JP4576322B2 - Shape correction method, mold, and method of manufacturing molded product - Google Patents

Description

  The present invention relates to a shape correction method for correcting a three-dimensional shape model having a fillet surface into a model shape suitable for press molding, a mold formed based on the shape correction method, and a molded product using the mold The present invention relates to a method for manufacturing a formed product.

Usually, in order to obtain a high-quality press-molded product, the mold shape is examined before mass production. Conventionally, by actually producing a mold, manufacturing a press-molded product using this mold, and performing a three-dimensional molding analysis of this molded product (presence of shape defects, presence of chips, presence of cracks), The mold is gradually modified to complete the best mold model.
However, since the conventional methods as described above require a lot of time and labor to analyze a molded product and modify the mold, recently, there is a technology that can search for a mold shape suitable for press molding by simulation. Has been developed.
In the simulation, when creating a mold model, it is necessary to create a mold model from ideal line data of the molded product. At this time, if corners exist in the shape model of the mold, it is necessary to create a fillet surface that smoothly connects these corners. For example, in Japanese Patent Laid-Open No. 11-3439 (Patent Document 1), a fillet surface can be formed by a simple operation of inputting a radius for a press forming analysis model created from line data. A method for creating a model for press forming analysis is disclosed.
JP 11-3439 A (page 2-6, FIG. 2)

  However, in the conventional press forming analysis model creation method as disclosed in Patent Document 1, generally, all fillet surfaces are connected by arcs. For example, as shown in FIG. 16, when performing a drawing process for forming a bottomed columnar container as shown in FIG. 17 from a plate material 12 using a punch 11 and a die 10 manufactured by a conventional technique, The curved surface of the part A has the shape of the inner upper surface of the torus as shown in FIG. 18, and the curved surface of the punch shoulder B has the shape of the outer lower surface of the torus shown in FIG. Here, the torus is a rotation surface drawn when the circle C is rotated once around the axis l, and is composed of a non-expandable surface except for the apex portion and the bottom surface portion (both are linear). The

  As described above, in the press forming analysis model creation method in which the fillet portions are simply connected by arcs, the produced mold has a non-expandable surface and was molded using such a mold. The molded article has a problem that wrinkles and cracks occur.

  The present invention has been made to solve the above problems, and is based on a shape correction method capable of correcting a press die shape into a shape suitable for press molding, and a shape model corrected by the shape correction method. It is an object of the present invention to provide a produced mold and a method for producing a mold capable of producing a high-quality molded product with reduced wrinkles and cracks by performing molding using the mold.

In order to solve the above problems, the present invention employs the following means.
The present invention relates to a shape correction method for correcting a mold model having a fillet surface into a model shape suitable for press molding, in which a computer uses a torus from a three-dimensional shape model expressed by a shape data file of the mold model. An extraction process of extracting a fillet surface expressed by a surface, and a first correction process of correcting the extracted fillet surface into an elliptic torus surface in which the vertex of the cross-sectional ellipse is located at the center of the fillet surface Provided is a shape correction method to be executed.

  According to the above method, for example, since the fillet surface having a curved surface shape of a part of the torus is corrected to the curved surface shape of an elliptic torus, the curvature of the fillet surface can be changed gently and the non-expandable surface Can be brought closer to a developable surface. This makes it possible to remove the cause of wrinkles and cracks.

  In the shape correction method, the computer has a smooth and continuous curvature at a boundary portion between the fillet surface composed of the elliptical torus surface corrected by the first correction process and a surface adjacent to the fillet surface. It is preferable to execute a second correction process for further correcting the shape of the fillet surface.

  According to this method, it is possible to smoothly connect the fillet surface after the first correction and the adjacent surface thereof, so that generation of wrinkles and cracks can be further prevented.

In the second modification process, as the fillet surface and the ridge line that connects the surface adjacent to the fillet surface after the first modification is represented as differentiable functions second floor above the fillet surface it is preferable that the positive Osamu.

