JP2006195832A - Method and apparatus for creating mold shape - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently create a mold shape including the shape of back drawing by making effective use of product shape data in the creation of the shape of back drawing. <P>SOLUTION: An apparatus for creating a mold shape includes a feature creating part 13 for creating the basic shape of a mold; a back drawing shape creation means 15 for creating the shape of back drawing of the mold; a back drawing data combining part 17 for combining the basic shape of the mold with the shape of back drawing; and a storage device 2 for storing wall thickness factor data 22 in which the conversion requirements for determining the shape of back drawing from the product shape so as to provide a predetermined wall thickness are set, for each pattern of product shape in which the shape of each part of the product is typified as a plurality of kinds. The back drawing shape creation means 15 divides the product shape derived from a three-dimensional model into a plurality of regions, and for each of the regions searches the wall thickness factor data 22 for the conversion requirements matching the corresponding pattern of the product shape, and creates the shape of back drawing for each region according to the conversion requirements. The shapes of back drawing are combined to produce the shape of back drawing of the entire mold. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method and an apparatus for generating a mold shape including a back-opening shape when designing a mold for forming an outer peripheral portion of a cast product.

  In forming a mold for casting a cast product such as a cylinder block or a cylinder head of an automobile engine, it has been conventionally performed to generate a mold shape based on a product model by a computer.

For example, in the mold design method and the design support system disclosed in Patent Document 1 below, the shape of the product and the boundary surface between the outer mold and the core are input to the computer, and the input information is input to the computer. Based on this, the processing means in the computer determines the outer shape and the core shape, respectively.
Japanese Patent Laid-Open No. 7-152821

  The invention disclosed in Patent Document 1 can generate a shape surface that mainly corresponds to the product shape among the shapes of the mold, but the mold (outer mold) that forms the outer periphery of the cast product. No particular attention is paid to how the shape of the back surface is generated with respect to the shape surface.

  By the way, when the outer mold is a sand mold, the surface on the back side with respect to the shape surface is reduced in weight by cutting unnecessary meat portions except for the reinforcing rib, and the thickness of the outer mold is increased. It is desirable to make it uniform, for example, in the case of a mold molding method called a cold box method (molding method in which sand mixed with dredged sand and liquid resin is filled in a mold and then cured at room temperature through amine gas) It is preferable to make the mold thickness substantially constant because the entire mold is uniformly cured.

  In the case of generating a back-filled shape so as to satisfy these requirements, the product shape data has not been used effectively in the past, and the surface is sequentially cut and created. There is a problem that it takes much time to generate a punched shape, and further, it is very troublesome to rework the punched shape even when the product shape is partially redesigned.

  In view of the above circumstances, the present invention effectively uses the product shape data for generating the backside shape, can efficiently generate the mold shape including the backside shape, and responds to the design change of the product shape. It is an object of the present invention to provide a mold shape generation method and a generation apparatus thereof that can easily change mold shape generation data.

  The method for generating a mold shape of the present invention is a method for generating a mold shape including a backside shape of a mold that forms the outer periphery of a cast product, and is based on a three-dimensional model of a product in an area corresponding to a single mold, A basic shape generating step for generating a mold basic shape having a shape surface corresponding to a product shape, a backside shape generating step for generating a backside shape of the mold, and a step of synthesizing the mold basic shape and the backside shape. As a pre-processing for generating the back-through shape, a plurality of types of product shape patterns in which the shape of each part of the product is classified are defined, and a predetermined thickness is given to each product shape pattern. The conversion conditions for determining the back-through shape from the product shape are set in the product, and in the back-through shape generation process, the product shape based on the above three-dimensional model is divided into a plurality of areas, and the product shape in the area is divided into each area. Is on Investigate which of the multiple types of product shape pattern is applicable, determine the backside shape according to the above conversion conditions according to the corresponding product shape pattern, and then synthesize the backside shape of each determined area to mold the entire mold It is characterized in that the back-filled shape of the sheet is obtained.

