JP7238673B2 - Numerical controller and control method - Google Patents

Description

The present invention relates to a numerical controller and control method.

The numerical control device described in Patent Document 1 controls a motor provided for each of two intersecting axes to move a table that supports a work material to a desired position. The time constant of the first low-pass filter is the reciprocal of the frequency of vibration occurring in one of the two axial directions. The time constant of the second low-pass filter is the reciprocal of the frequency of vibration generated in the other of the two axial directions. The numerical controller smoothes the speed change signal for speeding each motor through a first low-pass filter and a second low-pass filter.

Japanese Patent No. 6107306

When moving the table, the numerical controller applies a filter to the velocity waveform generated from the position command of the NC program to drive the motor. As for the time constant of the filter, it is preferable that the maximum torque, which is the torque when the acceleration of the motor is maximum, does not exceed the rated torque of the motor. Here, the maximum torque of the motor changes according to the mass of the jig and work material (referred to as load mass) loaded on the table. However, the numerical control device described in Patent Document 1 only determines the time constants of the first low-pass filter and the second low-pass filter according to the reciprocal of the vibration frequency, and the load mass changes. does not change the time constant. Therefore, when the maximum torque of the motor changes according to the load mass, there is a problem that an appropriate time constant for limiting the acceleration cannot be determined.

An object of the present invention is to appropriately determine the time constant of a filter for limiting acceleration even if the maximum torque of the motor changes according to the load mass, and at the same time, to provide It is an object of the present invention to provide a numerical controller and control method capable of determining a variable damping time constant according to the vibration frequency.

A numerical control device according to a first aspect of the present invention controls the operation of a machine capable of moving a table with a motor and machining a work material supported by a jig on the table with a tool mounted on a spindle, In a numerical controller comprising a controller capable of executing acceleration/deceleration processing for filtering a velocity waveform generated from a table position command, the controller controls the jig and the work material on the table. a first determination unit that determines a torque suppression time constant that is a time constant that corresponds to the maximum torque of the motor that changes according to the load mass that is the mass of the load, and the machine that changes according to the load mass a second determining unit that determines the reciprocal of the variable damping frequency corresponding to the vibration frequency unique to the variable damping time constant as a variable damping time constant; a first filter having the torque suppression time constant determined by the first determining unit; and a processing unit that executes the acceleration/deceleration process using a second filter having the variable damping time constant determined by the second determination unit.

In the first aspect, the numerical controller determines a torque suppression time constant according to the maximum torque of the motor that changes according to the load mass, and executes acceleration/deceleration processing using a first filter having the torque suppression time constant. . Therefore, the numerical controller can appropriately execute acceleration/deceleration processing so that the maximum torque does not exceed the rated torque even if the torque corresponding to the acceleration of the motor changes due to the change in the load mass. Furthermore, the numerical controller determines a variable damping time constant according to the vibration frequency unique to the machine, which changes according to the load mass, and executes acceleration/deceleration processing using a second filter having a variable damping time constant. do. Therefore, the numerical controller can appropriately suppress mechanical vibrations whose frequency changes according to the load mass.

In the first aspect, the load mass and the variable damping frequency may have a non-linear relationship. At this time, the numerical controller can accurately determine the variable damping time constant based on the load mass.

In the first aspect, the control unit further includes a third determining unit that determines, as a fixed damping time constant, the reciprocal of a fixed damping frequency corresponding to a vibration frequency unique to the machine that does not change according to the load mass. The processing unit may further use a third filter having the fixed damping time constant determined by the third determination unit to perform the acceleration/deceleration process. Therefore, the numerical controller can appropriately suppress machine vibrations that do not change according to the load mass.

In the first aspect, the control unit includes an acquisition unit that acquires torque and acceleration of the motor when the table is moved, and estimates the load mass based on the torque and the acceleration acquired by the acquisition unit. and an estimating unit, wherein the first determining unit determines the torque suppression time constant based on the load mass estimated by the estimating unit, and the second determining unit estimates by the estimating unit The variable damping time constant may be determined based on the load mass. At this time, the numerical controller can accurately determine the torque suppression time constant and the variable damping time constant without the operator having to measure the load mass in advance.

In the first aspect, the table is movable in two intersecting axial directions, the motor is provided for each of the axes in the two axial directions, and the first determination unit controls the torque for each axis. A time constant may be determined, the second determination unit may determine the variable damping time constant for each axis, and the processing unit may be capable of executing the acceleration/deceleration process for each axis. The numerical controller can appropriately execute the acceleration/deceleration process even if the maximum torque of the motor corresponding to each of the two moving directions of the table changes according to the load mass.

In the first aspect, the filter may be an FIR filter. At this time, the numerical controller can appropriately smooth the velocity waveform by acceleration/deceleration processing.

A control method according to a second aspect of the present invention moves a table by a motor, controls the operation of a machine capable of processing a work material supported by a jig on the table with a tool mounted on a spindle, and controls the operation of the table. A control method capable of executing an acceleration/deceleration process for filtering a velocity waveform generated from a position command, wherein the load mass is the mass of a load including the jig and the work material on the table a first determining step of determining a torque suppression time constant, which is a time constant responsive to the maximum torque of the motor that varies according to the load mass; A second determination step of determining the reciprocal of the vibration frequency as a variable damping time constant, a first filter having the torque suppression time constant determined by the first determination step, and the variable determined by the second determination step and a processing step of executing the acceleration/deceleration process using a second filter having a damping time constant. According to the second aspect, the same effects as those of the first aspect can be obtained.

