 and 150 ′.

<Basic algorithm concept>
The concept of this algorithm is local optimization for the wrinkle restraining force that constitutes the distribution of the entire load region. FIG. 4 shows a conceptual diagram when the wrinkle restraining force control algorithm is applied.
FIG. 4 (a) shows, in part, how a blank is formed by a punch (not shown), a die 130 and a blank holder (not shown) as seen in a typical plate forming process. It is. The flange portion is divided into several small areas of at least two divisions (in the figure, an arbitrary size and an arbitrary number) in the inflow direction and the circumferential direction. The application target of this algorithm is a case where the blank holder is divided into regions, and an independent wrinkle restraining force or wrinkle restraining pressure can be controlled by an actuator or the like in each divided region. The division mode is divided by a rectangular shape having the same size in FIG. 4A, but the application target of the present algorithm is not limited thereto (for example, a division method based on a hexagon may be used). . In addition to the case where the blank holder is physically divided, a blank holder having a structure capable of applying an independent pressure to each block even when the blank holder is integrated can be used.

In this algorithm, in order to determine the optimum wrinkle restraining force to be applied to each divided region, the concept of wrinkle restraint control established in cylindrical deep drawing as shown in FIG. 4B is introduced. FIG. 4B shows the basic concept of process control of cylindrical deep drawing that is the basis of this algorithm.
First stage: Detection by sensor unit 140 composed of sensor group of process variables during molding Second stage: Based on real-time evaluation data such as punch stroke and blank holder lifting amount associated with blank inflow Evaluation and reasoning of risk of breakage and wrinkles (control unit 150)
Third stage: Determination of optimum wrinkle restraining force using fuzzy reasoning method to avoid breakage and wrinkle (control unit 150)
Based on the above concept of process control, this algorithm predicts and evaluates wrinkles and fractures based on real-time evaluation data of machining variables for each divided area, and determines the force applied to each wrinkle suppression area. Is. The determination of the wrinkle restraining force or pressure control amount of each divided region is performed based on a quantitative evaluation with respect to molding defects at a site where each wrinkle restraining force effectively acts. That is, in order to determine the amount of control given to each region, evaluation values for wrinkles and breakage of each part of the workpiece are required. From this point of view, as shown in FIG. 4, at a certain forming stage (time t = tx), punch stroke S, blank flange end inflow displacements f1, f2,..., Fn-1, fn, fn + 1,. , Fm (m is the number of displacement measurement directions), and real-time evaluation data of machining variables such as blank holder displacements Ψ _i (i = 1, 2,..., P) on a total of p divided regions. Based on these data, the wrinkle restraining force BHF _i (i = 1, 2,..., P) applied to each region is determined. Then, the determined wrinkle restraining force or pressure is applied to the blank 120 via the actuator 110 sequentially or simultaneously for all the divided regions, and the wrinkle restraining force or pressure distribution in the entire flange portion is controlled.

(Evaluation and avoidance of wrinkle / breakage risk)
With regard to the wrinkle occurrence risk, the blank holder floating amount Ψ (FIG. 4) with respect to the divided region including the wrinkle occurrence part can be used as the wrinkle occurrence risk evaluation. Then, based on the evaluation value of the wrinkle occurrence risk level, the wrinkle restraining force applied to the divided region including the occurrence site is controlled to an optimum value. By determining the wrinkle restraining force at any time during molding for such wrinkle occurrence sites, the wrinkle restraining force is temporally reduced in all directions regardless of the inflow direction or the circumferential direction over the entire wrinkle restraining force load region. A spatial distribution can be determined.
Specifically, as shown in FIG. 5A, a reference thickness curve T _ref that does not change in thickness and an actually measured thickness T are respectively obtained at the same inflow amount f, and a deviation ψ between them is calculated as the wrinkle generation degree. The evaluation value. At this time, the thickness of the measured value T is obtained as the sum of the floating amount of the blank holder during forming an initial thickness T ₀ at the start of molding [psi.
While the wrinkle restraining force control amount for the purpose of suppressing wrinkles is determined, on the other hand, the possibility of breakage increases due to the excessive wrinkle restraining force load. Therefore, an algorithm for predicting and avoiding the fracture phenomenon is required. Therefore, the risk of fracture is quantitatively evaluated from the inflow history of the material having a correlation with the fracture phenomenon, and the control amount of the wrinkle restraining force focusing on the fracture is determined. As another method, it is also possible to use a method of evaluating the risk of rupture by an absolute rupture state using a value obtained by a ductile rupture conditional expression from the state of stress and strain. The latter method is effective in virtual forming (see FIG. 3B) in the embodiment of FIG.