  According to this method, in generating the back-through shape, the back-through shape is obtained from the product shape by the conversion condition according to the product shape pattern for each area into which the mold shape is divided. Since the shape is synthesized to obtain the backside shape of the entire mold, a backside shape that makes the mold have a predetermined thickness can be easily and efficiently generated. Further, even if there is a partial design change of the product, it is possible to easily change the backside shape by re-determining the backside shape only for the area including the design change portion.

  In this method, in the preliminary processing, as a plurality of types of product shape patterns, a concave shape pattern that is concave with respect to a predetermined reference surface, a convex shape pattern that is convex with respect to the reference surface, and the reference A curved surface shape pattern that is a gentle curved surface with respect to the surface and a square shape pattern that includes a square shape portion are set, and as a conversion condition for each product shape pattern, from the concave shape pattern, the approximate center of the concave shape The back side shape is obtained by enlarging with reference to the position, and the back side shape is obtained from the convex shape pattern by reducing the approximate center position of the convex shape, and from the curved shape pattern and the square shape pattern, It is preferable to obtain the back-through shape by translating the shape in a predetermined direction.

  In this way, the product shape can be appropriately categorized, and the conversion to the backside shape can be appropriately performed so that the thickness of the mold is substantially constant for each categorized pattern.

  In addition, the mold shape generating apparatus of the present invention is an apparatus for generating a mold shape including a backside shape of a mold that forms the outer periphery of a cast product, and is a three-dimensional model of a product in an area corresponding to a single mold. Based on the above, the basic shape generating means for generating the basic mold shape having a shape surface corresponding to the product shape, the reverse shape generating means for generating the reverse mold shape of the mold, and the above basic mold shape and reverse mold shape are synthesized. The mold final shape generating means for generating the final shape of the mold and a plurality of types of product shape patterns in which the shape of each part of the product is categorized, and a product having a predetermined thickness for each product shape pattern Storage means for storing wall thickness factor data in which a conversion condition for obtaining a backside shape from the shape is set, and the backside shape generating means is a dividing unit for dividing the product shape by the three-dimensional model into a plurality of areas. For each area divided by the dividing means, the product shape in the area is compared with the plural types of product shape patterns, and the selecting means for selecting the corresponding product shape pattern is selected by the selecting means. The conversion condition corresponding to the formed product shape pattern is obtained from the wall thickness factor data, and the reverse pattern generation means in the area for generating the reverse pattern for each area according to the conversion condition, and the reverse pattern in the area And a synthesizing unit for synthesizing the backside shape of each area obtained by the generating unit to obtain the backside shape of the entire mold.

  According to this apparatus, the above method is automatically executed.

  As described above, according to the method and apparatus for producing a mold of the present invention, a backside shape of a mold can be easily generated, and thereby a mold shape including a backside shape can be efficiently generated. it can.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram showing a configuration of a mold shape generation apparatus according to an embodiment of the present invention. The mold shape generation apparatus shown in this figure stores an arithmetic processing unit 1 including a CPU, CAD data, and the like. A storage device 2, an input device 3 including a keyboard and the like, and a display device 4 including a display such as a CRT are provided.

  The arithmetic processing device 1 includes an input processing unit 11 connected to the input device 3 and a display processing unit 12 connected to the display device 4, a feature generation unit 13 constituting basic shape generation means, It includes a feature setting unit 15a, a feature type selection unit 15b, a feature generation unit 15c, and a feature synthesis unit 15d that constitute the shape generation unit 15, and a back data synthesis unit 17 that constitutes a final mold shape generation unit.

  The feature generation unit 13 receives a three-dimensional model of a product in a region corresponding to a single mold from the input device 3 via the input processing unit 11. Then, the feature generation unit 13 determines a shape surface corresponding to the product shape based on the three-dimensional model, and generates a basic mold shape (a mold shape excluding the backside shape). A feature model FM1 corresponding to this basic mold shape is stored in the storage device 2 as sand mold CAD data 21.

