JP2007233972A - Three-dimensional shape data creation device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device that can easily create three-dimensional shape data on a three-dimensional object produced with the surface of the three-dimensional object partly offset in the thickness direction of the three-dimensional object, from non-offset three-dimensional shape data on the three-dimensional object. <P>SOLUTION: The three-dimensional shape data creation device has means for inputting non-offset three-dimensional shape data, means for selecting an offset face area, means for specifying an offset level, means for dividing the offset face area into a plurality of face elements, means for calculating coordinate data on each nodal point with the face elements offset in a normal direction by the specified offset level, means for correcting the coordinate data to create offset face data, means for dividing a gradational area into a plurality of face elements, means for calculating coordinate data on each nodal point of the face elements of the gradational area, and means for creating face data with the gradational area smoothed from the calculated coordinate data on each nodal point. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an apparatus for creating 3D shape data of a 3D object. Specifically, an apparatus for creating 3D shape data of a 3D object obtained by offsetting a part of the surface of the 3D object in the thickness direction of the 3D object from the 3D shape data of the 3D object before the offset About. Here, the “thickness direction” means the normal direction of the offset surface among the surfaces constituting the three-dimensional object.

In recent years, CAE (Computer Aided Engineering) has been used to determine product shape and mold specifications. In this type of technology, an analysis model is usually created based on shape data created by CAD (computer-aided design) or shape data obtained by actually measuring an actual product. Then, a simulation using the analysis model is performed, and the product shape and product specifications are determined based on the simulation result. By using the CAE technology, the number of product prototypes can be reduced and the design can be performed efficiently.
Patent Document 1 discloses an example of this type of CAE technology. In the technique of Patent Document 1, the shape of an actually produced mold is measured to create an analysis model of a molded product, and a simulation for countermeasures against molding defects is performed using the created analysis model.

JP 2005-196245 A

When determining the product shape and the mold specifications using the above-described CAE technology, it is sometimes desired to partially change the product thickness. For example, when determining the specifications of a mold used for resin injection molding, a simulation is performed based on the plate thickness distribution and gate arrangement temporarily set by the designer. As a result of the simulation, when a molding defect (for example, an air trap, a flow mark, etc.) occurs in the molded product, a measure is taken to partially change the product thickness. In such a case, in order to confirm whether or not a measure for partially changing the plate thickness is appropriate, an analysis model is created for the molded product after the plate thickness change, and a simulation is performed. Therefore, it is necessary to create an analysis model for the product after changing the plate thickness. Conventionally, in order to create an analysis model of a product in which the plate thickness is partially changed, the shape data before the plate thickness change created by CAD is changed on CAD, and the analysis model of the analysis model is based on the changed shape data. I was making it.
However, the work of correcting the plate thickness on CAD must be performed manually, and the plate thickness of the product is partially changed, and the level difference between the plate thickness changed portion and the portion where the plate thickness is not changed is made smooth. This required a lot of man-hours. In particular, in order to correct 3D shape data (that is, solid data) created by 3D CAD (hereinafter referred to as 3D-CAD) on 3D-CAD, many man-hours are required due to the characteristics of 3D-CAD. It cost. That is, in 3D-CAD, the commands available to the operator are limited, and the operator creates and changes solid data by using these commands in various combinations. For this reason, the operation | work which changes the plate | board thickness of a product partially is also performed by an operator using combining various commands. For this reason, it is difficult to smoothly connect the thickness change portion and the thickness non-change portion depending on how the operator uses the command and the order of the commands to be used, and these portions are twisted and connected. This necessitates the use of additional commands to correct these twists. Therefore, it takes a lot of time to obtain the final product shape data.

  The present invention has been made in view of the above situation, and the three-dimensional shape data of a three-dimensional object obtained by offsetting a part of the surface of the three-dimensional object in the thickness direction of the three-dimensional object is pre-offset. An apparatus that can be easily created from the three-dimensional shape data of the three-dimensional object is provided.

