JP6149843B2 - Method and apparatus for analyzing shape correction of press-formed product, and method for correcting shape of press-formed product - Google Patents

Description

  The present invention secures the shape stability of mass-produced press-molded products, and can easily correct the shape of the press-molded product. It relates to the correction method.

  In press molding, at the stage of releasing the press-molded product from the mold, a shape return called spring back occurs according to the residual stress distribution at the bottom dead center of the mold, and the shape as the mold (shape freezing) This will cause defective shape freezing.

  For example, when a press-molded product that is curved in the longitudinal direction is manufactured by press molding, when the press-molded product is released, a shape such as a spring near the end of the press-molded product and / or a twist in the longitudinal direction is caused by a springback. Freezing failure occurs.

  The springback becomes larger as the strength of the blank material to be processed is higher and the Young's modulus of the blank material is lower, and in producing a press-molded product with high dimensional accuracy, the shape freezing failure due to the springback is extremely large. It is an obstacle.

  As a method for overcoming the shape freezing failure due to springback, for example, Patent Document 1 specifies a position where deformation occurs in a press-molded product based on the shape of the press-molded product after press molding, and the deformation mode at the generated position. Accordingly, a press forming method is disclosed in which the deformation history in the press forming process is controlled in order to level the residual stress distribution at the generation position.

JP 2009-255106 A

  In Patent Document 1, the in-plane deformation history of the plate-like member is controlled so as to equalize the distribution of residual stress at the occurrence position according to the deformation mode at the occurrence position of the deformation. As a control method, compressive stress is applied to a site where elongation occurs, and tensile stress is applied to a site where shrinkage occurs. However, it is unclear how to apply compressive stress and tensile stress, and when mass-producing press-molded products, the effect of suppressing the shape change of press-molded products due to variations in processing conditions is expected. Therefore, a sufficient effect cannot be expected to ensure the shape stability of the press-formed product.

  The present invention has been made to solve such a problem, and in order to ensure the shape stability of mass-produced products by suppressing variations in the press-formed products when performing many press moldings with the same mold. It is an object of the present invention to provide a method and apparatus for analyzing the shape of a press-molded product that can easily correct the shape of the press-molded product by the method, and a method for correcting the shape of a press-molded product.

(1) The shape correction analysis method for a press-formed product according to the present invention is a method in which the computer performs the following steps. The residual stress before release of the press-formed product is determined by press forming analysis. A springback factor region specifying step for specifying in which region of the press-molded product a factor causing a springback, and the shape after the springback obtained based on the residual stress before the mold release An indenter indentation analysis step for performing springback analysis after the indenter is pushed and deformed by changing the indenter indentation part and the amount of indentation with respect to the area identified by the springback factor area identification step, and the indenter indentation By comparing the shape after indentation indentation obtained in the analysis process with the target shape of the press-formed product, it is effective for shape correction. The site and pushing the push-in amount of the indenter have a shape correction condition determining step of determining that,
In the indenter indentation analysis step, when compressive stress remains in the region specified in the springback factor region specifying step, the portion in the region is pressed with an indenter and specified in the springback factor region specifying step. If a tensile stress remains in the region, the portion in the region is pushed with an indenter, and then the portion opposite the pushing surface is pushed against the portion with the indenter in the direction opposite to the pushing direction. It is characterized by.

(2) In the above-described (1), in the springback factor region specifying step, the residual stress of a partial region of the press-formed product is set to 0, or the residual stress value of the partial region is set. Either the process is performed, or the residual stress difference before and after the mold release in the partial region is changed.

( 3 ) A method for correcting the shape of a press-formed product according to the present invention is a method for correcting the shape of a press-formed actual part using the method for analyzing the shape correction of a press-formed product according to (1) or (2) above. Press forming step of forming an actual press molded part by performing press molding using a mold corresponding to the mold model used in the press molding analysis of (1) or (2) above, and the press after release A shape correction step of correcting the shape of the press-formed actual part by pressing the indenter at the indentation site and the amount of the indenter obtained in the shape correction condition determining step with respect to the molded actual part. It is characterized by this.

