JPH06161527A - Numerical controller - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a numerical control device which generates an alarm when the position of a motor is deviated in a clamped state. [Structure] When the clamped state is confirmed, a difference between the contents of the interruption position register 232 and the pulse encoder 200 is obtained, and if the obtained result exceeds the contents of the judgment value register 230, an alarm is generated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a numerical controller, and more particularly to position control of a servo motor for moving a moving member.

[0002]

2. Description of the Related Art A numerical control device is a device for moving a moving member to a command position commanded by numerical data, and is used in a machine tool, a welding device, an industrial robot, a carrier device, an industrial sewing machine and the like.

In such a numerical controller, feedback control is generally performed to move the moving member to the command position. Therefore, as shown in FIG. 11, the NC controller 210, the axis movement controller 212, the acceleration / deceleration calculator 214, the deviation counter 216, and the speed control circuit 220.
A pulse encoder 200 is provided as a position detector.

The NC control unit 210 reads the NC data transferred to the operation data buffer 160 and issues a movement command including a target position value representing the target position of the work table 12. The axis control unit 212 obtains and outputs a movement amount increment at which the motor should be operated at regular time intervals from the target position value and the movement speed value issued by the NC control unit 210. The acceleration / deceleration calculation unit 214 creates a command pulse signal for accelerating the motor 50, operating it at a constant speed, and decelerating it based on the target position value instructed by the NC control unit 210.
Output to 16. By doing this, work table 1
In order to start and stop 2 with a small impact, the work table 12 can start moving gently and stop gently.

The deviation counter 216 stores the difference between the pulse number of the command pulse signal output from the acceleration / deceleration calculation unit 214 and the pulse number of the feedback pulse signal from the pulse encoder 200 for detecting the position of the motor 50. The speed control circuit 220 drives the motor 50 while speed-controlling the speed of the motor 50 by the voltage converted into an analog signal via the D / A converter 218 based on the content of the deviation counter 216. As a result, the work table 12 becomes the NC control unit 21.
By 0, it is moved to the position designated by the target position value.

Further, in such a numerical controller, the speed control circuit 220 can switch the motor between the locked state and the free state by the switch 224. This switching means turning on and off the power to the servo motor. Here, the locked state is a state in which the servo power is turned on. Specifically, the motor 50 is operated by the deviation counter 21.
6 is a state in which the motor 50 is driven according to the contents of 6 and the free state is a state where the servo power is cut off. Specifically, the motor 50 can freely rotate regardless of the contents of the deviation counter 216.

A clamp device 96 is generally mounted on the rotary shaft of a machine tool or the like, and the motor 50 of the speed control circuit 220 is brought into a locked state and a free state by using a clamp control signal. It is configured to switch.

The reason why the servo power supply is switched in this way is for various reasons. For example, in the servo motor control for driving the 0 ° / 180 ° work table 12 provided in the NC tapping machine, the servo power is switched on and off for the following reason.

The work table 12 of this type has a rectangular shape, and the work is fixed to pallets provided at both ends of the work table 12, and the work table is rotated to 0 ° and 180 ° so that one of the two is provided. Is positioned at the processing position, and the other is positioned at the attachment / detachment position for attaching / detaching the work. Further, the work table 12 is provided with a clamp device 96, which clamps the work table to the housing, so that the work table does not move even if a large force is applied when the work is attached or detached, and the work being processed is not displaced. Is being done.

If the motor 50 is in the locked state with the work table 12 clamped in this way,
If the position of the motor 50 shifts due to an external force including a clamping force or the like, the count value of the deviation counter 216 changes based on the feedback pulse signal from the pulse encoder 200 even though the command pulse signal is not output, and the speed control circuit 220 operates the motor 50 to try to eliminate the change. However, if the external force is stronger, the motor 5
0 cannot return to the original position, the speed control circuit 220 tries to operate the motor 50 with a larger voltage, and the position control is interrupted due to the overload of the motor. Therefore, when the work table 12 is clamped and it is not necessary to rotate the work table 12, the motor 50 is set in a free state so that feedback control is performed even if the motor 50 moves so that overload does not occur. When releasing the clamp, the lock state was used.

