Interference monitoring device

Abstract

Interference monitoring device (100) which performs a check for interference between a tool and a workpiece in a machine in order to carry out a predetermined machining of the workpiece while the tool and the workpiece are moved relative to each other on the basis of a program (20), wherein the interference monitoring device (100) comprises: a forward position calculation unit (15) which, based on the program (20), calculates a forward position of the tool or workpiece by a predetermined time period; an interference checking unit (2) which draws an estimated shape of a machined part of the workpiece after machining based on the advance position and performs interference checking based on the estimated shape of the machined part of the workpiece in the drawing; and a calculation unit (16) for an uncut area, which calculates an error between the estimated shape of the machined part of the workpiece in the drawing and an actual shape of the machined part of the workpiece after machining as an uncut area in the estimated shape of the machined part of the workpiece in the drawing, wherein the interference checking unit (2) does not perform interference checking in the uncut area.

Description

BACKGROUND OF THE INVENTION Subject of the invention

[0001] The present invention relates to an interference monitoring device that checks for interference between a tool and a workpiece in a machine in order to perform a predetermined machining of the workpiece while the tool and the workpiece are moved relative to each other on the basis of a program. State of the art

[0002] In a machine tool, for example, a tool and a workpiece are moved relative to each other based on a pre-defined program for machining the workpiece. If there is an error in the program or an error in the workpiece's mounting to the machine, interferences or malfunctions can occur, such as the tool colliding with the workpiece or with a workpiece clamping device during machine operation.

[0003] In this context, an interference monitoring device was developed (for example, patent document 1). In this interference monitoring device, for example, a program predicts the advance position (a preview of an advanced position) of a tool or workpiece by a predetermined time period, and the interference between the tool and the workpiece is checked based on the calculated advance position. If the occurrence of an interference is expected, the movement of the tool or workpiece is slowed down and stopped.

[0004] Patent document 1: Japanese patent JP 4221016 B2, published as JP 2008-027376 A.

[0005] US 2012 / 0203373 A1 discloses a method for generating a toolpath in a milling machining system, the method comprising: (A) a form offset step; (B) a step to form a virtual wall; (C) a step to form an interference area and to rework the form; (D) a step to form a closed form; (E) a step to form an intersection surface; (F) steps to form a toolpath; (G) a step to capture an unmachined area; and (H) a step to form a toolpath for an unmachined area. SUMMARY OF THE INVENTION

[0006] The present inventor developed the idea of ​​performing interference checking using an interference monitoring device. According to this check, while the estimated cutting shape of a workpiece is being drawn—in other words, while an estimated shape of a machined part of the workpiece is being drawn after machining—an interference check is performed based on the estimated shape of the machined part of the workpiece in the drawing. This idea presents the following problem.

[0007] As in Fig. As shown in Figure 3A, for example, the instruction endpoints (very small continuous blocks) Pa1 on an instruction path 1 are specified during actual control. Meanwhile, an interference monitoring device calculates a forward position Pb1 by predicting a program, which corresponds to time t1. N and the time t1 N+1This corresponds to a predetermined time period in advance. Therefore, the distance between points in a sequence of advance positions Pb1 is greater than the distance between the command endpoints Pa1, meaning that no intermediate coordinate corresponding to the command endpoint Pa1 can be calculated.

[0008] If the interference monitoring device draws an estimated shape of a machined part of the workpiece W after machining based on the advance positions Pb1, an error occurs between the estimated shape of the machined part of the workpiece W in the drawing (for example, a dashed line in a straight line between the advance positions Pb1) and an actual shape of the machined part of the workpiece W after machining (for example, a solid line along the command endpoints Pa1), as shown in Fig. Figure 3B shows an error (also referred to as the uncut area R). The uncut area R is an area that is cut off from the actual shape of the machined part of the workpiece W after machining, but which is incorrectly identified as an uncut area in the estimated shape of the machined part of the workpiece W in the drawing.

[0009] As in Fig. As shown in Figure 3C, a cut can then be instructed along a command path 2 next to the last command path 1. As shown in Fig. As shown in 3D, when the interference monitoring device has a forward position Pb2 on command path 2, which is at time t2 N and the time t2 N+1The interference monitoring device, which calculates and performs a disturbance check along a straight line connecting the advance positions Pb2, incorrectly identifies a cutting volume in the uncut area R as equal to or greater than a predetermined value. Thus, the interference monitoring device falsely detects that a disturbance has occurred between the tool T and the workpiece W, as shown in Fig. 3E is shown. This involuntarily leads to the operation of a machine tool being stopped, even though in reality there is no interference between the tool T and the workpiece W.

