JP5339999B2 - Numerical control device having interference check function - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a numerical controller for predicting the occurrence of interference, and for reliably preventing the interference. <P>SOLUTION: A numerical controller 10 equipped with an interference check part 21, and configured to decelerate and stop when interference is predicted includes: a prefetch means 12 for prefetching a program, and for converting it into prefetch block command data 13; a future position calculation part 19 for calculating a future machine position a predetermined time after for each predetermined cycle based on the actual machine position of a mobile section and prefetch block command data; and a means for calculating the traveling direction vector of the calculated future machine position, defining the future machine position calculated at first as a reference position, successively comparing the traveling direction vector of the machine position as the reference position with the traveling direction vector at the calculated future machine position, defining the machine position where the angle difference exceeds an allowable value as a new reference position, defining the machine position where the angle difference exceeds the allowable value as the future motion trajectory, and outputting it to the inference check part 21. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a numerical control device having a function of storing an outline of a movable part of a machine such as a tool or a workpiece and an outline of a fixed part of the machine and performing an interference check based on the stored outline model.

  A machine tool controlled by a numerical control device is one in which the numerical control device drives and controls the movable part (control axis) of the machine based on an NC program created in advance to process a workpiece or the like of a workpiece. It is. The tool attaches the workpiece or workpiece during machine operation, such as when there is an error in the NC program, when there is an error in attaching the workpiece to the machine, or when there is an error in the tool offset input. Interference between the machine movable part and other objects, such as collision with a jig or the like, may occur.

  A numerical control device having a function of predicting the above-described interference and generating an alarm is already known. In the interference prediction method, for example, a workpiece shape, a tool shape, a machine shape such as a machine interference check surface is set in advance, a movement command is read from a program, and the workpiece shape, tool shape, and machine shape set as the movement command are read. Check whether the workpiece and tool or machine are not interfering with each other.

  As a numerical control device having an interference check function, Patent Document 1 discloses a time required for safely stopping the machine after detecting the interference in order for the interference check device to check the interference of the machine during automatic operation. A technique using a machine position that precedes an actual machine position for a certain period of time is disclosed.

  Further, in Patent Document 2, in order to reliably predict the occurrence of interference even if the period of the interference check is long, from the position of the movable part at the time of the previous interference check to the position of the movable part at the time of the current interference check. A technique for acquiring the maximum position and the minimum position of each axis in movement is disclosed.

JP 2008-27376 A JP 2008-71015 A

In the technology disclosed in Patent Document 1 described in the background art, in order to accurately perform the interference check, the interference check device performs the operation for all machine positions that are preceded by a certain time that the numerical control device outputs for each interpolation period. It is necessary to perform an interference check while simulating machine operation and material cutting.
However, since the interference check process requires a very large amount of calculation, the interference check process cannot be completed within the interpolation cycle time of the numerical control device. May be missed. As a result, there is a difference between the actual operation of the machine and the operation recognized by the interference check device, and when the interference cannot be detected or there is a difference between the actual operation of the machine and the material cutting simulation of the interference check device. Unlike the actual shape of the material, there was a problem that the interference check could not be performed correctly (see FIGS. 6 to 8).

  An example in which the interference shown in FIG. 6 cannot be detected will be described. In the case where the moving operation is fast-forwarding of linear movement, the position acquired by the interference check device for performing the interference check first is P1, and in the interference check device, the interference check processing time for P1 is equal to the interpolation cycle time of the numerical control device. When ten times the time is required, the numerical controller outputs the positions of P2, P3,... P10, P11 while the interference check device performs the interference check process. When the interference check device performs an interference check at the position P1, and acquires the machine position to perform the next interference check, the position P11 is acquired. As a result, the interference check apparatus regards the movement path as a fast-forward movement from P1 to P11, and thus cannot detect interference.

An example of erroneously detecting interference shown in FIG. 7 will be described. In the case of a minute motion or a circular motion, the position acquired for performing the interference check first is P1, and the interference check device requires 10 times the interpolation cycle time of the numerical control device for the interference check processing time for P1. In this case, the numerical control device outputs the positions of P2, P3,..., P10, P11 while the interference check device performs the interference check process.
When the interference check device performs the interference check at the position P1 and acquires the machine position to perform the next interference check, the position P11 is acquired. As a result, since the interference check device regards the movement path as a cutting movement from P1 to P11, the parts to be cut (the moving operation parts of P2, P3,..., P10, P11) are not cut and the actual material is cut. There is a difference between the shape and the material recognized by the interference check device. Therefore, when the workpiece is moved to the position of P12 by approaching the already cut portion by rapid traverse, there is a difference between the material shape recognized by the interference check device and the actual material shape. It is erroneously detected that it interfered with.