[0011]

However, if the force generated during cutting exceeds the clamping force when the motor 50 is set in a free state when processing a work on the work table 12 with a machine tool or the like, the work table is not processed. 12 was rotated and could not be processed accurately.
Further, since the position of the work table 12 is displaced,
After that, there is a problem that defective machining is continued for all the workpieces held on the workpiece table 12.

The present invention has been made to solve the above-mentioned problems, and when the position of a fixed shaft deviates by a predetermined amount or more, an alarm is generated and the occurrence of a defective work piece can be detected promptly. It is an object of the present invention to provide a numerical control device capable of performing.

[0013]

In order to achieve this object, a numerical controller according to the present invention is positioned based on a position detector connected to a servo motor and a position detected by the position detector. A numerical controller comprising a shaft, a fixing means for temporarily fixing the shaft after positioning the shaft, and a servo control means for cutting off power to a servo motor after the shaft is fixed by the fixing means, Storage means for storing the detection value of the position detector at the time when the power supply to the servo motor is cut off by the servo control means, and whether or not the axis has moved while the axis is fixed by the fixing means. Reference value storage means for storing a reference value for determining whether or not the present value obtained from the position detector in the state where the shaft is fixed by the fixing means and the storage value in the storage means A calculation means for calculating the difference between the detected value and the detected value, and an alarm is generated when the difference between the present value calculated by the calculation means and the detected value exceeds the reference value stored in the reference value storage means. And an alarm generating means for generating the alarm.

[0014]

In the numerical controller of the present invention having the above-mentioned structure, when the position detector accurately positions the shaft, the fixing means fixes the shaft, and then the servo control means supplies power to the servo motor. Is cut off, and the detection value of the position detector when the power is cut off is stored in the storage means. Then, the difference between the current value obtained by the position detector and the detection value stored in the storage means in a state where the axis is fixed is calculated by the calculation means calculation, and the calculated current value and detection value When the difference exceeds the reference value stored in the reference value storage means, an alarm is generated by the alarm generation means.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to an NC tapping machine will be described in detail below with reference to the drawings.

FIG. 2 shows an NC tapping machine equipped with a 0 ° / 180 ° rotating work table device 10 (hereinafter abbreviated as work table device 10). The work table device 10 includes a work table 12 that holds a work and rotates by 180 °. The NC tapping machine of the present invention includes a work table device 10 and a processing for processing the work on the work table 12. And a device 14. A drill attached to the processing device 14,
The tool 16 such as a center drill or a tap can be moved to any position in the three-dimensional space. This is because the processing device 14
This is because it has three parts that are movable in the axial direction (direction perpendicular to the paper surface of the drawing), the Y-axis direction (horizontal direction in the drawing), and the Z-axis direction (vertical direction in the drawing).

The movement in the X-axis direction is supported on the carriage 20 by moving the carriage 20 supported by the bed 18 by the X-axis direction drive motor 21 (see FIG. 7). By moving the column 26 by the Y-axis direction drive motor 24, Z
Axial movement is achieved by a spindle head 28 supported by a column 26.
Are moved by the Z-axis direction drive motor 30. Further, the tool 16 is rotated by a spindle drive motor 32 attached to a spindle head 28,
Cut the work. The work table 12 is also provided with a motor built in the work table device 18 if necessary.
Rotate 0 °.

As shown in FIG. 3, the work table device 10 is provided.
The work table 12 has a rectangular shape, and pallets 36 and 38 are provided at both ends in the longitudinal direction. Grooves 40 and 42 for attaching the work directly or via a jig are cut in the pallets 36 and 38, respectively, and the work table 12 is rotated by 180 ° during the work, so that the pallets 36 and 38 are Alternately, they are positioned at the processing position below the processing device 14 and the attachment / detachment position separated from the processing device 14.

As shown in FIG. 4, the work table device 10
Has a table drive motor 50. This motor 5
The rotation of 0 is transmitted to the pinion 58 integrally formed at the tip of the rotary shaft by the engagement of the spur gear 52 mounted on the rotary shaft of the motor 50 and the spur gear 56 mounted on the rotary shaft 54. The rotation is caused by the engagement of the pinion 58 and the large gear 60 (see FIG. 3).
(See).