2 is a schematic side view of the machine tool 10; FIG. 2 is a block diagram showing electrical configurations of a numerical controller 20 and a machine tool 10; FIG. Graph showing frequency characteristics of variable vibration. 5 is a graph showing the relationship between the load mass M and the variable damping frequency Fvar; Flowchart of main processing. The flowchart of the main process in a modification.

Embodiments of the present invention will be described below. The machine tool 10 shown in FIG. 1 rotates the tool 4 mounted on the main spindle 9 at high speed and contacts the work W supported by a jig (not shown) on the table 50 to cut the work W. Processing, etc. Numerical controller 20 controls the operation of machine tool 10 . The horizontal direction, the front-rear direction, and the vertical direction of the machine tool 10 are the X-axis direction, the Y-axis direction, and the Z-axis direction, respectively.

<Configuration of machine tool 10>
As shown in FIG. 1, the machine tool 10 includes a bed 2, a column 5, a spindle head 7, a spindle 9, a table device 40, an operation panel 16 (see FIG. 2), and the like. In the machine tool 10, the table 50 of the table device 40 moves in two axial directions of the X axis and the Y axis. The bed section 2 is the base of the machine tool 10 . The column 5 is fixed to the rear portion of the upper surface of the bed portion 2 . The spindle head 7 moves along the front surface of the column 5 in the Z-axis direction. The column 5 has a Z-axis moving mechanism (not shown) on its front surface. The Z-axis movement mechanism uses a Z-axis motor 11 (see FIG. 2) as a drive source. The Z-axis movement mechanism has the same structure as the Y-axis movement mechanism described later. The spindle 9 extends in the Z-axis direction inside the spindle head 7 and is rotatably provided. A tool mounting hole (not shown) provided in the lower end of the spindle 9 is provided in the lower part of the spindle 9 . The tool 4 is mounted in the tool mounting hole.

The table device 40 is provided on the upper surface of the bed portion 2 and below the spindle head 7 . The table device 40 supports the table 50 so as to be movable in two axial directions of the X axis and the Y axis. For convenience of explanation, only the Y-axis moving mechanism for moving the table 50 in the Y-axis direction is illustrated in the table device 40 shown in FIG. 1, and the X-axis moving mechanism is omitted. The table device 40 includes a bed 41, a Y-axis guide rail 42, a Y-axis motor 14, a joint 43, a ball screw 44, a bearing portion 45, a nut 46, a table 50, and the like. The bed 41, Y-axis guide rail 42, Y-axis motor 14, joint 43, ball screw 44, bearing portion 45, and nut 46 constitute a Y-axis movement mechanism.

A bed 41 is installed on the upper surface of the bed section 2 . The bed 41 has a recess (not shown) elongated in the Y-axis direction in the central portion in the left-right direction, and most of the Y-axis movement mechanism, which will be described later, is housed inside the recess. A Y-axis guide rail 42 is provided above the bed 41 and extends in the Y-axis direction. The Y-axis guide rail 42 movably guides the table 50 in the Y-axis direction. The Y-axis motor 14 is provided behind the recess of the bed 41 . A ball screw 44 is provided inside the recess of the bed 41 and extends in the Y-axis direction. The joint 43 connects the forwardly protruding output shaft of the Y-axis motor 14 and the rear end of the ball screw 44 to each other. The bearing portion 45 rotatably supports the front end portion of the ball screw 44 . Therefore, when the output shaft of the Y-axis motor 14 rotates, the ball screw 44 rotates via the joint 43 . A nut 46 is fixed to the lower surface of the table 50 and screwed onto the ball screw 44 . Therefore, as the ball screw 44 rotates, the table 50 moves along with the nut 46 in the Y-axis direction.

The table device 40 has an X-axis movement mechanism in addition to the Y-axis movement mechanism. The X-axis movement mechanism supports the Y-axis movement mechanism so as to be movable in the X-axis direction. The X-axis movement mechanism uses the X-axis motor 13 (see FIG. 2) as a drive source, and has the same structure as the Y-axis movement mechanism.

As shown in FIG. 2 , the operation panel 16 has an input section 17 and a display section 18 . The input unit 17 is a device for performing various inputs, instructions, settings, and the like. The display unit 18 is a device that displays various screens.

<Electrical configuration>
As shown in FIG. 2, the numerical controller 20 includes a CPU 21, a ROM 22, a RAM 23, a storage device 24, an input/output section 25, drive circuits 26-29, and the like. The CPU 21 centrally controls the numerical control device 20 . The ROM 22 stores programs and setting values for the CPU 21 to execute main processing, which will be described later. The RAM 23 stores various data during execution of various processes. The storage device 24 is a non-volatile memory and stores various data in addition to the NC program. The input/output unit 25 is connected to the operation panel 16 . Drive circuits 26 to 29 are servo amplifiers. The Z-axis motor 11 has an encoder 11A. The spindle motor 12 has an encoder 12A. The X-axis motor 13 has an encoder 13A. The Y-axis motor 14 has an encoder 14A. A drive circuit 26 is connected to the Z-axis motor 11 and the encoder 11A. A drive circuit 27 is connected to the spindle motor 12 and the encoder 12A. A drive circuit 28 is connected to the X-axis motor 13 and the encoder 13A. A drive circuit 29 is connected to the Y-axis motor 14 and the encoder 14A.

The CPU 21 reads an NC program for machining the work material W, and sends a control command to the drive circuit to move each drive axis such as the feed axes (X-axis, Y-axis, Z-axis) and the main shaft 9 to a target position. Send to 26-29. The drive circuits 26 to 29 output drive currents to the corresponding motors 11 to 14 according to control commands (drive signals) received from the CPU 21, respectively. Drive circuits 26-29 receive feedback signals (position and speed signals) from encoders 11A-14A and control the positions and speeds of motors 11-14. The operation panel 16 is connected to the input/output section 25 of the numerical controller 20 .

