JP2013166151A - Laser beam machining device and laser beam machining method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laser beam machining device capable of avoiding instability of a galvano scanner without causing reduction in machining speed.SOLUTION: A scanner controller controls a galvano scanner. The scanner controller stores or calculates standard torque with respect to each of a pair of the galvano scanners. When an irradiation point of a laser beam is moved from a present position to a target position, moved distances between the present position and the target position in directions corresponding to each of the pair of galvano scanners are obtained. In the moved distances in the directions corresponding to each of the pair of galvano scanners, when the shorter moved distance is below a limit value, the galvano scanner corresponding to the direction moved distance of which is relatively long is made to generate the standard torque of the galvano scanner, and the galvano scanner corresponding to the direction moved distance of which is relatively short is made to generate torque smaller than the standard torque of the galvano scanner.

Description

  The present invention relates to an apparatus for performing laser processing by positioning a laser beam irradiation position with a galvano scanner, and a laser processing method.

  A laser processing apparatus such as a laser drill uses a pair of galvano scanners that scan a laser beam in two directions (x direction and y direction). The galvano scanner includes a mirror that reflects a laser beam, a motor that rotates the mirror, and an encoder that measures the rotation angle of the rotation shaft of the motor. Galvano scanners have a natural frequency that depends on their structure.

  In order to move the irradiation position of the laser beam, the mirror angle is controlled. The irradiation position is represented by a combination of mirror angles of the two mirrors. The operation command of the irradiation position is given as a target absolute angle of the mirror or a relative angle from the current mirror angle to the target absolute angle. When receiving the operation command, the galvano scanner rotates the motor so that the mirror angle becomes the target angle. In a laser processing apparatus such as a laser drill, it is desired to make as many holes as possible in as short a time as possible. In order to shorten the movement time of the irradiation position of the mirror, the angular acceleration of the motor is increased and stable control is desired. The angular acceleration of the motor is proportional to the motor torque.

  However, the operating frequency of the shift galvano scanner up to the target angle approaches the natural frequency. When the operating frequency of the galvano scanner approaches the natural frequency, the operation of the galvano scanner becomes vibrational and tends to be unstable in terms of control. In order to prevent the operation from becoming oscillating and from being unstable in terms of control, it is desirable to operate so that the operating frequency of the galvano scanner approaches the natural frequency.

  A large number of machining points where holes should be formed are distributed on the surface of the workpiece to be drilled. When drilling, a laser beam is irradiated to these processing points in order. When the irradiation point of the laser beam is moved to the next processing point to be processed, the controller sends an operation command to the pair of galvano scanners. This operation command satisfies the condition that the galvano scanner does not become oscillating and unstable in terms of control (this condition is referred to as “stable operation condition”), and the movement time to the target position is as short as possible. Is generated.

JP 2009-56474 A

  The movement distance in the x direction and the movement distance in the y direction from the processed machining point to the next machining point to be machined may differ greatly. Even in such a case, the pair of galvano scanners are controlled such that each motor satisfies the stable operation condition and the moving time to the target position is as short as possible. When the moving distance in one direction is extremely shorter than the moving distance in the other direction, the time required for the galvano scanner corresponding to the short moving distance to reach the target position compared to the other galvano scanner Becomes extremely short.

A short moving time in a direction in which the moving distance is short means that the operating frequency of the mirror of the galvano scanner corresponding to that direction is high. For this reason, the operating frequency of the mirror approaches the natural frequency and approaches the limit region of stable operating conditions.

  An object of the present invention is to provide a laser processing apparatus and a laser processing method capable of avoiding a controllable unstable operation of a galvano scanner without causing a decrease in processing speed.

According to one aspect of the invention,
A laser light source for emitting a laser beam;
A pair of galvano scanners that move the irradiation points of the laser beam emitted from the laser light source in different directions on the surface of the workpiece;
A scanner controller for controlling the galvano scanner,
The scanner controller
For each of the pair of galvano scanners, a standard torque is stored or calculated,
When moving the irradiation point of the laser beam from the current position to the target position, obtain a moving distance in a direction corresponding to each of the pair of galvano scanners from the current position to the target position,
Of the moving distances in the direction corresponding to each of the pair of galvano scanners, the shorter moving distance is compared with a limit value, and when the shorter moving distance is less than the limit value, the moving distance is relatively The galvano scanner corresponding to the long direction is caused to generate the standard torque of the galvano scanner, and the galvano scanner corresponding to the direction having a relatively short moving distance is caused to generate a torque smaller than the standard torque of the galvano scanner. A laser processing apparatus is provided.

