JP2009255150A - Laser machining apparatus and laser machining method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laser machining apparatus and a laser machining method, capable of excellently forming point-marks machined with laser beams of immediately after the start of machining. <P>SOLUTION: The laser machining apparatus machines the surface of a workpiece 10 loaded on a table 21 from the start point of laser machining by irradiating the surface of the workpiece 10 with a laser beam while rotating the table 21. While a laser beam for non-machining is emitted from a laser source 31 for machining, an offset signal generating circuit 62 generates an offset signal of a level corresponding to a change from the focal distance of an objective lens 35 in the incidence of a laser beam for non-machining to the focal distance of the objective lens 35 in the incidence of a laser beam for machining, and offsets the focal position of the laser beam. Thus, when the emission of the laser beam for non-machining is switched to the emission of the laser beam for machining, the offset signal generation from the offset signal generating circuit 62 is stopped, and the laser beam is focused on the surface of the workpiece 10. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a laser processing apparatus and a laser processing method for forming fine pits, continuous grooves, or reaction traces on a surface of a processing target by irradiating the surface of the processing target with laser light.

Conventionally, a processing object is fixed to a disk-shaped table or a drum-shaped fixing jig, and while rotating the table or the fixing jig, the processing object is irradiated with laser light from the processing head, and the irradiation position of the laser light Is moved in the radial direction or the rotational axis direction to form fine pits, continuous grooves, or reaction traces that are the basis for forming these by etching (hereinafter collectively referred to as processing). Laser processing apparatuses that form a trace) are known. In such a laser processing apparatus, the surface of the processing object slightly fluctuates in the optical axis direction of the laser light due to the rotation of the processing object. In order to always make the focal position of the laser beam coincide with the surface of the object to be processed even if there is such a slight change in the surface of the object to be processed, this type of laser processing apparatus is disclosed in, for example, Patent Document 1 below. As described above, focus servo control for driving the objective lens in the optical axis direction of the laser beam is performed using a signal generated by the reflected light from the surface of the workpiece.
JP 2001-243663 A

  On the other hand, in this type of laser processing apparatus, laser processing that makes the laser processing start point and the laser processing end point the same may be performed for each radial position or for each axial position. That is, in laser processing in which the irradiation position of laser light is moved in the radial direction using a disk-shaped table, a plurality of concentric processing marks are formed on the surface of the disk-shaped workpiece as shown in FIG. There are things to do. Further, in laser processing in which the irradiation position of laser light is moved in the direction of the rotation axis using a drum-shaped fixing jig, a plurality of circular processing marks may be formed at predetermined intervals in the direction of the rotation axis of the drum. . In such laser processing, when the laser processing at one radial position or axial position is completed, the laser beam irradiation intensity is switched to non-processing, that is, non-processing smaller than the processing laser irradiation intensity. The laser beam irradiation position is moved to the next radial position or axial position. Then, after moving the irradiation position of the laser beam to the next radial position or axial position, the irradiation intensity of the laser beam is switched to processing, that is, the laser irradiation for processing larger than the non-processing laser irradiation intensity. Switch to intensity and perform laser processing.

  In the laser processing as described above, the present inventor has good initial laser processing traces immediately after switching from the non-processing laser irradiation intensity to the processing laser irradiation intensity, that is, at each radial position or each axial position. I found that it was not formed. In particular, this phenomenon becomes more prominent as the processing trace becomes finer. FIG. 9A shows an example in which a continuous groove-shaped processing trace is not formed well. The width of the processing trace is narrower than the normal width immediately after the start of laser processing, and then gradually increases. It has become a normal width. FIG. 9B shows an example in which a plurality of pit-shaped processing marks are not formed satisfactorily. Immediately after the start of laser processing, the pit diameter is smaller than the normal pit diameter, and then gradually. It becomes larger and has a normal diameter.

  As a result of investigating the reason why the processing trace is not satisfactorily formed, the present inventor has concluded that this cause is due to the following reason. The first reason is that when the intensity of the laser beam emitted from the laser light source changes, the wavelength of the laser beam slightly changes. Generally, when the intensity of laser light increases, the wavelength of the laser light increases although it is very small, as shown in FIG. That is, when the non-processing laser beam is switched to the processing laser beam, the wavelength of the laser beam increases. When the laser beam is condensed by the convex lens, immediately after the wavelength of the laser beam increases, the focal position of the laser beam moves from the surface of the workpiece to the inside of the workpiece as shown in FIG. Shift. Further, when a plurality of lenses are used in the optical system for condensing the laser light, the focal position of the laser light may be shifted from the surface of the workpiece to the lens side, contrary to the above case. This shift in the focal position is recovered thereafter by focus servo control. However, as shown by the change in the focus error signal in FIG. 12, some time is required for the recovery. In this state where the focal position is shifted, the processing trace is not accurately formed on the surface of the processing target.

  The second reason is that the surface of the processing object in the vicinity of the focal point is heated by the high-intensity laser light when the surface of the processing object is continuously irradiated with high-intensity laser light for processing. Has risen to some extent. Therefore, the temperature of the surface of the object to be processed at the position that is actually processed by the laser light has risen in advance, and a processing trace is easily formed. However, since the intensity of the non-processing laser beam is small, immediately after the intensity of the laser beam is switched from the small non-processing intensity to the large processing intensity, the processing at the position where the laser beam is actually processed is performed. The surface temperature of the object is low, and it is difficult to form a processing mark.

  The present invention has been made in order to cope with the above-described problems, and the purpose of the present invention is to form a good laser processing trace even immediately after switching from the non-processing laser irradiation intensity to the processing laser irradiation intensity. An object of the present invention is to provide a laser processing apparatus and a laser processing method.

  In order to achieve the above object, the present invention is characterized in that a set portion for setting a workpiece, a rotating means for rotating the set portion, and a laser beam for laser processing the surface of the workpiece are emitted. A processing laser light source for processing, an objective lens for condensing the emitted laser light, a processing head including a focus actuator for driving the objective lens in the optical axis direction of the laser light, and reflected light from the surface of the processing object A focus servo control circuit that drives and controls the focus actuator by supplying a focus servo signal based on the focus actuator to maintain the focus position of the laser beam on the surface of the workpiece, and the irradiation position of the laser beam on the surface of the workpiece A driving signal is output to the moving means for moving the laser beam and the processing laser light source, and the intensity level corresponding to the level of the driving signal is output. The processing laser drive circuit for emitting the light to the processing laser light source and the moving means to move the irradiation position of the laser light to the laser processing start position, and the processing laser drive circuit to control the object to be processed A non-machining laser beam is emitted by emitting a non-machining laser beam having such a small intensity that the surface of the laser beam is not machined from the machining laser light source and operating the focus servo control circuit. And a laser processing device for processing the surface of the workpiece set on the set unit from the laser processing start position, with a control unit that emits a processing laser beam having an intensity greater than the intensity of the light from the processing laser light source. In addition, from the focal length of the objective lens when the non-processing laser beam is incident, the focal point of the objective lens when the processing laser beam is incident An offset signal generation circuit that generates an offset signal of a level corresponding to the change to the separation and is superimposed on the focus servo signal is provided, and the control means emits non-processing laser light from the processing laser light source When the offset signal generation circuit generates an offset signal, the focal position of the laser beam is shifted from the surface of the workpiece by a distance corresponding to the change, and the laser beam for processing is emitted from the emission of the non-processing laser beam. In switching to light emission, the offset signal generation circuit stops generating the offset signal so that the focal position of the laser beam coincides with the surface of the workpiece. In this case, the set unit is, for example, a table on which a processing target is placed and fixed, or a drum-shaped fixing member on which a processing target is wound and fixed on the outer peripheral surface.

