JP2005138119A - Method for simulating sheet forming - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make the solution of the shape of goods formed of plates possible using FEM with high accuracy and efficiently. <P>SOLUTION: The deflection distribution of a die corresponding to a forming stroke is determined in steps (a) to (c). In step (d-1), the deflection distribution is applied to the nodes on the surface of the die as the conditions of forced displacement when simulating plate formation by a dynamic explicit method. In step (d-2), the simulation of plate formation taking account of the deflection distribution which is accurately determined is performed. Furthermore, in step (d-3), the conditions of forced displacement are corrected until a forming load obtained in step (d-2) coincides with a desired forming load. That is, by performing the comparison and verification of the target value and calculated value of forming load and performing the simulation of the plate formation under the conditions of ideal forming load, the shape of the goods formed of the plate is simulated with high accuracy. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for solving a shape of a plate molded product with high accuracy and efficiency using a finite element method (hereinafter referred to as “FEM”).

Conventionally, poor shape accuracy due to springback of a molded product has been a chronic problem that has had a serious adverse effect on mold correction man-hours and production preparation lead time. It can be directly applied to complex shapes such as parts, and its application is expected. However, many of the previous examples that compared the predicted shape of the springback with FEM and the experimental results were limited to two-dimensional shapes, so the establishment of a technology that can predict springback with high accuracy in three-dimensional or complex shapes has been established. It was desired.
Therefore, plate forming is a shell element (in the case of simulation analysis, if the thickness of the material can be analyzed from the relationship between the size of the structure and the thickness of the material, the structure is divided into thin plates. Modeling with a solid element (in the simulation analysis, the structure is divided into vertical, horizontal, and height directions to express and analyze the mechanical changes of each rectangular parallelepiped. However, this is called a solid element), and a method of solving it at the same time is considered (for example, see Non-Patent Document 1).
Moreover, the method of solving the same subject by the static dissolution method is also invented (for example, refer nonpatent literature 2).

Hideo Sasamori, 5 others, "Application to 3D model (4th report on springback prediction by FEM)", The Japan Society for Technology of Plasticity, Proceedings of the 2001 Spring Seminar on Plasticity, p. 7-8 Masato Takamura and 4 others, “Sheet Forming Simulation Considering Elastic Die Deformation by Static Analysis FEM”, The Japan Society for Technology of Plasticity, Proc. 11-12

However, all the conventional simulation methods have the following drawbacks. In other words, even with complicated contact analysis such as press molding, if a dynamic explicit method that is robust to contact problems is used, the mold model is modeled with solid elements, and sheet molding simulation is performed simultaneously while considering deflection. It is possible to do.
Here, the dynamic explicit method is a method for handling a dynamic problem such as collision and vibration, and is a method for solving a dynamic balance using a virtual work principle formula including an acceleration term. This dynamic explicit method can be applied to the press molding simulation because the calculation at each time increment step (in the finite element simulation, the die is advanced little by little) is fast.
However, as a drawback, since the solution varies with time, there is a feature that it is not suitable for the calculation of the springback to solve the static balance. Moreover, in the case of the dynamic explicit method, it is necessary to reproduce in detail the finite element of the die dial part that is important in plate molding. Therefore, the size must be 1/10 to 1/20 or less. Then, from the characteristics of the dynamic explicit method, the time increment step is proportional to the minimum size of elements of all models except the rigid body (effective length of finite element), so compared with the mold model when assuming a rigid body, The time increment step becomes extremely small. Furthermore, since it is necessary to calculate a large number of mold solid elements, for example, when comparing large press products such as body panels of automobile parts, it becomes an unrealistic calculation time. As a result, the simulation method is not practical.

  The present invention has been made in view of the above problems, and the object of the present invention is to make it possible to solve the shape of a plate molded product with high accuracy and efficiency using FEM, and to achieve a spring back of the plate molded product. For example, it is to reliably avoid a shape accuracy defect.

  In order to solve the above problems, a plate forming simulation method according to claim 1 of the present invention includes a step of obtaining a deflection distribution of a mold according to a forming stroke, and the bending distribution is determined by a plate forming simulation by a dynamic explicit method. The step of performing the plate forming simulation is given to the nodes on the mold surface at the time of performing the step, and the correction of the forced displacement condition is performed until the forming load obtained thereby matches the desired forming load. And performing steps.

