JP2012176456A - Vibration suppressing apparatus for structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively suppress the vibration of a structure in such a compact configuration as to prevent upsizing or increase of costs.SOLUTION: A vibration suppressing apparatus for a column 3 of a double housing machining center includes: a damping servomotor 8 which is provided in the column 3 and is capable of generating a rotational torque through rotational drive; and a damping device 30 which outputs a rotation speed command to the damping servomotor 8 synchronously with a speed command relating to linear movement control of a saddle 5 and generates a rotational torque canceling a force applied to the column 3.

Description

  The present invention relates to a device that suppresses vibrations generated in structures of various machines such as machine tools.

  In various machines such as machine tools, when a moving body that moves along a structure is provided, vibration may occur in the structure due to a reaction force or the like when the moving body accelerates or decelerates. For example, in a portal machining center that is an example of a machine tool, a horizontal cross rail is provided on the front surface of a column as a structure standing on a bed so as to be movable up and down, and a spindle head is provided on the front surface of the cross rail. The saddle is provided as a moving body so that it can move horizontally. The reaction force when the saddle moves horizontally causes deflection and vibration in the column, which impairs the accuracy of the machine. In addition, such vibration is not limited to the reaction force accompanying the movement of the moving body, and may be generated by an external force.

  In order to suppress the vibration of the structure, it can be solved by increasing the secondary moment of the section of the structure itself, but this leads to an increase in the size and cost of the machine. Therefore, in Patent Document 1, in a case where a moving body is provided, a reaction canceling force vector (the product of the mass of the moving body and its linear acceleration is calculated along an axis parallel to the moving direction of the moving body and passing through the center of gravity of the moving body. An invention is described in which an actuator is installed that applies a vector having the same magnitude) to the structure.

Japanese Patent Laid-Open No. 11-329962

  However, in the invention of Patent Document 1, when a stage (moving body) moves horizontally on a base installed sideways, a reaction canceling force vector is applied from the side surface of the base by an actuator fixed outside the structure. It is like that. For this reason, when a heavy moving body moves horizontally such as a machine tool in which a saddle moves horizontally along a cross rail provided in a column, an absolute fixed object (for example, several hundred tons) It is difficult to realize this because it is necessary to install a lump of lump) next to it, and even if possible, it leads to an increase in the size and cost of the entire machine. Therefore, it is difficult to install the machine on a machine having a spatial restriction such as a machine tool.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a vibration suppressing device for a structure that can effectively suppress vibration with a compact configuration that does not increase in size and cost.

In order to achieve the above object, the invention according to claim 1 is provided in a structure including a moving body that is linearly controlled, and the force applied to the structure as the moving body moves linearly A device for suppressing vibration generated in a structure, the rotary actuator being provided in the structure and capable of generating rotational torque by rotational driving, and the speed command related to linear movement control of the mobile body And a damping means for generating a rotational torque that outputs a rotational speed command to the rotary actuator and cancels the force applied to the structure.
According to a second aspect of the present invention, in the configuration of the first aspect, the damping means includes a band-pass filter that extracts the speed command in a predetermined frequency band including a natural frequency of the structure, and the band The rotational speed command is output based on the speed command that has passed through a pass filter.
According to a third aspect of the present invention, in the configuration of the second aspect, an addition means for adding a predetermined rotation speed set in advance to the rotation speed command is provided.

According to the first aspect of the present invention, it is possible to effectively suppress the vibration of the structure with a compact configuration that does not cause an increase in size and cost.
According to the second aspect of the present invention, in addition to the effect of the first aspect, even if the size of the rotary actuator or the like is increased, excessive rotational torque is not generated, and the characteristics of the structure to be controlled Therefore, it is possible to suppress vibrations appropriately.
According to the third aspect of the present invention, in addition to the effect of the second aspect, it is possible to prevent the occurrence of fretting wear by avoiding the swinging motion at the same position, and the durability is not lowered.

