JP2707983B2 - Collision torque control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is applied to machine tools such as lathes, loaders thereof, distribution machines, various industrial machines, etc., and is used to reduce damage when a movable body driven by a motor collides. The present invention relates to a torque control device.

[0002]

2. Description of the Related Art Many machine tools such as lathes are provided with a carry-in / carry-out device such as a gantry loader and are operated automatically by an unmanned person. However, when automation is advanced and a complicated transport device is added, the number of interference points between the transport device and the feed table of the machine tool increases, and a collision may occur.
Therefore, conventionally, as a safety measure in the event of such a collision, an emergency stop at the time of overload has been proposed. That is, when the movable body collides with any obstacle while moving, abnormal torque is generated in the motor, and damage to the machine increases. Therefore, a disturbance torque such as a friction torque is monitored, and when the disturbance torque exceeds a predetermined abnormality determination level, the machine is stopped.

[0003]

However, even when the emergency stop is performed as described above, there is a time lag from when the motor load reaches the abnormality determination level to when the servo stop processing is performed. During that time, the machine will be pressed against the obstacle with the maximum torque, and the damage to the machine will be considerable. If the abnormality judgment level is set to a low value,
Although the effect of preventing damage to the machine is enhanced, the machine may be stopped by a disturbance load that does not lead to a collision, which hinders operation.

An object of the present invention is to provide a collision torque control device which can further reduce damage to a machine at the time of a collision and does not needlessly stop the machine.

[0005]

The structure of the present invention will be described with reference to FIG. 1 corresponding to an embodiment. This collision torque control device includes a load detecting means (22) for a motor (1) that drives a movable body (2), and stops when the load detection value reaches an abnormality determination level (Lb). Abnormal load stopping means (16) for giving the command (h) is provided. In the control device having this configuration, when the load detection value reaches the preparation level (La) set below the abnormality determination level (Lb), the collision preparation means (1) that outputs a torque limit command (s).
8) and a torque control means (12) for limiting the output torque of the motor (1) to a limit level (Lc) in response to the limit command (s).

In the above construction, the collision preparation means (18)
Further, an acceleration / deceleration torque correction means (17) may be provided which makes the load detection value input to the abnormal load stop means (16) a value obtained by subtracting the acceleration / deceleration torque of the motor (1). In addition, it is preferable to provide a mode selection means (15) for controlling a mode in which the collision preparation means (18) functions and a mode in which the collision preparation means (18) does not function.

[0007]

When the movable body (2) collides, the load of the motor (1) increases to move the movable body (2) to the command position. The abnormal load stop means (16) monitors the motor load, and outputs a stop command (h) to stop the motor (1) when the motor load reaches the abnormality determination level (Lb). There is a time delay from the abnormality determination to the start of the stop processing. During this time, the movable table (2) continues to be pressed against the collision target by the motor output. However, the preparation level (La) is set below the abnormality determination level (Lb),
When the load detection value reaches the preparation level (La), the collision preparation means (18) causes the torque control means (12) to limit the torque. Therefore, while the movable body (2) is being pressed against the collision target, the motor output does not increase to the maximum torque and is kept within the limit torque (Lc). Thus, damage to the machine is reduced. Further, at the preparation level (La), only the torque is limited, so that if the motor load does not increase to the abnormality determination level (Lb), the operation is continued as it is, and the abnormality determination level (Lb) is lowered. Unlike the case, useless emergency stop is avoided.

When the acceleration / deceleration torque correction means (17) is provided, when the motor (1) is accelerating or decelerating, a value obtained by subtracting the torque required for the acceleration or deceleration from the load detection value is the preparation level ( La) and the abnormality determination level (Lb). Therefore, the comparison operation is easy, and there is no need to limit the torque of the motor (1) or stop the motor (1) when it is unnecessary due to an erroneous determination. Mode selection means (1
In the case where 5) is provided, the function of the torque limiting means (12) is stopped, for example, when performing control to drive the motor (1) in the retraction direction of the movable body (2) immediately after the stop processing at the time of collision. And pull back with maximum torque. Thereby, damage to the machine can be minimized.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIG. The movable body 2 is composed of a movable portion of a feeder or a loader of a machine tool, and is driven by a motor 1 through a feed screw 3 such as a ball screw. The motor 1 is composed of a servomotor, and is driven via an amplifier 21 by an output of the servo controller 9 of the NC device 5.