  In the laser processing apparatus configured as described above, before the surface of the object to be processed is laser processed, the surface of the object to be processed is irradiated with a low-intensity non-processing laser beam, and the object lens is used. The focal position of the laser beam is offset. At the start of laser processing, a processing laser beam having a high intensity is irradiated onto the surface of the processing object, and the offset of the focal position of the laser beam by the objective lens is released. With this offset cancellation, even if the wavelength of the laser beam changes due to the intensity change of the laser beam emitted from the laser light source, the laser beam from the objective lens is immediately after switching from the non-processing laser beam to the processing laser beam. The focal position accurately matches the surface of the object to be processed, so that a laser processing trace can be satisfactorily formed.

  Further, another feature of the present invention is further provided with a reference position detecting means for detecting a reference position of rotation by the rotating means, and the control means switches and controls the processing laser drive circuit when detecting the reference position, The laser beam emitted from the processing laser light source is switched from a non-processing laser beam to a processing laser beam, or from a processing laser beam to a non-processing laser beam, and the control means Only when the processing laser beam is emitted from the processing laser light source, the moving means is controlled to move the irradiation position of the laser beam to the laser processing start position.

  In the circular laser processing in which the reference position is set as the processing start position and the processing end position, a plurality of different positions are laser processed one after another. Therefore, in such laser processing, since the laser processing is started at each of a plurality of different positions, the other features of the present invention are more effective.

  Another feature of the present invention is that the machining laser drive circuit transiently increases the level of the drive signal when switching from emission of non-machining laser light to emission of machining laser light, Thereafter, the level is returned to a predetermined level.

  In another aspect of the present invention configured as described above, the drive signal output from the processing laser drive circuit is increased for a predetermined short period of time immediately after switching to the processing intensity laser light. Since the processing laser light source emits laser light having an intensity corresponding to the level of the drive signal, immediately after switching to the laser light having the processing intensity, the temperature of the laser processing portion on the surface of the processing object increases. Becomes larger. As a result, even if the temperature of the laser processing location on the surface of the workpiece is not sufficiently increased immediately before switching to the processing intensity laser beam, the workpiece is laser processed satisfactorily due to the temperature increase. It becomes.

  Another feature of the present invention is that the surface of the object to be processed is positioned in front of the irradiation position of the laser light from the processing laser light source in the direction in which the laser light from the processing laser light source moves in the processing head. Further provided with a preheating laser light source for irradiating preheating laser light, and further, from the emission of the non-processing laser light to the processing laser drive circuit by the control means to the emission of the processing laser light. A delay circuit that delays switching by the moving time of the laser light irradiation position by the processing laser light source corresponding to the distance between the irradiation position of the laser light for preheating and the irradiation position of the laser light for processing, and for the residual heat Drive signal for driving the laser light source, which rises transiently when switching from non-processing laser light emission to processing laser light emission by the control means, and otherwise It outputs a drive signal to a predetermined level to preheat laser light source lies in the provision and preheating laser drive circuit for emitting a preheating laser source of laser light having an intensity corresponding to the drive signals.

    In another aspect of the present invention configured as described above, the temperature immediately before the laser light irradiation position by the processing laser light source is increased by the laser light irradiation by the preheating laser light source. Then, the intensity of the laser beam from the preheating laser light source is transiently controlled to be higher than the irradiation intensity before and after the start of laser processing. Therefore, the temperature of the laser processing portion on the surface of the processing object increases to the same extent as before even immediately before switching to the processing intensity laser light by the processing laser light source. As a result, the object to be processed can be satisfactorily laser processed.

  Furthermore, in carrying out the present invention, the invention is not limited to the invention of the laser processing apparatus for laser processing the workpiece, and the invention of the laser processing method for laser processing of the workpiece and the computer program for realizing the laser processing method Can also be implemented.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an overall schematic diagram of a laser processing apparatus according to the embodiment. The laser processing apparatus includes a table 21 as a support member that fixes and supports the workpiece 10 and a machining head 30 that irradiates the workpiece 10 with laser light to laser process the workpiece. . The table 21 is formed in a circular shape and is driven by a spindle motor 22 and a feed motor 23. The table 21 corresponds to the setting unit of the present invention.

The spindle motor 22 rotationally drives the table 21 through the rotation shaft 22a by the rotation. The spindle motor 22 incorporates an encoder 22b that detects the rotation of the motor 22, that is, the table 21, and outputs a rotation detection signal representing the rotation. This rotation detection signal is composed of an index signal Index generated every time the rotation position of the table 21 comes to one reference rotation position, and a pulse train signal that repeats a high level and a low level by a predetermined minute rotation angle and is mutually π A phase signal φ _A and a B phase signal φ _B that are out of phase by / 2. The index signal Index is supplied to the controller 70 described later. The A phase signal φ _A and the B phase signal φ _B are supplied to the spindle motor control circuit 51. The spindle motor control circuit 51 calculates the rotation speed of the spindle motor 22 using the A-phase signal φ _A and the B-phase signal φ _B from the encoder 22b, and the calculated rotation speed is determined by the controller 70 according to an instruction from the controller 70. The rotation of the spindle motor 22 is controlled so as to be equal to the designated rotational speed.

  The feed motor 23 rotates the screw rod 24 to drive the table 21 in the radial direction. The screw rod 24 is connected to one end of the screw rod 24 so as to rotate integrally with the rotation shaft of the feed motor 23, and is screwed to a nut (not shown) fixed to the support member 25 at the other end. The support member 25 fixedly supports the spindle motor 22 and is only allowed to move in the radial direction of the table 21. Therefore, when the feed motor 23 rotates, the spindle motor 22, the table 21, and the support member 25 are displaced in the radial direction of the table 21 by the screw mechanism including the screw rod 24 and the nut.

Also incorporated in the feed motor 23 is an encoder 23a that detects the rotation of the feed motor 23 and outputs the same rotation detection signals (index signal Index, A phase signal φ _A and B phase signal φ _B ) as the encoder 22b. It is. The A phase signal φ _A and the B phase signal φ _B are output to the radial position detection circuit 52. The radial position detection circuit 52 has a count circuit that counts up or counts down the A phase signal φ _A or the B phase signal φ _B from the encoder 23a in accordance with the rotation direction of the feed motor 23. Based on this, the radial position of the table irradiated with the laser light is calculated, and a detection signal representing the radial position is output to the feed motor control circuit 53 and the controller 70. The initial setting of the count circuit is performed according to an instruction from the controller 70 when the power is turned on.

