JP4299865B2 - Machine tool control apparatus and control method - Google Patents

Description

  The present invention relates to control of a machine tool. In particular, the present invention relates to a control device and a control method for controlling a feed control axis and a rotation control axis of a machine tool including a rotation control axis that is fed along the feed control axis.

  In a machine tool, a feed control shaft that performs a linear feed operation or a rotary feed operation, and a rotation control shaft that is installed on the feed control shaft and is fed along the feed control axis and performs a rotation indexing operation The configuration is known. Examples of the structure carried on the feed control shaft include a linear feed stand and a rotary feed stand, and examples of the structure carried on the rotation control shaft include a rotary indexing table and a turret tool post.

  In this type of machine tool, the feed control shaft and the rotation control shaft exert mechanical influences (that is, interference) caused by their operations on the other party, so that the stability of the position control of each control shaft deteriorates. As a result, there is a concern that the machining accuracy of the workpiece is lowered. Conventionally, in the technical fields other than machine tools, several measures for eliminating interference between control axes having such mechanical correlation have been proposed.

  For example, Patent Document 1 discloses a configuration that mechanically prevents an optical system from vibrating due to a reaction force exerted on a stator by a movable element of a linear motor for driving a stage in a stage apparatus incorporated in an exposure apparatus. . This stage device includes a reaction device that generates a force on the stator that cancels the reaction force from the mover. Since the reaction device controls the operation of the stator based on the detection value of the position detector that detects the actual displacement of the stator, it accurately eliminates error factors other than the reaction force and moves the stator to a predetermined position. Can be held stably.

  Patent Document 2 discloses a control device that removes interference between joints (that is, control axes) by feedback compensation in an articulated robot. In this control device, the interference torque value generated in each control axis is calculated, and the nonlinear disturbance torque applied to each control axis is estimated by the state observation means as a correction value, and the torque is determined by the interference torque value and the correction value. The command is corrected.

  Further, in Patent Document 3, in an industrial multi-axis robot having a spring element such as a speed reducer on each control axis, a state observation means is arranged on each axis to estimate a torsion angle between the motor and the load. A control device is disclosed that calculates an interference force using the estimated twist angle and corrects a torque command to the electric motor based on the interference force.

JP 2000-243811 A Japanese Unexamined Patent Publication No. Sho 63-314606 JP-A-9-222910

  In the stage device described in Patent Document 1, a stator that should be originally fixed and supported is intentionally mounted on a movement control shaft (reaction device) in order to cancel the reaction force exerted on the stator by the mover of the linear motor. Therefore, the relationship between the linear feed control axis of the mover and the movement control axis of the stator is slightly different from the relationship between the feed control axis and the rotation control axis of the machine tool described above, which is the subject of the present invention. is there. In addition, in order to eliminate various error factors when controlling the movement of the stator, a configuration is adopted in which the actual variation of the stator is measured by the position detector. In addition to being concerned about the increased cost of machine tool equipment, it is necessary to secure the location and reliability of the position detector in machine tools that are often placed in poor environments. Problems arise in terms of maintenance. Furthermore, it is difficult to apply the method of correcting the command value to the stator based on the actual measurement value of the displacement of the stator to high-speed and high-precision positioning control of the movable part in a general machine tool.

  Also in the robot control apparatus described in Patent Documents 2 and 3, as various data necessary for calculating the interference force and correcting the command value, data representing the state in which the motor is actually operating (that is, the state quantity) ) Is used. Such a configuration is effective in controlling a robot whose arm operation is slower than the operation of a movable part of a general machine tool and the required positional accuracy is lower than that of a machine tool. It is still difficult to adapt to the control of machine tools that require high-speed and high-precision positioning.

  It is an object of the present invention to provide an interference between a feed control axis and a rotation control axis in a control device for controlling the feed control axis and the rotation control axis of a machine tool having a rotation control axis that is fed along the feed control axis. It is an object of the present invention to provide a control device that can accurately and stably control the operation of each control axis without delay and can realize stable and highly accurate operation control of each control axis.

  Another object of the present invention is to provide a control method for controlling a feed control axis and a rotation control axis of a machine tool having a rotation control axis that is fed along the feed control axis. It is an object of the present invention to provide a control method that can accurately eliminate the interference without delay and realize stable and highly accurate operation control of each control axis, thereby improving the machining accuracy of the workpiece.

In order to achieve the above object, the invention described in claim 1 is directed to a feed operation of a feed control axis and a rotation control axis of a machine tool including a feed control axis and a rotation control axis fed along the feed control axis. In the control device for controlling the rotation operation of the rotation control shaft, the feed control shaft is controlled based on the position command commanded to at least one of the feed control shaft and the rotation control shaft and the position and mass information of the eccentric load carried by the rotation control shaft. Calculate the force exerted on the rotation control shaft by the thrust applied to the eccentric load during the feed operation, or the centripetal force and tangential force applied to the eccentric load while the rotation control shaft is rotating on the feed control shaft. An interference estimation unit that estimates interference generated between the feed control axis and the rotation control axis by calculating the force exerted, and at least one of the feed control axis and the rotation control axis based on the interference estimated by the interference estimation unit Power to To provide a control apparatus characterized by comprising a command correcting unit for correcting the command, the.

