JPS6324303A - Generating method for tool path data caused by shape change of shape model data - Google Patents

Abstract

PURPOSE:To change a tool path data within the minimum range by correcting the tool path data, based on an interference of the tool path data before a change, which has been cut within a range of a shape change model data, and a new surface data. CONSTITUTION:When a shape model is changed through a coordinate input device 20, etc., a cutting line containing a shape change partial range is designated to a data which has been read out of a shape model data 24 of an external storage device 10 by a computer 12. Subsequently, in this cutting line, an interference check of a corresponding tool path data 30 and a designated change shape model data is executed, and in accordance with whether an interference exists of not, a correction of raising and lowering directions of a tool passage data is executed. Next, a corrected tool path is fitted to the corresponding part of the data 30. In this way, the tool path data can be changed within a minimum range, and it is possible to cope quickly and appropriately with a partial change of the shape data.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for creating NC data, that is, tool path data, for performing mold machining in a computer-aided design system, and more specifically, This is a method for creating NC data when the shape of a product such as a vehicle is changed due to a design change or model change, in particular, the NC data (tool path data) that should be changed at the same time for the shape change part. The present invention relates to a method for creating tool path data efficiently and at high speed.

In recent years, computer-aided design systems (hereinafter referred to as CAD/C)
(referred to as AM) is becoming popular and is being applied to various industrial fields. In particular, C handles 3D shape model data.
AD/CAM is widely used (applied) from the concept stage of design to production simulation.

Such CAD/CAM systems are also used in the design of automobile vehicles. In this case, the product shape of the vehicle created in the computer may be changed due to design changes, model changes, or the like. Such a shape model consists of graphic data composed of free-form surface parts, and is stored in a database as a huge amount of data, and it takes a lot of time to process the shape when changing the shape.

In the CAD/CAM system described above, a shape model is created in a computer, and tool path data (referred to as NC data) for machining the shape into a mold is also created and stored in a storage device. However, if the shape is changed for the reasons mentioned above, it is naturally necessary to change the tool path data of the corresponding part accordingly.

When changing the tool path data in conjunction with changing the shape model data as described above, the unit to be changed is generally in units of surfaces, so it is necessary to delete the entire surface related to the shape change. Tool path data connected to the surface data is also deleted on a surface-by-surface basis. Then, new shape model data to be changed is created, and tool path data is also created again in accordance with the surface data of this new shape model data. For this reason, the process of creating new tool path data takes time and is inefficient, errors occur in the process of creating new tool path data, and database management within the system is required. There were disadvantages such as increased man-hours.

The present invention has been made to overcome such inconveniences, and is a computer-aided design system comprising shape model data and tool path data for machining the shape model data into a mold. In the tool path data creation method that changes the tool path data corresponding to the changed part of the shape model data formed in the system, new tool path data is created that handles the tool path corresponding to the shape part to be changed. It is an object of this invention to provide a method for changing tool path data efficiently and within a minimum range.

In order to achieve the above object, the present invention provides a computer-aided design system that creates shape model data and tool path data for machining a mold having the shape. A first method of creating tool path data for changing the tool path data of a portion corresponding to a shape changing portion of the tool path data, the tool path data before the shape model data being changed is cut by a cutting line indicating the range of the shape changing model data. a second step of checking the interference of the old tool path data with the new surface data to be changed; and a third step of correcting the old tool path data based on the interference check and making it new tool path data. and a fourth step of embedding the new tool path data in the correction section of the cut out old tool path data.

Next, a preferred example will be given of the method for creating tool path data accompanying a shape change of shape model data according to the present invention.
A detailed description will be given below with reference to the accompanying drawings.

FIG. 1 is a diagram showing the basic configuration of a computer-aided design system (CAD/CAM) that handles a shape model and a tool path for machining the shape into a mold according to the present invention, and the reference numeral 10 will be described later. This is an external storage device that stores shape model data 24 indicating the shape of a product such as a vehicle, tool path data 30, and the like.

