JP3808977B2 - Method for removing minute loops in the tool path - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for obtaining a workpiece having a predetermined shape by moving a rod-shaped processing tool to perform cutting, and particularly has a feature in processing a micro loop in a tool path.
[0002]
[Prior art]
Conventionally, when a workpiece having a predetermined shape is created by cutting, a processing material such as an end mill is driven by a computer control to cut the processing material using a cutting device. Yes.
[0003]
In such a case, a cutting process is performed by creating a tool path program based on the central axis of the processing tool and moving the processing tool while rotating the tool along the program. However, since the 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 processing shape, and a predetermined shape is obtained. It becomes impossible.
[0004]
Therefore, in consideration of the thickness of the processing tool, the above program is created with the offset shape shifted outward from the contour of the processing shape by the radius of the processing tool, and cutting according to the program is performed. .
[0005]
[Problems to be solved by the invention]
However, in the tool path based on the offset shape described above, an interference loop occurs when the contour of the machining 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 region of the processed shape.
[0006]
Therefore, in actual cutting, it is necessary to remove such interference loop data from the program. 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 a method for this check, but each method requires time and effort. In particular, when the machining shape becomes complicated, the number of loops increases, and a great deal of labor is required for the processing.
[0008]
In addition, there are a lot of such loops, and some of them are not interference loops, but there are some that have almost no influence on the machining shape even if they are removed. Conventionally, since such a minute loop is checked to see if it is an interference loop, it has been a complicated process as described above.
[0009]
The present invention has been made in view of such circumstances, and provides a method for removing a minute loop in a tool path that can simplify checking whether each loop constituting the tool path is an interference loop. Objective.
[0010]
[Means for Solving the Problems]
The inventor of the present invention firstly, based on past experience, that most of the micro loops in the tool path are interference loops, and some of the loops affect the machining shape even if they are removed from the data. We paid attention to the fact that there are a lot of small loops without.
[0011]
Then, such a high probability of being an interference loop and a minute loop that hardly affects the machining shape is previously removed from the data, and then only the remaining loops of a predetermined size or more are checked. Thus, the present inventors have found that the labor required for checking the interference loop can be greatly reduced.
[0012]
That is, in order to achieve the above object, in the present invention, first, a tool path along the offset shape is configured by connecting a plurality of straight line segments, and a plurality of loops configured by the plurality of line segments are formed. Try to form.
[0013]
And before performing the process of removing the loop (interference loop) including the line segment whose shortest distance between the contours of the machining shape is shorter than the radius of the rod-shaped processing tool among the plurality of loops from the tool path, When the total length of 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.
[0014]
That is, the total length of the line segments constituting the loop is a value that does not affect the machining shape even if the loop is removed, for example, 0.2 mm is used as the threshold value for convenience, and the loop is formed. If the total length of the line segment is less than this, the loop is removed from the data.
[0015]
Then, only the remaining loops having a total line segment length of 0.2 mm or more are checked as before. This reduces the number of loops to check and greatly simplifies the interference loop checking operation.
[0016]
Note that the calculation of the total length of the line segments constituting the loop is simpler than the interference loop check operation, and therefore the required effort does not change much even if this processing increases.
Next, the micro loop removal method in the tool path according to the present invention will be described in detail with reference to the drawings.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows an example of a cutting apparatus for performing a minute loop removing method in a tool path according to the present invention. That is, in FIG. 1, reference numeral 1 denotes an input device, which receives data such as machining shape data and tool speed necessary information for cutting, and sends the data to the memory 3 via the connected CPU 2. Remember.
[0018]
The CPU 2 operates in accordance with a program stored in the memory 3 while performing arithmetic processing based on various types of data and information, and drives the bar-shaped processing tool 5 of the connected cutting processing unit 4 to process the workpiece 6. Is to be cut.
[0019]
The memory 3 includes a storage unit for storing various data. In the memory 3, in particular, the contour shape data storage unit 7 for storing contour shape data of the cutting portion and the contour shape data thereof. An offset shape data storage unit 8 for storing an offset shape calculated by the CPU 2 performing an offset process based on the above is provided.
[0020]
Using such a cutting apparatus, the micro-loop removing method in the tool path according to the present invention first calculates an offset shape tool path based on the contour shape data, and stores it in the offset shape data storage unit 8. Thereafter, the process is performed according to the flowchart shown in FIG.
[0021]
In this case, as shown in FIG. 3, the contour of the outer shape portion 9 is a substantially bowl shape with a thin central portion, and has a rectangular hole portion 10, 11 in the central portion of each large diameter portion. A method for obtaining the shape by cutting will be described.
[0022]
The tool path corresponding to this contour shape is 13 loops i1, i2, i3, i4, i5, i6, i7, i8, i9, i10, i11, i12 each composed of a plurality of short straight line segments. , I13, and a rounded tool path R along the outer shape of the rod-like processing tool 5 is interpolated at the convex corner of the loop i1.
