JPH1173212A - Nc working simulation method and method for preparing work piece model data for the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily operate NC working simulation. SOLUTION: Cutter location data(CL data) are fetched by a CL data fetching part 50 from an upstream side CAM system to a downstream side NC working simulation system. The operation program of simulation is prepared from the CL data by a CL data/operation program converting part 52, and work piece model data are also prepared by a CL data/work piece model converting part 54. Then, a simulation operating part 56 is allowed to operate NC working simulation by the both prepared data. The CL data are simpler data than the shape data of a work piece including curved surface data so that the CL data can be easily fetched in the NC working simulation system. Also, the work piece model is expressed with the group of model lines prepared from the CL data so that the data processing can be made simple, and the NC working simulation can be easily attained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an NC machining simulation method and a method of preparing workpiece model data for NC machining simulation suitable for implementing the method.

[0002]

2. Description of the Related Art An NC machining simulation is, for example,
Prior to processing by the NC processing machine, this is performed to check for the presence of interference between the cutter and the workpiece. In the NC machining simulation for the interference check, when the cutter is moved in accordance with the cutter location data indicating the moving trajectory of the cutter or the NC program for actually controlling the NC machining machine in the NC machining simulation system, the cutter is moved. Is checked computationally based on cutter data representing a cutter and workpiece model data representing a workpiece model. Therefore, in order to perform an interference check simulation, workpiece model data and cutter location data or an NC program are required.

For this purpose, conventionally, workpiece shape data defining the shape of a workpiece and machining information such as cutter location data and NC programs are imported from a CAD / CAM system into an NC machining simulation system. Has been used to perform an NC machining simulation. However, the upstream CAD / CA
Since the format is usually different between the M system and the NC machining simulation system on the downstream side,
It took a lot of time to capture the data. Usually, the data file of the CAD / CAM system is an intermediate file, ie, an image (initial graphics exchange).
specification files), and the images file is converted to a data file for the NC machining simulation system. However, it takes a lot of time to acquire this data, especially to acquire the workpiece shape data.

[0004] Workpiece shape data generally includes approximated surface data that approximately represents a curved surface of a workpiece, and the approximated surface data is taken into a data file for an NC machining simulation system via an "iges" file. However, due to differences in approximation tolerance (tolerance) and curved surface expression (approximate expression) in the upstream CAD / CAM system and those in the downstream NC machining simulation system, so-called surface omission and trimming. Release occurs. Missing is that a gap is created between adjacent surfaces.
A situation occurs in which it is not possible to obtain a target curved surface by trimming the periphery of a large curved surface, and when these occur, the worker changes the approximate curved surface data on the upstream side, By correcting the approximated curved surface data on the downstream side, it is necessary to eliminate missing or trim release, and this operation requires a lot of time.

[0005] As described above, instead of directly taking in the workpiece shape data, in the CAD / CAM system,
From the workpiece shape data, an outline representing the outer shape of the workpiece when the workpiece is cut by a plurality of cutting planes separated from each other, that is, data representing a scan line is created (for example, data of the CAD function). This scan line data is taken into an NC machining simulation system and used as a substitute for the workpiece model data. And the scan line is curve data, so that an images file is also required.