  An example of erroneously detecting interference shown in FIG. 8 will be described. When performing the interference check for the hole processing or the groove processing for processing the portion indicated by the one-dot chain line, the position acquired for performing the interference check first is defined as P1, and the interference check device performs the interference check processing time for P1 in the numerical control device. When 10 times the interpolation cycle time is required, the numerical control device outputs the positions P2, P3,..., P10, P11 while the interference check device performs the interference check process. P1 to P8 are cutting operations, and P8 to P11 are fast-forwarding operations. Therefore, when the interference check device performs an interference check at the position P1 and acquires the machine position for the next interference check, the position P11 is acquired as the fast-forward position. As a result, the interference check device regards the movement route as fast-forward movement from P1 to P11, and erroneously detects that the material has interfered with the material by fast-forward.

  Moreover, although the technique disclosed in Patent Document 2 can reliably perform the interference check, it is not possible to specify the movement path within the range between the maximum position and the minimum position of each axis. For this reason, there is a problem in that interference may be detected even for movement in which interference does not occur.

Accordingly, in view of the above-described problems of the prior art, an object of the present invention is to output a machine position that precedes for a certain period of time based on a machining program in order to perform an interference check during automatic operation of a machine by a numerical controller. An object of the present invention is to provide a numerical controller for outputting only the machine position that can predict the occurrence of interference and reliably prevent the interference.
Another object of the present invention is to provide a numerical control device capable of obtaining a machine position necessary for performing a cutting simulation of a material to be cut according to the movement of a movable object as a locus of a movable part of the machine and performing an accurate simulation in an interference check. Is to provide.

The invention according to claim 1 of the present application is
A numerical control device for driving and controlling a movable part of a machine based on a command from a program, comprising an interference check means for checking interference between the movable part and another object, and interference is predicted by the interference check means. In the numerical control device that decelerates and stops the movement of the movable part when
Prefetching means for prefetching the program and converting it into prefetch block command data;
A preceding position calculating means for calculating a preceding machine position after a predetermined time every fixed period based on the actual machine position of the movable part and the prefetch block command data;
The calculated advance direction vector of the preceding machine position is calculated, the preceding calculated machine position is set as a reference position, the advance direction vector of the machine position as the reference position, and then the calculated advance direction The traveling direction vector at the machine position is sequentially compared, and the machine position whose angle difference exceeds a preset tolerance is set as a new reference position, and the machine position exceeding the tolerance is set as a preceding movement trajectory. Means for outputting to the interference check means,
The numerical control apparatus having an interference check function, wherein the interference check unit performs an interference check based on the preceding movement trajectory.

  According to the present invention, in order to perform an interference check during automatic operation of a machine by a numerical controller, the occurrence of interference is predicted in a numerical controller that outputs a machine position that is preceded by a predetermined time for each interpolation period based on a machining program. A numerical control device that outputs only the preceding machine position that can reliably prevent this interference can be provided, and the machine position required for simulating the material to be cut according to the movement of the movable object can be determined. It is possible to provide a numerical control device that can be obtained as a trajectory and can perform an accurate simulation in an interference check.

It is a functional block diagram of the numerical control apparatus of one Embodiment of this invention. It is a flowchart which shows the algorithm of the process which the numerical control apparatus in one Embodiment of this invention performs. It is a flowchart which shows the algorithm of the process in the machine position calculation part which needs an interference check. It is a figure explaining the example which processes a raw material with the machine controlled by a numerical control apparatus. It is a figure explaining that the shape similar to an actual cutting raw material can be recognized and the erroneous detection by an interference check can be prevented. It is a figure explaining the example which cannot perform the interference check in a prior art. It is a figure explaining the example in which the interference check in a prior art is made mistakenly. It is a figure explaining the example in which the interference check in a prior art is made mistakenly.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a functional block diagram of a numerical controller according to an embodiment of the present invention. The numerical controller 10 is divided into preprocessing and execution. In the preprocessing, the prefetching means 12 that performs preprocessing reads the command for each block from the machining program 11 stored in the machining program storage unit, converts the command into execution format data, creates the prefetched block command data 13, Stored in storage means for storing block command data.