  According to a second aspect of the present invention, in the control device according to the first aspect, the interference estimation unit is preceded by one control cycle or more than the cycle of the operation control of at least one of the feed control shaft and the rotation control shaft according to the position command. Then, the interference is estimated, and the command correction unit provides a control device that corrects the current command in the operation control cycle.

A third aspect of the present invention is the control device according to the first or second aspect, wherein when the eccentric load is changed , one of the feed control shaft and the rotation control shaft is stopped and the other is rotated at a constant speed. Interference estimation is performed by obtaining the position and mass of the changed eccentric load based on the current command equivalent to the interference commanded to one of the feed control shaft and the rotation control shaft in a state where the interference estimation unit does not estimate the interference during operation. There is provided a control device, further comprising a constant changing unit that changes the position and mass value of the eccentric load in an arithmetic expression used by the unit to estimate interference.

According to a fourth aspect of the present invention, in the control device according to the first or second aspect , the interference estimation unit estimates interference in a test operation in which one of the feed control shaft and the rotation control shaft is stopped and the other is rotated at a constant speed. An eccentricity information estimation unit for estimating the position and mass information of the eccentric load based on a current command corresponding to interference commanded to one of the feed control axis and the rotation control axis in a state where the , and have based the position command, to the position and mass information eccentric information estimating unit has estimated, estimates the interference, to provide a control device.

According to a fifth aspect of the present invention, there is provided a control method for controlling a feed operation of a feed control axis and a rotation operation of the rotation control axis of a machine tool including a feed control axis and a rotation control axis fed along the feed control axis. , While the feed control shaft is performing a feed operation based on the position command commanded to at least one of the feed control shaft and the rotation control shaft and the position and mass information of the eccentric load carried by the rotation control shaft. By calculating the force exerted on the rotation control shaft by the thrust applied to the load, or calculating the force exerted on the feed control shaft by the centripetal force and tangential force applied to the eccentric load while the rotation control shaft is rotating, A control method characterized by estimating interference generated between a feed control axis and a rotation control axis, and correcting a current command given to at least one of the feed control axis and the rotation control axis based on the estimated interference. provide

  According to a sixth aspect of the present invention, in the control method according to the fifth aspect, the interference is estimated at least one control cycle before the operation control cycle of at least one of the feed control shaft and the rotation control shaft according to the position command. And the control method which correct | amends the electric current command in the period of operation control based on this interference is provided.

The invention according to claim 7, in the control method according to claim 5 or 6, when the eccentric load is changed, to rotate the other when stopping one of the feed control axis and the rotary control axis at a constant speed Based on the current command equivalent to the interference commanded to one of the feed control shaft and the rotation control shaft in a state where the interference is not estimated in the test operation, find the position and mass of the changed eccentric load , Provided is a control method for changing the position and mass value of an eccentric load in an arithmetic expression used for estimating interference.

The invention according to claim 8 is the control method according to claim 5 or 6, wherein a test operation is performed in which one of the feed control shaft and the rotation control shaft is stopped and the other is rotated at a constant speed, and interference is caused in the test operation. based on the current command of the interference corresponding to the command to either the control shaft and the rotary control axis feed without this estimation, estimates the position and mass information of the eccentric load position and mass and position command and estimated and based on the information, estimate interference, to provide a control method.

  According to the first aspect of the present invention, since a position detector for detecting the actual state of interference is not required, an increase in the equipment cost of the machine tool can be suppressed, and the installation location and reliability of the position detector can be reduced. No need to consider. In addition, the interference estimation unit is known that can be acquired before the start of operation control, such as the position command commanded to at least one of the feed control axis and the rotation control axis, and the position and mass information of the eccentric load carried by the rotation control axis. Based on the data, the interference is estimated, and the command correction unit is configured to correct the current command directly given to each control axis based on the interference. Therefore, for the high-speed and high-precision positioning control in the machine tool, Adaptable without problems. Thus, according to the control device, the interference between the feed control axis and the rotation control axis in the machine tool can be accurately eliminated without delay, and stable and highly accurate operation control of each control axis can be realized. Thus, the machining accuracy of the workpiece can be improved.

  According to the second aspect of the invention, the adaptation to the high-speed and high-accuracy positioning control is further ensured.

  According to the third aspect of the present invention, it is possible to accurately deal with such a change in load with respect to a machine tool having a rotation control shaft that carries an object such as a work or a tool whose magnitude or arrangement of the load changes variously. Correspondingly, interference between the rotation control axis and the feed control axis can be accurately eliminated.

  According to the fourth aspect of the invention, since the work of measuring the position of the eccentric load and the mass information can be omitted, there is an advantage that the preparation work of the operation control is simplified.

  According to the invention described in claims 5 to 8, the same effects as those of the invention described in claims 1 to 4 are obtained.

