JPH0981221A - NC data creating apparatus and correction data creating method thereof - Google Patents

Abstract

(57) Abstract: It is possible to correct the tool diameter of a cutting tool that has a flat circular portion at the tip of the end of the cutting portion and an edge portion having a circular cross section with an arc of radius R around it. Of a simple NC data creation device and its correction data creation method. A contour line of a machining shape is extracted from CAD graphic data of a machining object generated in advance. Further, the tool shape data generated in advance for the cutting tool is separated into the edge portion of the tool and the virtual cylindrical tool. Next, a virtual contour line is created by offsetting the extracted contour line of the machining shape by the radius R of the edge portion of the radius end mill, and the virtual contour line is sequentially traced at the edge portion of the virtual cylindrical tool to obtain the tool trajectory. . Further, data indicating the correction direction and size of the tool and the movement trajectory of the tool before and after machining are added, and the data is output as a file as tool trajectory data.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an NC data creating apparatus for creating NC data of a numerically controlled machine tool and a correction data creating method therefor, and more particularly to an NC data creating apparatus capable of correcting a tool diameter of a cutting tool and its correction. Regarding data creation method.

[0002]

2. Description of the Related Art In a numerically controlled machine tool, that is, an NC machine tool, when an object to be machined is processed by a rotary tool such as an end mill using a machining center,
The trajectories of these tools are controlled with respect to the center of the rotary shaft of the NC machine tool. FIG. 11 shows this relationship.

FIG. 11 is a diagram showing a relationship between a tool locus and a contour shape of a workpiece as a conventional example.

In this case, the operator calculates the locus A of the tool center portion which is offset by the tool radius with respect to the contour shape B of the object to be machined, and stores the locus data of the tool center portion in the NC data creating device. There is a need. For this reason, the number of preparation steps before work becomes a problem. In addition, when an NC machine tool is used to machine an object using this NC data, variations in the tool diameter due to the manufacturing error of the tool itself, rotation accuracy of the rotary axis, and tool deflection due to cutting resistance during machining are added. However, high precision machining cannot be expected.

As a solution to this problem, correction of the tool diameter using a calculation function in a control unit on the NC machine tool (not shown) side is used. When using the tool diameter correction function, the NC data creation device adds NC data, which is added to the contour shape of the workpiece to indicate the direction in which correction is required, as shown by the arrow in FIG. 12, to the NC machine tool. provide.

FIG. 12 is a diagram showing a relationship between a tool trajectory to which a correction direction is added and a contour shape of an object to be machined as a conventional example.

In this case, the operator sets a vector (arrow in the figure), which is correction data indicating the size and direction of the tool center to be offset, and the contour shape AA of the object to be processed in the NC data creating device. To do. Then, the control data of the NC machine tool refers to this tool diameter correction data at the time of machining,
By calculating the locus BB of the tool center portion offset by the correction data with respect to the tool movement command and operating as the locus of the tool, the above-described tool manufacturing error, rotation accuracy, tool bending amount, and other machining errors It can be excluded from the factors.
This tool diameter correction function is generally used for two-dimensional machining using a square end mill and three-dimensional machining using a ball end mill.

[0008]

However, in the above-mentioned conventional example, in the conventional NC data in which the correction direction is added to the contour shape of the object to be processed, the center of the rotary axis of the cutting tool and its center such as the square end mill and the ball end mill are used. It is effective when the distance between the end of the tool and the point of contact with the workpiece is always the same. However, in the case of a cutting tool such as a radius end mill where the distance between the center of the rotating axis of the cutting tool and the contact point with the processing object at the end of the tool changes depending on the shape of the processing surface required for the processing object. Cannot handle the tool diameter as a constant value, so the above-described tool diameter correction function cannot be used. 13 and 14 show the positional relationship between the tool and the contact point of the workpiece in this case.
Shown in

FIG. 13 is a diagram showing a positional relationship between a radius end mill as a conventional example and a contact point of a workpiece.

FIG. 14 is a diagram showing a positional relationship between a radius end mill as a conventional example and a contact point of a workpiece.

13 and 14, X and Y are contact points between the radius end mill 25 and the object to be machined (hatched portion), and D1 and D2 are apparent tool diameters of the radius end mill 25.

This radius end mill is a machined rounded end of a square end mill. It prevents wear and chipping of sharp edges, which are the drawbacks of square end mills, and prolongs tool life, while reducing the roughness of the machined surface. This has the effect of improving the processing quality. However, since there is no NC data creation device that can add the above-described tool diameter correction function to the radius end mill, there is a problem that it cannot be applied to machining that requires high accuracy.