[0010] It is an object of the present invention to provide an interference monitoring device that prevents the erroneous detection of interference between a tool and a workpiece. This object is achieved by the subject matter of claim 1.

[0011] (1) An interference monitoring device according to the present invention (for example, the interference monitoring device 100 described later) performs a check for interference between a tool and a workpiece in a machine in order to carry out a predetermined machining operation on the workpiece while the tool and the workpiece are moved relative to each other based on a program. The interference monitoring device comprises: a forward position calculation unit (for example, the forward position calculation unit 15 described later) which, based on the program, calculates a forward position of the tool or the workpiece by a predetermined time period;An interference checking unit (for example, the interference checking device 2 described below) that draws an estimated shape of a machined part of the workpiece after machining based on the advance position and performs interference checking based on the estimated shape of the machined part of the workpiece in the drawing; and an uncut area calculation unit (for example, the uncut area calculation unit 16 described below) that calculates a discrepancy between the estimated shape of the machined part of the workpiece in the drawing and an actual shape of the machined part of the workpiece after machining as an uncut area in the estimated shape of the machined part of the workpiece in the drawing. The interference checking unit does not perform interference checking in the uncut area.

[0012] (2) In the interference monitoring device according to paragraph (1), the uncut area computation unit may calculate a maximum width in the uncut area. If an offset width between an estimated path based on an advance position on a previous command path and an estimated path based on an advance position on a current command path is equal to or less than the maximum width in the uncut area, the interference checking unit determines that the current command path should pass through the uncut area and does not perform interference checking.

[0013] (3) In the interference monitoring device according to point (2), the computation unit for the uncut area can calculate motion direction vectors from a calculated forward position at time t. NThis corresponds to calculating multiple command positions and a direction of movement vector vib from the calculated forward position, which corresponds to time t. N corresponds to a calculated advance position, which corresponds to time t N+1 This corresponds to calculating the multiple command positions. These are command positions between the calculated advance position, which corresponds to time t. N corresponds to, and the calculated advance position, which corresponds to time t N+1The uncut region computation unit can convert the motion direction vector vib into a unit vector. The uncut region computation unit can calculate the absolute value of the outer product of the unit vector and each motion direction vector via, thereby obtaining a normal offset width of each motion direction vector via to the motion direction vector vib. The uncut region computation unit can define a maximum of the offset widths as the maximum width in the uncut region.

[0014] (4) In the interference monitoring device according to point (1), the uncut area computation unit can calculate an area in the uncut area. If an area of ​​the current machining operation is equal to or smaller than the area in the uncut area, the interference monitoring unit determines that the current machining operation is being carried out in the uncut area and does not perform any interference checking.

[0015] (5) In the interference monitoring device according to point (4), the computation unit for the uncut area can calculate motion direction vectors vi from a calculated forward position at time t N This corresponds to calculating the multiple command positions and a direction of movement vector vi from the calculated forward position, which corresponds to time t. N corresponds to a calculated advance position, which corresponds to time t N+1This corresponds to calculating the multiple command positions. These are command positions between the calculated advance position, which corresponds to time t. N corresponds to, and the calculated advance position, which corresponds to time t N+1 This corresponds to the calculation unit for the uncut area. The unit of computation for the uncut area can obtain an area si in a region enclosed by the direction of motion vector vi and an adjacent direction of motion vector vi+1. The unit of computation for the uncut area can be the total sum of the areas si from time t. N up to the time t N+1 define as the area within the uncut region.

