JP4324376B2 - Active mass damper - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an active mass damper employed in a processing machine having a horizontal moving unit that is movable in the horizontal direction on a bed, and is capable of reducing floor vibration that occurs as the horizontal moving unit moves. Regarding mass dampers.
[0002]
[Prior art]
For example, a laser drilling machine that drills a printed circuit board using laser light is an X table that moves horizontally on a bed and an X table that is placed on the X table and is orthogonal to the movement direction of the X table. A Y table that moves in the horizontal direction, a fixed laser light source, and a reflection mirror that is rotatably supported and scans the laser light are provided.
[0003]
And when processing, the printed circuit board is divided into processing areas of a predetermined size, the center of the divided arbitrary processing area is positioned at the center of the laser beam, the laser beam is scanned to perform the processing, When the processing in the processing area is completed, the X table and the Y table are operated to move the printed board to the next processing area. Thereafter, the above operation is repeated until the processing is completed.
[0004]
Here, when the X table is moved, in the laser drilling machine, an exciting force having a magnitude obtained by multiplying the mass of the X table and the member placed on the X table by acceleration is generated in the horizontal direction. Since the point of action of this excitation force is higher than the floor, the laser drilling machine has the floor rigidity and laser drilling machine due to the moment force determined by the excitation force and the height of the action point. Rotational vibration (rocking vibration) having a natural frequency determined by the rotational inertia of is generated. The excitation force transmitted from one of the leveling bolts arranged on both sides of the laser drilling machine across the center of gravity of the laser drilling machine acts in the direction of pushing down the floor, and the excitation force transmitted from the other The force acts in the direction of lifting the floor. As a result, the floor generates vertical vibrations.
[0005]
In addition, when the Y table is moved, vertical vibrations are generated on the floor as in the case of moving the X table.
[0006]
Therefore, if the X table or the Y table (hereinafter collectively referred to as the X table) is moved at a high speed in order to improve the machining efficiency, the vibration of the floor increases.
[0007]
If the laser drilling machine is installed on the ground floor of a well-built building, the floor vibration will not be so great. However, when laser drilling machines are installed on floors above the second floor, these floors often do not have the rigidity and mass of the first floor, so when the laser drilling machine is operated, Large vibrations and associated noise may occur. Such vibration and noise not only cause discomfort for the operator, but also cause a reduction in machining accuracy and machining efficiency. Furthermore, the strength of the building may decrease due to repeated vibration.
[0008]
By the way, in order not to transmit the vibration of the equipment to the floor, a countermeasure against vibration is conventionally provided by providing a vibration isolating member made of an elastic body and a damper on the base of the equipment. However, if the laser drilling machine is flexibly supported by such a vibration isolating member, the rocking vibration will increase, so that the horizontal displacement of the X table is greatly increased compared to the case where it is not supported by the vibration isolating member, Positioning controllability is reduced. Also, when the laser drilling machine is softly supported, the support load of each vibration isolator changes as the X table moves, so the level of the laser drilling machine changes and high-precision machining is performed. It becomes difficult. Therefore, it is not appropriate to flexibly support the laser drilling machine with the vibration isolating member.
[0009]
Therefore, in Japanese Patent Laid-Open No. 6-336394, in order to reduce the vertical vibration transmitted to the movable carriage movable on the girder, the additional mass and the additional mass restrained by the linear motion restraining mechanism are added to the movable carriage. An active type dynamic vibration absorber (active mass damper) including a servo motor to be moved and an acceleration detector are provided. Then, the vertical vibration transmitted to the moving carriage is detected by the acceleration detector, and the active mass damper is controlled according to the detected value. Is attenuated. Therefore, by adopting such an active mass damper principle, the vertical excitation force based on the mass of the table or the like of the laser drilling machine can be attenuated.
[0010]
[Problems to be solved by the invention]
However, in the case of the above technique, it is not considered that the locking vibration is attenuated.
[0011]
Further, since the active mass damper is operated after the vibration is generated, a time delay occurs.
[0012]
By the way, in the case of a laser drilling machine, in order to improve work efficiency, the table is often moved at high speed, and the excitation force of the table is large.
[0013]
Here, when the mass of the weight of the active mass damper is large, it is relatively easy to suppress the excitation force of the table, but the entire laser processing machine becomes large.
[0014]
Therefore, if the mass of the weight is reduced for the purpose of reducing the size of the entire apparatus, it is necessary to relatively increase the acceleration of the weight. When holding the ball nut on the weight and driving the weight with the ball screw, if there is a gap between the ball nut and the ball screw, the two will collide when moving the weight or changing the moving direction suddenly. Higher order vibration components determined by the support rigidity of the weight and ball screw are excited. Therefore, when a gap is removed by applying a pressure between the ball screw and the ball nut, the weight does not return to the origin of movement due to the frictional force between them. Therefore, it is necessary to adjust the position of the weight by shortening the maintenance interval.