で表される。
このような関数を用いることにより、極めて容易にフィレット面とその隣接面とを滑らかに且つ連続的な曲率を有するように接続することが可能となる。 The function is, for example,

It is represented by
By using such a function, it is very easy to connect the fillet surface and its adjacent surface so as to have a smooth and continuous curvature.

The present invention is a mold model creation method for creating a mold model suitable for press molding, and includes a corner extraction process for extracting a corner composed of two surfaces from a three-dimensional model, and at least one Provided is a mold model creation method including a fillet creation process for creating a fillet surface of an elliptical torus surface at the corner .

  According to such a method, since the fillet surface of the elliptical torus surface is created at the corner, it becomes possible to connect the surfaces with a gentle curvature change, and the non-expandable surface is brought close to the expandable surface. It becomes possible. This makes it possible to remove the cause of wrinkles and cracks.

The present invention provides a mold manufactured based on a mold model modified by the above- described shape correction method.
The present invention provides a mold having a fillet surface to the curved shape of the elliptical torus.

  In any of the above molds, the fillet surface is formed as an elliptical torus surface. By using this mold, it is possible to produce a clean molded product free from wrinkles and cracks.

The present invention uses the mold described above having a fillet surface to the curved shape of the elliptical torus, provides a method for producing a molded article to produce a molded article by press molding a plate material.
Since the mold used in the above manufacturing method has a fillet surface formed as an elliptical torus surface, it is possible to manufacture a high-quality molded product free from wrinkles and cracks by using this mold.

The present invention is a three-dimensional shape processing apparatus that corrects a mold model having a fillet surface into a model shape suitable for press molding, from a three-dimensional shape model expressed by a shape data file of the mold model to a torus surface. 3 comprising: extraction means for extracting the represented fillet surface; and first correction means for correcting the extracted fillet surface into an elliptic torus surface whose apex of the cross-sectional ellipse is located at the center of the fillet surface. A dimension shape processing apparatus is provided.

  According to the above three-dimensional shape processing apparatus, for example, since a fillet surface having a curved surface shape of a part of a torus is corrected to a curved surface shape of an elliptic torus, the curvature of the fillet surface can be gradually changed, which is not possible. It is possible to bring the exhibition surface closer to the developable surface. This makes it possible to remove the cause of wrinkles and cracks.

The present invention relates to a shape correction program for correcting a mold model having a fillet surface into a model shape suitable for press molding, from a three-dimensional shape model represented by a shape data file of the mold model to a torus surface. Extraction means for extracting the expressed fillet surface, and a first correction process for correcting the extracted fillet surface into an elliptic torus surface whose apex of the cross-sectional ellipse is located at the center of the fillet surface. A shape correction program for execution is provided.

  By executing such a computer program using hardware resources, for example, the fillet surface formed as a torus surface is corrected to the curved surface shape of an elliptic torus, so that the curvature of the fillet surface can be changed gently. It becomes possible, and the non-developable surface can be brought close to the developable surface. This makes it possible to remove the cause of wrinkles and cracks.

  According to the present invention, it becomes possible to correct the mold model to a shape model suitable for press molding, so by performing molding using a mold produced based on such a shape model, There is an effect that a high-quality molded product with reduced wrinkles and cracks can be obtained.

Hereinafter, an embodiment of a shape correction method according to the present invention will be described with reference to the drawings.
[Shape correction method]
FIG. 1 is a block diagram showing a schematic configuration of a three-dimensional shape processing apparatus for realizing the shape correction method according to the present embodiment. As shown in FIG. 1, the three-dimensional shape processing apparatus according to the present embodiment is a computer system such as CAD (Computer Aided Design) or CAM (Computer Aided Manufacturing), and includes a CPU (Central Processing Unit) 1, RAM ( A main storage device 2 such as a Random Access Memory, an auxiliary storage device 3 such as an HDD (Hard Disk Drive), an input device 4 such as a keyboard and a mouse, and an output device 5 such as a monitor and a printer are configured. .
Various programs are stored in the auxiliary storage device 3, and the CPU 1 reads out the programs from the auxiliary storage device 3 to the main storage device 2 such as a RAM, and executes them to execute various processes described later, for example, a mold model. Create the mold, modify the created mold model, and so on.