In this external storage device 10, reference numeral 32 is machining condition data, which includes tool shape (diameter, diameter,
This data indicates machining conditions such as cutting speed, rotation, etc. determined from these conditions, such as length, material, lifespan, etc.), holder shape, cutting material, cutting surface finish (rough, finish), etc. Reference numeral 34 is machining plan data, which is data indicating a machining plan based on mold machining know-how such as designation of tools that can be used in mold machining and how to use the tools. Reference numeral 36 is design change part data, which is data regarding the design change part that is stored together with cutting shape data and tool path data for the shape change part. Reference numeral 12 is an electronic computer, and this computer 12 performs a series of processes for changing the shape, checking for interference in the tool path data after the shape change, and calculating new tool path data for the shape changed part. At the same time, the required shape model data 24 or tool path data 30 is read out from the external storage device 10, and the display of a three-dimensional image on the graphic display device 16 is controlled.

Reference numeral 14 is an interface device, which connects the electronic computer 12 with input/output devices such as a graphic display device 16, an operation panel (keyboard) 18, and a coordinate input device (table left) 20.

The operation panel 18 is an input operation panel through which the operator inputs processing commands and processing parameters to the computer 12, and the coordinate input device 20 is used by the operator to instruct the cutting range of the shape change portion from the overall shape model using a stylus pen 22. It is for the purpose of

The computer-aided design system according to the present invention generally includes:
The system is configured as described above, and the processing procedure and effects related to the creation of tool path data accompanying the shape change of the shape model will be explained next.

The method for creating tool path data according to the present invention utilizes cutting lines that indicate the range of the portion of the shape model whose shape should be changed, cuts out the tool path data before the change that corresponds to this shape change portion, and creates a new tool path data whose shape should be changed. Basically, the old tool path data is checked for interference with the surface data, the old tool path data is corrected based on this, and the old tool path data is embedded as new tool path data in the tool path data of the cut portion.

FIG. 2 is a schematic processing flow showing a method for creating tool path data according to the present invention. In order to create tool path data corresponding to the shape-changed portion that should be changed due to the change of the shape model, first, in step A, the shape model and tool path whose shape has been changed are input from the coordinate input device 20 or the operation panel 18. It is specified, read out from the external storage device 10, and displayed as a three-dimensional image on the graphic display device 16 as necessary.

Next, in step B, a range including the shape change part is specified with a cutting line (range line) for the shape model displayed on the graphic display device 16 (the shape model read from the external storage device 10 in step A). . This cutting line is made up of a set of a plurality of straight lines or curved lines, and is used in the next step C to cut out the part of the old tool path data that corresponds to the changed new surface data. That is, in step C, the electronic computer 12
calculates the intersection between the cutting line obtained in step B and the tool path data before the shape change (old tool path data) read from the external storage device 10 in the process of step A, classifies the tool path, and makes it valid. side or invalid side. The valid side is tool path data of a portion corresponding to the shape changing portion, and the invalid side is tool path data outside the shape changing portion. Then, the tool path data of the portion determined to be valid is cut out, and the position coordinates for embedding the tool path data corrected in step F in the cut portion are stored. This storage may be a working area of external storage device 10 or a working area of main memory in computer 12.

Next, in step D, an interference check is performed between the cut old tool path data and the new surface data constituting the new shape model data to be changed. This interference Che7
Based on the results of the process, in step E, the old tool path data is corrected. In other words, if the new surface data and tool path data interfere, correct the tool path data to a point where it does not interfere with the new surface data, and if the new surface data and tool path data do not interfere, change the new surface data. Correct it in the direction of lowering it to the point where it touches the data.

The detailed processing procedure for checking interference in the tool path, the detailed processing procedure for correcting the tool path data, and their effects will be described later.