The overall control device 4 is a means for controlling the entire machine having the movable body 2, and includes an NC device 5 and a programmable controller 6. The NC device 5 includes a main control unit 8 and a servo controller for each axis. The illustrated servo controller 9 is a unit that controls the servo motor 1. The main control means 8 includes a machining program 7
And outputs the axis feed command of each axis to each servo controller such as the servo controller 9 and outputs the sequence control command to the programmable controller 6. The programmable controller 6 is a device that mainly performs sequence control of the entire machine.

The servo controller 9 is a so-called software servo, and is composed of a control program and a computer device that executes the control program. The servo controller 9 includes a position control unit 10, a speed control unit 11, and a torque control unit 12 for controlling position, speed, and torque in a closed loop, respectively. The loop is a triple loop in the order of torque, speed, and position from the inside. Specifically, the torque control unit 12 includes a limit level setting unit 13,
While monitoring the detection value of the load detection means 22 of the motor 1,
This is a means for limiting the output torque within the level set in the limit level setting unit 13. The load detector 22 is connected to the amplifier 2
1 comprises an ammeter for detecting the current value of a power supply circuit connected to the motor 1, and the load detection value of the analog value is digitized by an A / D converter (not shown) in a loading section to the servo controller 9. Converted to a value. The output of the torque control unit 12 is output to an amplifier 21 for driving the motor 1. The programmable controller 6 includes an abnormal load stopping unit 16, a collision preparation unit 18, an acceleration / deceleration torque correcting unit 17, a pullback commanding unit 14, and a mode selecting unit 1 as means for constituting the collision torque control device.
5 are provided.

The abnormal load stopping means 16 monitors the load detection value of the load detection means 22 via the acceleration / deceleration torque correction means 17, and when the load detection value reaches the set abnormality determination level Lb, the main control means. 8, a stop command h is output, and the pull-back command means 14 is operated.

The collision preparation means 18 has a torque limitation giving judgment means 19 and a torque limitation command means 20. The torque limit applying determining means 19 is provided with the acceleration / deceleration torque correcting means 17.
This is a means for monitoring the load detection value of the load detection means 22 via the. And outputs a level reaching determination signal d to the torque limit command means 20 when the load detection value reaches the set preparation level La. The preparation level La is set to a value smaller than the abnormality determination level Lb. The torque limit command means 20
In response to the determination signal d, the set value of the torque limit level Lc is set in the limit level setting unit 13 in the torque control means 12 of the servo controller 9 and
This is a means for bringing the torque limiting function of the torque control means 12 into a functional state. The torque limit level Lc is set to, for example, 50% of the maximum torque. Note that the abnormality determination level Lb in the abnormal load stop means 16, the preparation level La in the torque limit provision determining means 19, and the torque limit level Lc of the torque limit instructing means 20 are determined by operating a control panel (not shown) or from outside. The value can be set and changed to an arbitrary value by inputting "." The collision preparation means 18 also has a function of releasing the torque limitation by the torque control means 12 when the load detection value does not increase to the abnormality determination level Lb by the set time after reaching the preparation level La.

The acceleration / deceleration torque correction means 17 presets a torque required for acceleration and a torque required for deceleration with a change curve corresponding to the elapsed time from the start of acceleration / deceleration.
This is a means for outputting the set acceleration / deceleration torque as a value subtracted from the load detection value of the load monitoring means 22.
The input of the load detection means 22 to the acceleration / deceleration torque correction means 17 is transmitted through the servo controller 9 and the main control means 8, and therefore, the load detection value is input as a digital value. The pull-back instruction means 14
Immediately after the stop processing of the servo controller 9 by the stop command h of the abnormal load stop means 16, a command is given to the main control means 8 so that the motor 1 rotates reversely for a predetermined time or a predetermined number of revolutions. The mode selection unit 15 is a unit that switches between a mode in which the collision preparation unit 18 functions and a mode in which the collision preparation unit 18 does not function. When the pullback instruction unit 14 operates, the mode is automatically switched to the function stop mode. The mode switching of the mode selecting means 15 is also possible by an operation panel or an external input.

The operation of the above configuration will be described. When the motor 1 attempts to move the movable body 2 at a constant speed for a predetermined distance, an actual torque acts on the motor 1 as shown by a curve a in FIG. This actual torque is a value obtained by adding the disturbance torque b shown in a trapezoidal shape in the same figure and the acceleration torque and the deceleration torque shown by the portions a1 and a3 of the curve a. The disturbance torque b is composed of a friction torque or the like of each part due to the movement of the movable body 22, and has a value that increases and decreases as the speed increases and decreases.