As shown in FIG. 5, the clamp device 96 is of a friction type in which the rotation of the rotating portion 88 is prevented by the frictional force between the clamp disk 98 attached to the spindle 86 and the housing 68. The clamp disk 98 is fixed to the lower end of the spindle 86 by a bolt 100 and a pin 102, and faces the friction surface 104 formed on the housing 68 with a minute gap. A clamp cylinder 106 is provided behind the clamp disk 98. The clamp cylinder 106 includes a cylinder housing 108 and a clamp piston 110 that is liquid-tightly fitted in the cylinder housing 108 and is movable in the axial direction. The clamp piston 110 is always kept in the retracted position slightly apart from the clamp disc 98 by the return spring 112, but the hydraulic pressure is applied to the hydraulic chamber 114 formed between the clamp piston 110 and the cylinder housing 108. It is advanced by being supplied, and the clamp disc 9
8 is pressed against the friction surface 104.

The hydraulic chamber 114 is provided in the cylinder housing 10.
A liquid passage 116 and a pipe 118 formed in No. 8 are connected to the hydraulic pressure source 120. An electromagnetic directional control valve 122 is provided in the pipe line 118 to connect the hydraulic pressure chamber 114 to the hydraulic pressure source 12
The hydraulic chamber 11 is adapted to be switched between a state in which it is in communication with 0 and a state in which it is in communication with the tank 124.
4 is communicated with the hydraulic pressure source 120. A pressure sensor 126 is provided in the pipeline 118, detects the hydraulic pressure in the hydraulic chamber 114, and outputs an ON signal when the hydraulic pressure in the hydraulic chamber 114 becomes lower than a set value and the clamp is released. When the work table 12 is clamped at a value higher than the set value, an OFF signal is issued.

The NC tapping machine is controlled by the main controller 130 shown in FIG. 6 and the sub controller 132 shown in FIG. The main controller 130 and the sub controller 132 are attached to the bed 18 as shown in FIG. The main controller 130 includes a main CPU 134 and a main RO.
The main component is a main computer 141 having an M136, a main RAM 138, and a bus 140 connecting them, and a keyboard 144, an input device 146, and the like are connected to the bus 140 via an input / output unit 142, and data and signals are transmitted. It is being supplied.

The keyboard 144 is used for inputting an operation program, data and the like, and is provided with a large number of keys such as numeric keys and alphabetic keys. The input device 146 is N
It is a device for inputting C data (operation program including numerical data), and the input is performed by reading NC data punched on a paper tape. A display device 152 and the like are also connected to the input / output unit 142 via the control circuit 150.

An operation data buffer 160 is further connected to the input / output unit 142, and an operation data memory 162 is connected to the operation data buffer 160. The operation data memory 162 stores various operation programs managed by program numbers. The operation program is composed of a series of instruction codes, and a part of the instruction codes stored in the operation data memory 162 is continuously read and stored in the operation data buffer 160 in accordance with a request from the main CPU 134.

The sub-control device 132 is a device for controlling the motor, and like the main control device 130, it mainly includes a sub-computer 180 having a sub-CPU 170, a sub-ROM 172, a sub-RAM 174 and a bus 176 connecting them. is there. The drive circuits 182, 184, 186, 188, 19 are connected to the input / output unit 178 connected to the bus 176.
Drive motors 21, 24, 30, drive motors 21, 24, 30, spindle drive motor 32, table drive motor 50, electromagnetic directional control valve 122, etc. are connected to the respective motors 0, 191, respectively. Encoders 192, 194, 196, 19 for detecting the respective rotation amounts of
8, 200 and the pressure sensor 126 provided on the clamp device 96 of the work table device 10 are connected. The pulse encoders 192-200 are incremental encoders that generate one pulse each time the motor rotates by a certain angle. The detection signal of the pressure sensor 126 is also supplied to the main computer 141.