Therefore, according to the present invention, it is possible to correct the tool diameter of a cutting tool having a flat circular portion at the tip of the end of the cutting portion and an edge portion having a circular cross section with an arc having a radius R around it. It is an object to provide an NC data creating device and a correction data creating method thereof.

[0014]

In order to achieve the above-mentioned object,
The NC data creation device of the present invention has the following features.

That is, in an NC data creating apparatus for creating NC data used in a numerically controlled machine tool, means for extracting a contour line from previously generated shape data of a workpiece and a tip of an end of a cutting portion are provided. From the pre-generated shape data of a cutting tool having a planar circular portion and an edge portion whose cross-sectional shape is formed by an arc having a radius R, the data of the end of the cutting tool and the virtual cylindrical tool data. And a means for calculating virtual contour line data by offsetting the contour line by the radius R of the cutting tool end, and a virtual cylindrical tool based on the calculated virtual contour line data. Means for adding data representing the direction of the offset when moving.

By using the virtual cylindrical tool, the tool diameter of the cutting tool in which the contact surface between the center of the cutting portion of the tool and the object to be processed changes is corrected.

Furthermore, the size of the circular portion at the end of the virtual columnar tool is equal to the planar circular portion at the end of the cutting tool.

In this way, the actual shape of the tool is idealized as simply as possible.

Alternatively, the means for calculating the virtual contour line data calculates the detour locus for preventing over-cutting beyond the virtual contour line due to the movement of the virtual cylindrical tool during the calculation. Characterize.

This prevents interference with the virtual contour line of the virtual cylinder tool due to having a length corresponding to the diameter of the virtual cylinder.

Alternatively, the shape data of the processing object is 2
It is characterized by being a dimensional plane. Alternatively, when the shape data of the processing object has a three-dimensional surface in the XYZ system, the shape data is XY, YZ, ZX.
It is characterized in that the tool diameter of the cutting tool is corrected based on the contour line extracted from each of the cross sections parallel to any of the planes.

By dividing the three-dimensional object into three two-dimensional planes, the tool diameter can be corrected by the virtual cylindrical tool.

To achieve the same object, the correction data creating method of the NC data creating device of the present invention has the following features.

That is, in the correction data creating method of the NC data creating device for creating the NC data used in the numerically controlled machine tool, the contour line is extracted from the shape data of the object to be machined generated in advance, and the end portion of the cut portion is extracted. From the shape data generated in advance of a cutting tool having a flat circular portion at the tip and an edge portion having a cross-sectional shape formed by an arc having a radius R around the tip, data of the cutting tool end and a virtual cylinder Tool data is calculated, virtual contour data obtained by offsetting the contour by the radius R of the cutting tool end is calculated, and the virtual cylindrical tool is moved based on the calculated virtual contour data. It is characterized in that data representing the direction of the offset when adding is added.

By using the virtual cylindrical tool, the tool diameter of the cutting tool in which the contact surface between the center of the cutting portion of the tool and the object to be processed changes is corrected.

Furthermore, the size of the circular portion at the end of the virtual columnar tool is equal to the planar circular portion at the end of the cutting tool.

This makes the actual shape of the tool ideal as simple as possible.

Alternatively, when calculating the virtual contour line data, a detour locus for preventing excessive cutting beyond the virtual contour line due to the movement of the virtual cylindrical tool is calculated.

This prevents interference with the virtual contour line of the virtual cylinder tool due to having a length corresponding to the diameter of the virtual cylinder.

Alternatively, the shape data of the workpiece is 2
It is characterized by being a dimensional plane. Alternatively, when the shape data of the processing object has a three-dimensional surface in the XYZ system, the shape data is XY, YZ, ZX.
It is characterized in that the tool diameter of the cutting tool is corrected based on the contour line extracted from each of the cross sections parallel to any of the planes.

By dividing a three-dimensional object into three two-dimensional planes, the tool diameter can be corrected by a virtual cylindrical tool.

[0032]

DETAILED DESCRIPTION OF THE INVENTION An embodiment of the present invention will be described below with reference to the accompanying drawings.

First, the main part of the NC data creating apparatus to which the present invention is applied will be described with reference to FIG.

FIG. 1 is a block diagram showing the outline of an NC data creating apparatus to which the present invention is applied.

