JP2619093B2 - Hole-cut block division method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Summary] In creating structural analysis input data of a part, a method of dividing a hole into blocks at a stage prior to performing mesh division is provided. In the three-dimensional wire frame model, a counterclockwise closed loop table that forms the same plane by line segments and arcs is created (step 1), and a punching table consisting of three consecutive points is created for the created closed loop table (step 1). 2) It is determined whether or not the three points in the hole punching table match the three points in the closed loop table (step 3).
It is configured such that it is determined whether or not the corresponding closed-loop table is divided into blocks according to the determination result (step 4).

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of dividing a hole into blocks in a stage prior to mesh division in creating input data for structural analysis of a part.

When calculating the strength of a part in advance, a three-dimensional wire frame model (plate shape model and fixed shape model) created using a CAD system is often analyzed by the finite element method. For this reason, in pre-processing (pre-processing), there is a demand for a method of performing block division and mesh division more quickly and efficiently.

[Prior Art] Various parts are used in all fields of industry.
Conventionally, the strength of such a component has been adopted by first performing a strength test on the manufactured component, and if a broken portion occurs, increasing the strength of the portion and redesigning it. However, in such a conventional method, it takes too much time to perform a strength test of a part, and when the strength test is not satisfied, it is a very troublesome procedure to redesign the component.

Therefore, in recent years, a method of checking the strength of a component at a stage before manufacturing the component, that is, at a stage of a design drawing, by stopping such a conventional method has been adopted. A finite element method, a boundary element method, a difference method, or the like is used as a method of calculating the strength of a component at the stage of a design drawing. Of these methods, the finite element method accounts for a large proportion. The finite element method divides a part into several parts (blocks) at the stage of a design drawing, performs a structural analysis using the finite element method for each block, and outputs the result.

This method is efficient when used in combination with a CAD system. In other words, a design drawing of a part is created using a CAD system, and structural analysis is performed on the created part design drawing by the finite element method. Since there is an existing program for structural analysis using the finite element method, structural analysis can be performed and results can be obtained only by inputting design data of parts.

FIG. 18 is a flowchart showing a conventional structure analysis operation. First, a part model is created using a CAD system (S1). When the creation of the part model is completed, the part model is divided into a plurality of blocks (S2). As a mode of division, there are a plate shape division and a solid shape division. Next, a boundary condition is input (S3). Here, as the boundary condition, for example, a constraint condition, a load condition, a material condition, and the like can be considered. Next, the block divided in step S2 is further divided into meshes (S
Four). The sequence up to this point is what is called pre-processing (pre-processing).
Is equivalent to

After the pre-processing is completed, an analysis operation based on a structural analysis is performed (S5). Step S5 is an analysis process. When the analysis calculation is completed, the analysis result is output (S6). Output processing of the result corresponds to post processing.

Here, the method of dividing the model of the plate shape and the solid shape in the pre-processing into blocks is automated as follows.

(1) Plate shape: A method of searching for a closed loop line segment (including an arc) consisting of the same plane and dividing it into triangles and quadrilaterals as shown in FIG. 19 (a) shows a triangle and all sides Minutes and one side is an arc. (B) shows a quadrangle, and there are a case where all sides are line segments, a case where one side is an arc, and a case where two sides are arcs. R1 and r2 in the figure are radii.

(2) Solid shape: A method of creating triangular prisms and quadrangular prisms as shown in FIG. 20 using triangular and quadrangular shapes divided in a plate shape.

(A) shows a triangular prism, and there are a case where all sides are line segments and a case where one side surface is a cylinder. (B) shows a quadrangular prism, and there are a case where all sides are line segments, a case where one side is a cylinder, and a case where two opposing sides are cylinders.

[Problems to be Solved by the Invention] In the conventional method, when there is a hole in the shape model, an unnecessary block is deleted at the time when the block division is completed. Therefore, if there are many unnecessary blocks, it takes a long time to delete. Further, in the block division in the closed loop, since the block is divided into a triangle and a quadrangle, the number of division points and the number of blocks are increased as compared with a case where no punching is instructed from the beginning, and there is a problem that efficiency is poor.