Japanese Unexamined Patent Publication (Kokai) No. 61-279979 discloses a technique for automatically performing various types of data processing on a thin sheet component manufactured by cutting, bending, or the like of a thin sheet material. Have been. The thin plate part is divided into specific data items in units of planes constituting the part, described in words according to the prescribed rules, and input to the computer from the key input means, and the data is input to the computer based on the input data. The document describes that a triangular drawing of a part, a development view, cutter location data for causing the NC processing machine to cut out the development material, a simulation program for bending the cut development material, and the like are automatically created. However, this publication does not describe performing a simulation of a cutting process by an NC processing machine based on cutter location data.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has been made to enable an NC machining simulation to be performed in a short time. In particular, the present invention utilizes cutter location data. The object of the present invention is to make it possible to create workpiece model data for NC machining simulation in a short time.
A processing simulation method and a method of creating workpiece model data for NC processing simulation are obtained. Each mode is divided into terms as in the claims, and each term is numbered,
Enter the number of another section as necessary.
This is to clarify the possibility of combining the features described in each section. (1) The cutter location data is taken into the NC machining simulation system from the CAM system, the work model data representing the work model and the simulation operation program are created from the taken cutter location data, and the work model data is created. An NC machining simulation method for performing an NC machining simulation of a workpiece model using the simulation and a simulation operation program (claim 1). Since cutter location data is an ordered set of point data, CA
Since the cutter location data can be taken directly from the M system to the NC machining simulation system without going through the images file, the data amount is small compared to the workpiece shape data including the approximate surface data. In addition, the time required for taking in data can be reduced. Further, when the cutter location data is fetched, a situation similar to a dropout or a trim release does not occur, so that a great deal of work time can be saved for eliminating these. In addition, the cutter location data becomes data representing the shape of the product itself after machining if the cutter radius is designated as 0, and the cutter location data before machining, such as casting, if the cutter radius is designated equal to the cutting allowance. Since the data represents the shape of the workpiece, these data can be used as workpiece model data according to the purpose. It is also easy to create a simulation operation program from cutter location data. Therefore, the data processing time after taking in the cutter location data can be shortened. Further, since the cutter location data is simpler data than the workpiece shape data including the approximated curved surface data, the calculations required for the interference check and the like are simple, and this point is also necessary for the NC machining simulation. Can save time. Also, by approximating the polygonal line represented by the cutter location data with one line segment at a time within the permissible error range, each part of the polygonal line is approximated by a new polygonal line having a small number of polygonal points, and a new cutter having a small data amount is obtained. It is easy to use location data. Since the workpiece shape data and the scan line data are generally a set of approximate curved surface data and approximate curve data, the data amount cannot be easily reduced in this way. In addition, it seems that it does not seem so meaningful at first glance to perform interference check using two cutter location data where the cutter radius is specified as the cutting allowance and the radius of the cutter actually used. Depending on the shape of the workpiece, particularly the shape of the concave portion, interference between the workpiece and the cutter often occurs, and this interference can be sufficiently detected using the above two cutter location data. it can. (2) A method for creating workpiece model data for NC machining simulation in which cutter location data is taken into the NC machining simulation system from the CAM system, and workpiece model data representing the workpiece model is created from the taken cutter location data. Claim 2). (3) The workpiece model data indicates that the radius of the cutter is zero.
Cutter location data created as (2)
Item 3. The method for creating workpiece model data for NC machining simulation according to the paragraph [1]. Cutter location data with a cutter radius of 0 can be easily created in a CAM system. (4) The method of creating workpiece model data for NC machining simulation according to the above mode (2), wherein the workpiece model data is cutter location data created by setting a cutter radius equal to a cutting allowance. Cutter location data with the cutter radius equal to the shaving allowance can be easily created in a CAM system. (5) In the process of creating the workpiece model data, the cutter location data is converted into a cutter location representing another polygonal line having a small number of polygonal points within a predetermined allowable error range of the polygonal line represented by the cutter location data. Includes data volume reduction process to convert to data (2)
Or (4) The method for creating workpiece model data for NC machining simulation according to any one of (4) to (4). If the data amount of the cutter location data is reduced by the data amount reduction step, the capacity of the data storage means can be reduced, and the amount of calculation during the simulation operation can be reduced, and the time required for the simulation can be reduced. . Note that the data amount reduction process can be executed in the CAM system. In this case, the cutter location data after the data amount reduction process
Since the data is taken into the processing simulation system, the time required for taking data is reduced. (6) The cutter location data includes a plurality of groups of cutter location data created in a plurality of directions parallel to each other and parallel to the surface of the workpiece. The method for creating workpiece model data for NC machining simulation described above. The cutter location data used for the NC machining simulation is as follows:
It may be formed only along a plurality of intersections between a plurality of substantially parallel surfaces (including planes and curved surfaces), such as a plurality of parallel planes, and the surface of the workpiece. In order to improve the reliability of the simulation, for example, in order to more reliably check the interference between the cutter and the workpiece, two groups of planes, each consisting of a plurality of planes parallel to each other and orthogonal to each other, are used. It is desirable that the object be created along the intersection line between the plurality of groups of intersecting faces and the workpiece. The features of the above items (3) to (6) are applicable to the NC machining simulation method of the item (1).