  Further, the three-dimensional model of the product fetched from the input device 3 via the input processing unit 11 is also input to the feature setting unit 15 a of the backside shape generating unit 15. The feature setting unit 15a functions as a dividing unit that divides the product shape based on the three-dimensional model into a plurality of sections, and sets a reference surface and a shape surface, which will be described later.

  The feature type selection unit 15b in the backside shape generation means 15 compares the product shape in the area with the plurality of types of product shape patterns for each divided area, and selects the corresponding product pattern. As a function. Specifically, as will be described in detail later, four product shape patterns A to D shown in FIG. 2 are determined in advance, and a pattern corresponding to the product shape in the area is selected from these patterns A to D. The

  The feature generation unit 15c in the backside shape generation unit 15 corresponds to the in-area backside shape generation unit, and obtains a conversion condition from the wall thickness factor data 22 in the storage device 2 according to the selected product shape pattern, and the conversion Depending on conditions, a back-filled shape in each area is generated.

  Here, the wall thickness factor data 22 is obtained by setting conversion conditions for obtaining a backside shape from a product shape so as to give a predetermined thickness for each of a plurality of predetermined product shape patterns. In the present embodiment, as shown in FIG. 2, the product shape is a concave pattern A that is concave with respect to a predetermined reference surface, a convex pattern B that is convex with respect to the reference surface, and the reference The concave shape pattern A is categorized into four types of patterns, that is, a curved surface shape pattern C that is a gentle curved surface with respect to the surface and a square shape pattern D that includes a square shape portion, and a conversion condition that gives a substantially constant thickness. Is obtained by enlarging with respect to the approximate center position of the concave shape to obtain a backside shape, and from the convex pattern B, the backside shape is obtained by reducing with respect to the approximate center position of the convex shape. From pattern C, the backside shape is obtained by translating it in a direction perpendicular to the reference plane, and from the square pattern D, the backside shape is obtained by translating it in a predetermined oblique direction. To do. In the figure, the solid line is the product shape, and the broken line is the back-through shape.

  Such conversion conditions for each of the patterns A to D are stored in advance in the storage device 2 as the thickness factor data 22.

  Further, the feature synthesis unit 15d in the backside shape generation unit 15 corresponds to the backside shape synthesis unit, and combines the backside shape for each area obtained by the feature generation unit 15c to obtain the backside shape of the entire mold. Is to ask for. The feature model FM2 corresponding to the back-through shape of the entire mold is stored in the storage device 2 as back-through CAD data 23.

  Further, the backside data compositing unit 17 combines the feature model FM1 of the sand CAD data 21 and the feature model FM2 of the backside CAD data 23, thereby generating a final mold shape. The shape is sent to the display device 4 via the display processing unit 12 and displayed.

  FIG. 3 shows the shape of the mold (sand mold) viewed from the back side. FIG. 3A shows the shape of the mold before synthesis of the back side data, that is, the feature model FM1 in the sand mold CAD data 21 in FIG. A mold shape 25A corresponding to is shown. FIG. 5B shows the final mold shape 25 after the back-filling data composition generated in the back-filling data composition unit 17 in FIG. Further, FIG. 4 shows an enlarged cross section of the mold shape 25.

  As shown in these drawings, when generating a shape of a mold made of a sand mold, a product shape portion 26 having an uneven shape corresponding to the product shape is formed on the surface on the product forming side. On the other hand, ribs 27 are disposed vertically and horizontally on the surface on the back side with respect to the surface on the product forming side, and the arrangement of the ribs 27 is preset. Further, a portion other than the rib 27 is provided with a back side portion 28 obtained by cutting the back side meat portion so as to have a substantially constant thickness according to the shape of the product shape portion 26, and the shape of the back side portion 28. Is generated by the above-described back-through shape generation means 15. The thickness of the portion other than the rib 27 is set according to the molding method or the like. For example, in the case of the cold box method described above, the thickness is about 10 mm.