  The interpolation / movement command distribution processing unit 14 that performs the execution process reads the prefetch block command data 13 for each block, and from each axis movement amount, each axis speed, and feed speed override command unit 23 commanded in the block. Based on the override value (%), a distribution movement amount commanded to each axis movable part (servo motor 22 of each axis) for each distribution cycle is obtained, and the distribution movement amount is added to the current position register 15 to obtain the current coordinates. Update the position (hereinafter “current position”). Further, the distributed movement amount which is a movement command is output to the movement command output unit 16 and is output to the acceleration / deceleration processing unit 17 via the movement command output unit 16. The acceleration / deceleration processing unit 17 performs acceleration / deceleration processing in response to a movement command from the movement command output unit 16, and moves the acceleration / deceleration processing by the acceleration / deceleration processing unit to the servo control unit 18 that controls the servo motor 22. The movement command is output.

  The servo control unit 18 determines the position and speed based on the movement command and the position and speed feedback from the position / speed detector attached to the servo motor 22 (or a movable part driven by the servo motor). Current feedback control based on feedback control and current feedback from a current detector that detects drive current is performed, and drive control of the servo motor 22 is performed via an amplifier (not shown). In FIG. 1, only one servo motor 22 is shown, but the same control is performed on the servo motor of each axis (each movable part) of the machine tool, and each movable part controls the position and speed. Is made. The feed speed override command unit 23 is input means for designating an override value.

  The configuration of the numerical control device 10 described above is a known configuration of a numerical control device that conventionally controls a machine. In an embodiment of the present invention, the numerical controller 10 further includes a preceding position calculation unit 19 after a certain time, a machine position calculation unit 20 that requires interference check, and an interference check unit 21 in addition to a conventionally known configuration. Yes.

The predecessor position calculation unit 19 after a certain period of time determines the actual machine position from the information in the prefetch block command data 13 or the current position of the machine stored in the interpolation movement command distribution processing unit 14 or the current position register 15. The current position data is acquired, and the machine position after a certain time is calculated by the preceding position calculation unit 19 after a certain time based on the prefetch block command data 13.
Further, when calculating the preceding position after a certain time, correction is made based on a command from the feed speed override command unit 23. The moving speed of the movable part is corrected by a command (%) from the speed specified by the machining program and the feed speed override command unit 23. Using this corrected moving speed, the actual machine position of the machine, and the pre-read block command data, the machine position after a certain time can be calculated.

  The machine position calculation unit 20 requiring the interference check is a minimum machine position required for simulating the machine position and the material to be cut, which are necessary for the interference check unit 21 to perform the interference check according to the operation of the movable unit. Is output to the interference check unit 21 as a preceding movement trajectory. The processing in the machine position calculation unit 20 that requires the interference check will be described later with reference to the flowchart shown in FIG.

  The interference check unit 21 stores contour shapes of tools and workpieces, machine structures, and the like, and based on the position of the movable unit that needs to be checked for interference sent from the machine position calculation unit 20, It is means for checking whether or not an interference check between the movable part and another object occurs. In the embodiment of the present invention, the interference check unit 21 performs the interference check based on the preceding movement trajectory sent from the machine position calculation unit 20 that needs the interference check. The interference check method and process of the interference check unit 21 are the same as those conventionally performed, and detailed description thereof is omitted. In FIG. 1, the interference check unit 21 is provided in the numerical control device 10, but may be provided outside the numerical control device 10 as an information processing device such as a personal computer, for example. In this case, information for interference check is exchanged between the information processing apparatus and the numerical control apparatus 10 via an interface (not shown).

FIG. 2 is a flowchart showing an algorithm of processing executed by the numerical controller according to the embodiment of the present invention. When the numerical controller starts its operation, it reads the machining program and performs the processing from step 100 onwards. First, preprocessing (step 100) is performed to create execution data, which is stored as prefetch block command data (step 101).
Based on the prefetch block command data, an execution process for distributing the movement command to each axis is performed. First, prefetch block command data of one block from the head is read (step 102). If the read command is not a program end command (step 103), the movement command distribution process of step 104 is executed. If the command is not a movement command, the command is executed.

The movement command distribution process in step 104 is performed based on the position (movement amount) and feed speed commanded in the read-ahead read block and the speed override value commanded by the feed speed override command unit 23. The distribution movement amount for each distribution cycle is obtained. The distribution movement amount thus obtained is added to the current position register 15 to update the current position (step 105).
Next, a process for calculating and outputting a position (command position) after a predetermined time for causing the interference check unit 21 to perform an interference check based on the prefetch block command data is performed (step 106) (after the predetermined time shown in FIG. 1). Processing of the preceding position calculation unit 19). This process is not directly related to the amount of movement distributed to each axis, but for each movement command distribution period, a position after a certain time from the current machine position is calculated, and a machine position calculation unit that requires interference check 20 output.

