JP2008071015A - Numerical controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a numerical controller having an interference checking function to accurately predict occurrence of an interference even at long intervals. <P>SOLUTION: An interpolation/distribution process is performed at predetermined intervals for executing an NC program and outputting an amount of movement instruction to each shaft that drives a movable part. The maximum/minimum positions (coordinate values) of each shaft between the prediction of a leading position and the interval of the interference checks are obtained through interpolation and distribution processes a predetermined time earlier than the above interpolation/distribution process. Based on the maximum/minimum values of each shaft between the position A of the movable part 1 during the previous interference check and the position B of the movable part 1 during the current interference check and on the three-dimensional configuration of the movable part 1, a three-dimensional area 4 for the interference checks is calculated and a determination is made as to whether or not the three-dimensional area 4 interferes with an object 2 to be interfered. Since the three-dimensional area 4 for the interference checks is calculated on the basis of the maximum and minimum positions of each shaft during the movement between the interference checks and the interference is checked, the occurrence of an interference can be reliably predicted. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a numerical control device having an interference check function for checking interference between a movable part of a machine driven by a numerical control device and another interference object.

  In a machine tool or the like controlled by a numerical control device, a movable part such as a tool or a workpiece interferes with or interferes with another object, and the movable part interferes with another interference object in order to prevent damage. It is generally performed to check whether or not the operation has started. In particular, in order to perform an interference check during automatic operation of a numerical control device, a method for acquiring the position of a movable part from a numerical control device having a function of outputting a machine position preceded by a predetermined time and performing an interference check is already known. is there.

  For example, interfering objects such as tools are defined by a solid of a combination of a plurality of solids, a machining program is executed to perform interpolation processing, and the movement position of the interfering object after the movement amount output to each axis is calculated, Calculate and obtain an interference judgment solid that represents the area that can interfere with the solid constituting the interferer that moves linearly from the current position to this calculated position, and determine the presence or absence of interference based on this interference judgment solid An interference check method using a numerical control device is known (see Patent Document 1).

JP-A-9-230918

  FIG. 1 and FIG. 2 are interference check methods that have been implemented conventionally according to the invention described in Patent Document 1. In FIG. 1, reference numeral 1 denotes a movable part of a machine controlled by a numerical control device such as a tool, and is represented as a three-dimensional shape of the movable part 1 defined in the drawing. Reference numeral 2 denotes a predefined interference object, which is shown in a three-dimensional shape defining the interference object 2 and conceptually represents these. 1A is a top view of the interference object 2 and the movable portion 1 as viewed from above, and FIG. 1B is a perspective view. When the position of the movable part 1 at the time of the previous interference check is A and the position of the movable part 1 at the time of the current interference check is B, the three-dimensional shape defined for the movable part 1 is from the position A. The area through which the three-dimensional shape of the movable part 1 obtained by linearly moving to the position B passes is defined as an interference determination area 3 (in FIG. 1, the solid of the movable part 1 at the position A and the position B is connected by a broken line). The interference is checked based on whether or not the determination area 3 and the predefined shape of the interference object 2 interfere with each other. In the example of FIG. 1, since the movable part 1 has entered the area of the interference target object 2, it is determined that interference occurs.

  On the other hand, the example shown in FIG. 2 shows an example of overlooking the occurrence of interference in this conventional interference check method. Assume that the position of the movable portion 1 at the previous interference check is A and the position of the movable portion at the current interference check is B. However, the movable part 1 moves from the position A to the position B via the passing point position C between the previous and current interference check intervals. In this case, during the movement from the position A to the position B, it enters the area of the interference object 2 at the passing point position C and interference occurs. However, in the interference check process, since the region through which the three-dimensional shape of the movable part 1 obtained by linearly moving from the position A to the position B passes is set as the interference determination region 3, it does not include this passing point position C. It is determined that no interference occurs, and the occurrence of interference is overlooked.