The apparatus of the present invention creates 3D shape data of a 3D object obtained by offsetting a part of the surface of the 3D object in the thickness direction using the 3D shape data of the 3D object before offset. . The three-dimensional shape data is composed of surface data of each surface constituting the three-dimensional object, and represents the three-dimensional shape by recognizing the closed space closed by the surface represented by the surface data as a solid. . Therefore, in order to create 3D shape data of a 3D object obtained by offsetting a part of the surface of the 3D object in the thickness direction, it is only necessary to create surface data of the offset surface. This is because the surface other than the offset surface is not different from the surface data of the three-dimensional object before the offset. Therefore, if the surface data of the offset surface is created, the 3D shape data of the 3D object after the offset can be created. Therefore, the apparatus of the present invention has a configuration schematically shown in FIG.
The apparatus shown in FIG. 18 includes an input unit 1, an offset surface selecting unit 2, and an offset amount designating unit 4 for inputting data necessary for creating post-offset three-dimensional shape data. That is, the input unit 1 inputs the three-dimensional shape data before the offset (for example, the three-dimensional shape data 100). The offset surface area selection unit 2 selects a surface area (for example, the area 102) to be offset of the three-dimensional object to be offset. The offset amount specifying means 4 specifies an offset amount (for example, an offset amount t).
The apparatus includes the following means for creating three-dimensional shape data after offset using data input, selected or designated by these means.
The first dividing means 3 divides the selected offset surface area into a plurality of surface elements. For example, the region 102 selected by the offset surface region selection unit 2 is divided into a plurality of minute surface elements.
The first coordinate data calculation means 5 offsets the coordinate data of each node when each of the divided surface elements is offset by an offset amount specified in the normal direction of the surface element. Calculate from the previous 3D shape data and the specified offset amount. Then, the first surface data creation means 6 corrects the coordinate data group calculated by the first coordinate data calculation means 5 so that the coordinate data of the corresponding nodes of the adjacent surface elements coincide with each other, and is offset. Create surface data after offset of surface area. For example, for each surface element obtained by dividing the region 102, the surface element is offset by an offset amount t specified in the normal direction, and the surface elements after the offset are connected (surface data) Surface data of the upper surface (106, 108) of the original object 104 is obtained.
The second dividing means divides the gradual change region set near the boundary line between the offset surface region and the non-offset surface region into a plurality of surface elements. For example, the gradual change region 110 set near the boundary line between the offset surface region 106 and the non-offset surface region 108 of the three-dimensional object 104 is divided into a plurality of minute surface elements.
The second coordinate data calculation means 8 calculates the coordinate data of each node of the surface element from the surface data after the offset and the three-dimensional shape data before the offset for each of the surface elements of the gradually changing region. . Then, the second surface data creating means 9 creates surface data obtained by smoothing the gradually changing region from the coordinate data of each node calculated by the second coordinate data calculating means 8. For example, the coordinate data 112 calculated by the second coordinate data calculation unit 8 is smoothed to obtain the coordinate data 114, thereby creating surface data of the gradually changing region 110.
When the surface data of the gradual change area is generated by the second surface data generating means 9, the surface data of the offset surface is specified. Thereby, the three-dimensional shape data 116 of the three-dimensional object after the offset is created.

  This 3D shape data creation device creates 3D shape data of an offset 3D object by simply inputting the 3D shape data before offset, selecting the area to be offset, and specifying the offset amount. Is done. For this reason, desired three-dimensional shape data can be obtained easily and in a short time. Moreover, an analytical model can be created from the obtained three-dimensional shape data, and the analytical model can be used for simulation.

  In the above-described 3D shape data creation device, the first coordinate data calculation means 5 calculates the coordinate data of each node of each surface element and the normal direction data of each surface element from the 3D shape data before the offset, Using the calculated coordinate data, normal direction data, and offset amount, the coordinate data of each node of each surface element after offset can be calculated. According to such a configuration, since the surface element is offset in the normal direction of the surface element for each surface element, the offset surface after the offset can be appropriately expressed.

  Further, in the above-described three-dimensional shape data creation device, the second coordinate data calculation unit 8 calculates the coordinate data of the nodes in the offset surface area in the gradual change area using the surface data after the offset, and before the offset. The coordinate data of the node in the non-offset area in the gradual change area can be calculated using the three-dimensional shape data.

The main features of the embodiments described in detail below are listed first.
(Mode 1) A three-dimensional CAD device that creates 3D-CAD data is used as input means for inputting three-dimensional shape data before offset. The three-dimensional CAD device and the three-dimensional shape data creation device are connected by a communication line. Three-dimensional CAD data (three-dimensional shape data) designed by the three-dimensional CAD device is input to the three-dimensional shape data creation device.
(Mode 2) The three-dimensional shape data creation device includes a display device that displays a three-dimensional object represented by the input three-dimensional shape data. The offset surface area selection unit selects a surface area to be offset on the three-dimensional object displayed on the display device.
(Mode 3) The three-dimensional shape data creation device has an input device for designating (inputting) an offset amount.
(Mode 4) The first dividing means divides the selected offset surface region into triangular microsurface elements.
(Mode 5) The first coordinate data calculation means calculates the coordinate data of each node of each surface element and the normal direction data of each surface element from the three-dimensional shape data before the offset, and the calculated coordinate data and normal line The coordinate data of each node of each surface element after the offset is calculated using the direction data and the offset amount.
(Mode 6) The first surface data calculation means matches the coordinate data of the corresponding nodes of the adjacent surface elements by an averaging method.
(Mode 7) The second dividing means divides the gradual change region into triangular minute surface elements.
(Mode 8) The second coordinate data calculation means calculates the coordinate data of the node on the offset surface area side in the gradually changing area using the surface data after the offset, and gradually changes using the three-dimensional shape data before the offset. The coordinate data of the node on the non-offset surface area side in the area is calculated.
(Mode 9) The second surface data creating means selects one or a plurality of nodes from a plurality of nodes in the offset surface region in the gradual change region (hereinafter, the selected node is the first node). 1 node). For each first node, one or a plurality of nodes are selected from a plurality of nodes in the non-offset surface region in the gradual change region (hereinafter, the selected node is referred to as a second node). For each first node, a cross section obtained by connecting the first node and the second node selected corresponding to the first node is specified. For each identified cross section, several nodes on the surface are moved so that the surface is smoothed, and coordinate data of the moved nodes is calculated. When there are a plurality of coordinate data corresponding to the same node, the coordinate data is corrected so as to coincide with each other, and surface data of the gradually changing region is created.
(Mode 10) The second surface data creation means selects a plurality of second nodes from the nodes on the boundary line between the gradual change region and the outside of the gradual change region for one first node.
(Mode 11) The second surface data creation means corrects each coordinate data of corresponding nodes by averaging.
(Mode 12) The surface data creation means corrects the surface data of the offset surface region after the offset and / or the surface data of the gradually changing region after the offset using the three-dimensional shape data before the offset.