<Feed axis control>
When the machine tool 10 is driven based on an NC program command (hereinafter referred to as a "feed axis command") that moves the tool 4 relative to the workpiece W in the X-axis direction or the Y-axis direction for machining. is exemplified. A case where the tool 4 is relatively moved in the Y-axis direction with respect to the work W to be machined will be described below as an example. The case where the tool 4 is relatively moved in the X-axis direction with respect to the workpiece W for machining is the same as the case where the tool 4 is relatively moved in the Y-axis direction for machining, so the description is omitted.

When the CPU 21 reads the feed axis command, the table 50 holding the workpiece W is moved to the position specified by the feed axis command, so the CPU 21 generates time-series data of the target position of the table 50 . The CPU 21 outputs target position data to the drive circuit 29 at predetermined intervals. The drive circuit 29 drives the Y-axis motor 14 based on the target position data output from the CPU 21 . The Y-axis motor 14 moves the table 50 to the target position in the Y-axis direction. Each time the CPU 21 inputs target position data to the drive circuit 29 , the drive circuit 29 drives the Y-axis motor 14 . The CPU 21 also drives the X-axis motor 13 in the same manner. As a result, the table 50 finally reaches the position specified by the feed axis command (hereinafter referred to as "command position"). The above control executed by the CPU 21 based on the feed axis command is called "feed axis control".

When generating the time-series data of the target positions as described above, the CPU 21 first determines each target position so that the speed when the table 50 moves to the position specified by the feed axis command remains constant. Next, the CPU 21 adjusts acceleration/deceleration characteristics corresponding to the shape of the velocity waveform by applying a moving average filter to the waveform indicating the time-series change in velocity (hereinafter referred to as "velocity waveform"). A moving average filter is a digital filter with a finite-time impulse response, ie an FIR filter. The CPU 21 determines the target position for each predetermined cycle based on the velocity waveform calculated by applying the moving average filter. The CPU 21 outputs the determined target position data to the drive circuit 29 at a predetermined cycle. The time constant of the moving average filter is called an acceleration/deceleration time constant. The process of adjusting the acceleration/deceleration characteristics by applying the moving average filter to the velocity waveform is called acceleration/deceleration process. Although _details will _be described later, the CPU ₂₁ includes three moving average filters ( Acceleration/deceleration processing is executed by applying the first filter FIR1, the second filter FIR2, and the third filter FIR3) to the velocity waveform.

<Torque suppression time constant _t1 >
In order to limit the maximum value of the torque generated in the Y-axis motor 14 (hereinafter referred to as "maximum torque") when executing the feed axis control, the CPU 21 converts the first filter FIR1 having the torque suppression time constant _t1 into the velocity waveform. Apply. Note that the maximum torque of the Y-axis motor 14 when the feed axis control is executed changes according to the load mass _M1 . The load mass _M1 corresponds to the sum of the mass of the table 50 itself, the equivalent mass of the feed mechanism, and the load mass M. Here, the equivalent mass of the feed mechanism is obtained by converting the total inertia of the Y-axis motor 14, the joint 43, the ball screw 44, and the nut 46 that constitute the feed mechanism of the table 50 into mass. The load mass M is the sum of the mass of the jig provided on the table 50 and the mass of the work material W held by the jig. The mass of table 50 and the equivalent mass of the feed mechanism are constants. Therefore, load mass _M1 changes when load mass M changes. Therefore, the torque suppression time constant _t1 for suppressing the maximum torque also changes according to the load mass M. The CPU 21 determines an appropriate torque suppression time constant _t1 and first filter FIR1 according to the load mass M, and applies them to the velocity waveform, thereby changing the maximum torque of the Y-axis motor 14 according to the load mass M. Feed axis control can be executed while limiting the maximum torque.

A method of calculating the torque suppression time constant _t1 is as follows. The maximum value of the torque allowed in the Y-axis motor 14 (hereinafter referred to as "rated torque") is referred to as Tmax [N]. The acceleration of the table 50 when the Y-axis motor 14 is driven at the rated torque Tmax is called a[m/s ² ]. The rated torque Tmax, the load mass M ₁ [kg], and the acceleration a satisfy the relationship of the following formula (1).
Tmax = M ₁ ×a (1)

Furthermore, the maximum speed of the table 50 defined by the machine tool 10 is called Vmax [m/s]. The torque suppression time constant _t1 , the maximum speed Vmax, the load mass _M1 , the rated torque Tmax, and the acceleration a satisfy the following equation (2).
_t1 =Vmax/a=Vmax/(Tmax/ _M1 ) (2)

<Variable damping time constant _t2 , Fixed damping time constant _t3 >
In order to limit the vibration generated in the machine tool 10 when the feed axis control is executed, the CPU 21 controls the second filter FIR2 having a variable damping time constant _t2 and the third filter FIR2 having a fixed damping time constant _t3 . FIR3 is applied to each velocity waveform. The vibrations generated in the machine tool 10 by the execution of the feed axis control are vibrations whose natural frequency changes according to the amount of moving material _M2 (hereinafter referred to as "variable vibration") and vibrations corresponding to the amount of moving material _M2 . There is a vibration whose natural frequency does not change (hereinafter referred to as “fixed vibration”). The amount of transferred material _M2 is the sum of the mass of the table 50 and the load mass M. At this time, since the mass of the table 50 is constant, the amount of transferred material _M2 changes according to the load mass M. That is, the variable vibration changes according to the payload M. The fixed frequency is a frequency at which the machine tool 10 is most likely to vibrate when the table 50 moves, and means a unique frequency determined according to the configuration of the machine tool 10 and the like. By applying a moving average filter having the reciprocal of the natural frequency as a time constant to the velocity waveform, it is possible to limit the vibration of the machine tool 10 during execution of the feed axis control. Hereinafter, the natural frequency of variable vibration will be referred to as variable damping frequency Fvar, and the natural frequency of fixed vibration will be referred to as fixed damping frequency Ffix.