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. Corresponding components are denoted by common reference symbols throughout the drawings.
Referring to the drawings, FIG. 1 is a functional block diagram showing the basic configuration of a motor control device 10 according to the present invention. 2 and 3 respectively illustrate main parts of machine tools 12 and 14 according to two representative examples to which the control device 10 can be applied. The control device 10 is installed on the feed control shafts 16L and 16R for executing the linear feed operation or the rotary feed operation, and the feed control shafts 16L and 16R, and is fed along the feed control shafts 16L and 16R, and the rotation indexing operation. Are controlled by the machine tools 12 and 14 having the rotation control shaft 18 for executing the operations of the feed control shafts 16L and 16R and the rotation control shaft 18. Note that the control device 10 can be functionally incorporated in an existing control device of a machine tool that uses an electric motor as a movable part drive source, such as a numerical control (NC) device.

  As shown in FIG. 1, the control device 10 includes a position command C1 that is commanded to at least one of the feed control shafts 16L and 16R and the rotation control shaft 18 (FIGS. 2 and 3), and an eccentricity that the rotation control shaft 18 carries. An interference estimator 22 for estimating the interference P generated between the feed control shafts 16L, 16R and the rotation control shaft 18 based on the position of the load 20 (FIGS. 2 and 3) and the mass information D; And a command correction unit 24 that corrects a current command C2 applied to at least one of the feed control shafts 16L and 16R and the rotation control shaft 18 based on the interference P estimated by the motor 22. In the present application, the term “interference” means a mechanical influence caused by each operation exerted between the feed control shafts 16L and 16R and the rotation control shaft 18, and acts in a linear direction as will be described later. It includes both interference thrust F and interference torque T acting in the rotational direction.

The machine tool 12 illustrated in FIG. 2 includes, as a table mechanism for placing a workpiece (not shown), a stationary base 26, a linear feed base 28 installed on the stationary base 26 so as to be linearly movable, and a straight line. And a rotary indexing table 30 that is rotatably installed on the feed base 28. The linear feed table 28 reciprocates on the stationary base 26 in the direction of the arrow A1 in accordance with the linear feed operation of the linear feed control shaft 16L using a linear motor (electric motor) (not shown) as a drive source. Further, the rotation index table 30 reciprocates in the direction indicated by the arrow B1 on the linear feed base 28 in accordance with the rotation index operation of the rotation control shaft 18 using a rotation motor (electric motor) (not shown) as a drive source.

On the other hand, the machine tool 14 illustrated in FIG. 3 includes, as a table mechanism for placing a workpiece (not shown), a stationary base (not shown), and a rotary feed base 32 that is rotatably installed on the stationary base. And a rotary indexing table 34 rotatably installed on the rotary feed base 32. The rotary feed base 32 reciprocates on the stationary base in the direction indicated by the arrow A2 in accordance with the rotary feed operation of the rotary feed control shaft 16R using a rotary motor (electric motor) (not shown) as a drive source. The rotation index table 34 reciprocally rotates in the direction of the arrow B2 on the rotation feed base 32 according to the rotation indexing operation of the rotation control shaft 18 using a rotation motor (electric motor) (not shown) as a drive source.

  In the machine tools 12 and 14 having the above-described configuration, the rotation index tables 30 and 34 have a center of gravity (that is, an eccentric load 20) at a position deviating from the rotation center due to the influence of the workpiece and workpiece holder placed thereon. May be formed. When the rotation control shaft 18 carries such an eccentric load 20, interference may occur between the linear or rotary feed bases 28 and 32 and the rotation index tables 30 and 34. That is, when the linear or rotary feed bases 28 and 32 are accelerated, the reaction of thrust or torque is exerted on the rotary index tables 30 and 34 having the eccentric load 20, and the positions of the rotary index tables 30 and 34 are changed. There is a risk of deviation from the command position. Similarly, when the rotary indexing tables 30 and 34 having the eccentric load 20 are accelerated, the reaction of the torque is exerted on the straight or rotary feed bases 28 and 32, and the positions of the straight or rotary feed stands 28 and 32 are changed. There is a risk of deviation from the command position. In either case, it may be a factor that reduces the machining accuracy of the workpiece.

  In order to cope with such a problem, the control device 10 according to the present invention includes a position command C1 in which the interference estimation unit 22 is commanded to at least one of the feed control shafts 16L and 16R and the rotation control shaft 18, and a rotation control shaft. Based on the position of the eccentric load 20 carried by 18 and the mass information D, the interference P is estimated. Based on the estimated interference P, the command correction unit 24 feeds the feed control shafts 16L and 16R and the rotation control shaft 18. By correcting the current command C2 applied to at least one of the above, it is possible to perform highly accurate operation control of each of the axes 16L, 16R, and 18 excluding the influence of the interference P. Therefore, since a position detector for detecting the actual state of interference is not required, an increase in the equipment cost of the machine tools 12 and 14 can be suppressed, and there is no need to consider the installation location and reliability of the position detector. Moreover, the interference estimation unit 22 estimates the interference P based on known data that can be acquired before the start of the operation control, such as the position command C1 and the position and mass information D of the eccentric load 20, and the command correction unit 24 Since the current command C2 directly applied to the control shafts 16L, 16R, 18 is corrected based on the interference P, the linear or rotary feed bases 28, 32 and the rotary index table in the machine tools 12, 14 are used. It can be applied to 30 and 34 high-speed and high-accuracy positioning control without problems. Thus, according to the control device 10, the interference P between the feed control shafts 16L and 16R and the rotation control shaft 18 in the machine tools 12 and 14 is accurately eliminated without delay, and the control shafts 16L, 16R, 18 stable high-precision motion control can be realized, so that the machining accuracy of the workpiece can be improved.

