JP2022020269A - Control apparatus, machine tool, control method, and control program - Google Patents

Abstract

To provide a control apparatus, machine tool, control method, and control program that can control the machine tool so as to rotate a workbench that holds a work material more appropriately than ever, even when a load is loaded on a machine table.SOLUTION: A control apparatus controls a machine tool comprising: a drive unit for rotating a workbench that fixes a work material around an axis parallel to the horizontal plane; and a control unit for controlling the drive unit. The control apparatus calculates the coefficient of rotational moment of a load loaded on a machine table (S5). The control apparatus corrects a command angle and an amount of angular error due to the load loaded on the machine table when the drive unit is driven in an amount corresponding to the command angle, on the basis of: the coefficient of torsional rigidity of the drive unit; the coefficient of rotational moment calculated in S5; and the command angle commanded by a program to the workbench with respect to the reference plane parallel to the horizontal plane (S2 and S3). The control apparatus drives the drive unit by the amount corresponding to the corrected command angle (S5).SELECTED DRAWING: Figure 5

Description

The present invention relates to control devices, machine tools, control methods, and control programs.

A control device that controls a conventional machine tool defines an internal model of the controlled object, and the physical constants of the internal model (for example, inertia) so as to reduce the error between the output speed and the actual speed when a command is given to the controlled object. ) Is estimated. The control target is, for example, a drive source that inclines the table on which the work material is loaded with respect to the horizontal plane. The control device of Patent Document 1 calculates an estimation error from the current return value and the estimated current value acquired in each predetermined cycle, and uses the speed return value and the estimation error detected in each predetermined cycle to estimate the inertia of the controlled object. And update the estimated friction.

Japanese Unexamined Patent Publication No. 2011-72178

The machine tool base is loaded with a rotary joint for supplying liquids such as cutting fluid and coolant, and a hydraulic rotary cylinder for driving the moving parts of jigs such as chucks that hold the workpiece in a linear direction. You can put on and take off things. In the conventional control device, when a load is added to the table, the physical constants such as inertia change due to the addition of the load, and the difference from the estimated physical constant of the internal model increases. Therefore, the control device may not be able to properly control the machine tool.

An object of the present invention is to provide a control device, a machine tool, a control method, and a control program capable of more appropriately controlling a machine tool that rotates a machine tool that holds a work material even when a load is added to the table. To provide.

The control device according to claim 1 is a control device for controlling a machine tool having a drive unit that rotates a table for fixing a work material about an axis parallel to a horizontal plane and a control unit that controls the drive unit. , The coefficient calculation unit that calculates the rotation moment coefficient, which is the coefficient of the rotation moment of the load added to the table, the torsional rigidity coefficient of the drive unit, the rotation moment coefficient calculated by the coefficient calculation unit, and the program. Based on the commanded angle of the table with respect to the reference plane parallel to the horizontal plane, the correction unit for correcting the command angle and the correction for the angle error caused by adding the load to the table. A drive control unit that drives the drive unit by an amount corresponding to the command angle corrected by the unit is provided. The control device corrects the command angle by the angle error based on the rotational moment coefficient of the load added to the table, the torsional rigidity coefficient of the drive unit, and the command angle of the table with respect to the reference surface. By driving the drive unit in consideration of the influence of the load added to the table, the control device can control the machine tool more appropriately than the conventional device even when the load is added to the table.

The control device according to claim 2 further includes an error calculation unit that calculates the angle error based on the torsional rigidity coefficient, the rotational moment coefficient, and the command angle, and the correction unit obtains the command angle. The angle error calculated by the error calculation unit is used for correction. The control device can simplify the process of correcting the command angle by the angle error, as compared with the device that corrects the command angle by the angle error without calculating the angle error.

The coefficient calculation unit of the control device according to claim 3 uses an output result output to the drive unit according to a predetermined drive condition and an internal model of the drive unit including the rotation moment coefficient as one of a plurality of variables. The rotational moment coefficient is calculated by calculating the plurality of variables so that the error from the derivation result derived by applying to the predetermined driving condition is minimized. The control device can calculate the rotational moment coefficient of the load based on the output result and the derivation result. The controller can calculate the rotational moment coefficient by excluding the influence of variables other than the rotational moment coefficient among the multiple variables of the internal model.

The coefficient calculation unit of the control device according to claim 4 is the first drive unit when the table is rotated at an angle perpendicular to the reference surface without the load being added to the table. One drive amount is acquired, and the second drive amount of the drive unit when the table is rotated at an angle perpendicular to the reference surface with the load added to the table is acquired. The rotation moment coefficient is calculated by integrating the reduction ratio of the drive unit with the difference obtained by subtracting the first drive amount from the second drive amount. The control device can calculate the rotation moment coefficient of the load by a relatively simple process of integrating the reduction ratio of the drive unit into the difference obtained by subtracting the first drive amount from the second drive amount.

The machine tool according to claim 5 comprises a drive unit that rotates a table for fixing a work material about an axis parallel to a horizontal plane, a control unit that controls the drive unit, and any one of claims 1 to 3. It is equipped with a control device. The machine tool has an effect according to the control device according to any one of claims 1 to 3 provided in the machine tool.

The control method according to claim 6 is the control method of a machine tool including a drive unit that rotates a table for fixing a work material around an axis parallel to a horizontal plane and a control unit that controls the drive unit. The program commands a coefficient calculation process for calculating the rotational moment coefficient, which is a coefficient of the rotational moment of the load added to the table, a torsional rigidity coefficient of the drive unit, and the rotational moment coefficient calculated in the coefficient calculation process. In the correction step of correcting the command angle by the angle error due to the addition of the load to the table based on the command angle of the table with respect to the reference plane parallel to the horizontal plane, and the correction step. A drive control step for driving the drive unit by an amount corresponding to the corrected command angle is provided. The control method has the same effect as that of the control device according to claim 1.