In the figure, 10 is an NC data creating device,
An NC machine tool 20 and a CAD / CAM engineering workstation (EWS) 21 are connected via a communication interface 9 which is a communication means, and various mutual data communication is possible. NC data creation device 10
Is a CPU 1 for generating NC data from CAD data, which is a basis for generating NC data of a workpiece, a tool diameter correction process described later, an input unit 2 such as a keyboard for inputting data and parameters, and data. CRT or other display unit 3 for displaying information such as parameters and parameters, output unit 4 such as a printer, generation of fixed parameters and NC data, ROM 6 for storing programs such as tool diameter correction processing, which will be described later, temporary variable parameters It is provided with a RAM 7 used as a storage and a working area, a storage device 8 such as a hard disk drive or a floppy disk drive, and the communication interface 9 described above, and is communicably connected by a bus 5 for internal communication.

Next, the software processing in the NC data creating apparatus will be described with reference to FIGS.

FIG. 2 shows an NC as an embodiment of the present invention.
It is a processing block diagram of software of a data creation device.

In the figure, CA from the figure data reading unit 11
The graphic data created by the D / CAM EWS 21 is read, and the shape to be processed is taken out by the processing shape extraction unit 12. The tool to be used is input by the operator via the tool input unit 13. If the shape of the tool is registered in the tool shape storage unit 14 in advance, the tool to be used can be designated by a simple input such as a code. If a radius end mill, which is a kind of cutting tool, having a flat circular portion at the tip of the end of the cutting portion and an edge portion having a cross-sectional shape formed by an arc having a radius R around the radius end mill is specified, the radius end mill is specified. The shape data of the end mill is separated by the tool shape interpretation unit 15 into an R portion of the edge portion of the radius end mill and a virtual cylindrical tool described later. Then, based on the machined shape and the tool shape, the NC data creation section 16 creates NC data with the tool diameter correction data added to the radius end mill, and stores it in the NC data storage section 18. NC created
It goes without saying that the data can be displayed as a tool locus on the display device 17. Then, the created NC data is converted into the NC language used by the NC machine tool 20 in the post processor unit 19 and transmitted to the NC machine tool 20 via the communication interface 9 or a storage medium such as a floppy disk. Passed through.

Next, the NC in the NC data creation unit 16
The flow of data creation processing will be described with reference to FIGS.

FIG. 3 shows an NC as an embodiment of the present invention.
It is a flow chart which shows creation processing of data.

In the figure, in step S1, the contour line 27 (s1-c1-c2-s2) of the machining shape of FIG. 6 is extracted from the CAD figure data of the machining object of FIG.

FIG. 5 is a diagram showing the shape of CAD graphic data of the object to be processed as an embodiment of the present invention.

FIG. 6 is a view showing a contour line of a processed shape of a processing object as one embodiment of the present invention.

Next, in step S2, the tool shape data of the radius end mill 25 is separated into the edge portion of the tool and the virtual cylindrical tool 25 and handled as shown in FIG.

FIG. 4 is a view showing the shape of a radius end mill as an embodiment of the present invention.

In the figure, the shaded area is the radius end mill 25.
3 shows a cross section of a virtual cylindrical tool 26 for treating the virtual cutting tool as a virtual cylindrical cutting tool. The virtual cylindrical tool 26 has a length L and a diameter D. The shape of the edge portion of the radius end mill 25 includes a circular portion having a radius R and a linear portion having a length D. However, L = (effective length of the radius end mill 25) -RD = (outer diameter of the cutting part of the radius end mill 25) -2 ×
R.

In step S3, the virtual contour line 28 of FIG. 7 is created by offsetting the contour line 27 of the machining shape taken out in step S2 by the radius R of the edge portion of the cutting tool.

FIG. 7 is a diagram showing a contour line of a virtual machining shape of a machining object as one embodiment of the present invention.

In the figure, (ss1-cc1-cc2-ss)
2) is the virtual contour line 28, and the broken line on the outside is the contour line 27 of the actual object to be processed.

In step S4, the movement trajectory of the virtual cylindrical tool 26 with respect to the virtual contour line 28 is obtained. The virtual contour line 28 is sequentially traced at the edge of the virtual cylindrical tool 26,
Find the tool path. Here, (cc1-cc2) of FIG.
When the radius end mill 25 traces the virtual contour line 28 in the actual cutting as described above, if too much cutting is performed than the cutting of the contour line 27 of the target machining shape, the bypass route sss3 is added to consider the excessive cutting. The tool locus of FIG. 8 (sss1-ccc1-sss3-ccc2-s
ss2) is calculated. In addition, the part where excessive shaving occurs
This can be easily calculated by utilizing the size of the virtual cylindrical tool 26 obtained in step S2 and comparing the coordinates of the loci of the two edges of the virtual contour line 28 and the virtual cylindrical tool 26 described above. It should be noted that the points are interpolated by straight lines or arcs by a general method to obtain a continuous tool locus. In addition, the shaving of the bottom of the object to be processed is (sss1-ccc1-sss3
After processing (-ccc2-sss2), another tool is used.