  As described above, the actual machine operation is sufficiently fast compared to the interference check process (the process time of the interference check process is slow compared to the machine operation). Therefore, the occurrence of interference is overlooked and the occurrence of interference cannot be predicted. There is a case. This problem occurs even when the program command is linear interpolation (for example, when moving linearly and then moving in the opposite direction), such as a three-dimensional arc or spline interpolation. This is noticeable when moving.

For example, when 100 msec is required for the interference check process, the position information used for the interference check is performed with a coordinate value every 100 msec. Taking FIG. 2 as an example, if the machine operation time from the previous position A to the current position B is 100 msec, the interference check is performed only in the broken line area 3 from the position A to the position B, and it actually passes. The interference check at the passing point position C is not performed.
If the interference check process can follow the machine operation in real time, this problem will not occur. However, the interference check is performed on all elements (work, table, column, etc.) constituting the machine as interference objects. It takes time, cannot follow the actual machine operation, and generates a non-detection unit that cannot detect and predict the interference such as the passing point position C.

  In order to solve such a problem, it is assumed that the interference check processing time is increased (for example, 50 msec) and information on the passing point position C is acquired. It is difficult to cope with changes in software logic and improvement in CPU capability.

  Therefore, an object of the present invention is to provide a numerical control device having an interference check function that can reliably predict the occurrence of interference even when the interference check cycle is as long as the conventional one.

  The present invention provides a numerical control device having a function of performing an interference check during automatic operation, and the maximum of each axis in the movement 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. Means for obtaining the position and minimum position; means for creating a solid area in which the three-dimensional shape of the predefined movable part moves from the minimum position to the maximum position of each of the obtained axes; and the solid area is defined in advance. By providing a means for checking whether or not the interference object is interfered with, it is possible to reliably predict the occurrence of interference between the movable part and another interference object.

  Even if the interference check interval is long, whether or not the solid region for interference check is created by obtaining the maximum position and the minimum position where each axis moves within the interference check interval, and the solid region interferes with the interference object Therefore, it is possible to reliably predict the occurrence of interference without overlooking the occurrence of interference.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 3 is an explanatory diagram of the principle of the interference checking method of the present invention. Similar to FIGS. 1 and 2, reference numeral 1 denotes a movable part of a machine that is driven and controlled by a numerical control device such as a tool of a machine tool, and reference numeral 2 denotes an interference target. Also in FIG. 3, the movable part 1 and the interference object 2 are displayed in their three-dimensional shapes that are defined in advance and set in the numerical control device. 3A is a top view and FIG. 3B is a perspective view. During NC program operation, when the position of the movable part 1 acquired at the previous interference check is A and the position of the movable part 1 acquired at the current interference check is B, the position acquired for the previous interference check The range information of the maximum position / minimum position of each axis during the movement from A to the position B acquired this time is acquired. As a region through which the movable part 1 passes when the three-dimensional shape defined with respect to the movable part 1 moves from the position A to the position B, a solid for interference check of the movement range surrounded by the maximum position and the minimum position. An area 4 is created, and an interference check between the three-dimensional area 4 and the interference target 2 such as a material or a mechanical structure is performed.

For example, if the movable part 1 moves in the XY plane in FIG. 3, the maximum value and minimum value of the X coordinate and the maximum value and minimum value of the Y coordinate are obtained, and the maximum value of the X and Y coordinates is calculated. The interference check is performed by determining whether or not the interference check solid region 4 as indicated by a broken line in FIG. 3 surrounded by the minimum value interferes with the solid shape of the interference object 2.
As a result, the interference check between the interference determination area 3 and the interference object 2 obtained by linearly moving between the positions acquired for each conventional interference check period as shown in FIG. The generation of interference due to the passing point C between the positions B can be predicted.