[0016] According to the present invention, the interference monitoring device can prevent a faulty detection of a disturbance between the tool and the workpiece. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 shows the configuration of an interference monitoring device according to one embodiment; Fig. Figure 2 shows a flowchart illustrating interference checking by an interference monitoring device according to a first embodiment; Fig. 3A shows a problem regarding an interference monitoring device; Fig. Figure 3B shows the problem with the interference monitoring device; Fig. Figure 3C shows the problem with the interference monitoring device; Fig. 3D shows the problem with the interference monitoring device; Fig. Figure 3E shows the problem with the interference monitoring device; Fig. Figure 4 shows the function of a calculation unit for an uncut area in the interference monitoring device according to the first embodiment; Fig. Figure 5 shows the function of the calculation unit for the uncut area in the interference monitoring device according to the first embodiment; Fig. Figure 6 shows the function of the calculation unit for the uncut area in the interference monitoring device according to the first embodiment; Fig. Figure 7 shows a flowchart illustrating a fault detection process by an interference monitoring device according to a second embodiment; Fig. Figure 8 shows the function of a calculation unit for an uncut area in the interference monitoring device according to the second embodiment; Fig. Figure 9 shows the function of a computation unit for an uncut area in the interference monitoring device according to the second embodiment; and Fig. Figure 10 shows the function of an interference checking device in the interference monitoring device according to the second embodiment. [Detailed description of the invention]

[0017] Examples of embodiments of the present invention are described below with reference to the accompanying drawings. Corresponding or comparable parts in the drawings are identified by the same reference numerals. (First embodiment)

[0018] Fig. Figure 1 shows the construction of an interference monitoring device according to a first embodiment. An interference monitoring device 100, as shown in Fig. The system shown in Figure 1 comprises a numerical control 1 and an interference monitoring device (interference monitoring unit) 2. The interference monitoring device 100 is not limited to a setup with the two devices and can be configured as a single device. The numerical control 1 moves a tool based on a program to control a machine tool (for example, a servo motor 3) to perform a machining operation, such as cutting, on a workpiece. The numerical control 1 calculates a tool advance position based on the program. The interference monitoring device 2 checks for interference between the tool and the workpiece based on the calculated advance position.

[0019] The numerical control 1 includes a command analysis unit 10, a distribution processing unit 11, a motion command output unit 12, an acceleration / brake processing unit 13, a servo control unit 14, a forward position calculation unit 15 and a calculation unit 16 for an uncut area.

[0020] The instruction analyzer 10 reads an instruction corresponding to a block from a program 20, converts the read instruction into data in an emulation, and generates look-ahead block instruction data or preview block instruction data 21. The instruction analyzer 10 stores the preview block instruction data 21, for example, in main memory (not shown).

[0021] The distribution processing unit 11 sequentially reads portions of the preview block command data 21 corresponding to a block. Based on the stroke and velocity of each axis instructed in the block and a bridging value (%) instructed by a feed velocity bridging command unit 4, the distribution processing unit 11 determines a distributed stroke in each distribution cycle, which is passed as a command to a moving part of each axis (a servo motor of each axis). The distribution processing unit 11 adds the determined distributed strokes, for example, to a current position directory (not shown), thus updating a current coordinate position (hereinafter referred to as a current position).

[0022] The distribution processing unit 11 outputs the determined distributed strokes to the acceleration / brake processing unit 13 via the motion command output unit 12. As described later, the motion command output unit 12 stops the output of the distributed strokes in a motion command issued by the distribution processing unit 11 to the acceleration / brake processing unit 13 in response to an input of an axis stop command from the interference checking device 2. Furthermore, the motion command output unit 12 outputs the motion command to the acceleration / brake processing unit 13 if no axis stop command has been input from the interference checking device 2.

[0023] The acceleration / deceleration processing unit 13 performs acceleration / deceleration processing in response to receiving the motion command and outputs a motion command, which includes a stroke resulting from the acceleration / deceleration processing, to the servo control unit 14. The servo control unit 14 performs position feedback control and velocity feedback control based on the output motion command, as well as position feedback from a position detector and velocity feedback from a velocity detector attached to the servo motor 3 (or a moving part controlled by the servo motor 3). Furthermore, the servo control unit 14 performs current feedback control based on current feedback from a current detector to detect a drive current and controls the drive of the servo motor 3 through an amplifier. While in Fig. 1 where only one servomotor 3 is shown, servomotors for all axes (all moving parts) of a machine tool are controlled in the same way to control the respective positions and speeds of the moving parts.

[0024] The advance position calculation unit 15 is a functional means that determines an advance position, which indicates the position to which a moving part driven by the servomotor 3 is to be moved from its current position after a certain advance time interval. The advance position is calculated based on the current position of the moving part, the set advance time interval, the preview block command data 21, and a bridging value (%) entered by the feed rate bridging command unit 4. The advance position calculation unit 15 outputs the advance time interval and the coordinate value of the advance position to the interference checking device 2 for interference checking.

