JP2007130671A - Program for twist determination and correction in pressing, and its method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control supporting means capable of reliably determining whether or not any twist is generated in a pressed article in the pressing simulation using a computer, and obtaining the specific numeral values forming a guideline for controlling the pressing condition for eliminating the twist if any twist is generated, and to control the pressing condition by using the supporting means. <P>SOLUTION: The control supporting means obtains the specific numerical value by the operation through the pressing simulation using a computer while paying attention to the fact that the case for generating the twist is a part of the internal stress exerted in a pressed article before the spring back. The formula T=(q×r)+(Q×r)-M for the operation, where T denotes a part of the internal stress, q denotes the in-plane shearing force, r denotes the distance to the point of evaluation from the center of the evaluation sectional line of the pressed article, Q denotes the shearing force in the thickness direction, and M denotes the torsional moment, respectively. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

In press processing, when manufacturing a processed product, in general, it is difficult to twist even a little, for example, the surface or direction (hereinafter referred to as “measurement point required”) and some twist. There is usually an acceptable place.
Therefore, the present invention inputs press processing conditions such as mold shape, workpiece pressing force, counter force, mold movement amount, etc. in press processing simulation of a processed material (metal plate material) using a computer, It is determined whether or not torsion has occurred at the measurement required location, and if twist has occurred, correction work for eliminating the twist, for example, assisting means useful in controlling processing conditions; The present invention relates to a technique for controlling machining conditions using the support means.

Conventionally, in order to determine whether or not torsion has occurred at a point requiring measurement of a processed product, a press processing simulation of a processed material (metal plate material) using a computer is performed, and as shown in FIG. The shape when the internal stress acting on the processed product disappears from the mold (hereinafter referred to as “after springback” or “after SB”) and the ideal product to be finally obtained The shape, that is, the shape of the designed product (hereinafter referred to as “design shape”) is overlapped in the virtual space of the computer, and the inclination angle 21 of the linear portion of both shapes is measured to determine the occurrence of twist and twist. If there is, the twist direction and twist angle are obtained.
However, with such a means, a straight line portion does not always exist at a measurement-required location, and the determination means is uncertain.
In addition, as shown in FIG. 6, in the press working, when the processed product is taken out from the mold, elastic deformation, so-called spring back deformation occurs, so that the pressing operation into the mold is completed, and the processed product is removed from the mold. The shape when the internal stress is still acting on the processed product immediately before removal (hereinafter referred to as “before springback” or “before SB”) is different from the shape after SB.
For this reason, even if the data of the direction and angle of the twist to be eliminated as described above is obtained, the data cannot be a direct guide on how to control the processing conditions in order to eliminate the twist. As exemplified below, the control of the machining conditions has been repeated trial and error relying on experience and intuition.
When twisting occurs in a processed product, conventionally, correction work for eliminating the twisting has been performed by the following method.

[Method of controlling machining conditions]
This method is a correction method for eliminating the twist of the processed product by controlling the processing conditions, for example, the conditions for moving the processing material such as the drawing bead and the plate pressing force into the mold.
However, as described above, since there is no specific guideline for controlling the processing conditions, it has been repeated trial and error relying on experience and intuition.

[How to modify the mold]
This is a method for correcting the shape of a mold by making an angle in a direction opposite to the twist angle generated in the processed product (see JP-A-2001-252721).
However, this method also has the problem of the spring back deformation described above, so even if the shape of the same angle mold is corrected in the opposite direction to the generated twist angle, the generated twist cannot always be solved. The trial and error was repeated to finely adjust (change) the correction angle of the mold appropriately.
Furthermore, there is a problem that correction work for making an angle on the mold is difficult and the strength of the mold is insufficient.
JP 2001-252721 A Japanese Patent Application No. 2005-142116

[Problems of the Invention]
An object of the present invention is to improve the disadvantages of the above-described two conventional methods. More specifically, whether or not a twist is generated at a measurement target point of a processed product in a press processing simulation using a computer. If there is a twist, corrective work for eliminating the twist, for example, a specific numerical value that serves as a guideline for controlling the processing conditions is obtained by calculation, and a support means for the control is obtained. Providing and controlling processing conditions using the support means (specific numerical values).
In this way, it is possible to reliably determine whether or not torsion has occurred at the measurement required location, and when the torsion has occurred, correction work for eliminating the torsion, for example, when controlling processing conditions In addition, it is possible to improve drawbacks such as repeated trial and error relying on experience and intuition as in the conventional method, and difficult correction of mold shapes for which accuracy is not ensured.