The variable vibration is mainly vibration of the table 50 in the Y-axis direction when the feed axis control is executed. FIG. 3 is a graph showing how the variable damping frequency Fvar changes according to the payload M. In FIG. A frequency showing a peak in the graph corresponds to the variable damping frequency Fvar. As shown in FIG. 3A, when the load M is 100 kg, the variable damping frequency Fvar is approximately 40 Hz. As shown in FIG. 3B, when the load M is 250 kg, the variable damping frequency Fvar is approximately 35 Hz. The variable damping frequency Fvar and the amount of moving material _M2 satisfy the relationship of the following equation (3).
2π×Fvar=√(k/M ₂ ) (3)
Fvar varies with payload M because the amount of transferred mass _M2 varies with payload M. Note that k is the rigidity of the table 50 in the Y-axis direction, and is a coefficient obtained by substituting a design value or an actual measurement value into equation (3). FIG. 4 is a graph showing the relationship between the load mass M and the variable damping frequency Fvar based on the equation (3). Thus, the load mass M and the variable damping frequency Fvar have a nonlinear relationship.

The reciprocal 1/Fvar of the variable damping frequency Fvar indicates the variable damping time constant _t2 , which is the time constant of the moving average filter capable of suppressing variable vibration (see equation (4)).
t ₂ =1/Fvar = 2π×√(M ₂ /k) (4)
The CPU 21 determines the second filter FIR2 based on an appropriate variable damping time constant _t2 according to the load mass M, and applies it to the velocity waveform. Thereby, the CPU 21 can execute the feed axis control while suppressing the variable vibration.

Fixed vibration is vibration of the entire machine that occurs mainly during execution of feed axis control. The reciprocal 1/Ffix of the fixed vibration damping frequency Ffix indicates the fixed vibration damping time constant _t3 , which is the time constant of the moving average filter capable of suppressing the fixed vibration (see equation (5)).
t ₃ =1/Ffix (5)
The CPU 21 determines the third filter FIR3 based on the fixed damping time constant _t3 , which is constant regardless of the load mass M, and applies it to the velocity waveform. Thereby, the CPU 21 can execute the feed axis control while suppressing the stationary vibration.

<Main processing>
The main processing will be described with reference to FIG. The CPU 21 starts main processing by reading and executing the program stored in the ROM 22 . The CPU 21 refers to the set values stored in the ROM 22 when executing the main process. The set values are the rated torque Tmax, maximum speed Vmax, coefficient k, and fixed damping frequency Ffix corresponding to the X axis, and the rated torque Tmax, maximum speed Vmax, coefficient k, and fixed damping frequency Ffix corresponding to the Y axis. , the maximum payload Mmax. The maximum load mass Mmax is the maximum load mass M allowed in the machine tool 10 .

The CPU 21 reads one command of the NC program stored in the storage device 24 (S11). The CPU 21 determines whether the operation of the machine tool 10 according to the read command is a fast-forward operation (S13). A fast-forward operation refers to an operation in which the X-axis motor 13 or the Y-axis motor 14 rotates at the maximum speed that can be set in the machine tool 10 .

When the CPU 21 determines that it is a fast-forward operation (S13: YES), it determines whether the machine tool 10 executes the fast-forward operation for the first time based on the NC program (S17). When the CPU 21 determines that the fast-forward operation is to be performed for the first time (S17: YES), the process proceeds to S19. In the following, it is assumed that the X-axis motor 13 and the Y-axis motor 14 each rotate at their maximum speeds for a fast forward operation. Rated torque Tmax, maximum speed Vmax, coefficient k, and fixed damping frequency Ffix corresponding to the X-axis are respectively defined as rated torque Tmax(x), maximum speed Vmax(x), coefficient k(x), fixed damping frequency Ffix (x). Rated torque Tmax, maximum speed Vmax, coefficient k, and fixed damping frequency Ffix corresponding to the Y-axis are respectively defined as rated torque Tmax(y), maximum speed Vmax(y), coefficient k(y), fixed damping frequency Ffix (y). In order to estimate the load mass M, the CPU 21 executes the processes of S19 to S23.

The CPU 21 substitutes M ₁ (x) corresponding to the rated torque Tmax(x), the maximum speed Vmax(x), and the maximum load mass Mmax stored in the ROM 22 into the equation (2), and the torque suppression corresponding to the X-axis A provisional value of constant _t1 (referred to as torque suppression time constant _t1 (x')) is calculated. The CPU 21 substitutes the coefficient k(x) stored in the ROM 22 and M ₂ (x) corresponding to the maximum loading mass Mmax into the equation (4), and _obtains the provisional value ( A variable damping time constant t ₂ (referred to as x′)) is calculated. The CPU 21 substitutes the fixed damping frequency Ffix(x) stored in the ROM 22 into the equation (5), and obtains the provisional value of the fixed damping time constant _t3 corresponding to the X-axis (fixed damping time constant _t3 (x' ) is calculated. The CPU 21 controls a first filter FIR1 having a torque suppression time constant _t1 (x'), a second filter FIR2 having a variable damping time constant _t2 (x'), and a fixed damping time constant _t3 (x'). ) is used to execute acceleration/deceleration processing using a third filter FIR3 (referred to as FIR3(x')) having a ) to adjust the velocity waveform for moving the table 50 in the X-axis direction by the X-axis motor 13 in the fast feed operation. .