That is, the controller 70 instructs the feed motor control circuit 53 to move the support member 25 to the initial position and the radial position detection circuit 52 at the time of power-on. In response to this instruction, the feed motor control circuit 53 rotates the feed motor 23 to move the support member 25 to the initial position. This initial position is a drive limit position of the support member 25 driven by the feed motor 23. The radial position detection circuit 52 continues to input the A phase signal φ _A or the B phase signal φ _B from the encoder 23a while the support member 25 is moving. When the support member 25 reaches the initial position and the rotation of the feed motor 23 stops, the radial position detection circuit 52 detects the stop of the input of the A phase signal φ _A or the B phase signal φ _B from the encoder 23a, and is built in. The count value of the count circuit is reset to “0”. At this time, the radial position detection circuit 52 outputs a signal for stopping the output to the feed motor control circuit 53, whereby the feed motor control circuit 53 stops outputting the drive signal to the feed motor 23. Thereafter, when the feed motor 23 is driven, the radial position detection circuit 52 counts up or down the A phase signal φ _A or the B phase signal φ _B according to the rotation direction of the feed motor 23, Based on the count value, the radial position of the table 21 irradiated with the laser light is calculated, and a signal representing the radial position is continuously output to the feed motor control circuit 53 and the controller 70.

  The feed motor control circuit 53 drives and controls the feed motor 23 in accordance with an instruction from the controller 70 to move the laser light irradiation position to the designated radius position on the table 21. Specifically, the feed motor control circuit 53 uses the radial position detected by the radial position detection circuit 52 when the controller 70 instructs to move the irradiation position of the laser beam to the designated radial position. And the feed motor 23 is rotated until the detected radial position becomes equal to the designated radial position.

  The processing head 30 includes a laser light source 31, a collimating lens 32, a polarizing beam splitter 33, a quarter wavelength plate 34, an objective lens 35, a condensing lens 36, a cylindrical lens 37, and a photodetector 38. In the processing head 30, the laser light from the laser light source 31 is condensed on the surface of the processing object 10 through the collimating lens 32, the polarization beam splitter 33, the quarter wavelength plate 34 and the objective lens 35. And a light spot is formed on the surface of the workpiece 10. The laser light source 31 is driven and controlled by a laser driving circuit 54 via a feedback control circuit 55.

  A condenser lens 41 and a light receiving element 42 are also provided in the processing head 30. The condensing lens 41 condenses the laser light incident on the polarizing beam splitter 33 from the laser light source 31 via the collimating lens 32 and slightly reflected by the polarizing beam splitter 33 on the light receiving element 42. The light receiving element 42 detects the intensity of the received laser light, that is, the laser light reflected by the polarization beam splitter 33, thereby supplying a signal representing the emission intensity of the laser light from the laser light source 31 to the feedback control circuit 55. .

  The laser drive circuit 54 responds to the non-processing intensity laser irradiation start command from the controller 70, as shown in FIGS. 3A and 3B, at a low level (that is, the non-processing level) L1. A drive signal composed of a direct current signal is output. This non-processing level L1 is low enough that the surface of the workpiece 10 is not laser-processed by irradiation of the laser light emitted from the laser light source 31 onto the surface of the workpiece 10, and focus servo control described later can be performed. Is set to have a level of Further, the laser drive circuit 54 responds to the command for starting the laser irradiation of the processing intensity from the controller 70, as shown in FIGS. 3 (a) and 3 (b). The drive signal is output. The drive signal at the machining level L2 in FIG. 3A is an example of a direct current signal for forming a continuous groove on the surface of the workpiece 10. The drive signal at the machining level L2 in FIG. 3B is an example of a pulse signal for forming fine pits on the surface of the workpiece 10. Note that the processing signal type (DC signal or pulse signal) output from the laser drive circuit 54 is controlled by the controller 70, and other types of signal waveforms are possible.

  The feature of the present embodiment is that the processing level (DC level in the case of a DC signal, pulse level in the case of a pulse signal) L2 is emitted from the laser light source 31 instead of the type of the waveform of the driving signal at the processing level L2. The surface of the workpiece 10 is high enough to be laser processed by irradiating the surface of the workpiece 10 with the laser beam. The processing level L2 drive signal naturally enables focus servo control to be described later. Further, the characteristics of the drive signal at these machining levels L2 are portions that become transiently higher than the steady machining level L2 at the time of continuous laser machining at the start, that is, when switching from the non-machining signal to the machining signal. It is a point having A. This is because immediately after the intensity of the laser beam is switched from a small intensity for non-machining to a large intensity for machining, the surface temperature of the workpiece at the position where the laser beam is actually machined is low. This is to avoid the formation of traces.

  The feedback control circuit 55 causes the laser light source 31 to emit laser light having an intensity corresponding to the non-processing level L1 and the processing level L2 of the drive signal by feedback control using the detection signal from the light receiving element 42.

  Further, the reflected light from the light spot formed on the surface of the workpiece 10 passes through the objective lens 35, the quarter wavelength plate 34, the polarization beam splitter 33, the condensing lens 36, and the cylindrical lens 37, and the photo detector. The light is guided to 38 and received. The photo detector 38 is constituted by four divided light receiving elements composed of four identical square light receiving elements divided by dividing lines, and each light receiving element receives detection signals Sa, Sb, Sc, Sd proportional to the amount of received light. Output as a received light signal. The detection signals Sa, Sb, Sc, and Sd represent the received light amounts of the respective light receiving elements arranged clockwise from the upper left. The machining head 30 also includes a focus actuator 43. The focus actuator 43 drives the objective lens 35 in the optical axis direction of the laser light (perpendicular to the surface of the workpiece 10).

  This laser processing apparatus includes an HF signal amplification circuit 56 that is connected to the photodetector 38 and amplifies the detection signals Sa, Sb, Sc, and Sd. A focus error signal generation circuit 57 is connected to the HF signal amplification circuit 56. The focus error signal generation circuit 57 calculates using the detection signals Sa to Sd from the photodetector 38 via the HF signal amplification circuit 56 (specifically, in the case of focus servo control by the astigmatism method, (Sa + Sc) − A focus error signal is generated by (calculation of (Sb + Sd)) and output to the focus servo circuit 58. The focus servo circuit 58 is controlled by the controller 70, generates a focus servo signal based on the focus error signal, and supplies the focus servo signal to the drive circuit 59. The drive circuit 59 drives and controls the focus actuator 43 according to the focus servo signal to displace the objective lens 35 in the optical axis direction. With these focus error signal generation circuit 57 and focus servo circuit 58, the objective lens 35 continues to focus the laser beam on the surface of the workpiece 10.

