JP2002328707A - Numerical controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately operate a skip control function by pressing. SOLUTION: This numerical controller is provided with a torque control part 502 for limiting the load torque of a servo motor 201 to be controlled to a preset value or less, a position deviation value detecting part 506 for detecting the deviation value of the position due to the movement instructing position of the servo motor 201, a torque-over judging part 504 for detecting the torque-over state based on the operation of the torque limiting part 502, and a movement instruction skip processing part 507 for skipping the movement instruction of the servo motor 201 on a condition that the torque-over state is detected by the torque cover judging part 504 when the detected result of the position deviation value detecting part 506 exceeds the preset skip deviation value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a numerical controller (N)
More specifically, the present invention relates to a numerical controller for accurately executing a skip control function of a movement command in an NC machine tool having at least one or more spindles or NC axes. Things.

[0002]

2. Description of the Related Art A numerical control device executes a numerical control process based on a processing program input by a paper tape or the like, and drives a machine tool based on a result of the process to perform a process on a workpiece as instructed.

FIG. 13 is a main block diagram showing a conventional numerical controller. The numerical controller 100 includes a memory 10
1, setting input unit 102, screen processing unit 103, PL
It comprises a C (programmable controller) circuit 104, a machine control signal processing unit 105, an analysis processing unit 106, an interpolation processing unit 107, and an acceleration / deceleration processing unit 108. 110 is a machining program. This processing program 110 is stored in the memory 101 after being read from a tape reader or the like. When the machining program 110 is executed, the machining program 110 is read from the memory 101 one block at a time and analyzed by the analysis processing unit 106. The code analyzed for each block is passed to the interpolation processing unit 107. The interpolation processing unit 107 given the code performs interpolation control, spindle control, auxiliary function control, and the like for each block according to the code. When a command pulse generated by the interpolation control is input, the acceleration / deceleration processing unit 108 performs an acceleration / deceleration process according to a time constant, and then outputs a command pulse to the servo control unit 200 and the spindle control unit 300.

The servo control unit 200 includes an acceleration / deceleration processing unit 10
The NC shaft 202 is driven through a power transmission means 204 such as a gear and a ball screw by controlling the servo motor 201 based on the command pulse given from the controller 8 and the feedback pulse given from the position detector 203. . The spindle control unit 300 includes an acceleration / deceleration processing unit 108
By controlling the spindle motor 301 on the basis of the command pulse given from the controller and the feedback pulse given from the position detector 303, the spindle 302 is driven via power transmission means 304 such as a gear and a belt.

In general, the numerical control device 100 uses a skip control function in correcting a tool length and measuring a position of a work. When a skip signal is input from a sensor or the like on the machine tool side, the skip control function is performed by the interpolation processing unit 10.
7 stops the feed of the servomotor 201 and measures the distance from the start position of the movement command to the stop position, thereby performing tool length correction and work position measurement.
If such a skip control function is used, the position can be detected by a simple command, and the tool length can be corrected.

In a lathe for processing a long work, there is a case where a position is detected by pressing a tail stock against an end face of the work. In a machine tool having two spindles, the position may be detected by pressing a chuck against a work. In these cases, the interpolation processing unit 107 drives the servomotor 201 with the torque control (current limit) of the servo control unit 200 enabled. The interpolation processing unit 107
When a torque limit detection signal is provided from the servo control unit 200, that is, when a signal indicating that the torque limit has been reached is provided from the servo control unit 200, this is detected as a skip signal and subsequent movement is performed. Use the function to stop command output. The same function as that of the servo motor 201 is realized also by detecting the torque limit detection signal during the position control of the main spindle motor 301.

[0007]

By the way, in the numerical controller 100 described above, when the torque limit detection signal from the servo control unit 200 or the spindle control unit 300 is always determined as a skip signal, when the level of the detected current value is small, ,
Due to an unexpected change in the frictional resistance, the NC shaft 202 or the spindle 30
2 may cause a skip stop at an unintended position. If the frictional resistance becomes larger than the torque limit value set as effective, the frictional resistance causes NC
The shaft 202 and the main shaft 302 cannot move,
Or, an abnormal alarm is generated due to an excessive error or the like. Also,
Depending on the time constant and the feed rate when the tail stock is pressed against the end face of the work or the chuck is pressed against the work, the torque generated when the motors 201 and 301 accelerate or decelerate exceeds the torque limit value, and the NC shaft 202 or the spindle 3
02 may be skipped at an incorrect position.