The present invention has been made in view of such a problem, and an object of the present invention is to provide a method for dividing a punched block, which can efficiently perform processing on a punched portion of a component.

[Means for Solving the Problems] FIG. 1 is a flowchart showing the principle of the method of the present invention. According to the present invention, in a three-dimensional wire frame model, a counterclockwise closed loop table that forms the same plane by a line segment and an arc is created (step 1). It is created (step 2), and it is determined whether or not three points of the hole punching table match three points of the closed loop table (step 3).
It is characterized in that it is determined whether or not the corresponding closed loop table is divided into blocks according to the determination result (step 4).

[Operation] In the pre-processing stage, it is checked whether or not three consecutive points correspond to three points in the closed loop table to determine a hole to be punched, and the hole is not blocked. This makes it possible to provide a perforated block dividing method capable of efficiently performing a process on a perforated portion of a component.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 2 is a general flowchart showing a sequence of disassembly of a punched block according to the present invention. First, create a 3D wireframe model using a CAD system (S
1) The line and arc data are read, and a point, line and arc table is created (S2). And these points created,
A counterclockwise closed loop table (to be described in detail later), which forms the same plane by the line segment and the arc, is created from the line segment and the arc table. Next, subdivision of line segments and arcs is performed (S3), and a punching table is created based on the subdivision results (S4).

After the punching table is created, it is checked whether the model is a plate shape or a solid shape (S5). In the case of a plate shape, the plate-shaped block is divided (including a check with a hole punching table) (S7), and a plate-shaped block configuration table is created (S8). In the case of a solid shape, a plate-shaped block division (including a check with a hole punching table) is performed (S9), and a plate-shaped block configuration table is created (S10). After the plate-shaped block configuration table is created, the solid-shaped block division is performed (S11), and a solid-shaped block configuration table is created (S12). First, a plate-shaped block configuration table is created for the solid shape because the solid shape is a plate shape on the front and back sides (see FIG. 20). Then, a solid block configuration table is created as a connection between the back and the front. The block configuration table is finally displayed as a block (S13).

FIG. 3 is a view showing a shape model (a three-dimensional wire frame model) used in the present invention. In the figure, E1 is a printed board, and E2 is a wire connected between the printed boards E1. The connection point between the printed board E1 and the wire E2 has a connector configuration. The corner points of the figure shown in the figure are numbered sequentially from 1. The radius is shown at the portion where the corner is arc-shaped. Here, E3 is a punched portion.

(1) When three consecutive points (21, 22, 23) are input in order to perform a punching instruction of the punching portion, the designated points are stored in a punching table as shown in FIG. 8 according to the flowchart shown in FIG. Set (21,22,23). Hole punching point (21,22,23)
If you enter, correct in the counterclockwise direction (23,22,2
1) is set on the punching table.

FIG. 7 is a flowchart showing a sequence of creating a punching table. First, the data set counter AWKTN of the punching table is cleared (S1). Next, it is checked whether or not the hole punching instruction has been completed (S2). If the instruction has ended, the sequence ends. Otherwise, the coordinates of three points (A, B, C) are input (S3). Next, the point coordinate table (PNTTB) is searched (S4), and it is checked whether three points exist (S5).

If there are no three points, an error message is displayed (S6) and the process returns to step S2. If there are three points, the line segments AB, BC are searched in the line segment table (ELMTB) (S7), and then the arc A- in the arc table (ARCTB).
B, BC are searched (S8). Then, it is checked whether AB and BC exist in the line segment or the arc (S9).
If AB and BC do not exist in the line segment or the arc, an error message is displayed (S6).

If AB and BC exist in a line segment or an arc, 3
A surface configuration process is performed at a point (S10), and it is checked whether the surface configuration process can be performed (S11). If the plane configuration processing cannot be performed, error message processing is performed (S6). If the plane configuration processing can be performed, it is checked whether points A, B, and C are counterclockwise (S12). If it is not counterclockwise, A and C are exchanged and unified counterclockwise (S13), the pointer of the point coordinate table PNTTTB of the coordinate values A, B, C is obtained (S14), and the data of the punching table (AWKT) is obtained. The set counter AWKTN is updated by 1 (S15). Next, the PNTTB pointers of the coordinate values A, B, and C are set in the punching table AWKT (S16), and step S2 is performed.
And the next processing is performed. In this way, the punching table
Data is sequentially stored in AWKT.