FIG. 8 is a diagram showing the trajectory of the virtual cylindrical tool as an embodiment of the present invention.

In step S5, points (p1 to p8) representing the characteristics of the shape of the virtual contour line 28 at the contact point between the edge portion of the virtual cylindrical tool 26 moving in the tool path obtained in step S4 and the virtual contour line 28. ), The correction data of the virtual cylindrical tool 26 is obtained. As for the correction direction of the tool, since the tool to be cut is considered as the virtual cylindrical tool 26,
As shown in FIG. 9, a direction perpendicular to the central axis Io of the tool is set from the contact points (p1 to p8) between the virtual contour line 28 and the virtual cylindrical tool 26. Also, the magnitude of the correction amount, that is,
The offset amount may be calculated as R at each point.

FIG. 9 is a diagram showing a locus of a virtual cylindrical tool to which a tool correction direction is added as an embodiment of the present invention.

In step S6, a movement operation from the initial position of the radius end mill 25 to the processing start position and the processing end position of the processing target object to the initial position is added.

FIG. 10 shows N as an embodiment of the present invention.
It is a figure which shows the example of C data.

In the figure, the tool correction direction obtained by the above procedure is set as an item of the tool correction data at each point (p1 to p8) with respect to the tool movement center point p0.
In addition, here, as the tool correction data (arrow in the figure),
Only the correction direction of the tool on the ZX plane is represented by -1, 0, 1. Further, the type of interpolation between points and the center coordinates in the case of circular interpolation are also stored together.

In step S7, the created tool path data is stored in the NC data storage section 18 and output to the post processor section 19 to end the processing.

Although the above embodiment is directed to the cross section of the object to be processed on the XZ plane, the same procedure is applied to the YZ and XY planes. For the three-dimensional surface, the virtual contour shape of the three-dimensional surface shape offset by the radius R in step S3 is XY, YZ, ZX.
The processing can be performed in the same manner as in the above method by cutting along a plane and treating each as a virtual contour line of a two-dimensional cross section.

The present invention may be applied to a system composed of a plurality of devices or an apparatus composed of a single device as in this embodiment. Further, it goes without saying that the present invention can be applied to the case where it is implemented by supplying a program to a system or an apparatus. In this case, the storage medium storing the program according to the present invention constitutes the present invention. Then, by reading the program from the storage medium to the system or device, the system or device operates in a predetermined manner.

<Effects of Embodiment> (1) By handling the locus of the radius end mill 25 by dividing it into the R part at the end of the radius end mill 25 and the virtual cylindrical tool 26, the manufacturing error and rotation of the tool of the radius end mill itself The tool diameter has been corrected to eliminate the factors that cause machining errors due to axis errors and machining resistance. (2) Since the edge portion of the virtual cylindrical tool 26 is moved along the virtual contour line 28, the vector (arrow in FIG. 9), which is the correction data, is simple in both size (R) and direction (right angle to Io). Was able to handle. (3) By using the calculated size of the virtual cylindrical tool 26, by comparing the coordinates of the loci of the two edges of the virtual contour line 28 and the virtual cylindrical tool 26, the detour of the tool is calculated. In the actual cutting process, it was possible to prevent the end portion of the radius end mill 25 from cutting the object to be processed more than necessary.

[0061]

As described above, according to the present invention, there is provided a cutting tool having a flat circular portion at the tip of the end of the cutting portion and an edge portion having a circular cross section with a radius R around the periphery. It is possible to provide an NC data creation device capable of correcting a tool diameter and a correction data creation method thereof.

[0062]

[Brief description of drawings]

FIG. 1 is a block configuration diagram showing an outline of an NC data creation device to which the present invention is applied.

FIG. 2 is a processing block diagram of software of the NC data creation device as one embodiment of the present invention.

FIG. 3 is a flowchart showing NC data creation processing as an embodiment of the present invention.

FIG. 4 is a diagram showing a shape of a radius end mill as one embodiment of the present invention.

FIG. 5 is a CA of an object to be processed as an embodiment of the present invention.
It is a figure which shows the shape of D graphic data.

FIG. 6 is a diagram showing a contour line of a processed shape of a processing object as one embodiment of the present invention.