Although the detailed explanation is omitted, the CPU 21 controls the provisional value of the torque suppression time constant _t1 corresponding to the Y-axis (referred to as torque suppression time constant _t1 (y')), the variable damping time constant _t2 . The provisional value (referred to as fixed damping time constant t ₃ (y′)) and the provisional value of fixed damping time constant t ₃ (referred to as fixed damping time constant t ₃ (y′)) are also calculated in the same manner. do. The CPU 21 selects a first filter FIR1 having a torque suppression time constant _t1 (y'), a second filter FIR2 having a variable damping time constant _t2 (y'), and a fixed damping time constant _t3 (y'). Acceleration/deceleration processing is executed using the third filter FIR3 provided, and the velocity waveform for moving the table 50 in the Y-axis direction by the Y-axis motor 14 in the fast feed operation is adjusted.

The CPU 21 executes feed axis control based on the adjusted speed waveform, and controls the rapid feed operation of the machine tool 10 (S19). The drive circuit 28 identifies the acceleration a(x) and the torque T(x) of the X-axis motor 13 based on the signal output from the encoder 13A while the machine tool 10 is executing the fast feed operation in S19. The drive circuit 29 specifies the acceleration a(y) and the torque T(y) of the Y-axis motor 14 based on the signal output from the encoder 14A while the machine tool 10 is executing the fast-forward operation in S19. The CPU 21 calculates accelerations a(x) and a(y) (collectively referred to as acceleration a) and torques T(x) and T( y) (collectively referred to as torque T) is acquired (S21). The CPU 21 substitutes the acceleration a and torque T into the following equation (6) to estimate the load mass _M1 .
_M1 = T/a (6)
The CPU 21 further calculates the load mass M(x) corresponding to the load mass M ₁ (x), which is the load mass M ₁ estimated based on the acceleration a(x) and the torque T(x), the acceleration a(y) and the torque The average value of the load mass M(y) corresponding to the load mass M ₁ (y), which is the load mass M ₁ estimated based on T(y), is estimated as the load mass M (S23). It should be noted that "load mass M=load mass M ₁ -equivalent mass of feed mechanism-mass of table 50". This estimation processing can be executed even when the X-axis and the Y-axis do not perform fast-forward operations at the same time. When only the X-axis performs the fast-forward operation, the load mass M(x) corresponding to the estimable load mass M ₁ (x) is estimated as the load mass M. When only the Y-axis performs fast-forwarding, the load mass M is estimated as the load mass M(y) corresponding to the estimable load mass M ₂ (y).

The CPU 21 substitutes the load mass M ₁ (x) corresponding to the estimated load mass M, the rated torque Tmax(x) and the maximum speed Vmax(x) stored in the ROM 22 into the equation (2), A torque suppression time constant t ₁ (referred to as torque suppression time constant t ₁ (x)) is determined (S25). The CPU 21 substitutes the moving mass amount M ₂ (x) corresponding to the estimated load mass M and the coefficient k(x) stored in the ROM 22 into the equation (4) to obtain the variable damping time constant t ₂ (referred to as variable damping time constant t ₂ (x)) is determined (S27). The CPU 21 substitutes the fixed damping frequency Ffix(x) stored in the ROM 22 into the equation (5) to obtain a fixed damping time constant t ₃ (referred to as a fixed damping time constant t ₃ (x)) corresponding to the X-axis. is determined (S29). Note that the fixed damping time constant t ₃ (x) is the same as the fixed damping time constant t ₃ (x') calculated when the fast forward operation is performed in S19. Although detailed explanation is omitted, the CPU 21 controls the torque suppression time constant t ₁ (referred to as torque suppression time constant t ₁ (y)) and the variable damping time constant t ₂ (variable damping time constant) corresponding to the Y axis. t ₂ (y)) and a fixed damping time constant t ₃ (referred to as a fixed damping time constant t ₃ (y)) are also determined by a similar calculation method. The CPU 21 calculates the determined torque suppression time constants t ₁ (x), t ₁ (y), variable damping time constants t ₂ (x), t ₂ (y), fixed damping time constants t ₃ (x), t ₃ (y) is stored in the RAM 23 (S31). The CPU 21 advances the process to S35.

In the process of S11, the CPU 21 determines whether or not the last command of the NC program has been read (S35). When the CPU 21 determines that the last command of the NC program has not been read (S35: NO), the process returns to S11. The CPU 21 reads one next command of the NC program (S11), and advances the process to S13.

When the CPU 21 determines that the fast-forwarding operation is not performed (S13: NO), the CPU 21 controls the machine tool 10 so that the machine tool 10 is driven by an operation (referred to as normal operation) according to the read command (S15). Although not described in detail here, normal operations include cutting operations, tapping operations, tool changing operations, etc., each operating using its own time constant. That is, when the table 50 moves in the X-axis direction during normal operation, the torque suppression time constant t ₁ (x), the variable damping time constant t ₂ (x), and the fixed damping time constant t ₃ (x) are different. Using the time constant, the velocity waveform for moving the table 50 in the X-axis direction by the X-axis motor 13 is adjusted. Also, when the table 50 moves in the Y-axis direction during normal operation, what are the torque suppression time constant t ₁ (y), the variable damping time constant t ₂ (y), and the fixed damping time constant t ₃ (y)? Using different time constants, the velocity waveform for moving the table 50 in the Y-axis direction by the Y-axis motor 14 is adjusted. The CPU 21 executes feed axis control based on the adjusted velocity waveform to control the normal operation of the machine tool 10 (S15). The CPU 21 advances the process to S35.

