Method for evaluating crotchiness, crotchiness evaluation apparatus, program, and method for manufacturing panel parts

Abstract

By simple forming analysis, it is possible to evaluate the warpage of the panel part before assembly to other parts. This is a warpage evaluation method for evaluating the warpage of a panel part before assembly, which is formed by press-forming a plate material into a three-dimensional shape, by forming analysis using a computer. A press-forming analysis step (20A) of performing a press-forming analysis with the plate material as the panel part and obtaining the shape of the panel after demolding as the reference panel shape (10), and a self-weight analysis is performed on the reference panel shape (10) under the condition that the panel part is placed on a flat surface, and a self-weight analysis step (20B) of obtaining the deformed panel shape after self-weight as the evaluation panel shape (11), and a warpage evaluation step (20C) of evaluating the warpage of the panel part of the evaluation panel shape (11).

Description

Technical Field

[0001] The present invention relates to a technique for evaluating the presence or absence of warping that occurs before assembling a panel part formed by press-molding a plate material into a three-dimensional shape to other parts by means of forming analysis using a computer. The forming analysis using a computer is hereinafter also referred to as CAE analysis. Here, the panel parts targeted by the present invention are not limited to automotive parts. The present invention can be applied to any panel part manufactured by press-molding a plate material into a three-dimensional shape. Further, the material of the panel part is not limited to steel materials. The present invention is also applicable to panel parts made of ferroalloys such as stainless steel, and further non-ferrous materials and non-metallic materials.

Background Art

[0002] As a conventional warping analysis method, for example, there is the method described in Patent Document 1. The method described in Patent Document 1 obtains a tension rigidity distribution by applying a load to the evaluation panel toward the back side. Then, from the tension rigidity distribution, the warping position on the panel surface is specified. Further, Patent Document 1 describes that when predicting the rigidity during transportation of a panel part, the warping position is estimated based on the product shape. Further, it is described that thereby, it is possible to predict whether warping occurs when gripping and transporting the panel surface by an adsorption means.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Before assembly, the panel component may experience rattling during transportation or the like. When rattling occurs in the panel component, there is a risk that plastic deformation (permanent strain) will occur in the panel component. If plastic deformation occurs, the panel component will not meet the surface accuracy as a product, and it will be necessary to dispose of the panel component, such as by discarding it. However, in Patent Document 1, the panel shape for predicting rattling is the product shape or the panel shape after springback. In Patent Document 1, the panel shape for predicting rattling is the panel shape of the panel component during transportation by the suction means.

[0005] However, as a result of the inventor's study, the following findings were obtained regarding the occurrence of rattling in thin panel components. The above-mentioned thin panel components are, for example, panel components with a length × width size exceeding 1000 mm × 1000 mm or panel components with a plate thickness of 1.5 mm or less. That is, it was found that the rattling analysis results in the product shape and the rattling analysis results in the panel shape after springback based on the press forming analysis may be different from the actual rattling situation occurring in the panel components at the site. Regarding the actual panel shapes immediately before transportation, measuring and evaluating them individually at the storage location or the like immediately before transportation makes the rattling evaluation itself complicated.

[0006] The present invention focuses on the above points and aims to enable the evaluation of rattling of the panel component before assembly by simple forming analysis.

Means for Solving the Problems

[0007] In order to solve the problem, one aspect of the present invention is a warpage evaluation method for evaluating the warpage of a panel part formed by press-forming a plate material before assembling it to other parts by using computer-aided forming analysis, the method comprising: a press-forming analysis step of performing a press-forming analysis using the plate material as the panel part and obtaining the shape of the panel after mold release as the reference panel shape; a self-weight analysis step of performing a self-weight analysis on the reference panel shape under the condition that the panel part is placed on a flat surface and obtaining the shape of the panel after deformation due to self-weight as the evaluation panel shape; and a warpage evaluation step of evaluating the warpage of the panel part having the evaluation panel shape.

Advantages of the Invention

[0008] According to an aspect of the present invention, by simply adding a self-weight analysis, it becomes possible to evaluate the warpage of the panel part before assembly in advance and easily by CAE analysis using a computer. Note that the warpage evaluation in this specification is evaluated, for example, by applying a load from the back side to the front side. The load for evaluation may be applied from the front side to the back side. Here, if the warpage situation of the actual panel part after pressing before assembly cannot be reproduced by CAE analysis, there are the following problems. That is, when it is estimated that warpage occurs, it is necessary to change the panel shape by taking measures such as shape imparting at the estimated position. However, conventionally, it cannot be easily determined whether the warpage is actually suppressed with the panel shape after the change. In this case, there is a risk of repeating mold modification and press forming, resulting in large losses of cost and time. On the other hand, according to an aspect of the present invention, such a situation can be solved.