According to another aspect of the invention,
A method of performing laser processing by irradiating the laser beam on the workpiece via a pair of galvano scanners that move the laser beam in different directions on the workpiece,
Obtaining a movement distance in a direction corresponding to each of the pair of galvano scanners when moving from the current position of the irradiation point of the laser beam to a target position;
Of the movement distances in the direction corresponding to each of the pair of galvano scanners, comparing the shorter movement distance,
In the step of comparing, when it is determined that the shorter moving distance is less than the limit value, the acceleration of the movement in the direction in which the moving distance is relatively short is represented by the acceleration of the movement in the direction in which the moving distance is relatively long. A step of moving the irradiation point of the laser beam smaller than the acceleration, and
And a step of emitting the laser beam after the irradiation point of the laser beam reaches the target position.

  By generating a torque smaller than the standard torque of the galvano scanner in the galvano scanner corresponding to the direction in which the moving distance is relatively short, the operation stability of the galvano scanner can be improved. The moving time of the laser beam irradiation point is limited by the moving time of the mirror of the galvano scanner corresponding to a relatively long direction. For this reason, even if the torque generated in the galvano scanner corresponding to the direction in which the movement distance is relatively short is reduced, the movement time of the laser beam irradiation point to the target position as a whole does not become long.

FIG. 1 is a schematic diagram of a laser processing apparatus according to an embodiment. FIG. 2 is a plan view showing an example of processing points defined on the surface of the processing object. FIG. 3A, FIG. 3B, and FIG. 3C are graphs showing examples of temporal variations in the acceleration, velocity, and position of the irradiation point of the laser beam when the laser processing apparatus according to the example is used. FIG. 4A, FIG. 4B, and FIG. 4C are graphs each showing an example of temporal variation of the acceleration, velocity, and position of the irradiation point of the laser beam when the laser processing apparatus according to the embodiment is used. FIG. 5A, FIG. 5B, and FIG. 5C are graphs showing examples of temporal variations in the acceleration, velocity, and position of the laser beam irradiation point when the laser processing apparatus according to the comparative example is used. FIG. 6 is a flowchart of the laser processing method according to the embodiment.

  FIG. 1 shows a schematic diagram of a laser processing apparatus according to an embodiment. The laser light source 10 emits a pulse laser beam. As the laser light source 10, for example, a carbon dioxide laser, a YAG laser, or the like can be used. When the laser light source 10 receives a trigger signal from the host device 30 such as a personal computer, the laser light source 10 emits a laser pulse.

  The beam section of the laser beam emitted from the laser light source 10 is shaped by the beam shaping optical system 11. The shaped laser beam is reflected by the bending mirror 13 and then enters the workpiece 40 via the x galvano scanner 15, the y galvano scanner 16, and the fθ lens 18. The workpiece 40 is, for example, a printed circuit board, and is held on the xy stage 19. An xyz orthogonal coordinate system in which the surface of the workpiece 40 is the xy plane and the normal direction is the z direction is defined.

  The x galvano scanner 15 moves the irradiation position of the laser beam in the x direction on the surface of the workpiece 40. The y galvano scanner 16 moves the irradiation position of the laser beam in the y direction on the surface of the workpiece 40. The moving direction by the x galvano scanner 16 and the moving direction by the y galvano scanner 16 are not necessarily orthogonal to each other. The laser beam can be irradiated to an arbitrary position within the surface of the workpiece 40 in the direction in which both intersect.

  The fθ lens 18 forms an image of the beam cross-section shaped by the beam shaping optical system 11 on the surface of the workpiece 40, and the laser beam is shaken in two directions by the x galvano scanner 15 and the y galvano scanner 16. Is vertically incident on the surface of the workpiece 40.

  The x galvano scanner 15 includes a mirror 15A, a motor 15B, and an encoder 15C. Similarly, the y galvano scanner 16 includes a mirror 16A, a motor 16B, and an encoder 16C. The motors 15B and 16B rotate the mirrors 15A and 16A, respectively. The encoders 15C and 16C measure the rotation angles from the reference position of the rotation shafts of the motors 15B and 16B, respectively. The rotation angles measured by the encoders 15C and 16C are input to the scanner controller 20.

  The scanner controller 20 controls the galvano scanner 15 for x and the galvano scanner 16 for y. Specifically, the scanner controller 20 transmits a command signal for causing the motors 15 </ b> A and 16 </ b> A to generate torque to the x galvano scanner 15 and the y galvano scanner 16.

