JP2737125B2 - How to create cross-sectional shape data of an object - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described in the following order. A Industrial application B Outline of the invention C Conventional technology (Fig. 5) D Problems to be solved by the invention (Fig. 6) E Means for solving the problems (Fig. 2) F function ( (FIG. 2) G Example (G1) Principle of Sectional Shape Creation Method (FIGS. 1 to 3) (G2) Sectional Shape Creation Processing Procedure (FIGS. 1 to 4) (G3) Other Embodiments (FIG. 2) The present invention relates to a method for creating cross-sectional shape data of an object, particularly
This is suitable for application when creating a cross-sectional shape data of a desired object using a CAD (computer aided design) type design device. B SUMMARY OF THE INVENTION The present invention provides a method for creating cross-sectional shape data on the shape of an object to be designed, in which a part of the shape is transformed into a deformation curve based on the outline of the base while utilizing data input means and display means. Therefore, it is possible to easily realize a design device which is easy to use. C. Prior Art This type of design apparatus is used for designing industrial products, and a method for forming a desired curved surface in an xyz space is disclosed in Japanese Patent Application Laid-Open No. 58-22413. This method of creating a surface is based on sequentially selecting a surface having a radius of curvature within a predetermined error range from a plurality of adjacent nodes among a number of points designated in the xyz space (referred to as nodes). It is possible to generate a curved surface approximating a curved surface passing through the designated node as a whole. However, according to this method, since a surface that can be generated is limited to a surface represented by a quadratic function, a free-form surface having an arbitrary shape (which cannot be defined by a quadratic function) cannot be generated as necessary. It is still insufficient in point. As a method for solving this problem, there has been proposed a method of generating a free-form surface by using an expression represented by a B-spline function for sequentially adjacent nodes. A smooth free-form surface approximating an array can be generated. That is, as shown in FIG. 5, the designer has seven nodes. Is set in the xyz space, a smooth free curve K0 can be generated so as to approximately roughly follow a straight line connecting the adjacent contacts, and a point on the smooth free curve K0 can be generated. Is Can be obtained by solving the simultaneous equations here Therefore, the expressions (1) to (5) are Which can be transformed as Can be expressed in a matrix format as D. Problems to be Solved by the Invention However, according to this method, it is difficult to efficiently adapt to the design procedure of the designer when actually designing the shape of an industrial product. First, since the generated B-spline curve does not pass through the node specified by the designer, there is a disadvantage that the external dimensions of the generated free-form surface cannot be predicted at the stage when the designer specifies the node. In general, when actually designing an industrial product, as shown in FIG. 6, a cross section is assumed for a main part of the product, and the outer dimensions of the cross section (for example, the outer dimension L _{x1 in the} x direction and the outer dimension L _{x1 in the} y direction) are assumed. The outer dimension (represented by _Ly1 ) is often given as a basic design condition, and the designer must select nodes so as to satisfy all the conditions for such a cross-sectional shape. However, since the B-spline function generated as described above with reference to FIG. 5 does not pass through the node specified by the designer, the designer eventually ends the B-spline curve generated by repeatedly specifying the node by trial and error. When the shape and dimensions are displayed on the display and examined, and as a result the design conditions for the external dimensions cannot be satisfied, a complicated operation of resetting the nodes must be repeated. Secondly, as described above with reference to FIG. This means that even if an attempt is made to correct a part of the cross-sectional shape once the design is completed, the local correction cannot be performed, and only the entire correction can be performed. However, in practice, the design work of the designer usually involves making the external shape being created one step closer to the shape imagined by the design by repeating local modifications. , In this regard B
-The method of generating a cross-sectional shape using a spline curve is inconvenient because it does not seem to match the design procedure. Third, the B-spline curve is characterized in that, in principle, it generates a curve that satisfies the condition that the curvature is continuous and the tangent is continuous. For example, the B-spline curve has a small curvature such that it is adjacent to a curved portion having a large curvature. In some cases, even if an attempt is made to generate a curved portion, it cannot be actually generated. If an unreasonable node is specified, the generated outline curve is deformed to an unpredictable degree (for example, the curved portion K0X in FIG. 6). As shown in FIG. 2). The present invention has been made in view of the above points, and when a designer actually designs a cross-sectional shape, a free curve having the same external dimensions as a predetermined external dimension is created by the designer using data input means and data input means. It is an object of the present invention to propose a method of creating cross-sectional shape data of an object which can be generated by easily performing a design operation using a display means. E. Means for Solving the Problem In order to solve such a problem, in the present invention, the cross-sectional shape data of a desired object is obtained by using a design device based on a base outline K1 representing a rough cross-sectional outline shape. A method for creating cross-sectional shape data of an object to be created, wherein a step SP2 for inputting substrate outline data representing a substrate outline K1 having a cross-sectional outline shape by data input means and a substrate outline line K1 based on the outline shape data are displayed. Step SP displayed on the means
3 and a step S of setting control point data representing a plurality of control points _PDM for deformation on the outline of the base body by the data input means.