[Configuration of the Invention]
In order to solve the above problems, the present invention pays attention to the fact that the cause of torsion is a part of internal stress (hereinafter referred to as “twist torque”) acting on the workpiece before SB, This is obtained by calculating a specific numerical value by a press working simulation using a computer to determine whether or not torsion has occurred at the point where measurement is required (no torsion when the torsion torque is zero), and torsion has occurred. If there is a correction work for eliminating the twist, for example, a twist correction support means used as a guideline for controlling the processing conditions, and using this support means, the processing conditions are set so as to eliminate the twist torque (to zero). It relates to means for controlling.
In the calculation, a relational expression T = (q × r) + (Q × r) −M is used.
Where T is the torsional torque, q is the in-plane shearing force, r is the distance from the center of the evaluation section line before SB to the evaluation point, Q is the shearing force in the thickness direction, and M is the torsional moment.
By the way, there are two reasons why the processed product after the SB is different from the design shape, that is, deformation of shape and occurrence of twist. However, the present invention is only for the latter, that is, the processed product is twisted to eliminate this. The invention relates to a correction technique, and does not deal with a correction technique for shape deformation.
For the technology for correcting the shape deformation, refer to Japanese Patent Application No. 2005-142116 filed earlier.

  FIG. 1 shows a procedure for determining whether or not torsion has occurred according to the present invention, a support procedure for controlling machining conditions to eliminate the twist when twist has occurred, and a control procedure for machining conditions using the assist procedure. Although the flow (procedure) is as shown, each procedure will be described in detail below.

1. Judgment direction setting procedure The procedure for setting the judgment direction in the direction (measurement required) where you want to judge the presence or absence of torsion of the workpiece.

2. Evaluation Section Line Setting Procedure An evaluation section line setting procedure for setting an evaluation section line V perpendicular to the determination direction of the processed product before SB as shown in FIG.
Note that the location to be set may be any as long as it is perpendicular to the determination direction.
Further, FIG. 3 shows only one evaluation cross section line V, but this is for the sake of simplification. In practice, the twist generated in the processed product gradually increases in the twist direction. In such cases, a plurality of evaluation cross section lines are set, and the torsion torque is calculated for each evaluation cross section line.
In addition, as a method of expressing the torsion torque of the entire workpiece, for example, a distribution graph in which the horizontal axis indicates the position of the cross section perpendicular to the torsion direction and the vertical axis indicates the torsion torque, or the torsion angle magnitude and torsion A three-dimensional graph or the like that indicates the direction of the object at the three-dimensional position of the processed product using the length and direction of the arrow may be considered.
In this way, it is possible to visually grasp the change in torsion torque of the entire processed product.

3. Evaluation Point Setting Procedure As shown in FIG. 4, the evaluation cross section line V is divided into m minute line segments, and a reference point for calculating the torsion torque for each minute line segment (hereinafter referred to as “evaluation point”). The evaluation point setting procedure for setting the center of each minute line segment, that is, the middle point.
The reason for dividing is that by dividing a complicated shape into minute line segments, individual calculations can be facilitated, and improvement in calculation accuracy can be expected.

4). Action force calculation procedure In the press processing simulation using a computer, press conditions such as mold shape, workpiece pressing force, counter force, mold movement amount, etc. are input, and the evaluation points shown in Fig. 5 For example, the torsional moment M acting on the evaluation point P along the 301 direction (the normal direction of the cross section where the evaluation cross section line V exists) and the in-plane along the 302 direction (the tangential direction of the evaluation cross section line V) A procedure for calculating the shearing force q and the shearing force Q in the plate thickness direction along the 303 direction (the direction obtained by the outer product of the unit vectors of the 301 direction axis and the 302 direction axis).
In the simulation, the acting forces q, Q, and M are calculated using an elastoplastic finite element method.
Note that the finite element method is a kind of approximate numerical solution method, in which the area of an object such as a plate material is broken down into individual elements whose mechanical behavior can be readily understood, and the entire assembly and behavior of each element is analyzed. This method is used in many fields in engineering simulation.
The elasto-plastic finite element method, which is one of the methods, is a method for solving elastic deformation and plastic deformation of an object at the same time, and is used for simulation related to plastic working of a metal plate material such as press working.
For details, refer to the aforementioned Japanese Patent Application No. 2005-142116.