In order to perform the fracture evaluation using the material inflow history, the displacement of the flange end in a specific direction is detected as shown in FIG. 4A, such as the measured displacements fn, fn + 1,. Estimate the risk from the excess or deficiency of the inflow. The measurement direction of the flange end displacement may be basically arbitrary, but it is preferable that the flange end displacement is not changed during molding and coincides with the inflow direction of the blank during molding as much as possible. The inflow amount in each segment can be obtained by an interpolation method or the like based on the displacement amount detected in the measurement line sandwiching the segment. Displacement data from each measurement line is transferred to a data storage area corresponding to each divided area and used for risk assessment of breakage and wrinkles.
Specifically, attention is paid to the difference between the deformation history as a reference for the fracture evaluation shown in FIG. As the deformation history data, the relationship of the punch stroke S to the flange end inflow amount f is used. At this time, in order to define the deformation history as a reference, a forming simulation is performed under the assumption that the plate thickness is constant and the volume is constant, and the history data of the ideal punch stroke S _ref for the flange end inflow amount f is determined. Then, the difference φ between the measured punch stroke S at the measured flange inflow amount f and the reference curve value S _{ref at} f is used as a fracture risk evaluation function.

<Specific example of algorithm>
Among the molding objects having non-uniform deformation behavior, the application method of the wrinkle suppression force distribution determination algorithm in the simplest square tube deep drawing will be described in detail with reference to FIGS.
(Determination of wrinkle suppression distribution based on fracture evaluation)
A specific processing flow when the above algorithm is implemented in the control system and real-time control is performed during molding is shown in the flowchart of FIG.
In the flowchart of FIG. 6, first, prior to processing of a target molded product, a blank type is designated by the operator (S210). Based on the designated type, a suitable fuzzy parameter is read from the database 230 prepared in advance (S212). After the above-described series of initial setting operations is completed, the blank material to be processed is placed at a predetermined position of the press device, and the initial wrinkle suppressing force load is started. Thereafter, the lowering of the punch starts (S214), and molding starts.
During this time, the flange end inflow displacement f, the punch stroke value S, and the blank holder lifting amount Ψ in each divided region necessary for the operation of the wrinkle restraining force distribution determination algorithm are measured inline every moment (S218). Based on these measured values, the incremental wrinkle suppression force increment value ΔBHF is determined for each divided region using fuzzy inference (S240). This is performed for all segments (S216 to S222), and when the processing is completed for all segments (“Yes” in S222), a wrinkle suppressing force load is applied to the actuator (S226).
This series of processes is repeated until the molding is completed (S216 to S228).
By using the database 230, it is possible to easily determine control rules even if the user is not a skilled person, and on the other hand, it is possible to add empirically acquired skills possessed by excellent skilled persons to the system. This is because the if-then rule used in the control system can easily express the operator's knowledge as a rule.
For example, if at a certain point in the molding process, the occurrence of a local wrinkle in a part is empirically obtained for a specific tendency of the inflow state, a rule is added to increase the wrinkle suppression pressure (increment) in that part. Can do. Thus, by changing the rule, the knowledge of the operator is reflected in the control system.

(Increase value of wrinkle restraining force by fuzzy reasoning part)
The control amount increment ΔBHF of the wrinkle restraining force or pressure in each divided region is determined by using fuzzy inference based on the fracture / wrinkle evaluation function for the blank material. The fuzzy control rules used at this time are determined semi-automatically based on the fuzzy parameters stored in the database 230 in advance. This fuzzy parameter is data associated with a machining variable and a machining history at the time of occurrence of fracture or wrinkle, and is obtained in a preliminary experiment or a prior molding simulation. This is normally stored in the database 230. By designating a data item suitable for the molding object in the database 230, a control rule used for the control system is read, and an appropriate control rule is determined without trial and error.