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a system including an NC machining simulation system for performing an NC machining simulation method using a workpiece model data created by the method according to the present invention; It is a block diagram showing the whole. This system includes a high-order CAD system 10, a CAD / CAM system 12, and an NC machining simulation system 14, each of which is mainly a computer.
They are connected by a network 16.

In the high-order CAD system 10, three-dimensional shape data representing the three-dimensional shape of a product is created. An example is shown in FIG. In this figure, 3 represented by a solid line
Each region surrounded by more than one curve and having a cross drawn by broken lines inside is one curved surface represented by one approximate expression. The three-dimensional shape data created by the high-order CAD system 10 is taken into the CAD / CAM system 12 according to the operation of the manual input device 20 according to the system software of the processing unit 22, and stored in the storage unit 24. Various operations of the manual operation input device 20 including the operation at this time are as follows.
This is performed according to the guidance displayed on the display device 26 such as a CRT display according to the system software. The input data is also displayed on the display device 26.

FIG. 2 is a functional block diagram of the processing section 22 which operates according to the system software. The three-dimensional data capturing unit 40 is a part that captures the three-dimensional shape data.
The machining area setting unit 42 sets the machining area based on the command from the CPU, and the cutter location data (hereinafter abbreviated as CL data) automatic calculation unit 44 automatically calculates the CL data. Since this CL data automatic calculation is well known, detailed description is omitted, but as shown in FIG. 7, based on the three-dimensional shape data stored in the storage unit 24 and the cutter radius r. Done. For example, the value of the cutter radius r is set to 0, the radius equal to the cutting allowance, the radius of the cutter actually used (for example, the radius of the tip hemisphere of the ball end mill) and the like, and the CL data for each value is specified. Is calculated.
Then, the acquired CL data is stored in the storage unit 24 and sent to the NC processing simulation system 14 via the network 16. Note that the actual NC
CL data for processing is generally created only along a plurality of intersections between a plurality of substantially parallel surfaces, such as a plurality of parallel planes, and the surface of the workpiece.
It is desirable that the CL data for the C processing simulation is created along the intersection line between the plurality of groups of intersecting surfaces and the workpiece. In the present embodiment, it is assumed that each of the planes is formed along a line of intersection between two groups of planes that are parallel to each other and that are orthogonal to each other and the surface of the workpiece. Depending on the shape of the workpiece and the purpose of the NC machining simulation, in addition to the two groups of planes described above, another two groups of plane groups intersecting the plane group at an intersection angle of 45 degrees and the surface of the workpiece may be used. In some cases, it may be desirable to create CL data along the intersection line of, or to change each of the planes to a curved surface.

NC machining simulation system 14
Also, the same manual operation input device 30, processing unit 32, storage unit 34 and display device 3 as in the CAD / CAM system 12 are used.
6 is provided. FIG. 3 shows a functional block diagram of the processing unit 32. In the CL data capturing unit 50, CL data is captured from the CAD / CAM system 12 in accordance with a command input from the manual operation input device 30. In the present embodiment, various CL data created in the CAD / CAM system 12 are continuously taken in as the value of the cutter radius r of 0, the cutting allowance, the radius of the cutter to be used, and the like. It is also possible to take in CL data corresponding to the cutter radius as needed. After capturing the CL data, the CL data
A simulation operation program is created in the L data / operation program conversion unit 52, and work model data is created in the CL data / work model conversion unit 54. Based on the created simulation operation program and workpiece model data, the simulation operation unit 56 performs an interference check, which is a kind of simulation operation.

The creation of the operation program in the CL data / operation program converter 52 is performed by executing the operation program creation program shown in the flowchart of FIG. In step 1 (hereinafter abbreviated as S1; the same applies to other steps), a CL data file name and a processing condition are selected. C is formed on the assumption that a target processing area of a target workpiece is processed by a cutter having a predetermined cutter radius.
The CL data file name of the L data is selected, and at the same time, data for designating the fixed posture and position of the workpiece is input.