A three-dimensional shape data creation apparatus 10 according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a schematic configuration of a three-dimensional shape data creation apparatus 10. As shown in FIG. 1, the three-dimensional shape data creation device 10 includes a computer 30, a display 12 that displays an image, a keyboard 14 that inputs data to the computer 30, and an arbitrary screen within a screen displayed on the display 12. The mouse 16 for designating the position, the memory 18 for storing various data, and the CAD data input device 20 for inputting 3D-CAD data to the computer 30 are configured.
The three-dimensional shape data creation apparatus 10 converts 3D-CAD data of a three-dimensional object obtained by offsetting a part of the surface of the three-dimensional object in the thickness direction (hereinafter referred to as a three-dimensional object after offset) into CAD data. The computer 30 generates 3D-CAD data (data of a three-dimensional object before offset) input from the input device 20.
Here, 3D-CAD data created by the three-dimensional shape data creation apparatus 10 will be described. 3D-CAD data defines the surface shape of a three-dimensional object by a plurality of surface data (planar data, curved surface data), and recognizes the inside of the space surrounded by the surface data as a solid. 3D shape data defining a 3D shape. By processing the 3D-CAD data by the computer 30, the shape of the three-dimensional object based on the 3D-CAD data is displayed on the display 12.

  As the CAD data input device 20, a CAD device that performs 3D-CAD (three-dimensional design) is used. The CAD data input device 20 is connected to the computer 30 via a communication line (for example, a LAN line). The 3D-CAD data created by the CAD data input device is input to the computer 30 via a communication line. The CAD data input device 20 may be a device that reads 3D-CAD data stored in a recording medium such as a CD-ROM.

  The display 12 includes a display screen and a circuit that activates the display screen. The display 12 displays an image on a display screen based on a signal output from the computer 30. For example, the computer 30 displays a three-dimensional object obtained by processing 3D-CAD data on the display screen.

  The keyboard 14 is an input device having a large number of input switches. A command value is input to the computer 30 by the operator operating these input switches.

  The mouse 16 is an input device including an input switch and an input roller, and designates an arbitrary position in the screen displayed on the display 12. The operator operates the input switch or moves the mouse 16 on the desk to move the input roller, whereby a command value is input to the computer 30.

  The memory 18 includes a ROM, a RAM, a hard disk, and the like. The memory 18 stores data input from the computer 30. Data stored in the memory 18 is read by the computer 30. The memory 18 stores a program and various data for the computer 30 to create 3D-CAD data of the three-dimensional object after offset from the 3D-CAD data of the three-dimensional object before offset. For example, data defining a gradual change region B set in the vicinity of a boundary line between an offset surface region A and a non-offset surface region described later is stored. The memory 18 stores a program for selecting one first node from the offset surface area A and selecting a plurality of second nodes from the nodes on the boundary line between the gradual change area B and the outer area. Yes.

  The computer 30 is constituted by a microprocessor having a CPU, a ROM, and a RAM. The computer 30 calculates various data stored in the ROM, RAM, memory 18 and the like in the computer 30 based on command values input from the keyboard 14 and the mouse 16. The computer 30 creates 3D-CAD data of the three-dimensional object after offset from the 3D-CAD data of the three-dimensional object before offset. By executing various programs, the computer 30 executes an offset surface area selecting unit 40, an offset amount specifying unit 42, a first dividing unit 44, a first coordinate data calculating unit 46, and a first surface data creating unit 48. And the second dividing means 50, the second coordinate data calculating means 52, and the second surface data creating means 54.

  Next, the operation when the 3D shape data creation apparatus 10 creates 3D-CAD data of the post-offset 3D object from the 3D-CAD data of the 3D object before offset will be described with reference to FIG. To do.