Main computer 141 and sub computer 1
80, a motor command memory 204, which is shared by the computers 141 and 180, and a reference value register 23.
0 and a shutoff position register 232 are provided to exchange information with each other. In the motor command memory 204, storage areas are separately provided for the five motors 21, 24, 30, 32, 50 controlled by the sub-control device 132, and the target positions of the moving members moved by the motors or Data for instructing the amount of movement, direction, etc. is stored. Further, each storage area is provided with a command execution start flag and a command execution end flag for instructing the start and end of the commanded operation. This command execution end flag serves as a positioning end signal.

The reference value register 230 includes the keyboard 1
A numerical value serving as a judgment reference value is input from 44.

The shut-off position register 232 stores the value of the pulse encoder 200 when the sub computer 180 shuts off the servo power of the table drive motor 50.

In the block diagram of FIG. 1, the parts of the main computer 141 and the sub computer 180 that control the table drive motor 50 for rotating the work table 12 and the clamp device 96 in the work table device 10 are extracted. is there. Then, it demonstrates based on this block diagram.

The same elements as those of FIG. 11 among the elements of FIG. 1 are designated by the same reference numerals.

The NC controller 210 is the main computer 141.
The axis movement control unit 212 and the acceleration / deceleration calculation unit 2
14 and the deviation counter 216 are sub computers 180
It is composed by. The alarm generation circuit 234 is configured by the sub computer 180. When an alarm occurs, the main computer 14 is operated via the motor command memory 204.
1, the alarm message is displayed on the display device 152. The DA converter 218 is composed of the input / output unit 178, and the speed control circuit 220 corresponds to the drive circuit 190.

The NC control unit 210 uses the operation data buffer 1
The NC data transferred to 60 is read and analyzed, converted into internal data that can be executed by a computer, and if the NC data is a rotation command for the work table 12, the target movement position of the work table 12 The rotation command value including the rotation speed is output. Axis movement control unit 212
Is the motor 5 required to execute the rotation command from the target rotation position and rotation speed of the work table 12.
The rotation amount θ and the rotation speed ω of 0 are calculated, distributed, and supplied to the acceleration / deceleration calculation unit 214. The distribution is to obtain the number of distribution command pulses to be supplied to the deviation counter 216 within a certain time Δt in order to achieve the rotation amount θ at the rotation speed ω.

A more specific description will be given. To rotate the table drive motor 50 at the rotation speed ω by θ degrees, Δt
It is necessary to rotate by Δθ (= ω · Δt) degrees for each time, and the command pulse numbers corresponding to θ degrees and Δθ degrees are p (= kθ) and Δp (= kωΔ, respectively).
If it is t), it is decided by distribution to supply Δp command pulses every Δt time, n (= p / Δp) times.

Further, the acceleration / deceleration calculation unit 214 is supplied with the command pulse number kω per unit time and the distribution command pulse number Δp corresponding to the rotation speed ω. Acceleration / deceleration calculation unit 21
4 produces a command pulse signal in response to this and outputs it to the deviation counter 216. However, at the beginning of rotation, the table drive motor 50 is accelerated by a predetermined time constant,
After rotating at a constant speed, a command pulse signal is created to decelerate and stop with the same time constant. That is, at the time of acceleration, a command pulse signal is created so that the pulse output time interval gradually narrows from a wide state and becomes the same as the transmission time interval Δt / Δp at constant speed rotation. The command pulse signal is generated so that

In the deviation counter 216, the acceleration / deceleration calculation unit 2
1 is added every time one command pulse signal is supplied from 14, and 1 is subtracted each time one feedback pulse is supplied from the pulse encoder 200 that detects the rotation amount of the table drive motor 50. Of the speed control circuit 22. The digital value of the difference is stored in the speed control circuit 22 after being converted into an acceleration / deceleration command voltage which is an analog amount by the D / A converter 218.
It is output to 0.

The speed control circuit 220 is a circuit for driving the table drive motor 50 while changing the speed of the table drive motor 50 with a gradient corresponding to the acceleration / deceleration command voltage, and the table drive motor 50 is in a locked state and a free state. A switch 224 that can be switched to and is provided. The switch 224 is controlled by the axis movement control unit 212.