In the present invention, in the step of obtaining the deflection distribution of the mold according to the molding stroke, the deflection distribution is accurately obtained. As such a technique, a simulation or a measuring device with high accuracy can be used.
Then, the deflection distribution is given as a forced displacement condition for the nodes on the mold surface when performing the plate forming simulation by the dynamic explicit method, and in the step of performing the plate forming simulation, the accurately obtained deflection distribution is taken into consideration. Perform plate forming simulation.
Further, in the step of correcting the forced displacement condition until the molding load obtained thereby coincides with the desired molding load, the target value of the molding load is compared with the calculated value, and the ideal molding load is verified. By performing plate forming simulation under conditions, the shape of the plate formed product can be simulated.

  In addition, a plate forming simulation method according to claim 2 of the present invention for solving the above-described problem includes a step of obtaining a deflection distribution of a portion to which a wrinkle restraining load of a mold is applied according to a molding stroke, and the corresponding deflection A portion excluding the step of applying the wrinkle suppression load to the node of the surface of the portion to which the wrinkle suppression load is applied when performing plate forming simulation by the dynamic explicit method, and the portion of the mold that provides the wrinkle suppression load Is assumed to be a rigid body, and a desired forming load is applied to perform a plate forming simulation.

In the present invention, in the step of obtaining the deflection distribution of the mold according to the molding stroke, the deflection distribution is accurately obtained. As such a technique, a simulation or a measuring device with high accuracy can be used.
Then, in the step of performing the plate forming simulation, the deflection equivalent is given as a forced displacement condition to the surface node of the portion to which the wrinkle restraining load is applied when performing the plate forming simulation by the dynamic explicit method. A plate forming simulation is performed in consideration of the obtained deflection distribution. Here, since the part excluding the part to which the wrinkle restraining load is applied is assumed to be a rigid body, it is not necessary to compare and verify the molding load target value and the calculated value.

  Since the present invention is configured as described above, the shape of the plate molded product can be solved with high accuracy and efficiency using the FEM, and it is possible to reliably avoid poor shape accuracy such as a springback of the plate molded product. Can do.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
In the embodiment of the present invention, the mold deflection distribution during press molding is obtained by the steps shown in FIGS. Specifically, it is as follows.
(A) Step: Assuming that the mold is a rigid body, only the mold surface is modeled as a shell element, and a plate forming simulation is performed by a dynamic explicit method.
(B) Step: For the die rigidity simulation by the static implicit method performed in the subsequent (c) step, the die is assumed to be an elastic body and is modeled as a solid element. a) Inserting / extracting (fitting) the nodal reaction force of the mold mesh obtained in the plate forming simulation of the step.
(C) Step: Actually, mold rigidity simulation is performed by a static implicit method.

  Furthermore, in the embodiment of the present invention, the die deflection distribution during press molding obtained by the simulation performed along the steps (a) to (c) is used as the step (d) or the step (e). This makes it possible to perform a simulation that takes into account the mold deflection during press molding.

FIG. 2 shows an example of a plate forming simulation method in consideration of mold deflection during press forming. First, in accordance with the procedure shown in steps (a) to (c) of FIG. 1, a mold deflection distribution corresponding to the molding stroke is obtained by simulation. At this time, the mold deflection is obtained as a function of the position and time of the mold. It is also possible to obtain a mold deflection distribution by measurement by a method described later.
(D-1) Step: (a) to (c) Steps (a) to (c) The deflection distribution of the mold obtained by the simulation method is used as a node on the mold surface when performing plate forming simulation by the dynamic explicit method. On the other hand, it is given as a forced displacement condition (mapped to a plate forming mesh). The amount of forced displacement at this time is usually 0.3 to in the case of a press mold for automobile panels. It is about 4 mm.
(D-2) Step: Actually, a plate forming simulation is performed by a dynamic explicit method.