The flow of the fuzzy inference process will be described with reference to the flowchart of FIG. First, the flange end inflow amount f, the stroke S, and the blank holder lift amount Ψ are measured using a sensor incorporated in the press device (S218). First real time evaluation data φ and second real time evaluation data (differential value of the first real time evaluation data) φ ′ are calculated from the deviation between the reference machining curve and the actual measurement data shown in FIG. At this time, the third real-time evaluation data Ψ and the fourth real-time evaluation data (differential values of the third real-time evaluation data) Ψ ′ are calculated using the reference plate thickness curve and the actually measured blank holder lift Ψ. (See FIG. 5 (a)). Then, the first and second real-time evaluation data φ and φ ′ are input values for the input-side membership functions μ _φ and μ _{φ ′} , and similarly, the third and fourth real-time evaluation data Ψ and Ψ. 'the mu _[psi, mu _[psi' used as respective input value for the input-side membership function part area of fuzzy sets _{(a ψS, a ψL, a} ψ'S, a ψ'L, a φS, a φL, A _{φ ′S} , A _φ′L ) are obtained respectively (S244: see FIGS. 8A and 8B). Then, determination processing is performed based on the if-then rule shown in Table 1 (breakage risk φ, φ ′) and Table 2 (wrinkle risk Ψ, ψ ′) (S245).

図８（ｃ），（ｄ）に示す、破断およびしわ抑制に対する出力値を決定したメンバーシップ関数それぞれにおいて、代入面積の重心位置Ｇを特定する。ただし、重心位置Ｇは出力側メンバーシップ関数の横軸方向の位置であり、以下の式で与えられる。

ここで、ａ_ｉ，ｇ_ｉはそれぞれ、出力側メンバーシップ関数を任意に分割した領域の面積および個々の重心位置である。この重心位置Ｇとして、しわ抑え力の増分値ΔＢＨＦ_ｆおよびΔＢＨＦ_ｗを求める。この２つの値を統合し、最終的なしわ抑え力増分値ΔＢＨＦを求める。 Next, the area in each input side membership function shown in FIGS. 8A and 8B is substituted into the output side membership function (S246: see FIG. 8C). The substitution area is calculated by the following formula.

The center-of-gravity position G of the substitution area is specified in each of the membership functions that determine the output values for fracture and wrinkle suppression shown in FIGS. However, the center-of-gravity position G is the position of the output side membership function in the horizontal axis direction, and is given by the following equation.

Here, a _i and g _i are the area of each region obtained by arbitrarily dividing the output-side membership function and the position of the center of gravity. As the gravity center position G, wrinkle restraining force increments ΔBHF _f and ΔBHF _w are obtained. These two values are integrated to obtain the final wrinkle restraining force increment value ΔBHF.

(Learning for fuzzy reasoning)
The fuzzy rules used in the present invention are determined based on a database related to molding conditions. At this time, when the read fuzzy rule (parameter) is applied to the target, if good molding is not achieved, the fuzzy system is learned from the processing history at that time, and the reliability of the control system is improved. Is possible. This is offline learning of fuzzy rules for environmental conditions and mechanical property fluctuations that are often problematic in the production field, such as differences in the lubrication state during database molding and actual molding, slight variations in material properties, and dimensional changes. It is possible to respond by optimization based on.
Specifically, this is achieved by changing the fuzzy parameters in the process flow shown in FIG. 9 (S254).