When creating 3D-CAD data of a three-dimensional object after offset by the three-dimensional shape data creation device 10, first, the 3D-CAD data of the three-dimensional object 22 before offset from the CAD data input device 20 is sent to the computer 30. input. The 3D-CAD data input to the computer 30 is processed by the computer 30, whereby the shape of the three-dimensional object before offset is displayed on the display 12.
FIG. 3 shows an example of the three-dimensional object 22 displayed on the display 12. As shown in FIG. 3, the display 12 displays surfaces 23, 27, and 28 when the three-dimensional object 22 is viewed from a certain viewpoint. Note that the viewpoint for viewing the three-dimensional object 22 can be changed by operating the keyboard 14 and / or the mouse 16.

When the 3D-CAD data of the three-dimensional object 22 before the offset is input to the computer 30, the operator operates the keyboard 14 and the mouse 16 to select from the surfaces 23, 27, 28, etc. constituting the three-dimensional object 22. The surface to be offset and its area are selected (step S2).
That is, the computer 30 first displays a message on the display 12 asking the operator to select an area to be offset. When the message is displayed on the display 12, the operator operates the keyboard 14 and the mouse 16 so that the surface on which the three-dimensional object is offset is displayed on the display 12. For example, when the surface 23 of the three-dimensional object 22 shown in FIG. 3 is offset, the viewpoint is changed so that the offset surface 23 is displayed on the upper side.
Next, the operator operates the mouse 16 to select a surface area from the surface to be offset of the displayed three-dimensional object. Specifically, the operator operates the mouse 16 to sketch a region to be offset to a part of the surface to be offset. For example, as shown in FIG. 4, a region A to be offset on the offset surface 23 of the three-dimensional object 22 is sketched.
When the area to be offset is sketched by the operator, the computer 30 sets the sketched area as an offset surface area (area indicated by A in the example of FIG. 4). At the same time, the computer 30 sets the gradual change region B based on data defining the gradual change region B (the region indicated by B in the example of FIG. 4) stored in the memory 18. In the present embodiment, a range of a predetermined distance is set as the gradual change region from the boundary line of the offset surface region toward both the offset side and the non-offset side. In the example shown in FIG. 4, the gradual change region B includes the entire offset surface region A, and a region wider than the offset surface region A by a predetermined range is set on the non-offset surface side.

  When the offset surface area and the gradual change area are set by the computer 30, the operator operates the keyboard 14 and the mouse 16 to specify an amount and an offset direction for offsetting the offset area (step S <b> 4). That is, the computer 30 displays a message for requesting the operator to input the offset amount and the offset direction on the display 12. The operator inputs the offset amount and the offset direction by operating the keyboard 14. The computer 30 stores the input offset amount and offset direction in the RAM. The offset direction is specified by setting the offset amount to a positive or negative value. In this embodiment, a positive value means that the plate thickness of the three-dimensional object 22 is increased, and a negative value means that the plate thickness of the three-dimensional object 22 is reduced. .

When the offset amount is designated, next, the computer 30 divides the plane data in the offset plane area into a large number of minute triangular planes (step S6). As a program for dividing the offset surface area into a plurality of minute triangular planes, conventionally known software for dividing the surface data of the 3D-CAD data into minute surface elements can be used.
FIG. 5 shows an example in which the offset surface area A set on the three-dimensional object 22 is divided into a plurality of minute triangular planes 24. As is clear from the figure, each generated microtriangular plane 24 shares a node (a vertex of a triangle) with the adjacent microtriangular plane 24.

  When the offset surface area is divided into a large number of minute triangular planes, the computer 30 calculates the coordinate data of each node of each minute triangular plane (step S8). For example, in the example illustrated in FIG. 5, the computer 30 first specifies the surface data of the surface 23 to be offset from the 3D-CAD data input from the CAD data input device 20, and each micro triangular plane is determined from the surface data. The coordinate data of the node is calculated. The calculated coordinate data of the nodes is represented by three-dimensional coordinates of x, y, and z.

  Once the coordinate data of each node is calculated, the computer 30 then calculates the normal direction of each minute triangular plane from the coordinate data of each node on the minute triangular plane (step S10). More specifically, the computer 30 calculates a unit normal vector V in the normal direction of the minute triangular plane from the coordinate data of each node on the minute triangular plane. At this time, the computer 30 reads the offset amount stored in step S4 and specifies the offset direction. That is, when the read offset amount is a positive value, the unit normal vector V is calculated in the direction of increasing the thickness of the three-dimensional object. When the read offset amount is a negative value, the unit normal vector V is calculated in the direction of decreasing the thickness of the three-dimensional object. The computer 30 calculates the unit normal vector V for all small triangular planes.