When the CPU 21 determines that the fast-forward operation is to be performed (S13: YES) and determines that the fast-forward operation is the second or subsequent fast-forward operation (S17: NO), the machine tool 10 is driven by the fast-forward operation. 10 is controlled (S33). At this time, when the table 50 moves in the X-axis direction due to the fast feed operation, the CPU 21 controls the first filter FIR1 having the torque suppression time constant t ₁ (x) stored in the RAM 23 in the processing of S31, the variable damping time constant t ₂ (x) and a third filter FIR3 having a fixed damping time constant t ₃ (x) are used to perform acceleration/deceleration processing, and the table 50 is moved in the X-axis direction by the X-axis motor 13. Adjust the velocity waveform for Further, when the table 50 moves in the Y-axis direction due to the fast feed operation, the CPU 21 controls the first filter FIR1 having the torque suppression time constant t ₁ (y) stored in the RAM 23 in the processing of S31, the variable damping time constant t ₂ (y) and a third filter FIR3 having a fixed damping time constant t ₃ (y) are used to perform acceleration/deceleration processing, and the table 50 is moved in the Y-axis direction by the Y-axis motor 14 in normal operation. Adjust the velocity waveform for moving to The CPU 21 executes feed axis control based on the adjusted velocity waveform to control the rapid feed operation of the machine tool 10 (S33). The CPU 21 advances the process to S35.

When the CPU 21 determines in the process of S11 that the last command of the NC program has been read (S35: YES), it ends the main process.

<Main actions and effects of the present invention>
The numerical control device 20 determines the torque suppression time constant _t1 according to the load mass M, the maximum speed Vmax, and the rated torque Tmax (S25), and performs acceleration using the first filter FIR1 having the torque suppression time constant _t1 . A deceleration process is executed (S33). Therefore, even if the torque corresponding to the acceleration of the X-axis motor 13 and the Y-axis motor 14 changes due to a change in the load mass M, the numerical control device 20 maintains the maximum torque of the X-axis motor 13 and the Y-axis motor 14 at the rated torque. Acceleration/deceleration processing can be properly executed so as not to exceed Tmax. Further, the numerical controller 20 determines a variable damping time constant _t2 for suppressing variable vibration of the machine tool 10 (S27), and accelerates/decelerates using the second filter FIR2 having the variable damping time constant _t2 . Processing is executed (S33). Therefore, the numerical controller 20 can appropriately suppress the variable vibration of the machine tool 10 even when the frequency of the variable vibration changes according to the load M.

Numerical controller 20 determines variable damping time constant _t2 on the assumption that load mass M and variable damping frequency Fvar have a nonlinear relationship. Therefore, the numerical controller 20 can accurately determine the variable damping time constant _t2 capable of suppressing variable vibrations even when the variable damping frequency Fvar changes in response to changes in the load mass M.

The numerical controller 20 determines a fixed damping time constant _t3 for suppressing the natural vibration of the machine tool 1 (S29), and performs acceleration/deceleration processing using the third filter FIR3 having the fixed damping time constant _t3 . (S33). Therefore, the numerical control device 20 can appropriately suppress the vibration of the machine tool 10 that does not change according to the load M.

The numerical controller 20 estimates the load mass M (S19 to S23), and determines the torque suppression time constant t ₁ and the variable damping time constant t ₂ based on the estimated load mass M (S25, S27). At this time, the numerical controller 20 can accurately determine the torque suppression time constant _t1 and the variable damping time constant _t2 even when the load mass M is undetermined. At this time, the numerical control device 20 does not need prior information regarding the payload M. Therefore, the numerical controller 20 can accurately determine the torque suppression time constant _t1 and the variable vibration suppression time constant _t2 without the operator having to measure the load mass M in advance.

The numerical controller 20 can move the table 50 in the X-axis direction and the Y-axis direction. The numerical controller 20 determines a torque suppression time constant t ₁ , a variable damping time constant t ₂ , and a fixed damping time constant t ₃ for each of the X-axis and Y-axis. Execute deceleration processing. Therefore, even if the maximum torque of each of the X-axis motor 13 and the Y-axis motor 14 changes according to the load mass M, the numerical controller 20 can appropriately execute the acceleration/deceleration process.

The numerical controller 20 uses an FIR filter as a moving average filter during acceleration/deceleration processing. Thereby, the numerical controller 20 can smooth the velocity waveform by the acceleration/deceleration process.

<Modification>
Main processing in the modified example will be described with reference to FIG. The difference from FIG. 5 is that the torque suppression time constants t ₁ (x) and t ₁ (y) and the variable damping time constant This is the point that determines t ₂ (x), t ₂ (y) and fixed damping time constants t ₃ (x), t ₃ (y). Therefore, the CPU 21 does not estimate the load mass. Hereinafter, processing different from that in FIG. 5 will be described in detail, and description of the same processing will be simplified.