In S2, the header and the footer are deleted. Two sets of data placed at the beginning and end of CL data created as an operation program for actually performing the NC processing are deleted. Subsequently, after the header for the NC machining simulation operation is created in S3, the execution of S4 to S6 is repeated to create the operation data for the NC machining simulation. In S4, the three-dimensional coordinates of each point are sequentially read one by one, converted into coordinate data for processing machine operation in S5, and determination of whether or not the end of the file is performed in S6 is repeated. The CL data is created as data representing the movement position of the cutter in the reference coordinate space in which the workpiece is stationary at a specific position in a specific posture, but actually, the CL data is The mounting orientation and position on the processing machine may be different from those described above, and only the workpiece, or both the workpiece and the cutter may be moved,
In S5, the CL data is converted into coordinate data that defines the movement position of each part of the processing machine in accordance with these circumstances. When the coordinate conversion for all points is completed, a footer for the NC machining simulation operation is created in S7 to complete the simulation operation program, and stored in the storage unit 34 in S8.

The CL data / workpiece model converter 54
The creation of the workpiece model data in is performed by executing the workpiece model data creation program shown in the flowchart of FIG. In step S11, a CL data file name (a file name of the CL data in which the cutter radius r is designated as a cutting margin) is selected, and an allowable error or the like is input. In step S12, a header and a footer are deleted. The selection of the CL data file name and the deletion of the header and footer are performed by the CL data / operation program conversion unit 5.
As in 2. The CL data in which the cutter radius r is specified as the cutting allowance is data representing a workpiece obtained by adding the cutting allowance to the three-dimensional shape data created in the upper CAD system 10. The following CL data means CL data for creating the workpiece model data. The allowable error will be described later.

Subsequently, in S13, after the coordinate values of the first two points among the coordinate values of many points included in the CL data are set to the coordinate values of the point A and the point B, S14 to S20 Is repeated, the data amount of the CL data is reduced. In the NC machining simulation, the accuracy is not required as much as in the actual NC machining.
A polygonal line (CL line) represented by the L data is converted into a simpler CL line (a model in which the CL line represents the model to be machined) having a small number of polygonal points (CL points) within the range of the tolerance input in S11. The conversion of the CL data is performed so as to approximate with (used as a line).

In S14, the coordinate value of the next point (the third point when S14 is executed first) is set as the coordinate value of point C, and an approximate error is calculated in S15.
As shown in FIG. 8A, an approximation error is calculated when the CL line formed by the line segment AB and the line segment BC is approximated by the line segment AC. And (1) of FIG.
Indicates a case where this approximation error is out of the permissible error range, that is, a case where the approximation error is larger than the permissible error. In this case, the determination result in S16 is NO, and in S17, A
The point is a model point which is a break point of the model line representing the workpiece model. Subsequently, in S18, as shown in (2) of FIG. 8, the B point so far becomes a new A point, and the C point becomes a B point.
It is changed to a point, and it is determined in S20 whether or not the data is the end data of the file currently being processed. Normally, NO
Therefore, in S14, the coordinate value of the next point is
The coordinate values of the points are set, and in S15, the approximation error shown in (2) of FIG. 8 is calculated.

On the other hand, as shown in FIG. 9A, when the calculated approximation error is within the allowable error range,
The result of the determination in S16 is YES, and in S19 the previous point C is changed to a new point B. Since the determination result in S20 is normally NO, S14 is executed, and the approximate calculation in S15 is performed after the next point is set as the C point. In this approximation calculation, as shown in FIG. 9 (2), the distance from the line segment AC is calculated for both the previous B point and the new B point. Here, not only the distance from the new point B to the line segment AC, but also the distance from all points located between the current point A and the point C to the line segment AC, that is, the distance between the point A and the point C. The approximation errors for all points located at are calculated for the following reasons. When the CL line has the shape shown in FIG. 10A and the approximation error at the new point B is the maximum, only the approximation error at the new point B needs to be calculated. In the case of the shape shown in FIG. 10 (2), the approximation error for the new point B may be outside the allowable error range while the approximation error for the previous point B may be outside the allowable error range. Get, in this case,
If the approximation error is calculated only for the new point B, there is a possibility that an erroneous determination may be made that the point is within the allowable error range even though it is actually outside the allowable error range. This possibility increases as the number of CL points located between points A and C increases, as shown in (3) of FIG. Therefore, in the present embodiment, approximation errors are calculated for all points located between the points A and C.