(D-3) Step: As a result of the plate forming simulation performed in the (d-2) step, the required forming load is checked. Specifically, as shown in FIG. 3, a target molding load T (obtained by calculation when the mold is assumed to be a rigid body) necessary to obtain a desired product shape, and (d-1). ) Based on the deflection distribution (forced displacement) of the mold given in the step, the calculated value C of the molding load obtained in the step (d-2) is compared and verified. As shown in FIG. 3, when the calculated value C is smaller than the target molding load T, the displacement amount of the entire mold is changed without changing the deflection distribution of the mold (the upper and lower molds are made closer). ). Then, returning to the step (d-2), the plate forming simulation is performed again by the dynamic explicit method. The loop of step (d-2) and step (d-3) is repeated until the calculated value C reaches the target molding load T.
(D-4) Step: When it is confirmed in step (d-3) that the calculated value C matches the target molding load T, a simulation result of the product shape during press molding is output. What is obtained as an output includes, for example, the thickness distribution of the press-formed product, the amount of spring back, and the like. These output values are highly accurate in consideration of mold deflection during press molding.

  On the other hand, FIG. 4 shows another example of the simulation method in consideration of the mold deflection during press molding. First, in the same way as the simulation method shown in FIG. 2, the die deflection distribution corresponding to the molding stroke is obtained by simulation according to the procedure shown in steps (a) to (c) of FIG. 1. It is also possible to obtain a mold deflection distribution by measurement by a method described later.

(E-1) Step: A portion to which a wrinkle-suppressing load is applied when a plate forming simulation is performed by a dynamic explicit method on a deflection distribution of a mold obtained by a simulation method using steps (a) to (c) as an example. (This part is a cushion ring in the case of a single action press and corresponds to a blank holder in the case of a double action press). ).
(E-2) Step: Excluding the part that gives the wrinkle suppression load of the mold (in the case of a single action press, the upper mold corresponds, and in the case of a double action press, the upper and lower molds correspond). Assuming a rigid body, a desired forming load is applied and the plate forming simulation is performed. In this case, since the portion excluding the portion to which the wrinkle restraining load is applied is assumed to be a rigid body, the molding load target value and the calculated value always coincide with each other. It is not necessary to check the molding load as in steps 2) and (d-3).
(E-3) Step: Output the simulation result of the product shape during press molding. What is obtained as an output is the same as step (d-4) in FIG.

Each of the above simulations can be performed using an electronic computer such as a personal computer. Then, according to the simulation method of the mold deflection distribution during press molding shown in FIG. 1, in the step (a), assuming that the mold is a rigid body, only the mold surface is modeled as a shell element, and the dynamic explicit method is used. A plate forming simulation is performed. This step does not calculate a large number of mold solid elements, so the advantage of the dynamic explicit method is that the calculation at each time increment step is fast and the calculation of the plate forming simulation in a short time. Can be terminated.
In the subsequent step (b), for the die rigidity simulation by the static implicit method performed in the step (c), the die is assumed to be an elastic body and is modeled as a solid element, and the plate is placed at the node position of the model. Insert and extrapolate the nodal reaction force of the mold mesh obtained during the molding simulation.
That is, in the plate forming simulation by the dynamic explicit method and the die rigidity simulation by the static implicit method, the positions of the nodes constituting each element are naturally different, and thus obtained by the plate forming simulation in (a) step. The reaction force at each node (node reaction force) composing the mesh of the plate molded product is inserted / extracted (fitted) at each node position of the mold modeled as a solid element assuming an elastic body. is there. The internal / extrapolation work can be performed by a general processing procedure in simulation.

In step (c), a die rigidity simulation is performed by a static implicit method on the die modeled as a solid element.
Here, since the static implicit method is a time integration method that repeatedly calculates to satisfy the stress balance at the end of the time increment step by the finite element method, the calculation result for each time increment can be obtained accurately. It becomes possible. In addition, since the relationship between the plate material being molded and each part of the mold may be considered to be in a condition in which they are always in contact with each other or are always separated from each other, the mold and the plate are in one time increment step. In the case where the contact state changes, the troubles unique to the static implicit method such that the calculation does not converge to the balanced state does not occur.
And, by accurately obtaining the static implicit method at each time increment step, which is far less than the dynamic explicit method, as a feature of the static implicit method, the mold deflection distribution during press molding is highly accurate and efficient. Can be solved.