[0025] The advance time duration used by the advance position calculation unit 15 is a value determined by adding a predetermined free time α and a value (TP1 + TP2 + TP3), the latter being obtained by adding a duration TP1 required for the interference checking device 2 to perform an interference check, a duration TP2 required for communication between the advance position calculation unit 15 and the interference checking device 2, and a duration TP3 required to decelerate and stop a moving part. Once this system configuration is established, the duration TP2 for communication between the advance position calculation unit 15 and the interference checking device 2 generally assumes a constant value without significant change and can be determined by measurement.The time duration TP3 required for deceleration and stopping is a constant value determined according to the configuration of the acceleration / deceleration processing unit 13. In contrast, the time duration TP1 required by the interference checking device 2 to perform the interference check varies according to the operating positions of the multiple moving parts.Taking into account the fact that the position of the moving part to be subjected to a fault check according to the current time is generally close to the position of the moving part that was subjected to the last fault check, a time period required for a fault check, which was performed immediately beforehand by the interference checking device 2, can be returned to the advance position calculation unit 15 for use as the advance time period, and this time period can be used as a time period TP1 required for the fault check.Alternatively, the interference checking device 2 or the advance position calculation unit 15 can use the advance time duration to determine an average of the time intervals required in the past for interference checks performed immediately prior (an average of the time intervals required for the last interference check, the penultimate interference check, the one before that penultimate interference check, ...). The determined average can be used as the time interval TP1 required for an interference check.

[0026] The interference checking device 2 stores the outline shape of a tool or workpiece, the outline shape of a machine, etc., when it receives the advance time and the coordinate value of the advance position from the advance position calculation unit 15. Based on the position of each moving part transmitted by the advance position calculation unit 15, the interference checking device 2 performs a check to determine whether an interference occurs between the tool and the workpiece and issues an axis stop command to the motion command output unit 12 based on the check result. The interference checking device 2 is equipped with an information processor, such as a PC.Further details of the processing carried out by the advance position calculation unit 15 and the interference verification device 2 are not described in this description, as they are publicly known from conventional methods, such as the method described in patent document 1.

[0027] The interference checking device 2 can be a device with which, while the estimated section from a workpiece is being drawn—in other words, while an estimated shape of a machined part of the workpiece is being drawn after machining—an interference check is performed based on the estimated shape of the machined part of the workpiece in the drawing. In this case, the following problem arises.

[0028] As in Fig. As shown in Figure 3A, for example, in the actual control by the distribution processing unit 11, the acceleration / brake processing unit 13, and the servo control unit 14, command endpoints (very small, continuous blocks) Pa1 are specified on a command path 1. Meanwhile, the advance position calculation unit 15 calculates an advance position Pb1 corresponding to a time t1 based on the preview block command data 21. N and a time t1 N+1 by a predetermined time interval. This makes the distance between points in a sequence of advance positions Pb1 greater than the distance between the command endpoints Pa1, meaning that no intermediate coordinate corresponding to the command endpoint Pa1 can be calculated.

[0029] If the interference checking device 2 draws an estimated shape of a machined part of a workpiece W after machining based on the advance positions Pb1, an error occurs between the estimated shape of the machined part of the workpiece W in the drawing (for example, the dashed line in a straight line between the advance positions Pb1) and an actual shape of the machined part of the workpiece W after machining (for example, solid line along the command endpoints Pa1), as shown in Fig. Figure 3B shows this error (also referred to as an uncut area R). The uncut area R is an area that is cut from the actual shape of the machined part of the workpiece W after machining, but is incorrectly identified as an uncut area in the estimated shape of the machined part of the workpiece W in the drawing.

[0030] As in Fig. As shown in Figure 3C, cutting along a command path 2 next to the last command path 1 can then be instructed. As shown in Fig. As shown in 3D, when the advance position calculation unit 15 has a advance position Pb2 on the command path 2, which is at time t2 N and the time t2 N+1 Correspondingly, the interference checking device 2 calculates and performs an interference check along a straight line connecting the advance positions Pb2, incorrectly identifies a cutting volume in the uncut area R as equal to or greater than a predetermined value. Thus, the interference checking device 2 incorrectly detects that an interference has occurred between the tool T and the workpiece W, as shown in Fig. 3E is shown. This unintentionally leads to the operation of a machine tool being stopped, even though there is actually no interference between the tool T and the workpiece W.

