JP2011118840A - Numerical control device having motor load torque measuring function - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a numerical control device having a motor load torque measuring function, by which a tool as a measurement target of load torque, a motor, and a measurement part are automatically decided based on an instruction of a processing program in operation and measurement of the load torque for each tool can be carried out without changing the processing program. <P>SOLUTION: Whether tool exchange is instructed is determined, and when the tool exchange is instructed, a tool to be measured is decided. Whether cutting action is instructed is determined, and a servo motor of a feed shaft is decided (SA100-SA103). Whether movement of the feed shaft is started is determined, and load torque measurement on each of motors is carried out, and measurement data of the load torque are recorded to a record memory (SA104-SA106). The measurement and recording of the load torque is performed until the movement of the feed shaft is finished, and processing is finished when the program is finished (SA107-SA109). <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a numerical control device that controls a machine tool, and more particularly to a numerical control device having a motor load torque measurement function.

  In a machine tool controlled by a numerical control device, a machining load is measured in order to detect breakage of a tool during machining of a workpiece and arrival of a tool life. Since the load torque during machining changes depending on the type of tool, the state of wear, and the machining operation, it is necessary to measure each tool and every machining operation.

  Patent Document 1 has an effect that it is very easy to set an automatic monitoring section of a machining load at the time of workpiece machining, and an upper limit value (damage value) of the machining load can be easily set without error. In addition, since the graph display of the processing load on the monitor is updated and displayed every time the tool is changed, the load fluctuations for each tool can be viewed in more detail by the operator. A technique that can more easily and reliably monitor the state is disclosed.

  In Patent Document 2, the load torque of the servo motor of the feed shaft that is automatically driven by the positioning operation is measured during the positioning operation, the sequence number is specified, and a block that does not measure the load torque even in the positioning operation is selected. In addition, there is disclosed a technique of a numerical control device capable of selecting only a block suitable for detecting the degree of wear as a load torque indicating wear or the like of a movable portion of a feed shaft.

  Patent Document 3 discloses a technique of a processing load monitoring method that can accurately compare temporally the sampling data of the processing load of the trial cutting and the actual measurement data of the processing load at the actual cutting, and monitor the processing state. .

JP-A-8-19939 JP 2005-32279 A Japanese Unexamined Patent Publication No. 7-51995

  In the technique disclosed in Patent Document 1, in order to measure the load torque during machining for each tool, an M code as an auxiliary function is manually inserted into the machining program before the machining program is executed. It was necessary to determine the tool to be measured and the measurement section (cutting operation section of each tool) (see FIG. 7). In the prior art shown in FIG. 7, auxiliary function M code 1 (reference m1), auxiliary function M code 2 (reference m2), auxiliary function M code 3 (reference m3), and auxiliary function M code 4 (reference m4) are manually performed. Is inserted into the machining program.

  As described above, as a method of determining the measurement section, it is a general method to arrange the auxiliary function M code before and after the measurement section of the machining program. However, it is necessary to manually change the machining program. It may also affect the execution of the machining program. Further, it is necessary to manually set the correspondence between the tool in the measurement section and the motor to be measured in advance, and the work is complicated.

  In the technique disclosed in Patent Document 2, it is necessary to determine the load torque measurement section based on the sequence number of the machining program, but the machining program needs to be changed in order to place the sequence number in the command block serving as the measurement section. It becomes.

  In the technique disclosed in Patent Document 3, since the load torque measurement section is determined and recorded in command block units of the machining program, different operations (such as drilling operation and clearance) are performed by one command, such as a tap cycle command. In the command block that performs (operation) continuously, each cutting operation section cannot be determined, and thus the load torque cannot be measured for each cutting operation (see FIG. 8). FIG. 8 is a diagram for explaining a conventional technique in which a load torque measurement section is determined and recorded in command block units of a machining program. As shown in FIG. 8, each block of the auxiliary function M code (symbol ms) for instructing the start of the measurement section and the auxiliary function M code (symbol me) for instructing the end of the measurement section is inserted into the machining program. However, the tap cycle command (block number: 30) is a command for performing two cutting operations, a drilling operation (cutting operation 1) and a relief operation (cutting operation 2). In such a command block, since each cutting operation section cannot be determined, the load torque cannot be classified for each cutting operation.