[0015]
An object of the present invention is to provide an active mass damper that can attenuate rocking vibration, is easy to maintain, and has a small size.
[0016]
[Means for Solving the Problems]
In order to achieve the above object, the first means of the present invention includes a supporting device that supports a weight so as to be movable in a horizontal direction, a weight driving device that drives the weight, and a controller that controls the weight driving device. In the active mass damper disposed in the processing machine, it is determined that the moving unit has entered a stopped state so that the moving direction of the weight is parallel to the moving direction of the moving unit of the processing machine. The controller drives the weight driving device by feedforward control based on a torque command value commanded to the driving unit of the moving unit and feedback control based on displacement of the weight, and the moving unit If but it is determined by said determining means that the stop state, the controller positions the weight based on the integrated value of the displacement of the weight in the center of the movement stroke And wherein the Rukoto.
[0017]
The second means of the present invention comprises a supporting device that supports a weight so as to be movable in a horizontal direction, a weight driving device that drives the weight, and a controller that controls the weight driving device. In the active mass damper disposed in the processing machine, a torque command value is commanded to the motor that drives the moving part of the processing machine so that the moving direction of the tool is parallel to the moving direction of the moving part of the processing machine. The weight driving device includes: a phase advance means for advancing a preset time phase from the time when the operation is performed; and a feedback control based on the specified torque value and the displacement of the weight, the phase output from the phase advance means being advanced. And a controller for driving.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
(First embodiment)
Hereinafter, the present invention will be described based on illustrated embodiments.
[0019]
FIG. 1 is a front view of a laser drilling machine according to a first embodiment of the present invention, FIG. 2 is a plan sectional view of an active mass damper, and FIG. 3 is a control block diagram of the active mass damper.
[0020]
The bed 6 of the laser drilling machine 2 is supported on the floor via a leveling bolt 5 and a block member 4. On the upper surface of the bed 6, a rail 9a of the linear guide 15a is fixed. The X table 7 is fixed to the slide unit 8a of the linear guide 15a and is movable in the horizontal direction (X direction) in the figure. A ball nut (not shown) held by the X table 7 is screwed into the ball screw 10a. The ball screw 10a is driven by a motor 11a.
[0021]
The motor 11 a is driven by a driver 43 based on a control signal output from the table driving controller 42.
[0022]
Note that a Y table (not shown) is supported on the X table 7 so as to be movable in the Y direction perpendicular to the paper surface, and a substrate is placed on the Y table. Then, the substrate on the Y table can be positioned at an arbitrary position in the horizontal direction by moving the X table 7 and the Y table, respectively.
[0023]
The portal frame 12 fixed to the upper surface of the bed 6 is provided with a laser source (not shown) and an optical system for guiding laser light output from the laser source to a processing position.
[0024]
As shown in FIG. 2, the motor stand 13, the bearing stands 19 a and 19 b and the rail 9 b of the linear guide 15 b which are components of the active mass damper 3 are fixed to the gantry 20. The weight 18 is supported by the slide unit 8b of the linear guide 15b and is movable in the X direction. The ball nut 16 fixed inside the weight 18 is screwed into the ball screw 10b. The ball screw 10b is rotatably supported by the bearing stand 19a, and one end thereof is connected to the output shaft of the motor 11b supported by the motor stand 13 through the coupling 14. The encoder 17 provided in the motor 11b is connected to the controller 40 via the driver 41 of the motor 11b. The controller 40 is connected to the signal output line 60 of the driver 43 of the motor 11a.
[0025]
As shown in FIG. 3, the inputs of the multiplier 44 and the determiner 50 of the controller 40 are connected to a signal output line 60. The determiner 50 is a torque command value signal (motor drive current value or motor drive voltage value) output from the driver 43 to the motor 11a every predetermined control period tc (for example, 1 ms). If the current torque command value and the torque command value in the previous control period tc are less than or equal to the preset value T0, the terminal c of the switch 53 is connected to the terminal b. In other cases, the terminal c is connected to the terminal a.
[0026]
The input side of the adder 52 is connected to the output side of the multiplier 44, the terminal a of the switch 53, the output side of the integrator 51 and the output side of the multiplier 49, and the output side is connected to the input side of the driver 41. Yes.