The host device 30 stores the coordinates of a plurality of machining points at which holes are to be formed in the workpiece 40 and the machining order. Laser processing is performed by sequentially transmitting the coordinates of the processing points from the host device 30 to the scanner controller 20. Actually, the target angle of the mirror of the galvano scanner is given to the scanner controller 20, but the angle of the mirror and the irradiation position of the laser beam have a one-to-one correspondence. For this reason, the angular acceleration, angular velocity, and angle of the mirror correspond to the acceleration, velocity, and position of the laser beam irradiation point. In the following description, the acceleration, velocity, and position of the laser beam irradiation point can be read as angular acceleration, angular velocity, and angle of the mirror.

  The scanner controller 20 stores the current position of the laser beam irradiation point and the target position of the movement destination. The target position is included in the command signal from the host device 30. Further, the scanner controller 20 stores or calculates the x-direction standard torque and the y-direction standard torque. Here, “calculate standard torque” means, for example, a process of obtaining a preferable torque by performing an evaluation experiment with various torques, and storing the obtained preferable torque as a standard torque in a temporary cache memory or the like. .

  The standard torque for the x direction and the standard torque for y are standard values of torque generated by the motor 15B of the galvano scanner 15 for x and the motor 16B of the galvano scanner 16 for y, respectively. The standard value is set to a large value so as to shorten the movement time as much as possible under the condition that the operation of the galvano scanner 15 for x and the galvano scanner 16 for y is not unstable due to the influence of the natural frequency. .

  FIG. 2 shows an example of processing point arrangement. A plurality of processing points P1, P2, and P3 are defined on the surface of the processing object 40. A laser beam is irradiated in the order of the processing points P1, P2, and P3. The coordinates of the processing points P1, P2, and P3 are (x1, y1), (x2, y2), and (x3, y3), respectively. The movement distances Lx1 and Ly1 in the x direction and y direction when moving the laser beam irradiation position from the processing point P1 to P2 are x2-x1 and y2-y1, respectively. The movement distances Lx2 and Ly2 in the x and y directions when moving the laser beam irradiation position from the processing point P2 to P3 are x3-x2 and y3-y2, respectively.

  The movement distance Ly2 is significantly shorter than the movement distance Lx2. On the other hand, the difference between the movement distances Lx1 and Ly1 is smaller than the difference between the movement distances Lx2 and Ly2.

  FIGS. 3A to 3C show time variations in acceleration, speed, and position when the laser beam irradiation point is moved from the processing point P1 to P2. 3A to 3C show an example in which the movement distance Ly1 in the y direction is shorter than the movement distance Lx1 in the x direction.

  The horizontal axis of FIG. 3A represents elapsed time, and the vertical axis represents acceleration. The acceleration ax in the x direction and the acceleration ay in the y direction are proportional to the torques generated by the motors 15B and 16B of the galvano scanner 15 for x (FIG. 1) and the galvano scanner 16 for y (FIG. 1), respectively. When the motor 15B of the x galvano scanner 15 generates the x-direction standard torque, the x-direction component of the acceleration at the irradiation point of the laser beam is referred to as the x-direction standard acceleration. Similarly, when the motor 16B of the galvano scanner for y 16 generates the y-direction standard torque, the y-direction component of the acceleration at the laser beam irradiation point is referred to as the y-direction standard acceleration. FIG. 3A shows a case where the x-direction standard acceleration and the y-direction standard acceleration are both ar. Note that the x-direction standard acceleration and the y-direction standard acceleration are not necessarily equal.

  In the first half of the moving time, the x component ax and y component ay of the acceleration of the irradiation point of the laser beam are both equal to the standard acceleration ar, and in the second half, the x component ax and y component ay of the acceleration are negative, Its absolute value is equal to the standard acceleration ar. When the movement distances Lx1 and Ly1 are not equal, the acceleration time in the x direction and the acceleration time in the y direction are not the same.

  The horizontal axis of FIG. 3B represents elapsed time, and the vertical axis represents speed. The gradients of the x component vx and the y component vy of the velocity during the acceleration period of the laser beam irradiation point are the same, and the gradients of the x component vx and the y component vy of the velocity during the deceleration period are the same.

  The horizontal axis in FIG. 3C represents elapsed time, the left vertical axis represents the x coordinate, and the right vertical axis represents the y coordinate. Since the movement distance Ly1 in the y direction is shorter than the movement distance Lx1 in the x direction, first, the y coordinate of the laser beam irradiation point reaches the y coordinate y2 of the target position, and then the x coordinate of the laser beam irradiation point is The x coordinate x2 of the target position is reached.

  FIGS. 4A to 4C show temporal variations in acceleration, speed, and position when the laser beam irradiation point is moved from the processing points P2 to P3. 4A to 4C show examples in which the movement distance Ly2 in the y direction is significantly shorter than the movement distance Lx2 in the x direction.