( 4 ) The press-molded product shape correction analysis apparatus according to the present invention obtains a residual stress before release of the press-molded product by press molding analysis, and the residual stress that causes a springback is the press An area specified by the springback factor area specifying means for specifying in which area of the molded product, and the springback factor area specifying means in the shape after the springback obtained based on the residual stress before the mold release On the other hand, an indenter indentation analyzing means for performing a springback analysis after the indenter is pushed and deformed by changing the indentation part and the amount of indentation, and a shape after the indenter is obtained by the indenter indentation analyzing means And the indented part and the amount of indentation, which are effective for shape correction by comparing the target shape of the press-formed product Possess and determination to shape correction condition determining means,
When the compressive stress remains in the area specified by the springback factor area specifying means, the indenter indentation analysis means presses a part in the area with the indenter and specifies by the springback factor area specifying means If a tensile stress remains in the region, the portion in the region is pushed with an indenter, and then the portion opposite the pushing surface is pushed against the portion with the indenter in the direction opposite to the pushing direction. It is characterized by.

( 5 ) In the above-mentioned ( 4 ), the springback factor area specifying means sets the residual stress of a partial area of the press-molded product to 0 or sets the residual stress value of the partial area to 0. Either the process is performed, or the residual stress difference before and after the mold release in the partial region is changed.

  In the present invention, the residual stress before release of the press-molded product is obtained by press-molding analysis, and the region of the press-molded product where the residual stress causes the springback is specified. For the region specified by the springback factor region specifying step and the springback factor region specifying step in the shape after the springback obtained based on the residual stress before the mold release, the indentation portion and the pressing amount of the indenter are set. The indenter indentation analysis step for performing the springback analysis after the indenter is changed and deformed, and the shape after the indenter obtained in the indenter indentation analysis step is compared with the target shape of the press-molded product. And a shape correction condition determining step for determining the indentation portion and the amount of the indenter effective for shape correction. Rukoto makes it possible to easily correct the shape of the press-molded product in a simple manner, it is possible to ensure the shape stability of the press-molded product of mass production.

It is a block diagram of the shape correction analysis apparatus of the press-formed product which concerns on one embodiment of this invention. It is explanatory drawing of the press-formed product made into object by embodiment of this invention. It is explanatory drawing of the definition of the springback amount which concerns on embodiment of this invention. It is explanatory drawing of the identification method of the site | part used as the factor of the spring back of the press-formed product which concerns on embodiment of this invention. It is explanatory drawing of the shaping | molding analysis method of the press molded product by indentation of the indenter which concerns on embodiment of this invention (the 1). It is explanatory drawing of the shaping | molding analysis method of the press molded product by indentation indentation which concerns on embodiment of this invention (the 2). It is a flowchart which shows the flow of a process of the shape correction analysis apparatus of the press molded product which concerns on embodiment of this invention. It is explanatory drawing of the area | region specified as a factor of the spring back of the press-formed product which concerns on embodiment of this invention. In embodiment of this invention, it is a figure which shows the change of the springback amount at the time of pushing an indenter in the site | part used as the factor of a twist (the 1). In embodiment of this invention, it is a figure which shows the change of the springback amount at the time of pushing an indenter in the site | part used as the factor of curvature. In embodiment of this invention, it is a figure which shows the change of the springback amount at the time of pushing an indenter in the site | part used as the factor of a twist (the 2). It is a flowchart of the shape correction method of the press-molded real part which concerns on embodiment of this invention.

[Press-formed product]
As shown in FIG. 2, the press-formed product targeted in the first to third embodiments of the present invention is a press-formed product 21 simulating a front pillar reinforcing member for automobiles, and 980 MPa as a blank material for the press-formed product 21. A grade GA (Galvannealed) steel plate (thickness 1.4mm) is used. Since the press-formed product 21 has a hat-shaped cross-sectional shape and is curved in the longitudinal direction, spring back such as torsion and warpage is likely to occur after press-molding and releasing, and application of a high-strength material from the viewpoint of shape freezing accuracy. Is difficult.

When the press-molded product 21 is press-molded, if a shape freezing failure due to springback occurs after mold release, it is necessary to quantitatively evaluate the degree of springback.
Therefore, in the embodiment of the present invention, the twist angle and the tip spring amount shown in FIG. 3 are used as quantitative evaluation values of the degree of springback.