On the other hand, after the detection of the skip signal, the servo motor 201 and the spindle motor 301 only stop moving, and the position deviation remains large. For this reason, when the torque limit is released immediately after the skip stop due to a program error or the like, the NC shaft 202 and the main shaft 302 move largely to reduce the position deviation amount, and, for example, bite into the work. For example, there is a risk of damaging the machine tool. Further, there is no means for easily recognizing the frictional resistance of the NC shaft 202 or the main shaft 302, and it is difficult to instruct a torque limit value in consideration of the frictional resistance. Further, for example, if the pressing center position is shifted when the tail stock is pressed, the tail stock is returned to perform fine adjustment of the center position,
The pressing operation must be performed again, and the operation becomes extremely complicated.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide a numerical controller capable of accurately performing a skip control function by pressing. Furthermore, to obtain a numerical control device capable of obtaining a numerical control device capable of preventing a situation in which a machine tool is damaged after the completion of the skip control function by pressing, a torque limit value in consideration of static friction resistance is set. It is an object of the present invention to obtain a numerical control device capable of giving a command, and to obtain a numerical control device capable of easily performing centering adjustment work even when the center position is shifted.

[0010]

In order to achieve the above object, a numerical controller according to the present invention comprises: a torque limiting unit for limiting a load torque of a rotary actuator to be controlled to a predetermined value or less; Position deviation amount detection means for detecting a deviation amount of the position of the actuator from the movement command position, and torque over determination means for detecting a torque over state based on the operation of the torque limiting means;
A movement command skip means for skipping a movement command of the rotary actuator on condition that the torque over determination means has detected a torque over state when a detection result of the position deviation amount detection means exceeds a preset skip deviation amount; And the following.

According to the present invention, when the torque over judging means judges that the torque is over, and when the position deviation exceeds the skip deviation, the movement command skipping means sends the movement command of the rotary actuator. Skipped.

[0012] In the numerical control device according to the next invention, in the above invention, the torque over determination means may be in a torque over state when the number of times of operation of the torque limiting means during a predetermined period exceeds a predetermined threshold value. Is detected.

According to the present invention, when the number of times of operation of the torque limiting means exceeds a predetermined threshold value during a predetermined period, it is determined that the torque is over.

In the numerical control device according to the next invention, in the above invention, the torque over determination means may be in a torque over state when the predetermined number of operations of the torque limit means reaches within a predetermined time. It is characterized by detecting.

According to the present invention, when the predetermined number of times of operation of the torque limiting means is reached within a predetermined time, it is determined that the torque is over.

In the numerical control device according to the present invention, in the above invention, after the movement command is skipped by the movement command skip means, the deviation amount of the position detected by the position deviation amount detection means is equal to or less than a predetermined value. It is characterized by further comprising a correcting means for correcting the movement command position in order to achieve the above.

According to the present invention, after the movement command is skipped by the movement command skip means, the movement command position is corrected by the correction means, and the amount of deviation of the position becomes equal to or less than a predetermined value.

A numerical controller according to the next invention performs an acceleration / deceleration process on the movement command of the rotary actuator and outputs the acceleration / deceleration process as a new movement command. Acceleration / deceleration processing determining means for detecting that the rotary actuator is performing acceleration / deceleration processing based on a comparison between the movement command to be performed and a new movement command output from the acceleration / deceleration processing unit, When the acceleration / deceleration processing determination means detects that the acceleration / deceleration processing is being performed, the torque over state is not detected regardless of the operation of the torque limiting means.

According to the present invention, when the acceleration / deceleration processing determining means detects that the acceleration / deceleration processing is being performed, the torque over determination means does not detect the torque over state regardless of the operation of the torque limiting means.