  Next, a specific example of the mold shape generation method by the above-described generation apparatus will be described based on the flowcharts of FIGS. 5 and 6.

  The flowcharts of FIGS. 5 and 6 show the processing by the arithmetic processing apparatus 1 shown in FIG. 1, particularly the processing as the backside shape generation means 15. First, in step S1, the mold shape to be generated is a plurality of island shapes. Divided into (areas). In this case, the number of divisions and the size of the island shape to be divided are determined according to the size and complexity of the mold shape. As a preferable division method, the shape is divided into island shapes defined by the ribs 27. . Next, in steps S2 and S3, a reference surface 31 and a shape surface 32 (see FIG. 7) are set for each island. In this case, as shown in FIG. 7, the plane having the maximum area in the island shape is the reference plane 31, and the other plane is the shape plane 32.

  Steps S1 to S3 serve as the feature setting unit 15a of the backside shape generating means 15 in FIG.

  Next, in step S4, it is determined whether or not the angle θ (see FIG. 8) formed by the reference surface 31 and the shape surface 32 satisfies cos θ ≧ 0.95 (equation (1)). If this determination is YES, it means that the angle θ formed by the reference surface 31 and the shape surface 32 is small, and the shape surface 32 is gently inclined or curved with respect to the reference surface 31. In step S5, the conversion condition based on the curved surface shape pattern C in FIG. 2 is applied, and the back-through shape is obtained by being translated by the thickness dimension in the direction perpendicular to the reference surface. Then, the process proceeds to step S22 described later.

  If the determination in step S4 is NO, it is determined in step S6 whether there are a plurality of surfaces that do not satisfy the above expression (1). If this determination is NO, that is, if there is a single surface that does not satisfy the above formula (1), in step S7, the conversion condition based on the angular pattern D in FIG. The direction of movement is determined and translated in this direction by the wall thickness. More specifically, the thickness dimension in the direction of parallel movement is decomposed in three directions of X, Y, and Z to obtain the X component, the Y component, and the Z component, and each component is moved in each direction. A back-through shape is required. Then, the process proceeds to step S22 described later.

  If the determination in step S6 is YES, it is determined in step S8 whether or not the plurality of shape surfaces are connected without intersecting the reference surface. If the determination is YES, in step S9, the above equation (1) is determined. After the shape is divided for each surface that does not satisfy the above, the process returns to step S6. If the number of faces that do not satisfy the above equation (1) due to the division becomes singular (the determination in step S6 is NO), the process proceeds to step S7, and the process proceeds to step S22.

  If the determination in step S8 is YES, the plurality of shape surfaces intersect with the reference surface, specifically, for example, a shape in which the plurality of shape surfaces are connected to the concave shape and both ends thereof intersect with the reference surface, or a plurality of shapes The shape surface is connected to the convex shape, and both ends of the shape surface intersect the reference surface. In this case, in step S10, the surfaces on which the uneven shape is formed are grouped. Subsequently, in step S11, an uneven center line CL (see FIG. 8) is set.

  Subsequently, in step S12, it is determined whether or not there is a surface where the angle θ formed by the shape surface and the reference surface satisfies θ> 0 (Equation (2)). Here, if there is a surface satisfying θ> 0, it means that the group including the surface has a convex shape (rib), and otherwise, each group in the island has a concave shape (boss).

  If the determination in step S12 is YES, it is determined whether there are a plurality of groups (convex shapes) having a surface that satisfies the above equation (2), and if the determination is NO (the number of groups is singular) The process proceeds to step S15 as it is, and if the determination is YES (the number of groups is plural), the island shape is divided for each convex shape having a surface satisfying the expression (2), and then the process proceeds to step S15.

  In step S15, the conversion condition by the convex pattern B in FIG. 2 is applied to the convex shape satisfying the above formula (2), and the convex shape is reduced to a dimension scale that maintains a predetermined thickness. A back-through shape is required.