As shown in FIG. 3 (a), the twist angle is defined by a crossing angle of a straight line formed by two points at the left end portion before and after the spring back, with three points near the right end portion of the press-formed product 21 as fixed points. did.
On the other hand, as shown in FIG. 3B, the tip splash amount is a displacement amount of one point at the left end portion before and after the spring back, with the three points near the right end portion of the press-formed product 21 as fixed points. It was.

  You may perform the press molding analysis and springback analysis which concern on Embodiment 1-3 of this invention using a commercially available FEM (finite element method) analysis system.

[Embodiment 1]
A press-formed product shape correction analysis apparatus (hereinafter, simply referred to as “shape correction analysis apparatus”) according to Embodiment 1 of the present invention will be described with reference to FIGS.

<Shaping correction analyzer>
As shown in FIG. 1, the shape correction analysis apparatus 1 is configured by a computer, and includes a display device 3, an input device 5, a main storage device 7, an auxiliary storage device 9, and an arithmetic processing unit 11.
The display device 3 is composed of a monitor or the like, and is used for displaying analysis results. The input device 5 includes a keyboard, a mouse, and the like, and is used for operator condition input. The main storage device 7 is composed of a RAM or the like, and is used for temporary storage of data used in the arithmetic processing unit 11 and arithmetic operations. The auxiliary storage device 9 is composed of a hard disk or the like, and is used for storing files.
A display device 3, an input device 5, a main storage device 7, and an auxiliary storage device 9 are connected to the arithmetic processing unit 11.

The arithmetic processing unit 11 is constituted by a CPU (Central Processing Unit) of a computer, and each means described below is realized by the CPU executing a predetermined program.
As means realized by the arithmetic processing unit 11, a springback factor region specifying means 13, an indenter indentation analyzing means 15, and a shape correction condition determining means 17 are provided.

≪Springback factor area identification means≫
The springback factor region specifying means 13 obtains the residual stress before release of the press-molded product 21 by press-molding analysis, and in the region of the press-molded product 21 the factor causing the springback is present in the residual stress. It is for specifying what to do.

Examples of the process for specifying the region that causes the springback include the following.
First, press molding analysis for press molding the press-molded product 21 shown in FIG. 2 is performed, and molding bottom dead center, that is, data (shape, stress distribution, strain distribution, etc.) before release of the press-molded product 21 is acquired. . Then, as shown in FIG. 4, a springback analysis is performed based on the data before the mold release to calculate the springback amount x.

Next, the springback contribution is calculated.
First, in the data before release, a springback analysis is performed on the stress distribution of the press-formed product 21 before release based on the stress distribution obtained by eliminating the stress in the partial region P, and the springback amount p is calculated. To do.

  Here, as a method of erasing the stress, the stress value of the region P in the press-formed product 21 is set to 0, or the stress difference before and after the release of the press-formed product 21 is obtained. And so on. In the embodiment of the present invention, any method may be used.

  Similarly, in the data before the mold release, a springback analysis is performed based on the stress distribution obtained by eliminating the stress of the partial region Q different from the region P with respect to the stress distribution of the press-formed product 21 before the mold release. Calculate the springback amount q.

  Next, the degree of contribution to the springback of the stress remaining in each of the regions P and Q in the press-formed product 21 (hereinafter referred to as springback contribution) is calculated. Specifically, the difference (xp) or (xq) between the springback amount x obtained based on the data before mold release and the springback amount p or q obtained by changing the stress distribution is obtained, respectively. The ratios (xp) / x and (xq) / x of (xp) and (xq) to the springback amount x are calculated as the contributions of springback. This indicates that the greater the value of the springback contribution calculated in this way, the greater the degree that the residual stress in the region related to the springback contribution contributes to the springback.

  Based on the springback contribution in the partial region of the press-formed product 21 calculated by the above operation, the stress remaining in either the region P or the region Q of the press-formed product 21 before release is more springback. Depending on whether it contributes, the region where the residual stress that causes the springback exists is specified.