Brief Description of the Drawings

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Mode for Carrying Out the Invention

[0010] Next, embodiments of the present invention will be described with reference to the drawings. Here, the presence or absence of warping in the actual panel parts after pressing is confirmed on the jig or at the place where the panel parts after pressing are assembled. The inventor has discovered that the evaluation of warping at the site of the panel before assembling the panel parts to other parts is different from the warping evaluation for the shape after springback calculated by CAE analysis. As a result of repeated examinations, the following findings were obtained. That is, in the case of a large panel part made of thin material, the panel part bends due to its own weight before assembly. This indicates that it is necessary to evaluate the panel shape considering the bending effect due to its own weight with respect to the panel shape after springback calculated by CAE analysis. The above-mentioned large panel part made of thin material is a panel part whose vertical × horizontal size exceeds 1000 mm × 1000 mm, or a panel part whose plate thickness is 1.5 mm or less.

[0011] Based on such findings, in the present embodiment, it was considered to perform warping analysis by CAE analysis on the panel shape considering the influence of its own weight. The present embodiment enables accurate determination of warping in the panel parts before assembly by such warping analysis. Further, in the present embodiment, since only a self-weight analysis is added, it can be easily evaluated by a forming analysis using a computer. Note that the evaluation of warping in the panel parts after assembly is performed assuming, for example, pressing in a state where the outer periphery is restrained. On the other hand, the evaluation of warping in the panel parts before assembly is performed assuming, for example, vibration input during conveyance in a state where the outer periphery is unrestrained.

[0012] (Warping evaluation device 1) The warping evaluation device 1 of the present embodiment is a device for evaluating warping in a panel part formed by press-forming a plate material into a three-dimensional shape before assembly. The warping evaluation device 1 of the present embodiment evaluates warping before assembly by a forming analysis using a computer. Therefore, the processing of the warping evaluation device 1 can be configured as a program executed by a computer. As shown in Fig. 1, the beak evaluation device 1 of this embodiment includes a press forming analysis unit 2, an evaluation panel shape determination unit 3, and a beak evaluation unit 4. Further, the beak evaluation device 1 may include a panel shape changing unit 6 shown in Fig. 1.

[0013] <Press forming analysis unit 2> The press forming analysis unit 2 constitutes a press forming analysis step. The press forming analysis unit 2 acquires information on the plate material to be evaluated and the press conditions for press forming. The press conditions are conditions such as the target part shape and the press forming method. Then, the press forming analysis unit 2 performs a press forming analysis of press forming with the set die model using the blank model of the plate material to be evaluated. And the shape of the press formed product after mold release is taken as the reference panel shape 10.

[0014] The set die model is set based on the forming surface shape of the actual die that press forms a blank made of a plate material into the target part shape by a known method. For example, a die model having a shape following the target part shape is taken as the set die model. However, a die model corrected by the amount of springback after mold release is preferably used as the set die model. The above press forming analysis includes two analyses. The two analyses are an analysis for obtaining the panel shape at the forming bottom dead center in press forming and an analysis for obtaining the shape after mold release, that is, after springback.

[0015] Press forming analysis is usually performed by CAE analysis such as the finite element method (FEM). Therefore, the above press forming analysis may be performed by structural analysis using a computer, for example, known CAE analysis. The reference panel shape 10 after mold release has a change amount due to mold release from the forming bottom dead center. The change amount is obtained by press forming analysis. Here, applicable press forming methods in this example include foam forming and draw forming. The present invention can be applied to any press forming method.

[0016] <Evaluation panel shape determination unit 3> The evaluation panel shape determination unit 3 is a processing unit that determines the evaluation panel shape 11. The evaluation panel shape 11 is a panel shape for evaluating warping. As shown in FIG. 2, the evaluation panel shape determination unit 3 includes a dimension evaluation unit 3A and a shape modification unit 3C.

[0017] [Dimension evaluation unit 3A] The dimension evaluation unit 3A includes a first determination unit 3Aa and a second determination unit 3Ab. The first determination unit 3Aa determines whether the dimensions of the reference panel shape 10 obtained by the press forming analysis unit 2 are 1000 mm × 1000 mm or more in plan view. Further, the second determination unit 3Ab determines whether the plate thickness of the reference panel shape 10 is 1.5 mm or less. If the dimension evaluation unit 3A does not satisfy the determination by the first determination unit 3Aa or the determination by the second determination unit 3Ab, it proceeds to the shape setting unit 3B. In the shape setting unit 3B, the reference panel shape 10 obtained by the press forming analysis unit 2 is set as the evaluation panel shape 11 for evaluating warping. Then, the shape setting unit 3B ends the processing of the evaluation panel shape determination unit 3. On the other hand, if the dimension evaluation unit 3A satisfies the above determination, it proceeds to the shape modification unit 3C.