  An adder 61 is connected between the focus servo circuit 58 and the drive circuit 59. The adder 61 adds (that is, superimposes) the offset signal from the offset signal generation circuit 62 to the focus servo signal from the focus servo circuit 58 and outputs the result. The offset signal generation circuit 62 is controlled by the controller 70, and as shown in FIG. 4, outputs the offset signal in the non-machining state and stops outputting the offset signal in the machining state (that is, the level of the offset signal is “0”). ”). The level of the offset signal is shifted in the direction away from the surface of the workpiece 10 by a distance equal to the focal position deviation immediately after switching the intensity of the laser beam when the laser beam is not processed. That is, it is for offsetting, and is set to a value that shifts the focal position by the distance. Thereby, there is no shift in the focal position immediately after the intensity of the laser beam from the processing laser light source 31 is switched from the non-processing intensity to the processing intensity.

  The controller 70 is configured by a computer including a CPU, ROM, RAM, and non-volatile memory such as a hard disk, and executes the laser processing program shown in FIG. 2 in accordance with an instruction from an input device 71 such as a keyboard and a mouse. As a result, the laser processing apparatus is operated. The controller 70 is also connected with a display device 72 for visually informing the operator of the operation instruction and the operation status.

  Next, the operation of the laser processing apparatus configured as described above will be described. The operator turns on a power supply (not shown) of the laser processing apparatus to start operation of various circuits shown in FIG. When the power is turned on, the controller 70 instructs the radial position detection circuit 52 and the feed motor control circuit 53 to perform initial setting by executing a program (not shown). In response to this instruction, the radial position detection circuit 52 starts to output a signal representing the radial position where the laser beam is irradiated by the initial setting operation of the radial position detection circuit 52 and the feed motor control circuit 53 described above.

  Next, the controller 70 prompts the operator to input machining data necessary for machining the workpiece 10 using the display device 72 by executing a program (not shown). The operator uses the input device 71 to specify the laser processing start radius position, the laser processing end radius position, the processing pitch P in the radial direction, the rotational linear velocity of the laser beam spot with respect to the processing target 10, and the groove processing or pit processing. In the case of pit processing, the pit interval in the rotation direction is input. The controller 70 stores the input machining data in an internal storage device. Note that this processing may be omitted when the machining data is already stored in the controller 70.

  After execution of such initial processing, the laser machining program is started from step S10 in FIG. 2, and the controller 70 sets a variable n for moving the irradiation position of the laser beam in the radial direction to an initial value in step S12. Set to “0”. Next, in step S14, the controller 70 outputs the input laser machining start radius position to the feed motor control circuit 53 and instructs the laser beam irradiation position to move to the laser machining start radius position. To do. The feed motor control circuit 53 inputs the radius position detected by the radius position detection circuit 52 and controls the rotation of the feed motor 23 until the irradiation position of the laser beam coincides with the laser processing start radius position. To move. When the radial position detected by the radial position detection circuit 52 becomes equal to the laser processing start radial position, the feed motor control circuit 53 stops the rotation of the feed motor 23. Thereby, the irradiation position of a laser beam moves to the laser processing start radius position.

After the process of step S14, the controller 70 calculates the rotational speed of the spindle motor 22 by using the input laser processing start radius position and the rotational linear speed in step S16, and uses the calculated rotational speed as the spindle. Outputs to the motor control circuit 51 and instructs the spindle motor 22 to start rotating. The spindle motor control circuit 51 calculates the rotational speed of the spindle motor 22 using the A-phase signal φ _A and the B-phase signal φ _B from the encoder 22b, and the calculated rotational speed is the rotational speed input from the controller 70. The rotation of the spindle motor 22 is controlled so as to be equal to.

  After the process of step S16, the controller 70 instructs the laser drive circuit 54 to emit laser light having non-processing intensity in step S18. As shown in FIGS. 3A and 3B, the laser drive circuit 54 starts to output a drive signal of the non-processing level L1 to the laser light source 31 via the feedback control circuit 55. The laser light source 31 starts to emit laser light having non-processing intensity corresponding to the non-processing level L1. Therefore, the processing object 10 starts to be irradiated with non-processing intensity laser light. Then, a light spot is formed on the surface of the workpiece 10 by the irradiation of the laser light, and reflected light from the light spot starts to be detected by the photodetector 38.

  After the process of step S18, the controller 70 instructs the focus servo circuit 58 to start operation in step S20. At this time, the received light signal corresponding to the reflected light detected by the photodetector 38 is supplied to the focus error signal generating circuit 57 via the HF signal amplifying circuit 56, and the focus error signal generating circuit 57 responds to the reflected light. The focus error signal is output to the focus servo circuit 58. Therefore, the focus servo circuit 58 starts operating after drawing in focus by a focus actuator driving circuit and an S-shaped detection circuit (not shown) according to the operation start instruction, and the focus servo signal is focused via the adder 61 and the drive circuit 59. Focus servo control for supplying the actuator 43 to drive the objective lens 35 in the optical axis direction of the laser beam is started. That is, the focus servo circuit 58 starts to drive and control the focus actuator 43 so that the focal position of the laser beam by the objective lens 35 coincides with the surface of the workpiece 10.

  After the process of step S20, the controller 70 instructs the offset signal generation circuit 62 to generate an offset signal in step S22. In response to this, the offset signal generation circuit 62 starts outputting an offset signal of a predetermined level to the adder 61 as shown in FIG. The adder 61 adds (superimposes) an offset signal to the focus servo signal from the focus servo circuit 58 and supplies it to the drive circuit 59. The drive circuit 59 drives and controls the focus actuator 43 according to the focus servo signal added (superposed) with the offset signal. Therefore, the focus actuator 43 moves the objective lens 35 by an amount corresponding to the level of the offset signal in the direction away from the surface of the workpiece 10. As a result, in this state, the focal position of the laser beam by the objective lens 35 is a position away from the surface of the workpiece 10 by an amount corresponding to the level of the offset signal, as indicated by a broken line in FIG. In this state, the signal output from the focus servo circuit 58 is kept at a level representing the deviation of the focal position of the laser beam.

  After the process of step S22, the controller 70 starts time measurement in step S24, and determines in step S26 whether or not a predetermined short time has passed since the start of time measurement. Then, when the predetermined short time has elapsed, the controller 70 determines “Yes” in Step S26 and executes the processes after Step S28. The processes in steps S24 and S26 are performed so that laser processing is not started in response to the arrival of the index signal Index almost simultaneously with the timing at which the offset signal is output by the processes in and after step S28. In step S28, input of the index signal Index from the encoder 22b is awaited. That is, it waits until the irradiation position of the laser beam comes to the reference rotation position with respect to the workpiece 10.

