JP3380429B2 - Offset processing method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to a method for obtaining a predetermined model by cutting a workpiece by moving a bar-shaped tool. In particular, the present invention has a feature in the processing of the interference loop in the offset shape. 2. Description of the Related Art Conventionally, when a shaped object is created by cutting, a shaping material is cut using a cutting device that drives a bar-shaped tool such as a drill under computer control to perform cutting. That is being done. In such a case, for example, as shown in FIG. 9, when the contour shape 1 of the cutting portion is a gourd shape in a top view and the inside is cut and removed in a plane, the rod-shaped processing tool 2 is used.
The program of the tool path 3 in which the center of the rod-shaped processing tool 2 is offset by the radius of the rod-shaped processing tool 2 in consideration of the thickness of the rod-shaped processing tool 2 is created. Further, a program for tool paths 4,... N for cutting and removing the inner side of the contour shape 1 is created, and a bar-shaped machining tool 2 is formed along these tool paths 3, 4,. The cutting process is performed by moving. However, in this case, as the tool path goes downward in the figure, the bar-shaped processing tool 2 approaches the protruding portion (a gourd-shaped constricted portion) 5 on the opposite side of the contour shape 1, and
There is a problem that the bar-shaped processing tool 2 cuts the non-cutting area. For this reason, it is determined whether or not there are points a and b intersecting with each of the tool paths 3, 4,.
If there is a further intersection, it is determined whether or not the bar-shaped tool 2 and the non-cutting area interfere with each other. When the bar-shaped tool 2 and the non-cutting area interfere with each other, the tool path 6 is made straight between the intersections a and b to prevent the bar-shaped tool 2 from breaking the non-cutting area. Have been done. However, in the above-described method, it is necessary to determine whether or not there are intersections a and b for all of the tool paths 3, 4,... N. Further, after determining whether or not the bar-shaped tool 2 and the non-cutting area interfere with each other, the shortest distance at which the bar-shaped tool 2 and the non-cutting area interfere with each other and a straight path where the bar-shaped tool 2 and the non-cutting area do not interfere are calculated. For example, there is a problem that many complicated arithmetic processing must be performed. If the contour shape is not as simple as the contour shape 1 in FIG. 9, but has a plurality of cut portions separated from each other or is complex, the processing required for this becomes more and more complicated. It also has a problem that it takes a lot of trouble. The present invention has been made in view of such circumstances, and among the tool paths in a plurality of cutting sections, a tool path which can be determined in advance that no interference occurs will be described.
By omitting detailed determination of whether or not interference occurs, it is possible to greatly simplify the arithmetic processing, and to provide an offset processing method capable of reliably preventing cutting of a non-cut area. Aim. [0010] In order to achieve the above object, in the offset processing method according to the present invention, first, the data of the contour shape and the data of the offset shape are each converted into a loop of a plurality of sides. Create as aggregate data. That is, a loop (closed area) is formed by joining a plurality of small straight sides, and a plurality of such loops are assembled to form a contour shape or an offset shape. Next, on the coordinates, a rectangle circumscribing each loop constituting the contour shape and a rectangle circumscribing each loop constituting the offset shape are compared,
It is determined whether the two opposite rectangles intersect each other or whether the distance between the rectangles is within the radius of the rod-shaped processing tool. [0012] This is because when the above-mentioned squares intersect with each other, the contour-shaped loop and the offset-shaped loop may naturally cause interference. Even if the above-mentioned rectangles do not intersect with each other, if the shortest distance between them is within the radius of the rod-shaped processing tool, no offset is taken into account in the contour loop, so interference may occur during actual processing. There is. For this reason, in order to eliminate the possibility of interference, it is necessary that there is a distance between the two squares that is equal to or greater than the radius of the rod-shaped processing tool. [0013] Next, among the above quadrangles, those which do not intersect each other and those which do not cause interference in the loops inside thereof, except for those which may cause interference with respect to the corresponding loops, have the outlines thereof. Any of the sides forming the loop of the shape and the sides forming the loop of the offset shape intersect, or the starting point of each side of the loop of the offset shape and each side of the loop of the contour shape It is determined whether or not there is any one whose shortest distance is shorter than the radius of the rod-shaped processing tool. [0014] If any of the sides forming the contour-shaped loop and the sides forming the offset-shaped loop intersect each other, the loops interfere with each other, and thus the offset-shaped loop including the side is interposed. Is removed so that the portion is not cut. Further, even if each side forming the contour-shaped loop and each side forming the offset-shaped loop do not intersect with each other, the starting point of the side of one of the loops,