[0018] [Shape modification unit 3C] The shape modification unit 3C includes a self-weight analysis unit 3Ca and an evaluation panel setting unit 3Cb. The self-weight analysis unit 3Ca performs a self-weight analysis on the panel part model of the reference panel shape 10 obtained by the press forming analysis unit 2. Then, by this self-weight analysis, the self-weight analysis unit 3Ca obtains the panel shape after deformation generated by the load of the self-weight. The self-weight analysis unit 3Ca constitutes a self-weight analysis step. Note that a known analysis method may be adopted for the self-weight analysis.

[0019] The self-weight analysis of this embodiment executes the analysis of applying self-weight to the panel parts of the reference panel shape 10 under the following conditions. The conditions are that without restraining the outer periphery of the panel parts, and as shown in FIG. 5, the panel parts of the reference panel shape 10 are placed on a flat and rigid placement surface 30. Under this condition, the panel parts will not deform downward any further by contacting the placement surface 30. The panel parts of the reference panel shape 10 are panel parts with large dimensions or thin plate panel parts. Therefore, depending on the three-dimensional shape formed by press forming, deformation will occur in the panel parts. Usually, in a plan view, the central part side of the panel shape is more likely to deform downward. The evaluation panel setting unit 3Cb sets the panel shape after deformation in the process of the self-weight analysis unit 3Ca as the evaluation panel shape 11.

[0020] <Buckling evaluation unit 4> The buckling evaluation unit 4 constitutes a buckling evaluation step. The buckling evaluation unit 4 evaluates buckling for the panel parts of the evaluation panel shape 11. For the evaluation method of buckling, a known analysis method may be applied. The processes for the evaluation of buckling are, for example, the process of confirming the presence or absence of buckling and the process of estimating the buckling position. In normal buckling evaluation, a load is applied from the front surface to the back surface of the panel part. Then, buckling analysis is performed based on the displacement information of the panel surface due to the load. The buckling evaluation of this embodiment may be implemented by applying a load from the front surface to the back surface of the panel. However, in this embodiment, the panel shape to be evaluated is the panel shape with a load applied from the front surface side to the back surface side in the self-weight analysis. Therefore, in this embodiment, a case where buckling analysis is performed under the condition of applying a load from the back surface side to the front surface side of the panel is taken as an example.

[0021] However, for example, when it is determined by self-weight analysis that there is a portion that bulges toward the front surface due to deformation of the panel shape, it is preferable to proceed as follows. That is, it is preferable to perform buckling analysis by applying a load from the front surface side to the back surface side of the panel at least to the bulging portion and its vicinity. In this case, buckling analysis is performed by applying a load from the front surface side to the back surface side of the panel. Also, the load application direction may be changed for each region of the panel. Further, it is also possible to perform an evaluation of applying a load from the back surface side to the front surface side and an evaluation of applying a load from the front surface side to the back surface side to the same part.

[0022] The buckling evaluation unit 4 of the present embodiment performs a process of estimating the buckling position for a panel component composed of the evaluation panel shape 11. As shown in FIG. 1, the buckling evaluation unit 4 of the present embodiment includes a tension rigidity strength distribution acquisition unit 4A and a buckling position evaluation unit 4B. In the present embodiment, the case where the buckling evaluation described in Patent Document 1 is adopted is exemplified. However, the point that the load application direction is from the back surface side is different.

[0023] [Tension rigidity strength distribution acquisition unit 4A] The tension rigidity strength distribution acquisition unit 4A performs a process of applying a load from the back surface to the front surface of the panel to the load application position preset on the panel surface for the evaluation panel shape 11. With that load, the panel surface is displaced by a preset displacement amount toward the front surface side. Then, the tension rigidity strength distribution acquisition unit 4A performs a process of obtaining the distribution of the tension rigidity along the panel surface generated thereby. As the above-mentioned preset displacement amount, a displacement amount of two levels or more is set. And the tension rigidity strength distribution acquisition unit 4A obtains the distribution of the tension rigidity along the panel surface for each set displacement amount. That is, a plurality of distributions of the tension rigidity along the panel surface are obtained. The tension rigidity strength distribution acquisition unit 4A obtains the above-mentioned distribution of the tension rigidity (tension rigidity strength distribution) by a load application simulation.

[0024] The load simulation is carried out, for example, under the condition of restraining the outer periphery of the panel part of the evaluation panel shape 11. For example, the panel surface is divided into a plurality of regions (nodes), and the reaction force (load) in each region generated by applying a load to the load application point is calculated by simulation. Then, the reaction force (load) in each region is obtained as the distribution of the tension rigidity (tension rigidity strength distribution) along the panel surface. Further, from the distribution of the tension rigidity (tension rigidity strength distribution) of a plurality of layers according to a plurality of displacement amounts, the load-displacement curve (load distribution) in each region (node) is obtained. The load application position is set at the position where the tension rigidity is estimated to be the weakest in the evaluation panel shape 11. For example, the load application position is set as the load application point within the central part of the panel surface. The central part of the panel surface includes, for example, the center point (e.g., the centroid point) of the panel, and is within the region with a radius of 10 mm from the center point.