FIG. 4 is a functional block diagram of the numerical controller 10 according to one embodiment of the present invention.
In the block analysis process 12 of the NC program, each block of the NC program stored in the NC memory 11 is sequentially read and a block analysis process is performed to convert it into execution data. In the movement command amount distribution processing 16, interpolation and movement command distribution processing to each axis are performed for each distribution processing cycle based on the execution data of each block obtained in the block analysis processing 12 of the NC program. The movement command amount is output to each of the servomotors M1 to Mn to be driven, and the servomotors M1 to Mn are driven and controlled via each servo control circuit. The operation processing up to this point is the same as that of the conventional numerical control device.

  The present embodiment further includes an interference object defining means 13 for defining and storing a three-dimensional shape of an interference object such as a tool, work, table, column, etc. of a machine where interference occurs. Further, the preceding position prediction of the movable part and the maximum / minimum value storage process 15 for each axis that drives the movable part 1 are performed. In this process, similar to the movement command amount distribution process 16, interpolation and movement command distribution processing for each axis are performed for each distribution processing cycle based on the execution data of each block obtained in the block analysis process 12 of the NC program. The position of the movable part (the position of each axis that drives the movable part) is obtained and stored, and the maximum value and the minimum value of each axis during the position reading for the interference check from the interference check process described later are obtained and stored. This processing is performed prior to the movement command amount distribution processing 16 by a predetermined time (distribution processing cycle × N).

  The interference check process 14 is an interference check from the time of reading at the time of the previous interference check to the time of reading, which is obtained by the preceding position prediction and the maximum / minimum value storage process 15 of each axis for each interference check processing period. The maximum position and the minimum position are read from a register that stores the maximum position and the minimum position of each axis during reading, and then the predicted preceding position is stored in this register (acquisition of maximum / minimum coordinate values of each axis in FIG. 4). Process 21).

  The maximum position and the minimum position of each axis between the position (position of each axis that drives the movable part) A read during the previous interference check and the movement to the position B of the movable part read during the current interference check Based on the three-dimensional shape of the movable part 1 defined by the interference object defining means 13, the three-dimensional area 4 for interference check is created (three-dimensional area creation process for check 22 in FIG. 4). Further, an interference check process is performed to determine whether or not there is interference between the three-dimensional area 4 obtained in the check three-dimensional area creation process 22 and another interference object 2 stored in the interference object definition means 13 (FIG. 4. Interference check processing 23) between the interference object and the three-dimensional area.

  When it is determined by this interference check process that interference occurs, a distribution stop process 17 is performed to stop the movement command amount distribution process 16 and stop the movement of the servo motors of the respective axes. As a result, the preceding position prediction and the maximum / minimum value storage processing 15 of each axis execute the NC program block command earlier by a predetermined time (distribution processing cycle × N) than the movement command amount distribution processing 16. (The movement command amount distribution processing 16 is performed for the same block with a predetermined time later than the preceding position prediction and the maximum / minimum value storage processing 15 for each axis), so that the movable part 1 is actually operated. Interference is predicted before moving to the interference position, and the movement stops, so that interference can be avoided.

  In addition, as described with reference to FIG. 3, a solid for interference check by moving the solid of the movable part based on the maximum / minimum coordinate value of each axis that drives the movable part 1 within the position reading interval for interference check. Since the region 4 is created and it is determined whether the interference between the three-dimensional region 4 and the interference object 2 occurs, it is possible to reliably predict the occurrence of interference without overlooking the occurrence of interference.

  FIG. 5 is a flowchart showing an algorithm of processing executed by the processor (CPU) of the numerical controller as the preceding position prediction and the maximum / minimum value storage processing 15 of each axis. As described above, this process starts the process at the same cycle as the movement command amount distribution process 16 normally performed by the numerical control device, a predetermined time earlier than the distribution process (a time earlier by the distribution period × N). It is. Therefore, the normal movement command amount distribution process 16 is executed after a predetermined time delay from the preceding position prediction and the maximum / minimum value storage process 15 of each axis.