FIG. 7 is a diagram showing a contour line of a virtual machining shape of a machining object as one embodiment of the present invention.

FIG. 8 is a diagram showing a trajectory of a virtual cylindrical tool as an embodiment of the present invention.

FIG. 9 is a diagram showing a trajectory of a virtual cylindrical tool to which a tool correction direction is added as an embodiment of the present invention.

FIG. 10 is a diagram showing an example of NC data according to an embodiment of the present invention.

FIG. 11 is a diagram showing a relationship between a tool trajectory and a contour shape of a processing object as a conventional example.

FIG. 12 is a diagram showing a relationship between a tool trajectory to which a correction direction is added and a contour shape of a processing object as a conventional example.

FIG. 13 is a diagram showing a positional relationship between a radius end mill as a conventional example and a contact point of an object to be processed.

FIG. 14 is a diagram showing a positional relationship between a radius end mill as a conventional example and a contact point of a workpiece.

[Explanation of symbols]

 1 CPU 2 Input part 3 Display part 4 Output part 5 Bus 6 ROM 7 RAM 8 Storage device 9 Communication interface 10 NC data creation device 11 Graphic data reading part 12 Machining shape extraction part 13 Tool input part 14 Tool shape storage part 15 Tool shape Interpretation unit 16 NC data creation unit 17 Display unit 18 NC data storage unit 19 Post processor unit 20 NC machine tool 21 CAD / CAM EWS 25 Radius end mill 26 Virtual cylindrical tool 27 Contour line of machining shape 28 Virtual contour line

Claims (10)

[Claims] 1. An NC data creating device for creating NC data used in a numerically controlled machine tool, comprising: means for extracting a contour line from pre-generated shape data of an object to be machined; From the pre-generated shape data of a cutting tool having a planar circular portion and an edge portion whose cross-sectional shape is formed by an arc having a radius R, the data of the end of the cutting tool and the virtual cylindrical tool data. And a means for calculating virtual contour line data in which the contour line is offset by a radius R of the cutting tool end portion, and the virtual columnar tool based on the calculated virtual contour line data. An NC data creation device for correcting the tool diameter of a cutting tool, comprising means for adding data indicating the direction of the offset when moving. 2. The NC data creation device according to claim 1, wherein the size of the circular portion at the end of the virtual columnar tool is equal to the planar circular portion at the end of the cutting tool. 3. A means for calculating virtual contour line data,
2. The NC data creation device according to claim 1, wherein a detour trajectory for preventing over-cutting beyond the virtual contour line due to movement of the virtual cylindrical tool is calculated at the time of the calculation. 4. The NC data creation device according to claim 1, wherein the shape data of the processing object is a two-dimensional plane. 5. The shape data of the processing object is XY-
In the case of having a three-dimensional surface in the Z system, the tool diameter of the cutting tool is corrected based on the contour line extracted from the shape data of the cross section parallel to any of the XY, YZ, and ZX planes. The NC according to claim 1,
Data creation device. 6. A correction data creation method of an NC data creation device for creating NC data used in a numerically controlled machine tool, wherein a contour line is extracted from previously generated shape data of an object to be processed, and an end portion of a cutting portion is extracted. From the pre-generated shape data of a cutting tool having a flat circular portion at the tip and an edge portion having a circular cross section with a radius R around the tip, data of the cutting tool end and virtual data are obtained. Cylinder tool data is calculated, virtual contour line data obtained by offsetting the contour line by the radius R of the cutting tool end is calculated, and the virtual columnar tool is calculated based on the calculated virtual contour line data. A correction data creation method of an NC data creation device for correcting the tool diameter of a cutting tool, characterized by adding data representing the direction of the offset when moving. 7. The correction of the NC data creating device according to claim 6, wherein the size of the circular portion at the end of the virtual columnar tool is equal to the planar circular portion at the end of the cutting tool. Data creation method. 8. A detour locus for preventing excessive shaving over the virtual contour line due to movement of the virtual cylindrical tool is calculated when calculating the virtual contour line data. A correction data creation method for the NC data creation device described. 9. The correction data creation method for an NC data creation device according to claim 6, wherein the shape data of the object to be processed is a two-dimensional plane. 10. The shape data of the object to be processed is X-
In the case of having a three-dimensional surface in the YZ system, it is possible to correct the tool diameter of the cutting tool based on the contour lines extracted from the shape data of the cross section parallel to any of the XY, YZ, and ZX planes. 7. The correction data creating method of the NC data creating device according to claim 6.