  When the unit normal vector V of each minute triangular plane is calculated, the computer 30 uses the unit normal vector V, the coordinate data of each node, and the offset amount read in step S10 to each minute triangular plane after the offset. The coordinate data of each node is calculated (step S12). That is, the computer 30 calculates coordinate data in which each node of each minute triangular plane is offset by an offset amount in the normal direction of the minute triangular plane. If the coordinate data of the node to be offset is (x1, y1, z1), the unit normal vector V is (xv, yv, zv), and the offset amount is P, the coordinate data (x2, y2, z2) is calculated by the following calculation formula.

The computer 30 calculates the coordinate data of the nodes after the offset for all the nodes on all the minute triangular planes. As described above, each minute triangular plane shares a node with the adjacent minute triangular plane. Accordingly, for the same node, the coordinate data of the node after offset is calculated from a plurality of small triangular planes sharing the node.
This will be specifically described with reference to FIGS. 10 and 11 show six minute triangular planes sharing the node 60, FIG. 10 shows a state before offset, and FIG. 11 shows a state after offset. FIG. 13 is a diagram illustrating a state before and after the offset of the cross section taken along the line XIII-XIII in FIG. 10.
When the node 60 is offset in the normal direction of the minute triangular plane 62, the coordinate data of the node 60a is calculated as shown in FIG. When the node 60 is offset in the normal direction of the minute triangular plane 64, the coordinate data of the node 60b is calculated. When the same calculation is performed on all the small triangular planes sharing the node 60, the offset nodes 60a to 60f corresponding to the node 60 before the offset are calculated as shown in FIG. In this way, by offsetting the same node in the normal direction of different planes, coordinate data of a plurality of corresponding nodes after offset are calculated from one node.
In the examples shown in FIGS. 11 and 13, the state when the small triangular plane is offset in the direction of increasing the plate thickness is illustrated, but when the small triangular plane is offset in the direction of decreasing the plate thickness. Also, the above-described processing is executed. Also, in the drawings referred to in the following description, only the state in which the thickness is offset in the direction of increasing the thickness is illustrated, but the offset in the direction of increasing the thickness is also performed in the case of offsetting in the direction of decreasing the thickness. The same processing as that is performed is performed.

When the coordinate data after offset of each node of each minute triangular plane is calculated, the computer 30 corrects the coordinate data after offset of the corresponding node of the adjacent minute triangle plane to match (step S14). . That is, the computer 30 averages the coordinate data of each node after the offset corresponding to one node before the offset. For example, in the case of FIGS. 11 and 13, the coordinate data of the nodes 60a to 60f are averaged to calculate the coordinates of the node 60g. Then, as shown in FIG. 12, adjacent minute triangular planes share the node 60g again.
When the computer 30 performs the above-described correction on all the nodes after the offset, adjacent minute triangular planes share the corrected nodes. As a result, surface data is generated when the offset region is offset by a predetermined amount in the normal direction.
For example, when the offset area A shown in FIG. 5 is offset by the offset amount P, the computer 30 performs the above-described processing, thereby creating the surface 25 shown in FIG. As described above, the surface 25 after the offset is an averaged surface obtained by moving each node of the surface 24 before the offset by the offset amount P in the normal direction of each minute triangular plane. Therefore, the surface 25 after the offset is a surface obtained by moving the surface 24 before the offset by the offset amount P in the thickness direction. As is apparent from FIG. 6, a gap is generated between the surface 25 and the surface 23 after the offset.

  When the computer 30 forms the surface data after the offset, the computer 30 corrects the surface data based on the curvature of the offset surface area A before the offset (step S16). In the example of FIG. 6, the surface 25 after the offset is corrected to become a smooth curved surface as shown in FIG. Further, the computer 30 sets side surfaces 80, 82 and the like that close a gap between the surface 25 after the offset and the surface 23 before the offset, and the surface 25 after the offset, the side surfaces 80, 82, and the like, A closed space surrounded by the surface of another three-dimensional object 22 is formed. The closed space is recognized as a solid and becomes 3D-CAD data.

When the 3D-CAD data after the offset is created, the computer 30 divides the plane data in the gradually changing area of the 3D-CAD data after the offset into a large number of minute triangular planes (step S18). For example, when the gradual change region B shown in FIG. 7 is divided into minute triangular planes, the gradual change region B becomes a surface (surface before smoothing) in which a large number of minute triangular planes 29 are combined as shown in FIG.
It should be noted that conventionally known software can be used for dividing the gradual change region B into the minute triangular planes by the computer 30 as in step S6.

  When the gradually changing region is divided into a large number of minute triangular planes, the computer 30 calculates coordinate data of the nodes of each minute triangular plane (step S20). That is, the computer 30 calculates the coordinate data (x, y, z) of the nodes on each minute triangular plane from the offset 3D-CAD data created in step S16.