If all the approximation errors shown in (2) of FIG. 9 are within the permissible error range, the judgment result in S16 becomes YES, S19 and S14 are executed again, and a line approximated by one line segment is obtained. Although the number of minutes is increased, if any of the approximation errors shown in (2) of FIG. 9 is out of the allowable error range, in S17 and S18, as shown in (3) of FIG. The point B is a new point A, and the previous point C is a new point B. As a result, the two line segments of the CL line shown in FIG. 9A are approximated by one line segment shown in FIG. 9C. Then, in S14, the next point is the new C
A similar process is repeated so that the calculation of the approximation error is performed on the new point B in S15, so that the CL line is reduced by as few CL points as possible within the allowable approximation error. It is converted to the specified CL line. Eventually, the determination result of S20 becomes YE
If S, in S21 and S22, the points that were respectively set to B and C at that time are both new C.
By setting the CL point (model point) of the L line (model line), CL data after data amount reduction (this is the workpiece model data) is completed.
4 is stored. FIG. 11 shows an example of the model line. In this figure, the model line looks like a curve because the distance between the CL points is small, but it is actually a broken line.

An interference check is performed in the simulation operation section 56 based on the simulation operation program created as described above and the workpiece model data. It is assumed that the cutter is moved along the CL line, and the relative position between the cutter and the workpiece model is displayed on the display device 36 at regular small time intervals, and the interference state between the two is checked. . At this time, as the cutter model, only the tip hemisphere part of the ball end mill that is actually scheduled to be used, the radius of which is reduced by the cutting allowance is used, and this cutter model and the workpiece model If they do, it is determined that interference between the cutter and the workpiece has occurred. As the cutter model, it is possible to use a model of the cutter alone, but it is also possible to use a model of a cutter peripheral member including a member that moves together with the cutter, such as an adapter and a chuck.

In the above-described embodiment, the CAD / CAM system 12 creates a plurality of types of CL data such as CL data for simulation operation and CL data for a workpiece model obtained by adding a cutting allowance to a three-dimensional shape of a product. , Is taken in the NC machining simulation system 14, but in the CAD / CAM system 12, the CL data is created with the cutter radius as a general value r, and the NC machining simulation system 14 By specifying r to a specific value, CL data for simulation operation,
It is also possible to create a plurality of types of CL data such as CL data for a workpiece model. In addition, the present invention can be implemented in various modified and improved aspects.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an entire system including an NC processing simulation system for performing an NC processing simulation method of the present invention.

FIG. 2 is a functional block diagram of a processing unit of the CAD / CAM system in FIG.

FIG. 3 is a functional block diagram of a processing unit of the NC processing simulation system in FIG. 1;

FIG. 4 is a flowchart showing a program stored in a CL data / operation program conversion unit in FIG. 3;

FIG. 5 is a flowchart showing a program stored in a CL data / workpiece model conversion unit in FIG. 3;

FIG. 6 is a diagram illustrating an example of a three-dimensional shape represented by three-dimensional shape data created in the upper CAD system of FIG. 1;

FIG. 7 is a diagram for explaining conversion from three-dimensional shape data to CL data in the CAD / CAM system of FIG. 1;

FIG. 8 is a diagram for explaining a reduction in the amount of CL data by executing a program represented by the flowchart of FIG. 5;

FIG. 9 is a diagram for explaining a reduction in the amount of CL data by executing a program represented by the flowchart of FIG. 5;

10 is a diagram for explaining a reduction in the amount of CL data by executing a program represented by the flowchart of FIG. 5;

11 is a diagram illustrating an example of a workpiece represented by workpiece data created by executing a program represented by the flowchart of FIG. 5;

[Explanation of symbols]

12: CAD / CAM system 14: NC processing simulation system 16: Network 30: Manual operation input device 3
2: processing unit 36: display device 50: CL data acquisition unit 52: CL data / operation program conversion unit
54: CL data / workpiece model conversion unit 56: Simulation operation unit

Claims (2)

[Claims] 1. A cutter location data is taken in from a CAM system into an NC machining simulation system, and workpiece model data representing a workpiece model and a simulation operation program are created from the taken cutter location data. An NC machining simulation method characterized by simulating NC machining of a workpiece model using model data and a simulation operation program. 2. An NC machining simulation system according to claim 1, wherein the cutter location data is taken from the CAM system into an NC machining simulation system, and workpiece model data representing a workpiece model is created from the taken cutter location data. Workpiece model data creation method.