  In the above operation, as the spring back amount, the twist angle or the tip spring amount shown in FIG. 3 is used. By calculating the springback contribution for each of the twist angle or the tip splash amount, each region in which residual stress that causes torsion or warpage occurring after the release of the press-formed product 21 exists is specified.

  In the above description, an example is shown in which the springback contributions for the two regions of the region P and the region Q are obtained and the springback contributions of the region P and the region Q are compared. The number is not limited to two, and may be three or more. The larger the number of the regions, the more accurately the region where the residual stress contributing to the springback exists.

  Further, for a region having a residual stress with the largest contribution of springback, the region is further divided into a plurality of regions, and a region having a residual stress with the highest contribution of springback is obtained from the divided regions. It may be. This also makes it possible to specify the region contributing to the springback more accurately and in detail.

≪Indenter indentation analysis means≫
The indenter indentation analysis means 15 performs a molding analysis of the process of pushing the indenter into the region where the residual stress that causes the springback specified by the springback factor area specifying means 13 is present, and the press molded product deformed by the indenter indentation. The springback analysis is performed based on the shape data 21 and the stress distribution.

  First, as shown in FIG. 5A, a constraint condition is given to the outer periphery of the press-formed product 21 after the springback analysis performed based on the data before release obtained by the press-forming analysis.

  When compressive stress remains in the region specified by the springback factor region specifying means 13, an indenter indentation site is set using the value of the compressive stress in the region as a guide (FIG. 5B), and the constraint Under the conditions, for example, a molding analysis of the process of pushing the ball head indenter 23 into the part is performed. In the molding analysis, the shape data, stress distribution, and the like of the press-formed product 21 when a predetermined indentation amount is reached are acquired (FIG. 5C).

  On the other hand, when the tensile stress remains in the region specified by the springback factor region specifying means 13, first, the indentation portion of the indenter 23 is set using the tensile stress value in the region as a guide (FIG. 6 (a )), A molding analysis of the process of pushing the indenter 23 into the part under the constraint condition is performed. After reaching a predetermined pushing amount, for example, the flat surface indenter 25 is set to a predetermined pushing back amount in a direction opposite to the pushing direction from the surface opposite to the pushing surface with respect to the portion under the constraint condition. Forming analysis of the process of pushing back until it reaches (FIG. 6 (b)), and obtaining shape data, stress distribution, etc. of the pressed product 21 after being pushed back by the flat surface indenter 25 (FIG. 6 (c)). . Here, the pushing back amount is the same as the pushing amount by the indenter 23.

  Molding analysis of the indentation by the indenter 23 and the pushback process by the indenter 25 is performed by changing the indentation part and the indentation amount, and the press-formed product 21 after the springback is analyzed by springback analysis for each condition in which the indentation part and the indentation amount are changed. Get shape data.

≪Shape correction condition determination means≫
The shape correction condition determining means 17 is for determining conditions suitable for correcting the shape of the press-formed product 21 after the spring back obtained by the indenter indentation analyzing means 15.

  Specifically, a deviation between the shape data of the press-formed product 21 after the spring back and the target shape data of the press-formed product 21 is calculated, and the deviation is acquired as a shape correction amount by pressing the indenter. By comparing the shape correction amount when the pressing portion and the pressing amount of the indenter 23 are changed, the pressing portion and the pressing amount of the indenter 23 that are suitable for correcting the shape of the press-formed product 21 after the spring back are determined. .

  The deviation between the shape data after the spring back of the press-formed product 21 and the target shape data is based on the target shape data of the press-formed product 21, and the twist angle of the press-formed product 21 after the spring back as shown in FIG. And it can obtain | require by calculating the amount of tip splashes.

<Shaping correction analysis method>
Next, the shape correction analysis method using the shape correction analysis apparatus 1 configured as described above will be described together with the operation of the shape correction analysis apparatus 1 by taking the case of correcting the shape of the press-formed product 21 as an example. .
The shape correction analysis method according to the first embodiment of the present invention includes a springback factor region specifying step, an indenter indentation analysis step, and a shape correction condition determination step.
Hereafter, each said process is demonstrated in detail based on FIG.