  Therefore, an object of the present invention is to automatically determine a tool and a motor to be subjected to measurement of load torque and a measurement section from a command of a machining program being executed, so that load torque for each tool can be changed without changing the machining program. It is to provide a numerical control device having a motor load torque measurement function capable of measuring the above. It is another object of the present invention to provide a numerical control device having a motor load torque measurement function that enables measurement of load torque for each cutting operation by distinguishing each cutting operation section from the moving direction of the feed shaft.

The invention according to claim 1 of the present application drives the feed shaft motor and the spindle motor of the machine tool according to the machining program to move the workpiece and the tool relative to each other to process the workpiece, and the load torque measuring means A numerical control device having a motor load torque measurement function for measuring a load torque of a feed shaft motor and a spindle motor, a tool number reading means for reading a tool number instructed by a tool change command of the machining program, and tool change A cutting operation discriminating means for discriminating whether the operation commanded by the subsequent machining program is a cutting operation or a non-cutting operation; and when the cutting operation discriminating means discriminates the cutting operation, the cutting operation A load torque measurement section in which a section from the start of movement to the end of movement of the feed shaft motor used for the load is set as a load torque measurement section In the load torque measurement section set by the setting means and the load torque measurement section setting means, the load torque of the feed shaft motor and the spindle motor is measured by the load torque measurement means and read by the tool number reading means. A numerical control device having a motor load torque measurement function, comprising storage means for storing motor load torque of each feed shaft motor and main shaft motor in association with a tool number.
According to a second aspect of the present invention, when there is a cutting operation in which the moving direction of the feed shaft is different in one command block of the machining program, the cutting operation determination unit determines this as another cutting operation, and 2. A numerical control apparatus having a motor load torque measurement function according to claim 1, wherein said command block is means for determining that said command block comprises a plurality of cutting operations, and measures and stores said load torque for each cutting operation. It is.

According to the present invention, the load torque of each tool can be measured without changing the machining program by automatically determining the load torque measurement target tool and motor and the measurement section from the command of the machining program being executed. It is possible to provide a numerical control device having a motor load torque measurement function that can be performed.
Furthermore, by distinguishing each cutting operation section from the moving direction of the feed shaft, it is possible to provide a numerical control device having a motor load torque measurement function that enables measurement of load torque for each cutting operation.

It is a block diagram of the principal part of the numerical control apparatus which is one Embodiment of this invention, and the principal part of the machine tool controlled by this numerical control apparatus. It is a figure explaining the load torque measurement data stored in a memory | storage means. It is a figure explaining embodiment of this invention. It is a flowchart which shows the algorithm of the process which measures the load torque which concerns on this invention. It is a figure explaining other embodiment of this invention. It is a flowchart which shows the algorithm of the process which measures the load torque which concerns on this invention (when there exists cutting operation from which the moving direction of a feed shaft differs). It is a figure explaining the prior art which inserts the M code of an auxiliary function into a machining program manually. It is a figure explaining the prior art which determines the measurement area of load torque for every command block of a processing program, and is recorded.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing a main part of a numerical control apparatus according to an embodiment of the present invention and a main part of a machine tool controlled by the numerical control apparatus. The numerical control device 10 includes a processor (CPU) 11, a ROM 12, a RAM 13, a servo control unit 14, a display control unit 15, a PMC 16, an I / O unit 17, a spindle control unit 18, and the like. Yes.
The processor 11 reads a system program stored in the ROM 12 and controls the numerical control apparatus as a whole in accordance with the system program. The RAM 13 stores temporary calculation data, display data, machining programs input from an input interface (not shown), and the like, and each feed associated with a tool number is related particularly to the present embodiment. It is a storage means for storing the motor load torque of each feed shaft motor and main shaft motor by attaching a shaft.

  The display control unit 15 includes the current position of each axis of the machine tool, an alarm, various parameters, image signals such as image data, and the current value of the measured load torque, the load torque, the load torque in relation to the present embodiment. A signal such as an average value or a maximum value is transmitted to the display 21. The display 21 performs a display function and a function of data input means, and displays various information described above on the display 21. Also, a setting input means for setting a limit value of the load torque for making an alarm is configured.