  After the process of step S15, it is determined in step S16 whether or not the island shape includes a concave shape having a surface that does not satisfy the formula (2) in addition to the convex shape. If NO, the process proceeds to step S22 described later.

  If the determination in step S12 is NO or the determination in step S16 is YES, that is, if a concave shape is included in the island shape, in step S17, the group by grouping the faces in step S10 It is determined whether the number is plural. If the determination in step S17 is NO (the number of groups is singular), the conversion condition by the pattern A in FIG. 2 is applied to the concave shape in step S18 so that the dimension scale maintains a predetermined thickness. When the concave shape is enlarged with respect to the center line CL, a back-through shape is obtained. Then, the process proceeds to step S22 described later.

  If the determination in step S17 is YES (the number of groups is plural), in step S19, the conversion condition by the pattern A in FIG. 2 is applied to the concave shape having a surface that does not satisfy the expression (2). The recessed shape is expanded with reference to the center line CL so as to obtain a dimension scale that maintains a predetermined thickness, whereby a back-through shape is required. Further, in step S20, it is determined whether or not the concave shape that is not the object of the processing in step S19 remains in the island shape. If it remains, the remaining shape is changed to another island shape in step S21. After that, the processes of steps S19 and S20 are repeated. In this way, until the concave shape that is not the object of processing in step S19 does not remain in the island shape, each concave shape is sequentially enlarged with reference to the center line CL to obtain a back-through shape. Then, the process proceeds to step S22 described later.

  Steps S4 to S21 function as the feature type selection unit 15b and the feature generation unit 12c of the backside shape generation unit 15 in FIG.

  Further, in step S22, as the process of performing the function as the feature synthesis unit 15d of the backside shape generating means 15 in FIG. 1, the backside shape for each island shape obtained in the above steps S4 to S21 is synthesized. . As a result, the back-through shape is completed.

  According to the mold shape generation method as described above, based on the three-dimensional model of the product input from the input device 3 via the input processing unit 11, the mold basic having a shape surface corresponding to the product shape by the feature generation unit 13 The shape is generated, and the backside shape generation means 15 also generates the backside shape of the mold based on the three-dimensional model of the product.

  In particular, as shown in FIG. 2, for each of a plurality of types of product shape patterns A to D, if the product shape is a concave shape, it is enlarged, if it is a convex shape, it is reduced, if it is a curved surface shape or a square shape. Conversion conditions for obtaining the back-through shape from the product shape are set in advance, such as translation, and when generating the back-through shape, the mold shape is divided into multiple island shapes, and each island shape The product shape pattern to be checked is examined, and the back-through shape is obtained according to the conversion conditions according to it, and the back-through shape for each island shape is synthesized, so the back-through shape is easily generated. .

  And according to the apparatus shown in FIG. 1, the data which set the conversion conditions for calculating | requiring a back shape from a product shape for every several types of product shape patterns AD are previously stored in the memory | storage device 2, and the thickness factor data 22 And using the wall thickness factor data 22, the inside-out shape generating means 15 in the arithmetic processing apparatus 1 automatically executes the method shown in FIGS. 5 and 6 to generate the inside-out shape. . Further, the backside shape generation means 15, the feature generation unit 13 constituting the basic shape generation means, and the backside data composition unit 17 constituting the final mold shape generation means automatically convert the mold shape including the backside shape. Therefore, it will be generated efficiently.

  In addition, when a partial design change of the product shape is performed, it is necessary to change the feature model FM2 corresponding to the backside shape along with the change of the feature model FM1 corresponding to the basic mold shape. In this case, it is possible to obtain the reverse shape only for the island shape of the design change portion, and use the data of the feature model FM2 before the change as it is for the other portions. Therefore, the feature model FM2 can be easily and efficiently changed according to the partial design change of the product.