The monitoring by the abnormal load stopping means 16 and the collision preparation means 18 is performed by subtracting the acceleration / deceleration torque from the actual torque by the acceleration / deceleration torque correction means 17 so as to be performed for the disturbance torque b. For the disturbance torque b generated as described above, a value during normal operation is measured and obtained in advance,
In order to exceed the value of the disturbance torque b by a predetermined amount,
The abnormality determination level Lb and the preparation level La are set as constant values as shown in FIG. Preparation level La
Is smaller than the abnormality determination level Lb. Note that the abnormality determination level Lb may be set as a trapezoidal change curve corresponding to a change in the disturbance torque b as shown in FIG. 2. In this case, the abnormality determination level Lb is prepared during acceleration / deceleration. It becomes smaller than the level La.

In the normal operation of the movable body 2, the disturbance torque b, which is the load detection value, does not reach the preparation level La, and the operation is performed without the torque limiting means 12 functioning. When the movable body 2 collides, as shown in FIG. 1B, the load of the motor 1 increases to move the movable body 2 to the command position of the servo controller 9. When the disturbance torque b reaches the preparation level La during this load increasing process, the collision preparation means 18 outputs a determination signal d of exceeding the level, and the torque control means 12 of the servo controller 9
Is set to the functional state. When the disturbance torque b reaches the abnormality determination level Lb, the motor 1 is stopped by a command from the abnormal load stop means 16. At this time, at the time of collision (time t
There is a time lag T2 from 1) to the time (t5) at which the servo stop processing is started. During this time, the state where the movable body 2 is pressed against the collision object by the output of the motor 1 continues.

However, before the time t3 when the abnormality determination level Lb is reached, the torque limiting process has already been started at the time when the preparation level La is reached (t2). Does not increase and is kept within the torque limit level Lc. Therefore, damage to the machine is reduced. In other words, when the torque limitation is not performed, the motor output reaches the maximum torque level Lc and continues for a while as shown by the thick broken line in the figure, but the collision is limited by the torque limitation as described above. The collision energy applied to the object is reduced by the range indicated by the hatching in FIG. Therefore, damage to the machine is reduced. Start of stop processing (t
5) After that, a motor reverse rotation command is given by the pull-back means 14, and the motor 1 stops rapidly and stops after further reverse rotation. Therefore, the deformation of the machine due to the collision is small. At the time of the reverse rotation, the function of the collision preparation means 18 is stopped by the mode selection command of the mode selection means 15, and the torque is limited by the torque limiting means 12 and the pull-back is performed at the maximum torque. Therefore, the effect of preventing deformation by pulling back is sufficiently exhibited, and damage to the machine is further reduced.

FIG. 3 to FIG. 5 show a machine tool with a loader to which the collision torque control device is applied and a control device therefor. As shown in FIG. 4, the machine tool 30 is formed of a two-axis turret type lathe, and the loader 40 is formed of a gantry loader. In the machine tool 30, two headstocks 33, 33 each having a main shaft 34 on a bed 32 are arranged side by side, and slide bases 36, 36 are mounted on both sides thereof via rails 37 so as to be movable laterally (X-axis direction). It was done. Each slide base 36 is provided with a turret carriage 38 (FIG. 5) on which a turret 35 is installed so as to be indexable and rotatable forward and backward (Z-axis direction). Are driven by the X-axis servo motor 1ax (FIG. 5) and the X-axis servo motor 1
az via a feed screw. The turret 35 has various tools 39 mounted on its peripheral surface.

The gantry loader 40 transfers the work W between the work table 46 and the spindle chuck 34, and the lifting rod 41 is moved to a traveling table 49 traveling on a rail 48 via a front-rear moving table 47. It is provided. A loader head 42 is provided at the lower end of the lifting rod 41, and a loader chuck 43 is provided on the front and lower surfaces thereof. The positions of the two chucks 43 are freely interchangeable. Gantry loader 40 travels in the lateral direction (X-axis direction), moves back and forth (Z-axis direction), and moves up and down (Y-axis direction)
Are the X-axis servomotor 1gx (FIG. 3) mounted on the gantry loader 40, the Z-axis servomotor 1gz, and Y
This is performed by the axis servo motor 1gy.