When the switch 224 is in the contact (ON) state, the table drive motor 50 is in a locked state controlled by the speed control circuit 220. The speed of the table drive motor 50 is controlled so that the content of the deviation counter 216 is maintained at an offset value that cancels the offsets of the D / A converter 218 and the speed control circuit 220.

Further, when the switch 224 is in the disconnected (OFF) state, the table drive motor 50 is operated by the speed control circuit 220.
It goes into the free state without being controlled by. This switch 22
No. 4 is turned on when the work table 12 is rotated, and is turned off when the work table 12 is rotated and positioned. This is the work table 12
Is clamped by the clamp device 96, an external force is applied, and when the position is displaced, the switch 224 is turned on.
If so, feedback control is performed, and an attempt is made to return to the original position. However, when the external force is larger, the original position cannot be returned, and a larger current is supplied to the table drive motor 50 to cause overload. Therefore, in order to avoid it, it is not necessary to rotate the work table 12. Therefore, the switch 224 is turned off.

The sub ROM 172 of the sub computer 180 has a work table rotation control routine shown in FIG.
The work table stopping routine shown in is stored.

First, the work table 12 will be described with reference to FIG.
The rotation control will be described.

In the work table rotation control routine, first, in step S1 (hereinafter abbreviated as S1; the same applies to other steps), it is determined whether a work table rotation command is issued. When the instruction code read from the operation data buffer 160 is the rotational positioning of the work table 12, the main computer 141 that functions as the NC control unit 210.
Stores the rotation direction, the target rotation position, the rotation speed, etc. of the work table 12 in the motor command memory 204 and sets the command execution start flag. Therefore, it is determined whether the command execution start flag is set. It is determined whether or not.

If the determination result is YES, S2
After the switch 224 of the speed control circuit 220 is turned on in S, S3 is executed and the clamp of the work table 12 is released. Specifically, the clamp release signal is O
The electromagnetic directional control valve 12 of the clamp device 96 is set to N.
The switching of 2 is performed, the hydraulic chamber 114 is made to communicate with the tank 124, and the clamp is released. When the clamp is released, the signal from the pressure sensor 126 turns ON,
The following steps are performed accordingly. In addition, ON / OFF of the clamp release signal, ON / OFF of the clamp release confirmation signal issued by the pressure sensor 126, and the speed control circuit 2
The time chart of FIG. 10 shows the timing of executing ON / OFF of the switch 224 of 20 and rotation control of the table drive motor 50 (rotational positioning of the work table 12).

After unclamping the work table 12, S4 is executed to position the work table 12. Here, the target rotation position, rotation speed, and rotation direction of the table drive motor 50 are the motor command memory 2
04, the distribution is performed by the function of the axis movement control unit 212 of the sub computer 180, the command pulse signal is generated by the function of the acceleration / deceleration calculation unit 214, and is output to the deviation counter 216. Moreover, the command execution end flag of the motor command memory 204 is reset.

The deviation counter 216 outputs the difference between the number of pulses of the command pulse signal and the number of feedback pulses, and the speed control circuit 220 controls the speed of the table drive motor 50 with an analog voltage according to the contents of the deviation counter 216. To drive. As described above, the acceleration / deceleration calculation unit 214 creates the command pulse signal so that the table drive motor 50 is first accelerated, then is rotated at a constant speed, and is decelerated when stopped. Starts rotation gently and then stops. When the table drive motor 50 rotates by the commanded amount and the positioning of the work table 12 is completed, the command execution end flag of the motor command memory 204 is set.

After the above positioning, the work table 12 is clamped (S5 is executed). Clamp release signal is OF
When set to F, the electromagnetic directional control valve 122 is switched, the hydraulic chamber 114 is connected to the hydraulic pressure source 120 and hydraulic pressure is supplied, and the signal of the pressure sensor 126 is turned off.
When the clamp is completed and the clamp is completed, S6 is executed and the switch 226 of the speed control circuit 224 is turned off.

Then, in S7, the pulse encoder 20
The detected value of 0 is stored in the interruption position register 232, and the execution of the routine ends.

As described above, the work table 12 is unclamped, moved, and clamped. Then, the processing is performed in the clamped state.

Next, the work table 12 will be described with reference to FIG.
The control during the stop will be described.