  When the irradiation position of the laser beam comes to the reference rotation position with respect to the workpiece 10 and the index signal Index is input to the controller 70, the controller 70 determines “Yes” in step S28, and proceeds to step S30. Then, the laser drive circuit 54 is instructed to emit laser light having a processing intensity, and the offset signal generation circuit 62 is instructed to stop outputting the offset signal in step S32. As a result, the laser driving circuit 54 starts to output a processing level L2 driving signal to the laser light source 31 via the feedback control circuit 55, as shown in FIG. The laser light source 31 starts to emit laser light having a processing intensity corresponding to the processing level L2. Therefore, the processing object 10 starts to be irradiated with laser light having a processing intensity, and the surface of the processing object 10 starts to be laser processed. Further, the offset signal generation circuit 62 stops generating the offset signal.

  By switching from the non-processing intensity laser light to the processing intensity laser light, the wavelength of the laser light increases and the focal length of the objective lens 35 increases. In this case, before the switching of the laser beam to the processing intensity, that is, at the time of irradiation of the non-processing intensity laser beam, the focal position of the laser beam is set to an offset position away from the surface of the workpiece 10 by the offset signal. It was set. The distance of the offset position from the surface of the workpiece 10 is set equal to the amount of change in the focal position due to switching from the non-machining intensity laser beam to the machining intensity laser beam. Therefore, immediately after switching to the processing intensity laser light by switching to the processing intensity laser light and stopping the offset signal, the focal position of the laser light by the objective lens 35 is accurately on the surface of the processing object 10. Focus servo control is performed so that

  In step S30, the controller 70 sends a direct drive signal to the laser drive circuit 54 based on the input designation of grooving or pit machining and, in the case of pit machining, the pit interval in the rotation direction. Instructs the generation of a pulsed drive signal having a generated or calculated pulse width. Therefore, when generation of a DC drive signal is instructed, the laser drive circuit 54 sends a DC drive signal having a processing level L2 as shown in FIG. The laser beam is output to the laser light source 31 so that the laser light source 31 continuously emits laser light having a processing intensity. When generation of a pulsed drive signal is instructed, the laser drive circuit 54 sends a pulsed drive signal having a processing level L2 as shown in FIG. The laser beam is output to the laser light source 31 so that the laser light source 31 emits laser light having a processing intensity discontinuously.

  Further, both of the driving signals of these processing levels L2 have a portion A that is transiently higher than the steady processing level L2 for a predetermined short time immediately after switching to the processing intensity laser beam. The light source 31 also emits laser light whose laser intensity has been increased transiently. This is because when the laser beam having the processing intensity is continuously applied to the surface of the workpiece 10, the laser processing spot on the surface of the workpiece 10 is heated immediately before the temperature of the machining spot is relatively low. Since it is high, the workpiece 10 is laser processed satisfactorily. However, immediately after switching to the laser beam with the processing intensity, the laser beam intensity of the immediately preceding non-processing intensity is low, so that the laser processing spot on the surface of the workpiece 10 is not heated so much and the same processing spot Is low, and the workpiece 10 is not laser processed satisfactorily. On the other hand, as described above, in the present embodiment, the portion A that is transiently higher than the steady processing level L2 is provided for a predetermined short time immediately after switching to the processing intensity laser beam. Therefore, even when the laser processing portion on the surface of the processing object 10 is not heated so much immediately before, the processing object 10 is laser processed satisfactorily. Further, if the amount of offset of the focal position by the offset signal is made equal to the amount of change of the focal length due to the intensity difference from the non-processing level L1 to the peak value of the processing level L2, the change of the focal position of the laser beam is reduced. The effect can be effectively eliminated.

  After the start of such laser processing, the controller 70 waits for the input of the index signal Index from the encoder 22b in step S34, as in step S28. When the irradiation position of the laser beam comes to the reference rotation position with respect to the workpiece 10 and the index signal Index is input to the controller 70, the controller 70 determines “Yes” in step S34, and proceeds to step S36. Thus, the laser drive circuit 54 is instructed to emit laser light having non-processing intensity. As a result, the laser drive circuit 54 stops generating the drive signal of the high machining level L2, and again starts to output the drive signal of the low non-machining level L1 to the laser light source 31 via the feedback control circuit 55. Therefore, the laser light source 31 again starts emitting laser light having non-processing intensity to the workpiece 10. As a result, laser processing for one round at one radial position is completed.

  After the process of step S36, the controller 70 adds “1” to the variable n in step S38. Next, in step S40, the controller 70 adds n · P to the laser processing start radius position using the input laser processing start radius position and the processing pitch P in the radial direction, and the laser processing ends. A radius position (laser processing start radius position + n · P) that is one outside the calculated radius position is calculated. Then, it is determined whether or not the radius position (laser machining start radius position + n · P) is larger than the input laser machining end radius position. If it is not larger than the laser processing end radius position, the controller 70 determines “No” in step S40 and proceeds to steps S42 and S44.

  In step S42, the controller 70 outputs the new radial position (laser machining start radial position + n · P) to the feed motor control circuit 53 and moves the irradiation position of the laser beam to the new radial position. To instruct. The feed motor control circuit 53 feeds the laser beam until the irradiation position of the laser beam coincides with the new radius position (laser processing start radius position + n · P) while inputting the radius position detected by the radius position detection circuit 52. The rotation of the motor 23 is controlled to move the table 21 in the radial direction. Thereby, the irradiation position of the laser beam moves to the new radius position (laser processing start radius position + n · P). Next, in step S44, the controller 70 calculates the rotational speed of the spindle motor 22 using the new radial position (laser processing start radial position + n · P) and the determined rotational linear velocity, The calculated rotation speed is output to the spindle motor control circuit 51. The spindle motor control circuit 51 rotates the spindle motor 22 at the input rotation speed as described in the processing of step S16.

  After the processing of step S44, the controller 70 performs laser processing on the new radius position (laser processing start radius position + n · P) of the processing target object 10 through steps S22 to S36 described above. Then, the controller 70 again adds “1” to the variable n in step S38, and a radial position (laser machining start radius position + n · P) that is one outside the radius position where the laser machining is completed in step S40. ) And a determination is made as to whether or not the radius position (laser machining start radius position + n · P) is greater than the input laser machining end radius position. If it is not larger than the laser processing end radius position, the controller 70 makes a “No” determination at step S40 to proceed to steps S42 and S44, and again executes the processes of steps S22 to S40 described above. When the new radial position (laser machining start radius position + n · P) becomes larger than the laser machining end radius position by the circulation process including steps S22 to S44, the controller 70 determines “Yes” in step S40. Determine and proceed to step S46.

  In step S46, the controller 70 instructs the focus servo circuit 58 to stop the operation, and stops the focus servo control by the focus servo circuit 58. Next, in step S <b> 48, the controller 70 instructs the laser drive circuit 54 to stop emitting laser light, and stops emitting laser light from the laser light source 31. Next, in step S50, the controller 70 instructs the spindle motor control circuit 51 to stop the rotation of the spindle motor 22, and stops the rotation of the spindle motor 22. Thereafter, the controller 70 ends the execution of the laser processing program in step S52. As a result, the workpiece 10 is laser machined at every inputted radial machining pitch P from the inputted laser machining start radius position to the laser machining end radius position.