FIG. 8 is a diagram showing a configuration example of a punching table (AWKT). In the case of a punched portion, three points (start point, middle point, end point; in the case of FIG. 3, for example, 23, 22, 21) of the portion are stored. Hole punching table data is 1
Data set counter AW
KTN = 1.

FIG. 9 is a diagram showing a configuration example of a point coordinate table (PNTTB). It consists of X, Y, Z coordinate values and flags for each point, each of which consists of an initial value and an additional part by block decomposition. FIG. 10 is a diagram showing a configuration example of a line segment table (ELMTB). The line segment is represented as end point and end point data, and further includes a flag. Each of them consists of an initial value and an additional value by block division. FIG. 11 is a diagram showing a configuration example of an arc table. It consists of an end point, an end point, a center point of an arc, a 3 o'clock direction vector, a 12:00 o'clock direction vector, and a flag.

(2) When three points are input, three points exist on a straight line, a line segment table (ELMTB), an arc table (ARCTB)
In the case where the end point is configured, as shown in FIG.
Prompt for re-entry as an error.

(3) FIG. 4 is an explanatory diagram of a hole punching instruction. In the figure, when punching holes in the closed loop (16-15-23-22-21-20-17), (16-15-23), (15-23)
−22), (23−22−21), (21−20−17), (20−17−)
16) and (17-16-15) can be input, and any one of them can be input (in the embodiment, 23-22-21 indicated by → is input).

(4) The PNTT of three points to be punched in the punching table (AWKT) by the above-described sequence (1) to (3)
The B number is set, and the count of the hole punching data counter (AWKTN) is also counted up.

(5) Fig. 12 shows the closed loop table (WKT) to be punched
FIG. 3 is a diagram illustrating a configuration example of a sub-closed loop table. Third
An end point and an end point for each side of the shape model shown in the figure are written. As for the type of the side, 1 is a straight line and 2 is a circular arc. Point 17 and
It is a circular arc only between 16. The sub-closed loop table (SWKT) is a table in which end points are rearranged in numerical order. The values of the data set counters (WKTN) and (SWKTN) are 7 according to the number of sides. First, the end point 23 is found by sequentially comparing end points from the start of the closed loop table (WKT) with the first pointer 23 at the start of the punching table (AWKT).

(6) When the end point 23 is found in the closed loop table (WKT), in order to make the end points 22 and 21 easy to see, the sub closed loop table (SWKT) (23-22-21-20-17) having the end point 23 at the top.
−16−15).

(7) Next, the second point of the punching table (AWKT)
22 is compared with the second end point 22 of the sub-closed loop table (SWKT), and if they match, the process proceeds to the next step (here, match at 22).

(8) Similarly, the third point 21 of the punching table (AWKT) and the third end point 21 of the sub closed loop table (SWKT)
Compare with In this case, since they match in 21, the closed loop (16-15-23-22-21-20-17) assumes that punching has been instructed, does not divide the block, and executes a closed loop table for dividing the next block. (WKT).

FIG. 13 is a flowchart showing a check operation of the hole punching table (AWKT) and the closed loop table (SWKT).
First, it is checked whether the punching data set counter (AWKTN) is 0 (S1), and the punching data check counter ICNT is cleared (S2). Then, 1 is added to the contents of ICNT (S3). Next, it is checked whether or not ICNT> AWKTN (S4). If so, the block is not a punched part, so the block division instruction flag is turned on (S5).

If not, the punching table (AWKT) indicated by the ICNT pointer is matched with the pointer of the closed loop table (WKT) (S6), and it is checked whether the first pointer matches (S7). If they do not match, the process returns to step S3. If they match, the closed loop table (WK
A closed roof sub-table (SWKT) is created with the first pointer of T) at the beginning (S8).

Next, the second pointers of AWKT and SWKT are compared (S9),
It is checked whether the pointers match (S10). If they do not match, the process returns to step S3, and if they match, the third pointer of AWKT is compared with the third pointer of SWKT (S11). If they do not match, the process returns to step S3, and if they match, the hole is the punching unit, and the block division instruction flag is turned off (S13).