The numerical control device according to the next invention is the numerical control device according to the above invention, wherein the load torque of the rotary actuator limited by the torque limiting means is reduced from a state in which the positional deviation detected by the positional deviation detecting means is increased. Is gradually increased, and a static friction load torque estimating means for estimating a static friction load torque based on a change in the position deviation amount detected by the position deviation amount detecting means is provided.

According to the present invention, the static friction load torque is estimated when the position deviation detected by the position deviation detector changes from the state in which the position deviation is increased.

The numerical controller according to the next invention is the numerical control device according to the above invention, wherein a maximum torque setting means for setting a maximum load torque serving as a limiting reference of the torque limiting means, and a maximum load set by the maximum torque setting means. An alarm determining unit that outputs an alarm when the torque does not reach the static friction load torque estimated by the static friction load torque estimating unit.

According to the present invention, an alarm is output when the maximum load torque set by the maximum torque setting means does not reach the static friction load torque estimated by the static friction load torque estimation means.

The numerical controller according to the next invention is the numerical control device according to the above invention, wherein a second rotary actuator for driving a second shaft member orthogonal to the first shaft member driven by the rotary actuator is controlled. A second torque limiting means for limiting a load torque of the second rotary actuator to a predetermined value or less, and a second position deviation for detecting a positional deviation amount of the second rotary actuator from a movement command position. When the second torque limiter is actuated, reference is made to a detection value of the second position deviation detector, and a follow-up of a movement command is performed so that the detected value is equal to or less than a preset value. And a follow-up means for performing.

According to the present invention, when the torque is limited, the movement command is followed up so that the deviation amount of the position related to the second rotary actuator becomes equal to or less than a preset value.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a numerical control device according to the present invention will be described below in detail with reference to the accompanying drawings.

Embodiment 1 FIG. 1 is a block diagram showing a main configuration of a numerical control device according to Embodiment 1 of the present invention. In FIG. 1, reference numeral 501 denotes a maximum torque setting means;
02 is a torque limiter, 503 is a torque limit detector, 50
Reference numeral 4 denotes a torque over determination unit; 505, a skip deviation amount setting unit; 506, a position deviation amount detection unit; 507, a movement command skip processing unit; 508, a skip coordinate correction unit; The same components as those of the numerical control device 100 shown in FIG. 13 are denoted by the same reference numerals, and description thereof is omitted.

The interpolation pulse processed by the interpolation processing unit 107 is given to the servo control unit 200 via the acceleration / deceleration processing unit 108. The acceleration / deceleration processing unit 108 performs acceleration / deceleration processing on the interpolation pulse according to a time constant set by a parameter, for example, as shown in FIG. 2, and outputs the pulse to the servo control unit 200 as a position command pulse train. The servo control unit 200, to which the position command pulse train is input from the acceleration / deceleration processing unit 108, controls the position command pulse train and the position detector 20.
The position of the servo motor 201 is controlled on the basis of the feedback pulse given from the controller 3, and the NC shaft 202 is driven via power transmission means 204 such as a gear and a ball screw, for example, as in the conventional motor shown in FIG. At this time,
The torque limiting unit 502 limits the upper limit of the motor output torque according to the torque limit value set by the maximum torque setting unit 501.

When the torque is limited by the torque limiting unit 502 due to pressing against a pressing interference object such as a tail stock or a chuck, that is, the servo motor 201 is pressed.
When the torque reaches the torque limit value, the torque limit detection unit 503 detects this, and outputs a torque limiting signal to the torque over determination unit 504. The in-acceleration / deceleration processing determination unit 509 compares the interpolation pulse, which is an input pulse to the acceleration / deceleration processing unit 108, with the position command pulse, which is an output pulse from the acceleration / deceleration processing unit 108, and determines whether the acceleration / deceleration processing is in progress. It is determined whether or not there is, and the determination result is given to the torque over determination unit 504. Specifically, as shown in the flowchart of FIG. 3, the output pulse / input pulse is calculated (step S301), and the output pulse / input pulse> K
If K is the determination value ≒ 1, it is determined that the vehicle is in a steady state (step S302). On the other hand, if output pulse / input pulse ≦ K, it is determined that acceleration / deceleration is being performed (step S303).