  In the above configuration, the position command C1 and the position and mass information D of the eccentric load 20 are manually input to the control device 10 by an operator or read into the control device 10 while being stored in a storage medium, for example. be able to. And the control apparatus 10 can have the input part and memory | storage part of these position command C1 and eccentric load information D (not shown).

  Next, an embodiment of each axis control method of the machine tool by the control device 10 will be described with reference to FIGS. In the following description, components corresponding to those shown in FIGS. 1 to 3 are denoted by common reference numerals, and the description thereof is omitted.

  First, an operation control method for the feed control shaft 16L and the rotation control shaft 18 in the machine tool 12 illustrated in FIG. 2 will be described. As shown in FIG. 4, in the control device 10, as a normal control loop 36 for the feed control shaft 16 </ b> L, the position control unit 38 calculates a position command C <b> 1 input to the feed control shaft 16 </ b> L (linear motor). Speed command C3, speed control unit 40 computes speed command C3 to obtain current command (or thrust command) C2, and current control unit 42 commands feed control shaft 16L with a current value according to current command C2, A position detector 44 such as an encoder provided along with the feed control shaft 16L detects the actual operating position of the feed control shaft 16L and feeds back to the position control unit 38. Similarly, in the control device 10, as a normal control loop 46 for the rotation control shaft 18, the position control unit 48 calculates the position command C <b> 1 input to the rotation control shaft 18 (rotation motor) and performs a speed command C <b> 3. Then, the speed control unit 50 computes the speed command C3 to obtain a current command (or torque command) C2, and the current control unit 52 commands the current value according to the current command C2 to the rotation control shaft 18, and the rotation control shaft 18 A position detector 54 such as an encoder provided in the vicinity has a configuration that detects the actual operation position of the rotation control shaft 18 and feeds back to the position control unit 48.

  In the control configuration described above, when the rotation control shaft 18 performs a rotation indexing operation on the feed control shaft 16L that is stationary or operating, the interference estimation unit 22 receives the position command C1 that is commanded to the rotation control shaft 18 and the rotation control. Based on the position of the eccentric load 20 carried by the shaft 18 and the mass information D, the interference P (that is, the interference thrust F) exerted on the feed control shaft 16L by the rotation control shaft 18 is estimated. Then, the command correction unit 24 adds the interference P (interference thrust F) estimated by the interference estimation unit 22 to the current command C2 output from the speed control unit 40 in the control loop 36 of the feed control shaft 16L to obtain a current. The command C2 is corrected. As a result, the current control unit 42 accurately commands the current value according to the current command C2 corrected by the command correction unit 24 to the feed control shaft 16L.

  In the control configuration described above, when the feed control shaft 16L performs a linear feed operation with respect to the stationary or operating rotation control shaft 18, the interference estimation unit 22 instructs both the feed control shaft 16L and the rotation control shaft 18. Based on each position command C1 and the position and mass information D of the eccentric load 20 carried by the rotation control shaft 18, the interference P (that is, interference torque T) exerted on the rotation control shaft 18 by the feed control shaft 16L is determined. presume. Then, the command correction unit 24 adds the interference P (interference torque T) estimated by the interference estimation unit 22 to the current command C2 output from the speed control unit 50 in the control loop 46 of the rotation control shaft 18 to obtain a current. The command C2 is corrected. As a result, the current control unit 52 accurately commands the rotation control shaft 18 with a current value according to the current command C2 corrected by the command correction unit 24.

  A method for estimating the interference P by the interference estimation unit 22 in the control flow will be described with reference to FIGS. 5 and 6 schematically show the mechanical relationship between the feed control shaft 16L and the rotation control shaft 18 with the eccentric load 20 as a mass point.

FIG. 5 shows a state in which the rotation control shaft 18 performs a rotation indexing operation on the feed control shaft 16L that is stationary or in operation (accelerating at an angular acceleration α). During this rotational indexing operation, the eccentric load 20 is applied with an centripetal force f corresponding to the angular velocity ω and a torque t (more precisely, tangential force t / r) corresponding to the angular acceleration α (FIG. 5 (a )). Here, when the distance from the rotation center O of the rotation control shaft 18 to the eccentric load 20 is r, and the mass of the eccentric load 20 is m,
f = m · r · ω ²
t / r = m · r · α = m · r · dω / dt
It is.