First, the processor reads the execution data of the block obtained by the block analysis processing of the NC program from the beginning (step a1), performs interpolation and distribution processing based on the execution data, and applies to each axis for each distribution cycle. A movement command amount is obtained (step a2).
The predicted position (coordinate value) of each axis is obtained from the movement command amount to each axis (step a3).
Next, the value of the register Rmax that stores the maximum position (coordinate value) of each axis during the interference check cycle is compared with the value of each axis obtained in step a3, and the position (coordinate value) obtained in step a3. If is larger, this value is stored in the register Rmax. Similarly, the value of the register Rmin that stores the minimum position (coordinate value) of each axis during the interference check period is compared with the value of each axis obtained in step a3, and the value obtained in step a3 is smaller. For example, this value is stored in the register Rmin (step a4). Thus, the maximum position and the minimum position are updated and stored in the registers Rmax and Rmin for each axis. Initially, the axis positions (coordinate values) at the start of operation are initially set in the registers Rmax and Rmin.

  Next, it is determined whether there is a position reading input from the interference check process (step a5). If there is no reading input, the process proceeds to step a7. When there is a read input, the maximum and minimum positions stored in the registers Rmax and Rmin are transferred to the interference check process, and registers for storing the maximum and minimum positions of each axis are obtained in Rmax and Rmin in step a3. The predicted position of each axis is stored (step a6).

Then, it is determined whether or not a machine stop command has been generated (step a7). If no machine stop command has been generated, it is determined whether or not the interpolation / distribution process for the block has been completed. If not, the process returns to step a2. If completed, the process returns to step a1, and the above-described processing is performed every interpolation distribution period.
As described above, in the preceding position prediction and the maximum / minimum value storage processing of each axis, the movable unit is moved a predetermined time (predetermined cycle) before the actual interpolation of the movement command amount to the servo motor of each axis. The predicted position (coordinate value) of each axis that drives 1 and the maximum and minimum positions of each axis during the previous interference check and the current interference check time are obtained, and the maximum and minimum positions of each axis are determined during the interference check. Will be read out.

FIG. 6 is a flowchart showing an algorithm of a process performed as the interference check process 14 by the processor of the numerical controller every interference check process cycle.
First, the maximum position and the minimum position stored in the registers Rmax and Rmin are read (step b1).
On the basis of the read maximum position and minimum position, and the three-dimensional shape of the movable unit 1 driven by each axis, a solid area 4 for interference check is created (step b2).

  An interference check is performed to determine whether interference occurs between the obtained three-dimensional region 4 and the defined interference object (step b3), and it is determined whether interference occurs (step b4). Then, the process returns to step b1. Hereinafter, the interference check is performed by repeatedly executing the processing from step b1 to step b4 for each interference check period. If it is determined in step b4 that interference will occur, a machine stop command is output (step b5), the movement command amount distribution process (process 16 in FIG. 4) to the servo motors of each axis is stopped, and the machine Stop operation.

It is explanatory drawing of the conventional interference check. It is explanatory drawing of the conventional interference check. It is principle explanatory drawing of the interference check of this invention. 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 preceding position prediction in the same embodiment, and the maximum / minimum position preservation | save process of each axis | shaft. It is a flowchart which shows the algorithm of the interference check process in the embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Movable part 2 Interference object 10 Numerical control apparatus M1-Mn Servo motor A Position of the movable part at the time of the previous interference check B Position of the movable part at the time of the current interference check C Passing point position

Claims (1)

  In a numerical control device that has a function of performing an interference check during automatic operation, the maximum and minimum positions of each axis in the movement from the position of the movable part at the previous interference check to the position of the movable part at the current interference check Means for obtaining a three-dimensional area in which the three-dimensional shape of the movable part defined in advance moves from the minimum position to the maximum position of each of the obtained axes, and interference in which the three-dimensional area is defined in advance. A numerical control apparatus comprising: means for checking whether interference occurs with a shape of an object.

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