JPS6324304A - Generating method for tool path data - Google Patents

Abstract

PURPOSE:To exactly and automatically execute working of a complicated curved surface part by converting a data of plural triangular tangential planes, checking an interference of a tool against each tangential plane data, and generating a tool path data. CONSTITUTION:A shape model data of a working surface, which has been written and stored in an external storage device 10 is converted to a data of plural triangular tangential planes by a computer 20, and a tangential plane correspondence table against an area map is generated. The computer 20 derives a tangential plane data of the correspondence table corresponding to the area map in which an occupied area of a tool is included, checks an interference of the tool and the tangential plane data, corrects and generates a tool path data so that the tool avoids the tangential plane having an interference part, and this data is stored in the device and an NC working is executed. By this tool path data, a tool path is controlled, and working of a complicated curved surface part is executed exactly and automatically without preventing an interference of the tool and a working surface by worker's monitoring.

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 using a computer-aided design system, etc. Creation of tool path data that enables accurate and automatic production of molds by checking the interference of the tool with the press mold formed based on the shape data of vehicles, etc. created in , and creating NC data. Regarding the method.

In recent years, computer-aided design systems (hereinafter referred to as CAD/
(referred to as CAFI) is becoming popular and being applied to various industrial fields. In particular, C that deals with three-dimensional shape models
AD/CAM is widely applied from the concept stage of design to production simulation.

As an example of the use of such a CAD/CAM system,
There are operating programs for NC machine tools that cut and form press molds for automobile parts, that is, there are programs that automatically create NC data. In this case, the CAD/CAM system stores shape model data of an automobile member composed of free-form surface parts as a database, and the CAD/CAM system
The /CAM system creates tool path data (NC data) by processing the shape model data.

By the way, automobile parts are usually composed of complicated free-formed surface parts, and the free-formed surface parts include parts that are significantly curved or bent. Therefore, if the NC machine tool is driven by calculating the tool path data for the shape model data without considering the cutting diameter of the tool that cuts and forms the mold, the tool will interfere with other machining surfaces, resulting in accurate Inconveniences arise in that a cutting surface cannot be obtained or the NC machine tool itself is damaged.

Therefore, as a method to avoid the interference of the tool with adjacent machined surfaces, as shown in Fig. There is a method in which NC data is created such that the tool A is moved along the offset surface b' when the tool A reaches the intersection line l from the offset surface a'.

In this case, interference of tool A with the machining surface can be avoided, but the position of intersection line 2 must be indicated by the operator in advance, which not only requires man-hours but also avoids incorrect instructions. It has been pointed out that if this is done, a large amount of manufacturing time and manufacturing cost will be wasted.

Another method is to set a curved surface (referred to as a fillet surface) that assumes the case where the tip of tool A comes into contact with both machining surfaces a and b, and then move tool A to the offset surface a' mentioned above. There is one in which NC data is created so as to move along the fillet surface and then move to the offset surface b' via the fillet surface. However, in this case as well, there is a disadvantage that setting the fillet surface etc. is extremely troublesome.

Furthermore, in the above method, only a ball tool can be used in which the tip of the tool A can be considered to be spherical when rotated. That is, for example, when using a flat tool, the machined surface a
Since the cutting angle of the tool changes depending on the inclination angle of , b, the offset h from the machining surfaces a and b also changes, making automatic setting of the tool path by arithmetic processing extremely complicated.

Still another method is to calculate the tool path without considering interference, and then remove the path indicated by the broken line in FIG. 1 to set the final tool path. In this case, it is extremely effective for simple machined surfaces, but
If the machined surface is extremely complex, it is impossible to completely avoid tool interference using only the above method.

The present invention has been made in order to overcome the above-mentioned disadvantages, and when creating tool path data for mold machining using a computer-aided design system or the like, curved surface data corresponding to the shape data of the mold are used. By converting the data into multiple tangential plane data made up of triangles, checking the interference of the tool with each tangential plane data, and creating tool path data, it is possible to accurately and automatically process free-form surfaces with complex shapes. The purpose of this invention is to provide a method for creating tool path data that can be performed in a timely manner.