Hereinafter, the force (that is, the interference thrust F) exerted on the feed control shaft 16L by the centripetal force f and the tangential force t / r will be considered. Here, the rotation angle of the eccentric load 20 from the machine coordinate origin G of the rotation control shaft 18 is θ, and the angle (position) of the feed control shaft 16L (that is, the linear feed direction) from the machine coordinate origin G is θ ₀ . Then, the resultant force F ′ (FIG. 5B) in the direction parallel to the feed control shaft 16L of the centripetal force f applied to the eccentric load 20 and the tangential force t / r during the rotation indexing operation is
F ′ = m · r · ω ² · cos (θ−θ ₀ ) + m · r · dω / dt · sin (θ−θ ₀ )
It becomes. Therefore, the interference thrust F (interference P) exerted by the rotation control shaft 18 on the feed control shaft 16L is estimated as F = −F ′. In the above description, r and m are acquired as the position and mass information D of the eccentric load 20, and θ is acquired as the position command C <b> 1 commanded to the rotation control shaft 18. Θ ₀ is a unique value of the machine tool 12 that represents the relative positional relationship between the feed control shaft 16L and the rotation control shaft 18.

On the other hand, FIG. 6 shows a state where the feed control shaft 16L is performing a linear feed operation with respect to the stationary or operating rotation control shaft 18 (accelerating at an acceleration a). During this linear feed operation, the following thrust u corresponding to the acceleration a is applied to the eccentric load 20 (FIG. 6A).
u = m · a = m · dv / dt
The force that the thrust u exerts on the rotation control shaft 18 (that is, the interference torque T) is
T = −u · r · sin (θ−θ ₀ ) = − m · r · dv / dt · sin (θ−θ ₀ )
It becomes. In this way, the interference torque T (interference P) exerted on the rotation control shaft 18 by the feed control shaft 16L is estimated. In the above description, r and m are acquired as the position and mass information D of the eccentric load 20, θ is acquired as the position command C1 commanded to the rotation control shaft 18, and a (or v) is the feed control shaft 16L. It is acquired from the position command C1 commanded to. Θ ₀ is a unique value of the machine tool 12 that represents the relative positional relationship between the feed control shaft 16L and the rotation control shaft 18.

  Next, an operation control method for the feed control shaft 16R and the rotation control shaft 18 in the machine tool 14 illustrated in FIG. 3 will be described. Since this operation control method is the same as the operation control method of the feed control shaft 16L and the rotation control shaft 18 in the machine tool 12 described above, the description of the control flow is omitted, and the interference is described with reference to FIGS. A method for estimating the interference P by the estimation unit 22 will be described. 7 and 8 schematically show the mechanical relationship between the feed control shaft 16R and the rotation control shaft 18 with the eccentric load 20 as a mass point.

FIG. 7 shows a state in which the rotation control shaft 18 performs a rotation indexing operation on the feed control shaft 16R that is stationary or in operation (accelerating at an angular acceleration α). The actual feed control shaft 16R has a rotation center axis at a position separated from the illustrated reference axis Z by a distance s (FIG. 3) in the direction orthogonal to the paper surface. During the rotation indexing operation of the rotation control shaft 18, the eccentric load 20 is applied with a centripetal force f corresponding to the angular velocity ω and a torque t (more precisely, tangential force t / r) corresponding to the angular acceleration α. Here, when the distance from the rotation center O of the rotation control shaft 18 to the eccentric load 20 is r, and the mass of the eccentric load 20 is m,
f = m · r · ω ²
t / r = m · r · α = m · r · dω / dt
It is.

Next, the force (namely, interference torque T) exerted on the feed control shaft 16R by the centripetal force f and the tangential force t / r will be considered. Here, the rotation angle of the eccentric load 20 from the machine coordinate origin G of the rotation control axis 18 is θ, and the angle (position) of the reference axis Z (axis parallel to the feed control axis 16R) from the machine coordinate origin G is the angle (position). Assuming θ ₀ , the resultant force F in the direction orthogonal to the reference axis Z of the centripetal force f and the tangential force t / r applied to the eccentric load 20 during the rotation indexing operation is
F = m · r · ω ² · sin (θ−θ ₀ ) −m · r · dω / dt · cos (θ−θ ₀ )
It becomes. Therefore, the interference torque T (interference P) exerted by the rotation control shaft 18 on the feed control shaft 16R is estimated as T = −F · s. In the above description, r, m, and s are acquired as the position and mass information D of the eccentric load 20, and θ is acquired as the position command C1 that is commanded to the rotation control shaft 18. Θ ₀ is a unique value of the machine tool 14 representing the relative positional relationship between the feed control shaft 16R and the rotation control shaft 18.