≪Springback factor area identification process≫
In the spring back factor region specifying step S1, the press back analysis of the press-formed product 21 is performed by the spring back factor region specifying means 13 to obtain the residual stress before releasing, and the residual stress becomes a factor of the spring back. Is a step of identifying which region of the press-formed product 21 exists.

  As described above, the shape freezing failure of the press-formed product 21 due to the spring back includes twisting and warping. Therefore, first, press forming analysis is performed to obtain the bottom dead center of the press-formed product 21, that is, data (shape, stress distribution, etc.) before release. Next, the spring back analysis is performed based on the data before releasing, and the shape data of the press-formed product 21 after the spring back is acquired. From the shape data before and after the spring back, as shown in FIG. 3, the twist and the warp due to the spring back are quantitatively evaluated by calculating the twist angle for the twist and the tip amount of the spring for the warp. . Then, based on the calculated twist angle and the amount of tip splash, a region where residual stress that contributes to twist or warp that occurs after the mold release of the press-formed product 21 exists is specified.

  FIG. 8 shows a region where there is residual stress that causes the torsion or warpage identified in the springback factor region identification step S1. From FIG. 8, it can be seen that the compressive stress mainly remains in the region A specified as the cause of the twist, whereas the tensile stress remains mainly in the region B specified as the cause of the warp. I understand.

≪Indenter indentation analysis process≫
The indenter indentation analysis step S3 performs, for example, a molding analysis of the process of pushing in the indenter 23 of the ball head in the region that causes the springback identified in the springback factor region identifying step S1 by the indenter indentation analysis unit 15; This is a step of performing a springback analysis based on the shape data and stress distribution of the press-formed product 21 after the indenter is pushed in and deformed.

When compressive stress mainly remains in the region, the indentation portion of the indenter 23 is set based on the value of the compressive stress in the region, and the indenter 23 is pushed in to a predetermined push amount.
On the other hand, when the tensile stress mainly remains in the region, the indentation portion of the indenter 23 is set based on the value of the tensile stress in the region, and the indenter 23 reaches a predetermined amount of indentation with respect to the portion. Push in. Subsequently, the surface is pushed back from the surface opposite to the pushing surface by, for example, a flat surface indenter 25 in a direction opposite to the pushing direction until a predetermined pushback amount is reached. The pushing back amount may be the same as the pushing amount by the indenter 23.

≪Shaping correction condition determination process≫
In the shape correction condition determination step S5, the shape correction condition determination means 17 determines conditions suitable for correcting the shape of the press-formed product 21 after the spring back obtained in the indenter indentation analysis step S3. .

  Specifically, a deviation between the target shape data of the press-formed product 21 and the shape data after the spring back obtained in the indenter indentation analysis step S3 is calculated, and the deviation is used as a shape correction amount by indentation of the indenter 23. By comparing the shape correction amount when the pressing portion and the pressing amount of the indenter 23 are changed, the pressing portion and the pressing amount of the indenter 23 suitable for correcting the shape of the press-formed product 21 after the spring back are determined. .

In FIG. 9, when the shape correction is performed by pressing the indenter 23 into the region a ₁ having a high residual compressive stress value in the region A identified as the cause of the twist of the press-formed product 21, The twist angle and the amount of spring at the tip are shown.

As the pushing amount of the indenter 23 increases, the twisting angle decreases, and when the pushing amount is 9 mm, the twisting angle becomes approximately 0 °. When the push-in amount is further increased, the twist angle is further decreased to a negative value, and a twist in the direction opposite to the twist before correction occurs in the press-formed product.
On the other hand, the tip spring amount slightly increases as the indenter 23 push-in amount increases, but when the push-in amount is 6 mm or more, the tip sprung amount does not change, and the warp correction by pushing the indenter 23 is corrected. There is no effect.

  In FIG. 10, in the region B identified as the cause of warping of the press-formed product 21, the indenter 23 is pushed into a portion b having a high residual tensile stress value, and then the surface opposite to the pushing surface with respect to the portion b. When the shape is corrected by pushing back the indenter 25 in the direction opposite to the pushing direction by the same amount as the pushing amount, the twist angle and the tip spring amount when the pushing amount is changed are shown.