として用いることができる。また、関数φ（ｆ_１）のｆ_１による変化率（微係数）である破断危険度の変化の傾向を示す評価関数として、

を用いる。これらの評価関数を定めることで、破断危険度はφおよびφ’の増大として評価可能となる。 <Specific example of wrinkle restraining force distribution determination>
Of the molding objects having non-uniform deformation behavior, the application method of the wrinkle restraining force distribution determination algorithm in the simplest square tube deep drawing will be described in detail below with reference to FIGS.
(Determination of wrinkle restraining force distribution based on fracture risk assessment)
Divided blank holders placed on the flange section are divided into areas A and B, and the risk of breakage is evaluated for the deformation of blanks belonging to each area, and wrinkle suppression pressure to avoid breakage is applied to each area. decide.
Specifically, as shown in FIG. 10, the tip of a contact-type displacement sensor (not shown) is brought into contact with the flange edge portion in region A, and the displacement in the measurement line 1 direction is measured. The measured value and _{f 1.} At this time, using the relationship f ₁ and the punch stroke S as an evaluation index of fracture risk. In other words, the line edge direction displacement f _{1 of} the corner edge obtained in advance by FE simulation assuming that no change in the plate thickness occurs and the relationship S _ref between the punch stroke and the stroke S are compared with the relationship between f ₁ and S actually measured during molding. By doing so, the risk of breakage is evaluated from the excess or deficiency of the material inflow.
That is, the evaluation function φ (f ₁ ) of the risk of fracture in the region B is

Can be used as Further, as an evaluation function indicating the tendency of change in the risk of fracture, which is the rate of change (derivative coefficient) of the function φ (f ₁ ) by f ₁

Is used. By determining these evaluation functions, the risk of fracture can be evaluated as an increase in φ and φ ′.

および、

を定義することで破断危険度が評価される。
以上の破断危険度に対する評価値を成形中時々刻々算出し、この評価値に基づいてそれぞれの領域において、ファジィ推論によりしわ抑え力の増分ΔＢＨＦ_ｆを決定する。 Similarly, for the direction of the measurement line 2, the flange end displacement f _{2 in the} line direction and the punch stroke relationship S _ref obtained in advance by simulation are used to measure the flange end displacement f ₂ and the punch measured actually.・ Evaluate the risk of breakage based on the stroke. That is, as the fracture evaluation function φ (f ₂ ) in the region B,

and,

The risk of breakage is evaluated by defining.
The evaluation value for the above risk of fracture is calculated every moment during molding, and the wrinkle restraining force increment ΔBHF _f is determined by fuzzy inference in each region based on this evaluation value.

を用いる。そして、しわ発生危険度の変化の傾向として、

を用いることができる。
以上のしわ発生危険度に対する評価値を成形中時々刻々算出し、この評価値に基づいてそれぞれの領域において、しわ抑え力の増分ΔＢＨＦ_ｗをファジィ推論する。 (Determination of wrinkle restraining force distribution based on wrinkle risk assessment)
The control amount of the wrinkle restraining force for the purpose of wrinkle suppression is determined for each segment based on the wrinkle generation height. This operation is sequentially performed on all the segments to determine the wrinkle restraining force distribution of the entire load region.
Specifically, as shown in FIG. 11, the wrinkle occurrence degree is evaluated for each segment based on the displacement amount Ψ of the blank holder lifted by the generation of wrinkles. That is, in the segment i that belongs to the area A, and measured the displacement amount d _i of the blank holder, an evaluation function [psi _i the wrinkle for the i th segment,

Is used. And as a tendency of the wrinkle occurrence risk change,

Can be used.
The evaluation value for the wrinkle occurrence risk is calculated momentarily during molding, and the increment ΔBHF _w of the wrinkle restraining force is fuzzy inferred in each region based on the evaluation value.

によって、しわ抑え力増分値を決定する。 (Update algorithm for wrinkle suppression)
By the above two processes, two values, ΔBHF _f and ΔBHF _w, are obtained for the break and the wrinkle as the increment value of the wrinkle restraining force for each segment. In order to calculate the final wrinkle suppression change amount, both values are compared and a larger value is used as the wrinkle suppression force increment value at this time.
That is,

The wrinkle restraining force increment value is determined by.