On the other hand, FIG. 8 shows a state in which the feed control shaft 16R is rotating and feeding with respect to the stationary or operating rotation control shaft 18 (accelerating at the tangential acceleration a). During this rotational feed operation, the following thrust u corresponding to the tangential acceleration a is applied to the eccentric load 20.
u = m · a = m · dv / dt
The force that the thrust u exerts on the rotation control shaft 18 (that is, the interference torque T) is
T = −u · r · cos (θ−θ ₀ ) = − m · r · dv / dt · cos (θ−θ ₀ )
It becomes. Thus, the interference torque T (interference P) exerted on the rotation control shaft 18 by the feed control shaft 16R is estimated. In the above description, r and m (and distance s for converting angular displacement into linear displacement) are acquired as the position and mass information D of the eccentric load 20, and θ is a position command commanded to the rotation control shaft 18. Acquired as C1, and a (or v) is acquired from the position command C1 commanded to the feed control shaft 16R. Θ ₀ is a unique value of the machine tool 14 representing the relative positional relationship between the feed control shaft 16R and the rotation control shaft 18.

  As described above, the control device 10 estimates the interference P based on the known data that the interference estimation unit 22 can acquire before the start of the operation control, and the command correction unit 24 determines the current command C2 based on the interference P. By adopting the correction configuration, it can be applied to high-speed and high-accuracy positioning control in the machine tools 12 and 14. Accordingly, the interference estimation unit 22 estimates the interference P one or more control cycles before the operation control cycle of at least one of the feed control shafts 16L and 16R and the rotation control shaft 18 according to the position command C1, and the command correction unit 24 is configured to correct the current command C2 in the operation control cycle, the adaptation to high-speed and high-accuracy positioning control is further ensured.

  By the way, in general, the rotation control axis of a machine tool carries an object such as a workpiece or a tool whose load size or arrangement changes in various ways, so even if the interference between the control axes is obtained by calculation as in the present invention. If constant terms such as mass, position, and angle in the calculation formula remain fixed, it becomes difficult to perform high-accuracy correction corresponding to changes in load. Therefore, in the control device 10 having the above-described basic configuration, it is advantageous to add a function for changing the operation constant for the interference estimation unit 22 to estimate the interference P in response to the change of the eccentric load 20.

FIG. 9 is a functional block diagram showing the configuration of the control device 60 according to a preferred embodiment of the present invention having such additional functions. In addition to the basic configuration of the control device 10 of FIG. 1, the control device 60 corresponds to a change in the eccentric load 20 and the operation constants (m, r, θ _0, etc.) for the interference estimation unit 22 to estimate the interference P ) Is further provided. Therefore, common reference numerals are assigned to components corresponding to the components of the control device 10, and detailed description thereof is omitted.

For example, in the embodiment shown in FIG. 5, when the rotation control shaft 18 rotates at a constant speed, the interference thrust F exerted on the feed control shaft 16L is F = −m · r · ω ² · cos (θ −θ ₀ ), and a sinusoidal curve is drawn. Therefore, when the eccentric load 20 is changed, a test is performed in which the rotation control shaft 18 is rotated at a constant speed (a low speed that does not cause the positional deviation of the feed control axis 16L to be excessive) while the feed control axis 16L is stopped. When the operation is performed, the control device 60 cancels the interference thrust F from the speed control unit 40 in a state where the interference estimation unit 22 does not estimate interference in a normal feedback loop (see FIG. 4) for the feed control shaft 16L. Similarly, a sinusoidal (that is, interference equivalent) current command C2 is output.

Here, the constant changing unit 62 observes the current command C2 corresponding to the interference output from the speed control unit 40 (that is, the current command C2 before being corrected by the command correcting unit 24), so that the calculation constant (m , R, θ _0, etc.) can be obtained. That is, since cos (θ−θ ₀ ) = 1 when the current command C2 indicates the maximum value C2max, m · r = K · C2max / ω ² (K is a torque constant specific to the motor). Therefore, the constant changing unit 62 can obtain the changed mass m and position r of the eccentric load 20 based on the maximum value C2max of the current command C2 and the angular velocity ω of the rotation control shaft 18 by the test operation. Further, based on the rotation angle θ of the rotation control shaft 18 when the current command C2 indicates the maximum value C2max or the minimum value 0, the angle of the feed control shaft 16L from the machine coordinate origin G (FIG. 5) (that is, the rotation control shaft). (Relative positional relationship between 18 and the feed control shaft 16L) θ ₀ can also be obtained.

In the above test operation, when it is difficult to operate the rotation control shaft 18 for one or more revolutions, the maximum value C2max of the current command C2 cannot be specified. Only the angle θ ₀ of the control shaft 16L needs to be measured. If both the current command C2 and the angle (θ−θ ₀ ) are observed in the test operation, the mass m and the position r of the eccentric load 20 can be obtained.

Similarly, in the embodiment shown in FIG. 7, when the rotation control shaft 18 rotates at a constant speed, the interference torque T exerted on the feed control shaft 16R is T = −s · m · r · ω ^2. Sin (θ−θ ₀ ) Therefore, similarly to the above method, the constant changing unit 62 performs a current command by a test operation that rotates the rotation control shaft 18 at a constant speed while the feed control shaft 16R is stopped when the eccentric load 20 is changed. Based on the maximum value C2max of C2, the angular velocity ω and the rotation angle θ of the rotation control shaft 18, the changed mass m and position r of the eccentric load 20, and the relative positional relationship between the rotation control shaft 18 and the feed control shaft 16R. s and θ ₀ can be determined.