  When the coordinate data of each node in the gradual change area is calculated, the computer 30 selects a reference node and a second node for smoothing the gradual change area (step S22). In this embodiment, one node on the offset surface area side in the gradual change area is selected as the reference node, and all the nodes on the boundary line of the gradual change area are selected as the second nodes. This will be specifically described with reference to the example shown in FIG. As shown in FIG. 8, the computer 30 selects one node (for example, the node 66) from the offset surface area A (that is, on the surface data 25 after the offset) as a reference node, and the boundary of the gradual change region B. All nodes on the line (for example, node 68 etc.) are selected as the second nodes.

When the computer 30 selects the reference node and the second node in step S22, the computer 30 first specifies a cross section obtained by connecting the reference node and each second node. Next, coordinate data obtained by moving each node on the surface of the cross section so as to smooth the surface of the cross section is calculated for each specified cross section (step S24).
Specifically, with reference to the example shown in FIG. 8, the computer 30 connects the reference node 66 and the second node 68 to specify the cross section 70, and smoothes the area within a predetermined range from the cross section 70. Set as. As shown in FIG. 8, the cross section 70 intersects a plurality of dividing lines (lines for dividing the gradual change region B into a plurality of minute triangular planes). The coordinate data is not calculated except for the nodes on the minute triangular plane among the intersections (for example, 72 in FIG. 8) of the cross section 70 and the plurality of dividing lines. The computer 30 calculates the coordinate data of each intersection based on the coordinate data of the node adjacent to the intersection. For example, the coordinate data of the intersection 72 in FIG. 8 is calculated based on the coordinate data of the nodes 74 and 76. Specifically, the coordinate data of the node 74 is (x3, y3, z3), the coordinate data of the node 76 is (x4, y4, z4), the distance between the intersection 72 and the node 74 is l, and the distance between the intersection 72 and the node 76 is Is set to m, the coordinate data (x5, y5, z5) of the intersection 72 is calculated by the following calculation formula.

When the coordinate data of all the intersections on the cross section 70 is calculated in this way, the shape of the cross section 70 is specified as shown in FIG. The computer 30 moves all the nodes or intersections except for the reference node and the second node on the cross section 70 in the direction of smoothing the surface of the cross section 70, and the coordinate data of the moved nodes or intersections (coordinates after smoothing) Data) is calculated (see FIG. 15).
When the computer 30 calculates the coordinate data after smoothing the nodes or intersections on the cross section 70, the computer 30 calculates the coordinate data after smoothing the nodes (except for the nodes on the cross section 70) in the smoothing region C. In the calculation of the coordinate data after smoothing the node in the smoothing region C, the coordinate data of the node, the coordinate data of the node or intersection on the cross section 70 closest to the node, and the node or intersection are moved. Calculated based on the coordinate data. For example, the coordinate data (x6, y6, z6) after smoothing of the node 74 in FIG. 8 is the coordinate data (x3, y3, z3) of the node 74 before smoothing, and the intersection point on the cross section 70 closest to the node. 72 using the coordinate data (x5, y5, z5) before smoothing and the coordinate data (x7, y7, z7) after smoothing of the intersection 72 are calculated by the following calculation formula.

The computer 30 performs the above-described processing for all nodes in the smoothing region C, and calculates coordinate data after smoothing all the nodes in the smoothing region C.
The computer 30 executes the processing performed on the cross section 70 described above for all cross sections obtained by connecting the reference node and each second node. As is clear from FIG. 8, since adjacent smoothing regions C are set to overlap, a plurality of smoothed coordinate data are calculated for one node in the gradually changing region. It becomes.

  When the computer 30 calculates the coordinate data after smoothing each node in the gradual change area, the computer 30 averages a plurality of smoothed coordinate data calculated for the same node and corrects it to one coordinate data. (Step S26). When the computer 30 performs the above-described correction on all the nodes in the gradual change region, smoothed surface data of the gradual change region is formed by a large number of minute triangular planes formed by these nodes.

  When the computer 30 creates the surface data after smoothing in step S26, the computer 30 corrects each minute triangular plane to a smooth curved surface corresponding to the inclination with the adjacent minute triangular plane (step S28). For example, as shown in FIG. 16, the shape of the minute triangular plane 84 is corrected to a smooth curved surface corresponding to the adjacent minute triangular planes 86 and 88. When all the minute triangular planes are corrected as described above, the smoothed surface data 26 and the surface data 23 outside the gradual change region B are smoothly combined as shown in FIG.

As described above, according to the three-dimensional shape data creation device 10, first, 3D-CAD data of a three-dimensional object obtained by offsetting the offset surface area of the three-dimensional object before offset in the thickness direction is created. Next, by smoothing the surface data in the gradual change region B, the surface data in the gradual change region and the surface data outside the gradual change region B are smoothly combined, and after the smoothed offset Surface data can be obtained.
Of the plurality of surfaces constituting the three-dimensional object, the surfaces that are not offset (for example, the surfaces 27 and 28 shown in FIG. 9) are the same as the surfaces of the three-dimensional object before the offset. For this reason, when the surface data of the surface after the offset smoothed in step S28 is obtained, the surface data of all the surfaces defining the three-dimensional object after the offset are obtained. By recognizing that the closed space closed by these surface data is fixed, smoothed 3D-CAD data after offset is created.