5. Torsional axis setting procedure To determine the occurrence of torsion, it is sufficient to set the torsional direction (judgment direction), but this is not sufficient to calculate the torsional torque. It is necessary to set (specify) the "twist axis".
In general, when a workpiece is twisted, a force (twisting torque) that rotates along the central axis of the workpiece is generated, and as a result, twisting often occurs.
Therefore, in the present invention, a procedure is adopted in which an axis passing through the center of the evaluation section line V (hereinafter referred to as “centroid”) is set as a torsion axis.
The coordinate value of the centroid can be obtained by averaging the coordinate values of all the evaluation points.

6). Evaluation point torsion torque calculation procedure The distance r from the centroid C to the evaluation point P necessary for obtaining the torsion torque is calculated from the coordinate position of the centroid C and the evaluation point P, and the torsion torque T of the evaluation point P is calculated. Is an evaluation point torsion torque calculation procedure using the following equation (hereinafter referred to as “relational equation 1”).
T = (q × r) + (Q × r) −M
Where q is the in-plane shear force r is the distance from the centroid to the evaluation point Q is the shear force in the thickness direction M is the torsional moment

7). Overall Torsion Torque Calculation Procedure The torsional torque of the entire evaluation section line V is obtained by summing up the torsional torques at all the evaluation points calculated by performing the procedures in 4 to 6 above on all evaluation points on the evaluation section line V. Total torsion torque calculation procedure to calculate

8). Machining condition control procedure As described above, in order to correct the twist, the machining condition may be controlled so as to eliminate (set to zero) the twist torque T calculated in the preceding item 6 that is the cause of the twist. .
By the way, according to the relational expression 1, in order to eliminate the torsional torque T (set to zero), the sum of the in-plane shearing force q, the shearing force Q in the thickness direction, and the torsional moment MTS is eliminated (set to zero). It is only necessary to correct the machining conditions.
Since it is clear from experiments and the like that it is the in-plane shear force q that mainly controls the torsional torque T. Therefore, even if only the in-plane shear force q is eliminated (set to zero), a practical effect is obtained. Can be expected.
For example, in order to eliminate the in-plane shearing force q (set it to zero), the in-plane shearing force q should be changed directly using the balance between the in-plane shearing force q and the in-plane tension. In other words, it is conceivable to correct the in-plane tension that can be directly connected to the processing conditions so as to have a uniform distribution over the entire processed product before SB.
If the tension is in the in-plane direction, it can be directly reflected in the processing conditions such as squeeze bead and plate pressing pressure.

Procedure of the present invention Example of twist determination of a processed product after conventional SB Evaluation point on evaluation section line Evaluation cross section line for processed product before SB Definition of evaluation point torsion torque Molding simulation example

Explanation of symbols

V Evaluation section line k Fine line segment of reference section line P Evaluation point C Centroid of evaluation section line
T Torsion torque around torsion axis r Distance from evaluation point to centroid

Claims (4)