[0023]
Then, the processing is sequentially performed from the loop i1 of the tool path shown in the drawing along the flowchart. First, in step 1 of FIG. 2, the loop number i is set to 1, and the loop i1 is set as a processing target. 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 set, when the loop number i is 3, the loop i3 is set. Each shall be attached.
[0024]
Next, in step 2, it is determined whether 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 determination is NO and the process proceeds to Step 3.
[0025]
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 line number j is larger than the number m of the loop line segments. Here, if the number m of line segments constituting the loop i1 is 50, j (= 1) <m (= 50), so NO is determined and the process proceeds to step 5.
[0026]
In step 5, the length of the first line segment (j1) in the loop i1 is added as the length of the line segment in the loop i1, and the process proceeds to step 6 where the line number j of the loop i1 becomes 2. Return to step 4 again.
[0027]
Then, the same operation as in Step 4, Step 5, Step 6, and Step 4 is repeated 50 times, the same as the number of line segments 50.
That is, here, the length of each line segment j in the loop i1 is added in order from the line segment j1 to the line segment j50, and the process of obtaining the length l of the line segment of the entire loop i1 is performed.
[0028]
Next, when the above operation is repeated 50 times and the length of the line segment of the entire loop i1 is obtained, the result is 51 in step 4, YES in step 4, and the process proceeds to step 7. In step 7, it is determined whether or not the length l of the obtained line segment of the entire loop i1 is smaller than the threshold value L.
[0029]
In this case, the threshold value L is a threshold value that can be regarded as an interference loop or a loop that does not affect the machining shape if it is equal to or less than that value, and can be removed from the data. Keep it.
[0030]
Since the loop i1 is a long loop, it is naturally larger than the threshold value L. In step 7, NO is determined and the process proceeds to step 8. 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 in the program as it is.
[0031]
Then, the same operation as above is repeated from the loop i2 to the loop i13. Among these loops, the total length l of the line segments of the loop i3 and the loop i9 is 0.2 mm or less. The total length of the line segments is set to 0.2 mm or more.
[0032]
As a result, at the time of processing of loop i3 and loop i9, step 7 becomes YES and the process proceeds to step 9. 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, YES is obtained in step 2 and the process of removing this minute loop is completed.
[0033]
Next, the remaining loops are checked for interference loops. As can be seen from FIG. 3, among the remaining loops, the nine loops i2, i5, i6, i7, i8, i10, i11, i12, i13, excluding the loop i1 and the loop i4, It comes to touch.
[0034]
Therefore, these loops are all interference loops, and the data is removed from the program when the interference loops are checked. Then, the remaining loops i1 and i4 are cut to obtain a processed shape as shown in FIG.
[0035]
In FIG. 4, 12 of the portions indicated by the alternate long and short dash line are portions that remain without being cut since the data of the loop i9 is removed, and 13, 14a, 14b, 14c, and 14d should be originally cut. Although it is a part, it is a part which could not be cut because of the relationship between the shape and diameter of the processing tool 5.
[0036]
These portions can be made into a more accurate processed shape by cutting with a small diameter processing tool as required. The portion corresponding to the loop i3 in FIG. 3 is too small to be discriminated from the set shape because the uncut portion is too small.
[0037]
In the above example, the threshold value L is set to 0.2 mm, but these threshold values should be appropriately set according to the size of the processed shape, the use of the workpiece, and the like. Can do.
[0038]
Further, in the above example, the processing shape is made simple as shown in FIG. 3 for convenience of explanation, but it has a complicated shape such that many micro loops such as the loop i3 in FIG. 3 are generated. In the case of a tool path, the above operation is very simple.
[0039]
【The invention's effect】
As described above, in the method for removing a micro loop in the tool path according to the present invention, the total length of the line segments constituting the loop is equal to or less than a predetermined value before performing the process for removing the interference loop from the tool path. In some cases, the loop is removed from the tool path.
[0040]
For this reason, a loop having a high probability of being an interference loop and having almost no influence on the machining shape even if removed is previously removed from the data, and the interference loop only needs to be checked for the remaining loop. As a result, the number of loops to be checked is reduced, and the check operation is greatly simplified. Therefore, the practical effect is great.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a cutting apparatus used in an example of the present invention.
FIG. 2 is a flowchart showing a processing order.
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 section 5 ... Processing tool 7 ... Contour shape data storage section 8 ... · Offset shape data storage unit 9 ··································· holes i1, i2, i3, i4, i5, i6, i7, i8, i9, i10, i11, i12, i13・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Loop n ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Number of loops j ・ ・ ・ ・ ・ ・ Line number m ・ ・ ・ ・ ・ ・ Line number l ・ ・ ・.... The total length L of the line segments constituting the loop ...

Claims (1)

A tool path along an offset shape in which the contour of the machining shape is shifted to the outside of the machining shape by the radius of the rod-shaped tool is constituted by a plurality of straight line segments and included in the tool path constituted by the plurality of line segments. The removal of the interference loop in a machining method in which an interference loop including a line segment whose shortest distance from the contour is shorter than the radius of the rod-shaped processing tool is removed from the tool path for cutting. Prior to, when 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. .

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