The control program according to claim 7 is a control device that controls a machine tool including a drive unit that rotates a table for fixing a work material around an axis parallel to a horizontal plane and a control unit that controls the drive unit. In a control program that can be executed, the coefficient calculation process for calculating the rotational moment coefficient, which is the coefficient of the rotational moment of the load added to the platform, the torsional rigidity coefficient of the drive unit, and the coefficient calculation process. Based on the rotation moment coefficient and the command angle of the table with respect to the reference plane parallel to the horizontal plane, the command angle is corrected by the angle error caused by adding the load to the table. It includes an instruction to cause the control device to execute the correction process for driving the drive unit and the drive control process for driving the drive unit by an amount corresponding to the command angle corrected by the correction process. The control program has the same effect as that of the control device of claim 1.

A perspective view of the machine tool 1. The perspective view of the support device 8. The block diagram which shows the electric composition of a control device 40 and a machine tool 1. The figure which shows the control system of a drive circuit 55. The flow chart of the main process of 1st Embodiment. (A) Schematic diagram of the A-axis pedestal 20 when the A-axis pedestal 20 is 0 (rad) with respect to the reference surface R, (B) The A-axis at the position where the A-axis pedestal 20 is at the command angle K1 with respect to the reference surface R. The schematic diagram of the angle error K2 when rotating a table 20. The functional block diagram which shows the function of the control device 40. The figure of the angular velocity curve and the angular acceleration curve when the two-stage moving average filters FIR1 and FIR2 are applied. The graph which shows the evaluation result of the main process of 1st Embodiment. The flow chart of the coefficient calculation process of the second embodiment. The schematic diagram of the A shaft base 20 when the A shaft base 20 is π / 2 (rad) (perpendicular) with respect to the reference plane R. The flow chart of the main process of the 2nd Embodiment.

The first and second embodiments of the present invention will be described in order with reference to the drawings. The following description uses left and right, front and back, and up and down indicated by arrows in the figure. The left-right direction, the front-back direction, and the up-down direction of the machine tool 1 are the X-axis direction, the Y-axis direction, and the Z-axis direction of the machine tool 1, respectively. The right, forward, and upward directions are positive, and the left, backward, and downward directions are negative. The machine tool 1 shown in FIG. 1 is a multifunction machine capable of cutting and turning a work material W (see FIG. 2) with a tool.

The structure of the machine tool 1 of the first and second embodiments will be described with reference to FIGS. 1 to 3. The machine tool 1 includes a base 2, a Y-axis moving mechanism (not shown), an X-axis moving mechanism (not shown), a Z-axis moving mechanism (not shown), a moving body 15, a vertical column 5, a spindle head 6, and a spindle (not shown). ), A support device 8, a tool changer 9, a control box (not shown), a control device 40 (see FIG. 3), and the like. The base 2 includes a pedestal 11, a main shaft base 12, a right base 13, a left base 14, and the like. The gantry 11 is a substantially rectangular parallelepiped structure that is long in the front-rear direction. The headstock base 12 is formed in a substantially rectangular parallelepiped shape long in the front-rear direction, and is provided behind the upper surface of the gantry 11. The right base 13 is provided on the right front of the upper surface of the gantry 11. The left base 14 is provided on the left front of the upper surface of the gantry 11. The right base 13 and the left base 14 each support the support device 8 on the upper surface.

The Y-axis movement mechanism is provided on the upper surface of the spindle base 12, and includes a Y-axis motor 62 (see FIG. 3) and the like. The Y-axis moving mechanism moves the substantially flat plate-shaped moving body 15 in the Y-axis direction by driving the Y-axis motor 62. The X-axis moving mechanism is provided on the upper surface of the moving body 15 and includes an X-axis motor 61 (see FIG. 3) and the like. The X-axis movement mechanism moves the vertical column 5 in the X-axis direction by driving the X-axis motor 61. The vertical column 5 moves on the base 2 in the X-axis direction and the Y-axis direction by the Y-axis moving mechanism, the moving body 15, and the X-axis moving mechanism. The Z-axis movement mechanism is provided on the front surface of the vertical column 5 and includes a Z-axis motor 63 (see FIG. 3) and the like. The Z-axis movement mechanism moves the spindle head 6 in the Z-axis direction by driving the Z-axis motor 63. The spindle (not shown) is provided inside the spindle head 6, and a tool mounting hole (not shown) is provided in the lower part of the spindle. A tool is mounted in the tool mounting hole. Therefore, the X-axis movement mechanism, the Y-axis movement mechanism, and the Z-axis movement mechanism move the work material W relative to the tool mounted on the spindle in the X-axis direction, the Y-axis direction, and the Z-axis direction, respectively. .. The spindle is rotated by a spindle motor 66 (see FIG. 3) provided on the upper part of the spindle head 6. At this time, the tool provided on the spindle rotates with respect to the work material W.

The tool changer 9 is a substantially annular shape surrounding the vertical column 5 and the spindle head 6. The tool changer 9 changes the tool currently mounted on the spindle while the Z-axis moving mechanism moves up and down the spindle head 6. The control box is attached to the outer wall of a cover (not shown) that covers the machine tool 1. The control device 40 is stored inside the control box. The control device 40 controls the operation of the machine tool 1 based on the NC program. The cover covering the machine tool 1 is provided with an operation panel 10 (see FIG. 3) on the outer wall surface. The operation panel 10 includes an operation unit 18 and a display unit 19. The operation unit 18 makes various settings for the control device 40. The display unit 19 displays various screens, messages, alarms, and the like.

The support device 8 is fixed to the upper surfaces of the right base 13 and the left base 14. As shown in FIG. 2, the support device 8 includes an A-axis base 20, a left-side support base 27, a drive unit 28, a rotary table 29, a C-axis drive unit 30, and the like. The A-axis base 20 can be detachably attached with loads 200 and 300. The load 200 includes a jig 201 added to the A-axis side (base side) with respect to the A-axis pedestal 20, and a work material W. The jig 201 is an instrument for fixing a work material W such as a chuck and a flat jig. The load 300 includes a rotary cylinder and a rotary joint added to the A-axis base 20 on the side opposite to the A-axis side (tail side). The rotary joint supplies liquids such as cutting fluid and coolant. The rotary cylinder drives a movable part of a jig such as a chuck that holds the work material W in a linear direction.