The CPU 21 acquires the load mass M input by the user through the input unit 17 (S51). The CPU 21 substitutes the load mass M ₁ (x) corresponding to the acquired load mass M, the rated torque Tmax(x), and the maximum speed Vmax(x) into the equation (2) to obtain the torque suppression time constant t ₁ (x ), and the torque suppression time constant _{t 1} (y) is determined (S53). The CPU 21 substitutes the transferred substance amount M ₂ (x) and the coefficient k(x) corresponding to the acquired load mass M into the equation (4) to determine the variable damping time constant t ₂ (x), and acquires The variable damping time constant _t 2 (y) is determined by substituting the amount of transferred substance M ₂ (y) corresponding to the load M and the coefficient k(y) into the equation (4) (S55). The CPU 21 substitutes the fixed damping frequency Ffix(x) into the equation (5) to determine the fixed damping time constant t ₃ (x), and substitutes the fixed damping frequency Ffix(y) into the equation (5). to determine the fixed damping time constant t ₃ (y) (S57). The CPU 21 calculates the determined torque suppression time constants t ₁ (x), t ₁ (y), variable damping time constants t ₂ (x), t ₂ (y), fixed damping time constants t ₃ (x), t ₃ (y) is stored in the RAM 23 (S59).

The CPU 21 reads one command of the NC program stored in the storage device 24 (S61). The CPU 21 determines whether or not the operation of the machine tool 10 according to the read command is a fast feed operation (S63). When the CPU 21 determines that it is a fast-forward operation (S63: YES), it controls the machine tool 10 so that the machine tool 10 is driven in a fast-forward operation (S65). The details of this process are the same as S33 in FIG. The CPU 21 advances the process to S69. On the other hand, when the CPU 21 determines that the fast-forward operation is not performed (S63: NO), the CPU 21 controls the machine tool 10 so that the machine tool 10 is driven by the normal operation according to the read command (S67). The details of this process are the same as S15 in FIG. The CPU 21 advances the process to S69.

In the process of S61, the CPU 21 determines whether or not the last command of the NC program has been read (S69). When the CPU 21 determines that the last command of the NC program has not been read (S69: NO), the process returns to S61. When the CPU 21 determines in the process of S61 that the last command of the NC program has been read (S69: YES), it ends the main process.

<Other Modifications>
The present invention is not limited to the above embodiments. The number of time constants used for acceleration/deceleration control is not limited to three (torque suppression time constant t ₁ , variable damping time constant t ₂ , fixed damping time constant t ₃ ), and other time constants may be used. good.

The numerical controller 20 determined the torque suppression time constant _t1 based on equation (2), and determined the variable damping time constant _t2 based on equation (4). On the other hand, the numerical controller 20 may determine the torque suppression time constant t ₁ and the variable damping time constant t ₂ by another method. For example, the numerical controller 20 may calculate in advance the torque suppression time constant t ₁ and the variable damping time constant t ₂ for the load masses M of 0 kg, 100 kg, and 250 kg, and store them in the ROM 22 . Hereinafter, the torque suppression time constants t ₁ when the load mass M is 0 kg, 100 kg, and 250 kg are denoted as t ₁ (0), t ₁ (100), and t ₁ (250). The variable damping time constants _t2 when the load M is 0 kg, 100 kg, and 250 kg are expressed as _t2 (0), _t2 (100), and _t2 (250). For example, when the load mass M is a value within the range of 0 to 100 kg (denoted as Ma), the numerical controller 20 controls the torque suppression time constants t ₁ (0) and t ₁ (100), the variable damping time constant t ₂ (0) and t ₂ (100), the torque suppression time constant t ₁ and the variable damping time constant t ₂ are calculated based on the following equations (11-1) and (11-2). You may
t ₁ = (t ₁ (100)-t ₁ (0))×Ma/(100-0) (11-1)
t ₂ = (t ₂ (100)-t ₂ (0))×Ma/(100-0) (11-2)

Similarly, when the load mass M is a value within the range of 100 to 250 kg (denoted as Mb), the numerical controller 20 controls the torque suppression time constants t ₁ (100) and t ₁ (250), the variable damping Through linear interpolation using time constants t ₂ (100) and t ₂ (250), torque suppression time constant t ₁ and variable damping time constant t ₂ are calculated based on the following equations (12-1) and (12-2). may be calculated.
t ₁ = (t ₁ (250) - _{t 1} (100)) x Mb/(250-100) (12-1)
t ₂ = (t ₂ (250) - _{t 2} (100)) x Mb/(250-100) (12-2)

The graph shown in FIG. 4 may be linearly approximated and the approximation function derived in advance. Numerical controller 20 calculates variable damping frequency Fvar by substituting load mass M into the derived approximation function, and determines variable damping time constant _t2 by substituting into equation (4). good.

The numerical controller 20 may perform acceleration/deceleration control using only the first filter FIR1 having the torque suppression time constant _t1 and the second filter FIR2 having the variable damping time constant _t2 . In this case, the numerical controller 20 does not need to use the third filter ₃ having the fixed damping time constant t3. Acceleration/deceleration control may be executed for either the X-axis or the Y-axis, and the other may not be executed. The moving average filter used for acceleration/deceleration processing is not limited to the FIR filter, and may be an infinite impulse response filter (IIR filter). The acceleration/deceleration process may be performed using two or more FIR filters corresponding to the variable damping time constant _t2 and the variable damping time constant _t2 . The acceleration/deceleration process may be performed using two or more FIR filters corresponding to the fixed damping time constant _t3 and the fixed damping time constant _t3 . The time constant of the Y-axis may also be used when performing the acceleration/deceleration control of the X-axis. For example, the torque suppression time constant t ₁ (x) for the X axis, the variable damping time constant t ₂ (x) for the X axis, the variable damping time constant t ₂ (y) for the Y axis, and the fixed X axis Acceleration/deceleration processing may be performed using FIR filters corresponding to the four time constants of the damping time constant t ₃ (x). Similarly, the time constant of the X-axis may also be used when performing the acceleration/deceleration control of the Y-axis. When performing acceleration/deceleration of the Z-axis, the acceleration/deceleration time constant of the X-axis or the Y-axis may be used.