Next, the machine position calculation unit 20 that requires the interference check calculates the machine position that requires the interference check and outputs it to the interference check unit 21 (step 107). The machine position calculation process that requires interference check will be described later with reference to the flowchart shown in FIG. Next, it is determined whether an axis stop command is commanded from the interference check unit 21 (step 108). If not commanded, the distributed movement amount obtained in step 104 is output to the acceleration / deceleration processing unit 17, and the acceleration / deceleration processing is performed. The amount of movement after this is output to the servo control unit 18 (steps 109 to 111).
On the other hand, if an axis stop command is instructed from the interference check unit 21 in step 108, an axis stop process is performed (step 113), and the acceleration / deceleration process unit 17 stops the acceleration / deceleration process and applies acceleration to the servo control unit 18. The output of the movement amount subjected to the deceleration process to the servo control unit 18 is stopped, and the moving unit is stopped.

FIG. 3 is a flowchart showing an algorithm of processing performed by the machine position calculation unit 20 that requires interference check of the numerical control apparatus according to the embodiment of the present invention.
[Step SA1] Initially set n to 1 and m to 2, and proceed to Step SA2.
[Step SA2] It is determined whether or not the position Pn is the final position. If it is the final position, the process proceeds to Step SA10, and if it is not the final position, the process proceeds to Step SA3. The determination of whether or not it is the final position can be made based on the number of n. The maximum number of n is the number of preceding positions calculated by the preceding position calculating unit 19 after a predetermined time by the numerical controller during the immediately preceding interference checking period in the interference checking unit 21. It can be determined whether or not the position Pn is the final position. In addition, the interference check in the interference check unit 21 is periodically repeated.
[Step SA3] The traveling direction vector Vn for the position Pn is obtained, and the process proceeds to Step SA4. The traveling direction vector at the position Pn is calculated by using the moving speed command data (feed speed designation data) of each movable shaft at the position Pn.
[Step SA4] It is determined whether the position Pm is the final position. If it is the final position, the process proceeds to Step SA10. If it is not the final position, the process proceeds to Step SA5.
[Step SA5] A traveling direction vector Vm for the position Pm is obtained, and the process proceeds to Step SA6.
[Step SA6] It is determined whether or not the angle difference Tnm between the traveling direction vector Vn and the traveling direction vector Vm is larger than the allowable value. If it is larger, the process proceeds to Step SA8, and if not larger, the process proceeds to Step SA7.
[Step SA7] Increment m by one and return to Step SA4 to continue the processing.
[Step SA8] Pm is output to the interference check unit as a position where the interference check is required, and the process proceeds to Step SA9. The data of the position Pm output to the interference check unit is also output to the interference check unit together with data for identifying whether it is cutting command data or rapid feed data. This data for identification is data included in the prefetch block command data 13.
[Step SA9] Set n = m, and proceed to Step SA2.
[Step SA10] The final position is output to the interference check unit, and the process ends.

  Since the interference check unit 21 can determine whether it is a fast feed process or a cutting feed process based on a command of the machining program, the preceding movement locus input to the interference check unit 21 at the time of cutting feed. Based on the above, the shape data of the material stored in the interference check unit 21 is updated.

  FIG. 4 is a diagram for explaining an example of processing a material by a machine controlled by a numerical control device. For the movement of FIG. 7, the interpolation positions (P2, P3,..., P11) output by the numerical controller while P11 is acquired after the P1 interference check is processed will be shown as an example. In addition, P1, P2,..., P11 indicate preceding positions, and each preceding position is information in the prefetch block command data 13 shown in FIG. The actual machine current position is acquired from the machine current position stored in the position register 15, and the machine position after a certain time is calculated by the preceding position calculation unit 19 after a certain time based on the prefetch block command data 13. . Here, the traveling direction vectors at the positions of P1, P2,..., P10 are V1, V2,..., V10, respectively, and an allowable value (t) (a two-point direction vector Set the angle difference.

The processing of the flowchart shown in FIG. 3 will be described as an example of processing at each position in FIG.
(1) First, using P1 as a reference position, an angular difference (T12) between the traveling direction vector (V1) and the traveling direction vector (V2) with respect to P2 is calculated.
(2) T12 and t are compared, and if T12> t, a position where an interference check is necessary is set. Since T12 ≦ t, P2 is not a position where an interference check is necessary.
(3) Similarly, when V3, V4,... Are sequentially compared with the traveling direction vector V1 at the reference position P1, T14> t as shown in FIG. 4C, and the position of the traveling direction vector V4, that is, The position of P4 is output to the interference check unit 21 as a position that requires the first interference check.
(4) The reference position is updated from P1 to P4, P5 is set as the reference position, the subsequent V5, V6,... Are compared with the traveling direction vector V4 of P4, the same processing is continued up to V10, and T45> t Therefore, a position P5 that requires interference check is calculated.
(5) When the interference check part 21 acquires P11 as a result, it acquires the position of P4 and P5 simultaneously.