The A-axis base 20 includes a base portion 21, a right connecting portion 22, and a left connecting portion 23. The base portion 21 is a plate-shaped portion having a substantially rectangular shape in a plan view in which the upper surface is parallel to the reference plane R when the angle of the A-axis base 20 with respect to the reference plane R (see FIG. 6) is 0 (rad). The reference plane R is a virtual plane parallel to the horizontal plane. The right connecting portion 22 extends diagonally upward to the right from the right end portion of the base portion 21 and is rotatably connected to the driving portion 28. The right connecting portion 22 has a substantially columnar support shaft 32 protruding to the right from the right end surface thereof. The left connecting portion 23 extends diagonally upward to the left from the left end portion of the base portion 21 and is rotatably connected to the left support base 27 described later. The left connecting portion 23 has a substantially columnar support shaft 31 projecting to the left from its left end surface. The left support base 27 is located on the right side of the A-axis base 20. The left support base 27 rotatably supports the support shaft 31. The bottom of the left support base 27 is fixed to the upper surface of the left base 14 (see FIG. 1).

The drive unit 28 is located on the right side of the A axle base 20. The drive unit 28 includes a right side support base 26, an A-axis motor 65, and the like. The bottom of the right support base 26 is fixed to the upper surface of the right base 13 (see FIG. 1). The right support base 26 rotatably supports the support shaft 32 of the right connecting portion 22 via the A-axis output shaft 67. The support shaft 32 of the right connecting portion 22 and the output shaft of the A-axis motor 65 are connected to each other via the A-axis output shaft 67. When the output shaft of the A-axis motor 65 rotates, the A-axis base 20 rotates integrally with the connecting portions 22 and 23 around the A-axis. The A axis is parallel to the X axis direction and passes through the centers of the support axes 31 and 32 in a side view. The drive unit 28 rotates the work material W with respect to the tool about the A axis. By tilting the A-axis base 20 at an arbitrary angle around the A-axis, the work material W is tilted in an arbitrary direction around the A-axis with respect to the tool mounted on the spindle.

The rotary table 29 is rotatably provided at substantially the center of the upper surface of the table portion 21. The rotary table 29 is formed in a disk shape and is provided substantially in the center of the upper surface of the A-axis table 20. The C-axis drive unit 30 is provided on the lower surface of the base portion 21 and is connected to the rotary table 29 via a hole (not shown) provided in the substantially center of the base portion 21. The C-axis drive unit 30 includes a rotating shaft (not shown), a C-axis motor 64 (see FIG. 3), and the like inside. The axis of rotation extends in a direction orthogonal to the rotary table 29. The rotary shaft is fixed to the rotary table 29. The rotor of the C-axis motor 64 is fixed to the rotating shaft. Therefore, when the C-axis motor 64 rotates the rotation axis, the rotary table 29 rotates about the C-axis. The upper surface of the rotary table 29 fixes the load 200. The C-axis drive unit 30 rotates the work material W with respect to the tool about the C-axis.

With reference to FIG. 3, the electrical configurations of the control device 40 and the machine tool 1 of the first and second embodiments will be described. The control device 40 includes a CPU 41, a ROM 42, a RAM 43, a storage unit 44, an input / output unit 45, and drive circuits 51 to 56. The machine tool 1 includes an X-axis motor 61, a Y-axis motor 62, a Z-axis motor 63, a C-axis motor 64, an A-axis motor 65, a spindle motor 66, and encoders 71 to 76. Hereinafter, when the drive circuits 51 to 56 are not distinguished, they are collectively referred to as the drive circuit 50. When the X-axis motor 61, the Y-axis motor 62, the Z-axis motor 63, the C-axis motor 64, the A-axis motor 65, and the spindle motor 66 are not distinguished, they are collectively referred to as a motor 60. When the encoders 71 to 76 are not distinguished, they are collectively referred to as an encoder 70.

The CPU 41 controls the operation of the machine tool 1. The ROM 42 stores a control program or the like for executing the main processing (see FIGS. 5 and 12) described later. The RAM 43 stores various data generated during execution of various processes. The storage unit 44 stores NC programs and the like. The input / output unit 45 is electrically connected to the drive circuit 50, the encoder 70, the operation unit 18, and the display unit 19, and inputs / outputs various signals between the drive circuit 50, the encoder 70, the operation unit 18, and the display unit 19. conduct.

The drive circuit 50 outputs a pulse signal to the motor 60 based on the command output by the CPU 41. The encoder 70 detects the rotation angle of the output shaft of the corresponding motor 60, and outputs the detection signal to the drive circuit 50 and the input / output unit 45. The motors 60 are all servo motors. The encoder 70 is a general absolute value encoder.

The control system of the drive circuit 55 will be described with reference to FIG. The CPU 41 of the control device 40 generates time-series data (described later) of the target angle for each predetermined cycle based on the A-axis feed command of the NC program, and outputs the angle command corresponding to each data to the drive circuit 55. The angle command indicates the rotation angle of the output shaft of the A-axis motor 65 when the A-axis base 20 is rotated to the target angle indicated by the data. The encoder 75 outputs the current rotation angle information of the output shaft of the A-axis motor 65 to the drive circuit 55 as a return value. The drive circuit 50 controls the drive current output to the A-axis motor 65 based on the return value and the angle command. Specifically, the drive circuit 55 calculates the angle deviation between the return value and the angle command by the adder 50A, and multiplies the angle deviation by the angle proportional gain to calculate the angular velocity command. The drive circuit 55 calculates the angular velocity deviation between the angular velocity command calculated by the adder 50B and the actual angular velocity, that is, the angular velocity return value obtained by differentiating the return value by the differentiator 50C. The drive circuit 55 adds a current command obtained by multiplying the angular velocity deviation calculated by the adder 50D by the angular velocity proportional gain and a current command obtained by integrating the angular velocity deviation with the integrator 50E and multiplying the integration result by the angular velocity integrated gain, and torque. Generate a command. The drive circuit 55 drives the A-axis motor 65 by a pulse signal indicating a torque command.

5 to 8, the main process executed by the CPU 41 of the control device 40 of the first embodiment will be described. The main process is started by the CPU 41 reading and executing the control program stored in the storage unit 44 when the power of the control device 40 is ON.