In order to achieve the above object, the present invention provides a method for creating tool path data for mold machining based on shape model data, wherein the machining surface data constituted by the shape model data is configured to form a triangle. Next, a correspondence table of the plurality of tangential plane data with respect to a predetermined area map knob is created, and further, the area map that includes the cutting area of the tool and the The method is characterized in that predetermined tangential plane data is obtained from a correspondence table, and then an interference check is performed between the tool and the tangential plane data, and corrected tool path data is created so that the tool avoids the tangential plane where the interference portion is located. shall be.

Next, a preferred embodiment of the method for creating tool path data according to the present invention will be described in detail with reference to the accompanying drawings.

The second session is based on a computer-aided design system (CAD/CAM) applied to the method of creating tool path data according to the present invention.
), in which reference numeral 10 is shape model data 12 indicating the three-dimensional curved shape of an automobile member, etc.
This is an external storage device in which the tool path data 14 calculated by the method of the present invention and the like are stored. In addition, the external storage device 10 further stores information such as the tool shape (diameter, length, material, etc.) for mold machining, the holder shape, the material of the mold, the finishing accuracy of the cutting surface, etc., and information from these conditions. Machining condition data 1G such as required cutting speed and rotation, and machining plan data 18 as know-how in mold machining such as machining direction and machining pinch are stored in advance as a database.

The external storage device 10 is connected to a computer 20 that constitutes a CAD/CAM system, and this computer 20
is the desired shape model data 1 from the external storage device 10.
2 is read out, a series of processing is performed to calculate the tool path by changing the interference of the tool path, and at the same time, the three-dimensional image display on the graphic display device 24 is controlled via the interface 22. The interface 22 includes an operation panel (keyboard) 2 for manually inputting machining condition data 16, machining plan data 18, etc. to the electronic computer 20.
6 is connected, and a coordinate input device (table left) 28 for creating, modifying, etc. graphic data is also connected.

The CAD/CAM system for implementing the method of the present invention is roughly configured as described above.
A method of creating tool path data for the C machine tool will be explained based on the flowchart shown in FIG.

Therefore, first, various machining parameters required for machining are input from the operation panel 26 to the electronic computer 20 (STPI). In this case, the machining parameters include the machining surface, machining evaporation turn, machining pitch, tool shape, tool holder shape, and tolerance when approximating the tool path to a straight line.

Next, based on the machining evaporation, machining pinch, etc. input in step 1, as shown in FIG. 4, the machining curved surface S
A tool path is temporarily set for (STP2). In this case, the temporarily set tool path is not limited to the one shown in FIG. 4, and it goes without saying that it can be set using various curves. The temporarily set tool path is approximately a straight line within a predetermined tolerance range, and is constructed by connecting temporary set point data P.

On the other hand, in step 3, the curved surface data constituting the curved surface S is converted into tangent plane data composed of a large number of triangles, as shown in FIG.

That is, fish school data is obtained by dividing the curved surface patch T constituting the curved surface S independently in the U direction and the V direction. In this case, the error between the straight line obtained by connecting the fish school data and the straight line formed from the curved surface data is a value ε that allows a preset tolerance. (For example, ε8,2 in the figure) ε3<ε. ) so that ε is set. Then, the above operation is performed on all curved surface notches T constituting the curved surface S.

Subsequently, the fish school data are combined by diagonals to obtain the tangent plane K of the triangle. Note that the above processing steps are performed on all curved surfaces S constituting the processing surface of the desired mold.

Next, a correspondence table between the tangent plane data obtained in step 3 and the area map is created (STP4). Here, the area map refers to
It is composed of a two-dimensional grid in a plane, and
, Y, and Z to classify the tangent plane data into sections.

Therefore, as shown in FIG. 6, tangent plane data included in a predetermined section of the area map M, for example, sections (a, b), is determined. In this case, the correspondence table is configured as shown in FIG.

That is, the data in the (a, b) sections include the curved surface number containing the tangential plane data (for example, St, St), the number for the tangential plane (for example, 1 of the tangential plane data that constitutes the tangential plane K)
i, j) and the identification code k for the tangent plane (for example, in the tangent plane composed of the tangent plane data P2., the upper left triangular tangent plane is set to 1, and the lower right The triangle tangent plane is 2).