Next, a shape correction method performed by the three-dimensional shape processing apparatus having the above-described configuration will be described with reference to FIG.
The shape correction method described below is realized by the CPU 1 provided in the three-dimensional shape processing apparatus reading out the shape correction program stored in the auxiliary storage device 3 to a RAM or the like and executing it.

  First, in step SA1 of FIG. 2, the CPU 1 performs a process of reading the shape data file of the mold model received via the auxiliary storage device 3 or a communication network (not shown). Here, the data file to be read is a data file in which the contents recorded by the international standard or the manufacturer publishing the specification are made clear, for example, data such as IGES, STEP, STL, DXF It is a file.

In the subsequent step SA2, the fillet surface is extracted from the three-dimensional shape model expressed by the read shape data file, that is, the mold model.
Here, generally, the fillet surface is created by a torus surface. Therefore, in this embodiment, a fillet surface is extracted by extracting a torus surface.

Specifically, by analyzing the curved surface of the three-dimensional shape model, the feature amount of the curved surface constituting the three-dimensional shape model is analyzed, and a curved surface whose feature amount matches the pre-registered feature amount of the torus is filled. Extract as a face. For example, torus feature amounts described below are stored in a predetermined memory area of the auxiliary storage device 3.
Hereinafter, an example of the curved surface analysis will be briefly described.

  For example, at a point P on the curved surface W as shown in FIG. 3, a unit vector standing perpendicular to the tangent plane is a unit normal vector n, a plane including the unit normal vector n is a normal plane, The line of intersection with the curved surface W is called the normal section. When the normal plane is rotated around the unit normal vector n using the differential of the normal section as the curvature, the relationship between the rotation angle θ and the curvature is obtained as a graph as shown in FIG. 4, for example.

Here, the maximum curvature K ₁ and the minimum curvature K ₂ are referred to as the principal curvature of the curved surface W at the point P, and a value obtained by multiplying these principal curvatures K ₁ and K ₂ is a Gaussian curvature Kg, and an average value is an average curvature Km. . The shape of the curved surface W can be grasped from the Gaussian curvature Kg and the average curvature Km. FIG. 5 shows an example of a shape determined by the Gaussian curvature and the average curvature. As shown in this figure, if the Gaussian curvature Kg = 0, that is, if one or both main curvatures are zero, the curved surface W becomes a developable surface. If the Gaussian curvature Kg takes a negative value, the curved surface W has a bowl shape. Conversely, if the Gaussian curvature Kg takes a positive value, the curved surface W takes a dish shape.

  The main curvature, Gaussian curvature, average curvature, and the like can be referred to as feature quantities for specifying a curved surface, and the shape of the curved surface can be specified by these distributions. For example, FIGS. 6 to 11 show examples of torus feature amounts. 6 is a Gaussian curvature distribution, FIG. 7 is an average curvature distribution, FIG. 8 is a main curvature (longitudinal direction) distribution, FIG. 9 is a main curvature (width direction), FIG. 10 is a length in a circumferential direction, and FIG. Indicates the length of the circumference in the direction of rotation.

  Next, in step SA3, a first correction process is performed. In this process, the torus surface is corrected to an elliptic torus surface. In this process, for example, the torus surface may be replaced with a previously registered elliptic torus surface, or the elliptical torus surface may be corrected by changing the control amount representing the torus surface. May be.