As shown in FIG. 5, the CPU 41 reads one line of the NC program stored in the storage unit 44 (S1). When the program read in S1 is the A-axis feed command, the CPU 41 calculates the angle error ΔQ (θ) (rad) according to the command angle θ (rad) instructed by the A-axis feed command (S2). The command angle θ is represented by the angle of the A-axis pedestal 20 with respect to the reference plane R. As shown in FIG. 6A, when the angle θ is 0, the surface of the A-axis pedestal 20 facing the A-axis is parallel to the reference surface R, and the center of gravity _Cg of the A-axis pedestal 20 is It is located vertically downward with respect to the A axis. The angle is a positive angle when the A-axis base 20 rotates counterclockwise when viewed from the left side from the position shown in FIG. 6 (A). The A-axis feed command instructs the A-axis pedestal 20 to rotate around the A-axis up to the command angle θ of the A-axis pedestal 20 with respect to the reference plane R parallel to the horizontal plane. The angle error ΔQ (θ) is an angle error due to the addition of the load to the A-axis pedestal 20 when the drive unit 28 is driven by the amount corresponding to the command angle θ specified by the A-axis feed command. ..

The CPU 41 calculates the angle error ΔQ (θ) using the equation (1). In the formula (1), E (deg / N · m) is a torsional rigidity coefficient of the drive unit 28, which is a value peculiar to the drive unit 28. E is stored in advance by the storage unit 44. F _θ sin (θ) (Nm) is the total rotational moment of the load added to the A-axis base 20, the C-axis drive unit 30, and the A-axis base 20. F _θ (Nm) is a coefficient for calculating the rotational moment according to the command angle θ, and is stored by the storage unit 44. The rotational moment (Nm) is calculated by multiplying the rotational moment coefficient Fθ (Nm) by the sine of the command angle _θ . The rotation moment coefficient F _θ is calculated by the CPU 41 by the previous process of S5 executed with the load added to the A axle base 20, and stored in the storage unit 44 in S10. When the CPU 41 has not executed the previous S5, the storage unit 44 stores the initial value of the rotation moment coefficient F _θ . The initial value of the rotational moment coefficient F _θ is a coefficient for calculating the rotational moment when no load is added to the A-axis pedestal 20, and is the rotational moment coefficient F _{θ 1} of the A-axis pedestal 20 and the C-axis drive unit 30. be.
ΔQ (θ) = E × F _θ sin (θ) ・ ・ ・ Equation (1)

As shown in FIG. 6B, when the command angle θ is K1 (rad), the CPU 41 calculates, for example, the angle error as K2 (rad). The CPU 41 uses the angle error ΔQ (θ) calculated in S2 to correct the command angle θ (S3). For example, the CPU 41 corrects the command angle θ by subtracting the angle error ΔQ (θ) from the command angle θ. The CPU 41 may omit S2 and S3 when the program read in S1 is not an A-axis feed command.

The CPU 41 determines whether or not the command of the NC program read in S1 is an A-axis fast-forward command (S4). The A-axis fast-forward command instructs the A-axis base 20 to rotate around the A-axis under fast-forward conditions up to the command angle θ of the A-axis base 20 with respect to the reference plane R parallel to the horizontal plane. The fast-forward condition is a condition in which the motor 60 rotates at the maximum angular velocity _Vmax that can be set in the machine tool 1. When the CPU 41 determines that the NC program command read in S1 is an A-axis fast-forward command (S4: YES), the CPU 41 performs A-axis fast-forward regarding the command angle θ corrected in S3 and variables of the internal model of the drive unit 28. The calculation is executed (S5). The CPU 41 stores the time-series data of the target angle output to the drive circuit 55 in response to the A-axis fast-forward command corrected in S5 based on the time constants T1 and T2 of FIR1 and FIR2 (see FIG. 8) stored in the storage unit 44. The A-axis fast forward is executed by outputting the angle command corresponding to each data of the time series data of the determined and determined target angle to the drive circuit 55. The CPU 41 applies the torque u output by the drive circuit 55 to the A-axis motor 65 and the return value x of the encoder 75 to the evaluation function of the internal model described later, and calculates a plurality of variables of the internal model of the drive unit 28. do.

A-axis fast-forwarding based on the A-axis fast-forwarding command will be described with reference to FIGS. 7 and 8. As shown in FIG. 7, the CPU 41 acquires an A-axis fast-forward command from the read NC program in S1 (P1). Since the CPU 41 rotates the A-axis base 20 to the command angle θ corrected by S3, the time-series data of the target angle is determined (P2). The CPU 41 outputs an angle command corresponding to the target angle data to the drive circuit 55 at a predetermined cycle. The angle command indicates the rotation angle and driving conditions of the A-axis motor 65 for rotating the A-axis base 20 to the target angle.

As shown in FIGS. 8A and 8B, when the CPU 41 rotates the A-axis platform 20 at a constant maximum angular velocity V _max up to the command angle θ of the A-axis fast-forward command at the angular velocity of the A-axis platform 20. Set a waveform (called an angular velocity waveform) that indicates a series change. Next, the CPU 41 applies two types of moving average filters FIR1 and FIR2 in order to the angular velocity waveform shown in FIG. 8B to smooth the change in the angular velocity indicated by the angular velocity waveform. FIR1 is applied to the angular velocity waveform shown in FIG. 8B, and the angular velocity accelerates from 0 to V _max during the period of the time constant T1 of FIR1, maintains the maximum angular velocity V _max , and then the angular velocity is increased during the period of the time constant T1. The angular velocity waveform is smoothed so as to decelerate from V _max to 0. FIR2 is applied to the angular velocity waveform to which FIR1 shown in FIG. 8C is applied, and as shown in FIG. 8D, the change in the angular velocity is smoothed at the start part and the end part of the acceleration period and the deceleration period in the angular velocity waveform. do. At this time, the lengths of the acceleration period and the deceleration period of the angular velocity waveform are increased by the time constant T2 of FIR2, respectively, and are set to (T1 + T2).

The CPU 41 determines the target angle for each predetermined cycle based on the angular velocity waveform of FIG. 8D obtained by applying FIR1 and FIR2. The CPU 41 outputs an angle command r corresponding to the determined target angle data to the drive circuit 55 at a predetermined cycle. The drive circuit 55 drives the A-axis motor 65 based on the angle command r output by the CPU 41 at a predetermined cycle. The A-axis motor 65 rotates the A-axis base 20 around the A-axis to a target angle. The A-axis pedestal 20 repeats the operation of rotating to a target angle at predetermined intervals. The A-axis platform 20 finally reaches the command angle specified by the A-axis fast-forward command.