  When laser processing the new workpiece 10 in the same manner as described above, the operator places the new workpiece 10 on the table 21 and fixes it to the table 21, and performs the laser processing shown in FIG. Start the program again. Thereby, the new workpiece 10 is laser-processed similarly to the above.

  According to the above embodiment, before the workpiece 10 is laser-processed, the surface of the workpiece 10 is irradiated with laser light having a non-machining intensity by the process of step S18, and the objective is obtained by the process of step S22. The focal position of the laser beam by the lens 35 is offset. At the start of laser processing, laser light having a processing intensity is irradiated on the surface of the workpiece 10 by the process of step S30, and the offset of the focal position of the laser light by the objective lens 35 is canceled by the process of step S32. I made it. With this offset cancellation, even if the wavelength of the laser beam changes due to the change in the intensity of the laser beam emitted from the laser light source 31, and the focal length changes, the laser beam with the non-processing intensity changes to the laser beam with the processing intensity. Immediately after the switching, the focal position of the laser beam by the objective lens 35 exactly coincides with the surface of the workpiece 10, and a laser processing trace is formed satisfactorily.

  Further, the drive signal output from the laser drive circuit 54 in the process of step S30 is a portion that is transiently higher than the steady processing level L1 for a predetermined short time immediately after switching to the processing intensity laser light. A. Since the laser light source 31 emits laser light having an intensity corresponding to the level of the drive signal, immediately after switching to the laser light having the processing intensity, the temperature of the laser processing portion on the surface of the processing object 10 is increased. The rise is greater. As a result, immediately before the processing intensity is switched to the laser beam, even if the temperature of the laser processing portion on the surface of the processing target 10 is not sufficiently increased, the temperature rise due to the portion A having the high processing level L2 The processing object 10 can be laser processed satisfactorily.

  As mentioned above, although embodiment of this invention was described in detail, in implementing this invention, it is not limited to the said embodiment, A various deformation | transformation is possible unless it deviates from the objective of this invention.

  For example, in the above-described embodiment, the laser beam intensity at the start of laser processing (when switching from non-processing intensity to processing intensity) is made transiently higher than the laser beam intensity thereafter. However, instead of or together with this, the position immediately before the irradiation point of the processing intensity laser beam is irradiated with the preheating laser beam, and the irradiation intensity of the preheating laser beam is irradiated before and after the start of laser processing. It is possible to make the temperature rise before irradiation of the laser irradiation point at the start of laser processing to be the same as that after that by increasing the intensity. Hereinafter, a laser processing apparatus according to this modification will be described with reference to the drawings.

  FIG. 6 shows an overall schematic view of a laser processing apparatus according to this modification. In this laser processing apparatus, in addition to the laser processing apparatus according to the above embodiment, a laser light source 44 for remaining heat is provided in the processing head 30, and a laser drive circuit 63 and a feedback control for driving the laser light source 44 are provided. A circuit 64 is provided. The laser light source 44 emits laser light having a wavelength different from that of the laser light source 31 for processing. The laser light emitted from the laser light source 44 passes through a collimating lens 45 and a polarization beam splitter 46, and is then dichroic mirror 47. Is incident on. The dichroic mirror 47 is provided between the polarizing beam splitter 33 and the ¼ wavelength plate 34 of the above embodiment, and reflects the laser light from the laser light source 31 and the reflected light from the surface of the workpiece 10 by the laser light. While allowing the light to pass, the laser light from the laser light source 44 and the reflected light from the surface of the workpiece 10 due to the laser light are reflected. Laser light incident from the laser light source 44 via the collimator lens 45 and the polarization beam splitter 46 is reflected by the dichroic mirror 47 and collected on the surface of the workpiece 10 via the quarter-wave plate 34 and the objective lens 35. To be lighted. In this case, the optical axis of the laser light from the laser light source 44 is slightly inclined with respect to the optical axis of the laser light from the laser light source 31 in the direction opposite to the rotation direction of the workpiece 10. Is condensed at a position slightly away from the laser light irradiation position of the laser light source 31 in the direction opposite to the rotation direction of the workpiece 10.

  The reflected light reflected by the dichroic mirror 47 enters the polarization beam splitter 46, is reflected by the polarization beam splitter 46, and enters the condenser lens 48. The condensing lens 48 condenses the light reflected by the polarization beam splitter 46 on the light receiving element 49. The light receiving element 49 detects the intensity of the laser light reflected by the polarization beam splitter 46, and supplies a signal representing the intensity of the laser light emitted from the laser light source 44 to the feedback control circuit 64 as a feedback signal. As indicated by S1 in FIG. 7, the laser drive circuit 63 is constantly kept at the predetermined level L3 in the drive state, and the predetermined level L3 is given by the controller 70 at the processing start instruction timing T1. A drive signal that is raised from the level L3 by a predetermined level and then gradually attenuates and returns to the predetermined level L3 is output to the feedback control circuit 64. The feedback control circuit 64 drives and controls the laser light source 44 so as to emit laser light having an intensity corresponding to the drive signal.

  The laser processing apparatus according to this modification includes a delay circuit 65 between the laser drive circuit 54 and the controller 70 of the above embodiment. The delay circuit 65 delays the instruction to start laser irradiation of the non-processing intensity and the processing intensity supplied from the controller 70 by the delay time set by the controller 70 and outputs the delayed instruction to the laser driving circuit 54. In this case, the laser drive circuit 54 responds to the instruction to start laser irradiation with non-processing intensity from the controller 70 delayed by the delay circuit 65, as shown by S2 in FIG. A drive signal composed of a DC signal of level L1 is output. Further, the laser drive circuit 54 responds to the instruction to start laser irradiation of the processing intensity from the controller 70 delayed by the delay circuit 65, as shown by the solid line S2 in FIG. A drive signal of level (that is, machining level) L2 is output. Since the other hardware configurations are the same as those in the above embodiment, the same reference numerals as those in the above embodiment are given and the description thereof is omitted.

  Next, the operation of the modified example configured as described above will be described. The controller 70 executes a laser processing program that is substantially the same as the laser processing program shown in FIG. Further, the difference from the above embodiment is that when the operator inputs the rotational linear velocity of the laser beam spot with respect to the workpiece 10, the delay time ΔT of the delay circuit 65 is set using the input rotational linear velocity. The point is to calculate and output to the delay circuit 65. In the calculation of the delay time ΔT, the laser irradiation position on the surface of the processing object 10 by the preheating laser light source 44 and the laser irradiation position on the surface of the processing object 10 by the processing laser light source 31 are preliminarily determined. The delay time ΔT is calculated by dividing the set interval by the rotational linear velocity. The delay circuit 65 stores the delay time ΔT supplied from the controller 70, and sets the delay time for instructing the start of laser irradiation of the non-processing intensity and the processing intensity.