[0027]
The encoder 17 is connected to the input side of a multiplier 47 and a differentiator 48 via a pulse counter 45 and a converter 46. A terminal c of the switch 53 is connected to the output side of the multiplier 47, and a terminal b is connected to the input side of the integrator 51. The output side of the differentiator 48 is connected to the input side of the multiplier 49.
[0028]
Next, the operation of this embodiment will be described.
[0029]
FIG. 4 is a diagram illustrating an example of a time history of the torque command value output from the driver 43, where the vertical axis represents the torque command value and the horizontal axis represents time. As shown in the figure, the X table 7 repeatedly moves and stops in a rapid acceleration / deceleration pattern, and there is little if it moves at a constant speed. Then, while all the tables are stopped, laser light is irradiated to make holes in the substrate.
[0030]
Next, the operation of the active mass damper 3 will be described. The origin of movement of the weight 18 is the center of the movement stroke of the weight 18.
[0031]
(1) Since the torque command value is 0 from time t0 to time t1 and all signals input to the adder 52 are 0, the motor 11b is stopped. Further, the switch 53 is connected to the terminal c and the terminal b by the determination device 50.
[0032]
(2) It is the acceleration period of the X table 7 from time t1 to time t2, and the torque command value increases from 0 to Tm. The torque command value output from the driver 43 is multiplied by a coefficient by the multiplier 44, and the output of the integrator 51 and the output of the multiplier 49 are added and input to the driver 41. Here, the sign of the signal input to the driver 41 is determined by the sign of the current value output to the motor 11 a and is determined so that the acceleration direction of the weight 18 is opposite to the acceleration direction of the X table 7.
[0033]
As a result, the horizontal excitation force generated when the X table 7 starts to move is offset (or reduced) by the horizontal excitation force generated when the weight 18 is moved. Therefore, no rocking vibration is generated in the laser drilling machine 2 and no floor vibration is generated.
[0034]
Thus, in this embodiment, since the weight is feedforward controlled by the torque command value signal, generation of floor vibration can be prevented without time delay.
[0035]
Further, the pulse signal output from the encoder 17 is counted by the pulse counter 45 and converted into the displacement of the weight 18, and the obtained displacement is multiplied by the coefficient by the multiplier 47 and input to the adder 52 (that is, the weight 18). The displacement is fed back to the drive signal of the motor 11b, converted into a speed signal by the differentiator 48, further multiplied by a coefficient by the multiplier 49 and input to the adder 52 (that is, the speed of the weight 18 is driven to the drive signal of the motor 11b). Therefore, it is possible to prevent the weight 18 from being excessively displaced and colliding with the bearing stands 19a, 19b and the like.
[0036]
Here, if the feedback control is too strong, the acceleration of the weight 18 is reduced and the effect of reducing floor vibration is reduced. Therefore, the coefficient of the multiplier 47 is set to an appropriate value by experiments or the like.
[0037]
Further, when the control period tc elapses after the torque command value exceeds T0, the determination device 50 connects the contact c of the switch 53 to the contact a.
[0038]
(3) It is a deceleration period of the X table 7 from the time t2 to the time t3, and the torque command value is reversed from Tm to -Tm and then increased to 0. In this case, the decelerating direction of the weight 18 is opposite to the decelerating direction of the X table 7, and as in the case (2), the horizontal excitation force generated when the X table 7 stops moving is canceled out. (Or reduce). Therefore, no rocking vibration is generated in the laser drilling machine 2 and no floor vibration is generated.
[0039]
When a substantially control period tc elapses after the torque command value becomes equal to or less than T0, the determination device 50 connects the contact c of the switch 53 to the contact b.
[0040]
(4) From time t3 to time t4 (a) When the weight 18 has returned to the origin, the torque command value is 0, and the output of the pulse counter 45 is also 0. Therefore, the motor 11b stops.
[0041]
(B) When the weight 18 is displaced from the origin, the torque command value is 0, but the pulse counter 45 outputs a signal corresponding to the distance from the origin. Although this signal is small, it is integrated by the integrator 51 to drive the motor 11b and return the weight 18 to the origin.
[0042]
At this time, since the substrate is processed, the weight 18 is moved with a small acceleration so as not to affect the laser drilling machine 2.
[0043]
Furthermore, in the above embodiment, when the torque command value in the continuous control period tc is T0 or less, the small signal value output from the pulse counter 45 is integrated. However, the signal value may be directly used. .
[0044]
That is, as shown in FIG. 5, a multiplier 54 is arranged instead of the integrator 51 in FIG. 3, and a multiplier 47 in FIG. 3 is arranged between the terminal a of the switch 53 and the adder 52. Then, the coefficient value of the multiplier 54 is made sufficiently larger than the coefficient value of the multiplier 47.