If the shortest distance to the other loop side is shorter than the radius of the rod-shaped tool, interference occurs. Therefore, also in this case, the cutting process is performed by removing the data of the offset-shaped loop including the side. In this way, by removing all the data of the offset-shaped loop in which the interference occurs, and performing the cutting process only on the offset-shaped loop in which the interference is not likely to occur, the cutting that does not cause the cutting to the non-cutting area is performed. Processing becomes possible. In this case, interference may occur due to rough intersections of circumscribed rectangles without performing complicated processing such as finding an intersection of each side of each loop from the beginning and making a determination through arithmetic processing or the like. Since a detailed judgment is made only for a certain item, the processing is greatly simplified. Next, the offset processing method according to the present invention will be described in detail with reference to the drawings. FIG. 1 shows an example of a cutting apparatus for performing an offset processing method according to the present invention. That is, in FIG. 1, an input device 11 receives data such as shape data of a cutting portion and information necessary for cutting, such as a tool speed, and sends the data to a memory 13 via a connected CPU 12. Remember. 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 tool 15 of the connected cutting section 14 to be operated. The workpiece 16 is cut. The memory 13 is provided with a storage unit for storing various data. The memory 13 includes, in particular, a contour shape data storage unit 17 for storing data of the contour shape of the cutting part and a contour shape data storage unit 17. C based on shape data
An offset shape data storage unit 18 that stores offset shape data calculated by the PU 12 performing an offset process is provided. Using such a cutting device, the offset processing method according to the present invention is performed according to the flowchart shown in FIG. Here, a description will be given of a cutting process that makes the character “ha” stand out by cutting and removing the outer side of the character “ha” in a plane using the shape data of the character “ha” as shown in FIG. . In this case, first, the contour shape data of the character "ha" is stored in the contour shape data storage unit 17 of the memory 13. Here, the contour shape data is composed of three closed loops j1, j2, and j3. Each of the loops j1, j2, and j3 has a short straight side l as shown in FIG. It is configured by connecting a plurality of them. In the case of the above character "ha", 100 to 200
It is composed of about one side l. Next, based on the contour shape data, C
By performing an offset process in the PU 12, offset shape data in which the tool path is moved to the outside of the outline of the character “ha” by the radius of the bar-shaped processing tool 15 is created, and this is stored in the offset shape data storage unit 18. Let it. In this case, similarly to the contour shape data, the offset shape data is obtained as a set of closed loops, and as shown in the figure, the loops i1, i2, i3, i
4, i5, i6, i7, i8, i9, i10, i11. Like the loops j1, j2, and j3, these loops are also formed by joining short sides. this house,
Loop i4, i5, i6, i7, i8, i9, i10,
As will be described later, i11 is a portion that causes interference with the contour shape. If cutting is performed based on this data as it is, a non-cutting area is broken. In this state, the flowchart shown in FIG. 2 is started. First, in step 1 shown in the drawing, the loop number i of the first one of the loops constituting the offset shape is set to 1. Next, in step 2, it is determined whether or not the number of loops nL of the offset shape is smaller than 1 of the loop number. The number of loops in the offset shape is 11
Here, since it is larger than 1, the result is NO here, and the process proceeds to step 3. In step 3, the loop number j of the first loop among the loops constituting the contour shape is set to 1. In step 4, it is determined whether or not the number of loops nB of the contour shape is smaller than 1 which is the loop number. The number of loops in the contour shape is 3
Here, since it is larger than 1, the result is also NO here, and the process proceeds to step 5. Hereafter, when the loop number of the offset shape is 1, the loop i1 is inserted. When the loop number is 2, the loop i2,... Insert loop j1 and in case of 2, loop j