  Then, the operator places the workpiece 10 on the table 21 and fixes it to the table 21 to start execution of the laser machining program. In the laser processing program according to this modified example, the instruction to start laser irradiation with non-processing intensity in steps S18 and S36 of FIG. 2 and the instruction to start laser irradiation with processing intensity in step S30 are output to the delay circuit 65. . The delay circuit 65 gives an instruction to start laser irradiation of the non-processing intensity and the processing intensity with a predetermined interval between the laser irradiation position by the preheating laser light source 44 and the laser irradiation position by the processing laser light source 31. Output to the laser drive circuit 54 with a delay of ΔT. Therefore, as shown in FIG. 7, at a timing T2 specified by the controller 70, which is delayed by the delay time ΔT with respect to the switching timing T1 from the non-processing intensity laser beam to the processing intensity laser beam. The laser intensity of the processing laser light source 31 is switched from the non-processing level L1 to the processing level L2.

  Further, in the laser machining program according to this modification, in addition to the instruction output for starting the laser irradiation of the non-machining intensity to the delay circuit 65 as shown in parentheses in step S18 of FIG. Is activated. Thus, the laser driving circuit 63 starts to generate laser light having an intensity corresponding to the predetermined level L3 in cooperation with the light receiving element 49 and the feedback control circuit 64. Further, as shown in parentheses in step S30 of FIG. 2, in addition to the instruction output for starting the laser irradiation of the processing intensity to the delay circuit 65, a level-up instruction signal is output to the laser driving circuit 63. In response to this, the laser drive circuit 63 increases the drive signal of the predetermined level L3 by a predetermined level at the processing start instruction timing T1, and then gradually attenuates and returns to the predetermined level L3. In response to this drive signal, the laser light source 44 for remaining heat emits a laser beam having a transiently rising intensity at the processing start instruction timing T1. Further, in step S48 of FIG. 2, an instruction to stop the emission of the laser light source 44 for preheating is also output to the laser drive circuit 63. In addition to stopping the emission of the laser light from the laser light source 31 for processing, the laser for preheating is used. The emission of laser light from the light source 44 is also controlled to stop. Since the intensity of the laser beam from the preheating laser light source 44 is automatically returned to the predetermined level L3 after the processing start instruction timing T1, in step S36 in FIG. Control by is not done.

  In the laser processing apparatus according to the modification as described above, the position in front of the laser light irradiation point by the processing laser light source 31 is the laser by the preheating laser light source 44 by the processing in parentheses in step S18 of FIG. Temperature rises due to light irradiation. Further, by the process in parentheses in step S30 of FIG. 2, the irradiation intensity of the laser light from the laser light source 44 for residual heat is transiently controlled to be higher than the irradiation intensity before and after the start of laser processing. . Therefore, the temperature of the laser processing location on the surface of the processing object 10 rises to the same extent as before even immediately before switching to the processing intensity laser light by the processing laser light source 31. As a result, the workpiece 10 is laser processed satisfactorily.

  Also in the laser machining apparatus according to the modified example, as indicated by a broken line in S2 of FIG. 7, the laser drive circuit 54 has a drive having a portion A ′ whose level is transiently increased at the timing T2, that is, when machining is started. The emission intensity of the laser light source 31 may be controlled by the signal. However, in this case, the rising level of the portion A ′ is smaller than that of the portion A (see FIG. 3) of the above embodiment. According to this, due to the increase in the intensity of the laser beam by the laser light source 31 corresponding to the portion A ′, the temperature of the laser processing portion on the surface of the processing object 10 at the start of processing sufficiently increases. As a result, even if the temperature of the laser processing portion on the surface of the processing object 10 is not sufficiently increased by the laser light from the preheating laser light source 44 at the start of the processing, the processing object 10 can be lasered satisfactorily. Processed.

  In the above-described embodiment and its modifications, the processing head 30 that condenses the laser light with the single objective lens 35 is used. In this case, since the focal length becomes longer as the wavelength of the laser beam becomes longer, the offset signal is superimposed on the focus servo signal so that the focal position moves away from the surface of the workpiece 10 toward the objective lens 30 side. However, instead of this, a processing head for condensing laser light using a plurality of lenses may be used. In this case, since the focal length may be shortened when the wavelength of the laser beam is increased, the sign and level of the offset signal are adjusted in accordance with the change of the focal length when the wavelength of the laser beam is increased. Should be set.

Further, in the above-described embodiment and its modification, the processing laser beam is switched from the non-processing intensity to the processing intensity at the same time as the rotation reference position is detected, and the processing intensity is switched from the processing intensity to the non-processing intensity. However, instead of this, switching from the non-processing intensity of the processing laser beam to the processing intensity is performed simultaneously with the detection of the rotation reference position, and the switching from the processing intensity to the non-processing intensity is performed. It may be performed after a short time has elapsed since the detection of the reference position. According to this, there is no unprocessed portion between the laser processing start point and the laser processing end point. In order to switch from the processing strength to the non-processing strength after a short time has elapsed since the rotation reference position was detected, a delay circuit may be used. In addition, counting of the number of pulses of the A phase signal φ _A or the B phase signal φ _B is started after the index signal Index is input, and when the count value is slightly larger than the count value corresponding to one rotation, It may be detected as a reference position.

  Moreover, in the said embodiment and its modification, this invention is applied to the laser processing apparatus and laser processing method which fix the process target object 10 to the table 21 comprised with the flat plate, rotate the table 21, and irradiate a laser beam. did. However, instead of this, a workpiece is fixed to the outer peripheral surface of a drum-shaped (ie, cylindrical) fixing jig (the set portion of the present invention), and the drum-shaped fixing jig is rotated about its axis. The present invention can also be applied to a laser processing apparatus and a laser processing method for irradiating a laser beam to form a plurality of circular processing marks at predetermined intervals in the rotation axis direction of the fixing jig.

  Further, in the above-described embodiment and its modification, the present invention relates to a laser processing apparatus and a laser processing method for forming concentric laser processing traces having the same laser processing start point and laser processing end point for each different radial position. Applied. However, instead of this, the present invention can also be applied to a laser processing apparatus and a laser processing method for forming a spiral laser processing trace by moving a laser beam spirally with respect to a processing object. In this case, there is only one laser processing start point, but the present invention can also be applied to this laser processing start point.

  Further, in the above embodiment, the processing head 30 is moved in the radial direction with respect to the processing target 10 by moving the table 21 in the radial direction by the feed motor 23. However, the machining head 30 may be moved in the radial direction relative to the table 21. Therefore, instead of the table 21, the machining head 30 may be driven by a motor and moved in the radial direction with respect to the table 21.

