JPH10340113A - Abnormal tool path elimination method for cutting work - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an abnormal tool path elimination method for the cutting work to eliminate the pinhole or spark caused by a numerical arithmetic error when a tool path program is produced and thus to obtain a work of a correct shape. SOLUTION: The check sections are defined among the end points or intersection points of the linear segments forming a tool path. If a certain check section is set in a vacant state having no segment or the segment of the check section is discontinuous to the segment of its adjacent check section and also the segment width is smaller than the prescribed value, it is decided that this check section is caused by an arithmetic error. Then a segment is added as a tool path to connect together the segments of two check sections existing at both sides of the relevant check section.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for obtaining a predetermined workpiece by moving a rod-like processing tool to cut a workpiece, and more particularly to a method for producing a workpiece with a numerical calculation error. It is characterized by the processing of minute gaps and protrusions that occur.

[0002]

2. Description of the Related Art Conventionally, when a predetermined workpiece is formed by cutting, a cutting device that performs cutting by driving a processing tool such as a drill under computer control is used.
2. Description of the Related Art Cutting a processing material is performed.

In such a case, for example, if the processing shape is a curve 1 as shown in FIG. 5, the curve 1 is converted into a curve corresponding to the radius of the processing tool in consideration of the thickness of the processing tool (not shown). A program for a tool path along the offset shape shifted to the outside of the processing tool (outside of the processing tool) (a path along the central axis of the processing tool and based on a position above the lower end of the processing tool by a radius of the processing tool) Is created.

[0004] The tool path 2 according to this program is formed by connecting a number of short straight line segments. And
The tool path 2 is a path 3 indicated by a dashed line in FIG.
In the case where a part that interferes with the machining shape is included, the data of the part of the path 3 is deleted, and the points a and b are moved so that the processing tool passes only the uppermost path in the tool path 2. , Cutting is performed leaving only the path passing through the point c.

[0005]

However, when a program for the tool path 2 is created, a numerical calculation error may occur. Due to the numerical calculation error, a minute gap (hereinafter, referred to as a pinhole) 4 or an abnormal protrusion (hereinafter, referred to as a spark) 5 as shown in FIG.

In such a case, if the cutting is performed based on the tool path 2 according to the program including the error as described above, the processing tool is cut to the non-cutting area by the pinhole 4, and the correct shape is obtained. There is a problem that it cannot be obtained.

In addition, the spark 5 causes the processing tool to suddenly move to an abnormal location, exceeding the limit of the conditions under which the processing tool can be moved, causing an emergency stop of the apparatus or the processing tool having an abnormal processing material. There is a problem that the notch is broken or damaged.

The present invention has been made in view of such circumstances, and when a tool path program is created, even if a pinhole or a spark is generated due to a numerical calculation error, the pinhole or spark is removed to obtain a correct shape. It is an object of the present invention to provide a method for removing an abnormal tool path in a cutting process capable of obtaining a workpiece.

[0009]

In order to achieve the above object, a method of removing an abnormal tool path in a cutting process according to the present invention comprises first forming a plurality of linear segments constituting a tool path along an offset shape. The interval between the endpoints and intersections on the coordinates in the respective scanning directions is defined as an inspection section. In this case, the end points are both ends of each line segment, and the intersection is an intersection where the line segments intersect in the three-dimensional shape.

[0010] The interval between adjacent ones at each end point or each intersection is defined as an inspection interval, and a certain inspection interval is empty with no line segment or a line segment included between the adjacent inspection interval. If they are discontinuous and the width of the test section is smaller than a predetermined value (a value that is not considered to be a correct path due to a small value), the test section is considered to have been caused by a calculation error. Line segments for connecting the line segments included in the inspection sections on both sides of the inspection section are added as a tool path.

As a result, even if an error occurs in the numerical calculation, a tool path is formed by continuous line segments ignoring pinholes and sparks, so that various problems caused by pinholes and sparks occur. Can be avoided.

If the width of the empty inspection section is wider than a predetermined value, it is regarded as a correct inspection section, and the tool path passes through a preset maximum cutting depth. Such a wide empty inspection section is a part having no shape which is usually located between tool paths, and in particular, a part which does not need to be processed.

[0013] Such a portion usually corresponds to a portion such as the bottom or pedestal of a workpiece. Therefore,
A maximum cutting depth that does not affect the shape of the workpiece is set in advance, and the cutting process is performed up to that depth in the wide empty inspection section. An inspection section that is not empty but includes a wide discontinuous line segment can also be regarded as a correct section.
Therefore, in this case, if there are a plurality of line segments in the inspection section, the uppermost line segment is selected as the tool path as in the conventional example.