The torsional torque acting on the workpiece before spring-back is used to determine whether the workpiece has been twisted and, if twisting has occurred, to support the machining condition correction work to eliminate the twist. To calculate
A procedure for setting a determination direction in a direction in which it is desired to determine whether or not torsion of the processed product occurs,
An evaluation cross-section line setting procedure for setting at least one evaluation cross-section line V perpendicular to the determination direction of the processed product before springback;
An evaluation point setting procedure for dividing the evaluation section line V into minute line segments and setting an evaluation point serving as a reference when calculating the torsion torque T for each minute line segment;
An acting force calculation procedure for calculating an in-plane shearing force q acting on each evaluation point, a shearing force Q in the thickness direction, and a torsional moment M;
A torsional axis setting procedure for setting the torsional axis on which the torsional torque T acts as an axis passing through the center of the evaluation section line V;
An evaluation point torsion torque calculation procedure for calculating the torsion torque T of the evaluation point using the following equation;
T = (q × r) + (Q × r) −M
Where q is the in-plane shear force, r is the distance from the center of the evaluation section line to the evaluation point, Q is the shear force in the thickness direction, M is the torsional moment,
The torsional torques at all evaluation points calculated by performing the acting force calculation procedure, the torsion axis setting procedure, and the evaluation point torsion torque calculation procedure at all evaluation points on the evaluation section line V are summed up. And an overall torsion torque calculation procedure for calculating the torsion torque of the entire evaluation section line V,
Twist judgment and correction support program in press working to be executed by computer.   A twist determination in press working and a correction program for causing the computer to execute a processing condition control procedure for controlling the processing conditions so as to eliminate the twist torque obtained by the program in the program according to claim 1. The torsional torque acting on the workpiece before spring-back is used to determine whether the workpiece has been twisted and, if twisting has occurred, to support the machining condition correction work to eliminate the twist. To calculate
A procedure for setting a determination direction in a direction in which it is desired to determine whether or not torsion of the processed product occurs,
An evaluation cross-section line setting procedure for setting at least one evaluation cross-section line V perpendicular to the determination direction of the processed product before springback;
An evaluation point setting procedure for dividing the evaluation cross-section line V into minute line segments and setting an evaluation point serving as a reference for calculating the torsion torque T for each minute line segment at the center of each minute line segment;
In-plane shearing force q acting on each evaluation point, sheet thickness direction shearing force Q, and torsional moment M are used in the press processing simulation using a computer to determine the shape of the mold, work piece pressing force, counter force, die An action force calculation procedure to calculate by inputting press working conditions such as travel distance,
A torsion axis setting procedure for setting the torsion axis on which the torsion torque T acts on an axis passing through the center of the evaluation section line V obtained by averaging the coordinate values of all evaluation points;
An evaluation point torsion torque calculation procedure for calculating the torsion torque T of the evaluation point using the following equation;
T = (q × r) + (Q × r) −M
Where q is the in-plane shear force, r is the distance from the center of the evaluation section line to the evaluation point, Q is the shear force in the thickness direction, M is the torsional moment,
The torsional torques at all evaluation points calculated by performing the acting force calculation procedure, the torsion axis setting procedure, and the evaluation point torsion torque calculation procedure at all evaluation points on the evaluation section line V are summed up. , An overall torsion torque calculation procedure for calculating the torsion torque of the entire evaluation section line V;
A machining condition control procedure for controlling the machining conditions so as to eliminate the torsion torque obtained in the overall torsion torque calculation procedure,
Twist judgment and correction program in press working to be executed by computer. The torsional torque acting on the workpiece before spring-back is used to determine whether the workpiece has been twisted and, if twisting has occurred, to support the machining condition correction work to eliminate the twist. To calculate
Setting a determination direction in a direction in which it is desired to determine whether or not torsion of the processed product has occurred; and
An evaluation cross-section line setting step for setting at least one evaluation cross-section line V perpendicular to the determination direction of the processed product before the spring back;
An evaluation point setting step of dividing the evaluation cross section line V into minute line segments and setting an evaluation point serving as a reference for calculating the torsion torque T for each minute line segment;
An acting force calculating step for calculating an in-plane shearing force q acting on each evaluation point, a shearing force Q in the thickness direction, and a torsional moment M;
A torsional axis setting step for setting the torsional axis on which the torsional torque T acts as an axis passing through the center of the evaluation section line V; and an evaluation point torsion for calculating the torsional torque T at the evaluation point using the following equation: Torque calculation procedure,
T = (q × r) + (Q × r) −M
Where q is the in-plane shear force, r is the distance from the center of the evaluation section line to the evaluation point, Q is the shear force in the thickness direction, M is the torsional moment,
Summing the torsion torques at all evaluation points calculated by performing the acting force calculation step, the torsion axis setting step, and the evaluation point torsion torque calculation step at all evaluation points on the evaluation section line V A torsion determination and a correction support method for press working in which a whole torsion torque calculating step for calculating the torsion torque of the entire evaluation section line V is performed using a computer.

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