Although the twist angle slightly increases as the amount of push-in increases, the change is small, and the effect of correcting the twist due to the push-in of the indenter 23 cannot be obtained.
On the other hand, the tip spring amount decreased as the push amount increased, and at the push amount of about 8 mm, the tip splash amount was almost 0 mm. Even if the push-in amount is further increased, the change in the tip spring amount is slight. When the push-in amount is 8 mm or more, it is difficult to obtain a further change in the tip spring amount due to the push of the indenter 23.

  As described above, by performing the press molding analysis and the spring back analysis, it is possible to identify the region that causes the shape freezing failure due to the spring back generated in the press-molded product after the mold release, in which the compressive stress remains. If there is, press the indenter, or if the tensile stress remains, press the indenter and push back with a flat surface indenter to correct the shape freeze defect of the press-molded product after springback. It becomes possible to do. Moreover, the amount of shape correction can be changed by changing the pushing amount of the indenter.

When actually correcting the shape of a press-formed product, it is preferable that either twist or warp can be individually corrected from the viewpoint of versatility, and the twist should be corrected as described above. The part (part a _{1 in} the area A in FIG. 8) and the part (part b in the area B in FIG. 8) that can correct the warp can be specified, and the shape of the press-molded product can be corrected appropriately. It is desirable to know the indentation site and the amount of indentation.

  In the above description, a flat surface indenter is used in the push-back process, but in the push-back process, it is only necessary to be able to push back the deformation of the press-molded product, and it does not exclude the use of a curved indenter. Absent.

[Embodiment 2]
In the first embodiment described above, the shape correction analysis device 1 and the shape correction analysis method for correcting the shape freezing failure due to the springback generated after the release in the press-formed product 21 obtained by press-molding the blank material have been described. . In the first embodiment, the object is to individually correct the twist and warpage of the press-formed product 21, but the second embodiment relates to an apparatus and method for correcting both the twist and warpage.
Hereinafter, the second embodiment will be described in detail.

The press-molded product 21 shown in FIG. 2 was twisted and warped by the springback after the mold release, and the twist angle and the tip amount were 1.1 ° and 3.6 mm, respectively.
Therefore, the pressing portion and the pressing amount of the indenter 23 are determined by the shape correction analyzing apparatus 1 or the shape correction analyzing method shown in the first embodiment in order to correct the twist angle and the tip spring amount.

FIG. 9A is a graph showing the relationship between the pushing amount and the twisting angle when the indenter 23 is pushed into the portion a ₁ (FIG. 8) where the residual stress that causes twisting exists after the press-molded product 21 is released. Yes, it can be seen from this graph that the twist angle is almost 0 ° when the push-in amount is 9 mm.

  FIG. 10B shows the amount of push-in and the amount of tip bounce when the indenter 23 is pushed back into the part b (FIG. 8) where residual stress that causes warping exists after the press-molded product 21 is released and pushed back by the same amount. This graph shows the relationship, and it can be seen from this graph that when the push-in amount is 8 mm, the tip spring amount is almost 0 mm.

Therefore, the press-molded product 21 is first twisted by pushing the indenter into the portion b with an indentation amount of 8 mm and pushing back the same amount to correct the warp, and then pushing indenter with an indentation amount of 9 mm into the portion a ₁ . The processing was performed in the order of correcting.
Table 1 shows the results of the amount of tip splash and the twist angle when the above processing is performed.

From the results of Table 1, the initial twist angle was 1.1 ° and the tip bounce amount was 3.6mm. However, by pushing back part b and pushing back part a ₁ by the same amount, the twist angle was 0.1 ° and the tip was The shape has been greatly improved with a 0.3mm length.
In the present embodiment, both the twist and the warp are corrected by pushing the part a ₁ after pushing the part b and pushing back the same amount, but pushing the part b after pushing the part a ₁ Even if correction is performed by pushing back by the same amount, the same effect can be obtained, and there is no difference in the effect of shape correction depending on the order of the pushed-in parts.