By performing such processing, an abnormal tool path due to a pinhole or spark can be distinguished from a correct tool path, and appropriate cutting can be performed. Next, a method of removing an abnormal tool path in cutting according to the present invention will be described in detail with reference to the drawings.

[0015]

FIG. 1 shows an example of a cutting apparatus for performing a method of removing an abnormal tool path in cutting according to the present invention. That is, in FIG.
Is an input device for inputting data such as data of a processing shape and information necessary for cutting, such as a tool speed, and sends the data to a memory 13 via a connected CPU 12 for storage.

The CPU 12 operates in accordance with the program stored in the memory 13 while performing arithmetic processing based on various data and information, and drives the bar-shaped working tool 15 of the connected cutting section 14 to be processed. The workpiece 16 is cut.

The memory 13 has a storage section for storing various data such as a contour shape data storage section for storing data of the contour shape of the cutting section. CPU1 based on shape data
2 is provided with a patch data storage unit 17 for storing patch data calculated by performing an offset process.

The method of removing an abnormal tool path in the cutting process according to the present invention using such a cutting apparatus first calculates an offset-shaped tool path composed of patch data based on the contour shape data, and calculates this. After the patch data is stored in the patch data storage unit 17, the process is performed according to the flowchart shown in FIG.

In this case, a description will be given of a case where cutting is performed along two chevron-shaped tool paths partially overlapping as shown in FIG. This tool path is composed of a plurality of straight line segments k1, k2, k3, k4,... Kn, and a spark 18 is formed in a line segment between the line segments k2 and k3. A pinhole 19 is formed between the line segment k3 and the line segment k4, and a gap 20 is formed between the line segment k5 and the line segment k6.
Are each made.

Then, processing is sequentially performed from the line segment k1 of the illustrated tool path according to the flowchart. First, in step 1 of FIG. 2, it is asked whether all the inspection sections are completed.
Since the inspection section including the line segment k1 is the first section, the determination is NO, and the process proceeds to step 2.

In step 2, the width D of the inspection section is Dmin1
Determine if it is greater than. In this case, Dmin1
Is a threshold value that is less than the value and is regarded as a spark and ignores the inspection section, and is set to, for example, 0.02 mm.

Since the length of the line segment k1 is short and its inclination is steep, the width D of the inspection section between the end points P and P 'of the line segment k1 is assumed to be smaller than 0.02 mm. Therefore, in step 2, the answer is YES, the process proceeds to step 3, and the inspection section corresponding to the line segment k 2 is returned to step 1.

Here, the width D of the inspection section of the line segment k2 is
If it is larger than 0.02 mm, the result of step 2 is NO, and the process proceeds to step 4. In step 4, it is determined whether the inspection section is empty without a line segment. However, since the inspection section of line segment k 2 is not empty, the determination is NO, and the process proceeds to step 5.

In step 5, the line segment passing through the uppermost line is selected. In the inspection section including the line segment k2,
Since there is only one line segment, the line segment k2 is selected as it is. Then, in step 6, the end point of the immediately preceding tool path, that is, the end point P 'of the line segment k1 is set to P0, and the start point of the current line segment, that is, the start point of the line segment k2 is set to P1.

Since the line segments k1 and k2 are continuous line segments, the points P0 and P1 are located at the same position. Therefore, in step 7, the result is YES, and the process proceeds to step 8,
The line segment k2 which is the current line segment is set as the tool path. In this case, the line segment k1 is ignored, but the line segment k1 is short,
Since the line segment is almost vertical, ignoring it has almost no effect on the cutting accuracy.

Then, the process proceeds to step 3 again, the inspection section including the next line segment k7 is reached, and the process proceeds to step 1. This line segment k7 is on a straight line with the next line segment k8, and a gap is formed therebetween, and a spark 18 is formed above the gap. In this case, the width of the inspection section including the spark 18 is set to 0.02 mm or less, and the width D of the inspection section including the line segment k7 and the line segment k8 is set to 0.02 mm or more.

The width D of the inspection section including the line segment k7 is
Since it is 0.02 mm or more, similar to the case of the line segment k2,
The line segment k7 also proceeds from step 1 to step 8, is included in the tool path in step 8, and proceeds to step 3. Next, the inspection section includes the spark 18 and the process proceeds from step 1 to step 2.