[0031] In this context, the calculation unit 16 calculates for the uncut area, as in Fig. Figure 4 shows an error between the estimated shape of the machined part of the workpiece W in the drawing (for example, a dashed line in a straight line between the advance positions Pb1) and an actual shape of the machined part of the workpiece W after machining (for example, the solid line along the command endpoints Pa1) as the uncut area R in the estimated shape of the machined part of the workpiece W in the drawing. For example, calculation unit 16 calculates a maximum width W' in the uncut area R.

[0032] More precisely, the calculation unit 16 calculates for the uncut area, as in Fig. Figure 5 shows the direction vectors of motion vi from the calculated forward position Pb1 at time t1. Ncorresponds to the multiple command endpoints Pa1 (for example vi = via = v1 to v6) and a direction of movement vector vi from the calculated forward position Pb1, which corresponds to time t1 N corresponds to the calculated advance position Pb1, which corresponds to time t1 N+1 This corresponds to (for example, vi = vib = v7). The command endpoints Pa1 on the command path 1 can be taken from the preview block command data 21 by the advance position calculation unit 15. The calculation unit 16 for the uncut area converts the movement direction vector v7 from the calculated advance position Pb1, which corresponds to time t1. N corresponds to the calculated advance position Pb1, which corresponds to time t1 N+1corresponds to a unit vector e7 and calculates the absolute value of the outer product of the unit vector e7 and all direction vectors vi (for example v1 to v6), as shown in the following formula, in order to obtain a normal direction offset width wi of each v1 to v6 from v7: wi=|e7×vi|. The calculation unit 16 for the uncut area defines a maximum of the offset widths wi as the maximum width W' in the uncut area R and outputs the maximum width W to the interference checking device 2.

[0033] The interference detection device 2 does not perform interference detection in the uncut area R. In other words, the interference detection device 2 treats the uncut area R as an area not intended for interference detection. This prevents the erroneous detection of interference between the tool T and the workpiece W.

[0034] If an offset width Wp exists between an estimated path based on the calculated advance positions Pb1 on the last command path 1, which is at time t1 N and the time t1 N+1 corresponds to (the dashed line in a straight line between Pb1) and an estimated path based on the calculated advance positions Pb2 on the current command path 2, which corresponds to time t2 N and the time t2 N+1 corresponds to (dashed line in a straight line between Pb2), as in Fig. As shown in Figure 6, if the maximum width W' in the uncut area R, as detected by the computation unit 16 for the uncut area, is equal to or less than the maximum width W', the interference checking device 2 determines, for example, that the current command path 2 passes through the uncut area R. In this case, the interference checking device 2 does not perform any interference checking between the tool T and the workpiece W. The offset width Wp can be a maximum distance between the estimated path based on the advance positions Pb1 (dashed line in a straight line between Pb1) and the estimated path based on the advance position Pb2 (dashed line in a straight line between Pb2). The maximum width W' can also be compensated for by taking a tool shape into account.

[0035] The following refers to Fig. 2 an interference verification process by the interference monitoring device 100 according to the first embodiment is described. Fig. Figure 2 shows a flowchart illustrating the interference verification process by the interference monitoring device 100 according to the first embodiment. (Preprocessing)

[0036] During preprocessing, the instruction analyzer 10 first reads an instruction corresponding to a block from the program 20, converts the read instruction into data in an embodiment, and generates the preview block instruction data 21. The instruction analyzer 10 stores, for example, the preview block instruction data 21 in main memory. (Execution processing)

[0037] During execution processing, the distribution processing unit 11 sequentially reads portions of the preview block command data 21 that correspond to a block. Furthermore, the distribution processing unit 11 acquires an override value through the feed rate override command unit 4. Based on the stroke and velocity of each axis instructed in the read block and the acquired override value, the distribution processing unit 11 calculates a distributed stroke in each distribution cycle, which is passed as a command to a moving part of each axis (a servo motor in each axis) and outputs the calculated distributed strokes to the motion command output unit 12. Finally, the distribution processing unit 11 adds the calculated distributed strokes to the current position directory, thereby updating the current coordinate position.