2,... In step 5, it is determined whether there is a possibility that the contour loop j1 and the offset loop i1 may intersect. As shown in FIG. 5, a rectangle 19 circumscribing the loop j1 and a rectangle 20 circumscribing the loop i1 are obtained on the XY coordinates, and the loop j1 and the loop j1 are determined by the positional relationship between the two rectangles 19 and 20. It is determined whether there is a possibility that the loop i1 may intersect. In this case, the square 1 circumscribing the loop j1
9 completely enters the rectangle 20 circumscribing the loop i1, and therefore the loop j1 and the loop i1 may intersect. In step 6, the number k of the first one of the sides constituting the offset-shaped loop i1 is set to 1, and the process proceeds to step 7. Next, in step 7, it is determined whether or not the number mL of the sides k forming the loop i1 is smaller than the number 1 of the side k. Several milliliters of side k forming loop i1
Is 50, for example, the answer is NO and the routine proceeds to step 8. In step 8, the number 1 of the first one of the sides constituting the loop j1 of the contour shape is set to 1, and
Proceed to step 9. In step 9, it is determined whether or not the number mB of the sides l forming the loop j1 is smaller than one. Also in this case, as in the case of the loop i1, assuming that 50 sides l are formed, mB is 50, which is larger than 1, and therefore, the process proceeds to step 10. Next, in step 10, the side k (= 1) of the offset-shaped loop i1 and the contour-shaped loop j1
It is determined whether or not the side l (= 1) intersects. This means that if side k and side l intersect, loop i1 and loop j1
Is determined, the judgment is made on each side k
And the side l are represented as straight-line equations, and it is determined whether or not the side k and the side l apply to the condition where the two equations intersect. That is, the side k and the side l are respectively expressed as follows: When the side k and the side l intersect, the condition for intersecting the side k and the side l is: Should be satisfied. In this case, since the side k and the side 1 do not intersect, the result is NO, and the process proceeds to step 11. Then, in a step 11, it is determined whether or not the shortest distance between the starting point of the side k and the side 1 is shorter than the radius of the rod-shaped working tool 15. This is because even if the side k and the side l do not intersect, if the shortest distance is shorter than the radius of the rod-shaped processing tool 15, interference occurs between the loop i1 and the loop j1, so that the side k and the side l intersect. This is performed to determine a case where interference occurs between the loop i1 and the loop j1. Since the end point of the side k is the start point of the next side k connected to the side k, the start point of each side k is the end point of all the sides k. Therefore, if the distance between the starting point of the side k and the side l is obtained, the shortest distance between the side k and the side l can be sufficiently obtained. As shown in FIG. 6, the coordinates of the end points of the side 1 are defined as P0 (x0, y0) and P1 (x1, y1), and the coordinates of the starting point of the side k are defined as P2 (x2, y2). When the coordinates of the intersection of the side l and the perpendicular extending from P2 to the side l are P (x, y), the distance between P2 -P0, P
The determination is made based on whether the minimum value of the distance between 2 and P1 and the distance between P2 and P is shorter than the radius of the rod-shaped processing tool 15. This is performed in the following manner. The equation of the parametric line segment on the side l is: And the value of the parameter t representing P is: Is determined by By substituting t into equation (3), the coordinates of P can be obtained. Here, according to the value of t, if t ≦ 0, P2 −
The distance between P0 is determined, and if t ≧ 1, the distance between P2 and P1 is determined. If 0 <t <1, the distance between P2 and P is determined. Thereby, the shortest distance between the starting point of the side k and the side l can be calculated. Since the offset-shaped loop i1 is located at a position shifted outward from the contour-shaped loop j1 by the radius of the rod-shaped processing tool 15, the starting point of the side k and the side l
Is not shorter than the length of the radius of the rod-shaped processing tool 15. Therefore, in this case, the determination is NO, the process proceeds to step 12, and the side 1 becomes 2. Then, returning to step 9, the side l (= 2)
Is greater than mB (= 50), and the processing proceeds to steps 10, 11, and 12. In order to perform this for all of the 50 sides l constituting the contour loop j1, the same operation is repeated 50 times until l becomes 50.
At the 51st time, l> mB, and the process proceeds from step 9 to step 13. At this stage, the offset-shaped loop i
It can be seen that the first side k of 1 does not interfere with all the sides l constituting the contour shaped loop j1. Next, in step 13, the side k becomes 2.