As described above, the interference check unit 21 performs the cutting simulation at the points (P4, P5) that can be newly acquired by the present invention in addition to the points (P1, P11) that have been acquired conventionally, so that the actual state as shown by the thick line in FIG. Therefore, it is possible to recognize a shape similar to that of the cutting material, and to prevent erroneous detection in the interference check.
In other words, as described above, the interference check unit 21 stores the contour shape of a tool or a workpiece, the contour shape of a machine structure, etc., and requires an interference check sent from the machine position calculation unit 20 that requires interference check. This is a means for checking whether or not an interference check between the movable part and another object occurs based on the position of the movable part. The interference check part 21 determines the contour shape of the workpiece, which is a material, by the above-described method. It can be updated including newly acquired points.

Similarly, the case where the process of the flowchart of the algorithm shown in FIG. 3 is applied to FIG. 6 will be described.
(1) First, using P1 as a reference position, an angular difference (T12) between the traveling direction vector (V1) and the traveling direction vector (V2) with respect to P2 is calculated.
(2) T12 and t are compared, and if T12> t, a position where an interference check is necessary is set. Since T12 ≦ t, P2 is not a position where an interference check is necessary.
(3) Similarly, when V3, V4,... Are compared sequentially with respect to V1, T16> t, and the position of V6, that is, P6 is output to the interference check unit 21 as a position that requires the first interference check.
(4) Further, with reference to P6, the subsequent V7, V8,... Are compared with the traveling direction V6, the same processing is continued up to V10, and a position where an interference check is required is calculated.
(5) As a result, when acquiring P11, the position of P6 is acquired simultaneously.
As described above, the interference check unit 21 can perform the interference check at the point (P6) that can be newly acquired by the present invention in addition to the points (P1, P11) acquired conventionally, and can detect the interference. .

Similarly, the case where the process of the flowchart of the algorithm shown in FIG. 3 is applied to FIG. 8 will be described.
(1) First, using P1 as a reference position, an angular difference (T12) between the traveling direction vector (V1) and the traveling direction vector (V2) with respect to P2 is calculated.
(2) T12 and t are compared, and if T12> t, a position where an interference check is necessary is set. Since T12 ≦ t, P2 is not a position where an interference check is necessary.
(3) Similarly, if V3, V4,... Are sequentially compared with respect to V1, T18> t and V8, that is, the position of P8 is output to the interference check unit 21 as a position requiring the first interference check.
(4) Further, with reference to P8, V9, V10,... Are compared with V8, the same processing is continued up to V11, and a position where interference check is necessary is calculated.
(5) As a result, when acquiring P11, the position of P8 is acquired simultaneously.
As described above, the interference check unit 21 updates the contour shape of the workpiece, which is a material, based on the point (P8) that is a cutting command position that can be newly acquired by the present invention, in addition to the points (P1, P11) acquired conventionally. It becomes possible to prevent erroneous detection of interference check.

DESCRIPTION OF SYMBOLS 10 Numerical control apparatus 11 Processing program 12 Prefetching means 13 Prefetch block command data 14 Interpolation movement command distribution processing part 15 Current position register 16 Movement command output part 17 Acceleration / deceleration processing part 18 Servo control part 19 Predecessor position calculation part after a fixed time 20 Machine Position Calculation Unit 21 Needing Interference Check Interference Check Unit 22 Servo Motor 23 Feed Speed Override Command Unit

Claims (1)

A numerical control device for driving and controlling a movable part of a machine based on a command from a program, comprising an interference check means for checking interference between the movable part and another object, and interference is predicted by the interference check means. In the numerical control device that decelerates and stops the movement of the movable part when
Prefetching means for prefetching the program and converting it into prefetch block command data;
A preceding position calculating means for calculating a preceding machine position after a predetermined time every fixed period based on the actual machine position of the movable part and the prefetch block command data;
The calculated advance direction vector of the preceding machine position is calculated, the preceding calculated machine position is set as a reference position, the advance direction vector of the machine position as the reference position, and then the calculated advance direction The traveling direction vector at the machine position is sequentially compared, and the machine position whose angle difference exceeds a preset tolerance is set as a new reference position, and the machine position exceeding the tolerance is set as a preceding movement trajectory. Means for outputting to the interference check means,
A numerical control apparatus having an interference check function, wherein the interference check unit performs an interference check based on the preceding movement locus.

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