Subsequently, in steps 5 and 6, interference calculation processing for the machined surfaces of the tool and tool holder is performed using the correspondence table set as described above. Here, the first processing step consisting of step 1 and step 2 and the second processing step consisting of step 3 and step 4 may be carried out in either order, or may be performed in parallel. .

Here, the shape of the tool during rotation is shown in Figure 8a.
The four types shown in d to d are representative. That is, FIG. 8a shows a ball tool 30, which is composed of a cylindrical portion 30a and a spherical portion 30b. Further, FIG. 8 shows a flat tool 32 having a cylindrical portion. Furthermore, Fig. 8C and d are respectively Satoshi type tools 34 and 36.
It is constituted by a combination of cylindrical parts 34a, 36a, conical parts 34b, 36b, and spherical parts 34c, 36c.

On the other hand, the tool holders that hold the tools 30, 32, 34 and 36 are generally shaped as shown in FIGS. 9a and 9b. That is, in FIG. 9a, the tool holder 38 has a cylindrical shape, and the tool holder 40 shown in FIG. There is.

Therefore, a description will be given of an interference calculation processing method for a machined surface when the ball tool 30 shown in FIG. 8a and the tool holder 38 shown in FIG. 9a are used.

In this case, the radius of the spherical portion 30b of the ball tool 30, that is, the cutting diameter is r, and the center point of the spherical portion 30b is P,
shall be. That is, this point P corresponds to the temporary setting point data Pi shown in FIG. 4 before the interference calculation process, and the ball tool 30 moves along the tool path connecting the temporary setting point data P with a straight line. Temporarily set to move.

First, the section of the area map M that includes the cutting radius r of the ball tool 30 is determined based on P, the coordinates of the points, and the cutting radius r. In this case, the ball tool 30 is included within the hatched area shown in FIG. 10a. Next, the section indicated by the hatched area is extracted from the correspondence table shown in FIG. 7, and the tangential plane K included therein is extracted.

Next, the state of interference between the tangential plane and the ball tool 30 is checked. In this case, the ball tool 30 is
Only the spherical portion 30b has the possibility of interfering with the machined surface, so interference between the spherical portion 30b and the tangential surface is checked. Note that this interference check can be performed, for example, as shown in FIGS. 11a to 11c. That is, the 11th
In FIG. 1A, the state of surface contact between the spherical portion 30b and the tangential surface is checked, and in FIG. 11, the state of edge contact between the spherical portion 30b and the tangential surface is checked. In addition, in FIG. 11C, the ball part 3
The state of point contact between 0b and the tangent plane is checked. Then, the path of the ball tool 30 is corrected so that the ball portion 30b does not interfere in these three states. Such arithmetic processing is performed on all the tangential planes K included in the hatched area in FIG. As a result, the ball tool 30 moves to point 08 where the point P of the spherical portion 30b does not interfere with the tangential plane K, as shown in FIG.

Next, the interference state of the tool holder 38 is checked. In this case, if the radius of the tool holder 38 is R, the area map M encompassed by the holder diameter R becomes the shaded area shown in FIG. Ask from the table. Then, an interference check between each of the tangential planes and the tool holder 38 is performed. In this case, the tool holder 38 has a cylindrical shape, and is shown in FIGS.
As shown in FIG. 3, by checking the states of surface contact, side contact, and point contact with respect to the tangent plane K, the position of the tool holder 38 that does not interfere is calculated. As a result, the tool holder 38 moves from the Q and l positions to the R and R positions as shown in FIG.
Move to position l. Therefore, the ball tool 30 will further move from the above-mentioned point Qi to the point R4.

As described above, the ball tool 30 and the tool holder 3
A tool path is set in which the tool 8 does not interfere with the machining surface of the mold. The modified path is shown in FIG. Note that either step 5 or step 6 may be performed first, or they may be processed in parallel.

Here, in the next step 7, the temporary setting point data P of the tool path temporarily set in FIG. 4 is converted into regular tool path data R8. The tool path data R4 determined in this way is provided to the NC machine tool as NC data.