Proceed to step 7. Here, the side k is mL (= 5
0), the process proceeds to step 8 and the side l is again 1
become. Then, in the same manner as described above, the steps 9, 10, 10, 11, 12, and the return to the step 9 are repeated 50 times, and at the 51st time, the process proceeds to the step 13, and the side k becomes 3. For the side k, the above operation is repeated 50 times. At the 51st time, the result of step 7 is YES, and the process proceeds to step 14. Thus, it can be seen that the offset-shaped loop i1 and the contour-shaped loop j1 do not interfere with each other on all sides. Then, in step 14, the loop number j of the contour shape becomes 2, and in step 4, it is determined whether or not this loop number 2 is larger than the number of loops 3 of the contour shape. Since the loop number is smaller than the number of loops, the determination is NO, and the process proceeds to step 5, where it is determined whether there is a possibility that the contour shaped loop j2 and the offset shaped loop i1 may intersect. In this case, as shown in FIG.
Rectangle 20 circumscribing the loop and rectangle 2 circumscribing the loop j2
1 is NO because it is completely separated, and the process proceeds to step 14. In this case, it is necessary that not only the rectangles 20 and 21 be separated from each other, but also that the distance be greater than the radius of the rod-shaped processing tool 15. In step 14, the loop number j of the contour shape becomes 3, but the square 22 circumscribing the loop j3
Since there is no possibility of crossing the rectangle 20 circumscribing the loop i1 or approaching a distance within the radius of the rod-shaped processing tool 15, the process proceeds to step 4, step 5, and step 14 again, and the loop number j becomes When it reaches 4, step 4
And the loop number j becomes larger than the loop number nB and Y
It becomes ES and proceeds to step 15. In step 15, the loop i of the offset shape becomes 2, and the process proceeds to step 2. That is, at this stage, since it is known that there is no possibility that the offset shape loop i1 will interfere with any loop of the contour shape, no further determination is made and the process proceeds to the loop i2. Then, according to the flowchart of FIG.
The same operation as described above is performed for the loop i2 and further for the loop i3. As a result, loop i
It can be seen that both the loops i2 and i3 have no possibility of interfering with each other at the stage of step 5 in the relationship with the loop j1. However, it can be seen that no interference occurs in steps 10 and 11. Therefore, both the loop i2 and the loop i3 do not interfere with any loop of the contour shape. Next, the process proceeds to step 15 again, where the processing is performed for the loop i4 whose loop number i is 4 in the offset shape, and the same processing is performed for each of the loops whose loop numbers are 5 to 11. As a result, as can be seen from FIG. 3, the loops i5, i6, i8, and i11 intersect with the loop j2, and the loops i4, i7, and i9 do not intersect with any loop of the contour shape. In the relationship with the loop j2, the rod-shaped tool 15 approaches a distance within the radius of the rod-shaped processing tool 15, causing interference. Further, the loop i10 approaches the distance within the radius of the rod-shaped processing tool 15 in relation to the loop j3, and interference occurs. Therefore, the loop i5, i6, i8, i
At the time of the processing of step 11, YES is determined in step 10 in relation to the loop j2, and the flow advances to step 16 to remove the data of these loops i5, i6, i8, and i11. The loops i4, i7 and i9 correspond to the loop j
In relation to 2, loop i10 becomes YES in step 11 in relation to loop j3, respectively,
Proceeding to step 16, these data are removed. Then, the loop number i of the offset shape becomes 12 in step 15, and if YES in step 2, all the processing ends. The result of the above processing is shown in Table 1 attached separately. [Table 1] This Table 1 shows the offset-shaped loops i1, i2, i
3, i4, i5, i6, i7, i8, i9, i10, i
11 are compared with loops j1, j2, j3 of the contour shape, respectively, Step 5, Step 10, Step 11
Here is a summary of the results. In Table 1, in the flowchart of FIG. 2, when there is a possibility that interference occurs, or when YES occurs, interference is marked as “○”, and when there is no possibility of interference or NO occurs, no interference occurs. Is marked with x. If there is no possibility of interference in step 5 and the result is x, steps 10 and 11 are left blank because no further processing is performed. In addition, when the result of step 5 and step 10 is ○, it is determined that interference occurs, and the process of step 11 is not performed, so that the portion of step 11 is blank. As a result of these processes, step 10 in Table 1
Alternatively, the loop i4, i5, i6, i7,
All data of the eight loops i8, i9, i10, and i11 are removed, and at the time of cutting, cutting is performed only on loops i1, i2, and i3 that do not cause interference. As a result, as shown in FIG. 8, loops i4, i5, i6, i7, i8, i
The contour corresponding to 9, i10, and i11 is not cut, and the contour shape cut into the workpiece 16 is such that the portion from which data has been removed due to interference has a curved surface along the peripheral surface of the rod-shaped tool 15. Processed. In the above description, the characters "ha"