[0025] Also, as the displacement amount of the panel at the load application point position, for example, two or more displacement amounts selected from the range of 10 mm or more and 40 mm or less are set. Then, for each level of the displacement amount, a simulation for obtaining the distribution of the tension rigidity is carried out. It is preferable that the number of levels of the displacement amount set is 3 or more. Here, the reason for setting the displacement amount in the range of 10 mm or more and 40 mm or less is as follows. That is, it is for the purpose of evaluating the rattling that will occur due to the pushing-in that causes displacement in this range. There is no problem in setting the level of the displacement amount to 10 levels or less, preferably 5 levels or less.

[0026] [Rattling Position Evaluation Unit 4B] The rattling position evaluation unit 4B determines the presence or absence of the rattling position based on the distributions of a plurality of tension rigidities obtained by the tension rigidity strength distribution acquisition unit 4A. When there is rattling, the rattling position is determined. Here, since the central part of the panel is the farthest from the restraint points on the panel periphery, it is estimated that the rigidity is the weakest. The buckling position evaluation unit 4B determines whether there is a region with a lower load than the central part of the panel from the strength of the load distribution (tension rigidity distribution) generated by loading the central part of the panel. Note that a region with a lower load than the central part of the panel is defined as a low-load region. And when it is determined that such a low-load region exists, that low-load region is determined as a buckling position with a high risk of buckling occurrence.

[0027] Alternatively, the buckling position evaluation unit 4B may determine a position where there is a temporary decrease in the load as the buckling position as the displacement increases at the load application position. Here, when a load is applied to the central part of the panel where the tension rigidity is estimated to be weak, nodes of deflection occur during the load application due to the propagation of the tension along the surface caused by the load application. Those nodes move along the surface. When that node is located in the low-load region, the movement of the node becomes easy, and it is estimated that buckling is likely to occur. That is, in the present embodiment, for the evaluation position, a portion where the load decreases as the displacement increases in the load-displacement curve (load distribution) is determined as the buckling position (low-load region). Alternatively, in the present embodiment, a region with a lower load than the central part of the panel where the tension rigidity is estimated to be weak is determined as the buckling position. On the other hand, when there is no such low-load region, it is determined that there is no buckling position in the panel component.

[0028] Through the above processing, the buckling evaluation unit 4 determines the presence or absence of a buckling position. Also, when there is buckling, the buckling position (low-load region) is obtained. When the third determination unit 5 determines that there is buckling based on the processing of the buckling evaluation unit 4, it proceeds to the panel shape changing unit 6. On the other hand, when the third determination unit 5 determines that there is no buckling position in the panel component, it ends the processing and, for example, sets the panel shape as the target component shape.

[0029] <Panel shape changing unit 6> When it is determined that there is a "buckle position", the panel shape changing unit 6 performs processing. The panel shape changing unit 6 changes the evaluation panel shape 11 so that the rigidity before assembling the panel becomes high. As a measure for changing the evaluation panel shape 11 so that the rigidity of the panel becomes high, for example, measures described in known methods, previously published patent gazettes, published gazettes, etc. are taken. For example, as a measure for increasing the rigidity, changing the panel curvature, attaching a reinforcing sheet, and imparting a shape such as a bead can be exemplified. Here, if it is the design stage of the part, the panel shape itself may be changed. The design stage of the part refers to, for example, the point in time when there is no mold yet. If it is the prototype stage, the mold can be adjusted to a mold corresponding to the changed panel shape. The adjustment of the mold is, for example, the adjustment of the expected mold shape. After the panel shape is changed by the panel shape changing unit 6, the above-mentioned respective processes are executed again to evaluate the buckling of the panel shape after the change again. Then, until it is determined that there is no buckling position and the panel rigidity before assembly is high, the above-mentioned process is repeated.

[0030] (Program 20) The buckling evaluation device 1 of the present embodiment is configured as a program 20 as shown in FIG. 3. This program 20 can be executed by the CPU of a computer. The program 20 shown in FIG. 3 is a program for evaluating the buckling before assembling a panel part to other parts by forming analysis. The above-mentioned panel part is, for example, a panel part manufactured by press-forming a plate material into a three-dimensional shape. This program 20 includes a press forming analysis step 20A, a self-weight analysis step 20B, and a buckling evaluation step 20C.