In addition, there are other tool shapes shown in FIGS. 8-d, and tool holder shapes shown in FIG. 9. In this case, the flat tool 32 and the tool holder 40 can be checked for interference with each other in the cylindrical shape shown in FIGS. 13A to 13C. Further, in the case of the full-form tools 34 and 36, interference checks can be performed on the cylindrical portions 34a, 36a and the spherical portion 34C136c as shown in FIGS. 11a to 11C and 13a to 13C. Moreover, for the conical portions 34b and 36b,
As shown in FIGS. 16a to 16C, conical portions 34b, 36b
The interference state can be detected by checking the surface contact and line contact between the bottom surface of the conical portion and the tangential surface, and the point contact between the side peripheral surfaces of the conical portions 34b and 36b and the tangential surface.

As described above, according to the present invention, when creating tool path data for mold machining using a computer-aided design system or the like, a machining surface configured from shape model data corresponding to the mold is created. Divide the triangle into tangential planes, make the tangential plane correspond to a predetermined area map, extract the tangential plane that may interfere from the position of the tool with respect to the area map, and prevent the tool from interfering with the tangential plane. NC data for mold machining is created by setting the tool path.

Therefore, when mold machining is performed based on the NC data, there is no possibility of defective molds due to interference between the tool and the machined surface, and it is possible to accurately and automatically manufacture high-precision molds. Become.

In addition, since interference calculation processing by a computer is performed sequentially using local tangent plane data extracted by specifying an area map, the processing speed is fast (tool path data can be created in a short time and used with NC machine tools, etc.). Furthermore, the interference state of various types of tools applied to the method of the present invention, such as ball tools, flat tools, and round tools, can be checked using the same algorithm. Therefore, the program has the advantage of being extremely simple.

Although the present invention has been described above with reference to preferred embodiments, the present invention is not limited to these embodiments, and various improvements and changes in design can be made without departing from the gist of the present invention. Of course.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing a tool path setting method according to the prior art, FIG. 2 is a schematic configuration diagram of a computer-aided design system to which the method of creating tool path data according to the present invention is applied, and FIG. 3 is a diagram of the present invention. A schematic processing flow showing a method for creating tool path data according to the invention, FIG. 4 is an explanatory diagram showing a temporary setting state of tool path data, and FIG. 6 is an explanatory diagram of an area map in the method for creating tool path data according to the present invention; FIG. 7 is an explanatory diagram of a correspondence table in the method for creating tool path data according to the present invention; FIGS. 8 a to d 9A and 9B are explanatory diagrams of the shape of a tool applied to the method of creating tool path data according to the present invention, FIGS. 10a and 10b are explanatory diagrams showing the correspondence between the area map and the tool and the area map and the tool holder in the tool path data creation method according to the present invention; a
12 to 14 are explanatory diagrams showing the contact states of the tool and the tool holder with the tangential plane in the method of creating tool path data according to the present invention, respectively. An explanatory diagram showing the positional relationship between a tool and a tangent plane and a tool holder and a tangent plane after interference is avoided. FIG. 15 is an explanatory diagram showing a point sequence of tool path data set in the tool path data creation method according to the present invention. It is. 10... External storage device 12... Shape model data 14... Tool path data 20... Computer 24... Graphic display device 26... Operation panel 28
...Coordinate input device 30...Ball tool 32.
...Flat tool 34.36...Full tool 38
．． 40...Tool holder S...Curved surface K...Tangential plane M...Area map FIG, 5 FIG, 11 (a) (b) (c) F[G,
6-′

Claims (3)

[Claims] (1) A method for creating tool path data for performing mold machining based on geometric model data, which converts machining surface data constituted by the geometric model data into data of a plurality of tangential planes constituting a triangle. Next, create a correspondence table of the plurality of tangential plane data with respect to a predetermined area map set in advance, and further obtain predetermined tangential plane data from the area map that includes the cutting area of the tool and the correspondence table, Next, an interference check between the tool and the tangential plane data is performed to create tool path data corrected so that the tool avoids the tangential plane where the interference portion is located. (2) A method for creating tool path data according to claim 1, in which the area map is constituted by a lattice-like plane including data on a plurality of tangential planes. (3) In the method according to claim 1, the interference check between the tool and the tangential plane data is performed based on the contact state between the triangular surface configured by the tangential plane data and the tool, and the contact state between the sides of the triangle and the tool. and a contact state between the apex of the triangle and the tool, respectively.