で表される。ここで、ａ_ｎ（ｎ＝１，…，Ｍ）はモデル・パラメータであり、以下で定義される二乗誤差関数が最小となるように、時刻ｎ以前の時系列データにより値が決定される。

<Introduction of prediction for evaluation function>
By using differential values such as formulas (4), (6), and (8) as the second evaluation function as an evaluation function that represents the tendency of the risk of wrinkles and fractures, an action is applied to the prediction based on the tendency. be able to. However, due to the nonlinear / unsteady characteristics peculiar to the plate forming process, the prediction based only on the rate of change of the evaluation function value results in an insufficient control result. Therefore, at the time of calculating the wrinkle restraining force increment value, it is necessary to improve the reliability of the evaluation function value by predicting the history after the control time using the history data so far.
For this purpose, a prediction system using an Mth-order autoregressive model (AR _(M) ) is applied to the evaluation function value prediction. The AR _(M) model is based on the time series data {x (n) | n = 1,..., T} of the observation variable x. This is one method for predicting. That is, the observed value hat x (t + 1) at the next time n + 1 is estimated by linear combination of the observed values at times n, n−1,..., N−M + 1. That is,

It is represented by Here, a _n (n = 1,..., M) is a model parameter, and a value is determined by time series data before time n so that the square error function defined below is minimized.

を用いることができる。ここで、Ψ（ｎ）は式（７）と対比させて、時刻ｔ＝ｎにおけるブランク・ホルダの変位量を表し、Ψ_ｒｅｆ（ｎ）は参照データ履歴を表す。
予測データに基づく評価関数の導入に伴い、しわ抑え力制御値決定のためのｉｆ−ｔｈｅｎルールが新たに必要となる。この場合のルールの一例として、

などを用いることで、予測データに対する評価関数を加味したファジィ制御が達成される。また、予測データの信頼度が高くない場合においても、第１，第２の評価関数に基づいて妥当な評価によりファジィ制御に問題を引き起こす可能性は低くなる。 The evaluation function value is predicted using the above prediction model. FIG. 12 shows an example in which wrinkle occurrence risk Ψ is used as an evaluation function for the concept of applying prediction. When determining the incremental value ΔBHFw (n) of the wrinkle restraining force at a certain time t = n, an evaluation function at a time t = n + 1 future from t = n is estimated from time series data before t = n, and the evaluation function Estimate the future value Ψ (n + 1) of the value. That is, as an evaluation function after the third,

Can be used. Here, Ψ (n) is compared with Expression (7), and represents the displacement amount of the blank holder at time t = n, and Ψ _ref (n) represents the reference data history.
With the introduction of the evaluation function based on the prediction data, an if-then rule for determining the wrinkle restraining force control value is newly required. As an example of the rule in this case,

By using the above, fuzzy control in consideration of the evaluation function for the prediction data is achieved. Further, even when the reliability of the prediction data is not high, the possibility of causing a problem in fuzzy control is reduced by an appropriate evaluation based on the first and second evaluation functions.

で定義され、σ_ｍおよびバーσはそれぞれ静水圧応力、相当応力であり、ａ，ｂは材料固有の物性値，バーεは相当ひずみである。上式を用いることで、Ｉ＝１．０により絶対的な値として破断を評価することができる。これは、流入データの過不足に基づく破断評価値は変形状態による影響を受ける点と比較して、高精度な破断判定が可能な点において利点となる。 <Introduction of high-accuracy fracture evaluation based on the ductile fracture model>
As an evaluation function with respect to the risk of fracture, the evaluation function based on the inflow history of the blank material has been described above. On the other hand, by using a ductile fracture condition formula obtained by formulating a ductile fracture model, it becomes possible to handle the fracture during molding strictly. Therefore, a ductile fracture conditional expression is used as the evaluation function instead of the fracture evaluation function based on the inflow data. This is an effective evaluation index particularly when applied to the numerical analysis using the analysis model of FIG. 3B in the embodiment of the algorithm shown in FIG.
Here, as an example of the ductile fracture conditional expression, Oyane's ductile fracture conditional expression is taken up. That is,

Σ _m and bar σ are hydrostatic pressure stress and equivalent stress, a and b are physical property values specific to the material, and bar ε is equivalent strain. By using the above equation, the fracture can be evaluated as an absolute value by I = 1.0. This is advantageous in that the fracture evaluation value based on the excess or deficiency of the inflow data can be determined with high accuracy as compared with the point that it is affected by the deformation state.