The width D of the inspection section including the spark 18
Is less than or equal to 0.02 mm, so the answer to step 2 is YES and the process proceeds to step 3, where the line segment k which is the next inspection section
Step 1 and Step 2
Proceed to. Since the width D of the inspection section is equal to or greater than 0.02 mm, the answer in Step 2 is NO, and the process proceeds to Step 4.

Since the inspection section including the line segment k8 is not empty, the process proceeds to step 5, and further proceeds to step 6. Here, since the inspection section including the previous spark 18 has been ignored, the tool path immediately before becomes the line segment k7, and the end point of the line segment k7 is P0 and the start point of the line segment k8 is P1. Becomes

Since the points P0 and P1 are different points, the result of step 7 is NO, and the process proceeds to step 9. And
In step 9, a line segment connecting point P0 of line segment k7 and point P1 of line segment k8 is added as a tool path. Then, in step 8, line segment k8 is also included in the tool path. As a result, the line segment k7 and the line segment k8 become one continuous line segment,
Spark 18 is removed from the data.

Similarly, the process proceeds to the inspection section including the line segment k3 and the inspection section including the line segment k9 and the line segment k10. Here, the inspection section including the line segment k9 and the inspection section including the line segment k10 both have a width D of 0.02 mm or more and include the pinhole 19 between the line segment k9 and the line segment k10. Width D
Is not less than 0.02 mm and not more than Dmin2. Dmin2
Is a threshold value below which the pinhole is regarded as a pinhole and the inspection section is ignored. In this case, it is set to 0.2 mm.

Then, it is assumed that the same processing as described above is sequentially performed, a line segment k9 is added to the tool path, and the process proceeds to the inspection section including the pinhole 19 in step 3. The process proceeds from step 3 to step 1 and step 2. In step 2, the width D of the inspection section including the pinhole 19 is 0.0
Since it is 2 mm or more, the result is NO, and the process proceeds to step 4.

Next, since this inspection section is empty, Y
It becomes ES and proceeds to step 10. Since the width D of the inspection section including the pinhole 19 is equal to or less than Dmin2 (0.2 mm), the determination is YES here, and the process returns to step 3 again.

Next, the inspection section including the pinhole 19 is not processed and is ignored and proceeds to the inspection section including the next line segment k10. Then, the process proceeds to step 1, step 2, step 4, step 5, step 6, and in step 6, the end point of the line segment k9 is P0 and the start point of the line segment k10 is P0.
It becomes 1.

Here, since the points P0 and P1 are different points, the answer is NO in Step 7, and the process proceeds to Step 9, where a line segment connecting the points P0 and P1 is added as a tool path. In step 8, the line segment k10 is also included in the tool path. As a result, the line segment k9 and the line segment k10
Also becomes one continuous line segment.

In this way, the processing is sequentially performed, and the line segments k11 and k12 which have other line segments above them are removed, and only the line segment passing through the uppermost line is used as the tool path. The process proceeds while selecting as.

Then, after the line segment k5 is added to the tool path, the process proceeds to the processing stage of the inspection section including the gap 20. When the width D of the inspection section including the gap 20 is Dmin2 or more,
After step 1, NO is determined in step 2 and the process proceeds to step 4. YES is determined in step 4 and the process proceeds to step 10. Further, since the width of the gap 20 is larger than Dmin2, the result of step 10 is NO, and the process proceeds to step 11.

In step 11, the tool path is a line segment passing through a preset maximum cutting depth L. That is, the gap 20 is determined to be a part that is not particularly related to the machining shape. Here, a tool path that is cut to the maximum cutting depth L that does not affect the machining shape is selected. In this case, the points L0 and L1 at the maximum cutting depth L
A line segment k13 is formed.

Next, in step 6, the end point of the line segment k5 becomes P0, and the start point of the line segment k13 (the same point as the point L0)
Becomes P1. Then, in step 7, the points P0 and P1
Is a different point, the determination is NO, and the process proceeds to step 9, where a line segment connecting the points P0 and P1 is added as a tool path.

Then, in step 8, the line segment k13 is also set as the tool path. Next, the process proceeds to step 3 again, and the target inspection section becomes an inspection section including the line segment k6. Then, the process proceeds to Step 1, Step 2, Step 4, Step 5, and Step 6. In Step 6, the end point of the line segment k13 is P0, and the start point of the line segment k6 is P1.

Then, the process proceeds to a step S7, wherein the points P0 and P
Since 1 is a different point, the process proceeds to step 9 and a line segment connecting the points P0 and P1 is added as a tool path. Thereafter, similarly, the processing of each line segment is performed. When the processing of the last line segment kn is completed, YES is obtained in step 1 and the processing is terminated.