In the above description, the twist is corrected by pushing the indenter 23 into the part a ₁ shown in FIG. 8 in the region specified as the cause of the twist. The part a ₁ is a part where the value of the residual compressive stress is high in the region, and the shape correction effect by pressing the indenter 23 is expected. On the other hand, a region a ₂ having a high residual compressive stress value can be confirmed in the region.
Accordingly, as in the case of the part a ₁ , the value of the residual compressive stress is high in the region, and the indenter 23 is pushed into the part a ₂ (FIG. 8) at a different position to try to correct the torsion.

When pushed in indenter 23 against sites a ₂ in FIG. 11 shows the twist angle and the tip vane amount when changing the pushing amount of the indenter 23.
As the push-in amount increases, both the twist angle and the tip spring amount decrease, and when the push amount is 10 mm, the twist angle and the tip spring amount are about 0 ° and about 0 mm, respectively. Will be corrected. When the push-in amount is further increased, both the twist angle and the tip bounce amount are further reduced to negative values, and a shape freezing defect occurs in the direction opposite to the twist and warp before correction.

  From the results shown in FIG. 9 and FIG. 11, it is possible to correct both the twist and the warp at the same time, the portion where the twist and warp due to the spring back of the press-formed product 21 after the mold release can be individually corrected. It was found that there was a site that could

[Embodiment 3]
The method for correcting the shape of an actual press-molded part according to the third embodiment is a method for correcting the shape of an actual press-molded part using the method for analyzing the shape correction of a press-formed product according to the first or second embodiment. Press forming step S11 for press forming an actual part, press forming actual part shape acquiring step S13 for measuring the shape of the press formed actual part manufactured in the press forming step, and the press forming obtained in the shape acquiring step An indenter that obtains a deviation between shape data of an actual part and target shape data of the press-formed actual part, and determines an indentation portion and an amount of indentation when correcting the shape of the actual press-formed part based on the deviation Indentation condition determination step S15, and a pre-indenter that presses the indenter into the actual press-molded part based on the indentation portion and the amount of indentation determined in the indenter indentation condition determination step. And a molded actual parts straightening step S17.
Hereafter, each said process is demonstrated in detail based on FIG.

<Press molding process>
The press molding step S11 is a step of molding an actual press molded part by performing press molding using a mold corresponding to the mold model used for the press molding analysis in the first and second embodiments. In the formed press-molded actual part, the spring back amount varies due to variations in processing conditions.

<Press molding actual part shape acquisition process>
The press-molded actual part shape acquisition step S13 is a process of acquiring the shape data of the press-molded actual part using, for example, a three-dimensional shape measuring device with respect to the press-molded press-molded actual part.

<Indenter indentation condition determination process>
The indenter indentation condition determination step S15 compares the shape data of the actual press-molded part acquired in the actual press-molded part shape acquisition step S13 with the target shape data, thereby obtaining the shape data such as the twist angle and the tip splash amount. Of the indenter for correcting the shape freezing failure due to the spring back obtained by the deviation and the shape correction analysis device 1 and the shape correction analysis method described in the first and second embodiments. This is a step of determining the indenter indentation part and the indentation amount in the actual press-molded part based on the relationship between the indentation part and the indentation (the same amount pushback) amount and the springback amount.

<Press forming actual part shape correction process>
In the press molding actual part shape correction step S17, pressing is performed by pressing the indenter into the indenter pressing condition determining step S15 obtained by the indenter pressing condition and the pressing (same amount pressing back) amount to the press molded actual part after releasing. This is a step of correcting the shape of the actual molded part.

  The actual press-formed parts vary in the amount of spring back after release due to slight differences in processing conditions and the like. For example, if you obtain shape data after releasing a press-formed actual part that was press-formed under the same press-forming conditions, and obtain the deviation from the target shape data, the tip spring amount deviation is large, but the twist angle The shape freezing defect differs depending on the actual press-molded part, such as a slight deviation, or conversely, a deviation of the tip splash amount is a small value but a deviation of the twist angle is large.

  Therefore, by applying the method for correcting the shape of the actual press-molded part shown in the third embodiment, the actual shape data of the actual press-molded part is measured and combined with the shape freezing failure of the individual press-molded actual part, It becomes possible to individually determine the indentation site and the amount of indentation for shape correction, and to reduce the shape variation for each press-formed actual part.