  According to the control device 60 having the above-described configuration, the rotation control shaft 18 that carries an object such as a workpiece or a tool whose load size or arrangement varies in addition to the special effects obtained by the control device 10 described above. For the machine tools 12 and 14 having the above, there can be obtained an advantage that the interference between the rotation control shaft and the feed control shaft can be accurately eliminated by accurately responding to such a change in load.

  In the control devices 10 and 60 described above, the position of the eccentric load 20 and the mass information D that are first given to the interference estimation unit 22 are described as known data that can be acquired before the start of the motion control. In this case, as the position r and the mass m of the eccentric load 20 are usually measured values, the preparation work for the operation control tends to be complicated. On the other hand, by using the function of the constant changing unit 62 of the control device 60 described above, the position and mass information D of the eccentric load 20 initially given to the interference estimating unit 22 are estimated appropriately without being actually measured. be able to.

  FIG. 10 is a functional block diagram showing the configuration of the control device 70 according to another preferred embodiment of the present invention having such additional functions. The control device 70 further includes an eccentricity information estimation unit 72 that estimates the position and mass information D of the eccentric load 20 in addition to the basic configuration of the control device 10 of FIG. Therefore, common reference numerals are assigned to components corresponding to the components of the control device 10, and detailed description thereof is omitted.

  The eccentric information estimation method by the eccentric information estimation unit 72 is substantially the same as the constant changing method by the constant changing unit 62 of the control device 60 described above. That is, for example, in the embodiment shown in FIG. 5, when the position of the eccentric load 20 and the mass information D are unknown, the test operation described above that rotates the rotation control shaft 18 at a constant speed while the feed control shaft 16L is stopped. In the normal feedback loop (see FIG. 4) of the control device 70 for the feed control shaft 16L, the current command C2 equivalent to interference is output from the speed control unit 40 in a state where the interference estimation unit 22 does not estimate interference. Let

Here, the eccentricity information estimation unit 72 is based on the current command C2 corresponding to the interference commanded to the feed control shaft 16L (that is, the current command C2 before correction by the command correction unit 24), and the position and mass information of the eccentric load 20. D (ie position r and mass m) is estimated. That is, in the equation of interference thrust F exerted on the feed control shaft 16L while the rotation control shaft 18 rotates at a constant speed ω, F = −m · r · ω ² · cos (θ−θ ₀ ), the current command C2 Since cos (θ−θ ₀ ) = 1 when m indicates the maximum value C2max, m · r = K · C2max / ω ² (K is a torque constant specific to the motor). Therefore, the eccentricity information estimation unit 72 can obtain the mass m and the position r of the eccentric load 20 based on the maximum value C2max of the current command C2 and the angular velocity ω of the rotation control shaft 18. Further, based on the rotation angle θ of the rotation control shaft 18 when the current command C2 indicates the maximum value C2max or the minimum value 0, the angle of the feed control shaft 16L from the machine coordinate origin G (FIG. 5) (that is, the rotation control shaft). (Relative positional relationship between 18 and the feed control shaft 16L) θ ₀ can also be obtained. The position and mass information D (position r and mass m) and the angle θ ₀ of the eccentric load 20 estimated in this way are stored in, for example, a storage unit (not shown) of the control device 70, and interfere in actual operation control. It is used when the estimation unit 22 estimates the interference thrust F.

The eccentric information estimation unit 72 can also estimate the position and mass information D of the eccentric load 20 by performing a test operation in which the feed control shaft 16L is fed at a constant acceleration while the rotation control shaft 18 is stopped. . With this test operation, the control device 70 causes the speed control unit 50 to output a current command C2 equivalent to interference in a state where the interference estimation unit 22 does not estimate interference in a normal feedback loop (see FIG. 4) with respect to the rotation control shaft 18. Output. Here, as described with reference to FIG. 6, the interference torque T exerted on the rotation control shaft 18 by the thrust u is T = −m · r · dv / dt · sin (θ−θ ₀ ). The rotation angle θ of the rotation control shaft 18 when the current command C2 indicates the minimum value 0 becomes the angle θ ₀ of the feed control shaft 16L from the machine coordinate origin G (FIG. 6). Then, the eccentricity information estimation unit 72 performs interference based on the current command C2 observed when the feed control shaft 16L is fed at a constant acceleration dv / dt while the rotation control shaft 18 is stopped at an arbitrary angle θ. From the equation of torque T, the mass m and position r of the eccentric load 20 can be obtained.

  According to the control device 70 having the above-described configuration, the measurement work of the position of the eccentric load 20 and the mass information D can be omitted in addition to the special effects of the control device 10 described above. The benefits are obtained.