[0045]
Alternatively, as shown in FIG. 6, the integrator 51 in FIG. 3 is replaced with a multiplier 54, and two series of switches 61 are arranged between the adder 52 and the driver 41. When the torque command value changes, the A side is enabled by the determiner 50 and the adder 52 is connected to the driver 41. When the torque command value in the continuous control period tc is T0 or less, the B side is By enabling the multiplier 54 and connecting it to the driver 41, the small signal value output from the pulse counter 45 is directly used.
[0046]
In either case, the operation is substantially the same as the above case. That is, even if the weight 18 is deviated from the origin when the X table 7 stops moving, the weight 18 can be returned to the origin by rotating the motor 11b. When correcting the displacement of the weight 18, the weight 18 is moved with a small acceleration so as not to affect the laser drilling machine 2, as in the above case.
[0047]
The determination method of the determination device 50 is not limited to this embodiment, and any determination method (for example, an acceleration sensor is provided in the X table 7 and the acceleration signal thereof can be used as long as it can be confirmed that the X table 7 is almost stopped. The motor 11b may be driven by the above, or a table movement start signal, a stop signal, or the like commanded from the table driving controller 42 may be used.
[0048]
By the way, the table driving controller 42 requires a slight processing time Δta when outputting a control signal corresponding to an arbitrary target position Q to the driver 43.
[0049]
Further, the driver 43 requires some processing time Δtb when outputting the torque command value corresponding to the input control signal to the multiplier 44.
[0050]
Further, the adder 52 outputs a signal obtained by adding (subtracting) the output of the integrator 51 and the output of the multiplier 49 to the output signal of the multiplier 44 (coefficient multiple of the torque command value). Some processing time Δtc is required.
[0051]
Furthermore, the driver 41 requires a slight processing time Δtd when outputting a drive signal corresponding to the output signal of the adder 52 to the motor 11b.
[0052]
Therefore, the drive signal is output to the motor 11b after the time ΔT (= Δta + Δtb + Δtc + Δtd. Hereinafter, the time ΔT is referred to as “control system delay time”) after the table drive controller 42 calculates the target position Q. Thereafter, that is, after the delay time ΔT of the control system from the acceleration / deceleration timing of the X table 7, the weight 18 is accelerated / decelerated.
[0053]
For this reason, in the first embodiment, the horizontal excitation force generated when the X table 7 moves / stops may not be suppressed.
[0054]
(Second embodiment)
Next, a second embodiment of the present invention will be described.
[0055]
FIG. 7 is a control block diagram according to the second embodiment of the present invention. Components having the same or the same functions as those in FIG.
[0056]
The high-pass filter 100 is disposed between the driver 43 and the multiplier 44, and the torque command value 60 output from the driver 43 to the motor 11 a is input to the multiplier 44 via the high-pass filter 100. The adder 52 is connected to the output side of the multiplier 44 and the output sides of the multipliers 47 and 49.
[0057]
FIG. 8 is a diagram illustrating an example of characteristics of the high-pass filter 100. A solid line indicates the torque command value 60 from the driver 43 that is an input of the high-pass filter 100, and a broken line indicates the output value 101 of the high-pass filter 100. .
[0058]
As shown in the figure, the phase of the output value 101 of the high-pass filter 100 advances with respect to the torque command value 60. Here, since the delay time ΔT of the control system is a value unique to the apparatus, if the high-pass filter 100 having a corner frequency such that the advance time Δt corresponding to the phase difference is equal to the delay time ΔT of the control system is selected, the control is performed. The system delay time ΔT can be offset by the advance time Δt. That is, the weight 18 can be accelerated / decelerated at the same timing in the opposite direction to the acceleration / deceleration direction of the X table 7.
[0059]
As a result, the horizontal excitation force generated when the X table 7 starts or stops moving is offset (or reduced) by the horizontal excitation force generated by the movement of the weight 18. The laser drilling machine 2 does not generate rocking vibration and does not generate floor vibration.
[0060]
As the value of the advance time Δt, a value when the torque command value becomes 0 at the time of deceleration may be used.
[0061]
In the above description, it has been described that the maximum torque during acceleration and the maximum torque during deceleration are the same in absolute value. However, since there is friction between the ball screw 10a and the ball nut 16, it is usually necessary to make the absolute value of the maximum torque during acceleration larger than the absolute value of the maximum torque during deceleration.
[0062]
Therefore, if the torque command value 60 when the X table 7 is stopped is set to a value slightly smaller than the frictional force acting between the ball screw 10a and the ball nut 16 (an offset is provided in the torque command value 60). It is possible to increase the response speed of the X table 7 at the time of activation.