[0031] The press forming analysis step 20A is a step of performing press forming analysis of press forming with a plate material as a target panel part. Further, from the analysis, it is a step of executing a process of obtaining the panel part after mold release as the reference panel shape 10. The self-weight analysis step 20B is a step of performing a self-weight analysis on the reference panel shape 10 under the condition that the panel component is placed on a flat surface. Further, from the analysis, a process of obtaining the panel shape after deformation due to self-weight as the evaluation panel shape 11 is executed. The warping evaluation step 20C is a step of executing a process of evaluating the warping of the panel component of the evaluation panel shape 11.

[0032] (Manufacturing method of panel component) The manufacturing method of the panel component of the present embodiment manufactures the panel component by a process as shown in FIG. 12, for example, and conveys the manufactured panel component to the next process or the like. The manufacturing method of the panel component of the present embodiment includes a warping evaluation step S30 and a panel component manufacturing step S32.

[0033] <Warping evaluation step S30> The warping evaluation step S30 may be executed by, for example, the above-described warping evaluation device 1. The warping evaluation step S30 first performs a warping evaluation on the panel component of the target component shape to be targeted by the warping evaluation method described above. In the evaluation of the warping, when it is evaluated that warping occurs, the target component shape is changed so that the warping is eliminated. Then, the change of the target component shape and the evaluation of the warping are repeated until it is determined that warping does not occur. When it is determined in the above warping evaluation that warping does not occur, the process proceeds to the panel component manufacturing step S32.

[0034] <Panel component manufacturing step S32> In the panel component manufacturing step S32, the plate material is press-formed to manufacture the panel component so as to have the finally determined target component shape. As the press-forming method, a known method may be adopted.

[0035] <Conveying step S34> The manufactured panel parts are conveyed to a warehouse or the next process by conveying means. The panel parts conveyed to the warehouse are temporarily placed and stored on the floor of the warehouse or on a pallet. Then, the panel parts are conveyed to the next process by the conveying means as needed. The conveying means grips and conveys the surface of the panel parts by, for example, suction or magnetic attachment.

[0036] <Assembly process S36> In the next process, the panel parts are assembled to other parts. The panel parts are, for example, parts such as the outer panel of a car door, a bonnet, and a roof. In the manufacturing method of the panel parts of the present embodiment, the panel parts are manufactured in a shape that does not cause rattling during the conveyance of the panel parts or the like. For this reason, the accuracy of the product is improved. Also, the yield is improved.

[0037] <Function and others> Conventionally, rattling problems occurred after prototyping, and die modifications were carried out through trial and error. In contrast, in the present embodiment, the presence or absence of rattling is examined in simulation. By this, in the present embodiment, it is possible to suppress the occurrence of defects at the evaluation stage using the actual product and contribute to reducing the development man-hour loss.

[0038] The present embodiment evaluates, for example, press-formed panels with a large area and thin plates, typified by outer panels such as the roof, hood, and door of an automobile. With this evaluation, it is possible to predict in advance the occurrence of distortion (permanent deformation) due to rattling of the panel parts, which is likely to occur in the conveyance process in press forming. And it becomes possible to establish countermeasures for this. Thus, in the present embodiment, for example, it is possible to detect the risk of rattling before prototyping an actual vehicle. As a result, it is possible to minimize the losses in development and production preparation.

[0039] That is, according to this embodiment, it is possible to easily predict the warping of the panel. Therefore, at the vehicle development stage, it is not always necessary to actually prototype the vehicle for the warping evaluation. And from the information on the panel shape of the product, it is possible to easily predict whether warping of the panel will occur during conveyance after press working or the like. That is, at the component design stage, it becomes possible to consider countermeasures against warping before assembly, such as during conveyance. As a result, in this embodiment, for example, losses in new vehicle development can be reduced, and efficient development and production can be achieved without reducing the production speed even in mass production.

Example

[0040] Next, an example of this embodiment will be described. FIG. 4 shows the panel shape of the actual panel component to be evaluated in this example. The target panel component shown in FIG. 4 has a thin plate thickness of 1.2 mm. Also, the size of the panel component is 1400 × 1100 mm. That is, the panel component in this example is a large component with one side exceeding 1000 m. When holding such a large panel component by hand, if the rigidity of the component is low, the component itself will bend. The panel component in this example is made of a steel material with a material strength of 270 MPa.

[0041] First, a model of a flat plate material (blank) made of a steel material with a plate thickness of 1.2 mm and a material strength of 270 MPa was generated. Press forming analysis for press forming the blank model of the plate material into the target panel shape was performed by FEM analysis. In this example, the target panel shape was set to the shape shown in FIG. 1. And from that analysis, a component model of the reference panel shape 10 was obtained. The reference panel shape 10 is the panel shape after demolding, that is, the panel shape after springback. Next, a self-weight analysis was performed on the obtained component model of the reference panel shape 10 to obtain a component model of the evaluation panel shape 11. The evaluation panel shape 11 consists of the panel shape deformed by its own weight.