The torque over determining section 504 determines whether or not the torque is over based on the torque limiting signal provided from the torque limiting detecting section 503 and the determination result provided from the acceleration / deceleration processing determining section 509.

FIG. 4 shows the above-mentioned torque over judgment section 50.
6 is a flowchart illustrating an operation example of FIG. In the torque over determination unit 504, a predetermined sampling period t (ms)
Monitor the state in which the torque is being limited, and sample the history of the state up to the number of sampling data N1 times.
That is, the history of the state in the past (t × N1) time (ms) is recorded. In step S201, the torque-over determination unit 504 checks the torque-over determination method instructed in the machining program, and proceeds to step S202 in the case of the torque-limit detection-times designation method. To step S203, and in the case of the normal method, the procedure proceeds to step S204.

In the torque limit detection frequency designation method, the number N1 of sampling data for judging torque over is set to a fixed value T1, and the detection frequency upper limit value N2 in the torque limiting state is set to a variable value P1 according to a command (step S1). S202). The upper limit N2 of the number of times of detection in the torque limiting state is a threshold for determining that the torque is over when the number of times of torque limitation generated during the number N1 of sampling data reaches this value.

In the torque limit determination time designation method, the number N1 of sampling data is set to a variable value T2 according to a command, and the upper limit value N2 of the number of detections in the torque limiting state is set to a fixed value P1 (step S203). Variable value T2
Sets the check time specified by the machining program to T (m
s), it can be calculated by T2 = T / t.
In the normal method, the number of sampling data N1 and the upper limit N2 of the number of times of detection in the torque limiting state are both fixed values 1.
Is set (step S204).

In each method, the number N1 of sampling data and the upper limit N of the number of times of detection in the torque limiting state are set.
When 2 is set, the sampling data of the number of sampling data N1 is read (step S205), and thereafter, it is determined whether or not the torque limit has occurred equal to or more than the upper limit value N2 of the number of detections in the torque limiting state (step S20).
6). If the result of the determination in step S206 is that the torque limit is less than the upper limit N2 of the number of times of detection, it is determined that the torque is not over (step S207), and the procedure ends. On the other hand, if the result of the determination in step S206 indicates that the torque limit is equal to or greater than the upper limit N2 of the number of times of detection, it is determined whether the acceleration / deceleration processing is being performed by further referring to the determination result from the acceleration / deceleration processing determination section 509. Is determined (step S208). If the determination result of the acceleration / deceleration processing determination unit 509 is not the acceleration / deceleration processing, it is determined that the torque is over (step S20).
9), end the procedure. On the other hand, even if the torque limit is equal to or greater than the detection count upper limit N2, if the determination result of the acceleration / deceleration processing determination section 509 is during acceleration / deceleration processing, the procedure ends without determining that torque is over.

The movement command skip processing section 507 of the interpolation processing section 107 compares the skip deviation amount set by the skip deviation amount setting section 505 with the actual position deviation amount detected by the position deviation amount detection section 506. If the position deviation amount exceeds the skip deviation amount, the torque over judgment unit 50
Under the condition that it is determined that the torque is over in 4, the machine position at that time is stored as a skip position,
Stop the axis movement command pulse output immediately. The machine position at the time when a predetermined condition is satisfied is stored as the skip position. The stored skip position can be read by a variable command or the like in the machining program, and can be used for, for example, measurement of a tool length. That is, the tool length can be obtained from the difference between the movement start position and the skip position. Further, it can be used to calculate the correction amount from the measured tool length.

After storing the skip position, it is necessary to return from the state in which the torque is limited by the torque limiting unit 502 to a state in which normal full torque can be output. Here, when the torque limitation is released while the position deviation amount is increasing due to the pressing, torque is suddenly generated by the increased position deviation amount, which may cause a failure such as damage to the machine tool. There is. Therefore, in the numerical control device according to the first embodiment, the skip coordinate correcting unit 508 of the interpolation processing unit 107 corrects the command position at the time of skip stop to prevent the above situation. More specifically, the skip coordinate correcting unit 508 generates a command pulse in a direction in which the position deviation amount detected by the position deviation amount detection unit 506 becomes zero, and issues a command so that the position deviation amount becomes a predetermined value or less. Correct the position. As a result, even when the torque limited by the torque limiting unit 502 is returned to a state where normal full torque can be output, there is no possibility of causing trouble such as damage to the machine tool.