It is the schematic which shows the whole laser processing apparatus concerning one Embodiment of this invention. It is a flowchart which shows the laser processing program performed by the controller of FIG. It is a time chart which shows the change of the level of the drive signal output from a laser drive circuit, and the intensity | strength of the laser beam radiate | emitted from a laser light source. It is a time chart of an offset signal. It is a figure for demonstrating the change of the focus position of the laser beam in a non-processing state and a processing state. It is the schematic which shows the whole laser processing apparatus concerning the modification of the said embodiment. It is a time chart which shows the intensity | strength change of the laser beam radiate | emitted from the laser light source for process which concerns on the said modification, and a residual heat. It is a top view of the processing object for demonstrating the example of the circular laser processing formed in a processing object. It is a figure which shows the laser processing trace by a conventional apparatus. It is a graph which shows the relationship between the intensity | strength of a laser beam, and a wavelength. It is a figure for demonstrating the change of the focus position of the laser beam in the non-processing state by a conventional apparatus, and a processing state. It is a signal waveform diagram which shows the time change of the focus error signal by the conventional apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Processing object, 21 ... Table, 22 ... Spindle motor, 23 ... Feed motor, 30 ... Processing head, 31, 44 ... Laser light source, 51 ... Spindle motor control circuit, 52 ... Radial position detection circuit, 53 ... Feed motor Control circuit, 54, 63 ... laser drive circuit, 55, 64 ... feedback control circuit, 58 ... focus servo circuit, 61 ... adder, 62 ... offset signal generation circuit, 70 ... controller

Claims (6)

A set part for setting a workpiece;
Rotating means for rotating the set unit;
A processing laser light source that emits laser light for laser processing the surface of a workpiece, an objective lens that condenses the emitted laser light, and a focus actuator that drives the objective lens in the optical axis direction of the laser light A processing head including:
A focus servo control circuit that drives and controls the focus actuator by supplying a focus servo signal based on reflected light from the surface of the workpiece to the focus actuator and maintains the focal position of the laser beam on the surface of the workpiece When,
Moving means for moving the irradiation position of the laser beam on the surface of the workpiece;
A processing laser drive circuit that outputs a drive signal to the processing laser light source and emits laser light having an intensity corresponding to the level of the drive signal to the processing laser light source;
The moving means is controlled to move the irradiation position of the laser beam to the laser processing start position, and the processing laser drive circuit is controlled to control the processing target surface so that the surface of the workpiece is not laser processed. After the laser beam is emitted from the processing laser light source and the focus servo control circuit is operated, the processing laser drive circuit is controlled to have a strength greater than that of the non-processing laser light. A laser processing apparatus that emits the laser beam from the processing laser light source, and laser-processes the surface of the processing object set in the set unit from the laser processing start position.
Generating an offset signal of a level corresponding to a change from a focal length of the objective lens at the time of incidence of the non-machining laser light to a focal length of the objective lens at the time of incidence of the machining laser light; An offset signal generation circuit for superimposing the focus servo signal is provided,
When the non-processing laser light is emitted from the processing laser light source, the control means generates an offset signal in the offset signal generation circuit so that the focal position of the laser light is determined from the surface of the processing object. It is shifted by a distance corresponding to the amount of change, and at the time of switching from the emission of the non-processing laser beam to the emission of the processing laser beam, the offset signal generation circuit stops generating the offset signal, and A laser processing apparatus characterized in that a focal position of laser light is made to coincide with a surface of an object to be processed. The laser processing apparatus according to claim 1, further comprising:
Providing a reference position detecting means for detecting a reference position of rotation by the rotating means;
The control means switches and controls the processing laser drive circuit when detecting the reference position, and changes the laser light emitted from the processing laser light source from the non-processing laser light to the processing laser light. Or switching from the processing laser light to the non-processing laser light, and the control means is the moving means only when the non-processing laser light is emitted from the processing laser light source. Is controlled to move the irradiation position of the laser beam to the laser processing start position. The laser processing apparatus according to claim 1 or 2,
The processing laser drive circuit transiently increases the level of the drive signal when switching from the emission of the non-processing laser light to the emission of the processing laser light, and then returns to a predetermined level. A laser processing apparatus characterized by being configured as described above. In the laser processing apparatus according to any one of claims 1 to 3,
In the direction in which the laser beam from the processing laser light source moves in the processing head, the surface of the object to be processed in front of the laser beam irradiation position by the processing laser light source is irradiated with the preheating laser beam. Further providing a preheating laser light source,
Switching from the emission of the non-machining laser beam to the machining laser beam to the machining laser drive circuit by the control means is performed by changing the irradiation position of the preheating laser beam and the machining laser beam. A delay circuit that delays by the moving time of the irradiation position of the laser beam by the laser light source for processing corresponding to the distance to the irradiation position of
A drive signal for driving the preheating laser light source, which rises transiently when the control means switches from emitting the non-machining laser beam to emitting the machining laser beam; A preheating laser drive circuit is provided that outputs a driving signal at a predetermined level to the preheating laser light source, and emits laser light having an intensity corresponding to the driving signal to the preheating laser light source. Laser processing equipment. A set part for setting a workpiece;
Rotating means for rotating the set unit;
A processing laser light source that emits laser light for laser processing the surface of a workpiece, an objective lens that condenses the emitted laser light, and a focus actuator that drives the objective lens in the optical axis direction of the laser light A processing head including:
A focus servo control circuit that drives and controls the focus actuator by supplying a focus servo signal based on reflected light from the surface of the workpiece to the focus actuator and maintains the focal position of the laser beam on the surface of the workpiece When,
Applied to a laser processing apparatus comprising a moving means for moving the irradiation position of the laser beam on the surface of the workpiece;
A moving step of controlling the moving means to move the irradiation position of the laser beam to a laser processing start position;
A non-machining laser that emits non-machining laser light from the machining laser light source so that the surface of the machining target is not laser-processed so that the non-machining laser light is emitted from the machining laser light source. A light irradiation process;
After the non-processing laser light irradiation step, a processing laser light having an intensity greater than the intensity of the non-processing laser light is emitted from the processing laser light source, and is applied to the surface of the processing object. A laser processing method for performing laser processing on a surface of a processing target set in the set portion, including a processing laser light irradiation step for irradiating laser light,
When the non-machining laser light is irradiated onto the surface of the workpiece by the non-machining laser light irradiation step, the focus actuator is offset controlled in addition to the focus servo control by the focus servo control circuit, and the non-processing laser light is irradiated. The focal position of the laser beam is processed by a distance corresponding to the change from the focal length of the objective lens when the processing laser beam is incident to the focal length of the objective lens when the processing laser beam is incident. An offset process for shifting from the surface of the object;
When switching from the non-processing laser light irradiation to the processing laser light irradiation in the processing laser light irradiation step, the offset control for the focus actuator is canceled and the focal position of the laser light is processed. A laser processing method comprising: an offset canceling step for matching with a surface of an object. In the laser processing method of Claim 5,
When switching from the irradiation of the non-processing laser beam to the irradiation of the processing laser beam in the processing laser irradiation step, the intensity of the processing laser beam is transiently increased, and then a predetermined level. The laser processing method is characterized in that it is restored to the strength of.

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