[0042] As shown in Fig. 5, the self-weight analysis was performed under the condition that the panel component was placed on the flat and rigid placement surface 30 without restraining the outer periphery of the panel component. At this time, in order to simulate that the part that has dropped due to its own weight comes into contact with the placement surface 30 and the part will not drop any further, the placement surface 30 is regarded as a rigid body. The self-weight analysis in this example is a shape analysis that simulates the state of placing the panel component on the placement surface 30 composed of a plane simulating the ground. And it is a shape analysis that allows the component itself to flex until it naturally touches the plane placement surface 30. Here, for a thin and large panel component, the component itself is prone to flexure. Therefore, when actually checking the presence or absence of rattling by tactile inspection, the check is performed at the inspection table or the component assembly position. Therefore, the influence of its own weight on the panel component cannot be avoided. In addition, when performing this self-weight analysis on the panel component, it often drops around the center of the component.

[0043] Next, the analysis of the rattling evaluation will be described. Here, Fig. 6 shows the displacement application position F1, and the evaluation points P1 and P2 in the rattling analysis.

[0044] <Regarding the evaluation point P1> First, the evaluation point P1 was evaluated. Here, the rattling analysis was performed under the following conditions (1) to (3). (1) The entire circumference of the panel outer periphery is constrained in the pressing direction at a pitch of 100 mm along the circumferential direction. (2) The panel is displaced 40 mm from the back to the front (from bottom to top in Fig. 6) at the displacement application position F1. And the displacement of the evaluation point P1 in the pressing direction associated with the displacement at the displacement application position F1 is obtained. (3) Then, the displacement in the pressing direction and the acceleration (second derivative) of the displacement are evaluated. Rattling can be detected by the acceleration. That is, when rattling occurs, the speed changes rapidly in the pressing direction or the reverse direction along with the displacement at the displacement application position F1. And the rattling can be quantitatively detected by this change. However, the presence or absence of unevenness can be determined only from the information on the displacement in the pressing direction in (2).

[0045] Figure 7 shows an example of a press shape for evaluating unevenness. As shown in Figure 7(a), in the actual part shape, the central part of the part has sunk due to the influence of its own weight. The actual part shape shows the amount of variation when the panel part of the product is placed on the floor. On the other hand, in the reference panel shape 10 after springback obtained by performing forming analysis with CAE (see Figure 7(b)), there is no sinking in the central part of the part. On the other hand, it was found that the evaluation panel shape 11 (see Figure 7(c)) obtained by performing self-weight analysis reproduced the actual part shape (see Figure 7(a)) well.

[0046] Figure 8 shows the results of unevenness analysis at the evaluation point P1 for each panel shape. Figure 8(a) shows the CAE analysis results for the panel shape of the product shape. Figure 8(b) shows the analysis results when an actual displacement is loaded on the displacement application position F1 in the actual part. The actual part is the panel part in the state where the panel part of the product shape is actually placed on the floor. The panel shape at this time is also called the actual part shape. Figure 8(c) shows the CAE analysis results for the reference panel shape 10 after springback that simulates the product shape. Figure 8(d) shows the CAE analysis results for the evaluation panel shape 11 after self-weight analysis. The analysis results in Figure 8 are expressed by the displacement and acceleration data of the evaluation point P1. The horizontal axis is the amount of displacement applied to the displacement application position F1. The vertical axis shows the amount of displacement and acceleration of the evaluation point P1 at that time. Also, except for the actual part shape, they are obtained by CAE analysis.

[0047] The following was found from Figure 8. In the panel shape of the product shape shown in Figure 4, there is no sinking in the central part in the CAE analysis, and as can be seen from Figure 8(a), there is no unevenness at the evaluation point P1. The absence of unevenness means that, as shown in Figure 8(a), the displacement and acceleration at the evaluation point change proportionally with respect to the applied displacement amount. As can be seen from FIG. 8(c), even in the reference panel shape 10 after springback, there was no rattling at the evaluation point P1 as well.

[0048] On the other hand, in the actual part shape, when the panel part is placed on the floor, for example, there is also a depression in the central part of the part. And as shown in FIG. 8(b), when a displacement of about 15 mm was applied, the displacement amount and acceleration at the evaluation point P1 changed rapidly. That is, rattling occurred. Also, the CAE analysis for the evaluation panel shape 11 (also in FIG. 8(d)) was in the same form as the depression in the central part of the actual part. That is, in the evaluation panel shape 11, when a displacement of about 15 mm was applied from the rattling analysis as in the actual part, the displacement amount and acceleration of the evaluation point changed rapidly. That is, rattling occurred.