By the above-described processing, the tool path at the time of the actual cutting process has a mountain shape formed by each line segment and another mountain shape having a valley at the center part connected thereto as shown in FIG. Are obtained as one continuous path.

Note that the last line segment kn is also a short and steeply inclined line segment close to the vertical direction, like the first line segment k1.
It is ignored as in FIG. However, this line segment k1
If the width D of the inspection section including the line segment kn and the line segment kn is greater than Dmin1, the tool path remains as it is, and in this case, both ends of the tool path are as shown by broken lines in FIG.

As a result, by moving the processing tool 15 along the tool path as shown in FIG. 4, even if the original data has a spark or a pinhole, the processing tool 1 can be easily
5 can be moved and the processing tool 15 is not damaged. In addition, it does not occur that the processing tool 15 enters the non-cutting area and cuts a necessary portion.

In the above example, Dmin1 is set to 0.
The threshold value is set to 02 mm and Dmin2 is set to 0.2 mm, but these threshold values can be set to appropriate values as appropriate according to the use and the like.

In the above example, a gap (between the segments k7 and k8) is formed below the spark 18 in the original data before processing. Sparks may occur above or below the
Even in such a case, similarly to the above, a tool path ignoring spark can be obtained by the processing according to the flowchart.

[0047]

As described above, according to the method for removing an abnormal tool path in cutting according to the present invention, an inspection section is set between each of the end points and intersections in a plurality of linear segments constituting the tool path. If the width of the inspection section is smaller than a predetermined value and the state is empty with no line segment, or if the line segments included between the adjacent inspection sections are discontinuous, the inspection section is calculated. A line segment for connecting the line segments of the inspection sections on both sides of the inspection section is regarded as being caused by an error, and is added as a tool path.

Therefore, when a program is created, even if a spark or a pinhole is generated due to a numerical calculation error, a continuous tool path is formed ignoring the spark and a pinhole. Problems such as damage to the working tool and erroneous cutting in the non-cutting area can be avoided.

When the width of the empty inspection section is wider than a predetermined value, such an inspection section is usually located between the tool paths and especially at a portion which does not need to be processed. Therefore, it is regarded as a correct inspection section, and the tool path passes through a preset maximum cutting depth.

Also, a wide discontinuous inspection section can be regarded as a correct section. In this case, if there are a plurality of line segments, the uppermost line segment is selected as a tool path. By performing such processing, an abnormal tool path due to a pinhole or a spark can be distinguished from a correct tool path, and appropriate cutting can be performed.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a cutting device used in an example of the present invention.

FIG. 2 is a flowchart showing the order of processing.

FIG. 3 is an explanatory diagram showing a tool path based on original data.

FIG. 4 is an explanatory diagram showing a tool path after removing an abnormal tool path.

FIG. 5 is an explanatory diagram showing a tool path according to a conventional example.

FIG. 6 is an explanatory diagram showing a pinhole and a spark.

[Explanation of symbols]

11 Input device 12 CPU 13 Memory 14 Cutting unit 15 Processing tool 17 ········ Patch data storage unit 18 ··················· Spark 19 ········· Pinhole 20 ······· Gap k1, k2, k3, k4, k5, k6 , K7, k8, k9, k1
0, k11, k12, k13, kn... Line segment P0... The end point of the immediately preceding tool path P1. ······· Maximum cutting depth D ····· Inspection section width Dnin1 ····· Inspection section width threshold including spark Dmin2 ····· Pin Threshold for inspection section width including hole

Claims (1)

[Claims] 1. A method for performing a three-dimensional cutting process while performing an offset process using a cutting device having a rod-shaped processing tool, wherein the processing shape is shifted to the outside of the processing shape by the radius of the processing tool. The tool path along the offset shape is composed of a plurality of straight line segments, and the end points and intersections of these line segments are defined as inspection sections on the coordinates in the scanning direction, and the inspection sections are empty with no line segments. Or, if the line segments included in each of the adjacent inspection sections are discontinuous and the width of the inspection section is smaller than a predetermined value, the inspection section is considered to have been caused by an arithmetic error. A tool path for connecting the line segments between the inspection sections on both sides of the inspection section is added, and the line segments included in the empty inspection section or the adjacent inspection sections are discontinuous. If the width is wider than the predetermined value,
A method for removing an abnormal tool path in a cutting process, wherein the inspection section is regarded as correct, and a tool path passing through a preset maximum cutting depth or an uppermost tool path is selected as a tool path in the inspection section. .