FIGS. 5 and 6 show examples of a machine tool controlled by the above numerical control device. Figure 5
6 shows a machine tool for measuring the center hole position of the work W using the skip control function by pressing the tail stock 1000. FIG. 6 shows a skip control function by pressing the chuck 1101 attached to the rear headstock 1100. 1 shows a machine tool for measuring the position of a workpiece W using the above-described method.

FIG. 7 is an example of a machining program for a pressing skip command. In FIG. 7, "G" described in the first line
0X0. Z-5. In the command block "", the positioning to the pressing start position is performed.
Positioning is performed at the position of the axis -5 mm. In the example of FIG. 5, positioning is performed such that the tip of the tail stock 1000 is located at the center of the work W. In the example of FIG. 6, the center of the rear headstock 1100 is positioned at the front spindle. Positioning is performed so as to match the center 1200.

Next, "G160Z2" described in the second line
0. Q30D5. A command block of F500 ″ indicates a pressing skip command, in which a pressing command is performed with a torque limit value of 30% (address Q) and a skip deviation amount of 5 mm (address D). 2
When the movement to the position of 0 mm is performed and the skip condition is satisfied on the way, the subsequent movement is skipped.

Next, "# 100 = #" described in the third line
In the command block of 5061 ", the variable (# 100)
The coordinate value at which skipping is stopped (# 5061) is substituted. In the case of the example of FIG.
In the example of FIG. 6, the position where the rear end of the work W is gripped by the back chuck 1101 is the coordinate value of the skip stop.

FIGS. 8 (a) to 8 (c) are graphs showing temporal changes in the command speed, torque and position deviation when the above-described skip command is executed. With the skip command, the shaft is moved while appropriately accelerating and decelerating in a state where the torque limit is set, and when the shaft is pressed against the interfering object (t0), the positional deviation increases thereafter. In the case of the example of FIG. 5, it is after the tip of the tail stock 1000 has pressed into the center hole of the work W, and in the case of the example of FIG.
This corresponds to the time after the sheet 101 is pressed.

When the above-mentioned state is continued, the positional deviation amount is sequentially increased by the pressing, and the torque is increased, so that the torque is soon limited (t1). If the torque over determination unit 504 determines that the torque is over and the position deviation amount exceeds the skip deviation amount in this state (t2), the interpolation process stops thereafter, and the movement command pulse output stops. Thereafter, the command position is corrected by the skip coordinate correcting unit 508, and the position deviation amount is canceled. In the case of the example of FIG. 5, the tip of the tail stock 1000 is located at the depth of the center hole of the work W, and in the case of FIG. 6, the position of the back chuck 1101 is the corrected command position. With the position deviation cancelled,
The torque limitation is released, and the pressing skip command is completed.

As described above, according to the above numerical control device, when the torque over determination unit 504 determines that the torque is over, and when the position deviation exceeds the skip deviation, the value at that time is determined. Since the mechanical position is stored as the skip position and the output of the axis movement command pulse is stopped immediately, the skip control function by pressing can be performed accurately.
In addition, when the acceleration / deceleration processing determination unit 509 determines that the acceleration / deceleration processing is being performed, the torque limit is set to the detection number upper limit N
Even if it is two or more, it is not determined that the torque is over, so there is no possibility that the NC shaft 202 will skip and stop at an incorrect position, and the skip control function can be performed more accurately. Further, after the skip position is stored, the skip coordinate correcting unit 508 generates a command pulse in a direction in which the position deviation amount detected by the position deviation amount detection unit 506 becomes zero, and the position deviation amount becomes a predetermined value. Since the command position is corrected so as to be as follows, even if the torque limited by the torque limiting unit 502 is returned to a state where normal full torque can be output, malfunctions such as damage to the machine tool may be prevented. There is no danger of bringing. Further, when the number of times of operation of the torque limiting unit 502 exceeds a predetermined threshold during a predetermined period, or when the number of times of operation of the predetermined torque limiting unit 502 reaches within a predetermined time, it is determined that the torque is over. Therefore, there is no fear that an unexpected change in the frictional resistance may cause the NC shaft 202 to skip at an unintended position.

