JPH117311A - Method for removing micro-loop in tool path - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for removing a micro-loop in a tool path for easily checking whether or not each loop constituting the tool path is an interference loop. SOLUTION: A tool path along an offset shape is constituted by linking plural linear segments, and plural loops which are respectively constituted of those plural segments are formed. Then, when the total length of the segments constituting the loop among the plural loops is less than a prescribed value, the loop is removed from the tool path before a processing for removing an interference loop among those plural loops from the tool path is operated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of obtaining a workpiece having a predetermined shape by moving a rod-shaped processing tool and performing cutting, and particularly to a method of processing a minute loop in a tool path. Have

[0002]

2. Description of the Related Art Conventionally, when a workpiece having a predetermined shape is formed by cutting, a cutting device that drives a processing tool such as an end mill under computer control to perform a cutting process is used to cut a processing material. That is being done.

In such a case, cutting processing is performed by creating a program of a tool path based on the center axis of the processing tool, and moving the processing tool while rotating according to the program. However, since the above processing tool has a thickness, if the center of the processing tool is moved along the contour of the processing shape, the processing tool bites into the inside of the processing shape, and a predetermined shape is obtained. Can not be.

[0004] In view of the thickness of the processing tool, the above-mentioned program is created using the offset shape shifted outward by the radius of the processing tool from the contour of the processing tool as a tool path, and cutting according to the program is performed. Have been done.

[0005]

However, in the tool path based on the above-described offset shape, an interference loop occurs when the contour of the processed shape has a concave corner or the like. This interference loop consists of a closed path, and if the processing tool is moved along the loop as it is, it cuts to the non-cutting area of the processed shape.

Therefore, it is necessary to remove such interference loop data from the above-mentioned program at the time of actual cutting. For this reason, it is performed to check whether each loop constituting the tool path is an interference loop or not.

[0007] Various methods are conceivable as this check method, but all of these methods require time and effort. In particular, when the processing shape becomes complicated, the number of loops increases, and a great deal of labor is required for the processing.

In addition, there are many such small loops, and there are some such loops which are not interference loops but have little effect on the processed shape even if they are removed. In the related art, since it is checked whether or not such a minute loop is an interference loop, complicated processing as described above has been performed.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and provides a method of removing a minute loop in a tool path which can easily check whether each loop constituting the tool path is an interference loop. Its purpose is to provide.

[0010]

According to the present invention, first, based on past experience, most of the micro loops in the tool path are interference loops. We noticed that there were many small loops that had little effect on the processed shape even if removed.

[0011] Such interference loops, which are highly probable and have little effect on the machined shape, are previously removed from the data, and then only the remaining loops having a predetermined size or more are checked. If you do it,
The present inventors have found that the labor required for checking the interference loop can be greatly reduced, and arrived at the present invention.

That is, in order to achieve the above object, according to the present invention, first, a tool path along an offset shape is formed by connecting a plurality of straight line segments, and a loop formed by the plurality of line segments is formed. Are formed.

Then, of the plurality of loops, a process of removing a loop (interference loop) including a line segment whose shortest distance between the contour of the processing shape is shorter than the radius of the rod-shaped processing tool is performed from the tool path. Previously, if the total length of the line segments constituting the loop among the plurality of loops is equal to or less than a predetermined value, the loop is also removed from the tool path.

That is, for the sake of convenience, the total length of the line segments constituting the loop is considered to have no effect on the processed shape even if the loop is removed, for example, 0.2 mm. If the total length of the line segments that make up is less than this, the loop is removed from the data.

Then, the total length of the remaining line segments is 0.2
The same check as before is performed only for loops of mm or more. This reduces the number of loops to check,
The task of checking for interference loops is greatly simplified.

The calculation of the total length of the line segments constituting the loop is simpler than the work of checking the interference loop, so that even if this processing is increased, the required labor does not change much. Next, a method for removing minute loops in a tool path according to the present invention will be described in detail with reference to the drawings.

[0017]

FIG. 1 shows an example of a cutting apparatus for performing a method for removing a minute loop in a tool path according to the present invention. That is, in FIG. 1, reference numeral 1 denotes an input device, which inputs data such as data required for cutting, such as data of a processing shape and a tool speed, and converts the data into
The data is sent to the memory 3 via the connected CPU 2 and stored.

The CPU 2 operates in accordance with a program stored in the memory 3 while performing arithmetic processing based on various data and information, and drives the bar-shaped processing tool 5 of the connected cutting section 4 to perform processing. The workpiece 6 is cut.

The memory 3 has a storage unit for storing various data.
In particular, the contour shape data storage unit 7 for storing data of the contour shape of the cutting part and the CP based on the contour shape data
An offset shape data storage unit 8 for storing an offset shape calculated by performing an offset process by U2 is provided.

Using such a cutting device, the method for removing minute loops in a tool path according to the present invention is as follows.
The tool path of the offset shape is calculated based on the contour shape data, and the calculated tool path is stored in the offset shape data storage unit 8, and then the processing is performed according to the flowchart shown in FIG.

In this case, as shown in FIG. 3, the outline of the outer portion 9 is substantially a gourd shape in which the center portion is narrow, and there are square holes 10 and 11 in the center portion of each large diameter portion. A method for obtaining such a contour by cutting will be described.

The tool path corresponding to this contour shape has 13 loops i1, i2, i3, i4, i5, i6, i7, i8, 13 loops each composed of a plurality of short straight line segments.
i9, i10, i11, i12, i13, and a rounded tool path R along the outer shape of the rod-shaped processing tool 5 is interpolated at each of the convex corners of the loop i1.