And P5, SP7, based on a plurality of deforming control point data, and generates a deformation curve data representing the deformation curve K2 by setting the curve segment data composed of Parametoritsuku space curves between deforming control point P _DM A step SP6 for displaying the deformation curve data as cross-sectional shape data on the display means, and a deformation curve K2 displayed on the display means.
, The sectional shape is corrected by the data input means. F action The base outline K1 representing a rough cross-sectional outline shape represents the outline dimensions of the cross-sectional shape to be created, while the deformation curve K2, which is a parametric space curve, is compared to the basic outline K1. By being able to generate and obtain a cross-sectional shape curve as a result of creation, the designer can use a data input means and a display means to locally generate a cross-sectional shape curve having an external dimension specified for the base external line K1. It can be created while making various modifications. G Example Hereinafter, an example of the present invention will be described in detail with reference to the drawings. (G1) Principle of Sectional Shape Creation Method In the sectional shape creation method according to the present invention, first, as shown in FIG. 1, a rough outline of a sectional shape to be generated is designated by a base outline K1. At this time, the external dimensions of each part can be designated. For example, in the case of FIG. 1, a polygonal outer shape line K1 having an outer size of _{Lx2 in} the x direction, an outer size of Ly2 in the y direction, and each line _segment formed by a straight line is designated. In this embodiment, the base outline K1 extends from the left and right ends of the lower side line K11 extending in the x direction upward in the y direction to the left side line K12.
And right line K13 is extended by the length L _y21 and L _y22, the upper end cutting line segment K14 and K15 inward length from section L _x21 and L
_{The cutting} line segments K17 and K18 extend from the inner end to the upper side line segment K16 by an extension of _x23 . After the rough external shape is designated by the designer as a polygonal basic outline K1 in this way, the designer then transforms each line constituting the basic outline K1 into a deformation curve K2 as shown in FIG. To modify the basic outline K1 into a shape as desired by the designer. This deformation curve K2 is generated by a Bezier curve representing a parametric free curve. In the case of FIG. 2, an arc-shaped deformation curve K2 is generated by the Bezier equation for each corner of the base outline K1. Therefore, the control points for deformation are on the line of the basic outline K1. Is set and the control point for deformation is set. A deformation curve K2 is generated in between. Here, the Bezier curve is represented by a control point for deformation on a basic outline K1 shown by a chain line in FIG. By setting the two control points for deformation A curved segment K _SG is formed between each curved segment K _SG
Is a cubic Bezier equation such as Like a parametric space curve Is expressed using. Here, t is the deformation of the ends of the curve segment K _SG 0 ≦ t ≦ 1 (15) These parameters change from 0 to 1. The curve segment K _SG represented by the cubic Bezier curve in this way is converted by the shift operator E into the reference control point. as well as By specifying, each point on the curve segment K _SG is Position vector from the origin 0 in xyz space by the expansion formula of It is expressed as Where the shift operator E is the control point on the curve segment K _SG For With the relationship Therefore, by expanding equation (14) and substituting the relationship of equation (17) , And as a result, the equation (16) is obtained. Thus, all curve segments K on the deformation curve K2
_SG has four control points based on equation (16). Which means that the two reference controls on the deformation curve K2 Can be set to an arbitrary value as required, and accordingly, the shape of the curve segment _KSG can be set locally and as an arbitrary free curve. Moreover as is clear from FIG. 2, on the basis of the data of the basic outline K1 comprising a polygonal shape designer entered (FIG. 1), a pair for determining the scope of the curve segment K _SG on the basic outline K1 Reference control point Can be specified, a curve inscribed in practice to the basic outline K1 can be generated as the deformation curve K2, and thus the designer can design a desired shape within the range of the outline dimensions determined in advance as design conditions. it can. In addition to this, the curve segment K _SG can be formed for each curve segment regardless of the current state of the adjacent curve segment, in principle, without restricting the shape based on this. _Even a shape having sharp corners between _SGs (for example, a case where arcs having extremely different radii are formed adjacent to each other) can be easily generated. (G2) Cross-sectional Shape Creation Processing Procedure Based on the principle of the above-described cross-sectional shape creation method, the design apparatus creates a cross-sectional shape according to the processing procedure shown in FIG. That is, when entering the cross-sectional shape creation processing program in step SP1, the design apparatus waits for the input of the basic outline data of the cross-sectional polygonal shape in step SP2. At this time, the design can input the rough shape of the cross section as a polygonal shape by inputting the coordinate data of the term points at both ends of each line segment forming the basic outline K1 described above with reference to FIG. When the data input is completed, the design device