Embodiment 2 Next, a second embodiment of the present invention will be described. FIG. 9 is a flowchart showing a processing procedure of the static friction load torque estimating means provided in the numerical control device according to the second embodiment of the present invention. The static friction load torque estimating means is provided in the maximum torque setting means 501 in the numerical control device shown in FIG.

First, the static friction load torque estimating means sets the torque limit of the shaft to be measured to 0% (step S501). Next, a movement command pulse is given to the measurement target axis by an increment value, and the position deviation amount is increased (step S502).

Next, the torque limit value is increased by 1% (step S503). The rate of increasing the torque limit value does not necessarily need to be 1%, but may be increased by another value (for example, 5%) in accordance with the estimation accuracy of friction.

Next, it is checked whether or not the positional deviation amount ≒ 0 (step S504). If the positional deviation amount is not ≒ 0, the process returns to step S503, and the process of sequentially increasing the torque limit value is repeated.

On the other hand, when the axis to be measured moves and the feedback position changes and the positional deviation becomes ≒ 0, it is estimated that the torque limit value at that time is the static friction load torque, and this is stored in the memory. (Step S505).

FIG. 10 is a flowchart showing a procedure of an alarm judgment performed by the alarm judging means in response to the pressing skip command as shown in the first embodiment from the load torque estimated by the frictional load torque estimating means. . It should be noted that this alarm determination means is also described in FIG.
In the numerical control device shown in FIG.
1 is provided.

In this alarm determination, first, the static friction load torque estimated by the static friction load torque estimating means is read (step S601), and then the torque limit value described in the pressing skip command is read (step S602).

The alarm judging means which has read out the static friction load torque and the torque limit value of the pressing skip command compares the two (step S603), and when the torque limit value of the pressing skip command exceeds the static friction load torque, Ends the procedure as it is.

On the other hand, if the torque limit value of the pressing skip command is lower than the static friction load torque, sufficient torque for moving the shaft cannot be given, so that an alarm is output by the alarm determining means. (Step S604).

As described above, according to the numerical control device for estimating the static friction load torque, it is checked in advance from the estimated static friction load torque whether an improper value is specified in the pressing skip command. This makes it possible to accurately perform the skip control function by pressing.

Embodiment 3 FIG. Next, a third embodiment of the present invention will be described. Third Embodiment In a third embodiment, a numerical control device will be described in order to accurately execute a movement command skip control function in a machine tool having a follow-up axis orthogonal to the NC axis in addition to the NC axis that issues a pressing skip command. I do.

FIG. 11 is a block diagram showing a main configuration of a numerical control device according to Embodiment 3 of the present invention. As is clear from the figure, this numerical control device is different from the numerical control device of the first embodiment shown in FIG. 1 in that the position command follow-up processing section 700, the maximum torque setting means 701 of the follow-up shaft, Up shaft torque limiter 7
02, a follow-up axis position deviation amount detection unit 703 and a servo control unit 800 dedicated to the follow-up axis are added.

When the numerical control device issues a skip command for pressing the NC axis, the torque limiting section 702 always limits the torque on the follow-up axis. The position deviation amount generated at the time of torque limitation is detected by the position deviation amount detection unit 703 and provided to the position command follow-up processing unit 700. The position command follow-up processing section 700 to which the position deviation amount is given, sets the position deviation amount to 0.
Follow up the position command so that

FIG. 12 shows an example of a machine tool controlled by the numerical controller according to the third embodiment. The center hole position of the work W is measured using a skip control function by pressing the tail stock 1000. 1 shows a machine tool for performing the following.

NC axis 202 for performing pressing skip command
Moves in the direction of the workpiece in response to a movement command. When the blade edge of the tailstock 1000 is pressed against a position slightly deviated from the center hole of the work W, stress acts in the follow-up axial direction. However, since the torque of the follow-up shaft is being limited, the follow-up shaft moves in the direction of the center of the work, under the stress. At this time, the command position of the follow-up axis is subjected to follow-up processing and becomes the position after the movement. By repeating the above, the blade edge of the tail stock 1000 reaches the innermost part of the center hole.