The CPU 41 calculates a plurality of variables of the internal model of the support device 8 as follows. The internal model includes the rotational moment (uneven load) of the load added to the A-axis pedestal 20 as one of a plurality of variables. The rotation moment of the load fluctuates according to the rotation angle of the A-axis base 20 of the support device 8, and indicates a force or torque for rotating the A-axis motor 65 in a direction for eliminating the rotation moment of the load. As shown in FIG. 6A, when the center of gravity C _g of the A-axis pedestal 20 is defined, a force due to the rotational moment of the load acts vertically downward on the center of gravity C _g of the A-axis pedestal 20.

式（２）でｆは式（３）の関係を満たす。Ｆ_Ｃは支持装置８に関するクーロン摩擦係数（Ｎ・ｍ）である。ｓｉｇｎ関数は、実数に対しその符号に応じて１、－１、０の何れかを返す符号関数である。Ｄは支持装置８に関する粘性摩擦係数（Ｎ・ｍ／（ｒａｄ／ｓ））である。

The internal model of the support device 8 may be appropriately set by using a plurality of variables, and is represented by, for example, the equation (2). In equation (2), θ is the angle of the A-axis platform 20 with respect to the reference plane R. θ (one dot with superscript) indicates the one-time derivative of the angle (angular velocity (rad / s)). θ (two dots with a top) indicates the double time derivative of the angle (angular acceleration (rad / s ² )). u (N · m) is the torque output by the drive circuit 55 to the A-axis motor 65, and J (kg · m ² ) is the moment of inertia with respect to the support device 8.

In equation (2), f satisfies the relationship of equation (3). FC is the Coulomb friction coefficient ( _Nm ) with respect to the support device 8. The sign function is a sign function that returns any of 1, -1, and 0 for a real number depending on its sign. D is a viscous friction coefficient (Nm / (rad / s)) with respect to the support device 8.

The torque u output by the drive circuit 55 can be estimated using the internal model of the equation (2). The estimation error e (ρ) can be derived by Eq. (4). ρ is a variable to be calculated, x is a return value from the encoder 75, and G _LPF is a low-pass filter for removing differential noise. The superscript T indicates that it is a transposed matrix. For example, ρ ^T represents the transposed matrix of ρ.
e (ρ) = GLPFu-ρ ^T x ... Equation (4)
In equation (4), ρ and x satisfy the relationship between equations (5) and (6). A plurality of variables represented by ρ (moment of inertia J, coefficient of viscous friction D, coefficient of Coulomb friction FC, coefficient of rotational moment _{F θ} ) are also called model variables.

As shown in FIG. 7, the CPU 41 determines ρ at which the evaluation function | e (ρ) | ² is minimized by the sequential least squares method (P3). When the return value acquired this time is the kth return value and the return value acquired last time is the (k-1) th return, the variable to be calculated this time is ρ (expressed as ρ ^) with circumflex (k). When the current estimation error e (ρ) is set to ε (k) and the current covariance matrix is set to P (k), ρ ^ (k), ε (k), and P (k) are given by Eq. (7). It is expressed by the formula (9).

ρ ^ (k), ε (k), P (k) are all based on the equations (7) to (9), and the previous ρ ^ (k-1), ε (k-1), P (k) It can be calculated sequentially using k-1), the current torque u (k), and the return value x (k). Therefore, the CPU 41 applies the torque u output by the drive circuit 55 to the A-axis motor 65 and the return value x of the encoder 75 to the internal model, and calculates equations (7) to (9) every predetermined cycle. The evaluation function | e (ρ) | ² is minimized ρ, that is, the model variables (moment of inertia J, viscous friction coefficient D, Coulomb friction coefficient FC, rotational moment coefficient _{F θ} ) are sequentially calculated (P3). The CPU 41 returns the process to S1.

When the CPU 41 determines that the NC program command read out is not an A-axis fast-forward command (S4: NO), the CPU 41 determines whether the NC program command read in S1 is a command to stop the operation of the machine tool 1. Judgment (S7). When the CPU 41 determines that it is not a command to stop the operation of the machine tool 1 (S7: NO), the CPU 41 executes a process according to the command read in S1 (S8), and returns the process to S1. At the time of the command and determination to stop the operation of the machine tool 1 (S7: YES), the CPU 41 determines whether or not the model variable has been calculated in S5 (S9). When the model variable has been calculated in S5 (S9: YES), the CPU 41 stores the model variable calculated in S5 in the storage unit 44 and updates the model variable (S10, P4). When the model variable has not been calculated in S5 (S9: NO) or next to S10, the CPU 41 ends the main process.

The evaluation result of the main treatment of the first embodiment will be described with reference to FIG. In the evaluation, by executing the main process of the first embodiment, the machine tool 1 that rotates the A-axis pedestal 20 that holds the work material W even when the load is added to the A-axis pedestal 20 is the A-axis. It was confirmed whether the fast-forward command can be rotated to the command angle θ more appropriately than before. An example is a case where the machine tool 1 executes the main process of the first embodiment, and a comparative example is a case where the machine tool 1 does not execute S2 and S3 of the main processes. The examples and comparative examples were driven under the following five conditions, and the relationship between the command angle and the error was compared. The error is an angle obtained by subtracting the command angle (rad) from the actual angle (rad) of the A-axis pedestal 20 after rotating the A-axis pedestal 20 in S5. The first condition is a condition in which no load is added. The second condition is a condition in which the load A1 is added to the tail side of the A shaft base 20. The third condition is a condition in which the load A2 is added to the tail side of the A-axis pedestal 20. The fourth condition is a condition in which the load A3 is added to the tail side of the A-axis pedestal 20. The fifth condition is a condition in which the load A4 is added to the base side of the A-axis base 20. The weight of the load under each condition is a value in the range of 35 to 600 (N), and the value is larger in the order of the load A1 to A4.