Although only the cutting of the contour portion is described, the description of the other cut portions is omitted because there is no possibility of interference. As described above, when the character "ha" is cut using the method according to the present invention, first, 11 loops forming an offset shape and 3 loops forming a contour shape are formed. Then, it is determined whether or not interference is likely to occur by comparing the rectangles circumscribing each of the loops. With such a simple operation, 19 out of the 33 combinations of the loops constituting the offset shape and the loops constituting the contour shape are determined to have no possibility of interference, and thereafter, Can be omitted from the processing. Next, with respect to the remaining 14 cases in which the possibility of interference remains, it is determined whether or not the sides forming the offset loop and the sides forming the contour loop cross each other. Then, a determination is made in consideration of the thickness of the bar-shaped processing tool 15 only for the remaining 10 types, excluding the four types where the sides intersect. As described above, the operation proceeds from the simple operation to the complicated operation sequentially, and the processing that does not have the possibility of causing the interference or the processing where the interference is clear is not performed thereafter. Therefore, the operation can be performed efficiently. In addition, since the cutting process is performed in a state where the data is deleted for the offset loop that causes the interference, the non-cut area is not broken down. In the above, as a method of obtaining the shortest distance between the side k and the side l, the distance between the starting point of the side k and the side l is obtained. Alternatively, it may be determined from the distance between and the side k. As described above, in the offset processing method according to the present invention, first, a rectangle circumscribing each loop constituting the contour shape and a rectangle circumscribing each loop constituting the offset shape are compared. And determine if the contrast may cause interference between the two loops,
If there is no possibility of interference, the subsequent processing is omitted. This greatly simplifies operations such as calculations. Then, by performing the following processing only on those which may cause interference, it is determined whether or not interference will occur in each of the loops constituting the offset shape. Delete and perform cutting. In this way, all the offset-shaped loops that cause interference are removed, and cutting is performed only on the offset-shaped loops that are unlikely to cause interference, so that breakage to a non-cutting region can be reliably prevented. become.

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 each loop of a contour shape and an offset shape. FIG. 4 is an explanatory diagram showing sides forming a loop. FIG. 5 is an explanatory diagram showing a rectangle for determining an intersecting state of intersecting loops; FIG. 6 is an explanatory diagram illustrating a method for obtaining a shortest distance between a starting point of a side k and a side l. FIG. 7 is an explanatory diagram showing a square for determining the presence or absence of intersection between loops that do not intersect; FIG. 8 is a plan view showing a workpiece after cutting. FIG. 9 is an explanatory diagram showing a conventional example. [Description of Signs] 11 Input device 12 CPU 13 Memory 14 ······ Cutting section 15 ··· Bar-shaped tools 19, 20, 21, 22 ··· Squares i1, i2, i3, i4, i5, i6, i7, i8 , I
9, i10, i11... Loops forming an offset shape j1, j2, j3... Loops forming a contour shape k. ········································································································· d ································································································································· 最 ·

Claims (1)

(57) [Claim 1] A method for performing a cutting process while performing an offset process using a cutting device having a bar-shaped processing tool, wherein data of a contour shape to be cut and corresponding data are provided. The data of the offset shape to be created is created as data of a set of loops each formed by joining a plurality of sides, and on the coordinates, each of the squares circumscribing each of the loops forming the contour shape and the offsets forming the offset shape Two squares circumscribing the loop are compared respectively, and two loops corresponding to the squares that intersect each other or approach within the radius of the rod-shaped processing tool among the two squares compared, and the two If there are sides that intersect each other among the sides constituting the loop, or in the two loops,
If there is a distance between the starting point of one side of the loop and the side of the other loop whose shortest distance is shorter than the radius of the rod-shaped processing tool, the data of the offset-shaped loop including that side is removed. Offset processing method characterized by performing cutting processing.