It is a functional block diagram which shows the basic composition of the control apparatus which concerns on this invention. It is a perspective view which shows roughly an example of the principal part of the machine tool which can apply the control apparatus of FIG. It is a perspective view which shows roughly the other example of the principal part of the machine tool which can apply the control apparatus of FIG. It is a block diagram which shows the control flow in the control apparatus of FIG. FIG. 3 is a diagram for explaining an interference estimation method for the machine tool in FIG. 2, (a) a diagram schematically showing a mechanical relationship between a feed control axis and a rotation control axis, and (b) a mechanical relationship between both axes. It is a figure which shows geometrically using an eccentric load as a mass point. FIG. 3 is a diagram for explaining another interference estimation method related to the machine tool of FIG. 2, (a) a diagram schematically showing a mechanical relationship between a feed control axis and a rotation control axis, and (b) a dynamics of both axes. It is a figure which shows a relationship geometrically by making an eccentric load into a mass point. It is a figure explaining the estimation method of the interference regarding the machine tool of FIG. It is a figure explaining the estimation method of the other interference regarding the machine tool of FIG. It is a functional block diagram which shows the structure of the control apparatus by one Embodiment of this invention. It is a functional block diagram which shows the structure of the control apparatus by other embodiment of this invention.

Explanation of symbols

10, 60, 70 Control device 12, 14 Machine tool 16L, 16R Feed control shaft 18 Rotation control shaft 20 Eccentric load 22 Interference estimation unit 24 Command correction unit 62 Constant change unit 72 Eccentric information estimation unit

Claims (8)

In a control device for controlling a feed operation of the feed control axis and a rotation operation of the rotation control axis of a machine tool including a feed control axis and a rotation control axis fed along the feed control axis.
While the feed control shaft performs a feed operation based on the position command commanded to at least one of the feed control shaft and the rotation control shaft and the position and mass information of the eccentric load carried by the rotation control shaft . The force exerted on the rotation control shaft by the thrust applied to the eccentric load is calculated, or the centripetal force and tangential force applied to the eccentric load while the rotation control shaft is rotating are exerted on the feed control shaft. An interference estimator for estimating interference generated between the feed control axis and the rotation control axis by calculating a force ;
A command correction unit that corrects a current command to be applied to at least one of the feed control axis and the rotation control axis based on the interference estimated by the interference estimation unit;
A control device comprising:   The interference estimation unit estimates the interference at least one control cycle before the operation control cycle of at least one of the feed control axis and the rotation control axis according to the position command, and the command correction unit The control device according to claim 1, wherein the current command in the cycle of the operation control is corrected.   When the eccentric load is changed, in the test operation in which one of the feed control shaft and the rotation control shaft is stopped and the other is rotated at a constant speed, the feed control shaft is not estimated by the interference estimation unit. And an arithmetic expression used by the interference estimation unit to estimate the interference by obtaining the position and mass of the changed eccentric load based on a current command corresponding to the interference commanded to one of the rotation control shafts. The control device according to claim 1, further comprising a constant changing unit that changes a position and a mass value of the eccentric load in.   In a test operation in which one of the feed control shaft and the rotation control shaft is stopped and the other is rotated at a constant speed, the interference estimation unit does not estimate the interference to either the feed control shaft or the rotation control shaft. An eccentricity information estimation unit that estimates the position and mass information of the eccentric load based on a current command corresponding to the commanded interference is further provided, and the interference estimation unit includes the position command and the eccentricity information estimation unit. The control device according to claim 1, wherein the interference is estimated based on the estimated position and mass information. In a control method for controlling a feed operation of the feed control axis and a rotation operation of the rotation control axis of a machine tool including a feed control axis and a rotation control axis fed along the feed control axis.
While the feed control shaft performs a feed operation based on the position command commanded to at least one of the feed control shaft and the rotation control shaft and the position and mass information of the eccentric load carried by the rotation control shaft . The force exerted on the rotation control shaft by the thrust applied to the eccentric load is calculated, or the centripetal force and tangential force applied to the eccentric load while the rotation control shaft is rotating are exerted on the feed control shaft. By calculating the force, the interference generated between the feed control axis and the rotation control axis is estimated,
Correcting a current command applied to at least one of the feed control axis and the rotation control axis based on the estimated interference;
A control method characterized by the above.   The interference is estimated at least one control period before the operation control period of at least one of the feed control axis and the rotation control axis according to the position command, and based on the interference, in the period of the operation control The control method according to claim 5, wherein the current command is corrected.   When the eccentric load is changed, a test operation is performed in which one of the feed control shaft and the rotation control shaft is stopped and the other is rotated at a constant speed, and the feed control is performed without estimating the interference in the test operation. The eccentricity in the arithmetic expression used for estimating the interference by obtaining the position and mass of the changed eccentric load based on a current command equivalent to the interference commanded to one of the shaft and the rotation control shaft The control method according to claim 5 or 6, wherein the load position and the mass value are changed.   A test operation is performed in which one of the feed control axis and the rotation control axis is stopped and the other is rotated at a constant speed, and either the feed control axis or the rotation control axis is not estimated in the test operation. The position and mass information of the eccentric load is estimated based on a current command equivalent to the interference commanded to, and the interference is estimated based on the position command and the estimated position and mass information. Item 7. The control method according to Item 5 or 6.

Images