[0038] The advance position calculation unit 15 calculates the advance position Pb1 on the command path 1, which is determined at time t1. N and the time t1 N+1 This corresponds, based on the current position of the moving part, a specified advance time duration, the preview block command data 21 and the bridging value (%) entered by the feed rate bridging command unit 4, to advance by a predetermined time duration (S11) (see Fig. 4) The calculation unit then calculates 16 for the uncut area, as shown in Fig. 4 and Fig. Figure 5 shows an error between an estimated shape of a machined part of the workpiece W in a drawing (for example, a dashed line in a straight line between the advance positions Pb1) and an actual shape of the machined part of the workpiece W' after machining (for example, a solid line along the command endpoints Pa1) as the uncut area R in the estimated shape of the machined part of the workpiece W in the drawing and calculates the maximum width W' in the uncut area R (S12).

[0039] The interference checking device 2 then calculates, as shown in Fig. Figure 6 shows the offset width Wp between an estimated path based on the calculated advance positions Pb1 on the last command path 1, which is at time t1. N and the time t1 N+1correspond (dashed line in a straight line between Pb1) and an estimated path based on the calculated advance positions Pb2 on the current command path 2, which is at time t2 N and the time t2 N+1 correspond (dashed line in a straight line between Pb2) (S13). The interference checking device 2 determines whether the calculated offset width Wp is equal to or less than the maximum width W' in the uncut area R, which was captured by the computation unit 16 for the uncut area (S14).

[0040] If the offset width Wp is equal to or less than the maximum width W', the interference checking device 2 determines that the current command path 2 should pass through the uncut area R, and the interference checking device 2 does not perform interference checking between the tool T and the workpiece W and does not issue an axis stop command to the motion command output unit 12. In this case, the motion command output unit 12 outputs the distributed strokes (S15), the acceleration / deceleration processing unit 13 performs acceleration / deceleration processing, and the servo control unit 14 issues a command to drive the servo motor 3.

[0041] However, if the offset width Wp is greater than the maximum width W', the interference checking device 2 determines that the current machining operation is taking place in a different area than the uncut area R. The interference checking device 2 then checks for interference between the tool T and the workpiece W at the advance positions Pb2. If a cutting volume is equal to or greater than a predetermined value (if YES in S16), the interference checking device 2 issues an axis stop command to the motion command output unit 12. In response, the motion command output unit 12 stops the output of a motion command (S17) to terminate the command to drive the servo motor 3.If, as a result of performing an interference check between the tool T and the workpiece W at the advance positions Pb2, the interference checking device 2 determines that the cutting volume is smaller than the predetermined value (if NO in S16), the interference checking device 2 does not issue an axis stop command to the motion command output unit 12. In response, the preceding process in step S15 is executed. The preceding process is repeated for each block in the program and in each distribution cycle.

[0042] As previously described, the computation unit 16 in the numerical control 1, according to the interference monitoring device 100 of the first embodiment, calculates an error between the estimated shape of the machined part of the workpiece W in the drawing and the actual shape of the machined part of the workpiece W after machining as the uncut area R in the estimated shape of the machined part of the workpiece W in the drawing. The interference checking device 2 does not perform interference checking in the uncut area R. This makes it possible to prevent a false detection of an interference between the tool T and the workpiece W, even though in reality no interference exists between the tool T and the workpiece W. (Second embodiment)

[0043] In the first embodiment, an erroneous detection of a disturbance between the tool T and the workpiece W was prevented by calculating the maximum width W' in the uncut area R. In a second embodiment, an erroneous detection of a disturbance between the tool T and the workpiece W is prevented by calculating an area S in the uncut area R.

[0044] In a numerical control 1 according to the second embodiment, the computing unit 16 for the uncut area acts and operates differently than the numerical control 1 in Fig. 1. As in Fig. As shown in Figure 8, the computation unit 16 for the uncut area calculates an error between an estimated shape of a machined part of workpiece W in a drawing (for example, a dashed line in a straight line between the advance positions Pb1) and an actual shape of the machined part of workpiece W after machining (for example, a solid line along the command endpoints Pa1) as the uncut area R in the estimated shape of the machined part of workpiece W in the drawing. For example, the computation unit 16 for the uncut area calculates the area S in the uncut area R.