In addition, in step (c), the surface pressure distribution acting on the mold surface obtained in step (a) is obtained as a function of time, the state of the mold mounting portion, and the cushion load as boundary conditions. By doing so, the deflection distribution of the mold during press molding can be solved with high accuracy and efficiency.
In addition, the method for obtaining the die deflection distribution during press molding is not limited to the simulation method shown in FIG. 1, and it is also possible to use the following measuring apparatus and measuring method.

  FIG. 5 shows a cross-sectional view of a press die 1 incorporating a measuring device for the amount of die displacement during press molding. A press machine 50 (see FIG. 12) on which the press mold 1 is mounted is a mechanical press machine using a link mechanism as a propulsion device for an upper mold ram. The mechanical press machine generates a necessary punch load by applying a driving amount equal to or greater than a dimensional value to the upper mold during press molding and applying pressure to the mold 1 while bending the press machine 50 itself.

The measuring apparatus according to the embodiment of the present invention detects displacement amounts detecting means 2, 3, 4, 5 that detect a displacement amount between specific parts of a die, which are built in the press die 1, and detect a punch load. Load detecting means 6 for detecting the load.
The displacement detection means 2, 3, and 4 are all constituted by eddy current sensors. Among these, the displacement amount detection means 2 is between a cushion ring 9 supported so as to be movable in the vertical direction with respect to the lower mold 7 via a slide guide 8 and a punch 10 fixed to the lower mold 7. It measures the distance in the horizontal direction. The eddy current sensor according to the displacement detection means 2 uses the appropriate vertical surface 10a of the punch 10 as a sensing surface, and the main body of the eddy current sensor maintains a posture facing the vertical surface 10a even during press molding. Moreover, it is firmly fixed to the cushion ring 9 via a bracket.

Further, the displacement amount detection means 3 measures the vertical distance between the cushion ring 9 and the upper mold 11. The eddy current sensor according to the displacement amount detecting means 3 uses an appropriate horizontal surface 11a of the upper die 11 as a sensing surface, and the main body of the eddy current sensor maintains a posture facing the horizontal surface 11a even during press molding. , And is firmly fixed to the cushion ring 9 via a bracket.
Further, the displacement amount detection means 4 measures the displacement amount between the appropriate vertical end surface 11b of the upper die 11 and the appropriate vertical surface 7a of the lower die 7. In the illustrated example, the vertical surface 7a is supported by a member 12 fixed to the lower mold 7 (in FIG. 5, for convenience of illustration, it is illustrated as being separated from the mold 7). The surface of the component 13 is selected as the vertical surface 7a as the sensing surface. The main body of the eddy current sensor according to the displacement amount detecting means 4 is firmly fixed to the vertical end surface 11a of the upper mold via the bracket so as to maintain the posture facing the vertical surface 7a even during press molding. .
The eddy current sensors used in these displacement amount detection means 2, 3, and 4 have a measurement range of about 5 mm and a resolution of about 2 μm, and are suitable for precise measurement of the displacement amount of each part. Moreover, since the eddy current sensor is a small sensor of about φ20 mm × 20 mm, it is suitable for mounting inside the mold.
Other non-contact type sensors can be used as long as they have the same performance as the eddy current sensor and can obtain output such as voltage so that measurement results during press molding can be obtained continuously. Etc. can also be used.

On the other hand, the displacement amount detection means 5 is constituted by a laser sensor, and measures the displacement amount between the upper die 11 and the upper surface 10b of the punch 10. The main body of the laser sensor is fixed in the vicinity of the mounting surface of the upper die 11 with respect to the ram 51 (see FIG. 12), and the die 14 forming a part of the upper die 11 has an opening 15 for allowing the laser beam L to pass therethrough. Is formed. In the panel, an opening for allowing the laser beam L to pass through is formed in advance. The laser sensor used for the displacement detection means 5 has a measurement range of about 500 mm and a resolution of about 50 μm, and is suitable for precise measurement of the displacement of the above part. Any other non-contact type laser sensor can be used as long as it has the same performance and can obtain output such as voltage so that measurement results during press molding can be continuously obtained. It is also possible to use a sensor or the like.
Moreover, the load detection means 6 is comprised with the load cell, and measures a punch load. The main body portion of the load cell is fixed to the lower mold 7 and supports a punch 10 separate from the lower mold 7 from below. Further, the punch 10 is supported by a guide similar to a slide plate, thereby preventing punch misalignment when a load is applied.