Then, processing is sequentially performed in accordance with the flowchart from the illustrated tool path loop i1. First, FIG.
In step 1, the loop number i is set to 1 and the loop i1 is processed. Hereafter, when the loop number i of the tool path is 1, the loop i1 is inserted, when the loop number i is 2, the loop i2 is inserted, and when the loop number i is 3, the loop i3. Each shall be added.

Next, in step 2, it is determined whether or not the loop number i is larger than the number n of loops. In this case, since the loop number i is 1 and the number n of loops is 13, the result is NO, and the process proceeds to step 3.

In step 3, the loop segment number j is set to 1 and the total length l of the loop segment is set to 0. Then, in step 4, it is determined whether or not the loop segment number j is larger than the loop segment number m.
Here, assuming that the number m of the line segments constituting the loop i1 is 50, j (= 1) <m (= 50).
It becomes O and it progresses to step 5.

At step 5, the length of the first line segment (j1) in the loop i1 is added as the length of the line segment of the loop i1, and the routine proceeds to step 6, where the number j of the line segment of the loop i1 is calculated. In step 2, the process returns to step 4.

Then, again, step 4, step 5,
The same operation as in step 6 and step 4 is performed for 50 line segments.
Repeat the same 50 times. That is, here, the loop i
In step 1, the length of each line segment j is sequentially added from line segment j1 to line segment j50 to obtain the length l of the entire line segment i1.

Next, the above operation is repeated 50 times,
When the length of the entire line segment of the loop i1 is obtained, the result is YES in step 4, and the process proceeds to step 7. In step 7, it is determined whether or not the obtained length l of the entire line segment of the loop i1 is smaller than the threshold value L.

In this case, the threshold value L is a threshold value which can be regarded as an interference loop or a loop having no influence on the machined shape if the value is equal to or less than the threshold value. Set in advance.

Since the loop i1 is a long loop, it is naturally larger than the threshold value L. In step 7, the result is NO, and the process proceeds to step 8. Then, in step 8, the loop number i becomes 2, and the processing target becomes the loop i2. That is, the data of the loop i1 is left as it is in the program.

Next, from loop i2 to loop i13,
The same operation as described above is repeated, but of these loops, the total length l of the line segment of loop i3 and loop i9
Is 0.2 mm or less, and the total length of the other loop line segments is 0.2 mm or more.

As a result, in the processing of the loop i3 and the loop i9, YES is determined in the step S7, and the process proceeds to the step S9.
Then, in step 9, the data of loop i3 and loop i9 are removed from the program. Then, finally, when the loop number i becomes 14, the answer to step 2 is YES, and the processing for removing the minute loop is completed.

Next, it is checked whether or not each of the remaining loops is an interference loop. As can be seen from FIG. 3, of the remaining loops, nine loops i2, i5, i6, i7, excluding loops i1 and i4.
i8, i10, i11, i12, and i13 are all in contact with the contour of the processed shape.

Therefore, these loops are all interference loops, and when the interference loop is checked, its data is removed from the program. Then, cutting is performed on the remaining loops i1 and i4, and FIG.
A processed shape as shown in FIG.

In FIG. 4, 12 of the portions indicated by the dashed line is the portion which has not been cut since the data of the loop i9 has been removed, and is 13, 14a, 14b, 14
c and 14d are portions that should be originally cut, but portions that could not be cut due to the relationship between the shape and the diameter of the processing tool 5.

These parts may, if necessary,
A more accurate processing shape can be obtained by cutting with a processing tool having a small diameter. In the portion corresponding to the loop i3 in FIG. 3, the uncut portion is too small so that it is almost impossible to determine the set shape.

In the above example, the threshold value L is set to 0.2 mm. However, these threshold values may be set to appropriate values depending on the size of the processed shape, the use of the workpiece, and the like. Can be set.

In the above example, the processing shape is
For the sake of convenience, the operation is simplified as shown in FIG. 3. However, when the tool path has a complicated shape such that a large number of minute loops such as the loop i3 in FIG. Extremely simple.

[0039]

As described above, in the method for removing a minute loop in a tool path according to the present invention, the total length of the line segments constituting the loop is reduced before the processing for removing the interference loop from the tool path is performed. If it is less than the predetermined value, the loop is removed from the tool path.

For this reason, a loop which has a high probability of being an interference loop and has almost no effect on the machined shape even if removed is removed from the data in advance, and only the remaining loops need to be checked for interference loops. become. As a result, the number of loops to be checked is reduced, and the checking operation is greatly simplified. Therefore, the practical effect is large.

[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 a plan view showing a processing shape.

[Explanation of symbols]

1 Input device 2 CPU 3 Memory 4 Cutting unit 5 Processing tool 7 ······ Contour shape data storage unit 8 ····· Offset shape data storage unit 9 ····· Outer part 10, 11 ··· Hole i1, i2, i3, i4 , I5, i6, i7, i8, i9, i1
0, i11, i12, i13 ... loop n ... number of loops j ... ... line segment number m ... The number of line segments l ····················· Threshold value

Claims (1)

[Claims] 1. A tool path along an offset shape in which the contour of a processing shape is shifted to the outside of the processing shape by the radius of a rod-shaped processing tool is constituted by a plurality of straight line segments, and is constituted by the plurality of line segments. Among the loops included in the tool path, the shortest distance between the contour is a machining method that performs cutting by removing an interference loop including a line segment shorter than the radius of the rod-shaped processing tool from the tool path, Prior to the removal of the interference loop, if the total length of the line segments constituting the loop is less than or equal to a predetermined value, the loop is removed from the tool path. Method for removing minute loops.