[0045] More precisely, the calculation unit 16 calculates for the uncut area, as in Fig. Figure 9 shows the direction vectors of motion vi from the calculated forward position Pb1 at time t1. Ncorresponds to the multiple command endpoints Pa1 (for example v1 to v6) and a direction of movement vector vi from the calculated forward position Pb1, which corresponds to time t1 N corresponds to the calculated advance position Pb1, which corresponds to time t1 N+1 This corresponds to (for example, v7). The command endpoints Pa1 on the command path 1 can be captured from the preview block command data 21 by the advance position calculation unit 15. The calculation unit 16 for the uncut area receives an area si in a region enclosed by a motion direction vector vi and an adjacent motion direction vector vi+1, as shown in the following formula: si=|vi×vi+1| / 2.

[0046] The calculation unit 16 for the uncut area receives a total sum of the areas si from time t1 N up to time t1 N+1as the area S in the uncut region R, as shown in the following formula, and outputs the obtained area S to the interference checking device 2. S=∑si, where Σ is the sum for i = 1 to 6.

[0047] The interference checking device 2 does not perform interference checking in the uncut area R. In other words, the interference checking device 2 treats the uncut area R as an area not intended for interference checking. This makes it possible to prevent the erroneous detection of interference between the tool T and the workpiece W. For example, if a cut surface Sp is created by traversing an estimated path based on the calculated advance positions Pb2 on the current command path 2 at time t2 N and the time t2 N+1If the area S in the uncut region R, as determined by the computation unit 16 for the uncut region, is equal to or less than the area S in the uncut region R, the interference checking device 2 determines that the current command path 2 should pass through the uncut region R. In this case, the interference checking device 2 does not perform any interference checking between the tool T and the workpiece W. As in Fig. As shown in Figure 10, the cut area Sp can be an area per unit length determined by dividing a cutting volume V by a length L. Alternatively, the cut area Sp can be an average of the areas per unit length. The area S can be compensated or balanced by taking a tool shape into account.

[0048] In the following, an interference verification process is described using an interference monitoring device 100 according to the second embodiment with reference to Fig. 7 described. Fig. Figure 7 shows a flowchart illustrating the interference verification process by the interference monitoring device 100 according to the second embodiment.

[0049] As in the previously described step S11, the advance position calculation unit 15 calculates the advance position Pb1 on the command path 1, which is determined at time t1. N and the time t1 N+1 This corresponds to the current position of a moving part, a defined and calculated advance time duration, the preview block command data 21, and a bridging value (%) entered by the feed rate bridging command unit 4 to advance by a predetermined time duration (S11) (see Fig. 8) The calculation unit then calculates 16 for the uncut area, as shown in Fig. 8 and Fig. Figure 9 shows an error between the estimated shape of the machined part of the workpiece W in the drawing (for example, a dashed line in a straight line between the advance positions Pb1) and an actual shape of the machined part of the workpiece W after machining (for example, a solid line along the command endpoints Pa1) as the uncut area R in the estimated shape of the machined part of the workpiece W in the drawing and calculates the area S in the uncut area R (S22).

[0050] The interference checking device 2 then calculates the cut area Sp along the estimated path based on the calculated advance positions Pb2 on the current command path 2 at time t2. N and the time t2 N+1correspond (S23). The interference checking device 2 determines whether the calculated cut area Sp is equal to or less than the area S in the uncut area R, which was detected by the computation unit 16 for the uncut area (S24).

[0051] If the cut area Sp is equal to or smaller than the area S, the interference checking device 2 determines that the current machining operation is performed in the uncut area R, and the interference checking device 2 does not perform a check for interference between the tool T and the workpiece and does not issue an axis stop command to the motion command output unit 12. In this case, the motion command output unit 12 issues distributed strokes (S15), the acceleration / deceleration processing unit 13 performs acceleration / deceleration processing, and the servo control unit 14 issues a command to drive the servo motor 3.

[0052] If the cut area Sp is larger than the area S, the interference checking device 2 determines that the current machining operation is taking place in a different area than the uncut area R. The interference checking device 2 then checks for interference between the tool T and the workpiece W at the advance position Pb2. If a cutting volume is equal to or greater than a predetermined value (if YES in S16), the interference checking device 2 issues an axis stop command to the motion command output unit 12. In response, the motion command output unit 12 stops the output of a motion command (S17) to terminate the command to drive the servo motor 3.If, as a result of performing an interference check between the tool T and the workpiece W at the advance positions Pb2, the interference checking device 2 determines that the cutting volume is smaller than the predetermined value (if NO in S16), the interference checking device 2 does not issue an axis stop command to the motion command output unit 12. In response, the preceding process in step S15 is executed. The preceding operation is repeated for each block in the program and in each distribution cycle.