These displacement amount detection means 2, 3, 4, 5 and the load detection means 6 are provided at a predetermined interval at a plurality of locations on the mold 1. In FIG. 5, for the sake of illustration, the displacement amount detection means 4, 5 are shown one by one, but actually, the displacement amount detection means 4, 5 are also one in the same manner as the displacement amount detection means 2. Two are provided on one cross section. Each sensor is provided so that its position is slightly shifted so that the mutual magnetic fields do not interfere with each other.
Then, the measurement results (measurement voltages) of the displacement detection means 2, 3, 4, 5 and the load detection means 6 are passed through the amplifier 17 schematically shown in FIG. 5 and via the analog-digital data converter 18. Then, it is processed by the processing device 19 such as a personal computer, and can be displayed by the display means 20 such as a display or a printer, if necessary.

  Furthermore, an opening for inserting a shim is formed at an appropriate position of the lower mold 7 between the bottom surface of the cushion ring 9 and the plane of the lower mold 7 facing the bottom surface for the reason described later. Yes. In addition, the contact surface (machined surface) of the shim is formed on the bottom surface of the cushion ring 9 and the plane of the lower mold 7 facing it. About the structure of the other part about the metal mold | die 1, since it is the same as that of the conventional metal mold | die, detailed description is abbreviate | omitted.

Here, the procedure for measuring the displacement amount between specific parts of the press mold 1 during the press molding operation using the apparatus for measuring the mold displacement amount during press molding according to the embodiment of the present invention is shown in FIG. The description will be given with reference.
(1) Determine the measurement conditions.
(i) Step: Calculation of punch load necessary for press forming Designed dead center when mold 1 is assumed to be a rigid body by forming simulation or geometric calculation. The punch load (desired punch load) is obtained.
(ii) Step: Determining the actual die height Necessary for obtaining a desired punch load by repeatedly performing test hitting while actually measuring the punch load by the load detecting means 6 so that the punch load calculated in (i) above is obtained. Determine the actual die height.

(2) Zero point adjustment of the displacement detection means 2, 3, 4, 5 is performed.
(i) Step: Determine no-load die height.
In a state where the material is not set in the mold and the cushion pin 16 (FIG. 5) is not applied with the cushion load to the cushion ring 9, the cushion ring 9 is lowered by its own weight. The upper die 11 is lowered while actually measuring the punch load by the load detecting means 6. Then, the die height at which the punch load starts to be actually generated is grasped. This unloaded die height is obtained by adding the initial plate thickness to the die height at which punch load actually starts to be generated.
(ii) Step: Subsequently, a load is applied to the cushion pin 16 to raise the cushion ring 9, and a gap is formed between the lower surface of the cushion ring 9 and the plane of the lower mold 7 facing the lower surface.
(iii) Step: The shim is inserted from the opening formed in the lower die 7 into the contact surface of the shim formed between the bottom surface of the cushion ring 9 and the flat surface of the lower die 11 facing the bottom surface. The shim used at this time is held in a position corresponding to the bottom dead center at the time of press working with the cushion ring 9 lowered by its own weight and sandwiched between the lower ring 11 and the upper surface of the cushion ring 9. The thickness is as large as possible.

(iv) Step: Remove the load of the cushion pin 16, lower the cushion ring 9, and bite the shim between the bottom surface of the cushion ring 9 and the lower mold plane facing the bottom surface. In this state, the cushion ring 9 is held at a position corresponding to the bottom dead center at the time of pressing without applying a load of the cushion pin 16.
(v) Step: By lowering the upper die 11 to the no-load die height determined in the above (2) (i) step, the cushion ring and the upper die are placed at the bottom dead center in the no-load state, and punched. In addition, a space corresponding to the plate thickness is provided between the cushion ring and the upper mold.
(vi) Step: Zero point adjustment of the displacement detection means 2, 3, 4, 5 is performed in the state of step (2) (v).