  The servo control unit 14 includes a processor, a memory such as a ROM, a RAM, and the like, and is based on each feed axis (in this embodiment, orthogonal) sent from the processor (CPU) 11 of the numerical controller 10 based on a machining program. The servo motors Mx, My, and Mz are driven through the servo amplifiers 22x, 22y, and 22z of the respective axes in response to a movement command to the feed axes of the X, Y, and Z axes). .

  Each axis servo motor Mx, My, Mz incorporates a pulse encoder (not shown) for position / speed detection. Each servo amplifier 22x, 22y, 22z includes a current detector (not shown) that detects the drive current of each servo motor Mx, My, Mz. The servo control unit 14 performs each process of the position loop, the speed loop, and the current loop based on the movement command from the processor 11 and the position, speed, and current feedback signals from each pulse encoder and each current detector. The position and speed of the servo motors Mx, My, and Mz for each axis are controlled. The processor (not shown) included in the servo control unit 14 incorporates a disturbance estimation observer, and the load torque of each feed shaft is estimated by this observer.

  A PMC (programmable machine controller) 16 is built in the numerical controller 10 and executes a sequence program to control the machine. In accordance with the M function, S function, and T function commanded by the machining program, these are converted into signals necessary for the machine tool side by the sequence program, and output from the I / O unit 17 to the machine tool side. A machine tool (not shown) replaces a tool to be used in accordance with a signal input from the I / O unit 17 based on the T function.

The spindle control unit 18 rotates the spindle motor Ms at the commanded rotational speed via the spindle amplifier 23 based on the spindle rotation command and orientation command from the processor 11 and the feedback signal from the position coder (not shown). Further, the rotational position of the spindle motor Ms is positioned at a predetermined position by an orientation command. A disturbance estimation observer is also incorporated in the spindle controller 18 so as to estimate and detect the load torque applied to the spindle motor Ms.
Note that the disturbance estimation observer incorporated in the servo control unit 14 and the spindle control unit 18 is a well-known technique as disclosed in, for example, Patent Document 3, and thus detailed description thereof is omitted.

  Servo motors and spindle motors when the tool is broken or worn when the workpiece is being cut by the tool, that is, when cutting commands (commands such as G01, G02, G03, G94) are executed. Can be monitored by measuring the load torque and taking statistics of the load torque measurement data.

  As described above, the servo control unit 14 and the spindle control unit 18 incorporate the disturbance estimation observer for the servo motors Mx, My, and Mz of each axis and the disturbance estimation observer for the spindle motor Ms. The load torque applied to the shaft motors Mx, My, Mz and the main shaft motor Ms is required. The load torque obtained by this observer is stored in a predetermined storage area of the RAM 13.

  FIG. 2 is a diagram for explaining load torque measurement data stored in the storage means. In a predetermined storage area of the RAM 13, measurement data (current value, maximum value, average value) of load torque of each motor during the cutting operation is stored for each measurement tool and measurement section. The current value stores the current value of the load torque measured during the measurement section. The maximum value stores the maximum value of the load torque measured during the measurement period. In addition, the average value of the load torque measured during the measurement section is stored in the average value after the measurement section ends. Note that a method for calculating the maximum value and the average value from the load torque measurement data can use a well-known statistical processing method, and thus a detailed description thereof will be omitted.

  As shown in FIG. 2, the measuring tool T01 is that the tool to be measured is T01, the machining program block that performs the measurement is 100 (sequence number), and the block 100 is divided into two measurement sections 1. , 2, the load torque measurement data of each motor is stored in the RAM 13 (see FIG. 1) as storage means as the main shaft 1, the main shaft 2, the servo shaft 1,. In addition, as in the measurement tool T05 and the measurement tool T20, load torque measurement data of each motor may be stored using the measurement block as one measurement section. In this case, it is determined whether or not the measurement section is divided into a plurality of sections according to the cutting operation executed in each measurement block. This will be described later with reference to FIG.