According to such a numerical controller, for example,
When the workpiece W is grasped from the back, even if the center is slightly shifted, the center can be adjusted by the action of the torque-limited follow-up shaft.
The work of adjusting the center of the tail stock 1000 can be performed in a short time.

[0060]

As described above, according to the present invention, when the torque over determination means determines that the torque is over, and when the position deviation exceeds the skip deviation, the movement command skip is performed. Since the movement command of the rotary actuator is skipped by the means, there is an operational effect that the skip control function by pressing can be accurately performed.

According to the next invention, when the number of times of operation of the torque limiting means exceeds a predetermined threshold value in a predetermined period, it is determined that the torque is over. Therefore, depending on an unexpected change in the frictional resistance, the movement command of the rotary actuator is skipped. The skip control function by pressing can be performed more accurately.

According to the next invention, when the predetermined number of actuations of the torque limiting means has been reached within a predetermined time, it is determined that the torque is over. Therefore, depending on an unexpected change in the frictional resistance, the movement command of the rotary actuator is determined. Is not skipped, and the skip control function by pressing can be performed more accurately.

According to the next invention, the movement command position is corrected by the correction means after the movement command is skipped by the movement command skip means, and the deviation amount of the position becomes a predetermined value or less. Even when the applied torque is returned to a state where a normal full torque can be output, there is no possibility that the machine tool may be damaged or other troubles.

According to the next invention, when the acceleration / deceleration processing determining means detects that the acceleration / deceleration processing is being performed, the torque over determination means does not detect the torque over state regardless of the operation of the torque limiting means. For example, even if the torque during acceleration / deceleration increases when the time constant is shortened, the skip control function can be accurately performed without being affected by the increase.

According to the next invention, the static friction load torque is estimated when the position deviation detected by the position deviation detecting means changes from the state in which the position deviation is increased. A torque limit value can be set in accordance with the static friction load torque.

According to the next invention, when the maximum load torque set by the maximum torque setting means does not reach the static friction load torque estimated by the static friction load torque estimating means, an alarm is output, so that the rotary actuator is driven. It can be determined previously whether the machining program is normal.

According to the next invention, when the torque is limited, the movement command is followed up so that the deviation amount of the position related to the second rotary actuator becomes equal to or less than a preset value. Even when the center is slightly deviated when the workpiece is gripped from the back, the centering can be performed by the action of the torque-limited follow-up shaft, so that the centering adjustment operation can be performed in a short time.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a main configuration of a numerical control device according to a first embodiment of the present invention;

FIG. 2 is a block diagram showing an extracted portion of an acceleration / deceleration process in the numerical controller of FIG. 1;

FIG. 3 is a flowchart illustrating the operation of a determination section during acceleration / deceleration processing.

FIG. 4 is a flowchart illustrating an operation of a torque over determination unit.

FIG. 5 is a conceptual diagram of a main part of a machine tool showing a state in which a center hole position of a work is measured using a skip control function by pressing a tail stock.

FIG. 6 is a conceptual diagram of a main part of a machine tool that measures a position of a work by using a skip control function by pressing a chuck attached to a rear headstock.

FIG. 7 is a diagram illustrating an example of a machining program of a pressing skip command.

FIGS. 8A to 8C are graphs showing temporal changes in a command speed, a torque, and a position deviation amount when a skip command is executed.

FIG. 9 is a flowchart showing a processing procedure of a static friction load torque estimating means provided in the numerical control device according to the second embodiment of the present invention.

FIG. 10 is a flowchart showing a processing procedure of an alarm judgment performed by the alarm judgment means in the pressing skip command as shown in the first embodiment from the load torque estimated by the friction load torque estimation means.

FIG. 11 is a block diagram illustrating a main configuration of a numerical control device according to a third embodiment of the present invention.

FIG. 12 is a conceptual diagram showing an example of a machine tool controlled by a numerical control device according to a third embodiment of the present invention.