[0063]
FIG. 9 is a diagram illustrating a characteristic example of the high-pass filter 100 in such a case, that is, when an offset is provided in the torque command value 60.
[0064]
As shown in the figure, even when the offset α is provided in the torque command value 60, the output value 101 in the stopped state becomes 0, so that the weight 18 can be returned almost to the origin.
[0065]
Instead of the high pass filter 100, phase advance means for advancing a preset time phase from when the torque command value is commanded may be used. Further, the phase advance time in this case is set to a time substantially equal to the time from when the torque command value is commanded to when the command is output to the spindle driving device.
[0066]
As described above, according to the present invention, even if the weight 18 is repeatedly moved in accordance with the movement of the X table 7, the weight 18 can always be moved from the vicinity of the origin, and therefore the position of the weight 18 needs to be adjusted. And easy to maintain.
[0067]
Further, since the pressurizing force applied to the ball screw 10b can be increased (the frictional force between the ball screw 10b and the ball nut is increased), the gap between the two can be surely eliminated, and the positioning accuracy is improved. be able to.
[0068]
Furthermore, since the active mass damper can be configured in a compact manner, it can be easily applied to a laser drilling machine or the like that does not include an active mass damper that is already in operation.
[0069]
Moreover, although the reduction of floor vibration due to the excitation force of the X table has been described, an active mass damper for the Y table may be provided if necessary.
[0070]
Furthermore, the speed control signal of the X table 7 output from the table drive controller 42 may be used for controlling the weight 18 so that the speed of the motor 11b is controlled by the driver 41.
[0071]
Further, although the case where one active mass damper is provided has been described, two active mass dampers may be provided and installed on both sides of the bed 6. When installed on both sides, only a horizontal force can be applied to the bed 6, which is more effective than a single case.
[0072]
【The invention's effect】
As described above, according to the present invention, by controlling the weight of the active mass damper, it is possible to reliably suppress the rocking vibration of the laser drilling machine caused by the table movement without time delay, thereby preventing floor vibration. can do. Further, since the weight is always moved from the origin, it is not necessary to adjust the position of the weight, and maintenance is easy.
[Brief description of the drawings]
FIG. 1 is a front view of a laser drilling machine according to a first embodiment of the present invention.
FIG. 2 is a plan sectional view of an active mass damper according to the present invention.
FIG. 3 is a control block diagram of an active mass damper according to the present invention.
4 is an example of a time history of a torque command value output from a driver 43. FIG.
FIG. 5 is a control block diagram of an active mass damper showing a modification of the present invention.
FIG. 6 is a control block diagram of an active mass damper showing a modification of the present invention.
FIG. 7 is a control block diagram of an active mass damper according to a second embodiment of the present invention.
FIG. 8 is an example of a time history of input / output characteristics of a high-pass filter.
FIG. 9 is an example of a time history of input / output characteristics of a high-pass filter.
[Explanation of symbols]
11b Motor 1 7 Encoder 18 Weight 43 Driver

Claims (4)

A support device that supports a weight in a horizontal direction, a weight drive device that drives the weight, and a controller that controls the weight drive device. The movement direction of the weight is the movement of the moving part of the processing machine. In an active mass damper arranged in the processing machine so as to be parallel to the direction,
A determination means for determining that the moving unit has entered a stopped state;
The controller drives the weight driving device by feedforward control based on a torque command value commanded to the driving unit of the moving unit and feedback control based on displacement of the weight ,
When the determination unit determines that the moving unit is in a stopped state,
The active mass damper , wherein the controller positions the weight at the center of the movement stroke based on an integrated value of displacement of the weight . If the previous SL mobile unit is determined by the determining means that the stop state, the controller is active mass damper of claim 1, wherein the switching the control gain about displacement of the weight to a high gain. A support device that supports a weight in a horizontal direction, a weight drive device that drives the weight, and a controller that controls the weight drive device. The movement direction of the weight is the movement of the moving part of the processing machine. In an active mass damper arranged in the processing machine so as to be parallel to the direction,
Phase advance means for advancing a preset time phase from the time when a torque command value is commanded to the motor that drives the moving part of the processing machine;
A controller that drives the weight driving device by feedback control based on the torque specified value and the weight displacement, the phase of which is output from the phase advance means;
Akti mass damper, characterized in that it comprises a. 4. The active mass damper according to claim 3, wherein the preset time is substantially equal to a time from when the torque command value is commanded to when the command is output to the spindle driving device. .

Images