The relationship between the command angle and the error in the comparative example is shown in FIG. 9 (A), and the relationship between the command angle and the error in the embodiment is shown in FIG. 9 (B). The vertical axis of FIGS. 9A and 9B indicates the error (rad) as a relative value using α, and the horizontal axis indicates the command angle (rad). The error (rad) does not exceed the value of the command angle (rad). The relationship between the command angle of the first condition to the fifth condition and the error is shown in the results 81 to 85. As shown in FIGS. 9 (A) and 9 (B), the first condition shown in the result 81 in both the comparative example and the embodiment is the absolute value of the error in the range of the command angle of −π / 6 to 2π / 3 (rad). Fits in α. In the comparative example, in the second condition shown in the result 82, the third condition shown in the result 83, and the fourth condition shown in the result 84, the larger the weight of the load, the larger the error than the condition where the weight of the load is small. Moreover, in the range of the command angle from −π / 6 to π / 2 (rad), the larger the absolute value of the command angle, the larger the error than the case where the absolute value of the command angle is small. In the case of the fifth condition shown in the result 85, the larger the absolute value of the command angle is, the larger the absolute value of the error is than the case where the absolute value of the command angle is small. On the other hand, in the embodiment, the angle is −π / 6 to 2π under any of the second condition shown in the result 82, the third condition shown in the result 83, the fourth condition shown in the result 84, and the fifth condition shown in the result 85. In the range of / 3 (rad), the absolute value of the error falls within α. From the above, the control device 40 of the first embodiment rotates the A-axis pedestal 20 that holds the work material W even when the loads 200 and 300 are added to the A-axis pedestal 20 by executing the main process. It was confirmed that the machine tool 1 can be controlled more appropriately than before. The control device 4 holds the work material W in both the case where the load 200 is added to the base side of the A shaft base 20 and the case where the load 300 is added to the tail side of the A shaft base 20. It was confirmed that the machine tool 1 that rotates the machine tool 1 can be appropriately controlled.

A coefficient calculation process executed by the CPU 41 of the control device 40 of the second embodiment will be described with reference to FIGS. 10 and 11. The coefficient calculation process is started by the CPU 41 reading and executing the control program stored in the storage unit 44 when the power of the control device 40 is turned on and the operator inputs a start instruction.

As shown in FIG. 10, the CPU 41 drives the A-axis motor 65 without adding a load to the A-axis pedestal 20, and the A-axis pedestal 20 has an angle of π / 2 (rad) with respect to the reference surface R. 20 is rotated (S21). As shown in FIG. 11, when the CPU 41 determines that the angle of the A-axis base 20 with respect to the reference surface R is π / 2 (rad) based on the output value of the encoder 75, the CPU 41 stops driving the A-axis motor 65. When the angle θ is π / 2 (rad), the surface of the A-axis pedestal 20 facing the A-axis is perpendicular to the reference surface R, and the center of gravity C _g of the A-axis pedestal 20 is on the A-axis. On the other hand, it is located in front. The CPU 41 acquires the first drive amount of the A-axis motor 65 when the A-axis pedestal 20 is rotated at an angle at which the A-axis pedestal 20 is perpendicular to the reference surface R without adding a load to the A-axis pedestal 20. (S22). The CPU 41 drives the A-axis motor 65 and rotates the A-axis pedestal 20 to an angle at which a load is added to the A-axis pedestal 20 (S23). The position where the load is added (fixed) to the A-axis pedestal 20 may be appropriately determined. For example, the angle of the A-axis pedestal 20 with respect to the reference surface R is 0 (rad).

The CPU 41 determines whether or not a load is added to the A axle base 20 (S24). The operator may add the load to the A-axis pedestal 20, and after adding the load to the A-axis pedestal 20, the operator operates the operation unit 18 to input an end signal indicating that the fixing work is completed. You may. The robot may fix the load to the A-axis pedestal 20, and the robot may input an end signal to the control device 40 after fixing the load to the A-axis pedestal 20. The CPU 41 determines whether or not the load is fixed to the A-axle base 20 depending on whether or not the end signal is detected. The CPU 41 waits in S24 until the load is fixed to the A axle base 20 (S24: NO). When the CPU 41 detects that the load is fixed to the A-axis 20 (S24: YES), the CPU 41 drives the A-axis motor 65 with the load added to the A-axis 20 as in S21. The A-axis pedestal 20 is rotated to a position of π / 2 (rad) at an angle of the A-axis pedestal 20 with respect to the reference plane R (S25). The CPU 41 sets the second drive amount of the A-axis motor 65 when the A-axis pedestal 20 is rotated at an angle at which the A-axis pedestal 20 is perpendicular to the reference surface R with the load added to the A-axis pedestal 20. Acquire (S26). The CPU 41 calculates the rotational moment coefficient of the load by integrating the reduction ratio of the A-axis motor 65 into the difference obtained by subtracting the first drive amount acquired in S22 from the second drive amount acquired in S26 (S28). The reduction ratio of the A-axis motor 65 is stored in the storage unit 44 in advance. The CPU 41 stores the calculated rotation moment coefficient of the load in the storage unit 44. The CPU 41 ends the coefficient calculation process.

With reference to FIG. 12, the main process executed by the CPU 41 of the control device 40 of the second embodiment will be described. The main process is started by the CPU 41 reading and executing the control program stored in the storage unit 44 when the power of the control device 40 is turned on. In FIG. 12, the same reference numerals are given to the same processes as those of the main process of the first embodiment of FIG. As shown in FIG. 12, the main process of the second embodiment is different from the main process of the first embodiment in that the processes of S32 and S35 are executed instead of the processes of S2 and S55 and the processes of S9 and S10 are not executed. Different from each other, the other treatments are the same as the main treatments of the first embodiment. Hereinafter, the processes of S32 and S35, which are different from those of the first embodiment, will be described.

The CPU 41 calculates the angle error ΔQ (θ) using the rotational moment of the load when the angle of the A-axis base 20 with respect to the reference plane R calculated in S28 after S1 is π / 2 (rad) (S32). .. The CPU 41 sets the rotational moment of the load when the angle of the A shaft base 20 with respect to the reference surface R calculated in S28 is π / 2 (rad) as the rotational moment coefficient F _θ2 , and the rotational moment coefficient F _θ of the equation (1). The angle error ΔQ (θ) is calculated by using the rotational moment coefficient F _θ2 instead of. Similar to the first embodiment, the CPU 41 corrects the command angle θ by using the angle error ΔQ (θ) calculated in S32 (S3).