  The horizontal axis of FIG. 4 represents elapsed time, and the vertical axis represents acceleration. The x-direction standard torque is generated in the motor 15B of the galvano scanner 15 for x (FIG. 1). In contrast, the motor 16B of the y galvano scanner 16 (FIG. 1) generates a torque smaller than the y-direction standard torque. For this reason, the x component of the acceleration at the irradiation point of the laser beam is equal to the x-direction standard acceleration ar. The y component ae of the acceleration of the laser beam irradiation point is smaller than the y-direction standard acceleration ar.

  The horizontal axis of FIG. 4B represents elapsed time, and the vertical axis represents the speed of the laser beam irradiation point. Since the acceleration ay in the y direction is smaller than the acceleration ax in the x direction, the slope of the y component vy of the velocity during the acceleration period is smaller than the slope of the x component vx.

  The horizontal axis in FIG. 4C represents elapsed time, the left vertical axis represents the x coordinate, and the right vertical axis represents the y coordinate. The change in the y coordinate of the laser beam irradiation point is more gradual than the change in the x coordinate.

  FIG. 5A to FIG. 5C show acceleration, speed, and time variation of the position when the laser beam irradiation position is moved from the processing point P2 to the processing point P3 by the method according to the comparative example.

  As shown in FIG. 5A, in the comparative example, the irradiation point of the laser beam is accelerated and decelerated at the standard acceleration ar without depending on the magnitude relationship between the movement distances Lx2 and Ly2. As shown in FIG. 5B, the inclination of the x component of the velocity of the laser beam irradiation point is equal to the inclination of the y component. As shown in FIG. 5C, the y coordinate of the irradiation point of the laser beam reaches the y coordinate y3 of the processing point P3 that is the target position in a very short time.

  In the comparative example, the cycle of acceleration and deceleration by the y galvano scanner 16 (FIG. 1) is shortened. That is, the operating frequency of the y galvano scanner 16 is increased. Since the y-direction standard torque is set so as to satisfy the conditions for the stable operation of the y-galvano scanner 16, the operation immediately becomes unstable even if the operating frequency of the y-galvano scanner 16 increases. There is nothing. However, when the operating frequency is increased, the operation is likely to be unstable due to disturbance or the like.

  In the embodiment, as shown in FIGS. 4A to 4C, the acceleration and deceleration times of the laser beam irradiation point are longer than the acceleration and deceleration times of the comparative example shown in FIGS. 5A to 5C. That is, in the method according to the embodiment, the operating frequency of the galvano scanner 16 for y is lower than the method according to the comparative example. For this reason, the stability of the operation of the galvano scanner 16 for y can be increased.

The torque generated by the motor 16B of the y galvano scanner 16 is set such that the movement time in the y direction from the machining point P2 to the machining point P3 does not exceed the movement time in the x direction. Therefore, even if the operating frequency of the y galvano scanner 16 is lowered, the moving time from the processing point P2 to the processing point P3 does not increase.

  As described above, when the method according to the embodiment is employed, the stability of the operation of the galvano scanner can be increased without increasing the movement time of the laser beam irradiation point.

  FIG. 6 shows a flowchart of a laser processing method according to the sixth embodiment. Each step of the flowchart is executed by the scanner controller 20 (FIG. 1).

  The scanner controller 20 receives the coordinates (target position) of the machining point to be machined next from the host device 30. In step S1, the moving distance in the x direction and the moving distance in the y direction are calculated from the current position and the target position of the laser beam irradiation point.

  In step S2, it is determined whether or not the difference between the movement distance in the x direction and the movement distance in the y direction exceeds a determination reference value. As an example, the difference between the movement distance Lx1 in the x direction and the movement distance Ly1 in the y direction shown in FIG. 2 is smaller than the determination reference value. The difference between the movement distance Lx2 in the x direction and the movement distance Ly2 in the y direction exceeds the determination reference value.

  Note that, as a determination target, a moving distance ratio may be adopted instead of the moving distance difference. For example, it may be determined whether the ratio of the longer movement distance to the shorter movement distance exceeds a determination reference value.

  If the difference or ratio between the movement distance in the x direction and the movement distance in the y direction exceeds the determination reference value, step S3 is executed, and if the difference or ratio between the two is equal to or less than the determination reference value, Step S4 is executed.