In the evaluation based on the inflow history data, a reference curve serving as an evaluation standard is used. However, when the I value is used for the evaluation function, it is difficult to determine a reference curve corresponding thereto. Therefore, the above-described prediction method is applied to the change rate of the I value, and a method of determining the increment value of the wrinkle restraining force based on the change rate at the future time point is applied. An analysis example in which a fourth-order AR model is actually applied to I-value change rate history data is shown in FIG. For the time step (time inc) 30 and later, data one step ahead was sequentially predicted from the previous data history. FIG. 13 (b) shows the basic trends that coincide with each other. Further, this data is integrated with respect to time and compared with the change history of the I value. The prediction data captures the original I value history data, and a reasonable prediction result can be obtained.
Next, a method for applying the integral value I in the ductile fracture conditional expression to fuzzy control will be described. As a basic control guideline, if it is detected that the future behavior of the I value history or the rate of change history is approaching rupture due to a rapid increase, the wrinkle suppression is suppressed. Is to reduce power. As a rule for this,
[Equation 15]
if {I (n + 1) is Large or I '(n + 1) is Large} then {DBHF is Small}
By using the above, it is possible to realize feedback control for future fracture evaluation.

<Module type blank holder>
A blank holder having a module structure that is optimal for the above-described wrinkle restraining force distribution control and that can be separated and freely configured by a wrinkle restraining force load element will be described below.
This is a basic element with shapes that can be combined with each other, so it is highly versatile, and it is possible to reconfigure and reconstruct the blank holder by combining multiple blank holders that are suitable for the molding object. It is possible. Therefore, it is possible to flexibly cope with a molding process of a desired shape.
Each module is equipped with an actuator for controlling the wrinkle restraining force. This module is a basic unit constituting a blank holder shape and a load element unit constituting a wrinkle restraining force distribution. This is because, by providing a plurality of actuators for generating wrinkle restraining force for each module, the degree of freedom of wrinkle restraining force distribution for the blank holder as a whole corresponds to the number of actuators.
The wrinkle suppression pressure applied to each segment built in the module is desirably determined according to the deformation state of the blank to be molded. For this reason, the material deformation state is grasped from the state of the actuator movable portion loaded on each segment and the driving state. For this purpose, it is possible to mount various sensors in the segment, sense displacement and load in-process, and control the wrinkle restraining force based on this information.
With the introduction of the above blank holder module, there is no need to newly manufacture a blank holder for each target shape of the machining process, and the blank holder shape can be appropriately reconfigured by combining multiple modules according to the shape. Rebuild and allow for flexible blank holder assembly. It can be expected as a solution for flexibly responding to low cost and high added value for high-mix low-volume production of the molding process.
FIG. 14B shows an example of a separation constitutional type blank holder constructed as a module structure. In the blank holders 320 and 330, a large number of separate modules each including three small wrinkle restraining force control actuators 321 and 331 are combined and divided into a large number of wrinkle restraining force load regions. By controlling the supply pressure to the actuator of each small segment blank holder independently, it is possible to load an arbitrary wrinkle suppression pressure distribution during molding.