Move to SP3, input vertex data for each line segment K11-K18
After the outer shape connected by the above is displayed on the display, the process proceeds to the next step SP4. This step SP4 is a step of waiting for whether or not to specify the deformation curve K2 having the same radius at the corner portion at each vertex position of the basic outline K1. Enter the command. When a positive result is obtained in step SP4, the design apparatus goes to step SP5 and waits for the designer to input and specify the above-described radius data for all corners. Move on. On the other hand, when a negative result is obtained in step SP4, the design apparatus moves to step SP7 and waits for the designer to input and specify the radius data for each corner portion. When the specification of the data is completed, the design device proceeds to step SP6. Move on to In practice, the designer uses the control points for deformation on the basic outline K1 in steps SP5 and SP7. By specifying the Specify the area in which the curve segment _KSG is to be generated in between and specify the deformation set for each corner Deformation curve an arc of predetermined radius as a line segment K _SG K2
Will be input. Thus, the design device is in a state where the data representing the deformation curve K2 has been locally input for the corner portion while using the data of the polygonal basic outline K1, and the design device has entered the input data at step SP6. By executing the above-described calculations on the equations (14) to (19) based on the above, data representing the deformation curve K2 is generated by specifying the parameter t at predetermined intervals. As a result of such calculation, the design device is in a state in which deformation curve data including the data of the straight line portion input for the basic outline K1 and the data of the deformation curve K2 calculated for the corner portion is generated. Displays this data on the display as cross-sectional shape data in the next step SP8. Thus, the designer can visually confirm the cross-sectional outer shape formed so as to be inscribed in the basic outer shape line K1 on the display screen of the display, and then, to partially correct the displayed outer shape. While inputting the processing data, a step-by-step design is performed on a cross-sectional outer shape having a desired shape. That is, in the next step SP9, the design device
Waits for the designer to determine whether or not to correct the straight line portion of the basic outline K1 that has not been deformed by the above processing, and inputs a correction command to correct the straight line portion by the designer. Then, it moves to step SP10. In this step SP10, the designer inputs the position data of the straight line portion to be corrected and the correction data for correcting the straight line portion into an arc. This correction data is actually, deformation control at each end of the curve segment K _SG made by a straight line on the basic outline K1 Changing the curve segment K _SG to a predetermined arcuate shape. Here, when the data is input, the design device generates the curve data in place of the straight line part data of the curve segment _KSG by calculating the data of the deformation curve K2 in step SP11 in the same manner as in step SP6 described above. After that, in step SP12, the sectional shape including the created data is displayed on the display. Thus the designer has not been transformed
K1 and the arc-shaped deformation curve generated at the corner
Together with K2, it is possible to visually check the cross-sectional external shape that is corrected by deforming the straight line part with a predetermined radius, and then step
In SP13, a command is input to the design device to judge whether or not there is a correction portion other than the linear portion. This processing procedure is a processing step in the case where it is determined in step SP9 that there is a correction portion in the linear portion. When the designer inputs a negative command in step SP9, the design apparatus immediately proceeds to step SP13. If an affirmative result is obtained in step SP13, the design apparatus moves to step SP14, and the designer specifies a portion to be corrected again in the curve portion having the data of the deformation curve K2 other than the linear portion, and specifies the correction value data. Wait for input. When the input of the correction data is completed, the design apparatus moves to step SP15 and executes a process of generating a deformation curve using the input correction value data for the input data of the correction portion, and then proceeds to step SP16. Then, the sectional outline shape corrected by the data of the generated deformation curve is displayed on the display, and the process returns to step SP9. Therefore, the designer determines whether or not to correct the linear portion again while visually confirming the corrected cross-sectional shape on the display, and if it is necessary to perform the correction, the designer loops through steps SP9-SP10-SP11-SP12-SP13. Then, when it is not necessary to correct the linear portion again, the process immediately shifts from step SP9 to step SP13 to wait for a determination as to whether or not it is necessary to correct the linear portion again. If the part other than the straight line part is to be corrected again, the design apparatus performs steps SP13-SP14-SP