(3) The displacement amount of each part of the mold is measured.
(i) Step: The shims used in the above steps (2) (iii) to (vi) are removed from the mold.
(ii) Step: Press molding is performed with the actual die height determined in the above step (1) (ii). Then, during the press molding, the displacement amount of each part of the mold is measured by the displacement amount detection means 2, 3, 4, 5.
(4) Output the measurement result.
Panel forming is performed, and the change in the clearance between the cushion ring 9 and the vertical surface 10a of the punch during press molding can be detected over time from the measurement result of the displacement detection means 2.
Further, the change in the clearance between the cushion ring 9 and the upper die 11 during press molding can be detected over time from the measurement result of the displacement amount detection means 3.
Furthermore, the change in the opening amount of the upper die 11 during press molding can be detected over time from the measurement result of the displacement amount detection means 4.
In addition, the displacement detection means 5 detects the displacement between the upper mold 11 and the punch upper surface 10b at a plurality of locations, measures the displacement of each part of the mold, and determines the overall deflection of the mold 1 over time. Can be detected.
Then, the measurement result can be processed by the processing device 19, displayed as a graph on the display means 20, or printed out by a printer if necessary.

FIGS. 8 to 11 show examples of measurement results obtained by the measuring device for the amount of mold displacement during press molding according to the embodiment of the present invention. In this measurement example, the displacement detection means 2, 3, 4,... On the vertical cross section through the lines (constant pitch) indicated by the symbols AA, BB, CC, DD in FIG. 5 is arranged.
FIG. 8 shows the opening amount of the cushion ring 9 detected by the displacement amount detection means 2 over time. Since each of the measurement positions A, B, C, and D is provided with two displacement amount detection means 2, the detection result of each measurement position in FIG. 8 is the average value of the measurement results of the two detection means. Represents. In the figure, a line indicated by reference sign Bh indicates a blank hold time point, and a line indicated by reference sign Bdc indicates the bottom dead center of the upper die 11 and the cushion ring 9 (the same applies to FIG. 9).
FIG. 5 shows the clearance of the wrinkle suppressing surface detected by the displacement amount detection means 3 over time. In FIG. 5, the measurement results of the two displacement amount detection means 3 at the measurement positions A, B, C, and D are separately shown as A1, A2, B1, B2, C1, C2, D1, and D2.

Further, FIG. 10 shows the deflection of the upper die 11 at the bottom dead center detected by the displacement amount detecting means 5 (value based on the punch upper surface 10b).
FIG. 11 shows the relationship between the deflection of the upper die 11 at the bottom dead center detected by the displacement detection means 5 and the punch load measured by the load detection means 6.
Note that, as shown in FIG. 12, the above measurement results show that the pressure F of the propulsion device against the ram 51 that drives the upper die 11 in the state where the lower die 7 and the upper die 11 are mounted on the press machine 50, It was measured under conditions that act outside the lower mold 7 and the upper mold 11.

Here, it is as follows when the effect obtained by embodiment of this invention which makes the said structure is put together.
That is, in the simulation method shown in FIG. 2, the deflection distribution is accurately obtained in the step of obtaining the deflection distribution of the mold according to the molding stroke. As the method, a simulation in which high accuracy is guaranteed, such as steps (a) to (c) in FIG. 1, or the measuring apparatus described with reference to FIGS.
Then, in step (d-1), the deflection distribution is given as a forced displacement condition to the nodes on the mold surface when performing plate forming simulation by the dynamic explicit method, and is accurately obtained in step (d-2). A plate forming simulation considering the deflection distribution is performed.
Further, in step (d-3), the forced displacement condition is corrected until the molding load obtained in step (d-2) matches the desired molding load. That is, as shown in FIG. 3, the target value T of the molding load and the calculated value C are compared and verified, and by performing a plate molding simulation under ideal molding load conditions, the shape of the plate molded product is increased. It is possible to simulate with accuracy.