It is a block diagram which shows the structure of the production | generation apparatus of the casting_mold | template shape by one Embodiment of this invention. It is explanatory drawing which shows the conversion conditions which obtain | require a back shape from a product shape so that predetermined | prescribed thickness may be given for every product shape pattern which classified the product shape into multiple types. It is a figure which shows the shape which looked at the casting_mold | template (sand mold) from the back side, Comprising: (a) is a casting_mold | template shape before slicing data synthesis | combination, (b) shows the final casting_mold | template shape after slicing data synthesis. . It is an expanded sectional view of a mold shape. It is a part of flowchart which shows the method of the backside shape production | generation by the backside shape production | generation means of an arithmetic processing unit. It is the remaining part of the flowchart. It is explanatory drawing which shows the reference plane and shape surface in a mold shape. It is explanatory drawing which shows the angle | corner which a reference surface and a shape surface make, and the centerline of a boss | hub or a rib.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Arithmetic processing apparatus 2 Memory | storage device 3 Input device 13 Feature production | generation part (basic shape production | generation means)
15 Backline shape generation means 15a Feature setting unit (division means)
15b Feature type selection unit (selection means)
15c feature generation unit (intra-zone backside shape generation means)
15d Feature composition unit (composition means)

Claims (3)

In a method of generating a mold shape including a backside shape of a mold that forms the outer periphery of a cast product,
Based on a three-dimensional model of the product in the area corresponding to a single mold, a basic shape generation process for generating a mold basic shape having a shape surface corresponding to the product shape, and a backside shape generation for generating a backside shape of the mold And a step of synthesizing the mold basic shape and the backside shape,
As a preliminary process for generating the above-mentioned back-through shape, a plurality of types of product shape patterns in which the shape of each part of the product is categorized are determined, and a predetermined thickness is given for each product shape pattern. Set the conversion conditions for finding the backside shape,
In the backside shape generation step, the product shape by the three-dimensional model is divided into a plurality of areas, and for each of the areas, the product shape in the area corresponds to one of the above-described multiple types of product shape patterns, Mold shape generation characterized by determining the backside shape based on the above conversion conditions according to the corresponding product shape pattern, and then combining the determined backside shape of each area to obtain the backside shape of the entire mold Method.   In the preliminary processing, as a plurality of types of product shape patterns, a concave shape pattern that is concave with respect to a predetermined reference surface, a convex shape pattern that is convex with respect to the reference surface, and the reference surface A curved surface shape pattern that is a gentle curved surface and a square shape pattern that includes a square shape portion are set, and conversion conditions for each product shape pattern are based on the approximate center position of the concave shape from the concave shape pattern. By enlarging, a back-through shape is obtained, and from the convex shape pattern, the back-through shape is obtained by reducing the approximate center position of the convex shape, and the shape is determined from the curved shape pattern and the square shape pattern. 2. The mold shape generation method according to claim 1, wherein the back-cut shape is obtained by parallel movement in the direction. In an apparatus for generating a mold shape including a backside shape of a mold that forms the outer periphery of a cast product,
A basic shape generating means for generating a basic shape of a mold having a shape surface corresponding to a product shape based on a three-dimensional model of a product in a region corresponding to a single mold;
A backside shape generating means for generating a backside shape of the mold;
Mold final shape generation means for generating the final shape of the mold by synthesizing the mold basic shape and the backside shape,
Thickness factor that sets conversion conditions for determining the backside shape from the product shape so as to define multiple types of product shape patterns that categorize the shape of each part of the product and give a predetermined thickness for each product shape pattern Storage means for storing data,
The inside-out shape generation means includes a dividing means for dividing the product shape by the three-dimensional model into a plurality of areas,
For each area divided by this dividing means, the product shape in the area and the above-mentioned multiple types of product shape patterns are compared, and the selecting means for selecting the corresponding product shape pattern,
The conversion condition corresponding to the product shape pattern selected by the selection means is determined from the thickness factor data, and the inside-back shape generation means for generating the reverse shape for each area according to the conversion condition;
An apparatus for generating a mold shape, comprising: a combining means for combining the back-through shape of each area obtained by the inside-back shape generating means in the area to obtain the back-back shape of the entire mold.

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