When the old tool path data is corrected in steps D and F above and new tool path data for the shape-changed portion is obtained, the new tool path data is embedded in the cut out part of the old tool path data in step C. Through this process, new tool path data is obtained for the new surface data of the shape-changed part based on the old tool path data before the shape change, but if the old tool corresponding to the new surface data If there is no path data and there is tool path data that has not been calculated in the previous step, then in step G, only the tool path data for that portion is recreated from the graphic display device 16 or the coordinate input device 20.

Although the method for creating tool path data according to the present invention has been outlined above, the main parts will be explained in more detail below.

FIG. 3 is a diagram showing the detailed processing procedure of step C in FIG. Step C shows a process of cutting out the old tool path data before the shape change corresponding to the new surface data to be changed, based on the cutting line (range line) indicating the range of the shape change part obtained in Step B. First, in step 1, the computer 12 approximates a given cutting line (range line) a to a polygonal line to calculate a group of approximate range lines a'.

That is, the range line a given as a closed loop of a straight line or a collection of curved lines is considered as a plurality of straight lines. Next, in step 2, the CL point is read from the old tool path data existing in the portion surrounded by the approximate range line group a'. Here, the tool path (Cutter Location
: CL) is a locus that the tool cutting edge passes, and is a set of points that can be connected with a straight line, one of which is called a CL point.

By moving the tool between one CL point and the next CL point (between two points), the object placed between the two points is removed, and a predetermined shape is processed.

FIG. 4 is a diagram conceptually showing this, and reference numeral 40 indicates a tool, and a set of points that can be connected by a straight line of trajectory through which the cutting edge 42 passes is a tool path (CL), and one CL
Point type 4: The tool moves between adjacent CL points 46, and the material is removed between these two points. Therefore, it is necessary to check the interference between the three-dimensional shape to be removed between these two points and the surface data forming the new shape model. This interference check will be described later.

Next, in step 3, each line segment 4 of the approximate range line a'
8 and the line segment 50 representing the old tool path specified by the two CL point types 446, and if there is an intersection, in step 4, the line segment 50 representing the tool path is divided by the intersection, This divided tool path line segment falls inside the range line. That is, it is determined whether it is the valid side corresponding to the tool path to be cut corresponding to the shape change portion or the invalid side outside the range line, and a valid flag is set for the line segment on the valid side.

This process is applied to all the line segments that make up the polygonal line approximation range line a' and all the tool paths that pass through the shape change part surrounded by this range line a' (paths that connect each two adjacent CL points). )
All tool paths to be cut are identified by repeating between the line segments representing . Line segment 50 representing range a' and tool path
The valid side (to be cut) specified by the intersection s, b'
Both end points of each tool path 51, 52, 54 (intersection b, b')
Each C has a valid flag set, and this flag is logical O on the starting point side of the valid tool path from the direction of travel of the tool path, indicating that the valid tool path starts immediately after, and on the end point side, the flag is logical O. The logic is 1, indicating that the tool path was valid until just before. Therefore, in step 5, all the tool path data passing through the shape change portion surrounded by the range line a are extracted and cut out for each tool path, the effective portion of the valid flags 0 to 1 attached in step 4.

FIG. 5 is a diagram showing the detailed processing procedure of steps D and E in FIG. 2. Steps D and E check for interference between the old tool path data cut out in step C and the new shape surface data to be changed, correct the old tool path data, and create a new tool according to the new surface data. It performs processing to create passage data.

In this process, a line segment connecting two CLs of the old tool path data cut out by the process shown in FIG. 4 is given, and first, in step 6, both end points (C
(L point) is further divided into finer points, and in step 7, an interference check is performed between each divided point and one tangential plane forming the new surface data. Here, the tangent plane is a plane created by polyhedral approximation of the curved surface constituting the new surface data.