In the work table stop control routine, it is first determined in S11 whether the work table 12 is stopped. This is done by confirming that the clamp release confirmation signal is OFF. If the determination result is YES, the absolute value of the difference between the current value detected by the pulse encoder 200 and the detection value stored in the cutoff position register 232 in S7 is calculated in S12.

Subsequently, in S13, the absolute value obtained in S12 is compared with the reference value stored in advance in the judgment value register 230.

At this time, in the state where the work table 12 is stopped, the worker has already removed the processed work from the pallet 38 and mounted the unprocessed work, and at the same time, on the other pallet 36. The work is processed by the tool 16. At that time, in milling or the like, when an excessive force is applied in a direction perpendicular to the axis of the tool 16, that is, in the rotation direction of the work table 12, a predetermined amount deviates from the position where the work table 12 is fixed, and the absolute value is If the standard value is exceeded, S13
The determination result of is YES, the alarm is generated by the alarm generation circuit 234 in S14, and the display device 15
At 2, a message indicating a warning is displayed. When an alarm is issued, the main computer 141 issues a stop command to the sub computer 180 via the motor command memory, so that the machine stops and the machining of the work is interrupted thereafter.

The present invention controls the motors other than the table drive motor for driving the work table 12 of the work table device in the NC tapping machine, machine tools other than the NC tapping machine, the carrier device, the industrial robot and the welding device. It can also be applied to numerical control devices such as.

In the present embodiment, the value of the position detector is stored in the interruption position register 232 to determine whether the axis has moved, but the value of the deviation counter 216 may be used.

Further, the timing of alarm generation may be changed as appropriate, such as immediately before the work table rotation command, instead of immediately after the position is displaced.

Further, the present invention is not limited to a rotary type work table, but a linear movement type work table, etc., in which various modifications and improvements are made based on the knowledge of those skilled in the art without departing from the scope of the claims. Can be carried out.

[0056]

As is apparent from the above description, according to the numerical control device of the present invention, when the position of the axis in the fixed state exceeds the reference value, an alarm is generated.
This has the effect of being able to quickly detect the occurrence of defective workpieces.

[Brief description of drawings]

FIG. 1 is a block diagram of a position control portion of the present invention.

FIG. 2 is a side view showing an appearance of an NC tapping machine that is an embodiment of the present invention.

FIG. 3 is a plan view showing a work table device of the NC tapping machine.

FIG. 4 is a plan view showing the work table detached from the work table device and partly in section.

FIG. 5 is a side sectional view of the work table device.

FIG. 6 is a block diagram showing a main controller that controls the NC tapping machine.

FIG. 7 is a block diagram showing a sub control device for controlling the NC tapping machine.

FIG. 8 is a flowchart showing a work table rotation control routine stored in a sub ROM of the sub computer.

FIG. 9 is a flowchart showing a routine for stopping a work table stored in a sub ROM of the sub computer.

FIG. 10 is a time chart of work table rotation control performed according to the work table rotation control routine.

FIG. 11 is a block diagram of a conventional position control portion.

[Explanation of symbols]

 12 work table 50 table drive motor 96 clamp device 130 main control device 132 sub control device 141 main computer 152 display device 180 sub computer 230 reference value register 232 shutoff position register 234 alarm generation circuit

Claims (1)

[Claims] 1. A position detector connected to a servomotor, a shaft positioned based on the position detected by the position detector, a fixing means for temporarily fixing the shaft after positioning the shaft, and A numerical control device comprising a servo control means for cutting off the power supply to the servo motor after the axis is fixed by the fixing means, wherein the position detection is performed at the time when the power supply to the servo motor is cut off by the servo control means. Storage means for storing the detection value of the container, reference value storage means for storing a reference value for determining whether or not the shaft has moved while the shaft is fixed by the fixing means, Calculating means for calculating the difference between the present value obtained by the position detector and the detected value stored in the storage means while the axis is fixed by the means, and the calculating means. Numerical control apparatus characterized by comprising an alarm generation means for generating an alarm when the difference between the calculated the current value and the detected value exceeds the stored reference value to the reference value storing means.