[0049] Next, from the results of FIG. 8, in order to suppress rattling, beads 14A were provided. The improved panel shape 14 is shown in FIG. 9. Regarding the improved panel shape 14 shown in this FIG. 9, the rattling of the evaluation panel shape 11 after the self-weight analysis was evaluated. From this evaluation, it was evaluated that the depression in the central part of the part was suppressed and there was no rattling at the evaluation point P1. When the actual part of the improved panel shape was placed on the floor and the rattling was evaluated with a finger, no rattling occurred at the evaluation point P1. That is, the countermeasure and its effect were confirmed.

[0050] <Regarding the evaluation point P2> Next, without changing the displacement application position F1, the same evaluation was performed with the evaluation point as P2. The evaluation point P2 is the position shown in FIG. 6. FIG. 10 shows the rattling evaluation results at the evaluation point P2. As can be seen from FIG. 10, even when the evaluation point was changed from P1 to P2, the same results as above were obtained. FIG. 10(a) is the CAE analysis result in the panel shape of the product shape. Figure 10(b) shows the analysis result when displacement is actually applied to the displacement application position F1 on the actual part. The actual part is a panel part in a state where a panel part having a product shape is actually placed on the floor. The panel shape at this time is also referred to as the actual part shape. Figure 10(c) shows the CAE analysis result for the reference panel shape 10 after springback simulating the product shape. Figure 10(d) shows the CAE analysis result for the evaluation panel shape 11 after self-weight analysis.

[0051] That is, as can be seen from Figure 10(a), when the panel shape was used to evaluate the product shape, in the CAE analysis, it was evaluated that there was no depression in the central part and no warping. On the other hand, in the actual part shape, there is a depression in the central part of the part due to being placed on the floor. And as shown in Figure 10(b), when a displacement of about 15 mm was applied, the displacement amount and acceleration at the evaluation point P2 changed rapidly. That is, warping occurred. Also in the CAE analysis, in the result of the evaluation panel shape 11 with self-weight analysis applied, it has the same form as the depression in the central part of the actual part. Therefore, from the warping analysis shown in Figure 10(d), when a displacement of about 15 mm was applied as in the actual part, the displacement amount and acceleration at the evaluation point changed rapidly. That is, warping occurred. In contrast, for the reference panel shape 10 after springback, the following determination was made. That is, as shown in Figure 10(c), at the evaluation point P2, it was determined that there was no warping.

[0052] Next, in order to suppress warping at the evaluation point P2, a bead 15A was provided. The improved panel shape is shown in Figure 11. Regarding the evaluation panel after self-weight analysis, with the improved panel shape 15 shown in Figure 11 as the reference panel shape 10, warping analysis was performed. In that warping analysis, it was determined that there was no warping at the evaluation point 2. Also, the actual part was placed on the floor from the improved panel shape 15 and warping at the evaluation point P2 was evaluated. From this evaluation, warping did not occur, and the countermeasure against warping and its effect were confirmed.

[0053] (Others) The present disclosure may also have the following configurations. (1) Disclosure 1 is a warpage evaluation method for evaluating warpage of a panel part formed by press-forming a plate material before assembly to other parts by forming analysis using a computer, a press-forming analysis step of performing a press-forming analysis using the plate material as the panel part and obtaining the panel shape after demolding as the reference panel shape; a self-weight analysis step of performing a self-weight analysis on the reference panel shape under the condition of placing the panel part on a flat surface and obtaining the panel shape after deformation due to self-weight as the evaluation panel shape; a warpage evaluation step of evaluating the warpage of the panel part having the evaluation panel shape; A warpage evaluation method comprising the above steps. (2) Disclosure 2 is that in the above warpage evaluation step, the distribution of tensile stiffness along the panel surface generated by displacing the panel surface from the back side to the front side by applying a load to the set load application position is obtained multiple times by changing the displacement amount due to the application of the load, and the warpage position on the panel surface is estimated from the obtained multiple distributions of tensile stiffness. (3) Disclosure 3 is to evaluate a panel part having a size in a plan view of longitudinal × lateral = 1000 × 1000 mm or more. (4) Disclosure 4 is to evaluate a panel part having a plate thickness of 1.5 mm or less. (5) Disclosure 5 is that the above press forming is foam forming or draw forming. (6) Disclosure 6 is a warpage evaluation device for evaluating warpage of a panel part formed by press-forming a plate material before assembly to other parts by forming analysis using a computer, a press-forming analysis unit that performs a press-forming analysis using the plate material as the panel part and obtains the panel shape after demolding as the reference panel shape; a self-weight analysis unit that performs a self-weight analysis on the reference panel shape under the condition of placing the panel part on a flat surface and obtains the panel shape after deformation due to self-weight as the evaluation panel shape; a warpage evaluation unit that evaluates the warpage of the panel part having the evaluation panel shape; A warpage evaluation device comprising... (7) Disclosure 7 is a program for evaluating warpage before assembling a panel part formed by press - molding a plate material onto other parts by means of forming analysis, a press - forming analysis step of performing press - forming analysis with the plate material as the panel part and obtaining the panel part after demolding as the reference panel shape; a self - weight analysis step of performing self - weight analysis on the reference panel shape under the condition of placing the panel part on a flat surface and obtaining the panel shape after deformation due to self - weight as the evaluation panel shape; a warpage evaluation step of evaluating the warpage of the panel part with the evaluation panel shape; a program for causing a computer to execute. (8) Disclosure 8 is a method for manufacturing a panel part by press - molding a plate material into a target part shape to manufacture the panel part, before press - molding, for the target part shape of the panel part, evaluating by the warpage evaluation method described in any one of Disclosures 1 to 5, and if it is determined in the evaluation that warpage occurs, changing the target part shape to a shape capable of suppressing the occurrence of warpage. A method for manufacturing a panel part.