[0053] As previously described, the numerical control 1 of the second embodiment can achieve comparable advantages to the first embodiment.

[0054] The present invention is not limited to the embodiments described above, and various changes and modifications can be made to the present invention. For example, the preceding embodiments described a machine tool that moves a tool. However, the features of the present invention should not be limited to this machine tool, but also apply to a machine tool that moves a workpiece.

[0055] The interference monitoring device 100 described in the preceding embodiments checks for interference between a tool and a workpiece in a machine tool. However, the features of the present invention are not limited to this machine tool, but also apply to an interference monitoring device that checks for interference between tools and workpieces in various types of machines, such as industrial machines or industrial robots. 1 Numerical control 2 Interference detection device (noise detection device) 3 servo motors 4. Control unit for overriding the feed rate 10 Command Analysis Unit 11 Distribution processing unit 12 Movement command output unit 13 Acceleration / brake processing unit 14 Servo control unit 15 Advance position calculation unit 16 units of calculation for uncut area 20 Program 21 Preview block command data 100 Interference monitoring device

Claims

[1] An interference monitoring device (100) that checks the interference between a tool and a workpiece in a machine to perform a predetermined machining of the workpiece while the tool and the workpiece are moved relative to each other on the basis of a program (20), the interference monitoring device (100) comprising: an advance position calculation unit (15) which calculates an advance position of the tool or the workpiece by a predetermined period of time based on the program (20); an interference checking unit (2) that draws an estimated shape of a machined part of the workpiece after machining based on the advance position and performs the interference check based on the estimated shape of the machined part of the workpiece in the drawing; and an uncut area calculation unit (16) that calculates an error between the estimated shape of the machined part of the workpiece in the drawing and an actual shape of the machined part of the workpiece after machining as an uncut area in the estimated shape of the machined part of the workpiece in the drawing, wherein the interference checking unit (2) does not carry out an interference check in the uncut area. [2] The interference monitoring device (100) according to claim 1, wherein the uninterrupted area calculation unit (16) calculates a maximum width in the uninterrupted area, and when an offset width between an estimated path based on an advance position on a last command path and an estimated path based on an advance position on a current command path is equal to or smaller than the maximum width in the uninterrupted area, the interference check unit (2) determines that the current command path should pass through the uninterrupted area and does not perform interference check. [3] Interference monitoring device (100) according to claim 2, wherein the calculation unit (16) for the uncut area movement direction vectors via a calculated advance position corresponding to the time t Ncorresponds to a plurality of command positions and calculates a movement direction vector vib from the calculated advance position corresponding to time t N corresponds to a calculated advance position corresponding to time t N+1 corresponds, wherein the plurality of command positions are command positions between the calculated advance position corresponding to the time t N and the calculated advance position corresponding to time t N+1 corresponds, are, the calculation unit (16) for the uncut area converts the movement direction vector vib into a unit vector, the uncut area calculation unit (16) calculates the absolute value of the outer product of the unit vector and each movement direction vector via, thereby obtaining a normal direction offset width of each movement direction vector via to the movement direction vector vib, and the calculation unit (16) for the uncut area defines a maximum of the offset widths as the maximum width in the uncut area. [4] The interference monitoring device (100) according to claim 1, wherein the uncut area calculation unit (16) calculates an area in the uncut area, and when an area of ​​the current machining is equal to or smaller than the area in the uncut area, the interference checking unit (2) determines that the current machining is performed in the uncut area and does not perform interference checking. [5] The interference monitoring device (100) according to claim 4, wherein the uncut area calculation unit (16) calculates movement direction vectors vi from a calculated advance position corresponding to time t Ncorresponds to several command positions and a movement direction vector vi from the calculated advance position corresponding to time t N corresponds to a calculated advance position corresponding to time t N+1 corresponds, wherein the plurality of command positions are command positions between the calculated advance position corresponding to the time t N and the calculated advance position corresponding to time t N+1 corresponds, are, the uncut area calculation unit (16) obtains an area si in an area surrounded by the movement direction vector vi and an adjacent movement direction vector vi+1, and the calculation unit (16) for the uncut area the total sum of the areas si from the time t N until time t N+1 defined as the area in the uncut region.

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