  In addition, the present invention is not limited to the shape correction for each press-molded actual part, but for each production lot, the frequency of setting the conditions for shape correction, such as performing shape evaluation and setting the indentation part and the amount of indentation. The effect can be expected even if is appropriately selected.

  By applying the shape correction analysis device and the shape correction analysis method and the shape correction method verified in the present invention, if it is a press-molded product in which the shape freezing failure due to the spring back after the mold release is a problem, The shape stability of mass-produced press-formed products can be ensured.

DESCRIPTION OF SYMBOLS 1 Shape correction analysis apparatus 3 Display apparatus 5 Input apparatus 7 Main storage device 9 Auxiliary storage apparatus 11 Arithmetic processing part 13 Springback factor area | region identification means 15 Indenter indentation analysis means 17 Shape correction condition determination means 21 Press molded product 23 Indenter (ball head) )
25 Indenter (flat surface)

Claims (5)

A method for analyzing the shape correction of a press-formed product, wherein the computer performs the following steps:
Determine the residual stress before release of the press-molded product by press-molding analysis, and specify in which region of the press-molded product the factor that causes the spring back of the residual stress is specified Process,
For the region specified by the springback factor region specifying step in the shape after the springback obtained based on the residual stress before the mold release, the indenter is pressed and deformed by changing the pressing portion and the pressing amount. Indenter indentation analysis process for performing springback analysis after giving
Shape correction condition determining step for determining the indentation portion and the amount of indentation effective for shape correction by comparing the shape after indentation of the indenter determined in the indenter indentation analysis step with the target shape of the press-formed product. It has a door,
In the indenter indentation analysis step, when compressive stress remains in the region identified in the springback factor region identification step, the region in the region is pushed in with an indenter,
When tensile stress remains in the region specified in the springback factor region specifying step, after the portion in the region is pressed with an indenter, the indenter is pressed from the surface opposite to the pressing surface with respect to the portion. A method for analyzing the shape correction of a press-molded product, characterized in that it is pushed back in a direction opposite to the pushing direction .   In the springback factor area specifying step, the residual stress in a partial area of the press-molded product is set to 0, the residual stress value in the partial area is changed, or before and after releasing the partial area. The shape correction analysis method for a press-formed product according to claim 1, wherein the residual stress difference is changed. A method of correcting the shape of an actual press-molded part using the method of analyzing the shape correction of a press-formed product according to claim 1 or 2 ,
A press molding step of forming a press molded actual part by performing press molding using a mold corresponding to the mold model used in the press molding analysis according to claim 1 or 2 , and the press molded actual part after release A shape correcting step of correcting the shape of the press-molded actual part by pressing the indenter with the pressing portion and the pressing amount of the indenter obtained in the shape correction condition determining step. A method for correcting the shape of a press-formed product. Determine the residual stress before release of the press-molded product by press-molding analysis, and specify in which region of the press-molded product the factor that causes the spring back of the residual stress is specified Means,
Deformation by indenting the indenter by changing the indentation part and the amount of indentation to the area specified by the springback factor area specifying means in the shape after springback obtained based on the residual stress before releasing Indenter indentation analysis means for performing springback analysis after giving
Shape correction condition determining means for determining the indentation portion and the amount of indentation effective for shape correction by comparing the shape after indentation of the indenter determined by the indenter indentation analysis means with the target shape of the press-formed product. It has a door,
The indenter indentation analysis means, when compressive stress remains in the area specified by the springback factor area specifying means, presses a site in the area with an indenter,
When a tensile stress remains in the region specified by the springback factor region specifying means, after the portion in the region is pressed with an indenter, the indenter starts from the surface opposite to the pressing surface with respect to the portion. The shape correction analysis device for a press-formed product , wherein the device is pushed back in a direction opposite to the pushing direction .   The springback factor area specifying means sets the residual stress of a partial area of the press-formed product to 0, changes the residual stress value of the partial area, or before and after releasing the partial area. The shape correction analysis apparatus for a press-formed product according to claim 4, wherein any one of the processes of changing the residual stress difference is performed.