When the CPU 41 determines that the command of the NC program read out is the A-axis fast-forward command (S4: YES), the CPU 41 executes the A-axis fast-forward regarding the command angle θ corrected in S3 (S35). The CPU 41 stores the time-series data of the target angle output to the drive circuit 55 in response to the A-axis fast-forward command corrected in S3 based on the time constants T1 and T2 of FIR1 and FIR2 (see FIG. 8) stored in the storage unit 44. Fast-forwarding is executed by determining and outputting the time-series data of the determined target angle to the drive circuit 55. The CPU 41 is set in advance and the time constants T1 and T2 stored in the storage unit 44 are used to determine the angle command r. The CPU 41 does not execute the process of calculating a plurality of variables of the internal model of the first embodiment. From the above, by the main processing of the second embodiment, the CPU 41 can correct the command angle θ by using the rotation moment of the load calculated by the coefficient calculation processing performed separately from the main processing. Although not shown, the control device 40 of the second embodiment shows the same evaluation result as the evaluation result of the control device 40 of the first embodiment of FIG. 9 by executing the main process.

In the first and second embodiments, the machine tool 1, the A shaft base 20, the control device 40, and the CPU 41 are examples of the machine tool, the base, the control device, and the control unit of the present invention. The A-axis motor 65 is an example of the drive unit of the present invention. P3 and S28 of S5 are examples of the coefficient calculation process and coefficient calculation process of the present invention, and the CPU 41 that performs P3 and S28 of S5 is an example of the coefficient calculation unit of the present invention. S2 and S32 are examples of the error calculation process and error calculation processing of the present invention, and the CPU 41 that performs S2 and S32 is an example of the error calculation unit of the present invention. S3 is an example of the correction process and correction processing of the present invention, and the CPU 41 performing S3 is an example of the correction unit of the present invention. S5 and S35 are examples of the drive control process and drive control process of the present invention, and the CPU 41 that performs S5 and S35 is an example of the drive control unit of the present invention.

The control device 40 of the first and second embodiments has a drive unit 28 that rotates the A-axis base 20 that fixes the work material W around an axis parallel to the horizontal plane, and a CPU 41 that controls the drive unit 28. The machine tool 1 provided is controlled. The CPU 41 calculates the rotational moment coefficient of the load added to the A axle base 20 (P3, S28 in S5). The CPU 41 is based on the torsional rigidity coefficient E of the drive unit 28, the calculated rotational moment coefficient of the load, and the command angle of the A-axis base 20 with respect to the reference plane R parallel to the horizontal plane, which is commanded by the NC program. Is corrected for the command angle by the angle error due to the addition of the A-axis base 20 (S2, S32, S3). The CPU 41 drives the drive unit 28 by an amount corresponding to the command angle corrected in S3 (S5, S35). The control device 40 and the machine tool 1 have an angle error command angle based on the rotational moment coefficient of the load added to the A shaft base 20, the torsional rigidity coefficient E of the drive unit 28, and the command angle of the A shaft base 20 with respect to the reference surface R. Is corrected (S3). Therefore, the control device 40 drives the drive unit 28 in consideration of the influence of the load added to the A-axis pedestal 20, so that even when the load is added to the A-axis pedestal 20, the control device 40 works more appropriately than the conventional device. Machine 1 can be controlled.

The CPU 41 of the control device 40 of the first and second embodiments is due to the fact that the load is added to the A shaft base 20 based on the torsional rigidity coefficient E of the drive unit 28, the rotational moment coefficient, and the command angle. Calculate the angular error (S2, S32). The CPU 41 corrects the command angle with the angle error calculated in S2 (S3). The control device 40 can simplify the process of correcting the command angle by the angle error as compared with the device that corrects the command angle by the angle error without calculating the angle error.

The CPU 41 of the control device 40 of the first embodiment defines an output result output to the drive unit 28 according to a predetermined drive condition and an internal model of the drive unit 28 including a rotation moment coefficient as one of a plurality of variables. The rotational moment coefficient of the load is calculated by calculating a plurality of variables so as to minimize the error from the derivation result derived by applying the drive condition (A-axis fast forward command) (S5). The control device 40 and the machine tool 1 of the first embodiment can calculate the rotation moment coefficient of the load based on the output result and the derivation result. The control device 40 can calculate the rotation moment coefficient by excluding the influence of variables other than the rotation moment coefficient among the plurality of variables of the internal model.

The CPU 41 of the control device 40 of the second embodiment is driven when the A-axis pedestal 20 is rotated at an angle such that the A-axis pedestal 20 is perpendicular to the reference surface R in a state where no load is added to the A-axis pedestal 20. Acquire the first drive amount of the unit 28 (S22). The CPU 41 acquires the second drive amount of the drive unit 28 when the A-axis pedestal 20 is rotated at an angle at which the A-axis pedestal 20 is perpendicular to the reference surface R with the load added to the A-axle pedestal 20. (S26). The CPU 41 calculates the rotational moment coefficient of the load by integrating the reduction ratio of the drive unit 28 into the difference obtained by subtracting the first drive amount acquired in S22 from the second drive amount acquired in S26 (S28). The control device 40 and the machine tool 1 of the second embodiment perform a relatively simple process of integrating the reduction ratio of the drive unit 28 into the difference obtained by subtracting the first drive amount from the second drive amount, and the rotational moment of the load. The coefficient can be calculated.

The present invention is not limited to the above embodiment. The control device 40 may be provided separately from the machine tool 1 not only when it is provided in the machine tool 1. For example, the control device 40 may be a device (PC, dedicated machine, etc.) connected to the machine tool 1.