14 (a) shows the wrinkle-restraining force distribution load for L-shaped square tube deep drawing by rearranging the blank holders that comprise the module with three actuators shown in FIG. 14 (b). An example of a configuration to be added is shown. In this way, the point that the distribution load of the wrinkle restraining force can be applied to various molding objects is greatly different from the conventionally used blank holder.
FIGS. 15A and 15B show the structure of a specific module type blank holder 350. The configuration shown in FIG. 15 shows a case where three modules are combined, and the frontmost module 350 shows a state in which the main body is cut in half in order to show the internal structure.
The module 350 main body incorporates three small hydraulic cylinders 352 and a piston 353 integrated as a wrinkle restraining force control actuator. The hydraulic system of each hydraulic cylinder 352 can supply hydraulic pressure independently by changing the height of the three hydraulic supply ports 356. Since the hydraulic systems are independent of each other, individual wrinkle suppression pressures can be independently and variably loaded by individually controlling the supply pressure. The segment blank holder module is attached to the outer plate of the press apparatus by a strong magnet 351 incorporated on the surface opposite to the wrinkle restraining force loading surface. Therefore, the module can be easily attached and detached, and the blank holder can be easily reconfigured. A flexible pressure-resistant hose may be used as a hydraulic pressure supply to the segment, blank, holder, and module. By using this hose, the degree of freedom in handling the hydraulic piping when the blank holder is configured is increased.
It is also possible to change the shape and size of the wrinkle suppressing surface (segment) 357 so that the configuration is suitable for molding objects of various shapes. As an example, FIG. 16 shows a case where wrinkle restraining force distribution control is performed when a complex shape is formed by a module in which three wrinkle restraining surfaces are formed in regular hexagonal shapes.
Compared with the case where the shape of the segment shown in FIGS. 14 and 15 is a square, the degree of freedom in the configuration of the blank holder shape is higher as shown in FIG.

FIG. 17 shows a configuration example of a hydraulic system when this segment blank holder module is used. This hydraulic system is designed and constructed so as to reliably generate the wrinkle restraining force distribution in consideration of the symmetrical characteristics of square tube deep drawing. The pressurized liquid is supplied from a pressure source (not shown) to the blank holder and is controlled by servo valves 522 and 524. The pressure is supplied to the segment actuators 552 and 554 (the piston 353 and the built-in hydraulic cylinder 352 in FIG. 15) of each blank holder through one of 27 directional control valves 532 and 534, for example. ing. The pressure converters 542 and 544 convert pressure to electricity, and the detected pressure is input to the computer system 510 via the A / D converter 514. The servo valves 522 and 524 and the direction control valves 532 and 534 are also controlled by the DI / O 516 and the D / A converter 518 of the computer system 510. The computer system 510 is also implemented with an algorithm for controlling the above-described wrinkle suppression distribution force.
In the above example, an example using hydraulic pressure is shown, but a fluid such as air or water may be used.
Moreover, you may use the actuator which has an equivalent function, such as a piezoelectric element.

Result of change in wrinkle restraining force distribution during molding obtained by performing the above control on square tube deep drawing using the hydraulic system of FIG. 17 using the blank holder of FIG. Are shown in FIGS. The three-dimensional bar graphs of FIGS. 18 (a) to 18 (d) increase the size of the wrinkle suppression pressure of each segment in the quarter region of the square tube deep drawing described with reference to FIGS. It is expressed as The module and the wrinkle suppression pressure were generated as shown in FIGS. 19A to 19C are graphs showing the wrinkle suppression change of each segment.
As shown in FIGS. 18 and 19, the wrinkle restraining pressure applied to each segment varies as the machining progresses, so that the wrinkle restraining force distribution applied to the workpiece changes. As wrinkles develop, the distribution in the inflow direction also changes.

It is a figure for demonstrating the wrinkle restraining force of the blank holder which is the conventional integral rigid body. It is a figure which shows the outline of wrinkle suppression force distribution by this invention. It is a figure which shows embodiment of this invention. It is a figure for demonstrating distributed wrinkle suppression force control. It is a figure explaining wrinkle generation | occurrence | production risk evaluation (a) and fracture | rupture generation | occurrence | production risk evaluation (b). It is a flowchart which shows the processing flow in shaping | molding. It is a flowchart which shows the processing flow of a fuzzy reasoning. Input-side membership function (a) for fracture risk, input-side membership function (b) for wrinkle risk, output-side membership function (c) based on if-then rule for avoiding fracture, wrinkle avoidance It is a figure which shows the output side membership function (d) based on the if-then rule for. It is a flowchart which shows the learning process of a fuzzy reasoning. It is a figure explaining a fracture avoidance algorithm. It is a figure explaining a wrinkle suppression algorithm. It is a figure which shows the evaluation function value with respect to prediction data. It is a figure explaining application of prediction by an autoregressive model to I value. It is a figure which shows the structure of the isolation | separation composition type | mold blank holder using a segment blank holder module. It is a figure which shows the structure of a blank holder module, and the basic composition of a blank holder. It is a figure which shows the structure of the isolation | separation structural formula blank holder comprised by the hexagonal segment. It is a figure which shows the structural example of the hydraulic system for applying a pressure to a blank holder module. It is a three-dimensional bar graph showing the size of the wrinkle restraining pressure of each segment as the height in a quarter of the square tube deep drawing with the wrinkle restraining force distribution during molding. It is a graph showing the wrinkle restraining change of each segment in the wrinkle restraining force distribution during molding.