[0054] Here, the entire contents of Japanese Patent Application No. 2024 - 080361 (filed on May 16, 2024), for which this application claims priority, are incorporated herein by reference in part. Here, although the description has been made with reference to a limited number of embodiments, the scope of rights is not limited thereto, and modifications of each embodiment based on the above disclosure are obvious to those skilled in the art.

Explanation of Reference Numerals

[0055] 1 Warpage evaluation device 2 Press - forming analysis unit 3 Evaluation panel shape determination unit 3A Dimension evaluation unit 3B Shape setting unit 3C Shape change unit 3Ca Self - weight analysis unit 3Cb Evaluation panel setting unit 4 Slack Evaluation Unit 4A Tensile Rigidity Strength Distribution Acquisition Unit 4B Slack Position Evaluation Unit 6 Panel Shape Change Unit 10 Reference Panel Shape 11 Evaluation Panel Shape 20 Program 20A Press Forming Analysis Step 20B Self-Weight Analysis Step 20C Slack Evaluation Step 30 Placing Surface F1 Displacement Application Position P1, P2 Evaluation Points

Claims

1. A method for evaluating dents in a panel part formed by press-molding a plate material before assembly to another part, by forming analysis using a computer, comprising: a press molding analysis step of performing a press molding analysis on the plate material as the panel part, and acquiring a panel shape after demolding as a reference panel shape; a weight analysis step of performing a weight analysis on the reference panel shape under a condition that the panel component is placed on a flat surface, and acquiring a panel shape after deformation due to the weight as an evaluation panel shape; a dent evaluation step for evaluating dents of a panel part having the above-mentioned evaluation panel shape; A method for evaluating the bekkotskii.

2. The dent evaluation step involves applying a load to a set load application position to displace the panel surface from the back side to the front side, thereby obtaining a distribution of tension stiffness along the panel surface multiple times by changing the amount of displacement caused by the load application, and estimating the dent position on the panel surface from the obtained distribution of tension stiffness. The method for evaluating the appearance of burrs according to claim 1.

3. The evaluation targets panel components with dimensions in plan view of 1000 x 1000 mm or more. The method for evaluating the appearance of burrs according to claim 1.

4. The evaluation targets panel parts with a thickness of 1.5 mm or less. The method for evaluating the appearance of burrs according to claim 1.

5. The press molding is form molding or draw molding. The method for evaluating the appearance of burrs according to claim 1.

6. A dent evaluation device that evaluates dents of a panel part formed by press-molding a plate material before assembly to another part by forming analysis using a computer, a press molding analysis unit that performs a press molding analysis on the plate material as the panel part and obtains a panel shape after demolding as a reference panel shape; a weight analysis unit that performs a weight analysis on the reference panel shape under a condition that the panel component is placed on a flat surface, and obtains the panel shape after deformation due to the weight as an evaluation panel shape; a dent evaluation unit for evaluating dents of a panel part having the evaluation panel shape; A bekkotsuki evaluation device comprising:

7. A program for evaluating the cracks of a panel part formed by press molding a plate material before assembly to another part by molding analysis, a press molding analysis step of performing a press molding analysis on the plate material as the panel part, and acquiring the panel part after demolding as a reference panel shape; a weight analysis step of performing a weight analysis on the reference panel shape under a condition that the panel component is placed on a flat surface, and acquiring a panel shape after deformation due to the weight as an evaluation panel shape; a dent evaluation step for evaluating dents of a panel part having the above-mentioned evaluation panel shape; A program for causing a computer to execute the above.

8. A method for manufacturing a panel part by press-molding a plate material into a target part shape, comprising the steps of: Before press molding, the target part shape of the panel part is evaluated by the dent evaluation method described in any one of claims 1 to 5, and if it is determined that dents will occur in the evaluation, the target part shape is changed to a shape that can suppress the occurrence of the dents. Manufacturing method of panel parts.

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