It is explanatory drawing of a portal type machining center. FIG. 3 is a block diagram of a servo motor control device and a vibration suppression servo motor vibration control device.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows a portal machining center as an example of a machine tool on which the vibration suppressing device of the present invention is mounted. In the portal machining center 1, a cross rail 4 is provided on the front surface of a column 3 as a structure standing on a base 2, and a saddle 5 as a moving body is horizontally disposed on the front surface of the cross rail 4. It is provided so that it can move linearly. The saddle 5 is controlled to move by a ball screw 6 and a servo motor 7 provided on the cross rail 4.

  On the other hand, on the opposite side of the servo motor 7 in the upper part of the column 3, a damping servo motor 8 as a rotary actuator is incorporated. In the servo motor 8 for vibration suppression, a stator 9 is integrally connected to the column 3 in a posture with the rotor 10 facing forward, and a disc 11 having a mass is connected to the rotor 10 to provide load inertia. ing. Therefore, when the vibration-damping servomotor 8 is driven, a rotational torque is applied to the column 3 through the stator 9 in the direction opposite to the rotational direction of the rotor 10 and the disk 11.

FIG. 2 shows a block diagram of the control device 20 of the servo motor 7 and the vibration control device 30 as vibration control means for controlling the rotation of the vibration control servo motor 8.
First, the control device 20 of the servo motor 7 is based on the position control unit 21 that outputs a speed command value based on the position command value Xi generated based on the NC program, and the speed command value from the position control unit 21. A speed control unit 22 that outputs a torque command value and a current control unit 23 that drives and controls the servo motor 7 based on the torque command value are provided. Reference numerals 24 and 25 denote subtractors, in which a position loop is set such that the deviation between the position feedback signal obtained from the rotation detector 26 provided in the servomotor 7 and the position command value Xi is zero. Inside the loop is a speed loop in which the deviation between the speed feedback signal obtained by differentiating the output signal from the rotation detector 26 by the differentiator 27 and the speed command value is zero.

  Next, the vibration damping device 30 drives and controls the vibration-damping servomotor 8 in synchronization with the output of the position command value Xi to the servomotor 7. The position command value Xi to the servomotor 7 is differentiated by the differentiator 31. The bandpass filter 32 for extracting a speed command waveform in a predetermined frequency band including the natural frequency of the column 3 from the speed command value obtained by differentiating with the above, and the speed command waveform is multiplied by a preset coefficient. A vibration suppression gain unit 33 that outputs a diversion speed command value and a rotation speed offset unit 34 that adds a rotation speed preset to the speed command value in an adder 35 are provided. In consideration of the case where a signal delay occurs due to the use of the bandpass filter 32, the control device 20 of the servo motor 7 is provided with a delay unit 28 that delays the input of the position command value Xi to the position control unit 21. It has been.

The vibration control speed command value corrected by the rotational speed offset unit 34 is input to the speed control unit 36 provided in the vibration control device 30 and is then output from the current control unit 37 based on the torque command value output therefrom. Is configured to drive and control the vibration suppression servomotor 8. In this case as well, the vibration detection servomotor 8 is provided with the rotation detector 38, and the speed feedback signal obtained by differentiating the output signal from the rotation detector 38 by the differentiator 39 is subtracted by the subtractor 40. A speed loop is set up so that the deviation from the command value is zero.
The vibration suppression device 30 and the vibration suppression servomotor 8 constitute a vibration suppression device for the column 3.

  In the vibration suppression device configured as described above, when the position command value Xi to the saddle 5 is output, the speed obtained via the differentiator 31 and the bandpass filter 32 of the vibration damping device 30 in synchronization with this. The vibration suppression speed command value is calculated from the command value by the vibration suppression gain unit 33 and corrected by the rotation speed offset unit 34 and the adder 35. Since the vibration control servo motor 8 is driven and controlled based on the corrected vibration control speed command value, the vibration control servo motor 8 operates in accordance with the operation of the saddle 5, and the disk 11 is moved. Rotation torque is applied to the column 3 in the direction opposite to the rotation direction of the disk 11. Therefore, a rotational torque proportional to the acceleration / deceleration is generated in the column 3, and the deflection and vibration generated in the column 3 with the movement of the saddle 5 can be canceled.