<Others>
The machine tool 1 is an example of the "machine" of the present invention. CPU21 is an example of the "control part" of this invention. CPU21 which processes S25 and S53 is an example of the "first decision part" of the present invention. CPU21 which processes S27 and S55 is an example of the "second decision part" of the present invention. CPU21 which processes S33 and S65 is an example of the "processing part" of the present invention. CPU21 which processes S29 and S57 is an example of the "third decision part" of the present invention. The processing of S25 and S53 is an example of the "first determination step" of the present invention. The processing of S27 and S55 is an example of the "second determination step" of the present invention. The processing of S33 and S65 is an example of the "processing step" of the present invention.

1: Machine tool 4: Tool 9: Spindle 10: Machine tool 13: X-axis motor 14: Y-axis motor 16: Operation panel 20: Numerical controller 21: CPU
50: Table FIR1: First filter FIR2: Second filter FIR3: Third filter Ffix: Fixed damping frequency Fvar: Variable damping frequency M: Load mass t1: Torque suppression time constant t2: Variable damping time constant t3: Fixed damping time constant

Claims (7)

The table is moved by a motor, and the tool mounted on the spindle controls the operation of the machine capable of processing the work material supported by the jig on the table, and the velocity waveform generated from the position command of the table is processed by the filter. In a numerical control device equipped with a control unit capable of executing acceleration/deceleration processing for
The control unit
A first step of determining a torque suppression time constant, which is a time constant corresponding to the maximum torque of the motor that changes according to the load mass, which is the mass of the load including the jig and the work material on the table. a decision unit;
a second determination unit that determines, as a variable damping time constant, a reciprocal of a variable damping frequency corresponding to a vibration frequency specific to the machine that changes according to the load mass;
a third determining unit that determines, as a fixed damping time constant, a reciprocal of a fixed damping frequency corresponding to a vibration frequency unique to the machine that does not change according to the load mass;
A first filter having the torque suppression time constant determined by the first determination unit, a second filter having the variable damping time constant determined by the second determination unit, and the and a processing unit that executes the acceleration/deceleration process using a third filter having a fixed damping time constant . The table is moved by a motor, and the tool mounted on the spindle controls the operation of the machine capable of processing the work material supported by the jig on the table, and the velocity waveform generated from the position command of the table is processed by the filter. In a numerical control device equipped with a control unit capable of executing acceleration/deceleration processing for
The control unit
an acquisition unit that acquires torque and acceleration of the motor when the table is moved;
an estimation unit for estimating a load mass, which is a mass of a load including the jig and the work material on the table, based on the torque and the acceleration acquired by the acquisition unit;
a first determination unit that determines a torque suppression time constant , which is a time constant corresponding to the maximum torque of the motor that changes according to the load mass, based on the load mass estimated by the estimation unit ;
A second determination of determining, as a variable damping time constant, the reciprocal of a variable damping frequency corresponding to a vibration frequency unique to the machine that varies according to the load mass, based on the load mass estimated by the estimator. Department and
Processing for executing the acceleration/deceleration process using a first filter having the torque suppression time constant determined by the first determination unit and a second filter having the variable damping time constant determined by the second determination unit A numerical control device comprising: 3. A numerical controller according to claim 1, wherein said load mass and said variable damping frequency have a non-linear relationship. The table is movable in two intersecting axial directions,
wherein the motor is provided for each shaft in the two axial directions;
The first determination unit determines the torque suppression time constant for each axis,
The second determination unit determines the variable damping time constant for each axis,
4. The numerical controller according to claim 1, wherein the processing unit can execute the acceleration/deceleration process for each of the axes. 5. A numerical controller according to claim 1, wherein said filter is an FIR filter. The table is moved by a motor, and the tool mounted on the spindle controls the operation of the machine capable of processing the work material supported by the jig on the table, and the velocity waveform generated from the position command of the table is processed by the filter. A control method capable of executing acceleration/deceleration processing for
A first step of determining a torque suppression time constant, which is a time constant corresponding to the maximum torque of the motor that changes according to the load mass, which is the mass of the load including the jig and the work material on the table. a decision process;
a second determining step of determining, as a variable damping time constant, the reciprocal of a variable damping frequency corresponding to a vibration frequency specific to the machine that changes according to the load mass;
a third determination step of determining, as a fixed damping time constant, the reciprocal of a fixed damping frequency corresponding to a vibration frequency unique to the machine that does not change according to the load mass;
A first filter having the torque suppression time constant determined by the first determination step, a second filter having the variable damping time constant determined by the second determination step, and the and a processing step of executing the acceleration/deceleration process using a third filter having a fixed damping time constant . The table is moved by a motor, and the tool mounted on the spindle controls the operation of the machine capable of processing the work material supported by the jig on the table, and the velocity waveform generated from the position command of the table is processed by the filter. A control method capable of executing acceleration/deceleration processing for
an acquiring step of acquiring the torque and acceleration of the motor when the table is moved;
an estimation step of estimating a load mass, which is the mass of a load including the jig and the work material on the table, based on the torque and the acceleration acquired in the acquisition step;
a first determination step of determining a torque suppression time constant , which is a time constant corresponding to the maximum torque of the motor that changes according to the load mass, based on the load mass estimated in the estimation step ;
A second determination of determining, as a variable damping time constant, the reciprocal of a variable damping frequency corresponding to the vibration frequency unique to the machine that changes according to the load mass, based on the load mass estimated in the estimation step. process and
A process of executing the acceleration/deceleration process using a first filter having the torque suppression time constant determined by the first determination step and a second filter having the variable damping time constant determined by the second determination step. A control method comprising:

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