Although the control device 40 of the first embodiment shows the determination of the model variables of the internal model regarding the drive unit 28, the shaft (unbalanced load) that receives the rotational moment (uneven load) of the load even in a machine having a machine configuration different from that of the machine tool 1 ( For example, it can be applied to a drive unit that rotates the A-axis base 20 around (C-axis). The method of correcting the command angle using the rotational moment coefficient of the load may be appropriately changed. The rotation moment coefficient F _θ is the sum of the rotation moment coefficient F _θ1 of the A-axis base 20 and the C-axis drive unit 30 and the rotation moment coefficient F _θ2 of the loads 200 and 300 added to the A-axis base 20. The angular error is caused by the rotational moments of all the elements rotating around the A axis. Therefore, as in the first embodiment, the control device 40 calculates the angle error using the rotation moment coefficient F _θ corresponding to all the elements rotating around the A axis including the loads 200 and 300 added to the A axle base 20. You may. When the rotational moment coefficient F _θ1 of the A-axis pedestal 20 and the C-axis drive unit 30 is used as an eigenvalue of the machine tool 1 and separately corrected, the control device 40 uses the load 200 added to the A-axis pedestal 20 as in the second embodiment. , 300 may be used to calculate the angular error using the rotational moment coefficient F _θ2 . For example, when the control device 40 corrects the pitch error at the time of manufacturing separately from the correction based on the rotation moment coefficient of the load, the CPU 41 of the control device 40 adds the angle error to the pitch error to obtain the pitch error. At the time of correction, the angle error may be corrected. When the command angle is θ and the command angle after correction is θa, the CPU 41 of the control device 40 calculates θa satisfying the equation (10), thereby performing the angle error and the command angle without calculating the angle error. θ may be corrected.
θa + E × F _θ sin (θa) = θ ・ ・ ・ Equation (10)

The variables of the internal model and the internal model may be changed as appropriate according to the configuration of the controlled object. The CPU 41 may appropriately change the processing based on the calculated model variables. The control device 40 may execute feedforward control in addition to feedback control based on the return value output by the encoder 70. At this time, the CPU 41 may optimize the feedforward control variable with the determined model variable. For example, the CPU 41 may optimize control variables such as the angular proportional gain, the angular velocity proportional gain, and the angular velocity integrated gain of the feedback control performed by the drive circuit 55. At this time, the control device 40 can control the machine tool 1 at high speed and with high accuracy. The predetermined drive conditions of the first embodiment may be appropriately changed, and for example, the CPU 41 may calculate model variables when the command indicated by the NC program acquired in S1 is the A-axis cutting feed command. The A-axis cutting feed command is a command of the NC program that moves the tool relative to the work material W attached to the A-axis base 20 around the A-axis under the cutting feed conditions. The cutting feed condition is a condition in which the motor 60 rotates at a predetermined cutting speed smaller than the maximum angular velocity _Vmax that can be set by the machine tool 1. At least one of S21 and S25, the operator may manually move the A-axis base 20 to a position of π / 2 (rad) (perpendicular) with respect to the reference plane R.

1: Machine tool 20: A shaft base 40: Control device 41: CPU
44: Storage unit 55: Drive circuit 65: A-axis motor 75: Encoder R: Reference plane

Claims (7)

In a control device that controls a machine tool having a drive unit that rotates a table for fixing a work material around an axis parallel to a horizontal plane and a control unit that controls the drive unit.
A coefficient calculation unit that calculates the rotational moment coefficient, which is the coefficient of the rotational moment of the load added to the table,
The load is loaded based on the torsional rigidity coefficient of the drive unit, the rotational moment coefficient calculated by the coefficient calculation unit, and the command angle of the table with respect to the reference plane parallel to the horizontal plane, which is commanded by the program. A correction unit that corrects the command angle by the amount of the angle error caused by adding to the table, and
A control device including a drive control unit that drives the drive unit by an amount corresponding to the command angle corrected by the correction unit. An error calculation unit for calculating the angle error based on the torsional rigidity coefficient, the rotational moment coefficient, and the command angle is further provided.
The control device according to claim 1, wherein the correction unit corrects the command angle with the angle error calculated by the error calculation unit. The coefficient calculation unit applies the output result output to the drive unit according to the predetermined drive condition and the internal model of the drive unit including the rotation moment coefficient as one of a plurality of variables to the predetermined drive condition. The control device according to claim 1 or 2, wherein the rotational moment coefficient is calculated by calculating the plurality of variables so as to minimize the error from the derivation result derived in the above. The coefficient calculation unit is
The first drive amount of the drive unit when the table is rotated at an angle such that the table is perpendicular to the reference surface without adding the load to the table is acquired.
The second drive amount of the drive unit when the table is rotated at an angle such that the table is perpendicular to the reference surface with the load added to the table is acquired.
The control device according to claim 1 or 2, wherein the rotation moment coefficient is calculated by integrating the reduction ratio of the drive unit into the difference obtained by subtracting the first drive amount from the second drive amount. A drive unit that rotates the table for fixing the work material around an axis parallel to the horizontal plane,
A machine tool comprising a control unit for controlling the drive unit and the control device according to any one of claims 1 to 4. In a machine tool control method including a drive unit that rotates a table for fixing a work material around an axis parallel to a horizontal plane and a control unit that controls the drive unit.
A coefficient calculation step for calculating the rotation moment coefficient, which is a coefficient of the rotation moment of the load added to the table, and
The load is loaded based on the torsional rigidity coefficient of the drive unit, the rotational moment coefficient calculated in the coefficient calculation step, and the command angle of the table with respect to the reference plane parallel to the horizontal plane, which is commanded by the program. A correction step that corrects the command angle by the amount of the angle error caused by adding to the table, and
A control method comprising a drive control step for driving the drive unit by an amount corresponding to the command angle corrected in the correction step. In a control program that can be executed by a control device that controls a machine tool having a drive unit that rotates a table for fixing a work material around an axis parallel to a horizontal plane and a control unit that controls the drive unit.
Coefficient calculation processing for calculating the rotational moment coefficient, which is the coefficient of the rotational moment of the load added to the table, and
The load is loaded based on the torsional rigidity coefficient of the drive unit, the rotational moment coefficient calculated by the coefficient calculation process, and the command angle of the table with respect to the reference plane parallel to the horizontal plane, which is commanded by the program. A correction process that corrects the command angle by the amount of the angle error caused by adding to the table, and
A control program comprising an instruction to cause the control device to execute a drive control process for driving the drive unit by an amount corresponding to the command angle corrected by the correction process.

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