  As described above, according to the vibration suppression device of the above aspect, the vibration suppression servomotor 8 provided in the column 3 and capable of generating rotational torque by rotational driving and the speed command related to the linear movement control of the saddle 5 are synchronized. And a vibration control device 30 that outputs a rotational speed command to the vibration suppression servomotor 8 and generates a rotational torque that cancels the force applied to the column 3. Thus, vibration of the column 3 can be effectively suppressed.

  In particular, here, the damping device 30 includes a bandpass filter 32 that extracts a speed command in a predetermined frequency band including the natural frequency of the column 3, and a rotational speed command based on the speed command that has passed through the bandpass filter 32. Therefore, an excessive rotational torque is not generated even when the size of the vibration suppression servomotor 8 or the disk 11 is increased, and an appropriate value corresponding to the characteristics of the column 3 to be controlled is obtained. Vibration suppression is possible.

However, when the band-pass filter 32 is used in this way, when the saddle 5 does not perform acceleration / deceleration operation, the vibration-damping servo motor 8 stops and swings according to the acceleration / deceleration operation. If the rocking motion is performed at the same position in this way, fretting wear occurs in the bearing, which may deteriorate durability.
However, in this case, the rotation speed command output through the bandpass filter 32 is provided with a rotation speed offset unit 34 and an adder 35 for adding a predetermined rotation speed to the rotation speed command. By avoiding dynamic motion, fretting wear can be prevented and durability is not lowered.

In the vibration damping device, the band-pass filter and the adding means can be omitted, and the configuration of the speed loop can be omitted by eliminating the rotation detector of the vibration damping servo motor.
The means for generating the load inertia in the vibration-damping servomotor is not limited to the disk connected to the rotor, and other means such as a weight connected to the rotor may be used.
Further, the rotary actuator is not limited to the servo motor, and for example, a pair of actuators such as a ball screw and a cylinder may be provided inside the structure, and the upper ends of the actuators may be connected to the structure. In this case, rotational torque can be applied by expanding and contracting both actuators in opposite directions.

  The form of the structure is not limited to a structure in which both ends are fixed like the column of the portal machining center of the above form, and may be a columnar structure in which the lower end is fixed. Therefore, the present invention is not limited to machine tools, and can be applied to various machines such as a measuring machine and a projection exposure apparatus mentioned in the prior art document.

  1 .... Portion type machining center, 2..Base, 3..Column, 4..Cross rail, 5..Saddle, 6..Ball screw, 7..Servo motor, 8..Servo motor for vibration suppression, 9 .. · Stator, 10 · · Rotor, 11 · · Disc, 20 · · Control device, 21 · · Position control unit, 22, 36 · · Speed control unit, 23, 37 · · Current control unit, 26, 38 · · Rotation Detector, 28 ... Delay unit, 30 ... Damping device, 32 ... Band pass filter, 33 ... Damping gain unit, 34 ... Rotational speed offset unit.

Claims (3)

A device that is provided in a structure including a moving body that is linearly controlled, and that suppresses vibration generated in the structure due to a force applied to the structure as the moving body moves linearly,
A rotary actuator provided in the structure and capable of generating rotational torque by rotational driving;
A vibration control means for outputting a rotational speed command to the rotary actuator in synchronization with a speed command related to linear movement control of the moving body, and generating a rotational torque that cancels a force applied to the structure. A vibration suppressing device for a structure having a feature.   The vibration damping means includes a bandpass filter that extracts the speed command in a predetermined frequency band including the natural frequency of the structure, and the rotational speed command is output based on the speed command that has passed through the bandpass filter. The structure vibration suppression device according to claim 1, wherein the vibration suppression device outputs the vibration.   The structure vibration suppressing device according to claim 2, further comprising addition means for adding a predetermined rotation speed set in advance to the rotation speed command.

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