FIG. 13 is a main block diagram showing a conventional numerical control device.

[Explanation of symbols]

100 Numerical control device, 101 memory, 102 setting input unit, 103 screen processing unit, 104 PLC circuit, 1
05 Machine control signal processing unit, 106 analysis processing unit, 10
7 interpolation processing unit, 108 acceleration / deceleration processing unit, 110 machining program, 200 servo control unit, 201 servo motor, 202 NC axis, 203 position detector, 204
Power transmission means, 300 spindle control section, 301 spindle motor, 302 spindle, 303 position detector, 304 power transmission means, 501 maximum torque setting means, 502 torque limit section, 503 torque limit detection section, 504 torque over determination section, 505 skip Deviation amount setting means, 50
6 position deviation amount detection unit, 507 movement command skip processing unit, 508 skip coordinate correction unit, 509 acceleration / deceleration processing determination unit, 700 position command follow-up processing unit, 7
01 Maximum torque setting means, 702 Torque limiter, 7
03 Position deviation amount detection unit, 800 Servo control unit, 10
00 tailstock, 1100 rear headstock, 110
1 Back chuck, 1200 spindle center.

Claims (8)

[Claims] 1. A torque limiting means for limiting a load torque of a rotary actuator to be controlled to a predetermined value or less; a position deviation detecting means for detecting a deviation of a position of the rotary actuator from a movement command position; A torque over determination unit that detects a torque over state based on the operation of the torque limiting unit; and a torque over determination unit that detects the torque over state when the detection result of the position deviation amount detection unit exceeds a preset skip deviation amount. And a movement command skip means for skipping a movement command of the rotary actuator on the condition that the rotation control is performed. 2. The torque-over determining means according to claim 1, wherein the torque-over determining means detects the torque-over state when the number of operations of the torque limiting means during a predetermined period exceeds a predetermined threshold. Numerical control device. 3. The torque-over determining unit according to claim 1, wherein the torque-over determining unit detects that the torque is over when the predetermined number of operations of the torque limiting unit reaches within a predetermined time. Numerical control unit. 4. A correction means for correcting a movement command position so that a deviation amount of a position detected by the position deviation amount detection means is reduced to a predetermined value or less after the movement command is skipped by the movement command skip means. The numerical control device according to claim 1, further comprising: 5. An acceleration / deceleration processing unit that performs acceleration / deceleration processing on a movement command of the rotary actuator and outputs the acceleration / deceleration processing as a new movement command; a movement command input to the acceleration / deceleration processing unit and the acceleration / deceleration. An acceleration / deceleration processing-in-progress determination means for detecting that the rotary actuator is in acceleration / deceleration processing based on a comparison with a new movement command output from the processing section. 5. The method according to claim 1, wherein when it is detected that the vehicle is in the deceleration process, the torque over determining means does not detect the torque over state regardless of the operation of the torque limiting means.
Numerical control apparatus according to any one of the above. 6. A load torque of a rotary actuator limited by said torque limiting means is gradually increased from a state in which the position error detected by said position error detecting means is increased, and said position error detecting means detects said position error. 2. A static friction load torque estimating means for estimating a static friction load torque based on a change in the positional deviation amount.
6. The numerical control device according to any one of items 5 to 5. 7. A maximum torque setting means for setting a maximum load torque serving as a limiting reference of the torque limiting means, and a maximum load torque set by the maximum torque setting means is a static friction load estimated by the static friction load torque estimation means. The numerical control device according to claim 6, further comprising: alarm determination means for outputting an alarm when the torque does not reach. 8. A second rotary actuator for driving a second shaft member orthogonal to the first shaft member driven by the rotary actuator is to be controlled, and a load torque of the second rotary actuator is set in advance. A second torque limiter that limits the value to a value equal to or less than a set value, a second position deviation amount detector that detects a position deviation amount with respect to a movement command position of the second rotary actuator, and a second torque limiter. And a follow-up means for referring to a detection value of the second position deviation amount detection means when activated, and performing a follow-up of a movement command so as to make the value equal to or less than a preset value. The numerical control device according to claim 1.