As for the load torques of the main shaft motor Ms and the servo motors Mx, My, Mz of each feed shaft that are measured and stored, the maximum value and the average value are obtained in the same manner as the load torque monitoring function provided in the conventional numerical control device.
Also, an alarm signal is output when the measured maximum value and average value of the load torque exceed a preset limit value. In addition, since the point which outputs an alarm signal when the maximum value and average value of the measured load torque exceed a limit value is the same as that of the prior art, detailed description is omitted.

  In the embodiment of the present invention, only the load torque in the cutting feed command is measured, but the load torque of the servo motor in the positioning operation is determined by determining the positioning (rapid feed) operation other than the cutting operation. It is also possible to measure automatically.

  In the above-described embodiment of the present invention, the example in which the load torque is monitored by estimating the load torque of the spindle motor Ms and the servo motors Mx, My, and Mz of each feed shaft with the disturbance estimation observer has been described. When the disturbance estimation observer is not provided, the magnitude of the motor drive current may be detected as the magnitude of the load torque. In this case, the motor drive current may be measured by measuring the current feedback signal detected and fed back by the current detector of each motor, or the current command (torque command) output from the speed loop is regarded as the load torque. You may make it measure.

  FIG. 3 is a diagram for explaining an embodiment of the present invention. When the machining program is executed, the tool to be measured is determined from the tool change command, and when a cutting operation is commanded, the servo motor of the feed axis used for the cutting operation is automatically determined from the command block. Then, the load torque is measured from the start of movement of the feed shaft to the end of movement as a load torque measurement section, and the load torque of the spindle motor and servo motor in that section is automatically measured.

  In FIG. 3, the machining program includes a tool change command (T01) block, an interpolation command (block number: 10, feed axis: Z axis, spindle: SP1) block, a tool change command (T03) block, an interpolation command ( The command of each block of block number: 20, feed axis: Z axis, spindle: SP1) is included.

FIG. 4 is a flowchart showing an algorithm of processing for measuring load torque according to the present invention. And the process of the flowchart shown in FIG. 4 is performed by the processor 11 of the numerical controller 10 for every predetermined period. Hereinafter, it demonstrates according to each step.
[Step SA100] It is determined whether or not tool change is instructed in the read machining program block. If a tool change instruction is issued, the process proceeds to Step SA101. If not, the process proceeds to Step S102. .
[Step SA101] The tool to be measured is determined from the tool change command of the machining program, and as shown in FIG. 2, the load torque measurement data of the tool to be measured, the servo motor that drives the tool, and the spindle motor are stored. Determine the recording memory to be used.
[Step SA102] It is determined whether or not a cutting operation has been commanded. If a cutting operation has been commanded, the process proceeds to Step SA103, and if not, the process proceeds to Step SA109. Whether or not it is a cutting command is determined by whether or not there is a G01 or G02 code in the block command.
[Step SA103] From the cutting command block of the machining program, the servo motor of the feed axis that drives the tool to be measured is determined.
[Step SA104] It is determined whether or not the movement of the feed axis is started, and the process proceeds to Step SA105 after waiting for the movement to start.
[Step SA105] The load torque of each motor is measured.
[Step SA106] The load torque measurement data is recorded in the recording memory.
[Step SA107] It is determined whether or not the movement of the feed axis is finished. If the movement is not finished, the process returns to Step SA105 to continue the process. If the movement is finished, the process goes to Step SA108.
[Step SA108] The cutting operation is terminated.
[Step SA109] It is determined whether or not the machining program is finished. If not finished, the process returns to Step SA100 to continue the process. If finished, the process for measuring the load torque of the motor is finished.

  FIG. 5 is a diagram for explaining another embodiment of the present invention. During execution of the machining program, if there is a cutting operation in which the movement direction of the feed shaft is different in one command block, it is determined that the cutting operation is another, and the load torque measurement section is distinguished. In the example of the tap cycle command shown in FIG. 5, the drilling operation and the relief operation are set as separate measurement sections, and the measured load torque data can be determined from the measurement sections. In FIG. 5, the machining program includes a tool change command T01 and a tap cycle command (block number: 30, feed axis: Z axis, spindle SP1).