For example, when the three-dimensional shape model is a bottomed columnar container as shown in FIG. 12, the curved surface D and curved surface E of the shoulder, which is a torus surface, are extracted as the fillet surface in the above-described step SA2. Here, FIG. 13 is a diagram in which the bottomed cylindrical container shown in FIG. 12 is cut by two planes passing through the central axis and intersecting each other, and FIG. 14 is an enlarged view of the curved surface D of FIG. It is. As shown in FIG. 14, since the curved surface D is a torus surface, its cross section is a circle. In the first correction process in step SA3, the fillet which is such a torus surface is corrected to an elliptic torus surface.
Here, both the elliptical torus and the normal torus (with a circular cross section) have the same characteristics that the upper and lower ends are developable surfaces and the Gaussian curvature changes between them. Compared to this, the area that can be regarded as a developable surface, that is, a portion where the Gaussian curvature is substantially zero (hereinafter referred to as “substantially developable surface”) has a large area. Therefore, it is preferable to correct the fillet surface, which is a torus surface, to an elliptical torus surface so that the substantially developable surface portion can be used effectively, in other words, to include a lot of the substantially developable surface. In this way, by correcting to the elliptical torus surface, the change in the curvature of the fillet surface can be suppressed, that is, the change in the displacement of the length can be reduced.
Specifically, as shown in FIG. 15, the elliptical torus is rotated so that the apex of the elliptical torus is at the center of the shoulder (see FIGS. 13 and 14), thereby correcting the shape of the shoulder. That is, an elliptical torus obtained by rotating an elliptical arc in the width direction of the elliptical torus by π / 4 (= 45 °) is applied to the shoulder.

In subsequent step SA4, a second correction process is performed. In this process, the elliptical torus surface is corrected so that the curvature at the boundary between the corrected elliptical torus surface and the surface adjacent to the elliptical torus surface is smooth and continuous.
Specifically, the elliptical torus surface is corrected so that a section line connecting the corrected elliptical torus surface and the adjacent curved surface adjacent to the elliptical torus surface is expressed as a function that can be differentiated by two or more floors. An example of a function is shown below.

  As a result, the elliptical torus surface and its adjacent curved surface can be smoothly connected.

  As described above, according to the shape correction method according to the present embodiment, the mold model including the fillet surface is subjected to curved surface analysis, and the fillet surface (torus surface) is extracted based on the result of the curved surface analysis, Since the extracted fillet surface is corrected to an elliptical torus surface, the fillet surface can be brought close to a developable surface and the curvature of the fillet surface can be changed gently. This makes it possible to remove the cause of wrinkles and cracks.

  In the above embodiment, the fillet surface is extracted by analyzing the curved surface of the three-dimensional shape model expressed by the shape data file and automatically extracting the torus surface based on the result, but the fillet surface is selected. The method is not limited to this example. For example, in a three-dimensional shape model expressed by a shape data file, the fillet plane may be specified by an operator operating an input device. Further, among the automatically extracted fillet surfaces, the above three-dimensional shape processing apparatus has a function for selecting a fillet surface to be subjected to shape correction by inquiring of an operator as to whether or not to make a shape correction target. It is also possible to have it.

  Further, in addition to a method of extracting a torus surface in a three-dimensional shape model already created as described above and correcting the curved surface to an elliptic torus surface, for example, in a fillet creation process during creation of a mold model, an elliptic torus It is good also as a structure which creates the fillet surface of a surface directly. For example, in the fillet creation process, a corner portion constituted by two surfaces may be extracted and a fillet surface having an elliptical torus surface shape may be created at the corner portion. It is also possible to create such an elliptical torus fillet surface at the vertex where the three surfaces intersect.

[Method of manufacturing molded product]
Next, the manufacturing method of the molded article which concerns on one Embodiment of this invention is demonstrated.
In the method for manufacturing a molded product according to the present embodiment, a molded product is manufactured using a mold that is manufactured based on a mold model that has been subjected to shape correction by the above-described shape correction method. That is, in the mold used in the method for manufacturing a molded product according to this embodiment, the fillet surface is not a torus surface but an elliptic torus surface.

Hereinafter, the case where a bottomed columnar container as shown in FIG. 12 is manufactured will be described as an example.
In this embodiment, as shown in FIG. 16, a plate material is disposed on the upper surface of the die 10, and a molded product is manufactured by performing cylindrical drawing by pressing the punch 11. At this time, since the curved surface of the die shoulder A of the die 10 and the curved surface of the punch shoulder B of the punch 11 shown in FIG. 16 are corrected to be an elliptical torus as shown in FIG. The compression deformation and elongation deformation in can be reduced as compared with the case of the torus surface. This makes it possible to produce a high-quality molded product with very few wrinkles and cracks.