The servomotors 1gx, 1gy, 1gz for each axis of the gantry loader 40 and the servomotors 1a for the left and right turrets 35L, 35R of the machine tool 30.
x and 1az are controlled by the overall control device 50 of FIG.
The overall control device 50 is a control device including the NC device described in FIG. 1 and a programmable controller, and a servo controller (not shown) for each of the axis motors.
have. The overall control device 50 is provided with the collision torque control device 100 of the above embodiment for each of the servomotors 1gx, 1gy, 1gz, 1ax, 1az. In this case, the slide base 36 of the machine tool 30, the turret carriage 38, and the traveling platform 4 of the loader 40
The front and rear movable table 47 and the lifting rod 41 constitute the movable table 2 in the embodiment of FIG.

As described above, by applying the present invention to the machine tool 30 including a two-axis lathe with a loader, the loader 40 and the machine tool 30 have a complicated structure with many interference points.
Driving can be done safely without worrying about damage at the time of collision.

[0023]

According to the present invention, there is provided a control device for emergency stop of a machine when a motor load reaches an abnormality determination level, wherein a preparation level is set below the abnormality determination level. At this point, the collision preparation means activates the torque limiting means so that the motor output does not increase to the maximum torque, so that damage to the machine at the time of collision can be further reduced. Further, at the preparation level, only the torque is limited, so that if the motor load does not increase to the abnormality determination level, the operation is continued as it is, and unnecessary stoppage is avoided. In the case of the invention of claim 2, since the acceleration / deceleration torque correction means is provided, when the motor is accelerated or decelerated, the value obtained by subtracting the torque required for the acceleration / deceleration from the load detection value is equal to the preparation level or the abnormality determination level. Will be compared. Therefore, the comparison operation is easy, and the torque is not limited or stopped when the motor is not necessary due to the erroneous determination. In the case of the third aspect of the present invention, since the mode selection means for controlling the mode in which the collision preparation means functions and the mode in which the collision preparation means does not function is provided, it is possible to perform the pull-back control after the collision of the movable body even if necessary, even after the collision. The maximum torque can be output, thereby minimizing damage to the machine.

[Brief description of the drawings]

FIG. 1A is a block diagram showing a conceptual configuration of an embodiment of the present invention, and FIG. 1B is an explanatory diagram showing a relationship between a load at the time of occurrence of a collision and each set level.

FIG. 2 is an explanatory diagram showing a relationship between the disturbance torque and the acceleration / deceleration torque.

FIG. 3 is a schematic block diagram of a control device of the machine tool with a loader to which the collision torque control device of the embodiment is applied.

FIG. 4 is a front view of the machine tool with the loader.

FIG. 5 is a partial plan view of the machine tool.

[Explanation of symbols]

1: motor, 1ax, 1ay, 1gx, 1gy, 1gz
... Servo motor, 2 ... Movable body, 3 ... Feed screw, 4 ... Overall control device, 5 ... NC device, 6 ... Programmable controller, 8 ... Main control means, 9 ... Servo controller, 12
... torque control means, 14 ... pullback control means, 15 ... mode selection means, 16 ... abnormal load stop means, 17 ... acceleration / deceleration torque correction means, 18 ... collision preparation means, 19 ... torque limit provision determination means, 20 ... torque Limit command means, 22 ... Load detection means, 30 ... Machine tool, 40 ... Gantry loader, 50 ... Overall control device, 100 ... Torque control device at collision, La ... Preparation level, Lb ... Abnormality judgment level, Lc ...
Torque limit level

Claims (3)

(57) [Claims] A detecting means for detecting a load of a motor for driving the movable body; an abnormal load stopping means for stopping the motor when a load detected by the means reaches an abnormal determination level; A collision preparation means for outputting a torque limit command when the load detection value reaches the preparation level set in the above, and a torque control means for restricting the output torque of the motor within the limit level in response to the limit command. When torque control device. 2. The collision torque according to claim 1, further comprising acceleration / deceleration torque correction means for setting a load detection value input to said collision preparation means and abnormal load stop means to a value obtained by subtracting the acceleration / deceleration torque of the motor. Control device. 3. The collision torque control device according to claim 1, further comprising a mode selection unit that controls a mode in which the collision preparation unit functions and a mode in which the collision preparation unit does not function.