After executing the processing of step 15-SP16, the procedure returns to the above-mentioned step SP9. If it is not necessary, a negative command is inputted in step SP13, and the processing program is terminated in step SP17. According to the above configuration, the designer can design the deformation curve K2 inscribed on the basic outline K1 based on the data of the basic outline K1, so before starting the design work, the sectional outline shape after the design is completed The finished dimensions can be specified, and thus the work of designing the cross-sectional shape can be further facilitated. In addition to this, the deformation curve K2 and the straight portion left undeformed can be locally corrected anew, so that the cross-sectional shape that is being designed by partially correcting the cross-sectional outer shape little by little It is possible to perform a design operation in which the shape is approached while accumulating corrections step by step toward the desired shape. Thus, it is possible to easily realize a more convenient design apparatus that is adapted to the designer's sense of design work. In addition to this, the deformation curve data is transferred to each curve segment K _SG
By being able to transform independently for each
Various shapes can be generated with a large degree of freedom. (G3) Other Embodiments (1) In the above-described embodiment, a case was described in which an arc was set as the deformation curve K2. However, the shape of the deformation curve K2 is not limited to this, and may be any shape as necessary. Free curves can be set. (2) In the above embodiment, the basic outline K1 is
Although the case where the line segments extending in the x and y directions are used has been described, the extending direction of each line segment is not limited to this, and a line segment extending in an oblique direction with respect to the x or y direction may be used. The basic outline K1 is not limited to a straight line, but may be an arbitrary curve. (3) In the above embodiment, as described above with reference to FIGS. 2 and 3, the control points for deformation set on the basic outline K1 Although the case where the deformation curve K2 composed of one curve segment is generated by providing two control points between them has been described, instead of this, as shown by a broken line K3 in FIG. Control points for deformation on line K1 In between, the deformation control at a position not on the basic outline K1 Even if it makes it so, the same effect as the above-mentioned case can be obtained. H Effects of the Invention As described above, according to the present invention, a deformation curve with respect to a basic outline is displayed by a display means, and a designer operates the input means to deform the parameter using a parametric free curve. With such a configuration, it is possible to easily realize a design device that is easier to use.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1 and 2 are schematic diagrams showing the principle of a method for creating cross-sectional shape data of an object according to the present invention; FIG. 3 is a schematic diagram showing a method for generating a deformation curve thereof; FIG. 4 is a flow chart showing the processing procedure of the design apparatus, and FIGS. 5 and 6 are schematic diagrams used to explain a conventional method for forming a cross-sectional shape.

Claims (1)

(57) [Claims] A method for creating cross-sectional shape data of a desired object based on a basic outline representing a rough cross-sectional outline shape using a design device, the method comprising: A step of inputting basic outline data representing the basic outline of the shape; a step of displaying the basic outline on the display means based on the outline shape data; and a step of displaying a plurality of basic outlines on the basic outline by the data input means. A step of setting control point data representing a control point for deformation; and forming curve segment data comprising a parametric space curve between the control points for deformation based on the plurality of control point data for deformation. A step of generating deformation curve data representing a curve; and a step of displaying the display means using the deformation curve data as the cross-sectional shape data. The comprising, by using the deformation curves the display, the cross-sectional shape data creation method of an object, characterized in that to perform the correction of the I connexion the cross-sectional shape to said data input means. 2. 2. The method according to claim 1, wherein the basic outer shape data is data representing a straight line. 3. A patent characterized by designating a part of a straight line portion among the basic outlines by the control point data for deformation, and generating the deformation curve data representing an arc between the specified control points for deformation. 3. The method for creating cross-sectional shape data of an object according to claim 2. 4. 2. A method according to claim 1, wherein said parametric space curve is represented by a Bezier curve.