  In step S3, the standard torque of the galvano scanner (in FIGS. 4A to 4C) is applied to the galvano scanner (in the case of FIGS. 4A to 4C, x galvano scanner 15) corresponding to the direction in which the moving distance is relatively long. In the case, x-direction standard torque) is generated. This standard torque corresponds to the standard acceleration ar shown in FIG. 4A. Further, the galvano scanner corresponding to the direction in which the moving distance is relatively short (in the case of FIGS. 4A to 4C, the galvano scanner 16 for y) is smaller than the standard torque (y direction standard torque) of the galvano scanner. Generate torque. This small torque corresponds to the torque ae shown in FIG. 4A.

  This small torque is determined so as to satisfy the condition that the moving time of the laser beam irradiation point in the direction in which the moving distance is relatively short does not exceed the moving time in the direction in which the moving distance is relatively long. . This condition restricts the lower limit value of the relatively small torque.

  Compare the distance traveled by the galvano scanner with the shorter travel distance with a preset limit value. When the shorter travel distance falls below the limit value, the torque generated by the galvano scanner is the standard torque. It is preferable to make it smaller. As a result, a sufficient effect of improving the stability of the operation of the galvano scanner can be obtained.

  In step S4, standard torque is generated in both of the pair of galvano scanners.

After step S3 or step S4, it is determined in step S5 whether or not the laser beam irradiation point has reached the target position. This determination can be made based on the outputs of the encoder 15C of the x galvano scanner 15 and the encoder 16C of the y galvano scanner 16. If the irradiation point has not reached the target position, the x galvano scanner 15 and the y galvano scanner 16 are operated until the target position is reached.

  If it is determined in step S5 that the irradiation point has reached the target position, in step S6, the host device 30 outputs a trigger signal to the laser light source 10 (FIG. 1) to emit a laser pulse.

  In step S <b> 7, it is determined whether or not processing of all processing points defined on the surface of the processing object 40 has been completed. When an unprocessed processing point remains, the process returns to step S1 to execute a step of moving the laser beam irradiation point to the next target position. When it is determined that all the processing points have been processed, the laser processing is ended.

  Although the present invention has been described with reference to the embodiments, the present invention is not limited thereto. It will be apparent to those skilled in the art that various modifications, improvements, combinations, and the like can be made.

DESCRIPTION OF SYMBOLS 10 Laser light source 11 Beam shaping optical system 13 Bending mirror 15 X Galvano scanner 15A Mirror 15B Motor 15C Encoder 16 Y Galvano scanner 16A Mirror 16B Motor 16C Encoder 18 fθ lens 19 xy stage 20 Scanner controller 30 Host device 40 Work object

Claims (4)

A laser light source for emitting a laser beam;
A pair of galvano scanners that move the irradiation points of the laser beam emitted from the laser light source in different directions on the surface of the workpiece;
A scanner controller for controlling the galvano scanner,
The scanner controller
For each of the pair of galvano scanners, a standard torque is stored or calculated,
When moving the irradiation point of the laser beam from the current position to the target position, obtain a moving distance in a direction corresponding to each of the pair of galvano scanners from the current position to the target position,
Of the moving distances in the direction corresponding to each of the pair of galvano scanners, the shorter moving distance is compared with a limit value, and when the shorter moving distance is less than the limit value, the moving distance is relatively The galvano scanner corresponding to the long direction is caused to generate the standard torque of the galvano scanner, and the galvano scanner corresponding to the direction having a relatively short moving distance is caused to generate a torque smaller than the standard torque of the galvano scanner. Laser processing equipment.   The scanner controller is configured such that the movement distance of the laser beam irradiation point in the direction in which the movement distance is relatively short does not exceed the movement time in the direction in which the movement distance is relatively long. The laser processing apparatus according to claim 1, wherein a torque to be generated by the galvano scanner corresponding to a short direction is determined. A method of performing laser processing by irradiating the laser beam on the workpiece via a pair of galvano scanners that move the laser beam in different directions on the workpiece,
Obtaining a movement distance in a direction corresponding to each of the pair of galvano scanners when moving from the current position of the irradiation point of the laser beam to a target position;
Of the movement distances in the direction corresponding to each of the pair of galvano scanners, comparing the shorter movement distance,
In the step of comparing, when it is determined that the shorter moving distance is less than the limit value, the acceleration of the movement in the direction in which the moving distance is relatively short is represented by the acceleration of the movement in the direction in which the moving distance is relatively long. A step of moving the irradiation point of the laser beam smaller than the acceleration, and
And a step of emitting the laser beam after an irradiation point of the laser beam reaches the target position.   The laser beam irradiation point is moved so that the movement time of the laser beam irradiation point in the direction in which the movement distance is relatively short does not exceed the movement time in the direction in which the movement distance is relatively long. Item 4. The laser processing method according to Item 3.

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