In the simulation method shown in FIG. 4, in the step of obtaining the deflection distribution of the mold corresponding to the molding stroke, the deflection distribution is accurately obtained in the same manner as in the example of FIG.
Then, in step (e-1), the deflection equivalent is given as a forced displacement condition to a node on the surface of the portion to which the wrinkle suppression load is applied when performing plate forming simulation by the dynamic explicit method. 2) In the step, a plate forming simulation is performed in consideration of the accurately obtained deflection distribution. Here, since the part excluding the part to which the wrinkle restraining load is applied is assumed to be a rigid body, the comparison and verification of the target value T of the molding load and the calculated value C are as shown in the example of FIG. It is unnecessary. Therefore, the shape of the plate molded product can be simulated with high accuracy also by the method of FIG.

It is a flowchart which shows the simulation method of the deflection distribution of the metal mold | die during press molding based on embodiment of this invention. It is a flowchart which shows the simulation method of the plate shaping | molding which considered the metal mold | die bending in the press molding based on embodiment of this invention. FIG. 3 is a graph comparing a target forming load required to obtain a desired product shape with a calculated value C of a forming load obtained in a plate forming simulation process shown in FIG. 2. It is a flowchart which shows another example of the simulation method of the plate shaping | molding which considered the metal mold | die bending in press molding based on embodiment of this invention. It is sectional drawing of the press die incorporating the measuring device of the amount of metallic mold displacement during press molding concerning an embodiment of the invention. It is a disassembled perspective view of the press die incorporating the measuring device of the die displacement amount during press molding shown in FIG. It is a flowchart which shows the procedure which measures the displacement amount between the specific parts of the press die in press molding operation | work using the measuring device of the die displacement amount in press molding shown in FIG. It is the graph which showed the opening amount of the cushion ring in press molding of the press die incorporating the measuring device of the die displacement amount in press molding shown in Drawing 5 with time. It is the graph which showed the clearance of the wrinkle suppression surface in press molding of the press die incorporating the measuring device of the amount of metallic mold displacement in press molding shown in Drawing 5 with time. It is the figure which showed the deflection | deviation of the upper mold | type in a bottom dead center of the press die incorporating the measuring device of the die displacement amount in press molding shown in FIG. FIG. 6 is a diagram showing the relationship between the deflection of the upper die at the bottom dead center and the punch load measured by the load detection means of the press die incorporating the device for measuring the amount of die displacement during press molding shown in FIG. is there. It is a schematic diagram which shows the press machine which mounts | wears with the press die shown in FIG.

Explanation of symbols

(A) to (c): Step of obtaining a mold deflection distribution according to a molding stroke by simulation (d-1): A mold method obtained by a simulation method using steps (a) to (c) as an example. The deflection distribution is given as a forced displacement condition for the nodes on the mold surface when performing plate forming simulation by the dynamic explicit method (mapped to the plate forming mesh) Step (d-2): Actually dynamic Step of performing plate forming simulation by explicit method (d-3): Step of checking required forming load as a result of plate forming simulation performed in step (d-2) (d-4): In step (d-3) The step of outputting the simulation result of the product shape during press forming when it is confirmed that the calculated value matches the target forming load e-1): (a) to (c) The surface of the portion to which the wrinkle-suppressing load is applied when performing the plate forming simulation by the dynamic explicit method on the deflection distribution of the mold obtained by the simulation method taking steps as an example. Step (e-2): Assuming that the portion excluding the portion to which the wrinkle-suppressing load is applied is a rigid body, is formed as a desired displacement condition. A step of applying a load and performing the plate forming simulation (e-3): a step of outputting a simulation result of the product shape during press forming

Claims (2)

Determining the mold deflection distribution according to the molding stroke;
Giving the deflection distribution as a forced displacement condition to the nodes on the mold surface when performing plate forming simulation by dynamic explicit method, and performing the plate forming simulation;
A plate forming simulation method comprising the step of correcting the forced displacement condition until a forming load obtained thereby coincides with a desired forming load. Obtaining a deflection distribution of a portion to which a wrinkle restraining load of the mold is applied according to a molding stroke;
The step of giving the deflection equivalent as a forced displacement condition to the node of the surface of the portion to which the wrinkle restraining load is applied when performing plate forming simulation by dynamic explicit method,
A plate forming simulation method comprising the steps of applying a desired forming load assuming that a portion excluding the portion to which the wrinkle suppressing load is applied is a rigid body, and performing the plate forming simulation.

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