The above-described three-dimensional shape data creation device 10 is used, for example, when designing a molding die for a molded product manufactured by injection molding. A molded product 90 in FIG. 17 is an example of a molded product manufactured by injection molding. The molded product 90 is a resin member used for bumpers such as automobiles. The design surface 92 of the molded product 90 is a design surface that is visually recognized by a consumer or the like when attached to an automobile or the like, and the back surface 94 is a back surface that is not visually recognized by the consumer or the like.
When designing a molding die of the molded product 90, first, 3D-CAD data of the molded product 90 is created. Then, CAE is executed based on the 3D-CAD data. In CAE, various conditions (temperature, pressure, resin inlet position, etc.) at the time of injection molding are set, and under these conditions, the resin flow path and the like when the molded product 90 is injection-molded are simulated. And the characteristic of the molded product 90 etc. are evaluated from a simulation result. As a result of evaluating the simulation result, when it is predicted that a molding defect will occur in the molded product 90, the type of the molding defect and the location where the molding defect occurs are specified. FIG. 17 shows that an air trap 96 is generated on the design surface 92 of the molded product 90.
As shown in FIG. 17, when it is found by simulation that there is a possibility that a defect such as an air trap 96 occurs on the design surface 92 of the molded product 90, the thickness of the back surface of the molded product 90 is partially changed. Measures are taken. That is, if the thickness of the molded product 90 is changed, the flow rate of the resin and the flow direction of the resin when the molded product 90 is injection-molded can be changed, and the occurrence of molding defects can be prevented. . In order to determine whether or not this measure is appropriate, it is preferable to perform simulation again.
Therefore, the 3D-CAD data after offset is created from the 3D-CAD data of the molded product before offset by the three-dimensional shape data creation apparatus 10 of the present embodiment. At this time, if the design surface 92 of the molded product 90 is offset, the shape of the design surface 92 is changed. Since the design surface 92 is a surface visually recognized by consumers and the like, and the design is important, it is not preferable to change the shape of the design surface 92. Therefore, the defective part (the part 98 corresponding to the air trap 96) of the back surface 94 is offset in the thickness direction.
When the 3D-CAD data after the offset is created, an analysis model is created again based on the 3D-CAD data, and a simulation is executed. As a result of the simulation, if it is confirmed that no defect occurs, the prototype is actually evaluated and evaluated. On the other hand, as a result of the simulation, if the problem is not resolved (including a case where a new problem is found), the creation and simulation of 3D-CAD data are repeated until the problem is resolved. In this way, by repeatedly changing the thickness of the CAE and 3D-CAD data, it is possible to design a molding die of a suitable molded product that does not cause molding defects.
Note that analysis software for the molded product 90 is installed in the above-described three-dimensional shape data creation apparatus 10 (that is, the computer 30 is provided with simulation means and evaluation means for evaluating the simulation result), and the three-dimensional shape data is obtained. The creation device 10 may perform simulation and evaluation of the simulation result. In addition, implementation of the simulation performed using a computer and evaluation of the simulation result are disclosed in detail in JP-A-2005-169766, and the configuration disclosed in this publication can be used.

As described above, according to the three-dimensional shape data creation device 10 of the present embodiment, the operator selects only a partial area of the surface to be offset of the three-dimensional object and inputs the offset amount. It is possible to create 3D-CAD data of a three-dimensional object obtained by offsetting the obtained surface region in the thickness direction of the three-dimensional object. Therefore, 3D-CAD data of the offset three-dimensional object can be created in a short time.
Further, according to the three-dimensional shape data creation device 10 of the present embodiment, 3D-CAD data of a three-dimensional object in which the vicinity of the boundary line between the offset surface and the non-offset surface of the three-dimensional object after offset is smoothed is created. The Therefore, even if an analysis model is created using 3D-CAD data after offset, simulation can be performed with high accuracy.