(9) If the three points of the punching table (AWKT) and the closed loop table (WKT) or the sub closed loop table (SWKT) do not match in the processing of (5) to (8), the punching table (AWKT) data set counter (AWKT
N) is incremented (updated) by 1 and checked.
When the value of the data set counter (WKTN) becomes the data set counter (AWKTN), it is determined that the block is not a perforated block, and block division is performed on the corresponding closed loop.

As described above, according to the present invention, the presence / absence of block division can be determined by comparing the closed loop table (WKT) with the punching table (SWKT). FIG. 5 is a diagram showing an example of block disassembly in a case where there is a hole. FIG. 6 is a diagram showing an example of block division in the case where there is no hole punching. In this example, 4
It is necessary to delete the blocks, and the number of blocks after the deletion is increased by three as compared with the case where the instruction to punch out is given from the beginning.

FIG. 14 is a block diagram showing an example of a system configuration for implementing the present invention, which shows a CAD system. In the figure, 1
Is a processor that performs various arithmetic controls, 2 is a main memory that stores information such as programs, graphic information, etc., 3 is a color monitor that displays graphic information, 4 is a disk that stores edited graphic information, and 5 is a coordinate. A light pen that is an input device,
6 is a keyboard for inputting various commands, 7 is a function switch, 8 is a doublet which is a coordinate input device,
9 is a cursor.

By using such a system, a graphic of a part is created on the color monitor 3, a structural analysis is performed in accordance with the above-described sequence, and no block division is performed on the punched portion. As a result, there is no need to perform unnecessary block division.

In the above-described embodiment, the case where the punching block division is performed on the plate shape model is shown. However, the present invention can be similarly applied to the solid shape model. FIG. 15 is a diagram showing a solid shape model. Reference numeral 10 in FIG. The solid shape model including the perforated portion 10 can be considered as a combination of the front and back plate shape models. Therefore, the hole punching instruction of the hole punching portion 10 can be specified by specifying the hole punching portion 10 from each of the front surface and the back surface as shown in FIG. 16, and the present invention can be applied. FIG. 17 is a diagram showing the result of block division.

[Effects of the Invention] As described above in detail, according to the present invention,
By automatically determining the punched portion, it is possible to omit the blocking of the punched portion and to efficiently perform the processing regarding the punched portion of the component.

[Brief description of the drawings]

FIG. 1 is a flow chart showing the principle of the method of the present invention, FIG. 2 is a general flow chart showing a sequence of block division according to the present invention, FIG. 3 is a view showing a shape model used in the present invention, and FIG. FIG. 5 is a diagram showing an example of block division in the case of punching, FIG. 6 is a diagram showing an example of block division in the case of no punching, and FIG. 7 is a sequence of creating a punching table. FIG. 8 is a diagram showing a configuration example of a hole punching table, FIG. 9 is a diagram showing a configuration example of a point coordinate table, FIG. 10 is a diagram showing a configuration example of a line segment table, and FIG. FIG. 12 is a diagram showing a configuration example of a closed-loop table and a sub-closed-loop table; FIG. 13 is a flowchart showing a check operation of a punching table and a closed-loop table; FIG. 15 is a block diagram showing a solid shape model, FIG. 16 is a diagram showing a punching instruction, FIG. 17 is a diagram showing a result of dividing a block, and FIG. 18 is a conventional diagram. 19 is a diagram showing a plate-shaped divided block, and FIG. 20 is a diagram showing a solid-shaped divided block. In FIG. 14, 1 is a processor, 2 is a main memory, 3 is a color monitor, 4 is a disk, 5 is a light pen, 6 is a keyboard, 7 is a function switch, 8 is a tablet, and 9 is a cursor.

Claims (1)

(57) [Claims] 1. In a three-dimensional wire frame model, a counterclockwise closed loop table which forms the same plane by a line segment and an arc is created (step 1). Is created (step 2), and it is determined whether or not the three points of the hole punching table match the three points in the closed loop table (step 3), and the corresponding closed loop table is divided into blocks according to the determination result. A method of dividing a perforated block, wherein a decision is made (step 4).