Claims (8)

In each area of areas divided flange portion, a sensor for detecting based on the detection distance plate thickness T _i between the segments and the die which is in contact with the blank, a sensor for detecting a displacement f of the plurality of directions of the flange end A data input means for inputting data from a sensor unit having a sensor for detecting the punch stroke S;
A region displacement means for determining the area displacement f _i of the respective regions of the flange portion from a plurality of directions of displacement f of the flange end,
Wrinkle occurrence risk evaluation means for evaluating the wrinkle occurrence risk of each area from the plate thickness T _i and the area displacement f _i of each area;
And a punch stroke S and the area displacement f _i, and fracture risk estimation means for evaluating the fracture risk of each area,
A wrinkle restraining force calculating means for obtaining a wrinkle restraining force increment value ΔBHF of each region based on outputs from the wrinkle occurrence risk evaluating means and the fracture risk evaluating means;
Wrinkle suppression in plate press forming, characterized in that actuator driving means for controlling an actuator for generating wrinkle suppression force provided for each region of the flange portion includes output means for outputting the wrinkle suppression force increment ΔBHF. Force distribution control device. The wrinkle occurrence risk evaluation means is related as a deviation between the plate thickness T _i and the region displacement f _i from the sensor unit and the reference plate thickness curve representing the relationship between the plate thickness T _i and the region displacement f _i . 2. The wrinkle restraining force distribution control device for plate press forming according to claim 1, wherein a wrinkle generation risk evaluation function is used. The fracture risk estimation means, said a region displacement f _i and punch stroke S from the region displacement means, the area displacement f _i and breaking occurs that is associated as a deviation between the reference machining curve representing the relationship between the punch stroke S The wrinkle restraining force distribution control device for plate press forming according to claim 1, wherein a risk evaluation function is used. 2. The wrinkle restraining force distribution control device for plate material press molding according to claim 1, wherein the fracture risk evaluation means uses a ductile fracture condition formula. The wrinkle restraining force distribution control device according to claim 1, wherein the wrinkle restraining force calculating means uses fuzzy reasoning. Computer system
A sensor for detecting a plate thickness Ti based on a detection distance between a segment in contact with a blank and a die in each region of the flange portion divided into regions; a sensor for detecting a displacement f in a plurality of directions of the flange end; A data input means for inputting data from a sensor unit having a sensor for detecting the punch stroke S;
Region displacement means for determining the area displacement f _i of the respective regions of the flange portion from a plurality of directions of displacement f of the flange end,
Wrinkle occurrence risk evaluation means for evaluating the wrinkle occurrence risk of each area from the plate thickness T _i and area displacement f _i of each area;
Punch stroke S and from the area displacement f _i, fracture risk evaluation means for evaluating the fracture risk of each area,
A wrinkle restraining force calculating means for obtaining a wrinkle restraining force increment value ΔBHF of each region based on outputs from the wrinkle occurrence risk evaluating means and the fracture risk evaluating means;
A program for causing an actuator driving means for controlling an actuator for generating a wrinkle restraining force provided for each region of the flange portion to function as an output means for outputting the wrinkle restraining force increment value ΔBHF. The plate material press-molding according to claim 1, wherein the actuator for generating the wrinkle restraining force is configured by combining a blank holder module integrally having a plurality of actuators that apply pressure by dividing a plane. Wrinkle restraining force distribution control device. The wrinkle restraining force distribution control device for plate press forming according to claim 7, wherein the blank holder module includes an actuator having a cylinder and a piston driven by fluids from ports having different heights.

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