As described above, according to the method for manufacturing a molded product according to the present embodiment, a molded product is manufactured using a mold manufactured based on a mold model modified to a shape suitable for molding. It becomes possible to produce a high-quality molded product with extremely few wrinkles and cracks.
In the above-described embodiment, the cylindrical drawing is described as a specific example of the pressing, but this is an example, for example, flange processing (stretch flange bending, drawing flange bending), extrusion processing, deep drawing processing, drawing bending. It can be applied to processing, overhanging, edge bending, extrusion, and the like.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and includes design changes and the like without departing from the scope of the present invention.

It is a block diagram which shows schematic structure of the three-dimensional shape processing apparatus which concerns on one Embodiment of this invention. It is the flowchart which showed the process sequence of the shape correction method performed by the three-dimensional shape processing apparatus which concerns on one Embodiment of this invention. It is a figure for demonstrating Gaussian curvature. FIG. 4 is a diagram showing a relationship between a rotation angle θ and a curvature obtained by rotating a normal plane around a unit normal vector n with a derivative of a normal section in the curved surface shown in FIG. 3 as a curvature. It is a figure which shows an example of the shape determined by a Gaussian curvature and an average curvature. It is the figure which showed an example of the Gaussian curvature distribution of a torus. It is the figure which showed an example of the average curvature distribution of a torus. It is the figure which showed an example of the main curvature (longitudinal direction) distribution of a torus. It is the figure which showed an example of the main curvature (width direction) of a torus. It is the figure which showed an example of the length of the rotation direction in the circumferential direction of a torus. It is the figure which showed an example of the length of the circumference in the rotation direction of a torus. It is a figure which shows an example of a three-dimensional shape model. It is the figure which cut off the cylindrical container with a bottom shown in FIG. 12 by two planes which cross | intersect mutually through a central axis. It is the figure which expanded and showed the curved surface D of FIG. It is a figure which shows the curved surface after correcting to an elliptical torus surface. FIG. 5 is a diagram illustrating an example of a drawing process for forming a bottomed columnar container from a plate material 12 using a punch 11 and a die 10. It is the figure which showed an example of the processed goods manufactured by the drawing process shown in FIG. It is the figure which showed the torus.

1 CPU
2 Main storage device 3 Auxiliary storage device 4 Input device 5 Output device

Claims (6)

A shape correction method for correcting a mold model having a fillet surface into a model shape suitable for press molding,
Computer
An extraction process for extracting the fillet surface represented by the torus surface from the three-dimensional shape model represented by the shape data file of the mold model;
A shape correction method for executing a first correction process in which the extracted fillet surface is corrected to an elliptic torus surface in which a vertex of a cross-sectional ellipse is located at the center of the fillet surface . The computer is
The curvature of the fillet surface is such that the curvature at the boundary between the fillet surface composed of the elliptical torus surface modified by the first modification process and the surface adjacent to the fillet surface is smooth and continuous. The shape correction method according to claim 1, wherein a second correction process for further correcting the shape is executed. A mold manufactured based on a mold model modified by the shape correction method according to claim 1 . The manufacturing method of the molded product which manufactures a molded product by press-molding a board | plate material using the shaping | molding die of Claim 3 . A three-dimensional shape processing apparatus for correcting a mold model having a fillet surface into a model shape suitable for press molding,
Extraction means for extracting a fillet surface expressed by a torus surface from a three-dimensional shape model expressed by a shape data file of a mold model;
A three-dimensional shape processing apparatus comprising: first correcting means for correcting the extracted fillet surface into an elliptical torus surface in which a vertex of a cross-sectional ellipse is located at the center of the fillet surface . A shape correction program for correcting a mold model having a fillet surface into a model shape suitable for press molding,
Extraction means for extracting a fillet surface expressed by a torus surface from a three-dimensional shape model expressed by a shape data file of a mold model;
A shape correction program for causing a computer to execute a first correction process for correcting the extracted fillet surface to an elliptical torus surface in which a vertex of a cross-sectional ellipse is located at the center of the fillet surface .

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