In this embodiment, the computer 30 sets the reference node on the offset surface area side, selects the second node on the non-offset surface side, and smoothes each section obtained by connecting the reference node and the second node. The surface data of the gradually changing region is created by averaging a plurality of coordinate data for the same node obtained by smoothing each cross section, but the present invention is not limited to such an embodiment. For example, the surface data of the gradual change region is created by a method in which a plane defined by the boundary line of the offset surface region A and the boundary line of the gradual change region B is used as the surface data after smoothing of the gradual change region B. be able to.
In this embodiment, one reference node is selected from within the offset surface area A, and a plurality of second nodes are selected from the nodes on the boundary line of the gradual change area B. However, the present invention is not limited to such an embodiment. Not limited. The reference node and the second node can be selected without departing from the present invention. For example, a plurality of reference points may be set on the offset surface side, and the same number of nodes may be set on the non-offset surface side with respect to the reference point. In addition, a reference node can be set at the center of the offset surface area, and the first node can be set so that the cross section is set at an equal angle with respect to the reference node.
In this embodiment, the coordinate data of the nodes is corrected by averaging a plurality of coordinate data calculated for the same node, but the present invention is not limited to such an embodiment. For example, each coordinate data of the corresponding node can be corrected by various other correction methods such as correcting the coordinate data of the node from the inclination of each minute triangular plane sharing the node.
In the present embodiment, the offset surface area A and the gradual change section B are divided into a large number of minute triangular planes, but may be divided into surfaces having other shapes.
In this embodiment, the gradual change region B is set so as to include the entire offset surface region A. However, the gradual change region B can be set by various other setting methods. For example, the gradual change region B can be set only near the boundary between the offset surface region A and the non-offset surface region.

Specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above.
The technical elements described in this specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology illustrated in the present specification or the drawings achieves a plurality of objects at the same time, and has technical utility by achieving one of the objects.

Block diagram of the three-dimensional shape data creation apparatus 10 of the present embodiment The flowchart which shows the process of the three-dimensional shape data creation apparatus 10 of a present Example. Schematic diagram of a three-dimensional object displayed by the three-dimensional shape data creation device 10 Schematic diagram of a three-dimensional object displayed by the three-dimensional shape data creation device 10 Schematic diagram of a three-dimensional object displayed by the three-dimensional shape data creation device 10 Schematic diagram of a three-dimensional object displayed by the three-dimensional shape data creation device 10 Schematic diagram of a three-dimensional object displayed by the three-dimensional shape data creation device 10 Schematic diagram of a three-dimensional object displayed by the three-dimensional shape data creation device 10 Schematic diagram of a three-dimensional object displayed by the three-dimensional shape data creation device 10 Enlarged view of the surface data displayed by the three-dimensional shape data creation device 10 Enlarged view of the surface data displayed by the three-dimensional shape data creation device 10 Enlarged view of the surface data displayed by the three-dimensional shape data creation device 10 Sectional view of surface data displayed by the three-dimensional shape data creation device 10 Sectional view of surface data displayed by the three-dimensional shape data creation device 10 Sectional view of surface data displayed by the three-dimensional shape data creation device 10 Sectional view of surface data displayed by the three-dimensional shape data creation device 10 Perspective view of molded product 90 Illustration of thickness change

Explanation of symbols

10: Three-dimensional shape data creation device 12: Display 14: Keyboard 16: Mouse 18: Memory 20: CAD data input device 30: Computer 40: Offset surface area selection means 42: Offset amount designation means 44: First division means 46: First coordinate data calculation means 48: first surface data creation means 50: second division means 52: second coordinate data calculation means 54: second surface data creation means

Claims (3)

An apparatus for creating 3D shape data of a 3D object obtained by offsetting a part of the surface of the 3D object in the thickness direction of the 3D object from the 3D shape data of the 3D object before offset. ,
Means for inputting the three-dimensional shape data before the offset;
An offset surface area selecting means for selecting a surface area to be offset of the three-dimensional object to be offset;
An offset amount specifying means for specifying an offset amount;
First dividing means for dividing the selected offset surface region into a plurality of surface elements;
For each of the divided surface elements, the coordinate data of each node when the surface element is offset by the offset amount specified in the normal direction of the surface element is designated as the three-dimensional shape data before offset. First coordinate data calculating means for calculating from the offset amount;
First, the coordinate data group calculated by the first coordinate data calculation means is corrected so that the coordinate data of the corresponding nodes of the adjacent surface elements coincide with each other to create surface data after offset of the offset surface area. One side data creation means;
A second dividing unit that divides a gradually changing region set in the vicinity of the boundary line between the offset surface region and the non-offset surface region into a plurality of surface elements;
Second coordinate data calculation means for calculating the coordinate data of each node of the surface element for each of the divided gradually changing areas from the surface data after offset and the three-dimensional shape data before offset;
Second surface data creating means for creating surface data obtained by smoothing the gradual change region from the coordinate data of each node calculated by the second coordinate data calculating means;
A three-dimensional shape data creation device characterized by comprising:   The first coordinate data calculation means calculates the coordinate data of each node of each surface element and the normal direction data of each surface element from the three-dimensional shape data before offset, and the calculated coordinate data, normal direction data and offset 2. The three-dimensional shape data creation apparatus according to claim 1, wherein coordinate data of each node of each surface element after offset is calculated using a quantity.   The second coordinate data calculation means calculates the coordinate data of the nodes in the offset surface area in the gradual change area using the surface data after the offset, and uses the three-dimensional shape data before the offset in the non-change area. 3. The three-dimensional shape data creation apparatus according to claim 1, wherein coordinate data of a node in the offset surface area is calculated.

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