FIG. 6 is a flowchart showing an algorithm of processing for measuring load torque according to the present invention (when there is a cutting operation in which the moving direction of the feed shaft is different). Hereinafter, it demonstrates according to each step.
[Step SB100] It is determined whether or not a tool change command is issued in the read machining program block. If a tool change command is issued, the process proceeds to Step SB101. If not, the process proceeds to Step SB102. .
[Step SB101] A tool to be measured is determined.
[Step SB102] It is determined whether or not a cutting operation has been commanded. If a cutting operation has been commanded, the process proceeds to Step SB103, and if not, the process proceeds to Step SB111. Whether or not it is a cutting command is determined by whether or not there is a G01 or G02 code in the block command.
[Step SB103] The servo motor for the feed axis is determined.
[Step SB104] It is determined whether or not the movement of the feed axis is started, and the process proceeds to Step SB105 after waiting for the movement to start.
[Step SB105] It is determined whether there is a cutting operation in which the moving direction of the feed axis is different. If there is a different cutting operation, the process proceeds to Step SB106, and if not, the process proceeds to Step SB107. The presence / absence of a cutting operation in which the moving direction of the feed shaft is different is performed by monitoring the moving direction vector of the feed shaft, for example.
[Step SB106] The measurement section is updated, and the process proceeds to Step SB107. As shown in FIG. 2, the measurement section is updated by storing the tool to be measured and load torque measurement data of the servo motor and spindle motor for driving the tool in the case of a cutting operation in which the moving direction of the feed axis is different. This means that the area to be set is set as a new measurement section.
[Step SB107] The load torque of each motor is measured.
[Step SB108] The load torque measurement data is stored in the recording memory.
[Step SB109] It is determined whether or not the movement of the feed axis is finished. If the movement is not finished, the process returns to Step SB105 and the process is continued. If the movement is finished, the process goes to Step SB110.
[Step SB110] The cutting operation is terminated.
[Step SB111] It is determined whether or not the machining program is finished. If not finished, the process returns to Step SB100 to continue the process. If finished, the process for measuring the load torque of the motor is finished.

  As described above, according to the present invention, no complicated setting work or machining program change work is required in the measurement of load torque. Therefore, even when a machining program is newly created or changed, it is possible to measure the motor load torque during machining for each tool and cutting operation and take statistics (average value and maximum value during cutting operation, etc.) It becomes easy.

  In the embodiment of the present invention, in addition to the load torque, the motor speed based on the speed feedback signal of the motor fed back and the speed command output from the position loop, the error amount (position error) obtained by the position loop processing In addition, the motor state such as the amount of heat obtained by the thermal simulation may be monitored.

10 Numerical Control Device 11 Processor (CPU)
12 ROM
13 RAM
14 Servo Control Unit 15 Display Control Unit 16 PMC
17 I / O unit 18 Spindle control unit 19 Bus 21 Display 22x, 22y, 22z Servo amplifier 23 Spindle amplifier Mx X-axis servo motor My Y-axis servo motor Mz Z-axis servo motor Ms Spindle motor

Claims (2)

According to the machining program, the feed axis motor and the spindle motor of the machine tool are driven to move the workpiece and the tool relatively to process the workpiece, and the load torque of the feed axis motor and the spindle motor being processed by the load torque measuring means A numerical control device having a motor load torque measurement function for measuring
Tool number reading means for reading the tool number instructed by the tool change command of the machining program;
A cutting motion discriminating means for discriminating whether the motion commanded by the machining program after the tool change is a cutting motion or a non-cutting motion;
Load torque measurement section setting means for setting, as a load torque measurement section, a section from the start of movement to the end of movement of the feed shaft motor used for the cutting operation when it is determined by the cutting operation determination means. When,
In the load torque measurement section set by the load torque measurement section setting means, the load torque of the feed shaft motor and the spindle motor is measured by the load torque measurement means and corresponds to the tool number read by the tool number reading means. Storage means for storing the motor load torque of each feed shaft motor and main shaft motor;
A numerical control device having a motor load torque measurement function.   When one command block of the machining program includes a cutting operation in which the moving direction of the feed shaft is different, the cutting operation determination unit determines that this is another cutting operation, and the one command block includes a plurality of cutting operations. The numerical control device having a motor load torque measuring function according to claim 1, wherein the numerical value control device is a means for determining that the operation consists of an operation, and measures and stores the load torque for each cutting operation.

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