Furthermore, the interference check with the new surface data at one point in the tool path is schematically shown in FIG. That is, in FIG. 6, when the tool 40 processes the new shape surface 60, if the center position of the tool is Q, the cutting range is the range indicated by r, and the slope 62 of the new shape surface 60 and the tool 40 If there is a misalignment in the tool path, it will not be possible to machine the desired shaped surface. Therefore, it becomes necessary to correct the tool path. For example, the old tool path data can be made into the new tool path data by performing a correction that moves the tool until the distance d from the slope 62 to the tool center Q becomes equal to the distance r. This process is called interference checking between the tool path and the shape surface and correction of the tool path data based on this. In the process shown in Figure 5, this process subdivides the tool path into fine points, and the new surface data is also subdivided by tangent planes that approximate the curved surface to a polyhedron, and interference checks and tool path data correction are performed for each minute part. Therefore, the tool path data can be calculated by simple geometric calculations in the vicinity of the approximate machining area.

In step 7, the above-mentioned interference check is performed for one point on the tool path and one tangent plane, and if there is interference, the tool path data is corrected in step 8 to increase the tool path data to a point where there is no interference. If not, in step 9, the tool path data is corrected in a downward direction until they are in contact.

FIG. 7 is a diagram showing the detailed procedure of step F in FIG. 2. Step F is a process of embedding new tool path data corrected from the old tool path data obtained in step E into the old tool path data cut out in step C. First, step 10
In step C, the position coordinates for embedding the corrected new tool path data recorded when the old tool path data for the shape-changed portion were cut out are read. Then, in step 11, the old tool path data
(uncut path data), the effective tool path data obtained in the process shown in FIG. Read the new tool path data (partial CL) obtained by the 51st interference check and tool path data correction processing, and if the partial CL is not completed, read the old tool path data immediately after the 10th valid flag in step 13, If the partial CL is not finished, the old tool path data is read from immediately after the valid flag 1 point to just before the next valid flag O point in step 14, and the process returns to step 12 to read the partial CL.

In this way, the new tool path data is embedded in the old tool path data, the new tool path data completed in step 15 is stored in the external storage device 10, and tool path data is created in accordance with the desired shape change. Ru.

As explained above, the method of creating tool path data accompanying a shape change of a shape model according to the present invention is to cut out the tool path data before the shape change at the cutting line indicating the range of the part to be changed in shape, and then Check the interference of the old tool path with the new surface data to be processed, and based on this, modify the old tool path data and create new tool path data.
Since this is a method of embedding the tool path data of the cut portion, it is only necessary to handle the tool path data in the range corresponding to the shape-changed portion, which greatly reduces the processing time for calculating new tool path data, and also embeds the old tool path data. New tool path data can be calculated by making corrections based on this, greatly simplifying the creation of new tool path data due to shape changes, and reducing errors in creating new tool path data. It also has various advantages, such as not complicating data heirloom management within the computer system.

Although the present invention has been described above with reference to preferred examples, the present invention is not limited to these examples, and it goes without saying that various improvements and changes in design can be made without departing from the gist of the present invention. It is.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the basic configuration of a computer-aided design system that handles a shape model according to the present invention and tool path data for machining the shape into a mold, and FIG. 2 is a diagram showing a shape change of the shape model according to the present invention. 3, 5 and 7 are diagrams showing the detailed processing procedure of the main steps of the processing flow shown in Fig. 2, and Fig. 4 is the tool path data. FIG. 6 is a diagram conceptually showing the interference check between the tool path and the shape surface and the correction of the tool path data.

Claims (1)

[Claims] (1) In a computer-aided design system that creates shape model data and tool path data for machining a mold having the shape, a portion of the shape model data created in the system that corresponds to the shape change portion. A method for creating tool path data that changes the tool path data, the method comprising:
a first step of cutting the tool path data before changing the shape model data with a cutting line indicating the range of the shape change model data; a second step of checking the interference of the old tool path data with the new surface data to be changed; a third step of correcting the old tool path data based on the interference check and making it new tool path data; and a fourth step of embedding the new tool path data in the correction section of the cut out old tool path data. A method for creating tool path data accompanying a shape change of shape model data.